Verastem (VSTM) 10-K 14 Mar 24 2023 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2023	Mar. 13, 2024	Jun. 30, 2023
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Transition Report	false
Document Period End Date	Dec. 31, 2023
Entity File Number	001-35403
Entity Registrant Name	Verastem, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	27-3269467
Entity Address, Address Line One	117 Kendrick Street, Suite 500
Entity Address, City or Town	Needham
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02494
City Area Code	781
Local Phone Number	292-4200
Title of 12(b) Security	Common Stock, $0.0001 par value
Trading Symbol	VSTM
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 [Flag]	false
Entity Shell Company	false
Entity Public Float			$ 186,689,509
Entity Common Stock, Shares Outstanding		25,295,495
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Entity Central Index Key	0001526119
Amendment Flag	false
Auditor Name	Ernst & Young LLP
Auditor Firm ID	42
Auditor Location	Boston, Massachusetts

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 77,909	$ 74,933
Short-term investments	59,220	12,961
Accounts receivable, net		31
Prepaid expenses and other current assets	6,553	4,945
Total current assets	143,682	92,870
Property and equipment, net	37	92
Right-of-use asset, net	1,171	1,789
Restricted cash	241	241
Other assets	4,587	58
Total assets	149,718	95,050
Current liabilities:
Accounts payable	7,184	4,901
Accrued expenses	17,928	14,983
Deferred liabilities	327	710
Lease liability, short-term	941	794
Total current liabilities	26,380	21,663
Non-current liabilities:
Long-term debt	40,086	24,526
Lease liability, long-term	530	1,470
Preferred stock tranche liability	4,189
Total liabilities	71,185	47,659
Convertible Preferred Stock:
Convertible preferred stock	21,159
Stockholders' equity:
Preferred stock, value
Common stock, $0.0001 par value; 300,000 shares authorized, 25,281 and 16,712 shares issued and outstanding at December 31, 2023 and December 31, 2022, respectively	3	2
Additional paid-in capital	882,248	784,912
Accumulated other comprehensive income	13
Accumulated deficit	(824,890)	(737,523)
Total stockholders' equity	57,374	47,391
Total liabilities, convertible preferred stock and stockholders' equity	$ 149,718	$ 95,050

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2023	Dec. 31, 2022
Preferred stock, shares authorized	5,000,000
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares issued	25,281,000	16,712,000
Common stock, shares outstanding	25,281,000	16,712,000
Series A Preferred Stock
Preferred stock, par value (in dollars per share)	$ 0.0001
Preferred stock, shares authorized	1,000,000
Preferred stock, shares issued	1,000,000
Preferred stock, shares outstanding	1,000,000
Series B Preferred Stock
Preferred stock, par value (in dollars per share)	$ 0.0001
Preferred stock, shares authorized	2,144,000	0
Preferred stock, shares issued	1,200,000	0
Preferred stock, shares outstanding	1,200,000	0
Preferred Stock [Member]
Preferred stock, par value (in dollars per share)	$ 0.0001
Preferred stock, shares authorized	5,000,000

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Revenue:
Total revenue		$ 2,596	$ 2,053
Operating expenses:
Research and development	$ 61,356	50,558	39,347
Selling, general and administrative	30,728	24,975	24,115
Total operating expenses	92,084	75,533	63,462
Loss from operations	(92,084)	(72,937)	(61,409)
Other income (expense)	(109)	47
Interest income	6,214	1,215	181
Interest expense	(4,139)	(2,137)	(9,972)
Change in fair value of preferred stock tranche liability	2,751
Net loss	$ (87,367)	$ (73,812)	$ (71,200)
Net loss per share-basic	$ (3.96)	$ (4.57)	$ (4.90)
Net loss per share-diluted	$ (3.93)	$ (4.57)	$ (4.90)
Weighted average common shares outstanding used in computing net loss per share - basic	22,054	16,138	14,535
Weighted average common shares outstanding used in computing net loss per share - diluted	22,054	16,138	14,535
Net Income (Loss)	$ (87,367)	$ (73,812)	$ (71,200)
Unrealized gain (loss) on available-for-sale securities	13	(34)	(19)
Comprehensive loss	$ (87,354)	(73,846)	(71,219)
Sale of COPIKTRA license and related assets
Revenue:
Total revenue		$ 2,596	1,447
Transition Services Revenue
Revenue:
Total revenue			$ 606

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Preferred stock Series A Preferred Stock	Preferred stock Series B Preferred Stock	Common stock Series A Preferred Stock	Common stock	Additional paid-in capital Series A Preferred Stock	Additional paid-in capital	Accumulated other comprehensive income/ (loss)	Accumulated deficit	Series A Preferred Stock	Series B Preferred Stock	Total
Balance at Dec. 31, 2020				$ 1		$ 707,731	$ 53	$ (592,511)			$ 115,274
Balance (in shares) at Dec. 31, 2020				14,205,004
Increase (Decrease) in Stockholders' Equity
Net Income (Loss)								(71,200)			(71,200)
Unrealized gain (loss) on available-for-sale marketable securities							(19)				(19)
Issuance of common stock resulting from at-the-market transactions, net						6,796					6,796
Issuance of common stock resulting from at-the-market transactions, net (in shares)				244,209
Issuance of common stock resulting from exercise of stock options						905					905
Issuance of common stock resulting from exercise of stock options (in shares)				49,087
Issuance of common stock resulting from vesting of restricted stock units (in shares)				215,409
Stock-based compensation expense						7,711					7,711
Issuance of common stock under Employee Stock Purchase Plan						182					182
Issuance of common stock under Employee Stock Purchase Plan (in shares)				9,172
Conversion of Notes into common stock				$ 1		27,999					28,000
Conversion of Notes into common stock (in shares)				717,949
Balance at Dec. 31, 2021				$ 2		751,234	34	(663,711)			87,559
Balance (in shares) at Dec. 31, 2021				15,440,830
Increase (Decrease) in Stockholders' Equity
Net Income (Loss)								(73,812)			(73,812)
Unrealized gain (loss) on available-for-sale marketable securities							(34)				(34)
Preferred Stock Issued During Period Stock Stock Exchange	1,000,000			(833,333)
Issuance of common stock resulting from at-the-market transactions, net						27,349					27,349
Issuance of common stock resulting from at-the-market transactions, net (in shares)				1,964,448
Issuance of common stock resulting from exercise of stock options						118					118
Issuance of common stock resulting from exercise of stock options (in shares)				8,181
Issuance of common stock resulting from vesting of restricted stock units (in shares)				121,441
Stock-based compensation expense						6,047					6,047
Issuance of common stock under Employee Stock Purchase Plan						164					164
Issuance of common stock under Employee Stock Purchase Plan (in shares)				10,194
Balance at Dec. 31, 2022				$ 2		784,912		(737,523)			$ 47,391
Balance (in shares) at Dec. 31, 2022				16,711,761							16,712,000
Balance (in shares, preferred) at Dec. 31, 2022	1,000,000									0
Increase (Decrease) in Stockholders' Equity
Net Income (Loss)								(87,367)			$ (87,367)
Unrealized gain (loss) on available-for-sale marketable securities							13				13
Issuance of common stock resulting from vesting of restricted stock units (in shares)				65,710
Stock-based compensation expense						5,860					5,860
Issuance of common stock, and pre-funded warrants, net of issuance cost of $6,351			$ 1		$ 91,419				$ 91,420
Issuance of common stock, and pre-funded warrants, net of issuance cost of $6,351 (in shares)			8,489,409
Issuance of common stock under Employee Stock Purchase Plan						57					57
Issuance of common stock under Employee Stock Purchase Plan (in shares)				14,270
Issuance of Series B Convertible Preferred Stock, net of issuance costs of $1,901 and preferred stock tranche liability of $6,940		$ 21,159
Issuance of Series B Convertible Preferred Stock, net of issuance costs of $1,901 and preferred stock tranche liability of $6,940, in shares		1,200,000
Balance at Dec. 31, 2023		$ 21,159		$ 3		$ 882,248	$ 13	$ (824,890)			$ 57,374
Balance (in shares) at Dec. 31, 2023				25,281,150							25,281,000
Balance (in shares, preferred) at Dec. 31, 2023	1,000,000	1,200,000							1,000,000	1,200,000

CONSOLIDATED STATEMENTS OF ST_2

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($)
Issuance of common stock, issuance costs	$ 6,351
Preferred stock tranche liability	6,940
Series B Preferred Stock
Issuance of stock costs	$ 1,901

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating activities
Net loss	$ (87,367)	$ (73,812)	$ (71,200)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	62	118	206
Amortization of right-of-use asset and lease liability	(175)	(154)	(134)
Stock-based compensation expense	5,860	6,047	7,711
Amortization of deferred financing costs, debt discounts and premiums and discounts on available-for-sale marketable securities	(1,132)	228	9,331
Change in fair value of preferred stock tranche liability	(2,751)
Changes in operating assets and liabilities:
Accounts receivable, net	31	485	(277)
Prepaid expenses, other current assets and other assets	(5,826)	744	(1,558)
Accounts payable	2,283	2,599	623
Accrued expenses and other liabilities	2,938	(638)	1,796
Deferred liabilities	(383)	710
Net cash used in operating activities	(86,460)	(63,673)	(53,502)
Investing activities
Purchases of property and equipment			(196)
Purchases of investments	(96,447)	(17,815)	(86,442)
Maturities of investments	52,000	84,000	86,725
Net cash provided by (used in) investing activities	(44,447)	66,185	87
Financing activities
Proceeds from issuance of Series B Convertible Preferred Stock, net	28,099
Proceeds from long-term debt, net	14,918	24,148
Proceeds from insurance premium financing	1,430
Payments on insurance premium financing	(1,430)
Repayment of 2018 Notes	(300)
Proceeds from the exercise of stock options and employee stock purchase program	57	282	1,087
Settlement of restricted stock for tax withholdings			(925)
Proceeds from the issuance of common stock, net	91,420	27,354	6,723
Net cash provided by financing activities	134,194	51,784	6,885
Increase (decrease) in cash, cash equivalents and restricted cash	3,287	54,296	(46,530)
Cash, cash equivalents and restricted cash at beginning of period	75,789	21,493	68,023
Cash, cash equivalents and restricted cash at end of period	79,076	75,789	21,493
Supplemental disclosure
Cash paid for interest	3,361	$ 1,536	1,007
Supplemental disclosure of non-cash investing and financing activities
Issuance of preferred stock tranche liability	6,940
Conversion of 2020 Notes into common stock			$ 28,000
Purchases of property and equipment including in accounts payable and accrued expenses	$ 7

Nature of business

Nature of business	12 Months Ended
	Dec. 31, 2023
Nature of business
Nature of business	1. Nature of business Verastem, Inc. (the “Company”) is a late-stage development biopharmaceutical company, with an ongoing registration directed trial, committed to advancing new medicines for patients battling cancer. The Company’s pipeline is focused on novel anticancer agents that inhibit critical signaling pathways in cancer that promote cancer cell survival and tumor growth, particularly RAF/MEK inhibition and FAK inhibition. On September 24, 2018, the Company’s first commercial product, COPIKTRA® (duvelisib), was approved by the U.S. Food and Drug Administration (the “FDA”) for the treatment of adult patients with certain hematologic cancers including relapsed or refractory chronic lymphocytic leukemia/ small lymphocytic lymphoma after at least two prior therapies and relapsed or refractory follicular lymphoma after at least two prior systemic therapies. On August 10, 2020, the Company and Secura Bio, Inc. (“Secura”) entered into an asset purchase agreement (“Secura APA”). Pursuant to the Secura APA, the Company sold to Secura its exclusive worldwide license, including certain related assets for the research, development, commercialization, and manufacture in oncology indications of products containing COPIKTRA (duvelisib). The transaction closed on September 30, 2020. Refer to Note 13. License, collaboration and commercial agreements The consolidated financial statements include the accounts of Verastem Securities Company and Verastem Europe GmbH, wholly-owned subsidiaries of the Company. All financial information presented has been consolidated and includes the accounts of the Company and its wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. The Company is subject to the risks associated with other life science companies, including, but not limited to, possible failure of preclinical testing or clinical trials, competitors developing new technological innovations, inability to obtain marketing approval of the Company’s product candidates, avutometinib and defactinib, market acceptance and commercial success of the Company’s product candidates, avutometinib and defactinib, following receipt of regulatory approval, and, protection of proprietary technology and the continued ability to obtain adequate financing to fund the Company’s future operations. If the Company does not obtain marketing approval and successfully commercialize its product candidates, avutometinib and defactinib, following regulatory approval, it will be unable to generate product revenue or achieve profitability and may need to raise additional capital. As of December 31, 2023, the Company had cash, cash equivalents, and investments of $137.1 million. In accordance with applicable accounting standards, the Company evaluated whether 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 12 months after the date of the issuance of these consolidated financial statements. The Company anticipates operating losses may continue for the foreseeable future since the Company does not yet have regulatory approval to sell any of its product candidates, and the Company continues to incur operating costs to execute its strategic plan, including costs related to research and development of its product candidates and commercial readiness activities. These conditions raise substantial doubt about the Company’s ability to continue as a going concern for 12 months after the date the consolidated financial statements are issued. The Company expects to finance its operations with its existing cash, cash equivalents and investments, through potential future milestones and royalties received pursuant to the Secura APA, through the loan and security agreement with Oxford Finance LLC (“Oxford”), or through other strategic financing opportunities that could include, but are not limited to collaboration agreements, future offerings of its equity, or the incurrence of debt. However, given the risk associated with these potential strategic or financing opportunities, they are not deemed probable for purposes of the going concern assessment. If the Company fails to obtain additional future capital, it may be unable to complete its planned preclinical studies and clinical trials and obtain approval of certain investigational product candidates from the FDA or foreign regulatory authorities. Therefore, there is substantial doubt about the Company’s ability to continue as a going concern. Reverse Stock Split On May 30, 2023, the Company filed a Certificate of Amendment to the Company’s Restated Certificate of Incorporation, as amended to date, with the Secretary of State of the State of Delaware to effect a reverse stock split of the Company’s issued and outstanding common stock, par value $0.0001 at a ratio of 1-for-12 (the “Reverse Stock Split”), as authorized at the Company’s 2023 annual meeting of stockholders held on May 15, 2023. The Company effected the Reverse Stock Split on May 31, 2023. No fractional shares were issued in connection with the Reverse Stock Split. Stockholders who otherwise were entitled to a fractional share of common stock were entitled to receive a price equal to the closing price of the common stock on the Nasdaq Capital Market on the date immediately preceding the Reverse Stock Split, as adjusted by the ratio of one share of common stock for every 12 shares of common stock, multiplied by the applicable fraction of a share. The number of shares of common stock that the Company is authorized to issue remains at 300,000,000 shares and the par value of its common stock remains unchanged at $0.0001 per share. The Company has retroactively restated the share and per share amounts in the consolidated financial statements as of December 31, 2022 and the 12 months ended December 31, 2023, 2022 and 2021, to give retroactive effect to the Reverse Stock Split. Proportionate adjustments were made to the per share exercise price and number of shares of common stock issuable under all outstanding stock options, convertible notes and preferred stock. In addition, proportionate adjustments have been made to the number of shares of common stock issuable upon vesting of the restricted stock units and the number of shares of common stock reserved for the Company’s equity incentive compensation plans. The consolidated statements of convertible preferred stock and stockholders’ equity and balance sheets reflect the impact of the Reverse Stock Split by reclassifying from “common stock” to “additional paid-in capital” in an amount equal to the par value of the decreased shares resulting from the Reverse Stock Split.

Summary of significant accounti

Summary of significant accounting policies	12 Months Ended
	Dec. 31, 2023
Summary of significant accounting policies
Summary of significant accounting policies	2. Significant accounting policies Basis of presentation The accompanying financial statements of the Company have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) under the assumption that the Company will continue as a going concern for the next 12 months. Accordingly, they do not include any adjustments that might result from the uncertainty related to the Company’s ability to continue as a going concern. Use of estimates The preparation of the Company’s financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. On an ongoing basis, management evaluates its estimates, including but not limited to estimates related to revenue recognition, accrued and prepaid clinical trial expense and other general accruals, stock-based compensation expense and its preferred stock tranche liability. The Company bases its estimates on historical experience and other market-specific or other relevant assumptions that it believes to be reasonable. Actual results could differ from such estimates. Segment and geographic information Operating segments are defined as components of an enterprise about which separate discrete information is available and regularly reviewed by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company views its operations and manages its business in one operating segment, which is the business of developing and commercializing drugs for the treatment of cancer. All material long-lived assets of the Company reside in the United States. Proceeds from grants In May 2022 the Company was awarded the “Therapeutic Accelerator Award” grant from Pancreatic Cancer Network (“PanCAN”) for up to $3.8 million (the “PanCAN Grant”). In August 2022, PanCAN agreed to provide the Company with an additional $0.5 million for the collection and analysis of patient samples. The grant is supporting a Phase 1b/2 clinical trial of GEMZAR (gemcitabine) and ABRAXANE (Nab-paclitaxel) in combination with avutometinib and defactinib entitled RAMP 205. The RAMP 205 study is evaluating whether combining avutometinib (to target mutant KRAS which is found in more than 90% of pancreatic adenocarcinomas) and defactinib (to reduce stromal density and adaptive resistance to avutometinib) to the standard GEMZAR/ABRAXANE regimen improves outcomes for patients with such pancreatic cancers. Through December 31, 2023, the Company has received $2.7 million of cash proceeds which was initially recorded as deferred liabilities on the balance sheet. The Company recognizes grants as contra research and development expense in the consolidated statement of operations and comprehensive loss on a systematic basis over the periods in which the entity recognizes as expenses the related costs for which the grants are intended to compensate. The Company recorded $2.0 million and $0.3 million of the proceeds as a reduction of research and development expense during the years ended December 31, 2023 and December 31, 2022, respectively. As of December 31, 2023 and December 31, 2022, the Company recorded $0.3 million and $0.7 million, respectively, as deferred liabilities in the consolidated balance sheet related to the PanCAN Grant. Cash, cash equivalents and restricted cash The Company considers all highly liquid investments with an original or remaining maturity of three months or less at the date of purchase to be cash equivalents. Cash equivalents consist of a U.S. Government money market funds and corporate bonds and commercial paper of publicly traded companies. Cash equivalents are reported at fair value. The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the consolidated balance sheets that sum to the total of the same such amounts shown in the consolidated statements of cash flows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2023 December 31, 2022 Cash and cash equivalents ​ $ 77,909 ​ $ 74,933 Restricted cash ​ 1,167 ​ 856 Total cash, cash equivalents and restricted cash ​ $ 79,076 ​ $ 75,789 ​ Fair value of financial instruments The Company determines the fair value of its financial instruments based upon the fair value hierarchy, which prioritizes valuation inputs based on the observable nature of those inputs. The fair value hierarchy applies only to the valuation inputs used in determining the reported fair value of the investments and is not a measure of the investment credit quality. The hierarchy defines three levels of valuation inputs: ​ ​ ​ ​ Level 1 inputs ​ Quoted prices in active markets for identical assets or liabilities that the Company can access at the measurement date. Level 2 inputs ​ Inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly. ​ Level 3 inputs ​ Unobservable inputs that reflect the Company’s own assumptions about the assumptions market participants would use in pricing the asset or liability. ​ ​ Items Measured at Fair Value on a Recurring Basis The following table presents information about the Company’s financial instruments that are measured at fair value on a recurring basis (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2023 Description Total Level 1 Level 2 Level 3 Financial assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents ​ $ 46,093 ​ $ 46,093 ​ $ — ​ $ — ​ Short-term investments ​ ​ 59,220 ​ ​ 5,992 ​ ​ 53,228 ​ ​ — ​ Total financial assets ​ $ 105,313 ​ $ 52,085 ​ $ 53,228 ​ $ — ​ Preferred stock tranche liability ​ $ 4,189 ​ $ — ​ $ — ​ $ 4,189 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 Description ​ Total Level 1 Level 2 Level 3 Financial assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents ​ $ 73,613 ​ $ 72,617 ​ $ 996 ​ $ — ​ Short-term investments ​ 12,961 ​ — ​ ​ 12,961 ​ — ​ Total financial assets ​ $ 86,574 ​ $ 72,617 ​ $ 13,957 ​ $ — ​ ​ A preferred stock tranche liability was recorded as a result of the entry into the Series B Convertible Preferred Stock Securities Purchase Agreement Note 7. Capital Stock) Below are the inputs used to value the preferred stock tranche liability at December 31, 2023 and January 24, 2023: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2023 ​ January 24, 2023 Risk-free interest rate 5.13-5.52 % ​ 4.41-4.84 % Volatility 75 % ​ 90 % Dividend yield — ​ ​ — ​ Remaining term (years) 0.6 ​ ​ 1.5 ​ ​ The following table represents a rollforward for the year ended December 31, 2023 of the preferred stock right liability recorded in connection with the entry into the Series B Convertible Preferred Stock Securities Purchase Agreement (in thousands): ​ ​ ​ ​ ​ January 1, 2023 ​ ​ $ — Fair value recognized upon entering into Securities Purchase Agreement ​ ​ ​ 6,940 Fair value adjustment ​ ​ ​ (2,751) December 31, 2023 ​ ​ $ 4,189 ​ Fair Value of Financial Instruments Note 9. Convertible Senior Notes The fair value of the Company’s long-term debt is determined using a discounted cash flow analysis with current applicable rates for similar instruments as of the consolidated balance sheet date. The carrying value of the Company’s long-term debt as of December 31, 2023 and December 31, 2022, was approximately $40.1 million and $24.5 million, respectively. The Company estimates that the fair value of its long-term debt as of December 31, 2023 and December 31, 2022, was approximately $39.6 million and $24.9 million, respectively. The fair value of the Company’s long-term debt was determined using Level 3 inputs. Investments Investments and cash equivalents consist of investments in a U.S. Government money market funds, overnight repurchase agreements collateralized by government agency securities or U.S. Treasury securities, corporate bonds and commercial paper of publicly traded companies that are classified as available-for-sale pursuant to ASC Topic 320, Investments—Debt and Equity Securities The Company reviews investments for impairment whenever the fair value of a investment is less than the amortized cost and evidence indicates that a investment’s carrying amount is not recoverable. Unrealized losses are evaluated for impairment under ASC 326, Financial Instruments - Credit Losses determined using the specific identification method and are included in interest income in the consolidated statements of operations and comprehensive loss. There were no realized gains or losses on investments for the years ended December 31, 2023, 2022 or 2021. Accrued interest receivable is excluded from the amortized cost and estimated fair value of the Company’s investments. Accrued interest receivable of $0.1 million is presented within prepaid expenses and other current assets on the consolidated balance sheets as of December 31, 2023 and December 31, 2022. There were two debt securities in an unrealized loss position at each of December 31, 2023, and December 31, 2022. None of these investments had been in an unrealized loss position for more than 12 months as of December 31, 2023 and December 31, 2022. The Company considered the decline in the market value for these securities to be primarily attributable to current economic conditions and not credit related. At both December 31, 2023 and December 31, 2022, the Company had the intent and ability to hold such securities until recovery. As a result, the Company did not record any charges for credit-related impairments for its investments as of December 31, 2023 and December 31, 2022. The following is a summary of available-for-sale securities with unrealized losses for less than 12 months as of December 31, 2023 and 2022 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2023 December 31, 2022 ​ ​ ​ Fair ​ Unrealized ​ Fair ​ Unrealized ​ ​ Value Losses Value Losses ​ Corporate bonds, agency bonds and commercial paper (due within 1 year) ​ $ 8,896 ​ $ (1) ​ $ 5,964 ​ $ (2) ​ Total available-for-sale securities in an unrealized loss position ​ $ 8,896 ​ $ (1) ​ $ 5,964 ​ $ (2) ​ ​ Cash, cash equivalents, restricted cash and investments consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2023 ​ ​ ​ Gross Gross ​ ​ ​ ​ Amortized ​ Unrealized ​ Unrealized ​ Fair ​ Cost Gains Losses Value Cash, cash equivalents & restricted cash: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and money market accounts ​ $ 79,076 ​ $ — ​ $ — ​ $ 79,076 ​ Total cash, cash equivalents & restricted cash: ​ $ 79,076 ​ $ — ​ $ — ​ $ 79,076 ​ Investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate bonds, agency bonds and commercial paper (due within 1 year ) ​ ​ 59,208 ​ ​ 13 ​ ​ (1) ​ ​ 59,220 ​ Total investments ​ $ 59,208 ​ $ 13 ​ $ (1) ​ $ 59,220 ​ Total cash, cash equivalents, restricted cash and investments ​ $ 138,284 ​ $ 13 ​ $ (1) ​ $ 138,296 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 ​ ​ ​ ​ Gross Gross ​ ​ ​ ​ Amortized Unrealized Unrealized Fair ​ ​ Cost Gains Losses Value Cash, cash equivalents & restricted cash: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and money market accounts ​ $ 74,794 ​ $ — ​ $ — ​ $ 74,794 ​ Corporate bonds, agency bonds and commercial paper (due within 90 days ) ​ ​ 995 ​ ​ — ​ $ — ​ ​ 995 ​ Total cash, cash equivalents & restricted cash: ​ $ 75,789 ​ $ — ​ $ — ​ $ 75,789 ​ Investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate bonds, agency bonds and commercial paper (due within 1 year ) ​ $ 12,961 ​ $ 2 ​ $ (2) ​ $ 12,961 ​ Total investments ​ $ 12,961 ​ $ 2 ​ $ (2) ​ $ 12,961 ​ Total cash, cash equivalents, restricted cash and investments ​ $ 88,750 ​ $ 2 ​ $ (2) ​ $ 88,750 ​ ​ Concentrations of credit risk and off-balance sheet risk Cash and cash equivalents, investments, and trade accounts receivable are financial instruments that potentially subject the Company to concentrations of credit risk. The Company mitigates this risk by maintaining its cash and cash equivalents and investments with high quality, accredited financial institutions. The management of the Company’s investments is not discretionary on the part of these financial institutions. As of December 31, 2023, the Company’s cash, cash equivalents and investments were deposited at four financial institutions and it has no significant off-balance sheet concentrations of credit risk, such as foreign currency exchange contracts, option contracts or other hedging arrangements. There was no accounts receivable balance as of December 31, 2023. As of December 31, 2022, there was one customer, Secura, that made up more than 60% of the Company’s trade accounts receivable balance. The Company assesses the creditworthiness of all its customers and sets and reassesses customer credit limits to ensure collectability of any trade accounts receivable balances are assured. For the year ended December 31, 2023, the Company did not record any revenue. For the year ended December 31, 2022 one customer, Secura, individually accounted for all of the Company’s total revenue. Refer to Note 13. License, collaboration, and commercial agreements for a detailed discussion of the Secura APA. Property and equipment Property and equipment consist of laboratory equipment, office furniture, computer equipment and leasehold improvements. Expenditures for repairs and maintenance are recorded to expense as incurred, whereas major betterments are capitalized as additions to property and equipment. Depreciation and amortization are calculated using the straight-line method over the following estimated useful lives of the assets: ​ ​ ​ ​ Laboratory equipment 5 years ​ Furniture 5 years ​ Computer equipment 3 years ​ Leasehold improvements Lesser of useful life or life of lease ​ Upon retirement or sale, the cost of the disposed asset and the related accumulated depreciation are removed from the accounts and any resulting gain or loss is recognized. The Company reviews its long-lived assets for impairment whenever events or changes in business circumstances indicate that the carrying value of assets may not be recoverable. Recoverability is measured by comparison of the asset’s book value to future net undiscounted cash flows that the assets are expected to generate. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the book value of the assets exceed their fair value, which is measured based on the projected discounted future net cash flows arising from the assets. No impairment losses have been recorded through December 31, 2023. Research and development costs The Company expenses research and development costs to operations as incurred. Research and development expenses consist of: ● employee-related expenses, including salaries, benefits, travel and stock-based compensation expense; ● external research and development expenses incurred under arrangements with third parties, such as clinical research organizations (“CROs”), clinical trial sites, manufacturing organizations and consultants, including the scientific advisory board; ● license fees; ● facilities, depreciation and other expenses, which include direct and allocated expenses for rent and maintenance of facilities, and laboratory supplies; and Stock-based compensation For service-based equity awards, the Company recognizes stock-based compensation expense for stock options, and restricted stock units (“RSUs”) issued to employees, directors, and consultants based on the grant date fair value of the awards on a straight-line basis over the requisite service period, which typically is the vest period. The Company recognized stock-based compensation for shares issued to employees under the Company’s employee stock purchase plan (“ESPP”) plan. The Company has granted performance-based RSUs and stock options with terms that allow the recipients to vest in a specific number of shares based upon the achievement of performance-based milestones as specified in the grants. Stock-based compensation expense associated with these performance-based RSUs and stock options is recognized if the performance condition is considered probable of achievement using the Company’s best estimates of the time to vesting for the achievement of the performance-based milestones. The grant date fair value of stock options is estimated using the Black-Scholes option pricing model that takes into account the fair value of its common stock, the exercise price, the expected life of the option, the expected volatility of its common stock, expected dividends on its common stock, and the risk-free interest rate over the expected life of the option. The Company applies the simplified method described in the Securities and Exchange Commission (“SEC”) Staff Accounting Bulletin (“SAB”) Topic 14.D.2 to calculate the expected term as it does not have sufficient historical exercise data to provide a reasonable basis upon which to estimate the expected term for options granted to employees. The expected term is applied to the stock option grant group as a whole, as the Company does not expect substantially different exercise or post-vesting termination behavior among its population. The Company has not paid and do not anticipate paying cash dividends on the Company’s shares of common stock; therefore, the expected dividend yield is assumed to be zero. The computation of expected volatility is based on the historical volatility of the Company’s common stock. The risk-free interest rate is based on a treasury instrument whose term is consistent with the expected term of the stock options. The Company accounts for forfeitures as they occur. The Company issues shares under the Company’s ESPP to employees. Stock-based compensation expense for discounted purchases under the ESPP is measured using the Black-Scholes model to compute the fair value of the lookback provision plus the purchase discount and is recognized as compensation expense over the offering period Leases At the inception of an arrangement, the Company determines whether the arrangement is or contains a lease based on the unique facts and circumstances within the arrangement. A lease is identified where an arrangement conveys the right to control the use of identified property, plant, and equipment for a period of time in exchange for consideration. Leases which are identified within the scope of ASC 842 and which have a term greater than one year are recognized on the Company’s consolidated balance sheets as right-of-use assets, lease liabilities and, if applicable, long-term lease liabilities. The Company has elected not to recognize leases with terms of one year or less on its consolidated balance sheets. Operating lease liabilities and their corresponding right-of-use assets are recorded based on the present value of lease payments over the expected remaining lease term. However, certain adjustments to the right-of-use asset may be required for items such as initial direct costs paid or incentives received. The interest rate implicit in lease contracts is typically not readily determinable. As a result, the Company utilizes its incremental borrowing rates to calculate the present value of lease payments. Incremental borrowing rates are the rates the Company incurs to borrow on a collateralized basis over a similar term an amount equal to the lease payments in a similar economic environment. In accordance with ASC 842, components of a lease are split into three categories: lease components (e.g., land, building, etc.), non-lease components (e.g., common area maintenance, maintenance, consumables, etc.), and non-components (e.g., property taxes, insurance, etc.). The fixed and in-substance fixed contract consideration (including any related to non-components) must be allocated based on fair values to the lease components and non-lease components. Although separation of lease and non-lease components is required, certain practical expedients are available. Entities may elect the practical expedient to not separate lease and non-lease components. Rather, they would account for each lease component and the related non-lease component together as a single component. The Company has elected to account for the lease and non-lease components of each of its operating leases as a single lease component and allocate all of the contract consideration to the lease component only. The lease component results in an operating right-of-use asset being recorded on the consolidated balance sheets and amortized on a straight-line basis as lease expense. Revenue recognition Revenue from Contracts with Customers Sales of intellectual property For sales of license and intellectual property, that include sale-based royalties, including milestone payments based on a level of sales, the Company evaluates whether the royalties and sales-based milestones are considered probable of being achieved and estimates the amount of royalties to include over the contractual term using the expected value method and estimates the sales-based milestones using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the associated royalty and milestone value is included in the transaction price. Royalties and sales-based milestones for territories for which there is not regulatory approval are not considered probable until such regulatory approval is achieved. The Company evaluates factors such as whether consideration is outside of the Company’s control, timeline for when the uncertainty will be resolved and historical sales of COPIKTRA if applicable. There is considerable judgment involved in determining whether it is probable that a significant revenue reversal would not occur. At the end of each subsequent reporting period, the Company reevaluates the probability of achievement of all milestones subject to constraint and amount of royalty revenue to be received and, if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect revenues and earnings in the period of adjustment. Collaborative arrangements Collaborative Arrangements: Contracts are considered to be collaborative arrangements when they satisfy the following criteria defined in ASC Topic 808, Collaborative Arrangements possibility of significant risk and rewards, based on whether or not the activity is successful. Payments received from or made to a partner that are the result of a collaborative relationship with a partner, instead of a customer relationship, such as co-development activities, are recorded as a reduction or increase to research and development expense, respectively. Accounts receivable, net Accounts receivable, net consists of amounts due from customers, net of applicable revenue reserves. Accounts receivable have standard payments that generally require payment within 30 to 90 days . The Company analyzes accounts that are past due for collectability and provides an allowance for receivables when collection becomes doubtful. Income taxes The Company accounts for income taxes under the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases using enacted tax rates in effect for the year in which the differences are expected to affect taxable income. Tax benefits are recognized when it is more likely than not that a tax position will be sustained during an audit. Deferred tax assets are reduced by a valuation allowance if current evidence indicates that it is considered more likely than not that these benefits will not be realized. The Company recognizes the tax effects of an uncertain tax position only if it is more likely than not that it will be sustained based solely on its technical merits as of the reporting date and only in an amount more likely than not that it will be sustained upon review by the tax authorities. The Company evaluates uncertain tax positions on a quarterly basis and adjust the liability for changes in facts and circumstances, such as new regulations or interpretations by the taxing authorities, new information obtained during a tax examination, significant amendment to an existing tax law, or resolution of an examination. To the extent that the final tax outcome of these matters is different than the amounts recorded, such differences will impact the income tax provision in the period in which such determination is made. The resolution of its uncertain income tax positions is dependent on uncontrollable factors such as law changes, new case law, and the willingness of the income tax authorities to settle, including the timing thereof and other factors. Although the Company does not anticipate significant changes to its uncertain income tax positions in the next 12 months, items outside of its control could cause its uncertain income tax positions to change in the future, which would be recorded in its statements of operations. Interest and/or penalties related to income tax matters are recognized as a component of income tax expense. Net operating loss (“NOL”) and tax credit carryforwards are subject to review and possible adjustment by the Internal Revenue Service and state tax authorities and may become subject to an annual limitation in the event of certain cumulative changes in the ownership interest of significant stockholders over a three-year period in excess of 50%, as defined under Sections 382 and 383 of the Internal Revenue Code, as well as similar state provisions. This could limit the amount of tax attributes that can be utilized annually to offset future taxable income or tax liabilities. The amount of the annual limitation is determined based on the value of the Company immediately prior to the ownership change. Subsequent ownership changes may further affect the limitation in future years. The Company experienced a greater than 50% change in ownership as defined under Section 382 and 383 of the Internal Revenue Code as well as similar state provisions during the year ended December 31, 2020. For more details please refer to Note 11. Income Taxes. ​ Net loss per share Basic net loss per common share is calculated by dividing net loss applicable to common stockholders by the weighted-average number of common shares outstanding during the period. Weighted-average number of common shares outstanding includes the weighted average effect of the pre-funded warrants issued in June 2023, as the exercise of which requires little or no consideration for the delivery of shares of common stock. Diluted net loss per common share is calculated by increasing the denominator by the weighted-average number of additional shares that could have been outstanding from securities convertible into common stock, such as stock options, restricted stock units, and ESPP (using the “treasury stock” method), the Notes (defined herein) , Series A Convertible Preferred Stock, and Series B Convertible Preferred Stock (using the “if-converted” method), unless their effect on net loss per share is antidilutive. Under the “if-converted” method, convertible instruments that are-in-the-money, are assumed to have been converted as of the beginning of the period or when issued, if later. Additionally, the effects of any interest expense and changes in fair value of any bifurcated derivatives shall be added back to the numerator of the diluted net loss per share calculation. Refer to Note 10. Net Loss per share Recently Adopted Accounting Standards Updates In June 2016, the Financial Accounting Standards Board (the “FASB”) issued Accounting Standard Update (“ASU”) No. 2016-13, Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”). ASU 2016-13 replaces the incurred loss impairment methodology under current GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. Effective January 1, 2023, the Company adopted the provisions of ASU 2016-13. The adoption did not have a material impact on the Company's consolidated financial statements or related financial statement disclosures. In August 2020, the FASB issued No. ASU 2020-06, Debt – Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging – Contracts in Entity’s Own Equity (Subtopic 815 – 40) (“ASU 2020-06”). ASU 2020-06 simplifies the complexity associated with applying U.S. GAAP for certain financial instruments with characteristics of liabilities and equity. More specifically, the amendments focus on the guidance for convertible instruments and derivative scope exception for contracts in an entity’s own equity. The ASU also simplifies the diluted earnings per share calculation in certain areas. The Company elected to adopt this standard on January 1, 2023 under the modified retrospective transition method. The adoption did not have a material impact on the Company's consolidated financial statements or related financial statement disclosures. In September 2022, the FASB issued ASU 2022-04, Liabilities—Supplier Finance Programs (Subtopic 405-50): Disclosure of Supplier Finance Program Obligations (“ASU 2022-04”). ASU 2022-04 requires the buyer in a supplier finance program to disclose information about the key terms of the program, outstanding confirmed amounts as of the end of the period, a rollforward of such amounts during each annual period, and a description of where in the financial statements outstanding amounts are presented. This guidance is effective for fiscal years beginning after December 15, 2022. We adopted this guidance as of January 1, 2023, on a prospective basis. The adoption of the standard only resulted in new disclosures and did not affect the Company’s recognition, measurement, or financial statement presentation of supplier finance program obligations on the consolidated financial statements. For additional information on the new disclosures, see Note 14. Notes Payable . Recently issued accounting standards updates In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures (“ASU 2023-07”), which is intended to improve reportable segment disclosure requirements, primarily through enhanced disclosures about significant segment expenses and by extending the disclosure requirements to entities with a single reportable segment. The guidance is effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024. Early adoption is permitted. ASU 2023-07 is to be applied retrospectively to all prior periods presented in the financial statements. We are currently evaluating the potential impact of adopting this new guidance on our consolidated financial statements and related disclosures. In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures (“ASU 2023-09”). The guidance in ASU 2023-09 improves the transparency of income tax disclosures by greater disaggregation of information in the rate reconciliation and income taxes paid disaggregated by jurisdiction. The standard is effective for public companies for fiscal years beginning after December 15, 2024, with early adoption permitted. The Company is currently evaluating the impact that the adoption of ASU 2023-09 may have on its consolidated financial statements. Other recent accounting pronouncements issued, but not yet effective, are not expected to be applicable to the Company or have a material effect on the consolidated financial statements upon future adoption.

Property and equipment, net

Property and equipment, net	12 Months Ended
	Dec. 31, 2023
Property and equipment, net
Property and equipment, net	3. Property and equipment, net Property and equipment and related accumulated depreciation are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, December 31, ​ ​ 2023 ​ 2022 Leasehold improvements ​ $ 146 ​ $ 146 ​ Furniture and fixtures ​ 811 ​ 811 ​ Computer equipment ​ 665 ​ 665 ​ Assets not yet placed in service ​ 7 ​ — ​ ​ ​ 1,629 ​ 1,622 ​ Less: accumulated depreciation ​ (1,592) ​ (1,530) ​ Total property and equipment, net ​ $ 37 ​ $ 92 ​ ​ The Company recorded approximately $0.1 million, $0.1 million, and $0.2 million in depreciation expense for the years ended December 31, 2023, 2022, and 2021, respectively .

Accrued expenses

Accrued expenses	12 Months Ended
	Dec. 31, 2023
Accrued expenses
Accrued expenses	4. Accrued expenses Accrued expenses consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2023 December 31, 2022 ​ ​ ​ ​ ​ ​ ​ ​ Accrued clinical trial expenses ​ $ 6,518 ​ $ 4,281 ​ Accrued contract manufacturing expenses ​ ​ 2,010 ​ ​ 3,258 ​ Accrued other research and development expenses ​ ​ 1,043 ​ ​ 996 ​ Accrued compensation and related benefits ​ 4,796 ​ 3,844 ​ Accrued professional fees ​ 637 ​ 469 ​ Accrued consulting fees ​ 1,078 ​ 902 ​ Accrued interest ​ ​ 316 ​ ​ 192 ​ Accrued commercialization costs ​ 453 ​ 148 ​ Accrued other ​ 1,077 ​ 893 ​ Total accrued expenses ​ $ 17,928 ​ $ 14,983 ​ ​

Long-term debt

Long-term debt	12 Months Ended
	Dec. 31, 2023
Long-term debt
Debt	5. Long-term debt Oxford On March 25, 2022 (the “Closing Date”), the Company entered into a loan and security agreement (the “Loan Agreement”) with Oxford, as collateral agent and a lender, and Oxford Finance Credit Fund III LP, as a lender (“OFCF III” and together with Oxford, the “Lenders”), pursuant to which the Lenders have agreed to lend the Company up to an aggregate principal amount of $150.0 million in a series of term loans (the “Term Loans”). On January 4, 2024, the Company amended the Loan Agreement to extend the date by which it may draw down the Term C Loan from March 31, 2024 to March 31, 2025. Pursuant to the Loan Agreement, as amended, the Company received an initial Term Loan of $25.0 million on the Closing Date, and drew down the second term loan of $15.0 million (the “Term B Loan”) on March 22, 2023 and may borrow an additional $110.0 million of Term Loans at its option upon the satisfaction of certain conditions as follows: i. $25.0 million (the “Term C Loan”), when the Company has received accelerated or full approval from the FDA of avutometinib for the treatment of LGSOC (the “Term C Milestone”). The Company may draw the Term C Loan within 60 days after the occurrence the Term C Milestone, but no later than March 31, 2025. ii. $35.0 million (the “Term D Loan”), when the Company has achieved at least $50.0 million in gross product revenue calculated on a trailing six-month basis (the “Term D Milestone”). The Company may draw the Term D Loan within 30 days after the occurrence of the Term D Milestone, but no later than March 31, 2025. iii. $50.0 million (the “Term E Loan”), at the sole discretion of the Lenders. The Term Loans bear interest at a floating rate equal to (a) the greater of (i) the one-month CME Secured Overnight Financing Rate and (ii) 0.13% plus (b) 7.37% , which is subject to an overall floor and cap. Interest is payable monthly in arrears on the first calendar day of each calendar month. As a result of the Term B Loan drawdown, beginning (i) April 1, 2025, or (ii) April 1, 2026, if either (A) avutometinib has received FDA approval for the treatment of LGSOC or (B) COPIKTRA has received FDA approval for the treatment of PTCL, the Company shall repay the Term Loans in consecutive equal monthly payments of principal, together with applicable interest, in arrears. All unpaid principal and accrued and unpaid interest with respect to each Term Loan is due and payable in full on March 1, 2027. The Company is required to make a final payment of 5.0% of the original principal amount of the Term Loans that are drawn, payable at maturity or upon any earlier acceleration or prepayment of the Term Loans (the “Final Payment Fee”). The Company may prepay all, but not less than all, of the Term Loans, subject to a prepayment fee equal to (i) 3.0% of the principal amount of the applicable Term Loan if prepaid on or before the first anniversary date of the funding date of such Term Loan, (ii) 2.0% of the principal amount of the applicable Term Loan if prepaid after the first anniversary and on or before the second anniversary of the funding date of such Term Loan, and (iii) 1.0% of the principal amount of the applicable Term Loan if prepaid after the second anniversary of the applicable funding date of such Term Loan. All Term Loans are subject to a facility fee of 0.5% of the principal amount. The Loan Agreement contains no financial covenants. The Loan Agreement includes customary events of default, including, among others, payment defaults, breach of representations and warrants, covenant defaults, judgment defaults, insolvency and bankruptcy defaults, and a material adverse change. The occurrence of an event of default could result in the acceleration of the obligations under the Loan Agreement, termination of the Term Loan commitments and the right to foreclose on the collateral securing the obligations. During the existence of an event of default, the Term Loans will accrue interest at a rate per annum equal to 5.0% above the otherwise applicable interest rate. In connection with the Loan Agreement, the Company granted Oxford a security interest in all of the Company’s personal property now owned or hereafter acquired, excluding intellectual property (but including the right to payments and proceeds of intellectual property), and a negative pledge on intellectual property. The Company assessed all terms and features of the Loan Agreement in order to identify any potential embedded features that would require bifurcation. As part of this analysis, the Company assessed the economic characteristics and risks of the Loan Agreement, including put and call features. The Company determined that all features of the Loan Agreement were clearly and closely associated with a debt host and did not require bifurcation as a derivative liability, or the fair value of the feature was immaterial to the Company's financial statements. The Company reassesses the features on a quarterly basis to determine if they require separate accounting. There have been no changes to the Company assessment through December 31, 2023. The debt issuance costs and the Final Payment Fee have been recorded as a debt discount which are being accreted to interest expense through the maturity date of the Term Loan using the effective interest method. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2023 December 31, 2022 Principal loan balance ​ $ 40,000 ​ $ 25,000 Final Payment Fee ​ ​ 661 ​ ​ 225 Debt issuance costs, net of accretion ​ ​ (575) ​ ​ (699) Long-term debt, net of discount ​ $ 40,086 ​ $ 24,526 ​ The following table sets forth total interest expense for the years ended December 31, 2023, 2022, and 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, ​ ​ 2023 ​ 2022 ​ 2021 Contractual Interest ​ $ 3,472 ​ $ 1,733 ​ $ 773 Amortization of debt discount and issuance costs ​ ​ 230 ​ ​ 179 ​ ​ 9,199 Amortization of Final Payment Fee ​ ​ 437 ​ ​ 225 ​ ​ — Total ​ $ 4,139 ​ $ 2,137 ​ $ 9,972 As of December 31, 2023, future principal payments due are as follows (in thousands): ​ ​ ​ ​ ​ 2024 ​ ​ — 2025 ​ ​ 15,000 2026 ​ ​ 20,000 2027 ​ ​ 5,000 Total principal payments ​ $ 40,000 ​

Leases

Leases	12 Months Ended
	Dec. 31, 2023
Leases
Leases	6. Leases On April 15, 2014, the Company entered into a lease agreement for approximately 15,197 square feet of office and laboratory space in Needham, Massachusetts. The lease term commenced on April 15, 2014 and it was scheduled to expire on September 30, 2019. Effective February 15, 2018, the Company amended its lease agreement to relocate within the facility to another location consisting of 27,810 square feet of office space (the Amended Lease Agreement). The Amended Lease Agreement extends the expiration date of the lease from September 2019 through June 2025. Pursuant to the Amended Lease Agreement, the initial annual base rent amount is approximately $0.7 million, which increases during the lease term to $1.1 million for the last 12-month period. The Company has accounted for its Needham, Massachusetts office space as an operating lease. The Company’s lease contains an option to renew and extend the lease terms and an option to terminate the lease prior to the expiration date. The Company has not included the lease extension or the termination options within the right-of-use asset and lease liability on the consolidated balance sheets as neither option is reasonably certain to be exercised. The Company’s lease includes variable non-lease components (e.g., common area maintenance, maintenance, consumables, etc.) that are not included in the right-of-use asset and lease liability and are reflected as an expense in the period incurred. The Company does not have any other operating or finance leases. In calculating the present value of future lease payments, the Company has elected to utilize its incremental borrowing rate based on the remaining lease term at the date of adoption of ASC 842. The Company has elected to account for lease components and associated non-lease components as a single lease component and has allocated all of the contract consideration to the lease components only. This will potentially result in the initial and subsequent measurement of the balances of the right-of-use asset and lease liability for leases being greater than if the policy election was not applied. As of December 31, 2023, a right-of-use asset of $1.2 million and lease liability of $1.5 million are reflected on the consolidated balance sheets. The elements of lease expense were as follows (dollar amounts in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, ​ ​ 2023 ​ 2022 ​ ​ 2021 Lease Expense ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating lease expense ​ $ 885 ​ $ 885 ​ $ 885 Total Lease Expense ​ $ 885 ​ $ 885 ​ $ 885 Other Information - Operating Leases ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating cash flows paid for amounts included in measurement of lease liabilities ​ $ 1,060 ​ $ 1,039 ​ $ 1,019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2023 Other Balance Sheet Information - Operating Leases ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average remaining lease term (in years) ​ ​ ​ ​ ​ ​ ​ ​ 1.5 Weighted average discount rate ​ ​ ​ ​ ​ ​ ​ ​ 14.6% Maturity Analysis ​ ​ ​ ​ ​ ​ ​ ​ ​ 2024 ​ ​ ​ ​ ​ ​ ​ ​ 1,081 2025 ​ ​ ​ ​ ​ ​ ​ ​ 546 Total ​ ​ ​ ​ $ ​ ​ ​ 1,627 Less: Present value discount ​ ​ ​ ​ ​ ​ ​ ​ (156) Lease Liability ​ ​ ​ ​ $ ​ ​ ​ 1,471 ​

Capital stock

Capital stock	12 Months Ended
	Dec. 31, 2023
Capital stock
Capital stock	7. Capital Stock Under the amended and restated certificate of incorporation, the Company’s board of directors has the authority, without further action by the stockholders, to issue up to 5,000,000 shares of preferred stock in one or more series, to establish from time to time the number of shares to be included in each such series, to fix the rights, preferences and privileges of the shares of each wholly unissued series and any qualifications, limitations or restrictions thereon and to increase or decrease the number of shares of any such series, but not below the number of shares of such series then outstanding. As of December 31, 2023 and 2022, the Company had reserved the following shares of common stock for the issuance of common stock for vested restricted stock units, the exercise of stock options, employee stock purchase plan, 2018 Notes, Series A Convertible Preferred Stock conversions to shares of common stock, the issuance and conversion of Series B Convertible Preferred Stock, and exercise of Pre-Funded Warrants (in thousands): ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ 2023 ​ 2022 Shares reserved under equity compensation plans 2,845 2,895 ​ Shares reserved for inducement grants ​ 810 ​ 327 ​ Shares reserved for 2018 Notes ​ — ​ 3 ​ Shares reserved for ESPP ​ 75 ​ 89 ​ Shares reserved for Series A Convertible Preferred Stock ​ 833 ​ 833 ​ Shares reserved for Series B Convertible Preferred Stock ​ 7,570 ​ — ​ Shares reserved for Pre-Funded Warrants ​ 1,539 ​ — ​ Total shares reserved 13,672 4,147 ​ ​ Each share of common stock is entitled to one vote. The holders of the common stock are also entitled to receive dividends whenever funds are legally available and when declared by the board of directors. ​ June 2023 Public Offering On June 15, 2023, the Company entered into an underwriting agreement (the “Underwriting Agreement”) with RBC Capital Markets, LLC and Cantor Fitzgerald & Co. (“Cantor”), as representatives of several underwriters (the “Underwriters”) to offer 7,181,409 shares of the Company’s common stock, at a price to the public of $9.75 per share, less the underwriting discounts and commissions, and, in lieu of shares of common stock to certain investors, pre-funded warrants to purchase up to an aggregate of 1,538,591 shares of common stock at a price to the public of $9.749 (the “Pre-Funded Warrants”) per Pre-Funded Warrant, which represents the per share public offering price for the shares of common stock less the $0.001 per share exercise price for each such Pre-Funded Warrant (the “June 2023 Offering”). In addition, the Company granted the Underwriters an option to purchase, at the public offering price less any underwriting discounts and commissions, an additional 1,308,000 shares of common stock, exercisable for 30 days from the date of the Underwriting Agreement, which the Underwriters exercised in full on June 16, 2023. The June 2023 Offering closed on June 21, 2023. The Company may not effect the exercise of any Pre-Funded Warrant, and a holder will not be entitled to exercise any portion of any Pre-Funded Warrant if, upon giving effect to such exercise, the aggregate number of shares of common stock beneficially owned by the holder (together with its affiliates) would exceed 9.99% of the number of shares of common stock outstanding immediately after giving effect to the exercise, which percentage may be increased or decreased at the holder’s election upon 61 days ’ notice to the Company subject to the terms of such Pre-Funded Warrants, provided that such percentage may in no event exceed 19.99% . Each Pre-Funded Warrant has an exercise price equal to $0.001 per share of common stock. The exercise price and the number of shares of common stock issuable upon exercise of each Pre-Funded Warrant is subject to appropriate adjustment in the event of certain stock dividends and distributions, stock splits, stock combinations, reclassifications or similar events affecting the Company’s common stock as well as upon any distribution of assets, including cash, stock or other property, to the Company’s stockholders. The Pre-Funded Warrants are exercisable as of June 21, 2023, do not expire and are exercisable in cash or by means of a cashless exercise. In addition, upon the consummation of an acquisition (as described in the Pre-Funded Warrant agreements), each Pre-Funded Warrant will automatically be converted into the right of the holder of such Pre-Funded Warrant to receive the kind and amount of securities, cash or other property that such holders would have received had they exercised such Pre-Funded Warrant immediately prior to such acquisition, without regard to any limitations on exercise contained in the Pre-Funded Warrants The Pre-Funded Warrants cannot require cash settlement, are freestanding financial instruments that are legally detachable and separately exercisable from the shares of common stock with which they were issued, are immediately exercisable, and do not embody an obligation for the Company to repurchase its common stock shares and permit the holders to receive a fixed number of shares of common stock upon exercise. Additionally, the Pre-Funded Warrants do not provide any guarantee of value or return. Accordingly, the Pre-Funded Warrants are classified as a component of permanent equity. After deducting for commissions and other offering expenses, the Company received net proceeds of approximately $91.4 million from the sale of 8,489,409 shares of common stock and 1,538,591 Pre-Funded Warrants. Series B Convertible Preferred Stock On January 24, 2023, the Company entered into a Securities Purchase Agreement (the “Series B Convertible Preferred Stock Securities Purchase Agreement”) with certain purchasers pursuant to which the Company agreed to sell and issue to the purchasers in a private placement (the “Private Placement”) up to 2,144,160 shares of its Series B convertible preferred stock, par value $0.0001 per share (the “Series B Convertible Preferred Stock”), in two tranches. On January 24, 2023, the Company filed the Certificate of Designation of the Preferences, Rights and Limitations of the Series B Convertible Preferred Stock (the “Series B Convertible Preferred Stock Certificate of Designation”) setting forth the preferences, rights and limitations of the Series B Convertible Preferred Stock with the Secretary of State of the State of Delaware. The Series B Convertible Preferred Stock Certificate of Designation became effective upon filing. Each share of the Series B Convertible Preferred Shares is convertible into 3.5305 shares of the Company’s common stock, such conversion rate reflects an adjustment to account for the Reverse Stock Split, at the option of the holders at any time, subject to certain limitations, including that the holder will be prohibited from converting Series B Convertible Preferred Stock into common stock if, as a result of such conversion, the holder, together with its affiliates, would beneficially own a number of shares of common stock above a conversion blocker, which is initially set at 9.99% (the “Conversion Blocker”) of the total common stock then issued and outstanding immediately following the conversion of such shares of Series B Convertible Preferred Stock. Holders of the Series B Convertible Preferred Stock are permitted to increase the Conversion Blocker to an amount not to exceed 19.99% upon 60 days ’ notice. The Company agreed to sell and issue in the first tranche of the Private Placement 1,200,000 shares of Series B Convertible Preferred Stock at a purchase price of $25.00 per share of Series B Convertible Preferred Stock (equivalent to $7.0812 per share of common stock on a post-Reverse Stock Split basis). The first tranche of the Private Placement closed on January 27, 2023. The Company received gross proceeds from the first tranche of the Private Placement of approximately $30.0 million, before deducting fees to the placement agent and other offering expenses payable by the Company (“Series B Convertible Preferred Stock Proceeds”). In addition, the Company agreed to sell and issue in the second tranche of the Private Placement 944,160 shares of Series B Convertible Preferred Stock at a purchase price of $31.77 per share of Series B Convertible Preferred Stock (equivalent to $9.00 per share of common stock on a post-Reverse Stock Split basis) if at any time within 18 months following the closing of the first tranche the 10-day volume weighted average price of the Company’s common stock (as quoted on Nasdaq and as calculated by Bloomberg) should reach at least $13.50 per share, such threshold reflects an adjustment to account for the Reverse Stock Split (which may be further adjusted for any reorganization, recapitalization, non-cash dividend, stock split, reverse stock split or other similar transaction as needed) with aggregate trading volume during the same 10-day period of at least $25 million (the “Second Tranche Right”). The second tranche of the Private Placement is expected to close within seven trading days of meeting the second tranche conditions and will be subject to additional, customary closing conditions. If the Second Tranche Right conditions are satisfied, the Company anticipates receiving gross proceeds from the second tranche of the Private Placement of approximately $30.0 million, before deducting fees to the placement agent and other offering expenses payable by the Company. The Series B Convertible Preferred Stock ranks (i) senior to the common stock; (ii) senior to all other classes and series of equity securities of the Company that by their terms do not rank senior to the Series B Convertible Preferred Stock; (iii) senior to all shares of the Company’s Series A Convertible Preferred Stock the equity securities described in (i)-(iii), the “Junior Stock”); (iv) on parity with any class or series of capital stock of the Company hereafter created specifically ranking by its terms on parity with the Series B Convertible Preferred Stock (the “Parity Stock”); (v) junior to any class or series of capital stock of the Company hereafter created specifically ranking by its terms senior to any Series B Convertible Preferred Stock (“Senior Stock”); and (vi) junior to all of the Company’s existing and future debt obligations, including convertible or exchangeable debt securities, in each case, as to distributions of assets upon liquidation, dissolution or winding up of the Company, whether voluntarily or involuntarily and as to the right to receive dividends. In the event of the liquidation, dissolution or winding up of the affairs of the Company, whether voluntary or involuntary, after payment or provision for payment of the debts and other liabilities of the Company, and subject to the prior and superior rights of any Senior Stock, each holder of shares of Series B Convertible Preferred Stock will be entitled to receive, in preference to any distributions of any of the assets or surplus funds of the Company to the holders of the common stock and any of the Company’s securities that are Junior Stock and pari passu with any distribution to the holders of any Parity Stock, an amount equal to $1.00 per share of Series B Convertible Preferred Stock, plus an additional amount equal to any dividends declared but unpaid on such shares, before any payments shall be made or any assets distributed to holders of the common stock or any of our securities that Junior Stock. So long as any shares of the Series B Convertible Preferred Stock remain outstanding, the Company cannot without the affirmative vote or consent of the holders of majority of the shares of the Series B Convertible Preferred Stock then-outstanding, in which the holders of the Series B Convertible Preferred Stock vote separately as a class: (a) amend, alter, modify or repeal (whether by merger, consolidation or otherwise) the Series B Convertible Preferred Stock Certificate of Designation, the Company’s certificate of incorporation, or the Company’s bylaws in any manner that adversely affects the rights, preferences, privileges or the restrictions provided for the benefit of, the Series B Convertible Preferred Stock; (b) issue further shares of Series B Convertible Preferred Stock or increase or decrease (other than by conversion) the number of authorized shares of Series B Convertible Preferred Stock; (c) authorize or issue any Senior Stock; or (d) enter into any agreement to do any of the foregoing that is not expressly made conditional on obtaining the affirmative vote or written consent of the majority of then-outstanding Series B Convertible Preferred Stock. Holders of Series B Convertible Preferred Stock are entitled to receive when, as and if dividends are declared and paid on the common stock, an equivalent dividend, calculated on an as-converted basis. Shares of Series B Convertible Preferred Stock are otherwise not entitled to dividends. The Company classified the first tranche of the Series B Convertible Preferred Stock as temporary equity in the consolidated balance sheets as the Company could be required to redeem the Series B Convertible Preferred Stock if the Company cannot convert the Series B Convertible Preferred Stock into shares of common stock for any reason including due to any applicable laws or by the rules or regulations of any stock exchange, interdealer quotation system, or other self-regulatory organization with jurisdiction over the Company which is not solely in the control of the Company. If the Company were required to redeem the Series B Convertible Preferred Stock, it would be based upon the volume-weighted-average price of common stock on an as converted basis on the date the holders provided a conversion notice to the Company. As of December 31, 2023, the Company did not adjust the carrying value of the Series B Convertible Preferred Stock since it was not probable the holders would be unable to convert the Series B Convertible Preferred Stock into shares of common stock due to any reason including due to any applicable laws or by the rules or regulations of any stock exchange, interdealer quotation system, or other self-regulatory organization with jurisdiction over the Company. The Company evaluated the Second Tranche Right under ASC 480, Distinguishing Liabilities from Equity The Company determined that all other features of the securities offered pursuant to the Series B Convertible Preferred Stock Securities Purchase Agreement were clearly and closely associated with the equity host and did not require bifurcation or the fair value of the feature was immaterial to the Company's consolidated financial statements. The Company reassesses the features on a quarterly basis to determine if they require separate accounting. There have been no changes to the Company’s original assessment through December 31, 2023. Series A Convertible Preferred Stock On November 4, 2022, the Company e ntered into an exchange agreement (the “Exchange Agreement”) with Biotechnology Value Fund, L.P., Biotechnology Value Fund II, L.P., Biotechnology Value Trading Fund OS LP and MSI BVF SPV, LLC (collectively referred to as “BVF”), pursuant to which BVF exchanged 833,333 shares of the Company’s common stock (as adjusted to account for the Reverse Stock Split) for 1,000,000 shares of newly designated Series A convertible preferred stock, par value $0.0001 per share (the “Series A Convertible Preferred Stock”) (the “Exchange”). Each share of the Series A Convertible Preferred Stock is convertible into 0.833 shares of the Company’s common stock (as adjusted to account for the Reverse Stock Split) at the option of the holder at any time, subject to certain limitations, including that the holder will be prohibited from converting Preferred Stock into common stock if, as a result of such conversion, the holder, together with its affiliates, would beneficially own a number of shares of common stock above the Conversion Blocker, initially set at 9.99% , of the total common stock then issued and outstanding immediately following the conversion of such shares of Preferred Stock. Holders of the Series A Convertible Preferred Stock are permitted to increase the Conversion Blocker to an amount not to exceed 19.99% upon 60 days ’ notice. Shares of Series A Convertible Preferred Stock generally have no voting rights, except as required by law and except that the consent of a majority of the holders of the outstanding Series A Convertible Preferred Stock will be required to amend the terms of the Series A Convertible Preferred Stock. In the event of the Company’s liquidation, dissolution or winding up, holders of Series A Convertible Preferred Stock will participate pari passu with any distribution of proceeds to holders of common stock. Holders of Series A Convertible Preferred Stock are entitled to receive when, as and if dividends are declared and paid on the common stock, an equivalent dividend, calculated on an as-converted basis. Shares of Series A Convertible Preferred Stock are otherwise not entitled to dividends. The Series A Convertible Preferred Stock (i) senior to any class or series of capital stock of the Company hereafter created specifically ranking by its terms junior to the Series A Convertible Preferred Stock; (ii) on parity with the common stock and any class or series of capital stock of the Company created specifically ranking by its terms on parity with the Series A Convertible Preferred Stock; and (iii) junior to the Series B Convertible Preferred Stock and to any class or series of capital stock of the Company created specifically ranking by its terms senior to any Series A Convertible Preferred Stock, in each case, as to distributions of assets upon liquidation, dissolution or winding up of the Company, whether voluntarily or involuntarily. The Company evaluated the Series A Preferred Stock for liability or equity classification under ASC 480, Distinguishing Liabilities from Equity At-the-market equity offering programs In August 2021, the Company entered into a sales agreement with Cantor pursuant to which the Company can offer and sell up to $ million of its common stock at the current market prices from time to time through Cantor as sales agent (the “August 2021 ATM”). During the years ended December 31, 2023, 2022, and 2021, the Company sold 0 shares, 1,964,448 shares and shares, respectively, under the August 2021 ATM for net proceeds of approximately $0.0 million, $27.4 million and $ million, respectively, (after deducting commissions and other offering expenses)

Stock-based compensation

Stock-based compensation	12 Months Ended
	Dec. 31, 2023
Stock-based compensation
Stock-based compensation	8. Stock-based compensation Stock-based compensation expense as reflected in the Company’s consolidated statements of operations and comprehensive loss was as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, ​ 2023 2022 2021 Research and development ​ $ 1,987 ​ $ 1,766 ​ $ 2,099 ​ Selling, general and administrative ​ 3,873 ​ 4,281 ​ 5,612 ​ Total stock-based compensation expense ​ $ 5,860 ​ $ 6,047 ​ $ 7,711 ​ ​ All of the $5.9 million, $6.0 million, and $7.7 million of stock-based compensation expense recorded during the years ended December 31, 2023, 2022, and 2021, respectively, was recorded to additional paid-in capital. The Company has awards outstanding under two equity compensation plans, the 2021 Equity Incentive Plan (the “2021 Plan”), and the Amended and Restated 2012 Incentive Plan (the “2012 Plan”), as well as the inducement award program. Terms of stock award agreements, including vesting requirements, are determined by the board of directors, subject to the provisions of the individual plans. 2021 Plan 2010 Equity Incentive Plan (the “ 2012 Plan The 2012 Plan became effective immediately upon the closing of the Company’s initial public offering in February 2012. Upon effectiveness of the 2012 Plan, the Company ceased making awards under the 2010 Plan. The 2012 Plan initially allowed the Company to grant awards for up to 285,714 shares of common stock, plus the number of shares of common stock available for grant under the 2010 Plan as of the effectiveness of the 2012 Plan (which was an additional 2,508 shares), plus that number of shares of common stock related to awards outstanding under the 2010 Plan which terminate by expiration, forfeiture, cancellation or otherwise. The 2012 Plan included an “evergreen provision” that allowed for an annual increase in the number of shares of common stock available for issuance under the 2012 Plan. The annual increase was added on the first day of each year from 2013 through 2018 and was equal to the lesser of 107,412 shares of common stock and 4.0% of the number of shares of common stock outstanding, or a lesser amount as determined by the board of directors. On each of January 1, 2018, January 1, 2017 and January 1, 2016, the number of shares available for issuance under the 2012 Plan increased by 107,412 under this provision. On December 18, 2018, the shareholders of the Company approved the Amended and Restated 2012 Incentive Plan which increased the maximum number of shares available for issuance under the 2012 Plan to 1,385,702 and eliminated the evergreen provision. On May 19, 2020, the shareholders of the Company approved the Amended and Restated 2012 Incentive Plan which increased the maximum number of shares available for issuance by 1,083,333 shares. Awards under the 2012 Plan may include the following award types: incentive stock options, nonqualified stock options, stock appreciation rights, restricted stock awards, RSUs, other stock-based or cash-based awards and any combination of the foregoing. As of December 31, 2023, under the 2012 Plan, the Company has granted stock options for 1,841,188 shares of common stock, of which 814,357 have been forfeited, 213,901 have expired, and 191,342 have been exercised, and granted RSUs for 556,432 shares of common stock, of which 87,458 have been forfeited and 455,878 have vested. The exercise price of each stock option has been equal to the closing price of a share of the Company’s common stock on the grant date. Upon adoption of the 2021 Plan, the Company ceased issuing awards from the 2012 Plan. Inducement Award Program In December 2014, the Company established an inducement award program (in accordance with Nasdaq Listing Rule 5635(c)(4)) under which it may grant non-statutory stock options to purchase, and RSUs in respect of up to an aggregate of respectively. In February 2020, the Board of Directors authorized the reduction of 169,447 shares available for issuance under this program. In September 2023, the Board of Directors authorized and reserved 500,000 additional shares of common stock under this program. The program is governed by the terms of the 2021 Plan, but shares issued pursuant to the program are not issued under the 2021 Plan. As of December 31, 2023, the Company had granted options for ​ Stock Options ​ Most options granted by the Company vest twenty-five percent (25%) one year from vesting start date and six and a quarter percent (6.25%) for each successive three-month period, thereafter (subject to acceleration of vesting in the event of certain change of control transactions) subject to the employee’s continued employment with, or service to, the Company on such vesting date and are exercisable for a period of ten years from the date of grant. A summary of the Company’s stock option activity and related information for the year ended December 31, 2023, is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Shares Weighted-average exercise price per share Weighted-average remaining contractual term (years) Aggregate intrinsic value (in thousands) Outstanding at December 31, 2022 1,168,105 ​ $ 33.63 7.1 ​ $ 18 ​ Granted 1,177,750 ​ ​ 7.98 ​ ​ ​ ​ ​ ​ Forfeited/cancelled (62,831) ​ ​ 35.38 ​ ​ ​ ​ ​ ​ Expired ​ (12,665) ​ ​ 117.12 ​ ​ ​ ​ ​ ​ Outstanding at December 31, 2023 2,270,359 ​ $ 19.81 7.8 ​ $ 559 ​ Vested at December 31, 2023 876,016 ​ $ 33.39 ​ 5.8 ​ $ 138 ​ ​ The fair value of each stock option was estimated using a Black-Scholes option-pricing model with the following weighted-average assumptions: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, ​ ​ 2023 ​ 2022 ​ 2021 Risk-free interest rate 3.77 % ​ 3.13 % ​ 1.15 % Volatility 92 % ​ 88 % ​ 89 % Dividend yield — ​ ​ — ​ ​ — ​ Expected term (years) 6.1 ​ ​ 5.8 ​ ​ 6.0 ​ ​ The Company recorded stock-based compensation expense associated with employee and non-employee stock options of $4.2 million, $4.2 million, and $4.1 million, for the years ended December 31, 2023, 2022, and 2021, respectively. The weighted-average grant date fair value of stock options granted in the years ended December 31, 2023, 2022, and 2021 was $6.16, $8.28, and $21.84 per stock option, respectively. The fair value of stock options that vested during the years ended December 31, 2023, 2022, and 2021 was $3.1 million, $4.4 million, and $3.8 million, respectively. The aggregate intrinsic value of options exercised (i.e., the difference between the market price at exercise and the price paid by employees to exercise the option) during the years ended December 31, 2023, 2022, and 2021 was $0.0 million, less than $0.1 million, and $0.8 million, respectively. At December 31, 2023 there was $9.2 million of total unrecognized compensation cost related to unvested stock options and the Company expects to recognize this cost over a remaining weighted-average period of 2.6 years. Restricted Stock Units (“RSUs”) Each RSU entitles the holder to receive one share of the Company’s common stock when the RSU vests. The RSUs generally vest (i) twenty-five percent (25%) one year from vesting start date and six and a quarter percent (6.25%) for each successive three-month period, thereafter, (ii) two tranches for 50% of the award with the second and final vesting date on the one year anniversary of the vesting commencement date and (iii) 100 percent within two years of the vesting commencement date. The RSUs are subject to acceleration of vesting in the event of certain change of control transactions and subject to the employee’s continued employment with, or service to, the Company on such vesting date. Compensation expense is recognized on a straight-line basis. A summary of RSU activity during the year ended December 31, 2023, is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Shares Weighted-average grant date fair value per share Outstanding at December 31, 2022 ​ 172,909 ​ $ 25.82 ​ Granted ​ 108,058 ​ $ 10.15 ​ Vested ​ (66,201) ​ $ 25.45 ​ Forfeited/cancelled ​ ​ (5,477) ​ $ 17.96 ​ Outstanding at December 31, 2023 ​ 209,289 ​ $ 18.05 ​ ​ The Company recorded stock-based compensation expense associated with employee and non-employee RSUs of $1.6 million, $1.8 million, and $3.5 million, for the years ended December 31, 2023, 2022, and 2021, respectively. The total fair value of restricted stock units vested during the years ended December 31, 2023, 2022, and 2021 was approximately $1.7 million, $2.3 million, and $3.7 million, respectively. At December 31, 2023, there was $3.1 million of total unrecognized compensation cost related to unvested RSUs and the Company expects to recognize this cost over a remaining weighted-average period of 2.1 years. Employee stock purchase plan At the Special Meeting of Stockholders, held on December 18, 2018, the stockholders approved the 2018 Employee Stock Purchase Plan (“2018 ESPP”). On June 21, 2019, the board of directors of the Company amended and restated the 2018 ESPP, to account for certain non-material changes to the plan’s administration (the “Amended and Restated 2018 ESPP”). The Amended and Restated 2018 ESPP provides eligible employees with the opportunity, through regular payroll deductions, to purchase shares of the Company’s common stock at 85% of the lesser of the fair market value of the common stock (a) on the date the option is granted, which is the first day of the purchase period, and (b) on the exercise date, which is the last business day of the purchase period. The Amended and Restated 2018 ESPP generally allows for two six-month purchase periods per year beginning in January and July, or such other periods as determined by the compensation committee of the Company’s board of directors. The Company has reserved 166,666 shares of common stock for the administration of the Amended and Restated 2018 ESPP. The fair value of shares expected to be purchased under the Amended and Restated 2018 ESPP was calculated using the Black-Scholes model with the following weighted-average assumptions: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, ​ ​ 2023 ​ 2022 ​ 2021 Risk-free interest rate 5.16 % ​ 1.56 % ​ 0.07 % Volatility 126 % ​ 77 % ​ 68 % Dividend yield — ​ ​ — ​ ​ — ​ Expected term (years) 0.5 ​ ​ 0.5 ​ ​ 0.5 ​ ​

Convertible senior notes

Convertible senior notes	12 Months Ended
	Dec. 31, 2023
Convertible Senior Notes
Convertible Senior Notes	9. Convertible Senior Notes 2018 Notes On October 17, 2018, the Company closed a registered direct public offering of $150.0 million aggregate principal amount of the Company’s 2018 Notes for net proceeds of approximately $145.3 million. The 2018 Notes were governed by the terms of a base indenture for senior debt securities (the “2018 Base Indenture”), as supplemented by the first supplemental indenture thereto (the “Supplemental Indenture” and together with the “2018 Base Indenture”, the “2018 Indenture”), each dated October 17, 2018, by and between the Company and Wilmington Trust, National Association, (“Wilmington”) as trustee. The 2018 Notes were senior unsecured obligations of the Company and bore interest at a rate of 5.00% per annum, payable semi-annually in arrears on May 1 and November 1 of each year, beginning on May 1, 2019. The 2018 Notes will mature on November 1, 2048, unless earlier repurchased, redeemed or converted in accordance with their terms. Prior to November 1, 2022, the Company did not have the right to redeem the 2018 Notes. On or after November 1, 2022, the Company may elect to redeem the 2018 Notes, in whole or in part, at a cash redemption price equal to the principal amount of the 2018 Notes to be redeemed, plus accrued and unpaid interest, if any. Unless the Company has previously called all outstanding 2018 Notes for redemption, the 2018 Notes will be subject to repurchase by the Company at the holders’ option on each of November 1, 2023, November 1, 2028, November 1, 2033, November 1, 2038 and November 1, 2043 (or, if any such date is not a business day, on the next business day) at a cash repurchase price equal to the principal amount of the 2018 Notes to be repurchased, plus accrued and unpaid interest, if any. The Company determined that the expected life of the 2018 Notes was equal to the period through November 1, 2023, as this represents the point at which the 2018 Notes were initially subject to repurchase by the Company at the option of the holders. In the fourth quarter of 2023, the Company repaid the remaining outstanding balance of 2018 Notes of $0.3 million in exchange for principal amount plus accrued and unpaid interest of a total of $0.3 million. As a result there are no outstanding 2018 Notes as of December 31, 2023. The components of the carrying value of the 2018 Notes as of December 31, 2022 are detailed below (in thousands): ​ ​ ​ ​ December 31, 2022 2018 Notes principal balance $ 300 Debt discount and issuance costs, net of accretion ​ (25) 2018 Notes, net $ 275 ​ 2019 Notes On November 14, 2019 and December 23, 2019, the Company entered into privately negotiated agreements to exchange approximately $114.3 million and $7.4 million, respectively, aggregate principal amount of the 2018 Notes for (i) approximately $62.9 million and $4.0 million, respectively, aggregate principal amount of newly issued 5.00% Convertible Senior Second Lien Notes due 2048 (the “2019 Notes”), (ii) an aggregate of $11.4 million and $0.7 million, respectively, in 2018 Notes principal repayment and (iii) accrued interest on the 2018 Notes through November 14, 2019 and December 23, 2019, respectively. As of March 31, 2020, all 2019 Notes had converted into shares of common stock and are no longer outstanding. 2020 Notes On November 6, 2020, the Company entered into a privately negotiated agreement with an investor who was a holder of the Company’s 2018 Notes to exchange approximately $28.0 million aggregate principal amount of 2018 Notes for approximately $28.0 million aggregate principal amount of newly issued 5.00% Convertible Senior Notes due 2048 (the “2020 Notes” and together with the 2018 Notes and 2019 Notes referred to as the “Notes”). The issuance of the 2020 Notes closed on November 13, 2020. On July 16, 2021, the aggregate principal of $28.0 million of 2020 Notes was converted into 717,949 shares of common stock. As a result, as of September 30, 2021, all 2020 Notes have converted into shares of common stock. Upon conversion of the 2020 Notes, holders received a cash payment equal to the accrued and unpaid interest on the converted 2020 Notes. Pursuant to ASC 815-15-40-1, upon conversion, the Company recorded the remaining discount on the 2020 Notes of $7.8 million as interest expense in the statements of operations and comprehensive loss during the year ended December 31, 2021. All Notes The Company determined that the expected life of the Notes was equal to the period through November 1, 2023, as this represents the point at which the Notes were initially subject to repurchase by the Company at the option of the holders. Accordingly, the total debt discount, inclusive of the fair value of the embedded conversion feature derivative at issuance and change in fair value of conversion options upon exchanges, was amortized using the effective interest method through November 1, 2023. The effective interest utilized to amortize 2018 Notes and 2020 Notes was 15.65% and 20.31%, respectively. For the year ended December 31, 2023, the Company recognized less than $0.1 million of interest expense related to the 2018 Notes.

Net loss per share

Net loss per share	12 Months Ended
	Dec. 31, 2023
Net loss per share
Net loss per share	10. Net Loss per Share ASC Topic 260, Earnings Per Share, The following potentially dilutive securities were excluded from the calculation of diluted net loss per share due to their anti-dilutive effect: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2023 2022 2021 Outstanding stock options ​ 2,270,359 1,168,105 1,355,220 ​ Outstanding restricted stock units ​ 209,289 ​ 172,909 ​ 233,710 ​ 2018 Notes ​ — ​ 3,489 ​ 3,489 ​ Employee stock purchase plan ​ 7,475 ​ 6,874 ​ 4,803 ​ Series A Convertible Preferred Stock ​ 833,333 ​ 833,333 ​ — ​ Series B Convertible Preferred Stock ​ 4,236,570 ​ — ​ — ​ Total potentially dilutive securities ​ 7,557,026 2,184,710 1,597,222 ​ ​

Income taxes

Income taxes	12 Months Ended
	Dec. 31, 2023
Income taxes
Income taxes	11. Income Taxes As of December 31, 2023, the Company had federal and state NOL carryforwards of approximately $473.6 million and $189.0 million, respectively, which are available to reduce future taxable income. The Company also had federal and state tax credits of $9.5 million and $2.2 million, respectively, which may be used to offset future tax liabilities. The NOL and tax credit carryforwards will expire at various dates through 2043, except for $277.9 million of federal NOL carryforwards which may be carried forward indefinitely. A reconciliation of income taxes computed using the U.S. federal statutory rate to that reflected in operations follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2023 2022 Income tax benefit using U.S. federal statutory rate 21.00 % 21.00 % State tax benefit, net of federal benefit 2.82 % 2.15 % Research and development tax credits 4.41 % 2.81 % Stock-based compensation ​ (0.98) % (2.17) % Permanent items 0.44 % (0.08) % Change in the valuation allowance (21.17) % (21.41) % Tax law change ​ (4.31) % — % NOL and tax credit expiration under Section 382 ​ (2.07) % (2.26) % Other (0.14) % (0.04) % ​ — % — % ​ On October 4, 2023, Massachusetts enacted tax law changes which included the adoption of a single sales apportionment factor effective on January 1, 2025. As required under ASC 740, the Company has accounted for the deferred tax impacts of this tax law change in the period the tax law was enacted, which has the impact of reducing its state deferred tax assets. The impact of the tax law change is offset by a change in valuation allowance. The principal components of the Company’s deferred tax assets and liabilities are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2023 2022 Deferred tax assets: ​ ​ ​ ​ ​ ​ ​ Net operating loss carryforwards ​ $ 110,152 ​ $ 103,243 ​ Capitalized research and development ​ 20,356 ​ 11,621 ​ Research and development credits ​ 11,192 ​ 7,107 ​ Stock-based compensation ​ 3,340 ​ 3,450 ​ Installment sale ​ ​ 6,909 ​ ​ 7,768 ​ Lease liability ​ ​ 311 ​ ​ 538 ​ Other deferred tax assets ​ 346 ​ 587 ​ Total deferred tax assets ​ 152,606 ​ 134,314 ​ Deferred tax liabilities: ​ ​ ​ ​ ​ ​ ​ Right-of-use asset ​ ​ (248) ​ ​ (425) ​ Debt discount ​ ​ — ​ ​ (4) ​ Other deferred tax liability ​ ​ — ​ ​ (29) ​ Total deferred tax liabilities ​ ​ (248) ​ ​ (458) ​ Net deferred tax asset prior to valuation allowance ​ ​ 152,358 ​ ​ 133,856 ​ Valuation allowance ​ (152,358) ​ (133,856) ​ Net deferred tax asset ​ $ — ​ $ — ​ ​ The Tax Cuts and Jobs Act (“TCJA”) requires taxpayers to capitalize and amortize research and development (“R&D”) expenditures under section 174 for tax years beginning after December 31, 2021. This rule became effective for the Company during 2022. The Company will amortize these costs for tax purposes over 5 15 The Company has recorded a valuation allowance against its deferred tax assets at December 31, 2023 and 2022 because the Company’s management believes that it is more likely than not that these assets will not be fully realized. The increase in the valuation allowance of approximately $18.5 million in the year ended December 31, 2023, primarily relates to the capitalization of research and development expenses, the generation of NOLs and R&D credits. Section 382 of the Internal Revenue Code and similar provisions under state law limit the utilization of U.S. NOL carryforwards, state NOL carryforwards, R&D credits, and Orphan Drug (“OD”) credits following certain cumulative changes in the ownership interest of significant stockholders over a three-year period in excess of 50%. Based on the Company’s analysis under Section 382, the Company believes that its federal NOL carryforwards, its state NOL carryforwards, R&D credits, and OD credits are limited by Section 382 and similar provisions under state law as of December 31, 2023. The portion of federal NOL carryforwards, state NOL carryforwards, R&D credits, and OD credits that were determined to be limited have been written off as of December 31, 2023. The remaining unused carryforwards and credits remain available for future periods. Due the Company’s full valuation allowance the write off of NOL carryforwards and R&D and OD credits did not have any impact to the statements of operation and comprehensive loss. The Company’s reserves related to taxes are based on a determination of whether and how much of a tax benefit taken by the Company in its tax filings or positions is more likely than not to be realized following resolution of any potential contingencies present related to the tax benefit. From inception and through December 31, 2023, the Company had no unrecognized tax benefits or related interest

Commitments and contingencies

Commitments and contingencies	12 Months Ended
	Dec. 31, 2023
Commitments and contingencies
Commitments and contingencies	12. Commitments and contingencies The Company entered into a lease agreement for approximately 27,810 square feet of office space in Needham, Massachusetts. Please refer to Note 6. Leases Pursuant to the terms of various agreements, the Company may be required to pay various development, regulatory and commercial milestones. In addition, if any products related to these agreements are approved for sale, the Company may be required to pay significant royalties on future sales. The payment of these amounts, however, is contingent upon the occurrence of various future events, which have a high degree of uncertainty of occurring.

License, collaboration and comm

License, collaboration and commercial agreements	12 Months Ended
	Dec. 31, 2023
License, collaboration and commercial agreements
License, collaboration and commercial agreements	13. License, collaboration and commercial agreements GenFleet Therapeutics (Shanghai), Inc. On August 24, 2023, the Company entered into a collaboration and option agreement (“GenFleet Agreement”) with GenFleet Therapeutics (Shanghai), Inc. (“GenFleet”), pursuant to which GenFleet granted the Company the option to obtain exclusive development and commercialization rights worldwide outside of mainland China, Hong Kong, Macau, and Taiwan (the “Territory”) for up to three oncology programs targeting RAS pathway driven cancers (the “GenFleet Options”). The Company may exercise its GenFleet Options on a program-by-program basis. The Company made an upfront payment of $2.0 million to GenFleet in September 2023 and will provide $1.5 million of research support (“GenFleet R&D Support Fee”) over the first three years of the GenFleet Agreement. In addition, pursuant to the GenFleet Agreement, upon achievement of certain development and commercial milestones, and upon the Company exercising its GenFleet Options, GenFleet will be entitled to receive payments of up to $622.0 million. The Company has also agreed to pay GenFleet royalties on net sales of licensed products in the Territory ranging from the mid to high single digits. The Company may terminate the GenFleet Agreement in its entirety or on a program-by-program basis by providing 90 days 60 days During the year ended December 31, 2023, the Company expensed $2.0 million related to the upfront payment and $0.2 million related to the GenFleet R&D Support Fee within research and development expense in the consolidated statements of operations and comprehensive loss. The future milestone payments are contingent in nature and will be recognized if and when the respective contingencies are resolved. If the Company elects to exercise its GenFleet Options, the related payment will be recognized if and when each respective GenFleet Option is elected. Secura Bio, Inc. (“Secura”) On August 10, 2020, the Company and Secura signed the Secura APA and on September 30, 2020, the transaction closed. Pursuant to the Secura APA, the Company sold to Secura its exclusive worldwide license, including related assets, for the research, development, commercialization, and manufacture in oncology indications of products containing duvelisib. The sale included certain intellectual property related to duvelisib in oncology indications, certain existing duvelisib inventory, claims and rights under certain contracts pertaining to duvelisib. Pursuant to the Secura APA, Secura assumed all operational and financial responsibility for activities that were part of the Company’s duvelisib oncology program, including all commercialization efforts related to duvelisib in the United States and Europe, as well as the Company’s ongoing duvelisib clinical trials. Further, Secura assumed all obligations with existing collaboration partners developing and commercializing duvelisib, which include Yakult Honsha Co., Ltd. (“Yakult”), CSPC Pharmaceutical Group Limited (“CSPC”), and Sanofi. Additionally, Secura assumed all royalty payment obligations due under the amended and restated license agreement with Infinity Pharmaceuticals, Inc. Pursuant to the terms of the Secura APA, Secura has paid the Company an up-front payment of $70.0 million in September 2020 and has agreed to pay the Company (i) regulatory milestone payments up to $45.0 million, consisting of a payment of $35.0 million upon receipt of regulatory approval of COPIKTRA in the United States for the treatment of peripheral T-cell lymphoma and a payment of $10.0 million upon receipt of the first regulatory approval for the commercial sale of COPIKTRA in the European Union for the treatment of peripheral T-cell lymphoma, (ii) sales milestone payments of up to $50.0 million, consisting of $10.0 million when total worldwide net sales of COPIKTRA exceed $100.0 million, $15.0 million when total worldwide net sales of COPIKTRA exceed $200.0 million and $25.0 million when total worldwide net sales of COPIKTRA exceed $300.0 million, (iii) low double-digit royalties on the annual aggregate net sales above $100.0 million in the United States, European Union, and the United Kingdom of Great Britain and Northern Ireland and (iv) 50% of all royalty, milestone and sublicense revenue payments payable to Secura under the Company’s existing license agreements with Sanofi, Yakult, and CSPC, and 50% of all royalty and milestone payments payable to Secura under any license or sublicense agreement entered into by Secura in certain jurisdictions. In connection with the Secura APA, the Company and Secura entered into a transition services agreement (“Secura TSA”). Under the terms of the Secura TSA, the Company provided certain support functions at Secura’s direction for a term of less than one year from the date of execution (“Secura TSA Services”). Services performed were paid at a mutually agreed upon rate. The Company evaluated the Secura APA and Secura TSA in accordance with ASC 606 as the Company concluded that the counterparty, Secura, is a customer. The Company identified the following performance obligations under the Secura APA and Secura TSA: ● a bundled performance obligation consisting of delivery of the duvelisib global license and intellectual property, certain existing duvelisib inventory, certain duvelisib contracts and clinical trials, certain regulatory approvals, and certain regulatory documentation and books and records (the “Bundled Secura Performance Obligation”); and ● Secura TSA Services. The Company concluded that the duvelisib global license and intellectual property were not distinct within the context of the contract (i.e. separately identifiable) because the other assets including certain existing duvelisib inventory, certain duvelisib contracts and clinical trials, certain regulatory approval, and certain regulatory documentation and books and records do not have stand-alone value from other duvelisib global license and intellectual property and Secura could not benefit from them without the duvelisib global license and intellectual property. Consistent with the guidance under ASC 606-10-25-16A, the Company disregarded immaterial promised goods and services when determining performance obligations. The Company has determined that the upfront payment of $70.0 million, future potential milestone payments and royalties including from Secura’s sublicensees should be allocated to the delivery of the Bundled Secura Performance Obligation. The Company has the right to consideration for TSA services in an amount that corresponds directly with the value to Secura of the Company’s performance to date. Consideration allocated to the Secura TSA Services will be recognized as such services are provided over the performance period using an output method based on the amount to which the Company has a right to invoice. The Company determined less than $0.1 million of future potential royalties the Company expects to receive pursuant to the Secura APA were not constrained as of December 31, 2023. When estimating the amount of royalties to be received that were not constrained, the Company used the expected value method as there are a range of possible outcomes. When estimating royalties expected to be received, the Company used a combination of internal projections and forecasts and data from external sources. The Company determined that all other future potential royalties were constrained under the guidance as of December 31, 2023. As part of the Company’s evaluation of the constraint on future royalties, the Company considered a number of factors in determining whether there is significant uncertainty associated with the future events that would result in royalty payments. Those factors include: the likelihood and magnitude of revenue reversals related to future royalties, the amount of variable consideration is highly susceptible to factors outside of the Company’s influence, the amount of time to resolve the uncertainty, and lack of significant history of selling COPIKTRA outside of the United States. As the consideration for future royalties is conditional, the Company recorded a corresponding contract asset for the expected future royalties. Portions of the contract asset are reclassified to accounts receivable when the right to consideration becomes unconditional. As of December 31, 2023, and 2022, the contract asset has been recorded within prepaid and other current assets on the consolidated balance sheets. The following table presents changes in the Company’s contract asset for the year ended December 31, 2023 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Contract Asset: December 31, 2022 Additions ​ Reclassification to receivable ​ December 31, 2023 Contract asset - Secura ​ $ 96 ​ $ — ​ $ (54) ​ $ 42 Total $ 96 ​ $ — ​ $ (54) ​ $ 42 ​ During the year ended December 31, 2023, the Company determined all future potential milestones were excluded from the transaction price, as all other milestone amounts were fully constrained under the guidance as of December 31, 2023. As part of the Company’s evaluation of the constraint, the Company considered a number of factors in determining whether there is significant uncertainty associated with the future events that would result in the milestone payments. Those factors included: the likelihood and magnitude of revenue reversals related to future milestones, the amount of variable consideration that is highly susceptible to factors outside of the Company’s influence and the uncertainty about the consideration is not expected to be resolved for an extended period of time. All future potential milestone payments were fully constrained as the risk of significant revenue reversal related to these amounts has not yet been resolved. During the year ended December 31, 2022, the Company recognized $2.6 million of sale of COPIKTRA license and related assets revenue within the statements of operations and comprehensive loss. The sale of COPIKTRA license and related assets revenue for the year ended December 31, 2022 related to one regulatory milestone for $2.5 million achieved by Secura’s sublicensee, CSPC, and $0.1 million related to royalties on COPIKTRA sales in the year ended December 31, 2022, and future royalties expected to be received pursuant to the Secura APA that were not constrained. The Company determined all other future potential milestones were excluded from the transaction price, as all other milestone amounts were fully constrained under the guidance as of December 31, 2022. During the year ended December 31, 2021, the Company recognized $1.4 million of sale of COPIKTRA license and related assets revenue within the statements of operations and comprehensive loss. The sale of COPIKTRA license and related assets revenue for the year ended December 31, 2021 primarily related to two regulatory milestone for $1.3 million achieved by Secura’s sublicensee and $0.2 million related to royalties received and expected to be received pursuant to the Secura APA. During the year ended December 31, 2021, the Company also recognized $0.6 million in transition services revenue within the statements of operations and comprehensive loss. The Company determined all other future potential milestones were excluded from the transaction price, as all other milestone amounts were fully constrained under the guidance as of December 31, 2021.

Employee benefit plan

Employee benefit plan	12 Months Ended
	Dec. 31, 2023
Employee benefit plan
Employee benefit plan	15. Employee benefit plan In June 2011, the Company adopted a 401(k) retirement and savings plan (the 401(k) Plan) covering all employees. The 401(k) Plan allows employees to make pre-tax or post-tax contributions up to the maximum allowable amount set by the Internal Revenue Service. Under the 401(k) Plan, the Company may make discretionary contributions as approved by the board of directors. The Company made contributions to the 401(k) Plan of approximately $0.8 million in each of the years ended December 31, 2023, 2022, and 2021.

Subsequent events

Subsequent events	12 Months Ended
	Dec. 31, 2023
Subsequent events.
Subsequent events	16. Subsequent events The Company reviews all activity subsequent to year end but prior to the issuance of the consolidated financial statements for events that could require disclosure or that could impact the carrying value of assets or liabilities as of the consolidated balance sheet date. The Company is not aware of any material subsequent events other than the following: Oxford Loan Agreement On January 4, 2024, the Company amended its Loan Agreement to extend the outside date for the period during which the Company may draw the Term C Loan from March 31, 2024, to March 31, 2025. Refer to Note 5. Long-term debt Option Exchange On January 17, 2024, the Company’s stockholders, upon recommendation of the board of directors, approved a one-time stock option exchange program (the “Option Exchange Program”) for certain employees, executive officers and non-employee directors of the Company who held certain underwater options and remained employed or otherwise engaged by the Company through the completion of the Exchange Offer. The Company’s offer to participate in the Option Exchange Program commenced on February 8, 2024, and expired on March 8, 2024 (the “Exchange Offer”). Pursuant to the Exchange Offer, 42 eligible holders elected to exchange, and the Company accepted for cancellation, eligible options to purchase an aggregate of 603,330 shares of the Company’s common stock. On March 11, 2024, promptly following the expiration of the Exchange Offer, the Company granted new options to purchase 603,330 shares of common stock, pursuant to the terms of the Exchange Offer and the 2021 Plan. The exercise price of the new options granted pursuant to the Option Exchange Offer was $11.44 per share, which was the closing price of the common stock on the Nasdaq Capital Market on the grant date of the new options. The stock option exchange is considered a modification of those options exchanged. The incremental compensation expense will be measured as the excess, if any, of the fair value of each new option granted measured as of the date the new options are granted, over the fair value of the eligible options surrendered, measured immediately prior to the grant of the new options. This incremental compensation expense will be recognized ratably over the remaining requisite service period of the new options subject to continued employment or service with the Company. Unrecognized compensation cost associated with stock options surrendered will be recognized in future periods subject to continued employment or service with the Company. The Company is continuing to evaluate the incremental compensation cost associated with the Option Exchange Program. ​

Summary of significant accoun_2

Summary of significant accounting policies (Policies)	12 Months Ended
	Dec. 31, 2023
Summary of significant accounting policies
Basis of presentation	Basis of presentation The accompanying financial statements of the Company have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) under the assumption that the Company will continue as a going concern for the next 12 months. Accordingly, they do not include any adjustments that might result from the uncertainty related to the Company’s ability to continue as a going concern.
Use of estimates	Use of estimates The preparation of the Company’s financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. On an ongoing basis, management evaluates its estimates, including but not limited to estimates related to revenue recognition, accrued and prepaid clinical trial expense and other general accruals, stock-based compensation expense and its preferred stock tranche liability. The Company bases its estimates on historical experience and other market-specific or other relevant assumptions that it believes to be reasonable. Actual results could differ from such estimates.
Segment and geographic information	Segment and geographic information Operating segments are defined as components of an enterprise about which separate discrete information is available and regularly reviewed by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company views its operations and manages its business in one operating segment, which is the business of developing and commercializing drugs for the treatment of cancer. All material long-lived assets of the Company reside in the United States.
Proceeds from Grants	Proceeds from grants In May 2022 the Company was awarded the “Therapeutic Accelerator Award” grant from Pancreatic Cancer Network (“PanCAN”) for up to $3.8 million (the “PanCAN Grant”). In August 2022, PanCAN agreed to provide the Company with an additional $0.5 million for the collection and analysis of patient samples. The grant is supporting a Phase 1b/2 clinical trial of GEMZAR (gemcitabine) and ABRAXANE (Nab-paclitaxel) in combination with avutometinib and defactinib entitled RAMP 205. The RAMP 205 study is evaluating whether combining avutometinib (to target mutant KRAS which is found in more than 90% of pancreatic adenocarcinomas) and defactinib (to reduce stromal density and adaptive resistance to avutometinib) to the standard GEMZAR/ABRAXANE regimen improves outcomes for patients with such pancreatic cancers. Through December 31, 2023, the Company has received $2.7 million of cash proceeds which was initially recorded as deferred liabilities on the balance sheet. The Company recognizes grants as contra research and development expense in the consolidated statement of operations and comprehensive loss on a systematic basis over the periods in which the entity recognizes as expenses the related costs for which the grants are intended to compensate. The Company recorded $2.0 million and $0.3 million of the proceeds as a reduction of research and development expense during the years ended December 31, 2023 and December 31, 2022, respectively. As of December 31, 2023 and December 31, 2022, the Company recorded $0.3 million and $0.7 million, respectively, as deferred liabilities in the consolidated balance sheet related to the PanCAN Grant.
Cash, cash equivalents and restricted cash	Cash, cash equivalents and restricted cash The Company considers all highly liquid investments with an original or remaining maturity of three months or less at the date of purchase to be cash equivalents. Cash equivalents consist of a U.S. Government money market funds and corporate bonds and commercial paper of publicly traded companies. Cash equivalents are reported at fair value. The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the consolidated balance sheets that sum to the total of the same such amounts shown in the consolidated statements of cash flows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2023 December 31, 2022 Cash and cash equivalents ​ $ 77,909 ​ $ 74,933 Restricted cash ​ 1,167 ​ 856 Total cash, cash equivalents and restricted cash ​ $ 79,076 ​ $ 75,789
Fair value of financial instruments	​ Fair value of financial instruments The Company determines the fair value of its financial instruments based upon the fair value hierarchy, which prioritizes valuation inputs based on the observable nature of those inputs. The fair value hierarchy applies only to the valuation inputs used in determining the reported fair value of the investments and is not a measure of the investment credit quality. The hierarchy defines three levels of valuation inputs: ​ ​ ​ ​ Level 1 inputs ​ Quoted prices in active markets for identical assets or liabilities that the Company can access at the measurement date. Level 2 inputs ​ Inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly. ​ Level 3 inputs ​ Unobservable inputs that reflect the Company’s own assumptions about the assumptions market participants would use in pricing the asset or liability. ​ ​ Items Measured at Fair Value on a Recurring Basis The following table presents information about the Company’s financial instruments that are measured at fair value on a recurring basis (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2023 Description Total Level 1 Level 2 Level 3 Financial assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents ​ $ 46,093 ​ $ 46,093 ​ $ — ​ $ — ​ Short-term investments ​ ​ 59,220 ​ ​ 5,992 ​ ​ 53,228 ​ ​ — ​ Total financial assets ​ $ 105,313 ​ $ 52,085 ​ $ 53,228 ​ $ — ​ Preferred stock tranche liability ​ $ 4,189 ​ $ — ​ $ — ​ $ 4,189 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 Description ​ Total Level 1 Level 2 Level 3 Financial assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents ​ $ 73,613 ​ $ 72,617 ​ $ 996 ​ $ — ​ Short-term investments ​ 12,961 ​ — ​ ​ 12,961 ​ — ​ Total financial assets ​ $ 86,574 ​ $ 72,617 ​ $ 13,957 ​ $ — ​ ​ A preferred stock tranche liability was recorded as a result of the entry into the Series B Convertible Preferred Stock Securities Purchase Agreement Note 7. Capital Stock) Below are the inputs used to value the preferred stock tranche liability at December 31, 2023 and January 24, 2023: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2023 ​ January 24, 2023 Risk-free interest rate 5.13-5.52 % ​ 4.41-4.84 % Volatility 75 % ​ 90 % Dividend yield — ​ ​ — ​ Remaining term (years) 0.6 ​ ​ 1.5 ​ ​ The following table represents a rollforward for the year ended December 31, 2023 of the preferred stock right liability recorded in connection with the entry into the Series B Convertible Preferred Stock Securities Purchase Agreement (in thousands): ​ ​ ​ ​ ​ January 1, 2023 ​ ​ $ — Fair value recognized upon entering into Securities Purchase Agreement ​ ​ ​ 6,940 Fair value adjustment ​ ​ ​ (2,751) December 31, 2023 ​ ​ $ 4,189 ​ Fair Value of Financial Instruments Note 9. Convertible Senior Notes The fair value of the Company’s long-term debt is determined using a discounted cash flow analysis with current applicable rates for similar instruments as of the consolidated balance sheet date. The carrying value of the Company’s long-term debt as of December 31, 2023 and December 31, 2022, was approximately $40.1 million and $24.5 million, respectively. The Company estimates that the fair value of its long-term debt as of December 31, 2023 and December 31, 2022, was approximately $39.6 million and $24.9 million, respectively. The fair value of the Company’s long-term debt was determined using Level 3 inputs.
Concentrations of credit risk and off-balance sheet risk	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 ​ ​ ​ ​ Gross Gross ​ ​ ​ ​ Amortized Unrealized Unrealized Fair ​ ​ Cost Gains Losses Value Cash, cash equivalents & restricted cash: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and money market accounts ​ $ 74,794 ​ $ — ​ $ — ​ $ 74,794 ​ Corporate bonds, agency bonds and commercial paper (due within 90 days ) ​ ​ 995 ​ ​ — ​ $ — ​ ​ 995 ​ Total cash, cash equivalents & restricted cash: ​ $ 75,789 ​ $ — ​ $ — ​ $ 75,789 ​ Investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate bonds, agency bonds and commercial paper (due within 1 year ) ​ $ 12,961 ​ $ 2 ​ $ (2) ​ $ 12,961 ​ Total investments ​ $ 12,961 ​ $ 2 ​ $ (2) ​ $ 12,961 ​ Total cash, cash equivalents, restricted cash and investments ​ $ 88,750 ​ $ 2 ​ $ (2) ​ $ 88,750 ​
Property and equipment	Property and equipment Property and equipment consist of laboratory equipment, office furniture, computer equipment and leasehold improvements. Expenditures for repairs and maintenance are recorded to expense as incurred, whereas major betterments are capitalized as additions to property and equipment. Depreciation and amortization are calculated using the straight-line method over the following estimated useful lives of the assets: ​ ​ ​ ​ Laboratory equipment 5 years ​ Furniture 5 years ​ Computer equipment 3 years ​ Leasehold improvements Lesser of useful life or life of lease ​ Upon retirement or sale, the cost of the disposed asset and the related accumulated depreciation are removed from the accounts and any resulting gain or loss is recognized. The Company reviews its long-lived assets for impairment whenever events or changes in business circumstances indicate that the carrying value of assets may not be recoverable. Recoverability is measured by comparison of the asset’s book value to future net undiscounted cash flows that the assets are expected to generate. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the book value of the assets exceed their fair value, which is measured based on the projected discounted future net cash flows arising from the assets. No impairment losses have been recorded through December 31, 2023.
Research and development costs	Research and development costs The Company expenses research and development costs to operations as incurred. Research and development expenses consist of: ● employee-related expenses, including salaries, benefits, travel and stock-based compensation expense; ● external research and development expenses incurred under arrangements with third parties, such as clinical research organizations (“CROs”), clinical trial sites, manufacturing organizations and consultants, including the scientific advisory board; ● license fees; ● facilities, depreciation and other expenses, which include direct and allocated expenses for rent and maintenance of facilities, and laboratory supplies; and
Stock-based compensation	Stock-based compensation For service-based equity awards, the Company recognizes stock-based compensation expense for stock options, and restricted stock units (“RSUs”) issued to employees, directors, and consultants based on the grant date fair value of the awards on a straight-line basis over the requisite service period, which typically is the vest period. The Company recognized stock-based compensation for shares issued to employees under the Company’s employee stock purchase plan (“ESPP”) plan. The Company has granted performance-based RSUs and stock options with terms that allow the recipients to vest in a specific number of shares based upon the achievement of performance-based milestones as specified in the grants. Stock-based compensation expense associated with these performance-based RSUs and stock options is recognized if the performance condition is considered probable of achievement using the Company’s best estimates of the time to vesting for the achievement of the performance-based milestones. The grant date fair value of stock options is estimated using the Black-Scholes option pricing model that takes into account the fair value of its common stock, the exercise price, the expected life of the option, the expected volatility of its common stock, expected dividends on its common stock, and the risk-free interest rate over the expected life of the option. The Company applies the simplified method described in the Securities and Exchange Commission (“SEC”) Staff Accounting Bulletin (“SAB”) Topic 14.D.2 to calculate the expected term as it does not have sufficient historical exercise data to provide a reasonable basis upon which to estimate the expected term for options granted to employees. The expected term is applied to the stock option grant group as a whole, as the Company does not expect substantially different exercise or post-vesting termination behavior among its population. The Company has not paid and do not anticipate paying cash dividends on the Company’s shares of common stock; therefore, the expected dividend yield is assumed to be zero. The computation of expected volatility is based on the historical volatility of the Company’s common stock. The risk-free interest rate is based on a treasury instrument whose term is consistent with the expected term of the stock options. The Company accounts for forfeitures as they occur. The Company issues shares under the Company’s ESPP to employees. Stock-based compensation expense for discounted purchases under the ESPP is measured using the Black-Scholes model to compute the fair value of the lookback provision plus the purchase discount and is recognized as compensation expense over the offering period
Leases	Leases At the inception of an arrangement, the Company determines whether the arrangement is or contains a lease based on the unique facts and circumstances within the arrangement. A lease is identified where an arrangement conveys the right to control the use of identified property, plant, and equipment for a period of time in exchange for consideration. Leases which are identified within the scope of ASC 842 and which have a term greater than one year are recognized on the Company’s consolidated balance sheets as right-of-use assets, lease liabilities and, if applicable, long-term lease liabilities. The Company has elected not to recognize leases with terms of one year or less on its consolidated balance sheets. Operating lease liabilities and their corresponding right-of-use assets are recorded based on the present value of lease payments over the expected remaining lease term. However, certain adjustments to the right-of-use asset may be required for items such as initial direct costs paid or incentives received. The interest rate implicit in lease contracts is typically not readily determinable. As a result, the Company utilizes its incremental borrowing rates to calculate the present value of lease payments. Incremental borrowing rates are the rates the Company incurs to borrow on a collateralized basis over a similar term an amount equal to the lease payments in a similar economic environment. In accordance with ASC 842, components of a lease are split into three categories: lease components (e.g., land, building, etc.), non-lease components (e.g., common area maintenance, maintenance, consumables, etc.), and non-components (e.g., property taxes, insurance, etc.). The fixed and in-substance fixed contract consideration (including any related to non-components) must be allocated based on fair values to the lease components and non-lease components. Although separation of lease and non-lease components is required, certain practical expedients are available. Entities may elect the practical expedient to not separate lease and non-lease components. Rather, they would account for each lease component and the related non-lease component together as a single component. The Company has elected to account for the lease and non-lease components of each of its operating leases as a single lease component and allocate all of the contract consideration to the lease component only. The lease component results in an operating right-of-use asset being recorded on the consolidated balance sheets and amortized on a straight-line basis as lease expense.
Revenue Recognition	Revenue recognition Revenue from Contracts with Customers
Sales of intellectual property	Sales of intellectual property
Collaborative Arrangements	Collaborative arrangements Collaborative Arrangements: Contracts are considered to be collaborative arrangements when they satisfy the following criteria defined in ASC Topic 808, Collaborative Arrangements possibility of significant risk and rewards, based on whether or not the activity is successful. Payments received from or made to a partner that are the result of a collaborative relationship with a partner, instead of a customer relationship, such as co-development activities, are recorded as a reduction or increase to research and development expense, respectively.
Accounts Receivable, Net	Accounts receivable, net Accounts receivable, net consists of amounts due from customers, net of applicable revenue reserves. Accounts receivable have standard payments that generally require payment within 30 to 90 days . The Company analyzes accounts that are past due for collectability and provides an allowance for receivables when collection becomes doubtful.
Income taxes	Income taxes The Company accounts for income taxes under the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases using enacted tax rates in effect for the year in which the differences are expected to affect taxable income. Tax benefits are recognized when it is more likely than not that a tax position will be sustained during an audit. Deferred tax assets are reduced by a valuation allowance if current evidence indicates that it is considered more likely than not that these benefits will not be realized. The Company recognizes the tax effects of an uncertain tax position only if it is more likely than not that it will be sustained based solely on its technical merits as of the reporting date and only in an amount more likely than not that it will be sustained upon review by the tax authorities. The Company evaluates uncertain tax positions on a quarterly basis and adjust the liability for changes in facts and circumstances, such as new regulations or interpretations by the taxing authorities, new information obtained during a tax examination, significant amendment to an existing tax law, or resolution of an examination. To the extent that the final tax outcome of these matters is different than the amounts recorded, such differences will impact the income tax provision in the period in which such determination is made. The resolution of its uncertain income tax positions is dependent on uncontrollable factors such as law changes, new case law, and the willingness of the income tax authorities to settle, including the timing thereof and other factors. Although the Company does not anticipate significant changes to its uncertain income tax positions in the next 12 months, items outside of its control could cause its uncertain income tax positions to change in the future, which would be recorded in its statements of operations. Interest and/or penalties related to income tax matters are recognized as a component of income tax expense. Net operating loss (“NOL”) and tax credit carryforwards are subject to review and possible adjustment by the Internal Revenue Service and state tax authorities and may become subject to an annual limitation in the event of certain cumulative changes in the ownership interest of significant stockholders over a three-year period in excess of 50%, as defined under Sections 382 and 383 of the Internal Revenue Code, as well as similar state provisions. This could limit the amount of tax attributes that can be utilized annually to offset future taxable income or tax liabilities. The amount of the annual limitation is determined based on the value of the Company immediately prior to the ownership change. Subsequent ownership changes may further affect the limitation in future years.
Net loss per share	​ Net loss per share Basic net loss per common share is calculated by dividing net loss applicable to common stockholders by the weighted-average number of common shares outstanding during the period. Weighted-average number of common shares outstanding includes the weighted average effect of the pre-funded warrants issued in June 2023, as the exercise of which requires little or no consideration for the delivery of shares of common stock. Diluted net loss per common share is calculated by increasing the denominator by the weighted-average number of additional shares that could have been outstanding from securities convertible into common stock, such as stock options, restricted stock units, and ESPP (using the “treasury stock” method), the Notes (defined herein) , Series A Convertible Preferred Stock, and Series B Convertible Preferred Stock (using the “if-converted” method), unless their effect on net loss per share is antidilutive. Under the “if-converted” method, convertible instruments that are-in-the-money, are assumed to have been converted as of the beginning of the period or when issued, if later. Additionally, the effects of any interest expense and changes in fair value of any bifurcated derivatives shall be added back to the numerator of the diluted net loss per share calculation. Refer to Note 10. Net Loss per share

Summary of significant accoun_3

Summary of significant accounting policies (Tables)	12 Months Ended
	Dec. 31, 2023
Summary of significant accounting policies
Schedule of reconciliation of cash, cash equivalents and restricted cash	The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the consolidated balance sheets that sum to the total of the same such amounts shown in the consolidated statements of cash flows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2023 December 31, 2022 Cash and cash equivalents ​ $ 77,909 ​ $ 74,933 Restricted cash ​ 1,167 ​ 856 Total cash, cash equivalents and restricted cash ​ $ 79,076 ​ $ 75,789
Schedule of financial instruments measured at fair value on a recurring basis	The following table presents information about the Company’s financial instruments that are measured at fair value on a recurring basis (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2023 Description Total Level 1 Level 2 Level 3 Financial assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents ​ $ 46,093 ​ $ 46,093 ​ $ — ​ $ — ​ Short-term investments ​ ​ 59,220 ​ ​ 5,992 ​ ​ 53,228 ​ ​ — ​ Total financial assets ​ $ 105,313 ​ $ 52,085 ​ $ 53,228 ​ $ — ​ Preferred stock tranche liability ​ $ 4,189 ​ $ — ​ $ — ​ $ 4,189 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 Description ​ Total Level 1 Level 2 Level 3 Financial assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents ​ $ 73,613 ​ $ 72,617 ​ $ 996 ​ $ — ​ Short-term investments ​ 12,961 ​ — ​ ​ 12,961 ​ — ​ Total financial assets ​ $ 86,574 ​ $ 72,617 ​ $ 13,957 ​ $ — ​
Schedule of derivative liability reconciliation	Below are the inputs used to value the preferred stock tranche liability at December 31, 2023 and January 24, 2023: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2023 ​ January 24, 2023 Risk-free interest rate 5.13-5.52 % ​ 4.41-4.84 % Volatility 75 % ​ 90 % Dividend yield — ​ ​ — ​ Remaining term (years) 0.6 ​ ​ 1.5 ​
Schedule of derivative liability reconciliation	The following table represents a rollforward for the year ended December 31, 2023 of the preferred stock right liability recorded in connection with the entry into the Series B Convertible Preferred Stock Securities Purchase Agreement (in thousands): ​ ​ ​ ​ ​ January 1, 2023 ​ ​ $ — Fair value recognized upon entering into Securities Purchase Agreement ​ ​ ​ 6,940 Fair value adjustment ​ ​ ​ (2,751) December 31, 2023 ​ ​ $ 4,189
Summary of available-for-sale securities with unrealized losses for less than 12 months	The following is a summary of available-for-sale securities with unrealized losses for less than 12 months as of December 31, 2023 and 2022 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2023 December 31, 2022 ​ ​ ​ Fair ​ Unrealized ​ Fair ​ Unrealized ​ ​ Value Losses Value Losses ​ Corporate bonds, agency bonds and commercial paper (due within 1 year) ​ $ 8,896 ​ $ (1) ​ $ 5,964 ​ $ (2) ​ Total available-for-sale securities in an unrealized loss position ​ $ 8,896 ​ $ (1) ​ $ 5,964 ​ $ (2) ​
Schedule of cash, cash equivalents and investments	Cash, cash equivalents, restricted cash and investments consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2023 ​ ​ ​ Gross Gross ​ ​ ​ ​ Amortized ​ Unrealized ​ Unrealized ​ Fair ​ Cost Gains Losses Value Cash, cash equivalents & restricted cash: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and money market accounts ​ $ 79,076 ​ $ — ​ $ — ​ $ 79,076 ​ Total cash, cash equivalents & restricted cash: ​ $ 79,076 ​ $ — ​ $ — ​ $ 79,076 ​ Investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate bonds, agency bonds and commercial paper (due within 1 year ) ​ ​ 59,208 ​ ​ 13 ​ ​ (1) ​ ​ 59,220 ​ Total investments ​ $ 59,208 ​ $ 13 ​ $ (1) ​ $ 59,220 ​ Total cash, cash equivalents, restricted cash and investments ​ $ 138,284 ​ $ 13 ​ $ (1) ​ $ 138,296 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 ​ ​ ​ ​ Gross Gross ​ ​ ​ ​ Amortized Unrealized Unrealized Fair ​ ​ Cost Gains Losses Value Cash, cash equivalents & restricted cash: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and money market accounts ​ $ 74,794 ​ $ — ​ $ — ​ $ 74,794 ​ Corporate bonds, agency bonds and commercial paper (due within 90 days ) ​ ​ 995 ​ ​ — ​ $ — ​ ​ 995 ​ Total cash, cash equivalents & restricted cash: ​ $ 75,789 ​ $ — ​ $ — ​ $ 75,789 ​ Investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate bonds, agency bonds and commercial paper (due within 1 year ) ​ $ 12,961 ​ $ 2 ​ $ (2) ​ $ 12,961 ​ Total investments ​ $ 12,961 ​ $ 2 ​ $ (2) ​ $ 12,961 ​ Total cash, cash equivalents, restricted cash and investments ​ $ 88,750 ​ $ 2 ​ $ (2) ​ $ 88,750 ​
Schedule of estimated useful lives of the assets	​ ​ ​ ​ Laboratory equipment 5 years ​ Furniture 5 years ​ Computer equipment 3 years ​ Leasehold improvements Lesser of useful life or life of lease ​

Property and equipment, net (Ta

Property and equipment, net (Tables)	12 Months Ended
	Dec. 31, 2022
Property and equipment, net
Schedule of property equipment and related accumulated depreciation	Property and equipment and related accumulated depreciation are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, December 31, ​ ​ 2023 ​ 2022 Leasehold improvements ​ $ 146 ​ $ 146 ​ Furniture and fixtures ​ 811 ​ 811 ​ Computer equipment ​ 665 ​ 665 ​ Assets not yet placed in service ​ 7 ​ — ​ ​ ​ 1,629 ​ 1,622 ​ Less: accumulated depreciation ​ (1,592) ​ (1,530) ​ Total property and equipment, net ​ $ 37 ​ $ 92 ​

Accrued expenses (Tables)

Accrued expenses (Tables)	12 Months Ended
	Dec. 31, 2022
Accrued expenses
Schedule of accrued expenses	Accrued expenses consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2023 December 31, 2022 ​ ​ ​ ​ ​ ​ ​ ​ Accrued clinical trial expenses ​ $ 6,518 ​ $ 4,281 ​ Accrued contract manufacturing expenses ​ ​ 2,010 ​ ​ 3,258 ​ Accrued other research and development expenses ​ ​ 1,043 ​ ​ 996 ​ Accrued compensation and related benefits ​ 4,796 ​ 3,844 ​ Accrued professional fees ​ 637 ​ 469 ​ Accrued consulting fees ​ 1,078 ​ 902 ​ Accrued interest ​ ​ 316 ​ ​ 192 ​ Accrued commercialization costs ​ 453 ​ 148 ​ Accrued other ​ 1,077 ​ 893 ​ Total accrued expenses ​ $ 17,928 ​ $ 14,983 ​ ​

Long-term debt (Tables)

Long-term debt (Tables)	12 Months Ended
	Dec. 31, 2022
Long-term debt
Schedule of carrying value of debt	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2023 December 31, 2022 Principal loan balance ​ $ 40,000 ​ $ 25,000 Final Payment Fee ​ ​ 661 ​ ​ 225 Debt issuance costs, net of accretion ​ ​ (575) ​ ​ (699) Long-term debt, net of discount ​ $ 40,086 ​ $ 24,526
Schedule of future principal payments under the Loan Agreement	​ ​ ​ ​ ​ 2024 ​ ​ — 2025 ​ ​ 15,000 2026 ​ ​ 20,000 2027 ​ ​ 5,000 Total principal payments ​ $ 40,000 ​

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2022
Leases
Summary of elements of lease expenses	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, ​ ​ 2023 ​ 2022 ​ ​ 2021 Lease Expense ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating lease expense ​ $ 885 ​ $ 885 ​ $ 885 Total Lease Expense ​ $ 885 ​ $ 885 ​ $ 885 Other Information - Operating Leases ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating cash flows paid for amounts included in measurement of lease liabilities ​ $ 1,060 ​ $ 1,039 ​ $ 1,019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2023 Other Balance Sheet Information - Operating Leases ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average remaining lease term (in years) ​ ​ ​ ​ ​ ​ ​ ​ 1.5 Weighted average discount rate ​ ​ ​ ​ ​ ​ ​ ​ 14.6% Maturity Analysis ​ ​ ​ ​ ​ ​ ​ ​ ​ 2024 ​ ​ ​ ​ ​ ​ ​ ​ 1,081 2025 ​ ​ ​ ​ ​ ​ ​ ​ 546 Total ​ ​ ​ ​ $ ​ ​ ​ 1,627 Less: Present value discount ​ ​ ​ ​ ​ ​ ​ ​ (156) Lease Liability ​ ​ ​ ​ $ ​ ​ ​ 1,471 ​

Capital Stock (Tables)

Capital Stock (Tables)	12 Months Ended
	Dec. 31, 2023
Capital stock
Schedule of shares of common stock reserved for the issuance of common stock for vested restricted stock units and the exercise of stock options	As of December 31, 2023 and 2022, the Company had reserved the following shares of common stock for the issuance of common stock for vested restricted stock units, the exercise of stock options, employee stock purchase plan, 2018 Notes, Series A Convertible Preferred Stock conversions to shares of common stock, the issuance and conversion of Series B Convertible Preferred Stock, and exercise of Pre-Funded Warrants (in thousands): ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ 2023 ​ 2022 Shares reserved under equity compensation plans 2,845 2,895 ​ Shares reserved for inducement grants ​ 810 ​ 327 ​ Shares reserved for 2018 Notes ​ — ​ 3 ​ Shares reserved for ESPP ​ 75 ​ 89 ​ Shares reserved for Series A Convertible Preferred Stock ​ 833 ​ 833 ​ Shares reserved for Series B Convertible Preferred Stock ​ 7,570 ​ — ​ Shares reserved for Pre-Funded Warrants ​ 1,539 ​ — ​ Total shares reserved 13,672 4,147 ​

Stock-based compensation (Table

Stock-based compensation (Tables)	12 Months Ended
	Dec. 31, 2022
Stock-based compensation
Schedule of stock-based compensation expense as reflected in the Company's consolidated statements of operations and comprehensive loss	Stock-based compensation expense as reflected in the Company’s consolidated statements of operations and comprehensive loss was as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, ​ 2023 2022 2021 Research and development ​ $ 1,987 ​ $ 1,766 ​ $ 2,099 ​ Selling, general and administrative ​ 3,873 ​ 4,281 ​ 5,612 ​ Total stock-based compensation expense ​ $ 5,860 ​ $ 6,047 ​ $ 7,711 ​
Summary of stock option activity and related information	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Shares Weighted-average exercise price per share Weighted-average remaining contractual term (years) Aggregate intrinsic value (in thousands) Outstanding at December 31, 2022 1,168,105 ​ $ 33.63 7.1 ​ $ 18 ​ Granted 1,177,750 ​ ​ 7.98 ​ ​ ​ ​ ​ ​ Forfeited/cancelled (62,831) ​ ​ 35.38 ​ ​ ​ ​ ​ ​ Expired ​ (12,665) ​ ​ 117.12 ​ ​ ​ ​ ​ ​ Outstanding at December 31, 2023 2,270,359 ​ $ 19.81 7.8 ​ $ 559 ​ Vested at December 31, 2023 876,016 ​ $ 33.39 ​ 5.8 ​ $ 138 ​
Schedule of assumptions used to estimate fair value of each stock option on grant date	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, ​ ​ 2023 ​ 2022 ​ 2021 Risk-free interest rate 3.77 % ​ 3.13 % ​ 1.15 % Volatility 92 % ​ 88 % ​ 89 % Dividend yield — ​ ​ — ​ ​ — ​ Expected term (years) 6.1 ​ ​ 5.8 ​ ​ 6.0 ​
Schedule of restricted stock units	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Shares Weighted-average grant date fair value per share Outstanding at December 31, 2022 ​ 172,909 ​ $ 25.82 ​ Granted ​ 108,058 ​ $ 10.15 ​ Vested ​ (66,201) ​ $ 25.45 ​ Forfeited/cancelled ​ ​ (5,477) ​ $ 17.96 ​ Outstanding at December 31, 2023 ​ 209,289 ​ $ 18.05 ​
Schedule of assumptions used to estimate fair value of each employee stock purchase plan on grant date	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, ​ ​ 2023 ​ 2022 ​ 2021 Risk-free interest rate 5.16 % ​ 1.56 % ​ 0.07 % Volatility 126 % ​ 77 % ​ 68 % Dividend yield — ​ ​ — ​ ​ — ​ Expected term (years) 0.5 ​ ​ 0.5 ​ ​ 0.5 ​

Convertible Senior Notes (Table

Convertible Senior Notes (Tables)	12 Months Ended
	Dec. 31, 2023
Convertible Senior Notes
Schedule of 2018 Notes	​ ​ ​ ​ December 31, 2022 2018 Notes principal balance $ 300 Debt discount and issuance costs, net of accretion ​ (25) 2018 Notes, net $ 275

Net loss per share (Tables)

Net loss per share (Tables)	12 Months Ended
	Dec. 31, 2022
Net loss per share
Schedule of potentially dilutive securities were excluded from the calculation of diluted net loss per share	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2023 2022 2021 Outstanding stock options ​ 2,270,359 1,168,105 1,355,220 ​ Outstanding restricted stock units ​ 209,289 ​ 172,909 ​ 233,710 ​ 2018 Notes ​ — ​ 3,489 ​ 3,489 ​ Employee stock purchase plan ​ 7,475 ​ 6,874 ​ 4,803 ​ Series A Convertible Preferred Stock ​ 833,333 ​ 833,333 ​ — ​ Series B Convertible Preferred Stock ​ 4,236,570 ​ — ​ — ​ Total potentially dilutive securities ​ 7,557,026 2,184,710 1,597,222 ​ ​

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2022
Income taxes
Schedule of reconciliation of income taxes computed using the U.S. federal statutory rate to that reflected in operations	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2023 2022 Income tax benefit using U.S. federal statutory rate 21.00 % 21.00 % State tax benefit, net of federal benefit 2.82 % 2.15 % Research and development tax credits 4.41 % 2.81 % Stock-based compensation ​ (0.98) % (2.17) % Permanent items 0.44 % (0.08) % Change in the valuation allowance (21.17) % (21.41) % Tax law change ​ (4.31) % — % NOL and tax credit expiration under Section 382 ​ (2.07) % (2.26) % Other (0.14) % (0.04) % ​ — % — %
Schedule of principal components of deferred tax assets and liabilities	On October 4, 2023, Massachusetts enacted tax law changes which included the adoption of a single sales apportionment factor effective on January 1, 2025. As required under ASC 740, the Company has accounted for the deferred tax impacts of this tax law change in the period the tax law was enacted, which has the impact of reducing its state deferred tax assets. The impact of the tax law change is offset by a change in valuation allowance. The principal components of the Company’s deferred tax assets and liabilities are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2023 2022 Deferred tax assets: ​ ​ ​ ​ ​ ​ ​ Net operating loss carryforwards ​ $ 110,152 ​ $ 103,243 ​ Capitalized research and development ​ 20,356 ​ 11,621 ​ Research and development credits ​ 11,192 ​ 7,107 ​ Stock-based compensation ​ 3,340 ​ 3,450 ​ Installment sale ​ ​ 6,909 ​ ​ 7,768 ​ Lease liability ​ ​ 311 ​ ​ 538 ​ Other deferred tax assets ​ 346 ​ 587 ​ Total deferred tax assets ​ 152,606 ​ 134,314 ​ Deferred tax liabilities: ​ ​ ​ ​ ​ ​ ​ Right-of-use asset ​ ​ (248) ​ ​ (425) ​ Debt discount ​ ​ — ​ ​ (4) ​ Other deferred tax liability ​ ​ — ​ ​ (29) ​ Total deferred tax liabilities ​ ​ (248) ​ ​ (458) ​ Net deferred tax asset prior to valuation allowance ​ ​ 152,358 ​ ​ 133,856 ​ Valuation allowance ​ (152,358) ​ (133,856) ​ Net deferred tax asset ​ $ — ​ $ — ​

License, collaboration and co_2

License, collaboration and commercial agreements (Tables)	12 Months Ended
	Dec. 31, 2022
License, collaboration and commercial agreements
Schedule of contract assets	The following table presents changes in the Company’s contract asset for the year ended December 31, 2023 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Contract Asset: December 31, 2022 Additions ​ Reclassification to receivable ​ December 31, 2023 Contract asset - Secura ​ $ 96 ​ $ — ​ $ (54) ​ $ 42 Total $ 96 ​ $ — ​ $ (54) ​ $ 42

Nature of business (Details)

Nature of business (Details) - USD ($) $ in Thousands	Mar. 22, 2023	Mar. 25, 2022	Dec. 31, 2023	Dec. 31, 2022
Nature of business
Accumulated deficit			$ 824,890	$ 737,523
Term loan
Nature of business
Issuance of debt		$ 25,000
Term B Loan
Nature of business
Issuance of debt	$ 15,000

Nature of business - Reverse St

Nature of business - Reverse Stock Split (Details)	May 30, 2023 $ / shares shares	Dec. 31, 2023 $ / shares shares	Dec. 31, 2022 $ / shares shares
Nature of business
Common stock, par value (in dollars per share) | $ / shares		$ 0.0001	$ 0.0001
Common stock, shares authorized | shares		300,000,000	300,000,000
Certificate of Amendment
Nature of business
Common stock, par value (in dollars per share) | $ / shares	$ 0.0001
Reverse stock split ratio	0.0833
Common stock, shares authorized | shares	300,000,000

Summary of significant accoun_4

Summary of significant accounting policies - Segment and geographic information (Details)	12 Months Ended
	Dec. 31, 2023 item
Segment and geographic information
Number of operating segments	1

Summary of significant accoun_5

Summary of significant accounting policies - Proceeds from grants (Details) - USD ($) $ in Thousands	1 Months Ended		12 Months Ended
	Aug. 31, 2022	May 31, 2022	Dec. 31, 2023	Dec. 31, 2022
Summary of significant accounting policies
Grant awarded, amount		$ 3,800
Cash proceeds	$ 500		$ 2,700
Reduction of research and development expense			$ 2,000	$ 300
Research and development costs			Research and development costs The Company expenses research and development costs to operations as incurred. Research and development expenses consist of: ● employee-related expenses, including salaries, benefits, travel and stock-based compensation expense; ● external research and development expenses incurred under arrangements with third parties, such as clinical research organizations (“CROs”), clinical trial sites, manufacturing organizations and consultants, including the scientific advisory board; ● license fees; ● facilities, depreciation and other expenses, which include direct and allocated expenses for rent and maintenance of facilities, and laboratory supplies; and
Deferred liabilities			$ 327	$ 710

Summary of significant accoun_6

Summary of significant accounting policies - Cash, cash equivalents and restricted cash (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Cash and cash equivalents	$ 77,909	$ 74,933
Restricted cash	241	241
Restricted cash	1,167	856
Total cash, cash equivalents and restricted cash	79,076	75,789	$ 21,493	$ 68,023
Prepaid Expenses and Other Current Assets
Property, Plant and Equipment [Line Items]
Restricted cash	900	$ 600
Letter of credit | Office and Laboratory Space in Needham, Massachusetts.
Property, Plant and Equipment [Line Items]
Restricted cash	$ 200

Summary of significant accoun_7

Summary of significant accounting policies - Fair Value Financial Instruments, Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Financial liabilities
Debt, carrying value	$ 40,000	$ 25,000
2018 Notes, net
Financial liabilities
Debt, carrying value	300
Level 3 | Term loan
Financial liabilities
Debt, fair value	$ 39,600	24,900
Level 3 | 2018 Notes, net
Financial liabilities
Debt, fair value		$ 300

Summary of significant accoun_8

Summary of significant accounting policies - Fair Value Financial Instruments, Measured at Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Financial assets
Short-term investments	$ 59,220
Total financial assets	105,313
Preferred stock tranche liability	4,189
Level 1
Financial assets
Short-term investments	5,992
Total financial assets	52,085
Level 2
Financial assets
Short-term investments	53,228
Total financial assets	53,228
Level 3
Financial assets
Preferred stock tranche liability	4,189
Recurring basis
Financial assets
Cash equivalents	46,093	$ 73,613
Short-term investments		12,961
Total financial assets		86,574
Preferred stock tranche liability	4,189
Recurring basis | Level 1
Financial assets
Cash equivalents	46,093	72,617
Total financial assets		72,617
Recurring basis | Level 2
Financial assets
Cash equivalents		996
Short-term investments		12,961
Total financial assets		$ 13,957
Recurring basis | Level 3
Financial assets
Preferred stock tranche liability	$ 4,189

Summary of significant accoun_9

Summary of significant accounting policies - Preferred stock tranche liability (Details) $ in Thousands	Jan. 24, 2024	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Financial liabilities
Long-term debt		$ 40,086	$ 24,526
Debt, carrying value		40,000	25,000
2018 Notes principle balance
Financial liabilities
Debt, carrying value			300
Level 3 | Term loan
Financial liabilities
Fair value of long-term debt		40,100	24,500
Debt, fair value		$ 39,600	$ 24,900
Risk-free interest rate | Level 3 | Maximum
Financial liabilities
Debt Instrument, Measurement Input	4.84	5.52
Risk-free interest rate | Level 3 | Minimum
Financial liabilities
Debt Instrument, Measurement Input	4.41	5.13
Volatility | Level 3
Financial liabilities
Debt Instrument, Measurement Input	90	75
Remaining term | Level 3
Financial liabilities
Remaining term (years)	1 year 6 months	1 year 8 months 7 days

Summary of significant accou_10

Summary of significant accounting policies - Preferred stock right liability (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($)
Financial assets
Fair value recognized upon entering into Securities Purchase Agreement	$ 6,940
Fair value adjustment	2,751
December 31, 2023	4,189
Level 3
Financial assets
Fair value recognized upon entering into Securities Purchase Agreement	6,940
Fair value adjustment	(2,751)
December 31, 2023	$ 4,189

Summary of significant accou_11

Summary of significant accounting policies - Fair Value Financial Instruments, Derivative Liability (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Nov. 06, 2020	Oct. 17, 2018
Derivative liability
Debt, carrying value	$ 40,000	$ 25,000
2018 Notes, net
Derivative liability
Interest rate (as a percent)		5%		5%
Debt, carrying value	$ 300
2018 Notes, net | Level 3
Derivative liability
Debt, fair value		$ 300
2020 Notes
Derivative liability
Interest rate (as a percent)			5%

Summary of significant accou_12

Summary of significant accounting policies - Investments (Details)	12 Months Ended
	Dec. 31, 2023 USD ($) item	Dec. 31, 2022 USD ($) item	Dec. 31, 2021 USD ($)
Investments
Total fair value of available-for-sale securities in an unrealized loss position for less than 12 months	$ 8,896,000	$ 5,964,000
Total unrealized loss of available-for-sale securities with unrealized losses for less than 12 months	(1,000)	(2,000)
Cash, cash equivalents & restricted cash	77,909,000	74,933,000
Gross Unrealized Gains	13,000	2,000
Total cash, cash equivalents, restricted cash and investments, Gross Unrealized Gains	13,000	2,000	$ 2,000
Gross Unrealized Losses	(1,000)	(2,000)
Total cash, cash equivalents, restricted cash and investments, Gross Unrealized Losses	(1,000)	(2,000)	(2,000)
Realized gains or losses on investments	$ 0	$ 0	0
Number of investments in unrealized loss position | item	2	2
Number of investments in unrealized loss position for more than 12 months	0	0
Amortized Cost
Investments
Cash, cash equivalents & restricted cash	$ 79,076,000	$ 75,789,000
Investments, Amortize Cost	59,208,000	12,961,000
Total cash, cash equivalents, restricted cash and investments, Amortized Cost	138,284,000	88,750,000	12,961,000
Total
Investments
Cash, cash equivalents & restricted cash, Fair Value	79,076,000	75,789,000
Investments, Fair Value	59,220,000	12,961,000
Total cash, cash equivalents, restricted cash and investments, Fair Value	138,296,000	88,750,000	12,961,000
Cash, cash equivalents & restricted cash | Amortized Cost
Investments
Cash, cash equivalents & restricted cash			995,000
Cash, cash equivalents & restricted cash | Total
Investments
Cash, cash equivalents & restricted cash, Fair Value			995,000
Cash and money market accounts. | Amortized Cost
Investments
Cash, cash equivalents & restricted cash		74,794,000	74,794,000
Cash and money market accounts. | Total
Investments
Cash, cash equivalents & restricted cash, Fair Value		74,794,000	74,794,000
Corporate bonds, agency bonds and commercial paper
Investments
Gross Unrealized Gains		2,000
Gross Unrealized Losses		(2,000)
Corporate bonds, agency bonds and commercial paper | Amortized Cost
Investments
Cash, cash equivalents & restricted cash		995,000
Due within 1 year		12,961,000
Corporate bonds, agency bonds and commercial paper | Total
Investments
Cash, cash equivalents & restricted cash, Fair Value		995,000
Due within 1 year, Fair Value		12,961,000
Investments.
Investments
Gross Unrealized Gains			2,000
Gross Unrealized Losses			(2,000)
Investments. | Amortized Cost
Investments
Investments, Amortize Cost			12,961,000
Investments. | Total
Investments
Investments, Fair Value			$ 12,961,000
Corporate bonds and commercial paper | Cash and money market accounts. | Amortized Cost
Investments
Cash, cash equivalents & restricted cash	79,076,000
Corporate bonds and commercial paper | Cash and money market accounts. | Total
Investments
Cash, cash equivalents & restricted cash, Fair Value	79,076,000
Corporate bonds, agency bonds and commercial paper (due within 1 year)
Investments
Fair value of available-for-sale securities with unrealized losses for less than 12 months	8,896,000	5,964,000
Unrealized loss of available-for-sale securities with unrealized losses for less than 12 months	$ (1,000)	$ (2,000)
Maturity period, investments	1 year
Gross Unrealized Gains	$ 13,000
Gross Unrealized Losses	(1,000)
Corporate bonds, agency bonds and commercial paper (due within 1 year) | Amortized Cost
Investments
Due within 1 year	59,208,000
Corporate bonds, agency bonds and commercial paper (due within 1 year) | Total
Investments
Due within 1 year, Fair Value	$ 59,220,000
Corporate bonds, agency bonds and commercial paper (due within 1 year) | Corporate bonds and commercial paper
Investments
Maturity period, investments		1 year
Corporate bonds, agency bonds and commercial paper (due within 90 days)
Investments
Original maturity period, cash and cash equivalents		90 days

Summary of significant accou_13

Summary of significant accounting policies - Concentrations of credit risk and off-balance sheet risk (Details) $ in Thousands	1 Months Ended		12 Months Ended
	Aug. 31, 2022 USD ($)	May 31, 2022 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($) Institution customer
Concentrations of credit risk and off-balance sheet risk
Accounts Receivable, Net				$ 31
Off-balance sheet concentrations of credit risk description			As of December 31, 2023, the Company’s cash, cash equivalents and investments were deposited at four financial institutions and it has no significant off-balance sheet concentrations of credit risk, such as foreign currency exchange contracts, option contracts or other hedging arrangements.
Number of financial institutions in which cash, cash equivalents and investments were deposited | Institution				4
Grant awarded, amount		$ 3,800
Cash proceeds	$ 500		$ 2,700
Reduction of research and development expense			2,000	$ 300
Deferred liabilities			$ (383)	$ 710
Trade accounts receivable | Credit Concentration Risk
Concentrations of credit risk and off-balance sheet risk
Number of customer | customer				1
Trade accounts receivable | Credit Concentration Risk | Minimum
Concentrations of credit risk and off-balance sheet risk
Percentage				60%
Revenue | Customer Concentration Risk
Concentrations of credit risk and off-balance sheet risk
Number of customer | customer				1

Summary of significant accou_14

Summary of significant accounting policies - Property and equipment (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($)
Property and equipment, net
Impairment losses on long-lived assets	$ 0
Laboratory equipment
Property and equipment, net
Estimated useful lives	5 years
Furniture
Property and equipment, net
Estimated useful lives	5 years
Computer equipment
Property and equipment, net
Estimated useful lives	3 years

Summary of significant accou_15

Summary of significant accounting policies - Accounts receivable, net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Sale of COPIKTRA license and related assets
Revenue recognition
Total revenue		$ 2,596	$ 1,447
Minimum
Accounts Receivable
Threshold accounts receivable typically due	30 days
Maximum
Accounts Receivable
Threshold accounts receivable typically due	90 days

Property and equipment, net (De

Property and equipment, net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Property and equipment
Property and equipment, gross	$ 1,629	$ 1,622
Less: accumulated depreciation	(1,592)	(1,530)
Property and equipment, net	37	92
Depreciation expenses	62	118	$ 206
Leasehold improvements
Property and equipment
Property and equipment, gross	146	146
Furniture
Property and equipment
Property and equipment, gross	811	811
Computer equipment
Property and equipment
Property and equipment, gross	665	$ 665
Assets not yet placed in service
Property and equipment
Property and equipment, gross	$ 7

Accrued expenses (Details)

Accrued expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Accrued expenses
Accrued clinical trail expenses	$ 6,518	$ 4,281
Accrued contract manufacturing expenses	2,010	3,258
Accrued other research and development expenses	1,043	996
Accrued compensation and related benefits	4,796	3,844
Accrued professional fees	637	469
Accrued consulting fees	1,078	902
Accrued interest	316	192
Accrued commercialization costs	453	148
Accrued other	1,077	893
Total accrued expenses	$ 17,928	$ 14,983

Long-term debt (Details)

Long-term debt (Details) - USD ($) $ in Millions	Mar. 22, 2023	Mar. 25, 2022
Loan Agreement
Long-term debt
Financial covenants		$ 0
Accrued interest rate		5%
Term loan
Long-term debt
Aggregate principal amount		$ 150
Issuance of debt		25
Current borrowing capacity		$ 110
Percentage of final prepayment fee		5%
Additional interest rate in an event of default		0.50%
Term loan | Secured Overnight Financing Rate
Long-term debt
Interest rate	7.37%
Basis spread	0.13%
Term loan | If prepaid on or before the first anniversary
Long-term debt
Percentage of final prepayment fee		3%
Term loan | If prepaid after the first anniversary and on or before the second anniversary
Long-term debt
Percentage of final prepayment fee		2%
Term loan | If prepaid after the second anniversary
Long-term debt
Percentage of final prepayment fee		1%
Term B Loan
Long-term debt
Issuance of debt	$ 15
Term C Loan
Long-term debt
Aggregate principal amount		$ 25
Debt instrument period to draw loan, Minimum		60 days
Term D Loan
Long-term debt
Aggregate principal amount		$ 35
Debt instrument period to draw loan, Minimum		30 days
Gross product revenue to be achieved		$ 50
Term F Loan
Long-term debt
Aggregate principal amount		$ 50

Long-term debt - Components of

Long-term debt - Components of carrying value of debt (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Long-term debt
Principal loan balance	$ 40,000	$ 25,000
Final Payment Fee	661	225
Debt issuance costs, net of accretion	(575)	(699)
Long-term debt, net of discount	$ 40,086	$ 24,526

Long-term debt - Schedule of in

Long-term debt - Schedule of interest expenses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Long-term debt
Contractual Interest	$ 3,472	$ 1,733	$ 773
Amortization of debt discount and issuance costs	230	179	9,199
Amortization of Final Payment Fee	437	225
Interest Expense, Total	$ 4,139	$ 2,137	$ 9,972

Long-term debt - Future princip

Long-term debt - Future principal payments (Details) $ in Thousands	Dec. 31, 2023 USD ($)
Future principal payments
2025	$ 15,000
2026	20,000
2027	5,000
Total principal payments	$ 40,000

Leases (Details)

Leases (Details) $ in Millions	Feb. 15, 2018 USD ($) ft²	Apr. 15, 2014 ft²
Office and Laboratory Space in Needham, Massachusetts.
Leases
Area of space | ft²	27,810	15,197
Office and Laboratory Space in Needham, Massachusetts. | Minimum
Leases
Operating lease expense | $	$ 0.7
Office and Laboratory Space in Needham, Massachusetts. | Maximum
Leases
Operating lease expense | $	$ 1.1
Office and Laboratory Space in Needham, Massachusetts
Leases
Area of space | ft²	27,810

Leases - Balance sheet and othe

Leases - Balance sheet and other information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Leases
Right-of use asset	$ 1,171	$ 1,789
Lease liability	1,471	1,500
Lease Expense
Operating lease expense	885	885	$ 885
Total Lease Expense	885	885	885
Other Information - Operating Leases
Operating cash flows paid for amounts included in measurement of lease liabilities	$ 1,060	1,039	$ 1,019
Weighted average remaining lease term (in years)	1 year 6 months
Weighted average discount rate	14.60%
Maturity Analysis
2025	$ 1,081
2026	546
Total	1,627
Less: Present value discount	(156)
Lease Liability	$ 1,471	$ 1,500

Capital Stock (Details)

Capital Stock (Details) $ in Thousands		1 Months Ended	12 Months Ended
	Nov. 04, 2022 shares	Aug. 31, 2021 USD ($)	Dec. 31, 2023 USD ($) Vote shares	Dec. 31, 2022 USD ($) shares	Dec. 31, 2021 USD ($)	Dec. 18, 2018 shares
Common stock
Shares reserved for issuance			13,672,000	4,147,000
Number of votes entitled for each share of common stock | Vote			1
Common stock
Proceeds from Issuance of Common Stock | $			$ 91,420	$ 27,354	$ 6,723
Preferred Stock, Shares Authorized			5,000,000
Pre-Funded Warrant
Common stock
Shares reserved for issuance			1,539,000
Common stock | Biotechnology Value Fund [Member]
Common stock
Conversion of stock, shares converted	833,333
Inducement Award Program
Common stock
Shares reserved for issuance			810,000	327,000
2021 ATM Program | At-the-market equity offering program
Common stock
Net proceeds from issuance of stock | $				$ 27,400	6,800
2021 ATM Program | Common stock | At-the-market equity offering program
Common stock
Maximum value of common stock allowed to be sold | $		$ 100,000
Convertible Common Stock [Member] | 2018 Notes, net
Common stock
Shares reserved for issuance				3,000
Equity compensation plans
Common stock
Shares reserved for issuance			2,845,000	2,895,000
Employee Stock purchase plan
Common stock
Shares reserved for issuance			75,000	89,000		166,666
Common stock
Proceeds from Issuance of Common Stock | $			$ 100	$ 200	$ 200
Series A Preferred Stock
Common stock
Shares reserved for issuance			833,000	833,000
Series B Preferred Stock
Common stock
Shares reserved for issuance			7,570,000

Capital stock - June 2023 Publi

Capital stock - June 2023 Public Offering (Details) - Underwriting Agreement - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
	Jun. 15, 2023	Dec. 31, 2023
Class of Stock [Line Items]
Period options are exercisable	30 days
Stock Issued, Pre Funded Warrants, Net of Issuance Costs		$ 91.4
Public
Class of Stock [Line Items]
Common shares, offered	7,181,409
Sale price of the Common Stock	$ 9.75
Underwriters
Class of Stock [Line Items]
Common shares, offered	1,308,000
Pre-Funded Warrant
Class of Stock [Line Items]
Exercise price of shares of common stock in the warrant issued (in dollars per share)	$ 0.001
Maximum amount of common stock owned, as a percentage, that would prevent exercise	9.99%
Days of notice for increase/decrease to maximum percentage owned	61 days
Upper limit of maximum amount of common stock owned by a holder, as a percentage	19.99%
Shares issued		1,538,591
Pre-Funded Warrant | Investors
Class of Stock [Line Items]
Common shares, offered	1,538,591
Sale price of the Common Stock	$ 9.749
Exercise price of shares of common stock in the warrant issued (in dollars per share)	$ 0.001
Common stock
Class of Stock [Line Items]
Shares issued		8,489,409

Capital Stock - Convertible Pre

Capital Stock - Convertible Preferred Stock (Details)			12 Months Ended
	Jan. 24, 2023 USD ($) tranche $ / shares shares	Nov. 04, 2022 $ / shares shares	Dec. 31, 2023 USD ($) shares
Class of Stock [Line Items]
Preferred Stock, Shares Authorized | shares			5,000,000
Preferred stock tranche liability | $			$ 4,189,000
SeriesA Convertible Preferred Stock
Class of Stock [Line Items]
Convertible preferred stock, shares issued upon conversion | shares		0.833
Conversion of preferred stock, conversion blocker, percent		9.99%
Conversion of Preferred Stock, Conversion Blocker, Notice Period		60 days
Series B Convertible Preferred Stock
Class of Stock [Line Items]
Number of tranches | tranche	2
Convertible preferred stock, shares issued upon conversion | shares	3.5305
Conversion of preferred stock, conversion blocker, percent	9.99%
Conversion of Preferred Stock, Conversion Blocker, Percent, Upon Giving Notice	19.99%
Conversion of Preferred Stock, Conversion Blocker, Notice Period	60 days
Threshold share price | $ / shares	$ 31.77
Expected closing period of issuance	10 days
Liquidation preference per share | $ / shares	$ 1
Fair value of the Second Tranche Right | $	$ 6,900,000		4,200,000
Mark-to-market adjustment under change in fair value of preferred stock tranche liability | $			$ 2,800,000
Series B Convertible Preferred Stock | Private placement
Class of Stock [Line Items]
Shares issued | shares	944,160
Conversion price | $ / shares	$ 7.0812
Gross proceeds | $	$ 30,000,000
Threshold share price | $ / shares	$ 13.50
Share price (in dollars per share) | $ / shares	$ 9
Share issue period	10 days
Threshold trading volume | $	$ 25,000,000
Trading days | $	7
Maximum | SeriesA Convertible Preferred Stock
Class of Stock [Line Items]
Conversion of Preferred Stock, Conversion Blocker, Percent, Upon Giving Notice		19.99%
Maximum | Series B Convertible Preferred Stock
Class of Stock [Line Items]
Aggregate shares to be sold | shares	2,144,160
Preferred stock, par value (in dollars per share) | $ / shares	$ 0.0001
Shares issued | shares	1,200,000
Share price (in dollars per share) | $ / shares	$ 25
BVP | Common stock
Class of Stock [Line Items]
Conversion of stock, shares converted | shares		833,333
BVP | SeriesA Convertible Preferred Stock
Class of Stock [Line Items]
Preferred stock, par value (in dollars per share) | $ / shares		$ 0.0001
Shares issued on conversion | shares		1,000,000

Capital Stock - At-the market e

Capital Stock - At-the market equity offering program (Details) - Cantor - At-the-market equity offering program - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Class of Stock [Line Items]
Shares issued	0	1,964,448	244,209
Net proceeds from issuance of stock	$ 0

Stock-based compensation - Stoc

Stock-based compensation - Stock-Based Compensation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Stock-based compensation
Total stock-based compensation expense	$ 5,860	$ 6,047	$ 7,711
Research and development
Stock-based compensation
Total stock-based compensation expense	1,987	1,766	2,099
Selling, General And Administrative Expense [Member]
Stock-based compensation
Total stock-based compensation expense	$ 3,873	$ 4,281	$ 5,612

Stock-based compensation - Equi

Stock-based compensation - Equity Plans and Activity (Details)

1 Months Ended

12 Months Ended

36 Months Ended

72 Months Ended

Feb. 29, 2012 shares

Sep. 30, 2023 shares

Feb. 29, 2020 shares

Dec. 31, 2018 shares

Jun. 30, 2018 shares

Dec. 31, 2023 item shares

Dec. 31, 2017 shares

Dec. 31, 2016 shares

Dec. 31, 2018 shares

Dec. 31, 2018 shares

Dec. 31, 2021 shares

May 19, 2020 shares

Dec. 18, 2018 shares

Dec. 31, 2014 shares

Stock-based compensation

Number of Equity Compensation Plans | item

2

Stock options

Stock-based compensation

Granted (in shares)

1,177,750

Forfeited/cancelled (in shares)

62,831

Expired (in shares)

12,665

Restricted stock units

Stock-based compensation

Granted (in shares)

108,058

Forfeited (in shares)

5,477

Vested (in shares)

66,201

Inducement Award Program

Stock-based compensation

Number of shares reserved

62,500

Additional number of shares authorized for issuance

500,000

104,166

141,666

208,333

48,333

Shares available for future grants

482,667

Reduction of shares available for issuance

169,447

Inducement Award Program | Stock options

Stock-based compensation

Granted (in shares)

825,562

Forfeited/cancelled (in shares)

472,880

Expired (in shares)

1,997

Exercised (in shares)

48,663

Inducement Award Program | Restricted stock units

Stock-based compensation

Granted (in shares)

80,804

Vested (in shares)

30,128

Equity Incentive Plan 2021 [Member]

Stock-based compensation

Number of shares reserved

1,991,666

Shares available for future grants

693,645

Equity Incentive Plan 2021 [Member] | Stock options

Stock-based compensation

Granted (in shares)

1,398,762

Exercised (in shares)

0

Forfeited (in shares)

52,013

Equity Incentive Plan 2021 [Member] | Restricted stock units

Stock-based compensation

Granted (in shares)

269,349

Forfeited (in shares)

18,594

Vested (in shares)

80,367

2012 Plan

Stock-based compensation

Number of shares reserved

285,714

1,104,177

1,083,333

1,385,702

Additional number of shares authorized for issuance

2,508

107,412

Percentage of outstanding shares of common stock used to compute annual increase in number of shares reserved

4%

2012 Plan | Maximum

Stock-based compensation

Annual increase in number of shares reserved

107,412

2012 Plan | Stock options

Stock-based compensation

Granted (in shares)

1,841,188

Forfeited/cancelled (in shares)

814,357

Expired (in shares)

213,901

Exercised (in shares)

191,342

2012 Plan | Restricted stock units

Stock-based compensation

Granted (in shares)

556,432

Forfeited (in shares)

87,458

Vested (in shares)

455,878

Incentive Plan 2021 New Shares [Member]

Stock-based compensation

Number of shares reserved

887,489

Stock-based compensation - St_2

Stock-based compensation - Stock Options (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Additional disclosures
Stock-based compensation expense	$ 5,860	$ 6,047	$ 7,711
Stock options
Stock-based compensation
Expiration term	10 years
Shares
Outstanding at the beginning of the period (in shares)	1,168,105
Granted (in shares)	1,177,750
Forfeited/cancelled (in shares)	(62,831)
Expired	(12,665)
Outstanding at the end of the period (in shares)	2,270,359	1,168,105
Vested at the end of the period (in shares)		876,016
Weighted-average exercise price per share
Outstanding at the beginning of the period (in dollars per share)	$ 33.63
Granted (in dollars per share)	7.98
Forfeited/cancelled (in dollars per share)	35.38
Expired (in dollars per share)	117.12
Outstanding at the end of the period (in dollars per share)	$ 19.81	$ 33.63
Vested at the end of the period (in dollars per share)		$ 33.39
Weighted-average remaining contractual term
Outstanding at the end of the period	7 years 9 months 18 days	7 years 1 month 6 days
Vested at the end of the period		5 years 9 months 18 days
Aggregate intrinsic value
Outstanding at the beginning of the period (in dollars)	$ 18
Outstanding at the end of the period (in dollars)	559	$ 18
Vested at the end of the period (in dollars)		$ 138
Assumptions used to estimate fair value of each stock-based award on the grant date
Risk-free interest rate (as a percent)		3.77%	3.13%	1.15%
Volatility (as a percent)		92%	88%	89%
Dividend yield (as a percent)		0%	0%	0%
Expected term (years)		6 years 1 month 6 days	5 years 9 months 18 days	6 years
Additional disclosures
Stock-based compensation expense	$ 4,200	$ 4,200	$ 4,100
Weighted-average grant date fair value (in dollars per share)	$ 6.16	$ 8.28	$ 21.84
Fair value of vested stock options	$ 3,100	$ 4,400	$ 3,800
Aggregate intrinsic value of options exercised (in dollars)	0	$ 100	$ 800
Total unrecognized stock-based compensation expense (in dollars)	$ 9,200
Weighted-average recognition period	2 years 7 months 6 days
Stock options | One Year From Vesting
Stock-based compensation
Vesting percentage	25%
Vesting period	1 year
Stock options | Successive Three-Month Periods After One Year From Vesting
Stock-based compensation
Vesting percentage	6.25%
Vesting period	3 months

Stock-based compensation - Rest

Stock-based compensation - Restricted Stock (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($) tranche $ / shares shares	Dec. 31, 2022 USD ($) item $ / shares shares	Dec. 31, 2021 USD ($)
Additional disclosures
Stock-based compensation expense | $	$ 5,860	$ 6,047	$ 7,711
Restricted stock units
Stock-based compensation
Number of shares holder to receive when RSU vests	1
Shares
Outstanding at the beginning of the period (in shares)	172,909
Granted (in shares)	108,058
Vested (in shares)	(66,201)
Forfeited/cancelled (in shares)	(5,477)
Outstanding at the end of the period (in shares)	209,289	172,909
Weighted-average grant date fair value
Outstanding at the beginning of the period (in dollars per share) | $ / shares	$ 25.82
Granted (in dollars per share) | $ / shares	10.15
Vested (in dollars per share) | $ / shares	25.45
Forfeited/cancelled (in dollars per share) | $ / shares	17.96
Outstanding at the end of the period (in dollars per share) | $ / shares	$ 18.05	$ 25.82
Additional disclosures
Stock-based compensation expense | $	$ 1,600	$ 1,800	3,500
Fair value of shares vested | $	1,700	$ 2,300	$ 3,700
Unrecognized stock-based compensation expense | $	$ 3,100
Weighted-average recognition period	2 years 1 month 6 days
Restricted stock units | One Year From Vesting
Stock-based compensation
Number of anniversaries | item		1
Vesting percentage	25%
Vesting period	1 year
Restricted stock units | Successive Three-Month Periods After One Year From Vesting
Stock-based compensation
Vesting percentage	6.25%
Vesting period	3 months
Restricted stock units | One Year Anniversary
Stock-based compensation
Number of installments | tranche	2
Vesting percentage	50%
Vesting period	1 year
Restricted stock units | Within Two Years of Vesting Commencement
Stock-based compensation
Vesting percentage	100%
Vesting period	2 years

Stock-based compensation - Empl

Stock-based compensation - Employee Stock Purchase Plan (Details) $ in Thousands		12 Months Ended
	Dec. 18, 2018 item shares	Dec. 31, 2023 USD ($) shares	Dec. 31, 2022 USD ($) shares	Dec. 31, 2021 USD ($) shares
Stock-based compensation
Shares reserved for issuance | shares		13,672,000	4,147,000
Assumptions used to estimate fair value of each stock-based award on the grant date
Stock-based compensation expense | $		$ 5,860	$ 6,047	$ 7,711
Proceeds from the exercise of stock options and employee stock purchase program | $		$ 57	$ 282	$ 1,087
Employee Stock purchase plan
Stock-based compensation
Percent of common stock at market price to be purchased	85%
Number of vesting periods | item	2
Vesting period	6 months
Shares reserved for issuance | shares	166,666	75,000	89,000
Assumptions used to estimate fair value of each stock-based award on the grant date
Risk-free interest rate (as a percent)		5.16%	1.56%	0.07%
Volatility (as a percent)		126%	77%	68%
Expected term (years)		6 months	6 months	6 months
Stock-based compensation expense | $		$ 100	$ 100	$ 100
Issuance of common stock under ESPP | shares		14,270	10,194	9,172

Convertible Senior Notes - Sche

Convertible Senior Notes - Schedule of Notes Carrying Value (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Convertible Notes
Debt, carrying value	$ 40,000	$ 25,000
Amortization of debt discount and issuance costs	(230)	(179)	$ (9,199)
Convertible senior notes		275
2018 Notes principle balance
Convertible Notes
Debt, carrying value		300
Amortization of debt discount and issuance costs		(25)
Convertible senior notes		$ 275
2018 Notes, net
Convertible Notes
Debt, carrying value	$ 300

Convertible Senior Notes (Detai

Convertible Senior Notes (Details) - USD ($) $ / shares in Units, $ in Thousands					12 Months Ended
	Jul. 16, 2021	Dec. 23, 2019	Nov. 14, 2019	Oct. 17, 2018	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Oct. 31, 2023	Nov. 06, 2020
Convertible Notes
Common stock, par value (in dollars per share)					$ 0.0001	$ 0.0001
Other Nonoperating Income (Expenses)					$ (109)	$ 47
Notes outstanding					40,086	24,526
Debt, carrying value					40,000	25,000
2018 Notes principle balance
Convertible Notes
Debt, carrying value						$ 300
2018 Notes, net
Convertible Notes
Aggregate principal amount				$ 150,000					$ 28,000
Net proceeds				$ 145,300
Interest rate (as a percent)				5%		5%
Effective interest rate								15.65%
Debt Conversion, Original Debt, Amount		$ 7,400	$ 114,300
Repayments of Convertible Debt		$ 700	11,400
Interest expense					100
Debt, carrying value					$ 300
2019 Notes
Convertible Notes
Interest rate (as a percent)		5%
Debt Conversion, Converted Instrument, Amount		$ 4,000	$ 62,900
2020 Notes
Convertible Notes
Aggregate principal amount									$ 28,000
Interest rate (as a percent)									5%
Effective interest rate								20.31%
Debt Conversion, Converted Instrument, Amount	$ 28,000
Interest expense							$ 7,800
Debt Conversion, Converted Instrument, Shares Issued	717,949

Net loss per share - Potentiall

Net loss per share - Potentially dilutive securities were excluded from the calculation of diluted net loss per share (Details) - shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Net loss per share
Potentially dilutive securities were excluded from the calculation of diluted net loss per share (in shares)	7,557,026	2,184,710	1,597,222
Stock options
Net loss per share
Potentially dilutive securities were excluded from the calculation of diluted net loss per share (in shares)	2,270,359	1,168,105	1,355,220
Restricted stock units
Net loss per share
Potentially dilutive securities were excluded from the calculation of diluted net loss per share (in shares)	209,289	172,909	233,710
Employee Stock purchase plan
Net loss per share
Potentially dilutive securities were excluded from the calculation of diluted net loss per share (in shares)	7,475	6,874	4,803
Series A Preferred Stock
Net loss per share
Potentially dilutive securities were excluded from the calculation of diluted net loss per share (in shares)	833,333	833,333
Series B Preferred Stock
Net loss per share
Potentially dilutive securities were excluded from the calculation of diluted net loss per share (in shares)	4,236,570
2018 Notes, net | Convertible Common Stock [Member]
Net loss per share
Potentially dilutive securities were excluded from the calculation of diluted net loss per share (in shares)		3,489	3,489

Income Taxes - Operating Loss C

Income Taxes - Operating Loss Carryforwards (Details) $ in Millions	Dec. 31, 2023 USD ($)
Federal
Operating loss carryforwards
NOL carryforwards	$ 473.6
Operating loss carryforwards, indefinite period	277.9
State
Operating loss carryforwards
NOL carryforwards	$ 189

Income Taxes - Tax Credits (Det

Income Taxes - Tax Credits (Details) $ in Millions	Dec. 31, 2023 USD ($)
Federal
Tax credit carryforwards
Tax credits	$ 9.5
State
Tax credit carryforwards
Tax credits	$ 2.2

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Income Taxes and Deferred Tax Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Reconciliation of income taxes computed using the U.S. federal statutory rate
Income tax benefit using U.S. federal statutory rate (as a percent)	21%	21%
State tax benefit, net of federal benefit (as a percent)	2.82%	2.15%
Research and development tax credits (as a percent)	4.41%	2.81%
Stock-based compensation	(0.98%)	(2.17%)
Permanent items (as a percent)	0.44%	(0.08%)
Change in the valuation allowance (as a percent)	(21.17%)	(21.41%)
Tax law change (as a percent)	(4.31%)
NOL and tax credit expiration under Section 382 (as a percent)	(2.07%)	(2.26%)
Other (as a percent)	(0.14%)	(0.04%)
Deferred tax assets:
Net operating loss carryforwards	$ 110,152	$ 103,243
Capitalized research and development	20,356	11,621
Research and development credits	11,192	7,107
Stock-based compensation	3,340	3,450
Installment sale	6,909	7,768
Lease liability	311	538
Other deferred tax assets	346	587
Total deferred tax assets	152,606	134,314
Deferred tax liabilities:
Right-of-use asset	(248)	(425)
Debt Discount		(4)
Other deferred tax liability		(29)
Total deferred tax liabilities	(248)	(458)
Net deferred tax asset prior to valuation allowance	152,358	133,856
Valuation allowance	(152,358)	(133,856)
Net deferred tax asset		$ 0
Additional disclosures
Increase (decrease) in valuation allowance	18,500
Unrecognized tax benefits	0
Interest and penalties accrued related to unrecognized tax benefits	0
Liability for uncertain tax positions	$ 0
Federal
Additional disclosures
Capitalized Research and Development Expenses, Amortization Period	5 years
Foreign
Additional disclosures
Capitalized Research and Development Expenses, Amortization Period	15 years

Commitments and contingencies (

Commitments and contingencies (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Office and Laboratory Space in Needham, Massachusetts | Letter of credit | Restricted Cash and Cash Equivalents, Noncurrent [Member]
Property, Plant and Equipment [Line Items]
Security deposit	$ 0.2	$ 0.2

License, collaboration and co_3

License, collaboration and commercial agreements - Genfleet Therapeutics (Details) - USD ($) $ in Thousands		1 Months Ended	12 Months Ended
	Aug. 24, 2023	Sep. 30, 2020	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Research and development			$ 61,356	$ 50,558	$ 39,347
Term of agreement		1 year
Sale of COPIKTRA license and related assets
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue recognized				$ 2,596	1,447
Transition Services Revenue
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue recognized					$ 606
Genfleet
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments	$ 622,000
Number of days written prior notice required for other party to terminate agreement	90 days
Number of days written notice required to terminate agreement if fails to cure breach	60 days
License and Collaboration Agreement | Genfleet
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront payment	$ 2,000		2,000
License and Collaboration Agreement | Genfleet | Research and Development Arrangement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Genfleet R&D Support Fee	$ 1,500
Research and development			$ 200

License, collaboration and co_4

License, collaboration and commercial agreements - Secura (Details) $ in Thousands	1 Months Ended	12 Months Ended
	Sep. 30, 2020 USD ($)	Dec. 31, 2022 USD ($) item	Dec. 31, 2021 USD ($) item
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Term of agreement	1 year
Sale of COPIKTRA license and related assets
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue recognized		$ 2,596	$ 1,447
Transition Services Revenue
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue recognized			606
License and Collaboration Agreement | Secura
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront payment	$ 70,000
Milestone payments receivable upon approval of COPIKTRA	35,000
Milestone payments receivable upon approval for commercial sale	10,000
Threshold sales to trigger royalty payments	$ 100,000
Percentage of all royalty, milestone and sublicense revenue payments payable	50%
Percentage of all royalty and milestone payments payable under certain jurisdictions	50%
Future potential royalties expected to be received		100	200
License and Collaboration Agreement | Secura | Sale of COPIKTRA license and related assets
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Regulatory milestone payments		2,500	1,300
Revenue recognized		$ 2,600	$ 1,400
Number of regulatory milestone achieved | item		1	2
License and Collaboration Agreement | Secura | Transition Services Revenue
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue recognized			$ 600
License and Collaboration Agreement | Secura | Sales Exceeds $100 Million
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Sales milestone receivable	$ 10,000
Threshold sales to trigger milestone payments	100,000
License and Collaboration Agreement | Secura | Sales Exceeds $200 Million
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Sales milestone receivable	15,000
Threshold sales to trigger milestone payments	200,000
License and Collaboration Agreement | Secura | Sales Exceeds $300 Million
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Sales milestone receivable	25,000
Threshold sales to trigger milestone payments	300,000
License and Collaboration Agreement | Secura | Maximum
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Regulatory milestone payments	45,000
Sales milestone receivable	$ 50,000

License, collaboration and co_5

License, collaboration and commercial agreements - Secura - Contract asset (Details) - License and Collaboration Agreement $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Balance at the beginning of period	$ 96
Reclassification to receivable	(54)
Balance at the end of period	42
Secura
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Balance at the beginning of period	96
Reclassification to receivable	(54)
Balance at the end of period	$ 42

Notes Payable (Details)

Notes Payable (Details) - AFCO $ in Millions	1 Months Ended
	Feb. 28, 2023 USD ($)
Short-Term Debt [Line Items]
Aggregate principal amount	$ 1.4
Interest rate (as a percent)	7.40%
Monthly payments	$ 0.1
Note Payable	$ 0

Employee benefit plan (Details)

Employee benefit plan (Details) $ in Millions	36 Months Ended
	Dec. 31, 2023 USD ($)
Employee benefit plan
Contributions made under 401(k) plan	$ 0.8

Subsequent events (Details)

Subsequent events (Details)	Jan. 17, 2024 USD ($) shares	Jan. 24, 2023 USD ($) tranche $ / shares shares	Mar. 11, 2024 $ / shares shares
Series B preferred stock
Subsequent events
Number of tranches | tranche		2
Threshold share price		$ 31.77
Expected closing period of issuance		10 days
Series B preferred stock | Maximum
Subsequent events
Aggregate shares to be sold | shares		2,144,160
Preferred stock, par value (in dollars per share)		$ 0.0001
Shares issued | shares		1,200,000
Share price (in dollars per share)		$ 25
Series B preferred stock | Private placement
Subsequent events
Conversion price		$ 7.0812
Shares issued | shares		944,160
Share price (in dollars per share)		$ 9
Gross proceeds | $		$ 30,000,000
Share issue period		10 days
Trading days | $		7
Threshold share price		$ 13.50
Threshold trading volume | $		$ 25,000,000
Subsequent events | Option Exchange Program
Subsequent events
Number of eligible stockholders | $	42
Number of shares reserved | shares	603,330		603,330
Exercise price of new options			$ 11.44

Cash, cash equivalents and rest

Cash, cash equivalents and restricted cash (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Cash and cash equivalents	$ 77,909	$ 74,933
Restricted cash	241	241
Restricted cash	1,167	856
Total cash, cash equivalents and restricted cash	79,076	75,789	$ 21,493	$ 68,023
Prepaid Expenses and Other Current Assets
Property, Plant and Equipment [Line Items]
Restricted cash	900	$ 600
Letter of credit | Office and Laboratory Space in Needham, Massachusetts.
Property, Plant and Equipment [Line Items]
Restricted cash	$ 200

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pay vs Performance Disclosure
Net Income (Loss)	$ (87,367)	$ (73,812)	$ (71,200)

Insider Trading Arrangements

Insider Trading Arrangements	12 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

Uncategorized Items - vstm-2023

Label	Element	Value
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures	us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	$ (90,000)
Additional paid-in capital
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures	us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	$ (90,000)