0001370053-24-000011 | 10-K | XBRL Viewer

Fair Value Measurements and Available for Sale Investments - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value included in short-term or long-term investments	$ 381,965	$ 512,868
US Treasury Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value included in short-term or long-term investments	325,714	374,527
Certificates of Deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value included in short-term or long-term investments	244	2,856
Agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value included in short-term or long-term investments	20,253	74,602
Commercial and corporate obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value included in short-term or long-term investments	35,754	60,883
Recurring \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value included in cash and cash equivalents	27,789	29,702
Recurring \| Mutual funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value included in cash and cash equivalents	6,286	41,812
Recurring \| US Treasury Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value included in short-term or long-term investments	325,714	374,527
Recurring \| Certificates of Deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value included in short-term or long-term investments	244	2,856
Recurring \| Agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value included in short-term or long-term investments	20,253	74,602
Recurring \| Commercial and corporate obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value included in short-term or long-term investments	35,754	60,883
Recurring \| Quoted Market Prices for Identical Assets (Level 1) \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value included in cash and cash equivalents	27,789	29,702
Recurring \| Quoted Market Prices for Identical Assets (Level 1) \| Mutual funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value included in cash and cash equivalents	6,286	41,812
Recurring \| Quoted Market Prices for Identical Assets (Level 1) \| US Treasury Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value included in short-term or long-term investments	325,714	374,527
Recurring \| Quoted Market Prices for Identical Assets (Level 1) \| Certificates of Deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value included in short-term or long-term investments	0	0
Recurring \| Quoted Market Prices for Identical Assets (Level 1) \| Agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value included in short-term or long-term investments	0	0
Recurring \| Quoted Market Prices for Identical Assets (Level 1) \| Commercial and corporate obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value included in short-term or long-term investments	0	0
Recurring \| Significant Other Observable Inputs (Level 2) \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value included in cash and cash equivalents	0	0
Recurring \| Significant Other Observable Inputs (Level 2) \| Mutual funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value included in cash and cash equivalents	0	0
Recurring \| Significant Other Observable Inputs (Level 2) \| US Treasury Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value included in short-term or long-term investments	0	0
Recurring \| Significant Other Observable Inputs (Level 2) \| Certificates of Deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value included in short-term or long-term investments	244	2,856
Recurring \| Significant Other Observable Inputs (Level 2) \| Agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value included in short-term or long-term investments	20,253	74,602
Recurring \| Significant Other Observable Inputs (Level 2) \| Commercial and corporate obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value included in short-term or long-term investments	35,754	60,883
Recurring \| Significant Unobservable Inputs (Level 3) \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value included in cash and cash equivalents	0	0
Recurring \| Significant Unobservable Inputs (Level 3) \| Mutual funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value included in cash and cash equivalents	0	0
Recurring \| Significant Unobservable Inputs (Level 3) \| US Treasury Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value included in short-term or long-term investments	0	0
Recurring \| Significant Unobservable Inputs (Level 3) \| Certificates of Deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value included in short-term or long-term investments	0	0
Recurring \| Significant Unobservable Inputs (Level 3) \| Agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value included in short-term or long-term investments	0	0
Recurring \| Significant Unobservable Inputs (Level 3) \| Commercial and corporate obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value included in short-term or long-term investments	$ 0	$ 0

Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Statement [Abstract]
Revenue from Contract with Customer, Product and Service [Extensible Enumeration]	Collaboration Revenue [Member]	Collaboration Revenue [Member]	Collaboration Revenue [Member]
Collaboration revenue	$ 17,157,000	$ 10,287,000	$ 63,175,000
Operating expenses:
Research and development	132,283,000	88,798,000	98,496,000
General and administrative	41,946,000	36,643,000	21,493,000
Acquired in-process research and development	7,339,000	0	0
Total operating expenses	181,568,000	125,441,000	119,989,000
Loss from operations	(164,411,000)	(115,154,000)	(56,814,000)
Other income (expense), net:
Interest income	18,873,000	7,550,000	431,000
Non-cash interest expense for the sale of future royalties	(18,083,000)	(21,108,000)	(1,450,000)
Other (expense) income, net	(2,000)	12,000	37,000
Total other income (expense), net	788,000	(13,546,000)	(982,000)
Loss before income taxes	(163,623,000)	(128,700,000)	(57,796,000)
Benefit (Provision) for income taxes	4,000	(24,000)	0
Net loss	(163,619,000)	(128,724,000)	(57,796,000)
Other comprehensive loss:
Unrealized gain (loss) on available for sale securities	4,449,000	(4,824,000)	(418,000)
Comprehensive loss	$ (159,170,000)	$ (133,548,000)	$ (58,214,000)
Net loss per common share:
Basic (in dollars per share)	$ (6.08)	$ (4.57)	$ (2.11)
Diluted (in dollars per share)	$ (6.08)	$ (4.57)	$ (2.11)
Weighted-average number of shares outstanding:
Basic (in shares)	26,924	28,165	27,431
Diluted (in shares)	26,924	28,165	27,431

Stockholders' Equity

12 Months Ended

Dec. 31, 2023

Equity [Abstract]

Stockholders' Equity

Stockholders’ Equity

Common Stock

Of the 500,000,000 shares of common stock authorized, 26,596,765 shares were issued and outstanding as of December 31, 2023.

Stock Repurchase Program

In January 2023, our Board of Directors authorized a stock repurchase program (the “Repurchase Program”) to repurchase up to $50.0 million of our outstanding common stock, par value $0.001 per share. The Repurchase Program was completed in May 2023. The following table presents the repurchase activity from January 1, 2023 through May 5, 2023, the end date of the Repurchase Program:


	Total number of shares purchased	Average price paid per share		Approximate dollar value of shares purchased (in thousands)
First Quarter 2023	1,589,424	$	24.19	$	38,456
Second Quarter 2023	534,790	21.59		11,544
Total	2,124,214			$	50,000

The repurchased common stock was subsequently retired after the repurchase and the par value of the shares was charged to common stock. The excess of the repurchase price over the par value was applied against additional paid in capital.

Open Market Sales Agreement

In November 2022, we entered into the Cowen Sales Agreement with Cowen, through which we may offer and sell shares of our common stock, having an aggregate offering of up to $150.0 million through Cowen as our sales agent. As of December 31, 2023, we had sold no shares under this agreement.

- Definition

The entire disclosure for equity.

+ References

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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Summary of Significant Accounting Policies - Summary of Potentially Dilutive Securities (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Options to purchase common stock (in shares)	4,800	3,977	3,631
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Options to purchase common stock (in shares)	4,279	3,602	3,631
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Options to purchase common stock (in shares)	521	375	0

Equity Incentive Plans - Narrative (Details) $ in Thousands					12 Months Ended
Equity Incentive Plans - Narrative (Details) $ in Thousands	Jan. 01, 2023 shares	Mar. 21, 2022 shares	Mar. 20, 2022 USD ($)	Jan. 01, 2018	Dec. 31, 2023 USD ($) shares	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Proceeds from issuance of common stock \| $					$ 1,800
Stock-based compensation \| $					33,205	$ 27,356	$ 15,347
Chief Executive Officer \| Former Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non cash share based compensation expense \| $			$ 3,200
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost \| $					$ 200
Weighted average period remaining for amortization of unrecognized compensation cost (in years)					4 months 13 days
Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)					4 years
Award expiration period (in years)					10 years
Unrecognized compensation cost \| $					$ 31,600
Weighted average period remaining for amortization of unrecognized compensation cost (in years)					2 years 8 months 1 day
Options \| Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)					1 year
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equivalent shares					1
Granted (in shares) \| shares					568,574
Unrecognized compensation cost \| $					$ 12,200
Weighted average period remaining for amortization of unrecognized compensation cost (in years)					1 year 2 months 23 days
RSUs \| Chief Executive Officer \| Interim President And Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)					24 months
Granted (in shares) \| shares		887,043
Stock-based compensation \| $					$ 11,700	$ 9,200
Equity Incentive Plan, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual increase in number of shares available for issuance				4.00%
Capital shares reserved for future issuance, increase (in shares) \| shares	1,140,527
Shares reserved for future award grants (in shares) \| shares					2,272,850
Employee Stock Purchase Plan, 2017 \| ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual increase in number of shares available for issuance				1.00%
Capital shares reserved for future issuance, increase (in shares) \| shares	285,131
Shares reserved for future award grants (in shares) \| shares					1,734,840
Issued under ESPP (in shares) \| shares					98,000

Commitments and Contingencies - Narrative (Details) ft² in Thousands, $ in Thousands	May 04, 2020 ft² $ / ft²	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Apr. 05, 2021 USD ($)
Lessee, Lease, Description [Line Items]
Operating ROU assets		$ 16,174	$ 17,898
Total		$ 17,814
Weighted-average discount rate		4.00%
Weighted average remaining lease term (in years)		7 years 8 months 12 days
Lease Agreement
Lessee, Lease, Description [Line Items]
Area of leased property (sqft) \| ft²	45
Operating term	124 months
Lessee renewal	5 years
Termination period	7 years
Monthly base rate (usd per sqft) \| $ / ft²	4.20
Increase in annual rent	3.00%
Operating ROU assets				$ 20,600
Total				$ 20,700
Security deposit		$ 300

Income Taxes - Deferred tax assets and liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2014
Deferred Tax Assets:
Net operating loss carryforwards	$ 72,777	$ 66,160
Section 174 Capitalized R&D	37,240	16,570
Research and development credits	19,058	12,844	$ 200
Equity compensation	10,533	10,021
Deferred Zejula royalty revenue	6,978	7,371
Lease liability	3,912	4,194
Other, net	7,201	3,458
Total deferred tax assets	157,699	120,618
Deferred Tax Liabilities:
ROU asset	(3,552)	(3,859)
Other, net	(2,658)	0
Fixed assets	(122)	(189)
Total deferred tax liabilities	(6,332)	(4,048)
Net deferred tax assets	151,367	116,570
Less: valuation allowance	(151,367)	(116,570)
Deferred tax assets, net of valuation allowance	$ 0	$ 0

Sale of Future Royalties - Narrative (Details) - USD ($)	1 Months Ended		12 Months Ended
	Sep. 30, 2022	Oct. 31, 2021	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Jan. 01, 2021
Liabilities Related To Sale Of Future Royalties [Line Items]
Repayment of liability for sale of future royalties			$ 11,726,000	$ 2,474,000	$ 0
Liability related to sale of future royalties			310,807,000	304,413,000
Non-cash interest expense for the sale of future royalties			18,083,000	21,108,000	1,450,000
Collaboration revenue			17,157,000	10,287,000	63,175,000
GSK
Liabilities Related To Sale Of Future Royalties [Line Items]
Collaboration revenue			17,200,000	10,300,000	$ 63,200,000
JEMPERLI Royalty Monetization Agreement
Liabilities Related To Sale Of Future Royalties [Line Items]
Repayment of liability for sale of future royalties			8,600,000
Issuance costs related to the sale of future royalties		$ 400,000	$ 37,000
Net of proceeds		249,600,000
Effective interest rate			8.10%
JEMPERLI Royalty Monetization Agreement \| Sagard
Liabilities Related To Sale Of Future Royalties [Line Items]
Proceeds from sale of future royalties		250,000,000
Royalties agreement, maximum annual royalty payout capacity		1,000,000,000
Royalties and milestones received			$ 10,400,000
Liability related to sale of future royalties		250,000,000
JEMPERLI Royalty Monetization Agreement \| Sagard \| By the end of 2026
Liabilities Related To Sale Of Future Royalties [Line Items]
Royalties and milestones, agreement amount to be received		$ 312,500,000
Proceeds, contingent on annual sales milestones upfront		125.00%
JEMPERLI Royalty Monetization Agreement \| Sagard \| During 2027
Liabilities Related To Sale Of Future Royalties [Line Items]
Royalties and milestones, agreement amount to be received		$ 337,500,000
Proceeds, contingent on annual sales milestones upfront		135.00%
JEMPERLI Royalty Monetization Agreement \| Sagard \| At any time after 2027
Liabilities Related To Sale Of Future Royalties [Line Items]
Royalties and milestones, agreement amount to be received		$ 412,500,000
Proceeds, contingent on annual sales milestones upfront		165.00%
JEMPERLI Royalty Monetization Agreement \| GSK
Liabilities Related To Sale Of Future Royalties [Line Items]
Non cash royalty revenue, for sale of future royalties				2,300,000
Non-cash interest expense for the sale of future royalties			17,100,000	20,400,000
Collaboration revenue			13,800,000	2,300,000
Zejula Royalty Monetization Agreement
Liabilities Related To Sale Of Future Royalties [Line Items]
Repayment of liability for sale of future royalties			$ 3,126,000
Net of proceeds	$ 34,800,000
Effective interest rate			2.70%
Zejula Royalty Monetization Agreement \| GSK
Liabilities Related To Sale Of Future Royalties [Line Items]
Non-cash interest expense for the sale of future royalties			$ 1,000,000	700,000
Payment rate						1.00%
Settlement agreement rate						0.50%
Effective royalty rate			0.50%
Collaboration revenue			$ 3,400,000	$ 1,400,000
Zejula Royalty Monetization Agreement \| DRI Healthcare Trust
Liabilities Related To Sale Of Future Royalties [Line Items]
Proceeds from sale of future royalties	35,000,000
Royalties and milestones, agreement amount to be received	10,000,000
Liability related to sale of future royalties	35,000,000
Issuance costs related to the sale of future royalties	$ 200,000

Income Taxes - Unrecognized tax benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at the beginning of the year	$ 3,369	$ 2,473
Increase related to prior year tax positions	153	0
Increase related to current year tax positions	1,494	896
Balance at the end of the year	$ 5,016	$ 3,369

Income Taxes - Schedule of Loss before Income Tax Provision (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
U.S.	$ (163,580)	$ (128,650)	$ (57,741)
Foreign	(43)	(50)	(55)
Loss before income taxes	$ (163,623)	$ (128,700)	$ (57,796)

- 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
-Topic 944
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+ Details

Equity Incentive Plans

12 Months Ended

Dec. 31, 2023

Share-Based Payment Arrangement [Abstract]

Equity Incentive Plans

2017 Equity Incentive Plan

In January 2017, our Board of Directors and stockholders approved and adopted the 2017 Equity Incentive Plan (the “2017 Plan”). Under the 2017 Plan, we may grant stock options, stock appreciation rights, restricted stock, restricted stock units and other awards to individuals who are then our employees, officers, directors or consultants. In addition, the number of shares of stock available for issuance under the 2017 Plan will be automatically increased each January 1, beginning on January 1, 2018, by 4% of the aggregate number of outstanding shares of our common stock as of the immediately preceding December 31 or such lesser number as determined by our Board of Directors. The 2017 Plan automatically increased by 1,140,527 shares as of January 1, 2023. As of December 31, 2023, 2,272,850 shares were available for future issuance.

Employee Stock Purchase Plan

In January 2017, our Board of Directors and stockholders approved and adopted the 2017 Employee Stock Purchase Plan or the ESPP. In addition, the number shares of stock available for issuance under the ESPP will be automatically increased each January 1, beginning on January 1, 2018, by 1% of the aggregate number of outstanding shares of our common stock as of the immediately preceding December 31 or such lesser number as determined by our Board of Directors. The ESPP automatically increased by 285,131 shares as of January 1, 2023. As of December 31, 2023, 98,000 shares have been issued under the ESPP. As of December 31, 2023, 1,734,840 shares were available for future issuance under the ESPP.

Stock Options

Stock options granted to employees and non-employees generally vest over a four-year period while stock options granted to directors generally vest over a one-year period. Each stock option award has a maximum term of 10 years from the date of grant, subject to earlier cancellation prior to vesting upon cessation of service to us. A summary of the activity related to stock option awards during the year ended December 31, 2023 is as follows:


	Shares Subject to Options	Weighted-Average Exercise Price per Share		Weighted-Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value (in thousands)
Outstanding at January 1, 2023	3,673,208	$	32.04	6.28	$	18,686
Granted	1,579,331	$	22.02
Exercises	(90,883)	$	18.95
Forfeitures and cancellations	(936,041)	$	37.52
Outstanding at December 31, 2023	4,225,615	$	27.36	7.42	$	5,827
Exercisable at December 31, 2023	2,154,408	$	30.60	6.10	$	4,741

Total cash received from the exercise of stock options was approximately $1.8 million during the year ended December 31, 2023.

Time-based Restricted Stock Units

Each Restricted Stock Unit (“RSU”) represents one equivalent share of our common stock to be issued after satisfying the applicable continued service-based vesting criteria over a specified period. The fair value of these RSUs is based on the closing price of our common stock on the date of the grant. We measure compensation expense over the expected vesting period on a straight-line basis. The RSUs do not entitle the participants to the rights of holders of common stock, such as voting rights, until the shares are issued.


	Number of Restricted Stock Units	Weighted-Average Grant Date Fair Value		Weighted-Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value (in thousands)
Outstanding at January 1, 2023	1,028,843	$	26.14	1.17	$	31,884
Granted	568,574	$	22.02
Released	(68,900)	$	23.89
Forfeitures and cancellations	(46,945)	$	21.87
Outstanding at December 31, 2023	1,481,572	$	24.80	0.73	$	31,735
RSU expected to vest at December 31, 2023	1,481,572	$	24.80	0.73	$	31,735

Stock-Based Compensation Expense

We recognize stock-based compensation expense for awards issued to employees and non-employees over the requisite service period based on the estimated grant-date fair value of such awards. We record the expense for stock-based compensation awards subject to performance-based milestone vesting over the requisite service period when management determines that achievement of the milestone is probable. Management evaluates when the achievement of a performance-based milestone is probable based on the expected satisfaction of the performance conditions at each reporting date. The

estimated fair values of stock option awards granted were determined on the date of grant using the Black-Scholes option valuation model with the following weighted-average assumptions:


		Year Ended December 31,

		2023			2022			2021
Risk-free interest rate		3.8	%		2.5	%		0.7	%
Expected volatility		85.7	%		87.4	%		92.9	%
Expected dividend yield		—	%		—	%		—	%
Expected term (in years)		5.82			6.09			6.18
Weighted average grant date fair value per share	$	16.06		$	21.58		$	22.34

We determine the appropriate risk-free interest rate, expected term for employee stock-based awards, contractual term for non-employee stock-based awards, and volatility assumptions. The weighted-average expected option term for employee and non-employee stock-based awards reflects the historical option term for 2023 and the simplified life method for 2022 and 2021, which defines the life as the average of the contractual term of the options and the weighted-average vesting period for all option tranches. Expected volatility incorporates the historical volatility of our stock price. The risk-free interest rate is based upon U.S. Treasury securities with remaining terms similar to the expected or contractual term of the stock-based payment awards. The assumed dividend yield is based on our expectation of not paying dividends in the foreseeable future.

Total non-cash stock-based compensation expense for all stock awards that was recognized in the consolidated statements of operations and comprehensive loss is as follows:


	Year Ended December 31,
(in thousands)		2023		2022		2021
Research and development		$	10,159	$	6,775	$	5,856
General and administrative		23,046		20,581		9,491
Total		$	33,205	$	27,356	$	15,347

On March 20, 2022, our then Chief Executive Officer (“former CEO”), resigned by mutual agreement with the Board of Directors. In connection with his separation agreement, we modified certain equity awards and recognized approximately $3.2 million in non-cash stock-based compensation expense. Given the former CEO had substantially rendered the required services per his separation agreement, we recorded the full expense related to the modification in the period ending March 31, 2022. Additionally, on March 21, 2022, we awarded our newly appointed Interim President and Chief Executive Officer RSUs for 887,043 shares of the Company’s common stock. The fair value of the award will be recognized as part of compensation cost, occurring ratably over the stated 24-month requisite service period. During the year ended December 31, 2023, we recognized $11.7 million and $9.2 million during the year ended December 31, 2022 of non-cash stock-based compensation cost related to the award.

At December 31, 2023, there was $31.6 million of unrecognized compensation cost related to unvested stock option awards, which is expected to be recognized over a remaining weighted average vesting period of 2.67 years, $12.2 million of unrecognized cost related to unvested RSU awards, which is expected to be recognized over a period of 1.23 years, and $0.2 million of unrecognized compensation cost related to the ESPP, which is expected to be recognized over a remaining weighted-average vesting period of 0.37 years.

Stockholders' Equity - Schedule Of Stock Repurchase Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2023
Equity [Abstract]
Total number of shares purchased (in shares)	534,790	1,589,424	2,124,214
Average price paid per share (in dollars per share)	$ 21.59	$ 24.19
Approximate dollar value of shares purchased (in dollars per share)	$ 11,544	$ 38,456	$ 50,000

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

Schedule of Outstanding Potentially Dilutive Securities Excluded in the Calculation of Diluted Net Loss Per Share

The following table sets forth the weighted-average outstanding potentially dilutive securities that have been excluded in the calculation of diluted net loss per share because to do so would be anti-dilutive (in common stock equivalent shares):


	Year Ended December 31,
(in thousands)		2023	2022	2021

Options to purchase common stock		4,279	3,602	3,631
Restricted stock units		521	375	—

Total		4,800	3,977	3,631

Description of the Business	12 Months Ended
Description of the Business	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of the Business	Description of the Business AnaptysBio, Inc. (“we,” “us,” “our,” or the “Company”) was incorporated in the state of Delaware in November 2005. We are a clinical-stage biotechnology company focused on delivering innovative immunology therapeutics. We are developing immune cell modulating antibodies, including two wholly owned checkpoint agonists in clinical-stage development, for autoimmune and inflammatory diseases: rosnilimab, our PD-1 agonist in a Phase 2b trial for the treatment of moderate-to-severe rheumatoid arthritis (“RA”) and a Phase 2 trial for the treatment of moderate-to-severe ulcerative colitis (“UC”); and ANB032, our BTLA agonist, in a Phase 2b trial for the treatment of moderate-to-severe atopic dermatitis (“AD”). We also have other preclinical immune cell modulator candidates for the treatment of autoimmune and inflammatory diseases in our portfolio, including ANB033, an anti-CD122 antagonist antibody, and ANB101, a BDCA2 modulator antibody. In addition, we have developed two cytokine antagonists that we are exploring options for out-licensing: imsidolimab, our anti-IL-36R antibody, in Phase 3 development for the treatment of generalized pustular psoriasis (“GPP”), and etokimab, our anti-IL-33 antagonist that is Phase 2/3 ready. We have also discovered multiple therapeutic antibodies licensed to GlaxoSmithKline, Inc. (“GSK”) in a financial collaboration for immuno-oncology, including an anti-PD-1 antagonist antibody (Jemperli (dostarlimab-gxly)) and an anti-TIM-3 antagonist antibody (cobolimab, GSK4069889). We currently recognize revenue from milestones and royalties achieved under our immuno-oncology collaboration with GSK. Since our inception, we have devoted our primary effort to research and development activities. Our financial support has been provided primarily from the sale of our common stock, royalty monetizations, as well as through funds received under our collaborative research and development agreements. Going forward, as we continue our expansion, we may seek additional financing and/or strategic investments. However, there can be no assurance that any additional financing or strategic investments will be available to us on acceptable terms, if at all. If events or circumstances occur such that we do not obtain additional funding, we will most likely be required to reduce our plans and/or certain discretionary spending, which could have a material adverse effect on our ability to achieve our intended business objectives. AnaptysBio management believes our currently available resources will provide sufficient funds to enable us to meet our operating plans for at least the next twelve months from the issuance of our consolidated financial statements. The accompanying consolidated financial statements do not include any adjustments that might be necessary if we are unable to continue as a going concern.

Commitments and Contingencies - Costs in Cash Flow Statement (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Operating lease cost	$ 2,478	$ 2,478	$ 2,213
Cash paid for amounts included in the measurement of lease liabilities	$ 2,386	$ 2,316	$ 705

Balance Sheet Accounts and Supplemental Disclosures - Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Balance Sheet Related Disclosures [Abstract]
Accrued compensation and related expenses	$ 7,201	$ 5,379
Accrued professional fees	1,168	607
Accrued research, development and manufacturing expenses	21,898	15,351
Accrued for repurchase of common stock	456	0
Other	244	296
Total accrued expenses	$ 30,967	$ 21,633

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

Basis of Presentation

The accompanying consolidated financial statements have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”). The accompanying consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”).

Basis of Consolidation

The accompanying consolidated financial statements include us and our wholly-owned Australian subsidiary. All intercompany accounts and transactions have been eliminated in consolidation. We operate in one reportable segment, and our functional and reporting currency is the U.S. dollar.

Use of Estimates

The preparation of the accompanying consolidated financial statements in conformity with U.S. GAAP requires our management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements, and reported amounts of revenues and expenses during the reporting periods. Actual results could differ from those estimates. We base our estimates and assumptions on historical experience when available and on various factors that we believe to be reasonable under the circumstances. Significant estimates relied upon in preparing these financial statements include estimates related to revenue recognition, accrued research and development expenses, stock-based compensation, and the liability related to the sale of future royalties. We evaluate our estimates and assumptions on an ongoing basis. Our actual results could differ from these estimates under different assumptions or conditions.

Cash and Cash Equivalents

We consider all highly liquid investments with a maturity at date of purchase of three months or less to be cash equivalents. Cash equivalents consist primarily of money market and mutual funds with original maturities of 90 days or less.

Short-Term and Long-Term Investments

All investments have been classified as “available-for-sale” and are carried at fair value as determined based upon quoted market prices or pricing models for similar securities at period end. Investments with contractual maturities less than 12 months at the balance sheet date are considered short-term investments. Those investments with contractual maturities 12 months or greater at the balance sheet date are considered long-term investments. Dividend and interest income are recognized when earned. Realized gains and losses are included in earnings and are derived using the specific identification method for determining the cost of securities sold. Unrealized gains and losses are reported as a component of 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 cost have resulted from a credit-related loss or other factors. If the decline in fair value is due to credit-related factors, a loss is recognized in net income, whereas if the decline in fair value is not due to credit-related factors, the loss is recorded in other comprehensive income (loss). No credit impairment losses have been recorded during the years ended December 31, 2023, 2022, or 2021.

Concentration of Credit Risk

Financial instruments that potentially subject us to a concentration of credit risk consist of cash and cash equivalents and certain investments in money market funds, certificates of deposit, agency securities, commercial obligations and U.S. Treasury securities. Bank deposits are diversified between three financial institutions and these deposits may exceed insured limits. We are exposed to credit risk in the event of default by the financial institutions holding our cash and cash equivalents and issuers of investments that are recorded on our consolidated balance sheets. We mitigate our risk by investing in high-grade instruments and limiting the concentration in any one issuer, which limits our exposure.

Property and Equipment

Property and equipment are stated at cost, less accumulated depreciation. Expenditures for major additions and betterments are capitalized. Maintenance and repairs are charged to operations as incurred. Depreciation and amortization are calculated using the straight-line method over the estimated useful lives of the assets, which range from three to seven years. Leasehold improvements are amortized using the straight-line method over the term of the lease. Upon sale or retirement of property and equipment, the related cost and accumulated depreciation are removed from the accounts and any gain or loss is reflected in operations.

Long Lived Assets

Long-lived assets, consisting of property and equipment, are reviewed for impairment whenever events or changes in circumstances indicate that the carrying value of an asset may not be recoverable based on undiscounted cash flows. If long-lived assets are impaired, an impairment loss is recognized and is measured as the amount by which the carrying value exceeds the estimated fair value of the assets. No impairment charges were recorded during the years ended December 31, 2023, 2022, or 2021.

Leases

Our leases consist of a lease for office and lab space that is classified as an operating lease. We determine if an arrangement is a lease at inception. Rent expense is recognized on a straight-line basis. When an operating lease includes rent abatements or requires fixed escalations of the minimum lease payments, the aggregate rental expense is recognized on a straight-line basis over the term of the lease. When an operating lease includes lease incentives such as leasehold improvement allowances, the lease incentive is included in ROU asset. For leases that have greater than a 12-month lease term, the ROU assets and lease liabilities are recognized based on the present value of the future minimum lease payments over the lease term. For this purpose, we consider only payments that are fixed and determinable at the time of commencement.

As our lease does not provide an implicit rate, we use our incremental borrowing rate based on the information available at commencement date in determining the present value of future payments. We account for fixed lease components separately from non-lease components.

We elected the practical expedient to not record leases with an initial term of 12 months or less on the balance sheet and recognize the associated lease payments in the consolidated statements of operations on a straight-line basis over the lease term.

Liability Related to the Sale of Future Royalties

We treat the liability related to the sale of future royalties as debt, amortized under the effective interest rate method over the estimated life of the Jemperli Royalty Monetization Agreement and the Zejula Royalty Monetization Agreement. See Note 5. The amortization of the liability related to the sale of future revenue is based on our current estimates of future royalty

payments. Royalty and milestone revenue will be recognized as earned and the payments made will be recorded as a reduction of the liability when paid.

Debt Issuance Costs

Debt issuance costs related to a recognized debt liability are deferred and amortized over the term of the debt using the effective interest method. These costs are recorded as a direct reduction to the carrying value of the debt on the balance sheet and the amortization expense is included in non-cash interest expense in the statement of operations.

Non-Cash Interest Expense on the Liability Related to the Sale of Future Royalties

The total threshold of royalties to be paid, less the net proceeds received will be recorded as non-cash interest expense over the life of the liability. We impute interest on the unamortized portion of the liability using the effective interest method and record expense based on the timing of payments received over the term of the Jemperli Royalty Monetization Agreement and the Zejula Royalty Monetization Agreement. Over the course of the agreement, the actual interest rate will be affected by the timing of royalty and milestone payments made and changes in the forecasted revenue.

Revenue Recognition

Revenue is recognized in accordance with revenue recognition accounting guidance, which utilizes five basic steps to determine whether revenue can be recognized and to what extent: (i) identify the contract with a customer; (ii) identify the performance obligation; (iii) determine the transaction price; (iv) allocate the transaction price; and (v) determine the recognition period.

Performance Obligations. We evaluate deliverables on a contract-by-contract basis to determine whether each deliverable represents a good or service that is distinct or has the same pattern of transfer as other deliverables. A deliverable is considered distinct if the customer can benefit from the good or service independently of other goods/services either in the contract or that can be obtained elsewhere, without regard to contract exclusivity, and the entity’s promise to transfer the good or service to the customer is separately identifiable from other promises in the contact. If the deliverable is not considered distinct, we combine such deliverables and account for them as a single performance obligation. We allocate the consideration to each deliverable at the inception of the arrangement based on the transaction price.

Our performance obligations may include the following:

•License Arrangements. The performance obligations under our collaboration and license agreements generally include exclusive or nonexclusive licenses to one or more products generated using our technologies. Licenses for multiple antibodies within a single contract are generally combined as they have substantially the same pattern of transfer to the customer. Historically, our licenses have held no value to the customer, as the antibodies were in the discovery phase and required our expertise for further development. Accordingly, licenses are not considered distinct.

•Research and Development Services. The performance obligations under our collaboration and license agreements generally include research and development services we perform on behalf of or with our collaborators. As discussed within license arrangements above, our licenses have historically held no value without the research and development services we provide. As we generally only provide research and development services for internally generated antibodies that require a license to be utilized by a third party, our research and development services are not considered distinct.

•Steering Committee Meetings. The performance obligations under our collaboration and license agreements may also include our participation on steering committees, which allows us to direct the progression of our discovery programs. As these steering committees would not occur or benefit the customer without the use of our licenses, these are not considered distinct.

We recognize consideration allocated to a performance obligation as the performance obligation is satisfied, and the determination as to whether consideration is recognized over time or at a point in time is made upon contract inception. For our collaboration agreements, this is generally over the period in which research and development services have been performed. There were no new agreements with performance obligations entered into during the year ended December 31, 2023.

Transaction Price. Our collaboration and license agreements generally include both fixed and variable consideration. Fixed payments, such as those for upfront fees are included in the transaction price at contract value, while variable consideration such as reimbursement for research and development services, milestone and royalty payments are estimated and then evaluated for constraints upon inception of the contract and evaluated on a quarterly basis thereafter. Research and development services are updated for actual invoices. Given the nature of our agreements, milestones are estimated using the most likely amount and are evaluated on a quarterly basis. Upon commercialization, royalty payments will be recognized in the period incurred.

Royalty Revenue

We receive royalty revenue on sales by our partners of products covered by patents or contract rights that we own and net sales of their approved drugs, where we have concluded the license is the predominant item to which the royalties relate. We do not have future performance obligations under these license arrangements. We generally satisfy our obligation to grant intellectual property rights on the effective date of the contract. However, we apply the royalty recognition constraint required under the guidance for sales-based royalties, which requires a sales-based royalty to be recorded when the underlying sale occurs. Therefore, royalties on sales of products commercialized by our partners are recognized in the quarter the product is sold. Our partners generally report sales information to us on a quarter lag. Thus, we estimate the expected royalty proceeds based on an analysis of our partners’ historical experience including their publicly announced sales. Differences between actual and estimated royalty revenues are adjusted for in the period in which they become known, typically the following quarter. As of December 31, 2023, there have not been material differences between actual and estimated royalty revenues.

Research and Development Expenses

Research and development costs primarily include third-party clinical and preclinical research and development services such as manufacturing, laboratory and related supplies, salaries and personnel-related costs, in-licensing fees, outside services, and an allocation of information technology, and facility overhead costs.

Costs associated with research and development activities are expensed as incurred. We account for nonrefundable advance payments for goods and services that will be used in future research and development activities as expense when the service has been performed or when the goods have been received. We estimate research and development costs incurred during the period, which impacts the amount of accrued expenses and prepaid balances related to such costs as of each balance sheet date. This process involves reviewing open contracts and purchase orders, communicating with our personnel and service providers to identify services that have been performed on our behalf and estimating the level of service performed and the associated cost incurred for the service when we have not yet been invoiced or otherwise notified of the actual cost. The majority of our service providers invoice us monthly in arrears for services performed or when contractual milestones are met. We make estimates of our accrued expenses as of each balance sheet date based on facts and circumstances known to us at that time. We periodically confirm the accuracy of our estimates with the service providers and make adjustments if necessary. The significant estimates in our accrued research and development expenses include the costs incurred for services performed by our vendors in connection with research and development activities for which we have not yet been invoiced.

Upfront and milestone payments incurred under our in-licensing agreements are expensed as acquired in-process research and development in the period in which they are incurred, provided that the technology or method has no alternative future use.

Acquired In-process Research and Development

Acquired in-process research and development costs consist of upfront payments incurred in connection with the acquisition of licensing of products or technologies that do not meet the definition of a business under the Accounting Standards of Codification Topic 805, Business Combinations.

Stock-Based Compensation

We recognize stock-based compensation expense using a fair-value-based method for costs related to all share-based payments, including stock options. Stock-based compensation cost for stock options granted to our employees and directors is measured at the grant date based on the fair-value of the award which is estimated using the Black-Scholes option-pricing model, and is recognized as expense over the requisite service period on a straight-line basis. We recognize forfeitures in the period in which forfeitures occur and record stock-based compensation expense as though all awards are expected to vest.

We record the expense for stock-based compensation awards subject to performance-based milestone vesting over the requisite service period when management determines that achievement of the milestone is probable. Management evaluates when the achievement of a performance-based milestone is probable based on the expected satisfaction of the performance conditions at each reporting date.

No tax benefits for stock-based compensation have been recognized in the statements of changes in stockholders’ equity or cash flows. We have not recognized, and do not expect to recognize in the near future, any tax benefit related to stock-based compensation cost as a result of our full valuation allowance on net deferred tax assets and net operating loss carryforwards.

Income Taxes

We account for income taxes under the asset and liability method. Under this method, deferred tax assets and liabilities are determined based on differences between financial reporting and tax basis of assets and liabilities and are measured using enacted tax rates and laws that are expected to be in effect when the differences are expected to be recovered or settled. Realization of deferred tax assets is dependent upon future taxable income. A valuation allowance is recognized if it is more likely than not that some portion or all of a deferred tax asset will not be realized based on the weight of available evidence, including expected future earnings.

We recognize an uncertain tax position in our consolidated financial statements when we conclude that a tax position is more likely than not to be sustained upon examination based solely on technical merits. Only after a tax position passes the first step of recognition will measurement be required. Under the measurement step, the tax benefit is measured as the largest amount of benefit that is more likely than not to be realized upon effective settlement. This is determined on a cumulative probability basis. The full impact of any change in recognition or measurement is reflected in the period in which such change occurs. We have elected to accrue any interest or penalties related to income taxes as part of our income tax expense.

Functional Currency of Foreign Operations

Our Australian subsidiary operates in a U.S. dollar functional currency environment. Assets and liabilities of our foreign subsidiary that are not denominated in the functional currency are remeasured into U.S. dollars at foreign currency exchange rates in effect at the balance sheet date except for nonmonetary assets and capital accounts, which are remeasured at historical foreign currency exchange rates in effect at the date of transaction. Expenses are generally remeasured at monthly foreign currency exchange rates which approximate average rates in effect during each period. Net realized and unrealized gains and losses from foreign currency transactions and remeasurement are reported in other income (expense), net, in the consolidated statements of operations.

Comprehensive Income (Loss)

Comprehensive income (loss) represents all changes in stockholders’ equity except those resulting from distributions to stockholders. Our unrealized gain and losses on available for sale investments represent the only component of other comprehensive income (loss) that is excluded from the reported net income (loss).

Net Loss Per Common Share

Basic net loss per common share is computed by dividing net loss by the weighted-average number of common shares outstanding during the period. Diluted net loss per share is computed by dividing net loss by the weighted-average number of common equivalent shares outstanding for the period, as well as any dilutive effect from outstanding stock options and warrants using the treasury stock method. For each period presented, there is no difference in the number of shares used to calculate basic and diluted net loss per share.


	Year Ended December 31,
(in thousands)		2023	2022	2021

Options to purchase common stock		4,279	3,602	3,631
Restricted stock units		521	375	—

Total		4,800	3,977	3,631

Accounting Pronouncements

We have implemented all new accounting pronouncements that are in effect and may have an impact on our consolidated financial statements. Unless otherwise discussed, we believe the impact of any recently issued pronouncements, not yet effective will not have a material impact on our consolidated financial statements.

Recent Accounting Pronouncements Not Yet Adopted

In November 2023, the Financial Accounting Standards Board (FASB) issued Accounting Standard Update (ASU) 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures, which requires enhanced disclosure of significant segment expenses on an annual and interim basis. The guidance will be effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning December 15, 2024, with early adoption permitted. Upon adoption, the guidance should be applied retrospectively to all prior periods presented in the financial statements. We are currently assessing the impact that this standard will have on our consolidated financial statements.

In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures Income Taxes, which improves the transparency of income tax disclosures by requiring consistent categories and greater disaggregation of information in the effective tax rate reconciliation and income taxes paid disaggregated by jurisdiction. It also includes certain other amendments to improve the effectiveness of income tax disclosures. This guidance will be effective for the annual periods beginning after December 15, 2024. Early adoption is permitted. Upon adoption, the guidance can be applied prospectively or retrospectively. We are currently assessing the impact that this standard will have on our consolidated financial statements.

Collaborative Research and Development Agreements

12 Months Ended

Dec. 31, 2023

Revenue from Contract with Customer [Abstract]

Collaborative Research and Development Agreements

GlaxoSmithKline Collaboration

In March 2014, we entered into a Collaboration and Exclusive License Agreement with GSK (the “GSK Agreement”) with TESARO, Inc. (“Tesaro”), an oncology-focused biopharmaceutical company now a part of GlaxoSmithKline (Tesaro and GlaxoSmithKline are hereinafter referred to, collectively, as “GSK”). Currently, under the GSK Agreement, GSK is developing Jemperli (dostarlimab), an anti-PD-1 antagonist antibody, as a monotherapy for various solid tumor indications. In addition, GSK is developing dostarlimab in combination with additional therapies under the collaboration, including with another development program from the GSK Agreement: cobolimab, an anti-TIM-3 antibody, in 2L NSCLC. In October 2023, Amendment No. 5 to the GSK Agreement was agreed by both parties to terminate the anti-LAG-3 antagonist antibody development program under the GSK Agreement. In accordance with the GSK Agreement and the amendment, we have regained full global rights to the anti-LAG-3 antagonist antibody development program.

For each remaining development program under the GSK Agreement, we are eligible to receive milestone payments if certain preclinical and clinical trial events are achieved by GSK, if certain U.S. and European regulatory submissions and approvals in multiple indications are achieved, and upon the achievement of specified levels of annual worldwide net sales. We will also be eligible to receive tiered 4-8% royalties related to worldwide net sales of products developed under the collaboration. On October 23, 2020, Amendment No. 3 to the GSK Agreement (the “Amendment”) was agreed to by both parties to permit GSK to conduct development and commercialization in combination with any third-party molecules of Zejula, an oral, once-daily poly (ADP-ribose) polymerase (PARP) inhibitor. Under the Amendment, we were granted increased royalties upon sales of Jemperli, equal to 8% of Net Sales (as defined in the GSK Agreement) below $1.0 billion and from 12% up to 25% of Net Sales above $1.0 billion. Unless earlier terminated by either party upon specified circumstances, the GSK Agreement will terminate, with respect to each specific developed product, upon the later of the 12th anniversary of the first commercial sale of the product or the expiration of the last to expire of any patent.

We assessed these arrangements in accordance with ASC 606 and concluded that the contract counterparty, GSK, is a customer. We identified the following material promises under the GSK Agreement: (1) the licenses under certain patent rights and transfer of certain development and regulatory information, (2) research and development (“R&D”) services, and (3) joint steering committee meetings. We considered the research and discovery capabilities of GSK for these specific programs and the fact that the discovery and optimization of these antibodies is proprietary and could not, at the time of contract inception, be provided by other vendors, to conclude that the license does not have stand-alone functionality and is therefore not distinct. Additionally, we determined that the joint steering committee participation would not have been provided without the R&D services and GSK Agreement. Based on these assessments, we identified all services to be interrelated and therefore concluded that the promises should be combined into a single performance obligation at the inception of the arrangement.

As of December 31, 2023, the transaction price for the GSK Agreement and Amendments includes the upfront payment, research reimbursement revenue and milestones and royalties earned to date, which are allocated in their entirety to the single performance obligation.

We recognized $17.2 million in royalty revenue during the year ended December 31, 2023 related to GSK’s net sales of Jemperli and Zejula during the period, which we estimate based on either GSK’s prior sales experience or actuals. Of the royalty revenue recognized during the year ended December 31, 2023, $13.8 million is Jemperli non-cash revenue related to the Jemperli Royalty Monetization Agreement, $3.4 million is Zejula non-cash revenue related to the Zejula Monetization Agreement, each of such agreements as described in Note 5. We recognized $5.3 million in royalty revenue during the year ended December 31, 2022, related to GSK’s net sales of Jemperli and Zejula during the period based on GSK’s prior sales experience or actuals. Of the royalty revenue recognized during the year ended December 31, 2022, $2.3 million is Jemperli non-cash revenue related to the Jemperli Royalty Monetization Agreement, $1.6 million is Zejula revenue prior to the Zejula Royalty Monetization Agreement and $1.4 million is Zejula non-cash revenue related to the Zejula Royalty Monetization Agreement. GSK reports sales information to us on a one quarter lag and differences between actual and estimated royalty revenues will be adjusted in the following quarter. All royalty revenue related to Zejula global net sales starting July 2022, will be paid directly to a wholly-owned subsidiary of DRI Healthcare Trust pursuant to the Zejula Royalty Monetization Agreement, as described in Note 5.

No clinical milestones were recognized during the year ended December 31, 2023 and we recognized one clinical milestone for $5.0 million during the year ended December 31, 2022. No other future clinical or regulatory milestones have been included in the transaction price, as all milestone amounts were subject to the revenue constraint. As part of the constraint evaluation, we considered numerous factors including the fact that the receipt of milestones is outside of our control and contingent upon success in future clinical trials, an outcome that is difficult to predict, and GSK’s efforts. Any consideration related to sales-based milestones, including royalties, will be recognized when the related sales occur as they were determined to relate predominantly to the intellectual property license granted to GSK and therefore have also been excluded from the

transaction price. We will re-evaluate the variable transaction price in each reporting period and as uncertain events are resolved or other changes in circumstances occur.

Milestones under the GSK Agreement are as follows:

Anti-PD-1

(Jemperli/Dostarlimab)

Anti-TIM-3
(GSK4069889A/Cobolimab)

Milestone Event

Amount

Quarter Recognized

Amount

Quarter Recognized

Initiated in vivo toxicology studies using good laboratory practices (GLPs)

$1.0M

Q2'15

$1.0M

Q4'15

IND clearance from the FDA

$4.0M

Q1'16

$4.0M

Q2'16

Phase 2 clinical trial initiation

$3.0M

Q2'17

$3.0M

Q4'17

Phase 3 clinical trial initiation - first indication

$5.0M

Q3'18

$5.0M

Q4'22

Phase 3 clinical trial initiation - second indication

$5.0M

Q2'19

$5.0M

—

Filing of the first BLA(1) - first indication

$10.0M

Q1'20

$10.0M

—

Filing of the first MAA(2) - first indication

$5.0M

Q1'20

$5.0M

—

Filing of the first BLA - second indication

$10.0M

Q1'21

$10.0M

—

First BLA approval - first indication

$20.0M

Q2'21

$20.0M

—

First MAA approval - first indication

$10.0M

Q2'21

$10.0M

—

First BLA approval - second indication

$20.0M

Q3'21

$20.0M

—

Filing of the first MAA - second indication(3)

$5.0M

—

$5.0M

—

First MAA approval - second indication(3)

$10.0M

—

$10.0M

—

First commercial sales milestone(3)

$15.0M

—

$15.0M

—

Second commercial sales milestone(3)

$25.0M

—

$25.0M

—

Third commercial sales milestone(3)

$50.0M

—

$50.0M

—

Fourth commercial sales milestone

$75.0M

—

$75.0M

—

Milestones recognized through December 31, 2023

$93.0M

—

$13.0M

—

Milestones that may be recognized in the future

$180.0M

—

$260.0M

—

(1)Biologics License Application (“BLA”)

(2)Marketing Authorization Application (“MAA”)

(3)For Jemperli, the filing and approval of the first MAA for a second indication and first three commercial sales milestones are included as part of the royalty monetization agreement with Sagard, see Note 5. Cash is generally received within 30 days of milestone achievement.

We recognized $17.2 million in revenue under the GSK Agreement during the year ended December 31, 2023, of which $17.2 million was related to royalty revenue and none was related to milestone revenue, as there were no milestones earned during the year. We recognized $10.3 million in revenue during the year ended December 31, 2022, of which $5.3 million was related to royalty revenue and $5.0 million was related to one milestone. We recognized $63.2 million in revenue during the year ended December 31, 2021, of which $60.0 million was related to four milestones and $3.2 million was related to royalty revenue.

Centessa

On November 24, 2023, we entered into an exclusive license agreement (the “Centessa Agreement”) with Centessa Pharmaceuticals (UK) Limited (“Centessa”), pursuant to which we acquired the exclusive global development and commercialization rights to a blood dendritic cell antigen 2 (BDCA2) modulator antibody portfolio, including lead asset CBS004 (renamed ANB101), CBS008 (renamed ANB102) and the related family of backup antibodies, for the treatment of autoimmune and inflammatory diseases.

In connection with the Centessa Agreement, we paid Centessa an upfront cash payment of $4.0 million and an additional cash payment of $3.0 million as reimbursement to Centessa for manufacturing costs incurred. There were $0.3 million in transaction costs incurred. The total transaction amount of $7.3 million was expensed as in-process research and development in December 2023, and the $7.0 million in payments made as of December 31, 2023 were classified as an operating activity in

the statement of cash flows. We accounted for the transaction as an asset acquisition as the set of acquired assets did not constitute a business.

Under the term of the agreement, Centessa may be entitled to receive potential future payments of up to $10.0 million upon the achievement of a certain event-based milestone and would be entitled to receive on a product-by-product and country-by-country basis, a royalty of low single digits on annual net sales of any product in the territory in each calendar year. As of December 31, 2023, achievement of the milestone is not probable and, therefore, we have not recognized a liability for the associated $10.0 million contingent consideration.

Fair Value Measurements and Available for Sale Investments (Tables)

12 Months Ended

Dec. 31, 2023

Fair Value Disclosures [Abstract]

Schedule of Assets and Liabilities that Require Fair Value Measurements on a Recurring Basis

The following table summarizes our assets and liabilities that require fair value measurements on a recurring basis and their respective input levels based on the fair value hierarchy:


	Fair Value Measurements at End of Period Using:
(in thousands)	Fair Value		Quoted Market Prices for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
At December 31, 2023
Money market funds(1)	$	27,789	$	27,789	$	—	$	—
Mutual funds(1)	6,286		6,286		—		—
U.S. Treasury securities(2)	325,714		325,714		—		—
Certificates of deposit(2)	244		—		244		—
Agency securities(2)	20,253		—		20,253		—
Commercial and corporate obligations(2)	35,754		—		35,754		—

At December 31, 2022
Money market funds(1)	$	29,702	$	29,702	$	—	$	—
Mutual funds(1)	41,812		41,812		—		—
U.S. Treasury securities(2)	374,527		374,527		—		—
Certificates of deposit(2)	2,856		—		2,856		—
Agency securities(2)	74,602		—		74,602		—
Commercial and corporate obligations(2)	60,883		—		60,883		—

(1) Included in cash and cash equivalents in the accompanying consolidated balance sheets.

(2) Included in short-term or long-term investments in the accompanying consolidated balance sheets depending on the respective maturity date.

Schedule of Available-for-sale Investments

The aggregate market value, cost basis, and gross unrealized gains and losses of available-for-sale investments by security type, classified in cash equivalents, short-term and long-term investments as of December 31, 2023 are as follows:


(in thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Total Fair Value
Agency securities(1)	$	20,322	$	—	$	(69)	$	20,253
Certificates of deposit(2)	246		—		(2)		244
Commercial and corporate obligations(3)	35,760		77		(83)		35,754
US Treasury securities(4)	326,227		122		(635)		325,714
Total available-for-sale investments	$	382,555	$	199	$	(789)	$	381,965

(1) Of our outstanding agency securities, $20.3 million have maturity dates of less than one year and $0.0 million have a maturity date of between one to two years as of December 31, 2023.

(2) Of our outstanding certificates of deposit, $0.2 million have a maturity date of less than one year and $0.0 million have a maturity date of between one to two years as of December 31, 2023.

(3) Of our outstanding commercial and corporate obligations, $25.8 million have maturity dates of less than one year and $10.0 million have a maturity date of between one to two years as of December 31, 2023.

(4) Of our outstanding U.S. Treasury securities, $308.6 million have maturity dates of less than one year and $17.1 million have a maturity date of between one to two years as of December 31, 2023.


(in thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Total Fair Value
Agency securities(1)	$	75,504	$	11	$	(913)	$	74,602
Certificates of deposit(2)	2,915		—		(59)		2,856
Commercial and corporate obligations(3)	61,791		8		(916)		60,883
US Treasury securities(4)	377,697		19		(3,189)		374,527
Total available-for-sale investments	$	517,907	$	38	$	(5,077)	$	512,868

(1) Of our outstanding agency securities, $57.1 million have maturity dates of less than one year and $17.5 million have a maturity date of between one to two years as of December 31, 2022.

(2) Of our outstanding certificates of deposit, $2.6 million have a maturity date of less than one year and $0.3 million have a maturity date of between one to two years as of December 31, 2022.

(3) Of our outstanding commercial and corporate obligations, $44.0 million have maturity dates of less than one year and $16.9 million have a maturity date of between one to two years as of December 31, 2022.

(4) Of our outstanding U.S. Treasury securities, $266.2 million have maturity dates of less than one year and $108.3 million have a maturity date of between one to two years as of December 31, 2022.

Schedule of Unrealized Loss and Fair Values in a Loss Position

The following tables present gross unrealized losses and fair values for those investments that were in an unrealized loss position as of December 31, 2023 and December 31, 2022, aggregated by investment category and the length of time that individual securities have been in a continuous loss position:


	December 31, 2023
	Less than 12 Months				12 Months or Greater				Total
(in thousands)	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
Agency securities	$	2,530	$	(1)	$	17,723	$	(68)	$	20,253	$	(69)
Certificates of Deposit	—		—		244		(2)		244		(2)
Commercial and corporate obligations	5,160		(9)		15,200		(74)		20,360		(83)
US Treasury Securities	98,840		(110)		99,000		(525)		197,840		(635)
Total	$	106,530	$	(120)	$	132,167	$	(669)	$	238,697	$	(789)


	December 31, 2022
	Less than 12 Months				12 Months or Greater				Total
(in thousands)	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
Agency securities	$	61,117	$	(843)	$	3,437	$	(70)	$	64,554	$	(913)
Certificates of Deposit	481		(10)		2,375		(49)		2,856		(59)
Commercial and corporate obligations	44,213		(624)		14,778		(292)		58,991		(916)
US Treasury Securities	298,575		(2,667)		41,937		(522)		340,513		(3,189)
Total	$	404,386	$	(4,144)	$	62,527	$	(933)	$	466,914	$	(5,077)

Balance Sheet Accounts and Supplemental Disclosures - Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 8,316	$ 7,665
Less: accumulated depreciation and amortization	(6,218)	(5,576)
Total property and equipment, net	2,098	2,089
Laboratory equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	6,473	5,869
Office furniture and equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	1,640	1,593
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 203	$ 203

Stockholders' Equity - Narrative (Details) - USD ($)	12 Months Ended
Stockholders' Equity - Narrative (Details) - USD ($)	Dec. 31, 2023	Jan. 31, 2023	Dec. 31, 2022	Nov. 30, 2022
Class of Stock [Line Items]
Common stock, shares authorized (in shares)	500,000,000		500,000,000
Common stock, shares issued (in shares)	26,596,765		28,513,000
Common stock, shares outstanding (in shares)	26,596,765		28,513,000
Authorized repurchase amount		$ 50,000,000
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001	$ 0.001
Open Market Sales Agreement
Class of Stock [Line Items]
Aggregate offering of (up to)				$ 150,000,000
Shares sold (in shares)	0

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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+ Details

Commitments and Contingencies

12 Months Ended

Dec. 31, 2023

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

Operating Leases

On May 4, 2020, we entered into a lease agreement with Wateridge Property Owner, LP, with respect to facilities in the building at 10770 Wateridge Circle, San Diego, California 92121 (the “Lease Agreement”). Under the Lease Agreement, we agreed to lease approximately 45,000 square feet of space for a term of 124 months, beginning on April 5, 2021. The terms of the Lease Agreement provide us with an option to extend the term of the lease for an additional five years, as well as a one-time option to terminate the lease after seven years with the payment of a termination fee. The exercise of the lease option is at our sole discretion, which we currently do not anticipate exercising and as such was not recognized as part of the ROU asset and lease liability. The monthly base rent was initially $4.20 per rentable square foot and is increased by 3% annually. Under the Lease Agreement, we are also responsible for our pro rata share of real estate taxes, building insurance, maintenance, direct expenses, and utilities. Upon lease commencement, on April 5, 2021, we recognized an ROU asset of $20.6 million, with a corresponding lease liability of $20.7 million on the consolidated balance sheets. The ROU asset includes adjustments for prepayments, initial direct costs, and lease incentives. As of December 31, 2023, we have recorded $0.3 million as a security deposit in accordance with the terms of the Lease Agreement.

Our lease payments are fixed, and we recognize lease expense for leases on a straight-line basis over the lease term. Operating lease ROU assets and lease liabilities are recorded based on the present value of the future minimum lease payments over the lease term at commencement date. As our lease does not provide an implicit rate, we used our incremental borrowing rate based on the information available at the lease commencement date in determining the present value of future payments. The weighted-average discount rate used was 4.0% and the weighted-average remaining lease term is approximately 7.7 years.

The following non-cancellable office lease costs are included in our consolidated statements of cash flow (in thousands):


		Year Ended December 31,
Leases	Classification on the Cash Flow	2023		2022		2021
Operating lease cost	Operating	$	2,478	$	2,478	$	2,213
Cash paid for amounts included in the measurement of lease liabilities	Operating	2,386		2,316		705

At December 31, 2023, the future minimum annual obligations for the Company’s operating lease liabilities are as follows:


Years Ending December 31, (in thousands)
2024	$	2,457
2025	2,531
2026	2,607
2027	2,685
2028	2,766
Thereafter	7,788
Total minimum payments required	$	20,834
Less: imputed interest	(3,020)
Total	$	17,814

Other Commitments and Contingencies

We have entered into agreements with certain vendors for the provision of goods and services, which includes manufacturing services with contract manufacturing organizations and development services with contract research organizations. These agreements may include certain provisions for purchase obligations and termination obligations that could require payments for the cancellation of committed purchase obligations or for early termination of the agreements. The amount of the cancellation or termination payments vary and are based on the timing of the cancellation or termination and the specific terms of the agreement.

Guarantees and Indemnifications

We enter into standard indemnification arrangements in the ordinary course of business. Pursuant to certain of these arrangements, we indemnify, hold harmless, and agree to reimburse the indemnified parties for losses suffered or incurred by the indemnified party for third-party claims in connection with our breach of the agreement, our negligence or willful misconduct in connection with the agreement, or any trade secret, copyright, patent or other intellectual property infringement claim with respect to our technology. The term of these indemnification arrangements is generally perpetual. The maximum potential amount of future payments we could be required to make under these agreements is not determinable because it involves claims that may be made against us in the future, but have not yet been made.

We indemnify our officers and directors for certain events or occurrences, subject to certain limits, while the officer or director is or was serving in such capacity, as permitted under Delaware law, in accordance with our certificate of incorporation and bylaws, and pursuant to agreements providing for indemnification entered into with our officers and directors. The term of the indemnification period lasts as long as an officer or director may be subject to any proceeding arising out of acts or omissions of such officer or director in such capacity.

The maximum amount of potential future indemnification of directors and officers is unlimited; however, we currently hold director and officer liability insurance. This insurance allows the transfer of risk associated with our exposure and may enable us to recover a portion of any future amounts paid.

We believe that the fair value of these indemnification obligations is minimal. Accordingly, we have not recognized any liabilities relating to these obligations for any period presented.

Fair Value Measurements and Available for Sale Investments - Narrative (Details) - USD ($)	Dec. 31, 2023	Dec. 31, 2022
Fair Value Disclosures [Abstract]
Available for sale investments	$ 789,000	$ 5,077,000
Unrealized loss position for greater than 12 months	669,000	$ 933,000
Allowance for credit losses	$ 0

Audit Information	12 Months Ended
Audit Information	Dec. 31, 2023
Auditor Information [Abstract]
Auditor Name	KPMG LLP
Auditor Location	San Diego, California
Auditor Firm ID	185

Income Taxes

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Income Taxes

The components of loss before income tax provision consist of the following:


	Year Ended December 31,
(in thousands)	2023		2022		2021
U.S.	$	(163,580)	$	(128,650)	$	(57,741)
Foreign	(43)		(50)		(55)
Consolidated net loss before income taxes	$	(163,623)	$	(128,700)	$	(57,796)

For the years ended December 31, 2023 and 2022, we recognized an income tax benefit of $4,000 and income tax provision of $24,000, respectively, related to state income taxes. For the year ended December 31, 2021, we recognized no benefit or provision for income taxes.

Significant components of our deferred tax assets and liabilities are as follows:


	December 31,
(in thousands)	2023		2022
Deferred Tax Assets:
Net operating loss carryforwards	$	72,777	$	66,160
Section 174 Capitalized R&D	37,240		16,570
Research and development credits	19,058		12,844
Equity compensation	10,533		10,021
Deferred Zejula royalty revenue	6,978		7,371
Lease liability	3,912		4,194
Other, net	7,201		3,458
Total deferred tax assets	157,699		120,618
Deferred Tax Liabilities:
ROU asset	(3,552)		(3,859)
Other, net	(2,658)		—
Fixed assets	(122)		(189)
Total deferred tax liabilities	(6,332)		(4,048)
Net deferred tax assets	151,367		116,570
Less: valuation allowance	(151,367)		(116,570)
Deferred tax assets, net of valuation allowance	$	—	$	—

We have recorded a full valuation allowance against our net deferred tax assets due to the uncertainty surrounding the realization of such assets. Management has determined it more likely than not that the deferred tax assets are not realizable due to our historical loss position.

As of December 31, 2023, we had federal and state net operating loss carryforwards (“NOLs”), of $313.8 million and $73.3 million, respectively. The federal and state NOLs generated prior to 2018 will begin to expire in 2030 and 2028, respectively, unless previously utilized. The federal NOL includes $261.7 million of net operating losses generated in 2018 and after. Federal net operating losses generated in 2018 and after carryover indefinitely and may generally be used to offset up to 80% of future taxable income. As of December 31, 2023, we had federal and state research tax credit carryforwards of approximately $12.1 million and $14.4 million, respectively. The federal research tax credit carryforwards will begin to expire in 2041 and the state research tax credits carryforward indefinitely. We also have foreign tax losses of $3.2 million, which will carry forward indefinitely, subject to a continuity of ownership test.

The above NOL carryforward and the federal and state research tax credit carryforwards may be subject to an annual limitation under section 382 and 383 of the Internal Revenue Code of 1986, as amended (the “Code”), and similar state provisions if we experience one or more ownership changes which would limit the amount of NOL and tax credit carryforwards that can be utilized to offset future taxable income and tax, respectively. In general, an ownership change as defined by Section 382 and 383, results from transactions increasing ownership of certain stockholders or public groups in the stock of the corporation by more than 50 percentage points over a three-year period. In September 2015, we completed a Section 382 analysis through December 31, 2014 and determined that there was an ownership change in 2007 that may limit the utilization of approximately $5.3 million and $5.4 million in federal and state NOLs, respectively, and $0.2 million in both federal and state research tax credits. We subsequently extended the analysis period of the study through December 31, 2022, noting ownership changes on January 31, 2017 and March 8, 2021. To reflect the impact of the January 31, 2017 and March 8, 2021 ownership changes, we reduced federal research credit carryforwards by approximately $15.0 million. Our use of federal and state NOLs and research credits could be limited further by the provisions of Section 382 of the U.S. Internal Revenue Code of 1986, as amended, depending upon the timing and amount of additional equity securities that we have issued or will issue. State NOL carryforwards may be similarly limited. If a change in ownership were to have occurred, NOL and tax credits carryforwards could be eliminated or restricted. If eliminated, the related asset would be removed from the deferred tax asset schedule with a corresponding reduction in the valuation allowance. Due to the existence of the valuation allowance, limitations created by ownership changes, if any, will not impact our effective tax rate.

The following is a reconciliation of the expected statutory federal income tax provision to our actual income tax provision:


	Year Ended December 31,
(in thousands)	2023		2022		2021
Expected income tax benefit at federal statutory tax rate	$	(34,361)	$	(27,026)	$	(12,138)
State income taxes, net of federal benefit	(1,912)		(800)		(142)
Permanent items	56		27		17
Equity compensation	2,840		(297)		(708)


Non-deductible compensation	3,693		2,060		—


Research credits	(6,213)		(3,319)		8,087
Other	109		(6)		42
Change in the valuation allowance	35,784		29,385		4,842
Income tax (benefit) expense	$	(4)	$	24	$	—

We recognize a tax benefit from an uncertain tax position when it is more likely than not that the position will be sustained upon examination, including resolutions of any related appeals or litigation processes, based on the technical merits. Income tax positions must meet a more likely than not recognition at the effective date to be recognized. As of December 31, 2023 and 2022, we had no unrecognized tax benefits that, if recognized and realized, would affect the effective tax rate due to the valuation allowance against deferred tax assets. The following table summarizes the activity related to our unrecognized tax benefits:


	Year Ended December 31,
(in thousands)	2023		2022
Balance at the beginning of the year	$	3,369	$	2,473
Increase related to prior year tax positions	153		—
Increase related to current year tax positions	1,494		896
Balance at the end of the year	$	5,016	$	3,369

If recognized, these amounts would not affect our effective tax rate, since they would be offset by an equal corresponding adjustment in the deferred tax asset valuation allowance. We do not anticipate there will be a significant change in unrecognized tax benefits within the next 12 months.

Our policy is to recognize interest and penalties related to income tax matters in the provision for income taxes. As of December 31, 2023 and 2022, there were no interest or penalties on uncertain tax benefits.

We file income tax returns in the United States, California, various U.S. state jurisdictions and Australia. Due to our losses incurred, we are essentially subject to income tax examination by tax authorities from inception to date.

- 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
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480990/946-20-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(h)(2))
-Publisher FASB
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-Name Accounting Standards Codification
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-14

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
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-Name Accounting Standards Codification
-Section 50
-Paragraph 21
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-URI https://asc.fasb.org//1943274/2147482685/740-10-50-21

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 270
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482526/740-270-50-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 17
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-17

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 6.I.5.Q1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479360/740-10-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 11.C)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479360/740-10-S99-2

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482603/740-30-50-2

+ Details

Sale of Future Royalties (Tables)

12 Months Ended

Dec. 31, 2023

Other Liabilities Disclosure [Abstract]

Schedule of Royalty Transaction Activity

The following table shows the activity within the liability account for the year ended December 31, 2023:


(in thousands)	December 31, 2023
Liability related to sale of future Jemperli royalties and milestones - balance at 12/31/2022	$	269,540

Issuance costs related to the sale of future royalties	37
Amortization of issuance costs	39
Royalty and milestone payments to Sagard	(8,600)
Non-cash interest expense recognized	17,074
Liability related to sale of future royalties and milestones - ending balance	$	278,090

The following table shows the activity within the liability account for the year ended December 31, 2023:


(in thousands)	December 31, 2023
Liability related to sale of future Zejula royalties - balance at 12/31/2022	$	34,873


Amortization of issuance costs	28
Royalty payments to DRI	(3,126)
Non-cash interest expense recognized	942
Liability related to sale of future royalties - ending balance	$	32,717

Consolidated Statements of Stockholders’ Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Stockholders' equity, beginning balance (in shares) at Dec. 31, 2020		27,356,000
Stockholders' equity, beginning balance at Dec. 31, 2020	$ 396,731	$ 27	$ 660,665	$ (4)	$ (263,957)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock from exercises of options and employee stock purchase plan (in shares)		291,000
Issuance of common stock from exercises of options and employee stock purchase plan	2,564	$ 1	2,563
Stock-based compensation	15,347		15,347
Comprehensive loss	(418)			(418)
Net loss	(57,796)				(57,796)
Stockholders' equity, ending balance (in shares) at Dec. 31, 2021		27,647,000
Stockholders' equity, ending balance at Dec. 31, 2021	356,428	$ 28	678,575	(422)	(321,753)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock from exercises of options and employee stock purchase plan (in shares)		866,000
Issuance of common stock from exercises of options and employee stock purchase plan	11,867	$ 1	11,866
Stock-based compensation	27,356		27,356
Comprehensive loss	(4,824)			(4,824)
Net loss	$ (128,724)				(128,724)
Stockholders' equity, ending balance (in shares) at Dec. 31, 2022	28,513,000	28,513,000
Stockholders' equity, ending balance at Dec. 31, 2022	$ 262,103	$ 29	717,797	(5,246)	(450,477)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock from exercises of options and employee stock purchase plan (in shares)		139,000
Issuance of common stock from exercises of options and employee stock purchase plan	2,421		2,421
Issuance of common stock upon vesting of restricted stock units (in shares)		69,000
Repurchases and retirements of common stock (in shares)		(2,124,000)
Repurchases and retirements of common stock	(50,456)	$ (2)	(50,454)
Stock-based compensation	33,205		33,205
Comprehensive loss	4,449			4,449
Net loss	$ (163,619)				(163,619)
Stockholders' equity, ending balance (in shares) at Dec. 31, 2023	26,596,765	26,597,000
Stockholders' equity, ending balance at Dec. 31, 2023	$ 88,103	$ 27	$ 702,969	$ (797)	$ (614,096)

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares outstanding (in shares)	0	0
Preferred stock, shares issued (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	500,000,000	500,000,000
Common stock, shares issued (in shares)	26,596,765	28,513,000
Common stock, shares outstanding (in shares)	26,596,765	28,513,000

Collaborative Research and Development Agreements - Narrative (Details)			1 Months Ended		3 Months Ended		12 Months Ended
	Nov. 24, 2023 USD ($)	Oct. 23, 2020 USD ($)	Dec. 31, 2023 USD ($)	Mar. 31, 2014	Dec. 31, 2022 USD ($)	Sep. 30, 2018 USD ($)	Dec. 31, 2023 USD ($) milestone	Dec. 31, 2022 USD ($) milestone	Dec. 31, 2021 USD ($) milestone
Disaggregation of Revenue [Line Items]
Collaboration revenue							$ 17,157,000	$ 10,287,000	$ 63,175,000
GSK
Disaggregation of Revenue [Line Items]
Collaboration revenue							17,200,000	10,300,000	63,200,000
GSK \| Collaborative Research and Development Agreement \| Minimum
Disaggregation of Revenue [Line Items]
Royalty percent on net sales				4.00%
GSK \| Collaborative Research and Development Agreement \| Maximum
Disaggregation of Revenue [Line Items]
Royalty percent on net sales				8.00%
GSK \| Collaborative Research and Development Agreement \| Anti-PD-1 (Jemperli/Dostarlimab)
Disaggregation of Revenue [Line Items]
Agreement term following first commercial sale or expiration of the last to expire patent (in years)		12 years
GSK \| Phase 3 clinical trial initiation - first indication \| Anti-PD-1 (Jemperli/Dostarlimab)
Disaggregation of Revenue [Line Items]
Collaboration revenue						$ 5,000,000.0
GSK \| Phase 3 clinical trial initiation - first indication \| Anti-TIM-3 (GSK4069889A/Cobolimab)
Disaggregation of Revenue [Line Items]
Collaboration revenue					$ 5,000,000.0			$ 5,000,000
Number of milestones achieved during period \| milestone								1
GSK \| Royalty Agreement
Disaggregation of Revenue [Line Items]
Collaboration revenue							17,200,000	$ 5,300,000	3,200,000
GSK \| Royalty Agreement, up To $1. 0 billion \| Anti-PD-1 (Jemperli/Dostarlimab)
Disaggregation of Revenue [Line Items]
Royalty percent on net sales		8.00%
Royalty sales		$ 1,000,000,000
GSK \| Royalty Agreement, above $1. 0 billion \| Anti-PD-1 (Jemperli/Dostarlimab)
Disaggregation of Revenue [Line Items]
Royalty sales		$ 1,000,000,000
GSK \| Royalty Agreement, above $1. 0 billion \| Anti-PD-1 (Jemperli/Dostarlimab) \| Minimum
Disaggregation of Revenue [Line Items]
Royalty percent on net sales		12.00%
GSK \| Royalty Agreement, above $1. 0 billion \| Anti-PD-1 (Jemperli/Dostarlimab) \| Maximum
Disaggregation of Revenue [Line Items]
Royalty percent on net sales		25.00%
GSK \| JEMPERLI Royalty Monetization Agreement
Disaggregation of Revenue [Line Items]
Collaboration revenue							13,800,000	2,300,000
Non cash royalty revenue, for sale of future royalties								2,300,000
GSK \| Zejula Revenue
Disaggregation of Revenue [Line Items]
Collaboration revenue								1,600,000
GSK \| Zejula Royalty Monetization Agreement
Disaggregation of Revenue [Line Items]
Collaboration revenue							3,400,000	1,400,000
GSK \| Milestone Agreements
Disaggregation of Revenue [Line Items]
Collaboration revenue							$ 0	$ 5,000,000	$ 60,000,000
Number of milestones achieved during period \| milestone							0	1	4
Centessa \| Collaborative Research and Development Agreement
Disaggregation of Revenue [Line Items]
Potential future payments	$ 10,000,000		$ 10,000,000				$ 10,000,000
Centessa \| Collaborative Research and Development Agreement \| License Agreement, Centessa Pharmaceuticals (UK) Limited
Disaggregation of Revenue [Line Items]
Cash payment	4,000,000		7,000,000
Reimbursement	$ 3,000,000
Transaction costs incurred			300,000
Total transaction			$ 7,300,000

Summary of Significant Accounting Policies (Policies)	12 Months Ended
Summary of Significant Accounting Policies (Policies)	Dec. 31, 2023
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”). The accompanying consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”).
Basis of Consolidation	Basis of Consolidation The accompanying consolidated financial statements include us and our wholly-owned Australian subsidiary. All intercompany accounts and transactions have been eliminated in consolidation. We operate in one reportable segment, and our functional and reporting currency is the U.S. dollar.
Use of Estimates	Use of Estimates The preparation of the accompanying consolidated financial statements in conformity with U.S. GAAP requires our management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements, and reported amounts of revenues and expenses during the reporting periods. Actual results could differ from those estimates. We base our estimates and assumptions on historical experience when available and on various factors that we believe to be reasonable under the circumstances. Significant estimates relied upon in preparing these financial statements include estimates related to revenue recognition, accrued research and development expenses, stock-based compensation, and the liability related to the sale of future royalties. We evaluate our estimates and assumptions on an ongoing basis. Our actual results could differ from these estimates under different assumptions or conditions.
Cash and Cash Equivalents	Cash and Cash Equivalents We consider all highly liquid investments with a maturity at date of purchase of three months or less to be cash equivalents. Cash equivalents consist primarily of money market and mutual funds with original maturities of 90 days or less.
Short Term and Long Term Investments	Short-Term and Long-Term Investments All investments have been classified as “available-for-sale” and are carried at fair value as determined based upon quoted market prices or pricing models for similar securities at period end. Investments with contractual maturities less than 12 months at the balance sheet date are considered short-term investments. Those investments with contractual maturities 12 months or greater at the balance sheet date are considered long-term investments. Dividend and interest income are recognized when earned. Realized gains and losses are included in earnings and are derived using the specific identification method for determining the cost of securities sold. Unrealized gains and losses are reported as a component of 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 cost have resulted from a credit-related loss or other factors. If the decline in fair value is due to credit-related factors, a loss is recognized in net income, whereas if the decline in fair value is not due to credit-related factors, the loss is recorded in other comprehensive income (loss). No credit impairment losses have been recorded during the years ended December 31, 2023, 2022, or 2021.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments that potentially subject us to a concentration of credit risk consist of cash and cash equivalents and certain investments in money market funds, certificates of deposit, agency securities, commercial obligations and U.S. Treasury securities. Bank deposits are diversified between three financial institutions and these deposits may exceed insured limits. We are exposed to credit risk in the event of default by the financial institutions holding our cash and cash equivalents and issuers of investments that are recorded on our consolidated balance sheets. We mitigate our risk by investing in high-grade instruments and limiting the concentration in any one issuer, which limits our exposure.
Property and Equipment	Property and Equipment Property and equipment are stated at cost, less accumulated depreciation. Expenditures for major additions and betterments are capitalized. Maintenance and repairs are charged to operations as incurred. Depreciation and amortization are calculated using the straight-line method over the estimated useful lives of the assets, which range from three to seven years. Leasehold improvements are amortized using the straight-line method over the term of the lease. Upon sale or retirement of property and equipment, the related cost and accumulated depreciation are removed from the accounts and any gain or loss is reflected in operations.
Long Lived Assets	Long Lived Assets Long-lived assets, consisting of property and equipment, are reviewed for impairment whenever events or changes in circumstances indicate that the carrying value of an asset may not be recoverable based on undiscounted cash flows. If long-lived assets are impaired, an impairment loss is recognized and is measured as the amount by which the carrying value exceeds the estimated fair value of the assets.
Leases	Leases Our leases consist of a lease for office and lab space that is classified as an operating lease. We determine if an arrangement is a lease at inception. Rent expense is recognized on a straight-line basis. When an operating lease includes rent abatements or requires fixed escalations of the minimum lease payments, the aggregate rental expense is recognized on a straight-line basis over the term of the lease. When an operating lease includes lease incentives such as leasehold improvement allowances, the lease incentive is included in ROU asset. For leases that have greater than a 12-month lease term, the ROU assets and lease liabilities are recognized based on the present value of the future minimum lease payments over the lease term. For this purpose, we consider only payments that are fixed and determinable at the time of commencement. As our lease does not provide an implicit rate, we use our incremental borrowing rate based on the information available at commencement date in determining the present value of future payments. We account for fixed lease components separately from non-lease components. We elected the practical expedient to not record leases with an initial term of 12 months or less on the balance sheet and recognize the associated lease payments in the consolidated statements of operations on a straight-line basis over the lease term.
Liability Related to the Sale of Future Royalties	Liability Related to the Sale of Future Royalties We treat the liability related to the sale of future royalties as debt, amortized under the effective interest rate method over the estimated life of the Jemperli Royalty Monetization Agreement and the Zejula Royalty Monetization Agreement. See Note 5. The amortization of the liability related to the sale of future revenue is based on our current estimates of future royalty payments. Royalty and milestone revenue will be recognized as earned and the payments made will be recorded as a reduction of the liability when paid.
Debt Issuance Costs	Debt Issuance Costs Debt issuance costs related to a recognized debt liability are deferred and amortized over the term of the debt using the effective interest method. These costs are recorded as a direct reduction to the carrying value of the debt on the balance sheet and the amortization expense is included in non-cash interest expense in the statement of operations.
Non-Cash Interest Expense on the Liability Related to the Sale of Future Royalties	Non-Cash Interest Expense on the Liability Related to the Sale of Future Royalties The total threshold of royalties to be paid, less the net proceeds received will be recorded as non-cash interest expense over the life of the liability. We impute interest on the unamortized portion of the liability using the effective interest method and record expense based on the timing of payments received over the term of the Jemperli Royalty Monetization Agreement and the Zejula Royalty Monetization Agreement. Over the course of the agreement, the actual interest rate will be affected by the timing of royalty and milestone payments made and changes in the forecasted revenue.
Revenue Recognition	Revenue Recognition Revenue is recognized in accordance with revenue recognition accounting guidance, which utilizes five basic steps to determine whether revenue can be recognized and to what extent: (i) identify the contract with a customer; (ii) identify the performance obligation; (iii) determine the transaction price; (iv) allocate the transaction price; and (v) determine the recognition period. Performance Obligations. We evaluate deliverables on a contract-by-contract basis to determine whether each deliverable represents a good or service that is distinct or has the same pattern of transfer as other deliverables. A deliverable is considered distinct if the customer can benefit from the good or service independently of other goods/services either in the contract or that can be obtained elsewhere, without regard to contract exclusivity, and the entity’s promise to transfer the good or service to the customer is separately identifiable from other promises in the contact. If the deliverable is not considered distinct, we combine such deliverables and account for them as a single performance obligation. We allocate the consideration to each deliverable at the inception of the arrangement based on the transaction price. Our performance obligations may include the following: •License Arrangements. The performance obligations under our collaboration and license agreements generally include exclusive or nonexclusive licenses to one or more products generated using our technologies. Licenses for multiple antibodies within a single contract are generally combined as they have substantially the same pattern of transfer to the customer. Historically, our licenses have held no value to the customer, as the antibodies were in the discovery phase and required our expertise for further development. Accordingly, licenses are not considered distinct. •Research and Development Services. The performance obligations under our collaboration and license agreements generally include research and development services we perform on behalf of or with our collaborators. As discussed within license arrangements above, our licenses have historically held no value without the research and development services we provide. As we generally only provide research and development services for internally generated antibodies that require a license to be utilized by a third party, our research and development services are not considered distinct. •Steering Committee Meetings. The performance obligations under our collaboration and license agreements may also include our participation on steering committees, which allows us to direct the progression of our discovery programs. As these steering committees would not occur or benefit the customer without the use of our licenses, these are not considered distinct. We recognize consideration allocated to a performance obligation as the performance obligation is satisfied, and the determination as to whether consideration is recognized over time or at a point in time is made upon contract inception. For our collaboration agreements, this is generally over the period in which research and development services have been performed. There were no new agreements with performance obligations entered into during the year ended December 31, 2023. Transaction Price. Our collaboration and license agreements generally include both fixed and variable consideration. Fixed payments, such as those for upfront fees are included in the transaction price at contract value, while variable consideration such as reimbursement for research and development services, milestone and royalty payments are estimated and then evaluated for constraints upon inception of the contract and evaluated on a quarterly basis thereafter. Research and development services are updated for actual invoices. Given the nature of our agreements, milestones are estimated using the most likely amount and are evaluated on a quarterly basis. Upon commercialization, royalty payments will be recognized in the period incurred. Royalty Revenue We receive royalty revenue on sales by our partners of products covered by patents or contract rights that we own and net sales of their approved drugs, where we have concluded the license is the predominant item to which the royalties relate. We do not have future performance obligations under these license arrangements. We generally satisfy our obligation to grant intellectual property rights on the effective date of the contract. However, we apply the royalty recognition constraint required under the guidance for sales-based royalties, which requires a sales-based royalty to be recorded when the underlying sale occurs. Therefore, royalties on sales of products commercialized by our partners are recognized in the quarter the product is sold. Our partners generally report sales information to us on a quarter lag. Thus, we estimate the expected royalty proceeds based on an analysis of our partners’ historical experience including their publicly announced sales. Differences between actual and estimated royalty revenues are adjusted for in the period in which they become known, typically the following quarter. As of December 31, 2023, there have not been material differences between actual and estimated royalty revenues.
Research and Development Expenses	Research and Development Expenses Research and development costs primarily include third-party clinical and preclinical research and development services such as manufacturing, laboratory and related supplies, salaries and personnel-related costs, in-licensing fees, outside services, and an allocation of information technology, and facility overhead costs. Costs associated with research and development activities are expensed as incurred. We account for nonrefundable advance payments for goods and services that will be used in future research and development activities as expense when the service has been performed or when the goods have been received. We estimate research and development costs incurred during the period, which impacts the amount of accrued expenses and prepaid balances related to such costs as of each balance sheet date. This process involves reviewing open contracts and purchase orders, communicating with our personnel and service providers to identify services that have been performed on our behalf and estimating the level of service performed and the associated cost incurred for the service when we have not yet been invoiced or otherwise notified of the actual cost. The majority of our service providers invoice us monthly in arrears for services performed or when contractual milestones are met. We make estimates of our accrued expenses as of each balance sheet date based on facts and circumstances known to us at that time. We periodically confirm the accuracy of our estimates with the service providers and make adjustments if necessary. The significant estimates in our accrued research and development expenses include the costs incurred for services performed by our vendors in connection with research and development activities for which we have not yet been invoiced. Upfront and milestone payments incurred under our in-licensing agreements are expensed as acquired in-process research and development in the period in which they are incurred, provided that the technology or method has no alternative future use. Acquired In-process Research and Development Acquired in-process research and development costs consist of upfront payments incurred in connection with the acquisition of licensing of products or technologies that do not meet the definition of a business under the Accounting Standards of Codification Topic 805, Business Combinations.
Stock-Based Compensation	Stock-Based Compensation We recognize stock-based compensation expense using a fair-value-based method for costs related to all share-based payments, including stock options. Stock-based compensation cost for stock options granted to our employees and directors is measured at the grant date based on the fair-value of the award which is estimated using the Black-Scholes option-pricing model, and is recognized as expense over the requisite service period on a straight-line basis. We recognize forfeitures in the period in which forfeitures occur and record stock-based compensation expense as though all awards are expected to vest. We record the expense for stock-based compensation awards subject to performance-based milestone vesting over the requisite service period when management determines that achievement of the milestone is probable. Management evaluates when the achievement of a performance-based milestone is probable based on the expected satisfaction of the performance conditions at each reporting date. Each Restricted Stock Unit (“RSU”) represents one equivalent share of our common stock to be issued after satisfying the applicable continued service-based vesting criteria over a specified period. The fair value of these RSUs is based on the closing price of our common stock on the date of the grant. We measure compensation expense over the expected vesting period on a straight-line basis. No tax benefits for stock-based compensation have been recognized in the statements of changes in stockholders’ equity or cash flows. We have not recognized, and do not expect to recognize in the near future, any tax benefit related to stock-based compensation cost as a result of our full valuation allowance on net deferred tax assets and net operating loss carryforwards.
Income Taxes	Income Taxes We account for income taxes under the asset and liability method. Under this method, deferred tax assets and liabilities are determined based on differences between financial reporting and tax basis of assets and liabilities and are measured using enacted tax rates and laws that are expected to be in effect when the differences are expected to be recovered or settled. Realization of deferred tax assets is dependent upon future taxable income. A valuation allowance is recognized if it is more likely than not that some portion or all of a deferred tax asset will not be realized based on the weight of available evidence, including expected future earnings. We recognize an uncertain tax position in our consolidated financial statements when we conclude that a tax position is more likely than not to be sustained upon examination based solely on technical merits. Only after a tax position passes the first step of recognition will measurement be required. Under the measurement step, the tax benefit is measured as the largest amount of benefit that is more likely than not to be realized upon effective settlement. This is determined on a cumulative probability basis. The full impact of any change in recognition or measurement is reflected in the period in which such change occurs. We have elected to accrue any interest or penalties related to income taxes as part of our income tax expense.
Foreign Currency of Foreign Operations	Functional Currency of Foreign Operations Our Australian subsidiary operates in a U.S. dollar functional currency environment. Assets and liabilities of our foreign subsidiary that are not denominated in the functional currency are remeasured into U.S. dollars at foreign currency exchange rates in effect at the balance sheet date except for nonmonetary assets and capital accounts, which are remeasured at historical foreign currency exchange rates in effect at the date of transaction. Expenses are generally remeasured at monthly foreign currency exchange rates which approximate average rates in effect during each period. Net realized and unrealized gains and losses from foreign currency transactions and remeasurement are reported in other income (expense), net, in the consolidated statements of operations.
Comprehensive Income (Loss)	Comprehensive Income (Loss) Comprehensive income (loss) represents all changes in stockholders’ equity except those resulting from distributions to stockholders. Our unrealized gain and losses on available for sale investments represent the only component of other comprehensive income (loss) that is excluded from the reported net income (loss).
Net Loss Per Common Share	Net Loss Per Common Share Basic net loss per common share is computed by dividing net loss by the weighted-average number of common shares outstanding during the period. Diluted net loss per share is computed by dividing net loss by the weighted-average number of common equivalent shares outstanding for the period, as well as any dilutive effect from outstanding stock options and warrants using the treasury stock method. For each period presented, there is no difference in the number of shares used to calculate basic and diluted net loss per share.
Accounting Pronouncements and Recent Accounting Pronouncements Not Yet Adopted	Accounting Pronouncements We have implemented all new accounting pronouncements that are in effect and may have an impact on our consolidated financial statements. Unless otherwise discussed, we believe the impact of any recently issued pronouncements, not yet effective will not have a material impact on our consolidated financial statements. Recent Accounting Pronouncements Not Yet Adopted In November 2023, the Financial Accounting Standards Board (FASB) issued Accounting Standard Update (ASU) 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures, which requires enhanced disclosure of significant segment expenses on an annual and interim basis. The guidance will be effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning December 15, 2024, with early adoption permitted. Upon adoption, the guidance should be applied retrospectively to all prior periods presented in the financial statements. We are currently assessing the impact that this standard will have on our consolidated financial statements. In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures Income Taxes, which improves the transparency of income tax disclosures by requiring consistent categories and greater disaggregation of information in the effective tax rate reconciliation and income taxes paid disaggregated by jurisdiction. It also includes certain other amendments to improve the effectiveness of income tax disclosures. This guidance will be effective for the annual periods beginning after December 15, 2024. Early adoption is permitted. Upon adoption, the guidance can be applied prospectively or retrospectively. We are currently assessing the impact that this standard will have on our consolidated financial statements.

Balance Sheet Accounts and Supplemental Disclosures

12 Months Ended

Dec. 31, 2023

Balance Sheet Related Disclosures [Abstract]

Balance Sheet Accounts and Supplemental Disclosures

Property and Equipment

Property and equipment consist of the following:


(in thousands)	December 31, 2023		December 31, 2022
Laboratory equipment	$	6,473	$	5,869
Office furniture and equipment	1,640		1,593
Leasehold improvements	203		203
Property and equipment, gross	8,316		7,665
Less: accumulated depreciation and amortization	(6,218)		(5,576)
Total property and equipment, net	$	2,098	$	2,089

Accrued Expenses

Accrued expenses consist of the following:


(in thousands)	December 31, 2023		December 31, 2022
Accrued compensation and related expenses	$	7,201	$	5,379
Accrued professional fees	1,168		607
Accrued research, development and manufacturing expenses	21,898		15,351
Accrued for repurchase of common stock	456		—
Other	244		296
Total accrued expenses	$	30,967	$	21,633

Pay vs Performance Disclosure - USD ($) $ in Thousands	12 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pay vs Performance Disclosure
Net Income (Loss)	$ (163,619)	$ (128,724)	$ (57,796)

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
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-Name Accounting Standards Codification
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
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Reference 13: http://www.xbrl.org/2003/role/exampleRef
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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Reference 15: http://www.xbrl.org/2003/role/disclosureRef
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Reference 16: http://www.xbrl.org/2003/role/disclosureRef
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Reference 17: http://www.xbrl.org/2003/role/disclosureRef
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Reference 18: http://www.xbrl.org/2003/role/disclosureRef
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Reference 20: http://www.xbrl.org/2009/role/commonPracticeRef
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+ Details

Collaborative Research and Development Agreements (Tables)

12 Months Ended

Dec. 31, 2023

Revenue from Contract with Customer [Abstract]

Schedule of Milestones Achieved

Milestones under the GSK Agreement are as follows:

Anti-PD-1

(Jemperli/Dostarlimab)

Anti-TIM-3
(GSK4069889A/Cobolimab)

Milestone Event

Amount

Quarter Recognized

Amount

Quarter Recognized

Initiated in vivo toxicology studies using good laboratory practices (GLPs)

$1.0M

Q2'15

$1.0M

Q4'15

IND clearance from the FDA

$4.0M

Q1'16

$4.0M

Q2'16

Phase 2 clinical trial initiation

$3.0M

Q2'17

$3.0M

Q4'17

Phase 3 clinical trial initiation - first indication

$5.0M

Q3'18

$5.0M

Q4'22

Phase 3 clinical trial initiation - second indication

$5.0M

Q2'19

$5.0M

—

Filing of the first BLA(1) - first indication

$10.0M

Q1'20

$10.0M

—

Filing of the first MAA(2) - first indication

$5.0M

Q1'20

$5.0M

—

Filing of the first BLA - second indication

$10.0M

Q1'21

$10.0M

—

First BLA approval - first indication

$20.0M

Q2'21

$20.0M

—

First MAA approval - first indication

$10.0M

Q2'21

$10.0M

—

First BLA approval - second indication

$20.0M

Q3'21

$20.0M

—

Filing of the first MAA - second indication(3)

$5.0M

—

$5.0M

—

First MAA approval - second indication(3)

$10.0M

—

$10.0M

—

First commercial sales milestone(3)

$15.0M

—

$15.0M

—

Second commercial sales milestone(3)

$25.0M

—

$25.0M

—

Third commercial sales milestone(3)

$50.0M

—

$50.0M

—

Fourth commercial sales milestone

$75.0M

—

$75.0M

—

Milestones recognized through December 31, 2023

$93.0M

—

$13.0M

—

Milestones that may be recognized in the future

$180.0M

—

$260.0M

—

(1)Biologics License Application (“BLA”)

(2)Marketing Authorization Application (“MAA”)

Equity Incentive Plans - Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Shares Subject to Options
Beginning balance (in shares)	3,673,208
Granted (in shares)	1,579,331
Exercises (in shares)	(90,883)
Forfeitures and cancellations (in shares)	(936,041)
Ending balance (in shares)	4,225,615	3,673,208
Stock options exercisable, ending balance (in shares)	2,154,408
Weighted-Average Exercise Price per Share
Beginning balance (in dollars per share)	$ 32.04
Granted (in dollars per share)	22.02
Exercises (in dollars per share)	18.95
Forfeitures and cancellations (in dollars per share)	37.52
Ending balance (in dollars per share)	27.36	$ 32.04
Stock options exercisable, ending balance (in dollars per share)	$ 30.60
Weighted-Average Remaining Contractual Term and Aggregate Intrinsic Value
Weighted average remaining contractual term, options outstanding	7 years 5 months 1 day	6 years 3 months 10 days
Weighted average remaining contractual term, options exercisable	6 years 1 month 6 days
Aggregate intrinsic value, options outstanding	$ 5,827	$ 18,686
Aggregate intrinsic value, options exercisable	$ 4,741

Employee Benefit Plan	12 Months Ended
Employee Benefit Plan	Dec. 31, 2023
Retirement Benefits [Abstract]
Employee Benefit Plan	Employee Benefit Plan We have a defined contribution 401(k) plan available to eligible employees. Employee contributions are voluntary and are determined on an individual basis, limited to the maximum amount allowable under U.S. federal tax regulations. We elected to match 100% of an employee’s contributions up to 10% of the employees’ eligible salary with a maximum limit of $22,500 in 2023, 100% of an employee’s contribution up to 6% of the employees’ salary with a maximum limit of $11,000 in 2022, and $8,000 in 2021. For the years ended December 31, 2023, 2022, and 2021, we incurred approximately $1.6 million, $1.0 million, and $0.6 million, respectively of costs related to the 401(k) plan.

- Definition

The entire disclosure for retirement benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 70
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
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-URI https://asc.fasb.org//1943274/2147480794/715-70-50-1

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+ Details

Income Taxes - Reconciliation of income taxes (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Expected income tax benefit at federal statutory tax rate	$ (34,361,000)	$ (27,026,000)	$ (12,138,000)
State income taxes, net of federal benefit	(1,912,000)	(800,000)	(142,000)
Permanent items	56,000	27,000	17,000
Equity compensation	2,840,000	(297,000)	(708,000)
Non-deductible compensation	3,693,000	2,060,000	0
Research credits	(6,213,000)	(3,319,000)	8,087,000
Other	109,000	(6,000)	42,000
Change in the valuation allowance	35,784,000	29,385,000	4,842,000
Income tax (benefit) expense	$ (4,000)	$ 24,000	$ 0

Collaborative Research and Development Agreements - Schedule of Milestone Achieved (Details) - USD ($) $ in Thousands	3 Months Ended													12 Months Ended
	Dec. 31, 2022	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Mar. 31, 2020	Jun. 30, 2019	Sep. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Jun. 30, 2015	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration revenue														$ 17,157	$ 10,287	$ 63,175
Milestone revenue recognition														Cash is generally received within 30 days of milestone achievement.
GSK
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration revenue														$ 17,200	10,300	$ 63,200
GSK \| Anti-PD-1 (Jemperli/Dostarlimab) \| Initiated in vivo toxicology studies using good laboratory practices (GLPs)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration revenue													$ 1,000
GSK \| Anti-PD-1 (Jemperli/Dostarlimab) \| IND clearance from the FDA
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration revenue											$ 4,000
GSK \| Anti-PD-1 (Jemperli/Dostarlimab) \| Phase 2 clinical trial initiation
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration revenue									$ 3,000
GSK \| Anti-PD-1 (Jemperli/Dostarlimab) \| Phase 3 clinical trial initiation - first indication
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration revenue							$ 5,000
GSK \| Anti-PD-1 (Jemperli/Dostarlimab) \| Phase 3 clinical trial initiation - second indication
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration revenue						$ 5,000
GSK \| Anti-PD-1 (Jemperli/Dostarlimab) \| Filing of the first BLA - first indication
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration revenue					$ 10,000
GSK \| Anti-PD-1 (Jemperli/Dostarlimab) \| Filing of the first MAA - first indication
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration revenue					$ 5,000
GSK \| Anti-PD-1 (Jemperli/Dostarlimab) \| Filing of the first BLA - second indication
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration revenue				$ 10,000
GSK \| Anti-PD-1 (Jemperli/Dostarlimab) \| First BLA approval - first indication
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration revenue			$ 20,000
GSK \| Anti-PD-1 (Jemperli/Dostarlimab) \| First MAA approval - first indication
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration revenue			$ 10,000
GSK \| Anti-PD-1 (Jemperli/Dostarlimab) \| First BLA approval - second indication
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration revenue		$ 20,000
GSK \| Anti-PD-1 (Jemperli/Dostarlimab) \| Filing of the first MAA - second indication
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestones that may be recognized in the future														5,000
GSK \| Anti-PD-1 (Jemperli/Dostarlimab) \| First MAA approval - second indication
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestones that may be recognized in the future														10,000
GSK \| Anti-PD-1 (Jemperli/Dostarlimab) \| First commercial sales milestone
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestones that may be recognized in the future														15,000
GSK \| Anti-PD-1 (Jemperli/Dostarlimab) \| Second commercial sales milestone
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestones that may be recognized in the future														25,000
GSK \| Anti-PD-1 (Jemperli/Dostarlimab) \| Third commercial sales milestone
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestones that may be recognized in the future														50,000
GSK \| Anti-PD-1 (Jemperli/Dostarlimab) \| Fourth commercial sales milestone
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestones that may be recognized in the future														75,000
GSK \| Anti-PD-1 (Jemperli/Dostarlimab) \| Milestones recognized through December 31, 2023
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration revenue														93,000
GSK \| Anti-PD-1 (Jemperli/Dostarlimab) \| Milestones that may be recognized in the future
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestones that may be recognized in the future														180,000
GSK \| Anti-TIM-3 (GSK4069889A/Cobolimab) \| Initiated in vivo toxicology studies using good laboratory practices (GLPs)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration revenue												$ 1,000
GSK \| Anti-TIM-3 (GSK4069889A/Cobolimab) \| IND clearance from the FDA
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration revenue										$ 4,000
GSK \| Anti-TIM-3 (GSK4069889A/Cobolimab) \| Phase 2 clinical trial initiation
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration revenue								$ 3,000
GSK \| Anti-TIM-3 (GSK4069889A/Cobolimab) \| Phase 3 clinical trial initiation - first indication
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration revenue	$ 5,000														$ 5,000
GSK \| Anti-TIM-3 (GSK4069889A/Cobolimab) \| Phase 3 clinical trial initiation - second indication
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestones that may be recognized in the future														5,000
GSK \| Anti-TIM-3 (GSK4069889A/Cobolimab) \| Filing of the first BLA - first indication
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestones that may be recognized in the future														10,000
GSK \| Anti-TIM-3 (GSK4069889A/Cobolimab) \| Filing of the first MAA - first indication
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestones that may be recognized in the future														5,000
GSK \| Anti-TIM-3 (GSK4069889A/Cobolimab) \| Filing of the first BLA - second indication
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestones that may be recognized in the future														10,000
GSK \| Anti-TIM-3 (GSK4069889A/Cobolimab) \| First BLA approval - first indication
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestones that may be recognized in the future														20,000
GSK \| Anti-TIM-3 (GSK4069889A/Cobolimab) \| First MAA approval - first indication
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestones that may be recognized in the future														10,000
GSK \| Anti-TIM-3 (GSK4069889A/Cobolimab) \| First BLA approval - second indication
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestones that may be recognized in the future														20,000
GSK \| Anti-TIM-3 (GSK4069889A/Cobolimab) \| Filing of the first MAA - second indication
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestones that may be recognized in the future														5,000
GSK \| Anti-TIM-3 (GSK4069889A/Cobolimab) \| First MAA approval - second indication
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestones that may be recognized in the future														10,000
GSK \| Anti-TIM-3 (GSK4069889A/Cobolimab) \| First commercial sales milestone
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestones that may be recognized in the future														15,000
GSK \| Anti-TIM-3 (GSK4069889A/Cobolimab) \| Second commercial sales milestone
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestones that may be recognized in the future														25,000
GSK \| Anti-TIM-3 (GSK4069889A/Cobolimab) \| Third commercial sales milestone
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestones that may be recognized in the future														50,000
GSK \| Anti-TIM-3 (GSK4069889A/Cobolimab) \| Fourth commercial sales milestone
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestones that may be recognized in the future														75,000
GSK \| Anti-TIM-3 (GSK4069889A/Cobolimab) \| Milestones recognized through December 31, 2023
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration revenue														13,000
GSK \| Anti-TIM-3 (GSK4069889A/Cobolimab) \| Milestones that may be recognized in the future
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestones that may be recognized in the future														$ 260,000

Income Taxes - Narrative (Details) - USD ($)	12 Months Ended
Income Taxes - Narrative (Details) - USD ($)	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2014
Operating Loss Carryforwards [Line Items]
Income tax (benefit) expense	$ (4,000)	$ 24,000	$ 0
Research and development credits	19,058,000	12,844,000		$ 200,000
Unrecognized tax benefits that if recognized and realized would affect the effective tax rate	0	0
Interest or penalties on uncertain tax benefits	0	0
Federal tax authority
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	313,800,000
Domestic				5,300,000
Research and development credits		$ 15,000,000
Federal tax authority \| 2018 and after
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	261,700,000
Federal tax authority \| Research tax credit carryforwards
Operating Loss Carryforwards [Line Items]
Research tax credit carryforwards	12,100,000
State tax authority
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	73,300,000
State and local				$ 5,400,000
State tax authority \| Research tax credit carryforwards
Operating Loss Carryforwards [Line Items]
Research tax credit carryforwards	14,400,000
Foreign tax authority
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$ 3,200,000

Balance Sheet Accounts and Supplemental Disclosures (Tables)

12 Months Ended

Dec. 31, 2023

Balance Sheet Related Disclosures [Abstract]

Schedule of Property and Equipment

Property and equipment consist of the following:


(in thousands)	December 31, 2023		December 31, 2022
Laboratory equipment	$	6,473	$	5,869
Office furniture and equipment	1,640		1,593
Leasehold improvements	203		203
Property and equipment, gross	8,316		7,665
Less: accumulated depreciation and amortization	(6,218)		(5,576)
Total property and equipment, net	$	2,098	$	2,089

Schedule of Accrued Expenses

Accrued expenses consist of the following:


(in thousands)	December 31, 2023		December 31, 2022
Accrued compensation and related expenses	$	7,201	$	5,379
Accrued professional fees	1,168		607
Accrued research, development and manufacturing expenses	21,898		15,351
Accrued for repurchase of common stock	456		—
Other	244		296
Total accrued expenses	$	30,967	$	21,633

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 35,965	$ 71,308
Receivables from collaborative partners	6,851	1,419
Short-term investments	354,939	369,933
Prepaid expenses and other current assets	9,080	4,545
Total current assets	406,835	447,205
Property and equipment, net	2,098	2,089
Operating lease right-of-use assets	16,174	17,898
Long-term investments	27,026	142,935
Other long-term assets	256	256
Total assets	452,389	610,383
Current liabilities:
Accounts payable	4,698	2,784
Accrued expenses	30,967	21,633
Current portion of operating lease liability	1,777	1,637
Total current liabilities	37,442	26,054
Liability related to sale of future royalties	310,807	304,413
Operating lease liability, net of current portion	16,037	17,813
Stockholders’ equity:
Preferred stock, $0.001 par value, 10,000 shares authorized and no shares, issued or outstanding at December 31, 2023 and December 31, 2022, respectively	0	0
Common stock, $0.001 par value, 500,000 shares authorized, 26,597 shares and 28,513 shares issued and outstanding at December 31, 2023 and December 31, 2022, respectively	27	29
Additional paid in capital	702,969	717,797
Accumulated other comprehensive loss	(797)	(5,246)
Accumulated deficit	(614,096)	(450,477)
Total stockholders’ equity	88,103	262,103
Total liabilities and stockholders’ equity	$ 452,389	$ 610,383

Cover page - USD ($)	12 Months Ended
Cover page - USD ($)	Dec. 31, 2023	Mar. 05, 2024	Jun. 30, 2023
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2023
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-37985
Entity Registrant Name	ANAPTYSBIO, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-3828755
Entity Address, Address Line One	10770 Wateridge Circle
Entity Address, Address Line Two	Suite 210
Entity Address, City or Town	San Diego
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92121
City Area Code	858
Local Phone Number	362-6295
Title of 12(b) Security	Common Stock, $0.001 par value
Trading Symbol	ANAB
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	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	false
Document Financial Statement Error Correction	false
Entity Shell Company	false
Entity Public Float			$ 366,560,992
Entity Common Stock, Shares Outstanding		26,763,081
Documents Incorporated by Reference	Portions of the registrant’s Definitive Proxy Statement relating to the 2024 Annual Meeting of Stockholders, scheduled to be held on June 12, 2024, are incorporated by reference into Part III of this Annual Report on Form 10-K to the extent stated herein. The Definitive Proxy Statement will be filed within 120 days of the Registrant’s fiscal year ended December 31, 2023. Except with respect to information specifically incorporated by reference in this Form 10-K, the Proxy Statement is not deemed to be filed as part of this Form 10-K.
Entity Central Index Key	0001370053
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Amendment Flag	false

Sale of Future Royalties - Schedule of Royalty Transaction Activity (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Oct. 31, 2021	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Liabilities Related To Sale Of Future Royalties [Roll Forward]
Royalty payments to DRI		$ (11,726)	$ (2,474)	$ 0
JEMPERLI Royalty Monetization Agreement
Liabilities Related To Sale Of Future Royalties [Roll Forward]
Beginning balance		269,540
Issuance costs related to the sale of future royalties	$ 400	37
Amortization of issuance costs		39
Royalty payments to DRI		(8,600)
Non-cash interest expense recognized		17,074
Ending balance		278,090	269,540
Zejula Royalty Monetization Agreement
Liabilities Related To Sale Of Future Royalties [Roll Forward]
Beginning balance		34,873
Amortization of issuance costs		28
Royalty payments to DRI		(3,126)
Non-cash interest expense recognized		942
Ending balance		$ 32,717	$ 34,873

Fair Value Measurements and Available for Sale Investments

12 Months Ended

Dec. 31, 2023

Fair Value Disclosures [Abstract]

Fair Value Measurements and Available for Sale Investments

Fair Value Measurements

Our financial instruments consist principally of cash, cash equivalents, short-term and long-term investments, receivables, and accounts payable. Certain of our financial assets and liabilities have been recorded at fair value in the consolidated balance sheet in accordance with the accounting standards for fair value measurements.

Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants on the measurement date. Accounting guidance also establishes a fair value hierarchy that requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. The standard describes three levels of inputs that may be used to measure fair value:

Level 1 - Observable inputs that reflect quoted prices (unadjusted) for identical assets or liabilities in active markets.

Level 2 - Inputs are observable, unadjusted quoted prices in active markets for similar assets or liabilities, unadjusted 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 related assets or liabilities; and

Level 3 - Unobservable inputs that are supported by little or no market activities, therefore requiring an entity to develop its own assumptions.

Assets and Liabilities Measured at Fair Value on a Recurring Basis

The following table summarizes our assets and liabilities that require fair value measurements on a recurring basis and their respective input levels based on the fair value hierarchy:


	Fair Value Measurements at End of Period Using:
(in thousands)	Fair Value		Quoted Market Prices for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
At December 31, 2023
Money market funds(1)	$	27,789	$	27,789	$	—	$	—
Mutual funds(1)	6,286		6,286		—		—
U.S. Treasury securities(2)	325,714		325,714		—		—
Certificates of deposit(2)	244		—		244		—
Agency securities(2)	20,253		—		20,253		—
Commercial and corporate obligations(2)	35,754		—		35,754		—

At December 31, 2022
Money market funds(1)	$	29,702	$	29,702	$	—	$	—
Mutual funds(1)	41,812		41,812		—		—
U.S. Treasury securities(2)	374,527		374,527		—		—
Certificates of deposit(2)	2,856		—		2,856		—
Agency securities(2)	74,602		—		74,602		—
Commercial and corporate obligations(2)	60,883		—		60,883		—

(1) Included in cash and cash equivalents in the accompanying consolidated balance sheets.

(2) Included in short-term or long-term investments in the accompanying consolidated balance sheets depending on the respective maturity date.

The following methods and assumptions were used to estimate the fair value of our financial instruments for which it is practicable to estimate that value:

Marketable Securities. For fair values determined by Level 1 inputs, which utilize quoted prices in active markets for identical assets, the level of judgment required to estimate fair value is relatively low. For fair values determined by Level 2 inputs, which utilize quoted prices in less active markets for similar assets, the level of judgment required to estimate fair value is also considered relatively low.

Fair Value of Other Financial Instruments

The carrying amounts of certain of our financial instruments, including cash and cash equivalents, accounts payable, and accrued expenses approximate fair value due to their short-term nature.

Available for Sale Investments

We invest our excess cash in agency securities, debt instruments of financial institutions and corporations, commercial obligations, and U.S. Treasury securities, which we classify as available-for-sale investments. These investments are carried at fair value and are included in the tables above. The aggregate market value, cost basis, and gross unrealized gains and losses of available-for-sale investments by security type, classified in cash equivalents, short-term and long-term investments as of December 31, 2023 are as follows:


(in thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Total Fair Value
Agency securities(1)	$	20,322	$	—	$	(69)	$	20,253
Certificates of deposit(2)	246		—		(2)		244
Commercial and corporate obligations(3)	35,760		77		(83)		35,754
US Treasury securities(4)	326,227		122		(635)		325,714
Total available-for-sale investments	$	382,555	$	199	$	(789)	$	381,965

(1) Of our outstanding agency securities, $20.3 million have maturity dates of less than one year and $0.0 million have a maturity date of between one to two years as of December 31, 2023.

(2) Of our outstanding certificates of deposit, $0.2 million have a maturity date of less than one year and $0.0 million have a maturity date of between one to two years as of December 31, 2023.

(4) Of our outstanding U.S. Treasury securities, $308.6 million have maturity dates of less than one year and $17.1 million have a maturity date of between one to two years as of December 31, 2023.


(in thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Total Fair Value
Agency securities(1)	$	75,504	$	11	$	(913)	$	74,602
Certificates of deposit(2)	2,915		—		(59)		2,856
Commercial and corporate obligations(3)	61,791		8		(916)		60,883
US Treasury securities(4)	377,697		19		(3,189)		374,527
Total available-for-sale investments	$	517,907	$	38	$	(5,077)	$	512,868

(1) Of our outstanding agency securities, $57.1 million have maturity dates of less than one year and $17.5 million have a maturity date of between one to two years as of December 31, 2022.

(2) Of our outstanding certificates of deposit, $2.6 million have a maturity date of less than one year and $0.3 million have a maturity date of between one to two years as of December 31, 2022.

(4) Of our outstanding U.S. Treasury securities, $266.2 million have maturity dates of less than one year and $108.3 million have a maturity date of between one to two years as of December 31, 2022.


	December 31, 2023
	Less than 12 Months				12 Months or Greater				Total
(in thousands)	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
Agency securities	$	2,530	$	(1)	$	17,723	$	(68)	$	20,253	$	(69)
Certificates of Deposit	—		—		244		(2)		244		(2)
Commercial and corporate obligations	5,160		(9)		15,200		(74)		20,360		(83)
US Treasury Securities	98,840		(110)		99,000		(525)		197,840		(635)
Total	$	106,530	$	(120)	$	132,167	$	(669)	$	238,697	$	(789)


	December 31, 2022
	Less than 12 Months				12 Months or Greater				Total
(in thousands)	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
Agency securities	$	61,117	$	(843)	$	3,437	$	(70)	$	64,554	$	(913)
Certificates of Deposit	481		(10)		2,375		(49)		2,856		(59)
Commercial and corporate obligations	44,213		(624)		14,778		(292)		58,991		(916)
US Treasury Securities	298,575		(2,667)		41,937		(522)		340,513		(3,189)
Total	$	404,386	$	(4,144)	$	62,527	$	(933)	$	466,914	$	(5,077)

As of December 31, 2023 and 2022, unrealized losses on available-for-sale investments were $0.8 million and $5.1 million, respectively, with unrealized losses of $0.7 million, on available for sale investments that were in an unrealized loss position for greater than 12 months as of December 31, 2023. We do not intend to sell the investments and it is not more likely than not that we will be required to sell the investments before recovery of their amortized cost basis, accordingly, no allowance for credit losses was recorded.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Commitments and Contingencies - Schedule of Future Minimum Annual Obligations under Operating Leases (Details) $ in Thousands	Dec. 31, 2023 USD ($)
Commitments and Contingencies Disclosure [Abstract]
2024	$ 2,457
2025	2,531
2026	2,607
2027	2,685
2028	2,766
Thereafter	7,788
Total minimum payments required	20,834
Less: imputed interest	(3,020)
Total	$ 17,814

Equity Incentive Plans (Tables)

12 Months Ended

Dec. 31, 2023

Share-Based Payment Arrangement [Abstract]

Schedule of Activity Related to Stock Option Awards

A summary of the activity related to stock option awards during the year ended December 31, 2023 is as follows:


	Shares Subject to Options	Weighted-Average Exercise Price per Share		Weighted-Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value (in thousands)
Outstanding at January 1, 2023	3,673,208	$	32.04	6.28	$	18,686
Granted	1,579,331	$	22.02
Exercises	(90,883)	$	18.95
Forfeitures and cancellations	(936,041)	$	37.52
Outstanding at December 31, 2023	4,225,615	$	27.36	7.42	$	5,827
Exercisable at December 31, 2023	2,154,408	$	30.60	6.10	$	4,741

Schedule of Time-based Restricted Stock Units Activity


	Number of Restricted Stock Units	Weighted-Average Grant Date Fair Value		Weighted-Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value (in thousands)
Outstanding at January 1, 2023	1,028,843	$	26.14	1.17	$	31,884
Granted	568,574	$	22.02
Released	(68,900)	$	23.89
Forfeitures and cancellations	(46,945)	$	21.87
Outstanding at December 31, 2023	1,481,572	$	24.80	0.73	$	31,735
RSU expected to vest at December 31, 2023	1,481,572	$	24.80	0.73	$	31,735

Schedule of Weighted Average Assumptions in Stock Option Valuations

The

estimated fair values of stock option awards granted were determined on the date of grant using the Black-Scholes option valuation model with the following weighted-average assumptions:


		Year Ended December 31,

		2023			2022			2021
Risk-free interest rate		3.8	%		2.5	%		0.7	%
Expected volatility		85.7	%		87.4	%		92.9	%
Expected dividend yield		—	%		—	%		—	%
Expected term (in years)		5.82			6.09			6.18
Weighted average grant date fair value per share	$	16.06		$	21.58		$	22.34

Schedule of Non-cash Stock-based Compensation Expense

Total non-cash stock-based compensation expense for all stock awards that was recognized in the consolidated statements of operations and comprehensive loss is as follows:


	Year Ended December 31,
(in thousands)		2023		2022		2021
Research and development		$	10,159	$	6,775	$	5,856
General and administrative		23,046		20,581		9,491
Total		$	33,205	$	27,356	$	15,347

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (163,619)	$ (128,724)	$ (57,796)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	652	675	619
Stock-based compensation	33,205	27,356	15,347
Accretion/amortization of investments, net	(10,521)	(2,507)	493
Amortization of right-of-use assets – operating	1,724	1,660	1,471
Non-cash interest expense	18,083	21,108	1,450
Gain on disposal of property and equipment	0	0	(15)
Changes in operating assets and liabilities:
Receivables from collaborative partners	(5,432)	(543)	(876)
Prepaid expenses and other assets	(4,194)	(813)	(1,801)
Accounts payable and other liabilities	10,938	9,700	(4,740)
Operating lease liabilities	(1,636)	(1,505)	(72)
Net cash used in operating activities	(120,800)	(73,593)	(45,920)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of investments	(303,919)	(802,503)	(118,662)
Sales and maturities of investments	449,480	408,016	158,848
Proceeds from the sale of property and equipment	0	0	15
Purchases of property and equipment	(807)	(358)	(1,366)
Net cash provided by (used in) investing activities	144,754	(394,845)	38,835
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock	2,472	11,827	2,553
Proceeds from the sale of future royalties	0	35,000	250,000
Repayment of liability for sale of future royalties	(11,726)	(2,474)	0
Payments for repurchase of common stock	(50,000)	0	0
Payments for issuance costs related to the sale of future royalties	(43)	(336)	(255)
Net cash (used in) provided by financing activities	(59,297)	44,017	252,298
Net (decrease) increase in cash, cash equivalents, and restricted cash	(35,343)	(424,421)	245,213
Cash, cash equivalents and restricted cash, beginning of period	71,308	495,729	250,516
Cash, cash equivalents and restricted cash, end of period	35,965	71,308	495,729
Non-cash investing and financing activities:
Leased assets obtained in exchange for operating lease liabilities	0	0	20,685
Amounts accrued for property and equipment	8	154	31
Amounts accrued for issuance costs related to the sale of future royalties	0	80	102
Amounts accrued for repurchase of common stock	456	0	0
Receivable related to issuance of common stock, upon exercise of stock options	$ (51)	$ 40	$ 11

Sale of Future Royalties

12 Months Ended

Dec. 31, 2023

Other Liabilities Disclosure [Abstract]

Sale of Future Royalties

Jemperli Royalty Monetization Agreement

In October 2021, we signed a royalty monetization agreement (“Jemperli Royalty Monetization Agreement”) with Sagard Healthcare Royalty Partners, LP (“Sagard”). Under the terms of the Jemperli Royalty Monetization Agreement, we received $250.0 million in exchange for royalties and milestones payable to us under our GSK collaboration on annual global net sales of Jemperli below $1.0 billion starting in October 2021 (not including any combination products that contain both Jemperli and another Development Antibody). The aggregate Jemperli royalties and milestones to be received by Sagard under the Jemperli Royalty Monetization Agreement is capped at certain fixed multiples of the upfront payment based on time. Once Sagard receives an aggregate amount of either $312.5 million (125% of the upfront) by the end of 2026, or $337.5 million (135% of the upfront) during 2027, or $412.5 million (165% of the upfront) at any time after 2027, the Jemperli Royalty Monetization Agreement will expire resulting in us regaining all subsequent Jemperli royalties and milestones. As of December 31, 2023, Sagard has received a total of $10.4 million in royalties and milestones.

The Jemperli Royalty Monetization Agreement includes a call option pursuant to which at any time after December 1, 2024, we may reacquire our interest in the specified royalties by paying Sagard (in cash) a specified amount as described in the Jemperli Royalty Monetization Agreement. The exercise of this call option is at our sole discretion, which we currently do not anticipate exercising.

The proceeds received from Sagard of $250.0 million were recorded as a liability, net of transaction costs of $0.4 million, which will be amortized over the estimated life of the arrangement using the effective interest rate method. The aggregate future estimated payments, less the $249.6 million, net of proceeds, will be recognized as non-cash interest expense over the life of the agreement. Royalty and milestone revenue will be recognized as earned on net sales of Jemperli, and these payments to Sagard will be recorded as a reduction of the liability when paid. As such payments are made to Sagard, the balance of the liability will be effectively repaid over the life of the Jemperli Royalty Monetization Agreement.

We estimate the effective interest rate used to record non-cash interest expense under the Jemperli Royalty Monetization Agreement based on the estimate of future royalty payments to be received by Sagard. As of December 31, 2023, the estimated effective rate under the agreement was 8.1%. Over the life of the arrangement, the actual effective interest rate will be affected by the amount and the timing of the royalty payments received by Sagard and changes in our forecasted royalties. At each reporting date, we will reassess our estimate of total future royalty payments to be received and if such payments are materially different than our original estimates, we will prospectively adjust the imputed interest rate and the related amortization of the royalty obligation.

We recognized Jemperli non-cash royalty revenue of approximately $13.8 million and $2.3 million during the years ended December 31, 2023 and 2022, respectively and non-cash interest expense of approximately $17.1 million and $20.4 million during the years ended December 31, 2023 and 2022, respectively. The interest and amortization of issuance costs is reflected as non-cash interest expense for the sale of future royalties in the Consolidated Statements of Operations.

The following table shows the activity within the liability account for the year ended December 31, 2023:


(in thousands)	December 31, 2023
Liability related to sale of future Jemperli royalties and milestones - balance at 12/31/2022	$	269,540

Issuance costs related to the sale of future royalties	37
Amortization of issuance costs	39
Royalty and milestone payments to Sagard	(8,600)
Non-cash interest expense recognized	17,074
Liability related to sale of future royalties and milestones - ending balance	$	278,090

Zejula Royalty Monetization Agreement

In October 2020, in connection with Amendment No. 3 to the GSK Agreement, GSK agreed, under the terms of a settlement agreement (the “GSK Settlement Agreement”), to pay us a royalty on all GSK net sales of Zejula starting January 1, 2021. Under the GSK Settlement Agreement, the royalty is paid at a rate of 1.0% but is subject to reduction due to royalties paid to third parties, with a minimum royalty payable under the GSK Settlement Agreement of 0.5% of global net sales of Zejula. The current effective royalty rate is 0.5%.

In September 2022, we signed a purchase and sale agreement (the “Zejula Royalty Monetization Agreement”) with a wholly-owned subsidiary of DRI Healthcare Trust (“DRI”) to monetize all of our future royalties on global net sales of Zejula under the GSK Settlement Agreement. Under the terms of the Zejula Royalty Monetization Agreement, we received $35.0 million in exchange for all royalties payable by GSK to us under the GSK Settlement Agreement on global net sales of Zejula starting in July 2022 (the “Purchased Royalty Interest”). In addition, under the Zejula Royalty Monetization Agreement, we are entitled to receive an additional $10.0 million payment from DRI if Zejula is approved by the U.S. Food and Drug Administration for the treatment of endometrial cancer on or prior to December 31, 2025.

The proceeds received from DRI of $35.0 million were recorded as a liability, net of transaction costs of $0.2 million, which will be amortized over the estimated life of the arrangement using the effective interest rate method. Royalty revenue will be recognized as earned on net sales of Zejula, and these royalty payments to DRI will be recorded as a reduction of the liability when paid. The aggregate future estimated payments, less the $34.8 million, of net proceeds, will be recorded as non-cash interest expense over the life of the agreement. As such payments are made to DRI, the balance of the liability will be effectively repaid over the life of the Zejula Royalty Monetization Agreement.

We estimate the effective interest rate used to record non-cash interest expense under the Zejula Royalty Monetization Agreement based on the estimate of future royalty payments to be received by DRI. As of December 31, 2023, the estimated effective rate under the agreement was 2.7%. Over the life of the arrangement, the actual effective interest rate will be affected by the amount and the timing of the royalty payments received by DRI and the changes in our forecasted royalties. At each reporting date, we will reassess our estimate of total future royalty payments to be received and if such payments are materially different than our original estimates, we will prospectively adjust the imputed interest rate and the related amortization of the royalty obligation.

We recognized Zejula non-cash royalty revenue of approximately $3.4 million and $1.4 million during the years ended December 31, 2023 and 2022, respectively and non-cash interest expense of approximately $1.0 million and $0.7 million during the years ended December 31, 2023 and 2022, respectively. The interest and amortization of issuance costs is reflected as non-cash interest expense for the sale of future royalties in the Consolidated Statements of Operations.

The following table shows the activity within the liability account for the year ended December 31, 2023:


(in thousands)	December 31, 2023
Liability related to sale of future Zejula royalties - balance at 12/31/2022	$	34,873


Amortization of issuance costs	28
Royalty payments to DRI	(3,126)
Non-cash interest expense recognized	942
Liability related to sale of future royalties - ending balance	$	32,717

Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2023

Equity [Abstract]

Schedule of Repurchase Activity

The following table presents the repurchase activity from January 1, 2023 through May 5, 2023, the end date of the Repurchase Program:


	Total number of shares purchased	Average price paid per share		Approximate dollar value of shares purchased (in thousands)
First Quarter 2023	1,589,424	$	24.19	$	38,456
Second Quarter 2023	534,790	21.59		11,544
Total	2,124,214			$	50,000

Equity Incentive Plans - Time-based Restricted Stock Units (Details) - RSUs - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Number of Restricted Stock Units
Number of shares, beginning balance (in shares)	1,028,843
Granted (in shares)	568,574
Released (in shares)	(68,900)
Forfeitures and cancellations (in shares)	(46,945)
Number of shares, ending balance (in shares)	1,481,572	1,028,843
Number of shares, Restricted stock units expected to vest (in shares)	1,481,572
Weighted-Average Grant Date Fair Value
Weighted average grant date fair value, beginning balance (in dollars per share)	$ 26.14
Granted (in dollars per share)	22.02
Released (in dollars per share)	23.89
Forfeitures and cancellations (in dollars per share)	21.87
Weighted average grant date fair value, ending balance (in dollars per share)	24.80	$ 26.14
Weighted average grant date fair value , Restricted stock units expected to vest (in dollars per share)	$ 24.80
Weighted-Average Remaining Contractual Term and Aggregate Intrinsic Value
Weighted average remaining contractual term, other than options outstanding (in years)	8 months 23 days	1 year 2 months 1 day
Weighted average remaining contractual term, other than options vested and expected to vest (in years)	8 months 23 days
Aggregate intrinsic value, outstanding	$ 31,735	$ 31,884
Aggregate intrinsic value, restricted stock units expected to vest	$ 31,735

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2023

Commitments and Contingencies Disclosure [Abstract]

Schedule of Costs in Cash Flow Statement

The following non-cancellable office lease costs are included in our consolidated statements of cash flow (in thousands):


		Year Ended December 31,
Leases	Classification on the Cash Flow	2023		2022		2021
Operating lease cost	Operating	$	2,478	$	2,478	$	2,213
Cash paid for amounts included in the measurement of lease liabilities	Operating	2,386		2,316		705

Schedule of Future Minimum Annual Obligations

At December 31, 2023, the future minimum annual obligations for the Company’s operating lease liabilities are as follows:


Years Ending December 31, (in thousands)
2024	$	2,457
2025	2,531
2026	2,607
2027	2,685
2028	2,766
Thereafter	7,788
Total minimum payments required	$	20,834
Less: imputed interest	(3,020)
Total	$	17,814

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Dec. 31, 2023
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Equity Incentive Plans - Option Fair Value Assumptions (Details) - Options - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	3.80%	2.50%	0.70%
Expected volatility	85.70%	87.40%	92.90%
Expected dividend yield	0.00%	0.00%	0.00%
Expected term (in years)	5 years 9 months 25 days	6 years 1 month 2 days	6 years 2 months 4 days
Weighted average grant date fair value per share (in dollars per share)	$ 16.06	$ 21.58	$ 22.34

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 26: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(iii)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 27: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(iv)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 28: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(v)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

+ Details

Employee Benefit Plan (Details) - USD ($)	12 Months Ended
Employee Benefit Plan (Details) - USD ($)	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Retirement Benefits [Abstract]
Employer match, percent of contributions	100.00%	100.00%
Employer match, percent of employees' gross pay	10.00%	6.00%
Employer match, maximum contributions	$ 22,500	$ 11,000	$ 8,000
Employer contributions to the plan	$ 1,600,000	$ 1,000,000	$ 600,000

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Schedule of Loss before Income Tax Provision

The components of loss before income tax provision consist of the following:


	Year Ended December 31,
(in thousands)	2023		2022		2021
U.S.	$	(163,580)	$	(128,650)	$	(57,741)
Foreign	(43)		(50)		(55)
Consolidated net loss before income taxes	$	(163,623)	$	(128,700)	$	(57,796)

Schedule of Components of Deferred Tax Assets and Liabilities

Significant components of our deferred tax assets and liabilities are as follows:


	December 31,
(in thousands)	2023		2022
Deferred Tax Assets:
Net operating loss carryforwards	$	72,777	$	66,160
Section 174 Capitalized R&D	37,240		16,570
Research and development credits	19,058		12,844
Equity compensation	10,533		10,021
Deferred Zejula royalty revenue	6,978		7,371
Lease liability	3,912		4,194
Other, net	7,201		3,458
Total deferred tax assets	157,699		120,618
Deferred Tax Liabilities:
ROU asset	(3,552)		(3,859)
Other, net	(2,658)		—
Fixed assets	(122)		(189)
Total deferred tax liabilities	(6,332)		(4,048)
Net deferred tax assets	151,367		116,570
Less: valuation allowance	(151,367)		(116,570)
Deferred tax assets, net of valuation allowance	$	—	$	—

Schedule of Reconciliation of Expected Statutory Federal Income Tax Provision and Actual Income Tax Provision

The following is a reconciliation of the expected statutory federal income tax provision to our actual income tax provision:


	Year Ended December 31,
(in thousands)	2023		2022		2021
Expected income tax benefit at federal statutory tax rate	$	(34,361)	$	(27,026)	$	(12,138)
State income taxes, net of federal benefit	(1,912)		(800)		(142)
Permanent items	56		27		17
Equity compensation	2,840		(297)		(708)


Non-deductible compensation	3,693		2,060		—


Research credits	(6,213)		(3,319)		8,087
Other	109		(6)		42
Change in the valuation allowance	35,784		29,385		4,842
Income tax (benefit) expense	$	(4)	$	24	$	—

Schedule of Activity Related to Unrecognized Tax Benefits

The following table summarizes the activity related to our unrecognized tax benefits:


	Year Ended December 31,
(in thousands)	2023		2022
Balance at the beginning of the year	$	3,369	$	2,473
Increase related to prior year tax positions	153		—
Increase related to current year tax positions	1,494		896
Balance at the end of the year	$	5,016	$	3,369

Fair Value Measurements and Available for Sale Investments - Schedule of Unrealized Loss and Fair Values in a Loss Position (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months, Fair Value	$ 106,530	$ 404,386
Less than 12 Months, Gross Unrealized Losses	(120)	(4,144)
12 Months or Greater, Fair Value	132,167	62,527
12 Months or Greater, Gross Unrealized Losses	(669)	(933)
Fair Value	238,697	466,914
Gross Unrealized Losses	(789)	(5,077)
Agency securities
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months, Fair Value	2,530	61,117
Less than 12 Months, Gross Unrealized Losses	(1)	(843)
12 Months or Greater, Fair Value	17,723	3,437
12 Months or Greater, Gross Unrealized Losses	(68)	(70)
Fair Value	20,253	64,554
Gross Unrealized Losses	(69)	(913)
Certificates of Deposit
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months, Fair Value	0	481
Less than 12 Months, Gross Unrealized Losses	0	(10)
12 Months or Greater, Fair Value	244	2,375
12 Months or Greater, Gross Unrealized Losses	(2)	(49)
Fair Value	244	2,856
Gross Unrealized Losses	(2)	(59)
Commercial and corporate obligations
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months, Fair Value	5,160	44,213
Less than 12 Months, Gross Unrealized Losses	(9)	(624)
12 Months or Greater, Fair Value	15,200	14,778
12 Months or Greater, Gross Unrealized Losses	(74)	(292)
Fair Value	20,360	58,991
Gross Unrealized Losses	(83)	(916)
US Treasury Securities
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months, Fair Value	98,840	298,575
Less than 12 Months, Gross Unrealized Losses	(110)	(2,667)
12 Months or Greater, Fair Value	99,000	41,937
12 Months or Greater, Gross Unrealized Losses	(525)	(522)
Fair Value	197,840	340,513
Gross Unrealized Losses	$ (635)	$ (3,189)

Summary of Significant Accounting Policies - Narrative (Details)	12 Months Ended
	Dec. 31, 2023 USD ($) segment bank	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Accounting Policies [Abstract]
Number of reportable segments \| segment	1
Number of banks utilized for diversification of funds (in banks) \| bank	3
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Long-lived asset impairment charges \| $	$ 0	$ 0	$ 0
RSUs
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Award equivalent shares	1
Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property and equipment, useful life (in years)	3 years
Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property and equipment, useful life (in years)	7 years

Equity Incentive Plans - Allocation of Share-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 33,205	$ 27,356	$ 15,347
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	10,159	6,775	5,856
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 23,046	$ 20,581	$ 9,491

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

Fair Value Measurements and Available for Sale Investments - Available-for-sale Investments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 382,555	$ 517,907
Gross Unrealized Gains	199	38
Gross Unrealized Losses	(789)	(5,077)
Total Fair Value	381,965	512,868
Short-term investments	354,939	369,933
Long-term investments	27,026	142,935
Agency securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	20,322	75,504
Gross Unrealized Gains	0	11
Gross Unrealized Losses	(69)	(913)
Total Fair Value	20,253	74,602
Short-term investments	20,300	57,100
Long-term investments	$ 0	$ 17,500
Agency securities \| Minimum
Debt Securities, Available-for-sale [Line Items]
Remaining maturity (in years)	1 year	1 year
Agency securities \| Maximum
Debt Securities, Available-for-sale [Line Items]
Remaining maturity (in years)	2 years	2 years
Certificates of deposit
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 246	$ 2,915
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(2)	(59)
Total Fair Value	244	2,856
Short-term investments	200	2,600
Long-term investments	$ 0	$ 300
Certificates of deposit \| Minimum
Debt Securities, Available-for-sale [Line Items]
Remaining maturity (in years)	1 year	1 year
Certificates of deposit \| Maximum
Debt Securities, Available-for-sale [Line Items]
Remaining maturity (in years)	2 years	2 years
Commercial and corporate obligations
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 35,760	$ 61,791
Gross Unrealized Gains	77	8
Gross Unrealized Losses	(83)	(916)
Total Fair Value	35,754	60,883
Short-term investments	25,800	44,000
Long-term investments	$ 10,000	$ 16,900
Commercial and corporate obligations \| Minimum
Debt Securities, Available-for-sale [Line Items]
Remaining maturity (in years)	1 year	1 year
Commercial and corporate obligations \| Maximum
Debt Securities, Available-for-sale [Line Items]
Remaining maturity (in years)	2 years	2 years
US Treasury Securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 326,227	$ 377,697
Gross Unrealized Gains	122	19
Gross Unrealized Losses	(635)	(3,189)
Total Fair Value	325,714	374,527
Short-term investments	308,600	266,200
Long-term investments	$ 17,100	$ 108,300
US Treasury Securities \| Minimum
Debt Securities, Available-for-sale [Line Items]
Remaining maturity (in years)	1 year	1 year
US Treasury Securities \| Maximum
Debt Securities, Available-for-sale [Line Items]
Remaining maturity (in years)	2 years	2 years