Allakos (ALLK) 10-Q 9 Aug 23 2023 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2023	Aug. 04, 2023
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q2
Trading Symbol	ALLK
Entity Registrant Name	Allakos Inc.
Entity Central Index Key	0001564824
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		86,917,706
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity File Number	001-38582
Entity Tax Identification Number	45-4798831
Entity Address, Address Line One	825 Industrial Road
Entity Address, Address Line Two	Suite 500
Entity Address, City or Town	San Carlos
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94070
City Area Code	650
Local Phone Number	597-5002
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common Stock, par value $0.001
Security Exchange Name	NASDAQ
Document Quarterly Report	true
Document Transition Report	false
Entity Incorporation, State or Country Code	DE

BALANCE SHEETS (Unaudited)

BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 67,381	$ 87,217
Investments	153,721	192,569
Prepaid expenses and other current assets	30,460	29,057
Total current assets	251,562	308,843
Property and equipment, net	36,446	39,144
Operating lease right-of-use assets	24,489	30,225
Other long-term assets	6,699	8,208
Total assets	319,196	386,420
Current liabilities:
Accounts payable	4,307	4,832
Accrued expenses and other current liabilities	20,177	25,206
Total current liabilities	24,484	30,038
Operating lease liabilities, net of current portion	39,734	45,949
Total liabilities	64,218	75,987
Contingencies (Note 7)
Stockholders’ equity:
Preferred stock, $0.001 par value per share; 20,000 shares authorized as of June 30, 2023 and December 31, 2022; no shares issued and outstanding as of June 30, 2023 and December 31, 2022	0	0
Common stock, $0.001 par value per share; 200,000 shares authorized as of June 30, 2023 and December 31, 2022; 86,823 and 85,387 shares issued and outstanding as of June 30, 2023 and December 31, 2022, respectively	87	85
Additional paid-in capital	1,265,350	1,243,408
Accumulated other comprehensive loss	(159)	(284)
Accumulated deficit	(1,010,300)	(932,776)
Total stockholders’ equity	254,978	310,433
Total liabilities and stockholders’ equity	$ 319,196	$ 386,420

BALANCE SHEETS (Unaudited) (Par

BALANCE SHEETS (Unaudited) (Parenthetical) - $ / shares	Jun. 30, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	20,000,000	20,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	86,823,000	85,387,000
Common stock, shares outstanding	86,823,000	85,387,000

STATEMENTS OF OPERATIONS AND CO

STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Operating expenses
Research and development	$ 27,280	$ 34,448	$ 60,358	$ 211,255
General and administrative	10,537	14,669	22,505	33,513
Total operating expenses	37,817	49,117	82,863	244,768
Loss from operations	(37,817)	(49,117)	(82,863)	(244,768)
Interest income	2,697	104	5,375	187
Other expense, net	0	(90)	(36)	(1,545)
Net loss	(35,120)	(49,103)	(77,524)	(246,126)
Unrealized gain (loss) on investments	(171)	209	125	(107)
Comprehensive loss	$ (35,291)	$ (48,894)	$ (77,399)	$ (246,233)
Net loss per common share:
Net loss per common share, basic	$ (0.41)	$ (0.9)	$ (0.9)	$ (4.5)
Net loss per common share, diluted	$ (0.41)	$ (0.9)	$ (0.9)	$ (4.5)
Weighted-average number of common shares outstanding:
Weighted-average shares of common stock outstanding, basic	86,646	54,798	86,246	54,742
Weighted-average shares of common stock outstanding, diluted	86,646	54,798	86,246	54,742

STATEMENTS OF STOCKHOLDERS' EQU

STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Gain (Loss)	Accumulated Deficit
Balance at Dec. 31, 2021	$ 445,476	$ 54	$ 1,058,399	$ (153)	$ (612,824)
Balance, Shares at Dec. 31, 2021		54,622
Stock-based compensation expense	11,392	$ 0	11,392	0	0
Issuance of common stock upon exercise of stock options	104	$ 0	104	0	0
Issuance of common stock upon exercise of stock options, Shares		34
Issuance of common stock upon 2018 ESPP purchase	243	$ 0	243	0	0
Issuance of common stock upon 2018 ESPP purchase, Shares		42
Issuance of common stock upon vesting of restricted stock units	0	$ 0	0	0	0
Issuance of common stock upon vesting of restricted stock units, Shares		63
Unrealized gain (loss) on investments	(316)	$ 0	0	(316)	0
Net loss	(197,023)	0	0	0	(197,023)
Balance at Mar. 31, 2022	259,876	$ 54	1,070,138	(469)	(809,847)
Balance, Shares at Mar. 31, 2022		54,761
Balance at Dec. 31, 2021	445,476	$ 54	1,058,399	(153)	(612,824)
Balance, Shares at Dec. 31, 2021		54,622
Unrealized gain (loss) on investments	(107)
Net loss	(246,126)
Balance at Jun. 30, 2022	222,809	$ 54	1,081,965	(260)	(858,950)
Balance, Shares at Jun. 30, 2022		54,844
Balance at Mar. 31, 2022	259,876	$ 54	1,070,138	(469)	(809,847)
Balance, Shares at Mar. 31, 2022		54,761
Stock-based compensation expense	11,761	$ 0	11,761	0	0
Issuance of common stock upon exercise of stock options	66	$ 0	66	0	0
Issuance of common stock upon exercise of stock options, Shares		25
Issuance of common stock upon vesting of restricted stock units	0	$ 0	0	0	0
Issuance of common stock upon vesting of restricted stock units, Shares		58
Unrealized gain (loss) on investments	209	$ 0	0	209	0
Net loss	(49,103)	0	0	0	(49,103)
Balance at Jun. 30, 2022	222,809	$ 54	1,081,965	(260)	(858,950)
Balance, Shares at Jun. 30, 2022		54,844
Balance at Dec. 31, 2022	310,433	$ 85	1,243,408	(284)	(932,776)
Balance, Shares at Dec. 31, 2022		85,387
Stock-based compensation expense	10,665	$ 0	10,665	0	0
Issuance of common stock upon exercise of stock options	26	$ 0	26	0	0
Issuance of common stock upon exercise of stock options, Shares		6
Issuance of common stock upon 2018 ESPP purchase	442	$ 0	442	0	0
Issuance of common stock upon 2018 ESPP purchase, Shares		144
Issuance of common stock upon vesting of restricted stock units	0	$ 1	(1)	0	0
Issuance of common stock upon vesting of restricted stock units, Shares		881
Issuance of common stock under the ATM Offering net of issuance costs	990	$ 0	990	0	0
Issuance of common stock under the ATM Offering net of issuance costs, Shares		142
Unrealized gain (loss) on investments	296	$ 0	0	296	0
Net loss	(42,404)	0	0	0	(42,404)
Balance at Mar. 31, 2023	280,448	$ 86	1,255,530	12	(975,180)
Balance, Shares at Mar. 31, 2023		86,560
Balance at Dec. 31, 2022	$ 310,433	$ 85	1,243,408	(284)	(932,776)
Balance, Shares at Dec. 31, 2022		85,387
Issuance of common stock upon exercise of stock options, Shares	6
Unrealized gain (loss) on investments	$ 125
Net loss	(77,524)
Balance at Jun. 30, 2023	254,978	$ 87	1,265,350	(159)	(1,010,300)
Balance, Shares at Jun. 30, 2023		86,823
Balance at Mar. 31, 2023	280,448	$ 86	1,255,530	12	(975,180)
Balance, Shares at Mar. 31, 2023		86,560
Stock-based compensation expense	9,821	$ 0	9,821	0	0
Issuance of common stock upon vesting of restricted stock units	0	$ 1	(1)	0	0
Issuance of common stock upon vesting of restricted stock units, Shares		263
Unrealized gain (loss) on investments	(171)	$ 0	0	(171)	0
Net loss	(35,120)	0	0	0	(35,120)
Balance at Jun. 30, 2023	$ 254,978	$ 87	$ 1,265,350	$ (159)	$ (1,010,300)
Balance, Shares at Jun. 30, 2023		86,823

STATEMENTS OF CASH FLOWS (unaud

STATEMENTS OF CASH FLOWS (unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Cash flows from operating activities
Net loss	$ (77,524)	$ (246,126)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	3,045	4,064
Stock-based compensation	20,486	23,153
Net amortization (accretion) of premiums and discounts on investments	(3,187)	1,616
Noncash lease expense	784	961
Loss on disposal of property and equipment	3	28
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(1,201)	17,621
Other long-term assets	1,509	(4,148)
Accounts payable	(357)	(3,645)
Accrued expenses and other current liabilities	(4,729)	1,969
Operating lease liabilities, net of current portion	(1,562)	(2,550)
Net cash used in operating activities	(62,733)	(207,057)
Cash flows from investing activities
Purchases of investments	(113,042)	(19,988)
Proceeds from sales of investments	0	19,989
Proceeds from maturities of investments	155,000	140,000
Proceeds from sale of property and equipment	0	1,169
Purchases of property and equipment	(519)	(5,699)
Net cash provided by investing activities	41,439	135,471
Cash flows from financing activities
Proceeds from issuance of common stock, net of issuance costs	990	0
Proceeds from exercise of stock options	26	170
Proceeds from issuance of common stock under the 2018 ESPP	442	243
Net cash provided by financing activities	1,458	413
Net increase (decrease) in cash, cash equivalents and restricted cash	(19,836)	(71,173)
Cash, cash equivalents and restricted cash, beginning of period	88,689	155,097
Cash, cash equivalents and restricted cash, end of period	68,853	83,924
Noncash investing and financing items:
Noncash adjustments to right-of-use assets	(5,617)	0
Increase (decrease) in payables related to purchase of property and equipment	$ (169)	$ (2,238)

Organization and Business

Organization and Business	6 Months Ended
	Jun. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Business	1. Organization and Business Allakos Inc. (“Allakos” or the “Company”) was incorporated in the state of Delaware in March 2012. Allakos is a clinical stage biopharmaceutical company focused on the development of lirentelimab (AK002) and AK006 for the treatment of eosinophil and mast cell related diseases. The Company’s primary activities to date have included establishing its facilities, recruiting personnel, conducting research and development of its product candidates and raising capital. The Company’s operations are located in San Carlos, California. The Company operates in one reportable segment. Liquidity Matters Since inception, the Company has incurred net losses and negative cash flows from operations. During the six months ended June 30, 2023, the Company incurred a net loss of $ 77.5 million . At June 30, 2023, the Company had an accumulated deficit of $ 1,010.3 million and does not expect to experience positive cash flows from operating activities in the foreseeable future. The Company has financed its operations to date primarily through the sale of common stock. Management expects to incur additional operating losses in the future as the Company continues to further develop, seek regulatory approval for and, if approved, commence commercialization of its product candidates. Due to the clinical study results released in December 2021, our Board of Directors approved in February 2022 plans to reduce our contractual commitments and a reorganization plan (the “Reorganization Plan”) to reduce operating costs and better align our workforce with the clinical development plans of our business. The Company had $ 221.1 million of cash, cash equivalents and marketable securities at June 30, 2023 . Management believes that this amount is sufficient to fund the Company’s operations for at least the next 12 months from the issuance date of these financial statements.

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2023
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The unaudited interim financial statements have been prepared in accordance with United States generally accepted accounting principles (“U.S. GAAP”). The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts and disclosures reported in the financial statements and accompanying notes. The interim balance sheet as of June 30, 2023, the statements of operations and comprehensive loss, statements of stockholders’ equity for the three and six months ended June 30, 2023 and 2022 and statements of cash flows for the six months ended June 30, 2023 and 2022 are unaudited. The unaudited interim financial statements have been prepared on the same basis as the audited annual financial statements and reflect, in the opinion of management, all adjustments of a normal and recurring nature that are necessary for the fair presentation of the Company’s financial position as of June 30, 2023 and its results of operations and comprehensive loss for the three and six months ended June 30, 2023 and 2022 and its cash flows for the six months ended June 30, 2023 and 2022. Certain information and note disclosures normally included in annual audited financial statements prepared in accordance with U.S. GAAP have been omitted. The financial data and the other financial information disclosed in these notes to the interim financial statements are also unaudited. The results of operations for any interim period are not necessarily indicative of the results to be expected for the entire year or for any other future annual or interim period. These interim financial statements should be read in conjunction with the Company’s audited financial statements included in the Company’s Annual Report on Form 10-K, which was filed with the SEC on March 6, 2023. Use of Estimates Management uses significant judgment when making estimates related to common stock valuation and related stock-based compensation expense, accrued research and development expense, and lease-related assets and liabilities. Management bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results could differ from those estimates under different assumptions or conditions, and those differences could be material to the financial position and results of operations. Concentration of Credit Risk and Other Risks and Uncertainties Financial instruments that potentially subject the Company to credit risk principally consist of cash, cash equivalents and investments. These financial instruments are currently held in accounts in varying amounts at four separate financial institutions that management believes possesses high credit quality. Amounts on deposit with these financial institutions have and will continue to exceed federally-insured limits. The Company has not experienced any losses on its cash deposits. Additionally, the Company’s investment policy limits its investments to certain types of securities issued by or backed by the U.S. government and its agencies. The Company is subject to a number of risks similar to that of other early stage biopharmaceutical companies, including, but not limited to, the need to obtain adequate additional funding, possible failure of current or future clinical trials, its reliance on third-parties to conduct its clinical trials, the need to obtain regulatory and marketing approvals for its product candidates, competitive developments, the need to successfully commercialize and gain market acceptance of the Company’s product candidates, its right to develop and commercialize its product candidates pursuant to the terms and conditions of the licenses granted to the Company, protection of proprietary technology, the ability to make milestone, royalty or other payments due under licensing agreements, and the need to secure and maintain adequate manufacturing arrangements with third-parties. If the Company does not successfully commercialize or partner its product candidates, it will be unable to generate product revenue or achieve profitability. Cash, Cash Equivalents and Restricted Cash The Company considers all highly liquid investments with original maturities of three months or less from the date of purchase to be cash equivalents. The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the Company’s balance sheets and which, in aggregate, represent the amounts reported in the accompanying statements of cash flows (in thousands): June 30, December 31, 2023 2022 Cash and cash equivalents $ 67,381 $ 87,217 Restricted cash in other long-term assets 1,472 1,472 Total $ 68,853 $ 88,689 June 30, December 31, 2022 2021 Cash and cash equivalents $ 82,452 $ 152,822 Restricted cash in other long-term assets 1,472 2,275 Total $ 83,924 $ 155,097 Restricted cash at June 30, 2023 represents $ 1.5 million in security deposits for the lease of the Company’s facility in San Carlos, California. The security deposit is in the form of a letter of credit secured by restricted cash and is recorded in other long-term assets on the Company’s balance sheets . Investments The Company invests in marketable securities, primarily securities issued by the United States government and its agencies. The Company’s investments are considered available-for-sale and are classified as current assets even when the stated maturities of the underlying securities exceed one year from the date of the current balance sheet being reported. This classification reflects management’s ability and intent to utilize proceeds from the sale of such investments to fund ongoing operations. Unrealized gains and losses are excluded from earnings and are reported as a component of accumulated other comprehensive gain (loss). The cost of securities sold is determined using the specific-identification method. Interest earned and adjustments for the amortization of premiums and discounts on investments are included in interest income on the statements of operations and comprehensive loss. Realized gains and losses and declines in fair value judged to be other than temporary, if any, on investments in marketable securities are included in other expense, net, on the statements of operations and comprehensive loss. Operating Leases The Company accounts for its leases in accordance with Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 842, “Leases” (“ASC 842”). Right-of-use assets represent the Company’s right to use an underlying asset over the lease term and include any lease payments made prior to the lease commencement date and are reduced by lease incentives. Lease liabilities represent the present value of the total lease payments over the lease term, calculated using the Company’s incremental borrowing rate. In determining the Company’s incremental borrowing rate, consideration is given to the term of the lease and the Company’s credit risk. The Company recognizes options to extend a lease when it is reasonably certain that it will exercise such extension. The Company does not recognize options to terminate a lease when it is reasonably certain that it will not exercise such early termination options. Lease expense is recognized on a straight-line basis over the expected lease term. Accrued Research and Development Expense Service agreements with contract development and manufacturing organizations (“CDMOs”), clinical contract research organizations (“CROs”) and clinical investigative sites comprise a significant component of the Company’s research and development activities. External costs for these vendors are recognized as the services are incurred. The Company accrues for expenses resulting from obligations under agreements with its third-parties for which the timing of payments does not match the periods over which the materials or services are provided to the Company. Accruals are recorded based on estimates of services received and efforts expended pursuant to agreements established with CDMOs, clinical CROs, clinical investigative sites and other outside service providers. These estimates are typically based on contracted amounts applied to the proportion of work performed and determined through analysis with internal personnel and external service providers as to the progress or stage of completion of the services. The Company makes judgements and estimates in determining the accrual balance in each reporting period. In the event advance payments are made to a CDMO, clinical CRO, clinical investigative site or other outside service provider, the payments are recorded within prepaid expenses and other current assets or other long-term assets, as appropriate, and subsequently recognized as research and development expense when the associated services have been performed. As actual costs become known, the Company adjusts its liabilities and assets. Inputs, such as the extent of services received and the duration of services to be performed, may vary from the Company’s estimates, which will result in adjustments to research and development expense in future periods. Changes in these estimates that result in material changes to the Company’s accruals could materially affect the Company’s results of operations. The Company’s historical estimates have not been materially different from actual amounts recorded. Research and Development Expense Research and development costs are expensed as incurred. Research and development costs include, among others, consulting costs, salaries, benefits, travel, stock-based compensation, laboratory supplies and other non-capital equipment utilized for in-house research, allocation of facilities and overhead costs and external costs paid to third-parties that conduct research and development activities on the Company’s behalf. Costs to terminate commitments with third-party suppliers performing research and development activities and amounts incurred in connection with license agreements, including milestone payments, are also included in research and development expense. Advance payments for goods or services to be rendered in the future for use in research and development activities are deferred and included in prepaid expenses and other current assets or other long-term assets, as appropriate. The deferred amounts are expensed as the related goods are delivered or the services are performed. Comprehensive Loss Comprehensive loss is defined as the change in stockholders’ equity during a period from transactions and other events and circumstances from non-owner sources. The differences between net loss and comprehensive loss for the three and six months ended June 30, 2023 and 2022 are a result of unrealized gains and losses on the Company’s investments included in current assets on the Company’s balance sheets. Net Loss per Share The Company calculates basic net loss per share by dividing the net loss attributable to common stockholders by the weighted-average shares of common stock outstanding during the period. The Company calculates diluted net loss per share after giving consideration to all potentially dilutive securities outstanding during the period using the treasury-stock and if-converted methods, except where the effect of including such securities would be anti-dilutive. Because the Company has reported net losses since inception, the effect from potentially dilutive securities would have been anti-dilutive and therefore has been excluded from the calculation of diluted net loss per share. The Company’s weighted-average shares of common stock outstanding increased from 54.8 million shares during the second quarter of 2022 to a weighted-average of 86.6 million during the second quarter of 2023 and from 54.7 million shares to 86.2 million shares during the six months ended June 30, 2022 and June 30, 2023, respectively, primarily as a result of the 29.9 million shares sold as part of an underwritten registered direct offering closed on September 21, 2022 (the “September 2022 Offering”). Refer to Note 8 “Stockholders’ Equity” for additional details related to the offering. Basic and diluted net loss per share was calculated as follows (in thousands, except per share data): Three Months Ended Six Months Ended June 30, June 30, 2023 2022 2023 2022 Numerator: Net loss $ ( 35,120 ) $ ( 49,103 ) $ ( 77,524 ) $ ( 246,126 ) Denominator: Weighted-average shares of common stock outstanding, 86,646 54,798 86,246 54,742 Net loss per share, basic and diluted $ ( 0.41 ) $ ( 0.90 ) $ ( 0.90 ) $ ( 4.50 ) The following table sets forth the potentially dilutive securities that have been excluded from the calculation of diluted net loss per share due to their anti-dilutive effect for the periods indicated (in thousands): Six Months Ended June 30, 2023 2022 Options to purchase common stock 7,216 5,543 Unvested restricted stock units 5,598 4,839 Unvested performance stock units 2,868 3,809 Shares issuable under employee stock purchase plans 123 67 Total 15,805 14,258 Recently Issued and Adopted Accounting Pronouncements The Company has reviewed recently issued accounting pronouncements and concluded they are either not applicable to the business or that no material effect is expected on the Company’s financial statements as a result of future adoption.

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2023
Fair Value Disclosures [Abstract]
Fair Value Measurements	3. Fair Value Measurements The Company measures and reports certain financial instruments as assets and liabilities at fair value on a recurring basis. The Company’s financial assets measured at fair value on a recurring basis were as follows (in thousands): June 30, 2023 Level 1 Level 2 Level 3 Total Cash equivalents: Money market funds $ 66,754 $ — $ — $ 66,754 Total cash equivalents 66,754 — — 66,754 Short-term marketable securities U.S. treasuries 153,721 — — 153,721 Total short-term marketable securities 153,721 — — 153,721 Total cash equivalents and short-term $ 220,475 $ — $ — $ 220,475 December 31, 2022 Level 1 Level 2 Level 3 Total Cash equivalents: Money market funds $ 86,270 $ — $ — $ 86,270 Total cash equivalents 86,270 — — 86,270 Short-term marketable securities: U.S. treasuries 192,569 — — 192,569 Total short-term marketable securities 192,569 — — 192,569 Total cash equivalents and short-term $ 278,839 $ — $ — $ 278,839 The Company evaluates transfers between levels at the end of each reporting period. There were no transfers of assets or liabilities between levels during the three and six months ended June 30, 2023 and 2022.

Investments

Investments	6 Months Ended
	Jun. 30, 2023
Investments, Debt and Equity Securities [Abstract]
Investments	4. Investments All investments were considered available-for-sale at June 30, 2023. The amortized cost, gross unrealized holding gains or losses, and fair value of the Company’s investments by major security type at June 30, 2023 and December 31, 2022 are summarized in the table below (in thousands): June 30, 2023 Amortized Unrealized Unrealized Fair Available-for-sale securities: U.S. treasuries classified as investments $ 153,880 $ 10 $ ( 169 ) $ 153,721 Total available-for-sale securities $ 153,880 $ 10 $ ( 169 ) $ 153,721 December 31, 2022 Amortized Unrealized Unrealized Fair Available-for-sale securities: U.S. treasuries classified as investments $ 192,853 $ 3 $ ( 287 ) $ 192,569 Total available-for-sale securities $ 192,853 $ 3 $ ( 287 ) $ 192,569 The amortized cost of available-for-sale securities is adjusted for amortization of premiums and accretion of discounts to maturity. As of June 30, 2023 and December 31, 2022, the aggregate fair value of securities held by the Company in an unrealized loss position for less than twelve months was $ 145.9 million and $ 162.6 million , respectively. These securities had remaining maturities of less than one year . The Company has the intent and ability to hold such securities until recovery and has determined that there has been no material change to their credit risk. As a result, the Company determined it did not hold any investments with a credit loss at June 30, 2023 and December 31, 2022. There were no material realized gains or losses recognized on the sale or maturity of available-for-sale securities during the three and six months ended June 30, 2023 and 2022, and as a result, there were no material reclassifications out of accumulated other comprehensive gain (loss) for the same periods.

Balance Sheet Components and Su

Balance Sheet Components and Supplemental Disclosures	6 Months Ended
	Jun. 30, 2023
Balance Sheet Related Disclosures [Abstract]
Balance Sheet Components and Supplemental Disclosures	5. Balance Sheet Components and Supplemental Disclosures Property and Equipment, Net Property and equipment, net, consisted of the following (in thousands): June 30, December 31, 2023 2022 Laboratory equipment $ 6,985 $ 6,473 Furniture and office equipment 3,946 3,947 Leasehold improvements 32,457 32,457 Capitalized software 4,186 4,112 Construction-in-progress 182 422 47,756 47,411 Less accumulated depreciation ( 11,310 ) ( 8,267 ) Property and equipment, net $ 36,446 $ 39,144 Depreciation and amortization expense for the three months ended June 30, 2023 and 2022 was $ 1.5 million and $ 1.9 million , respectively. Depreciation and amortization expense for the six months ended June 30, 2023 and 2022 was $ 3.0 million and $ 4.1 million , respectively. Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities consisted of the following (in thousands): June 30, December 31, 2023 2022 Accrued contract research and development expense $ 11,990 $ 13,950 Accrued compensation and benefits expense 4,615 7,039 Current portion of operating lease liabilities 2,645 3,161 Other current liabilities 927 1,056 Total $ 20,177 $ 25,206

Leases

Leases	6 Months Ended
	Jun. 30, 2023
Leases [Abstract]
Leases	6. Leases Operating Leases The Company’s lease obligations primarily relate to leased office and laboratory space under noncancelable operating lease. In accordance with ASC 842, the Company has performed an evaluation of its other contracts with vendors and has determined that, except for the leases described below, none of its other contracts contain a material lease. 2019 San Carlos Lease In December 2019 , the Company entered into an operating lease agreement for office and laboratory space in San Carlos, California (the “2019 San Carlos Lease”). The contractual term of the 2019 San Carlos Lease is 10.25 years from August 2021 until October 2031 . The 2019 San Carlos Lease provides rent abatements and includes a one-time option to extend the lease term for five years . This option to extend the lease term was not determined to be reasonably certain and therefore has not been included in the Company’s calculation of the associated operating lease liability under ASC 842. The 2019 San Carlos Lease includes monthly base rent amounts escalating over the term of the lease. In addition, the lessor provided for a TIA of up to $ 14.7 million, which was fully utilized and are recorded in lease obligations. On March 27, 2023, the Company entered into an amendment for the 2019 San Carlos Lease, whereby rentable square feet was adjusted to 95,692 square feet and lease payments were reduced by approximately 2.5 % per month, effective from January 1, 2022 through the end of the lease term. The Company accounted for these changes as a modification under ASC 842 and the operating right-of-use asset and lease liability were remeasured during the first quarter of 2023 utilizing an estimated incremental borrowing rate of 10.5 %. Our estimated incremental borrowing rate was based on our estimated rate of interest for a fully collateralized borrowing over a similar term as the remaining lease payments while incorporating our credit risk. As a result of the modification, the right-of-use asset and lease liability decreased by approximately $ 5.6 million. No gain or loss was recognized upon the modification. Classification of Operating Leases The 2019 San Carlos Lease required a security deposit of $ 1.5 million, which the Company satisfied by establishing a letter of credit secured by restricted cash. As of June 30, 2023 and December 31, 2022, a security deposit of $ 1.5 million for the 2019 San Carlos Lease was recorded as restricted cash in other long-term assets on the Company’s balance sheets. Classification of the Company’s operating lease liabilities included on the Company’s balance sheets at June 30, 2023 and December 31, 2022 was as follows (in thousands): June 30, December 31, 2023 2022 Operating lease liabilities Current portion included in accrued expenses and $ 2,645 $ 3,161 Operating lease liabilities, net of current portion 39,734 45,949 Total operating lease liabilities $ 42,379 $ 49,110 The components of lease costs included in operating expenses in the Company’s statements of operations and comprehensive loss were as follows (in thousands): Three Months Ended Six Months Ended June 30, June 30, 2023 2022 2023 2022 Operating lease costs $ 1,407 $ 1,471 $ 2,876 $ 2,925 Variable costs 900 1,005 1,839 1,688 Total lease costs $ 2,307 $ 2,476 $ 4,715 $ 4,613 Variable costs included in the table above represent amounts the Company pays related to property taxes, insurance, maintenance and repair costs. Cash paid for amounts included in the measurement of the Company’s operating lease liabilities and presented within cash used in operating activities in the statements of cash flows was $ 3.2 million and $ 3.4 million for the six months ended June 30, 2023 and 2022, respectively. Cash received for amounts related to tenant improvement allowances from lessors was $ 0.3 million and $ 1.0 million for the six months ended June 30, 2023 and 2022, respectively. Operating Lease Obligations Future lease payments required under operating leases included on the Company’s balance sheet at June 30, 2023 are as follows (in thousands): Fiscal Year Ending December 31, 2023 (remaining 6 months) $ 3,468 2024 7,075 2025 7,287 2026 7,506 2027 7,731 Thereafter 31,834 Total future lease payments 64,901 Less: Present value adjustment 22,522 Operating lease liabilities $ 42,379 Operating lease liabilities are based on the net present value of the remaining lease payments over the remaining lease term. In determining the present value of lease payments, the Company used its incremental borrowing rate based on the information available at the lease commencement date. As of June 30, 2023, the weighted-average remaining lease term of the Company’s leases was 8.3 years and the weighted-average discount rate used to determine the operating lease liabilities included on the balance sheet was 10.5 % . As of June 30, 2023 , the Company was not party to any lease agreements containing material residual value guarantees or material restrictive covenants.

Contingencies

Contingencies	6 Months Ended
	Jun. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
Contingencies	7. Contingencies In-Licensing Agreements The Company has entered into exclusive and non-exclusive, royalty bearing license agreements with third-parties for certain intellectual property. Under the terms of the license agreements, the Company is obligated to pay milestone payments upon the achievement of specified clinical, regulatory and commercial milestones. Research and development expense associated with the Company’s milestone payments are recognized when such milestone has been achieved. Actual amounts due under the license agreements will vary depending on factors including, but not limited to, the number of products developed and the Company’s ability to further develop and commercialize the licensed product. The Company is also subject to future royalty payments based on sales of the licensed products. The Company did no t recognize any milestone expense for the three and six months ended June 30, 2023 and 2022. As of June 30, 2023 , the Company has no t incurred any royalty liabilities related to its license agreements, as product sales have not yet commenced. Exclusive License Agreement with The Johns Hopkins University In December 2013, the Company entered into a license agreement with The Johns Hopkins University (“JHU”) for a worldwide exclusive license to develop, use, manufacture and commercialize covered product candidates including lirentelimab, which was amended in September 2016. Under the terms of the agreement, the Company has made upfront and milestone payments of $ 0.7 million through June 30, 2023 and may be required to make aggregate additional milestone payments of up to $ 1.8 million. The Company also issued 88,887 shares of common stock as consideration under the JHU license agreement. In addition to milestone payments, the Company is also subject to low single-digit royalties to JHU based on future net sales of each licensed therapeutic product candidate by the Company and its affiliates and sublicensees, with up to a low six-digit dollar minimum annual royalty payment. Non-exclusive License Agreement with BioWa Inc. and Lonza Sales AG In October 2013, the Company entered into a tripartite agreement with BioWa Inc. (“BioWa”), and Lonza Sales AG (“Lonza Sales”), for the non-exclusive worldwide license to develop and commercialize product candidates including lirentelimab that are manufactured using a technology jointly developed and owned by BioWa and Lonza Sales. Under the terms of the agreement, the Company has made milestone payments of $ 3.4 million through June 30, 2023 and may be required to make aggregate additional milestone payments of up to $ 38.0 million. In addition to milestone payments, the Company is also subject to minimum annual commercial license fees of $ 40,000 per year to BioWa until such time as BioWa receives royalty payments, as well as low single-digit royalties to BioWa and to Lonza Sales. Royalties are based on future net sales by the Company and its affiliates and sublicensees. Indemnification Agreements The Company has entered into indemnification agreements with certain directors and officers that require the Company, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors or officers. To date, no such matters have arisen and the Company does not believe that the outcome of any claims under indemnification arrangements will have a material adverse effect on its financial positions, results of operations or cash flows. Accordingly, the Company has no t recorded a liability related to such indemnifications at June 30, 2023 .

Stockholders' Equity

Stockholders' Equity	6 Months Ended
	Jun. 30, 2023
Stockholders' Equity Note [Abstract]
Stockholders' Equity	8. Stockholders ’ Equity September 2022 Offering On September 21, 2022, the Company closed an underwritten registered direct offering (the “September 2022 Offering”) under its shelf registration statement on Form S-3 (File No. 333-265085), supplemented by a prospectus supplement filed with the SEC on September 19, 2022 pursuant to Rule 424(b) under the Securities Act of 1933, as amended. In connection with the September 2022 Offering, the Company sold an aggregate of 29,882,000 shares of our common stock, par value $ 0.001 per share, at a public offering price of $ 5.02 per share. Aggregate net proceeds were approximately $ 140.6 million, after deducting the underwriting commissions and estimated offering expenses. “At-the-Market” Equity Offering On August 4, 2022, the Company entered into a sales agreement (the “2022 Sales Agreement”) with Cowen and Company, LLC (“Cowen”). Pursuant to Sales Agreement, the Company may sell, from time to time, up to an aggregate of $ 75.0 million in gross sales proceeds of its common stock through an “at-the-market” offering (“ATM Offering”) as defined under the Securities Act of 1933. The Company will pay a commission equal to 3 % of the gross proceeds from the sale of shares of its common stock under the Sales Agreement. The $ 75.0 million of common stock that may be offered, issued and sold in the ATM Offering is included in the $ 250.0 million of securities that may be offered, issued and sold by the Company under its registration statement on Form S-3 (File No. 333-265085). The Company expects to use the net proceeds from sales under the 2022 Sales Agreement for general corporate purposes. During the six months ended June 30, 2023 , the Company sold 0.1 million shares of its common stock at an average price of $ 7.20 per share through its ATM Offering, resulting in proceeds of $ 1.0 million net of commissions, with all sales occurring during the first quarter of 2023. Under its current ATM Offering program, $ 74.0 million of common stock remain available for future sales as of June 30, 2023 ; however, the Company is not obligated to make any sales under this program.

Stock-Based Compensation

Stock-Based Compensation	6 Months Ended
	Jun. 30, 2023
Share-Based Payment Arrangement [Abstract]
Stock-Based Compensation	9. Stock-Based Compensation Total stock-based compensation expense recognized is as follows (in thousands): Three Months Ended Six Months Ended June 30, June 30, 2023 2022 2023 2022 Research and development $ 4,088 $ 4,870 $ 8,763 $ 9,305 General and administrative 5,733 6,891 11,723 13,848 Total $ 9,821 $ 11,761 $ 20,486 $ 23,153 No income tax benefits for stock-based compensation expense have been recognized for the three and six months ended June 30, 2023 and 2022 as a result of the Company’s full valuation allowance applied to net deferred tax assets and net operating loss carryforwards. Equity Incentive Plans In July 2018, the Board of Directors adopted the 2018 Equity Incentive Plan (the “2018 Plan”). The 2018 Plan provides for the grant of incentive stock options, non-statutory stock options, restricted stock awards, restricted stock units (“RSUs”), stock appreciation rights, performance units and performance shares. The number of shares of common stock that may be issued under the 2018 Plan will automatically increase on each January 1, beginning with the fiscal year ending December 31, 2019, equal to the least of (i) 5,000,000 shares, (ii) 5 % of the outstanding shares of common stock as of the last day of the preceding fiscal year or (iii) such other amount as the Board of Directors may determine. Stock options and RSUs granted under the 2018 Plan generally vest over four years and expire no more than 10 years from the date of grant. Following the IPO and upon the effectiveness of the 2018 Plan, the Company’s 2012 Equity Incentive Plan, as amended, (the “2012 Plan”), terminated and no further awards will be granted thereunder. All outstanding awards under the 2012 Plan will continue to be governed by their existing terms. Any shares subject to awards granted under the 2012 Plan that, on or after the termination of the 2012 Plan, expire or terminate and shares previously issued pursuant to awards granted under the 2012 Plan that, on or after the termination of the 2012 Plan, are forfeited or repurchased by the Company will be transferred into the 2018 Plan. As of June 30, 2023, the maximum number of shares that may be added to the 2018 Plan pursuant to the preceding sentence is 2,684,997 shares. Prior to its termination, the 2012 Plan provided for the grant of stock options, stock appreciation rights, restricted stock and restricted stock units to employees, directors and consultants. Stock options granted under the 2012 Plan generally vest over four years and expire no more than 10 years from the date of grant. Stock Options The following weighted-average assumptions were used to calculate the fair value of stock options granted during the periods indicated: Three Months Ended Six Months Ended June 30, June 30, 2023 2022 2023 2022 Risk-free interest rate 3.81 % 2.76 % 3.69 % 2.61 % Expected volatility 97.24 % 73.61 % 96.20 % 73.48 % Expected dividend yield — — — — Expected term (in years) 5.73 5.66 5.99 5.73 The Company’s stock option activity during the six months ended June 30, 2023 is summarized as follows (number of shares in thousands): Weighted- Average Options Exercise Outstanding Price Balance at December 31, 2022 5,423 $ 15.41 Granted 2,343 $ 6.57 Exercised ( 6 ) $ 4.14 Expired ( 164 ) $ 52.69 Forfeited ( 380 ) $ 8.22 Balance at June 30, 2023 7,216 $ 12.08 Options exercisable 4,253 $ 13.60 Options vested and expected to vest 7,024 $ 12.17 As of June 30, 2023, total unrecognized stock-based compensation expense relating to unvested stock options was $ 18.0 million . This amount is expected to be recognized over a weighted-average period of 2.7 years. Time-based Restricted Stock Units (“RSU”) RSU activity under the 2018 Plan during the six months ended June 30, 2023 is summarized as follows (in thousands, except per share data): Weighted- Average Grant Date Shares Fair Value Balance at December 31, 2022 4,478 $ 16.90 Granted 3,170 $ 7.07 Vested ( 1,144 ) $ 15.67 Forfeited ( 906 ) $ 12.71 Balance at June 30, 2023 5,598 $ 12.26 The weighted-average fair value of RSUs granted during the six months ended June 30, 2023 and 2022 was $ 7.07 and $ 5.53 , respectively. As of June 30, 2023, total unrecognized stock-based compensation expense relating to unvested RSUs was $ 60.4 million and the weighted-average remaining vesting period was 2.5 years. Performance-based Restricted Stock Units (“PSUs”) PSU activity under the 2018 Plan during the six months ended June 30, 2023 is summarized as follows (in thousands, except per share data): Weighted- Average Grant Date Shares Fair Value Balance at December 31, 2022 3,276 $ 6.21 Forfeited ( 408 ) $ 5.58 Balance at June 30, 2023 2,868 $ 6.30 As of June 30, 2023, total unrecognized stock-based compensation expense relating to unvested PSUs was $ 18.1 million and the weighted-average remaining vesting period was 0.8 year. Employee Stock Purchase Plan In July 2018, the Company’s Board of Directors and stockholders approved the 2018 Employee Stock Purchase Plan (the “2018 ESPP”). The number of shares of common stock that may be issued under the 2018 ESPP shall automatically increase on each January 1, beginning with the fiscal year ending December 31, 2019, equal to the least of (i) 1,000,000 shares, (ii) 1 % of the outstanding shares of common stock as of the last day of the immediately preceding fiscal year and (iii) such other amount determined by the 2018 ESPP administrator. As of June 30, 2023, the number of shares available for issuance under the 2018 ESPP was 2,918,936 . Under the 2018 ESPP, employees may purchase shares of the Company’s common stock at a price per share equal to 85 % of the lower of the fair market value of the common stock on the first trading day of the offering period or on the exercise date. The 2018 ESPP provides for consecutive, overlapping 24 -month offering periods, each of which will include four 6-month purchase periods. The first offering period under the 2018 ESPP commenced on July 18, 2018 . During the three and six months ended June 30, 2023, stock-based compensation expense related to the 2018 ESPP was $ 0.1 million and $ 0.4 million , respectively. During the three and six months ended June 30, 2022 , stock-based compensation expense related to the 2018 ESPP was $ 0.3 million and $ 0.5 million, respectively.

Defined Contribution Plans

Defined Contribution Plans	6 Months Ended
	Jun. 30, 2023
Retirement Benefits [Abstract]
Defined Contribution Plans	10. Defined Contribution Plans In January 2018, the Company established a defined contribution plan under Section 401(k) of the Internal Revenue Code (the “401(k) plan”). The 401(k) plan covers all employees who meet defined minimum age and service requirements. Employee contributions are voluntary and are determined on an individual basis, limited to the maximum amount allowable under U.S. federal tax regulations. The Company makes matching contributions of up to 4 % of the eligible employees’ compensation to the 401(k) plan. During the three and six months ended June 30, 2023, the Company made contributions to the 401(k) plan of $ 0.2 million and $ 0.6 million , respectively. During the three and six months ended June 30, 2022, the Company made contributions to the 401(k) plan of $ 0.2 million and $ 0.7 million , respectively.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2023
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The unaudited interim financial statements have been prepared in accordance with United States generally accepted accounting principles (“U.S. GAAP”). The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts and disclosures reported in the financial statements and accompanying notes. The interim balance sheet as of June 30, 2023, the statements of operations and comprehensive loss, statements of stockholders’ equity for the three and six months ended June 30, 2023 and 2022 and statements of cash flows for the six months ended June 30, 2023 and 2022 are unaudited. The unaudited interim financial statements have been prepared on the same basis as the audited annual financial statements and reflect, in the opinion of management, all adjustments of a normal and recurring nature that are necessary for the fair presentation of the Company’s financial position as of June 30, 2023 and its results of operations and comprehensive loss for the three and six months ended June 30, 2023 and 2022 and its cash flows for the six months ended June 30, 2023 and 2022. Certain information and note disclosures normally included in annual audited financial statements prepared in accordance with U.S. GAAP have been omitted. The financial data and the other financial information disclosed in these notes to the interim financial statements are also unaudited. The results of operations for any interim period are not necessarily indicative of the results to be expected for the entire year or for any other future annual or interim period. These interim financial statements should be read in conjunction with the Company’s audited financial statements included in the Company’s Annual Report on Form 10-K, which was filed with the SEC on March 6, 2023.
Use of Estimates	Use of Estimates Management uses significant judgment when making estimates related to common stock valuation and related stock-based compensation expense, accrued research and development expense, and lease-related assets and liabilities. Management bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results could differ from those estimates under different assumptions or conditions, and those differences could be material to the financial position and results of operations.
Concentration of Credit Risk and Other Risks and Uncertainties	Concentration of Credit Risk and Other Risks and Uncertainties Financial instruments that potentially subject the Company to credit risk principally consist of cash, cash equivalents and investments. These financial instruments are currently held in accounts in varying amounts at four separate financial institutions that management believes possesses high credit quality. Amounts on deposit with these financial institutions have and will continue to exceed federally-insured limits. The Company has not experienced any losses on its cash deposits. Additionally, the Company’s investment policy limits its investments to certain types of securities issued by or backed by the U.S. government and its agencies. The Company is subject to a number of risks similar to that of other early stage biopharmaceutical companies, including, but not limited to, the need to obtain adequate additional funding, possible failure of current or future clinical trials, its reliance on third-parties to conduct its clinical trials, the need to obtain regulatory and marketing approvals for its product candidates, competitive developments, the need to successfully commercialize and gain market acceptance of the Company’s product candidates, its right to develop and commercialize its product candidates pursuant to the terms and conditions of the licenses granted to the Company, protection of proprietary technology, the ability to make milestone, royalty or other payments due under licensing agreements, and the need to secure and maintain adequate manufacturing arrangements with third-parties. If the Company does not successfully commercialize or partner its product candidates, it will be unable to generate product revenue or achieve profitability.
Cash, Cash Equivalents and Restricted Cash	Cash, Cash Equivalents and Restricted Cash The Company considers all highly liquid investments with original maturities of three months or less from the date of purchase to be cash equivalents. The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the Company’s balance sheets and which, in aggregate, represent the amounts reported in the accompanying statements of cash flows (in thousands): June 30, December 31, 2023 2022 Cash and cash equivalents $ 67,381 $ 87,217 Restricted cash in other long-term assets 1,472 1,472 Total $ 68,853 $ 88,689 June 30, December 31, 2022 2021 Cash and cash equivalents $ 82,452 $ 152,822 Restricted cash in other long-term assets 1,472 2,275 Total $ 83,924 $ 155,097 Restricted cash at June 30, 2023 represents $ 1.5 million in security deposits for the lease of the Company’s facility in San Carlos, California. The security deposit is in the form of a letter of credit secured by restricted cash and is recorded in other long-term assets on the Company’s balance sheets
Investments	Investments The Company invests in marketable securities, primarily securities issued by the United States government and its agencies. The Company’s investments are considered available-for-sale and are classified as current assets even when the stated maturities of the underlying securities exceed one year from the date of the current balance sheet being reported. This classification reflects management’s ability and intent to utilize proceeds from the sale of such investments to fund ongoing operations. Unrealized gains and losses are excluded from earnings and are reported as a component of accumulated other comprehensive gain (loss). The cost of securities sold is determined using the specific-identification method. Interest earned and adjustments for the amortization of premiums and discounts on investments are included in interest income on the statements of operations and comprehensive loss. Realized gains and losses and declines in fair value judged to be other than temporary, if any, on investments in marketable securities are included in other expense, net, on the statements of operations and comprehensive loss.
Operating Leases	Operating Leases The Company accounts for its leases in accordance with Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 842, “Leases” (“ASC 842”). Right-of-use assets represent the Company’s right to use an underlying asset over the lease term and include any lease payments made prior to the lease commencement date and are reduced by lease incentives. Lease liabilities represent the present value of the total lease payments over the lease term, calculated using the Company’s incremental borrowing rate. In determining the Company’s incremental borrowing rate, consideration is given to the term of the lease and the Company’s credit risk. The Company recognizes options to extend a lease when it is reasonably certain that it will exercise such extension. The Company does not recognize options to terminate a lease when it is reasonably certain that it will not exercise such early termination options. Lease expense is recognized on a straight-line basis over the expected lease term.
Accrued Research and Development Expense	Accrued Research and Development Expense Service agreements with contract development and manufacturing organizations (“CDMOs”), clinical contract research organizations (“CROs”) and clinical investigative sites comprise a significant component of the Company’s research and development activities. External costs for these vendors are recognized as the services are incurred. The Company accrues for expenses resulting from obligations under agreements with its third-parties for which the timing of payments does not match the periods over which the materials or services are provided to the Company. Accruals are recorded based on estimates of services received and efforts expended pursuant to agreements established with CDMOs, clinical CROs, clinical investigative sites and other outside service providers. These estimates are typically based on contracted amounts applied to the proportion of work performed and determined through analysis with internal personnel and external service providers as to the progress or stage of completion of the services. The Company makes judgements and estimates in determining the accrual balance in each reporting period. In the event advance payments are made to a CDMO, clinical CRO, clinical investigative site or other outside service provider, the payments are recorded within prepaid expenses and other current assets or other long-term assets, as appropriate, and subsequently recognized as research and development expense when the associated services have been performed. As actual costs become known, the Company adjusts its liabilities and assets. Inputs, such as the extent of services received and the duration of services to be performed, may vary from the Company’s estimates, which will result in adjustments to research and development expense in future periods. Changes in these estimates that result in material changes to the Company’s accruals could materially affect the Company’s results of operations. The Company’s historical estimates have not been materially different from actual amounts recorded.
Research and Development Expense	Research and Development Expense Research and development costs are expensed as incurred. Research and development costs include, among others, consulting costs, salaries, benefits, travel, stock-based compensation, laboratory supplies and other non-capital equipment utilized for in-house research, allocation of facilities and overhead costs and external costs paid to third-parties that conduct research and development activities on the Company’s behalf. Costs to terminate commitments with third-party suppliers performing research and development activities and amounts incurred in connection with license agreements, including milestone payments, are also included in research and development expense. Advance payments for goods or services to be rendered in the future for use in research and development activities are deferred and included in prepaid expenses and other current assets or other long-term assets, as appropriate. The deferred amounts are expensed as the related goods are delivered or the services are performed.
Comprehensive Loss	Comprehensive Loss Comprehensive loss is defined as the change in stockholders’ equity during a period from transactions and other events and circumstances from non-owner sources. The differences between net loss and comprehensive loss for the three and six months ended June 30, 2023 and 2022 are a result of unrealized gains and losses on the Company’s investments included in current assets on the Company’s balance sheets.
Net Loss per Share	Net Loss per Share The Company calculates basic net loss per share by dividing the net loss attributable to common stockholders by the weighted-average shares of common stock outstanding during the period. The Company calculates diluted net loss per share after giving consideration to all potentially dilutive securities outstanding during the period using the treasury-stock and if-converted methods, except where the effect of including such securities would be anti-dilutive. Because the Company has reported net losses since inception, the effect from potentially dilutive securities would have been anti-dilutive and therefore has been excluded from the calculation of diluted net loss per share. The Company’s weighted-average shares of common stock outstanding increased from 54.8 million shares during the second quarter of 2022 to a weighted-average of 86.6 million during the second quarter of 2023 and from 54.7 million shares to 86.2 million shares during the six months ended June 30, 2022 and June 30, 2023, respectively, primarily as a result of the 29.9 million shares sold as part of an underwritten registered direct offering closed on September 21, 2022 (the “September 2022 Offering”). Refer to Note 8 “Stockholders’ Equity” for additional details related to the offering. Basic and diluted net loss per share was calculated as follows (in thousands, except per share data): Three Months Ended Six Months Ended June 30, June 30, 2023 2022 2023 2022 Numerator: Net loss $ ( 35,120 ) $ ( 49,103 ) $ ( 77,524 ) $ ( 246,126 ) Denominator: Weighted-average shares of common stock outstanding, 86,646 54,798 86,246 54,742 Net loss per share, basic and diluted $ ( 0.41 ) $ ( 0.90 ) $ ( 0.90 ) $ ( 4.50 ) The following table sets forth the potentially dilutive securities that have been excluded from the calculation of diluted net loss per share due to their anti-dilutive effect for the periods indicated (in thousands): Six Months Ended June 30, 2023 2022 Options to purchase common stock 7,216 5,543 Unvested restricted stock units 5,598 4,839 Unvested performance stock units 2,868 3,809 Shares issuable under employee stock purchase plans 123 67 Total 15,805 14,258
Recently Issued and Adopted Accounting Pronouncements	Recently Issued and Adopted Accounting Pronouncements The Company has reviewed recently issued accounting pronouncements and concluded they are either not applicable to the business or that no material effect is expected on the Company’s financial statements as a result of future adoption.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	6 Months Ended
	Jun. 30, 2023
Accounting Policies [Abstract]
Reconciliation of Cash, Cash Equivalents and Restricted Cash	The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the Company’s balance sheets and which, in aggregate, represent the amounts reported in the accompanying statements of cash flows (in thousands): June 30, December 31, 2023 2022 Cash and cash equivalents $ 67,381 $ 87,217 Restricted cash in other long-term assets 1,472 1,472 Total $ 68,853 $ 88,689 June 30, December 31, 2022 2021 Cash and cash equivalents $ 82,452 $ 152,822 Restricted cash in other long-term assets 1,472 2,275 Total $ 83,924 $ 155,097
Calculation of Basic and Diluted Net Loss per Share	Basic and diluted net loss per share was calculated as follows (in thousands, except per share data): Three Months Ended Six Months Ended June 30, June 30, 2023 2022 2023 2022 Numerator: Net loss $ ( 35,120 ) $ ( 49,103 ) $ ( 77,524 ) $ ( 246,126 ) Denominator: Weighted-average shares of common stock outstanding, 86,646 54,798 86,246 54,742 Net loss per share, basic and diluted $ ( 0.41 ) $ ( 0.90 ) $ ( 0.90 ) $ ( 4.50 )
Summary of Potentially Dilutive Securities Excluded from Calculation of Diluted Net Loss Per Share	The following table sets forth the potentially dilutive securities that have been excluded from the calculation of diluted net loss per share due to their anti-dilutive effect for the periods indicated (in thousands): Six Months Ended June 30, 2023 2022 Options to purchase common stock 7,216 5,543 Unvested restricted stock units 5,598 4,839 Unvested performance stock units 2,868 3,809 Shares issuable under employee stock purchase plans 123 67 Total 15,805 14,258

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2023
Fair Value Disclosures [Abstract]
Summary of Financial Assets Measured at Fair Value on Recurring Basis	The Company’s financial assets measured at fair value on a recurring basis were as follows (in thousands): June 30, 2023 Level 1 Level 2 Level 3 Total Cash equivalents: Money market funds $ 66,754 $ — $ — $ 66,754 Total cash equivalents 66,754 — — 66,754 Short-term marketable securities U.S. treasuries 153,721 — — 153,721 Total short-term marketable securities 153,721 — — 153,721 Total cash equivalents and short-term $ 220,475 $ — $ — $ 220,475 December 31, 2022 Level 1 Level 2 Level 3 Total Cash equivalents: Money market funds $ 86,270 $ — $ — $ 86,270 Total cash equivalents 86,270 — — 86,270 Short-term marketable securities: U.S. treasuries 192,569 — — 192,569 Total short-term marketable securities 192,569 — — 192,569 Total cash equivalents and short-term $ 278,839 $ — $ — $ 278,839

Investments (Tables)

Investments (Tables)	6 Months Ended
	Jun. 30, 2023
Investments, Debt and Equity Securities [Abstract]
Summary of Amortized Cost, Gross Unrealized Holding Gains or Losses, and Fair Value of Investments	All investments were considered available-for-sale at June 30, 2023. The amortized cost, gross unrealized holding gains or losses, and fair value of the Company’s investments by major security type at June 30, 2023 and December 31, 2022 are summarized in the table below (in thousands): June 30, 2023 Amortized Unrealized Unrealized Fair Available-for-sale securities: U.S. treasuries classified as investments $ 153,880 $ 10 $ ( 169 ) $ 153,721 Total available-for-sale securities $ 153,880 $ 10 $ ( 169 ) $ 153,721 December 31, 2022 Amortized Unrealized Unrealized Fair Available-for-sale securities: U.S. treasuries classified as investments $ 192,853 $ 3 $ ( 287 ) $ 192,569 Total available-for-sale securities $ 192,853 $ 3 $ ( 287 ) $ 192,569

Balance Sheet Components and _2

Balance Sheet Components and Supplemental Disclosures (Tables)	6 Months Ended
	Jun. 30, 2023
Balance Sheet Related Disclosures [Abstract]
Schedule of Property and Equipment, Net	Property and equipment, net, consisted of the following (in thousands): June 30, December 31, 2023 2022 Laboratory equipment $ 6,985 $ 6,473 Furniture and office equipment 3,946 3,947 Leasehold improvements 32,457 32,457 Capitalized software 4,186 4,112 Construction-in-progress 182 422 47,756 47,411 Less accumulated depreciation ( 11,310 ) ( 8,267 ) Property and equipment, net $ 36,446 $ 39,144
Schedule of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consisted of the following (in thousands): June 30, December 31, 2023 2022 Accrued contract research and development expense $ 11,990 $ 13,950 Accrued compensation and benefits expense 4,615 7,039 Current portion of operating lease liabilities 2,645 3,161 Other current liabilities 927 1,056 Total $ 20,177 $ 25,206

Leases (Tables)

Leases (Tables)	6 Months Ended
	Jun. 30, 2023
Leases [Abstract]
Summary of Classification of Company's Operating Lease Liabilities	Classification of the Company’s operating lease liabilities included on the Company’s balance sheets at June 30, 2023 and December 31, 2022 was as follows (in thousands): June 30, December 31, 2023 2022 Operating lease liabilities Current portion included in accrued expenses and $ 2,645 $ 3,161 Operating lease liabilities, net of current portion 39,734 45,949 Total operating lease liabilities $ 42,379 $ 49,110
Summary of Components of Lease Costs	The components of lease costs included in operating expenses in the Company’s statements of operations and comprehensive loss were as follows (in thousands): Three Months Ended Six Months Ended June 30, June 30, 2023 2022 2023 2022 Operating lease costs $ 1,407 $ 1,471 $ 2,876 $ 2,925 Variable costs 900 1,005 1,839 1,688 Total lease costs $ 2,307 $ 2,476 $ 4,715 $ 4,613
Summary of Future Lease Payments Required Under Operating Leases	Future lease payments required under operating leases included on the Company’s balance sheet at June 30, 2023 are as follows (in thousands): Fiscal Year Ending December 31, 2023 (remaining 6 months) $ 3,468 2024 7,075 2025 7,287 2026 7,506 2027 7,731 Thereafter 31,834 Total future lease payments 64,901 Less: Present value adjustment 22,522 Operating lease liabilities $ 42,379

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	6 Months Ended
	Jun. 30, 2023
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Summary of Total Stock-Based Compensation Expense Recognized	Total stock-based compensation expense recognized is as follows (in thousands): Three Months Ended Six Months Ended June 30, June 30, 2023 2022 2023 2022 Research and development $ 4,088 $ 4,870 $ 8,763 $ 9,305 General and administrative 5,733 6,891 11,723 13,848 Total $ 9,821 $ 11,761 $ 20,486 $ 23,153
Summary of Weighted-Average Assumptions Used to Calculate Fair Value of Stock Options Granted	The following weighted-average assumptions were used to calculate the fair value of stock options granted during the periods indicated: Three Months Ended Six Months Ended June 30, June 30, 2023 2022 2023 2022 Risk-free interest rate 3.81 % 2.76 % 3.69 % 2.61 % Expected volatility 97.24 % 73.61 % 96.20 % 73.48 % Expected dividend yield — — — — Expected term (in years) 5.73 5.66 5.99 5.73
Summary of Stock Option Activity	The Company’s stock option activity during the six months ended June 30, 2023 is summarized as follows (number of shares in thousands): Weighted- Average Options Exercise Outstanding Price Balance at December 31, 2022 5,423 $ 15.41 Granted 2,343 $ 6.57 Exercised ( 6 ) $ 4.14 Expired ( 164 ) $ 52.69 Forfeited ( 380 ) $ 8.22 Balance at June 30, 2023 7,216 $ 12.08 Options exercisable 4,253 $ 13.60 Options vested and expected to vest 7,024 $ 12.17
Time-based Restricted Stock Units ("RSU")
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Summary of Restricted Stock Units	RSU activity under the 2018 Plan during the six months ended June 30, 2023 is summarized as follows (in thousands, except per share data): Weighted- Average Grant Date Shares Fair Value Balance at December 31, 2022 4,478 $ 16.90 Granted 3,170 $ 7.07 Vested ( 1,144 ) $ 15.67 Forfeited ( 906 ) $ 12.71 Balance at June 30, 2023 5,598 $ 12.26
Performance-based Restricted Stock Units ("PSU")
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Summary of Restricted Stock Units	PSU activity under the 2018 Plan during the six months ended June 30, 2023 is summarized as follows (in thousands, except per share data): Weighted- Average Grant Date Shares Fair Value Balance at December 31, 2022 3,276 $ 6.21 Forfeited ( 408 ) $ 5.58 Balance at June 30, 2023 2,868 $ 6.30

Organization and Business - Add

Organization and Business - Additional Information (Details) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2023 USD ($)	Mar. 31, 2023 USD ($)	Jun. 30, 2022 USD ($)	Mar. 31, 2022 USD ($)	Jun. 30, 2023 USD ($) Segment	Jun. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of reportable segments | Segment					1
Net loss	$ 35,120	$ 42,404	$ 49,103	$ 197,023	$ 77,524	$ 246,126
Accumulated deficit	1,010,300				1,010,300		$ 932,776
Cash, cash equivalents and marketable securities	$ 221,100				$ 221,100

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Reconciliation of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022	Dec. 31, 2021
Cash and Cash Equivalents [Abstract]
Cash and cash equivalents	$ 67,381	$ 87,217	$ 82,452	$ 152,822
Restricted cash in other long-term assets	1,472	1,472	1,472	2,275
Total	$ 68,853	$ 88,689	$ 83,924	$ 155,097

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Additional Information (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2023	Sep. 30, 2022	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021
Restricted cash in other long term assets, deposit for lease facility	$ 1,472		$ 1,472	$ 1,472	$ 1,472	$ 1,472	$ 2,275
Weighted-average shares of common stock outstanding, diluted	86,646		54,798	86,246	54,742
Registered Direct Offering
Sale of shares of common stock		29,900

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Calculation of Basic and Diluted Net Loss per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2023	Jun. 30, 2022
Numerator:
Net loss	$ (35,120)	$ (42,404)	$ (49,103)	$ (197,023)	$ (77,524)	$ (246,126)
Denominator:
Weighted-average shares of common stock outstanding, basic	86,646		54,798		86,246	54,742
Weighted-average shares of common stock outstanding, diluted	86,646		54,798		86,246	54,742
Net loss per share, basic	$ (0.41)		$ (0.9)		$ (0.9)	$ (4.5)
Net loss per share, diluted	$ (0.41)		$ (0.9)		$ (0.9)	$ (4.5)

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Summary of Potentially Dilutive Securities Excluded from Calculation of Diluted Net Loss per Share (Details) - shares shares in Thousands	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from calculation of diluted net loss per share due to anti-dilutive effect	15,805	14,258
Options to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from calculation of diluted net loss per share due to anti-dilutive effect	7,216	5,543
Unvested Restricted Stock Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from calculation of diluted net loss per share due to anti-dilutive effect	5,598	4,839
Unvested Performance Stock Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from calculation of diluted net loss per share due to anti-dilutive effect	2,868	3,809
Shares Issuable under Employee Stock Purchase Plans
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from calculation of diluted net loss per share due to anti-dilutive effect	123	67

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Financial Assets Measured at Fair Value on Recurring Basis (Details) - USD ($)	Jun. 30, 2023	Dec. 31, 2022
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term marketable securities	$ 153,721,000	$ 192,569,000
Fair Value, Measurements, Recurring Basis
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	66,754,000	86,270,000
Short-term marketable securities	153,721,000	192,569,000
Total cash equivalents and short-term marketable securities	220,475,000	278,839,000
Fair Value, Measurements, Recurring Basis | Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	66,754,000	86,270,000
Short-term marketable securities	153,721,000	192,569,000
Total cash equivalents and short-term marketable securities	220,475,000	278,839,000
Fair Value, Measurements, Recurring Basis | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Short-term marketable securities	0	0
Total cash equivalents and short-term marketable securities	0	0
Fair Value, Measurements, Recurring Basis | Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Short-term marketable securities	0	0
Total cash equivalents and short-term marketable securities	0	0
Fair Value, Measurements, Recurring Basis | Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	66,754,000	86,270,000
Fair Value, Measurements, Recurring Basis | Money Market Funds | Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	66,754,000	86,270,000
Fair Value, Measurements, Recurring Basis | Money Market Funds | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Fair Value, Measurements, Recurring Basis | Money Market Funds | Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Fair Value, Measurements, Recurring Basis | U.S. Treasuries
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term marketable securities	153,721,000	192,569,000
Fair Value, Measurements, Recurring Basis | U.S. Treasuries | Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term marketable securities	153,721,000	192,569,000
Fair Value, Measurements, Recurring Basis | U.S. Treasuries | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term marketable securities	0	0
Fair Value, Measurements, Recurring Basis | U.S. Treasuries | Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term marketable securities	$ 0	$ 0

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Fair Value Disclosures [Abstract]
Transfers of assets between level 1 to level 2	$ 0	$ 0	$ 0	$ 0
Transfers of assets between level 2 to level 1	0	0	0	0
Transfers of liabilities between level 1 to level 2	0	0	0	0
Transfers of liabilities between level 2 to level 1	$ 0	$ 0	0	0
Transfers of assets into level 3			0	0
Transfers of assets out of level 3			0	0
Transfers of liabilities into level 3			0	0
Transfers of liabilities out of level 3			$ 0	$ 0

Investments - Summary of Amorti

Investments - Summary of Amortized Cost, Gross Unrealized Holding Gains or Losses, and Fair Value of Marketable Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost Basis	$ 153,880	$ 192,853
Unrealized Gains	10	3
Unrealized Losses	(169)	(287)
Fair Value	153,721	192,569
Investments | U.S. Treasuries
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost Basis	153,880	192,853
Unrealized Gains	10	3
Unrealized Losses	(169)	(287)
Fair Value	$ 153,721	$ 192,569

Investments - Additional Inform

Investments - Additional Information (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale securities in an unrealized loss position, fair value	$ 145,900,000		$ 145,900,000		$ 162,600,000
Available-for-sale securities gross recognized losses on sale or maturity	$ 0	$ 0	$ 0	$ 0
Maximum
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale securities, remaining maturity period	1 year		1 year		1 year

Balance Sheet Components and _3

Balance Sheet Components and Supplemental Disclosures - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 47,756	$ 47,411
Less accumulated depreciation	(11,310)	(8,267)
Property and equipment, net	36,446	39,144
Laboratory Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	6,985	6,473
Furniture And Office Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	3,946	3,947
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	32,457	32,457
Capitalized Software
Property Plant And Equipment [Line Items]
Property and equipment, gross	4,186	4,112
Construction In Progress
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 182	$ 422

Balance Sheet Components and _4

Balance Sheet Components and Supplemental Disclosures - Schedule of Other Long-Term Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Balance Sheet Related Disclosures [Line Items]
Other long-term assets , Total	$ 6,699	$ 8,208

Balance Sheet Components and _5

Balance Sheet Components and Supplemental Disclosures - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Balance Sheet Related Disclosures [Line Items]
Depreciation and amortization	$ 1,500	$ 1,900	$ 3,045	$ 4,064

Balance Sheet Components and _6

Balance Sheet Components and Supplemental Disclosures - Schedule of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Payables and Accruals [Abstract]
Accrued contract research and development expense	$ 11,990	$ 13,950
Accrued compensation and benefits expense	4,615	7,039
Current portion of operating lease liabilities	2,645	3,161
Other current liabilities	927	1,056
Total	$ 20,177	$ 25,206

Leases - Additional Information

Leases - Additional Information (Details) $ in Thousands	1 Months Ended	6 Months Ended
	Dec. 31, 2019 USD ($)	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Mar. 27, 2023 USD ($) ft²	Dec. 31, 2022 USD ($)
Lessee, Lease, Description [Line Items]
Remaining lease liability		$ 39,734			$ 45,949
Remaining right-of-use assets		24,489			30,225
Cash paid for amounts included in measurement of operating lease liabilities		3,200	$ 3,400
Cash received for amounts related to tenant improvement allowances from lessors		$ 300	$ 1,000
Operating lease, weighted-average remaining lease term		8 years 3 months 18 days
Operating lease, weighted-average discount rate		10.50%
2019 San Carlos Lease Agreement
Lessee, Lease, Description [Line Items]
Operating lease agreement initiation period	2019-12
Base term of lease	10 years 3 months
Lessee operating lease expected termination Period	2031-10
Lease term extension period	5 years
Area of lease | ft²				95,692
Percentage of lease payments reduced				2.50%
Incremental borrowing rate				10.50%
Right of use asset and lease liability decreased				$ 5,600
Security deposit in the form of letter of credit secured by restricted cash		$ 1,500			$ 1,500
2019 San Carlos Lease Agreement | Maximum
Lessee, Lease, Description [Line Items]
Tenant improvement allowance	$ 14,700

Leases - Summary of Classificat

Leases - Summary of Classification of Company's Operating Lease Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Operating lease liabilities
Current portion included in accrued expenses and other current liabilities	$ 2,645	$ 3,161
Operating lease liabilities, net of current portion	39,734	45,949
Total operating lease liabilities	$ 42,379	$ 49,110

Leases - Summary of Components

Leases - Summary of Components of Lease Costs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Leases [Abstract]
Operating lease cost	$ 1,407	$ 1,471	$ 2,876	$ 2,925
Variable cost	900	1,005	1,839	1,688
Total lease costs	$ 2,307	$ 2,476	$ 4,715	$ 4,613

Leases - Summary of Future Leas

Leases - Summary of Future Lease Payments Required Under Operating Leases (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Lessee, Operating Lease, Liability, to be Paid, Fiscal Year Maturity [Abstract]
2023 (remaining 6 months)	$ 3,468
2024	7,075
2025	7,287
2026	7,506
2027	7,731
Thereafter	31,834
Total future lease payments	64,901
Present value adjustment	22,522
Operating lease liabilities	$ 42,379	$ 49,110

Contingencies - Additional Info

Contingencies - Additional Information (Details) - USD ($)	3 Months Ended		6 Months Ended		115 Months Ended	117 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2023	Dec. 31, 2022
Loss Contingencies [Line Items]
Accrued Royalties	$ 0		$ 0		$ 0	$ 0
Common stock, shares issued	86,823,000		86,823,000		86,823,000	86,823,000	85,387,000
In-Licensing Agreements
Loss Contingencies [Line Items]
Milestone expense	$ 0	$ 0	$ 0	$ 0
Exclusive License Agreement with The Johns Hopkins University
Loss Contingencies [Line Items]
Upfront and milestone payments					$ 700,000
Common stock, shares issued	88,887		88,887		88,887	88,887
Non-exclusive License Agreement with BioWa Inc. and Lonza Sales AG
Loss Contingencies [Line Items]
Milestone payments						$ 3,400,000
Indemnification Agreements [Member]
Loss Contingencies [Line Items]
Liability related to indemnifications	$ 0		$ 0		$ 0	0
Minimum | Non-exclusive License Agreement with BioWa Inc. and Lonza Sales AG
Loss Contingencies [Line Items]
Annual commercial license fees						40,000
Maximum | Exclusive License Agreement with The Johns Hopkins University
Loss Contingencies [Line Items]
Aggregate additional milestone payments	1,800,000		1,800,000		1,800,000	1,800,000
Maximum | Non-exclusive License Agreement with BioWa Inc. and Lonza Sales AG
Loss Contingencies [Line Items]
Aggregate additional milestone payments	$ 38,000,000		$ 38,000,000		$ 38,000,000	$ 38,000,000

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands			6 Months Ended
	Sep. 21, 2022	Aug. 04, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Class of Stock [Line Items]
Common stock, par value			$ 0.001		$ 0.001
Aggregate net proceeds			$ 990	$ 0
Common stock sold (in Shares)			100,000
September 2022 Offering
Class of Stock [Line Items]
Sale of shares of common stock	29,882,000
Common stock, par value	$ 0.001
Sale of stock, average price per share	$ 5.02
Aggregate net proceeds	$ 140,600
At-the-Market Equity Offering
Class of Stock [Line Items]
Sale of stock, average price per share			$ 7.2
Aggregate amount available to be sold under sales agreement		$ 75,000
Commission rate		3%
Amount of securities offered under S-3 registartion statement		$ 250,000
Proceeds from sale of common stock, net of commission			$ 1,000
Common stock available for sale			$ 74,000

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Total Stock-Based Compensation Expense Recognized (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 9,821	$ 11,761	$ 20,486	$ 23,153
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	4,088	4,870	8,763	9,305
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 5,733	$ 6,891	$ 11,723	$ 13,848

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) - USD ($)	1 Months Ended	3 Months Ended		6 Months Ended
	Jul. 31, 2018	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Tax benefits for stock-based compensation expense recognized		$ 0	$ 0	$ 0	$ 0
Stock options granted				2,343,000
Total unrecognized stock-based compensation expense relating to unvested stock options		18,000,000		$ 18,000,000
Weighted-average recognition period				2 years 8 months 12 days
Total stock-based compensation expense		9,821,000	11,761,000	$ 20,486,000	$ 23,153,000
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average recognition period				2 years 6 months
Weighted-average fair value granted				$ 7.07	$ 5.53
Total unrecognized stock-based compensation expense		$ 60,400,000		$ 60,400,000
2018 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Increase in number of common stock shares reserved for issuance per year	1,000,000
Percentage increase in shares reserved for issuance per year	1%
Price as a percentage of fair market value of common stock	85%
Consecutive overlapping offering period	24 months
Number of shares available for issuance		2,918,936		2,918,936
First offering period commence date	Jul. 18, 2018
Total stock-based compensation expense		$ 100,000	$ 300,000	$ 400,000	$ 500,000
Performance-based Restricted Stock Units ("PSU")
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average recognition period				9 months 18 days
Total unrecognized stock-based compensation expense		$ 18,100,000		$ 18,100,000
2018 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Increase in number of common stock shares reserved for issuance per year	5,000,000
Percentage increase in shares reserved for issuance per year	5%
Vesting period	4 years
2018 Equity Incentive Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Option expiration period	10 years
2012 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period	4 years
Maximum number of additional shares authorized to be added to the Plan				2,684,997
2012 Equity Incentive Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Option expiration period	10 years

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of Weighted-Average Assumptions Used to Calculate Fair Value of Stock Options Granted (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate	3.81%	2.76%	3.69%	2.61%
Expected volatility	97.24%	73.61%	96.20%	73.48%
Expected dividend yield	0%	0%	0%	0%
Expected term (in years)	5 years 8 months 23 days	5 years 7 months 28 days	5 years 11 months 26 days	5 years 8 months 23 days

Stock-Based Compensation - Su_3

Stock-Based Compensation - Summary of Stock Option Activity (Details) shares in Thousands	6 Months Ended
	Jun. 30, 2023 $ / shares shares
Share-Based Payment Arrangement [Abstract]
Options Outstanding, Beginning balance | shares	5,423
Options Outstanding, Granted | shares	2,343
Options Outstanding, Exercised | shares	(6)
Options outstanding, Expired | shares	(164)
Options Outstanding, forfeited | shares	(380)
Options Outstanding, Ending balance | shares	7,216
Options Outstanding, Options exercisable | shares	4,253
Options Outstanding, Options vested and expected to vest | shares	7,024
Weighted Average Exercise Price, Beginning balance | $ / shares	$ 15.41
Weighted Average Exercise Price, Granted | $ / shares	6.57
Weighted Average Exercise Price, Exercised | $ / shares	4.14
Weighted Average Exercise Price, Expired | $ / shares	52.69
Weighted Average Exercise Price, Forfeited | $ / shares	8.22
Weighted Average Exercise Price, Ending balance | $ / shares	12.08
Weighted Average Exercise Price, Options exercisable | $ / shares	13.6
Weighted Average Exercise Price, Options vested and expected to vest | $ / shares	$ 12.17

Stock-Based Compensation - Su_4

Stock-Based Compensation - Summary of RSU Activity Under 2018 Plan (Details) - $ / shares shares in Thousands	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Restricted Stock Units
Number of Shares
Balance at December 31, 2022	4,478
Granted	3,170
Vested	(1,144)
Forfeited	(906)
Balance at June 30, 2023	5,598
Weighted-Average Grant Date Fair Value
Balance at December 31, 2021	$ 16.9
Granted	7.07	$ 5.53
Vested	15.67
Forfeited	12.71
Balance at June 30, 2023	$ 12.26
Performance-based Restricted Stock Units ("PSU")
Number of Shares
Balance at December 31, 2022	3,276
Forfeited	(408)
Balance at June 30, 2023	2,868
Weighted-Average Grant Date Fair Value
Balance at December 31, 2021	$ 6.21
Forfeited	5.58
Balance at June 30, 2023	$ 6.3

Defined Contribution Plans - Ad

Defined Contribution Plans - Additional Information (Details) - 401(K) Plan - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Defined Contribution Plan Disclosure [Line Items]
Employer contribution matching percentage			4%	4%
Contributions made by employer	$ 0.2	$ 0.2	$ 0.6	$ 0.7