HOOKIPA Pharma (HOOK) 10-Q14 Nov 242024 Q3 Quarterly reportFinancial data

Company Profile

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2024	Nov. 11, 2024
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2024
Document Transition Report	false
Entity File Number	001-38869
Entity Registrant Name	HOOKIPA PHARMA INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	81-5395687
Entity Address, Address Line One	350 Fifth Avenue, 72nd Floor, Suite 7240
Entity Address, City or Town	New York
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10118
Country Region	+43
City Area Code	1
Local Phone Number	890 63 60
Title of 12(b) Security	Common Stock
Trading Symbol	HOOK
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	true
Entity Ex Transition Period	true
Entity Shell Company	false
Entity Central Index Key	0001760542
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q3
Amendment Flag	false
Common stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		9,655,022
Class A common stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		2,399,517

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) - USD ($)		Sep. 30, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents		$ 59,750,000	$ 117,096,000
Accounts receivable		324,000	511,000
Receivable research incentives		24,666,000	18,760,000
Prepaid expenses and other current assets		8,416,000	10,749,000
Total current assets		93,156,000	147,116,000
Non-current assets:
Restricted cash		207,000	425,000
Property, plant and equipment, net		6,860,000	7,742,000
Operating lease right of use assets		2,862,000	5,473,000
Prepaid expenses and other non-current assets		6,645,000	581,000
Total non-current assets		16,574,000	14,221,000
Total assets		109,730,000	161,337,000
Current liabilities
Accounts payable		8,955,000	12,498,000
Deferred revenues		5,334,000	14,631,000
Operating lease liabilities, current		1,206,000	1,638,000
Accrued expenses and other current liabilities		13,073,000	12,101,000
Loans payable, current			1,120,000
Total current liabilities		28,568,000	41,988,000
Non-current liabilities
Operating lease liabilities, non-current		1,619,000	3,801,000
Deferred revenues, non-current		1,679,000	19,674,000
Other non-current liabilities		6,062,000	6,017,000
Total non-current liabilities		9,360,000	29,492,000
Total liabilities		37,928,000	71,480,000
Stockholders' equity:
Preferred Stock		0	0
Additional paid-in capital		468,199,000	467,050,000
Accumulated other comprehensive loss		(8,584,000)	(7,933,000)
Accumulated deficit		(387,814,000)	(369,261,000)
Total stockholders' equity	[1]	71,802,000	89,857,000
Total liabilities and stockholders' equity		109,730,000	161,337,000
Common stock
Stockholders' equity:
Common stock		1,000	1,000
Class A common stock
Stockholders' equity:
Common stock		$ 0	$ 0

[1] (1) one

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) (Parenthetical)	Sep. 30, 2024 $ / shares shares	Dec. 31, 2023 $ / shares shares
Preferred stock, par value (in dollars per share) \| $ / shares	$ 0.0001	$ 0.0001
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Series A convertible preferred stock
Preferred stock shares designated (in shares)	2,978	2,978
Preferred stock, shares outstanding (in shares)	370	370
Series A-1 convertible preferred stock
Preferred stock shares designated (in shares)	15,800	15,800
Preferred stock, shares outstanding (in shares)	10,800	10,800
Series A-2 convertible preferred stock
Preferred stock shares designated (in shares)	15,268	15,268
Preferred stock, shares outstanding (in shares)	15,268	15,268
Common stock
Common stock, par value (in dollars per share) \| $ / shares	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	40,000,000	20,000,000
Common stock, shares issued (in shares)	9,655,022	9,655,022
Common stock, shares outstanding (in shares)	9,655,022	9,655,022
Class A common stock
Common stock, par value (in dollars per share) \| $ / shares	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	3,900,000	3,900,000
Common stock, shares issued (in shares)	2,399,517	2,399,517
Common stock, shares outstanding (in shares)	2,399,517	2,399,517

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (UNAUDITED) - USD ($)		3 Months Ended		9 Months Ended
		Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (UNAUDITED)
Revenue from collaboration and licensing		$ 4,703,000	$ 6,867,000	$ 42,592,000	$ 12,722,000
Revenue from Contract with Customer, Product and Service [Extensible List]		hook:CollaborationAndLicensingMember	hook:CollaborationAndLicensingMember	hook:CollaborationAndLicensingMember	hook:CollaborationAndLicensingMember
Operating expenses:
Research and development		$ (15,565,000)	$ (24,625,000)	$ (55,482,000)	$ (65,262,000)
General and administrative		(6,732,000)	(4,912,000)	(14,733,000)	(14,259,000)
Restructuring		(878,000)		(2,201,000)
Impairment		(172,000)		(172,000)
Total operating expenses		(23,347,000)	(29,537,000)	(72,588,000)	(79,521,000)
Loss from operations		(18,644,000)	(22,670,000)	(29,996,000)	(66,799,000)
Other (expense) income:
Grant income		2,183,000	2,916,000	6,924,000	7,486,000
Interest income		809,000	1,570,000	3,213,000	4,052,000
Interest expense			(49,000)	(2,000)	(268,000)
Other income (expense), net		1,811,000	(833,000)	1,308,000	(1,029,000)
Total other income, net		4,803,000	3,604,000	11,443,000	10,241,000
Net loss before tax		(13,841,000)	(19,066,000)	(18,553,000)	(56,558,000)
Income tax expense		0	0	0	(204,000)
Net loss		(13,841,000)	(19,066,000)	(18,553,000)	(56,762,000)
Other comprehensive loss:
Foreign currency translation gain (loss), net of tax		(1,360,000)	1,216,000	(651,000)	1,130,000
Comprehensive loss		$ (15,201,000)	$ (17,850,000)	$ (19,204,000)	$ (55,632,000)
Net loss per share - basic	[1]	$ (1.10)	$ (1.73)	$ (1.48)	$ (6.41)
Net loss per share - diluted	[1]	$ (1.10)	$ (1.73)	$ (1.48)	$ (6.41)

[1] (1) one

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (UNAUDITED) (Parenthetical)	Jul. 09, 2024
CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (UNAUDITED)
Reverse stock split of common stock	0.1

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (UNAUDITED) - USD ($)		Convertible Preferred Stock Series A convertible preferred stock	Convertible Preferred Stock Series A-1 convertible preferred stock	Convertible Preferred Stock Series A-2 convertible preferred stock Public offering	Convertible Preferred Stock	Common Stock Common stock		Common Stock Class A common stock	Common Stock Common Stock Public offering	[1]	Common Stock Series A convertible preferred stock	[1]	Common Stock Series A-1 convertible preferred stock	[1]	Additional Paid-In Capital Common Stock Public offering	Additional Paid-In Capital Series A convertible preferred stock	Additional Paid-In Capital Series A-1 convertible preferred stock	Additional Paid-In Capital Series A-2 convertible preferred stock Public offering	Additional Paid-In Capital Series A-2 convertible preferred stock	Additional Paid-In Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit	Common Stock Public offering	Series A-2 convertible preferred stock Public offering	Series A-2 convertible preferred stock	Total
Balance at the beginning of the period at Dec. 31, 2022					$ 0	$ 1,000	[1]	$ 0												$ 397,353,000	$ (7,156,000)	$ (287,681,000)				$ 102,517,000
Balance at the beginning of the period (in shares) at Dec. 31, 2022					17,497	5,231,713	[1]	2,399,517
Increase (Decrease) in Stockholders' Equity
Issuance of common stock upon exercise of stock options						$ 0	[1]													1,000						1,000
Issuance of common stock upon exercise of stock options (in shares)	[1]					569
Foreign currency translation adjustment, net of tax																					(17,000)					(17,000)
Stock-based compensation income																				658,000						658,000
Net Income (Loss)																						(19,680,000)				(19,680,000)
Balance at the end of the period at Mar. 31, 2023					$ 0	$ 1,000	[1]	$ 0												398,012,000	(7,173,000)	(307,361,000)				83,479,000
Balance at the end of the period (in shares) at Mar. 31, 2023					17,497	5,232,282	[1]	2,399,517
Balance at the beginning of the period at Dec. 31, 2022					$ 0	$ 1,000	[1]	$ 0												397,353,000	(7,156,000)	(287,681,000)				102,517,000
Balance at the beginning of the period (in shares) at Dec. 31, 2022					17,497	5,231,713	[1]	2,399,517
Increase (Decrease) in Stockholders' Equity
Foreign currency translation adjustment, net of tax																										1,130,000
Net Income (Loss)																										(56,762,000)
Balance at the end of the period at Sep. 30, 2023					$ 0	$ 1,000	[1]	$ 0												445,519,000	(6,026,000)	(344,443,000)				95,051,000
Balance at the end of the period (in shares) at Sep. 30, 2023					26,438	8,155,059	[1]	2,399,517
Balance at the beginning of the period at Dec. 31, 2022					$ 0	$ 1,000	[1]	$ 0												397,353,000	(7,156,000)	(287,681,000)				102,517,000
Balance at the beginning of the period (in shares) at Dec. 31, 2022					17,497	5,231,713	[1]	2,399,517
Increase (Decrease) in Stockholders' Equity
Net Income (Loss)																										(81,600,000)
Balance at the end of the period at Dec. 31, 2023					$ 0	$ 1,000	[1]	$ 0												467,050,000	(7,933,000)	(369,261,000)				89,857,000	[2]
Balance at the end of the period (in shares) at Dec. 31, 2023					26,438	9,655,022	[1]	2,399,517
Balance at the beginning of the period at Mar. 31, 2023					$ 0	$ 1,000	[1]	$ 0												398,012,000	(7,173,000)	(307,361,000)				83,479,000
Balance at the beginning of the period (in shares) at Mar. 31, 2023					17,497	5,232,282	[1]	2,399,517
Increase (Decrease) in Stockholders' Equity
Conversion of preferred stock into common stock		$ 0	$ 0								$ 0		$ 0			$ 0	$ 0
Conversion of preferred stock into common stock (in shares)		(1,327)	(5,000)								132,700		500,000
Issuance of stock				$ 0					$ 0						$ 27,795,000			$ 18,531,000					$ 27,795,000	$ 18,531,000
Issuance of stock (in shares)				15,268					2,290,077
ATM costs																				(86,000)						(86,000)
Foreign currency translation adjustment, net of tax																					(69,000)					(69,000)
Stock-based compensation income																				696,000						696,000
Net Income (Loss)																						(18,016,000)				(18,016,000)
Balance at the end of the period at Jun. 30, 2023					$ 0	$ 1,000	[1]	$ 0												444,948,000	(7,242,000)	(325,377,000)				112,330,000
Balance at the end of the period (in shares) at Jun. 30, 2023					26,438	8,155,059	[1]	2,399,517
Increase (Decrease) in Stockholders' Equity
Issuance of stock															$ (2,000)				$ (1,000)				$ (2,000)		$ (1,000)
Foreign currency translation adjustment, net of tax																					1,216,000					1,216,000
Stock-based compensation income																				574,000						574,000
Net Income (Loss)																						(19,066,000)				(19,066,000)
Balance at the end of the period at Sep. 30, 2023					$ 0	$ 1,000	[1]	$ 0												445,519,000	(6,026,000)	(344,443,000)				95,051,000
Balance at the end of the period (in shares) at Sep. 30, 2023					26,438	8,155,059	[1]	2,399,517
Balance at the beginning of the period at Dec. 31, 2023					$ 0	$ 1,000	[1]	$ 0												467,050,000	(7,933,000)	(369,261,000)				89,857,000	[2]
Balance at the beginning of the period (in shares) at Dec. 31, 2023					26,438	9,655,022	[1]	2,399,517
Increase (Decrease) in Stockholders' Equity
Foreign currency translation adjustment, net of tax																					531,000					531,000
Stock-based compensation income																				(249,000)						(249,000)
Net Income (Loss)																						14,383,000				14,383,000
Balance at the end of the period at Mar. 31, 2024					$ 0	$ 1,000	[1]	$ 0												466,801,000	(7,402,000)	(354,878,000)				104,522,000
Balance at the end of the period (in shares) at Mar. 31, 2024					26,438	9,655,022	[1]	2,399,517
Balance at the beginning of the period at Dec. 31, 2023					$ 0	$ 1,000	[1]	$ 0												467,050,000	(7,933,000)	(369,261,000)				89,857,000	[2]
Balance at the beginning of the period (in shares) at Dec. 31, 2023					26,438	9,655,022	[1]	2,399,517
Increase (Decrease) in Stockholders' Equity
Foreign currency translation adjustment, net of tax																										(651,000)
Net Income (Loss)																										(18,553,000)
Balance at the end of the period at Sep. 30, 2024					$ 0	$ 1,000	[1]	$ 0												468,199,000	(8,584,000)	(387,814,000)				71,802,000	[2]
Balance at the end of the period (in shares) at Sep. 30, 2024					26,438	9,655,022	[1]	2,399,517
Balance at the beginning of the period at Mar. 31, 2024					$ 0	$ 1,000	[1]	$ 0												466,801,000	(7,402,000)	(354,878,000)				104,522,000
Balance at the beginning of the period (in shares) at Mar. 31, 2024					26,438	9,655,022	[1]	2,399,517
Increase (Decrease) in Stockholders' Equity
Foreign currency translation adjustment, net of tax																					178,000					178,000
Stock-based compensation income																				459,000						459,000
Net Income (Loss)																						(19,095,000)				(19,095,000)
Balance at the end of the period at Jun. 30, 2024					$ 0	$ 1,000	[1]	$ 0												467,260,000	(7,224,000)	(373,973,000)				86,064,000
Balance at the end of the period (in shares) at Jun. 30, 2024					26,438	9,655,022	[1]	2,399,517
Increase (Decrease) in Stockholders' Equity
Foreign currency translation adjustment, net of tax																					(1,360,000)					(1,360,000)
Stock-based compensation income																				939,000						939,000
Net Income (Loss)																						(13,841,000)				(13,841,000)
Balance at the end of the period at Sep. 30, 2024					$ 0	$ 1,000	[1]	$ 0												$ 468,199,000	$ (8,584,000)	$ (387,814,000)				$ 71,802,000	[2]
Balance at the end of the period (in shares) at Sep. 30, 2024					26,438	9,655,022	[1]	2,399,517

[1] (1) one (1) one

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (UNAUDITED) (Parenthetical) $ in Thousands	3 Months Ended
	Jun. 30, 2023 USD ($) $ / shares
Series A-2 convertible preferred stock \| Public offering
Share price (in USD per share) \| $ / shares	$ 13,100
Issuance costs \| $	$ 1,470
Common stock \| Public offering
Share price (in USD per share) \| $ / shares	$ 13.10
Issuance costs \| $	$ 2,205

CONDENSED CONSOLIDATED STATEM_5

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Operating activities:
Net loss	$ (18,553)	$ (56,762)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	1,149	1,928
Depreciation and amortization expense	2,054	2,274
Impairment expense	172
Other non-cash items	3	4
Changes in operating assets and liabilities:
Accounts receivable	561	5,838
Receivable research incentives	(5,582)	(7,227)
Prepaid expenses and other current assets	2,158	3,507
Prepaid expenses and other non-current assets	(5,901)	(242)
Accounts payable	(5,091)	4,104
Deferred revenues	(26,742)	(1,161)
Operating lease liabilities	(1,194)	(819)
Accrued expenses and other liabilities	926	2,052
Other non-current liabilities		204
Net cash used in operating activities	(56,040)	(46,300)
Investing activities:
Purchases of property and equipment	(192)	(3,737)
Net cash used in investing activities	(192)	(3,737)
Financing activities:
Proceeds from issuance of convertible preferred stock, net of issuance costs		18,530
Proceeds from issuance of common stock, net of issuance costs		27,794
Payments for deferred offering costs	(135)	(149)
Repayments of borrowings	(1,141)	(1,754)
Net cash (used in) provided by financing activities	(1,276)	44,421
Net decrease in cash, cash equivalents and restricted cash	(57,508)	(5,616)
Cash, cash equivalents and restricted cash at beginning of period	117,521	113,444
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(56)	267
Cash, cash equivalents and restricted cash at end of period	59,957	108,095
Supplemental disclosure of cash flow information:
Cash paid for interest	(2)	(10)
Cash paid for income taxes	0	(204)
Supplemental disclosure of non-cash financing activities:
Property and equipment additions in accounts payable and accrued expenses	(4)	(121)
Lease assets obtained in exchange for new operating lease liabilities	466	$ 19
Lease assets derecognized upon lease modification	$ (1,961)

Nature of the business and orga

Nature of the business and organization	9 Months Ended
Nature of the business and organization	Sep. 30, 2024
Nature of the business and organization
Nature of the business and organization	1. Nature of the business and organization HOOKIPA Pharma Inc. (“HOOKIPA” or the “Company”) is a clinical stage biopharmaceutical company developing a new class of immunotherapeutics based on its proprietary arenavirus platform that is designed to reprogram the body’s immune system. The Company was incorporated under the name of Hookipa Biotech, Inc. under the laws of the State of Delaware in February 2017 as a fully-owned subsidiary of Hookipa Biotech AG. In June 2018, the Company changed its name from Hookipa Biotech, Inc. to HOOKIPA Pharma Inc. and in order to effectuate the change of the jurisdiction of incorporation, the Company acquired all of the shares of Hookipa Biotech AG, now HOOKIPA Biotech GmbH. HOOKIPA is headquartered in New York, with European research and preclinical development operations headquartered in Vienna, Austria. In April 2019, the Company closed its initial public offering (“IPO”) and its common stock is currently traded on the Nasdaq Capital Market under the ticker symbol “HOOK”. The Company is subject to risks and uncertainties common to early-stage companies in the biotechnology industry, including, but not limited to, development by competitors of new technological innovations, dependence on key personnel, protection of proprietary technology, compliance with government regulations, the ability to establish clinical- and commercial-scale manufacturing processes and the ability to secure additional capital to fund operations. Product candidates currently under development will require significant additional research and development efforts, including extensive preclinical and clinical testing and regulatory approval prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel and infrastructure and extensive compliance-reporting capabilities and may not ultimately lead to a marketing approval and commercialization of a product. Even if the Company’s drug development efforts are successful, it is uncertain if and when the Company will realize significant revenue from product sales.

Summary of significant accounti

Summary of significant accounting policies	9 Months Ended
Summary of significant accounting policies	Sep. 30, 2024
Summary of significant accounting policies
Summary of significant accounting policies	2. Summary of significant accounting policies Basis of presentation The Company’s condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). The accompanying condensed consolidated financial statements include the accounts of the Company and its wholly owned subsidiary. All intercompany accounts and transactions have been eliminated in consolidation. The consolidated balance sheet as of December 31, 2023 was derived from audited financial statements but does not include all disclosures required by GAAP. The accompanying condensed consolidated balance sheet as of September 30, 2024, the condensed consolidated statements of operations, and comprehensive loss for the three and nine months ended September 30, 2024 and 2023, the condensed consolidated statement of convertible preferred stock and stockholders’ equity for the three and nine months ended September 30, 2024 and 2023 and the condensed consolidated statements of cash flows for the nine months ended September 30, 2024 and 2023 are unaudited. The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited annual consolidated financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair statement for interim reporting. Certain information and footnote disclosures typically included in annual financial statements prepared in accordance with GAAP have been condensed or omitted. Accordingly, these unaudited interim condensed consolidated financial statements should be read in conjunction with the Company’s audited financial statements for the year ended December 31, 2023 included in the Company’s Annual Report on Form 10-K, filed with the Securities and Exchange Commission (“SEC”) Going concern At each reporting period, in accordance with Accounting Standards Codification ("ASC") 205-40, Going Concern, the Company evaluates whether there are conditions or events that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that the financial statements are issued. The Company’s evaluation entails analyzing prospective operating budgets and forecasts for expectations of the Company’s cash needs and comparing those needs to the current cash and cash equivalent balances. The Company is required to make certain additional disclosures if it concludes substantial doubt exists and it is not alleviated by the Company’s plans or when its plans alleviate substantial doubt about the Company’s ability to continue as a going concern. This evaluation initially does not take into consideration the potential mitigating effect of management’s plans that have not been fully implemented as of the date the condensed consolidated financial statements are issued. When substantial doubt exists under this methodology, management evaluates whether the mitigating effect of its plans sufficiently alleviates substantial doubt about the Company’s ability to continue as a going concern. The mitigating effect of management’s plans, however, is only considered if both (1) it is probable that the plans will be effectively implemented within one year after the date that the condensed consolidated financial statements are issued, and (2) it is probable that the plans, when implemented, will mitigate the relevant conditions or events that raise substantial doubt about the entity’s ability to continue as a going concern within one year after the date that these condensed consolidated financial statements are issued. In performing its analysis, management excluded certain elements of its operating plan that cannot be considered probable. Under ASC 205-40, the future receipt of potential funding from future partnerships, equity or debt issuances, the potential milestones from the Gilead Collaboration Agreement and potential reductions in force cannot be considered probable at this time because these plans are not entirely within the Company’s control and/or have not been approved by the Board of Directors as of the date of these condensed consolidated financial statements. Since inception, the Company’s activities have consisted primarily of performing research and development to advance its technologies. The Company is still in the development phase and has not been marketing its technologies to date. Through September 30, 2024, the Company has funded its operations with proceeds from sales of common stock, sales of convertible preferred stock, sales of redeemable convertible preferred stock, collaboration and licensing agreements, grants and borrowings under various agreements with foreign public funding agencies. Since inception, the Company has incurred recurring losses, including a net loss of $ 18.6 387.8 These condensed consolidated financial statements have been prepared assuming that the Company will continue as a going concern, which contemplates the realization of assets and the settlement of liabilities and commitments in the normal course of business. The condensed consolidated financial statements do not reflect any adjustments relating to the recoverability and classification of assets or the amounts and classification of liabilities that might result from the outcome of the uncertainties described above. Reverse stock split On July 9, 2024, the Company effected a reverse stock split of the outstanding shares of its common stock on a one-for-ten ( 1 one Use of estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue, income and expenses during the reporting periods. Significant estimates and assumptions reflected in these condensed consolidated financial statements include, but are not limited to, the recognition of revenue and income, the accrual of research and development expenses and general and administrative expenses, the present value of lease right of use assets and corresponding liabilities, the valuation of stock-based awards, the valuation of current loans payable, the impairment of long-lived assets and going concern. The Company bases its estimates on historical experience, known trends and other market-specific or other relevant factors that it believes to be reasonable under the circumstances. On an ongoing basis, management evaluates its estimates as there are changes in circumstances, facts and experience. As of the date of issuance of these unaudited condensed consolidated financial statements, the Company is not aware of any specific event or circumstance that would require the Company to update estimates, judgments or revise the carrying value of any assets or liabilities. Actual results may differ from those estimates or assumptions. Deferred offering costs The Company capitalizes certain legal, professional accounting and other third-party fees that are directly associated with in-process equity financings as deferred offering costs until such financings are consummated. After consummation of an equity financing, these costs are recorded in stockholders’ equity as a reduction of the additional paid-in capital on a pro-rata basis generated as a result of the offering. Should the in-process equity financing be abandoned, the deferred offering costs will be expensed immediately as a charge to operating expenses in the condensed consolidated statements of operations and comprehensive loss. Concentrations of credit risk and of significant suppliers Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash, cash equivalents and short-term bank deposits held with banks in excess of publicly insured limits. For the three and nine months ended September 30, 2024 and September 30, 2023 the net proceeds from the Company’s offerings have been deposited in interest-bearing bank accounts with two of the largest investment grade U.S. financial institutions and have been partially invested in money market funds. The money market funds, held in U.S. dollars, are primarily invested in U.S. and foreign short-term debt obligations. As of September 30, 2024 and December 31, 2023, the Company’s cash and cash equivalents included smaller amounts of cash balances held in accounts with regional European banks at the Company’s Austrian subsidiary, partially in euros. The Company does not believe that it is subject to unusual credit risk beyond the normal credit risk associated with commercial banking relationships. The Company relies, and expects to continue to rely, on a small number of vendors to manufacture supplies and raw materials for its development programs. These programs could be adversely affected by a significant interruption in these manufacturing services or the availability of raw materials. As of September 30, 2024 Gilead Sciences, Inc. (“Gilead”) accounted for the majority of the accounts receivable balance. As of December 31, 2023, Gilead and F. Hoffmann-La Roche Ltd. and Hoffmann-La Roche Inc. (together “Roche”) accounted for the majority of the accounts receivable balance. For the three months ended September 30, 2024 Gilead accounted for the majority of the Company’s revenues. For the nine months ended September 30, 2024 Roche accounted for the majority of the Company’s revenues as a result of a contract modification and the recognition of upfront and milestone payments previously recorded as deferred revenues. For the three and nine months ended September 30, 2023 Gilead and Roche accounted for the majority of the Company’s revenues. Other customers accounted for less than 10.0% of accounts receivable or net revenues. The Company monitors the financial performance of its customers so that it can appropriately respond to changes in their credit-worthiness. To date, the Company has not experienced any significant losses with respect to collection of its accounts receivable. Cash equivalents The Company considers all highly liquid investments with maturities of three months or less at the date of purchase to be cash equivalents. As of September 30, 2024 and December 31, 2023, cash equivalents consisted of money market funds and short-term deposits. Fair value measurements Certain assets and liabilities are carried at fair value under GAAP. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. Financial assets and liabilities carried at fair value are to be classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable: ● Level 1 - Quoted prices in active markets for identical assets or liabilities. ● Level 2 - Observable inputs (other than Level 1 quoted prices), such as quoted prices in active markets for similar assets or liabilities, quoted prices in markets that are not active for identical or similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data. ● Level 3 - Unobservable inputs that are supported by little or no market activity and that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques. The Company’s cash equivalents are carried at fair value, determined according to the fair value hierarchy described above (see Note 6). Property and equipment Property and equipment are stated at cost less accumulated depreciation and amortization. Depreciation and amortization expense is recognized using the straight-line method over the estimated useful life of each asset as follows: Estimated useful life Leasehold improvements shorter of useful life or term of lease Laboratory equipment 2 - 10 years Furniture and fixtures 2 - 10 years Computer equipment and software 2 - 4 years Costs for capital assets not yet placed into service are capitalized as construction-in-progress and depreciated once placed into service. Expenditures for repairs and maintenance are charged to expense as incurred. When property and equipment is sold or otherwise disposed of, the cost and related accumulated depreciation are eliminated from the accounts and any resulting gain or loss is reflected in the consolidated statements of operations. Leases The determination whether an arrangement qualifies as a lease is made at contract inception. A lease qualifies as a finance lease if any of the following criteria are met at the inception of the lease: (i) there is a transfer of ownership of the leased asset to the Company by the end of the lease term, (ii) the Company holds an option to purchase the leased asset that it is reasonably certain to exercise, (iii) the lease term is for a major part of the remaining economic life of the leased asset, (iv) the present value of the sum of lease payments equals or exceeds substantially all of the fair value of the leased asset, or (v) the nature of the leased asset is specialized to the point that it is expected to provide the lessor no alternative use at the end of the lease term. All other leases are recorded as operating leases and are included in right of use (“ROU”) assets and lease liabilities in the consolidated balance sheets. For leases with an initial term of 12 months or less, the Company does not recognize a right of use asset or lease liability. These short-term leases are expensed on a straight-line basis over the lease term. ROU assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent its obligation to make lease payments arising from the lease. ROU assets and lease liabilities are recognized at the commencement date of the lease based upon the present value of lease payments over the lease term. When determining the lease term, the Company includes options to extend or terminate the lease when it is reasonably certain that the option will be exercised. The Company uses the implicit rate when readily determinable and uses its incremental borrowing rate when the implicit rate is not readily determinable based upon the information available at the commencement date in determining the present value of the lease payments. The incremental borrowing rate is determined using a secured borrowing rate for the same currency and term as the associated lease. The lease payments used to determine ROU assets may include lease incentives, stated rent increases and escalation clauses linked to rates of inflation when determinable and are recognized as ROU asset on the consolidated balance sheet. In addition, certain of the Company’s arrangements contain lease and non-lease components. The Company generally separates lease payments from non-lease payments. Operating leases are reflected in operating lease assets, in current operating lease liabilities and non-current operating lease liabilities in the consolidated balance sheets. Finance leases are reflected in finance lease assets, in accrued expenses and other current liabilities and in other non-current operating lease liabilities in the consolidated balance sheets. The ROU asset is tested for impairment in accordance with ASC 360. Capitalized Software Development Cost The Company capitalizes certain implementation costs for internal-use software incurred in a cloud computing agreement that is a service contract. Eligible costs associated with cloud computing arrangements, such as software business applications used in the normal course of business, are capitalized in accordance with ASC 350. These costs are recognized on a straight-line basis in the same line item in the statement of operations and comprehensive loss as the expense for fees for the associated cloud computing arrangement, over the term of the arrangement, plus reasonably certain renewals. Impairment of long-lived assets Long-lived assets, including operating and finance lease right of use assets, consist of property and equipment. Long-lived assets to be held and used are tested for recoverability whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable. Factors that the Company considers in deciding when to perform an impairment review include significant underperformance of the business in relation to expectations, significant negative technological, scientific or economic trends and significant changes or planned changes in the use of the assets. If an impairment review is performed to evaluate a long-lived asset group for recoverability, the Company compares forecasts of undiscounted cash flows expected to result from the use and eventual disposition of the long-lived asset group to its carrying value. An impairment loss would be recognized in loss from operations when estimated undiscounted future cash flows expected to result from the use of an asset group are less than its carrying amount. The impairment loss would be based on the excess of the carrying value of the impaired asset group over its fair value (see Note 5 and Note 7). Restructuring Costs and liabilities associated with restructuring activities are recognized when the actions are probable and estimable, which is when management approves the associated actions. Employee-related severance charges are recognized at the time of communication to employees. Revenue recognition from collaboration and licensing The Company recognized revenue from collaboration and license agreements with Gilead and Roche. Under the collaboration and license agreement with Gilead (as amended and restated, the “Gilead Collaboration Agreement”), the parties agreed to collaborate with respect to two preclinical research programs to evaluate potential vaccine products for the treatment, cure, diagnosis or prevention of the hepatitis B virus (“HBV”) and the human immunodeficiency virus (“HIV”). In February 2022, the parties signed an amended and restated collaboration agreement (the “Restated Gilead Collaboration Agreement”), which revised the terms only for the HIV program, whereby the Company took on development responsibilities for the HIV program candidate through a Phase 1b clinical trial. The Company’s performance obligations under the terms of the original agreement include one combined performance obligation for each research program (HBV and HIV) comprised of the transfer of intellectual property rights (licenses) and providing research and development services. The terms of the Restated Gilead Collaboration Agreement added an additional performance obligation to perform research and development work for the HIV program. The licenses do not represent distinct performance obligations, because they cannot be used without the research and development services. Payments to the Company under the Restated Gilead Collaboration Agreement include a non-refundable up-front payment, payments for research and development activities, payments based upon the achievement of defined milestones, and if certain future conditions are met, payments for manufacturing services, commercial milestones and royalties on product sales. Under the research collaboration and license agreement with Roche (the “Roche Collaboration Agreement”), the Company agreed to conduct research and early clinical development through Phase 1b for HB-700, a novel investigational arenaviral immunotherapy for the treatment of KRAS-mutated cancers. The Roche Collaboration Agreement also included an obligation of the Company to deliver a specified package of preclinical data and results with respect to a second program, targeting undisclosed cancer antigens (collectively “UCAs”) and an option for Roche to license the UCA program. The Company’s performance obligations under the terms of the Roche Collaboration Agreement included one combined performance obligation for the transfer of intellectual property rights (licenses) and providing research and development services for the HB-700 program, and a second, separate performance obligation to perform research and development services with respect to the UCA program. The UCA Option provided a right to license the program at the standalone selling price and therefore did not constitute a separate performance obligation. Payments to the Company under the Roche Collaboration Agreement included a non-refundable up-front payment, payments based upon the achievement of defined milestones, an additional payment if the option for the UCA program was exercised and royalties on product sales. In January 2024, Roche provided written notice of the termination of the collaboration and licensing agreement to the Company resulting in early recognition of revenue previously recorded as deferred revenue. The termination was made according to Roche’s right to terminate without cause, acknowledging that, the Company had met all go-forward criteria under the agreement. Upon the collaboration and licensing agreement termination effective date of April 25, 2024, the Company regained full control of the associated intellectual property portfolio and has full collaboration and licensing rights for this program. The Company evaluates its collaboration and licensing arrangements pursuant to ASC 606 Revenue from Contracts with Customers. To determine the recognition of revenue from arrangements that fall within the scope of ASC 606, the Company performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the Company satisfies a performance obligation. Under ASC 606, the Company applies significant judgement to evaluate whether the promises under the collaboration and licensing arrangements represent separate or one or more combined performance obligations, the allocation of the transaction price to identified performance obligations, the timing of revenue recognition, whether the UCA Option constitutes a material right, and the determination of when milestone payments are probable of being received. Upfront payment and program initiation fee The non-refundable upfront-payment received by the Company upon signing of the Gilead Collaboration Agreement, and milestone payments that were linked to future performance obligations, were initially recorded as deferred revenue and allocated between the two research program performance obligations. Such amounts are recognized as revenue over the performance period of the respective services on a percent of completion basis using total estimated research and development labor hours (input method) for each of the obligations. The percent of completion basis using labor hours was considered the best measure of progress in which control of the combined performance obligations transfers to the customer, due to the short time intervals in which research results are shared with the collaboration partner and the nature of the work being performed. The non-refundable program initiation payment received from Gilead upon signing of the Restated Collaboration Agreement was also initially recorded as deferred revenue and is recognized on a percent of completion basis using total estimated research and development costs (input method) for the performance of the obligations. The percent of completion basis using research and development costs was considered the best measure of progress in which control of the performance obligations transfers to the customer, due to the immediate benefit that it adds to the value of the customer’s rights on the program, the short time intervals in which development results are shared and the nature of the work being performed. The non-refundable upfront-payment received by the Company upon signing of the Roche Collaboration Agreement was initially recorded as deferred revenue and allocated between the HB-700 program and the UCA program. Such amounts were recognized as revenue over the performance period of the respective services on a percent of completion basis using total estimated research and development costs (input method) for each of the obligations during the initial term of the contract. The percent of completion basis using research and development costs was considered the best measure of progress in which control of the performance obligations transfers to the customer. Reimbursement for services Under the Gilead Collaboration Agreement and historically under the Roche Collaboration Agreement prior to termination, the Company incurs employee expenses as well as external costs for research, manufacturing and clinical trial activities presented as operating expenses or prepaid expenses. Based on the nature of the Company's responsibilities under the collaboration arrangements, reimbursement of those costs are presented as revenue and not deducted from expenses, as the Company controls the research activities. Amounts of consideration allocated to the performance of research or manufacturing services are recognized over the period in which services are performed. Reimbursements for external costs are recognized as revenues as progress is achieved. Unpaid reimbursement amounts are presented as Accounts Receivable. Research and development milestones The Gilead Collaboration Agreement includes, and the Roche Collaboration Agreement included, contingent milestone payments related to specified preclinical and clinical development milestones. These milestone payments represent variable consideration that are not initially recognized within the transaction price as they are fully constrained under the guidance in ASC 606, due to the scientific uncertainties and the required commitment from Gilead and Roche. While no further milestone payments are expected under the terminated Roche Collaboration Agreement, the Company will continue to assess the probability of significant reversals for any amounts that become likely to be realized under the Gilead Collaboration Agreement prior to including the variable consideration associated with these payments within the transaction price. Sales-based milestones and royalty payments The Gilead Collaboration Agreement also includes, and the Roche Collaboration Agreement included, certain sales-based milestone and royalty payments upon successful commercialization of a licensed product. In accordance with ASC 606-10-55-65 Sales Based or Usage Based Royalties, the Company recognizes revenues from sales-based milestone and royalty payments at the later of (i) the occurrence of the subsequent sale; or (ii) the performance obligation to which some or all of the sales-based milestone or royalty payments has been allocated has been satisfied. The Company anticipates recognizing these milestones and royalty payments if and when subsequent sales are generated from a licensed product by the collaboration partner. Cost to fulfill contracts The Company incurs costs for personnel, supplies and other costs related to its laboratory operations as well as fees from third parties and license expenses in connection with its research and development obligations under collaboration and licensing agreements. These costs are recognized as research and development expenses over the period in which services are performed. Sublicense fees triggered by the receipt of payments are capitalized as an asset when the obligation to pay the fee arises. The capitalized asset is amortized over the period in which the revenue from the triggering payment is recognized. Recent accounting pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”) or other standard setting bodies that the Company adopts as of the specified effective date. Recently Issued Accounting Pronouncements In December 2023, the FASB issued final guidance in ASU No. 2023-09, Income Taxes (ASC 740): Improvements to Income Tax Disclosures requiring entities to provide additional information in the rate reconciliation and disclosures about income taxes paid. For public business entities, the guidance is effective for annual periods beginning after December 15, 2024. The Company does not expect this ASU to have a material impact on the consolidated financial statements. In November 2023, the FASB issued ASU No. 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures which requires public entities to disclose significant segment expenses regularly provided to the chief operating decision-maker. Public entities with a single reporting segment have to provide all disclosures required by ASC 280, including the significant segment expense disclosures. For public business entities, the guidance is effective for annual periods beginning after December 15, 2024. The Company does not expect this ASU to have a material impact on the consolidated financial statements.

Collaboration and Licensing Agr

Collaboration and Licensing Agreements	9 Months Ended
Collaboration and Licensing Agreements	Sep. 30, 2024
Collaboration and Licensing Agreements
Collaboration and Licensing Agreements	3. Collaboration and Licensing Agreements Gilead Collaboration and License Agreement In June 2018, the Company entered into the Gilead Collaboration Agreement whereby the Company and Gilead agreed to collaborate with respect to two preclinical research programs to evaluate potential vaccine products for the treatment, cure, diagnosis or prevention of HBV and HIV. In February 2022, the Company signed the Amended and Restated Collaboration Agreement, which altered key aspects of the collaboration pertaining to the HIV therapeutic. Most importantly, the Amended and Restated Collaboration Agreement allocated additional research and development responsibility to the Company with respect to the Company’s HIV candidate and provided for additional funding by Gilead of such research and development activities as well as increased later stage development and commercial milestone payments. Under the Gilead Collaboration Agreement, the Company granted Gilead an exclusive, royalty-bearing license to the Company’s technology platforms. Upon entering into the agreement in June 2018, the Company received a non-refundable $10.0 million upfront payment from Gilead and upon signing of the Restated Gilead Collaboration Agreement in February 2022, the Company received a program initiation fee of $15.0 million. Gilead is also obligated to make additional payments to the Company upon the achievement of pre-clinical, development and commercial milestones. The development milestones amount to $140.0 million for the HBV program, and up to $172.5 million for the HIV program, inclusive of a $10.0 million program completion fee, payable upon Gilead’s exercise of the option to pursue further development activities post Phase 1b. The commercial milestones amount to a total of $50.0 million for the HBV program, and $65.0 million for the HIV program. Additionally, Gilead is obligated to pay royalties on net sales for each program. Payments from Gilead generally have a 60-day payment term. The $10.0 million upfront payment, the $15.0 million initiation fee and $13.0 million in milestone payments were initially recorded as deferred revenue in the consolidated balance sheet and are recognized as revenue when revenue recognition criteria are met. As of September 30, 2024, $7.0 million of such payments were still recorded as a liability in deferred revenues, current and non-current. As of December 31, 2023, $7.5 million of upfront and milestone payments were included as a liability in deferred revenues, current and non-current. Approximately 38% of deferred revenue is expected to be recognized as revenue in the remainder of 2024, 51% in 2025 and the remaining 11% in 2026. In the three months ended September 30, 2024, the Company recognized $4.4 million of the milestone and initiation payments that were originally recorded as deferred revenue. Furthermore, the Company recognized $0.3 million of revenue from cost reimbursements for research and development services. In the three months ended September 30, 2023, the Company recognized $1.2 million of the upfront and milestone payments that were originally recorded as deferred revenue. Furthermore, the Company recognized $0.5 million of revenue from cost reimbursements for research and development services. In the nine months ended September 30, 2024, the Company recognized $5.7 million of the milestone and initiation payments that were originally recorded as deferred revenue. Furthermore, the Company recognized $0.5 million of revenue from cost reimbursements for research and development services. In the nine months ended September 30, 2023, the Company recognized $3.8 million of the upfront and milestone payments that were originally recorded as deferred revenue. Furthermore, the Company recognized $1.3 million of revenue from cost reimbursements for research and development services. Sublicense fees payable to certain licensors of technologies upon the receipt of the deferred upfront and milestone payments, were capitalized as a contract asset and will be amortized over the period in which the revenue from the triggering payment is recognized. As of September 30, 2024 and December 31, 2023, the contract asset relating to the sublicense payment was $0.2 million and $0.1 million, respectively, and there was no liability relating to sublicense payment. Roche Collaboration and License Agreement In October 2022, the Company entered into the Roche Collaboration Agreement whereby the Company and Roche agreed to collaborate with respect to the development of novel arenaviral immunotherapies for KRAS-mutated cancers and, potentially, a second, novel arenaviral immunotherapeutic program targeting specific undisclosed cancer antigens. In January 2024, Roche provided written notice of the termination of the Roche Collaboration Agreement to the Company. The termination was made according to Roche’s right to terminate without cause, acknowledging that the Company had met all go-forward criteria under the agreement. Pursuant to the terms of the Roche Collaboration Agreement, following the termination notice, the Roche Collaboration Agreement terminated on April 25, 2024. Under the terms of the original Roche Collaboration Agreement, the Company had granted Roche an exclusive, royalty-bearing license to the Company’s technology platforms for KRAS-mutated cancers, and an option right to exclusively license a second, novel arenaviral immunotherapeutic program targeting undisclosed cancer antigens. Upon the termination effective date of April 25, 2024, the Company regained full control of the associated intellectual property portfolio and full collaboration and licensing rights for this program. Upon signing the Roche Collaboration Agreement in October 2022, the Company received a non-refundable upfront payment of $25.0 million. This upfront payment, a $10.0 million milestone payment received in the three months ended March 31, 2023, and a $10.0 million milestone payment received in the three months ended June 30, 2024 were considered as part of the transaction price and were recognized as revenue when revenue recognition criteria were met over the period in which services were performed. As of September 30, 2024, no liabilities were recorded in deferred revenues, current and non-current. As of December 31, 2023, $26.8 million of such payments were included as a liability in deferred revenues, current and non-current. The Company considered the termination by Roche as a contract modification of the combined performance obligations and the transaction price. The modification was accounted for on a cumulative catch-up basis, applying the revised percent of completion to the revised transaction price, resulting in an immediate increase of revenue in the period of the modification. The transaction price was recognized as revenue over the remaining performance period using updated total estimated research and development costs. The remaining liability included in deferred revenues was recognized in the three months ended June 30, 2024. Accordingly, the Company recognized in the three months ended September 30, 2024 no revenue. Furthermore, the Company recognized $0.3 million of revenue from cost reimbursements for activities related to the preparation of a first in human trial. In the nine months ended September 30, 2024, the Company recognized revenues of $36.3 million of the upfront and milestone payments that were originally recorded as deferred revenue. Furthermore, the Company recognized $0.1 million of revenue from cost reimbursements for activities related to the preparation of a first in human trial of HB-700. In the nine months ended September 30, 2023, the Company recognized $7.3 million of the upfront and milestone payments that were originally recorded as deferred revenue. Furthermore, the Company recognized $0.3 million of revenue from cost reimbursements for activities related to the preparation of a first in human trial. Sublicense fees payable to certain licensors of technologies upon the receipt of the deferred upfront and milestone payments, were capitalized as a contract asset and will be amortized over the period in which the revenue from the triggering payment is recognized. As of September 30, 2024 there was no contract asset and no liability relating to sublicense payments. As of December 31, 2023 the contract asset was $2.0 million and there was no liability relating to sublicense payments.

Restructuring

Restructuring	9 Months Ended
Restructuring	Sep. 30, 2024
Restructuring
Restructuring	4. Restructuring On January 29, 2024, the Company announced and began implementing its decision to prioritize the clinical development of its eseba-vec (formerly HB-200) program for the treatment of HPV16+ head and neck cancers and its two Gilead-partnered infectious disease programs and to pause development activities related to HB-300 and most of its preclinical research activities. In connection with this strategic refocus, the Company’s board of directors approved a restructuring plan to rebalance the Company’s cost structure, which originally included a reduction of the Company’s workforce by approximately 30% and the discontinuation of the Company’s GMP manufacturing facility project. This original part of the restructuring plan was completed by the end of the second quarter of 2024 and the Company recorded restructuring charges of $1.3 million in the six months ended June 30, 2024. During the third quarter of 2024, the Company started an enterprise-wide initiative intended to improve its business through specialized organizational programs that include targeted cost-savings and continued to take actions to implement further restructuring actions, which included a further reduction of the Company’s workforce by another approximately 20%. These continued restructuring actions are expected to be substantially completed by the end of the first quarter of 2025. The restructuring charges recorded for the continued restructuring actions for the three months ended September 30, 2024 are $ 0.9 As a result of the restructuring plan and the enterprise-wide initiative, the Company incurred the following charges which were included within Restructuring expense in the condensed consolidated statements of operations and comprehensive loss. The following table summarizes the effect of the restructuring charges (in thousands): Three months ended September 30, Nine months ended September 30, 2024 2023 2024 2023 Cash charges Severance and other personnel expenses 832 — 2,070 — Professional fees and other related charges 46 — 131 — Total $ 878 $ — $ 2,201 $ — The following table summarizes a roll-forward of cash restructuring-related liabilities, which are included within Accrued expenses and other current liabilities in the condensed consolidated balance sheets (in thousands): Severance and other personnel costs Professional fees and other related charges Total Balance as of December 31, 2023 $ — $ — $ — Severance and other personnel costs, professional fees and other related charges 2,070 131 2,201 Total cash charges (1,231) (82) (1,313) Balance as of September 30, 2024 $ 839 $ 49 $ 888

Impairment

Impairment	9 Months Ended
Impairment	Sep. 30, 2024
Restructuring
Impairment	5. Impairment As a result of the targeted cost-savings, restructuring actions, and strategic considerations preceeding the adoption of the restructuring plan, which included the termination of a part of the Company’s rented office and laboratory space in Vienna, Austria, the Company assessed the recoverability of the long-lived assets relating to the laboratory equipment at September 30, 2024, and determined that the undiscounted cash flows of certain asset groups were below the carrying values, indicating impairment. The carrying values of the assets were written down to their estimated fair value, which was determined based on the cost approach. The impairment test was performed as of September 30, 2024 using Level 3 inputs including assumptions and estimates for the current replacement costs of similar assets adjusted for estimated depreciation and deterioration of the existing equipment and economic obsolescence. The following table summarizes the effect of the non-cash impairment charges (in thousands): Three months ended September 30, Nine months ended September 30, 2024 2023 2024 2023 Non-cash impairment charges Asset write-offs $ (172) $ — $ (172) $ — Total non-cash impairment charges $ (172) $ — $ (172) $ —

Fair Value of Financial Assets

Fair Value of Financial Assets	9 Months Ended
Fair Value of Financial Assets	Sep. 30, 2024
Fair Value of Financial Assets
Fair Value of Financial Assets	6. Fair Value of Financial Assets The following tables present information about the Company’s financial assets measured at fair value on a recurring basis and indicating the level of the fair value hierarchy utilized to determine such fair values (in thousands): Fair Value Measurement at September 30, 2024 Level 1 Level 2 Level 3 Total Cash equivalents: Money market funds $ 49,744 $ — $ — $ 49,744 Total $ 49,744 $ — $ — $ 49,744 Fair Value Measurement at December 31, 2023 Level 1 Level 2 Level 3 Total Cash equivalents: Money market funds $ 91,084 $ — $ — $ 91,084 Total $ 91,084 $ — $ — $ 91,084 During the nine months ended September 30, 2024, there were 1 3

Property, plant and equipment,

Property, plant and equipment, net	9 Months Ended
Property, plant and equipment, net	Sep. 30, 2024
Property, plant and equipment, net.
Property, plant and equipment, net	7. Property, plant and equipment, net Property, plant and equipment, net consisted of the following (in thousands): September 30, December 31, 2024 2023 Land $ 2,040 $ 2,025 Leasehold improvements 3,332 3,300 Construction in progress 23 212 Laboratory equipment 8,748 8,722 Furniture and fixtures 655 654 Computer equipment and software 2,523 2,652 Property and equipment, gross 17,321 17,565 Less: Accumulated depreciation (10,461) (9,823) Property and equipment, net $ 6,860 $ 7,742 As a result of the termination of rented laboratory space (see Note 5) the Company determined that the estimated undiscounted future cash flows for certain assets used in affected laboratories were less than their carrying values. The Company therefore recognized an impairment charge of $ 0.2 There were no

Receivable research incentive

Receivable research incentive	9 Months Ended
Receivable research incentive	Sep. 30, 2024
Receivable research incentive
Receivable research incentive	8. Receivable research incentive The Company participates in a research incentive program provided by the Austrian government under which it is entitled to reimbursement of a percentage of qualifying research and development expenses and capital expenditures incurred in Austria. Submissions for reimbursement under the program are submitted annually. Incentive amounts are generally paid out during the calendar year that follows the year of the expenses but remain subject to subsequent examinations by the responsible authority. Reimbursements received in excess of the recognized receivable research incentive for a certain period are recorded within other long-term liabilities for potential repayment until such time that an audit has taken place, upon expiration of the potential reclaim period, or when it is no longer probable that a reclaim will happen. The years 2018 to present remain open to examination by the authorities. Furthermore, the Company participated in the life sciences research and development program provided by the New York State government under which it was entitled to reimbursement of a percentage of qualifying research and development expenses in New York State up to $0.5 million per year for the years 2019 to 2021. The Company also participates in the New York City biotechnology tax credit program, according to which certain expenses for business in the biotechnology field in New York City limited to $0.25 million per year for three consecutive years from January 1, 2023 to December 31, 2025 are incentivized. As of September 30, 2024, the Company recognized receivables of $ 24.7 related to the Austrian research incentive program, $1.4 million related to the New York State life sciences research and development program and $0.1 million related to the New York City biotechnology tax credit program. During the three months ended September 30, 2024 and 2023, the Company recorded $2.2 million and $2.9 million, respectively, of income related to the incentive program within the Company’s condensed consolidated statements of operations and comprehensive loss as part of the grant income related to the Austrian incentive program. Research incentives depend on the eligible research and development expenses of the respective period. During the nine months ended September 30, 2024 and 2023, the Company recorded $6.9 million and $7.2 million, respectively, of income related to the incentive program within the Company’s condensed consolidated statements of operations and comprehensive loss as part of the grant income related to the Austrian incentive program. Research incentives depend on the eligible research and development expenses of the respective period.

Accrued expenses and other curr

Accrued expenses and other current liabilities	9 Months Ended
Accrued expenses and other current liabilities	Sep. 30, 2024
Accrued expenses and other current liabilities
Accrued expenses and other current liabilities	9. Accrued expenses and other current liabilities Accrued expenses and other current liabilities consisted of the following (in thousands): September 30, December 31, 2024 2023 Salaries and bonuses 4,816 5,665 Social security contributions 285 340 Unearned grant income — 52 Accrued external research and development expenses 5,685 4,594 Accrued external general and administration expenses 884 292 Accrued for property and equipment acquisitions — 14 Accrued for restructuring expenses 888 — Income taxes — 367 Other accruals and liabilities 515 777 $ 13,073 $ 12,101

Loans payable

Loans payable	9 Months Ended
Loans payable	Sep. 30, 2024
Loans payable
Loans payable	10. Loans payable As of September 30, 2024 and December 31, 2023, loans payable consisted of the following (in thousands): September 30, December 31, 2024 2023 Loans from FFG $ — $ 1,172 Unamortized debt discount — (52) Total loans payable, net $ — $ 1,120 In connection with the funding agreements with the Austrian Research Promotion Agency, ( Österreichische Forschungsförderungsgesellschaft, The FFG Loans bear interest at rates that are below market rates of interest. The Company accounted for the imputed benefit arising from the difference between an estimated market rate of interest and the rate of interest charged by FFG as grant income from FFG. On the date that FFG loan proceeds are received, the Company recognized the portion of the loan proceeds allocated to grant funding as a discount to the carrying value of the loan and as unearned income, which was recognized as grant income over the term of the funding agreement. As of September 30, 2024, the Company has no

Common stock, Class A common st

Common stock, Class A common stock and convertible preferred stock	9 Months Ended
	Sep. 30, 2024
Common stock, Class A common stock and convertible preferred stock
Common stock, Class A common stock and convertible preferred stock	11. Common stock, Class A common stock and convertible preferred stock The Company’s capital structure consists of common stock, Class A common stock and preferred stock. On July 9, 2024, the Company effected a reverse stock split of the outstanding shares of its common stock on a one-for-ten basis (see Note 2). As of September 30, 2024, the Company was authorized to issue 40,000,000 shares of common stock, 3,900,000 shares of Class A common stock and 10,000,000 shares of preferred stock. The Company has designated 2,978 of the 10,000,000 authorized shares of preferred stock as non-voting Series A convertible preferred stock, 15,800 of the 10,000,000 authorized shares of preferred stock as non-voting Series A-1 convertible preferred stock and 15,268 of the 10,000,000 authorized shares of preferred Class A Series A Series A-1 Series A-2 On June 5, 2023, the Company closed a public offering of 2,290,077 (22,900,768 before the Reverse Stock Split) shares of its common stock and 15,268 shares of Series A-2 convertible preferred stock at a public offering price of $13.10 and $1,310.00 per share, respectively, for net proceeds of $46.2 million after deducting underwriting discounts and commissions and offering expenses. On February 15, 2022, the Company entered into a stock purchase agreement with Gilead (“Stock Purchase Agreement”), that requires Gilead, at the Company’s option, to purchase up to $35.0 million of the Company’s common stock. On February 15, 2022, Gilead purchased an initial amount of 166,666 (1,666,666 before the Reverse Stock Split) shares of the Company’s common stock in exchange for $5.0 million in cash at a purchase price per share equal to $30.00. On December 20, 2023, the parties amended and restated the Stock Purchase Agreement (the “Amended Stock Purchase Agreement”) and Gilead purchased 1,500,000 (15,000,000 before the Reverse Stock Split) shares of the Company’s common stock in exchange for approximately $21.3 million in cash at a purchase price per share equal to $14.167. Pursuant to the terms of the Amended Stock Purchase Agreement, the Company may require Gilead to purchase the balance of the $8.75 million of common stock as pro-rata participation in potential future equity raises. The Company’s right to sell shares of its common stock to Gilead is subject to specified limitations, including a limitation that prevents the Company from requesting purchases of shares of common stock by Gilead that would result in a beneficial ownership of more than 19.9% of the total number of outstanding shares of common stock by Gilead. The Company has three series of preferred stock authorized, issued and outstanding as of September 30, 2024: Series A convertible preferred stock, Series A-1 convertible preferred stock and Series A-2 convertible preferred stock. Shares of Series A, Series A-1 and Series A-2 convertible preferred stock may be independently converted into common stock. Holders of Series A, Series A-1 and Series A-2 convertible preferred stock have equal rights, powers and privileges. Holders of common stock are entitled to one vote for each share held on all matters submitted to a vote of the stockholders. The holders of Class A common stock and Series A, Series A-1 and Series A-2 convertible preferred stock are not entitled to vote, except as required by law. The holders of common stock and Class A common stock do not have any cumulative voting rights. Each holder of Class A common stock has the right to convert each ten shares of Class A common stock into one share of common stock at such holder's election. Each holder of Series A, Series A-1 and Series A-2 convertible preferred stock has the right to convert each share of Series A, Series A-1 and Series A-2 convertible preferred stock into 100 shares of common stock at any time at the holder’s option, provided that the holder will be prohibited, subject to certain exceptions, from converting Series A, Series A-1 and Series A-2 convertible preferred stock into shares of the Company’s common stock if, as a result of such conversion, the holder, together with its affiliates, would own more than 9.99% of the total number of shares of the Company’s common stock then issued and outstanding. Holders of common stock and Class A common stock are entitled to receive ratably any dividends declared by the board of directors out of funds legally available for that purpose, subject to any preferential dividend rights of any outstanding preferred stock. Holders of Series A, Series A-1 and Series A-2 preferred stock will be entitled to receive dividends at a rate equal to (on an as-if-converted-to-common stock basis), and in the same form and manner as, dividends actually paid on shares of the Company’s common stock. Holders of common stock and Class A common stock have no preemptive rights, conversion rights, or other subscription rights or redemption or sinking fund provisions. In the event of a liquidation, dissolution, or winding up of the Company, holders of the Company’s Series A, Series A-1 and Series A-2 convertible preferred stock will receive a payment equal to $0.001 per share of Series A, Series A-1 and Series A-2 convertible preferred stock before any proceeds are distributed to the holders of common stock. Then, holders of common stock and Class A common stock will be entitled to share ratably in all assets remaining after payment of all debts and other liabilities. There were 370 shares of Series A convertible preferred stock, 10,800 shares of Series A-1 convertible preferred stock and 15,268 shares of Series A-2 convertible preferred stock outstanding as of September 30, 2024 and December 31, 2023, respectively. In May 2023 certain of the Company’s stockholders elected to convert an aggregate of 1,327 shares of Series A convertible preferred stock and an aggregate of 5,000 shares of Series A-1 convertible preferred stock owned by such holders into an aggregate of 632,700 (6,327,000 before the Reverse Stock Split) shares of the Company’s common stock.

Stock-based compensation

Stock-based compensation	9 Months Ended
Stock-based compensation	Sep. 30, 2024
Stock-based compensation
Stock-based compensation	12. Stock-based compensation 2018 Stock Option and Grant Plan In June 2018, the Company’s board of directors approved the 2018 Stock Option and Grant Plan. Options granted under the 2018 Stock Option and Grant Plan generally vest over four years, with 25% of the options vesting upon the first anniversary of the grant date and the remaining 75% of the options vesting in 12 equal quarterly installments following the first anniversary of the grant date, provided the option holder continues to have an employment or service relationship with the Company on each vesting date. The options expire on the 10 th 2019 Stock Option and Incentive Plan On April 1, 2019, the Company’s stockholders approved the 2019 Stock Option and Incentive Plan, which became effective as of the effective date of the registration statement in connection with the Company’s IPO. The plan provides for the grant of shares of restricted stock, long term incentive awards, stock options or other equity-based awards. As of September 30, 2024, the maximum number of shares of the Company’s common stock that may be issued under the Company’s 2019 Stock Option and Incentive Plan was 1,202,548 shares which shall be cumulatively increased on January 1 of each year by up to 4.0% of the then outstanding number of shares of common stock and Class A common stock. Options granted under the 2019 Stock Option and Incentive Plan generally vest over four years, with 25% of the options vesting upon the first anniversary of the grant date and the remaining 75% of the options vesting in 12 equal quarterly installments following the first anniversary of the grant date, provided the option holder continues to have an employment or service relationship with the Company on each vesting date. Initial options granted to non-executive directors upon their election generally vest over a three-year term with 33% of the options vesting upon the first anniversary of the grant date and the remaining 67% of the options vesting in eight equal quarterly installments following the first anniversary of the grant date. Annual option re-grants to non-executive directors generally vest on the earlier of the first anniversary of the grant date and the next annual meeting of stockholders. The options expire on the 10 th On August 7, 2023, the Company’s board of directors approved a one-time offer to eligible non-executive, non-director employees to exchange certain outstanding stock options for new stock options with modified terms. Under the stock option exchange program (the “Offer”), the Company offered to exchange certain out-of-the-money stock options for new stock options at an exchange ratio of between 1.75 and 2.50 surrendered options for one new option exercisable for shares of common stock with a lower exercise price and extended vesting terms. Pursuant to the Offer, a total of 82 eligible participants tendered, and the Company accepted for cancellation, stock options to purchase an aggregate of 54,323 shares of the Company’s common stock with exercise prices between $69.00 and $140.00. The eligible options that were accepted for cancellation represented approximately 86.6% of the total shares of common stock underlying all of the eligible options. In accordance with the terms and conditions of the Offer, on September 12, 2023, the Company issued new options to purchase an aggregate of 27,376 shares of common stock in exchange for the cancellation of the tendered eligible options. The exercise price per share of each new option granted in the Offer is $10.00. New options issued for previously vested stock options vest on the first anniversary of the grant date and new options issued for previously unvested stock options vest over a three-year term in twelve equal quarterly installments. The stock option exchange offer resulted in incremental stock-based compensation expense of $0.1 million, recognized using the graded-vesting method over the remaining requisite service period of the new stock options. 2023 Inducement Plan On April 7, 2023, the Company’s board of directors adopted the Company’s 2023 Inducement Plan (the “2023 Inducement Plan”) pursuant to which the Company reserved 50,000 shares of common stock for issuance under the 2023 Inducement Plan. The 2023 Inducement Plan provides for the grant of non-statutory stock options to eligible individuals. In accordance with Nasdaq Marketplace Rule 5635(c)(4), awards under the 2023 Inducement Plan may only be made to individuals not previously employees or directors of the Company (or following such individuals’ bona fide period of non-employment with the Company), as an inducement material to the individuals’ entry into employment with the Company. Awards granted under the 2023 Inducement Plan must be approved by either a majority of the Company’s independent directors or the compensation committee of the Company’s board of directors. As of September 30, 2024, the Company had 10,000 shares of its common stock available for future issuance under the 2023 Inducement Plan. The following table presents a summary of awards outstanding: As of September 30, 2024 2018 Plan 2019 Plan Inducement Awards Total Granted and outstanding awards: Stock options 73,935 964,206 40,000 1,078,141 Total 73,935 964,206 40,000 1,078,141 Stock option valuation The Company estimates the option’s fair value on the date of grant using the Black-Scholes option-pricing model. Black-Scholes utilizes assumptions related to expected term, volatility, the risk-free interest rate, the dividend and employee exercise behavior. Forfeitures are accounted for when they occur. Expected volatilities utilized in the Black-Scholes model are based on historical volatilities of a group of comparable companies. The group of representative companies have characteristics similar to the Company, including the stage of product development and focus on the life science industry. Management believes that this represents the most accurate basis for estimating expected future volatilities under the current conditions. The risk-free interest rate is derived from the yields for U.S. Treasuries with a remaining term approximating the expected life of the options. The expected term represents the period of time that the options granted are expected to be outstanding. The following table summarizes the assumptions used in the Black-Scholes option-pricing model for estimating the fair value of stock options granted during: Three months ended September 30, Nine months ended September 30, 2024 2023 2024 2023 Risk-free interest rate 4.12 % 4.48 % 4.52 % 3.70 % Expected term (in years) 5.9 4.4 6.0 5.7 Expected volatility 103.0 % 90.6 % 101.5 % 93.5 % Expected dividends — % — % — % — % For the 2024 and 2023 grants, the Company used the simplified method in developing an estimate of the expected term due to a lack of historical exercise data. Stock option activity The following table summarizes the Company’s stock option activity since January 1, 2024 (in thousands, except share and per share amounts): Weighted Weighted Average Average Remaining Aggregate Number of Exercise Contractual Intrinsic Shares Price Term Value (in years) Outstanding as of December 31, 2023 810,942 $ 42.76 7.4 $ 486 Granted 429,781 7.53 Exercised — — Forfeited (162,582) 29.99 Outstanding as of September 30, 2024 1,078,141 $ 30.64 5.7 $ 224 Options exercisable as of September 30, 2024 497,606 $ 54.79 3.9 $ 224 Options unvested as of September 30, 2024 580,535 $ 9.94 7.2 $ — The aggregate intrinsic value of stock options was calculated as the difference between the exercise price of the stock options and the fair value of the Company’s common stock for those stock options that had exercise prices lower than the fair value of the Company’s common stock. The fair value per common stock used for calculating the intrinsic values as of September 30, 2024 and December 31, 2023, was $4.30 and $8.10, respectively. No cash was received from stock option exercise under share-based payment arrangements for the nine months ended September 30, 2024. Cash received from stock option exercises under share-based payment arrangements for the nine months ended September 30, 2023 was $1 thousand. Restricted Stock Units In the three months ended September 30, 2024, the Company granted restricted stock units with time-based vesting conditions to officers. The restricted stock units vest in two equal installments in July 2025 and in July 2026. The Company measures the fair value of restricted stock units on the date of grant using the underlying common stock fair value. Expenses are recorded using the graded-vesting method. The table below summarizes the Company’s restricted stock unit activity since December 31, 2023: Weighted Average Grant Number of Date Fair Shares Value Outstanding as of December 31, 2023 — $ — Granted 178,570 6.44 Vested — — Forfeited — — Outstanding as of September 30, 2024 178,570 $ 6.44 Stock-based compensation Stock-based compensation expense was classified in the condensed consolidated statements of operations and comprehensive loss as follows (in thousands): Three months ended September 30, Nine months ended September 30, 2024 2023 2024 2023 Research and development expenses (1) $ 248 $ 216 $ 251 $ 764 General and administrative expenses (1) 691 358 898 1,164 $ 939 $ 574 $ 1,149 $ 1,928 (1)

Income taxes

Income taxes	9 Months Ended
Income taxes	Sep. 30, 2024
Income taxes
Income taxes	13. Income taxes Income tax expense during the nine months ended September 30, 2024 and September 30, 2023 resulted from minimum tax obligations in Austria, and U.S. federal and state income tax as well as minimum tax obligations in Austria, respectively. During the three and nine months ended September 30, 2024 and 2023, the Company recorded no income tax benefits for the net operating losses incurred due to its uncertainty of realizing a benefit from those items. The Company’s losses before income taxes were generated in the United States and Austria. The Company has evaluated the positive and negative evidence bearing upon its ability to realize the deferred tax assets resulting from its net operating loss carryforwards. Management has considered the Company’s history of cumulative net losses incurred since inception and its lack of commercialization of any products or generation of any revenue from product sales since inception and has concluded that it is more likely than not that the Company will not realize the benefits of its deferred tax assets. Accordingly, a full valuation allowance has been established against the deferred tax assets as of September 30, 2024 and December 31, 2023. Management reevaluates the positive and negative evidence at each reporting period.

Commitments and contingencies

Commitments and contingencies	9 Months Ended
Commitments and contingencies	Sep. 30, 2024
Commitments and contingencies
Commitments and contingencies	14. Commitments and contingencies Operating and Finance Leases The Company leases for real estate, including office and laboratory space, and has entered into various other agreements with respect to assets used in conducting its business. The Company is required to maintain a cash balance of $0.2 million to secure letters of credit associated with real estate leases. This amount was classified as non-current restricted cash in the Company’s condensed consolidated balance sheet as of September 30, 2024. As of September 30, 2024 and December 31, 2023, the Company’s operating lease right-of-use assets were $ 2.9 1.2 2.8 Contract manufacturing arrangements The Company has entered into arrangements with contract manufacturing organizations (“CMOs”) for manufacturing of materials for research and development purposes, including manufacturing of clinical trial materials. These contracts generally provide for non-cancellable obligations or cancellation penalties depending on the time of cancellation. As of September 30, 2024, the Company’s total non-cancellable obligations under contracts with CMOs were $ 5.9 million, of which $ 1.7 million relates to 2024 (remaining three months) deliverables, and $ 4.2 million relates to 2025 deliverables. Intellectual property licenses The Company has entered into certain license agreements under which it is obligated to make milestone payments upon the achievement of certain development and regulatory milestones, to pay royalties on net sales of licensed products, and to pay a percentage of the sublicense fees which the Company receives from its sublicensees. In the three and nine months ended September 30, 2024, the Company recorded $0.6 million and $3.5 million, respectively, in licensing fees related to intellectual property licenses as research and development expenses. The amount is mainly related to the upfront payment and milestone payments received by the Company under the Gilead Collaboration Agreement and the Roche Collaboration Agreement. The amount recognized as expenses has been agreed to by the licensors but calculation of sublicensing fees on future payments may be subject to interpretation and may change until agreed to by the receiving party. Indemnification agreements In the ordinary course of business, the Company may provide indemnification of varying scope and terms to vendors, lessors, business partners and other parties with respect to certain matters including, but not limited to, losses arising out of breach of such agreements or from intellectual property infringement claims made by third parties. In addition, the Company has entered into indemnification agreements with members of its board of directors and senior management that will require the Company, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors or officers. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is, in many cases, unlimited. To date, the Company has not incurred any material costs as a result of such indemnifications. The Company is not aware of any claims under indemnification arrangements, and it has not accrued any liabilities related to such obligations in its condensed consolidated financial statements as of September 30, 2024 or December 31, 2023. Legal proceedings The Company is not currently a party to any material legal proceedings. From time to time, the Company may become involved in litigation or legal proceedings relating to claims arising in the ordinary course of business. At each reporting date, the Company evaluates whether or not a potential loss amount or a potential range of loss is probable and reasonably estimable under the provisions of the authoritative guidance that addresses accounting for contingencies. The Company expenses the costs related to such legal proceedings as incurred.

Net loss per share

Net loss per share	9 Months Ended
Net loss per share	Sep. 30, 2024
Net loss per share
Net loss per share	15. Net loss per share The following table sets forth the computation of the basic and diluted net loss per share attributable to common stockholders (in thousands, except for share and per share amounts): Three months ended September 30, Nine months ended September 30, 2024 2023 2024 2023 Numerator: Net loss $ (13,841) $ (19,066) $ (18,553) $ (56,762) Denominator: Weighted-average common shares outstanding, basic and diluted 9,894,974 8,395,011 9,894,974 6,793,358 Weighted-average Series A convertible preferred shares outstanding, basic and diluted, presented as if converted into common stock (1) 37,000 37,000 37,000 99,218 Weighted-average Series A-1 convertible preferred shares outstanding, basic and diluted, presented as if converted into common stock (1) 1,080,000 1,080,000 1,080,000 1,310,769 Weighted-average Series A-2 convertible preferred shares outstanding, basic and diluted, presented as if converted into common stock (1) 1,526,800 1,526,800 1,526,800 654,343 Total number of shares used to calculate net loss per share, basic and diluted 12,538,774 11,038,811 12,538,774 8,857,688 Net loss per share, basic and diluted $ (1.10) $ (1.73) $ (1.48) $ (6.41) (1) one shares common preferred stock, 1,080,000 shares of the Company’s common stock were issuable upon conversion of Series A-1 convertible preferred stock and 1,526,800 shares of the Company’s common stock were issuable upon conversion of Series A-2 convertible preferred stock (see Note 11). Since the Company was in a loss position for all periods presented, basic net loss per share is the same as diluted net loss per share for all periods as the inclusion of all potential common shares (common stock and Class A common stock) outstanding would have been anti-dilutive. Potentially dilutive securities that were not included in the diluted per share calculations because they would be anti-dilutive were as follows: Three and nine months ended September 30, 2024 2023 Options issued and outstanding 1,078,141 836,221 Unvested restricted stock units 178,570 — Total 1,256,711 836,221

Related Parties

Related Parties	9 Months Ended
Related Parties	Sep. 30, 2024
Related Parties
Related Parties	16. Related Parties Effective September 15, 2023, Malte Peters, a member of the Company’s board of directors, agreed to lead the Company’s clinical activities as ad interim Senior Clinical Advisor. No expense was recorded during the three months ended September 30, 2024. During the nine months ended September 30, 2024, the Company recorded expense of $0.2 million related to a consultancy services agreement entered into with Dr. Peters, effective September 15, 2023. The consultancy services agreement was terminated on March 31, 2024.

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($)	3 Months Ended						9 Months Ended		12 Months Ended
Pay vs Performance Disclosure - USD ($)	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Pay vs Performance Disclosure
Net Income (Loss)	$ (13,841,000)	$ (19,095,000)	$ 14,383,000	$ (19,066,000)	$ (18,016,000)	$ (19,680,000)	$ (18,553,000)	$ (56,762,000)	$ (81,600,000)

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Sep. 30, 2024
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
Rule 10b5-1 Arrangement Modified	false
Non-Rule 10b5-1 Arrangement Modified	false

Summary of significant accoun_2

Summary of significant accounting policies (Policies)	9 Months Ended
Summary of significant accounting policies (Policies)	Sep. 30, 2024
Summary of significant accounting policies
Basis of presentation	Basis of presentation The Company’s condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). The accompanying condensed consolidated financial statements include the accounts of the Company and its wholly owned subsidiary. All intercompany accounts and transactions have been eliminated in consolidation. The consolidated balance sheet as of December 31, 2023 was derived from audited financial statements but does not include all disclosures required by GAAP. The accompanying condensed consolidated balance sheet as of September 30, 2024, the condensed consolidated statements of operations, and comprehensive loss for the three and nine months ended September 30, 2024 and 2023, the condensed consolidated statement of convertible preferred stock and stockholders’ equity for the three and nine months ended September 30, 2024 and 2023 and the condensed consolidated statements of cash flows for the nine months ended September 30, 2024 and 2023 are unaudited. The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited annual consolidated financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair statement for interim reporting. Certain information and footnote disclosures typically included in annual financial statements prepared in accordance with GAAP have been condensed or omitted. Accordingly, these unaudited interim condensed consolidated financial statements should be read in conjunction with the Company’s audited financial statements for the year ended December 31, 2023 included in the Company’s Annual Report on Form 10-K, filed with the Securities and Exchange Commission (“SEC”)
Going concern	Going concern At each reporting period, in accordance with Accounting Standards Codification ("ASC") 205-40, Going Concern, the Company evaluates whether there are conditions or events that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that the financial statements are issued. The Company’s evaluation entails analyzing prospective operating budgets and forecasts for expectations of the Company’s cash needs and comparing those needs to the current cash and cash equivalent balances. The Company is required to make certain additional disclosures if it concludes substantial doubt exists and it is not alleviated by the Company’s plans or when its plans alleviate substantial doubt about the Company’s ability to continue as a going concern. This evaluation initially does not take into consideration the potential mitigating effect of management’s plans that have not been fully implemented as of the date the condensed consolidated financial statements are issued. When substantial doubt exists under this methodology, management evaluates whether the mitigating effect of its plans sufficiently alleviates substantial doubt about the Company’s ability to continue as a going concern. The mitigating effect of management’s plans, however, is only considered if both (1) it is probable that the plans will be effectively implemented within one year after the date that the condensed consolidated financial statements are issued, and (2) it is probable that the plans, when implemented, will mitigate the relevant conditions or events that raise substantial doubt about the entity’s ability to continue as a going concern within one year after the date that these condensed consolidated financial statements are issued. In performing its analysis, management excluded certain elements of its operating plan that cannot be considered probable. Under ASC 205-40, the future receipt of potential funding from future partnerships, equity or debt issuances, the potential milestones from the Gilead Collaboration Agreement and potential reductions in force cannot be considered probable at this time because these plans are not entirely within the Company’s control and/or have not been approved by the Board of Directors as of the date of these condensed consolidated financial statements. Since inception, the Company’s activities have consisted primarily of performing research and development to advance its technologies. The Company is still in the development phase and has not been marketing its technologies to date. Through September 30, 2024, the Company has funded its operations with proceeds from sales of common stock, sales of convertible preferred stock, sales of redeemable convertible preferred stock, collaboration and licensing agreements, grants and borrowings under various agreements with foreign public funding agencies. Since inception, the Company has incurred recurring losses, including a net loss of $ 18.6 387.8 These condensed consolidated financial statements have been prepared assuming that the Company will continue as a going concern, which contemplates the realization of assets and the settlement of liabilities and commitments in the normal course of business. The condensed consolidated financial statements do not reflect any adjustments relating to the recoverability and classification of assets or the amounts and classification of liabilities that might result from the outcome of the uncertainties described above.
Reverse Stock Split	Reverse stock split On July 9, 2024, the Company effected a reverse stock split of the outstanding shares of its common stock on a one-for-ten ( 1 one
Use of estimates	Use of estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue, income and expenses during the reporting periods. Significant estimates and assumptions reflected in these condensed consolidated financial statements include, but are not limited to, the recognition of revenue and income, the accrual of research and development expenses and general and administrative expenses, the present value of lease right of use assets and corresponding liabilities, the valuation of stock-based awards, the valuation of current loans payable, the impairment of long-lived assets and going concern. The Company bases its estimates on historical experience, known trends and other market-specific or other relevant factors that it believes to be reasonable under the circumstances. On an ongoing basis, management evaluates its estimates as there are changes in circumstances, facts and experience. As of the date of issuance of these unaudited condensed consolidated financial statements, the Company is not aware of any specific event or circumstance that would require the Company to update estimates, judgments or revise the carrying value of any assets or liabilities. Actual results may differ from those estimates or assumptions.
Deferred offering costs	Deferred offering costs The Company capitalizes certain legal, professional accounting and other third-party fees that are directly associated with in-process equity financings as deferred offering costs until such financings are consummated. After consummation of an equity financing, these costs are recorded in stockholders’ equity as a reduction of the additional paid-in capital on a pro-rata basis generated as a result of the offering. Should the in-process equity financing be abandoned, the deferred offering costs will be expensed immediately as a charge to operating expenses in the condensed consolidated statements of operations and comprehensive loss.
Concentrations of credit risk and of significant suppliers	Concentrations of credit risk and of significant suppliers Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash, cash equivalents and short-term bank deposits held with banks in excess of publicly insured limits. For the three and nine months ended September 30, 2024 and September 30, 2023 the net proceeds from the Company’s offerings have been deposited in interest-bearing bank accounts with two of the largest investment grade U.S. financial institutions and have been partially invested in money market funds. The money market funds, held in U.S. dollars, are primarily invested in U.S. and foreign short-term debt obligations. As of September 30, 2024 and December 31, 2023, the Company’s cash and cash equivalents included smaller amounts of cash balances held in accounts with regional European banks at the Company’s Austrian subsidiary, partially in euros. The Company does not believe that it is subject to unusual credit risk beyond the normal credit risk associated with commercial banking relationships. The Company relies, and expects to continue to rely, on a small number of vendors to manufacture supplies and raw materials for its development programs. These programs could be adversely affected by a significant interruption in these manufacturing services or the availability of raw materials. As of September 30, 2024 Gilead Sciences, Inc. (“Gilead”) accounted for the majority of the accounts receivable balance. As of December 31, 2023, Gilead and F. Hoffmann-La Roche Ltd. and Hoffmann-La Roche Inc. (together “Roche”) accounted for the majority of the accounts receivable balance. For the three months ended September 30, 2024 Gilead accounted for the majority of the Company’s revenues. For the nine months ended September 30, 2024 Roche accounted for the majority of the Company’s revenues as a result of a contract modification and the recognition of upfront and milestone payments previously recorded as deferred revenues. For the three and nine months ended September 30, 2023 Gilead and Roche accounted for the majority of the Company’s revenues. Other customers accounted for less than 10.0% of accounts receivable or net revenues. The Company monitors the financial performance of its customers so that it can appropriately respond to changes in their credit-worthiness. To date, the Company has not experienced any significant losses with respect to collection of its accounts receivable.
Cash equivalents	Cash equivalents The Company considers all highly liquid investments with maturities of three months or less at the date of purchase to be cash equivalents. As of September 30, 2024 and December 31, 2023, cash equivalents consisted of money market funds and short-term deposits.
Fair value measurements	Fair value measurements Certain assets and liabilities are carried at fair value under GAAP. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. Financial assets and liabilities carried at fair value are to be classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable: ● Level 1 - Quoted prices in active markets for identical assets or liabilities. ● Level 2 - Observable inputs (other than Level 1 quoted prices), such as quoted prices in active markets for similar assets or liabilities, quoted prices in markets that are not active for identical or similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data. ● Level 3 - Unobservable inputs that are supported by little or no market activity and that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques. The Company’s cash equivalents are carried at fair value, determined according to the fair value hierarchy described above (see Note 6).
Property and equipment	Property and equipment Property and equipment are stated at cost less accumulated depreciation and amortization. Depreciation and amortization expense is recognized using the straight-line method over the estimated useful life of each asset as follows: Estimated useful life Leasehold improvements shorter of useful life or term of lease Laboratory equipment 2 - 10 years Furniture and fixtures 2 - 10 years Computer equipment and software 2 - 4 years Costs for capital assets not yet placed into service are capitalized as construction-in-progress and depreciated once placed into service. Expenditures for repairs and maintenance are charged to expense as incurred. When property and equipment is sold or otherwise disposed of, the cost and related accumulated depreciation are eliminated from the accounts and any resulting gain or loss is reflected in the consolidated statements of operations.
Leases	Leases The determination whether an arrangement qualifies as a lease is made at contract inception. A lease qualifies as a finance lease if any of the following criteria are met at the inception of the lease: (i) there is a transfer of ownership of the leased asset to the Company by the end of the lease term, (ii) the Company holds an option to purchase the leased asset that it is reasonably certain to exercise, (iii) the lease term is for a major part of the remaining economic life of the leased asset, (iv) the present value of the sum of lease payments equals or exceeds substantially all of the fair value of the leased asset, or (v) the nature of the leased asset is specialized to the point that it is expected to provide the lessor no alternative use at the end of the lease term. All other leases are recorded as operating leases and are included in right of use (“ROU”) assets and lease liabilities in the consolidated balance sheets. For leases with an initial term of 12 months or less, the Company does not recognize a right of use asset or lease liability. These short-term leases are expensed on a straight-line basis over the lease term. ROU assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent its obligation to make lease payments arising from the lease. ROU assets and lease liabilities are recognized at the commencement date of the lease based upon the present value of lease payments over the lease term. When determining the lease term, the Company includes options to extend or terminate the lease when it is reasonably certain that the option will be exercised. The Company uses the implicit rate when readily determinable and uses its incremental borrowing rate when the implicit rate is not readily determinable based upon the information available at the commencement date in determining the present value of the lease payments. The incremental borrowing rate is determined using a secured borrowing rate for the same currency and term as the associated lease. The lease payments used to determine ROU assets may include lease incentives, stated rent increases and escalation clauses linked to rates of inflation when determinable and are recognized as ROU asset on the consolidated balance sheet. In addition, certain of the Company’s arrangements contain lease and non-lease components. The Company generally separates lease payments from non-lease payments. Operating leases are reflected in operating lease assets, in current operating lease liabilities and non-current operating lease liabilities in the consolidated balance sheets. Finance leases are reflected in finance lease assets, in accrued expenses and other current liabilities and in other non-current operating lease liabilities in the consolidated balance sheets. The ROU asset is tested for impairment in accordance with ASC 360.
Capitalized Software Development Cost	Capitalized Software Development Cost The Company capitalizes certain implementation costs for internal-use software incurred in a cloud computing agreement that is a service contract. Eligible costs associated with cloud computing arrangements, such as software business applications used in the normal course of business, are capitalized in accordance with ASC 350. These costs are recognized on a straight-line basis in the same line item in the statement of operations and comprehensive loss as the expense for fees for the associated cloud computing arrangement, over the term of the arrangement, plus reasonably certain renewals.
Restructuring	Restructuring Costs and liabilities associated with restructuring activities are recognized when the actions are probable and estimable, which is when management approves the associated actions. Employee-related severance charges are recognized at the time of communication to employees.
Revenue recognition from collaboration and licensing	Revenue recognition from collaboration and licensing The Company recognized revenue from collaboration and license agreements with Gilead and Roche. Under the collaboration and license agreement with Gilead (as amended and restated, the “Gilead Collaboration Agreement”), the parties agreed to collaborate with respect to two preclinical research programs to evaluate potential vaccine products for the treatment, cure, diagnosis or prevention of the hepatitis B virus (“HBV”) and the human immunodeficiency virus (“HIV”). In February 2022, the parties signed an amended and restated collaboration agreement (the “Restated Gilead Collaboration Agreement”), which revised the terms only for the HIV program, whereby the Company took on development responsibilities for the HIV program candidate through a Phase 1b clinical trial. The Company’s performance obligations under the terms of the original agreement include one combined performance obligation for each research program (HBV and HIV) comprised of the transfer of intellectual property rights (licenses) and providing research and development services. The terms of the Restated Gilead Collaboration Agreement added an additional performance obligation to perform research and development work for the HIV program. The licenses do not represent distinct performance obligations, because they cannot be used without the research and development services. Payments to the Company under the Restated Gilead Collaboration Agreement include a non-refundable up-front payment, payments for research and development activities, payments based upon the achievement of defined milestones, and if certain future conditions are met, payments for manufacturing services, commercial milestones and royalties on product sales. Under the research collaboration and license agreement with Roche (the “Roche Collaboration Agreement”), the Company agreed to conduct research and early clinical development through Phase 1b for HB-700, a novel investigational arenaviral immunotherapy for the treatment of KRAS-mutated cancers. The Roche Collaboration Agreement also included an obligation of the Company to deliver a specified package of preclinical data and results with respect to a second program, targeting undisclosed cancer antigens (collectively “UCAs”) and an option for Roche to license the UCA program. The Company’s performance obligations under the terms of the Roche Collaboration Agreement included one combined performance obligation for the transfer of intellectual property rights (licenses) and providing research and development services for the HB-700 program, and a second, separate performance obligation to perform research and development services with respect to the UCA program. The UCA Option provided a right to license the program at the standalone selling price and therefore did not constitute a separate performance obligation. Payments to the Company under the Roche Collaboration Agreement included a non-refundable up-front payment, payments based upon the achievement of defined milestones, an additional payment if the option for the UCA program was exercised and royalties on product sales. In January 2024, Roche provided written notice of the termination of the collaboration and licensing agreement to the Company resulting in early recognition of revenue previously recorded as deferred revenue. The termination was made according to Roche’s right to terminate without cause, acknowledging that, the Company had met all go-forward criteria under the agreement. Upon the collaboration and licensing agreement termination effective date of April 25, 2024, the Company regained full control of the associated intellectual property portfolio and has full collaboration and licensing rights for this program. The Company evaluates its collaboration and licensing arrangements pursuant to ASC 606 Revenue from Contracts with Customers. To determine the recognition of revenue from arrangements that fall within the scope of ASC 606, the Company performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the Company satisfies a performance obligation. Under ASC 606, the Company applies significant judgement to evaluate whether the promises under the collaboration and licensing arrangements represent separate or one or more combined performance obligations, the allocation of the transaction price to identified performance obligations, the timing of revenue recognition, whether the UCA Option constitutes a material right, and the determination of when milestone payments are probable of being received. Upfront payment and program initiation fee The non-refundable upfront-payment received by the Company upon signing of the Gilead Collaboration Agreement, and milestone payments that were linked to future performance obligations, were initially recorded as deferred revenue and allocated between the two research program performance obligations. Such amounts are recognized as revenue over the performance period of the respective services on a percent of completion basis using total estimated research and development labor hours (input method) for each of the obligations. The percent of completion basis using labor hours was considered the best measure of progress in which control of the combined performance obligations transfers to the customer, due to the short time intervals in which research results are shared with the collaboration partner and the nature of the work being performed. The non-refundable program initiation payment received from Gilead upon signing of the Restated Collaboration Agreement was also initially recorded as deferred revenue and is recognized on a percent of completion basis using total estimated research and development costs (input method) for the performance of the obligations. The percent of completion basis using research and development costs was considered the best measure of progress in which control of the performance obligations transfers to the customer, due to the immediate benefit that it adds to the value of the customer’s rights on the program, the short time intervals in which development results are shared and the nature of the work being performed. The non-refundable upfront-payment received by the Company upon signing of the Roche Collaboration Agreement was initially recorded as deferred revenue and allocated between the HB-700 program and the UCA program. Such amounts were recognized as revenue over the performance period of the respective services on a percent of completion basis using total estimated research and development costs (input method) for each of the obligations during the initial term of the contract. The percent of completion basis using research and development costs was considered the best measure of progress in which control of the performance obligations transfers to the customer. Reimbursement for services Under the Gilead Collaboration Agreement and historically under the Roche Collaboration Agreement prior to termination, the Company incurs employee expenses as well as external costs for research, manufacturing and clinical trial activities presented as operating expenses or prepaid expenses. Based on the nature of the Company's responsibilities under the collaboration arrangements, reimbursement of those costs are presented as revenue and not deducted from expenses, as the Company controls the research activities. Amounts of consideration allocated to the performance of research or manufacturing services are recognized over the period in which services are performed. Reimbursements for external costs are recognized as revenues as progress is achieved. Unpaid reimbursement amounts are presented as Accounts Receivable. Research and development milestones The Gilead Collaboration Agreement includes, and the Roche Collaboration Agreement included, contingent milestone payments related to specified preclinical and clinical development milestones. These milestone payments represent variable consideration that are not initially recognized within the transaction price as they are fully constrained under the guidance in ASC 606, due to the scientific uncertainties and the required commitment from Gilead and Roche. While no further milestone payments are expected under the terminated Roche Collaboration Agreement, the Company will continue to assess the probability of significant reversals for any amounts that become likely to be realized under the Gilead Collaboration Agreement prior to including the variable consideration associated with these payments within the transaction price. Sales-based milestones and royalty payments The Gilead Collaboration Agreement also includes, and the Roche Collaboration Agreement included, certain sales-based milestone and royalty payments upon successful commercialization of a licensed product. In accordance with ASC 606-10-55-65 Sales Based or Usage Based Royalties, the Company recognizes revenues from sales-based milestone and royalty payments at the later of (i) the occurrence of the subsequent sale; or (ii) the performance obligation to which some or all of the sales-based milestone or royalty payments has been allocated has been satisfied. The Company anticipates recognizing these milestones and royalty payments if and when subsequent sales are generated from a licensed product by the collaboration partner. Cost to fulfill contracts The Company incurs costs for personnel, supplies and other costs related to its laboratory operations as well as fees from third parties and license expenses in connection with its research and development obligations under collaboration and licensing agreements. These costs are recognized as research and development expenses over the period in which services are performed. Sublicense fees triggered by the receipt of payments are capitalized as an asset when the obligation to pay the fee arises. The capitalized asset is amortized over the period in which the revenue from the triggering payment is recognized.
Recent accounting pronouncements	Recent accounting pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”) or other standard setting bodies that the Company adopts as of the specified effective date. Recently Issued Accounting Pronouncements In December 2023, the FASB issued final guidance in ASU No. 2023-09, Income Taxes (ASC 740): Improvements to Income Tax Disclosures requiring entities to provide additional information in the rate reconciliation and disclosures about income taxes paid. For public business entities, the guidance is effective for annual periods beginning after December 15, 2024. The Company does not expect this ASU to have a material impact on the consolidated financial statements. In November 2023, the FASB issued ASU No. 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures which requires public entities to disclose significant segment expenses regularly provided to the chief operating decision-maker. Public entities with a single reporting segment have to provide all disclosures required by ASC 280, including the significant segment expense disclosures. For public business entities, the guidance is effective for annual periods beginning after December 15, 2024. The Company does not expect this ASU to have a material impact on the consolidated financial statements.
Impairment of long-lived assets	Impairment of long-lived assets Long-lived assets, including operating and finance lease right of use assets, consist of property and equipment. Long-lived assets to be held and used are tested for recoverability whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable. Factors that the Company considers in deciding when to perform an impairment review include significant underperformance of the business in relation to expectations, significant negative technological, scientific or economic trends and significant changes or planned changes in the use of the assets. If an impairment review is performed to evaluate a long-lived asset group for recoverability, the Company compares forecasts of undiscounted cash flows expected to result from the use and eventual disposition of the long-lived asset group to its carrying value. An impairment loss would be recognized in loss from operations when estimated undiscounted future cash flows expected to result from the use of an asset group are less than its carrying amount. The impairment loss would be based on the excess of the carrying value of the impaired asset group over its fair value (see Note 5 and Note 7).

Summary of significant accoun_3

Summary of significant accounting policies (Tables)	9 Months Ended
Summary of significant accounting policies (Tables)	Sep. 30, 2024
Summary of significant accounting policies
Schedule of estimated useful life of each asset	Estimated useful life Leasehold improvements shorter of useful life or term of lease Laboratory equipment 2 - 10 years Furniture and fixtures 2 - 10 years Computer equipment and software 2 - 4 years

Restructuring (Tables)

Restructuring (Tables)	9 Months Ended
Restructuring (Tables)	Sep. 30, 2024
Restructuring
Schedule of restructuring charges	Three months ended September 30, Nine months ended September 30, 2024 2023 2024 2023 Cash charges Severance and other personnel expenses 832 — 2,070 — Professional fees and other related charges 46 — 131 — Total $ 878 $ — $ 2,201 $ —
Schedule of roll-forward of cash restructuring-related liabilities	Severance and other personnel costs Professional fees and other related charges Total Balance as of December 31, 2023 $ — $ — $ — Severance and other personnel costs, professional fees and other related charges 2,070 131 2,201 Total cash charges (1,231) (82) (1,313) Balance as of September 30, 2024 $ 839 $ 49 $ 888

Impairment (Tables)

Impairment (Tables)	9 Months Ended
Impairment (Tables)	Sep. 30, 2024
Restructuring
Schedule of restructuring charges	Three months ended September 30, Nine months ended September 30, 2024 2023 2024 2023 Non-cash impairment charges Asset write-offs $ (172) $ — $ (172) $ — Total non-cash impairment charges $ (172) $ — $ (172) $ —

Fair Value of Financial Assets

Fair Value of Financial Assets (Tables)	9 Months Ended
Fair Value of Financial Assets (Tables)	Sep. 30, 2024
Fair Value of Financial Assets
Schedule of financial assets measured at fair value on a recurring basis	The following tables present information about the Company’s financial assets measured at fair value on a recurring basis and indicating the level of the fair value hierarchy utilized to determine such fair values (in thousands): Fair Value Measurement at September 30, 2024 Level 1 Level 2 Level 3 Total Cash equivalents: Money market funds $ 49,744 $ — $ — $ 49,744 Total $ 49,744 $ — $ — $ 49,744 Fair Value Measurement at December 31, 2023 Level 1 Level 2 Level 3 Total Cash equivalents: Money market funds $ 91,084 $ — $ — $ 91,084 Total $ 91,084 $ — $ — $ 91,084

Property, plant and equipment_2

Property, plant and equipment, net (Tables)	9 Months Ended
Property, plant and equipment, net (Tables)	Sep. 30, 2024
Property, plant and equipment, net.
Schedule of property, plant and equipment, net	Property, plant and equipment, net consisted of the following (in thousands): September 30, December 31, 2024 2023 Land $ 2,040 $ 2,025 Leasehold improvements 3,332 3,300 Construction in progress 23 212 Laboratory equipment 8,748 8,722 Furniture and fixtures 655 654 Computer equipment and software 2,523 2,652 Property and equipment, gross 17,321 17,565 Less: Accumulated depreciation (10,461) (9,823) Property and equipment, net $ 6,860 $ 7,742

Accrued expenses and other cu_2

Accrued expenses and other current liabilities (Tables)	9 Months Ended
Accrued expenses and other current liabilities (Tables)	Sep. 30, 2024
Accrued expenses and other current liabilities
Schedule of accrued expenses and other current liabilities	Accrued expenses and other current liabilities consisted of the following (in thousands): September 30, December 31, 2024 2023 Salaries and bonuses 4,816 5,665 Social security contributions 285 340 Unearned grant income — 52 Accrued external research and development expenses 5,685 4,594 Accrued external general and administration expenses 884 292 Accrued for property and equipment acquisitions — 14 Accrued for restructuring expenses 888 — Income taxes — 367 Other accruals and liabilities 515 777 $ 13,073 $ 12,101

Loans payable (Tables)

Loans payable (Tables)	9 Months Ended
Loans payable (Tables)	Sep. 30, 2024
Loans payable
Schedule of loans payable	September 30, December 31, 2024 2023 Loans from FFG $ — $ 1,172 Unamortized debt discount — (52) Total loans payable, net $ — $ 1,120

Stock-based compensation (Table

Stock-based compensation (Tables)	9 Months Ended
Stock-based compensation (Tables)	Sep. 30, 2024
Stock-based compensation
Schedule of awards outstanding	As of September 30, 2024 2018 Plan 2019 Plan Inducement Awards Total Granted and outstanding awards: Stock options 73,935 964,206 40,000 1,078,141 Total 73,935 964,206 40,000 1,078,141
Schedule of assumptions used in the Black-Scholes option-pricing model for estimating the fair value of stock options granted	Three months ended September 30, Nine months ended September 30, 2024 2023 2024 2023 Risk-free interest rate 4.12 % 4.48 % 4.52 % 3.70 % Expected term (in years) 5.9 4.4 6.0 5.7 Expected volatility 103.0 % 90.6 % 101.5 % 93.5 % Expected dividends — % — % — % — %
Schedule of summary of stock option activity	The following table summarizes the Company’s stock option activity since January 1, 2024 (in thousands, except share and per share amounts): Weighted Weighted Average Average Remaining Aggregate Number of Exercise Contractual Intrinsic Shares Price Term Value (in years) Outstanding as of December 31, 2023 810,942 $ 42.76 7.4 $ 486 Granted 429,781 7.53 Exercised — — Forfeited (162,582) 29.99 Outstanding as of September 30, 2024 1,078,141 $ 30.64 5.7 $ 224 Options exercisable as of September 30, 2024 497,606 $ 54.79 3.9 $ 224 Options unvested as of September 30, 2024 580,535 $ 9.94 7.2 $ —
Schedule of restricted stock Units	Weighted Average Grant Number of Date Fair Shares Value Outstanding as of December 31, 2023 — $ — Granted 178,570 6.44 Vested — — Forfeited — — Outstanding as of September 30, 2024 178,570 $ 6.44
Schedule of stock-based compensation expense	Stock-based compensation expense was classified in the condensed consolidated statements of operations and comprehensive loss as follows (in thousands): Three months ended September 30, Nine months ended September 30, 2024 2023 2024 2023 Research and development expenses (1) $ 248 $ 216 $ 251 $ 764 General and administrative expenses (1) 691 358 898 1,164 $ 939 $ 574 $ 1,149 $ 1,928 (1)

Net loss per share (Tables)

Net loss per share (Tables)	9 Months Ended
Net loss per share (Tables)	Sep. 30, 2024
Net loss per share
Schedule of basic and diluted Net loss per share attributable to common stockholders	The following table sets forth the computation of the basic and diluted net loss per share attributable to common stockholders (in thousands, except for share and per share amounts): Three months ended September 30, Nine months ended September 30, 2024 2023 2024 2023 Numerator: Net loss $ (13,841) $ (19,066) $ (18,553) $ (56,762) Denominator: Weighted-average common shares outstanding, basic and diluted 9,894,974 8,395,011 9,894,974 6,793,358 Weighted-average Series A convertible preferred shares outstanding, basic and diluted, presented as if converted into common stock (1) 37,000 37,000 37,000 99,218 Weighted-average Series A-1 convertible preferred shares outstanding, basic and diluted, presented as if converted into common stock (1) 1,080,000 1,080,000 1,080,000 1,310,769 Weighted-average Series A-2 convertible preferred shares outstanding, basic and diluted, presented as if converted into common stock (1) 1,526,800 1,526,800 1,526,800 654,343 Total number of shares used to calculate net loss per share, basic and diluted 12,538,774 11,038,811 12,538,774 8,857,688 Net loss per share, basic and diluted $ (1.10) $ (1.73) $ (1.48) $ (6.41) (1) one shares common preferred stock, 1,080,000 shares of the Company’s common stock were issuable upon conversion of Series A-1 convertible preferred stock and 1,526,800 shares of the Company’s common stock were issuable upon conversion of Series A-2 convertible preferred stock (see Note 11).
Schedule of potentially dilutive securities that were not included in the diluted per share calculations	Three and nine months ended September 30, 2024 2023 Options issued and outstanding 1,078,141 836,221 Unvested restricted stock units 178,570 — Total 1,256,711 836,221

Summary of significant accoun_4

Summary of significant accounting policies - Going concern (Details) - USD ($)	3 Months Ended						9 Months Ended		12 Months Ended
	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Summary of significant accounting policies
Net Income (Loss)	$ (13,841,000)	$ (19,095,000)	$ 14,383,000	$ (19,066,000)	$ (18,016,000)	$ (19,680,000)	$ (18,553,000)	$ (56,762,000)	$ (81,600,000)
Accumulated deficit	$ (387,814,000)						$ (387,814,000)		$ (369,261,000)

Summary of significant accoun_5

Summary of significant accounting policies - Reverse Stock Split (Details)	Jul. 09, 2024 $ / shares
Summary of significant accounting policies
Reverse stock split of common stock	0.1
Common stock, par value (in dollars per share)	$ 0.0001

Summary of significant accoun_6

Summary of significant accounting policies - Property and equipment (Details)	Sep. 30, 2024
Laboratory equipment \| Minimum
Property and equipment
Estimated useful life (in years)	2 years
Laboratory equipment \| Maximum
Property and equipment
Estimated useful life (in years)	10 years
Furniture and fixtures \| Minimum
Property and equipment
Estimated useful life (in years)	2 years
Furniture and fixtures \| Maximum
Property and equipment
Estimated useful life (in years)	10 years
Computer equipment and software \| Minimum
Property and equipment
Estimated useful life (in years)	2 years
Computer equipment and software \| Maximum
Property and equipment
Estimated useful life (in years)	4 years

Summary of significant accoun_7

Summary of significant accounting policies - Others (Details)	9 Months Ended
	Sep. 30, 2024 item Program
Summary of significant accounting policies
Number of preclinical research programs \| Program	2
Number of Combined Performance Obligation	1
Number of combined performance obligation for each research program	1
Number of research program performance obligations	2

Collaboration and Licensing A_2

Collaboration and Licensing Agreements (Details)	1 Months Ended			3 Months Ended				9 Months Ended
Collaboration and Licensing Agreements (Details)	Oct. 31, 2022 USD ($)	Feb. 28, 2022 USD ($)	Jun. 30, 2018 USD ($) item	Sep. 30, 2024 USD ($)	Jun. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Mar. 31, 2023 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Dec. 31, 2023 USD ($)
Collaboration and Licensing Agreements
Revenue				$ 4,703,000		$ 6,867,000		$ 42,592,000	$ 12,722,000
Gilead Collaboration and License Agreement
Collaboration and Licensing Agreements
Number of preclinical research programs \| item			2
Upfront payment received			$ 10,000,000
Program initiation fee		$ 15,000,000	$ 15,000,000
Payment term (in days)			60 days
Milestone payment received			$ 13,000,000
Percentage of upfront payment included in deferred revenue expected to be recognized in 2024				38%				38%
Percentage of upfront payment included in deferred revenue expected to be recognized in 2025				51%				51%
Percentage of upfront payment included in deferred revenue expected to be recognized in 2026				11%				11%
Revenue recognized from cost reimbursements for research and development services				$ 300,000		500,000		$ 500,000	1,300,000
Contract asset relating to the sublicense payment				200,000				200,000		$ 100,000
Contract liability relating to sublicense payment				0				0		0
Deferred revenues				7,000,000				7,000,000		7,500,000
Revenue				4,400,000		1,200,000		5,700,000	3,800,000
Roche collaboration agreement
Collaboration and Licensing Agreements
Upfront payment received	$ 25,000,000
Milestone payment received					$ 10,000,000		$ 10,000,000
Collaborative arrangement revenue from cost reimbursements for preparation of first human trial								100,000
Revenue recognized from cost reimbursements				300,000				300,000
Contract asset relating to the sublicense payment				0				0		2,000,000
Contract liability relating to sublicense payment				0				0		0
Deferred revenues										$ 26,800,000
Deferred income				0				0
Revenue				$ 0		$ 4,900,000		$ 36,300,000	$ 7,300,000
Development Milestones \| HBV program
Collaboration and Licensing Agreements
Total milestone amount			140,000,000
Development Milestones \| HIV program
Collaboration and Licensing Agreements
program completion fee			10,000,000
Development Milestones \| HIV program \| Maximum
Collaboration and Licensing Agreements
Total milestone amount			172,500,000
Commercial Milestones \| HBV program
Collaboration and Licensing Agreements
Total milestone amount			50,000,000
Commercial Milestones \| HIV program
Collaboration and Licensing Agreements
Total milestone amount			$ 65,000,000

Restructuring (Details)

Restructuring (Details) - USD ($)	3 Months Ended		9 Months Ended
Restructuring (Details) - USD ($)	Sep. 30, 2024	Jun. 30, 2024	Sep. 30, 2024
Restructuring
Reduction if workforce (in percent)	20%		30%
Cash restructuring charges
Severance and other personnel costs	$ 832,000		$ 2,070,000
Professional fees and other related charges	46,000		131,000
Total	$ 878,000	$ 1,300,000	$ 2,201,000

Restructuring - Roll-forward ca

Restructuring - Roll-forward cash restructuring-related liabilities (Details)	9 Months Ended
	Sep. 30, 2024 USD ($)
Restructuring Cost and Reserve [Line Items]
Severance and other personnel costs, professional fees and other related charges.	$ 2,201,000
Total charges	(1,313,000)
Ending Balance	888,000
Severance and other personnel costs [Member]
Restructuring Cost and Reserve [Line Items]
Severance and other personnel costs, professional fees and other related charges.	2,070,000
Total charges	(1,231,000)
Ending Balance	839,000
Professional fees and other related charges. [Member]
Restructuring Cost and Reserve [Line Items]
Severance and other personnel costs, professional fees and other related charges.	131,000
Total charges	(82,000)
Ending Balance	$ 49,000

Impairment - Non-cash impairmen

Impairment - Non-cash impairment charges (Details) - USD ($)	3 Months Ended	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2024	Sep. 30, 2023
Property, Plant and Equipment [Line Items]
Asset write-offs	$ (172,000)	$ (172,000)
Total non-cash impairment charges		(172,000)
Laboratory equipment
Property, Plant and Equipment [Line Items]
Asset write-offs	(172,000)	(172,000)	$ 0
Total non-cash impairment charges	$ (172,000)	$ (172,000)

Fair Value of Financial Asset_2

Fair Value of Financial Assets (Details) - USD ($)	9 Months Ended
Fair Value of Financial Assets (Details) - USD ($)	Sep. 30, 2024	Dec. 31, 2023
Fair Value of Financial Assets
Transfers from Level 1 to Level 2	$ 0
Transfers from Level 2 to Level 1	0
Transfers from into Level 3	0
Transfers from out of Level 3	0
Recurring
Fair Value of Financial Assets
Total	49,744,000	$ 91,084,000
Recurring \| Money market funds
Fair Value of Financial Assets
Cash equivalents	49,744,000	91,084,000
Recurring \| Level 1
Fair Value of Financial Assets
Total	49,744,000	91,084,000
Recurring \| Level 1 \| Money market funds
Fair Value of Financial Assets
Cash equivalents	$ 49,744,000	$ 91,084,000

Property, plant and equipment_3

Property, plant and equipment, net (Details) - USD ($)	3 Months Ended	9 Months Ended
Property, plant and equipment, net (Details) - USD ($)	Sep. 30, 2024	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Property and equipment
Property and equipment, gross	$ 17,321,000	$ 17,321,000		$ 17,565,000
Less: Accumulated depreciation	(10,461,000)	(10,461,000)		(9,823,000)
Property and equipment, net	6,860,000	6,860,000		7,742,000
Impairment charges of assets	172,000	172,000
Land
Property and equipment
Property and equipment, gross	2,040,000	2,040,000		2,025,000
Leasehold improvements
Property and equipment
Property and equipment, gross	3,332,000	3,332,000		3,300,000
Construction in progress
Property and equipment
Property and equipment, gross	23,000	23,000		212,000
Laboratory equipment
Property and equipment
Property and equipment, gross	8,748,000	8,748,000		8,722,000
Impairment charges of assets	172,000	172,000	$ 0
Furniture and fixtures
Property and equipment
Property and equipment, gross	655,000	655,000		654,000
Computer equipment and software
Property and equipment
Property and equipment, gross	$ 2,523,000	$ 2,523,000		$ 2,652,000

Receivable research incentive (

Receivable research incentive (Details) - USD ($)	3 Months Ended		9 Months Ended
Receivable research incentive (Details) - USD ($)	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Research and Development Incentive Program [Line Items]
Receivable research incentives	$ 24,666,000		$ 24,666,000		$ 18,760,000
Grant Income	2,183,000	$ 2,916,000	6,924,000	$ 7,486,000
Austrian Research Incentive Program
Research and Development Incentive Program [Line Items]
Income related to the incentive program recorded as grant income	2,200,000	$ 2,900,000
Receivable research incentives	24,500,000		24,500,000		17,300,000
Grant Income			6,900,000	$ 7,200,000
New York State Life Sciences Research and Development Program
Research and Development Incentive Program [Line Items]
Receivable research incentives	100,000		100,000		1,400,000
Reimbursement of research and development expenses	500,000		500,000
New York State New York City Biotechnology Tax Credit Program
Research and Development Incentive Program [Line Items]
Receivable research incentives	$ 100,000		100,000		$ 100,000
Maximum expenses eligible for incentives			$ 250,000

Accrued expenses and other cu_3

Accrued expenses and other current liabilities (Details) - USD ($)	Sep. 30, 2024	Dec. 31, 2023
Accrued expenses and other current liabilities
Salaries and bonuses	$ 4,816,000	$ 5,665,000
Social security contributions	285,000	340,000
Unearned grant income (current)		52,000
Accrued external research and development expenses	5,685,000	4,594,000
Accrued external general and administration expenses	884,000	292,000
Accrued for property and equipment acquisitions		14,000
Accrued for restructuring expenses	888,000
Income taxes		367,000
Other accruals and liabilities.	515,000	777,000
Total	$ 13,073,000	$ 12,101,000

Loans payable (Details)

Loans payable (Details) $ in Thousands	9 Months Ended
Loans payable (Details) $ in Thousands	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2024 EUR (€)	Dec. 31, 2023 USD ($)
Loans payable
Loans from FFG				$ 1,172
Unamortized debt discount				(52)
Total loans payable, net			€ 0	$ 1,120
Principal payment	$ 1,141	$ 1,754

Common stock, Class A common _2

Common stock, Class A common stock and convertible preferred stock (Details) $ / shares in Units, $ in Thousands					1 Months Ended	9 Months Ended
	Jul. 09, 2024 shares	Dec. 20, 2023 USD ($) $ / shares shares	Jun. 05, 2023 USD ($) $ / shares shares	Feb. 15, 2022 USD ($) $ / shares shares	May 31, 2023 shares	Sep. 30, 2024 item Vote $ / shares shares	Sep. 30, 2023 USD ($)	Dec. 31, 2023 shares
Preferred stock, shares authorized (in shares)						10,000,000		10,000,000
Shares retired due to round-down effects and redeemed (in shares)	37
Net proceeds from public offering \| $			$ 46,200
Proceeds from issuance of common stock, net of issuance costs \| $							$ 27,794
Number Of Series Of Preferred Stock Authorized, Issued And Outstanding. \| item						3
Common stock
Common stock, shares authorized (in shares)						40,000,000		20,000,000
Common stock, issued (in shares)						9,655,022		9,655,022
Common stock, outstanding (in shares)						9,655,022		9,655,022
Issuance of stock (in shares)			2,290,077
Share price (in USD per share) \| $ / shares			$ 13.10
Conversion of preferred stock into common stock (in shares)					632,700
Number of votes \| Vote						1
Common stock \| Pre Reverse Stock Split
Issuance of stock (in shares)			22,900,768
Conversion of preferred stock into common stock (in shares)					6,327,000
Class A common stock
Common stock, shares authorized (in shares)						3,900,000		3,900,000
Common stock, issued (in shares)						2,399,517		2,399,517
Common stock, outstanding (in shares)						2,399,517		2,399,517
Number of common stock issued upon conversion of each share (in shares)						1
Series A, SeriesA-1 And SeriesA-2 convertible Preferred Stock
Number of common stock issued upon conversion of each share (in shares)						100
Threshold percentage for conversion (in %)						9.99%
Liquidation preference per share (in $ per share) \| $ / shares						$ 0.001
Series A convertible preferred stock
Preferred stock shares designated (in shares)						2,978		2,978
Preferred stock, shares issued (in shares)						370
Preferred stock, shares outstanding (in shares)						370		370
Number of shares elected to convert (in shares)					1,327
Series A-1 convertible preferred stock
Preferred stock shares designated (in shares)						15,800		15,800
Preferred stock, shares issued (in shares)						10,800
Preferred stock, shares outstanding (in shares)						10,800		10,800
Number of shares elected to convert (in shares)					5,000
Series A-2 convertible preferred stock
Preferred stock shares designated (in shares)						15,268		15,268
Preferred stock, shares issued (in shares)						15,268
Preferred stock, shares outstanding (in shares)						15,268		15,268
Issuance of stock (in shares)			15,268
Share price (in USD per share) \| $ / shares			$ 1,310
Stock Purchase Agreement
Issuance of stock (in shares)				166,666
Share price (in USD per share) \| $ / shares				$ 30
Net proceeds from public offering \| $				$ 35,000
Proceeds from issuance of common stock, net of issuance costs \| $				$ 5,000
Stock Purchase Agreement \| Pre Reverse Stock Split
Issuance of stock (in shares)				1,666,666
Stock Purchase Agreement \| Gilead \| Gilead Collaboration and License Agreement
Ownership percentage (in %)				19.90%
Amended Stock Purchase Agreement
Issuance of stock (in shares)		1,500,000
Share price (in USD per share) \| $ / shares		$ 14.167
Proceeds from issuance of common stock, net of issuance costs \| $		$ 21,300
Outstanding amount \| $		$ 8,750
Amended Stock Purchase Agreement \| Pre Reverse Stock Split
Issuance of stock (in shares)		15,000,000

Stock-based compensation - 2018

Stock-based compensation - 2018 Stock Option and Grant Plan (Details)	1 Months Ended
	Jun. 30, 2018 installment	Sep. 30, 2024 shares	Dec. 31, 2023 shares
Stock-based compensation
Options outstanding (in shares)		1,078,141	810,942
2018 Stock Option and Grant Plan
Stock-based compensation
Vesting period (in years)	4 years
Options outstanding (in shares)		73,935
2018 Stock Option and Grant Plan \| Vesting upon first anniversary
Stock-based compensation
Percentage of options vesting (in %)	25%
2018 Stock Option and Grant Plan \| Vesting in equal quarterly installments
Stock-based compensation
Percentage of options vesting (in %)	75%
Number of quarterly installments for vesting \| installment	12

Stock-based compensation - 2019

Stock-based compensation - 2019 Stock Option and Incentive Plan and 2023 Inducement Plan (Details) $ / shares in Units, $ in Millions			9 Months Ended
	Sep. 12, 2023 $ / shares shares	Aug. 07, 2023 USD ($) item installment $ / shares shares	Sep. 30, 2024 installment shares	Apr. 07, 2023 shares
Stock-based compensation
Number of common stock entitled for each option upon the exercise of the option			1
Stock option exchange offer
Stock-based compensation
Vesting period (in years)		3 years
Number of quarterly installments for vesting \| installment		12
Eligible participants \| item		82
Exercise of stock options cancelled (in shares)		54,323
Percentage of options accepted for cancellation (in %)		86.60%
Issuance of common stock (in shares)	27,376
Exercise price per share (in $ per share) \| $ / shares	$ 10
Stock option exchange offer resulted in incremental stock-based compensation expense \| $		$ 0.1
Stock option exchange offer \| Minimum
Stock-based compensation
Exchange ratio		1.75
Exercise price (in $ per share) \| $ / shares		$ 69
Stock option exchange offer \| Maximum
Stock-based compensation
Exchange ratio		2.50
Exercise price (in $ per share) \| $ / shares		$ 140
2019 Stock Option and Incentive Plan
Stock-based compensation
Number stock option authorized (in shares)			1,202,548
Annual increase in cumulative number of shares authorized for issuance (in %)			4%
Vesting period (in years)			4 years
2019 Stock Option and Incentive Plan \| Non Executive Directors
Stock-based compensation
Vesting period (in years)			3 years
2019 Stock Option and Incentive Plan \| Vesting upon first anniversary
Stock-based compensation
Percentage of options vesting (in %)			25%
2019 Stock Option and Incentive Plan \| Vesting upon first anniversary \| Non Executive Directors
Stock-based compensation
Percentage of options vesting (in %)			33%
2019 Stock Option and Incentive Plan \| Vesting in equal quarterly installments
Stock-based compensation
Percentage of options vesting (in %)			75%
Number of quarterly installments for vesting \| installment			12
2019 Stock Option and Incentive Plan \| Vesting in equal quarterly installments \| Non Executive Directors
Stock-based compensation
Percentage of options vesting (in %)			67%
Number of quarterly installments for vesting \| installment			8
2023 Inducement Plan
Stock-based compensation
Stock reserved for future issuance (in shares)			10,000	50,000

Stock-based compensation - Summ

Stock-based compensation - Summary of awards outstanding (Details) - shares	Sep. 30, 2024	Dec. 31, 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding (in shares)	1,078,141	810,942
2018 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding (in shares)	73,935
2019 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding (in shares)	964,206
Inducement Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding (in shares)	40,000

Stock-based compensation - Stoc

Stock-based compensation - Stock option valuation assumptions (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Assumptions used in the Black-Scholes option-pricing model
Risk-free interest rate	4.12%	4.48%	4.52%	3.70%
Expected term (in years)	5 years 10 months 24 days	4 years 4 months 24 days	6 years	5 years 8 months
Expected volatility	103%	90.60%	101.50%	93.50%

Stock-based compensation - St_2

Stock-based compensation - Stock option activity (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Number of Shares
Beginning balance	810,942
Granted	429,781
Forfeited	(162,582)
Ending balance	1,078,141		810,942
Option exercisable	497,606
Option unvested	580,535
Weighted Average Exercise Price
Beginning balance	$ 42.76
Granted	7.53
Forfeited	29.99
Ending balance	30.64		$ 42.76
Option exercisable	54.79
Option unvested	$ 9.94
Weighted Average Remaining Contractual Term
Weighted Average Remaining Contractual Term (in years)	5 years 8 months 12 days		7 years 4 months 24 days
Weighted Average Remaining Contractual Term, option exercisable (in years)	3 years 10 months 24 days
Weighted Average Remaining Contractual Term, option unvested (in years)	7 years 2 months 12 days
Aggregate Intrinsic Value, beginning balance	$ 486
Aggregate Intrinsic Value, ending balance	224		$ 486
Aggregate Intrinsic Value, options exercisable	$ 224
Fair value per common stock used for calculating intrinsic values (in $ per share)	$ 4.30		$ 8.10
Cash was received from option exercise under share-based payment arrangements	$ 0	$ 1

Stock-based compensation - Rest

Stock-based compensation - Restricted Stock Units (Details)	3 Months Ended	9 Months Ended
Stock-based compensation - Restricted Stock Units (Details)	Sep. 30, 2024 installment $ / shares shares	Sep. 30, 2024 $ / shares shares
Number of Shares
Granted \| shares		178,570
Ending balance \| shares	178,570	178,570
Weighted Average Grant Date Fair Value
Granted \| $ / shares		$ 6.44
Ending balance \| $ / shares	$ 6.44	$ 6.44
Restricted stock units
Stock-based compensation
Number of equal installments of vesting \| installment	2

Stock-based compensation - St_3

Stock-based compensation - Stock-based compensation expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Stock-based compensation
Stock-based compensation expense	$ 939	$ 574	$ 1,149	$ 1,928
Research and development expenses
Stock-based compensation
Stock-based compensation expense	248	216	251	764
General and administrative expense
Stock-based compensation
Stock-based compensation expense	$ 691	$ 358	$ 898	$ 1,164

Income taxes (Details)

Income taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
Income taxes (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Income taxes
Income tax benefits for the net operating losses incurred	$ 0	$ 0	$ 0	$ 0
Income Tax Expense (Benefit)	$ 0	$ 0	$ 0	$ 204

Commitments and contingencies -

Commitments and contingencies - Operating and Finance Leases (Details) - USD ($)	Sep. 30, 2024	Dec. 31, 2023
Commitments and contingencies
Cash balance maintained to secure a letter of credit associated with a real estate lease	$ 207,000	$ 425,000
Operating lease right-of-use assets	2,862,000	5,473,000
Outstanding operating lease obligations	2,800,000	5,400,000
Current operating lease liability	1,206,000	1,638,000
Non-current operating lease liability	$ 1,619,000	$ 3,801,000
Weighted average discount rate on operating lease liabilities (as a percent)	4.50%
Weighted average lease term remaining on operating lease liabilities (in years)	2 years 10 months

Commitments and contingencies_2

Commitments and contingencies - Others (Details)	3 Months Ended	9 Months Ended
Commitments and contingencies - Others (Details)	Sep. 30, 2024 USD ($)	Sep. 30, 2024 USD ($)
Commitments and contingencies
Non-cancellable obligations	$ 5,900,000	$ 5,900,000
2024 deliverables (remaining three months)	1,700,000	1,700,000
2025 deliverables	4,200,000	4,200,000
Licensing fees from intellectual property licenses	$ 600,000	$ 3,500,000

Net loss per share (Details)

Net loss per share (Details) - USD ($)		3 Months Ended						9 Months Ended		12 Months Ended
Net loss per share (Details) - USD ($)		Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Numerator:
Net Income (Loss)		$ (13,841,000)	$ (19,095,000)	$ 14,383,000	$ (19,066,000)	$ (18,016,000)	$ (19,680,000)	$ (18,553,000)	$ (56,762,000)	$ (81,600,000)
Denominator:
Weighted-average Shares outstanding, basic		12,538,774			11,038,811			12,538,774	8,857,688
Weighted-average Shares outstanding, diluted		12,538,774			11,038,811			12,538,774	8,857,688
Net loss per share - basic	[1]	$ (1.10)			$ (1.73)			$ (1.48)	$ (6.41)
Net loss per share - diluted	[1]	$ (1.10)			$ (1.73)			$ (1.48)	$ (6.41)
Class A common stock
Denominator:
Number of common stock issued upon conversion of each share of Preferred Stock		1						1
Number of common shares issuable upon conversion of common stock		239,952						239,952
Common stock
Denominator:
Weighted-average Shares outstanding, basic		9,894,974			8,395,011			9,894,974	6,793,358
Weighted-average Shares outstanding, diluted		9,894,974			8,395,011			9,894,974	6,793,358
Series A convertible preferred stock
Denominator:
Weighted-average Shares outstanding, basic		37,000			37,000			37,000	99,218
Weighted-average Shares outstanding, diluted		37,000			37,000			37,000	99,218
Number of common stock issued upon conversion of each share of Preferred Stock		100						100
Number of common stock issuable upon conversion of convertible preferred stock		37,000						37,000
Series A-1 convertible preferred stock
Denominator:
Weighted-average Shares outstanding, basic		1,080,000			1,080,000			1,080,000	1,310,769
Weighted-average Shares outstanding, diluted		1,080,000			1,080,000			1,080,000	1,310,769
Number of common stock issued upon conversion of each share of Preferred Stock		100						100
Number of common stock issuable upon conversion of convertible preferred stock		1,080,000						1,080,000
Series A-2 convertible preferred stock
Denominator:
Weighted-average Shares outstanding, basic		1,526,800			1,526,800			1,526,800	654,343
Weighted-average Shares outstanding, diluted		1,526,800			1,526,800			1,526,800	654,343
Number of common stock issued upon conversion of each share of Preferred Stock		100						100
Number of common stock issuable upon conversion of convertible preferred stock		1,526,800						1,526,800

[1] (1) one

Net loss per share - Antidiluti

Net loss per share - Antidilutive securities (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Anti-dilutive securities
Anti-dilutive shares	1,256,711	836,221	1,256,711	836,221
Options issued and outstanding
Anti-dilutive securities
Anti-dilutive shares	1,078,141	836,221	1,078,141	836,221
Restricted stock units
Anti-dilutive securities
Anti-dilutive shares			178,570

Related Parties (Details)

Related Parties (Details) - USD ($)	3 Months Ended	9 Months Ended
Related Parties (Details) - USD ($)	Sep. 30, 2024	Sep. 30, 2024
Board of directors \| Malte Peters \| Consulting agreement
Related parties
Expense recorded	$ 0	$ 200,000