Astria Therapeutics (ATXS) 10-Q 13 Nov 23 2023 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2023	Oct. 31, 2023
Document and Entity Information
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2023
Document Transition Report	false
Entity File Number	001-37467
Entity Registrant Name	Astria Therapeutics, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	26-3687168
Entity Address, Address Line One	75 State Street Suite 1400
Entity Address, City or Town	Boston
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02109
City Area Code	617
Local Phone Number	349-1971
Title of 12(b) Security	Common Stock, $0.001 par value per share
Trading Symbol	ATXS
Security Exchange Name	NASDAQ
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
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		36,296,191
Entity Central Index Key	0001454789
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3
Amendment Flag	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 119,806	$ 20,525
Short-term investments	69,000	205,912
Prepaid expenses and other current assets	2,660	1,253
Total current assets	191,466	227,690
Right-of-use asset	514	948
Other assets	1,881	1,995
Total assets	193,861	230,633
Current liabilities:
Accounts payable	1,138	788
Accrued expenses	7,756	7,690
Current portion of operating lease liabilities	488	582
Total current liabilities	9,382	9,060
Long term portion of operating lease liabilities		357
Total liabilities	9,382	9,417
Commitments (Note 6)
Stockholders' equity:
Common stock, $0.001 par value per share, 150,000,000 shares authorized; 28,042,296 and 27,501,340 shares issued and outstanding at September 30, 2023 and December 31, 2022, respectively	28	28
Additional paid-in capital	638,251	632,512
Accumulated other comprehensive loss		(79)
Accumulated deficit	(549,124)	(507,643)
Total stockholders' equity	184,479	221,216
Total liabilities and stockholders' equity	193,861	230,633
Preferred stock
Stockholders' equity:
Preferred stock
Series X redeemable convertible preferred stock
Stockholders' equity:
Preferred stock	$ 95,324	$ 96,398

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2023	Dec. 31, 2022
Preferred stock, par value (in dollars per share)	$ 0.001
Preferred stock, authorized	5,000,000
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, authorized	150,000,000	150,000,000
Common stock, issued	28,042,296	27,501,340
Common stock, outstanding	28,042,296	27,501,340
Preferred stock
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, authorized	4,908,620	4,908,620
Preferred stock, issued	0	0
Preferred stock, outstanding	0	0
Series X redeemable convertible preferred stock
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, authorized	91,380	91,380
Preferred stock, issued	31,107	31,455
Preferred stock, outstanding	31,107	31,455

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Operating expenses:
Research and development	$ 13,338	$ 7,698	$ 30,460	$ 24,673
General and administrative	6,898	4,688	18,371	14,540
Total operating expenses	20,236	12,386	48,831	39,213
Loss from operations	(20,236)	(12,386)	(48,831)	(39,213)
Other income (expense):
Interest and investment income	2,527	437	7,404	706
Other expense, net	(18)	(48)	(54)	(64)
Total other income, net	2,509	389	7,350	642
Net loss	$ (17,727)	$ (11,997)	$ (41,481)	$ (38,571)
Net loss per share attributable to common shareholders - basic	$ (0.63)	$ (0.87)	$ (1.48)	$ (2.91)
Net loss per share attributable to common shareholders - diluted	$ (0.63)	$ (0.87)	$ (1.48)	$ (2.91)
Weighted-average common shares outstanding used in net loss per share - basic	28,040,173	13,742,385	28,002,663	13,261,422
Weighted-average common shares outstanding used in net loss per share - diluted	28,040,173	13,742,385	28,002,663	13,261,422

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Condensed Consolidated Statements of Comprehensive Loss
Net loss	$ (17,727)	$ (11,997)	$ (41,481)	$ (38,571)
Other comprehensive gain (loss):
Unrealized gain (loss) on short-term investments, net of tax of $0		(29)	79	(215)
Total other comprehensive gain (loss):		(29)	79	(215)
Comprehensive loss	$ (17,727)	$ (12,026)	$ (41,402)	$ (38,786)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Comprehensive Loss (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Condensed Consolidated Statements of Comprehensive Loss
Unrealized gain (loss) on short-term investments, net of tax	$ 0	$ 0	$ 0	$ 0

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders' Equity - USD ($) $ in Thousands	Preferred stock Series X redeemable convertible preferred stock	Common stock	Additional paid-in capital	Accumulated deficit	Accumulated other comprehensive loss	Total
Beginning balance at Dec. 31, 2021	$ 96,398	$ 13	$ 481,709	$ (455,809)	$ 0	$ 122,311
Beginning balance (in shares) at Dec. 31, 2021	31,455	13,016,955
Increase (Decrease) in Shareholders' Equity
Expense related to warrants inherited in acquisition of Quellis			1,542			1,542
Stock-based compensation expense			1,209			1,209
Unrealized gain (loss) on short-term investments					(53)	(53)
Net loss				(15,324)		(15,324)
Ending balance at Mar. 31, 2022	$ 96,398	$ 13	484,460	(471,133)	(53)	109,685
Ending balance (in shares) at Mar. 31, 2022	31,455	13,016,955
Beginning balance at Dec. 31, 2021	$ 96,398	$ 13	481,709	(455,809)	0	122,311
Beginning balance (in shares) at Dec. 31, 2021	31,455	13,016,955
Increase (Decrease) in Shareholders' Equity
Net loss						(38,571)
Ending balance at Sep. 30, 2022	$ 96,398	$ 16	511,053	(494,380)	(215)	112,872
Ending balance (in shares) at Sep. 30, 2022	31,455	15,748,323
Beginning balance at Mar. 31, 2022	$ 96,398	$ 13	484,460	(471,133)	(53)	109,685
Beginning balance (in shares) at Mar. 31, 2022	31,455	13,016,955
Increase (Decrease) in Shareholders' Equity
Stock-based compensation expense			1,117			1,117
Unrealized gain (loss) on short-term investments					(133)	(133)
Net loss				(11,250)		(11,250)
Ending balance at Jun. 30, 2022	$ 96,398	$ 13	485,577	(482,383)	(186)	99,419
Ending balance (in shares) at Jun. 30, 2022	31,455	13,016,955
Increase (Decrease) in Shareholders' Equity
Issuance of common stock upon exercise of options			34			34
Issuance of common stock upon exercise of options (in shares)		16,202
Issuance of common stock for at-the-market offerings, net of issuance costs		$ 3	24,287			24,290
Issuance of common stock for at-the-market offerings, net of issuance costs (in shares)		2,715,166
Stock-based compensation expense			1,155			1,155
Unrealized gain (loss) on short-term investments					(29)	(29)
Net loss				(11,997)		(11,997)
Ending balance at Sep. 30, 2022	$ 96,398	$ 16	511,053	(494,380)	(215)	112,872
Ending balance (in shares) at Sep. 30, 2022	31,455	15,748,323
Beginning balance at Dec. 31, 2022	$ 96,398	$ 28	632,512	(507,643)	(79)	221,216
Beginning balance (in shares) at Dec. 31, 2022	31,455	27,501,340
Increase (Decrease) in Shareholders' Equity
Issuance of common stock upon the conversion of preferred stock	$ (1,074)		1,074
Issuance of common stock upon the conversion of preferred stock (shares)	(348)	57,910
Issuance of common stock upon exercise of options and warrants			37			37
Issuance of common stock upon exercise of options and warrants (in shares)		427,468
Stock-based compensation expense			1,220			1,220
Unrealized gain (loss) on short-term investments					75	75
Net loss				(11,188)		(11,188)
Ending balance at Mar. 31, 2023	$ 95,324	$ 28	634,843	(518,831)	(4)	211,360
Ending balance (in shares) at Mar. 31, 2023	31,107	27,986,718
Beginning balance at Dec. 31, 2022	$ 96,398	$ 28	632,512	(507,643)	(79)	221,216
Beginning balance (in shares) at Dec. 31, 2022	31,455	27,501,340
Increase (Decrease) in Shareholders' Equity
Net loss						(41,481)
Ending balance at Sep. 30, 2023	$ 95,324	$ 28	638,251	(549,124)		184,479
Ending balance (in shares) at Sep. 30, 2023	31,107	28,042,296
Beginning balance at Mar. 31, 2023	$ 95,324	$ 28	634,843	(518,831)	(4)	211,360
Beginning balance (in shares) at Mar. 31, 2023	31,107	27,986,718
Increase (Decrease) in Shareholders' Equity
Issuance of common stock upon exercise of options			273			273
Issuance of common stock upon exercise of options (in shares)		39,126
Stock-based compensation expense			1,331			1,331
Unrealized gain (loss) on short-term investments					$ 4	4
Net loss				(12,566)		(12,566)
Ending balance at Jun. 30, 2023	$ 95,324	$ 28	636,447	(531,397)		200,402
Ending balance (in shares) at Jun. 30, 2023	31,107	28,025,844
Increase (Decrease) in Shareholders' Equity
Issuance of common stock upon exercise of options			110			110
Issuance of common stock upon exercise of options (in shares)		16,452
Stock-based compensation expense			1,694			1,694
Net loss				(17,727)		(17,727)
Ending balance at Sep. 30, 2023	$ 95,324	$ 28	$ 638,251	$ (549,124)		$ 184,479
Ending balance (in shares) at Sep. 30, 2023	31,107	28,042,296

Condensed Consolidated Statem_5

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Operating activities
Net loss	$ (41,481)	$ (38,571)
Reconciliation of net loss to net cash used in operating activities:
Stock-based compensation expense	4,245	3,481
Net gain on warrants inherited in acquisition of Quellis		1,542
Right-of-use asset - operating lease	434
Other non-cash items	(52)	127
Changes in assets and liabilities:
Prepaid expenses and other assets	(1,318)	(468)
Lease liability - operating lease	(451)	24
Accounts payable	350	(766)
Accrued expenses	66	1,762
Net cash used in operating activities	(38,207)	(32,869)
Investing activities
Purchases of short-term investments	(1,216,423)	(217,564)
Sales and maturities of short-term investments	1,353,500	185,675
Purchases of property and equipment	(9)	(60)
Net cash provided by (used in) investing activities	137,068	(31,949)
Financing activities
Proceeds from at-the-market offering, net of issuance costs		24,290
Proceeds from exercise of stock options	420	34
Net cash provided by financing activities	420	24,324
Net increase (decrease) in cash, cash equivalents and restricted cash	99,281	(40,494)
Cash, cash equivalents and restricted cash, beginning of period	20,688	86,629
Cash, cash equivalents and restricted cash, end of period	119,969	46,135
Supplemental disclosure of non-cash transactions:
Conversion of Series X Preferred Stock into common stock	$ 1,074
Purchases of property and equipment in accounts payable and accrued liabilities		$ 31

Organization and Operations

Organization and Operations	9 Months Ended
	Sep. 30, 2023
Organization and Operations
Organization and Operations	1. Organization and Operations The Company Astria Therapeutics, Inc. (the “Company”), is a biopharmaceutical company focused on the discovery, development and commercialization of novel therapeutics for allergic and immunological diseases. The Company’s lead product candidate is STAR-0215, a potential best-in-class monoclonal antibody inhibitor of plasma kallikrein in clinical development for the treatment of hereditary angioedema (“HAE”), a rare, debilitating and potentially life-threatening disease. The Company’s second product candidate is STAR-0310, a monoclonal antibody OX40 antagonist that is in preclinical development for the treatment of atopic dermatitis (“AD”), an immune disorder associated with loss of skin barrier function and itching. The Company was incorporated in the State of Delaware on June 26, 2008. Liquidity On June 30, 2021, the Company entered into an Open Market Sale Agreement SM As of September 30, 2023, the Company had an accumulated deficit of $549.1 million and had available cash, cash equivalents and short-term investments of $188.8 million which the Company estimates are sufficient to sustain operations for at least twelve months from the issuance of these unaudited condensed consolidated financial statements. Subsequent to September 30, 2023, the Company closed an underwritten public offering of (i) 8,253,895 shares of the Company’s common stock and accompanying common stock warrants to purchase an aggregate of 6,190,418 shares of common stock and (ii), in lieu of common stock to certain investors, pre-funded warrants to purchase up to an aggregate of 1,571,093 shares of common stock and accompanying common stock warrants to purchase up to an aggregate of 1,178,320 shares of common stock for aggregate gross proceeds of approximately $64.0 million, before deducting underwriting discounts and commissions and other offering expenses (the “October 2023 Financing”). Each pre-funded warrant has an exercise price of $0.001 per share. Each common stock warrant has an exercise price of $8.025 per share. The Company has been primarily involved with research and development activities and has incurred operating losses and negative cash flows from operations since its inception. The Company has not generated any product revenues and has financed its operations primarily through public offerings and private placements of its equity securities. There can be no assurance that the Company will be able to obtain additional debt, equity or other financing or generate product revenues or revenues from collaborative partners, on terms acceptable to the Company, on a timely basis or at all. The failure of the Company to obtain sufficient funds on acceptable terms when needed could have a material adverse effect on the Company’s business, results of operations, and financial condition. The Company is subject to a number of risks similar to other life science companies, including, but not limited to, successful discovery and development of its drug candidates, raising additional capital, development by its competitors of new technological innovations, protection of proprietary technology and regulatory approval and market acceptance of the Company’s products. The Company anticipates that it will continue to incur significant operating losses for the next several years as it continues to develop its product candidates.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2023
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation and Principles of Consolidation The accompanying financial statements and the related disclosures are unaudited and have been prepared in accordance with United States generally accepted accounting principles (“U.S. GAAP”). Additionally, certain information and footnote disclosures normally included in the Company’s annual financial statements have been condensed or omitted from this report. Accordingly, these unaudited condensed consolidated financial statements should be read in conjunction with the financial statements as of and for the year ended December 31, 2022 and notes thereto included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2022 (the “2022 Annual Report on Form 10-K”). The unaudited condensed consolidated financial statements have been prepared on the same basis as the audited financial statements. In the opinion of the Company’s management, the accompanying unaudited condensed consolidated financial statements contain all adjustments, including those adjustments that are of a normal and recurring nature, which are necessary to fairly present the Company’s results for the interim periods presented. The results for the three and nine months ended September 30, 2023 are not necessarily indicative of the results for the year ending December 31, 2023 or for any future period. The accompanying unaudited condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries, Astria Securities Corporation and Quellis Biosciences, LLC, successor in interest to Quellis. All intercompany balances and transactions have been eliminated in consolidation. Use of Estimates The preparation of the Company’s unaudited condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the unaudited condensed consolidated financial statements and accompanying notes. Actual results could differ from such estimates. The Company utilizes certain estimates to record expenses relating to research and development contracts. These contract estimates, which are primarily related to the length of service of each contract and the amount of service provided as of each measurement date, are determined by the Company based on input from internal project management, as well as from the Company’s service providers. Net Loss Per Share Basic net loss per share is calculated by dividing net loss attributable to common stockholders by the weighted average shares outstanding during the period, without consideration for common stock equivalents. Diluted net loss per share is calculated by adjusting weighted average shares outstanding for the dilutive effect of common stock equivalents outstanding for the period, determined using the treasury-stock method. For purposes of the Company’s dilutive net loss per share calculation, preferred stock, stock options and warrants to purchase common stock were considered to be common stock equivalents but were excluded from the calculation of diluted net loss per share as their effect would be anti-dilutive; therefore, basic and diluted net loss per share were the same for all periods presented. The following common stock equivalents, including Series X Preferred Stock shown as common stock equivalents, were excluded from the calculation of diluted net loss per share for the periods indicated because including them would have had an anti-dilutive effect: ​ ​ ​ ​ ​ ​ ​ ​ Three and Nine Months Ended September 30, ​ 2023 2022 Series X Preferred Stock ​ 5,184,591 ​ 5,242,501 Stock options 3,321,448 2,237,948 Common stock warrants 331,858 1,530,176 ​ ​ 8,837,897 ​ 9,010,625 ​ Cash, Cash Equivalents and Restricted Cash Cash equivalents are short-term, highly liquid investments that are readily convertible into cash, with original maturities of three months or less and reverse repurchase agreements with a maturity period of one business day at the time of purchase. Cash equivalents are mainly comprised of money market accounts invested in U.S. Treasury securities, corporate debt securities, commercial paper and reverse repurchase agreements with a maturity period of one business day at the time of purchase. Restricted cash is comprised of deposits with a financial institution used to collateralize letters of credit related to the Company’s lease arrangements. Restricted cash is presented as a component of prepaid expenses and other current assets other long-term assets The reconciliation of cash, cash equivalents and restricted cash reported within the applicable condensed consolidated balance sheet that sum to the total of the same such amount shown in the condensed consolidated statement of cash flows is as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ 2023 2022 Cash and cash equivalents ​ $ 119,806 ​ $ 45,972 Restricted cash ​ ​ 163 ​ ​ 163 Total ​ $ 119,969 ​ $ 46,135 ​ Preferred Stock Discount In February 2021, the Company issued Series X Preferred Stock in a private placement transaction. It was determined that this transaction resulted in recognition of a beneficial conversion feature, which was valued based on the difference between the price of the shares of common stock on the date of commitment and the conversion price on the closing date, resulting in a total value of $19.6 million. Additionally, the Company incurred total issuance costs of $5.7 million related to the private placement. Both of these features were recorded as a discount on Series X Preferred Stock recognized at the close of the transaction. These features are analogous to preferred dividends and are recorded as a non-cash return to holders of Series X Preferred Stock through additional paid in capital. The discount related to the beneficial conversion feature was recognized through the earliest possible date of conversion, which occurred in June 2021. The issuance costs are recognized as a dividend at the time of conversion to shares of common stock. As of September 30, 2023, $24.4 million of the above amounts were accounted for as a non-cash dividend related to shares of Series X Preferred Stock, and $0.9 million remained to be recognized upon future conversion. Recent Accounting Pronouncements - Adopted From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”) or other standard setting bodies and adopted by the Company as of the specified effective date. In June 2016, the FASB issued Accounting Standards Update 2016-13, Financial Instruments-Credit Losses Recent Accounting Pronouncements – Not Yet Adopted In August 2020, the FASB issued Accounting Standards Update 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) Summary of Significant Accounting Policies The Company’s significant accounting policies are described in Note 2, “ Summary of Significant Accounting Policies

Financial Instruments

Financial Instruments	9 Months Ended
	Sep. 30, 2023
Financial Instruments
Financial Instruments	3. Financial Instruments The tables below present information about the Company’s assets and liabilities that are measured at fair value on a recurring basis as of September 30, 2023 and December 31, 2022, and indicate the fair value hierarchy of the valuation techniques the Company utilized to determine such fair value. In general, fair values determined by Level 1 inputs utilize observable inputs such as quoted prices in active markets for identical assets or liabilities. Fair values determined by Level 2 inputs utilize data points that are either directly or indirectly observable, such as quoted prices, interest rates and yield curves. Fair values determined by Level 3 inputs utilize unobservable data points for which there is little or no market data, which require the Company to develop its own assumptions for the asset or liability. There were no transfers between fair value measurement levels during the three and nine months ended September 30, 2023 and 2022. The Company’s investment portfolio may include fixed income securities that do not always trade on a daily basis. As a result, the pricing services used by the Company apply other available information as applicable through processes such as benchmark yields, benchmarking of like securities, sector groupings and matrix pricing to prepare valuations. The Company validates the prices provided by its third party pricing services by obtaining market values from other pricing sources and analyzing pricing data in certain instances. The Company also invests in certain reverse repurchase agreements which are collateralized by deposits in the form of U.S. Government Securities and Obligations for an amount no less than 102% of their value. The Company does not record an asset or liability for the collateral as the Company is not permitted to sell or re-pledge the collateral. The collateral has at least the prevailing credit rating of U.S. Government Treasuries and Agencies. The Company utilized a third-party custodian to manage the exchange of funds and ensure that collateral received is maintained at 102% of the value of the reverse repurchase agreements on a daily basis. The Company accounted for warrants to purchase its stock pursuant to Accounting Standards Codification (“ASC”) Topic 470, Debt Distinguishing Liabilities from Equity Below is a summary of assets and liabilities measured at fair value on a recurring basis (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of September 30, 2023 ​ ​ Quoted ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Prices ​ Significant ​ Significant ​ ​ ​ ​ in Active ​ Observable ​ Unobservable ​ ​ ​ ​ Markets ​ Inputs ​ Inputs ​ ​ ​ (Level 1) (Level 2) (Level 3) Total Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ $ 3,876 ​ $ — ​ $ — ​ $ 3,876 Short-term investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Reverse repurchase agreements ​ ​ — ​ ​ 69,000 ​ ​ — ​ ​ 69,000 Total ​ $ 3,876 ​ $ 69,000 ​ $ — ​ $ 72,876 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2022 ​ ​ Quoted ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Prices ​ Significant ​ Significant ​ ​ ​ ​ in Active ​ Observable ​ Unobservable ​ ​ ​ ​ Markets ​ Inputs ​ Inputs ​ ​ ​ (Level 1) (Level 2) (Level 3) Total Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ $ 1,944 ​ $ — ​ $ — ​ $ 1,944 Short-term investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate debt securities ​ ​ — ​ ​ 16,445 ​ ​ — ​ ​ 16,445 Yankee securities ​ ​ — ​ ​ 1,999 ​ ​ — ​ ​ 1,999 Bonds ​ ​ — ​ ​ 2,988 ​ ​ — ​ ​ 2,988 Treasury bills ​ ​ 5,980 ​ ​ — ​ ​ — ​ ​ 5,980 Reverse repurchase agreements ​ ​ — ​ ​ 178,500 ​ ​ — ​ ​ 178,500 Total ​ $ 7,924 ​ $ 199,932 ​ $ — ​ $ 207,856 ​ The carrying amounts reflected in the unaudited condensed consolidated balance sheets for cash, prepaid expenses and other current assets, accounts payable and accrued expenses approximate their fair values due to the short-term nature of these assets and liabilities. Items measured at fair value on a recurring basis include cash equivalents and short-term investments as of September 30, 2023 and December 31, 2022.

Short-Term Investments

Short-Term Investments	9 Months Ended
	Sep. 30, 2023
Short-Term Investments
Short-Term Investments	4. Short-Term Investments The following table summarizes the short-term investments held at September 30, 2023 and December 31, 2022 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross Unrealized Gross Unrealized ​ ​ ​ ​ Amortized Cost ​ Gains ​ Losses ​ Fair Value September 30, 2023 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Reverse repurchase agreements ​ $ 69,000 ​ $ — ​ $ — ​ $ 69,000 Total ​ $ 69,000 ​ $ — ​ $ — ​ $ 69,000 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross Unrealized ​ Gross Unrealized ​ ​ ​ ​ Amortized Cost Gains Losses Fair Value December 31, 2022 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate debt securities ​ $ 16,508 ​ $ — ​ $ (63) ​ $ 16,445 Treasury bills ​ ​ 5,983 ​ ​ — ​ ​ (3) ​ ​ 5,980 Yankee securities ​ ​ 2,000 ​ ​ — ​ ​ (1) ​ ​ 1,999 U.S. agency bonds ​ ​ 3,000 ​ ​ — ​ ​ (12) ​ ​ 2,988 Reverse repurchase agreements ​ ​ 178,500 ​ ​ — ​ ​ — ​ ​ 178,500 Total ​ $ 205,991 ​ $ — ​ $ (79) ​ $ 205,912 ​ The contractual maturities of all short-term investments held at September 30, 2023 and December 31, 2022 were one year or less. There were no short-term investments in an unrealized loss position as of September 30, 2023. There were 16 short-term investments in an unrealized loss position with an aggregate value of $25.6 million as of December 31, 2022. These investments were in a loss position for less than 12 months and the Company considered the loss to be temporary in nature. The Company considered the decline in market value for these securities to be primarily attributable to economic and market conditions. ​ Gross realized gains and losses on the sales of short-term investments are included in other income, net. Unrealized holding gains or losses for the period that have been included in accumulated other comprehensive income, as well as gains and losses reclassified out of accumulated other comprehensive income into other income, net, were not material to the Company’s condensed consolidated statements of operations. The cost of investments sold or the amount reclassified out of the accumulated other comprehensive income into other income, net is based on the specific identification method for purposes of recording realized gains and losses. All proceeds in the three and nine month periods ended September 30, 2023 and 2022 related to maturities of underlying investments. The gains on proceeds from maturities of short-term investments were not material to the Company’s condensed consolidated statements of operations for the three and nine months ended September 30, 2023 and 2022.

Accrued Expenses

Accrued Expenses	9 Months Ended
	Sep. 30, 2023
Accrued Expenses
Accrued Expenses	5. Accrued Expenses Accrued expenses consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ 2023 2022 Accrued contracted costs ​ $ 2,863 ​ $ 2,822 Accrued compensation ​ ​ 2,671 ​ ​ 3,373 Accrued professional fees ​ ​ 1,891 ​ ​ 588 Accrued other ​ ​ 331 ​ ​ 407 Accrued milestones ​ ​ — ​ ​ 500 Total ​ $ 7,756 ​ $ 7,690 ​

Commitments

Commitments	9 Months Ended
	Sep. 30, 2023
Commitments
Commitments	6. Commitments On January 28, 2022, the Company entered into a sublease agreement (the “Sublease”) with Grant Thornton LLP for new office space to replace its existing office space. The Sublease commenced on May 1, 2022 and will end on July 31, 2024 (or on such earlier date as the term may cease or expire as set forth in the Sublease). Future minimum payments required under the Company’s Sublease as of September 30, 2023 are summarized as follows (in thousands): ​ ​ ​ ​ Period Ending December 31, Amount 2023 ​ $ 112 2024 ​ ​ 395 Total lease payments ​ $ 507 Less: imputed interest ​ $ (19) Total operating lease liabilities ​ $ 488 ​ Rent expense was $0.2 million and $0.2 million for the three months ended September 30, 2023 and 2022, respectively. Rent expense was $0.5 million and $0.7 million for the nine months ended September 30, 2023 and 2022, respectively. Lease payments were $0.2 million and $0.2 million for the three months ended September 30, 2023 and 2022, respectively. Lease payments were $0.5 million and $0.7 million for the nine months ended September 30, 2023 and 2022, respectively.

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2023
Stockholders' Equity
Stockholders' Equity	7. Stockholders’ Equity Preferred Stock Under the Company’s Restated Certificate of Incorporation, the Company has 5,000,000 shares of preferred stock authorized for issuance, with a $0.001 par value per share. Preferred stock may be issued from time to time in one or more series, each series to have such terms as stated or expressed in the resolutions providing for the issue of such series adopted by the Board of Directors of the Company. Preferred stock which may be redeemed, purchased or acquired by the Company may be reissued except as otherwise provided by law. ​ In January 2021, the Company entered into a Stock Purchase Agreement (the “Purchase Agreement”) with certain institutional and accredited investors. Pursuant to the Purchase Agreement, the Company sold an aggregate of 35,573 shares of Series X Preferred Stock for gross proceeds of approximately $110.0 million, and net proceeds of $104.3 million. Each share of Series X Preferred Stock is convertible into 166.67 shares of common stock. On January 3, 2023, a holder of Series X Preferred Stock elected to convert 348 shares of Series X Preferred Stock into 57,910 shares of common stock. As of September 30, 2023, the Company had 31,107 shares of Series X Preferred Stock outstanding and the number of shares of underlying common stock issuable upon conversion of the Series X Preferred Stock was 5,184,591. Outstanding Warrants The following table presents information about warrants that are issued and outstanding at September 30, 2023: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Issued Equity Instrument Warrants Outstanding Exercise Price Date of Expiration 2019 Common Stock ​ 331,858 ​ $ 37.50 2/7/2024 Total ​ ​ 331,858 ​ ​ ​ Weighted average exercise price ​ ​ ​ ​ ​ $ 37.50 ​ Weighted average life in years ​ ​ ​ ​ ​ 0.36 ​

Reserved for Future Issuance

Reserved for Future Issuance	9 Months Ended
	Sep. 30, 2023
Reserved for Future Issuance
Reserved for Future Issuance	8. Reserved for Future Issuance The Company has reserved for future issuance the following shares of common stock: ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ 2023 2022 Series X Preferred Stock ​ 5,184,591 ​ 5,242,501 Reserve under the 2015 Amended and Restated Stock Incentive Plan and the 2022 Inducement Stock Incentive Plan 4,566,822 1,013,520 Options outstanding to purchase common stock 3,321,448 2,253,431 Warrants for the purchase of common stock ​ 331,858 ​ 1,530,176 Shares reserved for the employee stock purchase plan 43,060 ​ 36,982 Total 13,447,779 10,076,610 ​

Stock Incentive Plans

Stock Incentive Plans	9 Months Ended
	Sep. 30, 2023
Stock Incentive Plans
Stock Incentive Plans	9. Stock Incentive Plans A summary of the Company’s stock option activity and related information follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ ​ ​ ​ ​ Average ​ Aggregate ​ ​ ​ ​ Weighted- ​ Remaining ​ Intrinsic ​ ​ ​ ​ Average ​ Contractual ​ Value ​ Shares Exercise Price Term (years) (in thousands) Outstanding at December 31, 2022 2,253,431 ​ $ 15.43 8.57 ​ $ 9,733 Granted 1,657,550 ​ $ 12.62 ​ ​ ​ ​ ​ Exercised ​ (78,050) ​ $ 5.37 ​ ​ ​ ​ ​ Cancelled or forfeited (510,960) ​ $ 16.96 ​ ​ ​ ​ ​ Expired ​ (523) ​ $ 138.60 ​ ​ ​ ​ ​ Outstanding at September 30, 2023 ​ 3,321,448 ​ $ 14.01 ​ 8.55 ​ $ 1,436 Vested and exercisable at September 30, 2023 ​ 994,708 ​ $ 19.38 ​ 7.63 ​ $ 662 Vested and expected to vest at September 30, 2023 3,321,448 ​ $ 14.01 ​ 8.55 ​ $ 1,436 ​ The intrinsic value of stock options exercised in the three and nine months ended September 30, 2023 was less than $0.1 million and $0.5 million, respectively. The intrinsic value of stock options exercised was $0.1 million in both the three and nine months ended September 30, 2022. The total grant date fair value of stock options vested for the three months ended September 30, 2023 and 2022 was $0.9 million and $0.9 million, respectively. The total grant date fair value of stock options vested for the nine months ended September 30, 2023 and 2022 was $3.6 million and $4.7 million, respectively. The weighted-average grant date fair value per share of options granted to employees and non-employees for the three months ended September 30, 2023 and 2022 was $5.89 and $2.54, respectively. The weighted-average grant date fair value per share of options granted to employees and non-employees for the nine months ended September 30, 2023 and 2022 was $7.48 and $3.66, respectively. At September 30, 2023, the total unrecognized compensation expense related to unvested stock option awards was $14.6 million. The Company expects to recognize that cost over a weighted-average period of approximately 2.8 years. On February 1, 2023, the Company issued stock options exercisable for 855,000 shares of common stock to certain officers of the Company subject to stockholder approval of the authorization of additional shares of common stock for issuance under the Company’s 2015 Amended and Restated Stock Incentive Plan on or before January 31, 2024. On June 2, 2023, the Company’s stockholders approved the addition of 4,300,000 shares of common stock to the shares of common stock authorized for issuance under this plan, which satisfied the grant condition on such officer grants. As of September 30, 2023, 755,000 of these options remain outstanding. On February 17, 2022, the Company’s Board of Directors adopted the 2022 Inducement Stock Incentive Plan (the “Inducement Plan”). The Inducement Plan provides for the grant of nonstatutory stock options, stock appreciation rights, restricted stock, restricted stock units and other stock-based awards with respect to an aggregate of 300,000 shares of the Company’s common stock. On January 31, 2023, the Company’s Board of Directors approved an amendment to the Inducement Plan to increase the number of shares of common stock authorized for issuance thereunder from 300,000 shares of common stock to 700,000 shares of common stock. Awards under the Inducement Plan may only be granted to persons who (a) were not previously an employee or director of the Company or (b) are commencing employment with the Company following a bona fide period of non-employment, in either case as an inducement material to the individual’s entering into employment with the Company and in accordance with the requirements of Nasdaq Stock Market Rule 5635(c)(4). As of September 30, 2023, options to purchase 538,100 shares of common stock have been granted under the Inducement Plan, which are included in the table above.

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2023
Subsequent Events
Subsequent Events	10. Subsequent Events On October 4, 2023, the Company entered into a license agreement with Ichnos Sciences SA and Ichnos Sciences Inc. (collectively “Ichnos”) pursuant to which Ichnos granted to the Company an exclusive (even as to Ichnos and its affiliates), worldwide, and sublicensable right and license to certain patent rights and related know-how, or collectively the Licensed Intellectual Property, to develop, manufacture, and commercialize Ichnos’ proprietary OX40 portfolio. The OX40 portfolio includes Ichnos’ proprietary OX40 antagonist monoclonal antibody, with the generic name telazorlimab and also referred to by Ichnos as “ISB 830” as well as Ichnos’ proprietary affinity matured next generation OX40 antagonist monoclonal antibody referred to by Ichnos as “ISB 830-X8” and referred to by the Company as “STAR-0310 candidate” (collectively, the “Licensed Compounds”). The Company agreed to use commercially reasonable efforts to develop, obtain regulatory approval for, and commercialize at least one product that contains or comprises a Licensed Compound (a “Licensed Product”) in the United States, France, Germany, Italy, Spain, the United Kingdom and Japan. Under the terms of the license agreement, the Company paid Ichnos a one-time upfront license fee of $15.0 million in October 2023. The Company is obligated to pay Ichnos up to $305.0 million in milestones, consisting of up to $20.0 million upon the achievement of certain development milestones, up to $70.0 million upon the achievement of certain regulatory milestones and up to $215.0 million upon achievement of certain commercial milestones, in each case in up to three indications with respect to the first applicable Licensed Product to achieve such milestone events. The Company is also obligated to pay Ichnos tiered royalties ranging from a mid-single-digit percentage to a low double-digit percentage on aggregate annual net sales of all Licensed Products. The Company is obligated to pay royalties on a Licensed Product-by-Licensed Product and country-by-country basis until the latest of: (i) the expiration of the last valid claim covering the composition of matter of such Licensed Product in such country; (ii) the expiration of the last regulatory exclusivity with respect to such Licensed Product in such country; and (iii) twelve years following the first commercial sale of such Licensed Product in such country. The royalty rate is subject to reduction on a Licensed Product-by-Licensed Product and country-by-country basis under certain circumstances. On October 16, 2023, the Company closed the October 2023 Financing.

Summary of Significant Accoun_2

Summary of Significant Accounting Polices (Polices)	9 Months Ended
	Sep. 30, 2023
Summary of Significant Accounting Policies
Basis of Presentation and Principles of Consolidation	Basis of Presentation and Principles of Consolidation The accompanying financial statements and the related disclosures are unaudited and have been prepared in accordance with United States generally accepted accounting principles (“U.S. GAAP”). Additionally, certain information and footnote disclosures normally included in the Company’s annual financial statements have been condensed or omitted from this report. Accordingly, these unaudited condensed consolidated financial statements should be read in conjunction with the financial statements as of and for the year ended December 31, 2022 and notes thereto included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2022 (the “2022 Annual Report on Form 10-K”). The unaudited condensed consolidated financial statements have been prepared on the same basis as the audited financial statements. In the opinion of the Company’s management, the accompanying unaudited condensed consolidated financial statements contain all adjustments, including those adjustments that are of a normal and recurring nature, which are necessary to fairly present the Company’s results for the interim periods presented. The results for the three and nine months ended September 30, 2023 are not necessarily indicative of the results for the year ending December 31, 2023 or for any future period. The accompanying unaudited condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries, Astria Securities Corporation and Quellis Biosciences, LLC, successor in interest to Quellis. All intercompany balances and transactions have been eliminated in consolidation.
Use of Estimates	Use of Estimates The preparation of the Company’s unaudited condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the unaudited condensed consolidated financial statements and accompanying notes. Actual results could differ from such estimates. The Company utilizes certain estimates to record expenses relating to research and development contracts. These contract estimates, which are primarily related to the length of service of each contract and the amount of service provided as of each measurement date, are determined by the Company based on input from internal project management, as well as from the Company’s service providers.
Net Loss Per Share	Net Loss Per Share Basic net loss per share is calculated by dividing net loss attributable to common stockholders by the weighted average shares outstanding during the period, without consideration for common stock equivalents. Diluted net loss per share is calculated by adjusting weighted average shares outstanding for the dilutive effect of common stock equivalents outstanding for the period, determined using the treasury-stock method. For purposes of the Company’s dilutive net loss per share calculation, preferred stock, stock options and warrants to purchase common stock were considered to be common stock equivalents but were excluded from the calculation of diluted net loss per share as their effect would be anti-dilutive; therefore, basic and diluted net loss per share were the same for all periods presented. The following common stock equivalents, including Series X Preferred Stock shown as common stock equivalents, were excluded from the calculation of diluted net loss per share for the periods indicated because including them would have had an anti-dilutive effect: ​ ​ ​ ​ ​ ​ ​ ​ Three and Nine Months Ended September 30, ​ 2023 2022 Series X Preferred Stock ​ 5,184,591 ​ 5,242,501 Stock options 3,321,448 2,237,948 Common stock warrants 331,858 1,530,176 ​ ​ 8,837,897 ​ 9,010,625 ​
Cash, Cash Equivalents and Restricted Cash	Cash, Cash Equivalents and Restricted Cash Cash equivalents are short-term, highly liquid investments that are readily convertible into cash, with original maturities of three months or less and reverse repurchase agreements with a maturity period of one business day at the time of purchase. Cash equivalents are mainly comprised of money market accounts invested in U.S. Treasury securities, corporate debt securities, commercial paper and reverse repurchase agreements with a maturity period of one business day at the time of purchase. Restricted cash is comprised of deposits with a financial institution used to collateralize letters of credit related to the Company’s lease arrangements. Restricted cash is presented as a component of prepaid expenses and other current assets other long-term assets The reconciliation of cash, cash equivalents and restricted cash reported within the applicable condensed consolidated balance sheet that sum to the total of the same such amount shown in the condensed consolidated statement of cash flows is as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ 2023 2022 Cash and cash equivalents ​ $ 119,806 ​ $ 45,972 Restricted cash ​ ​ 163 ​ ​ 163 Total ​ $ 119,969 ​ $ 46,135 ​
Preferred Stock Discount	Preferred Stock Discount In February 2021, the Company issued Series X Preferred Stock in a private placement transaction. It was determined that this transaction resulted in recognition of a beneficial conversion feature, which was valued based on the difference between the price of the shares of common stock on the date of commitment and the conversion price on the closing date, resulting in a total value of $19.6 million. Additionally, the Company incurred total issuance costs of $5.7 million related to the private placement. Both of these features were recorded as a discount on Series X Preferred Stock recognized at the close of the transaction. These features are analogous to preferred dividends and are recorded as a non-cash return to holders of Series X Preferred Stock through additional paid in capital. The discount related to the beneficial conversion feature was recognized through the earliest possible date of conversion, which occurred in June 2021. The issuance costs are recognized as a dividend at the time of conversion to shares of common stock. As of September 30, 2023, $24.4 million of the above amounts were accounted for as a non-cash dividend related to shares of Series X Preferred Stock, and $0.9 million remained to be recognized upon future conversion.
Recent Accounting Pronouncements - Adopted	Recent Accounting Pronouncements - Adopted From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”) or other standard setting bodies and adopted by the Company as of the specified effective date. In June 2016, the FASB issued Accounting Standards Update 2016-13, Financial Instruments-Credit Losses
Recent Accounting Pronouncements - Not Yet Adopted	Recent Accounting Pronouncements – Not Yet Adopted In August 2020, the FASB issued Accounting Standards Update 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)
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies The Company’s significant accounting policies are described in Note 2, “ Summary of Significant Accounting Policies

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2023
Summary of Significant Accounting Policies
Schedule of anti-dilutive common stock equivalents excluded from the calculation of diluted net loss per share	​ ​ ​ ​ ​ ​ ​ ​ Three and Nine Months Ended September 30, ​ 2023 2022 Series X Preferred Stock ​ 5,184,591 ​ 5,242,501 Stock options 3,321,448 2,237,948 Common stock warrants 331,858 1,530,176 ​ ​ 8,837,897 ​ 9,010,625
Schedule of condensed consolidated statement of cash flows	The reconciliation of cash, cash equivalents and restricted cash reported within the applicable condensed consolidated balance sheet that sum to the total of the same such amount shown in the condensed consolidated statement of cash flows is as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ 2023 2022 Cash and cash equivalents ​ $ 119,806 ​ $ 45,972 Restricted cash ​ ​ 163 ​ ​ 163 Total ​ $ 119,969 ​ $ 46,135 ​

Financial Instruments (Tables)

Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2023
Financial Instruments
Schedule of assets and liabilities measured fair value on a recurring basis	Below is a summary of assets and liabilities measured at fair value on a recurring basis (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of September 30, 2023 ​ ​ Quoted ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Prices ​ Significant ​ Significant ​ ​ ​ ​ in Active ​ Observable ​ Unobservable ​ ​ ​ ​ Markets ​ Inputs ​ Inputs ​ ​ ​ (Level 1) (Level 2) (Level 3) Total Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ $ 3,876 ​ $ — ​ $ — ​ $ 3,876 Short-term investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Reverse repurchase agreements ​ ​ — ​ ​ 69,000 ​ ​ — ​ ​ 69,000 Total ​ $ 3,876 ​ $ 69,000 ​ $ — ​ $ 72,876 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2022 ​ ​ Quoted ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Prices ​ Significant ​ Significant ​ ​ ​ ​ in Active ​ Observable ​ Unobservable ​ ​ ​ ​ Markets ​ Inputs ​ Inputs ​ ​ ​ (Level 1) (Level 2) (Level 3) Total Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ $ 1,944 ​ $ — ​ $ — ​ $ 1,944 Short-term investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate debt securities ​ ​ — ​ ​ 16,445 ​ ​ — ​ ​ 16,445 Yankee securities ​ ​ — ​ ​ 1,999 ​ ​ — ​ ​ 1,999 Bonds ​ ​ — ​ ​ 2,988 ​ ​ — ​ ​ 2,988 Treasury bills ​ ​ 5,980 ​ ​ — ​ ​ — ​ ​ 5,980 Reverse repurchase agreements ​ ​ — ​ ​ 178,500 ​ ​ — ​ ​ 178,500 Total ​ $ 7,924 ​ $ 199,932 ​ $ — ​ $ 207,856

Short-Term Investments (Tables)

Short-Term Investments (Tables)	9 Months Ended
	Sep. 30, 2023
Short-Term Investments
Schedule of the short-term investments	The following table summarizes the short-term investments held at September 30, 2023 and December 31, 2022 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross Unrealized Gross Unrealized ​ ​ ​ ​ Amortized Cost ​ Gains ​ Losses ​ Fair Value September 30, 2023 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Reverse repurchase agreements ​ $ 69,000 ​ $ — ​ $ — ​ $ 69,000 Total ​ $ 69,000 ​ $ — ​ $ — ​ $ 69,000 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross Unrealized ​ Gross Unrealized ​ ​ ​ ​ Amortized Cost Gains Losses Fair Value December 31, 2022 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate debt securities ​ $ 16,508 ​ $ — ​ $ (63) ​ $ 16,445 Treasury bills ​ ​ 5,983 ​ ​ — ​ ​ (3) ​ ​ 5,980 Yankee securities ​ ​ 2,000 ​ ​ — ​ ​ (1) ​ ​ 1,999 U.S. agency bonds ​ ​ 3,000 ​ ​ — ​ ​ (12) ​ ​ 2,988 Reverse repurchase agreements ​ ​ 178,500 ​ ​ — ​ ​ — ​ ​ 178,500 Total ​ $ 205,991 ​ $ — ​ $ (79) ​ $ 205,912 ​

Accrued Expenses (Tables)

Accrued Expenses (Tables)	9 Months Ended
	Sep. 30, 2023
Accrued Expenses
Schedule of accrued expenses	Accrued expenses consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ 2023 2022 Accrued contracted costs ​ $ 2,863 ​ $ 2,822 Accrued compensation ​ ​ 2,671 ​ ​ 3,373 Accrued professional fees ​ ​ 1,891 ​ ​ 588 Accrued other ​ ​ 331 ​ ​ 407 Accrued milestones ​ ​ — ​ ​ 500 Total ​ $ 7,756 ​ $ 7,690 ​

Commitments (Tables)

Commitments (Tables)	9 Months Ended
	Sep. 30, 2023
Commitments
Schedule of future minimum payments required under the Company's Sublease agreement	Future minimum payments required under the Company’s Sublease as of September 30, 2023 are summarized as follows (in thousands): ​ ​ ​ ​ Period Ending December 31, Amount 2023 ​ $ 112 2024 ​ ​ 395 Total lease payments ​ $ 507 Less: imputed interest ​ $ (19) Total operating lease liabilities ​ $ 488

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2023
Stockholders' Equity
Schedule of warrants issued and outstanding	The following table presents information about warrants that are issued and outstanding at September 30, 2023: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Issued Equity Instrument Warrants Outstanding Exercise Price Date of Expiration 2019 Common Stock ​ 331,858 ​ $ 37.50 2/7/2024 Total ​ ​ 331,858 ​ ​ ​ Weighted average exercise price ​ ​ ​ ​ ​ $ 37.50 ​ Weighted average life in years ​ ​ ​ ​ ​ 0.36 ​

Reserved for Future Issuance (T

Reserved for Future Issuance (Tables)	9 Months Ended
	Sep. 30, 2023
Reserved for Future Issuance
Reserved for Future Issuance	​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ 2023 2022 Series X Preferred Stock ​ 5,184,591 ​ 5,242,501 Reserve under the 2015 Amended and Restated Stock Incentive Plan and the 2022 Inducement Stock Incentive Plan 4,566,822 1,013,520 Options outstanding to purchase common stock 3,321,448 2,253,431 Warrants for the purchase of common stock ​ 331,858 ​ 1,530,176 Shares reserved for the employee stock purchase plan 43,060 ​ 36,982 Total 13,447,779 10,076,610 ​

Stock Incentive Plans (Tables)

Stock Incentive Plans (Tables)	9 Months Ended
	Sep. 30, 2023
Stock Incentive Plans
Schedule of stock option activity	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ ​ ​ ​ ​ Average ​ Aggregate ​ ​ ​ ​ Weighted- ​ Remaining ​ Intrinsic ​ ​ ​ ​ Average ​ Contractual ​ Value ​ Shares Exercise Price Term (years) (in thousands) Outstanding at December 31, 2022 2,253,431 ​ $ 15.43 8.57 ​ $ 9,733 Granted 1,657,550 ​ $ 12.62 ​ ​ ​ ​ ​ Exercised ​ (78,050) ​ $ 5.37 ​ ​ ​ ​ ​ Cancelled or forfeited (510,960) ​ $ 16.96 ​ ​ ​ ​ ​ Expired ​ (523) ​ $ 138.60 ​ ​ ​ ​ ​ Outstanding at September 30, 2023 ​ 3,321,448 ​ $ 14.01 ​ 8.55 ​ $ 1,436 Vested and exercisable at September 30, 2023 ​ 994,708 ​ $ 19.38 ​ 7.63 ​ $ 662 Vested and expected to vest at September 30, 2023 3,321,448 ​ $ 14.01 ​ 8.55 ​ $ 1,436

Organization and Operations - L

Organization and Operations - Liquidity (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended	3 Months Ended	9 Months Ended
	Jun. 30, 2021	Nov. 30, 2022	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Liquidity
Accumulated deficit				$ 549,124		$ 507,643
Cash, cash equivalents and short-term investments				$ 188,800
Exercise price (in dollars per share)				$ 37.50
Common stock
Liquidity
Issuance of common stock for at-the-market offerings, net of issuance costs (in shares)			2,715,166
Pre-funded warrants
Liquidity
Exercise price (in dollars per share)				0.001
Common stock warrants
Liquidity
Exercise price (in dollars per share)				$ 8.025
ATM Program | Common stock
Liquidity
Net proceeds from issuance of common stock			$ 24,300		$ 24,300
Gross proceeds from issuance of stock			25,000		25,000
Underwritten public offering
Liquidity
Number of shares issued				8,253,895
Gross proceeds from issuance of stock				$ 64,000
Underwritten public offering | Common stock warrants
Liquidity
Number of warrants to purchase common stock				6,190,418
Underwritten public offering | Pre-funded warrants
Liquidity
Number of warrants to purchase common stock				1,571,093
Underwritten public offering | Common stock warrants
Liquidity
Number of warrants to purchase common stock				1,178,320
Jefferies | ATM Program
Liquidity
Maximum aggregate value of common shares which can be issued under the agreement	$ 25,000		50,000		50,000
Percentage of commission paid to underwriter based on proceeds from common stock	3%
Amount of common stock available for future issuance		$ 50,000	$ 30,500		$ 30,500
Aggregate offering price		$ 88,100
Amount of common stock remains available for sale under ATM program				$ 50,000
Issuance of common stock for at-the-market offerings, net of issuance costs (in shares)			2,715,166		2,715,166

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Net Loss Per Share (Details) - shares	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Antidilutive common stock equivalents excluded from computation of diluted net loss per share
Anti-dilutive securities excluded from the calculation of diluted net loss per share (in shares)	8,837,897	9,010,625
Series X Preferred Stock
Antidilutive common stock equivalents excluded from computation of diluted net loss per share
Anti-dilutive securities excluded from the calculation of diluted net loss per share (in shares)	5,184,591	5,242,501
Stock options
Antidilutive common stock equivalents excluded from computation of diluted net loss per share
Anti-dilutive securities excluded from the calculation of diluted net loss per share (in shares)	3,321,448	2,237,948
Common stock warrants
Antidilutive common stock equivalents excluded from computation of diluted net loss per share
Anti-dilutive securities excluded from the calculation of diluted net loss per share (in shares)	331,858	1,530,176

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Dec. 31, 2021
Summary of Significant Accounting Policies
Restricted cash, Balance Sheet location	Prepaid expenses and other current assets		Other assets
Cash and cash equivalents	$ 119,806	$ 20,525	$ 45,972
Restricted cash	163		163
Total	$ 119,969	$ 20,688	$ 46,135	$ 86,629

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Preferred Stock Discount (Details) - Private Placement - Series X redeemable convertible preferred stock - USD ($) $ in Millions	1 Months Ended	9 Months Ended
	Feb. 28, 2021	Sep. 30, 2023
Preferred stock discount
Beneficial conversion feature	$ 19.6
Deferred stock issuance costs for Underwriting Agreement	$ 5.7
Non-cash dividend		$ 24.4
Value of remaining shares not yet converted		$ 0.9

Financial Instruments - Fair va

Financial Instruments - Fair value hierarchy (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Financial Instruments Measurements
Transfers between fair value measurement levels	$ 0	$ 0	$ 0	$ 0
Reverse repurchase agreements | Government Securities and Obligations
Financial Instruments Measurements
Percentage of investment amount to collateralized deposits value			102%
Recurring
Assets:
Total	72,876		$ 72,876		$ 207,856
Recurring | Level 1
Assets:
Total	3,876		3,876		7,924
Recurring | Level 2
Assets:
Total	69,000		69,000		199,932
Recurring | Money market funds
Assets:
Cash and cash equivalents:	3,876		3,876		1,944
Recurring | Money market funds | Level 1
Assets:
Cash and cash equivalents:	3,876		3,876		1,944
Recurring | Corporate debt securities
Assets:
Short-term investments:					16,445
Recurring | Corporate debt securities | Level 2
Assets:
Short-term investments:					16,445
Recurring | Yankee securities
Assets:
Short-term investments:					1,999
Recurring | Yankee securities | Level 2
Assets:
Short-term investments:					1,999
Recurring | Bonds
Assets:
Short-term investments:					2,988
Recurring | Bonds | Level 2
Assets:
Short-term investments:					2,988
Recurring | Treasury bills
Assets:
Short-term investments:					5,980
Recurring | Treasury bills | Level 1
Assets:
Short-term investments:					5,980
Recurring | Reverse repurchase agreements
Assets:
Short-term investments:	69,000		69,000		178,500
Recurring | Reverse repurchase agreements | Level 2
Assets:
Short-term investments:	$ 69,000		$ 69,000		$ 178,500

Short-Term Investments (Details

Short-Term Investments (Details) $ in Thousands	Sep. 30, 2023 USD ($) item	Dec. 31, 2022 USD ($) item
Short-term Investments
Short-Term Investments
Amortized Cost	$ 69,000	$ 205,991
Gross Unrealized Losses		(79)
Fair Value	$ 69,000	$ 205,912
Number of short term investments in unrealized loss position for less than 12 months | item	0	16
Aggregate value of short term investments in unrealized loss position for less than 12 months		$ 25,600
Corporate debt securities
Short-Term Investments
Amortized Cost		16,508
Gross Unrealized Losses		(63)
Fair Value		16,445
Treasury bills
Short-Term Investments
Amortized Cost		5,983
Gross Unrealized Losses		(3)
Fair Value		5,980
Yankee securities
Short-Term Investments
Amortized Cost		2,000
Gross Unrealized Losses		(1)
Fair Value		1,999
U.S. agency bonds
Short-Term Investments
Amortized Cost		3,000
Gross Unrealized Losses		(12)
Fair Value		2,988
Reverse repurchase agreements
Short-Term Investments
Amortized Cost	$ 69,000	178,500
Fair Value	$ 69,000	$ 178,500

Accrued Expenses (Details)

Accrued Expenses (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Accrued Expenses
Accrued contracted costs	$ 2,863	$ 2,822
Accrued compensation	2,671	3,373
Accrued professional fees	1,891	588
Accrued other	331	407
Accrued milestones		500
Total	$ 7,756	$ 7,690

Commitments (Details)

Commitments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Future minimum payments
2023	$ 112		$ 112
2024	395		395
Total lease payments	507		507
Less: imputed interest	(19)		(19)
Total operating lease liabilities	488		488
Operating leases
Rent expense	200	$ 200	500	$ 700
Lease payments	$ 200	$ 200	$ 500	$ 700

Stockholders' Equity - Preferre

Stockholders' Equity - Preferred Stock (Details) $ / shares in Units, $ in Millions		1 Months Ended
	Jan. 03, 2023 shares	Jan. 31, 2021 USD ($) shares	Sep. 30, 2023 series $ / shares shares	Jan. 31, 2023 shares	Dec. 31, 2022 $ / shares shares
Preferred Stock
Preferred stock, authorized			5,000,000
Preferred stock, par value (in dollars per share) | $ / shares			$ 0.001
Minimum number of series used to issue preferred stock | series			1
Series X redeemable convertible preferred stock
Preferred Stock
Preferred stock, authorized			91,380		91,380
Preferred stock, par value (in dollars per share) | $ / shares			$ 0.001		$ 0.001
Aggregate shares of series X preferred stock		35,573
Gross proceeds from series X preferred stock | $		$ 110
Net proceeds from series X preferred stock | $		$ 104.3
Number of preferred shares converted during period	348
Issuance of common stock upon the conversion of preferred stock (shares)	57,910
Preferred stock, outstanding (in shares)			31,107		31,455
Common stock issuable upon conversion of the series X preferred stock			5,184,591	166.67

Stockholders' Equity - Outstand

Stockholders' Equity - Outstanding warrants (Details)	9 Months Ended
	Sep. 30, 2023 $ / shares shares
Stockholders' Equity
Warrants Outstanding (in shares) | shares	331,858
Exercise price (in dollars per share) | $ / shares	$ 37.50
Weighted average
Stockholders' Equity
Weighted average life (in years)	4 months 9 days
Warrants Issued in 2019 | Common stock warrants
Stockholders' Equity
Warrants Outstanding (in shares) | shares	331,858
Exercise price (in dollars per share) | $ / shares	$ 37.50

Reserved for Future Issuance (D

Reserved for Future Issuance (Details) - shares	Sep. 30, 2023	Dec. 31, 2022
Reserved for Future Issuance
Number of shares reserved for future issuance	13,447,779	10,076,610
Series X Preferred Stock
Reserved for Future Issuance
Number of shares reserved for future issuance	5,184,591	5,242,501
Reserve under the 2015 Amended and Restated Stock Incentive Plan and the 2022 Inducement Stock Incentive Plan
Reserved for Future Issuance
Number of shares reserved for future issuance	4,566,822	1,013,520
Options outstanding to purchase common stock
Reserved for Future Issuance
Number of shares reserved for future issuance	3,321,448	2,253,431
Warrants for the purchase of common stock
Reserved for Future Issuance
Number of shares reserved for future issuance	331,858	1,530,176
Shares reserved for the employee stock purchase plan
Reserved for Future Issuance
Number of shares reserved for future issuance	43,060	36,982

Stock Incentive Plans - Stock o

Stock Incentive Plans - Stock options (Details) - Stock options - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Shares
Outstanding, beginning of year (in shares)			2,253,431
Granted (in shares)			1,657,550
Exercised (in shares)			(78,050)
Cancelled or forfeited (in shares)			(510,960)
Expired (in shares)			(523)
Outstanding, end of year (in shares)	3,321,448		3,321,448		2,253,431
Vested and exercisable (in shares)	994,708		994,708
Vested and expected to vest (in shares)	3,321,448		3,321,448
Weighted-Average Exercise Price
Outstanding, beginning of year (in dollars per share)			$ 15.43
Granted (in dollars per share)			12.62
Exercised (in dollars per share)			5.37
Cancelled or forfeited (in dollars per share)			16.96
Expired (in dollars per share)			138.60
Outstanding at end of year (in dollars per share)	$ 14.01		14.01		$ 15.43
Vested and exercisable at end of year (in dollars per share)	19.38		19.38
Vested and expected to vest at end of the year (in dollars per share)	$ 14.01		$ 14.01
Weighted Average Remaining Contractual Term (years)
Outstanding			8 years 6 months 18 days		8 years 6 months 25 days
Vested and exercisable			7 years 7 months 17 days
Vested and expected to vest			8 years 6 months 18 days
Aggregate Intrinsic Value
Outstanding	$ 1,436		$ 1,436		$ 9,733
Vested and exercisable	662		662
Vested and expected to vest	1,436		$ 1,436
Stock Incentive Plans
Number of options exercised (in shares)			78,050
Intrinsic value of options exercised	100	$ 100	$ 500	$ 100
Aggregate fair value of options vested	$ 900	$ 900	$ 3,600	$ 4,700
Weighted average grant date fair value of options granted (in dollars per share)	$ 5.89	$ 2.54	$ 7.48	$ 3.66
Unrecognized compensation expense related to unvested stock option awards	$ 14,600		$ 14,600
Weighted-average amortization period over which cost is expected to be recognized			2 years 9 months 18 days

Stock Incentive Plans - Inducem

Stock Incentive Plans - Inducement plan (Details) - shares	Sep. 30, 2023	Jun. 02, 2023	Feb. 01, 2023	Jan. 31, 2023	Jan. 30, 2023	Feb. 17, 2022
2022 Inducement Stock Incentive Plan
Stock Incentive Plans
Number of shares authorized				700,000	300,000	300,000
Number of grants issued	538,100
2015 Amended and Restated Stock Incentive Plan
Stock Incentive Plans
Number of shares issued			855,000
Number of additional shares authorized		4,300,000
Number of stock options remain outstanding	755,000

Subsequent Events (Details)

Subsequent Events (Details) - License agreement $ in Millions	1 Months Ended
	Oct. 31, 2023 USD ($)	Oct. 04, 2023 USD ($) item
Underwritten public offering
Subsequent Events
Maximum number of indications under regulatory approval and commercial sales milestones | item		3
Subsequent Event
Subsequent Events
Upfront license fee paid	$ 15
License fee payable in milestone		$ 305
License fee payable related to clinical development milestones	$ 20
Maximum number of indications under clinical development milestones | item		70,000,000
License fee payable related to regulatory approval and commercial sales milestones		$ 215