Bolt Biotherapeutics (BOLT) 10-Q 13 Aug 24 2024 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2024	Aug. 07, 2024
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2024
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q2
Entity Registrant Name	Bolt Biotherapeutics, Inc.
Entity Central Index Key	0001641281
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		38,264,843
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Title of 12(b) Security	Common Stock, $0.00001 par value
Trading Symbol	BOLT
Security Exchange Name	NASDAQ
Entity File Number	001-39988
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	47-2804636
Entity Address, Address Line One	900 Chesapeake
Entity Address, Address Line Two	Drive
Entity Address, City or Town	Redwood City
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94063
City Area Code	650
Local Phone Number	665-9295
Document Quarterly Report	true
Document Transition Report	false

CONDENSED BALANCE SHEETS (Unaud

CONDENSED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 6,202	$ 10,810
Short-term investments	67,495	91,379
Prepaid expenses and other current assets	2,934	3,519
Total current assets	76,631	105,708
Property and equipment, net	4,079	4,957
Operating lease right-of-use assets	17,559	19,120
Restricted cash	1,765	1,765
Long-term investments	23,834	26,413
Other assets	308	1,821
Total assets	124,176	159,784
Current liabilities:
Accounts payable	2,627	2,987
Accrued expenses and other current liabilities	10,254	12,486
Deferred revenue	2,024	2,201
Operating lease liabilities	2,995	2,782
Total current liabilities	17,900	20,456
Operating lease liabilities, net of current portion	15,896	17,437
Deferred revenue, non-current	4,520	9,107
Other long-term liabilities	0	43
Total liabilities	38,316	47,043
Commitments and contingencies (Note 7)
Stockholders' equity (deficit):
Preferred stock, $0.00001 par value, authorized shares-10,000,000 shares authorized at June 30, 2024 and December 31, 2023; zero shares issued and outstanding at June 30, 2024 and December 31, 2023	0	0
Common stock, $0.00001 par value; 200,000,000 shares authorized at June 30, 2024 and December 31, 2023; 38,264,843 and 38,114,606 shares issued and outstanding at June 30, 2024 and December 31, 2023, respectively	1	1
Additional paid-in capital	482,194	476,988
Accumulated other comprehensive (loss) gain	(44)	37
Accumulated deficit	(396,291)	(364,285)
Total stockholders' equity:	85,860	112,741
Total liabilities and stockholders' equity	$ 124,176	$ 159,784

CONDENSED BALANCE SHEETS (Una_2

CONDENSED BALANCE SHEETS (Unaudited) (Parenthetical) - $ / shares	Jun. 30, 2024	Dec. 31, 2023
Statement of Financial Position [Abstract]
Preferred Stock, Par or Stated Value Per Share	$ 0.00001	$ 0.00001
Preferred Stock, Shares Authorized	10,000,000	10,000,000
Preferred Stock, Shares Issued	0	0
Preferred Stock, Shares Outstanding	0	0
Common Stock, Par or Stated Value Per Share	$ 0.00001	$ 0.00001
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares, issued	38,264,843	38,114,606
Common stock, shares, outstanding	38,264,843	38,114,606

CONDENSED STATEMENTS OF OPERATI

CONDENSED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Income Statement [Abstract]
Collaboration revenue	$ 1,275	$ 1,433	$ 6,549	$ 3,259
Operating expenses:
Research and development	15,433	15,644	31,962	30,269
General and administrative	4,874	5,621	10,711	11,237
Resturcturing charges	3,565		3,565
Total operating expense	23,872	21,265	46,238	41,506
Loss from operations	(22,597)	(19,832)	(39,689)	(38,247)
Other income, net
Interest income, net	1,402	1,775	3,008	3,210
Other income			4,675
Total other income, net	1,402	1,775	7,683	3,210
Net loss	(21,195)	(18,057)	(32,006)	(35,037)
Net unrealized (loss) gain on marketable securities	(8)	6	(81)	690
Comprehensive loss	$ (21,203)	$ (18,051)	$ (32,087)	$ (34,347)
Net loss per share, basic	$ (0.56)	$ (0.48)	$ (0.84)	$ (0.93)
Net loss per share, diluted	$ (0.56)	$ (0.48)	$ (0.84)	$ (0.93)
Weighted-average shares outstanding, basic	38,128,344	37,750,393	38,098,383	37,717,391
Weighted-average shares outstanding, diluted	38,128,344	37,750,393	38,098,383	37,717,391

CONDENSED STATEMENTS OF STOCKHO

CONDENSED STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit
Beginning Balance at Dec. 31, 2022	$ 171,506		$ 467,513	$ (919)	$ (295,088)
Beginning Balance, Shares at Dec. 31, 2022		37,797,902
Vesting of restricted stock units		30,017
Issuance of common stock under employee stock purchase plan, Shares		118,566
Issuance of common stock under employee stock purchase plan	141	$ 1	140
Issuance of common stock upon exercise of stock options, Shares		4,501
Issuance of common stock upon exercise of stock options	6		6
Stock-based compensation	4,826		4,826
Unrealized gain (loss) on available-for-sale investments	690			690
Net loss	(35,037)				(35,037)
Ending Balance at Jun. 30, 2023	142,132	$ 1	472,485	(229)	(330,125)
Ending Balance, Shares at Jun. 30, 2023		37,950,986
Beginning Balance at Mar. 31, 2023	157,686		469,989	(235)	(312,068)
Beginning Balance, Shares at Mar. 31, 2023		37,813,037
Vesting of restricted stock units		14,882
Issuance of common stock under employee stock purchase plan, Shares		118,566
Issuance of common stock under employee stock purchase plan	141	$ 1	140
Issuance of common stock upon exercise of stock options, Shares		4,501
Issuance of common stock upon exercise of stock options	6		6
Stock-based compensation	2,350		2,350
Unrealized gain (loss) on available-for-sale investments	6			6
Net loss	(18,057)				(18,057)
Ending Balance at Jun. 30, 2023	142,132	$ 1	472,485	(229)	(330,125)
Ending Balance, Shares at Jun. 30, 2023		37,950,986
Beginning Balance at Dec. 31, 2023	112,741	$ 1	476,988	37	(364,285)
Beginning Balance, Shares at Dec. 31, 2023		38,114,606
Vesting of restricted stock units		25,646
Issuance of common stock under employee stock purchase plan, Shares		124,591
Issuance of common stock under employee stock purchase plan	79		79
Stock-based compensation	5,127		5,127
Unrealized gain (loss) on available-for-sale investments	(81)			(81)
Net loss	(32,006)				(32,006)
Ending Balance at Jun. 30, 2024	85,860	$ 1	482,194	(44)	(396,291)
Ending Balance, Shares at Jun. 30, 2024		38,264,843
Beginning Balance at Mar. 31, 2024	104,159	$ 1	479,290	(36)	(375,096)
Beginning Balance, Shares at Mar. 31, 2024		38,127,740
Vesting of restricted stock units		12,512
Issuance of common stock under employee stock purchase plan, Shares		124,591
Issuance of common stock under employee stock purchase plan	79		79
Stock-based compensation	2,825		2,825
Unrealized gain (loss) on available-for-sale investments	(8)			(8)
Net loss	(21,195)				(21,195)
Ending Balance at Jun. 30, 2024	$ 85,860	$ 1	$ 482,194	$ (44)	$ (396,291)
Ending Balance, Shares at Jun. 30, 2024		38,264,843

CONDENSED STATEMENTS OF CASH FL

CONDENSED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (32,006)	$ (35,037)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	915	925
Stock-based compensation expense	5,127	4,826
Accretion of discount on marketable securities	(1,824)	(1,964)
Non-cash lease expense	1,561	1,450
Changes in operating assets and liabilities:
Prepaid expenses and other assets	2,098	(928)
Accounts payable and accrued expenses	(2,629)	(5,428)
Operating lease liabilities	(1,328)	(1,139)
Deferred revenue	(4,764)	(1,217)
Other long-term liabilities	(43)	1
Net cash used in operating activities	(32,893)	(38,511)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of property and equipment	0	(35)
Purchases of marketable securities	(55,283)	(96,524)
Maturities of marketable securities	83,489	139,130
Net cash provided by investing activities	28,206	42,571
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock	79	147
Net cash provided by financing activities	79	147
Net (decrease) increase in cash	(4,608)	4,207
Cash, cash equivalents and restricted cash at beginning of year	12,575	10,809
Cash, cash equivalents and restricted cash at end of period	7,967	15,016
Reconciliation of cash, cash equivalents and restricted cash:
Cash and cash equivalents	6,202	13,451
Restricted cash	1,765	1,565
Total cash, cash equivalents and restricted cash	7,967	15,016
Supplemental schedule of non-cash investing and financing activities:
Purchases of property and equipment included in accounts payable and accrued liabilities	37	46
Deferred offering costs in accounts payable and accrued liabilities	$ 102	$ 102

Description of the Business

Description of the Business	6 Months Ended
	Jun. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of the Business	1. Description of the Business Bolt Biotherapeutics, Inc. (the “Company”) is a clinical-stage biopharmaceutical company developing novel immunotherapies for the treatment of cancer. The Company’s pipeline candidates are built on the Company’s deep expertise in myeloid biology and cancer drug development, uniting the targeting precision of antibodies with the power of the innate and adaptive immune system to reprogram the tumor microenvironment for a productive anti-cancer response.

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2024
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The accompanying unaudited condensed financial statements as of June 30, 2024 and for the three and six months ended June 30, 2024 and 2023 have been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) for interim financial information and pursuant to applicable rules and regulations of the SEC regarding interim financial reporting. Accordingly, they do not include all of the information and notes required by U.S. GAAP for complete financial statements. These unaudited condensed financial statements include only normal and recurring adjustments, which are normal in nature, that the Company believes are necessary to a fair statement of the Company’s financial position and the results of its operations and cash flows. The balance sheet as of December 31, 2023 was derived from the audited financial statements as of that date. These interim financial results are not necessarily indicative of results to be expected for the full year or any other period. These unaudited condensed financial statements and the notes accompanying them should be read in conjunction with the Company’s Annual Report on Form 10-K for the year ended December 31, 2023 . Risks and Uncertainties The Company is subject to a number of risks similar to other early-stage biopharmaceutical companies, including, but not limited to, changes in any of the following areas that the Company believes could have a material adverse effect on its future financial position or results of operations: risks related to the successful discovery and development of its product candidates, ability to raise additional capital, development of new technological innovations by its competitors, delay or inability to obtain chemical or biological intermediates from such suppliers required for the synthesis of the Company’s product candidates, protection of intellectual property rights, litigation or claims against the Company based on intellectual property rights, and regulatory clearance and market acceptance of the Company’s products. Global economic and business activities continue to face widespread macroeconomic uncertainties, including pandemics, labor shortages, inflation and monetary supply shifts, recession risks and potential disruptions from major geopolitical conflicts. The Company continues to actively monitor the impact of these macroeconomic factors on its financial condition, liquidity, operations, and workforce. The extent of the impact of these factors on the Company’s operational and financial performance, including its ability to execute its business strategies and initiatives in the expected time frame, will depend on future developments, which are uncertain and cannot be predicted; however, any continued or renewed disruption resulting from these factors could negatively impact the Company’s business. The Company relies on single source manufacturers and suppliers for the supply of its product candidates. Disruption from these manufacturers or suppliers would have a negative impact on the Company’s business, financial position, and results of operations. Liquidity The Company has incurred net losses and negative cash flows from operations since its inception and anticipates continuing to incur net losses for the foreseeable future. As of June 30, 2024 , the Company had cash and cash equivalents and marketable securities of $ 97.5 million and an accumulated deficit of $ 396.3 million. Based upon the Company's current operating plans, the Company believes that its existing cash, cash equivalents and marketable securities will be sufficient to fund its operations for at least the next 12 months following the issuance date of this Quarterly Report on Form 10-Q. The Company will need to raise additional capital to continue the advancement of its programs. In the near term, the Company's primary uses of cash will be to fund the completion of key milestones for clinical programs and to fund its operations, including research and development activities and employee salaries. This includes significant costs relating to clinical trials and manufacture of the Company's product candidates. The Company's uses of cash in the long term will be similar as the Company advances its research and development activities and pays employee salaries. Most pharmaceutical products require larger clinical trials as development progresses, and the Company expects its funding requirements to grow with the advancement of its programs. The Company's long-term funding requirements will depend on many factors, which are uncertain but include its portfolio prioritization decisions and the success of its collaborations. In turn, the Company's ability to raise additional capital through equity or partnering will depend on the general economic environment in which it operates and its ability to achieve key milestones. Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, and the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. On an ongoing basis, the Company evaluates its estimates and assumptions, including those related to revenue recognition, stock-based compensation, restructuring costs, long-lived assets impairment assessment, and accrued 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 may differ materially from those estimates. Restructuring Charges Restructuring charges consist primarily of employee severance, contract termination costs and other costs. Liabilities for costs associated with a restructuring activity are recognized when the liability is incurred and are measured at fair value. For one-time employee terminations benefits, the Company recognizes the liability in full on the communication date when future services are not required or amortizes the liability ratably over the service period, if required. The fair value of termination benefits reflects the Company’s estimate of expected utilization of certain Company-funded post-employment benefits. One-time termination benefits include severance, continuation of health insurance coverage for certain employees, and other company funded benefits. Long-lived Assets Impairment Assessment Long-lived assets, including operating lease assets, are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. The recoverability of assets to be held and used is measured by a comparison of the carrying amount of the asset group to future net cash flows estimated by the Company to be generated by such assets. If such asset group is considered to be impaired, the impairment to be recognized is the amount by which the carrying amount of the asset group exceeds the fair value of the asset group. During the three months ended June 30, 2024 , the Company performed an evaluation of the impact of the May 2024 announcement and restructuring plan on the carrying value of its long-lived assets and concluded that there was no impairment charge to be recognized on the long-lived assets. Allowance for Credit Losses For available-for-sale securities in an unrealized loss position, the Company first assesses whether it intends to sell, or if it is more likely than not that the Company will be required to sell, the security before recovery of its amortized cost basis. If either of the criteria regarding intent or requirement to sell is met, the security’s amortized cost basis is written down to fair value through earnings. For available-for-sale securities that do not meet the aforementioned criteria, the Company evaluates whether the decline in fair value has resulted from credit losses or other factors. In making this assessment, the Company considers the severity of the impairment, any changes in interest rates, market conditions, changes to the underlying credit ratings and forecasted recovery, among other factors. The credit-related portion of unrealized losses, and any subsequent improvements, are recorded in interest income through an allowance account. Any impairment that has not been recorded through an allowance for credit losses is included in other comprehensive income (loss) on the statements of operations and comprehensive loss. The Company elected the practical expedient to exclude the applicable accrued interest from both the fair value and amortized costs basis of its available-for-sale securities for purposes of identifying and measuring an impairment. Accrued interest receivable on available-for-sale securities is recorded within cash and cash equivalents on the Company's condensed balance sheets. The Company's accounting policy is to not measure an allowance for credit loss for accrued interest receivable and to write-off any uncollectible accrued interest receivable as a reversal of interest income in a timely manner, which the Company considers to be in the period in which it determines the accrued interest will not be collected by the Company. Concentrations of Credit Risk Financial instruments that potentially subject the Company to concentration of credit risk consist of cash, cash equivalents and marketable securities. As of June 30, 2024 and December 31, 2023 , most of the Company’s funds were invested with a registered investment manager and custodied at one financial institution, with operating cash kept at a separate financial institution, and account balances may at times exceed federally insured limits. Management believes that the Company is not subject to unusual or significant credit risk beyond the normal credit risk associated with commercial banking relationships. Net Loss Per Share Basic net loss per share is calculated by dividing the net loss by the weighted-average number of shares of common stock outstanding during the period, without consideration for potentially dilutive securities. Diluted net loss per share is computed by dividing the net loss by the weighted-average number of common stock and potentially dilutive securities outstanding for the period. For purposes of the diluted net loss per share calculation, convertible preferred stock, stock options, common stock subject to repurchase related to unvested restricted stock awards and early exercise of stock options are considered potentially dilutive securities. Basic and diluted net loss per share is presented in conformity with the two-class method required for participating securities as the convertible preferred stock is considered a participating security because it participates in dividends with common stock. The Company also considers the shares issued upon the early exercise of stock options subject to repurchase to be participating securities because holders of such shares have non-forfeitable dividend rights in the event a dividend is paid on common stock. The holders of all series of convertible preferred stock and the holders of early exercised shares subject to repurchase do not have a contractual obligation to share in the Company’s losses. As such, the net loss was attributed entirely to common stockholders. Because the Company has reported a net loss for all periods presented, diluted net loss per share is the same as basic net loss per share for all periods presented as potentially dilutive securities were anti-dilutive. Recent Accounting Standards From time to time, new accounting standards are issued by the Financial Accounting Standards Board (the “FASB”), or other standard setting bodies and adopted by the Company as of the specified effective date. Unless otherwise discussed, the impact of recently issued standards that are not yet effective will not have a material impact on the Company’s financial position or results of operations upon adoption. In November 2023, the FASB issued ASU 2023-07 Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures (“ASU 2023-07”), which requires entities to disclose incremental segment information on an annual and interim basis. ASU 2023-07 requires entities with a single reportable segment to provide all the disclosures required by the amendments in ASU 2023-07 and all existing segment disclosures in Segment Reporting (Topic 280). ASU 2023-07 is effective for annual periods beginning on January 1, 2024, and interim periods beginning on January 1, 2025. The Company does not expect the adoption of ASU 2023-07 to have a material impact on its financial statements and related disclosures. In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures (“ASU 2023-09”). ASU 2023-09 requires enhanced annual disclosures regarding the rate reconciliation and income taxes paid information. ASU 2023-09 is effective for annual periods beginning on January 1, 2025 and may be adopted on a prospective or retrospective basis. Early adoption is permitted. The Company is evaluating the impact of this guidance on its financial statements and related disclosures.

Fair Value Measurements and Fai

Fair Value Measurements and Fair Value of Financial Instruments	6 Months Ended
	Jun. 30, 2024
Fair Value Disclosures [Abstract]
Fair Value Measurements and Fair Value of Financial Instruments	3. Fair Value Measurements and Fair Value of Financial Instruments The authoritative guidance on fair value measurements establishes a three-tier fair value hierarchy for disclosure of fair value measurements as follows: Level 1 —Quoted prices in active markets for identical assets or liabilities. Level 2 —Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities, quoted prices in markets that are no t active or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 —U no bservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. Assets and liabilities measured at fair value are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires management to make judgments and consider factors specific to the asset or liability. During the three and six months ended June 30, 2024, financial assets measured on a recurring basis consist of cash invested in money market accounts, short-term investments, and long-term investments. The fair value of short- and long-term investments is based upon market prices quoted on the last day of the fiscal period or other observable market inputs. The Company obtains pricing information from its investment manager and generally determines the fair value of investment securities using standard observable inputs, including reported trades, broker/dealer quotes, bids and/or offers. There were no transfers within the hierarchy during the three and six months ended June 30, 2024 or 2023. Marketable securities, all of which are classified as available-for-sale securities, consisted of the following at June 30, 2024 and December 31, 2023 (in thousands): June 30, 2024 Amortized Unrealized Unrealized Estimated Cost Gains Losses Fair Value Asset-backed securities $ 24,982 $ 3 $ ( 12 ) $ 24,973 U.S. treasury securities 25,730 — ( 13 ) 25,717 Other government agency securities 6,481 — ( 11 ) 6,470 Commercial paper 7,986 — ( 5 ) 7,981 Corporate debt securities 29,157 9 ( 15 ) 29,151 Total $ 94,336 $ 12 $ ( 56 ) $ 94,292 December 31, 2023 Amortized Unrealized Unrealized Estimated Cost Gains Losses Fair Value Asset-backed securities $ 17,347 $ 10 $ ( 15 ) $ 17,342 U.S. treasury securities 43,924 34 ( 11 ) 43,947 Other government agency securities 13,371 — ( 15 ) 13,356 Commercial paper 20,351 4 ( 10 ) 20,345 Corporate debt securities 22,763 41 ( 2 ) 22,802 Total $ 117,756 $ 89 $ ( 53 ) $ 117,792 As of June 30, 2024, the unrealized losses for available-for-sale investments were primarily due to changes in interest rates and not due to increased credit risks associated with specific securities. The contractual terms of those investments do not permit the issuer to settle the securities at a price less than the amortized cost bases of the investments. The Company does not currently intend to sell the investments and it is not more likely than not that the Company will be required to sell the investments before recovery of their amortized cost bases, which may be at the time of maturity. As of June 30, 2024 , no allowance for credit losses was recorded and the Company did not recognize any impairment losses related to investments. The tables below show the gross unrealized losses and fair value of the Company's available-for-sale securities with unrealized losses that are not deemed to have credit losses (in thousands), aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position at June 30, 2024 and December 31, 2023, respectively: June 30, 2024 Less Than 12 Months More Than 12 Months Total Estimated Unrealized Estimated Unrealized Estimated Unrealized Fair Value Losses Fair Value Losses Fair Value Losses Asset-backed securities $ 6,485 $ ( 2 ) $ 18,488 $ ( 10 ) $ 24,973 $ ( 12 ) U.S. treasury securities 14,839 ( 6 ) 10,878 ( 7 ) 25,717 ( 13 ) Other government agency securities — — 6,470 ( 11 ) 6,470 ( 11 ) Commercial paper 7,981 ( 5 ) — — 7,981 ( 5 ) Corporate debt securities 18,816 ( 8 ) 10,335 ( 7 ) 29,151 ( 15 ) Total $ 48,121 $ ( 21 ) $ 46,171 $ ( 35 ) $ 94,292 $ ( 56 ) December 31, 2023 Less Than 12 Months More Than 12 Months Total Estimated Unrealized Estimated Unrealized Estimated Unrealized Fair Value Losses Fair Value Losses Fair Value Losses Asset-backed securities $ 4,686 $ — $ 12,656 $ ( 15 ) $ 17,342 $ ( 15 ) U.S. treasury securities 34,104 — 9,843 ( 11 ) 43,947 ( 11 ) Other government agency securities 2,477 ( 1 ) 10,879 ( 14 ) 13,356 ( 15 ) Commercial paper 20,345 ( 10 ) — — 20,345 ( 10 ) Corporate debt securities 9,566 ( 1 ) 13,236 ( 1 ) 22,802 ( 2 ) Total $ 71,178 $ ( 12 ) $ 46,614 $ ( 41 ) $ 117,792 $ ( 53 ) Accrued interest receivable on available-for-sale securities were $ 0.4 million and $ 0.3 million at June 30, 2024 and December 31, 2023, respectively, which are recorded in cash and cash equivalents line item on the Company's condensed balance sheets. The Company has not written off any accrued interest receivables for the three and six months ended June 30, 2024. As of June 30, 2024 and December 31, 2023, the fair values of the Company’s assets, which are measured at fair value on a recurring basis, were determined using the following inputs (in thousands): June 30, 2024 Total (Level 1) (Level 2) (Level 3) Money market funds $ 1,990 $ 1,990 $ — $ — Asset-backed securities 24,973 — 24,973 — U.S. treasury securities 25,717 6,422 19,295 — Other government agency securities 6,470 — 6,470 — Commercial paper 7,981 — 7,981 — Corporate debt securities 29,151 — 29,151 — Total $ 96,282 $ 8,412 $ 87,870 $ — December 31, 2023 Total (Level 1) (Level 2) (Level 3) Money market funds $ 8,641 $ 8,641 $ — $ — Asset-backed securities 17,342 — 17,342 — U.S. treasury securities 43,947 33,001 10,946 — Other government agency securities 13,356 — 13,356 — Commercial paper 20,345 — 20,345 — Corporate debt securities 22,802 — 22,802 — Total $ 126,433 $ 41,642 $ 84,791 $ —

Balance Sheet Components

Balance Sheet Components	6 Months Ended
	Jun. 30, 2024
Balance Sheet Related Disclosures [Abstract]
Balance Sheet Components	4. Balance Sheet Components Property and Equipment, net Property and equipment, net, consist of the following (in thousands): June 30, December 31, Laboratory equipment $ 10,075 $ 10,038 Office equipment 386 386 Leasehold improvements 286 285 Total property and equipment 10,747 10,709 Less accumulated depreciation and amortization ( 6,668 ) ( 5,752 ) Total $ 4,079 $ 4,957 Depreciation expense related to property and equipment was $ 0.4 million for each of the three months ended June 30, 2024 and 2023 and $ 0.9 million for each of the six months ended June 30, 2024 and 2023. Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities consist of the following (in thousands): June 30, December 31, Accrued research and development $ 4,019 $ 6,092 Accrued compensation 2,889 5,820 Accrued restructuring charges 2,900 — Accrued other 446 574 Total $ 10,254 $ 12,486

Collaborations

Collaborations	6 Months Ended
	Jun. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Collaborations	5. Collaborations Joint Development and License Agreement with Toray Industries, Inc. In March 2019, the Company entered into a Joint Development and License Agreement (the “Toray Agreement”) with Toray Industries, Inc. (“Toray”) to jointly develop and commercialize a Boltbody™ immune-stimulating antibody conjugate (“ISAC”) containing Toray’s proprietary antibody to treat cancer. The Company determined that the Toray Agreement is a contract with a customer and should be accounted for under ASC 606. In conjunction with the Toray Agreement, the Company entered into a Series T Convertible Preferred Stock Purchase Agreement (the “Series T Agreement”) for the issuance of 717,514 shares of Series T convertible preferred stock to Toray. These contracts have been evaluated together and the consideration in excess of the fair value of the Series T convertible preferred stock of $ 1.5 million has been allocated to the Toray Agreement and included in the total consideration for collaboration revenue. In February 2021, in connection with the Company’s initial public offering ("IPO"), all outstanding shares of Series T convertible preferred stock were converted into shares of the Company’s common stock. In the Toray Agreement, the Company has identified one bundled performance obligation which includes the license rights, research and development services and services associated with participation on a joint steering committee. The transaction price includes the $ 1.5 million allocated from the Series T convertible preferred stock and $ 1.9 million of estimated variable consideration related to compensation for research and development services at the agreed upon full-time employee rate and third-party costs. Collaboration revenue is recognized over time proportionate to the costs that the Company has incurred to perform the services using an input method as a measure of progress towards satisfying the performance obligation, which is based on project hours. Amounts are billed based on estimated variable consideration in the quarter ahead of performance and are trued up on the subsequent quarter’s invoice following the work performed. The cumulative effect of revisions to estimated hours to complete the Company’s performance obligation will be recorded in the period in which changes are identified and amounts can be reasonably estimated. As of June 30, 2024 , receivables of $ 0.2 million related to research and development services performed under the Toray Agreement were recorded as part of the prepaid expenses and other current assets line item on the Company's condensed balance sheet. Deferred revenue allocated to the unsatisfied performance obligation is recorded as a contract liability on the Company's condensed balance sheet and will be recognized over time as the services are performed. As of June 30, 2024 , contract liabilities totaling $ 1.0 million at period-end were recorded in deferred revenue with $ 0.4 million in current liabilities and $ 0.6 million in non-current liabilities on the Company's condensed balance sheet based on the forecasted periods of performance. The following table presents changes in the Company contract liability (in thousands): Balance at December 31, 2023 $ 1,502 Addition—amount billed or accrued for research and development services 285 Revenue recognized ( 814 ) Balance at June 30, 2024 $ 973 The Company recorded $ 0.2 million and $ 0.8 million revenue during the three and six months ended June 30, 2024 , respectively, and zero in the same periods in 2023. The Toray Agreement includes both fixed and variable considerations. Under the Toray Agreement, the Company will be compensated for early-stage development and manufacturing activities based on agreed full-time equivalent rates and actual out-of-pocket costs incurred through the completion of the first Phase 1 clinical trial for the lead product candidate and Toray is entitled to reimbursement for 50% of such development costs from the Company’s share of revenues collected from the sale or licensing of collaboration products. Although the legal term of the agreement is until collaboration products are no longer sold in the territories covered under the agreement, the parties have present enforceable rights and obligations through the end of the first Phase 1 clinical trial, after which both parties can opt out of continued development under the agreement. As such, the accounting term of the Toray Agreement was considered to terminate upon completion of the first Phase 1 clinical trial. After the conclusion of the first Phase 1 clinical trial, the parties will share equally all costs of development activities necessary for obtaining regulatory approval of collaboration products in the indications in the territories covered under the agreement, unless either party elects to opt out of its co-funding obligations or reduce them by half, which election can be on a region-by-region basis or for the territories covered under the agreement as a whole. Such optional additional items will be accounted for as contract modifications when development advances past certain milestones and the parties both exercise their opt-in rights. Oncology Research and Development Collaboration with Genmab A/S In May 2021, the Company entered into a License and Collaboration Agreement (the “Genmab Agreement”) with Genmab A/S (“Genmab”). Together, the companies will evaluate Genmab antibodies and bispecific antibody engineering technologies in combination with the Company’s Boltbody ISAC technology platform, with the goal of discovering and developing next-generation bispecific ISACs for the treatment of cancer. Under this research collaboration, the companies will evaluate multiple bispecific ISAC concepts to identify up to three clinical candidates for development. Genmab will fund the research, along with the preclinical and clinical development of these candidates through initial clinical proof of concept. Under the Genmab Agreement, the Company received an upfront payment of $ 10.0 million. The Company has determined that the Genmab Agreement is a contract with a customer and should be accounted for under ASC 606. In conjunction with the Genmab Agreement, the Company entered into a stock purchase agreement (the “Genmab SPA”) for the issuance of 821,045 shares of the Company’s common stock to Genmab for a total purchase price of $ 15.0 million. These contracts have been evaluated together and the consideration in excess of the fair value of the common stock of $ 1.4 million has been allocated to the Genmab Agreement and included in the total consideration for collaboration revenue. In the Genmab Agreement, the Company has identified one bundled performance obligation that includes the license rights, research and development services, and services associated with participation on a joint research committee. The transaction price includes the $ 10.0 million upfront payment, the $ 1.4 million allocated from the Genmab SPA, and $ 28.6 million of estimated variable consideration related to compensation for research and development services at the agreed upon full-time employee rate and third-party costs. Collaboration revenue is recognized over time proportionate to the costs that the Company has incurred to perform the services using an input method as a measure of progress towards satisfying the performance obligation, which is based on project hours. Compensation for the research and development services are billed in the quarter based on actual hours incurred to satisfy the performance obligation. The cumulative effect of revisions to estimated hours to complete the Company’s performance obligation will be recorded in the period in which changes are identified and amounts can be reasonably estimated. As of June 30, 2024 , receivables of $ 0.5 million related to research and development services performed under the Genmab Agreement were recorded as part of the prepaid expenses and other current assets line item on the Company's condensed balance sheet. Deferred revenue allocated to the unsatisfied performance obligation is recorded as a contract liability on the Company's condensed balance sheet and will be recognized over time as the services are performed. As of June 30, 2024 , contract liabilities totaling $ 5.6 million were recorded in deferred revenue with $ 1.6 million in current liabilities and $ 4.0 million in non-current liabilities on the Company's condensed balance sheet based on the forecasted periods of performance. The following table presents changes in the Company contract liability (in thousands): Balance at December 31, 2023 $ 6,664 Addition—amount billed for research and development services 1,169 Revenue recognized ( 2,263 ) Balance at June 30, 2024 $ 5,570 The Company recorded $ 1.0 million and $ 2.3 million in revenue earned during the three and six months ended June 30, 2024 , respectively, and $ 0.8 million and $ 1.8 million in the same periods in 2023, respectively, based on services performed under the Genmab Agreement during the period. Under the Genmab Agreement, the Company will be compensated for research and development services at the agreed upon full-time employee rate and third-party costs through initial clinical proof of concept of the therapeutic candidates, which also represents the period of time both parties have enforceable rights and obligations. As such, the accounting term of the Genmab Agreement was considered to terminate upon completion of the initial clinical proof of concept of the therapeutic candidates, after which Genmab has the option to develop and commercialize up to three therapeutic candidates and the Company has the option to participate in development and commercialization of one candidate. The Genmab Agreement includes optional additional items which will be accounted for as contract modifications after initial clinical proof of concept of the therapeutic candidates. With respect to each candidate for which a party has exercised its program opt-in rights and has exclusive global rights, the other party is eligible to receive potential development and sales-based milestone payments and tiered royalties, subject to certain customary reductions, the amount of all such considerations will vary based on the market potential of the applicable territory for which such party has exercised its program opt-in rights. Under the Genmab Agreement, the Company is eligible to receive total potential milestone payments of up to $ 125.0 million in development milestones and $ 160.0 million in sale milestones per therapeutic candidate exclusively developed and commercialized by Genmab, along with tiered royalties at rates from a single-digit to mid-teens percentage based on net sales of each therapeutic candidate. However, given the current phase of development of therapeutic candidates under the Genmab Agreement, the Company cannot estimate the probability or timing of achieving these milestones, and, therefore, has excluded all milestone and royalty payments from the transaction prices of the agreement. Oncology Research and Development Collaboration with Innovent Biologics, Inc. In March 2024, the Company entered into an amended and restated license and collaboration agreement with Innovent Biologics, Inc. (the “Amended Innovent Agreement”), which amends the original license and collaboration agreement with Innovent Biologics, Inc. ("Innovent") dated August 25, 2021 (the “Original Innovent Agreement”). Under the Original Innovent Agreement, the Company and Innovent leveraged Innovent’s proprietary therapeutic antibody portfolio and antibody discovery capability against undisclosed oncology targets in combination with the Company's Boltbody ISAC technology and myeloid biology expertise to create new candidates for cancer treatments. Innovent funded the initial research, along with the preclinical development of these candidates through the contract modification date. Under the Original Innovent Agreement, the Company received an upfront payment of $ 5.0 million and was compensated for research and development services at the agreed upon full-time employee rate and third-party costs. As part of the Amended Innovent Agreement, Innovent paid the Company a one-time payment of $ 4.7 million to be relieved from certain future funding and developmental obligations under the Original Innovent Agreement. Additionally, the Company secured exclusive worldwide rights to ISAC programs utilizing specified antibodies against two tumor antigen targets and assumed all future development and commercialization costs for any such ISAC program. Under the Amended Innovent Agreement, the Company has the right, but not the obligation, to further develop and commercialize the ISAC programs. Innovent and its affiliates are eligible to receive total potential milestones payments of up to $ 112.7 million, as well as royalties in low single digits on global net sales. The Company determined that the Amended Innovent Agreement no longer meets the criteria under ASC 606. Therefore, $ 2.5 million of deferred revenue allocated to the unsatisfied performance obligation as of the contract modification date, was recognized as revenue and the $ 4.7 million one-time payment received was recognized as other income on the condensed statement of operations and comprehensive loss in the first quarter of 2024. The following table presents changes in the Company contract liability (in thousands): Balance at December 31, 2023 $ 3,142 Addition—amount billed for research and development services 331 Revenue recognized ( 3,473 ) Balance at June 30, 2024 $ — The Company recorded zero and $ 3.5 million in revenue earned during the three and six months ended June 30, 2024 , respectively, and $ 0.6 million and $ 1.5 million in the same periods in 2023, respectively, based on services performed to satisfy the performance obligation under the Innovent collaboration during the periods. Oncology Clinical Trial Collaboration and Supply Agreement with Bristol-Myers Squibb In September 2021, the Company entered into a clinical collaboration and supply agreement with Bristol-Myers Squibb Company (“BMS”) to study trastuzumab imbotolimod in combination with BMS’s PD-1 checkpoint inhibitor nivolumab, for the treatment of HER2-expressing solid tumors (the “BMS Agreement”). Under the BMS Agreement, BMS granted the Company a non-exclusive, non-transferable, royalty-free license (with a right to sublicense) under its intellectual property to use nivolumab in a clinical trial for a combination therapy of nivolumab and trastuzumab imbotolimod, formerly known as BDC-1001. On May 14, 2024, the Company announced a strategic pipeline prioritization and restructuring plan pursuant to which it will discontinue developing trastuzumab imbotolimod, which includes the clinical trial for a combination therapy of nivolumab and trastuzumab imbotolimod. Clinical Supply Agreement with F. Hoffmann-La Roche Ltd In September 2022, the Company entered into a clinical supply agreement with Roche to study trastuzumab imbotolimod in combination with Roche’s pertuzumab (Perjeta®), a compound approved for the treatment of HER2-positive breast cancer (the "Roche Agreement"). Under the Roche Agreement, Roche granted the Company a non-exclusive, non-sublicensable, royalty-free license under its intellectual property to use pertuzumab in a clinical trial for a combination therapy of pertuzumab and trastuzumab imbotolimod. On May 14, 2024, the Company announced a strategic pipeline prioritization and restructuring plan pursuant to which it will discontinue developing trastuzumab imbotolimod, which includes the clinical trial for a combination therapy of pertuzumab and trastuzumab imbotolimod .

Commitment and Contingencies

Commitment and Contingencies	6 Months Ended
	Jun. 30, 2024
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	6. Commitments and Contingencies Leases The Company has operating leases for its corporate office, laboratory and vivarium space in Redwood City, California. On August 7, 2020, the Company executed a non-cancellable lease agreement for 71,646 square feet of space (the “Chesapeake Master Lease”), which consist of 25,956 square feet under an existing lease and 45,690 square feet of additional space, for its corporate office, laboratory and vivarium space in Redwood City, California. The Chesapeake Master Lease has an initial term of ten years from the commencement date, with an option to extend the lease for an additional eight-year term. The Chesapeake Master Lease contains rent escalation, and the Company is also responsible for certain operating expenses and taxes throughout the lease term. In addition, the Company is entitled to up to $ 4.8 million of tenant improvement allowance, which was paid directly by the landlord to various vendors. Upon execution of the non-cancellable lease agreement, the Company took control of 10,000 square feet of space, which was subleased as further described below. The remaining 35,690 square feet of additional office, laboratory and vivarium space commenced in June 2021. In connection with the execution of the Chesapeake Master Lease, the Company entered into two operating lease agreements to sublease portions of the premises to two unrelated third parties. The first sublease agreement, to sublease 10,000 square feet, commenced in August 2020 and expired on August 31, 2022 . The second sublease agreement, to sublease 10,500 square feet, commenced in June 2021 and expired on July 31, 2023 . In August 2022, the second sublease agreement was amended to expand the subleased premises to 11,655 square feet in the first year and further increase to 13,743 square feet in the second year. In addition, the expiration date of the second sublease was also amended to the expiration date of the Chesapeake Master Lease. The subtenant has an early termination option with the early termination date no earlier than September 30, 2024 , and no option to extend the sublease term . Rent for the second sublease is subject to scheduled annual increases and the subtenant is responsible for certain operating expenses and taxes throughout the term under the sublease agreement. Sublease income under the two sublease agreements was approximately $ 0.2 million for each of the three months ended June 30, 2024 and 2023 and $ 0.4 million for each of six months ended June 30, 2024 and 2023. At June 30, 2024 and December 31, 2023, finance right-of-use leases were used to finance capital equipment such as printers or ozone generators, and are immaterial. The weighted-average remaining lease term and discount rate related to the Company’s lease liabilities as of June 30, 2024 were 6.4 years and 11.2 %, respectively, for the operating leases. The weighted-average remaining lease term and discount rate related to the Company’s lease liabilities as of December 31, 2023 were 6.7 years and 11.1 %, respectively, for the operating leases. The Company lease discount rates are based on estimates of its incremental borrowing rate, as the discount rates implicit in the Company’s leases cannot be readily determined. As the Company does not have any outstanding debt, the Company estimates the incremental borrowing rate based on its estimated credit rating and available market information. The components of lease expense were as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2024 2023 2024 2023 Total operating lease cost $ 1,119 $ 1,119 $ 2,239 $ 2,239 Supplemental cash flow information related to leases was as follows (in thousands): Six Months Ended June 30, 2024 2023 Operating cash flows from operating leases $ 2,411 $ 2,332 The following is a schedule by year for future maturities of the Company’s operating lease liabilities and sublease income to be received as of June 30, 2024 (in thousands): Operating Leases Sublease Income 2024 $ 2,475 $ 183 2025 4,340 — 2026 3,484 — 2027 3,602 — 2028 3,724 — Thereafter 9,514 — Total minimum lease payments/sublease income 27,139 183 Less imputed interest ( 8,248 ) — Total $ 18,891 $ 183 Supply Agreement In January 2022, the Company entered into an amended and restated supply agreement with EirGenix, Inc. (the “Amended Supply Agreement”), which amends the original supply agreement with EirGenix, Inc. (“EirGenix”), dated March 10, 2019, pursuant to which EirGenix agreed to supply to the Company, on a non-exclusive basis, bulk drug substance of EG12014, its monoclonal antibody being developed as a biosimilar of trastuzumab, which the Company uses in the manufacture of trastuzumab imbotolimod. Under the Amended Supply Agreement, the Company may be required to pay milestone payments upon the achievement of specified regulatory milestones. The Amended Supply Agreement is cancellable by the Company upon delivering the appropriate written notice. On May 14, 2024, the Company announced a strategic pipeline prioritization and restructuring plan pursuant to which it will discontinue developing trastuzumab imbotolimod. As of June 30, 2024 , the Company did no t incur any nor have any milestone payments probable under the Amended Supply Agreement. Guarantees and Indemnifications In the normal course of business, the Company enters into agreements that contain a variety of representations and provide for general indemnification. The Company’s exposure under these agreements is unknown because it involves claims that may be made against the Company in the future. To date, the Company has not paid any claims or been required to defend any action related to its indemnification obligations. As of June 30, 2024, the Company did not have any material indemnification claims that were probable or reasonably possible and, consequently, had not recorded related liabilities. Other Commitments The Company enters into agreements in the normal course of business, including with contract research organizations for clinical trials, contract manufacturing organizations for certain manufacturing services, and vendors for preclinical studies and other services and products for operating purposes, which are generally cancelable upon written notice. Legal Proceedings From time to time, we might be subject to various legal proceedings relating to claims arising out of our operations. The outcome of litigation is inherently uncertain. If one or more legal matters were resolved against us in a reporting period for amounts above management’s expectations, our business, results of operations, financial position and cash flows for that reporting period could be materially adversely affected. Except as described below, we are not currently involved in any material legal proceedings, the ultimate disposition of which could have a material adverse effect on our operations, financial condition or cash flows. Securities Class Action On July 2, 2024, a securities class action complaint was filed against the Company and certain of its directors and executive officers (collectively, the "Defendants") in the United States District Court for the Northern District of California, captioned Nesterenko v. Bolt Biotherapeutics, Inc. et al. , Case No. 3:24-cv-03985 , purportedly on behalf of a class of individuals who purchased or otherwise acquired the Company’s common stock between February 5, 2021 and May 14, 2024. The complaint alleges that Defendants made false and/or misleading statements in violation of Sections 10(b) and 20(a) of the Securities Exchange Act of 1934, as amended. The complaint seeks unspecified monetary damages and other relief. The Company intends to defend the case vigorously.

Restructuring

Restructuring	6 Months Ended
	Jun. 30, 2024
Restructuring and Related Activities [Abstract]
Restructuring	7. R estructuring On May 14, 2024, the Company announced a strategic pipeline prioritization and restructuring plan pursuant to which it will discontinue developing trastuzumab imbotolimod in order to focus on the Company’s Phase 1 asset, BDC-3042, a Dectin-2 agonist antibody, and the Company's next generation ISAC platform including new clinical candidate, BDC-4182, targeting Claudin 18.2, and reduce overall operating expenses. The restructuring plan reduced the Company’s workforce by approximately 50 %. The Company recorded a total restructuring charge of $ 3.6 million, which consist of $ 2.9 million of one-time termination benefits such as severance costs and related benefits and $ 0.7 million of non-cash stock-based compensation expense. No cash payments and no other non-cash settlements or adjustments were made during the three and six months ended June 30, 2024. As of June 30, 2024 , the $ 2.9 million one-time termination benefits remain payable and are recorded within the accrued expenses and other current liabilities line item on the Company's condensed balance sheet. Severance payments commenced in July 2024 and will extend through July 2025.

Common Stock

Common Stock	6 Months Ended
	Jun. 30, 2024
Equity [Abstract]
Common Stock	8. Common Stock Shelf Registration and At-The-Market Equity Offering On March 30, 2022, the Company filed a shelf registration statement on Form S-3 (the "Registration Statement"). Pursuant to the Registration Statement, the Company may offer and sell securities having an aggregate public offering price of up to $ 250.0 million. In connection with the filing of the Registration Statement, the Company also entered into a sales agreement with Cowen and Company, LLC ("Cowen"), as sales agent or principal, pursuant to which the Company may issue and sell shares of its common stock for an aggregate offering price of up to $ 75.0 million under an at-the-market (the “ATM”) offering program. Pursuant to the ATM, the Company will pay Cowen a commission rate equal to 3.0 % of the gross proceeds from the sale of any shares of common stock. The Company is not obligated to make any sales of shares of its common stock under the ATM. As of June 30, 2024 , no shares of the Company's common stock have been sold under this ATM.

Stock-Based Compensation

Stock-Based Compensation	6 Months Ended
	Jun. 30, 2024
Share-Based Payment Arrangement [Abstract]
Stock-Based Compensation	9. Stock-Based Compensation 2021 Equity Incentive Plan and 2021 Employee Stock Purchase Plan In January 2021, the Company’s board of directors adopted the 2021 Equity Incentive Plan (the “2021 Plan”) and the Company’s stockholders approved the 2021 Plan. The 2021 Plan authorized issuance of up to 8,075,000 shares of common stock and it became effective upon the execution of the underwriting agreement for the Company’s IPO. In addition, the number of shares of common stock reserved for issuance under the 2021 Plan automatically increases on the first day of January of each calendar year that commences after the 2021 Plan became effective and continuing through and including January 1, 2031, in an amount equal to 5 % of the total number of shares of the Company’s common stock outstanding on December 31, or a lesser number of shares determined by the Company's board of directors or compensation committee. As a result, common stock reserved for issuance under the 2021 Plan was increased by 1,905,730 shares on January 1, 2024. In connection with the workforce reduction described in Note 7 “Restructuring”, the Company entered into consulting agreements with certain officers of the Company, pursuant to which a total of 1,615,713 stock options previously granted to the officers were canceled on July 15, 2024. In addition, in January 2021, the Company’s board of directors and stockholders adopted the 2021 Employee Stock Purchase Plan (the “ESPP”). The ESPP authorized issuance of up to 420,000 shares of common stock and it became effective upon the execution of the underwriting agreement for the Company’s IPO. The 2021 ESPP permits participants to purchase common stock through payroll deductions of up to 15 % of their eligible compensation. Employees purchase shares of common stock at a price per share equal to 85 % of the lower of the fair market value at the start or end of six-month purchase periods within the two-year offering period. In addition, the number of shares of common stock reserved for issuance under the 2021 ESPP automatically increases on January 1 of each calendar year that commences after the ESPP became effective and continuing through and including January 1, 2031, by the lesser of (1) 1 % of the total number of shares of the Company's common stock outstanding on December 31 of the preceding calendar year, (2) 840,000 shares, and (3) a number of shares determined by the Company's board of directors. As a result, common stock reserved for issuance under the 2021 ESPP was increased by 381,146 shares on January 1, 2024. During the six months ended June 30, 2024 , 124,591 shares were issued under the ESPP and 118,566 shares were issued under the ESPP during the same period in 2023. Performance and Service-Based Stock Options In September 2020, the compensation committee of the Company’s board of directors granted 526,018 options to employees that would commence vesting upon the closing of the Series C-2 financing and generally vest monthly over 48 months (the “Performance Awards”). The Company recognizes expense based on the fair value of the Performance Awards over the estimated service period (under the graded vesting method) to the extent the achievement of the related performance criteria is estimated to be probable. The Company determined that the financing milestone was achieved during January 2021. Accordingly, the Company recognized stock-based compensation expense related to the Performance Awards of approximately $ 14,000 and $ 31,000 for the three and six months ended June 30, 2024 , respectively, and $ 39,000 and $ 0.1 million for the same periods in 2023, respectively. The weighted-average grant date fair value of the Performance Awards was $ 3.24 per share. Restricted Stock Units In December 2021, the Company issued 336,000 restricted stock units under the 2021 Plan at a grant date fair value of $ 4.51 per share. These restricted stock units vest in equal quarterly installments over three years , subject to the employee's continued employment with, or services to, the Company on each vesting date. Each restricted stock unit represents the right to receive one share of the Company's common stock when and if the applicable vesting conditions are satisfied. Stock-Based Compensation Expense The following table summarizes the components of stock-based compensation expense recognized in the Company’s statement of operations and comprehensive loss (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2024 2023 2024 2023 Research and development $ 1,077 $ 905 $ 2,057 $ 1,931 General and administrative 1,748 1,445 3,070 2,895 Total $ 2,825 $ 2,350 $ 5,127 $ 4,826

Net Loss Per Share

Net Loss Per Share	6 Months Ended
	Jun. 30, 2024
Earnings Per Share [Abstract]
Net Loss Per Share	10. Net Loss Per Share The following table sets forth the computation of the Company’s basic and diluted net loss per share attributable to common stockholders, which excludes shares which are legally outstanding, but subject to repurchase by the Company (in thousands, except share and per share amounts): Three Months Ended June 30, Six Months Ended June 30, 2024 2023 2024 2023 Numerator: Net loss $ ( 21,195 ) $ ( 18,057 ) $ ( 32,006 ) $ ( 35,037 ) Denominator: Weighted average common shares outstanding 38,164,856 37,851,141 38,141,318 37,826,508 Weighted average common stock outstanding subject to repurchase related to unvested early exercised stock options and restricted stock awards ( 36,512 ) ( 100,748 ) ( 42,935 ) ( 109,117 ) Weighted average common shares outstanding - basic and 38,128,344 37,750,393 38,098,383 37,717,391 Net loss per share attributable to common stockholders, basic $ ( 0.56 ) $ ( 0.48 ) $ ( 0.84 ) $ ( 0.93 ) Potentially dilutive shares to be issued under the ESPP as of June 30, 2024 and 2023 were not included in the calculation of diluted net loss per share because they would be anti-dilutive and were immaterial. In addition, potential dilutive securities not included in the calculation of diluted net loss per share because to do so would be anti-dilutive are as follows (in common stock equivalent shares): As of June 30, 2024 2023 Common stock options issued and outstanding 12,601,974 10,794,785 Common stock outstanding subject to repurchase related to 25,025 89,300 Total 12,626,999 10,884,085

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2024
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed financial statements as of June 30, 2024 and for the three and six months ended June 30, 2024 and 2023 have been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) for interim financial information and pursuant to applicable rules and regulations of the SEC regarding interim financial reporting. Accordingly, they do not include all of the information and notes required by U.S. GAAP for complete financial statements. These unaudited condensed financial statements include only normal and recurring adjustments, which are normal in nature, that the Company believes are necessary to a fair statement of the Company’s financial position and the results of its operations and cash flows. The balance sheet as of December 31, 2023 was derived from the audited financial statements as of that date. These interim financial results are not necessarily indicative of results to be expected for the full year or any other period. These unaudited condensed financial statements and the notes accompanying them should be read in conjunction with the Company’s Annual Report on Form 10-K for the year ended December 31, 2023 .
Risks and Uncertainties	Risks and Uncertainties The Company is subject to a number of risks similar to other early-stage biopharmaceutical companies, including, but not limited to, changes in any of the following areas that the Company believes could have a material adverse effect on its future financial position or results of operations: risks related to the successful discovery and development of its product candidates, ability to raise additional capital, development of new technological innovations by its competitors, delay or inability to obtain chemical or biological intermediates from such suppliers required for the synthesis of the Company’s product candidates, protection of intellectual property rights, litigation or claims against the Company based on intellectual property rights, and regulatory clearance and market acceptance of the Company’s products. Global economic and business activities continue to face widespread macroeconomic uncertainties, including pandemics, labor shortages, inflation and monetary supply shifts, recession risks and potential disruptions from major geopolitical conflicts. The Company continues to actively monitor the impact of these macroeconomic factors on its financial condition, liquidity, operations, and workforce. The extent of the impact of these factors on the Company’s operational and financial performance, including its ability to execute its business strategies and initiatives in the expected time frame, will depend on future developments, which are uncertain and cannot be predicted; however, any continued or renewed disruption resulting from these factors could negatively impact the Company’s business. The Company relies on single source manufacturers and suppliers for the supply of its product candidates. Disruption from these manufacturers or suppliers would have a negative impact on the Company’s business, financial position, and results of operations.
Liquidity	Liquidity The Company has incurred net losses and negative cash flows from operations since its inception and anticipates continuing to incur net losses for the foreseeable future. As of June 30, 2024 , the Company had cash and cash equivalents and marketable securities of $ 97.5 million and an accumulated deficit of $ 396.3 million. Based upon the Company's current operating plans, the Company believes that its existing cash, cash equivalents and marketable securities will be sufficient to fund its operations for at least the next 12 months following the issuance date of this Quarterly Report on Form 10-Q. The Company will need to raise additional capital to continue the advancement of its programs. In the near term, the Company's primary uses of cash will be to fund the completion of key milestones for clinical programs and to fund its operations, including research and development activities and employee salaries. This includes significant costs relating to clinical trials and manufacture of the Company's product candidates. The Company's uses of cash in the long term will be similar as the Company advances its research and development activities and pays employee salaries. Most pharmaceutical products require larger clinical trials as development progresses, and the Company expects its funding requirements to grow with the advancement of its programs. The Company's long-term funding requirements will depend on many factors, which are uncertain but include its portfolio prioritization decisions and the success of its collaborations. In turn, the Company's ability to raise additional capital through equity or partnering will depend on the general economic environment in which it operates and its ability to achieve key milestones.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, and the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. On an ongoing basis, the Company evaluates its estimates and assumptions, including those related to revenue recognition, stock-based compensation, restructuring costs, long-lived assets impairment assessment, and accrued 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 may differ materially from those estimates.
Restructuring Charges	Restructuring Charges Restructuring charges consist primarily of employee severance, contract termination costs and other costs. Liabilities for costs associated with a restructuring activity are recognized when the liability is incurred and are measured at fair value. For one-time employee terminations benefits, the Company recognizes the liability in full on the communication date when future services are not required or amortizes the liability ratably over the service period, if required. The fair value of termination benefits reflects the Company’s estimate of expected utilization of certain Company-funded post-employment benefits. One-time termination benefits include severance, continuation of health insurance coverage for certain employees, and other company funded benefits.
Long-lived assets Impairment assessment	Long-lived Assets Impairment Assessment Long-lived assets, including operating lease assets, are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. The recoverability of assets to be held and used is measured by a comparison of the carrying amount of the asset group to future net cash flows estimated by the Company to be generated by such assets. If such asset group is considered to be impaired, the impairment to be recognized is the amount by which the carrying amount of the asset group exceeds the fair value of the asset group. During the three months ended June 30, 2024 , the Company performed an evaluation of the impact of the May 2024 announcement and restructuring plan on the carrying value of its long-lived assets and concluded that there was no impairment charge to be recognized on the long-lived assets.
Allowance for Credit Losses	Allowance for Credit Losses For available-for-sale securities in an unrealized loss position, the Company first assesses whether it intends to sell, or if it is more likely than not that the Company will be required to sell, the security before recovery of its amortized cost basis. If either of the criteria regarding intent or requirement to sell is met, the security’s amortized cost basis is written down to fair value through earnings. For available-for-sale securities that do not meet the aforementioned criteria, the Company evaluates whether the decline in fair value has resulted from credit losses or other factors. In making this assessment, the Company considers the severity of the impairment, any changes in interest rates, market conditions, changes to the underlying credit ratings and forecasted recovery, among other factors. The credit-related portion of unrealized losses, and any subsequent improvements, are recorded in interest income through an allowance account. Any impairment that has not been recorded through an allowance for credit losses is included in other comprehensive income (loss) on the statements of operations and comprehensive loss. The Company elected the practical expedient to exclude the applicable accrued interest from both the fair value and amortized costs basis of its available-for-sale securities for purposes of identifying and measuring an impairment. Accrued interest receivable on available-for-sale securities is recorded within cash and cash equivalents on the Company's condensed balance sheets. The Company's accounting policy is to not measure an allowance for credit loss for accrued interest receivable and to write-off any uncollectible accrued interest receivable as a reversal of interest income in a timely manner, which the Company considers to be in the period in which it determines the accrued interest will not be collected by the Company.
Concentrations of Credit Risk	Concentrations of Credit Risk Financial instruments that potentially subject the Company to concentration of credit risk consist of cash, cash equivalents and marketable securities. As of June 30, 2024 and December 31, 2023 , most of the Company’s funds were invested with a registered investment manager and custodied at one financial institution, with operating cash kept at a separate financial institution, and account balances may at times exceed federally insured limits. Management believes that the Company is not subject to unusual or significant credit risk beyond the normal credit risk associated with commercial banking relationships.
Net Loss Per Share	Net Loss Per Share Basic net loss per share is calculated by dividing the net loss by the weighted-average number of shares of common stock outstanding during the period, without consideration for potentially dilutive securities. Diluted net loss per share is computed by dividing the net loss by the weighted-average number of common stock and potentially dilutive securities outstanding for the period. For purposes of the diluted net loss per share calculation, convertible preferred stock, stock options, common stock subject to repurchase related to unvested restricted stock awards and early exercise of stock options are considered potentially dilutive securities. Basic and diluted net loss per share is presented in conformity with the two-class method required for participating securities as the convertible preferred stock is considered a participating security because it participates in dividends with common stock. The Company also considers the shares issued upon the early exercise of stock options subject to repurchase to be participating securities because holders of such shares have non-forfeitable dividend rights in the event a dividend is paid on common stock. The holders of all series of convertible preferred stock and the holders of early exercised shares subject to repurchase do not have a contractual obligation to share in the Company’s losses. As such, the net loss was attributed entirely to common stockholders. Because the Company has reported a net loss for all periods presented, diluted net loss per share is the same as basic net loss per share for all periods presented as potentially dilutive securities were anti-dilutive.
Recent Accounting Standards	Recent Accounting Standards From time to time, new accounting standards are issued by the Financial Accounting Standards Board (the “FASB”), or other standard setting bodies and adopted by the Company as of the specified effective date. Unless otherwise discussed, the impact of recently issued standards that are not yet effective will not have a material impact on the Company’s financial position or results of operations upon adoption. In November 2023, the FASB issued ASU 2023-07 Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures (“ASU 2023-07”), which requires entities to disclose incremental segment information on an annual and interim basis. ASU 2023-07 requires entities with a single reportable segment to provide all the disclosures required by the amendments in ASU 2023-07 and all existing segment disclosures in Segment Reporting (Topic 280). ASU 2023-07 is effective for annual periods beginning on January 1, 2024, and interim periods beginning on January 1, 2025. The Company does not expect the adoption of ASU 2023-07 to have a material impact on its financial statements and related disclosures. In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures (“ASU 2023-09”). ASU 2023-09 requires enhanced annual disclosures regarding the rate reconciliation and income taxes paid information. ASU 2023-09 is effective for annual periods beginning on January 1, 2025 and may be adopted on a prospective or retrospective basis. Early adoption is permitted. The Company is evaluating the impact of this guidance on its financial statements and related disclosures.

Fair Value Measurements and F_2

Fair Value Measurements and Fair Value of Financial Instruments (Tables)	6 Months Ended
	Jun. 30, 2024
Fair Value Disclosures [Abstract]
Schedule of Marketable Securities Classified as Available-for-sale Securities	Marketable securities, all of which are classified as available-for-sale securities, consisted of the following at June 30, 2024 and December 31, 2023 (in thousands): June 30, 2024 Amortized Unrealized Unrealized Estimated Cost Gains Losses Fair Value Asset-backed securities $ 24,982 $ 3 $ ( 12 ) $ 24,973 U.S. treasury securities 25,730 — ( 13 ) 25,717 Other government agency securities 6,481 — ( 11 ) 6,470 Commercial paper 7,986 — ( 5 ) 7,981 Corporate debt securities 29,157 9 ( 15 ) 29,151 Total $ 94,336 $ 12 $ ( 56 ) $ 94,292 December 31, 2023 Amortized Unrealized Unrealized Estimated Cost Gains Losses Fair Value Asset-backed securities $ 17,347 $ 10 $ ( 15 ) $ 17,342 U.S. treasury securities 43,924 34 ( 11 ) 43,947 Other government agency securities 13,371 — ( 15 ) 13,356 Commercial paper 20,351 4 ( 10 ) 20,345 Corporate debt securities 22,763 41 ( 2 ) 22,802 Total $ 117,756 $ 89 $ ( 53 ) $ 117,792
Schedule of gross unrealized losses and fair value of Company's available-for-sale securities	The tables below show the gross unrealized losses and fair value of the Company's available-for-sale securities with unrealized losses that are not deemed to have credit losses (in thousands), aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position at June 30, 2024 and December 31, 2023, respectively: June 30, 2024 Less Than 12 Months More Than 12 Months Total Estimated Unrealized Estimated Unrealized Estimated Unrealized Fair Value Losses Fair Value Losses Fair Value Losses Asset-backed securities $ 6,485 $ ( 2 ) $ 18,488 $ ( 10 ) $ 24,973 $ ( 12 ) U.S. treasury securities 14,839 ( 6 ) 10,878 ( 7 ) 25,717 ( 13 ) Other government agency securities — — 6,470 ( 11 ) 6,470 ( 11 ) Commercial paper 7,981 ( 5 ) — — 7,981 ( 5 ) Corporate debt securities 18,816 ( 8 ) 10,335 ( 7 ) 29,151 ( 15 ) Total $ 48,121 $ ( 21 ) $ 46,171 $ ( 35 ) $ 94,292 $ ( 56 ) December 31, 2023 Less Than 12 Months More Than 12 Months Total Estimated Unrealized Estimated Unrealized Estimated Unrealized Fair Value Losses Fair Value Losses Fair Value Losses Asset-backed securities $ 4,686 $ — $ 12,656 $ ( 15 ) $ 17,342 $ ( 15 ) U.S. treasury securities 34,104 — 9,843 ( 11 ) 43,947 ( 11 ) Other government agency securities 2,477 ( 1 ) 10,879 ( 14 ) 13,356 ( 15 ) Commercial paper 20,345 ( 10 ) — — 20,345 ( 10 ) Corporate debt securities 9,566 ( 1 ) 13,236 ( 1 ) 22,802 ( 2 ) Total $ 71,178 $ ( 12 ) $ 46,614 $ ( 41 ) $ 117,792 $ ( 53 )
Schedule of Fair Values of Assets and Liabilities Measured at Fair Value on Recurring Basis	As of June 30, 2024 and December 31, 2023, the fair values of the Company’s assets, which are measured at fair value on a recurring basis, were determined using the following inputs (in thousands): June 30, 2024 Total (Level 1) (Level 2) (Level 3) Money market funds $ 1,990 $ 1,990 $ — $ — Asset-backed securities 24,973 — 24,973 — U.S. treasury securities 25,717 6,422 19,295 — Other government agency securities 6,470 — 6,470 — Commercial paper 7,981 — 7,981 — Corporate debt securities 29,151 — 29,151 — Total $ 96,282 $ 8,412 $ 87,870 $ — December 31, 2023 Total (Level 1) (Level 2) (Level 3) Money market funds $ 8,641 $ 8,641 $ — $ — Asset-backed securities 17,342 — 17,342 — U.S. treasury securities 43,947 33,001 10,946 — Other government agency securities 13,356 — 13,356 — Commercial paper 20,345 — 20,345 — Corporate debt securities 22,802 — 22,802 — Total $ 126,433 $ 41,642 $ 84,791 $ —

Balance Sheet Components (Table

Balance Sheet Components (Tables)	6 Months Ended
	Jun. 30, 2024
Balance Sheet Related Disclosures [Abstract]
Property and Equipment, Net	Property and equipment, net, consist of the following (in thousands): June 30, December 31, Laboratory equipment $ 10,075 $ 10,038 Office equipment 386 386 Leasehold improvements 286 285 Total property and equipment 10,747 10,709 Less accumulated depreciation and amortization ( 6,668 ) ( 5,752 ) Total $ 4,079 $ 4,957
Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consist of the following (in thousands): June 30, December 31, Accrued research and development $ 4,019 $ 6,092 Accrued compensation 2,889 5,820 Accrued restructuring charges 2,900 — Accrued other 446 574 Total $ 10,254 $ 12,486

Collaborations (Tables)

Collaborations (Tables)	6 Months Ended
	Jun. 30, 2024
Toray Development Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Schedule of Changes in Contract Liability	The following table presents changes in the Company contract liability (in thousands): Balance at December 31, 2023 $ 1,502 Addition—amount billed or accrued for research and development services 285 Revenue recognized ( 814 ) Balance at June 30, 2024 $ 973
Genmab Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Schedule of Changes in Contract Liability	The following table presents changes in the Company contract liability (in thousands): Balance at December 31, 2023 $ 6,664 Addition—amount billed for research and development services 1,169 Revenue recognized ( 2,263 ) Balance at June 30, 2024 $ 5,570
Innovent Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Schedule of Changes in Contract Liability	The following table presents changes in the Company contract liability (in thousands): Balance at December 31, 2023 $ 3,142 Addition—amount billed for research and development services 331 Revenue recognized ( 3,473 ) Balance at June 30, 2024 $ —

Commitment and Contingencies (T

Commitment and Contingencies (Tables)	6 Months Ended
	Jun. 30, 2024
Commitments and Contingencies Disclosure [Abstract]
Components of Lease Expense	The components of lease expense were as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2024 2023 2024 2023 Total operating lease cost $ 1,119 $ 1,119 $ 2,239 $ 2,239
Supplemental Cash Flow Information Related to Leases	Supplemental cash flow information related to leases was as follows (in thousands): Six Months Ended June 30, 2024 2023 Operating cash flows from operating leases $ 2,411 $ 2,332
Schedule by Year for Future Maturities of Operating Lease Liabilities and Sublease Income to be Received	The following is a schedule by year for future maturities of the Company’s operating lease liabilities and sublease income to be received as of June 30, 2024 (in thousands): Operating Leases Sublease Income 2024 $ 2,475 $ 183 2025 4,340 — 2026 3,484 — 2027 3,602 — 2028 3,724 — Thereafter 9,514 — Total minimum lease payments/sublease income 27,139 183 Less imputed interest ( 8,248 ) — Total $ 18,891 $ 183

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	6 Months Ended
	Jun. 30, 2024
Share-Based Payment Arrangement [Abstract]
Summary of Components of Stock-Based Compensation Expense Recognized	The following table summarizes the components of stock-based compensation expense recognized in the Company’s statement of operations and comprehensive loss (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2024 2023 2024 2023 Research and development $ 1,077 $ 905 $ 2,057 $ 1,931 General and administrative 1,748 1,445 3,070 2,895 Total $ 2,825 $ 2,350 $ 5,127 $ 4,826

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	6 Months Ended
	Jun. 30, 2024
Earnings Per Share [Abstract]
Computation of Basic and Diluted Net Loss per Share Attributable to Common Stockholders, which excludes Shares Legally Outstanding	The following table sets forth the computation of the Company’s basic and diluted net loss per share attributable to common stockholders, which excludes shares which are legally outstanding, but subject to repurchase by the Company (in thousands, except share and per share amounts): Three Months Ended June 30, Six Months Ended June 30, 2024 2023 2024 2023 Numerator: Net loss $ ( 21,195 ) $ ( 18,057 ) $ ( 32,006 ) $ ( 35,037 ) Denominator: Weighted average common shares outstanding 38,164,856 37,851,141 38,141,318 37,826,508 Weighted average common stock outstanding subject to repurchase related to unvested early exercised stock options and restricted stock awards ( 36,512 ) ( 100,748 ) ( 42,935 ) ( 109,117 ) Weighted average common shares outstanding - basic and 38,128,344 37,750,393 38,098,383 37,717,391 Net loss per share attributable to common stockholders, basic $ ( 0.56 ) $ ( 0.48 ) $ ( 0.84 ) $ ( 0.93 )
Potentially Dilutive Securities not Included in the Calculation of Diluted Net Loss per Share	In addition, potential dilutive securities not included in the calculation of diluted net loss per share because to do so would be anti-dilutive are as follows (in common stock equivalent shares): As of June 30, 2024 2023 Common stock options issued and outstanding 12,601,974 10,794,785 Common stock outstanding subject to repurchase related to 25,025 89,300 Total 12,626,999 10,884,085

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	3 Months Ended
	Jun. 30, 2024	Dec. 31, 2023
Accounting Policies [Abstract]
Cash and cash equivalents and marketable securities	$ 97,500,000
Accumulated deficit	(396,291,000)	$ (364,285,000)
Impairment charge to be recognized on the long-lived assets	$ 0

Fair Value Measurements and F_3

Fair Value Measurements and Fair Value of Financial Instruments - Additional Information (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Fair value, asset, transfers into level 3	$ 0	$ 0	$ 0	$ 0
Fair value, asset, transfers out of level 3	0	0	0	0
Fair value, liability, transfers into level 3	0	0	0	0
Fair value, liability, transfers out of level 3	0	$ 0	0	$ 0
Allowance for credit losses	0		0
Accrued interest receivable on available-for-sale securities	$ 400,000		$ 400,000		$ 300,000

Fair Value Measurements and F_4

Fair Value Measurements and Fair Value of Financial Instruments - Schedule of Marketable Securities Classified as Available-for-sale Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	$ 94,336	$ 117,756
Unrealized Gains	12	89
Unrealized Losses	(56)	(53)
Estimated Fair Value	94,292	117,792
Asset Backed Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	24,982	17,347
Unrealized Gains	3	10
Unrealized Losses	(12)	(15)
Estimated Fair Value	24,973	17,342
U.S. Treasury Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	25,730	43,924
Unrealized Gains	0	34
Unrealized Losses	(13)	(11)
Estimated Fair Value	25,717	43,947
Other Government Agency Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	6,481	13,371
Unrealized Losses	(11)	(15)
Estimated Fair Value	6,470	13,356
Commercial Paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	7,986	20,351
Unrealized Gains	0	4
Unrealized Losses	(5)	(10)
Estimated Fair Value	7,981	20,345
Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	29,157	22,763
Unrealized Gains	9	41
Unrealized Losses	(15)	(2)
Estimated Fair Value	$ 29,151	$ 22,802

Fair Value Measurements and F_5

Fair Value Measurements and Fair Value of Financial Instruments - Schedule of gross unrealized losses and fair value of Company's available-for-sale securities (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Less Than 12 Months Estimated Fair Value	$ 48,121	$ 71,178
More Than 12 Months Estimated Fair Value	46,171	46,614
Total Estimated Fair Value	94,292	117,792
Less Than 12 Months Unrealized Losses	(21)	(12)
More Than 12 Months Unrealized Losses	(35)	(41)
Total Unrealized Losses	(56)	(53)
Asset Backed Securities
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Less Than 12 Months Estimated Fair Value	6,485	4,686
More Than 12 Months Estimated Fair Value	18,488	12,656
Total Estimated Fair Value	24,973	17,342
Less Than 12 Months Unrealized Losses	(2)
More Than 12 Months Unrealized Losses	(10)	(15)
Total Unrealized Losses	(12)	(15)
U.S. Treasury Securities
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Less Than 12 Months Estimated Fair Value	14,839	34,104
More Than 12 Months Estimated Fair Value	10,878	9,843
Total Estimated Fair Value	25,717	43,947
Less Than 12 Months Unrealized Losses	(6)
More Than 12 Months Unrealized Losses	(7)	(11)
Total Unrealized Losses	(13)	(11)
Other Government Agency Securities
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Less Than 12 Months Estimated Fair Value		2,477
More Than 12 Months Estimated Fair Value	6,470	10,879
Total Estimated Fair Value	6,470	13,356
Less Than 12 Months Unrealized Losses		(1)
More Than 12 Months Unrealized Losses	(11)	(14)
Total Unrealized Losses	(11)	(15)
Commercial Paper
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Less Than 12 Months Estimated Fair Value	7,981	20,345
Total Estimated Fair Value	7,981	20,345
Less Than 12 Months Unrealized Losses	(5)	(10)
Total Unrealized Losses	(5)	(10)
Corporate Debt Securities
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Less Than 12 Months Estimated Fair Value	18,816	9,566
More Than 12 Months Estimated Fair Value	10,335	13,236
Total Estimated Fair Value	29,151	22,802
Less Than 12 Months Unrealized Losses	(8)	(1)
More Than 12 Months Unrealized Losses	(7)	(1)
Total Unrealized Losses	$ (15)	$ (2)

Fair Value Measurements and F_6

Fair Value Measurements and Fair Value of Financial Instruments - Schedule of Fair Values of Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - Recurring Basis - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total asset	$ 96,282	$ 126,433
Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total asset	1,990	8,641
Asset Backed Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total asset	24,973	17,342
U.S. Treasury Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total asset	25,717	43,947
Other Government Agency Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total asset	6,470	13,356
Commercial Paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total asset	7,981	20,345
Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total asset	29,151	22,802
Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total asset	8,412	41,642
Level 1 | Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total asset	1,990	8,641
Level 1 | U.S. Treasury Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total asset	6,422	33,001
Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total asset	87,870	84,791
Level 2 | Asset Backed Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total asset	24,973	17,342
Level 2 | U.S. Treasury Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total asset	19,295	10,946
Level 2 | Other Government Agency Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total asset	6,470	13,356
Level 2 | Commercial Paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total asset	7,981	20,345
Level 2 | Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total asset	$ 29,151	$ 22,802

Balance Sheet Components - Prop

Balance Sheet Components - Property and Equipment, Net (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 10,747	$ 10,709
Less accumulated depreciation and amortization	(6,668)	(5,752)
Total	4,079	4,957
Laboratory Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	10,075	10,038
Office Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	386	386
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 286	$ 285

Balance Sheet Components - Addi

Balance Sheet Components - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Balance Sheet Related Disclosures [Abstract]
Depreciation expense	$ 0.4	$ 0.4	$ 0.9	$ 0.9

Balance Sheet Components - Accr

Balance Sheet Components - Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Balance Sheet Related Disclosures [Abstract]
Accrued research and development	$ 4,019	$ 6,092
Accrued compensation	2,889	5,820
Accrued restructuring charges	2,900
Accrued other	446	574
Total	$ 10,254	$ 12,486

Collaborations - Additional Inf

Collaborations - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended			3 Months Ended			6 Months Ended
	Mar. 31, 2024	May 31, 2021	Mar. 31, 2019	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration revenue				$ 1,275		$ 1,433	$ 6,549	$ 3,259
Toray Development Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Contract liability				973			973		$ 1,502
Contract liability, current				400			400
Contract liability, non-current				600			600
Collaboration revenue				200		0	800	0
Variable consideration related to reimbursements for research and development services			$ 1,900
Toray Development Agreement | Prepaid Expenses and Other Current Assets
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research and development services receivables							200
Genmab Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Contract liability				5,570			5,570		6,664
Upfront payment received		$ 10,000
Contract liability, current				1,600			1,600
Contract liability, non-current				4,000			4,000
Collaboration revenue				1,000		800	2,300	1,800
Allocated from stock purchase agreement		1,400
Variable consideration related to reimbursements for research and development services		28,600
Potential future sale milestone payments		$ 160,000
Genmab Agreement | Prepaid Expenses and Other Current Assets
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research and development services receivables							500
Genmab Agreement | Common Stock
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Common stock sold		821,045
Consideration in excess of fair value		$ 1,400
Purchase price under Stock Purchase Agreement		15,000
Genmab Agreement | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Potential future sale milestone payments		$ 125,000
Innovent Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Contract liability				0			0		$ 3,142
Upfront payment received	$ 5,000
Collaboration revenue				$ 0		$ 600	$ 3,500	$ 1,500
One-time payment receivable					$ 4,700
Deferred revenue	$ 2,500				2,500
Innovent Agreement | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Potential future sale milestone payments					112,700
Innovent Agreement | Other Income
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
One-time payment receivable					$ 4,700
Series T Convertible Preferred Stock | Toray Development Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Common stock sold			717,514
Consideration in excess of fair value			$ 1,500
Allocated from stock purchase agreement			$ 1,500

Collaborations - Schedule of Ch

Collaborations - Schedule of Changes in Contract Liability (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2024 USD ($)
Toray Development Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Beginning Balance	$ 1,502
Addition - amount billed for research and development services	285
Revenue recognized	(814)
Ending Balance	973
Genmab Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Beginning Balance	6,664
Addition - amount billed for research and development services	1,169
Revenue recognized	(2,263)
Ending Balance	5,570
Innovent Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Beginning Balance	3,142
Addition - amount billed for research and development services	331
Revenue recognized	(3,473)
Ending Balance	$ 0

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details)		1 Months Ended		3 Months Ended		6 Months Ended
	Aug. 07, 2020 USD ($) ft²	Aug. 31, 2022 ft²	Jun. 30, 2021 ft²	Jun. 30, 2024 USD ($)	Jun. 30, 2023 USD ($)	Jun. 30, 2024 USD ($) ft²	Jun. 30, 2023 USD ($)	Dec. 31, 2023
Commitments And Contingencies [Line Items]
Sublease income | $						$ 183,000
Weighted-average remaining lease term				6 years 4 months 24 days		6 years 4 months 24 days		6 years 8 months 12 days
Weighted-average discount rate				11.20%		11.20%		11.10%
Potential future milestone payments | $						$ 0
Chesapeake Master Lease
Commitments And Contingencies [Line Items]
Operating lease, area of property available	71,646
Operating lease, area of property, extension space available	25,956
Operating lease, area of property, additional space available	45,690
Operating lease, initial term of contract	10 years
Operating lease, option to extend	true
Operating lease, extended additional term	8 years
Tenant improvement allowance | $	$ 4,800,000
Operating lease, area of property subleased	10,000
Operating lease, area of property, additional space remaining			35,690
Sublease, area of property leased	10,000	11,655
Sublease expiration date	Aug. 31, 2022					Jul. 31, 2023
Increase decrease in operating lease sublease area of property leased		13,743
Sublease, area of property expected to be leased						10,500
Operating sublease, option to extend, description						The subtenant has an early termination option with the early termination date no earlier than September 30, 2024, and no option to extend the sublease term
Operating sublease, option to extend		false
Sublease income | $				$ 200,000	$ 200,000	$ 400,000	$ 400,000
Chesapeake Master Lease | Maximum
Commitments And Contingencies [Line Items]
Sublease expiration date		Sep. 30, 2024

Commitments and Contingencies_2

Commitments and Contingencies - Components of Lease Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
Total operating lease cost	$ 1,119	$ 1,119	$ 2,239	$ 2,239

Commitments and Contingencies_3

Commitments and Contingencies - Supplemental Cash Flow Information Related to Leases (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
Operating cash flows from operating leases	$ 2,411	$ 2,332

Commitments and Contingencies_4

Commitments and Contingencies - Schedule by Year for Future Maturities of Operating Lease Liabilities and Sublease Income to be Received (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2024 USD ($)
Operating Leases
Operating Leases, 2024	$ 2,475
Operating Leases, 2025	4,340
Operating Leases, 2026	3,484
Operating Leases, 2027	3,602
Operating Leases, 2028	3,724
Operating Leases, Thereafter	9,514
Operating Leases, Total minimum lease payments	27,139
Less imputed interest	(8,248)
Operating lease liabilities	18,891
Sublease Income
Sublease Income, 2024	183
Total Sublease Income	183
Sublease Income, Total	$ 183

Common Stock - Additional Infor

Common Stock - Additional Information (Details) - Shelf Registration and At-The-Market Equity Offering - USD ($) $ in Millions		6 Months Ended
	Mar. 30, 2022	Jun. 30, 2024
Common Stock
Class Of Warrant Or Right [Line Items]
Common stock sold		0
Maximum
Class Of Warrant Or Right [Line Items]
Aggregate offering price	$ 250
Cowen and Company, LLC ("Cowen") | Common Stock
Class Of Warrant Or Right [Line Items]
Percentage of gross proceeds from sale of common stock	3%
Cowen and Company, LLC ("Cowen") | Maximum | Common Stock
Class Of Warrant Or Right [Line Items]
Aggregate offering price	$ 75

Restructuring - Additional Info

Restructuring - Additional Information (Details) - USD ($)		3 Months Ended	6 Months Ended
	May 14, 2024	Jun. 30, 2024	Jun. 30, 2024
Restructuring Cost and Reserve [Line Items]
Number of positions to be reduced, percentage	50%
Expected restructuring cost	$ 3,600,000
Cash payments for restructuring		$ 0	$ 0
Non-cash settlements or adjustment		0	0
Restructuring reserve		$ 2,900,000	$ 2,900,000
One-time Termination Benefit, Employee Severance
Restructuring Cost and Reserve [Line Items]
Expected restructuring cost	2,900,000
Stock-based Compensation Modification
Restructuring Cost and Reserve [Line Items]
Expected restructuring cost	$ 700,000

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) - USD ($)			1 Months Ended			3 Months Ended		6 Months Ended
	Jul. 15, 2024	Dec. 31, 2022	Dec. 31, 2021	Jan. 31, 2021	Sep. 30, 2020	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Jan. 01, 2024
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense								$ 5,127,000	$ 4,826,000
Performance and Service Based Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares issued					526,018
Vesting period					48 months
Stock-based compensation expense						$ 14,000	$ 39,000	$ 31,000	$ 100,000
Weighted-average grant date fair value of awards								$ 3.24
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares issued			336,000
Vesting period			3 years
Weighted-average grant date fair value of awards			$ 4.51
Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock under employee stock purchase plan, Shares						124,591	118,566	124,591	118,566
2021 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for issuance										1,905,730
2021 Plan | Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares authorized for issuance				8,075,000
Percentage equal to number of shares of common stock outstanding		5%
2021 Plan | Consulting Agreements [Member] | Subsequent Event
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of stock options, canceled	1,615,713
2021 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage equal to number of shares of common stock outstanding		1%
Common stock reserved for issuance						840,000		840,000		381,146
Purchase price of stock as percentage of fair market value				85%
2021 Employee Stock Purchase Plan | Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares authorized for issuance				420,000
Plan offering period				2 years
Issuance of common stock under employee stock purchase plan, Shares								124,591	118,566
2021 Employee Stock Purchase Plan | Common Stock | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of eligible compensation for payroll deductions to purchase stock				15%

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Components of Stock-Based Compensation Expense Recognized (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 2,825	$ 2,350	$ 5,127	$ 4,826
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	1,077	905	2,057	1,931
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 1,748	$ 1,445	$ 3,070	$ 2,895

Net Loss Per Share - Computatio

Net Loss Per Share - Computation of Basic and Diluted Net Loss per Share Attributable to Common Stockholders, which excludes Shares Legally Outstanding (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Numerator:
Net loss	$ (21,195)	$ (18,057)	$ (32,006)	$ (35,037)
Denominator:
Weighted average common shares outstanding	38,164,856	37,851,141	38,141,318	37,826,508
Weighted average common stock outstanding subject to repurchase related to unvested early exercised stock options and restricted stock awards	(36,512)	(100,748)	(42,935)	(109,117)
Weighted average common shares outstanding - basic	38,128,344	37,750,393	38,098,383	37,717,391
Weighted average common shares outstanding - diluted	38,128,344	37,750,393	38,098,383	37,717,391
Net loss per share attributable to common stockholders, basic	$ (0.56)	$ (0.48)	$ (0.84)	$ (0.93)
Net loss per share attributable to common stockholders, diluted	$ (0.56)	$ (0.48)	$ (0.84)	$ (0.93)

Net Loss Per Share - Potentiall

Net Loss Per Share - Potentially Dilutive Securities not Included in the Calculation of Diluted Net Loss per Share (Details) - shares	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities not included in the calculation of diluted net loss per share	12,626,999	10,884,085
Common Stock Options Issued and Outstanding
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities not included in the calculation of diluted net loss per share	12,601,974	10,794,785
Common Stock Outstanding Subject to Repurchase Related to Unvested Early Exercised Stock Options and Restricted Stock Awards
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities not included in the calculation of diluted net loss per share	25,025	89,300