Prelude Therapeutics (PRLD) 10-Q7 May 242024 Q1 Quarterly reportFinancial data

Company Profile

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2024	May 01, 2024
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2024
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q1
Trading Symbol	PRLD
Entity Registrant Name	PRELUDE THERAPEUTICS INC
Entity Central Index Key	0001678660
Entity Current Reporting Status	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Common Stock, Shares Outstanding		54,929,567
Entity Shell Company	false
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Security Exchange Name	NASDAQ
Entity Interactive Data Current	Yes
Entity File Number	001-39527
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	81-1384762
Entity Address, Address Line One	175 Innovation Boulevard
Entity Address, City or Town	Wilmington
Entity Address, State or Province	DE
Entity Address, Postal Zip Code	19805
City Area Code	302
Local Phone Number	467-1280
Document Quarterly Report	true
Document Transition Report	false

BALANCE SHEETS (UNAUDITED)

BALANCE SHEETS (UNAUDITED) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 24,707	$ 25,291
Marketable securities	177,217	207,644
Prepaid expenses and other current assets	3,442	2,654
Total current assets	205,366	235,589
Restricted cash	4,044	4,044
Property and equipment, net	7,294	7,325
Right-of-use asset	30,107	30,412
Other assets	295	295
Total assets	247,106	277,665
Current liabilities:
Accounts payable	5,308	4,580
Accrued expenses and other current liabilities	10,147	15,768
Operating lease liability	2,188	1,481
Total current liabilities	17,643	21,829
Other liabilities	3,277	3,339
Operating lease liability	15,452	15,407
Total liabilities	36,372	40,575
Commitments (Note 8)
Stockholders’ equity:
Additional paid-in capital	698,785	693,252
Accumulated other comprehensive (loss) income	(235)	223
Accumulated deficit	(487,821)	(456,390)
Total stockholders’ equity	210,734	237,090
Total liabilities and stockholders’ equity	247,106	277,665
Voting Common Stock
Stockholders’ equity:
Common stock	4	4
Non-voting Common Stock
Stockholders’ equity:
Common stock	$ 1	$ 1

BALANCE SHEETS (PARENTHETICAL)

BALANCE SHEETS (PARENTHETICAL) (UNAUDITED) - $ / shares	Mar. 31, 2024	Dec. 31, 2023
Voting Common Stock
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	487,149,741	487,149,741
Common stock, shares, issued	42,071,505	42,063,995
Common stock, shares, outstanding	42,071,505	42,063,995
Non-voting Common Stock
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	12,850,259	12,850,259
Common stock, shares, issued	12,850,259	12,850,259
Common stock, shares, outstanding	12,850,259	12,850,259

STATEMENTS OF OPERATIONS AND CO

STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Operating expenses:
Research and development	$ 27,409	$ 21,834
General and administrative	6,934	7,281
Total operating expenses	34,343	29,115
Loss from operations	(34,343)	(29,115)
Other income, net	2,912	1,397
Net loss	$ (31,431)	$ (27,718)
Per share information:
Net loss per share of common stock, basic	$ (0.42)	$ (0.58)
Net loss per share of common stock, diluted	$ (0.42)	$ (0.58)
Weighted average common shares outstanding, basic	75,735,954	47,737,190
Weighted average common shares outstanding, diluted	75,735,954	47,737,190
Comprehensive loss
Net loss	$ (31,431)	$ (27,718)
Unrealized (loss) gain on marketable securities, net of tax	(458)	1,294
Comprehensive loss	$ (31,889)	$ (26,424)

STATEMENTS OF CHANGES IN STOCKH

STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (UNAUDITED) - USD ($) $ in Thousands	Total	Common Stock Voting Common Stock	Common Stock Non-voting Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit
Beginning balance at Dec. 31, 2022	$ 195,437	$ 4	$ 1	$ 531,682	$ (1,692)	$ (334,558)
Beginning balance (shares) at Dec. 31, 2022		36,496,994	11,402,037
Issuance of common stock upon exercise of stock options & vesting of RSUs	28			28
Issuance of common stock upon exercise of stock options & vesting of RSUs, (shares)		17,224
Unrealized gain (loss) on marketable securities, net of tax	1,294				1,294
Stock-based compensation expense	6,256			6,256
Net loss	(27,718)					(27,718)
Ending balance at Mar. 31, 2023	175,297	$ 4	$ 1	537,966	(398)	(362,276)
Ending balance (shares) at Mar. 31, 2023		36,514,218	11,402,037
Beginning balance at Dec. 31, 2023	237,090	$ 4	$ 1	693,252	223	(456,390)
Beginning balance (shares) at Dec. 31, 2023		42,063,995	12,850,259
Issuance of common stock upon exercise of stock options & vesting of RSUs	(14)			(14)
Issuance of common stock upon exercise of stock options & vesting of RSUs, (shares)		7,510
Unrealized gain (loss) on marketable securities, net of tax	(458)				(458)
Stock-based compensation expense	5,547			5,547
Net loss	(31,431)					(31,431)
Ending balance at Mar. 31, 2024	$ 210,734	$ 4	$ 1	$ 698,785	$ (235)	$ (487,821)
Ending balance (shares) at Mar. 31, 2024		42,071,505	12,850,259

STATEMENTS OF CHANGES IN STOC_2

STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (UNAUDITED) (PARENTHETICAL)	3 Months Ended
	Mar. 31, 2024 shares
Statement of Stockholders' Equity [Abstract]
Shares withheld for employee taxes	4,285

STATEMENTS OF CASH FLOWS (UNAUD

STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Cash flows used in operating activities:
Net loss	$ (31,431)	$ (27,718)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	426	278
Noncash lease expense	414	432
Stock-based compensation	5,547	6,256
Amortization of premium and discount on marketable securities, net	(1,541)	(446)
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(788)	(355)
Accounts payable	631	374
Accrued expenses and other liabilities	(5,692)	(1,903)
Long-term prepaid expenses and other long-term assets		(6,610)
Operating lease liabilities	643	(442)
Net cash used in operating activities	(31,791)	(30,134)
Cash flows provided by investing activities:
Purchases of marketable securities	(5,490)	(7,191)
Proceeds from maturities of marketable securities	37,000	26,000
Purchases of property and equipment	(289)	(810)
Net cash provided by investing activities	31,221	17,999
Cash flows used in financing activities:
Payment of offering costs		(297)
Proceeds from the issuance of common stock in connection with the exercise of stock options	2	28
Payment of withholding taxes related to stock-based compensation to employees	(16)
Net cash used in financing activities	(14)	(269)
Net decrease in cash, cash equivalents and restricted cash	(584)	(12,404)
Cash, cash equivalents, and restricted cash at beginning of period	29,335	34,649
Cash, cash equivalents, and restricted cash at end of period	28,751	22,245
Supplemental disclosures:
Operating lease right-of-use assets obtained in exchange for operating lease liabilities	109
Property and equipment in accounts payable and accrued expenses and other current liabilities	269	21
Unrealized (loss) gain on marketable securities	$ (458)	$ 1,294

Background

Background	3 Months Ended
Background	Mar. 31, 2024
Background [Abstract]
Background	1. Background Prelude Therapeutics Incorporated (the “Company”) is a clinical-stage fully integrated oncology company built on a foundation of drug discovery excellence to deliver novel precision cancer medicines to underserved patients. Since beginning operations in 2016, the Company has devoted substantially all its efforts to research and development, conducting preclinical and clinical studies, recruiting management and technical staff, administration, and raising capital.

Risks and Liquidity

Risks and Liquidity	3 Months Ended
Risks and Liquidity	Mar. 31, 2024
Risks And Liquidity [Abstract]
Risks and Liquidity	2. Risks and liquidity The Company faces a number of risks common to early-stage companies in the biotechnology industry. Principal among these risks are the uncertainties in the development process, development of the same or similar technological innovations by competitors, protection of proprietary technology, dependence on key personnel, compliance with government regulations and approval requirements, and the need to obtain additional financing to fund operations. Product candidates currently under development will require significant additional research and development efforts, including extensive preclinical and clinical testing and regulatory approval, prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel infrastructure, and extensive compliance-reporting capabilities. There can be no assurance that the Company’s research and development will be successfully completed, adequate protection for the Company’s technology will be obtained, any products developed will obtain necessary government regulatory approval, or any approved products will be commercially viable. The Company operates in an environment of rapid change in technology and substantial competition from pharmaceutical and biotechnology companies. Since its inception, the Company has incurred operating losses and had an accumulated deficit of $ 487.8 million at March 31, 2024. The Company has no revenue to-date and devotes its efforts to research and development. The Company anticipates incurring additional losses until such time, if ever, that it can generate significant sales of its product candidates currently in development. The Company believes its cash, cash equivalents, and marketable securities as of March 31, 2024 will be sufficient to fund its operating expenses and capital expenditure requirements for at least the next twelve months from the filing date of this Quarterly Report on Form 10-Q. To fund its operating expenses and capital expenditure requirements after that date, the Company plans to seek additional funding through public or private equity offerings, debt financings, collaborations, strategic alliances and licensing arrangements. The Company may not be able to obtain financing on acceptable terms, or at all, and the Company may not be able to enter into strategic alliances or other arrangements on favorable terms, or at all. The terms of any financing may adversely affect the holdings or the rights of the Company’s stockholders. If the Company is unable to obtain funding, it could be required to delay, reduce or eliminate research and development programs, product portfolio expansion or future commercialization efforts, which could adversely affect its business prospects.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
Summary of Significant Accounting Policies	Mar. 31, 2024
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	3. Summary of significant accounting policies The summary of significant accounting policies included in the Company’s financial statements for the year ended December 31, 2023 can be found in “Note 3. Summary of significant accounting policies” of the Company’s Annual Report on Form 10-K filed with the Securities and Exchange Commission (the “SEC”) on February 15, 2024. Those policies have not materially changed. Basis of presentation The accompanying unaudited interim financial statements have been prepared in accordance with generally accepted accounting principles (“GAAP”) for interim financial information, the instructions to Form 10-Q and Article 10 of Regulation S-X. They do not include all of the information and notes required by GAAP for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation have been included. Operating results for the three months ended March 31, 2024 are not necessarily indicative of the results that may be expected for the year ending December 31, 2024. The accompanying unaudited interim financial statements should be read in conjunction with the annual audited financial statements and related notes as of and for the year ended December 31, 2023 found in the Company's Annual Report on Form 10-K filed with the SEC on February 15, 2024. Any reference in these notes to applicable guidance is meant to refer to GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Updates (“ASU”) of the Financial Accounting Standards Board (“FASB”). Use of estimates The preparation of the unaudited interim financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and contingent liabilities at the date of the unaudited interim financial statements and the reported amounts of expenses during the reporting period. Actual results could differ from those estimates. Estimates and assumptions are periodically reviewed, and the effects of the revisions are reflected in the accompanying unaudited interim financial statements in the period they are determined to be necessary. The most significant estimate relates to accrued clinical trial expenses. Income taxes Based upon the historical and anticipated future losses, management has determined that the deferred tax assets generated by net operating losses and research and development credits do not meet the more likely than not threshold for realizability. Accordingly, a full valuation allowance has been recorded against the Company’s net deferred tax assets as of March 31, 2024 and December 31, 2023. Cash, Cash Equivalents and Restricted cash The Company’s cash equivalents include short-term highly liquid investments with an original maturity of 90 days or less when purchased and are carried at fair value in the accompanying balance sheets. Restricted cash consists of a letter of credit for the benefit of the landlord in connection with the Company’s Chestnut Run Lease. See Note 8 for further details. The following table provides a reconciliation of cash and cash equivalents and restricted cash reported within the balance sheet that total to the amounts shown in the statement of cash flows: (in thousands) March 31, December 31, Cash and cash equivalents $ 24,707 $ 25,291 Restricted cash 4,044 4,044 Total cash, cash equivalents, and restricted cash shown in statement of cash flows $ 28,751 $ 29,335 Marketable Securities The Company’s marketable securities consist of investments in corporate debt securities, United States (“U.S.”) government debt securities, and agency securities that are classified as available-for-sale. The securities are carried at fair value with the unrealized gains and losses, net of tax, included in accumulated other comprehensive loss, a component of stockholders’ equity. Realized gains and losses as well as credit losses, if any, on marketable securities are included in the Company’s statements of operations. The Company classifies marketable securities that are available for use in current operations as current assets on the balance sheets. Net Loss Per Share Basic net loss per share of common stock is computed by dividing net loss by the weighted-average number of shares of common stock outstanding during each period, including pre-funded warrants to purchase shares of common stock. The weighted-average number of shares of common stock outstanding used in the basic net loss per share calculation does not include unvested restricted stock awards as these instruments are considered contingently issuable shares until they vest. Diluted net loss per share of common stock includes the effect, if any, from the potential exercise of securities, such as stock options, and the effect from unvested restricted stock awards and restricted stock units which would result in the issuance of incremental shares of common stock. For diluted net loss per share, the weighted-average number of shares of common stock is the same for basic net loss per share due to the fact that when a net loss exists, dilutive securities are not included in the calculation as the impact is anti-dilutive. The Company’s unvested restricted stock awards entitle the holder to participate in dividends and earnings of the Company, and, if the Company were to recognize net income, it would have to use the two-class method to calculate earnings per share. The two-class method is not applicable during periods with a net loss, as the holders of the unvested restricted stock awards have no obligation to fund losses. The following potentially dilutive securities have been excluded from the computation of diluted weighted-average shares of common stock outstanding, as they would be anti-dilutive: March 31, 2024 2023 Unvested restricted stock awards — 131,468 Unvested restricted stock units 93,125 163,750 Stock options 14,737,740 11,868,020 Employee stock purchase plan 50,941 51,837 14,881,806 12,215,075 Amounts in the above table reflect the common stock equivalents. Recently Issued Accounting Pronouncements Emerging Growth Company Status The Company is an emerging growth company, as defined in the Jumpstart Our Business Startups Act of 2012 (the “JOBS Act”). Under the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards issued subsequent to the enactment of the JOBS Act, until such time as those standards apply to private companies. The Company has elected to use this extended transition period for complying with new or revised accounting standards that have different effective dates for public and private companies until the earlier of the date that it (i) is no longer an emerging growth company or (ii) affirmatively and irrevocably opts out of the extended transition period provided in the JOBS Act. As a result, these unaudited interim financial statements may not be comparable to companies that comply with the new or revised accounting pronouncements as of public company effective dates. Accounting guidance not yet adopted In November 2023, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU"), 2023-07, Segment Reporting (Topic 280) – Improvements to Reportable Segment Disclosures. This ASU expands segment disclosures by requiring disclosure of significant segment expenses that are regularly provided to the chief operating decision maker and included within each reported measure of segment profit or loss, an amount for other segment items and a description of its composition, and interim disclosures of a reportable segment’s profit or loss and assets. The disclosures required under ASU 2023-07 are also required for public entities with a single reportable segment. The amendments in this ASU are effective for fiscal years beginning after December 15, 2023 and interim periods within fiscal years beginning after December 15, 2024. Early adoption is permitted. The Company is currently evaluating the impact of this standard but does not expect that it will have a material impact on the financial statements and related disclosures. In December 2023, the FASB issued ASU 2023-09, Income Taxes - Improvements to Income Tax Disclosures. ASU 2023-09 requires enhanced income tax disclosures related to the rate reconciliation and income taxes paid information. For public business entities, the amendments in this ASU are effective for annual periods beginning after December 15, 2024 with early adoption permitted. The Company is currently evaluating the impact of this standard but does not expect that it will have a material impact on the financial statements and related disclosures.

Marketable Securities

Marketable Securities	3 Months Ended
Marketable Securities	Mar. 31, 2024
Investments, Debt and Equity Securities [Abstract]
Marketable Securities	4. Marketable Securities The following provides detail of the Company's marketable securities. (in thousands) Amortized Cost Gross unrealized gain Gross unrealized loss Fair Value March 31, 2024 Marketable securities: Agency securities $ 10,566 $ — $ ( 6 ) $ 10,560 Corporate debt securities 66,059 20 ( 90 ) 65,989 U.S. government securities 100,827 — ( 159 ) 100,668 Total marketable securities $ 177,452 $ 20 $ ( 255 ) $ 177,217 December 31, 2023 Marketable securities: Agency securities $ 10,431 $ 19 $ — $ 10,450 Corporate debt securities 67,806 193 ( 20 ) 67,979 U.S. government securities 129,184 72 ( 41 ) 129,215 Total marketable securities $ 207,421 $ 284 $ ( 61 ) $ 207,644 The Company’s marketable securities generally have contractual maturity dates of 22 months or less. As of March 31, 2024 , the Company had 44 securities with a total fair market value of $ 166.3 million in an unrealized loss position. The Company believes any unrealized losses associated with the decline in value of its securities is temporary and is primarily related to market factors. Furthermore, the Company believes it is more likely than not that it will be able to hold its marketable securities to maturity. Therefore, the Company anticipates a full recovery of the amortized cost basis of its marketable securities at maturity and an allowance for credit losses was not recognized.

Fair Value of Financial Instrum

Fair Value of Financial Instruments	3 Months Ended
Fair Value of Financial Instruments	Mar. 31, 2024
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	5. Fair Value of Financial Instruments Fair value is the price that could be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. Fair value determination in accordance with applicable accounting guidance requires that a number of significant judgments be made. Additionally, fair value is used on a nonrecurring basis to evaluate assets for impairment or as required for disclosure purposes by applicable accounting guidance on disclosures about fair value of financial instruments. Depending on the nature of the assets and liabilities, various valuation techniques and assumptions are used when estimating fair value. The Company follows the provisions of ASC 820, Fair Value Measurement, for financial assets and liabilities measured on a recurring basis. The guidance requires fair value measurements be classified and disclosed in one of the following three categories: • Level 1: Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities. • Level 2: Quoted prices in markets that are not active, or inputs which are observable, either directly or indirectly, for substantially the full term of the asset or liabilities. • Level 3: Prices or valuation techniques that require inputs that are both significant to the fair value measurement and unobservable (i.e., supported by little or no market activity). The following fair value hierarchy table presents information about the Company’s assets and liabilities measured at fair value on a recurring basis: Fair value measurement at reporting date using (in thousands) Quoted prices Significant Significant March 31, 2024 Assets Cash equivalents: Money Market Funds $ 23,063 $ — $ — Marketable securities: Agency securities — 10,560 — Corporate debt securities — 65,989 — U.S. government securities — 100,668 — Total marketable securities — 177,217 — Total financial assets $ 23,063 $ 177,217 $ — December 31, 2023 Assets Cash equivalents: Money Market Funds $ 24,369 $ — $ — Marketable securities: Agency securities $ — $ 10,450 $ — Corporate debt securities — 67,979 — U.S. government securities — 129,215 — Total marketable securities — 207,644 — Total financial assets $ 24,369 $ 207,644 $ —

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	3 Months Ended
Accrued Expenses and Other Current Liabilities	Mar. 31, 2024
Payables and Accruals [Abstract]
Accrued Expenses and Other Current Liabilities	6. Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities consisted of the following: (in thousands) March 31, December 31, Compensation and related benefits $ 3,640 $ 9,157 Research and development 5,707 5,666 Other 800 945 $ 10,147 $ 15,768

Common Stock

Common Stock	3 Months Ended
Common Stock	Mar. 31, 2024
Equity [Abstract]
Common Stock	7. Common Stock The Company has two classes of common stock: “voting common stock” and “non-voting common stock.” The holders of the voting common stock are entitled to one vote for each share of voting common stock held at all meetings of stockholders . Except as otherwise required by law, the holders of non-voting common stock shall not be entitled to vote at any meetings of stockholders (or written actions in lieu of meetings) and the shares of non-voting common stock shall not be included in determining the number of shares voting or entitled to vote on any matter. Unless required by law, there shall be no cumulative voting. Any holder of non-voting common stock may elect to convert each share of non-voting common stock into one fully paid and non-assessable share of voting common stock at any time by providing written notice to the Company; provided that as a result of such conversion, such holder, together with its affiliates and any members of a Schedule 13(d) group with such holder, would not beneficially own in excess of 9.99 % of the Company’s common stock immediately prior to and following such conversion, unless otherwise as expressly provided for in the Company’s restated certificate of incorporation. However, this ownership limitation may be increased (not to exceed 19.99 %) or decreased to any other percentage designated by such holder of non-voting common stock upon 61 days’ notice to the Company. Open Market Sales Agreement In March 2023, in connection with filing a prospectus supplement to its Shelf Registration Statement, the Company entered into an Open Market Sales Agreement (the Sales Agreement) with Jefferies LLC, as the sales agent, pursuant to which the Company may offer and sell shares of its common stock having an aggregate offering amount of up to $ 75.0 million. The $ 75.0 million of common stock that may be issued and sold pursuant to the Sales Agreement is included in the $ 400.0 million of securities that may be issued and sold pursuant to the Shelf Registration Statement. The Company will pay Jefferies LLC a commission rate of up to 3.0 % of the aggregate gross proceeds from the sale of any shares of common stock pursuant to the Sales Agreement. At March 31, 2024, there was $ 75.0 million remaining under the Sales Agreement. 2023 financings During the second quarter of 2023, the Company sold 6,761,200 shares of its common stock which comprised of (i) 5,312,978 shares of its voting common stock and (ii) 1,448,222 shares of its non-voting common stock at a price of $ 5.75 per share and to certain investors in lieu of common stock, the Company sold pre-funded warrants to purchase 12,895,256 shares of voting common stock at a price of $ 5.7499 per pre-funded warrant, resulting in gross proceeds to the Company of $ 113.0 million. Of the voting common stock issued, 2,264,456 shares were purchased by the Company’s underwriters in connection with a 30-day option at a price of $ 5.75 per share. Offering costs of $ 2.6 million, of which $ 0.3 million were previously paid and deferred, were recorded to additional paid-in capital in the accompanying balance sheets, resulting in net proceeds of $ 110.4 million. During the fourth quarter of 2023, the Company sold in a private placement pre-funded warrants to purchase 7,936,759 shares of voting common stock at a price of $ 3.1499 per pre-funded warrant, resulting in net proceeds of $ 24.8 million after deducting offering costs of $ 0.2 million. The purchase price per share of each pre-funded warrant represents the per share offering price for the common stock, minus the $ 0.0001 per share exercise price of such pre-funded warrant. As of March 31, 2024 , no pre-funded warrants had been exercised. The pre-funded warrants were classified as a component of permanent stockholders’ equity within additional paid-in capital and were recorded at the issuance date using a relative fair value allocation method. The pre-funded warrants are equity classified because they (i) are freestanding financial instruments that are legally detachable and separately exercisable from the equity instruments, (ii) are immediately exercisable, (iii) do not embody an obligation for the Company to repurchase its shares, (iv) permit the holders to receive a fixed number of shares of common stock upon exercise, (v) are indexed to the Company’s common stock and (vi) meet the equity classification criteria. In addition, such pre-funded warrants do not provide any guarantee of value or return. The Company did not conduct any financings during the first quarter of 2024.

Commitments

Commitments	3 Months Ended
Commitments	Mar. 31, 2024
Commitments and Contingencies Disclosure [Abstract]
Commitments	8. Commitments Leases The Company leases office and laboratory space in Wilmington, Delaware under a noncancelable lease (the “Chestnut Run Lease”). The premises include approximately 81,000 rentable square feet and has an initial term of 162 months with 3 five-year extension options and certain expansion rights. Neither the option to extend nor the expansion rights were recognized as part of the Company's measurement of the right-of-use ("ROU") asset and operating lease liability as of March 31, 2024. Under the terms of the Chestnut Run Lease, the landlord provided an allowance towards the cost of completing tenant improvements for the premises. The Company concluded that the improvements resulting from both the landlord's build-out and the tenant improvements are the landlord's assets for accounting purposes. Costs incurred by the Company related to tenant improvements in excess of the landlord's allowance were treated as prepaid rent and increased the right-of-use asset on the commencement date. The discount rate used to account for the Company’s operating lease under ASC 842, Leases, was the Company’s estimated incremental borrowing rate on the commencement date of 15.0 %. The Company's incremental borrowing rate reflects a collateralized borrowing with a similar term and amount as the Chestnut Run Lease. Lease cost for the three months ended March 31, 2024 and 2023 was $ 1.1 million and $ 0.5 million, respectively. Cash paid for amounts included in the measurement of operating lease liabilities for the three months ended March 31, 2024 and 2023 was nil and $ 0.5 million, respectively. The remaining lease term of the Chestnut Run Lease is 13.2 years and future minimum annual lease payments at March 31, 2024 are as follows: (in thousands) 2024 (remaining) $ 1,747 2025 2,746 2026 2,979 2027 3,054 2028 3,130 2029 3,209 Thereafter 26,427 Total undiscounted lease payments 43,292 Less imputed interest ( 25,652 ) Current lease liability $ 17,640 The Company paid a security deposit for the Chestnut Run Lease in the form of a letter of credit of $ 4.0 million, which is included in the accompanying balance sheet as restricted cash as of March 31, 2024 . The security deposit may be reduced to $ 0.5 million over time in accordance with the terms of the Chestnut Run Lease. In connection with the Company’s expansion of operations in the State of Delaware, the Company was approved for a grant from the State of Delaware in 2021 that will provide up to $ 5.5 million in reimbursements over three years for the development of lab space in addition to increasing jobs in Delaware to meet specific targeted levels through 2023 . During the third quarter of 2022, the Company was approved for an additional grant from the State of Delaware for the development of lab space in the amount of $ 1.0 million. In 2022, the Company received cash of $ 3.4 million from the grants for the development of lab space. The Company has met the minimum requirements stated in the grant agreement in order to not be required to pay back any portion of the $ 3.4 million disbursed. The Company deferred the recognition of these grant funds as they relate to capitalized costs and has classified them as long-term liabilities in the accompanying balance sheet. The Company recognizes the grant funds in other income as grant income over the length of the lease term. Additionally, if the Company leaves the State of Delaware within five years of the disbursement, the Company is required to return an amount equal to the amount of grant funds disbursed on a pro-rated basis. Employment Agreements The Company entered into employment agreements with key personnel providing for compensation and severance in certain circumstances, as defined in the respective employment agreements. 401(k) Defined Contribution Plan The Company sponsors a 401(k) defined‑contribution plan covering all employees. Participants are permitted to contribute up to 100 % of their eligible annual pretax compensation up to an established federal limit on aggregate participant contributions. The Company provides a match of a maximum amount of 3 % of the participant’s compensation. For both the three months ended March 31, 2024 and 2023, the Company made matching contributions of $ 0.2 million. Research Collaboration Agreement In 2023, the Company entered into a multi-year, multi-program agreement with AbCellera Biologics Incorporated ("AbCellera") to jointly discover, develop, and commercialize novel oncology medicines for up to five programs. Under the terms of the agreement, AbCellera will lead manufacturing activities and the Company will lead clinical development and global commercialization, subject to AbCellera’s option to co-promote any resulting commercial products in the United States. If, at any point one party in the collaboration opts-out of future co-development cost sharing, that party will be entitled to a royalty from commercialization of the collaboration target, dependent on the proportion of their co-development contributions compared to the total development costs of a target as defined within the agreement. The Company concluded that the agreement with AbCellera will be accounted for under the scope of ASC 808, Collaborative Arrangements, as both parties will actively participate in joint operating activities and are exposed to significant risks and rewards. Under ASC 808, certain transactions between collaborative arrangement participants should follow the accounting for revenue under ASC 606, Revenue from Contracts with Customers, when the collaborative arrangement participant is a customer for a distinct good or service. The Company determined that co-development arrangement as defined in our agreement with AbCellera does not meet the definition of a customer as defined by ASC 606. As a result, these activities will be accounted for as research and development costs. Costs related to the AbCellera collaboration were not material for the three months ended March 31, 2024. Other Research and Development Arrangements The Company enters into agreements with clinical research organizations ("CROs") to assist in the performance of research and development activities. Expenditures to CROs represent a significant cost in clinical development for the Company.

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
Stock-Based Compensation	Mar. 31, 2024
Share-Based Payment Arrangement [Abstract]
Stock-Based Compensation	9. Stock-Based Compensation The Company has two equity incentive plans: the 2016 Equity Incentive Plan, as amended, and the 2020 Equity Incentive Plan. New awards can only be granted under the 2020 Equity Incentive Plan (the “Plan”) and as of March 31, 2024 , 4,904,812 shares were available for future grants. The number of shares of the Company’s common stock that may be issued pursuant to rights granted under the Plan shall automatically increase on January 1st of each year and continuing for ten years beginning on January 1, 2021, in an amount equal to five percent of the total number of shares of the Company’s common stock outstanding on December 31st of the preceding calendar year, subject to the discretion of the Company's board of directors or compensation committee to determine a lesser number of shares shall be added for such year. On January 1, 2024, 2,745,712 shares were added to the Plan. The Plan provides for the granting of common stock, incentive stock options, nonqualified stock options, restricted stock awards, restricted stock units and/or stock appreciation rights to employees, directors, and other persons, as determined by the Company’s board of directors. The Company’s stock options vest based on the terms in each award agreement, generally over four-year periods with 25 % of options vesting after one year and then monthly thereafter, and have a term of ten years . The Company measures stock-based awards at their grant-date fair value and records compensation expense on a straight-line basis over the vesting period of the awards. The Company recorded stock-based compensation expense in the following expense categories in its accompanying statements of operations: Three Months Ended (in thousands) 2024 2023 Research and development $ 3,010 $ 2,991 General and administrative 2,537 3,265 $ 5,547 $ 6,256 Stock Options The following table summarizes stock option activity for the periods indicated: Number Weighted Weighted Outstanding at January 1, 2024 11,898,446 $ 10.60 7.77 Granted 3,071,300 $ 4.58 Exercised ( 1,170 ) $ 1.89 Forfeited ( 230,836 ) $ 15.66 Outstanding at March 31, 2024 14,737,740 $ 9.27 8.02 Exercisable at March 31, 2024 7,001,612 $ 11.15 6.93 At March 31, 2024 , the aggregate intrinsic value of outstanding options and exercisable options was $ 6.4 million and $ 5.8 million, respectively. The following table summarizes information about stock options outstanding at March 31, 2024 under the Plan: Options Outstanding Options Exercisable Range of Exercise Prices Number Weighted Average Weighted Number Weighted $ 0.31 - $ 4.56 2,290,135 6.06 $ 2.13 1,975,983 $ 1.82 $ 4.57 - $ 5.00 4,041,027 9.51 4.65 538,800 4.82 $ 5.01 - $ 10.34 3,689,654 8.74 6.72 1,058,642 6.74 $ 10.35 - $ 88.98 4,716,924 7.12 18.68 3,428,187 18.89 14,737,740 7,001,612 The weighted-average grant date fair value of options granted was $ 3.40 and $ 5.12 per option for the three months ended March 31, 2024 and 2023 , respectively. The Company recorded stock-based compensation expense of $ 5.3 million and $ 5.9 million for the three months ended March 31, 2024 and 2023, respectively, related to stock options. As of March 31, 2024 , the total unrecognized compensation expense related to unvested stock option awards was $ 40.9 million, which the Company expects to recognize over a weighted-average period of 2.31 years. The fair value of each option was estimated on th e date of grant using the weighted average assumptions in the table below: Three months ended 2024 2023 Expected volatility 85.12 % 83.55 % Risk-free interest rate 4.14 % 3.80 % Expected life (in years) 6.07 6.05 Expected dividend yield — — Restricted Stock Awards and Units The Company issues restricted stock awards (“RSA”) to employees that generally vest over a four-year period with 25 % of awards vesting after one year and then monthly thereafter. Any unvested shares will be forfeited upon termination of services. The fair value of an RSA is equal to the fair market value price of the Company’s common stock on the date of grant. RSA expense is recorded on a straight-line basis over the vesting period. The following table summarizes activity related to RSA stock-based payment awards: Number of Weighted-average Unvested balance at January 1, 2024 27,008 $ 3.26 Vested ( 27,008 ) $ 3.26 Unvested balance at March 31, 2024 — $ — The Company recorded stock-based compensation expense of $ 0.1 million and $ 0.2 million for the three months ended March 31, 2024 and 2023, respectively, related to RSAs. As of March 31, 2024 , there was no unrecognized expense related to RSAs. The Company granted restricted stock units (“RSU”) to employees that generally vest over a four-year period with 25 % of awards vesting after one year and then quarterly thereafter. Any unvested units will be forfeited upon termination of services. The following table summarizes activity related to RSU stock-based payment awards: Number of Weighted-average Unvested balance at January 1, 2024 103,750 $ 6.16 Vested ( 10,625 ) $ 6.44 Unvested balance at March 31, 2024 93,125 $ 6.12 The Company recorded stock-based compensation expense of $ 0.1 million for both the three months ended March 31, 2024 and 2023, related to RSUs. At March 31, 2024 , the total unrecognized expense related to the RSUs was $ 0.5 million, which the Company expects to recognize over 1.87 years. Employee Stock Purchase Plan The Company has an Employee Stock Purchase Plan (the “ESPP”), which, as of March 31, 2024 , had 2,168,434 shares of common stock reserved for future issuance. The number of shares of the Company’s common stock that may be issued pursuant to rights granted under the ESPP shall automatically increase on January 1st of each year and continuing for ten years beginning in 2021, in an amount equal to one percent of the total number of shares of all classes of the Company’s common stock outstanding on December 31st of the preceding calendar year, subject to the discretion of the Company's board of directors or compensation committee to determine a lesser number of shares shall be added for such year. On January 1, 2024, 549,142 shares were added to the ESPP. Under the ESPP, eligible employees can purchase the Company’s common stock through accumulated payroll deductions at such times as are established by the Company's compensation committee. Eligible employees may purchase the Company’s common stock at 85 % of the lower of the fair market value of the Company’s common stock on the first day of the offering period or on the last day of the offering period. Eligible employees may contribute up to 15 % of their eligible compensation. Under the ESPP, a participant may not accrue rights to purchase more than $ 25,000 worth of the Company’s common stock for each calendar year in which such right is outstanding. The ESPP is considered compensatory under the FASB stock compensation rules. Accordingly, share-based compensation expense is determined based on the option’s grant-date fair value as estimated by applying the Black Scholes option-pricing model and is recognized over the withholding period. The Company recognized share-based compensation expense of $ 0.1 million for each of the three months ended March 31, 2024 and 2023 , related to the ESPP.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
Summary of Significant Accounting Policies (Policies)	Mar. 31, 2024
Accounting Policies [Abstract]
Basis of presentation	Basis of presentation The accompanying unaudited interim financial statements have been prepared in accordance with generally accepted accounting principles (“GAAP”) for interim financial information, the instructions to Form 10-Q and Article 10 of Regulation S-X. They do not include all of the information and notes required by GAAP for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation have been included. Operating results for the three months ended March 31, 2024 are not necessarily indicative of the results that may be expected for the year ending December 31, 2024. The accompanying unaudited interim financial statements should be read in conjunction with the annual audited financial statements and related notes as of and for the year ended December 31, 2023 found in the Company's Annual Report on Form 10-K filed with the SEC on February 15, 2024. Any reference in these notes to applicable guidance is meant to refer to GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Updates (“ASU”) of the Financial Accounting Standards Board (“FASB”).
Use of estimates	Use of estimates The preparation of the unaudited interim financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and contingent liabilities at the date of the unaudited interim financial statements and the reported amounts of expenses during the reporting period. Actual results could differ from those estimates. Estimates and assumptions are periodically reviewed, and the effects of the revisions are reflected in the accompanying unaudited interim financial statements in the period they are determined to be necessary. The most significant estimate relates to accrued clinical trial expenses.
Income taxes	Income taxes Based upon the historical and anticipated future losses, management has determined that the deferred tax assets generated by net operating losses and research and development credits do not meet the more likely than not threshold for realizability. Accordingly, a full valuation allowance has been recorded against the Company’s net deferred tax assets as of March 31, 2024 and December 31, 2023.
Cash, Cash Equivalents and Restricted Cash	Cash, Cash Equivalents and Restricted cash The Company’s cash equivalents include short-term highly liquid investments with an original maturity of 90 days or less when purchased and are carried at fair value in the accompanying balance sheets. Restricted cash consists of a letter of credit for the benefit of the landlord in connection with the Company’s Chestnut Run Lease. See Note 8 for further details. The following table provides a reconciliation of cash and cash equivalents and restricted cash reported within the balance sheet that total to the amounts shown in the statement of cash flows: (in thousands) March 31, December 31, Cash and cash equivalents $ 24,707 $ 25,291 Restricted cash 4,044 4,044 Total cash, cash equivalents, and restricted cash shown in statement of cash flows $ 28,751 $ 29,335
Marketable Securities	Marketable Securities The Company’s marketable securities consist of investments in corporate debt securities, United States (“U.S.”) government debt securities, and agency securities that are classified as available-for-sale. The securities are carried at fair value with the unrealized gains and losses, net of tax, included in accumulated other comprehensive loss, a component of stockholders’ equity. Realized gains and losses as well as credit losses, if any, on marketable securities are included in the Company’s statements of operations. The Company classifies marketable securities that are available for use in current operations as current assets on the balance sheets.
Net Loss Per Share	Net Loss Per Share Basic net loss per share of common stock is computed by dividing net loss by the weighted-average number of shares of common stock outstanding during each period, including pre-funded warrants to purchase shares of common stock. The weighted-average number of shares of common stock outstanding used in the basic net loss per share calculation does not include unvested restricted stock awards as these instruments are considered contingently issuable shares until they vest. Diluted net loss per share of common stock includes the effect, if any, from the potential exercise of securities, such as stock options, and the effect from unvested restricted stock awards and restricted stock units which would result in the issuance of incremental shares of common stock. For diluted net loss per share, the weighted-average number of shares of common stock is the same for basic net loss per share due to the fact that when a net loss exists, dilutive securities are not included in the calculation as the impact is anti-dilutive. The Company’s unvested restricted stock awards entitle the holder to participate in dividends and earnings of the Company, and, if the Company were to recognize net income, it would have to use the two-class method to calculate earnings per share. The two-class method is not applicable during periods with a net loss, as the holders of the unvested restricted stock awards have no obligation to fund losses. The following potentially dilutive securities have been excluded from the computation of diluted weighted-average shares of common stock outstanding, as they would be anti-dilutive: March 31, 2024 2023 Unvested restricted stock awards — 131,468 Unvested restricted stock units 93,125 163,750 Stock options 14,737,740 11,868,020 Employee stock purchase plan 50,941 51,837 14,881,806 12,215,075 Amounts in the above table reflect the common stock equivalents.
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements Emerging Growth Company Status The Company is an emerging growth company, as defined in the Jumpstart Our Business Startups Act of 2012 (the “JOBS Act”). Under the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards issued subsequent to the enactment of the JOBS Act, until such time as those standards apply to private companies. The Company has elected to use this extended transition period for complying with new or revised accounting standards that have different effective dates for public and private companies until the earlier of the date that it (i) is no longer an emerging growth company or (ii) affirmatively and irrevocably opts out of the extended transition period provided in the JOBS Act. As a result, these unaudited interim financial statements may not be comparable to companies that comply with the new or revised accounting pronouncements as of public company effective dates. Accounting guidance not yet adopted In November 2023, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU"), 2023-07, Segment Reporting (Topic 280) – Improvements to Reportable Segment Disclosures. This ASU expands segment disclosures by requiring disclosure of significant segment expenses that are regularly provided to the chief operating decision maker and included within each reported measure of segment profit or loss, an amount for other segment items and a description of its composition, and interim disclosures of a reportable segment’s profit or loss and assets. The disclosures required under ASU 2023-07 are also required for public entities with a single reportable segment. The amendments in this ASU are effective for fiscal years beginning after December 15, 2023 and interim periods within fiscal years beginning after December 15, 2024. Early adoption is permitted. The Company is currently evaluating the impact of this standard but does not expect that it will have a material impact on the financial statements and related disclosures. In December 2023, the FASB issued ASU 2023-09, Income Taxes - Improvements to Income Tax Disclosures. ASU 2023-09 requires enhanced income tax disclosures related to the rate reconciliation and income taxes paid information. For public business entities, the amendments in this ASU are effective for annual periods beginning after December 15, 2024 with early adoption permitted. The Company is currently evaluating the impact of this standard but does not expect that it will have a material impact on the financial statements and related disclosures.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	3 Months Ended
Summary of Significant Accounting Policies (Tables)	Mar. 31, 2024
Accounting Policies [Abstract]
Schedule of Reconciliation of Cash and Cash Equivalents and Restricted Cash	The following table provides a reconciliation of cash and cash equivalents and restricted cash reported within the balance sheet that total to the amounts shown in the statement of cash flows: (in thousands) March 31, December 31, Cash and cash equivalents $ 24,707 $ 25,291 Restricted cash 4,044 4,044 Total cash, cash equivalents, and restricted cash shown in statement of cash flows $ 28,751 $ 29,335
Schedule of Potentially Dilutive Securities Excluded from Computation of Diluted Weighted-average Shares of Common Stock Outstanding	The following potentially dilutive securities have been excluded from the computation of diluted weighted-average shares of common stock outstanding, as they would be anti-dilutive: March 31, 2024 2023 Unvested restricted stock awards — 131,468 Unvested restricted stock units 93,125 163,750 Stock options 14,737,740 11,868,020 Employee stock purchase plan 50,941 51,837 14,881,806 12,215,075

Marketable Securities (Tables)

Marketable Securities (Tables)	3 Months Ended
Marketable Securities (Tables)	Mar. 31, 2024
Investments, Debt and Equity Securities [Abstract]
Schedule of Marketable Securities	The following provides detail of the Company's marketable securities. (in thousands) Amortized Cost Gross unrealized gain Gross unrealized loss Fair Value March 31, 2024 Marketable securities: Agency securities $ 10,566 $ — $ ( 6 ) $ 10,560 Corporate debt securities 66,059 20 ( 90 ) 65,989 U.S. government securities 100,827 — ( 159 ) 100,668 Total marketable securities $ 177,452 $ 20 $ ( 255 ) $ 177,217 December 31, 2023 Marketable securities: Agency securities $ 10,431 $ 19 $ — $ 10,450 Corporate debt securities 67,806 193 ( 20 ) 67,979 U.S. government securities 129,184 72 ( 41 ) 129,215 Total marketable securities $ 207,421 $ 284 $ ( 61 ) $ 207,644

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	3 Months Ended
Fair Value of Financial Instruments (Tables)	Mar. 31, 2024
Fair Value Disclosures [Abstract]
Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis	The following fair value hierarchy table presents information about the Company’s assets and liabilities measured at fair value on a recurring basis: Fair value measurement at reporting date using (in thousands) Quoted prices Significant Significant March 31, 2024 Assets Cash equivalents: Money Market Funds $ 23,063 $ — $ — Marketable securities: Agency securities — 10,560 — Corporate debt securities — 65,989 — U.S. government securities — 100,668 — Total marketable securities — 177,217 — Total financial assets $ 23,063 $ 177,217 $ — December 31, 2023 Assets Cash equivalents: Money Market Funds $ 24,369 $ — $ — Marketable securities: Agency securities $ — $ 10,450 $ — Corporate debt securities — 67,979 — U.S. government securities — 129,215 — Total marketable securities — 207,644 — Total financial assets $ 24,369 $ 207,644 $ —

Accrued Expenses and Other Cu_2

Accrued Expenses and Other Current Liabilities (Tables)	3 Months Ended
Accrued Expenses and Other Current Liabilities (Tables)	Mar. 31, 2024
Payables and Accruals [Abstract]
Schedule of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consisted of the following: (in thousands) March 31, December 31, Compensation and related benefits $ 3,640 $ 9,157 Research and development 5,707 5,666 Other 800 945 $ 10,147 $ 15,768

Commitments (Tables)

Commitments (Tables)	3 Months Ended
Commitments (Tables)	Mar. 31, 2024
Chestnut Run Lease
Schedule of Future Minimum Annual Lease Payments Under Lease	The remaining lease term of the Chestnut Run Lease is 13.2 years and future minimum annual lease payments at March 31, 2024 are as follows: (in thousands) 2024 (remaining) $ 1,747 2025 2,746 2026 2,979 2027 3,054 2028 3,130 2029 3,209 Thereafter 26,427 Total undiscounted lease payments 43,292 Less imputed interest ( 25,652 ) Current lease liability $ 17,640

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
Stock-Based Compensation (Tables)	Mar. 31, 2024
Share-Based Payment Arrangement [Abstract]
Schedule of Stock-Based Compensation Expense Recorded in Statements of Operations	The Company recorded stock-based compensation expense in the following expense categories in its accompanying statements of operations: Three Months Ended (in thousands) 2024 2023 Research and development $ 3,010 $ 2,991 General and administrative 2,537 3,265 $ 5,547 $ 6,256
Summary of Stock Option Activity	The following table summarizes stock option activity for the periods indicated: Number Weighted Weighted Outstanding at January 1, 2024 11,898,446 $ 10.60 7.77 Granted 3,071,300 $ 4.58 Exercised ( 1,170 ) $ 1.89 Forfeited ( 230,836 ) $ 15.66 Outstanding at March 31, 2024 14,737,740 $ 9.27 8.02 Exercisable at March 31, 2024 7,001,612 $ 11.15 6.93
Summary of Information about Stock Options Outstanding	The following table summarizes information about stock options outstanding at March 31, 2024 under the Plan: Options Outstanding Options Exercisable Range of Exercise Prices Number Weighted Average Weighted Number Weighted $ 0.31 - $ 4.56 2,290,135 6.06 $ 2.13 1,975,983 $ 1.82 $ 4.57 - $ 5.00 4,041,027 9.51 4.65 538,800 4.82 $ 5.01 - $ 10.34 3,689,654 8.74 6.72 1,058,642 6.74 $ 10.35 - $ 88.98 4,716,924 7.12 18.68 3,428,187 18.89 14,737,740 7,001,612
Schedule of Fair Value of Each Option Estimated on Date of Grant Using Weighted Average Assumptions	The fair value of each option was estimated on th e date of grant using the weighted average assumptions in the table below: Three months ended 2024 2023 Expected volatility 85.12 % 83.55 % Risk-free interest rate 4.14 % 3.80 % Expected life (in years) 6.07 6.05 Expected dividend yield — —
Summary of Activity related to RSA Stock-Based Payment Awards	The following table summarizes activity related to RSA stock-based payment awards: Number of Weighted-average Unvested balance at January 1, 2024 27,008 $ 3.26 Vested ( 27,008 ) $ 3.26 Unvested balance at March 31, 2024 — $ —
Summary of Activity related to RSU Stock-Based Payment Awards	The following table summarizes activity related to RSU stock-based payment awards: Number of Weighted-average Unvested balance at January 1, 2024 103,750 $ 6.16 Vested ( 10,625 ) $ 6.44 Unvested balance at March 31, 2024 93,125 $ 6.12

Risks and Liquidity - Additiona

Risks and Liquidity - Additional Information (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Risks And Liquidity [Abstract]
Accumulated deficit	$ (487,821)	$ (456,390)

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Schedule of Reconciliation of Cash and Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Accounting Policies [Abstract]
Cash and cash equivalents	$ 24,707	$ 25,291
Restricted cash	4,044	4,044
Total cash, cash equivalents, and restricted cash shown in statement of cash flows	$ 28,751	$ 29,335

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Schedule of Potentially Dilutive Securities Excluded from Computation of Diluted Weighted-average Shares of Common Stock Outstanding (Details) - shares	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	14,881,806	12,215,075
Unvested Restricted Stock Awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share		131,468
Unvested Restricted Stock Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	93,125	163,750
Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	14,737,740	11,868,020
Employee Stock Purchase Plan
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	50,941	51,837

Marketable Securities - Schedul

Marketable Securities - Schedule of Marketable Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Agency Securities
Marketable Securities [Line Items]
Marketable securities, Amortized cost	$ 10,566	$ 10,431
Marketable securities, Gross unrealized gain		19
Marketable securities, Gross unrealized loss	(6)
Marketable securities, Fair value	10,560	10,450
Corporate Debt Securities
Marketable Securities [Line Items]
Marketable securities, Amortized cost	66,059	67,806
Marketable securities, Gross unrealized gain	20	193
Marketable securities, Gross unrealized loss	(90)	(20)
Marketable securities, Fair value	65,989	67,979
U.S. Government Securities
Marketable Securities [Line Items]
Marketable securities, Amortized cost	100,827	129,184
Marketable securities, Gross unrealized gain		72
Marketable securities, Gross unrealized loss	(159)	(41)
Marketable securities, Fair value	100,668	129,215
Marketable Securities
Marketable Securities [Line Items]
Marketable securities, Amortized cost	177,452	207,421
Marketable securities, Gross unrealized gain	20	284
Marketable securities, Gross unrealized loss	(255)	(61)
Marketable securities, Fair value	$ 177,217	$ 207,644

Marketable Securities - Additio

Marketable Securities - Additional Information (Details) $ in Millions	Mar. 31, 2024 USD ($) Security
Investments, Debt and Equity Securities [Abstract]
Number of marketable securities \| Security	44
Securities fair market value unrealized loss position \| $	$ 166.3

Fair Value of Financial Instr_3

Fair Value of Financial Instruments - Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Agency Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value measurement, assets	$ 10,560	$ 10,450
Corporate Debt Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value measurement, assets	65,989	67,979
U.S. Government Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value measurement, assets	100,668	129,215
Recurring Basis \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value measurement, assets	23,063	24,369
Recurring Basis \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Money Market Funds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value measurement, assets	23,063	24,369
Recurring Basis \| Significant other observable inputs (Level 2)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value measurement, assets	177,217	207,644
Fair value measurement, assets	177,217	207,644
Recurring Basis \| Significant other observable inputs (Level 2) \| Agency Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value measurement, assets	10,560	10,450
Recurring Basis \| Significant other observable inputs (Level 2) \| Corporate Debt Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value measurement, assets	65,989	67,979
Recurring Basis \| Significant other observable inputs (Level 2) \| U.S. Government Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value measurement, assets	$ 100,668	$ 129,215

Accrued Expenses and Other Cu_3

Accrued Expenses and Other Current Liabilities - Summary of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Payables and Accruals [Abstract]
Compensation and related benefits	$ 3,640	$ 9,157
Research and development	5,707	5,666
Other	800	945
Accrued expenses and other current liabilities	$ 10,147	$ 15,768

Common Stock - Additional Infor

Common Stock - Additional Information (Details) - USD ($)	1 Months Ended	3 Months Ended
Common Stock - Additional Information (Details) - USD ($)	Mar. 31, 2023	Mar. 31, 2024	Dec. 31, 2023	Jun. 30, 2023
Class Of Stock [Line Items]
Amount of securities that may be issued and sold	$ 400,000,000
Gross proceeds from issuance of common stock and prefunded warrants				$ 113,000,000
Offering costs			$ 200,000	2,600,000
Offering costs previously paid and deferred				300,000
Net proceeds from issuance			$ 24,800,000	$ 110,400,000
Open Market Sales Agreement \| Jefferies LLC
Class Of Stock [Line Items]
Amount remaining under the sales agreement	75,000,000
Maximum \| Open Market Sales Agreement \| Jefferies LLC
Class Of Stock [Line Items]
Common stock aggregate offering amount	$ 75,000,000
Percentage of commission on gross proceeds from sale of common stock	3%
Pre-Funded Warrants
Class Of Stock [Line Items]
Warrants exercise price per share			$ 0.0001
Warrants exercised		0
Pre-Funded Warrants \| Voting Common Stock
Class Of Stock [Line Items]
Shares issued price per share				$ 5.7499
Warrants to purchase common stock				12,895,256
Pre-Funded Warrants \| Voting Common Stock \| Private Placement
Class Of Stock [Line Items]
Shares issued price per share			$ 3.1499
Warrants to purchase common stock			7,936,759
Common Stock
Class Of Stock [Line Items]
Common stock, voting rights		The holders of the voting common stock are entitled to one vote for each share of voting common stock held at all meetings of stockholders
Number of shares sold				6,761,200
Shares issued price per share				$ 5.75
Common Stock \| Minimum
Class Of Stock [Line Items]
Beneficial ownership percentage		9.99%
Common Stock \| Maximum
Class Of Stock [Line Items]
Beneficial ownership percentage		19.99%
Common Stock \| Voting Common Stock
Class Of Stock [Line Items]
Number of shares sold				5,312,978
Shares issued during period				2,264,456
Common Stock \| Non-voting Common Stock
Class Of Stock [Line Items]
Number of shares sold				1,448,222

Commitments - Additional Inform

Commitments - Additional Information (Details) $ in Millions	3 Months Ended
	Mar. 31, 2024 USD ($) ft² Extension	Mar. 31, 2023 USD ($)
Other Commitments [Line Items]
Lease cost	$ 1.1	$ 0.5
Cash paid in the measurement of operating lease liabilities	0	0.5
Reimbursements for development of lab space	$ 5.5
Reimbursements for development of lab space period	3 years
Reimbursements for development of lab space expiration year	2023
Additional grant for development of lab space	$ 1
Grant for development of lab space	3.4
Disbursement incurred costs for lab space	$ 3.4
Defined contribution plan, maximum annual contributions per employee, percent	100%
Defined contribution plan, employer matching contribution, percent of employee's gross pay	3%
Defined contribution plan, employer discretionary contribution amount	$ 0.2	$ 0.2
Chestnut Run Lease
Other Commitments [Line Items]
Lease renewal period	5 years
Area of lease premises \| ft²	81,000
Remaining lease term	13 years 2 months 12 days
Initial term of lease	162 months
Number of lease extensions \| Extension	3
Operating lease estimated incremental borrowing rate percent	15%
Chestnut Run Lease \| Letter of Credit
Other Commitments [Line Items]
Security deposit	$ 4
Chestnut Run Lease \| Letter of Credit \| Pro Forma
Other Commitments [Line Items]
Security deposit	$ 0.5

Commitments - Schedule of Futur

Commitments - Schedule of Future Minimum Annual Lease Payments Under Lease (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Lease Liability [Line Items]
Current lease liability	$ 2,188	$ 1,481
Chestnut Run Lease
Lease Liability [Line Items]
2024 (remaining)	1,747
2025	2,746
2026	2,979
2027	3,054
2028	3,130
2029	3,209
Thereafter	26,427
Total undiscounted lease payments	43,292
Less imputed interest	(25,652)
Current lease liability	$ 17,640

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details)	3 Months Ended
Stock-Based Compensation - Additional Information (Details)	Mar. 31, 2024 USD ($) Plan $ / shares shares	Mar. 31, 2023 USD ($) $ / shares	Jan. 01, 2024 shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of equity incentive plans \| Plan	2
Aggregate intrinsic value of outstanding options	$ 6,400,000
Aggregate intrinsic value of exercisable options	5,800,000
Stock-based compensation expense	$ 5,547,000	$ 6,256,000
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average grant date fair value of options granted \| $ / shares	$ 3.4	$ 5.12
Stock-based compensation expense	$ 5,300,000	$ 5,900,000
Total unrecognized compensation expense related to unvested stock option awards	$ 40,900,000
Total unrecognized compensation expense, weighted-average period	2 years 3 months 21 days
Restricted Stock Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period	4 years
Stock-based compensation expense	$ 100,000	200,000
Share-based payment arrangement, nonvested award, unrecognized expense	$ 0
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period	4 years
Stock-based compensation expense	$ 100,000	100,000
Total unrecognized compensation expense, weighted-average period	1 year 10 months 13 days
Share-based payment arrangement, nonvested award, unrecognized expense	$ 500,000
2020 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future grants \| shares	4,904,812
Terms of award	The number of shares of the Company’s common stock that may be issued pursuant to rights granted under the Plan shall automatically increase on January 1st of each year and continuing for ten years beginning on January 1, 2021, in an amount equal to five percent of the total number of shares of the Company’s common stock outstanding on December 31st of the preceding calendar year, subject to the discretion of the Company's board of directors or compensation committee to determine a lesser number of shares shall be added for such year. On January 1, 2024, 2,745,712 shares were added to the Plan.
Award term	10 years
Percentage of shares outstanding used to calculate annual increase in number of shares that can be issued	5%
Number of shares authorized \| shares			2,745,712
2020 Equity Incentive Plan \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period	4 years
2020 Equity Incentive Plan \| Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period	1 year
2020 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future grants \| shares	2,168,434
Terms of award	The number of shares of the Company’s common stock that may be issued pursuant to rights granted under the ESPP shall automatically increase on January 1st of each year and continuing for ten years beginning in 2021, in an amount equal to one percent of the total number of shares of all classes of the Company’s common stock outstanding on December 31st of the preceding calendar year, subject to the discretion of the Company's board of directors or compensation committee to determine a lesser number of shares shall be added for such year.
Award term	10 years
Percentage of shares outstanding used to calculate annual increase in number of shares that can be issued	1%
Stock-based compensation expense	$ 100,000	$ 100,000
Common stock additional capital shares reserved for future issuance \| shares			549,142
Eligible employees purchase common stock percentage of lower of fair market value	85%
Participants accrue rights to purchase maximum common stock amount	$ 25,000
2020 Employee Stock Purchase Plan \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Eligible employees contribution percentage	15%
Vesting After One Year \| Restricted Stock Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of stock options vested	25%
Vesting After One Year \| Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of stock options vested	25%
Vesting After One Year \| 2020 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of stock options vested	25%

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Stock-Based Compensation Expense Recorded in Statements of Operations (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 5,547	$ 6,256
Research and Development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	3,010	2,991
General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 2,537	$ 3,265

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock Option Activity (Details) - $ / shares	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Number of shares, Outstanding at beginning of period	11,898,446
Number of shares, Granted	3,071,300
Number of shares, Exercised	(1,170)
Number of shares, Forfeited	(230,836)
Number of shares, Outstanding at end of period	14,737,740	11,898,446
Number of shares, Exercisable at March 31, 2024	7,001,612
Weighted average exercise price per share, Outstanding at beginning of period	$ 10.60
Weighted average exercise price per share, Granted	4.58
Weighted average exercise price per share, Exercised	1.89
Weighted average exercise price per share, Forfeited	15.66
Weighted average exercise price per share, Outstanding at end of period	9.27	$ 10.60
Weighted average exercise price per share, Exercisable at March 31,2023	$ 11.15
Weighted average remaining contractual term (years), Outstanding	8 years 7 days	7 years 9 months 7 days
Weighted average remaining contractual term (years), Exercisable	6 years 11 months 4 days

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of Information about Stock Options Outstanding (Details)	3 Months Ended
	Mar. 31, 2024 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options Outstanding, Number \| shares	14,737,740
Options Exercisable, Number Exercisable \| shares	7,001,612
$0.31 - $4.56
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Range of Exercise Prices, Minimum	$ 0.31
Range of Exercise Prices, Maximum	$ 4.56
Options Outstanding, Number \| shares	2,290,135
Options Outstanding, Weighted Average Remaining Contractual Life (in years)	6 years 21 days
Options Outstanding, Weighted Average Exercise Price	$ 2.13
Options Exercisable, Number Exercisable \| shares	1,975,983
Options Exercisable, Weighted Average Exercise Price	$ 1.82
$4.57 - $5.00
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Range of Exercise Prices, Minimum	4.57
Range of Exercise Prices, Maximum	$ 5
Options Outstanding, Number \| shares	4,041,027
Options Outstanding, Weighted Average Remaining Contractual Life (in years)	9 years 6 months 3 days
Options Outstanding, Weighted Average Exercise Price	$ 4.65
Options Exercisable, Number Exercisable \| shares	538,800
Options Exercisable, Weighted Average Exercise Price	$ 4.82
$5.01 - $10.34
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Range of Exercise Prices, Minimum	5.01
Range of Exercise Prices, Maximum	$ 10.34
Options Outstanding, Number \| shares	3,689,654
Options Outstanding, Weighted Average Remaining Contractual Life (in years)	8 years 8 months 26 days
Options Outstanding, Weighted Average Exercise Price	$ 6.72
Options Exercisable, Number Exercisable \| shares	1,058,642
Options Exercisable, Weighted Average Exercise Price	$ 6.74
$10.35 - $88.98
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Range of Exercise Prices, Minimum	10.35
Range of Exercise Prices, Maximum	$ 88.98
Options Outstanding, Number \| shares	4,716,924
Options Outstanding, Weighted Average Remaining Contractual Life (in years)	7 years 1 month 13 days
Options Outstanding, Weighted Average Exercise Price	$ 18.68
Options Exercisable, Number Exercisable \| shares	3,428,187
Options Exercisable, Weighted Average Exercise Price	$ 18.89

Stock-Based Compensation - Sc_2

Stock-Based Compensation - Schedule of Fair Value of Each Option Estimated on Date of Grant Using Weighted Average Assumptions (Details) - Stock Options	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility	85.12%	83.55%
Risk-free interest rate	4.14%	3.80%
Expected life (in years)	6 years 25 days	6 years 18 days

Stock-Based Compensation - Su_3

Stock-Based Compensation - Summary of Activity related to RSA Stock-Based Payment Awards (Details) - Restricted Stock Awards	3 Months Ended
	Mar. 31, 2024 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares, Unvested balance at beginning of period \| shares	27,008
Number of shares, Vested \| shares	(27,008)
Weighted-average grant date fair value, Unvested balance at beginning of period \| $ / shares	$ 3.26
Weighted-average grant date fair value, Vested \| $ / shares	$ 3.26

Stock-Based Compensation - Su_4

Stock-Based Compensation - Summary of Activity related to RSU Stock-Based Payment Awards (Details) - Restricted Stock Units	3 Months Ended
	Mar. 31, 2024 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares, Unvested balance at beginning of period \| shares	103,750
Number of shares, Vested \| shares	(10,625)
Number of shares, Unvested balance at end of period \| shares	93,125
Weighted-average grant date fair value, Unvested balance at beginning of period \| $ / shares	$ 6.16
Weighted-average grant date fair value, Vested \| $ / shares	6.44
Weighted-average grant date fair value, Unvested balance at end of period \| $ / shares	$ 6.12