Curis (CRIS) 10-K 8 Feb 24 2023 FY Annual report Financial data

Cover

Cover - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Feb. 01, 2024	Jun. 30, 2023
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2023
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	000-30347
Entity Registrant Name	CURIS, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	04-3505116
Entity Address, Address Line One	128 Spring Street, Building C - Suite 500
Entity Address, City or Town	Lexington
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02421
City Area Code	617
Local Phone Number	503-6500
Title of 12(b) Security	Common Stock, $0.01 par value per share
Trading Symbol	CRIS
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	false
Document Financial Statement Error Correction	false
Entity Shell Company	false
Entity Public Float			$ 82.3
Entity Common Stock, Shares Outstanding		5,894,085
Documents Incorporated by Reference	Specified portions of the registrant’s proxy statement for the annual meeting of stockholders scheduled to be held on May 21, 2024, which are to be filed with the Commission not later than 120 days after the close of the Registrant’s fiscal year ended December 31, 2023 pursuant to Regulation 14A, have been incorporated by reference in Items 10-14 of Part III of this Annual Report on Form 10-K.
Amendment Flag	false
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Entity Central Index Key	0001108205

Audit Information

Audit Information	12 Months Ended
	Dec. 31, 2023
Audit Information [Abstract]
Auditor Name	PricewaterhouseCoopers LLP
Auditor Location	Boston, Massachusetts
Auditor Firm ID	238

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 26,681	$ 19,658
Short-term investments	29,653	65,965
Accounts receivable	2,794	2,975
Prepaid expenses and other current assets	1,780	3,521
Total current assets	60,908	92,119
Property and equipment, net	434	689
Restricted cash, long-term	544	635
Operating lease right-of-use asset	3,056	4,401
Other assets	3,358	2,022
Goodwill	8,982	8,982
Total assets	77,282	108,848
Current liabilities:
Accounts payable	3,172	3,193
Accrued liabilities	9,040	5,679
Current portion of operating lease liability	1,305	1,141
Total current liabilities	13,517	10,013
Long-term operating lease liability	1,489	2,800
Liability related to the sale of future royalties, net	42,606	49,483
Total liabilities	57,612	62,296
Commitments and contingencies, Note 7
Stockholders’ equity:
Preferred stock, $0.01 par value—5,000,000 shares authorized, no shares issued and outstanding at December 31, 2023 and 2022	0	0
Common stock, $0.01 par value—22,781,250 shares authorized, 5,894,085 shares issued and outstanding at December 31, 2023; 11,390,625 shares authorized, 4,830,464 shares issued and outstanding at December 31, 2022	59	48
Additional paid-in capital	1,215,792	1,195,687
Accumulated deficit	(1,196,410)	(1,148,997)
Accumulated other comprehensive gain (loss)	229	(186)
Total stockholders’ equity	19,670	46,552
Total liabilities and stockholders’ equity	$ 77,282	$ 108,848

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	22,781,250	11,390,625
Common stock, shares issued (in shares)	5,894,085	4,830,464
Common stock, shares outstanding (in shares)	5,894,085	4,830,464

Consolidated Statements of Oper

Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Revenues, net:
Revenues, net	$ 10,023	$ 10,162
Operating expenses:
Cost of royalties	212	257
Research and development	39,496	43,277
General and administrative	18,647	19,648
Total operating expenses	58,355	63,182
Loss from operations	(48,332)	(53,020)
Other income (expense):
Interest income	2,938	1,119
Expense related to the sale of future royalties	(2,019)	(4,771)
Total other income (expense)	919	(3,652)
Net loss	$ (47,413)	$ (56,672)
Net loss per common share, basic (in dollars per share)	$ (8.96)	$ (12.14)
Net loss per common share, diluted (in dollars per share)	$ (8.96)	$ (12.14)
Weighted average common shares, basic (in shares)	5,293,294	4,669,626
Weighted average common shares, diluted (in shares)	5,293,294	4,669,626
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract]
Net loss	$ (47,413)	$ (56,672)
Other comprehensive income (loss):
Unrealized gain (loss) on marketable securities	415	(77)
Comprehensive loss	$ (46,998)	$ (56,749)

Consolidated Statements of Stoc

Consolidated Statements of Stockholders’ Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Gain (Loss)
Beginning balance (in shares) at Dec. 31, 2021		4,582,353
Beginning balance at Dec. 31, 2021	$ 90,707	$ 46	$ 1,183,095	$ (1,092,325)	$ (109)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock in connection with 2021 Sales Agreement, net of fees (in shares)		229,185
Issuance of common stock in connection with July Registered Direct, net of fees of $1.3 million	5,594	$ 2	5,592
Stock-based compensation	6,752		6,752
Issuance of common stock under employee benefit plans, including restricted stock awards (in shares)		18,926
Issuance of common stock under employee benefit plans, including restricted stock awards	248		248
Unrealized gain (loss) on marketable securities	(77)				(77)
Net loss	$ (56,672)			(56,672)
Ending balance (in shares) at Dec. 31, 2022	4,830,464	4,830,464
Ending balance at Dec. 31, 2022	$ 46,552	$ 48	1,195,687	(1,148,997)	(186)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock in connection with 2021 Sales Agreement, net of fees (in shares)		920,488
Issuance of common stock in connection with July Registered Direct, net of fees of $1.3 million	13,814	$ 9	13,805
Stock-based compensation	6,000		6,000
Issuance of common stock under employee benefit plans, including restricted stock awards (in shares)		149,633
Issuance of common stock under employee benefit plans, including restricted stock awards	302	$ 2	300
Cancellation of restricted stock awards (in shares)		(6,500)
Cancellation of restricted stock awards	0		0
Unrealized gain (loss) on marketable securities	415				415
Net loss	$ (47,413)			(47,413)
Ending balance (in shares) at Dec. 31, 2023	5,894,085	5,894,085
Ending balance at Dec. 31, 2023	$ 19,670	$ 59	$ 1,215,792	$ (1,196,410)	$ 229

Consolidated Statements of St_2

Consolidated Statements of Stockholders’ Equity (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Statement of Stockholders' Equity [Abstract]
Fees for issuance of shares	$ 1.3	$ 0.7

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Cash flows from operating activities:
Net loss	$ (47,413)	$ (56,672)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	255	233
Non-cash lease expense	1,344	1,158
Stock-based compensation expense	6,000	6,752
Non-cash activity related to the sale of future royalties	(340)	659
Amortization of premiums and discounts on investments	(1,059)	351
Changes in operating assets and liabilities:
Accounts receivable	181	249
Prepaid expenses and other assets	405	(2,276)
Accounts payable and accrued and other liabilities	3,340	(3,884)
Operating lease liability	(1,147)	(907)
Total adjustments	8,979	2,335
Net cash used in operating activities	(38,434)	(54,337)
Cash flows from investing activities:
Purchases of investments	(70,340)	(62,000)
Sales and maturities of investments	108,126	95,439
Purchases of property and equipment	0	(416)
Net cash provided by investing activities	37,786	33,023
Cash flows from financing activities:
Proceeds from issuance of common stock, net of issuance costs	14,117	5,842
Payment of liability of future royalties, net of imputed interest	(6,537)	(4,975)
Net cash provided by financing activities	7,580	867
Net increase (decrease) in cash and cash equivalents and restricted cash	6,932	(20,447)
Cash and cash equivalents and restricted cash, beginning of period	20,293	40,740
Cash and cash equivalents and restricted cash, end of period	27,225	20,293
Supplemental cash flow data:
Cash paid for interest	2,359	4,112
Decrease in right-of-use assets and operating lease liabilities resulting from lease modification	$ 0	$ 191

Nature of Business

Nature of Business	12 Months Ended
	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Business	Nature of Business Curis, Inc. is a biotechnology company focused on the development of emavusertib (CA-4948), an orally available, small molecule inhibitor of Interleukin-1 receptor associated kinase, or IRAK4. Throughout these consolidated financial statements, Curis, Inc. and its wholly owned subsidiaries are collectively referred to as “the Company,” “Curis,” “we,” “us,” or “our.” The Company is party to a collaboration agreement with Genentech Inc. (“Genentech”), a member of the Roche Group, under which Genentech and F. Hoffmann-La Roche Ltd (“Roche”) are commercializing Erivedge® (vismodegib), a first-in-class orally administered small molecule Hedgehog signaling pathway antagonist. Erivedge is approved for the treatment of advanced basal cell carcinoma (“BCC”). The Company is party to an exclusive collaboration agreement with Aurigene Discovery Technologies Limited (“Aurigene”) for the discovery, development and commercialization of small molecule compounds in the areas of immuno-oncology and precision oncology, including emavusertib. The Company is subject to risks common to companies in the biotechnology industry as well as risks that are specific to the Company’s business, including, but not limited to: the Company’s ability to obtain adequate financing to fund its operations; the Company’s ability to continue as a going concern; the Company’s ability to advance and expand its research and development program for emavusertib; the Company’s ability to execute on its overall business strategies; the Company’s ability to obtain and maintain necessary intellectual property protection; development by the Company’s competitors of new or better technological innovations; the Company’s ability to comply with regulatory requirements; the Company’s ability to obtain and maintain applicable regulatory approvals and commercialize any approved drug candidates; and the ability of the Company and its wholly owned subsidiary, Curis Royalty, LLC (“Curis Royalty”), to satisfy the terms of the royalty interest purchase agreement (the “Oberland Purchase Agreement”) with entities managed by Oberland Capital Management, LLC (the “Purchasers”), and Lind SA LLC (the “Agent”), as collateral agent for the Purchasers. The Company’s future operating results will largely depend on the progress of emavusertib and the magnitude of payments that it may receive and make under its current and potential future collaborations. The results of the Company’s operations have varied and will likely continue to vary significantly from year to year and quarter to quarter and depend on a number of factors, including, but not limited to the timing, outcome and cost of the Company’s preclinical studies and clinical trials for its drug candidate. The Company will require substantial funds to maintain its research and development program and support operations. The Company has incurred losses and cash outflows from operations since its inception. The Company had an accumulated deficit of approximately $1.2 billion as of December 31, 2023 and incurred a net loss of $47.4 million and used $38.4 million of cash in operations for the year ended December 31, 2023. The Company expects to continue to generate operating losses in the foreseeable future. In accordance with Financial Accounting Standards Board (“FASB”) Accounting Standards Update (“ASU”) No. 2014-15, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern (Subtopic 205-40), the Company has concluded there are conditions and events, considered in the aggregate, that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that the consolidated financial statements are issued. Based on the Company's $56.3 million of existing cash, cash equivalents and investments at December 31, 2023, recurring losses and cash outflows from operations since inception, an expectation of continuing losses and cash outflows from operations for the foreseeable future and the need to raise additional capital to finance our future operations, the Company concluded it does not have sufficient cash on hand to support current operations within the next 12 months from the date of filing this Annual Report on Form 10-K. These factors raise substantial doubt regarding the Company’s ability to continue as a going concern. The Company plans to seek additional funding through a number of potential avenues, including private or public equity financings, collaborations, or other strategic transactions as needed. The Company may not be able to obtain funding on acceptable terms, or at all. The terms of any financing may adversely affect the holdings or the rights of the Company’s stockholders. The Company’s ability to raise additional funds will depend, among other factors, on financial, economic and market conditions, many of which are outside of its control and it may be unable to raise financing when needed, or on terms favorable to the Company. If necessary funds are not available, the Company will have to delay, reduce the scope of, or eliminate its development of emavusertib, potentially delaying the time to market for or preventing the marketing of emavusertib, which may have a material adverse effect on the Company’s operations and future prospects.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies (a) Basis of Presentation and Principles of Consolidation The accompanying consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the U.S. (“GAAP”) and include the accounts of our wholly owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. In accordance with FASB ASU No. 2014-15 , Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern (Subtopic 205-40) , the Company has concluded there are conditions and events, considered in the aggregate, that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that the consolidated financial statements are issued. On September 28, 2023, the Company effected a 1-for-20 reverse stock split of its common stock (“the Reverse Stock Split”). All references to shares of common stock outstanding, average number of shares outstanding and per share amounts in these consolidated financial statements and notes to consolidated financial statements have been restated to reflect the Reverse Stock Split on a retroactive basis. (b) Use of Estimates and Assumptions The preparation of the Company’s consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts and disclosure of revenue, expenses and certain assets and liabilities at the balance sheet date. Such estimates include the performance obligations under the Company’s collaboration agreements; the collectability of receivables; and the value of certain investments and liabilities. Actual results may differ from such estimates. (c) Cash Equivalents, Restricted Cash, and Investments Cash equivalents consist of highly liquid investments purchased with original maturities of three months or less. All other investments are marketable securities. The Company separately classified $0.5 million and $0.6 million of its cash as restricted cash, long-term as of December 31, 2023 and 2022, respectively. These amounts represent the security deposit associated with the Company's Lexington, Massachusetts headquarters. The Company’s short-term investments are marketable debt securities with original maturities of greater than three months from the date of purchase, but less than twelve months from the balance sheet date. Marketable securities consist of commercial paper, corporate bonds and notes, and/or government obligations. All of the Company’s investments have been designated available-for-sale and are stated at fair value. Unrealized gains and losses on investments are included in accumulated other comprehensive income (loss) as a separate component of stockholders’ equity. Realized gains and losses, dividends and interest income are included in other income (expense) in the period during which the securities are sold. Any premium or discount arising at purchase is amortized and/or accreted to interest income. (d) Concentrations and Significant Customer Information Financial instruments which potentially subject the Company to concentrations of credit risk consist principally of cash and cash equivalents, marketable securities, and accounts receivable. The Company maintains deposits in federally insured financial institutions in excess of federally insured limits. Management believes that the Company is not exposed to significant credit risk due to the financial position of the depository institutions in which those deposits are held. The Company’s credit risk related to investments is reduced as a result of the Company’s policy to limit the amount invested in any one issue. The Company's operations are located entirely within the U.S. The Company's focus is primarily on the development of emavusertib, a small molecule IRK4 inhibitor. The Company's customer, Genentech, accounted for 99% and 100% of the total gross revenues for the years ended December 31, 2023 and 2022, respectively. The Company’s accounts receivable at December 31, 2023 and December 31, 2022 represents amounts due from royalties earned on sales of Erivedge by Genentech and Roche. The Company relies on third parties to manufacture and supply emavusertib. In addition, there are a small number of suppliers for certain raw materials that the Company uses to manufacture emavusertib. (e) Long-Lived Assets Other than Goodwill Long-lived assets other than goodwill consist of property and equipment. The Company applies the guidance in FASB Codification Topic 360-10-05, Impairment or Disposal of Long-Lived Assets . If it were determined that the carrying value of the Company’s other long-lived assets might not be recoverable based upon the existence of one or more indicators of impairment, the Company would measure an impairment based on the difference between the carrying value and fair value of the asset. The Company did not recognize any material impairment charges for the years ended December 31, 2023 or December 31, 2022. Purchased equipment is recorded at cost. The Company does not currently hold any leased equipment. Depreciation and amortization are provided on the straight-line method over the estimated useful lives of the related assets or the remaining terms of the leases, whichever is shorter, as follows: Useful Life Laboratory equipment, computers and software 3-5 years Leasehold improvements Lesser of lease or asset life Office furniture and equipment 5 years (f) Leases The Company determines if an arrangement is a lease at contract inception. The Company made an accounting policy election to not recognize leases with an initial term of 12 months or less within its consolidated balance sheets and to recognize those lease payments on a straight-line basis in its consolidated statements of operations and comprehensive loss over the lease term. Operating lease assets represent the Company's right to use an underlying asset for the lease term and operating lease liabilities represent its obligation to make lease payments arising from the lease. Operating lease assets and liabilities are recognized at the commencement date of the lease based upon the present value of lease payments over the lease term. When determining the lease term, the Company includes options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. As the Company's lease does not provide an implicit interest rate, the Company uses its incremental borrowing rate, which is based on rates that would be incurred to borrow on a collateralized basis over a term equal to the lease payments in a similar economic environment, in determining the present value of lease payments. The lease payment used to determine the operating lease asset may include lease incentives, stated rent increases and was recognized as an operating lease right-of-use asset in the consolidated balance sheets. The Company's lease agreements may include both lease and non-lease components, which may be accounted for as a single lease component when the payments are fixed. Variable payments included in the lease agreement are expensed as incurred. The Company's operating lease is reflected in operating lease right-of-use asset and operating lease liability in the consolidated balance sheets. Lease expense for lease payments is recognized on a straight-line basis over the lease term. (g) Other assets Other assets consist of long-term prepayments and deposits. (h) Goodwill The Company had goodwill of $9.0 million as of both December 31, 2023 and 2022. The Company applies the guidance in the FASB Codification Topic 350, Intangibles—Goodwill and Other . The Company performs its annual goodwill assessment as of December 31. As part of its annual goodwill assessment, the Company determined (1) it operates as a single reporting unit and (2) the fair value of the Company exceeded the carrying value of its net assets. Accordingly, no goodwill impairment was recognized for each of the years ended December 31, 2023 and 2022, and there have been no cumulative impairments. (i) Revenue Recognition The Company applies the revenue recognition guidance in accordance with FASB Codification Topic 606, Revenue from Contracts with Customers . The Company recognizes royalty revenues related to Genentech’s and Roche’s sales of Erivedge. For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and where the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). The Company expects to continue recognizing royalty revenue from Genentech’s sales of Erivedge in the U.S. and Roche's sales of Erivedge outside of the U.S. (see Note 10, Research and Development Collaborations). However, a significant portion of Erivedge royalties will be paid to the Purchasers pursuant to the Oberland Purchase Agreement (see Note 8, Liability Related to the Sale of Future Royalties). (j) Research and Development Research and development expense primarily consists of costs incurred to discover, research and develop emavusertib. These expenses primarily include: (1) salaries and related expenses for personnel, including stock-based compensation expense; (2) costs of conducting clinical trials, including amounts paid to clinical centers, clinical research organizations and consultants; (3) other outside service including regulatory and costs of contract manufacturing; (4) the cost of companion drugs; (5) facility costs; and (6) certain payments that we make under our collaboration agreements. The Company expenses research and development costs as they are incurred. (k) Basic and Diluted Loss per Common Share Basic and diluted net losses per share were determined by dividing net loss by the weighted average number of common shares outstanding during the period. Diluted net loss per common share is the same as basic net loss per common share for all periods presented, as the effect of the potential common stock equivalents is antidilutive due to the Company’s net loss position for all periods presented. Antidilutive securities consist of stock options outstanding of 840,880 and 683,666 as of December 31, 2023 and 2022, respectively and unvested restricted stock awards of 110,500 as of December 31, 2023. (l) Stock-Based Compensation The Company accounts for stock-based compensation transactions using a grant-date fair-value based method under FASB Codification Topic 718, Compensation-Stock Compensation . The Company measures compensation cost for stock-based compensation at fair value and recognizes the expense as compensation expense over the period that the recipient is required to provide service in exchange for the award, which generally is the vesting period. The Company uses the Black-Scholes option pricing model to measure the fair value of stock options. This model requires estimates related to the award’s expected life and future stock price volatility of the underlying equity security. Actual compensation expense recognized over the vesting period will only be for those shares that vest. The expected volatility is based on the annualized daily historical volatility of the Company’s stock price for a time period consistent with the expected term of each grant. Management believes that the historical volatility of the Company’s stock price best represents the future volatility of the stock price. The risk-free rate is based on the U.S. Treasury yield in effect at the time of grant for the expected term of the respective grant. The Company has not historically paid cash dividends, and does not expect to pay cash dividends in the foreseeable future. (m) Comprehensive Loss Comprehensive loss is comprised of net loss and other comprehensive income (loss). Other comprehensive income (loss) includes unrealized gains and losses arising during the period on available-for-sale securities. (n) Segment Reporting The Company has determined that it operates in a single reportable segment, which is the research and development of innovative drug candidates for the treatment of human cancer. (o) Interest Expense on Liability related to the Sale of Future Royalties In March 2019 the Company entered into the Oberland Purchase Agreement. Pursuant to the terms of the Oberland Purchase Agreement the Company sold to the Purchasers a portion of its rights to receive royalties from Genentech on potential net sales of Erivedge. As a result of the obligation to pay future royalties to the Purchasers, the Company recorded the proceeds as a liability in its consolidated balance sheet that is accounted for using the interest method over the expected life of the Oberland Purchase Agreement. As a result, the Company imputes interest on the transaction and records imputed interest expense at the estimated interest rate. The Company's estimate of the interest rate under the Oberland Purchase Agreement is based on the amount of royalty payments expected to be received by the Purchasers over the life of the arrangement. (p) New Accounting Pronouncements Issued, Not Yet Adopted In November 2023, the FASB issued ASU No. 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures , which provides updates to qualitative and quantitative reportable segment disclosure requirements, including enhanced disclosures about significant segment expenses and increased interim disclosure requirements, among others. ASU No. 2023-07 is effective for fiscal years beginning after December 15, 2023, and interim periods in fiscal years beginning after December 15, 2024. Early adoption is permitted, and the amendments should be applied retrospectively. The Company is currently evaluating the impact of the ASU on the consolidated financial statement disclosures. In December 2023, the FASB issued ASU No. 2023-09, Improvements to Income Tax Disclosures , which requires disclosure of disaggregated income taxes paid, prescribes standard categories for the components of the effective tax rate reconciliation, and modifies other income tax-related disclosures. ASU No. 2023-09 is effective for fiscal years beginning after December 15, 2024 and allows for adoption on a prospective basis, with a retrospective option. Early adoption is permitted. The Company is currently evaluating the impact of the ASU on the income tax disclosures within the consolidated financial statements.

Fair Value of Financial Instrum

Fair Value of Financial Instruments	12 Months Ended
	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	Fair Value of Financial Instruments The Company applies the provisions of FASB Codification 820, Fair Value Measurements (“ASC 820”) for its financial assets and liabilities that are re-measured and reported at fair value each reporting period and the non-financial assets and liabilities that are re-measured and reported at fair value on a non-recurring basis. Fair value is the price that would be received from selling an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. When determining fair value, the Company considers the principal or most advantageous market in which it would transact and considers assumptions that market participants would use when pricing the asset or liability. ASC 820 establishes a three-level valuation hierarchy for disclosure of fair value measurements. Financial assets and liabilities are categorized within the valuation hierarchy based upon the lowest level of input that is significant to the measurement of fair value. The three levels of the hierarchy are defined 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 not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. In accordance with the fair value hierarchy, the following tables show the fair value as of December 31, 2023 and 2022 of those financial assets and liabilities that are measured at fair value on a recurring basis, according to the valuation techniques the Company used to determine their fair value. Quoted Prices in Other Unobservable Fair Value (in thousands) As of December 31, 2023 Cash equivalents: Money market funds $ 16,780 $ — $ — $ 16,780 U.S. treasury securities and government agency obligations — 4,735 — 4,735 Corporate debt securities and commercial paper — 2,021 — 2,021 Short-term investments: Corporate debt securities and commercial paper — 12,996 — 12,996 U.S. treasury securities and government agency obligations — 16,657 — 16,657 Total $ 16,780 $ 36,409 $ — $ 53,189 Quoted Prices in Other Unobservable Fair Value (in thousands) As of December 31, 2022 Cash equivalents: Money market funds $ 15,215 $ — $ — $ 15,215 U.S. treasury securities and government agency obligations — 2,998 — 2,998 Short-term investments: Corporate debt securities and commercial paper — 42,071 — 42,071 U.S. treasury securities and government agency obligations — 23,894 — 23,894 Total assets at fair value $ 15,215 $ 68,963 $ — $ 84,178

Investments

Investments	12 Months Ended
	Dec. 31, 2023
Investments, Debt and Equity Securities [Abstract]
Investments	Investments The amortized cost, unrealized gains and losses and fair value of investments available-for-sale as of December 31, 2023 are as follows: (in thousands) Amortized Unrealized Unrealized Fair Value Short-term investments: Corporate debt securities and commercial paper $ 12,999 $ — $ (3) $ 12,996 U.S. treasury securities and government agency obligations 16,655 3 (1) 16,657 Total investments $ 29,654 $ 3 $ (4) $ 29,653 The weighted average remaining maturity of short-term investments was 0.2 years at December 31, 2023. The amortized cost, unrealized gains and losses and fair value of investments available-for-sale as of December 31, 2022 are as follows: (in thousands) Amortized Unrealized Unrealized Fair Value Short-term investments: Corporate debt securities and commercial paper $ 42,109 $ 2 $ (40) $ 42,071 U.S. treasury securities and government agency obligations 24,042 — (148) 23,894 Total investments $ 66,151 $ 2 $ (188) $ 65,965 The weighted average remaining maturity of short-term investments was 0.3 years at December 31, 2022. No credit losses on available-for-sale securities were recognized during the years ended December 31, 2023 and 2022. In its evaluation to determine expected credit losses, management considered all available historical and current information, expectations of future economic conditions, the type of security, the credit rating of the security, and the size of the loss position, as well as other relevant information. The Company does not intend to sell, and is unlikely to be required to sell, any of these available-for-sale investments before their effective maturity or market price recovery.

Property and Equipment, Net

Property and Equipment, Net	12 Months Ended
	Dec. 31, 2023
Property, Plant and Equipment [Abstract]
Property and Equipment, Net	Property and Equipment, Net Property and equipment consisted of the following: December 31, (in thousands) 2023 2022 Laboratory equipment, computers and software $ 1,140 $ 1,776 Leasehold improvements 257 257 Office furniture and equipment 1,028 1,113 2,425 3,146 Less—Accumulated depreciation and amortization (1,991) (2,457) Property and equipment, net $ 434 $ 689 Depreciation and amortization expense related to property and equipment was $0.3 million and $0.2 million for the years ended December 31, 2023 and 2022, respectively.

Accrued Liabilities

Accrued Liabilities	12 Months Ended
	Dec. 31, 2023
Other Liabilities Disclosure [Abstract]
Accrued Liabilities	Accrued Liabilities Accrued liabilities consisted of the following: December 31, (in thousands) 2023 2022 Headcount related costs $ 3,701 $ 3,152 Research and development costs 4,163 1,727 Professional and legal fees 1,059 762 Other 117 38 Total $ 9,040 $ 5,679

Leases and Commitments

Leases and Commitments	12 Months Ended
	Dec. 31, 2023
Leases [Abstract]
Leases and Commitments	Leases and Commitments (a) Operating Leases The Company has a single lease for real estate, including laboratory and office space, and certain equipment, located at 128 Spring Street in Lexington, Massachusetts which commenced on May 1, 2020. In January 2022, the Company amended its lease agreement for 128 Spring Street ("Lease Amendment") and the Lease Amendment commenced during the second quarter of 2022. The Lease Amendment added approximately 9,340 square feet to the existing space for $30 per square foot, or $0.3 million per year in base rent subject to annual rent increases. The Lease Amendment provides the Company and the landlord each with an option to terminate the lease agreement before the original lease term expires on April 30, 2027. The Company's early termination option becomes effective on the lease commencement date of a new lease for larger premises within the landlord’s commercial real estate portfolio (“New Lease”), and the Company may exercise its early termination option by providing the landlord with written notice of such election to terminate the lease agreement concurrently with the execution of the New Lease. The landlord has the option to early terminate the lease agreement by providing written notice to the Company eighteen months prior to December 31, 2025, or June 30, 2024. The Company expects the lease to end as of December 31, 2025. The Lease Amendment constituted a modification as it reduces the original lease term and increases the scope of the lease (additional space provided under the Lease Amendment), and required evaluation of the remeasurement of the lease liability and corresponding right-of-use asset. The additional space did not result in a separate contract as the rent increase was determined not to be commensurate with the standalone price for the additional right of use. Accordingly, the Company reassessed the classification of the lease, and concluded it continues to be an operating lease, and remeasured the lease liability on the basis of the reduced lease term as of the effective date of the modification. The shortened lease term and resulting remeasurement for the modification resulted in a decrease to the lease liability and the right-of-use asset. The additional space provided under the Lease Amendment and resulting remeasurement for the modification resulted in an increase to the lease liability and the right-of-use asset. During the year ended December 31, 2022, the Company recognized a net decrease of $0.2 million to the lease liability and right-of-use asset as a result of the modification. The discount rate associated with the Company’s right-of-use asset is 10%. The total cash obligation for the base rent over the six-year term of this lease is approximately $8.8 million, of which $1.5 million was paid during the year ended December 31, 2023 . The Company's lease is an operating lease. The following table summarizes the presentation in the Company's consolidated balance sheet for the operating lease: December 31, (in thousands) 2023 2022 Assets: Operating lease right-of-use asset $ 3,056 $ 4,401 Liabilities: Operating lease liability - short-term $ 1,305 $ 1,141 Operating lease liability - long-term 1,489 2,800 Total operating liability $ 2,794 $ 3,941 The following table summarizes the effect of lease costs in our consolidated statements of operations and comprehensive loss: For the Year Ended December 31, (in thousands) 2023 2022 Operating lease cost Research and development $ 483 $ 1,187 General and administrative 1,182 382 Total $ 1,665 $ 1,569 The Company’s lease payments through the end of the expected lease term are expected to be as follows: Year Ending December 31, (in thousands) 2024 1,512 2025 1,558 Total lease payments $ 3,070 Less: interest 276 Present value of operating lease liabilities $ 2,794 (b) License and Funding Agreements In exchange for the right to use licensed technology in its research and development efforts, the Company has entered into various license agreements and funding agreements. These license agreements generally stipulate that the Company is obligated to pay royalties on future revenues, if any, resulting from use of the underlying licensed technology. Such revenues may include up-front license fees, contingent payments upon collaborators’ achievement of development and regulatory objectives, and royalties. In addition, some of the agreements commit the Company to make contractually defined payments upon the attainment of scientific or clinical milestones. The Company expenses these payments as they are incurred and expenses royalty payments as related future product sales or as royalty revenues are recorded. The Company accrues expenses for scientific and clinical objectives over the period that the work required to meet the respective objective is completed, provided that the Company believes that the achievement of such objective is probable. For the years ended December 31, 2023 and 2022, the Company also recognized $0.2 million and $0.3 million, respectively, as cost of royalty revenues in its consolidated statements of operations and comprehensive loss (see Note 10(a), Research and Development Collaborations - Genentech).

Liability Related to the Sale o

Liability Related to the Sale of Future Royalties	12 Months Ended
	Dec. 31, 2023
Nonmonetary Transactions [Abstract]
Liability Related to the Sale of Future Royalties	Liability Related to the Sale of Future Royalties In March 2019, the Company and Curis Royalty entered into the royalty interest purchase agreement (“Oberland Purchase Agreement”) with TPC Investments I LP and TPC Investments II LP ("the Purchasers"), each of which is a Delaware limited partnership managed by Oberland Capital Management, LLC, and Lind SA LLC, a Delaware limited liability company managed by Oberland Capital Management, LLC, as collateral agent for the Purchasers. The Company sold to the Purchasers a portion of its rights to receive royalties from Genentech on potential net sales of Erivedge. Concurrently with the closing of the Oberland Purchase Agreement, Curis Royalty used a portion of the proceeds to terminate and repay the then existing loan with Healthcare Royalty Partners III, L.P. As upfront consideration for the purchase of the royalty rights, the Purchasers paid to Curis Royalty $65.0 million less certain transaction expenses. Curis Royalty will also be entitled to receive up to $53.5 million in milestone payments based on sales of Erivedge if the Purchasers receive payments pursuant to the Oberland Purchase Agreement in excess of $117.0 million on or prior to December 31, 2026. The Oberland Purchase Agreement provides that after the occurrence of an event of default as defined under the security agreement by Curis Royalty, the Purchasers shall have the option, for a period of 180 days, to require Curis Royalty to repurchase a portion of certain royalty and royalty related payments, excluding a portion of non-U.S. royalties retained by Curis Royalty ("Purchased Receivables"), at a price (the "Put/Call Price") equal to 250% of the sum of the upfront purchase price and any portion of the milestone payments paid in a lump sum by the Purchasers, if any, minus certain payments previously received by the Purchasers with respect to the Purchased Receivables. The Company concluded the put option is an embedded derivative that requires bifurcation from the deferred royalty obligation and evaluates the fair value of the put option each reporting period. The estimated fair value of the put option is immaterial as of both December 31, 2023 and 2022. Additionally, Curis Royalty shall have the option at any time to repurchase the Purchased Receivables at the Put/Call Price as of the date of such repurchase. No events of default occurred as of December 31, 2023. As a result of the obligation to pay future royalties to the Purchasers, the Company recorded the proceeds as a liability on its consolidated balance sheets. It accounts for the liability and interest expense using the interest method over the expected life of the Oberland Purchase Agreement. As a result, the Company imputes interest on the transaction and records imputed interest expense at the estimated interest rate. The Company's estimate of the interest rate under the Oberland Purchase Agreement is based on the amount of royalty payments expected to be received by the Purchasers over the life of the Oberland Purchase Agreement. The projected amount of royalty payments expected to be paid to the Purchasers involves the use of significant estimates and assumptions with respect to the revenue growth rate in the Company's projections of sales of Erivedge. The Company periodically assesses the expected royalty payments to Curis Royalty from Genentech using a combination of historical results and forecasts from market data sources. To the extent such payments are greater or less than its initial estimates or the timing of such payments is materially different than its original estimates, the Company will prospectively adjust the amortization of the liability. The Company determined the fair value of the liability related to the sale of future royalties at the time of the Oberland Purchase Agreement to be $65.0 million, with a current effective annual imputed interest rate of 1.5%. The Company incurred $0.6 million of transaction costs in connection with the Oberland Purchase Agreement. These transaction costs will be amortized to imputed interest expense over the estimated term of the Oberland Purchase Agreement. The carrying value of the liability related to the sale of future royalties approximates fair value as of December 31, 2023 and is based on the Company's current estimates of future royalties expected to be paid the Purchasers over the life of the arrangement, which are considered Level 3 inputs. The following table shows the activity with respect to the liability related to the sale of future royalties during the years ended December 31, 2022 and 2023: (in thousands) Carrying value of liability related to the sale of future royalties at January 1, 2022 $ 53,798 Other 739 Imputed interest expense 4,033 Less: payments to the Purchasers (9,087) Carrying value of liability related to the sale of future royalties at December 31, 2022 $ 49,483 Other (119) Imputed interest expense 2,138 Less: payments to the Purchasers (8,896) Carrying value of liability related to the sale of future royalties at December 31, 2023 $ 42,606 In March 2023, Curis and Curis Royalty received a letter from counsel to Oberland Capital Management, LLC, the Purchasers and the Agent alleging defaults under Sections 4.04 and 6.04(b) of the Oberland Purchase Agreement and demanding cure of the asserted default under Section 6.04(b) of the Oberland Purchase Agreement. The asserted basis for the

Common Stock

Common Stock	12 Months Ended
	Dec. 31, 2023
Equity [Abstract]
Common Stock	Common Stock All common share amounts and per share amounts have been adjusted to reflect the Reverse Stock Split. (a) Charter Amendments In September 2023, the Company's stockholders approved an increase to the number of authorized shares of its common stock from 11,390,625 shares to 22,781,250 shares. (b) Sales Agreement with Cantor Fitzgerald & Co. and JonesTrading Institutional Services LLC In March 2021, the Company entered into a sales agreement (the “2021 Sales Agreement”) with Cantor Fitzgerald & Co. (“Cantor”) and JonesTrading Institutional Services LLC (“JonesTrading”) to sell from time to time shares of the Company’s common stock through an “at-the-market offering” program under which Cantor and JonesTrading act as sales agents. Subject to the terms and conditions of the 2021 Sales Agreement, Cantor and JonesTrading could sell the common stock by any method deemed to be an “at-the-market” offering as defined in Rule 415 promulgated under the Securities Act of 1933, as amended (the "Securities Act"). Pursuant to the terms of the 2021 Sales Agreement, the aggregate compensation payable to each of Cantor and JonesTrading was 3% of the gross proceeds from sales of the common stock sold by Cantor or JonesTrading, as applicable. The Company sold 229,185 shares of common stock under the 2021 Sales Agreement during the year ended December 31, 2022, representing gross proceeds of $6.3 million. On February 8, 2024, the Company entered into an amended and restated sales agreement with Cantor and JonesTrading (the “2024 Sales Agreement”), which supersedes the 2021 Sales Agreement. Pursuant to the 2024 Sales Agreement, the Company can sell from time to time shares of the Company’s stock through an “at-the-market offering” program under which Cantor and JonesTrading act as sales agents. Subject to the terms and conditions of the 2024 Sales Agreement, Cantor and JonesTrading can sell the common stock by any method deemed to be an “at-the-market” offering as defined in Rule 415 promulgated under the Securities Act. Pursuant to the terms of the 2024 Sales Agreement, the aggregate compensation payable to each of Cantor and JonesTrading is 3% of the gross proceeds from sales of the common stock sold by Cantor or JonesTrading, as applicable. (c) Registered Direct Offering In July 2023, the Company sold and issued, in a registered direct offering (the “July Registered Direct”) to certain institutional investors, an aggregate of 920,488 shares of common stock at a purchase price per share of $16.40 per share for net proceeds of approximately $13.8 million. (d) Aspire Capital Fund, LLC In February 2020, the Company entered into a common stock purchase agreement (the “Agreement”) for the sale of up to $30.0 million of the Company's common stock with Aspire Capital Fund, LLC ("Aspire Capital"). The Company did not sell shares of common stock under the Agreement during the year ended December 31, 2022. The Agreement expired in August 2022. The Company also entered into a Registration Rights Agreement with Aspire Capital in connection with its entry into the Agreement, which also expired in August 2022.

Research and Development Collab

Research and Development Collaborations	12 Months Ended
	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Research and Development Collaborations	Research and Development Collaborations (a) Genentech In June 2003, the Company licensed its proprietary Hedgehog pathway antagonist technologies to Genentech for human therapeutic use. The primary focus of the collaborative research plan has been to develop molecules that inhibit the Hedgehog pathway for the treatment of various cancers. The collaboration is currently focused on the development of Erivedge, which is being commercialized by Genentech in the U.S. and by Genentech's parent company, Roche, outside of the U.S. for the treatment of advanced BCC. Pursuant to the collaboration agreement, the Company is eligible to receive up to an aggregate of $115.0 million in contingent cash milestone payments, exclusive of royalty payments, in connection with the development of Erivedge or another small molecule Hedgehog pathway inhibitor, assuming the successful achievement by Genentech and Roche of specified clinical development and regulatory objectives. Of this amount, the Company has received $59.0 million in cash milestone payments as of December 31, 2023. In addition to these payments and pursuant to the collaboration agreement, the Company is entitled to a royalty on net sales of Erivedge that ranges from 5% to 7.5%. The royalty rate applicable to Erivedge may be decreased by 2% on a country-by-country basis in certain specified circumstances. The Company recognized $9.9 million and $10.3 million in royalty revenues under the Genentech collaboration during the years ended December 31, 2023 and 2022, respectively. Cost of royalties comprises payments to university licensors and was immaterial for the years ended December 31, 2023 and 2022. The Company has accounts receivable from Genentech under this collaboration of $2.7 million and $3.0 million as of December 31, 2023 and 2022, respectively, in its consolidated balance sheets. As further discussed in Note 8, Liability Related to the Sales of Future Royalties, a significant portion of royalty revenues received from Genentech on net sales of Erivedge will be paid to the Purchasers pursuant to the Oberland Purchase Agreement. (b) Aurigene In January 2015, the Company entered into an exclusive collaboration agreement with Aurigene for the discovery, development and commercialization of small molecule compounds in the areas of immuno-oncology and selected precision oncology targets. Under the collaboration agreement, Aurigene granted the Company an option to obtain exclusive, royalty-bearing licenses to relevant Aurigene technology to develop, manufacture and commercialize products containing certain of such compounds anywhere in the world, except for India and Russia, which are territories retained by Aurigene. In September 2016, the Company and Aurigene entered into an amendment to the collaboration agreement. Under the terms of the amendment, in exchange for the issuance of shares of the Company's common stock, Aurigene waived payment of up to a total of $24.5 million in potential milestones and other payments associated with the first four programs in the collaboration that may have become due from the Company under the collaboration agreement. To the extent any of these waived milestones or other payments are not payable by the Company, for example in the event one or more of the milestone events do not occur, the Company will have the right to deduct the unused waived amount from any one or more of the milestone payment obligations tied to achievement of commercial milestone events. The amendment also provides that, in the event supplemental program activities are performed by Aurigene, the Company will provide up to $2.0 million of additional funding for each of the third and fourth licensed program. In February 2020, the Company and Aurigene further amended their collaboration agreement. Under the terms of the amended agreement, Aurigene will fund and conduct a Phase 2b/3 randomized study evaluating CA-170, in combination with chemoradiation, in approximately 240 patients with non-squamous non-small cell lung cancer. In turn, Aurigene has rights to develop and commercialize CA-170 in Asia, in addition to its existing rights in India and Russia, based on the terms of the original agreement. The Company retains U.S., European Union, and rest of world rights to CA-170, and is entitled to receive royalty payments on potential future sales of CA-170 in Asia at percentage rates ranging from the high single digits up to 10% subject to specified reductions. As of December 31, 2023, the Company has exercised its option to license the following four programs under the collaboration: 1. IRAK4 Program - a precision oncology program of small molecule inhibitors of IRAK4. The development candidate is emavusertib. 2. PD1/VISTA Program - an immuno-oncology program of small molecule antagonists of PD1 and VISTA immune checkpoint pathways. The development candidate is CA-170. 3. PD1/TIM3 Program - an immuno-oncology program of small molecule antagonists of PD1 and TIM3 immune checkpoint pathways. The development candidate is CA-327. 4. An immuno-oncology program. For each of the licensed programs the Company is obligated to use commercially reasonable efforts to develop, obtain regulatory approval for, and commercialize at least one product in each of the U.S., specified countries in the European Union and Japan, and Aurigene is obligated to use commercially reasonable efforts to perform its obligations under the development plan for such licensed program in an expeditious manner. For each of the IRAK4, PD1/VISTA, PD1/TIM3 programs, and the immuno-oncology program, the Company has remaining unpaid or unwaived payment obligations of $42.5 million per program, related to regulatory approval and commercial sales milestones, plus specified additional payments for approvals for additional indications, if any. (c) ImmuNext In January 2020, the Company entered into an option and license agreement with ImmuNext (the “ImmuNext Agreement”). Under the terms of the ImmuNext Agreement, the Company agreed to engage in a collaborative effort with ImmuNext, and to conduct a Phase 1 clinical trial of CI-8993. In exchange, ImmuNext granted the Company an exclusive option, exercisable until the earlier of (a) January 2024 or (b) 90 days after database lock for the first Phase 1 trial in which the endpoints are satisfied to obtain an exclusive, worldwide license to develop and commercialize certain VISTA antagonizing compounds and products containing these compounds in the field of oncology. The Company did not exercise its option. The rights to the VISTA antagonizing compounds reverted to ImmuNext upon the expiration of the ImmuNext agreement in January 2024.

Stock Plans and Stock-Based Com

Stock Plans and Stock-Based Compensation	12 Months Ended
	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Stock Plans and Stock-Based Compensation	Stock Plans and Stock-Based Compensation As of December 31, 2023, the Company had two shareholder-approved, stock-based compensation plans: (i) the Fourth Amended and Restated 2010 Stock Incentive Plan (“2010 Plan”) and (ii) the Amended and Restated 2010 Employee Stock Purchase Plan, (“ESPP”). New employees are generally issued options as an inducement equity award under Nasdaq Listing Rule 5635(c)(4) outside of the 2010 Plan (“Inducement Awards”). The number of shares of common stock available for issuance under the plans and the number of shares of common stock issuable upon the exercise of then outstanding options have been adjusted to reflect the Reverse Stock Split. The Fourth Amended and Restated 2010 Stock Incentive Plan The 2010 Plan permits the granting of incentive and non-qualified stock options and stock awards to employees, officers, directors, and consultants of the Company and its subsidiaries at prices determined by the Company’s board of directors. The Company can issue up to 1,159,500 shares of its common stock pursuant to awards granted under the 2010 Plan. Options vest and become exercisable based on a schedule determined by the board of directors and expire up to ten years from the date of grant. The 2010 Plan uses a “fungible share” concept under which each share of stock subject to awards granted as options and stock appreciation rights (“SARs”), will cause one share per share under the award to be removed from the available share pool, while each share of stock subject to awards granted as restricted stock, restricted stock units, other stock-based awards or performance awards where the price charged for the award is less than 100% of the fair market value of the Company’s common stock will cause 1.3 shares per share under the award to be removed from the available share pool. As of December 31, 2023, the Company has only granted options to purchase shares of the Company’s common stock with an exercise price equal to the closing market price of the Company’s common stock on the Nasdaq Capital Market on the grant date and issued restricted stock awards at no cost to Company employees, excluding officers. During the year ended December 31, 2023, the Company’s board of directors granted options to purchase 220,180 shares of the Company’s common stock to officers and employees of the Company under the 2010 Plan. These options vest and become exercisable as to 25% of the shares underlying the award after the first year and as to an additional 6.25% of the shares underlying the award in each subsequent quarter, based upon continued employment over a four-year period, and are exercisable at a price equal to the closing price of the Company’s common stock on the grant date. During the year ended December 31, 2023, the Company’s board of directors granted options to its non-employee directors to purchase 21,250 shares of common stock under the 2010 Plan, which will vest and become exercisable in one year from the date of grant. These options were granted at an exercise price that equaled the closing market price of the Company’s common stock on the grant date. During the year ended December 31, 2023, the Company’s board of directors granted restricted stock awards ("RSAs"), for an aggregate amount of 117,000 shares to the employees of the Company, excluding officers, under the 2010 Plan. These RSAs vest as to 50% of the shares underlying the award on the first anniversary of the date of the grant and 50% after the second anniversary, based upon continued employment. As of December 31, 2023, 289,912 shares remained available for grant under the 2010 Plan. Inducement Awards The Company grants Inducement Awards to certain new employees. These options generally vest as to 25% of the shares underlying the option on the first anniversary of the grant date, and as to an additional 6.25% of the shares underlying the option on each successive quarter thereafter. During the year ended December 31, 2023, the Company’s board of directors granted Inducement Awards to purchase 43,112 shares of common stock. These options were granted at an exercise price that equaled the closing market price of the Company’s common stock on grant date. Stock Options A summary of stock option activity under the 2010 Plan and Inducement Awards are summarized as follows: Number of Weighted Weighted Aggregate Intrinsic Value Outstanding, December 31, 2022 683,666 $ 64.72 6.51 Granted 284,542 13.90 Exercised (515) 13.40 Canceled (126,813) 64.58 Outstanding, December 31, 2023 840,880 $ 47.58 7.16 $ 91 Exercisable at December 31, 2023 450,008 $ 63.00 5.77 $ — Vested and unvested expected to vest at December 31, 2023 840,880 $ 47.58 7.16 $ 91 The weighted average grant date fair values of stock options granted during the years ended December 31, 2023 and 2022 were $11.70 and $42.80, respectively, and were calculated using the following estimated assumptions under the Black-Scholes option pricing model: For the Year Ended 2023 2022 Expected term (years) 5.5 5.5 Risk-free interest rate 3.5-4.7% 1.4-4.1% Expected volatility 115-116% 110-115% Expected dividend yield None None As of December 31, 2023, there was approximately $8.0 million of unrecognized compensation cost related to unvested employee stock option awards outstanding, which is expected to be recognized as expense over a weighted average period of 2.5 years. The intrinsic value of employee stock options exercised during the year ended December 31, 2023 was immaterial. Restricted Stock Awards The following table presents a summary of outstanding RSAs under the 2010 Plan as of December 31, 2023: Number of Weighted Unvested, December 31, 2022 — $ — Awarded 117,000 18.20 Vested — — Forfeited (6,500) 18.20 Unvested, December 31, 2023 110,500 $ 18.20 As of December 31, 2023, there were 110,500 shares outstanding underlying RSAs that are expected to vest. The aggregate fair value of these shares of restricted stock was $2.1 million. As of December 31, 2023, there was $1.4 million of unrecognized compensation costs related to RSAs, which are expected to be recognized as expense over a remaining weighted average period of 1.4 years. Amended and Restated 2010 Employee Stock Purchase Plan The Company has reserved 100,000 shares of common stock for issuance under the ESPP. Eligible employees may purchase shares of the Company’s common stock at 85% of the lower closing market price of the common stock at the beginning of the enrollment period or ending date of the any purchase period within a two-year enrollment period, as defined. The Company has four six-month purchase periods per each two-year enrollment period. If, within any one of the four purchase periods in an enrollment period, the purchase period ending stock price is lower than the stock price at the beginning of the enrollment period, the two-year enrollment resets at the new lower stock price. During the year ended December 31, 2023, 32,117 shares were issued under the ESPP. As of December 31, 2023, there were 26,631 shares available for future purchase under the ESPP. For the years ended December 31, 2023 and 2022, the Company recorded compensation expense related to its ESPP and calculated the fair value of shares expected to be purchased under the ESPP using the Black-Scholes model. Total Stock-Based Compensation Expense For the years ended December 31, 2023 and 2022, the Company recorded employee and non-employee stock-based compensation expense to the following line items in its costs and expenses section of the consolidated statements of operations and comprehensive loss: For the Year Ended December 31, 2023 2022 Research and development expenses $ 2,770 $ 2,798 General and administrative expenses 3,230 3,954 Total stock-based compensation expense $ 6,000 $ 6,752 No income tax benefits have been recorded for the years ended December 31, 2023 and 2022, as the Company has recorded a full valuation allowance and management has concluded that it is more likely than not that the net deferred tax assets will not be realized (see Note 13, Income Taxes).

Retirement Savings Plan

Retirement Savings Plan	12 Months Ended
	Dec. 31, 2023
Retirement Benefits [Abstract]
Retirement Savings Plan	Retirement Savings Plan

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes For the years ended December 31, 2023 and 2022, the Company did not record any federal or state income tax expense given its continued operating losses, all of which were attributable to the United States. A reconciliation between income tax benefit and the expected tax benefit at the statutory rate for the years ended December 31, 2023 and 2022 are as follows: For the Year Ended 2023 2022 Statutory federal income tax rate 21.0 % 21.0 % State income taxes, net of federal benefit 6.1 % 6.0 % Research and development tax credits 3.7 % 3.3 % Orphan drug tax credits 4.9 % 4.4 % Expiration of NOLs/credits (6.3) % (3.2) % Other 1.5 % (0.6) % Stock based compensation (2.5) % — % Change in valuation allowance (28.4) % (30.9) % Effective income tax rate — % — % The principal components of the Company’s deferred tax assets at December 31, 2023 and December 31, 2022, respectively, are as follows: December 31, 2023 2022 Deferred Tax Assets: NOL carryforwards $ 91,036 $ 79,827 Research and development tax credit carryforwards 16,973 15,996 Orphan drug tax credit carryforwards 24,983 22,565 Depreciation and amortization 5,552 6,449 Capitalized research and development expenditures 42,271 41,168 Stock options 4,857 4,506 Accrued expenses and other 973 1,067 Oberland agreement 11,640 13,285 Lease liability 763 1,072 Total gross deferred tax asset 199,048 185,935 Valuation allowance (198,212) (184,738) Net deferred tax asset $ 836 $ 1,197 Deferred tax liabilities: Right of use asset (836) (1,197) Total gross deferred tax liabilities $ (836) $ (1,197) Net deferred tax assets (liabilities) $ — $ — As of December 31, 2023, the Company had U.S. federal tax-effected net operating loss carryforwards of $74.8 million, of which $34.1 million will expire in years 2024 through 2037 and the remainder do not expire but are subject to 80% limitation. As of December 31, 2023, the Company had state net operating loss carryforwards of $16.2 million that will expire between years 2033 and 2043. As of December 31, 2023 and 2022, the Company had federal research and development credit carryforwards of $12.9 million and $12.2 million, respectively. The credits will expire in the years 2024 through 2043. As of December 31, 2023 and 2022, the Company had state research and development credit carryforwards of $4.1 million and $3.8 million, respectively. The credits will expire in the years 2024 through 2038, unless previously utilized. As of December 31, 2023 and 2022, the Company had orphan drug tax credit carryforwards of $25.0 million and $22.6 million, respectively. These credits, if any, relate to qualified expenses incurred for fimepinostat and emavusertib since receiving the Orphan Drug designation. The credits will expire in the years 2035 through 2043. As of December 31, 2023 and 2022, the Company had deferred tax assets associated with the capitalization of Section 174 costs of $16.9 million and $9.8 million, respectively, which were included in capitalized research and development expenditures in the table above. The Company has evaluated the positive and negative evidence bearing upon the realizability of its deferred tax assets, and has determined that it is more likely than not that the Company will not recognize the benefits of the deferred tax assets. Accordingly, the Company had a valuation allowance of approximately $198.2 million and $184.7 million as of December 31, 2023 and 2022, respectively. The valuation allowance increased approximately $13.5 million and $17.3 million during the years ended December 31, 2023 and 2022. Utilization of the NOL may be subject to a substantial annual limitation under Section 382 of the Internal Revenue Code of 1986 due to ownership change limitations that have occurred previously or that could occur in the future. These ownership changes may limit the amount of NOL carryforwards that can be utilized annually to offset future taxable income and tax, respectively. The Company completed a §382 study in 2019 and determined no ownership changes have occurred and no limitation on NOLs through December 31, 2018. There could be additional ownership changes in the future, which may result in additional limitations in the utilization of the carryforward NOLs and credits, and the Company does not expect to have any taxable income for the foreseeable future. An individual tax position must satisfy for some or all of the benefits of that position to be recognized in a company’s financial statements. At December 31, 2023 and 2022, the Company had no unrecognized tax benefits. The Company has not, as yet, conducted a study of its R&D credit carryforwards. This study may result in an adjustment to the Company’s R&D credit carryforwards, however, until a study is completed and any adjustment is known, no amounts are being presented as an uncertain tax position under FASB Codification Topic 740 Income Taxes . A full valuation allowance has been provided against the Company’s R&D credits and, if an adjustment is required, this adjustment would be offset by an adjustment to the valuation allowance. Thus, there would be no impact to the consolidated balance sheets or consolidated statements of operations and comprehensive loss if an adjustment were required. As of December 31, 2023, the Company is generally no longer subject to examination by taxing authorities for years prior to 2020. However, NOL’s and credits in the United States may be subject to adjustments by taxing authorities in future years in which they are utilized. The Company is currently not under examination by the IRS or any other jurisdictions for any tax years. The Company recognizes both accrued interest and penalties related to unrecognized benefits in income tax expense. The Company has not recorded any interest or penalties on any unrecognized tax benefits since its inception.

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Pay vs Performance Disclosure
Net loss	$ (47,413)	$ (56,672)

Insider Trading Arrangements

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

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Basis of Presentation and Principles of Consolidation	Basis of Presentation and Principles of Consolidation The accompanying consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the U.S. (“GAAP”) and include the accounts of our wholly owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation.
Use of Estimates and Assumptions	Use of Estimates and Assumptions
Cash Equivalents, Restricted Cash, and Investments	Cash Equivalents, Restricted Cash, and Investments Cash equivalents consist of highly liquid investments purchased with original maturities of three months or less. All other investments are marketable securities. The Company separately classified $0.5 million and $0.6 million of its cash as restricted cash, long-term as of December 31, 2023 and 2022, respectively. These amounts represent the security deposit associated with the Company's Lexington, Massachusetts headquarters. The Company’s short-term investments are marketable debt securities with original maturities of greater than three months from the date of purchase, but less than twelve months from the balance sheet date. Marketable securities consist of commercial paper, corporate bonds and notes, and/or government obligations. All of the Company’s investments have been designated available-for-sale and are stated at fair value. Unrealized gains and losses on investments are included in accumulated other comprehensive income (loss) as a separate component of stockholders’ equity. Realized gains and losses, dividends and interest income are included in other income (expense) in the period during which the securities are sold. Any premium or discount arising at purchase is amortized and/or accreted to interest income.
Concentrations and Significant Customer Information	Concentrations and Significant Customer Information Financial instruments which potentially subject the Company to concentrations of credit risk consist principally of cash and cash equivalents, marketable securities, and accounts receivable. The Company maintains deposits in federally insured financial institutions in excess of federally insured limits. Management believes that the Company is not exposed to significant credit risk due to the financial position of the depository institutions in which those deposits are held. The Company’s credit risk related to investments is reduced as a result of the Company’s policy to limit the amount invested in any one issue. The Company's operations are located entirely within the U.S. The Company's focus is primarily on the development of emavusertib, a small molecule IRK4 inhibitor. The Company's customer, Genentech, accounted for 99% and 100% of the total gross revenues for the years ended December 31, 2023 and 2022, respectively. The Company’s accounts receivable at December 31, 2023 and December 31, 2022 represents amounts due from royalties earned on sales of Erivedge by Genentech and Roche.
Long-Lived Assets Other than Goodwill	Long-Lived Assets Other than Goodwill Long-lived assets other than goodwill consist of property and equipment. The Company applies the guidance in FASB Codification Topic 360-10-05, Impairment or Disposal of Long-Lived Assets
Leases	Leases The Company determines if an arrangement is a lease at contract inception. The Company made an accounting policy election to not recognize leases with an initial term of 12 months or less within its consolidated balance sheets and to recognize those lease payments on a straight-line basis in its consolidated statements of operations and comprehensive loss over the lease term. Operating lease assets represent the Company's right to use an underlying asset for the lease term and operating lease liabilities represent its obligation to make lease payments arising from the lease. Operating lease assets and liabilities are recognized at the commencement date of the lease based upon the present value of lease payments over the lease term. When determining the lease term, the Company includes options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. As the Company's lease does not provide an implicit interest rate, the Company uses its incremental borrowing rate, which is based on rates that would be incurred to borrow on a collateralized basis over a term equal to the lease payments in a similar economic environment, in determining the present value of lease payments. The lease payment used to determine the operating lease asset may include lease incentives, stated rent increases and was recognized as an operating lease right-of-use asset in the consolidated balance sheets. The Company's lease agreements may include both lease and non-lease components, which may be accounted for as a single lease component when the payments are fixed. Variable payments included in the lease agreement are expensed as incurred.
Other assets	Other assets Other assets consist of long-term prepayments and deposits.
Goodwill	Goodwill
Revenue Recognition	Revenue Recognition The Company applies the revenue recognition guidance in accordance with FASB Codification Topic 606, Revenue from Contracts with Customers .
Research and Development	Research and Development Research and development expense primarily consists of costs incurred to discover, research and develop emavusertib. These expenses primarily include: (1) salaries and related expenses for personnel, including stock-based compensation expense; (2) costs of conducting clinical trials, including amounts paid to clinical centers, clinical research organizations and consultants; (3) other outside service including regulatory and costs of contract manufacturing; (4) the cost of companion drugs; (5) facility costs; and (6) certain payments that we make under our collaboration agreements. The Company expenses research and development costs as they are incurred.
Basic and Diluted Loss per Common Share	Basic and Diluted Loss per Common Share
Stock-Based Compensation	Stock-Based Compensation The Company accounts for stock-based compensation transactions using a grant-date fair-value based method under FASB Codification Topic 718, Compensation-Stock Compensation . The Company measures compensation cost for stock-based compensation at fair value and recognizes the expense as compensation expense over the period that the recipient is required to provide service in exchange for the award, which generally is the vesting period. The Company uses the Black-Scholes option pricing model to measure the fair value of stock options. This model requires estimates related to the award’s expected life and future stock price volatility of the underlying equity security. Actual compensation expense recognized over the vesting period will only be for those shares that vest.
Comprehensive Loss	Comprehensive Loss Comprehensive loss is comprised of net loss and other comprehensive income (loss). Other comprehensive income (loss) includes unrealized gains and losses arising during the period on available-for-sale securities.
Segment Reporting	Segment Reporting
Interest Expense on Liability related to the Sale of Future Royalties	Interest Expense on Liability related to the Sale of Future Royalties
New Accounting Pronouncements	New Accounting Pronouncements Issued, Not Yet Adopted In November 2023, the FASB issued ASU No. 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures , which provides updates to qualitative and quantitative reportable segment disclosure requirements, including enhanced disclosures about significant segment expenses and increased interim disclosure requirements, among others. ASU No. 2023-07 is effective for fiscal years beginning after December 15, 2023, and interim periods in fiscal years beginning after December 15, 2024. Early adoption is permitted, and the amendments should be applied retrospectively. The Company is currently evaluating the impact of the ASU on the consolidated financial statement disclosures. In December 2023, the FASB issued ASU No. 2023-09, Improvements to Income Tax Disclosures , which requires disclosure of disaggregated income taxes paid, prescribes standard categories for the components of the effective tax rate reconciliation, and modifies other income tax-related disclosures. ASU No. 2023-09 is effective for fiscal years beginning after December 15, 2024 and allows for adoption on a prospective basis, with a retrospective option. Early adoption is permitted. The Company is currently evaluating the impact of the ASU on the income tax disclosures within the consolidated financial statements.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The Company applies the provisions of FASB Codification 820, Fair Value Measurements (“ASC 820”) for its financial assets and liabilities that are re-measured and reported at fair value each reporting period and the non-financial assets and liabilities that are re-measured and reported at fair value on a non-recurring basis. Fair value is the price that would be received from selling an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. When determining fair value, the Company considers the principal or most advantageous market in which it would transact and considers assumptions that market participants would use when pricing the asset or liability. ASC 820 establishes a three-level valuation hierarchy for disclosure of fair value measurements. Financial assets and liabilities are categorized within the valuation hierarchy based upon the lowest level of input that is significant to the measurement of fair value. The three levels of the hierarchy are defined 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 not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Schedule of Estimated Useful Lives of Long-Lived Assets Other Than Goodwill	Depreciation and amortization are provided on the straight-line method over the estimated useful lives of the related assets or the remaining terms of the leases, whichever is shorter, as follows: Useful Life Laboratory equipment, computers and software 3-5 years Leasehold improvements Lesser of lease or asset life Office furniture and equipment 5 years

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Schedule of Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis	In accordance with the fair value hierarchy, the following tables show the fair value as of December 31, 2023 and 2022 of those financial assets and liabilities that are measured at fair value on a recurring basis, according to the valuation techniques the Company used to determine their fair value. Quoted Prices in Other Unobservable Fair Value (in thousands) As of December 31, 2023 Cash equivalents: Money market funds $ 16,780 $ — $ — $ 16,780 U.S. treasury securities and government agency obligations — 4,735 — 4,735 Corporate debt securities and commercial paper — 2,021 — 2,021 Short-term investments: Corporate debt securities and commercial paper — 12,996 — 12,996 U.S. treasury securities and government agency obligations — 16,657 — 16,657 Total $ 16,780 $ 36,409 $ — $ 53,189 Quoted Prices in Other Unobservable Fair Value (in thousands) As of December 31, 2022 Cash equivalents: Money market funds $ 15,215 $ — $ — $ 15,215 U.S. treasury securities and government agency obligations — 2,998 — 2,998 Short-term investments: Corporate debt securities and commercial paper — 42,071 — 42,071 U.S. treasury securities and government agency obligations — 23,894 — 23,894 Total assets at fair value $ 15,215 $ 68,963 $ — $ 84,178

Investments (Tables)

Investments (Tables)	12 Months Ended
	Dec. 31, 2023
Investments, Debt and Equity Securities [Abstract]
Schedule of Amortized Cost, Unrealized Gains and Losses and Fair Value of Investments Available-for-Sale	The amortized cost, unrealized gains and losses and fair value of investments available-for-sale as of December 31, 2023 are as follows: (in thousands) Amortized Unrealized Unrealized Fair Value Short-term investments: Corporate debt securities and commercial paper $ 12,999 $ — $ (3) $ 12,996 U.S. treasury securities and government agency obligations 16,655 3 (1) 16,657 Total investments $ 29,654 $ 3 $ (4) $ 29,653 The amortized cost, unrealized gains and losses and fair value of investments available-for-sale as of December 31, 2022 are as follows: (in thousands) Amortized Unrealized Unrealized Fair Value Short-term investments: Corporate debt securities and commercial paper $ 42,109 $ 2 $ (40) $ 42,071 U.S. treasury securities and government agency obligations 24,042 — (148) 23,894 Total investments $ 66,151 $ 2 $ (188) $ 65,965

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	12 Months Ended
	Dec. 31, 2023
Property, Plant and Equipment [Abstract]
Schedule of Property and Equipment	Property and equipment consisted of the following: December 31, (in thousands) 2023 2022 Laboratory equipment, computers and software $ 1,140 $ 1,776 Leasehold improvements 257 257 Office furniture and equipment 1,028 1,113 2,425 3,146 Less—Accumulated depreciation and amortization (1,991) (2,457) Property and equipment, net $ 434 $ 689

Accrued Liabilities (Tables)

Accrued Liabilities (Tables)	12 Months Ended
	Dec. 31, 2023
Other Liabilities Disclosure [Abstract]
Schedule of Accrued Liabilities	Accrued liabilities consisted of the following: December 31, (in thousands) 2023 2022 Headcount related costs $ 3,701 $ 3,152 Research and development costs 4,163 1,727 Professional and legal fees 1,059 762 Other 117 38 Total $ 9,040 $ 5,679

Leases and Commitments (Tables)

Leases and Commitments (Tables)	12 Months Ended
	Dec. 31, 2023
Leases [Abstract]
Schedule of Balance Sheet Information for Operating Leases	The Company's lease is an operating lease. The following table summarizes the presentation in the Company's consolidated balance sheet for the operating lease: December 31, (in thousands) 2023 2022 Assets: Operating lease right-of-use asset $ 3,056 $ 4,401 Liabilities: Operating lease liability - short-term $ 1,305 $ 1,141 Operating lease liability - long-term 1,489 2,800 Total operating liability $ 2,794 $ 3,941
Schedule of Lease Cost	The following table summarizes the effect of lease costs in our consolidated statements of operations and comprehensive loss: For the Year Ended December 31, (in thousands) 2023 2022 Operating lease cost Research and development $ 483 $ 1,187 General and administrative 1,182 382 Total $ 1,665 $ 1,569
Schedule of Lease Maturity Schedule	The Company’s lease payments through the end of the expected lease term are expected to be as follows: Year Ending December 31, (in thousands) 2024 1,512 2025 1,558 Total lease payments $ 3,070 Less: interest 276 Present value of operating lease liabilities $ 2,794

Liability Related to the Sale_2

Liability Related to the Sale of Future Royalties (Tables)	12 Months Ended
	Dec. 31, 2023
Nonmonetary Transactions [Abstract]
Schedule of Liability Related to the Sale of Future Royalties	The following table shows the activity with respect to the liability related to the sale of future royalties during the years ended December 31, 2022 and 2023: (in thousands) Carrying value of liability related to the sale of future royalties at January 1, 2022 $ 53,798 Other 739 Imputed interest expense 4,033 Less: payments to the Purchasers (9,087) Carrying value of liability related to the sale of future royalties at December 31, 2022 $ 49,483 Other (119) Imputed interest expense 2,138 Less: payments to the Purchasers (8,896) Carrying value of liability related to the sale of future royalties at December 31, 2023 $ 42,606

Stock Plans and Stock-Based C_2

Stock Plans and Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Schedule of Stock Option	A summary of stock option activity under the 2010 Plan and Inducement Awards are summarized as follows: Number of Weighted Weighted Aggregate Intrinsic Value Outstanding, December 31, 2022 683,666 $ 64.72 6.51 Granted 284,542 13.90 Exercised (515) 13.40 Canceled (126,813) 64.58 Outstanding, December 31, 2023 840,880 $ 47.58 7.16 $ 91 Exercisable at December 31, 2023 450,008 $ 63.00 5.77 $ — Vested and unvested expected to vest at December 31, 2023 840,880 $ 47.58 7.16 $ 91
Schedule of Valuation Assumptions Used to Calculate Fair Value of Employee Options Awarded	the following estimated assumptions under the Black-Scholes option pricing model: For the Year Ended 2023 2022 Expected term (years) 5.5 5.5 Risk-free interest rate 3.5-4.7% 1.4-4.1% Expected volatility 115-116% 110-115% Expected dividend yield None None
Schedule of Unvested Restricted Stock Shares Activity	The following table presents a summary of outstanding RSAs under the 2010 Plan as of December 31, 2023: Number of Weighted Unvested, December 31, 2022 — $ — Awarded 117,000 18.20 Vested — — Forfeited (6,500) 18.20 Unvested, December 31, 2023 110,500 $ 18.20
Schedule of Stock-Based Compensation Expense	For the years ended December 31, 2023 and 2022, the Company recorded employee and non-employee stock-based compensation expense to the following line items in its costs and expenses section of the consolidated statements of operations and comprehensive loss: For the Year Ended December 31, 2023 2022 Research and development expenses $ 2,770 $ 2,798 General and administrative expenses 3,230 3,954 Total stock-based compensation expense $ 6,000 $ 6,752

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Schedule of Effective Income Tax Rate Reconciliation	A reconciliation between income tax benefit and the expected tax benefit at the statutory rate for the years ended December 31, 2023 and 2022 are as follows: For the Year Ended 2023 2022 Statutory federal income tax rate 21.0 % 21.0 % State income taxes, net of federal benefit 6.1 % 6.0 % Research and development tax credits 3.7 % 3.3 % Orphan drug tax credits 4.9 % 4.4 % Expiration of NOLs/credits (6.3) % (3.2) % Other 1.5 % (0.6) % Stock based compensation (2.5) % — % Change in valuation allowance (28.4) % (30.9) % Effective income tax rate — % — %
Schedule of Components of Deferred Tax Assets	The principal components of the Company’s deferred tax assets at December 31, 2023 and December 31, 2022, respectively, are as follows: December 31, 2023 2022 Deferred Tax Assets: NOL carryforwards $ 91,036 $ 79,827 Research and development tax credit carryforwards 16,973 15,996 Orphan drug tax credit carryforwards 24,983 22,565 Depreciation and amortization 5,552 6,449 Capitalized research and development expenditures 42,271 41,168 Stock options 4,857 4,506 Accrued expenses and other 973 1,067 Oberland agreement 11,640 13,285 Lease liability 763 1,072 Total gross deferred tax asset 199,048 185,935 Valuation allowance (198,212) (184,738) Net deferred tax asset $ 836 $ 1,197 Deferred tax liabilities: Right of use asset (836) (1,197) Total gross deferred tax liabilities $ (836) $ (1,197) Net deferred tax assets (liabilities) $ — $ —

Nature of Business (Details)

Nature of Business (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accumulated deficit	$ 1,196,410	$ 1,148,997
Net loss	47,413	56,672
Net cash used in operating activities	38,434	$ 54,337
Cash, cash equivalents, and investments	$ 56,300

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Narrative (Details)		12 Months Ended
	Sep. 28, 2023	Dec. 31, 2023 USD ($) segment	Dec. 31, 2022 USD ($)
Significant Accounting Policies [Line Items]
Reverse stock split ratio	0.05
Restricted cash		$ 500,000	$ 600,000
Goodwill		8,982,000	8,982,000
Goodwill impairment charges		$ 0	$ 0
Number of reportable segments | segment		1
Customer Concentration Risk | Genentech, Inc. | Revenue Benchmark
Significant Accounting Policies [Line Items]
Total gross revenue		99%	100%

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Schedule of Estimated Useful Lives of Long-Lived Assets (Details)	Dec. 31, 2023
Office furniture and equipment
Property, Plant and Equipment [Line Items]
Useful Life	5 years
Minimum | Laboratory equipment, computers and software
Property, Plant and Equipment [Line Items]
Useful Life	3 years
Maximum | Laboratory equipment, computers and software
Property, Plant and Equipment [Line Items]
Useful Life	5 years

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Antidilutive Securities (Details) - shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Employee Stock Option
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total antidilutive securities (in shares)	840,880	683,666
Restricted Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total antidilutive securities (in shares)	110,500

Fair Value of Financial Instr_3

Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Short-term investments:
Available for sale debt securities	$ 100	$ 200
Fair Value, Measurements, Recurring
Short-term investments:
Total	53,189	84,178
Fair Value, Measurements, Recurring | Corporate debt securities and commercial paper
Short-term investments:
Short-term investments:	12,996	42,071
Fair Value, Measurements, Recurring | U.S. treasury securities and government agency obligations
Short-term investments:
Short-term investments:	16,657	23,894
Fair Value, Measurements, Recurring | Money market funds
Cash equivalents:
Cash equivalents:	16,780	15,215
Fair Value, Measurements, Recurring | U.S. treasury securities and government agency obligations
Cash equivalents:
Cash equivalents:	4,735	2,998
Fair Value, Measurements, Recurring | Corporate debt securities and commercial paper | Corporate debt securities and commercial paper
Cash equivalents:
Cash equivalents:	2,021
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets (Level 1)
Short-term investments:
Total	16,780	15,215
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets (Level 1) | Corporate debt securities and commercial paper
Short-term investments:
Short-term investments:	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets (Level 1) | U.S. treasury securities and government agency obligations
Short-term investments:
Short-term investments:	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets (Level 1) | Money market funds
Cash equivalents:
Cash equivalents:	16,780	15,215
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets (Level 1) | U.S. treasury securities and government agency obligations
Cash equivalents:
Cash equivalents:	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets (Level 1) | Corporate debt securities and commercial paper | Corporate debt securities and commercial paper
Cash equivalents:
Cash equivalents:	0
Fair Value, Measurements, Recurring | Other Observable Inputs (Level 2)
Short-term investments:
Total	36,409	68,963
Fair Value, Measurements, Recurring | Other Observable Inputs (Level 2) | Corporate debt securities and commercial paper
Short-term investments:
Short-term investments:	12,996	42,071
Fair Value, Measurements, Recurring | Other Observable Inputs (Level 2) | U.S. treasury securities and government agency obligations
Short-term investments:
Short-term investments:	16,657	23,894
Fair Value, Measurements, Recurring | Other Observable Inputs (Level 2) | Money market funds
Cash equivalents:
Cash equivalents:	0	0
Fair Value, Measurements, Recurring | Other Observable Inputs (Level 2) | U.S. treasury securities and government agency obligations
Cash equivalents:
Cash equivalents:	4,735	2,998
Fair Value, Measurements, Recurring | Other Observable Inputs (Level 2) | Corporate debt securities and commercial paper | Corporate debt securities and commercial paper
Cash equivalents:
Cash equivalents:	2,021
Fair Value, Measurements, Recurring | Unobservable Inputs (Level 3)
Short-term investments:
Total	0	0
Fair Value, Measurements, Recurring | Unobservable Inputs (Level 3) | Corporate debt securities and commercial paper
Short-term investments:
Short-term investments:	0	0
Fair Value, Measurements, Recurring | Unobservable Inputs (Level 3) | U.S. treasury securities and government agency obligations
Short-term investments:
Short-term investments:	0	0
Fair Value, Measurements, Recurring | Unobservable Inputs (Level 3) | Money market funds
Cash equivalents:
Cash equivalents:	0	0
Fair Value, Measurements, Recurring | Unobservable Inputs (Level 3) | U.S. treasury securities and government agency obligations
Cash equivalents:
Cash equivalents:	0	$ 0
Fair Value, Measurements, Recurring | Unobservable Inputs (Level 3) | Corporate debt securities and commercial paper | Corporate debt securities and commercial paper
Cash equivalents:
Cash equivalents:	$ 0

Investments - Schedule of Amort

Investments - Schedule of Amortized Cost, Unrealized Gains and Losses and Fair Value of Investments Available-for-Sale (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 29,654	$ 66,151
Unrealized Gain	3	2
Unrealized Loss	(4)	(188)
Fair Value	29,653	65,965
Corporate debt securities and commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	12,999	42,109
Unrealized Gain	0	2
Unrealized Loss	(3)	(40)
Fair Value	12,996	42,071
U.S. treasury securities and government agency obligations
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	16,655	24,042
Unrealized Gain	3	0
Unrealized Loss	(1)	(148)
Fair Value	$ 16,657	$ 23,894

Investments - Narrative (Detail

Investments - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Investments, Debt and Equity Securities [Abstract]
Range of maturities	2 months 12 days	3 months 18 days
Debt securities, available-for-sale, credit loss	$ 0	$ 0
Fair value of available-for-sale investments in a continuous unrealized loss position for 12 months or longer	$ 0	$ 27,400,000

Property and Equipment, Net - S

Property and Equipment, Net - Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Property and equipment	$ 2,425	$ 3,146
Less—Accumulated depreciation and amortization	(1,991)	(2,457)
Property and equipment, net	434	689
Laboratory equipment, computers and software
Property, Plant and Equipment [Line Items]
Property and equipment	1,140	1,776
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment	257	257
Office furniture and equipment
Property, Plant and Equipment [Line Items]
Property and equipment	$ 1,028	$ 1,113

Property and Equipment, Net - N

Property and Equipment, Net - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Abstract]
Depreciation and amortization expense	$ 255	$ 233

Accrued Liabilities (Details)

Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Other Liabilities Disclosure [Abstract]
Headcount related costs	$ 3,701	$ 3,152
Research and development costs	4,163	1,727
Professional and legal fees	1,059	762
Other	117	38
Total	$ 9,040	$ 5,679

Leases and Commitments - Narrat

Leases and Commitments - Narrative (Details) $ in Thousands	1 Months Ended	12 Months Ended
	Jan. 31, 2022 USD ($) ft² $ / ft²	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Lessee, Lease, Description [Line Items]
Operating lease payments		$ 1,500
Decrease in operating lease right of use asset			$ 200
Discount rate (percent)		10%
Lease term		6 years
Operating lease cash obligation		$ 8,800
Cost of royalties		$ 212	$ 257
128 Spring Street Lease Amendment
Lessee, Lease, Description [Line Items]
Area of real estate property | ft²	9,340
Cost of existing space | $ / ft²	30
Operating lease payments	$ 300
Lessor option to terminate, written notice period		18 months

Leases and Commitments - Schedu

Leases and Commitments - Schedule of Balance Sheet Information for Operating Leases (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Leases [Abstract]
Operating lease right-of-use asset	$ 3,056	$ 4,401
Operating lease liability - short-term	1,305	1,141
Operating lease liability - long-term	1,489	2,800
Total operating liability	$ 2,794	$ 3,941

Leases and Commitments - Sche_2

Leases and Commitments - Schedule of Lease Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Lessee, Lease, Description [Line Items]
Operating lease cost	$ 1,665,000	$ 1,569
Research and development expenses
Lessee, Lease, Description [Line Items]
Operating lease cost	483,000	1,187
General and administrative expenses
Lessee, Lease, Description [Line Items]
Operating lease cost	$ 1,182,000	$ 382

Leases and Commitments - Sche_3

Leases and Commitments - Schedule of Lease Maturity Schedule (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Future Lease Payments (Topic 842)
2024	$ 1,512
2025	1,558
Total lease payments	3,070
Less: interest	276
Present value of operating lease liabilities	$ 2,794	$ 3,941

Liability Related to the Sale_3

Liability Related to the Sale of Future Royalties - Narrative (Details) - USD ($) $ in Millions	1 Months Ended
	Mar. 31, 2019	Dec. 31, 2023
Nonmonetary Transaction [Line Items]
Non-cash interest rate	1.50%
Transaction fees	$ 0.6
Oberland Capital
Nonmonetary Transaction [Line Items]
Transaction expenses	$ 65
Purchaser default option period	180 days
Percentage of royalty purchase agreement	250%
Estimated price amount		$ 56.9
Oberland Capital | Aggregate Net Royalties Prior To 2027
Nonmonetary Transaction [Line Items]
Cash proceeds from royalty purchase agreement	$ 53.5
Royalty amount threshold	$ 117

Liability Related to the Sale_4

Liability Related to the Sale of Future Royalties - Schedule of Liability Related to the Sale of Future Royalties (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Nonmonetary Transaction [Roll Forward]
Beginning balance	$ 49,483	$ 53,798
Other	(119)	739
Imputed interest expense	2,138	4,033
Less: payments to the Purchasers	(8,896)	(9,087)
Ending balance	$ 42,606	$ 49,483

Common Stock (Details)

Common Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	12 Months Ended
	Jul. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Feb. 08, 2024	Sep. 30, 2023	Mar. 31, 2021	Feb. 29, 2020
Common Stock And Warrant Liability [Line Items]
Common stock, shares authorized (in shares)		22,781,250	11,390,625		11,390,625
Net proceeds from sale of common stock		$ 14,117	$ 5,842
Registered Direct Offering
Common Stock And Warrant Liability [Line Items]
Number of shares sold (in shares)	920,488
Net proceeds from sale of common stock	$ 13,800
Sale price per share (in dollars per share)	$ 16.40
Common Stock | Cantor Fitzgerald And Co
Common Stock And Warrant Liability [Line Items]
Compensation fee						3%
Number of shares sold (in shares)			229,185
Net proceeds from sale of common stock		$ 6,300
Common Stock | Cantor Fitzgerald And Co | Subsequent Event
Common Stock And Warrant Liability [Line Items]
Compensation fee				3%
Common Stock | Aspire Capital Fund, LLC
Common Stock And Warrant Liability [Line Items]
Authorized purchase program amount							$ 30,000

Research and Development Coll_2

Research and Development Collaborations (Details)	1 Months Ended		12 Months Ended
	Sep. 30, 2016 USD ($) program	Jun. 30, 2003 USD ($)	Dec. 31, 2023 USD ($) program product	Dec. 31, 2022 USD ($)	Feb. 29, 2020
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenues			$ 10,023,000	$ 10,162,000
Accounts receivable			$ 2,794,000	2,975,000
Number of programs licensed | program	4		4
Genentech, Inc.
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Amount received for specified clinical development and regulatory objectives			$ 59,000,000
Percentage of royalty rate decrease		2%
Accounts receivable			2,700,000	3,000,000
Genentech, Inc. | Royalties
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenues			$ 9,900,000	$ 10,300,000
Genentech, Inc. | Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Eligible to receive contingent cash milestone payments (up to)		$ 115,000,000
Percentage of royalty on net sales		7.50%
Genentech, Inc. | Minimum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Percentage of royalty on net sales		5%
Aurigene Discovery Technologies Limited
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Waived payment of milestone and other payments (up to)	$ 24,500,000
Number of products required to commercialize | product			1
Aurigene Discovery Technologies Limited | Third and Fourth Programs
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Additional funding	$ 2,000,000
Aurigene Discovery Technologies Limited | IRAK4, PD1/VISTA,PD1/TIM3 Program
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Waived payment of milestone and other payments (up to)			$ 42,500,000
Aurigene Discovery Technologies Limited | Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Royalty fees receivable (as a percent)					10%

Stock Plans and Stock-Based C_3

Stock Plans and Stock-Based Compensation - Narrative (Details)	12 Months Ended
	Dec. 31, 2023 USD ($) plan purchase_period $ / shares shares	Dec. 31, 2022 USD ($) $ / shares shares
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Number of shareholder-approved, share-based compensation plans | plan	2
Granted (in shares)	284,542
Weighted average grant-date fair values of stock options (in dollars per share) | $ / shares	$ 11.70	$ 42.80
Unrecognized compensation cost, including impact of estimated forfeitures | $	$ 8,000,000
Weighted average period of when compensation expense is expected to be recognized	2 years 6 months
Income tax benefit | $	$ 0	$ 0
Employee Stock Option
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Vesting period (years)	4 years
Awarded (in shares)	43,112
Employee Stock Option | Award Vesting After First Year
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Percentage of vested shares which are exercisable under stock option	25%
Employee Stock Option | Quarterly Vesting After First Year
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Percentage of vested shares which are exercisable under stock option	6.25%
Restricted Stock
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Awarded (in shares)	117,000
Weighted average period of when compensation expense is expected to be recognized	1 year 4 months 24 days
Outstanding shares (in shares)	110,500	0
Aggregate fair value of restricted stock | $	$ 2,100,000
Compensation expense related to employee and director stock option grants | $	$ 1,400,000
Restricted Stock | First Anniversary of Grant Date
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Percentage of vested shares which are exercisable under stock option	50%
Restricted Stock | Second Anniversary of Grant Date
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Percentage of vested shares which are exercisable under stock option	50%
Amended and Restated 2010 Stock Incentive Plan
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Number of shares available for issue (up to)	1,159,500
Period of time options are exercisable	10 years
Number of shares under award to be removed from share pool (in shares)	289,912
Amended and Restated 2010 Stock Incentive Plan | Stock Options, or Stock Appreciation Rights
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Shares removed from available share pool (in shares)	1
Amended and Restated 2010 Stock Incentive Plan | Restricted Stock, RSUs, Other Stock-Based Awards, or Performance Awards
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Shares removed from available share pool (in shares)	1.3
Price charged for award based on fair market value percentage (less than)	100%
2010 Plan
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Granted (in shares)	220,180
2010 Plan | Employee Stock Option | Non-Employee Directors
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Granted (in shares)	21,250
Vesting period (years)	1 year
2010 Plan | Employee Stock Option | Award Vesting After First Year
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Percentage of vested shares which are exercisable under stock option	25%
2010 Plan | Employee Stock Option | Quarterly Vesting After First Year
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Percentage of vested shares which are exercisable under stock option	6.25%
2010 Plan | Restricted Stock
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Aggregate amount of granted restricted stock awards, or RSAs (in shares)	117,000
2010 Employee Stock Purchase Plan
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Shares issued under ESPP during period (in shares)	32,117
Shares available for future purchase under ESPP (in shares)	26,631
2010 Employee Stock Purchase Plan | Employee Stock Purchase Plan
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Price charged for award based on fair market value percentage (less than)	85%
Shares available under plan (in shares)	100,000
Enrollment period	2 years
Number of purchase periods per year | purchase_period	4
Term of purchase periods	6 months

Stock Plans and Stock-Based C_4

Stock Plans and Stock-Based Compensation - Schedule of Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Number of Options
Beginning balance (in shares)	683,666
Granted (in shares)	284,542
Exercised (in shares)	(515)
Canceled (in shares)	(126,813)
Ending balance (in shares)	840,880	683,666
Exercisable at end of period (in shares)	450,008
Vested and unvested expected to vest at end of period (in shares)	840,880
Weighted Average Exercise Price per Share
Beginning balance (in dollars per share)	$ 64.72
Granted (in dollars per share)	13.90
Exercised (in dollars per share)	13.40
Canceled (in dollars per share)	64.58
Ending balance (in dollars per share)	47.58	$ 64.72
Exercisable at end of period (in dollars per share)	63
Vested and unvested expected to vest at end of period (in dollars per share)	$ 47.58
Weighted Average Remaining Contractual Life
Outstanding at end of period	7 years 1 month 28 days	6 years 6 months 3 days
Exercisable at end of period	5 years 9 months 7 days
Vested and unvested expected to vest at end of period	7 years 1 month 28 days
Aggregate Intrinsic Value
Outstanding at end of period	$ 91
Exercisable at end of period	0
Vested and unvested expected to vest at end of period	$ 91

Stock Plans and Stock-Based C_5

Stock Plans and Stock-Based Compensation - Key Assumptions (Details) - Employees and Officers	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Expected term (years)	5 years 6 months	5 years 6 months
Minimum risk-free interest rate (percent)	3.50%	1.40%
Maximum risk-free interest rate (percent)	4.70%	4.10%
Minimum volatility (percent)	115%	110%
Maximum volatility (percent)	116%	115%

Stock Plans and Stock-Based C_6

Stock Plans and Stock-Based Compensation - Summary of Activity RSU (Details) - Restricted Stock	12 Months Ended
	Dec. 31, 2023 $ / shares shares
Number of Shares
Beginning balance (in shares) | shares	0
Awarded (in shares) | shares	117,000
Vested (in shares) | shares	0
Forfeited (in shares) | shares	(6,500)
Ending balance (in shares) | shares	110,500
Weighted Average Grant Date Fair Value
Beginning balance (in dollars per share) | $ / shares	$ 0
Awarded (in dollars per share) | $ / shares	18.20
Vested (in dollars per share) | $ / shares	0
Forfeited (in dollars per share) | $ / shares	18.20
Ending balance (in dollars per share) | $ / shares	$ 18.20

Stock Plans and Stock-Based C_7

Stock Plans and Stock-Based Compensation - Compensation Expense Allocation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Total stock-based compensation expense	$ 6,000	$ 6,752
Research and development expenses
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Total stock-based compensation expense	2,770	2,798
General and administrative expenses
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Total stock-based compensation expense	$ 3,230	$ 3,954

Retirement Savings Plan (Detail

Retirement Savings Plan (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Retirement Benefits [Abstract]
Matching contribution	$ 0.6	$ 0.7

Income Taxes - Schedule of Effe

Income Taxes - Schedule of Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Statutory federal income tax rate	21%	21%
State income taxes, net of federal benefit	6.10%	6%
Research and development tax credits	3.70%	3.30%
Orphan drug tax credits	4.90%	4.40%
Expiration of NOLs/credits	(6.30%)	(3.20%)
Other	1.50%	(0.60%)
Stock based compensation	(2.50%)	0%
Change in valuation allowance	(28.40%)	(30.90%)
Effective income tax rate	0%	0%

Income Taxes - Schedule of Comp

Income Taxes - Schedule of Components of Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred Tax Assets:
NOL carryforwards	$ 91,036	$ 79,827
Research and development tax credit carryforwards	16,973	15,996
Orphan drug tax credit carryforwards	24,983	22,565
Depreciation and amortization	5,552	6,449
Capitalized research and development expenditures	42,271	41,168
Stock options	4,857	4,506
Accrued expenses and other	973	1,067
Oberland agreement	11,640	13,285
Lease liability	763	1,072
Total gross deferred tax asset	199,048	185,935
Valuation allowance	(198,212)	(184,738)
Net deferred tax asset	836	1,197
Deferred tax liabilities:
Right of use asset	(836)	(1,197)
Total gross deferred tax liabilities	(836)	(1,197)
Net deferred tax assets (liabilities)	$ 0	$ 0

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Income Taxes [Line Items]
Orphan drug tax credit carryforwards	$ 24,983,000	$ 22,565,000
Valuation allowance	198,212,000	184,738,000
Increase (decrease) in valuation allowance	13,500,000	17,300,000
Unrecognized tax benefits	0	0
Uncertain tax position	0
Deferred tax assets, capitalization of section 174 costs	16,900,000	9,800,000
Federal
Income Taxes [Line Items]
Net operating loss	74,800,000
Federal | Research and Experimentation
Income Taxes [Line Items]
Research and experimentation credit carryforwards	12,900,000	12,200,000
Federal | Tax Years 2024 through 2037
Income Taxes [Line Items]
Net operating loss	34,100,000
State
Income Taxes [Line Items]
Net operating loss	16,200,000
State | Research and Experimentation
Income Taxes [Line Items]
Research and experimentation credit carryforwards	$ 4,100,000	$ 3,800,000