0000906709-23-000004 | 10-K | XBRL Viewer

Liabilities Related to the Sales of Future Royalties

12 Months Ended

Dec. 31, 2022

On February 24, 2012, we entered into a purchase and sale agreement (the 2012 Purchase and Sale Agreement) with RPI Finance Trust (RPI), an affiliate of Royalty Pharma, pursuant to which we sold, and RPI purchased, our right to receive royalty payments (the 2012 Transaction Royalties) arising from the worldwide net sales, from and after January 1, 2012, of (a) CIMZIA®, under our license, manufacturing and supply agreement with UCB Pharma (UCB), and (b) MIRCERA®, under our license, manufacturing and supply agreement with F. Hoffmann-La Roche Ltd and Hoffmann-La Roche Inc. (together referred to as Roche). We received aggregate cash proceeds of $124.0 million for the 2012 Transaction Royalties. Although we sold all of our rights to receive royalties from the CIMZIA® and MIRCERA® products, as a result of our ongoing manufacturing and supply obligations related to the generation of these royalties, we continue to account for these royalties as revenue. We recorded the $124.0 million in proceeds from this transaction as a liability (the 2012 Royalty Obligation) that is amortized using the effective interest method over the estimated life of the 2012 Purchase and Sale Agreement as royalties from the CIMZIA® and MIRCERA® products are remitted directly to RPI. As of December 31, 2022, our prospective effective interest rate used to amortize the liability is 10%.

On June 5, 2020, UCB served notice of a Declaratory Judgment of Patent Invalidity, filed in the United States District Court for the District of Delaware, seeking a declaration of invalidity of certain of our patents that we had licensed to UCB and pursued similar actions in other jurisdictions. On October 14, 2021, RPI and we entered into a Letter Agreement which permitted us to enter into a Settlement Agreement, effective October 13, 2021, with UCB to effect the negotiation between RPI and UCB in which UCB and RPI agreed to a reduction in the royalty term and annual decreases in the royalty rate over the remaining royalty term in exchange for UCB’s withdrawal of all of UCB’s litigation and challenges.

We concluded that we should account for the decrease in royalty payments to RPI as a result of these agreements as a modification of our liability. Due to the significance of the change in the estimated royalty payments, we concluded that we should treat the modification as an extinguishment of the prior liability and recognize a new liability based on the revised royalty payments and term, discounted to fair value. Accordingly, we estimated the fair value to be approximately $84.7 million, reflecting a discount rate of 16.0%. As a result, we recognized a loss of $23.5 million on the revaluation of the prior liability in the three months ended December 31, 2021, and we wrote off the remaining $0.9 million of unamortized

transaction costs. We present these charges in Loss on revaluation of liability related to the sale of future royalties line in our Consolidated Statement of Operations.

On December 16, 2020, we entered into a purchase and sale agreement (the 2020 Purchase and Sale Agreement) with entities managed by Healthcare Royalty Management, LLC (collectively, HCR). Pursuant to the 2020 Purchase and Sale Agreement, we agreed to sell to HCR certain of our rights to receive royalty payments (the 2020 Transaction Royalties) arising from the worldwide net sales, from and after October 1, 2020 until such time that certain return thresholds are met as described below, of (a) MOVANTIK® under that certain License Agreement, dated September 20, 2009, by and between Nektar and AstraZeneca AB, as amended, (b) ADYNOVATE® under that certain Exclusive Research, Development, License and Manufacturing and Supply Agreement, dated September 26, 2005, by and among Nektar, Baxalta US Inc. and Baxalta GmbH, as amended, (c) REBINYN® under that certain Settlement and License Agreement, dated December 21, 2016, by and among Nektar, Novo Nordisk Inc., Novo Nordisk A/S and Novo Nordisk A/G and (d) licensed products under that certain Right to Sublicense Agreement, dated October 27, 2017, by and among Nektar, Baxalta Incorporated, Baxalta US Inc. and Baxalta GmbH.

The 2020 Purchase and Sale Agreement will automatically expire, and the payment of the 2020 Transaction Royalties to HCR will cease, when HCR has received payments of the 2020 Transaction Royalties equal to $210.0 million (the 2025 Threshold), if the 2025 Threshold is achieved on or prior to December 31, 2025, or $240.0 million, if the 2025 Threshold is not achieved on or prior to December 31, 2025 (or, if earlier, the date on which the last royalty payment under the relevant license agreements is made). If HCR has received payments of the 2020 Transaction Royalties equal to at least $208.0 million on or prior to December 31, 2025, we have the option to pay the difference between the 2025 Threshold and such 2020 Transaction Royalties, and the 2025 Threshold will be met and the 2020 Purchase and Sale Agreement will expire. After the 2020 Purchase and Sale Agreement expires, all rights to receive the 2020 Transaction Royalties return to Nektar.

On December 30, 2020, we received aggregate cash proceeds of $150.0 million for the 2020 Transaction Royalties. As part of the sale, we incurred approximately $3.8 million in transaction costs, which will be amortized to interest expense over the estimated life of the 2020 Purchase and Sale Agreement. Although we sold all of our rights to receive royalties from these products up to the cap, as a result of the limits on the 2020 Transaction Royalties to be received by HCR and our ongoing manufacturing and supply obligations related to the generation of these royalties, we will continue to account for these non-cash royalties as revenue, commencing with royalties for the three months ended December 31, 2020, to be received by HCR in the first quarter of 2021. We recorded the $150.0 million in proceeds from this transaction as a liability (the 2020 Royalty Obligation) that will be amortized using the effective interest method over the estimated life of the 2020 Purchase and Sale Agreement. As of December 31, 2022, our prospective effective interest rate used to amortize the liability is 20%.

The following table shows the activity within the liability account of each arrangement (in thousands):


	Year-Ended December 31, 2022						Period from inception to December 31, 2022
	2012 Purchase and Sale Agreement		2020 Purchase and Sale Agreement		Total		2012 Purchase and Sale Agreement		2020 Purchase and Sale Agreement		Total
Liabilities related to the sales of future royalties—beginning balance	$	78,282	$	120,062	$	198,344	$	—	$	—	$	—
Royalty monetization proceeds	—		—		—		124,000		150,000		274,000
Non-cash royalty revenue	(33,865)		(35,929)		(69,794)		(316,523)		(86,722)		(403,245)
Non-cash interest expense	10,750		18,161		28,911		234,168		39,016		273,184
Payments to RPI	—		—		—		(10,000)		—		(10,000)
Loss on revaluation of liability related to the sale of future royalties	—				—		23,522		—		23,522
Liabilities related to the sales of future royalties – ending balance	55,167		102,294		157,461		55,167		102,294		157,461
Less: unamortized transaction costs	—		(2,083)		(2,083)		—		(2,083)		(2,083)
Liabilities related to the sales of future royalties, net	$	55,167	$	100,211	$	155,378	$	55,167	$	100,211	$	155,378

Pursuant to the 2012 Purchase and Sale Agreement, in March 2014 and March 2013, we were required to pay RPI $7.0 million and $3.0 million, respectively, as a result of worldwide net sales of MIRCERA® for the 12 month periods ended

December 31, 2013 and 2012 not reaching certain minimum thresholds. The 2012 Purchase and Sale Agreement does not include any other potential payments related to minimum net sales thresholds and, therefore, we do not expect to make any further payments to RPI related to this agreement.

As royalties are remitted to RPI and HCR by our licensees, the balances of the respective Royalty Obligations will be effectively repaid over the lives of the agreements. To determine the amortization of the Royalty Obligations, we are required to estimate the total amount of future royalty payments to be received by RPI and HCR, respectively. The sum of these amounts less the net proceeds we received will be recorded as non-cash interest expense, as well as the loss on the revaluation described above, over the lives of the respective Royalty Obligations. We periodically assess the estimated royalty payments to RPI and HCR from our licensees and to the extent the amount or timing of such payments is materially different than our original estimates, we will prospectively adjust the imputed interest rate and the related amortization of the appropriate Royalty Obligation.

There are a number of factors that could materially affect the amount and timing of royalty payments from our licensees, most of which are not within our control. Such factors include, but are not limited to, changing standards of care, the introduction of competing products, manufacturing or other delays, biosimilar competition, intellectual property matters, adverse events that result in governmental health authority imposed restrictions on the use of the drug products, significant changes in foreign exchange rates as the royalties remitted to RPI or HCR are made in U.S. dollars (USD) while significant portions of the underlying sales of the products of our licensees are made in currencies other than USD, and other events or circumstances that could result in reduced royalty payments from our licensees, all of which would result in a reduction of non-cash royalty revenues and the non-cash interest expense over the life of the respective Royalty Obligation. Conversely, for the 2012 Purchase and Sale Agreement, if sales of these products are more than expected, the non-cash royalty revenues and the non-cash interest expense recorded by us would be greater over the term of the 2012 Royalty Obligation.

Cash and Investments in Marketable Securities (Tables)

12 Months Ended

Dec. 31, 2022

Cash and Cash Equivalents [Abstract]

Schedule of Cash and Investments in Marketable Securities, Including Cash Equivalents

Cash and investments in marketable securities, including cash equivalents, are as follows (in thousands):


	Estimated Fair Value at
	December 31, 2022		December 31, 2021
Cash and cash equivalents	$	88,227	$	25,218
Short-term investments	416,750		708,737
Long-term investments	—		64,828
Total cash and investments in marketable securities	$	504,977	$	798,783

Schedule of Portfolio of Cash and Investments in Marketable Securities

Our portfolio of cash and investments in marketable securities includes (in thousands):


	Fair Value Hierarchy Level	December 31, 2022								December 31, 2021
		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value		Fair Value
Corporate notes and bonds	2	$	84,377	$	—	$	(855)	$	83,522	$	278,121
Corporate commercial paper	2	345,125		25		(946)		344,204		478,629
Obligations of U.S. government agencies	2	—		—		—		—		5,875
Available-for-sale investments		429,502		25		(1,801)		427,726		762,625
Money market funds	1							47,054		23,968
Certificates of deposit	2							21,399		10,940
Cash	N/A							8,798		1,250
Total cash and investments in marketable securities								$	504,977	$	798,783

Co-Development Agreement with SFJ Pharmaceuticals and Development Derivative Liability

12 Months Ended

Dec. 31, 2022

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Co-Development Agreement with SFJ Pharmaceuticals and Development Derivative Liability

On February 12, 2021, we entered into a Co-Development Agreement (the SFJ Agreement) with SFJ Pharmaceuticals XII, L.P., a SFJ Pharmaceuticals Group company (SFJ), pursuant to which SFJ would pay up to $150.0 million in committed funding to support a Phase 2/3 study of bempegaldesleukin in combination with Keytruda® (pembrolizumab) for first-line treatment of patients with metastatic or unresectable recurrent squamous cell carcinoma of the head and neck (the SCCHN Clinical Trial) whose tumors express PD-L1 (the SCCHN Indication). SFJ has primary responsibility for the clinical trial management of the SCCHN Clinical Trial, and we are the sponsor of the SCCHN Clinical Trial. The SFJ Agreement provided for us to pay up to $637.5 million in Success Payments in the event of FDA approval of bempegaldesleukin for the metastatic melanoma, the SCCHN Indication, or both, and in the event of FDA approval of one additional bempegaldesleukin indication.

We presented the SFJ Agreement as a Development derivative liability in our Consolidated Balance Sheets, which we remeasured to fair value at each reporting date. As SFJ conducted the SCCHN Clinical Trial, we recorded non-cash research and development expense with a corresponding increase to the development derivative liability, and as SFJ remitted funding to us to support our internal costs of conducting the trial, we also recorded a corresponding increase to the development derivative liability. We presented the gain (loss) from the remeasurement as change in fair value of development derivative liability in our Consolidated Statements of Operations.

The following table presents the changes in the development derivative liability:


		Year Ended December 31,
	Fair Value Hierarchy Level	2022		2021
Fair value as of December 31, 2021 and February 12, 2021 (inception), respectively	3	$	27,726	$	—
Non-cash research and development expense		4,951		16,703
Cash receipts from SFJ		750		3,000
Change in the fair value of development derivative liability		(33,427)		8,023
Fair value at end of period	3	$	—	$	27,726

As of December 31, 2021, we valued the derivative using a scenario-based discounted cash flow method, whereby each scenario makes assumptions about the probability and timing of cash flows, and we discount such cash flows to present value using a risk-adjusted rate. The key inputs to the valuation included our estimates of the following: (i) the probability of the bempegaldesleukin trials meeting their primary endpoints, and if successful, the probability and timing of achieving FDA approval, (ii) the timing and the amount of costs incurred by SFJ for the SCCHN Clinical Trial, including the probability of early termination of the study based on an interim futility analysis, and (iii) each party’s cost of borrowing.

As of March 31, 2022, due to the negative results of the metastatic melanoma trial and initial discussions with SFJ, we concluded that it was remote that SFJ and we would continue the SCCHN Clinical Trial. Accordingly, the fair value of the development derivative liability was reduced to zero as of March 31, 2022, and we recognized a corresponding gain in the Change in fair value of development derivative liability. As discussed in Note 1, on April 14, 2022, BMS and we decided to end the development for bempegaldesleukin in combination with Opdivo® and that all other ongoing studies in the bempegaldesleukin program would be discontinued. We also announced that SFJ and we agreed to discontinue the SCCHN Clinical Trial. Accordingly, SFJ will not be entitled to any Success Payments, and SFJ has the responsibility to wind down the SCCHN Clinical Trial at its sole cost. SFJ has no right to seek reimbursement from us for any costs incurred for the SCCHN Clinical Trial.

Cash and Investments in Marketable Securities

12 Months Ended

Dec. 31, 2022

Cash and Cash Equivalents [Abstract]

Cash, Cash Equivalents, and Marketable Securities

Cash and Investments in Marketable Securities Cash and investments in marketable securities, including cash equivalents, are as follows (in thousands):


	Estimated Fair Value at
	December 31, 2022		December 31, 2021
Cash and cash equivalents	$	88,227	$	25,218
Short-term investments	416,750		708,737
Long-term investments	—		64,828
Total cash and investments in marketable securities	$	504,977	$	798,783

We invest in liquid, high quality debt securities. Our investments in debt securities are subject to interest rate risk. To minimize the exposure due to an adverse shift in interest rates, we invest in securities with maturities of two years or less and maintain a weighted average maturity of one year or less. All of our long-term investments as of December 31, 2021 had maturities between one and two years.

During the year ended December 31, 2022 we sold no available-for-sale securities. During the years ended December 31, 2021 and 2020, we sold available-for-sale securities totaling $11.5 million and $41.7 million, respectively. Gross realized gains and losses on those sales were not significant.

We report our accrued interest receivable, which totaled $0.7 million and $1.4 million at December 31, 2022 and December 31, 2021, respectively, in other current assets on our Consolidated Balance Sheets.

Our portfolio of cash and investments in marketable securities includes (in thousands):


	Fair Value Hierarchy Level	December 31, 2022								December 31, 2021
		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value		Fair Value
Corporate notes and bonds	2	$	84,377	$	—	$	(855)	$	83,522	$	278,121
Corporate commercial paper	2	345,125		25		(946)		344,204		478,629
Obligations of U.S. government agencies	2	—		—		—		—		5,875
Available-for-sale investments		429,502		25		(1,801)		427,726		762,625
Money market funds	1							47,054		23,968
Certificates of deposit	2							21,399		10,940
Cash	N/A							8,798		1,250
Total cash and investments in marketable securities								$	504,977	$	798,783

At December 31, 2021, our gross unrealized losses totaled $0.7 million. Our gross unrealized gains were not significant. As of December 31, 2022 and 2021, we assessed our marketable securities with unrealized losses and concluded that the losses were not attributable to credit. Accordingly, we have not recorded an allowance for credit losses for these securities.

At both December 31, 2022 and 2021, we had letter of credit arrangements in favor of our landlords and certain vendors totaling $7.5 million and $8.1 million, respectively. These letters of credit are secured by investments of similar amounts.

Stock-Based Compensation - Schedule of Black-Scholes Option-Pricing Model Assumptions Used to Calculate Fair Value of Employee Stock Options (Details) - $ / shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share-Based Payment Arrangement [Abstract]
Average risk-free interest rate	2.90%	1.20%	0.40%
Dividend yield	0.00%	0.00%	0.00%
Average volatility factor	77.90%	63.80%	64.10%
Weighted-average expected life	5 years 7 months 6 days	5 years 6 months	5 years 7 months 6 days
Weighted-average grant-date fair value of options granted (in dollars per share)	$ 3.18	$ 8.07	$ 10.70

Property, Plant and Equipment

12 Months Ended

Dec. 31, 2022

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment

Property, plant and equipment consists of the following (in thousands):


	December 31,
	2022		2021
Building and leasehold improvements	$	74,889	$	97,385
Laboratory equipment	24,243		42,704
Computer equipment and software	26,205		28,829
Manufacturing equipment	25,052		22,374
Furniture, fixtures, and other	4,263		10,094
Depreciable property, plant and equipment at cost	154,652		201,386
Less: accumulated depreciation	(124,731)		(148,039)
Depreciable property, plant and equipment, net	29,921		53,347
Construction-in-progress	2,530		7,163
Property, plant and equipment, net	$	32,451	$	60,510

Laboratory and manufacturing equipment, including construction-in-process, include assets that support both our manufacturing and research and development activities.

Property, plant and equipment decreased significantly for the year ended December 31, 2022 as a result of our 2022 Restructuring Plan. As further disclosed in Note 11, we sold our research and development facility in India, we sold or disposed of laboratory equipment and certain computer software, and we recognized impairment charges for leasehold improvements and certain furniture and fixtures for spaces we seek to sublease.

Depreciation and amortization expense for property, plant and equipment for the years ended December 31, 2022, 2021, and 2020 was $12.2 million, $13.0 million, and $12.5 million, respectively.

Restructuring, Impairment and Other Costs of Terminated Program - Narrative (Details) $ in Thousands			1 Months Ended	3 Months Ended	7 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2022	May 31, 2022	Apr. 30, 2022	Dec. 31, 2022 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Jun. 30, 2022
Restructuring Cost and Reserve [Line Items]
Impairment of right-of-use assets and property, plant and equipment							$ 65,761	$ 0	$ 0
Book value in excess of fair value					$ 67,875
Third St. Facility
Restructuring Cost and Reserve [Line Items]
Book value in excess of fair value				$ 12,000
Measurement Input, Market Participant Subtenant Borrowing Rate
Restructuring Cost and Reserve [Line Items]
Operating lease, measurement input	7.90%	6.40%
Nektar 214 \| Bristol-Myers Squibb
Restructuring Cost and Reserve [Line Items]
Reimbursement of expenses						$ 20,800
Employee Severance
Restructuring Cost and Reserve [Line Items]
Percent of positions eliminated			70.00%
Entity number of employees			225							735

Inventory (Tables)

12 Months Ended

Dec. 31, 2022

Inventory Disclosure [Abstract]

Schedule of Inventory

Inventory consists of the following (in thousands):


	December 31,
	2022		2021
Raw materials	$	2,575	$	3,166
Work-in-process	10,749		9,342
Finished goods	5,878		3,293
Total inventory	$	19,202	$	15,801

Operating Leases - Schedule of Future Minimum Lease Payments for Operating Leases (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Leases [Abstract]
2023	$ 19,216
2024	21,572
2025	22,254
2026	22,958
2027	23,681
2028 and thereafter	51,732
Total lease payments	161,413
Less: portion representing interest	(29,917)
Operating lease liabilities	131,496
Less: current portion	(18,667)	$ (17,441)
Operating lease liabilities, less current portion	$ 112,829	$ 125,736

Stock-Based Compensation

12 Months Ended

Dec. 31, 2022

Share-Based Payment Arrangement [Abstract]

Stock-Based Compensation

2017 Performance Incentive Plan

Our 2017 Performance Incentive Plan (2017 Plan) provides for the issuance of our common stock to members of the Board of Directors, officers or employees, certain consultants and advisors and our subsidiaries. Our 2017 Plan has been amended and restated such that an aggregate 39,200,000 shares have been authorized for issuance as of December 31, 2022, including 5,000,000 shares that were approved on June 8, 2022. Under the 2017 Plan, we may issue stock options, restricted stock, performance stock, stock units, stock appreciation rights and other similar types of awards. When the 2017 Plan was approved on June 14, 2017, any shares of our common stock that were available for issuance under our 2012 Performance Incentive Plan (the 2012 Plan) ceased to be available for future grants. However, options and RSUs granted under the 2012 Plan remained outstanding, and any options or RSUs that were cancelled or forfeited became available for issuance under the 2017 Plan. Shares issued for RSUs, PSUs or any other “full-value award” are counted against the share limit as 1.5 shares for every one share granted in connection with the award.

We have granted non-qualified stock options, RSUs and PSUs to employees, officers, and non-employee directors. For our employees, the requisite service period is generally four years for stock options, and three years for RSUs and PSUs. For our directors, the requisite service is generally one year for stock options and RSUs. The maximum term of a stock option is eight years from the date of grant. The per share exercise price of an option generally may not be less than the fair market value of a share of our common stock on the NASDAQ Stock Market on the date of grant.

Under our Change in Control Plan (the CIC Plan), in the event of a change of control of Nektar and a subsequent termination of employment initiated by us or a successor company other than for Cause (as defined in the CIC Plan) within twelve months following a change of control, our employees are entitled to full acceleration of their unvested equity awards. Our Chief Executive Officer, Senior Vice Presidents and Vice Presidents (including Principal Fellows) are also entitled to full acceleration of unvested equity awards if the termination is initiated by the employee for a Good Reason Resignation (as

defined in the CIC Plan) within twelve months following a change of control. Additionally, non-employee directors would also be entitled to full acceleration of vesting of all outstanding stock awards in the event of a change of control transaction.

Employee Stock Purchase Plan

Under the terms of our Employee Stock Purchase Plan (ESPP), employees may purchase shares of our common stock based on a percentage of their compensation subject to certain limits. Shares are purchased at 85% of the lower of the closing price on either the first day or last day of each six-month offering period. An aggregate 3,500,000 shares have been authorized for issuance under our ESPP.

Stock-Based Compensation Expense

We recognize total stock-based compensation expense in our Consolidated Statements of Operations as follows (in thousands):


	Year Ended December 31,
	2022		2021		2020
Cost of goods sold	$	2,824	$	2,779	$	2,825
Research and development	27,727		54,821		57,116
General and administrative	24,488		37,074		33,295
Restructuring, impairment and other costs of terminated program	2,281		—		1,025
Total stock-based compensation	$	57,320	$	94,674	$	94,261

Stock-based compensation expense resulting from PSUs and our ESPP was not significant in the years ended December 31, 2022, 2021, and 2020.

As of December 31, 2022, total unrecognized compensation costs of $83.1 million related to unvested stock-based compensation awards are expected to be recognized as expense over a weighted-average period of 2.3 years.

Black-Scholes Assumptions

The following table lists the Black-Scholes option-pricing model assumptions used to calculate the fair value of employee and director stock options, as well as the resulting grant-date fair value:


	Year Ended December 31,
	2022			2021			2020
Average risk-free interest rate	2.9		%	1.2		%	0.4		%
Dividend yield	0.0		%	0.0		%	0.0		%
Average volatility factor	77.9		%	63.8		%	64.1		%
Weighted-average expected life	5.6 years			5.5 years			5.6 years
Weighted-average grant-date fair value of options granted	$	3.18		$	8.07		$	10.70

The average risk-free interest rate is based on the U.S. treasury yield curve in effect at the time of grant for periods commensurate with the expected life of the stock-based award. We have never paid dividends, nor do we expect to pay dividends in the foreseeable future; therefore, we used a dividend yield of zero. Our estimate of expected volatility is based on the daily historical trading data of our common stock at the time of grant over a historical period commensurate with the expected life of the stock-based award. We estimated the weighted-average expected life based on the contractual and vesting terms of the stock options, as well as historical cancellation and exercise data.

Summary of Stock Option Activity

The table below presents a summary of stock option activity under our equity incentive plans (in thousands, except for price per share and contractual life information):


	Number of Shares	Weighted- Average Exercise Price per Share		Weighted- Average Remaining Contractual Life (in Years)	Aggregate Intrinsic Value(1)
Outstanding at December 31, 2021	13,542	$	23.62
Options granted	6,276	4.76
Options exercised	(15)	12.43
Options forfeited & canceled	(5,715)	20.73
Outstanding at December 31, 2022	14,088	$	16.40	5.71	$	—

Exercisable at December 31, 2022	6,029	27.82		3.60	$	—

_______________________________________________________________

(1)Aggregate intrinsic value represents the difference between the exercise price of the option and the closing market price of our common stock on December 31, 2022.

The intrinsic value of options exercised during the year ended December 31, 2022 was not significant and totaled $17.3 million and $15.9 million during the years ended December 31, 2021 and 2020, respectively.

Summary of RSU Activity

A summary of RSU award activity is as follows (in thousands except for per share amounts):


	Units Issued	Weighted- Average Grant Date Fair Value
Unvested at December 31, 2021	9,930	$	16.80
Granted	7,708	4.14
Vested and released	(2,872)	17.64
Forfeited and canceled	(5,454)	15.68
Unvested at December 31, 2022	9,312	$	6.81

The weighted-average grant-date fair values of RSUs granted during the years ended December 31, 2022, 2021 and 2020 were $4.14, $14.68 and $19.24, respectively. The fair value of RSU's that vested in the years ended December 31, 2022, 2021 and 2020 totaled $17.5 million, $45.3 million and $33.3 million, respectively.

401(k) Retirement Plan

We sponsor a 401(k) retirement plan whereby eligible employees may elect to contribute up to the lesser of 60% of their annual compensation or the statutorily prescribed annual limit allowable under Internal Revenue Service regulations. The 401(k) plan permits us to make matching contributions on behalf of all participants, up to a maximum of $12,000 per participant for the year ended December 31, 2022, and up to a maximum of $6,000 per participant for the years ended December 31, 2021 and 2020. For the years ended December 31, 2022, 2021, and 2020, we recognized $2.5 million, $3.6 million and $3.5 million, respectively, of compensation expense in connection with our 401(k) retirement plan.

CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Statement of Comprehensive Income [Abstract]
Net loss	$ (368,198)	$ (523,837)	$ (444,440)
Other comprehensive income (loss):
Net unrealized gain (loss) on available-for-sale investments	(1,114)	(1,568)	(927)
Net foreign currency translation gain (loss)	(1,636)	(294)	(363)
Other comprehensive income (loss)	(2,750)	(1,862)	(1,290)
Comprehensive loss	$ (370,948)	$ (525,699)	$ (445,730)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(22))
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+ Details

- Definition

Amount after tax and reclassification adjustments of other comprehensive income (loss).

+ References

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+ Details

Segment Reporting

12 Months Ended

Dec. 31, 2022

Segment Reporting [Abstract]

Segment Reporting

We operate in one business segment which focuses on applying our technology platforms to develop novel drug candidates. Our business offerings have similar economics and other characteristics, including the nature of products and manufacturing processes, types of customers, distribution methods and regulatory environment. We are comprehensively managed as one business segment by our Chief Executive Officer.

Our revenue is derived primarily from customers in the pharmaceutical and biotechnology industries. Revenue from UCB Pharma, Baxalta / Takeda, AstraZeneca and Pfizer represented 37%, 25%, 14% and 11% of our revenue, respectively, for the year ended December 31, 2022. Revenue from UCB Pharma, Baxalta / Takeda, AstraZeneca and Pfizer represented 36%, 23%, 16% and 13% of our revenue, respectively, for the year ended December 31, 2021. Revenue from BMS, UCB Pharma, Baxalta / Takeda, and AstraZeneca represented 33%, 23%, 14% and 13% of our revenue for the year-ended December 31, 2020.

Revenue by geographic area is based on the headquarters or shipping locations of our partners. The following table sets forth revenue by geographic area (in thousands):


	Year Ended December 31,
	2022		2021		2020
United States	$	9,841	$	10,114	$	64,966
Rest of World	82,214		91,793		87,949
Total revenue	$	92,055	$	101,907	$	152,915

At December 31, 2022, all of our property, plant and equipment was located in the United States. At December 31, 2021, $56.1 million, 93%, of the net book value of our property, plant and equipment was located in the United States with the remainder in India.

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

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+ Details

Operating Leases - Schedule of Lease Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Leases [Abstract]
Operating lease expense	$ 17,057	$ 19,153	$ 18,985
Variable lease expense	10,700	8,974	8,179
Total lease expense	$ 27,757	$ 28,127	$ 27,164

Income Taxes - Schedule of Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Current:
Federal	$ 0	$ 0	$ 0
State	(608)	50	165
Foreign	1,115	609	364
Total current income tax expense	507	659	529
Deferred:
Federal	0	0	0
State	0	0	0
Foreign	2,708	(102)	(36)
Total deferred income tax expense	2,708	(102)	(36)
Provision for income taxes	$ 3,215	$ 557	$ 493

Restructuring, Impairment and Other Costs of Terminated Program (Tables)

12 Months Ended

Dec. 31, 2022

Restructuring and Related Activities [Abstract]

Schedule of Restructuring, Impairment and Other Costs of Terminated Program

Restructuring, impairment and other costs of terminated program includes the following (in thousands):


	Year Ended December 31, 2022
Clinical trial expense, other third-party and employee costs for the wind down of the bempegaldesleukin program	$	31,693
Severance and benefit expense	30,904
Impairment of right-of-use assets and property, plant and equipment	65,761
(Gain) loss on sale or disposal of property, plant and equipment, net	(3,326)
Contract termination and other restructuring costs	10,898
Restructuring, impairment and other costs of terminated program	$	135,930

The following table provides details regarding the severance and other termination benefit expense. We present the liability, which we paid in January 2023, in accrued compensation on our Consolidated Balance Sheet (in thousands):


	Year Ended December 31, 2022
	No service period		Service period required		Total
Liability balance as of March 31, 2022	$	—	$	—	$	—
Expense recognized during the period	22,993		7,911		30,904
Payments during the period	(22,993)		(4,612)		(27,605)
Liability balance as of December 31, 2022	$	—	$	3,299	$	3,299

We recorded impairment charges as follows (in thousands):


	Year Ended December 31, 2022
	Operating Lease Right-of-Use Assets		Property, Plant and Equipment		Total
Net book value of impaired sublease assets as of May 31, 2022	$	72,481	$	16,348	$	88,829
Less: Fair value of impaired sublease assets — Level 3 of Fair Value Hierarchy	(16,174)		(4,780)		(20,954)
Book value in excess of fair value	56,307		11,568		67,875
Less: Amounts recorded as amortization between May 31 and December 31, 2022 for Third St. facility	(1,717)		(397)		(2,114)
Total impairment of sublease assets	$	54,590	$	11,171	$	65,761

Schedule of Property, Plant and Equipment

Property, plant and equipment consists of the following (in thousands):


	December 31,
	2022		2021
Building and leasehold improvements	$	74,889	$	97,385
Laboratory equipment	24,243		42,704
Computer equipment and software	26,205		28,829
Manufacturing equipment	25,052		22,374
Furniture, fixtures, and other	4,263		10,094
Depreciable property, plant and equipment at cost	154,652		201,386
Less: accumulated depreciation	(124,731)		(148,039)
Depreciable property, plant and equipment, net	29,921		53,347
Construction-in-progress	2,530		7,163
Property, plant and equipment, net	$	32,451	$	60,510

We recorded the gains and losses as follows (in thousands):


	Year Ended December 31, 2022
Proceeds from sales		$	13,196
Net book value of assets		9,870
Total (gain) loss on sale or disposal of property, plan and equipment, net		(3,326)

Organization and Summary of Significant Accounting Policies (Details) shares in Millions			1 Months Ended	3 Months Ended	12 Months Ended
	Jan. 14, 2020 USD ($)	Jul. 23, 2017	Apr. 30, 2022	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($) reporting_unit shares	Dec. 31, 2021 USD ($) shares	Dec. 31, 2020 USD ($) shares	Mar. 31, 2022 USD ($)
Organization And Summary Of Significant Accounting Policies [Line Items]
Cash and investments in marketable securities					$ 504,977,000	$ 798,783,000
Net expense reimbursements from collaboration partner						21,400,000
Number of reporting unit evaluated for goodwill \| reporting_unit					1
Total revenue					$ 92,055,000	101,907,000	$ 152,915,000
Level 3 \| Development Derivative Liability
Organization And Summary Of Significant Accounting Policies [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value					$ 0	$ 27,726,000	$ 0	$ 0
Employee Severance
Organization And Summary Of Significant Accounting Policies [Line Items]
Percent of positions eliminated			70.00%
Expense recognized during the period				$ 30,904,000
Stock Options, RSUs and PSUs
Organization And Summary Of Significant Accounting Policies [Line Items]
Weighted average antidilutive securities excluded from computation of earnings per share (in shares) \| shares					21.2	18.4	17.4
BMS Collaboration Agreement
Organization And Summary Of Significant Accounting Policies [Line Items]
Sales milestone revenue						$ 50,000,000
Nektar-358 \| Nektar's \| Eli Lilly And Company
Organization And Summary Of Significant Accounting Policies [Line Items]
Percentage of regulatory milestones payments will be reduced if conditions occur		75.00%
Cash And NonCash Royalties
Organization And Summary Of Significant Accounting Policies [Line Items]
Total revenue					$ 69,800,000	$ 77,700,000	$ 79,600,000
NKTR - 181 \| Program Termination
Organization And Summary Of Significant Accounting Policies [Line Items]
Expense recognized during the period	$ 45,200,000
NKTR - 181 \| Program Termination, Advance Paymnt To Contract Manyfacturers
Organization And Summary Of Significant Accounting Policies [Line Items]
Expense recognized during the period	19,700,000
NKTR - 181 \| Program Termination, Noncancellable Commitments
Organization And Summary Of Significant Accounting Policies [Line Items]
Expense recognized during the period	$ 25,500,000
Buildings
Organization And Summary Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful lives					20 years
Minimum \| Manufacturing equipment
Organization And Summary Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful lives					3 years
Maximum \| Nektar-358 \| Nektar's \| Eli Lilly And Company
Organization And Summary Of Significant Accounting Policies [Line Items]
Percentage of funding phase 3 development costs on an indication by indication basis borne		25.00%
Maximum \| Manufacturing equipment
Organization And Summary Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful lives					10 years

Cash and Investments in Marketable Securities - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Cash and Investments in Marketable Securities [Line Items]
Target maturity period	2 years
Weighted average maturity period	1 year
Sales of investments	$ 0	$ 11,504	$ 41,700
Accrued interest receivable	700	1,400
Gross unrealized gains	25
Gross unrealized losses	1,801	700
Letter of credit	$ 7,500	$ 8,100
Minimum
Cash and Investments in Marketable Securities [Line Items]
Long term investment maturity period		1 year
Maximum
Cash and Investments in Marketable Securities [Line Items]
Long term investment maturity period		2 years

Stockholders' Equity

12 Months Ended

Dec. 31, 2022

Equity [Abstract]

Stockholders' Equity

Stockholders’ Equity

As discussed in Note 10, on April 3, 2018, we completed the issuance and sale of 8,284,600 shares of our common stock under a Share Purchase Agreement with BMS. These shares are unregistered and subject to certain lock-up and stand-still provisions for a five-year period.

Prior to the filing of this Annual Report on Form 10-K, we had an effective shelf registration statement on Form S-3 (the 2021 Shelf Registration Statement) on file with the SEC. The 2021 Shelf Registration Statement permitted the offering, issuance and sale by us of up to an aggregate offering price of $300.0 million of common stock, preferred stock, debt securities and warrants in one or more offerings and in any combination, all of which could be offered, issued and sold in “at-the-market” sales pursuant to an equity distribution agreement with Cowen and Company, LLC (the Equity Distribution Agreement). No securities were sold under the 2021 Shelf Registration Statement or the Equity Distribution Agreement. As a result of the recent decline in our market capitalization, we are no longer a well-known seasoned issuer. Accordingly, the 2021 Shelf Registration Statement will no longer be available for us to offer and sell securities pursuant to the 2021 Shelf Registration Statement following the filing of this Annual Report on Form 10-K.

As of December 31, 2022, shares of common stock reserved for future issuance are as follows (in thousands):


Stock options, RSUs and PSUs outstanding			23,589
Shares available for future grant under the 2017 Performance Incentive Plan			2,973
Shares available for issuance under the employee stock purchase plan			841
Total common stock reserved for issuance			27,403

Our accumulated other comprehensive loss as of December 31, 2022, includes $1.8 million for net unrealized losses on our available for sale securities and $5.1 million for accumulated net translation losses primarily from our subsidiary in India.

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

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+ Details

Organization and Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Summary of Significant Accounting Policies	Organization and Summary of Significant Accounting Policies Organization We are a research-based biopharmaceutical company headquartered in San Francisco, California and incorporated in Delaware. We are developing a pipeline of drug candidates that utilize our advanced polymer conjugate technology platforms, which are designed to enable the development of new molecular entities that target known mechanisms of action. Our research and development pipeline of new investigational drugs includes innovative medicines in the field of immunotherapy. Our research and development activities have required significant ongoing investment to date and are expected to continue to require significant investment. As a result, we expect to continue to incur substantial losses and negative cash flows from operations in the future. We have financed our operations primarily through cash generated from licensing, collaboration and manufacturing agreements and financing transactions. At December 31, 2022, we had approximately $505.0 million in cash and investments in marketable securities. Results of Bempegaldesleukin Program and the 2022 Restructuring Plan In March and April 2022, we announced the unsuccessful results from our clinical trials studying bempegaldesleukin in combination with Opdivo® under our Strategic Collaboration Agreement with Bristol-Myers Squibb Company (BMS). Based on these results, we decided to discontinue all of our ongoing clinical trials of bempegaldesleukin in combination with checkpoint inhibitors and tyrosine kinase inhibitors. In April 2022, we also announced new strategic reorganization and cost restructuring plans (together, the 2022 Restructuring Plan) for the Company’s future: •On March 14, 2022, BMS and we announced that the registrational trial for bempegaldesleukin in combination with Opdivo® in metastatic melanoma did not meet its primary endpoints and that BMS and we decided to discontinue the registrational trials in metastatic melanoma and adjuvant melanoma. See Note 10 for additional information on our BMS Collaboration Agreement. •On April 14, 2022, we announced that each of our registrational trials for bempegaldesleukin in combination with Opdivo® in renal cell carcinoma and in cisplatin-ineligible, locally advanced or metastatic urothelial cancer did not meet their respective primary endpoints. Due to these results, BMS and we decided to discontinue these studies and all other ongoing studies for bempegaldesleukin in combination with Opdivo®. •On April 14, 2022, we announced that, in consultation with SFJ Pharmaceuticals and based upon a recommendation from an independent Data Monitoring Committee, we decided to discontinue our Phase 2/3 study in bempegaldesleukin in combination with Keytruda® in patients with metastatic or unresectable recurrent squamous cell cancer of the head and neck under our Co-Development Agreement with SFJ Pharmaceuticals. See Note 6 for additional information regarding our Co-Development Agreement with SFJ Pharmaceuticals. •We also announced on April 14, 2022, the discontinuation of our Phase 1/2 PROPEL study of bempegaldesleukin in combination with Keytruda® in locally advanced or metastatic solid tumors, including non-small cell lung cancer. With these announcements on April 14, 2022, subject to activities required for an orderly wind down of the studies, there will be no ongoing clinical development activities of bempegaldesleukin. •On April 25, 2022, we announced our 2022 Restructuring Plan, which was reviewed and approved by our Board of Directors on April 14, 2022. Pursuant to the 2022 Restructuring Plan, on April 26, 2022, our duly authorized officers implemented certain strategic, operational and organizational steps, including the prioritization of key Phase 2 development programs to advance our early stage research pipeline. In addition, we announced our plan to reduce our workforce by approximately 70% and to close our research facility in India. We have incurred significant costs resulting from these decisions and plans. See Note 11 for additional information on the effect of the 2022 Restructuring Plan on our Consolidated Financial Statements. Basis of Presentation, Principles of Consolidation and Use of Estimates Our Consolidated Financial Statements include the financial position, results of operations and cash flows of our wholly-owned subsidiaries. We have eliminated all intercompany accounts and transactions in consolidation. Our Consolidated Financial Statements are denominated in U.S. dollars. Accordingly, changes in exchange rates between the applicable foreign currency and the U.S. dollar will affect the translation of each foreign subsidiary’s financial results into U.S. dollars for purposes of reporting our consolidated financial results. We include translation gains and losses in accumulated other comprehensive loss in the stockholders’ equity section of our Consolidated Balance Sheets. To date, such cumulative currency translation adjustments have not been significant to our consolidated financial position. Our comprehensive loss consists of our net loss plus our foreign currency translation gains and losses and unrealized holding gains and losses on available-for-sale securities. There were no significant reclassifications out of accumulated other comprehensive loss to the statements of operations during the years ended December 31, 2022, 2021 and 2020. The preparation of consolidated financial statements in conformity with U.S. generally accepted accounting principles (GAAP) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. Accounting estimates and assumptions are inherently uncertain. Actual results could differ materially from those estimates and assumptions. Our estimates include those related to the selling prices of performance obligations and amounts of variable consideration in collaboration agreements, royalty revenue, and other assumptions required for revenue recognition as described further below; the net realizable value of inventory; the fair value and impairment of investments, goodwill and long-lived assets; contingencies, accrued clinical trial, contract manufacturing and other expenses; income taxes; non-cash royalty revenue and non-cash interest expense from our liabilities related to our sales of future royalties; assumptions used in the valuation of our development derivative liability as further described in Note 6; our assumptions used in stock-based compensation; and ongoing litigation, among other estimates. We base our estimates on historical experience and on other assumptions that management believes are reasonable under the circumstances. These estimates form the basis for making judgments about the carrying values of assets and liabilities when these values are not readily apparent from other sources. As appropriate, we assess estimates each period, update them to reflect current information, and will generally reflect any changes in estimates in the period first identified. Fair Value of Financial Instruments The recorded amounts of certain financial instruments, including cash and cash equivalents, accounts receivable, accounts payable and accrued liabilities approximate their fair values due to their relatively short maturities. We record available-for-sale investments and cash equivalents at their estimated fair values, which are based on market prices from a variety of industry standard data providers and generally represent quoted prices for similar assets in active markets or have been derived from observable market data. As further described in Note 11, we estimated the fair value of our lease assets for recognizing impairment charges based on management’s estimates of several unobservable inputs, including estimated time to enter a sublease, sublease rental rates and free rent periods. As further described in Note 6, we recorded the development derivative liability at its estimated fair value based on management’s estimates of several unobservable inputs, including the probabilities of success of clinical trials and various other inputs. The fair value of our financial assets and liabilities are determined in accordance with the fair value hierarchy established in ASC 820-10, Fair Value Measurements and Disclosures (ASC 820). ASC 820 defines fair value as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The fair value hierarchy of ASC Topic 820 requires an entity to maximize the use of observable inputs when measuring fair value and classifies those inputs into three levels: Level 1 — Quoted prices in active markets for identical assets or liabilities. Level 2 — Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices for identical or similar assets or liabilities in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. For the years ended December 31, 2022 and 2021, there were no transfers between Level 1 and Level 2 of the fair value hierarchy. Level 3 — Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. Cash, Cash Equivalents, and Investments in Marketable Securities We consider all investments in marketable securities with an original maturity of three months or less when purchased to be cash equivalents. We classify investments in securities with remaining maturities of less than one year, or where our intent is to use the investments to fund current operations or to make them available for current operations, as short-term investments. We classify investments in securities with remaining maturities of over one year as long-term investments. Our cash and investments are held or issued by financial institutions that management believes are of high credit quality. However, they are exposed to credit risk in the event of default by the third parties that hold or issue such assets. Our investment policy limits investments to fixed income securities denominated and payable in U.S. dollars such as corporate bonds, corporate commercial paper, U.S. government obligations, and money market funds and places restrictions on maturities and concentrations by type and issuer. For our available-for-sale securities, we have significant concentrations of issuers in the banking and financial services industry. While our investment policy requires that we only invest in highly-rated securities and limit our exposure to any single issuer, a variety of factors may materially affect the financial condition of issuers. Additionally, pursuant to our investment policy, we may sell securities before maturity if the issuer’s credit rating has been downgraded below our minimum credit rating requirements, which may result in a loss on the sale. Accordingly, if factors result in downgrades below our minimum credit rating requirements and if we decide to sell these securities, we may experience losses on such sales. Investments are designated as available-for-sale and are carried at fair value with unrealized gains and losses reported in stockholders’ equity as accumulated other comprehensive income (loss). We review our portfolio of available-for-sale debt securities, using both quantitative and qualitative factors, to determine if declines in fair value below amortized cost have resulted from a credit-related loss or other factors. If the decline in fair value is due to credit-related factors, we recognize a loss in our Consolidated Statement of Operations, whereas if the decline in fair value is not due to credit-related factors, we recognize the loss in other comprehensive income (loss). We include coupon interest on securities classified as available-for-sale, as well as amortization of premiums and accretion of discounts to maturity, in interest income. The cost of securities sold is based on the specific identification method. Accounts Receivable and Significant Customer Concentrations Our customers are primarily pharmaceutical and biotechnology companies that are primarily located in the U.S. and Europe and with whom we have multi-year arrangements. Our accounts receivable balance contains billed and unbilled trade receivables from product sales, milestones (to the extent that they have been achieved and are due from the counterparty), other contingent payments, as well as reimbursable costs from collaborative research and development agreements. Our accounts receivable included $4.2 million and $21.4 million for unbilled net expense reimbursements from our collaboration partner Bristol-Myers Squibb Company (BMS) as of December 31, 2022 and December 31, 2021, respectively. The remaining accounts receivable related primarily to product sales. We perform a regular review of our partners’ credit risk and payment histories when circumstances warrant, including payments made subsequent to year-end. When appropriate, we provide for an allowance for doubtful accounts by reserving for specifically identified doubtful accounts, although historically we have not experienced credit losses from our accounts receivable. Inventory and Significant Supplier Concentrations We generally manufacture inventory upon receipt of firm purchase orders from our collaboration partners, and we may manufacture certain intermediate work-in-process materials and purchase raw materials based on purchase forecasts from our collaboration partners. Inventory includes direct materials, direct labor, and manufacturing overhead, and we determine cost on a first-in, first-out basis for raw materials and on a specific identification basis for work-in-process and finished goods. We value inventory at the lower of cost or net realizable value, and we write down defective or excess inventory to net realizable value based on historical experience or projected usage. We expense inventory related to our research and development activities when we purchase or manufacture it. We are dependent on our suppliers and contract manufacturers to provide raw materials and drugs of appropriate quality and reliability and to meet applicable contract and regulatory requirements. In certain cases, we rely on single sources of supply of one or more critical materials. Consequently, in the event that supplies are delayed or interrupted for any reason, our ability to develop and produce our drug candidates, our ability to supply comparator drugs for our clinical trials, or our ability to meet our supply obligations could be significantly impaired, which could have a material adverse effect on our business, financial condition and results of operations. Restructuring We recognize restructuring charges related to reorganization plans that have been committed to by management when liabilities have been incurred. In connection with these activities, we record restructuring charges at fair value for: •contractual employee termination benefits provided that the obligations result from services already rendered based on vested rights to such benefits when the payment of benefits becomes probable and the amount can be reasonably estimated; •one-time employee termination benefits on the communication date from management to the employees provided that management has committed to a plan of termination, the plan identifies the employees and their expected termination dates, the details of termination benefits are complete, and it is unlikely that changes to the plan will be made or the plan will be withdrawn; •contract termination costs when we cancel the contract in accordance with its terms; and •costs to be incurred over the remaining contract term without economic benefit to us at the cease-use date. For one-time employee terminations benefits, we recognize the liability in full on the communication date when future services are not required or amortize the liability ratably over the service period, if required. The fair value of termination benefits reflects our estimates of expected utilization of certain Company-funded post-employment benefits. See Note 11 for additional information on the severance expense that we recognized for employees terminated in connection with our 2022 Restructuring Plan. Long-Lived Assets We report property, plant and equipment at cost, net of accumulated depreciation. We capitalize major improvements and expense maintenance and repairs as incurred. We generally recognize depreciation on a straight-line basis. We depreciate manufacturing, laboratory and other equipment over their estimated useful lives of generally three to ten years, depreciate buildings over the estimated useful life of generally twenty years and amortize leasehold improvements over the shorter of the estimated useful lives or the remaining term of the related lease. Goodwill represents the excess of the price paid for another entity over the fair value of the assets acquired and liabilities assumed in a business combination. We are organized in one reporting unit and evaluate the goodwill for the Company as a whole. Goodwill has an indefinite useful life and is not amortized, but instead tested for impairment at least annually in the fourth quarter of each year using an October 1 measurement date. We assess the impairment of long-lived assets whenever events or changes in business circumstances indicate that the carrying amounts of the assets may not be fully recoverable. In the case of property, plant and equipment and right-of-use assets for our leases, we determine whether there has been an impairment by comparing the carrying value of the asset to the anticipated undiscounted net cash flows associated with the asset. If such cash flows are less than the carrying value, we write down the asset to its fair value, which may be measured as anticipated discounted net cash flows associated with the asset. In the case of goodwill impairment, we compare the carrying value of the reporting unit to its fair value, which we generally measure using market capitalization for our single reporting unit. If an impairment exists, we write down goodwill such that the carrying value of the reporting unit equals its fair value. See Note 11 for additional information on the long-lived asset impairment expense that we recognized in connection with our 2022 Restructuring Plan. Leases We determine if an arrangement contains a lease at the inception of the arrangement. Right-of-use assets represent our right to use an underlying asset for the lease term, and lease liabilities represent our obligation to make lease payments arising from the lease. We recognize operating lease right-of-use assets and liabilities at the lease commencement date based on the present value of lease payments over the expected lease term. In determining the present value of lease payments, we use our incremental borrowing rate based on the information available at the lease commencement date. We have elected the practical expedient to account for the lease and non-lease components, such as common area maintenance charges, as a single lease component for our facilities leases, and elected the short-term lease recognition exemption for our short-term leases, under which we do not recognize lease liabilities and right-of-use assets for leases with an original term of twelve months or less. Our expected lease terms may include options to extend or terminate the lease when it is reasonably certain that we will exercise any such options. We recognize lease expense for our operating leases on a straight-line basis over the expected lease term. We have elected to recognize lease incentives, such as tenant improvement allowances, at the lease commencement date as a reduction of the right-of-use asset and lease liability until paid to us by the lessor to the extent that the lease provides a specified fixed or maximum level of reimbursement and we are reasonably certain to incur reimbursable costs at least equaling such amounts. Please see Note 5 for additional information regarding our leases. Collaborative Arrangements We enter into collaboration arrangements with pharmaceutical and biotechnology collaboration partners, under which we may grant licenses to our collaboration partners to further develop and commercialize one of our drug candidates, either alone or in combination with the collaboration partners’ compounds, or grant licenses to partners to use our technology to research and develop their own drug candidates. We may also perform research, development, manufacturing and supply activities under our collaboration agreements. Consideration under these contracts may include an upfront payment, development and regulatory milestones and other contingent payments, expense reimbursements, royalties based on net sales of approved drugs, and commercial sales milestone payments. Additionally, these contracts may provide options for the customer to purchase our proprietary PEGylation materials, drug candidates or additional contract research and development services under separate contracts. When we enter into collaboration agreements, we assess whether the arrangements fall within the scope of ASC 808, Collaborative Arrangements (ASC 808) based on whether the arrangements involve joint operating activities and whether both parties have active participation in the arrangement and are exposed to significant risks and rewards of the arrangement. To the extent that the arrangement falls within the scope of ASC 808, we assess whether the payments between us and our collaboration partner fall within the scope of other accounting literature. If we conclude that payments from the collaboration partner to us represent consideration from a customer, such as license fees and contract research and development activities, we account for those payments within the scope of ASC 606, Revenue from Contracts with Customers (ASC 606). However, if we conclude that our collaboration partner is not a customer for certain activities and associated payments, such as for certain collaborative research, development, manufacturing and commercial activities, we present such payments as a reduction of research and development expense or general and administrative expense, based on where we present the underlying expense. Revenue Recognition For elements of those arrangements that we determine should be accounted for under ASC 606, we assess which activities in our collaboration agreements are performance obligations that should be accounted for separately and determine the transaction price of the arrangement, which includes the assessment of the probability of achievement of future milestones and other potential consideration. For arrangements that include multiple performance obligations, such as granting a license or performing contract research and development activities or participation on joint steering or other committees, we allocate upfront and milestone payments under a relative standalone selling price method. Accordingly, we develop assumptions that require judgment to determine the standalone selling price for each performance obligation identified in the contract. These key assumptions may include revenue forecasts, clinical development timelines and costs, discount rates and probabilities of clinical and regulatory success. Product sales Product sales are primarily derived from manufacturing and supply agreements with our customers. We have assessed our current manufacturing and supply arrangements and have generally determined that they provide the customer an option to purchase our proprietary PEGylation materials. Accordingly, we treat each purchase order as a discrete exercise of the customer’s option (i.e. a separate contract) rather than as a component of the overall arrangement. The pricing for the manufacturing and supply is generally at a fixed price and may be subject to annual producer price index (PPI) adjustments. We invoice and recognize product sales when title and risk of loss pass to the customer, which generally occurs upon shipment. Customer payments are generally due 30 days from receipt of an invoice. We test our products for adherence to technical specifications before shipment; accordingly, we have not experienced any significant returns from our customers. We recognize costs related to shipping and handling of product to customers in cost of goods sold. Royalty revenue, including Non-cash royalty revenue Generally, for our collaboration arrangements that include sales-based royalties, we have granted our collaboration partner a license to our intellectual property. Pursuant to these arrangements, our collaboration partners are typically obligated to pay a royalty that is based on the net sales of their approved drugs that are sold in the countries where we have intellectual property rights covering their drugs. We have sold our rights to receive sales-based royalties for CIMZIA®, MIRCERA®, MOVANTIK®, ADYNOVATE® and REBINYN® as further described in Note 7. For collaboration arrangements that include sales-based royalties, we have concluded that the license is the predominant item to which the royalties relate, which include commercial milestone payments based on the level of sales. Accordingly, we recognize royalty revenue when the underlying sales occur based on our best estimates of sales of the drugs. Our aggregate royalty and non-cash royalty revenue of $69.8 million, $77.7 million and $79.6 million for the years ended December 31, 2022, 2021 and 2020, respectively, represents revenue for granting licenses for which we had satisfied in prior periods. Our partners generally pay royalties or commercial milestones after the end of the calendar quarter in accordance with contractual terms. We present commercial milestone payments within license, collaboration and other revenue. License, collaboration and other revenue License Grants: For collaboration arrangements that include a grant of a license to our intellectual property, we consider whether the license grant is distinct from the other performance obligations included in the arrangement. Generally, we would conclude that the license is distinct if the customer is able to benefit from the license with the resources available to it. For licenses that are distinct, we recognize revenues from nonrefundable, upfront payments and other consideration allocated to the license when the license term has begun and we have provided all necessary information regarding the underlying intellectual property to the customer, which generally occurs at or near the inception of the arrangement. Milestone Payments: At the inception of the arrangement and at each reporting date thereafter, we assess whether we should include any milestone payments or other forms of variable consideration in the transaction price, based on whether a significant reversal of revenue previously recognized is not probable upon resolution of the uncertainty. Since milestone payments may become payable to us upon the initiation of a clinical study, filing for or receipt of regulatory approval or the first commercial sale of a product, we review the relevant facts and circumstances to determine when we should update the transaction price, which may occur before the triggering event. When we do update the transaction price for milestone payments, we allocate it on a relative standalone selling price basis and record revenue on a cumulative catch-up basis, which results in recognizing revenue for previously satisfied performance obligations in such period. As described further in Note 10, we recognized $50.0 million of milestones in the year ended December 31, 2020 because we had previously satisfied the performance obligation. If we update the transaction price before the triggering event, we recognize the increase in the transaction price as a contract asset. Our partners generally pay development milestones subsequent to achievement of the triggering event. Research and Development Services: For amounts allocated to our research and development obligations in a collaboration arrangement, we recognize revenue over time using a proportional performance model, representing the transfer of goods or services as we perform activities over the term of the agreement. Research and Development Expense Research and development costs are expensed as incurred and include salaries, benefits and other operating costs such as outside services, supplies and allocated overhead costs. We perform research and development activities for our drug candidates and technology development and for certain third parties under collaboration agreements. For our drug candidates and our internal technology development programs, we invest our own funds without reimbursement from a third party. Where we perform research and development activities under a joint development collaboration, such as our collaboration with BMS, we record the cost reimbursement from our partner as a reduction to research and development expense when reimbursement amounts are due to us under the agreement. We record an accrued expense for the estimated unbilled costs of our clinical study activities performed by third parties. The financial terms of these agreements are subject to negotiation, vary from contract to contract and may result in uneven payment flows to our vendors. Payments under the contracts depend on factors such as the achievement of certain events, successful enrollment of patients and completion of certain clinical trial activities. We generally recognize costs associated with the start-up and reporting phases of the clinical trials as incurred. We generally accrue costs associated with the treatment phase of clinical trials based on the estimated activities performed by our third party vendors, including our contract research organizations. We may also accrue expenses based on the total estimated cost of the treatment phase on a per patient basis and expense the per patient cost ratably over the estimated patient treatment period. In specific circumstances, such as for certain time-based costs, we recognize clinical trial expenses ratably over the service period, as we believe that this methodology may be more reflective of the timing of costs incurred. We record an accrued expense for the estimated costs of our contract manufacturing activities performed by third parties. The financial terms of these agreements are subject to negotiation, vary from contract to contract and may result in uneven payment flows to our vendors. Payments under the contracts include upfront payments and milestone payments, which depend on factors such as the achievement of the completion of certain stages of the manufacturing process. For purposes of recognizing expense, we assess whether we consider the production process to be sufficiently defined such that the resulting product can be considered the delivery of a good, as evidenced by predictive or contractually required yields in the production process or payment terms based on the actual yield, or the delivery of a service, where processes and yields are developing and less certain. If we consider the process to be the delivery of a good, we recognize expense when the drug product is delivered, or we otherwise bear risk of loss. If we consider the process to be the delivery of a service, we recognize expense based on our best estimates of the contract manufacturer’s progress towards completion of the stages in the contracts. We recognize and amortize upfront payments and accrue liabilities based on the specific terms of each arrangement. Certain arrangements may provide upfront payments for certain stages of the arrangement and milestone payments for the completion of certain stages, and, accordingly, we may record advance payments for services that have not been completed or goods not delivered and liabilities for stages where the contract manufacturer is entitled to a milestone payment. We capitalize advance payments for goods or services that will be used or rendered for future research and development activities and recognize expense as the related goods are delivered or services performed. We base our estimates on the best information available at the time. However, additional information may become available to us in the future which may allow us to make a more accurate estimate in future periods. In this event, we may be required to record adjustments to research and development expenses in future periods when the actual level of activity becomes more certain. We generally consider such increases or decreases in cost as changes in estimates and reflect them in research and development expenses in the period identified. Restructuring, Impairment and Other Costs for Terminated Program Amounts recorded as restructuring, impairment and other costs for terminated program for the year ended December 31, 2022 relate to the termination of the bempegaldesleukin program and the 2022 Restructuring Plan. See Note 11 for additional information. Amounts recorded as restructuring, impairment and other costs for terminated program for the year ended December 31, 2020 relate to the termination of the NKTR-181 program. On January 14, 2020, the joint FDA Anesthetic Drug Products Advisory Committee and Drug Safety and Risk Management Committee did not recommend approval of our NDA for NKTR-181. As a result, we withdrew our NDA and wound down Inheris and the NKTR-181 program. As a result, we wrote off $45.2 million, including $19.7 million of advance payments to contract manufacturers for commercial batches of NKTR-181 and $25.5 million of additional costs, primarily for non-cancellable commitments to our contract manufacturers and certain severance costs. Stock-Based Compensation Stock-based compensation arrangements include grants of stock options, restricted stock units (RSUs), performance stock units (PSUs) under our equity incentive plans, as well as shares issued under our Employee Stock Purchase Plan (ESPP), through which employees may purchase our common stock at a discount to the market price. We expense the grant date fair value of options, RSUs, PSUs and ESPP shares on a straight-line basis over the requisite service periods in our Consolidated Statements of Operations and recognize forfeitures of options, RSUs and PSUs as they occur. For options and RSUs that vest upon the achievement of performance milestones, we recognize expense provided that we believe that the performance milestones are probable of achievement, and we estimate the vesting period based on our evaluation of the estimated date of achievement of these milestones. For PSUs, we recognize expense based on the grant date fair value regardless of whether the market condition is met. Additionally, we do not adjust the expense based on the number of shares ultimately issued, which may be higher or lower than the grant amount. We report expense amounts in cost of goods sold, research and development expense, and general and administrative expense based on the function of the applicable employee. Stock-based compensation charges are non-cash charges and have no effect on our reported cash flows. We estimate the grant date fair value of our stock-based compensation awards as follows: •We use the Black-Scholes option pricing model for the respective grant to determine the estimated fair value of the option on the date of grant (grant date fair value) and the estimated fair value of common stock purchased under the ESPP. The Black-Scholes option pricing model requires the input of highly subjective assumptions, including but not limited to, our stock price volatility over the term of the awards, and actual and projected employee stock option exercise behaviors. •The number of shares issuable under PSUs is based on our total shareholder return as compared to other companies within the Nasdaq biotechnology index over the measurement period and may be capped based on our absolute total shareholder return over such period. We use the Monte Carlo simulation model to determine the estimated grant date fair value. The Monte Carlo simulation model incorporates assumptions such as the volatility of our stock, the volatility of the stock of other peer companies within the index, and the correlation of both our stock and our peer companies’ stock to the index. •The fair value of an RSU is equal to the closing price of our common stock on the grant date. Income Taxes We account for income taxes under the liability method. Under this method, we determine deferred tax assets and liabilities based on differences between the financial reporting and tax reporting bases of assets and liabilities, measured using enacted tax rates and laws that we expect to be in effect when we expect the differences to reverse. Realization of deferred tax assets is dependent upon future earnings, the timing and amount of which are uncertain. We record a valuation allowance against deferred tax assets to reduce their carrying value to an amount that is more likely than not to be realized. When we establish or reduce the valuation allowance related to the deferred tax assets, our provision for income taxes will increase or decrease, respectively, in the period we make such determination. We utilize a two-step approach to recognize and measure uncertain tax positions. The first step is to evaluate the tax position for recognition by determining if the weight of available evidence indicates that it is more likely than not that the position will be sustained upon tax authority examination, including resolution of related appeals or litigation processes, if any. The second step is to measure the tax benefit as the largest amount of benefit, determined on a cumulative probability basis, that is more than 50% likely of being realized upon ultimate settlement. For the years ended December 31, 2022, 2021 and 2020, our income tax provision primarily relates to our Nektar India subsidiary. As a result of the 2022 Restructuring Plan and our intent to wind down our foreign subsidiaries, we have recorded a provision for the repatriation of accumulated earnings and profits from India. See Note 13 for additional information. Net Loss Per Share For all periods presented in the Consolidated Statements of Operations, the net loss available to common stockholders is equal to the reported net loss. We calculate basic net loss per share based on the weighted-average number of common shares outstanding during the periods presented. For the years ended December 31, 2022, 2021 and 2020, basic and diluted net loss per share are the same due to our net losses and the requirement to exclude potentially dilutive securities which would have an antidilutive effect on net loss per share. We excluded shares underlying the weighted average outstanding stock options, RSUs and PSUs, which totaled 21.2 million, 18.4 million and 17.4 million for the years ended December 31, 2022, 2021 and 2020, respectively. Comprehensive Loss Comprehensive loss is the change in stockholders’ equity from transactions and other events and circumstances other than those resulting from investments by stockholders and distributions to stockholders. Our comprehensive loss includes our net loss, gains and losses from the foreign currency translation of the assets and liabilities of our foreign subsidiaries, and unrealized gains and losses on investments in available-for-sale securities. Recent Accounting Pronouncements We have reviewed recent accounting pronouncements and concluded they are either not applicable to us or that we do not expect adoption to have a material effect on our consolidated financial statements.

Commitments and Contingencies	12 Months Ended
Commitments and Contingencies	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Purchase Commitments In the normal course of business, we enter into various firm purchase commitments related to contract manufacturing, clinical development and certain other items. As of December 31, 2022, these commitments were not significant. Legal Matters From time to time, we are involved in lawsuits, arbitrations, claims, investigations and proceedings, consisting of intellectual property, commercial, employment and other matters, which arise in the ordinary course of business. We make provisions for liabilities when it is both probable that a liability has been incurred and the amount of the loss can be reasonably estimated. Such provisions are reviewed at least quarterly and adjusted to reflect the impact of settlement negotiations, judicial and administrative rulings, advice of legal counsel, and other information and events pertaining to a particular case. Litigation is inherently unpredictable. If any unfavorable ruling were to occur in any specific period, there exists the possibility of a material adverse impact on the results of our operations for that period and on our cash flows and liquidity. We have recorded no liability for any litigation matters in our Consolidated Balance Sheets at either December 31, 2022 or December 31, 2021. Foreign Operations We have operated in a number of foreign countries, but we are in the process of winding down our foreign subsidiaries. As of December 31, 2022, we no longer have any foreign properties and only a few remaining employees in foreign locations. We are subject to numerous local laws and regulations that can result in claims made by foreign government agencies or other third parties that are often difficult to predict even after the application of good faith compliance efforts. Indemnification Obligations During the course of our normal operating activities, we have agreed to certain contingent indemnification obligations as further described below. The term of our indemnification obligations is generally perpetual. There is generally no limitation on the potential amount of future payments we could be required to make under these indemnification obligations. To date, we have not incurred significant costs to defend lawsuits or settle claims based on our indemnification obligations. If any of our indemnification obligations is triggered, we may incur substantial liabilities. Because the aggregate amount of any of these potential indemnification obligations is not a stated amount, we cannot reasonably estimate the overall maximum amount of any such obligations. We have recorded no liabilities for these obligations in our Consolidated Balance Sheets at either December 31, 2022 or December 31, 2021. Indemnifications in Connection with Commercial Agreements As part of our collaboration agreements with our partners related to the license, development, manufacture and supply of drugs and PEGylation materials based on our proprietary technologies and drug candidates, we generally agree to defend, indemnify and hold harmless our partners from and against third party liabilities arising out of the agreement, including product liability (with respect to our activities) and infringement of intellectual property to the extent the intellectual property is developed by us and licensed to our partners. The term of these indemnification obligations is generally perpetual commencing after execution of the agreement. There is generally no limitation on the potential amount of future payments we could be required to make under these indemnification obligations. From time to time, we enter into other strategic agreements such as divestitures and financing transactions pursuant to which we are required to make representations and warranties and undertake to perform or comply with certain covenants. For example, we made certain intellectual property representations in connection with our RPI and HCR transactions, however, the time limitation we have to indemnify RPI with respect to any breach of these intellectual property-based representations and warranties has passed. In the event it is determined that we breached certain of the representations and warranties or covenants made by us in any such agreements or certain express indemnification provisions are applicable, we could incur substantial indemnification liabilities depending on the timing, nature, and amount of any such claims. To date, we have not incurred any costs to defend lawsuits or settle claims related to these indemnification obligations, nor any breaches of representations or warranties or covenants. Because the aggregate amount of any potential indemnification obligation is not a stated amount, we cannot reasonably estimate the overall maximum amount of any such obligations. Indemnification of Underwriters and Initial Purchasers of our Securities In connection with our sale of equity we have agreed to defend, indemnify and hold harmless our underwriters or initial purchasers, as applicable, as well as certain related parties from and against certain liabilities, including liabilities under the Securities Act of 1933, as amended. Director and Officer Indemnifications As permitted under Delaware law, and as set forth in our Certificate of Incorporation and our Bylaws, we indemnify our directors, executive officers, other officers, employees, and other agents for certain events or occurrences that may arise while in such capacity. The maximum potential amount of future payments we could be required to make under this indemnification is unlimited; however, we have insurance policies that may limit our exposure and may enable us to recover a portion of any future amounts paid. Assuming the applicability of coverage, the willingness of the insurer to assume coverage, and subject to certain retention, loss limits and other policy provisions, we believe any obligations under this indemnification would not be material, other than retention of up to $10.0 million per incident for merger and acquisition related claims, $10.0 million per incident for securities related claims and $10.0 million per incident for non-securities related claims per our insurance policy. However, no assurances can be given that the covering insurers will not attempt to dispute the validity, applicability, or amount of coverage without expensive litigation against these insurers, in which case we may incur substantial liabilities as a result of these indemnification obligations.

Restructuring, Impairment and Other Costs of Terminated Program - Sublease Information (Details) - USD ($) $ in Thousands	7 Months Ended	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	May 31, 2022
Restructuring Cost and Reserve [Line Items]
Book value in excess of fair value	$ 67,875
Less: Amounts recorded as amortization between May 31 and December 31, 2022 for Third St. facility	(2,114)
Total impairment of sublease assets		$ 65,761	$ 0	$ 0
Reported Value Measurement
Restructuring Cost and Reserve [Line Items]
Property, plant and equipment and Operating lease right-of-use assets					$ (88,829)
Estimate of Fair Value Measurement \| Level 3
Restructuring Cost and Reserve [Line Items]
Property, plant and equipment and Operating lease right-of-use assets	(20,954)	(20,954)
Sublease Property, Plant And Equipment
Restructuring Cost and Reserve [Line Items]
Book value in excess of fair value	56,307
Less: Amounts recorded as amortization between May 31 and December 31, 2022 for Third St. facility	(1,717)
Total impairment of sublease assets		54,590
Sublease Property, Plant And Equipment \| Reported Value Measurement
Restructuring Cost and Reserve [Line Items]
Property, plant and equipment and Operating lease right-of-use assets					(72,481)
Sublease Property, Plant And Equipment \| Estimate of Fair Value Measurement \| Level 3
Restructuring Cost and Reserve [Line Items]
Property, plant and equipment and Operating lease right-of-use assets	(16,174)	(16,174)
Sublease Operating Lease Right of Use Assets
Restructuring Cost and Reserve [Line Items]
Book value in excess of fair value	11,568
Less: Amounts recorded as amortization between May 31 and December 31, 2022 for Third St. facility	(397)
Total impairment of sublease assets		11,171
Sublease Operating Lease Right of Use Assets \| Reported Value Measurement
Restructuring Cost and Reserve [Line Items]
Property, plant and equipment and Operating lease right-of-use assets					$ (16,348)
Sublease Operating Lease Right of Use Assets \| Estimate of Fair Value Measurement \| Level 3
Restructuring Cost and Reserve [Line Items]
Property, plant and equipment and Operating lease right-of-use assets	$ (4,780)	$ (4,780)

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2022

Share-Based Payment Arrangement [Abstract]

Schedule of Stock-Based Compensation Expense

We recognize total stock-based compensation expense in our Consolidated Statements of Operations as follows (in thousands):


	Year Ended December 31,
	2022		2021		2020
Cost of goods sold	$	2,824	$	2,779	$	2,825
Research and development	27,727		54,821		57,116
General and administrative	24,488		37,074		33,295
Restructuring, impairment and other costs of terminated program	2,281		—		1,025
Total stock-based compensation	$	57,320	$	94,674	$	94,261

Schedule of Black-Scholes Option-Pricing Model Assumptions Used to Calculate Fair Value of Employee Stock Options

As of December 31, 2022, shares of common stock reserved for future issuance are as follows (in thousands):


Stock options, RSUs and PSUs outstanding			23,589
Shares available for future grant under the 2017 Performance Incentive Plan			2,973
Shares available for issuance under the employee stock purchase plan			841
Total common stock reserved for issuance			27,403

The following table lists the Black-Scholes option-pricing model assumptions used to calculate the fair value of employee and director stock options, as well as the resulting grant-date fair value:


	Year Ended December 31,
	2022			2021			2020
Average risk-free interest rate	2.9		%	1.2		%	0.4		%
Dividend yield	0.0		%	0.0		%	0.0		%
Average volatility factor	77.9		%	63.8		%	64.1		%
Weighted-average expected life	5.6 years			5.5 years			5.6 years
Weighted-average grant-date fair value of options granted	$	3.18		$	8.07		$	10.70

Schedule of Stock Option Activity Under Equity Incentive Plans

The table below presents a summary of stock option activity under our equity incentive plans (in thousands, except for price per share and contractual life information):


	Number of Shares	Weighted- Average Exercise Price per Share		Weighted- Average Remaining Contractual Life (in Years)	Aggregate Intrinsic Value(1)
Outstanding at December 31, 2021	13,542	$	23.62
Options granted	6,276	4.76
Options exercised	(15)	12.43
Options forfeited & canceled	(5,715)	20.73
Outstanding at December 31, 2022	14,088	$	16.40	5.71	$	—

Exercisable at December 31, 2022	6,029	27.82		3.60	$	—

_______________________________________________________________(1)Aggregate intrinsic value represents the difference between the exercise price of the option and the closing market price of our common stock on December 31, 2022.

Schedule of Restricted Stock Unit Award Activity

A summary of RSU award activity is as follows (in thousands except for per share amounts):


	Units Issued	Weighted- Average Grant Date Fair Value
Unvested at December 31, 2021	9,930	$	16.80
Granted	7,708	4.14
Vested and released	(2,872)	17.64
Forfeited and canceled	(5,454)	15.68
Unvested at December 31, 2022	9,312	$	6.81

Segment Reporting (Tables)

12 Months Ended

Dec. 31, 2022

Segment Reporting [Abstract]

Schedule of Revenue by Geographic Area

The following table sets forth revenue by geographic area (in thousands):


	Year Ended December 31,
	2022		2021		2020
United States	$	9,841	$	10,114	$	64,966
Rest of World	82,214		91,793		87,949
Total revenue	$	92,055	$	101,907	$	152,915

Income Taxes - Schedule of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balance	$ 80,604	$ 78,665	$ 77,410
Tax positions related to current year:
Additions	378	2,371	2,512
Reductions	0	0	0
Tax positions related to prior years:
Additions	5,272	58	193
Reductions	0	(490)	(1,450)
Settlements	0	0	0
Lapses in statute of limitations	(409)	0	0
Ending balance	$ 85,845	$ 80,604	$ 78,665

Segment Reporting - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($) segment	Dec. 31, 2021 USD ($)	Dec. 31, 2020
Segment Reporting Information [Line Items]
Number of operating business segment \| segment	1
Property, plant and equipment, net	$ 32,451	$ 60,510
United States
Segment Reporting Information [Line Items]
Property, plant and equipment, net		$ 56,100
Revenue \| UCB \| Customer Concentration Risk
Segment Reporting Information [Line Items]
Percentage revenue from customers	37.00%	36.00%	23.00%
Revenue \| Baxalta Incorporated Or Takeda P L C \| Customer Concentration Risk
Segment Reporting Information [Line Items]
Percentage revenue from customers	25.00%	23.00%	14.00%
Revenue \| Astra Zeneca Ab \| Customer Concentration Risk
Segment Reporting Information [Line Items]
Percentage revenue from customers	14.00%	16.00%	13.00%
Revenue \| Pfizer \| Customer Concentration Risk
Segment Reporting Information [Line Items]
Percentage revenue from customers	11.00%	13.00%
Revenue \| BMS \| Customer Concentration Risk
Segment Reporting Information [Line Items]
Percentage revenue from customers			33.00%
Property, Plant and Equipment \| Geographic Concentration Risk \| United States
Segment Reporting Information [Line Items]
Percentage revenue from customers		93.00%

Liabilities Related to the Sales of Future Royalties (Tables)

12 Months Ended

Dec. 31, 2022

Schedule of Liability Related to Potential Future Royalties

The following table shows the activity within the liability account of each arrangement (in thousands):


	Year-Ended December 31, 2022						Period from inception to December 31, 2022
	2012 Purchase and Sale Agreement		2020 Purchase and Sale Agreement		Total		2012 Purchase and Sale Agreement		2020 Purchase and Sale Agreement		Total
Liabilities related to the sales of future royalties—beginning balance	$	78,282	$	120,062	$	198,344	$	—	$	—	$	—
Royalty monetization proceeds	—		—		—		124,000		150,000		274,000
Non-cash royalty revenue	(33,865)		(35,929)		(69,794)		(316,523)		(86,722)		(403,245)
Non-cash interest expense	10,750		18,161		28,911		234,168		39,016		273,184
Payments to RPI	—		—		—		(10,000)		—		(10,000)
Loss on revaluation of liability related to the sale of future royalties	—				—		23,522		—		23,522
Liabilities related to the sales of future royalties – ending balance	55,167		102,294		157,461		55,167		102,294		157,461
Less: unamortized transaction costs	—		(2,083)		(2,083)		—		(2,083)		(2,083)
Liabilities related to the sales of future royalties, net	$	55,167	$	100,211	$	155,378	$	55,167	$	100,211	$	155,378

Stockholders' Equity - Schedule of Shares of Common Stock Reserved for Future Issuance (Details) shares in Thousands	Dec. 31, 2022 shares
Class of Stock [Line Items]
Total common stock reserved for issuance	27,403
2017 Performance Incentive Plan
Class of Stock [Line Items]
Total common stock reserved for issuance	2,973
Employee Stock Purchase Plan
Class of Stock [Line Items]
Total common stock reserved for issuance	841
Share-based Payment Arrangement, Option, RSUs And PSUs
Class of Stock [Line Items]
Total common stock reserved for issuance	23,589

Inventory

12 Months Ended

Dec. 31, 2022

Inventory Disclosure [Abstract]

Inventory

Inventory Inventory consists of the following (in thousands):


	December 31,
	2022		2021
Raw materials	$	2,575	$	3,166
Work-in-process	10,749		9,342
Finished goods	5,878		3,293
Total inventory	$	19,202	$	15,801

CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Capital in Excess of Par Value	Accumulated Other Comprehensive Loss	Accumulated Deficit
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock, shares outstanding (in shares)		176,505
Beginning balance (in shares) at Dec. 31, 2019		176,505
Beginning balance at Dec. 31, 2019	$ 1,405,391	$ 17	$ 3,271,097	$ (1,005)	$ (1,864,718)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued under equity compensation plans (in shares)		3,586
Shares issued under equity compensation plans	23,373	$ 1	23,372
Stock-based compensation	94,261		94,261
Comprehensive loss	(445,730)			(1,290)	(444,440)
Ending balance (in shares) at Dec. 31, 2020		180,091
Ending balance at Dec. 31, 2020	1,077,295	$ 18	3,388,730	(2,295)	(2,309,158)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock, shares outstanding (in shares)		180,091
Shares issued under equity compensation plans (in shares)		5,377
Shares issued under equity compensation plans	33,238	$ 1	33,237
Stock-based compensation	94,674		94,674
Comprehensive loss	$ (525,699)			(1,862)	(523,837)
Ending balance (in shares) at Dec. 31, 2021	185,468	185,468
Ending balance at Dec. 31, 2021	$ 679,508	$ 19	3,516,641	(4,157)	(2,832,995)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock, shares outstanding (in shares)	185,468	185,468
Shares issued under equity compensation plans (in shares)		3,092
Shares issued under equity compensation plans	$ 758	$ 0	758
Stock-based compensation	57,320		57,320
Comprehensive loss	$ (370,948)			(2,750)	(368,198)
Ending balance (in shares) at Dec. 31, 2022	188,560	188,560
Ending balance at Dec. 31, 2022	$ 366,638	$ 19	$ 3,574,719	$ (6,907)	$ (3,201,193)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock, shares outstanding (in shares)	188,560	188,560

- Definition

Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(g)(1)(ii))
-URI https://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 852
-SubTopic 10
-Section 55
-Paragraph 10
-URI https://asc.fasb.org/extlink&oid=84165509&loc=d3e56426-112766

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 4.E)
-URI https://asc.fasb.org/extlink&oid=122038336&loc=d3e74512-122707

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(31))
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-URI https://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

+ Details

Cash and Investments in Marketable Securities - Schedule of Cash and Investments in Marketable Securities, Including Cash Equivalents (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Estimated Fair Value at
Cash and cash equivalents	$ 88,227	$ 25,218
Short-term investments	416,750	708,737
Long-term investments	0	64,828
Total cash and investments in marketable securities	$ 504,977	$ 798,783

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 88,227	$ 25,218
Short-term investments	416,750	708,737
Accounts receivable	5,981	22,492
Inventory	19,202	15,801
Other current assets	15,808	23,333
Total current assets	545,968	795,581
Long-term investments	0	64,828
Property, plant and equipment, net	32,451	60,510
Operating lease right-of-use assets	53,435	117,025
Goodwill	76,501	76,501
Other assets	2,245	2,744
Total assets	710,600	1,117,189
Current liabilities:
Accounts payable	12,980	9,747
Accrued compensation	9,582	15,735
Accrued clinical trial expenses	12,262	26,809
Other accrued expenses	14,713	15,468
Operating lease liabilities, current portion	18,667	17,441
Total current liabilities	68,204	85,200
Operating lease liabilities, less current portion	112,829	125,736
Development derivative liability	0	27,726
Liabilities related to the sales of future royalties, net	155,378	195,427
Other long-term liabilities	7,551	3,592
Total liabilities	343,962	437,681
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $0.0001 par value; 10,000 shares authorized; no shares designated, issued or outstanding at December 31, 2022 or 2021	0	0
Common stock, $0.0001 par value; 300,000 shares authorized; 188,560 shares and 185,468 shares issued and outstanding at December 31, 2022 and 2021, respectively	19	19
Capital in excess of par value	3,574,719	3,516,641
Accumulated other comprehensive loss	(6,907)	(4,157)
Accumulated deficit	(3,201,193)	(2,832,995)
Total stockholders’ equity	366,638	679,508
Total liabilities and stockholders’ equity	$ 710,600	$ 1,117,189

Income Taxes

12 Months Ended

Dec. 31, 2022

Income Tax Disclosure [Abstract]

Income Taxes

Loss before provision for income taxes includes the following components (in thousands):


	Year Ended December 31,
	2022		2021		2020
Domestic	$	(371,900)	$	(524,440)	$	(445,370)
Foreign	6,917		1,160		1,423
Loss before provision for income taxes	$	(364,983)	$	(523,280)	$	(443,947)

Provision for Income Taxes

The provision for income taxes consists of the following (in thousands):


	Year Ended December 31,
	2022		2021		2020
Current:
Federal	$	—	$	—	$	—
State	(608)		50		165
Foreign	1,115		609		364
Total current income tax expense	507		659		529
Deferred:
Federal	—		—		—
State	—		—		—
Foreign	2,708		(102)		(36)
Total deferred income tax expense	2,708		(102)		(36)
Provision for income taxes	$	3,215	$	557	$	493

Our income tax provision related to continuing operations differs from the amount computed by applying the statutory income tax rate of 21% to our pretax loss as follows (in thousands):


	Year Ended December 31,
	2022		2021		2020
Income tax benefit at federal statutory rate	$	(76,647)	$	(109,889)	$	(93,229)
Research credits	(987)		(4,727)		(3,081)
Change in valuation allowance	51,108		97,914		87,060
Expiration of net operating loss carryforwards	12,348		286		286
Stock-based compensation	15,778		6,627		7,929
Non-cash interest expense on liability related to sales of future royalties	6,071		9,936		6,356
Non-cash royalty revenue related to sales of future royalties	(7,112)		(7,891)		(7,967)
Loss on revaluation of liability related to the sale of future royalties	—		4,940		—
Other	2,656		3,361		3,139
Provision for income taxes	$	3,215	$	557	$	493

Deferred Tax Assets and Liabilities

Deferred income taxes reflect the net tax effects of loss and credit carryforwards and temporary differences between the carrying amount of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. We measure deferred tax assets and liabilities based on the rates at which they are expected to reverse in the future. Significant components of our deferred tax assets for federal and state income taxes are as follows (in thousands):


	December 31,
	2022		2021
Deferred tax assets:
Net operating loss carryforwards	$	545,508	$	564,712
Research and other credits	142,198		139,996
Net capital loss carryforwards	38,445		—
Operating lease liabilities	28,254		34,680
Stock-based compensation	22,110		33,408
Capitalized research and development costs	24,134		—
Liability related to the sale of future royalties	13,424		23,757
Other	13,935		17,290
Deferred tax assets before valuation allowance	828,008		813,843
Valuation allowance for deferred tax assets	(816,235)		(785,748)
Total deferred tax assets	11,773		28,095
Deferred tax liabilities:
Operating lease right-of-use assets	(11,335)		(27,204)
Investment in foreign subsidiary	(2,451)		—
Other	(392)		(564)
Total deferred tax liabilities	(14,178)		(27,768)
Net deferred tax assets (liabilities)	$	(2,405)	$	327

Realization of our deferred tax assets is dependent upon future earnings, if any, the timing and amount of which are uncertain. Because of our lack of U.S. earnings history, other than income resulting from revenue recognized from the BMS Collaboration Agreement, and projected future losses, we have fully reserved our net U.S. deferred tax assets with a valuation allowance. The valuation allowance increased by $30.5 million and $115.6 million during the years ended December 31, 2022 and 2021, respectively.

Our net deferred tax liability position reflects the provision for the withholding taxes associated with the repatriation of accumulated earnings and profits from India.

Net Operating Loss and Tax Credit Carryforwards

As of December 31, 2022, we had a net operating loss carryforward for federal income tax purposes of approximately $2.4 billion, of which $1.3 billion is subject to expiration beginning in 2023 and a total state net operating loss carryforward of approximately $0.7 billion, portions of which will begin to expire in 2027. We have federal tax credits of approximately $123.8 million, which will begin to expire in 2023 and state research credits of approximately $48.8 million which have no expiration date. Utilization of some of the federal and state net operating loss and credit carryforwards are subject to annual limitations due to the “change in ownership” provisions of the Internal Revenue Code of 1986 and similar state provisions.

Unrecognized tax benefits

We have the following activity relating to unrecognized tax benefits (in thousands):


	Year Ended December 31,
	2022		2021		2020
Beginning balance	$	80,604	$	78,665	$	77,410
Tax positions related to current year:
Additions	378		2,371		2,512
Reductions	—		—		—
Tax positions related to prior years:
Additions	5,272		58		193
Reductions	—		(490)		(1,450)
Settlements	—		—		—
Lapses in statute of limitations	(409)		—		—
Ending balance	$	85,845	$	80,604	$	78,665

If we are eventually able to recognize our uncertain tax positions, our effective tax rate may be reduced. We currently have a full valuation allowance against our U.S. net deferred tax asset which would impact the timing of the effective tax rate benefit should any of these uncertain tax positions be favorably settled in the future. Adjustments to the substantial majority of our uncertain tax positions would result in an adjustment of our net operating loss or tax credit carryforwards rather than resulting in a cash outlay.

We file income tax returns in the U.S., California, Alabama, certain other states and India. As a result of our net operating loss and research credit carryforwards, substantially all of our domestic tax years remain open and subject to examination. We may be subject to examination in India from time to time, but we do not believe that any liability resulting from such an examination would have a material effect on our financial position or results of operations.

Our policy is to include interest and penalties related to unrecognized tax benefits, if any, within the provision for income taxes in the consolidated statements of operations. During the years ended December 31, 2022, 2021 and 2020, no significant interest or penalties were recognized relating to unrecognized tax benefits. Although it is reasonably possible that certain unrecognized tax benefits could change in the future, we do not anticipate any significant changes over the next twelve months.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 21
-URI https://asc.fasb.org/extlink&oid=121826272&loc=d3e32857-109319

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 11.C)
-URI https://asc.fasb.org/extlink&oid=122134291&loc=d3e330215-122817

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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-Section 50
-Paragraph 17
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=121826272&loc=d3e32809-109319

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Topic 740
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-Section S99
-Paragraph 1
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-URI https://asc.fasb.org/extlink&oid=122134291&loc=d3e330036-122817

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org/extlink&oid=121826272&loc=d3e32705-109319

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-URI https://asc.fasb.org/topic&trid=2144680

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-Paragraph 2
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-URI https://asc.fasb.org/extlink&oid=6424122&loc=d3e41874-109331

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(h)(2))
-URI https://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

+ Details

Property, Plant and Equipment - Schedule of Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Depreciable property, plant and equipment at cost	$ 154,652	$ 201,386
Less: accumulated depreciation	(124,731)	(148,039)
Depreciable property, plant and equipment, net	29,921	53,347
Construction-in-progress	2,530	7,163
Property, plant and equipment, net	32,451	60,510
Building and leasehold improvements
Property, Plant and Equipment [Line Items]
Depreciable property, plant and equipment at cost	74,889	97,385
Laboratory equipment
Property, Plant and Equipment [Line Items]
Depreciable property, plant and equipment at cost	24,243	42,704
Computer equipment and software
Property, Plant and Equipment [Line Items]
Depreciable property, plant and equipment at cost	26,205	28,829
Manufacturing equipment
Property, Plant and Equipment [Line Items]
Depreciable property, plant and equipment at cost	25,052	22,374
Furniture, fixtures, and other
Property, Plant and Equipment [Line Items]
Depreciable property, plant and equipment at cost	$ 4,263	$ 10,094

CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($)
Statement of Cash Flows [Abstract]
Sale of future royalties transaction costs	$ 3.8

Liabilities Related to the Sales of Future Royalties - Schedule of Liability Related to Potential Future Royalties (Detail) - USD ($) $ in Thousands	12 Months Ended			24 Months Ended	130 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2022	Dec. 31, 2022
Liability Related To Sale Of Future Royalties [Roll Forward]
Liabilities related to the sales of future royalties—beginning balance	$ 198,344				$ 0
Royalty monetization proceeds	0				274,000
Non-cash royalty revenue	(69,794)	$ (77,746)	$ (48,563)		(403,245)
Non-cash interest expense	28,911	47,313	$ 30,267		273,184
Payments to RPI	0				(10,000)
Loss on revaluation of liability related to the sale of future royalties	0				23,522
Liabilities related to the sales of future royalties – ending balance	157,461	198,344		$ 157,461	157,461
Less: unamortized transaction costs	(2,083)			(2,083)	(2,083)
Liabilities related to the sales of future royalties, net	155,378	195,427		155,378	155,378
2012 Purchase and Sale Agreement
Liability Related To Sale Of Future Royalties [Roll Forward]
Liabilities related to the sales of future royalties—beginning balance	78,282				0
Royalty monetization proceeds	0				124,000
Non-cash royalty revenue	(33,865)				(316,523)
Non-cash interest expense	10,750				234,168
Payments to RPI	0				(10,000)
Loss on revaluation of liability related to the sale of future royalties	0				23,522
Liabilities related to the sales of future royalties – ending balance	55,167	78,282		55,167	55,167
Less: unamortized transaction costs	0			0	0
Liabilities related to the sales of future royalties, net	55,167			55,167	55,167
2020 Purchase and Sale Agreement
Liability Related To Sale Of Future Royalties [Roll Forward]
Liabilities related to the sales of future royalties—beginning balance	120,062			0
Royalty monetization proceeds	0			150,000
Non-cash royalty revenue	(35,929)			(86,722)
Non-cash interest expense	18,161			39,016
Payments to RPI	0			0
Loss on revaluation of liability related to the sale of future royalties				0
Liabilities related to the sales of future royalties – ending balance	102,294	$ 120,062		102,294	102,294
Less: unamortized transaction costs	(2,083)			(2,083)	(2,083)
Liabilities related to the sales of future royalties, net	$ 100,211			$ 100,211	$ 100,211

Cover - USD ($) $ in Millions	12 Months Ended
Cover - USD ($) $ in Millions	Dec. 31, 2022	Feb. 21, 2023	Jun. 30, 2022
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2022
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	0-24006
Entity Registrant Name	NEKTAR THERAPEUTICS
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	94-3134940
Entity Address, Address Line One	455 Mission Bay Boulevard South
Entity Address, City or Town	San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94158
City Area Code	415
Local Phone Number	482-5300
Title of 12(b) Security	Common Stock, $0.0001 par value
Trading Symbol	NKTR
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 704
Entity Common Stock, Shares Outstanding (in shares)		189,235,139
Documents Incorporated by Reference	Portions of registrant’s definitive Proxy Statement to be filed for its 2023 Annual Meeting of Stockholders are incorporated by reference into Part III hereof. Such Proxy Statement will be filed with the Securities and Exchange Commission within 120 days of the end of the fiscal year covered by this Annual Report on Form 10-K.
Amendment Flag	false
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	FY
Entity Central Index Key	0000906709

License and Collaboration Agreements - Additional Information (Details) - USD ($) $ in Thousands			1 Months Ended	3 Months Ended	9 Months Ended	12 Months Ended
	Feb. 13, 2018	Jul. 23, 2017	Apr. 30, 2018	Mar. 31, 2022	Dec. 31, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Net expense reimbursements from collaboration partner							$ 21,400
Accounts receivable					$ 5,981	$ 5,981	22,492
Bristol Myers Squibb Collaboration Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Accounts receivable					4,200	4,200
Bristol-Myers Squibb \| Purchase Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Shares issued (in shares)			8,284,600
Sale of stock consideration received			$ 850,000
Other
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential future additional payments for development milestones					40,000	40,000
Nektar 214 \| Bristol-Myers Squibb
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Reimbursement of expenses					$ 20,800
Nektar 214 \| Bristol-Myers Squibb \| Research and Development
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Reimbursement of expenses				$ 24,900		$ 45,700	$ 101,500	$ 128,200
Bristol Myers Squibb Collaboration Agreement \| Nektar 214 \| Bristol-Myers Squibb
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Percentage of sharing production costs	35.00%
Bristol Myers Squibb Collaboration Agreement \| Nektar 214 \| Bristol-Myers Squibb \| Opdivo
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Percentage of sharing development costs	67.50%
Nektar-358 \| Eli Lilly
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Percentage of sharing in Phase 2 development costs		75.00%
Nektar-358 \| Eli Lilly And Company \| Maximum
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential future additional development and regulatory milestones		$ 250,000
Nektar's \| Bristol Myers Squibb Collaboration Agreement \| Nektar 214
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Percentage of sharing production costs	65.00%
Upfront and milestone payments received from license agreements			1,000,000
Nektar's \| Bristol Myers Squibb Collaboration Agreement \| Nektar 214 \| Milestone One
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential future additional payments for development milestones			$ 50,000
Nektar's \| Bristol Myers Squibb Collaboration Agreement \| Nektar 214 \| Opdivo
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Percentage of sharing development costs	32.50%
Nektar's \| Nektar-358
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Received upfront and milestone payment		$ 150,000
Percentage of sharing in Phase 2 development costs		25.00%
Nektar's \| Nektar-358 \| Eli Lilly And Company
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Percentage of regulatory milestones payments will be reduced under certain conditions		50.00%
Percentage of regulatory milestones payments will be reduced if conditions occur		75.00%
Nektar's \| Nektar-358 \| Eli Lilly And Company \| Maximum
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Percentage of funding phase 3 development costs on an indication by indication basis borne		25.00%

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Revenue:
Total revenue	$ 92,055	$ 101,907	$ 152,915
Operating costs and expenses:
Cost of goods sold	21,635	24,897	19,477
Research and development	218,323	400,269	408,678
General and administrative	92,333	122,844	104,682
Restructuring, impairment and other costs of terminated program	135,930	0	45,189
Total operating costs and expenses	468,221	548,010	578,026
Loss from operations	(376,166)	(446,103)	(425,111)
Non-operating income (expense):
Change in fair value of development derivative liability	33,427	(8,023)	0
Non-cash interest expense on liabilities related to the sales of future royalties	(28,911)	(47,313)	(30,267)
Loss on revaluation of liability related to the sale of future royalties	0	(24,410)	0
Interest income and other income (expense), net	6,667	2,569	18,282
Interest expense	0	0	(6,851)
Total non-operating income (expense), net	11,183	(77,177)	(18,836)
Loss before provision for income taxes	(364,983)	(523,280)	(443,947)
Provision for income taxes	3,215	557	493
Net loss	$ (368,198)	$ (523,837)	$ (444,440)
Basic net loss per share (in dollars per share)	$ (1.97)	$ (2.86)	$ (2.49)
Diluted net loss per share (in dollars per share)	$ (1.97)	$ (2.86)	$ (2.49)
Weighted average shares outstanding used in computing basic net loss per share (in shares)	187,138	183,298	178,581
Weighted average shares outstanding used in computing diluted net loss per share (in shares)	187,138	183,298	178,581
Product sales
Revenue:
Total revenue	$ 20,348	$ 23,725	$ 17,504
Royalty revenue
Revenue:
Total revenue	0	0	30,999
Non-cash royalty revenue related to the sales of future royalties
Revenue:
Total revenue	69,794	77,746	48,563
License, collaboration and other revenue
Revenue:
Total revenue	$ 1,913	$ 436	$ 55,849

Operating Leases - Schedule of Operating Lease Information (Details)	12 Months Ended
	Dec. 31, 2022 term
Mission Bay Facility
Leases [Line Items]
Number of consecutive terms to extend lease	2
Lease extension term	5 years
Third Street Facility
Leases [Line Items]
Number of consecutive terms to extend lease	1
Lease extension term	5 years

Organization and Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	Organization We are a research-based biopharmaceutical company headquartered in San Francisco, California and incorporated in Delaware. We are developing a pipeline of drug candidates that utilize our advanced polymer conjugate technology platforms, which are designed to enable the development of new molecular entities that target known mechanisms of action. Our research and development pipeline of new investigational drugs includes innovative medicines in the field of immunotherapy. Our research and development activities have required significant ongoing investment to date and are expected to continue to require significant investment. As a result, we expect to continue to incur substantial losses and negative cash flows from operations in the future. We have financed our operations primarily through cash generated from licensing, collaboration and manufacturing agreements and financing transactions.
Basis of Presentation, Principles of Consolidation and Use of Estimates	Basis of Presentation, Principles of Consolidation and Use of Estimates Our Consolidated Financial Statements include the financial position, results of operations and cash flows of our wholly-owned subsidiaries. We have eliminated all intercompany accounts and transactions in consolidation. Our Consolidated Financial Statements are denominated in U.S. dollars. Accordingly, changes in exchange rates between the applicable foreign currency and the U.S. dollar will affect the translation of each foreign subsidiary’s financial results into U.S. dollars for purposes of reporting our consolidated financial results. We include translation gains and losses in accumulated other comprehensive loss in the stockholders’ equity section of our Consolidated Balance Sheets. To date, such cumulative currency translation adjustments have not been significant to our consolidated financial position. Our comprehensive loss consists of our net loss plus our foreign currency translation gains and losses and unrealized holding gains and losses on available-for-sale securities. There were no significant reclassifications out of accumulated other comprehensive loss to the statements of operations during the years ended December 31, 2022, 2021 and 2020. The preparation of consolidated financial statements in conformity with U.S. generally accepted accounting principles (GAAP) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. Accounting estimates and assumptions are inherently uncertain. Actual results could differ materially from those estimates and assumptions. Our estimates include those related to the selling prices of performance obligations and amounts of variable consideration in collaboration agreements, royalty revenue, and other assumptions required for revenue recognition as described further below; the net realizable value of inventory; the fair value and impairment of investments, goodwill and long-lived assets; contingencies, accrued clinical trial, contract manufacturing and other expenses; income taxes; non-cash royalty revenue and non-cash interest expense from our liabilities related to our sales of future royalties; assumptions used in the valuation of our development derivative liability as further described in Note 6; our assumptions used in stock-based compensation; and ongoing litigation, among other estimates. We base our estimates on historical experience and on other assumptions that management believes are reasonable under the circumstances. These estimates form the basis for making judgments about the carrying values of assets and liabilities when these values are not readily apparent from other sources. As appropriate, we assess estimates each period, update them to reflect current information, and will generally reflect any changes in estimates in the period first identified.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The recorded amounts of certain financial instruments, including cash and cash equivalents, accounts receivable, accounts payable and accrued liabilities approximate their fair values due to their relatively short maturities. We record available-for-sale investments and cash equivalents at their estimated fair values, which are based on market prices from a variety of industry standard data providers and generally represent quoted prices for similar assets in active markets or have been derived from observable market data. As further described in Note 11, we estimated the fair value of our lease assets for recognizing impairment charges based on management’s estimates of several unobservable inputs, including estimated time to enter a sublease, sublease rental rates and free rent periods. As further described in Note 6, we recorded the development derivative liability at its estimated fair value based on management’s estimates of several unobservable inputs, including the probabilities of success of clinical trials and various other inputs. The fair value of our financial assets and liabilities are determined in accordance with the fair value hierarchy established in ASC 820-10, Fair Value Measurements and Disclosures (ASC 820). ASC 820 defines fair value as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The fair value hierarchy of ASC Topic 820 requires an entity to maximize the use of observable inputs when measuring fair value and classifies those inputs into three levels: Level 1 — Quoted prices in active markets for identical assets or liabilities. Level 2 — Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices for identical or similar assets or liabilities in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. For the years ended December 31, 2022 and 2021, there were no transfers between Level 1 and Level 2 of the fair value hierarchy. Level 3 — Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.
Cash, Cash Equivalents, and Investments in Marketable Securities	Cash, Cash Equivalents, and Investments in Marketable Securities We consider all investments in marketable securities with an original maturity of three months or less when purchased to be cash equivalents. We classify investments in securities with remaining maturities of less than one year, or where our intent is to use the investments to fund current operations or to make them available for current operations, as short-term investments. We classify investments in securities with remaining maturities of over one year as long-term investments. Our cash and investments are held or issued by financial institutions that management believes are of high credit quality. However, they are exposed to credit risk in the event of default by the third parties that hold or issue such assets. Our investment policy limits investments to fixed income securities denominated and payable in U.S. dollars such as corporate bonds, corporate commercial paper, U.S. government obligations, and money market funds and places restrictions on maturities and concentrations by type and issuer. For our available-for-sale securities, we have significant concentrations of issuers in the banking and financial services industry. While our investment policy requires that we only invest in highly-rated securities and limit our exposure to any single issuer, a variety of factors may materially affect the financial condition of issuers. Additionally, pursuant to our investment policy, we may sell securities before maturity if the issuer’s credit rating has been downgraded below our minimum credit rating requirements, which may result in a loss on the sale. Accordingly, if factors result in downgrades below our minimum credit rating requirements and if we decide to sell these securities, we may experience losses on such sales. Investments are designated as available-for-sale and are carried at fair value with unrealized gains and losses reported in stockholders’ equity as accumulated other comprehensive income (loss). We review our portfolio of available-for-sale debt securities, using both quantitative and qualitative factors, to determine if declines in fair value below amortized cost have resulted from a credit-related loss or other factors. If the decline in fair value is due to credit-related factors, we recognize a loss in our Consolidated Statement of Operations, whereas if the decline in fair value is not due to credit-related factors, we recognize the loss in other comprehensive income (loss). We include coupon interest on securities classified as available-for-sale, as well as amortization of premiums and accretion of discounts to maturity, in interest income. The cost of securities sold is based on the specific identification method.
Accounts Receivable and Significant Customer Concentrations	Accounts Receivable and Significant Customer Concentrations Our customers are primarily pharmaceutical and biotechnology companies that are primarily located in the U.S. and Europe and with whom we have multi-year arrangements. Our accounts receivable balance contains billed and unbilled trade receivables from product sales, milestones (to the extent that they have been achieved and are due from the counterparty), other contingent payments, as well as reimbursable costs from collaborative research and development agreements.We perform a regular review of our partners’ credit risk and payment histories when circumstances warrant, including payments made subsequent to year-end. When appropriate, we provide for an allowance for doubtful accounts by reserving for specifically identified doubtful accounts, although historically we have not experienced credit losses from our accounts receivable.
Inventory and Significant Supplier Concentrations	Inventory and Significant Supplier Concentrations We generally manufacture inventory upon receipt of firm purchase orders from our collaboration partners, and we may manufacture certain intermediate work-in-process materials and purchase raw materials based on purchase forecasts from our collaboration partners. Inventory includes direct materials, direct labor, and manufacturing overhead, and we determine cost on a first-in, first-out basis for raw materials and on a specific identification basis for work-in-process and finished goods. We value inventory at the lower of cost or net realizable value, and we write down defective or excess inventory to net realizable value based on historical experience or projected usage. We expense inventory related to our research and development activities when we purchase or manufacture it. We are dependent on our suppliers and contract manufacturers to provide raw materials and drugs of appropriate quality and reliability and to meet applicable contract and regulatory requirements. In certain cases, we rely on single sources of supply of one or more critical materials. Consequently, in the event that supplies are delayed or interrupted for any reason, our ability to develop and produce our drug candidates, our ability to supply comparator drugs for our clinical trials, or our ability to meet our supply obligations could be significantly impaired, which could have a material adverse effect on our business, financial condition and results of operations.
Restructuring	Restructuring We recognize restructuring charges related to reorganization plans that have been committed to by management when liabilities have been incurred. In connection with these activities, we record restructuring charges at fair value for: •contractual employee termination benefits provided that the obligations result from services already rendered based on vested rights to such benefits when the payment of benefits becomes probable and the amount can be reasonably estimated; •one-time employee termination benefits on the communication date from management to the employees provided that management has committed to a plan of termination, the plan identifies the employees and their expected termination dates, the details of termination benefits are complete, and it is unlikely that changes to the plan will be made or the plan will be withdrawn; •contract termination costs when we cancel the contract in accordance with its terms; and •costs to be incurred over the remaining contract term without economic benefit to us at the cease-use date. For one-time employee terminations benefits, we recognize the liability in full on the communication date when future services are not required or amortize the liability ratably over the service period, if required. The fair value of termination benefits reflects our estimates of expected utilization of certain Company-funded post-employment benefits.
Long-Lived Assets	Long-Lived Assets We report property, plant and equipment at cost, net of accumulated depreciation. We capitalize major improvements and expense maintenance and repairs as incurred. We generally recognize depreciation on a straight-line basis. We depreciate manufacturing, laboratory and other equipment over their estimated useful lives of generally three to ten years, depreciate buildings over the estimated useful life of generally twenty years and amortize leasehold improvements over the shorter of the estimated useful lives or the remaining term of the related lease. Goodwill represents the excess of the price paid for another entity over the fair value of the assets acquired and liabilities assumed in a business combination. We are organized in one reporting unit and evaluate the goodwill for the Company as a whole. Goodwill has an indefinite useful life and is not amortized, but instead tested for impairment at least annually in the fourth quarter of each year using an October 1 measurement date. We assess the impairment of long-lived assets whenever events or changes in business circumstances indicate that the carrying amounts of the assets may not be fully recoverable. In the case of property, plant and equipment and right-of-use assets for our leases, we determine whether there has been an impairment by comparing the carrying value of the asset to the anticipated undiscounted net cash flows associated with the asset. If such cash flows are less than the carrying value, we write down the asset to its fair value, which may be measured as anticipated discounted net cash flows associated with the asset. In the case of goodwill impairment, we compare the carrying value of the reporting unit to its fair value, which we generally measure using market capitalization for our single reporting unit. If an impairment exists, we write down goodwill such that the carrying value of the reporting unit equals its fair value.
Leases	Leases We determine if an arrangement contains a lease at the inception of the arrangement. Right-of-use assets represent our right to use an underlying asset for the lease term, and lease liabilities represent our obligation to make lease payments arising from the lease. We recognize operating lease right-of-use assets and liabilities at the lease commencement date based on the present value of lease payments over the expected lease term. In determining the present value of lease payments, we use our incremental borrowing rate based on the information available at the lease commencement date. We have elected the practical expedient to account for the lease and non-lease components, such as common area maintenance charges, as a single lease component for our facilities leases, and elected the short-term lease recognition exemption for our short-term leases, under which we do not recognize lease liabilities and right-of-use assets for leases with an original term of twelve months or less. Our expected lease terms may include options to extend or terminate the lease when it is reasonably certain that we will exercise any such options. We recognize lease expense for our operating leases on a straight-line basis over the expected lease term. We have elected to recognize lease incentives, such as tenant improvement allowances, at the lease commencement date as a reduction of the right-of-use asset and lease liability until paid to us by the lessor to the extent that the lease provides a specified fixed or maximum level of reimbursement and we are reasonably certain to incur reimbursable costs at least equaling such amounts. Please see Note 5 for additional information regarding our leases.
Collaborative Arrangements	Collaborative Arrangements We enter into collaboration arrangements with pharmaceutical and biotechnology collaboration partners, under which we may grant licenses to our collaboration partners to further develop and commercialize one of our drug candidates, either alone or in combination with the collaboration partners’ compounds, or grant licenses to partners to use our technology to research and develop their own drug candidates. We may also perform research, development, manufacturing and supply activities under our collaboration agreements. Consideration under these contracts may include an upfront payment, development and regulatory milestones and other contingent payments, expense reimbursements, royalties based on net sales of approved drugs, and commercial sales milestone payments. Additionally, these contracts may provide options for the customer to purchase our proprietary PEGylation materials, drug candidates or additional contract research and development services under separate contracts. When we enter into collaboration agreements, we assess whether the arrangements fall within the scope of ASC 808, Collaborative Arrangements (ASC 808) based on whether the arrangements involve joint operating activities and whether both parties have active participation in the arrangement and are exposed to significant risks and rewards of the arrangement. To the extent that the arrangement falls within the scope of ASC 808, we assess whether the payments between us and our collaboration partner fall within the scope of other accounting literature. If we conclude that payments from the collaboration partner to us represent consideration from a customer, such as license fees and contract research and development activities, we account for those payments within the scope of ASC 606, Revenue from Contracts with Customers (ASC 606). However, if we conclude that our collaboration partner is not a customer for certain activities and associated payments, such as for certain collaborative research, development, manufacturing and commercial activities, we present such payments as a reduction of research and development expense or general and administrative expense, based on where we present the underlying expense.
Revenue Recognition	Revenue Recognition For elements of those arrangements that we determine should be accounted for under ASC 606, we assess which activities in our collaboration agreements are performance obligations that should be accounted for separately and determine the transaction price of the arrangement, which includes the assessment of the probability of achievement of future milestones and other potential consideration. For arrangements that include multiple performance obligations, such as granting a license or performing contract research and development activities or participation on joint steering or other committees, we allocate upfront and milestone payments under a relative standalone selling price method. Accordingly, we develop assumptions that require judgment to determine the standalone selling price for each performance obligation identified in the contract. These key assumptions may include revenue forecasts, clinical development timelines and costs, discount rates and probabilities of clinical and regulatory success. Product sales Product sales are primarily derived from manufacturing and supply agreements with our customers. We have assessed our current manufacturing and supply arrangements and have generally determined that they provide the customer an option to purchase our proprietary PEGylation materials. Accordingly, we treat each purchase order as a discrete exercise of the customer’s option (i.e. a separate contract) rather than as a component of the overall arrangement. The pricing for the manufacturing and supply is generally at a fixed price and may be subject to annual producer price index (PPI) adjustments. We invoice and recognize product sales when title and risk of loss pass to the customer, which generally occurs upon shipment. Customer payments are generally due 30 days from receipt of an invoice. We test our products for adherence to technical specifications before shipment; accordingly, we have not experienced any significant returns from our customers. We recognize costs related to shipping and handling of product to customers in cost of goods sold. Royalty revenue, including Non-cash royalty revenue Generally, for our collaboration arrangements that include sales-based royalties, we have granted our collaboration partner a license to our intellectual property. Pursuant to these arrangements, our collaboration partners are typically obligated to pay a royalty that is based on the net sales of their approved drugs that are sold in the countries where we have intellectual property rights covering their drugs. We have sold our rights to receive sales-based royalties for CIMZIA®, MIRCERA®, MOVANTIK®, ADYNOVATE® and REBINYN® as further described in Note 7. For collaboration arrangements that include sales-based royalties, we have concluded that the license is the predominant item to which the royalties relate, which include commercial milestone payments based on the level of sales. Accordingly, we recognize royalty revenue when the underlying sales occur based on our best estimates of sales of the drugs. Our aggregate royalty and non-cash royalty revenue of $69.8 million, $77.7 million and $79.6 million for the years ended December 31, 2022, 2021 and 2020, respectively, represents revenue for granting licenses for which we had satisfied in prior periods. Our partners generally pay royalties or commercial milestones after the end of the calendar quarter in accordance with contractual terms. We present commercial milestone payments within license, collaboration and other revenue. License, collaboration and other revenue License Grants: For collaboration arrangements that include a grant of a license to our intellectual property, we consider whether the license grant is distinct from the other performance obligations included in the arrangement. Generally, we would conclude that the license is distinct if the customer is able to benefit from the license with the resources available to it. For licenses that are distinct, we recognize revenues from nonrefundable, upfront payments and other consideration allocated to the license when the license term has begun and we have provided all necessary information regarding the underlying intellectual property to the customer, which generally occurs at or near the inception of the arrangement. Milestone Payments: At the inception of the arrangement and at each reporting date thereafter, we assess whether we should include any milestone payments or other forms of variable consideration in the transaction price, based on whether a significant reversal of revenue previously recognized is not probable upon resolution of the uncertainty. Since milestone payments may become payable to us upon the initiation of a clinical study, filing for or receipt of regulatory approval or the first commercial sale of a product, we review the relevant facts and circumstances to determine when we should update the transaction price, which may occur before the triggering event. When we do update the transaction price for milestone payments, we allocate it on a relative standalone selling price basis and record revenue on a cumulative catch-up basis, which results in recognizing revenue for previously satisfied performance obligations in such period. As described further in Note 10, we recognized $50.0 million of milestones in the year ended December 31, 2020 because we had previously satisfied the performance obligation. If we update the transaction price before the triggering event, we recognize the increase in the transaction price as a contract asset. Our partners generally pay development milestones subsequent to achievement of the triggering event. Research and Development Services: For amounts allocated to our research and development obligations in a collaboration arrangement, we recognize revenue over time using a proportional performance model, representing the transfer of goods or services as we perform activities over the term of the agreement.
Research and Development Expense	Research and Development Expense Research and development costs are expensed as incurred and include salaries, benefits and other operating costs such as outside services, supplies and allocated overhead costs. We perform research and development activities for our drug candidates and technology development and for certain third parties under collaboration agreements. For our drug candidates and our internal technology development programs, we invest our own funds without reimbursement from a third party. Where we perform research and development activities under a joint development collaboration, such as our collaboration with BMS, we record the cost reimbursement from our partner as a reduction to research and development expense when reimbursement amounts are due to us under the agreement. We record an accrued expense for the estimated unbilled costs of our clinical study activities performed by third parties. The financial terms of these agreements are subject to negotiation, vary from contract to contract and may result in uneven payment flows to our vendors. Payments under the contracts depend on factors such as the achievement of certain events, successful enrollment of patients and completion of certain clinical trial activities. We generally recognize costs associated with the start-up and reporting phases of the clinical trials as incurred. We generally accrue costs associated with the treatment phase of clinical trials based on the estimated activities performed by our third party vendors, including our contract research organizations. We may also accrue expenses based on the total estimated cost of the treatment phase on a per patient basis and expense the per patient cost ratably over the estimated patient treatment period. In specific circumstances, such as for certain time-based costs, we recognize clinical trial expenses ratably over the service period, as we believe that this methodology may be more reflective of the timing of costs incurred. We record an accrued expense for the estimated costs of our contract manufacturing activities performed by third parties. The financial terms of these agreements are subject to negotiation, vary from contract to contract and may result in uneven payment flows to our vendors. Payments under the contracts include upfront payments and milestone payments, which depend on factors such as the achievement of the completion of certain stages of the manufacturing process. For purposes of recognizing expense, we assess whether we consider the production process to be sufficiently defined such that the resulting product can be considered the delivery of a good, as evidenced by predictive or contractually required yields in the production process or payment terms based on the actual yield, or the delivery of a service, where processes and yields are developing and less certain. If we consider the process to be the delivery of a good, we recognize expense when the drug product is delivered, or we otherwise bear risk of loss. If we consider the process to be the delivery of a service, we recognize expense based on our best estimates of the contract manufacturer’s progress towards completion of the stages in the contracts. We recognize and amortize upfront payments and accrue liabilities based on the specific terms of each arrangement. Certain arrangements may provide upfront payments for certain stages of the arrangement and milestone payments for the completion of certain stages, and, accordingly, we may record advance payments for services that have not been completed or goods not delivered and liabilities for stages where the contract manufacturer is entitled to a milestone payment. We capitalize advance payments for goods or services that will be used or rendered for future research and development activities and recognize expense as the related goods are delivered or services performed. We base our estimates on the best information available at the time. However, additional information may become available to us in the future which may allow us to make a more accurate estimate in future periods. In this event, we may be required to record adjustments to research and development expenses in future periods when the actual level of activity becomes more certain. We generally consider such increases or decreases in cost as changes in estimates and reflect them in research and development expenses in the period identified.
Restructuring, Impairment and Other Costs for Terminated Program	Restructuring, Impairment and Other Costs for Terminated Program Amounts recorded as restructuring, impairment and other costs for terminated program for the year ended December 31, 2022 relate to the termination of the bempegaldesleukin program and the 2022 Restructuring Plan. See Note 11 for additional information. Amounts recorded as restructuring, impairment and other costs for terminated program for the year ended December 31, 2020 relate to the termination of the NKTR-181 program. On January 14, 2020, the joint FDA Anesthetic Drug Products Advisory Committee and Drug Safety and Risk Management Committee did not recommend approval of our NDA for NKTR-181. As a result, we withdrew our NDA and wound down Inheris and the NKTR-181 program.
Stock-Based Compensation	Stock-Based Compensation Stock-based compensation arrangements include grants of stock options, restricted stock units (RSUs), performance stock units (PSUs) under our equity incentive plans, as well as shares issued under our Employee Stock Purchase Plan (ESPP), through which employees may purchase our common stock at a discount to the market price. We expense the grant date fair value of options, RSUs, PSUs and ESPP shares on a straight-line basis over the requisite service periods in our Consolidated Statements of Operations and recognize forfeitures of options, RSUs and PSUs as they occur. For options and RSUs that vest upon the achievement of performance milestones, we recognize expense provided that we believe that the performance milestones are probable of achievement, and we estimate the vesting period based on our evaluation of the estimated date of achievement of these milestones. For PSUs, we recognize expense based on the grant date fair value regardless of whether the market condition is met. Additionally, we do not adjust the expense based on the number of shares ultimately issued, which may be higher or lower than the grant amount. We report expense amounts in cost of goods sold, research and development expense, and general and administrative expense based on the function of the applicable employee. Stock-based compensation charges are non-cash charges and have no effect on our reported cash flows. We estimate the grant date fair value of our stock-based compensation awards as follows: •We use the Black-Scholes option pricing model for the respective grant to determine the estimated fair value of the option on the date of grant (grant date fair value) and the estimated fair value of common stock purchased under the ESPP. The Black-Scholes option pricing model requires the input of highly subjective assumptions, including but not limited to, our stock price volatility over the term of the awards, and actual and projected employee stock option exercise behaviors. •The number of shares issuable under PSUs is based on our total shareholder return as compared to other companies within the Nasdaq biotechnology index over the measurement period and may be capped based on our absolute total shareholder return over such period. We use the Monte Carlo simulation model to determine the estimated grant date fair value. The Monte Carlo simulation model incorporates assumptions such as the volatility of our stock, the volatility of the stock of other peer companies within the index, and the correlation of both our stock and our peer companies’ stock to the index. •The fair value of an RSU is equal to the closing price of our common stock on the grant date.
Income Taxes	Income Taxes We account for income taxes under the liability method. Under this method, we determine deferred tax assets and liabilities based on differences between the financial reporting and tax reporting bases of assets and liabilities, measured using enacted tax rates and laws that we expect to be in effect when we expect the differences to reverse. Realization of deferred tax assets is dependent upon future earnings, the timing and amount of which are uncertain. We record a valuation allowance against deferred tax assets to reduce their carrying value to an amount that is more likely than not to be realized. When we establish or reduce the valuation allowance related to the deferred tax assets, our provision for income taxes will increase or decrease, respectively, in the period we make such determination. We utilize a two-step approach to recognize and measure uncertain tax positions. The first step is to evaluate the tax position for recognition by determining if the weight of available evidence indicates that it is more likely than not that the position will be sustained upon tax authority examination, including resolution of related appeals or litigation processes, if any. The second step is to measure the tax benefit as the largest amount of benefit, determined on a cumulative probability basis, that is more than 50% likely of being realized upon ultimate settlement. For the years ended December 31, 2022, 2021 and 2020, our income tax provision primarily relates to our Nektar India subsidiary. As a result of the 2022 Restructuring Plan and our intent to wind down our foreign subsidiaries, we have recorded a provision for the repatriation of accumulated earnings and profits from India. See Note 13 for additional information.
Net Loss Per Share	Net Loss Per Share For all periods presented in the Consolidated Statements of Operations, the net loss available to common stockholders is equal to the reported net loss. We calculate basic net loss per share based on the weighted-average number of common shares outstanding during the periods presented.
Comprehensive Loss	Comprehensive Loss Comprehensive loss is the change in stockholders’ equity from transactions and other events and circumstances other than those resulting from investments by stockholders and distributions to stockholders. Our comprehensive loss includes our net loss, gains and losses from the foreign currency translation of the assets and liabilities of our foreign subsidiaries, and unrealized gains and losses on investments in available-for-sale securities.
Recent Accounting Pronouncements	Recent Accounting Pronouncements We have reviewed recent accounting pronouncements and concluded they are either not applicable to us or that we do not expect adoption to have a material effect on our consolidated financial statements.

License and Collaboration Agreements - License, Collaboration and Other Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
License And Collaboration Agreements [Line Items]
License, collaboration and other revenue	$ 1,913	$ 436	$ 55,849
Bristol-Myers Squibb \| Bempegaldesleukin
License And Collaboration Agreements [Line Items]
License, collaboration and other revenue	0	0	50,000
Other
License And Collaboration Agreements [Line Items]
License, collaboration and other revenue	$ 1,913	$ 436	$ 5,849

Income Taxes - Schedule of Income Tax Provision Related to Continuing Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income tax benefit at federal statutory rate	$ (76,647)	$ (109,889)	$ (93,229)
Research credits	(987)	(4,727)	(3,081)
Change in valuation allowance	51,108	97,914	87,060
Expiration of net operating loss carryforwards	12,348	286	286
Stock-based compensation	15,778	6,627	7,929
Non-cash interest expense on liability related to sales of future royalties	6,071	9,936	6,356
Non-cash royalty revenue related to sales of future royalties	(7,112)	(7,891)	(7,967)
Loss on revaluation of liability related to the sale of future royalties	0	4,940	0
Other	2,656	3,361	3,139
Provision for income taxes	$ 3,215	$ 557	$ 493

Restructuring, Impairment and Other Costs of Terminated Program - Restructuring Reserve Rollforward (Details) $ in Thousands	3 Months Ended
	Sep. 30, 2022 USD ($)
Employee Severance
Restructuring Reserve [Roll Forward]
Liability balance as of March 31, 2022	$ 0
Expense recognized during the period	30,904
Payments during the period	(27,605)
Liability balance as of December 31, 2022	3,299
No service period
Restructuring Reserve [Roll Forward]
Liability balance as of March 31, 2022	0
Expense recognized during the period	22,993
Payments during the period	(22,993)
Liability balance as of December 31, 2022	0
Service period required
Restructuring Reserve [Roll Forward]
Liability balance as of March 31, 2022	0
Expense recognized during the period	7,911
Payments during the period	(4,612)
Liability balance as of December 31, 2022	$ 3,299

Stock-Based Compensation - Additional Information (Details)	12 Months Ended
	Dec. 31, 2022 USD ($) $ / shares shares	Dec. 31, 2021 USD ($) $ / shares	Dec. 31, 2020 USD ($) $ / shares	Jun. 08, 2022 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Change in control severance payment period for executives	12 months
Total unrecognized compensation costs	$ 83,100,000
Recognized over a weighted-average period	2 years 3 months 18 days
Dividend yield	0.00%	0.00%	0.00%
Total intrinsic value of options exercised		$ 17,300,000	$ 15,900,000
Maximum 401(k) per employee, percentage of annual salary	60.00%
Matching 401(k) employer contribution, maximum amount	$ 12,000	6,000	6,000
Compensation expense in connection with 401(k) retirement plan	$ 2,500,000	$ 3,600,000	$ 3,500,000
2017 Performance Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized \| shares	39,200,000			5,000,000
Share-based compensation plan's share limit reduction for every one restricted stock unit granted	1.5
Stock options term under equity incentive plans	8 years
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield	0.00%
Stock Options \| 2017 Performance Incentive Plan \| Employee
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Service period for stock-based compensation award granted	4 years
Stock Options \| 2017 Performance Incentive Plan \| Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Service period for stock-based compensation award granted	1 year
RSUs and PSUs \| 2017 Performance Incentive Plan \| Employee
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Service period for stock-based compensation award granted	3 years
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Offering period	6 months
Employee Stock Purchase Plan \| Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Purchase price of common stock, percent	85.00%
Number of common stock shares available for stock options grants (in shares) \| shares	3,500,000
Restricted Stock Units (RSU)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in dollars per share) \| $ / shares	$ 4.14	$ 14.68	$ 19.24
Fair value of restricted stock vested	$ 17,500,000	$ 45,300,000	$ 33,300,000

Restructuring, Impairment and Other Costs of Terminated Program - Summary of Restructuring Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Restructuring and Related Activities [Abstract]
Clinical trial expense, other third-party and employee costs for the wind down of the bempegaldesleukin program	$ 31,693
Severance and benefit expense	30,904
Impairment of right-of-use assets and property, plant and equipment	65,761	$ 0	$ 0
(Gain) loss on sale or disposal of property, plant and equipment, net	(3,326)	$ 0	$ 0
Contract termination and other restructuring costs	10,898
Restructuring, impairment and other costs of terminated program	$ 135,930

Operating Leases - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($) ft²	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Leases [Line Items]
Impairment of right-of-use assets and property, plant and equipment	$ 65,761	$ 0	$ 0
Operating lease, payments	$ 20,100	$ 16,800	$ 16,200
Weighted average remaining lease term	7 years 1 month 6 days
Weighted average discount rate, percent	5.80%
Subleases aggregate lease payments	$ 10,500
Sublease Property, Plant And Equipment
Leases [Line Items]
Impairment of right-of-use assets and property, plant and equipment	$ 54,590
Mission Bay Facility
Leases [Line Items]
Lease space (in sq ft) \| ft²	155,215
Third Street Facility
Leases [Line Items]
Lease space (in sq ft) \| ft²	135,936

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2022

Income Tax Disclosure [Abstract]

Schedule of Income Before Income Tax, Domestic and Foreign

Loss before provision for income taxes includes the following components (in thousands):


	Year Ended December 31,
	2022		2021		2020
Domestic	$	(371,900)	$	(524,440)	$	(445,370)
Foreign	6,917		1,160		1,423
Loss before provision for income taxes	$	(364,983)	$	(523,280)	$	(443,947)

Schedule of Provision for Income Taxes

The provision for income taxes consists of the following (in thousands):


	Year Ended December 31,
	2022		2021		2020
Current:
Federal	$	—	$	—	$	—
State	(608)		50		165
Foreign	1,115		609		364
Total current income tax expense	507		659		529
Deferred:
Federal	—		—		—
State	—		—		—
Foreign	2,708		(102)		(36)
Total deferred income tax expense	2,708		(102)		(36)
Provision for income taxes	$	3,215	$	557	$	493

Schedule of Income Tax Provision Related to Continuing Operations

Our income tax provision related to continuing operations differs from the amount computed by applying the statutory income tax rate of 21% to our pretax loss as follows (in thousands):


	Year Ended December 31,
	2022		2021		2020
Income tax benefit at federal statutory rate	$	(76,647)	$	(109,889)	$	(93,229)
Research credits	(987)		(4,727)		(3,081)
Change in valuation allowance	51,108		97,914		87,060
Expiration of net operating loss carryforwards	12,348		286		286
Stock-based compensation	15,778		6,627		7,929
Non-cash interest expense on liability related to sales of future royalties	6,071		9,936		6,356
Non-cash royalty revenue related to sales of future royalties	(7,112)		(7,891)		(7,967)
Loss on revaluation of liability related to the sale of future royalties	—		4,940		—
Other	2,656		3,361		3,139
Provision for income taxes	$	3,215	$	557	$	493

Schedule of Significant Components of Deferred Tax Assets and Liabilities

We measure deferred tax assets and liabilities based on the rates at which they are expected to reverse in the future. Significant components of our deferred tax assets for federal and state income taxes are as follows (in thousands):


	December 31,
	2022		2021
Deferred tax assets:
Net operating loss carryforwards	$	545,508	$	564,712
Research and other credits	142,198		139,996
Net capital loss carryforwards	38,445		—
Operating lease liabilities	28,254		34,680
Stock-based compensation	22,110		33,408
Capitalized research and development costs	24,134		—
Liability related to the sale of future royalties	13,424		23,757
Other	13,935		17,290
Deferred tax assets before valuation allowance	828,008		813,843
Valuation allowance for deferred tax assets	(816,235)		(785,748)
Total deferred tax assets	11,773		28,095
Deferred tax liabilities:
Operating lease right-of-use assets	(11,335)		(27,204)
Investment in foreign subsidiary	(2,451)		—
Other	(392)		(564)
Total deferred tax liabilities	(14,178)		(27,768)
Net deferred tax assets (liabilities)	$	(2,405)	$	327

Schedule of Unrecognized Tax Benefits

We have the following activity relating to unrecognized tax benefits (in thousands):


	Year Ended December 31,
	2022		2021		2020
Beginning balance	$	80,604	$	78,665	$	77,410
Tax positions related to current year:
Additions	378		2,371		2,512
Reductions	—		—		—
Tax positions related to prior years:
Additions	5,272		58		193
Reductions	—		(490)		(1,450)
Settlements	—		—		—
Lapses in statute of limitations	(409)		—		—
Ending balance	$	85,845	$	80,604	$	78,665

Operating Leases

12 Months Ended

Dec. 31, 2022

Leases [Abstract]

Operating Leases

Our leases consist of a Lease Agreement (the Mission Bay Lease) with ARE-San Francisco No. 19, LLC (ARE) for our 155,215 square foot corporate office and R&D facility located at 455 Mission Bay Boulevard South, San Francisco, California (the Mission Bay Facility) and a Lease Agreement (the Third Street Lease) with Kilroy Realty Finance Partnership, L.P. (Kilroy) for an additional 135,936 square foot of office space at 360 Third Street, San Francisco, California (the Third Street Facility). The following table presents key information regarding these leases (dollars in thousands):


	Mission Bay Facility	Third Street Facility
Lease commencement	September 2017	June 2018
Lease term	January 2030	January 2030
Renewal terms	Two consecutive five-year terms	One five-year term

•The monthly base rent for both facilities will escalate over the term of the lease at various intervals.

•Both leases include various covenants, indemnities, defaults, termination rights, security deposits and other provisions customary for lease transactions of this nature.

•During the term of the Mission Bay Lease, we are responsible for paying our share of operating expenses specified in the lease, including utilities, common area maintenance, insurance costs and taxes.

•For the Third Street Lease, our fixed annual base rent on an industrial gross lease basis includes certain expenses and property taxes paid directly by the landlord. We have a one-time right of first offer with respect to certain additional rental space at the Third Street Facility.

Due to our 2022 Restructuring Plan, during the year ended December 31, 2022, we recorded impairment charges of $54.6 million for our right-of-use assets which we are seeking to sublease. See Note 11 for additional information.

We generally recognize lease expense for our operating leases on a straight-line basis over the lease term, and we continue to recognize lease expense on a straight-line basis for spaces for which we did not recognize an impairment. For spaces where we did recognize an impairment charge, the aggregate lease expense recognized over the remaining term is reduced by the amount of the impairment charge, but we recognize the remaining lease expense on an accelerated basis. The components of lease expense, which we include in operating expenses in our Consolidated Statements of Operations, were as follows (in thousands):


	Year Ended December 31,
	2022		2021		2020
Operating lease expense	$	17,057	$	19,153	$	18,985
Variable lease expense	10,700		8,974		8,179
Total lease expense	$	27,757	$	28,127	$	27,164

During the years ended December 31, 2022, 2021 and 2010, we paid $20.1 million, $16.8 million and $16.2 million, respectively, of operating lease payments related to our lease liabilities, which we include in net cash used in operating activities in our Consolidated Statements of Cash Flows.

As of December 31, 2022, the maturities of our operating lease liabilities were as follows (in thousands):


Year ending December 31,
2023	$	19,216
2024	21,572
2025	22,254
2026	22,958
2027	23,681
2028 and thereafter	51,732
Total lease payments	161,413
Less: portion representing interest	(29,917)
Operating lease liabilities	131,496
Less: current portion	(18,667)
Operating lease liabilities, less current portion	$	112,829

As of December 31, 2022, the weighted-average remaining lease term is 7.1 years and the weighted-average discount rate used to determine the operating lease liability was 5.8%.

We have entered into subleases for certain spaces that provide recovery of $10.5 million in aggregate lease payments, as well as the subtenants' share of operating expenses. The reduction to lease expense for the year ended December 31, 2022, was not significant but will increase in future periods.

Restructuring, Impairment and Other Costs of Terminated Program - Schedule of Property, Plant and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Restructuring Cost and Reserve [Line Items]
Proceeds from sales	$ 13,196	$ 0	$ 0
Property, plant and equipment, net	32,451	$ 60,510
Facility Closing
Restructuring Cost and Reserve [Line Items]
Proceeds from sales	13,196
Property, plant and equipment, net	9,870
Total (gain) loss on sale or disposal of property, plan and equipment, net	$ (3,326)

Income Taxes - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Taxes Disclosure [Line Items]
Increase in valuation allowance	$ 30,500	$ 115,600
Operating loss carryforwards, subject to expiration	1,300,000
Income tax research credits	987	4,727	$ 3,081
Unrecognized tax benefits, interest recognized	0	0	0
Unrecognized tax benefits, penalties recognized	$ 0	$ 0	$ 0
Unrecognized tax benefits, period may increase or decrease due to tax examination	12 months
Federal
Income Taxes Disclosure [Line Items]
Operating loss carryforwards	$ 2,400,000
Income tax research credits	123,800
State
Income Taxes Disclosure [Line Items]
Operating loss carryforwards	700,000
Income tax research credits	$ 48,800

Co-Development Agreement with SFJ Pharmaceuticals and Development Derivative Liability (Tables)

12 Months Ended

Dec. 31, 2022

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of Derivative Liabilities at Fair Value

The following table presents the changes in the development derivative liability:


		Year Ended December 31,
	Fair Value Hierarchy Level	2022		2021
Fair value as of December 31, 2021 and February 12, 2021 (inception), respectively	3	$	27,726	$	—
Non-cash research and development expense		4,951		16,703
Cash receipts from SFJ		750		3,000
Change in the fair value of development derivative liability		(33,427)		8,023
Fair value at end of period	3	$	—	$	27,726

Cash and Investments in Marketable Securities - Schedule of Portfolio of Cash and Investments in Marketable Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	$ 429,502
Gross Unrealized Gains	25
Gross Unrealized Losses	(1,801)	$ (700)
Fair Value	427,726	762,625
Cash	8,798	1,250
Total cash and investments in marketable securities	504,977	798,783
Corporate notes and bonds \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	84,377
Gross Unrealized Gains	0
Gross Unrealized Losses	(855)
Fair Value	83,522	278,121
Corporate commercial paper \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	345,125
Gross Unrealized Gains	25
Gross Unrealized Losses	(946)
Fair Value	344,204	478,629
Obligations of U.S. government agencies \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	0
Gross Unrealized Gains	0
Gross Unrealized Losses	0
Fair Value	0	5,875
Money market funds \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in marketable securities	47,054	23,968
Certificates of deposit \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in marketable securities	$ 21,399	$ 10,940

Stockholders' Equity - Additional Information (Details) - USD ($)	Apr. 03, 2018	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Class of Stock [Line Items]
Stock issued during period subject to lock-up and stand-still provisions period	5 years
Aggregate offering price		$ 300,000,000
Losses recorded in AOCI		(366,638,000)	$ (679,508,000)	$ (1,077,295,000)	$ (1,405,391,000)
Common Stock
Class of Stock [Line Items]
Sale of stock to Bristol-Myers Squibb (in shares)	8,284,600
Losses recorded in AOCI		(19,000)	$ (19,000)	$ (18,000)	$ (17,000)
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-Sale, Parent
Class of Stock [Line Items]
Losses recorded in AOCI		1,800,000
Accumulated Foreign Currency Adjustment Attributable to Parent
Class of Stock [Line Items]
Losses recorded in AOCI		$ 5,100,000

- Definition

+ References

+ Details

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended			130 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2022
Cash flows from operating activities:
Net loss	$ (368,198)	$ (523,837)	$ (444,440)
Adjustments to reconcile net loss to net cash used in operating activities:
Non-cash royalty revenue related to the sales of future royalties	(69,794)	(77,746)	(48,563)	$ (403,245)
Non-cash interest expense on liabilities related to sales of future royalties	28,911	47,313	30,267	273,184
Loss on revaluation of liability related to the sale of future royalties	0	24,410	0
Change in fair value of development derivative liability	(33,427)	8,023	0
Non-cash research and development expense	4,951	16,703	0
Stock-based compensation	57,320	94,674	94,261
Depreciation and amortization	13,030	14,146	14,182
Deferred income tax expense	2,708	(102)	(36)
Impairment of right-of-use assets and property, plant and equipment	65,761	0	0
(Gain) loss on sale or disposal of property, plant and equipment, net	(3,326)	0	0
Impairment of advance payments to contract manufacturers and equipment for terminated program	0	0	20,351
Amortization of premiums (discounts), net and other non-cash transactions	(2,435)	6,730	3,943
Changes in operating assets and liabilities:
Accounts receivable	16,511	12,397	1,913
Inventory	(3,401)	(509)	(2,627)
Operating leases, net	(2,680)	2,340	2,743
Other assets	6,906	(2,586)	4,512
Accounts payable	3,103	(11,690)	2,382
Accrued compensation	(6,153)	1,203	4,697
Other accrued expenses	(12,734)	(23,524)	8,644
Deferred revenue	(1,060)	(605)	(5,516)
Net cash used in operating activities	(304,007)	(412,660)	(313,287)
Cash flows from investing activities:
Purchases of investments	(467,914)	(960,689)	(987,533)
Maturities of investments	826,229	1,166,951	1,449,304
Sales of investments	0	11,504	41,700
Purchases of property, plant and equipment	(5,676)	(14,989)	(7,258)
Sales of property, plant and equipment	13,196	0	0
Net cash provided by investing activities	365,835	202,777	496,213
Cash flows from financing activities:
Proceeds from sale of future royalties, net of $3.8 million of transaction costs	0	0	146,250
Repayment of senior notes	0	0	(250,000)
Cash receipts from development derivative liability	750	3,000	0
Proceeds from shares issued under equity compensation plans	758	33,238	23,396
Net cash provided by (used in) financing activities	1,508	36,238	(80,354)
Effect of foreign exchange rates on cash and cash equivalents	(327)	(92)	20
Net increase (decrease) in cash and cash equivalents	63,009	(173,737)	102,592
Cash and cash equivalents at beginning of year	25,218	198,955	96,363
Cash and cash equivalents at end of year	88,227	25,218	198,955	$ 88,227
Supplemental disclosure of cash flow information:
Cash paid for interest	0	0	9,742
Cash paid for income taxes	272	325	539
Operating lease right-of-use assets recognized in exchange for lease liabilities	0	1,057	2,133
Accounts receivable recognized in exchange for long-term liabilities	$ 0	$ 0	$ 4,000

Income Taxes - Schedule of Significant Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Deferred tax assets:
Net operating loss carryforwards	$ 545,508	$ 564,712
Research and other credits	142,198	139,996
Net capital loss carryforwards	38,445	0
Operating lease liabilities	28,254	34,680
Stock-based compensation	22,110	33,408
Capitalized research and development costs	24,134	0
Liability related to the sale of future royalties	13,424	23,757
Other	13,935	17,290
Deferred tax assets before valuation allowance	828,008	813,843
Valuation allowance for deferred tax assets	(816,235)	(785,748)
Total deferred tax assets	11,773	28,095
Deferred tax liabilities:
Operating lease right-of-use assets	(11,335)	(27,204)
Investment in foreign subsidiary	(2,451)	0
Other	(392)	(564)
Total deferred tax liabilities	(14,178)	(27,768)
Total deferred tax liabilities	$ (2,405)
Net deferred tax assets (liabilities)		$ 327

Operating Leases (Tables)

12 Months Ended

Dec. 31, 2022

Leases [Abstract]

Schedule of Operating Lease Information

The following table presents key information regarding these leases (dollars in thousands):


	Mission Bay Facility	Third Street Facility
Lease commencement	September 2017	June 2018
Lease term	January 2030	January 2030
Renewal terms	Two consecutive five-year terms	One five-year term

Schedule of Lease Expense

The components of lease expense, which we include in operating expenses in our Consolidated Statements of Operations, were as follows (in thousands):


	Year Ended December 31,
	2022		2021		2020
Operating lease expense	$	17,057	$	19,153	$	18,985
Variable lease expense	10,700		8,974		8,179
Total lease expense	$	27,757	$	28,127	$	27,164

Schedule of Future Minimum Lease Payments for Operating Leases

As of December 31, 2022, the maturities of our operating lease liabilities were as follows (in thousands):


Year ending December 31,
2023	$	19,216
2024	21,572
2025	22,254
2026	22,958
2027	23,681
2028 and thereafter	51,732
Total lease payments	161,413
Less: portion representing interest	(29,917)
Operating lease liabilities	131,496
Less: current portion	(18,667)
Operating lease liabilities, less current portion	$	112,829

Co-Development Agreement with SFJ Pharmaceuticals and Development Derivative Liability - Schedule of Fair Value of Derivative Liability (Details) - Development Derivative Liability - Level 3 - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value as of December 31, 2021 and February 12, 2021 (inception), respectively	$ 27,726	$ 0
Non-cash research and development expense	4,951	16,703
Cash receipts from SFJ	750	3,000
Change in the fair value of development derivative liability	(33,427)	8,023
Fair value at end of period	$ 0	$ 27,726

License and Collaboration Agreements (Tables)

12 Months Ended

Dec. 31, 2022

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Schedule of License, Collaboration and Other Revenue

In accordance with our collaboration agreements, we recognized license, collaboration and other revenue as follows (in thousands):


		Year Ended December 31,
Partner	Agreement	2022		2021		2020
Bristol-Myers Squibb	Bempegaldesleukin	$	—	$	—	$	50,000
Other		1,913		436		5,849
License, collaboration and other revenue		$	1,913	$	436	$	55,849

Income Taxes - Schedule of Income (Loss) Before Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Domestic	$ (371,900)	$ (524,440)	$ (445,370)
Foreign	6,917	1,160	1,423
Loss before provision for income taxes	$ (364,983)	$ (523,280)	$ (443,947)

- Definition

Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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-Paragraph 32
-Subparagraph (f)
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-Subparagraph (SX 210.9-05(b)(2))
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Reference 9: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
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-Topic 280
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Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(15))
-URI https://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260

+ Details

License and Collaboration Agreements

12 Months Ended

Dec. 31, 2022

Organization, Consolidation and Presentation of Financial Statements [Abstract]

License and Collaboration Agreements

We have entered into various collaboration agreements including license agreements and collaborative research, development and commercialization agreements with various pharmaceutical and biotechnology companies. Under these collaboration arrangements, we are entitled to receive license fees, upfront payments, milestone and other contingent payments, royalties, sales milestone payments, and payments for the manufacture and supply of our proprietary PEGylation materials and/or reimbursement for research and development activities. We generally include our costs of performing these services in research and development expense, except for costs for product sales to our collaboration partners which we include in cost of goods sold. We analyze our agreements to determine whether we should account for the agreements within the scope of ASC 808, and, if so, we analyze whether we should account for any elements under ASC 606.

In accordance with our collaboration agreements, we recognized license, collaboration and other revenue as follows (in thousands):


		Year Ended December 31,
Partner	Agreement	2022		2021		2020
Bristol-Myers Squibb	Bempegaldesleukin	$	—	$	—	$	50,000
Other		1,913		436		5,849
License, collaboration and other revenue		$	1,913	$	436	$	55,849

Bristol-Myers Squibb (BMS): Bempegaldesleukin (previously referred to as NKTR-214)

On February 13, 2018, we entered into a Strategic Collaboration Agreement (the BMS Collaboration Agreement) and a Share Purchase Agreement with BMS, both of which became effective on April 3, 2018. Pursuant to the BMS Collaboration Agreement, we and BMS have jointly developed bempegaldesleukin in combination with BMS’s Opdivo®. The parties share the internal and external development costs for bempegaldesleukin in combination regimens based on each party’s relative ownership interest in the compounds included in the regimens. In accordance with the agreement, the parties share development costs for bempegaldesleukin in combination with Opdivo®, 67.5% of costs to BMS and 32.5% to Nektar. The parties share costs for the manufacturing and commercialization of bempegaldesleukin, 35% of the costs to BMS and 65% to Nektar.

Upon the effective date of the BMS Collaboration Agreement in April 2018, BMS paid us a non-refundable upfront cash payment of $1.0 billion and purchased 8,284,600 shares of our common stock pursuant to the Share Purchase Agreement for total additional cash consideration of $850.0 million. In 2020, we received non-refundable milestone payments of $50.0 million in aggregate for the first patient, first visit in the registrational trials in muscle-invasive bladder cancer and adjuvant melanoma.

As discussed in Note 1, on March 14, 2022, we announced our registrational trial in metastatic melanoma did not meet its primary endpoints and that BMS and we decided to discontinue the trials in metastatic melanoma and adjuvant melanoma. On April 14, 2022, we announced that our registrational trials in each of renal cell carcinoma and cisplatin-ineligible, locally advanced or metastatic urothelial cancer did not meet their respective primary endpoints. Due to these results, BMS and we decided that these studies and all other ongoing studies in the program will be discontinued. The decision to terminate the program does not affect the cost-sharing provisions under the BMS Collaboration Agreement. However, without further development of bempegaldesleukin, we will no longer be eligible for the development, regulatory and sales milestones under the arrangement.

We determined that the BMS Collaboration Agreement falls within the scope of ASC 808. As mentioned above, BMS shares certain percentages of development costs incurred by us and we share certain percentages of development costs incurred by BMS. We consider these activities to represent collaborative activities under ASC 808 and we recognize such cost sharing

proportionately with the performance of the underlying services. We recognized BMS’ reimbursement of our expenses as a reduction of research and development expense and our reimbursement of BMS’ expenses as research and development expense. As discussed in Note 11, we terminated the development of bempegaldesleukin, and therefore, in the second quarter of 2022, we began reporting clinical trial, other third-party costs and employee costs for the bempegaldesleukin program in restructuring, impairment and other costs of program. Accordingly, during the year ended December 31, 2022, we recorded $45.7 million for the net reimbursement from BMS, of which we recorded $24.9 million as a reduction of research and development expense for the first quarter of 2022, and $20.8 million as a reduction of restructuring, impairment and other costs of terminated program for the remaining three quarters of 2022. During the years ended December 31, 2021 and 2020, we recorded $101.5 million and $128.2 million, respectively, as a reduction of research and development expense for the net reimbursement from BMS. As of December 31, 2022, we have recorded an unbilled receivable of $4.2 million from BMS in accounts receivable in our Consolidated Balance Sheet, which we received in February 2023.

Eli Lilly and Company (Lilly): NKTR-358

On July 23, 2017, we entered into a worldwide license agreement (the Lilly Agreement) with Eli Lilly and Company (Lilly) to co-develop rezpegaldesleukin, a novel immunological drug candidate that we invented, pursuant to which we received an initial payment of $150.0 million and are eligible for up to $250.0 million in additional development and regulatory milestones. Although we are entitled to significant development milestones under this arrangement if Lilly decides to proceed to Phase 3 development, we have excluded such milestones from the transaction price due to the significant uncertainties involved with clinical development. We re-evaluate the transaction price at each reporting period and as uncertain events are resolved or other changes in circumstances occur.

We are currently in Phase 1B and Phase 2 development, where we share costs with 75% of the costs borne by Lilly and 25% of the costs borne by us. Lilly is responsible for the costs of Phase 3 development, but we retain the option to contribute up to 25% of the costs of Phase 3 development on an indication-by-indication basis in order for us to achieve the maximum royalty level under the Lilly Agreement, and further, if approved, we will have the opportunity to receive a royalty rate up to the low twenties percent based upon our Phase 3 development cost contribution and the level of annual global product sales. Lilly will be responsible for all costs of global commercialization, and we will have an option to co-promote in the U.S. under certain conditions. A portion of the development milestones may be reduced by 50% under certain conditions, related to the final formulation of the approved product and the timing of prior approval (if any) of competitive products with a similar mechanism of action, which could reduce these milestone payments by 75% if both conditions occur. The Lilly Agreement will continue until Lilly no longer has any royalty payment obligations or, if earlier, the termination of the agreement in accordance with its terms. The Lilly Agreement may be terminated by Lilly for convenience, and may also be terminated under certain other circumstances, including material breach.

On February 23, 2023, we announced the topline data from the Phase 2 study of rezpegaldesleukin in adult patients with systemic lupus erythematosus (SLE) (Phase 2 Lupus Study). The primary endpoint of the Phase 2 Lupus Study was not met, and Lilly has notified us that it does not intend to advance rezpegaldesleukin into Phase 3 development for SLE.

Baxalta Inc. / Takeda Pharmaceutical Ltd.: Hemophilia

We are a party to an exclusive research, development, license and manufacturing and supply agreement with Baxalta Inc. (Baxalta), a subsidiary of Takeda Pharmaceutical Company Ltd. (Takeda), entered into in September 2005 to develop products designed to improve therapies for Hemophilia A patients using our PEGylation technology, resulting in the approval of ADYNOVATE® by the FDA in 2015, which is now marketed in the U.S., the European Union, and many other countries. We are entitled to royalties based on worldwide net sales of ADYNOVATE® and a sales milestone upon achievement of an annual worldwide net sales target. We are responsible for supplying Takeda with its requirements for our proprietary materials. Takeda is responsible for all clinical development, regulatory, and commercialization expenses. The agreement is terminable by the parties under customary conditions.

In October 2017, we entered into a right to sublicense agreement with Baxalta, under which we granted to Baxalta the right to grant a nonexclusive sublicense to certain patents that were previously exclusively licensed to Baxalta under our 2005 agreement. Under the right to sublicense agreement, we are entitled to single digit royalty payments based upon net sales of the products covered under the sublicense throughout the term of the agreement. As described in Note 7, we sold our rights to receive these royalties to HCR pursuant to the 2020 Purchase and Sale Agreement.

AstraZeneca AB: MOVANTIK® (naloxegol oxalate)

In September 2009, we entered into an agreement with AstraZeneca AB (AstraZeneca) under which we granted AstraZeneca a worldwide, exclusive license under our patents and other intellectual property to develop, market, and sell MOVANTIK®. AstraZeneca is responsible for all research, development and commercialization costs and related decisions for MOVANTIK®. Through various sublicense arrangements to RedHill Biopharma, Kyowa Hakko Kirin Co. Ltd. and Knight Therapeutics, as of April 2020, AstraZeneca has sub-licensed all of its global commercialization rights. Our rights, including the royalty rate, royalty term and future potential sales milestones, remain unchanged as a result of these sublicenses.

We are generally entitled to escalating double-digit royalty payments and sales milestones for net sales of MOVANTIK®. As described in Note 7, we sold our rights to receive these royalties to HCR pursuant to the 2020 Purchase and Sale Agreement.

Other

We have other collaboration agreements that have resulted in commercialized products for our collaborations partners. Under these agreements, we may sell our proprietary PEGylation materials for use in these products, and we are entitled to receive royalties based on net sales of these products as well as sales milestones. Additionally, we have a collaboration agreement for a product under development, under which we are entitled to up to a total of $40.0 million of regulatory milestones, as well as royalties based on net sales, if approved, and sales milestones upon achievement of an annual net sales targets. However, given the current phase of development of the product under this collaboration agreement, we cannot estimate the probability or timing of achieving these milestones, and, therefore, have excluded all development milestones from the transaction price for this agreement.

Audit Information	12 Months Ended
Audit Information	Dec. 31, 2022
Auditor Information [Abstract]
Auditor Name	Ernst & Young LLP
Auditor Location	San Mateo, California
Auditor Firm ID	42

Stock-Based Compensation - Schedule of Stock Option Activity Under Equity Incentive Plans (Details) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($) $ / shares shares
Number of Shares
Outstanding, beginning balance (in shares) \| shares	13,542
Options granted (in shares) \| shares	6,276
Options exercised (in shares) \| shares	(15)
Options forfeited and canceled (in shares) \| shares	(5,715)
Outstanding, ending balance (in shares) \| shares	14,088
Weighted- Average Exercise Price per Share
Outstanding, beginning balance (in dollars per share) \| $ / shares	$ 23.62
Options granted (in dollars per share) \| $ / shares	4.76
Options exercised (in dollars per share) \| $ / shares	12.43
Options forfeited and canceled (in dollars per share) \| $ / shares	20.73
Outstanding, ending balance (in dollars per share) \| $ / shares	$ 16.40
Weighted- Average Remaining Contractual Life (in Years)
Weighted-Average Remaining Contractual Life, Outstanding	5 years 8 months 15 days
Aggregate Intrinsic Value, Outstanding \| $	$ 0
Number of Shares, Exercisable (in shares) \| shares	6,029
Weighted-Average Exercise Price Per Share, Exercisable (in dollars per share) \| $ / shares	$ 27.82
Weighted-Average Remaining Contractual Life, Exercisable	3 years 7 months 6 days
Aggregate Intrinsic Value, Exercisable \| $	$ 0

Segment Reporting - Revenue by Geographic Area (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Revenue by geographic area
Total revenue	$ 92,055	$ 101,907	$ 152,915
United States \| Reportable Geographical Components
Revenue by geographic area
Total revenue	9,841	10,114	64,966
Rest of World \| Reportable Geographical Components
Revenue by geographic area
Total revenue	$ 82,214	$ 91,793	$ 87,949

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=126901519&loc=d3e8906-108599

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 40
-URI https://asc.fasb.org/extlink&oid=126901519&loc=d3e9031-108599

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 41
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=126901519&loc=d3e9038-108599

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126901519&loc=d3e8933-108599

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=126901519&loc=d3e8933-108599

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=126920106&loc=SL49130543-203045

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126901519&loc=d3e8736-108599

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=126901519&loc=d3e8736-108599

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI https://asc.fasb.org/extlink&oid=126901519&loc=d3e9054-108599

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI https://asc.fasb.org/extlink&oid=126920106&loc=SL49130545-203045

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 924
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 11.L)
-URI https://asc.fasb.org/extlink&oid=6472922&loc=d3e499488-122856

+ Details

Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2022

Equity [Abstract]

Schedule of Shares of Common Stock Reserved for Future Issuance

As of December 31, 2022, shares of common stock reserved for future issuance are as follows (in thousands):


Stock options, RSUs and PSUs outstanding			23,589
Shares available for future grant under the 2017 Performance Incentive Plan			2,973
Shares available for issuance under the employee stock purchase plan			841
Total common stock reserved for issuance			27,403

The following table lists the Black-Scholes option-pricing model assumptions used to calculate the fair value of employee and director stock options, as well as the resulting grant-date fair value:


	Year Ended December 31,
	2022			2021			2020
Average risk-free interest rate	2.9		%	1.2		%	0.4		%
Dividend yield	0.0		%	0.0		%	0.0		%
Average volatility factor	77.9		%	63.8		%	64.1		%
Weighted-average expected life	5.6 years			5.5 years			5.6 years
Weighted-average grant-date fair value of options granted	$	3.18		$	8.07		$	10.70

Stock-Based Compensation - Schedule of Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	$ 57,320	$ 94,674	$ 94,261
Cost of goods sold
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	2,824	2,779	2,825
Research and development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	27,727	54,821	57,116
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	24,488	37,074	33,295
Restructuring, impairment and other costs of terminated program
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	$ 2,281	$ 0	$ 1,025

Co-Development Agreement with SFJ Pharmaceuticals and Development Derivative Liability - Additional Information (Details) - SFJ Pharmaceuticals	Feb. 12, 2021 USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Committed funding	$ 150,000,000
Collaborative arrangement, success-based payments	$ 637,500,000

Restructuring, Impairment and Other Costs of Terminated Program

12 Months Ended

Dec. 31, 2022

Restructuring and Related Activities [Abstract]

Restructuring, Impairment and Other Costs of Terminated Program

As discussed in Note 1, because our registrational trials in bempegaldesleukin did not meet their primary endpoints, we decided to discontinue all of our ongoing clinical trials of bempegaldesleukin in combination with checkpoint inhibitors and tyrosine kinase inhibitors, and, during April 2022, we announced the 2022 Restructuring Plan to prioritize key Phase 2 development programs, to advance our early stage research pipeline and to reduce our workforce by approximately 70% from approximately 735 to approximately 225 employees. In connection with these events, we reported the following costs in restructuring, impairment and other costs of terminated program for the year ended December 31, 2022:

•Clinical trial expense, other third-party costs and employee costs for the wind down of the bempegaldesleukin program, net of the reimbursement from BMS;

•Severance and related benefit costs pursuant to the 2022 Restructuring Plan;

•Impairment of sublease assets, including right-of-use assets and property, plant and equipment resulting from the 2022 Restructuring Plan, reflecting excess office and laboratory leased spaces in San Francisco, CA;

•(Gain) loss on sale or disposal of property, plant and equipment; and

•Contract termination and other costs associated with the wind down of the bempegaldesleukin program.

In prior periods through March 31, 2022, we reported the clinical trial costs, other third-party costs and employee costs related to the bempegaldesleukin program primarily in research and development expense.

Restructuring, impairment and other costs of terminated program includes the following (in thousands):


	Year Ended December 31, 2022
Clinical trial expense, other third-party and employee costs for the wind down of the bempegaldesleukin program	$	31,693
Severance and benefit expense	30,904
Impairment of right-of-use assets and property, plant and equipment	65,761
(Gain) loss on sale or disposal of property, plant and equipment, net	(3,326)
Contract termination and other restructuring costs	10,898
Restructuring, impairment and other costs of terminated program	$	135,930

Clinical trial expense, other third-party and employee costs for the wind down of the bempegaldesleukin program

The clinical costs associated with winding down the bempegaldesleukin program primarily include clinical trial and other development expenses to transition patients from our sponsor-led trials to standard of care or our post-trial access program, as well as direct employee costs supporting these efforts. We recorded a reduction of expense of $20.8 million for the net reimbursement from BMS primarily for such costs.

Severance and Benefit Expense

Employees affected by the reduction in force under our 2022 Restructuring Plan were entitled to receive severance payments and certain Company funded benefits. We recognized severance and benefit expense in full for employees who were notified of their termination in April 2022 and had no requirements for future service, and we recognized expense for employees who were required to render services to receive their severance ratably over the service period. This service period began in April 2022 with all affected employees terminated on or before December 31, 2022, and therefore we will recognize no further expense. The following table provides details regarding the severance and other termination benefit expense. We present the liability, which we paid in January 2023, in accrued compensation on our Consolidated Balance Sheet (in thousands):


	Year Ended December 31, 2022
	No service period		Service period required		Total
Liability balance as of March 31, 2022	$	—	$	—	$	—
Expense recognized during the period	22,993		7,911		30,904
Payments during the period	(22,993)		(4,612)		(27,605)
Liability balance as of December 31, 2022	$	—	$	3,299	$	3,299

Impairment of Right-of-Use Assets and Property, Plant and Equipment

In connection with our 2022 Restructuring Plan, we have consolidated our San Francisco operations in our Mission Bay Facility, and we have vacated our Third St. Facility and certain laboratory and office spaces at our Mission Bay Facility. We are seeking to sublease the vacated spaces, while still maintaining sufficient office and laboratory space to allow our team to develop our proprietary programs.

As a result of these plans, we reviewed each of our vacated spaces for impairment as of May 31, 2022, when management had determined which spaces we would seek to sublease, and subsequently at each reporting date or as facts and circumstances changed. As part of our impairment evaluation of each vacated space, we separately compared the estimated undiscounted income to the net book value of the related long-term assets, which include right-of-use assets and certain property, plant and equipment, primarily leasehold improvements (collectively, sublease assets). We estimated sublease income using market participant assumptions, including the length of time to enter into a sublease and sublease payments, which we evaluated using sublease negotiations or agreements when applicable, current real estate trends and market conditions. If such income exceeded the net book value of the related assets, we did not record an impairment charge. Otherwise, we recorded an impairment charge by reducing the net book value of the assets to their estimated fair value, which we determined by discounting the estimated sublease cash flows using the estimated borrowing rate of a market participant subtenant, which we estimated to be 6.4% and 7.9% as of May 31, 2022 and December 31, 2022, respectively. We recorded the substantial majority of our impairment charges as of May 31, 2022, primarily reflecting decreased rental recovery rates for our office lease space on Third St. However, as the office lease market in San Francisco deteriorated after May 31, 2022 in the fourth quarter of 2022, we recorded an additional impairment charge of $12.0 million in the three months ended December 31, 2022, for the Third St. Facility, reflecting an increase in our estimated time to enter into a sublease.

We recorded impairment charges as follows (in thousands):


	Year Ended December 31, 2022
	Operating Lease Right-of-Use Assets		Property, Plant and Equipment		Total
Net book value of impaired sublease assets as of May 31, 2022	$	72,481	$	16,348	$	88,829
Less: Fair value of impaired sublease assets — Level 3 of Fair Value Hierarchy	(16,174)		(4,780)		(20,954)
Book value in excess of fair value	56,307		11,568		67,875
Less: Amounts recorded as amortization between May 31 and December 31, 2022 for Third St. facility	(1,717)		(397)		(2,114)
Total impairment of sublease assets	$	54,590	$	11,171	$	65,761

We may record adjustments to impairment expense in future periods as we enter into sublease agreements or update our estimates as additional information becomes available to us.

(Gain) Loss on Sale or Disposal of Property, Plant and Equipment, Net

In connection with our 2022 Restructuring Plan, we terminated all research and development activities at our owned facility in India, which we sold in December 2022. We also recognized losses including excess equipment, net of sale proceeds, and the disposal of software to support the commercialization of bempegaldesleukin. We recorded the gains and losses as follows (in thousands):


	Year Ended December 31, 2022
Proceeds from sales		$	13,196
Net book value of assets		9,870
Total (gain) loss on sale or disposal of property, plan and equipment, net		(3,326)

Property, Plant and Equipment - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Depreciation and amortization expenses	$ 12.2	$ 13.0	$ 12.5

Property, Plant and Equipment (Tables)

12 Months Ended

Dec. 31, 2022

Property, Plant and Equipment [Abstract]

Schedule of Property, Plant and Equipment

Property, plant and equipment consists of the following (in thousands):


	December 31,
	2022		2021
Building and leasehold improvements	$	74,889	$	97,385
Laboratory equipment	24,243		42,704
Computer equipment and software	26,205		28,829
Manufacturing equipment	25,052		22,374
Furniture, fixtures, and other	4,263		10,094
Depreciable property, plant and equipment at cost	154,652		201,386
Less: accumulated depreciation	(124,731)		(148,039)
Depreciable property, plant and equipment, net	29,921		53,347
Construction-in-progress	2,530		7,163
Property, plant and equipment, net	$	32,451	$	60,510

We recorded the gains and losses as follows (in thousands):


	Year Ended December 31, 2022
Proceeds from sales		$	13,196
Net book value of assets		9,870
Total (gain) loss on sale or disposal of property, plan and equipment, net		(3,326)

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2022	Dec. 31, 2021
Statement of Financial Position [Abstract]
Preferred stock, par value (in usd per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares designated (in shares)	0	0
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in usd per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	300,000,000	300,000,000
Common stock, shares issued (in shares)	188,560,000	185,468,000
Common stock, shares outstanding (in shares)	188,560,000	185,468,000

Stock-Based Compensation - Schedule of Restricted Stock Unit Award Activity (Details) - Restricted Stock Units (RSU) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Units Issued
Beginning balance (in shares)	9,930
Granted (in shares)	7,708
Vested and released (in shares)	(2,872)
Forfeited and canceled (in shares)	(5,454)
Ending balance (in shares)	9,312	9,930
Weighted- Average Grant Date Fair Value
Beginning balance (in dollars per share)	$ 16.80
Granted (in dollars per share)	4.14	$ 14.68	$ 19.24
Vested and released (in dollars per share)	17.64
Forfeited and canceled (in dollars per share)	15.68
Ending balance (in dollars per share)	$ 6.81	$ 16.80

Liabilities Related to the Sales of Future Royalties - Additional Information (Details) $ in Thousands				1 Months Ended		3 Months Ended	12 Months Ended
	Dec. 30, 2020 USD ($)	Dec. 16, 2020 USD ($)	Feb. 24, 2012 USD ($)	Mar. 31, 2014 USD ($)	Mar. 31, 2013 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Liability Related to the Sale of Future Royalties [Line Items]
Loss on revaluation of liability related to the sale of future royalties							$ 0	$ 24,410	$ 0
2012 Purchase and Sale Agreement
Liability Related to the Sale of Future Royalties [Line Items]
Proceeds from sale of royalty rights			$ 124,000
2012 Purchase and Sale Agreement \| Future Royalties
Liability Related to the Sale of Future Royalties [Line Items]
Fair value of liabilities							$ 84,700
Loss on revaluation of liability related to the sale of future royalties						$ 23,500
Transaction costs related to revised royalty payments						$ 900
2012 Purchase and Sale Agreement \| Future Royalties \| Measurement Input, Discount Rate
Liability Related to the Sale of Future Royalties [Line Items]
Royalties liability, measurement input							0.160
2020 Purchase and Sale Agreement
Liability Related to the Sale of Future Royalties [Line Items]
Proceeds from sale of royalty rights	$ 150,000
Payment of transaction related to purchase and sale agreement		$ 210,000
Payment of transaction related to purchase and sale agreement if threshold is not achieved		240,000
Minimum transaction royalties payments needed to pay the difference between the 2025 threshold and 2020 transaction royalties		$ 208,000
Transaction costs related to sale of potential future royalties	$ 3,800
2020 Purchase and Sale Agreement \| Measurement Input, Discount Rate
Liability Related to the Sale of Future Royalties [Line Items]
Royalties liability, measurement input							0.20
2020 Purchase and Sale Agreement \| Measurement Input, Interest Rate
Liability Related to the Sale of Future Royalties [Line Items]
Royalties liability, measurement input							0.10
Pursuant to the 2012 Purchase and Sale Agreement
Liability Related to the Sale of Future Royalties [Line Items]
Payment made for milestone not achieved year two				$ 7,000
Payment made for milestone not achieved year one					$ 3,000

Inventory - Schedule of Inventories (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Inventory Disclosure [Abstract]
Raw materials	$ 2,575	$ 3,166
Work-in-process	10,749	9,342
Finished goods	5,878	3,293
Total inventory	$ 19,202	$ 15,801

Commitments and Contingencies (Details) - USD ($)	Dec. 31, 2022	Dec. 31, 2021
Indemnification Obligation
Loss Contingencies [Line Items]
Litigation matters, liabilities	$ 0	$ 0
Merger and Acquisition Related Claims \| Maximum
Loss Contingencies [Line Items]
Obligations under Director and Officer Indemnifications per incident	10,000,000
Securities Related Claims
Loss Contingencies [Line Items]
Obligations under Director and Officer Indemnifications per incident	10,000,000
Non-Securities Related Claims
Loss Contingencies [Line Items]
Obligations under Director and Officer Indemnifications per incident	$ 10,000,000