SELLAS Life Sciences (SLS) 10-K 16 Mar 23 2022 FY Annual report Financial data

Cover

Cover - USD ($)	12 Months Ended
	Dec. 31, 2022	Mar. 15, 2023	Jun. 30, 2022
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2022
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-33958
Entity Registrant Name	SELLAS Life Sciences Group, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-8099512
Entity Address, Address Line One	7 Times Square
Entity Address, Address Line Two	Suite 2503
Entity Address, City or Town	New York
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10036
City Area Code	(646)
Local Phone Number	200-5278
Title of 12(b) Security	Common Stock, $0.0001 Par Value per share
Trading Symbol	SLS
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	false
Entity Shell Company	false
Entity Public Float			$ 45,790,691
Entity Common Stock, Shares Outstanding		28,302,504
Documents Incorporated by Reference	Certain information required in Part III of this Annual Report on Form 10-K is incorporated from the registrant’s Proxy Statement for its 2023 Annual Meeting of Stockholders to be filed with the Securities and Exchange Commission pursuant to Regulation 14A not later than 120 days after the end of the fiscal year covered by this Form 10-K, provided that if such Proxy Statement is not filed within such period, such information will be included in an amendment to this Form 10-K to be filed within such 120-day period.
Entity Central Index Key	0001390478
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	FY
Amendment Flag	false

Audit Information

Audit Information	12 Months Ended
	Dec. 31, 2022
Audit Information [Abstract]
Auditor Firm ID	659
Auditor Name	Moss Adams LLP
Auditor Location	Campbell, California

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 17,125	$ 21,355
Restricted cash and cash equivalents	100	100
Prepaid expenses and other current assets	531	1,589
Total current assets	17,756	23,044
Operating lease right-of-use assets	874	723
Goodwill	1,914	1,914
Deposits and other assets	399	594
Total assets	20,943	26,275
Current liabilities:
Accounts payable	3,357	2,144
Accrued expenses and other current liabilities	6,286	2,640
Operating lease liabilities	372	198
Acquired in-process research and development payable	5,500	0
Total current liabilities	15,515	4,982
Operating lease liabilities, non-current	573	610
Warrant liability	4	40
Contingent consideration	0	296
Total liabilities	16,092	5,928
Commitments and contingencies (Note 8)
Stockholders’ equity:
Preferred stock, $0.0001 par value; 5,000,000 shares authorized; Series A convertible preferred stock, 17,500 shares designated; 0 shares issued and outstanding at December 31, 2022 and 2021	0	0
Common stock, $0.0001 par value; 350,000,000 shares authorized, 21,005,405 and 15,895,637 shares issued and outstanding at December 31, 2022 and 2021, respectively	2	2
Additional paid-in capital	184,753	158,948
Accumulated deficit	(179,904)	(138,603)
Total stockholders’ equity	4,851	20,347
Total liabilities and stockholders’ equity	$ 20,943	$ 26,275

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2022	Dec. 31, 2021
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	350,000,000	350,000,000
Common stock, shares issued (in shares)	21,005,405	15,895,637
Common stock, shares outstanding (in shares)	21,005,405	15,895,637
Series A Preferred Stock
Preferred stock, shares authorized (in shares)	17,500	17,500

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Income Statement [Abstract]
Licensing revenue	$ 1,000,000	$ 7,600,000
Operating expenses:
Cost of revenue	100,000	200,000
Research and development	20,268,000	15,674,000
General and administrative	12,582,000	11,320,000
Acquired in-process research and development	10,000,000	0
In-process research and development impairment charge	0	5,700,000
Total operating expenses	42,950,000	32,894,000
Loss from operations	(41,950,000)	(25,294,000)
Non-operating income:
Change in fair value of warrant liability	36,000	15,000
Change in fair value of contingent consideration	296,000	4,337,000
Interest income	317,000	6,000
Total non-operating income	649,000	4,358,000
Loss before income taxes	(41,301,000)	(20,936,000)
Income tax benefit	0	237,000
Net loss	$ (41,301,000)	$ (20,699,000)
Per share information:
Net loss per common share, basic (in dollars per share)	$ (2.13)	$ (1.34)
Net loss per common share, diluted (in dollars per share)	$ (2.13)	$ (1.34)
Weighted-average common shares outstanding, basic (in shares)	19,395,709	15,481,113
Weighted-average common shares outstanding, diluted (in shares)	19,395,709	15,481,113

CONSOLIDATED STATEMENT OF STOCK

CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2020		14,254,554
Beginning balance at Dec. 31, 2020	$ 27,961	$ 1	$ 145,864	$ (117,904)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock and common stock warrants, net of issuance costs (in shares)		786,927
Issuance of common stock and common stock warrants, net of issuance costs	9,005		9,005
Issuance of common stock for exercise of warrants/ net of issuance costs (in shares)		844,061
Issuance of common stock for exercise of warrants/ net of issuance costs	3,069	$ 1	3,068
Vesting of restricted stock units (in shares)		10,095
Stock-based compensation	1,011		1,011
Net loss	$ (20,699)			(20,699)
Ending balance (in shares) at Dec. 31, 2021	15,895,637	15,895,637
Ending balance at Dec. 31, 2021	$ 20,347	$ 2	158,948	(138,603)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock and common stock warrants, net of issuance costs (in shares)		4,629,630
Issuance of common stock and common stock warrants, net of issuance costs	22,946		22,946
Issuance of common stock for exercise of warrants/ net of issuance costs (in shares)		415,005
Issuance of common stock for exercise of warrants/ net of issuance costs	1,048		1,048
Issuance of common stock under employee stock purchase plan (in shares)		25,089
Issuance of common stock under employee stock purchase plan	85		85
Vesting of restricted stock units (in shares)		40,044
Stock-based compensation	1,726		1,726
Net loss	$ (41,301)			(41,301)
Ending balance (in shares) at Dec. 31, 2022	21,005,405	21,005,405
Ending balance at Dec. 31, 2022	$ 4,851	$ 2	$ 184,753	$ (179,904)

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities:
Net loss	$ (41,301)	$ (20,699)
Adjustment to reconcile net loss to net cash used in operating activities:
Acquired in-process research and development	10,000	0
Non-cash in-process research and development impairment charge	0	5,700
Non-cash stock-based compensation	1,726	1,011
Non-cash lease expense	457	173
Change in fair value of contingent consideration	(296)	(4,337)
Change in fair value of common stock warrants	(36)	(15)
Deferred income taxes	0	(239)
Changes in operating assets and liabilities:
Contract asset	0	1,128
Prepaid expenses and other assets	1,253	(1,174)
Accounts payable	1,213	(2,513)
Accrued expenses and other current liabilities	3,646	727
Operating lease liabilities	(471)	(183)
Deferred revenue	0	(5,600)
Net cash used in operating activities	(23,809)	(26,021)
Cash flows from investing activities:
Cash paid for acquisition of in-process research and development	(4,500)	0
Net cash used in investing activities	(4,500)	0
Cash flows from financing activities:
Proceeds from issuance of common stock and common stock warrants, net of issuance costs	22,946	0
Proceeds from issuance of common stock, net of issuance costs	1,048	9,005
Proceeds from employee stock plan purchases	85	0
Proceeds from exercise of warrants	0	3,069
Net cash provided by financing activities	24,079	12,074
Net decrease in cash, cash equivalents, restricted cash, and restricted cash equivalents	(4,230)	(13,947)
Cash, cash equivalents, restricted cash, and restricted cash equivalents at the beginning of year	21,455	35,402
Cash, cash equivalents, restricted cash, and restricted cash equivalents at the end of year	17,225	21,455
Supplemental disclosure of cash flow information:
Cash received during the year for interest	317	6
Supplemental disclosures:
Payable for acquired in-process research and development	5,500	0
Increase in operating lease right of use assets and current and non-current operating lease liabilities	$ 449	$ 0

Organization and Description of

Organization and Description of Business	12 Months Ended
	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Description of Business	Organization and Description of Business SELLAS Life Sciences Group, Inc. (the "Company" or "SELLAS") is a late-stage clinical biopharmaceutical company focused on novel therapeutics for a broad range of cancer indications. SELLAS’ lead product candidate, galinpepimut-S ("GPS"), is a cancer immunotherapeutic agent licensed from Memorial Sloan Kettering Cancer Center ("MSK") and targets the Wilms Tumor 1 ("WT1") protein, which is present in an array of tumor types. GPS has potential as a monotherapy or in combination with other immunotherapeutic agents to address a broad spectrum of hematologic, or blood, cancers and solid tumor indications. SELLAS' second product candidate is GFH009, a small molecule, highly selective cyclin-dependent kinase 9 ("CDK9") inhibitor, which is licensed from GenFleet Therapeutics (Shanghai), Inc. ("GenFleet"), for all therapeutic and diagnostic uses in the world outside of Greater China (mainland China, Hong Kong, Macau and Taiwan). As used in this Annual Report on Form 10-K, the words the "Company," and "SELLAS" refer to SELLAS Life Sciences Group, Inc. and its consolidated subsidiaries following the completion of the business combination with Galena Biopharma, Inc., a Delaware corporation ("Galena"), and SELLAS Life Sciences Group, Ltd., a privately held Bermuda exempted company ("Private SELLAS") in December 2017. This business combination is referred to as the Merger. Upon completion of the Merger, the Company's name changed from "Galena Biopharma, Inc." to "SELLAS Life Sciences Group, Inc." and the Company's financial statements became those of Private SELLAS.

Liquidity and Going Concern

Liquidity and Going Concern	12 Months Ended
	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Liquidity and Going Concern	Liquidity and Going Concern The accompanying consolidated financial statements have been prepared on a going concern basis, which contemplates the realization of assets and the satisfaction of liabilities in the normal course of business. The accompanying consolidated financial statements do not reflect any adjustments relating to the recoverability and reclassifications of assets and liabilities that might be necessary if the Company is unable to continue as a going concern. The Company expects its costs and expenses to increase as it continues to develop its product candidates and progress its current and planned clinical programs. Pursuant to the requirements of Accounting Standard Codification ("ASC") 205-40, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern , management must evaluate whether there are conditions or events, considered in the aggregate, that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that the consolidated financial statements are issued. 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 these financial statements are issued, but will consider such plans if (1) it is probable that the plans will be effectively implemented within one year after the date the financial statements are issued, and (2) it is probable that the plans, when implemented, will mitigate the relevant condition or events that raise substantial doubt about the entity’s ability to continue as a going concern within one year after the date the consolidated financial statements are issued. Certain elements of the Company’s operating plan to alleviate the conditions that raise substantial doubt are outside of the Company’s control and cannot be included in management’s evaluation under the requirements of ASC 205-40. Since inception, the Company has incurred recurring losses and negative cash flows from operations and has an accumulated deficit of $179.9 million as of December 31, 2022. During the year ended December 31, 2022, the Company incurred a net loss of $41.3 million and used $23.8 million of cash in operations. The Company continues to expect to generate operating losses and negative cash flows for the next few years and will need additional funding to support its planned operating activities through profitability. The transition to profitability is dependent upon the successful development, approval, and commercialization of the Company's product candidates and the achievement of a level of revenues adequate to support its cost structure. As of December 31, 2022, the Company had cash and cash equivalents of $17.1 million. The Company expects its cash and cash equivalents will not be sufficient to fund its current planned operations for at least the next twelve months from the date of issuance of these financial statements. The $13.0 million of development milestone payments to the Company triggered by 3DMed's participation in the REGAL study are variable in nature and not under the Company's control, and therefore are not included in the Company's going concern assumption. These conditions give rise to a substantial doubt over the Company’s ability to continue as a going concern. These consolidated financial statements do not include any adjustments related to the recoverability and classification of recorded asset amounts or the amounts and classification of liabilities that might result from the outcome of this uncertainty. On February 28, 2023, the Company consummated an underwritten public offering (the "February 2023 Offering"), issuing 7,220,217 shares of common stock and accompanying common stock warrants to purchase an aggregate of 7,220,217 shares of common stock. The shares of common stock and accompanying common stock warrants were sold at a combined price of $2.77 per share and accompanying common stock warrant. Each common stock warrant sold with the shares of common stock represents the right to purchase one share of the Company’s common stock at an exercise price of $2.77 per share. The common stock warrants are exercisable immediately and will expire on February 28, 2028, five years from the date of issuance. The net proceeds to the Company from the February 2023 Offering were approximately $18.5 million, after deducting underwriting discounts and commissions and estimated offering expenses, and excluding the exercise of any warrants. On April 16, 2021, the Company entered into a Controlled Equity Offering SM Sales Agreement (the "Sales Agreement"), with Cantor Fitzgerald & Co. (the "Agent"). From time to time during the term of the Sales Agreement, the Company may offer and sell shares of common stock having an aggregate offering price up to a total of $50.0 million in gross proceeds. The Agent will collect a fee equal to 3% of the gross sales price of all shares of common stock sold. Shares of common stock sold under the Sales Agreement are offered and sold pursuant to the Company's registration statement on Form S-3, which was filed with the U.S. Securities and Exchange Commission ("SEC") on April 16, 2021 and declared effective on April 29, 2021. During the year ended December 31, 2022, the Company sold 415,005 shares of common stock pursuant to the Sales Agreement at an average price of $2.60 per share for aggregate net proceeds of approximately $1.0 million. Subsequent to December 31, 2022, the Company sol d 76,882 shares of common stock pursuant to the Sales Agreement at an average price of $3.59 for aggregate net proceeds of approximately $0.3 million. There remains approximately $39.2 million available for future sales of shares of common stock under the Sales Agreement. Other than the Sales Agreement, the Company currently does not have any commitments to obtain additional funds. In December 2020, the Company, together with its wholly-owned subsidiary, SLSG Limited, LLC, entered into an Exclusive License Agreement (the “3DMed License Agreement”) with 3D Medicines Inc. ("3DMed"), pursuant to which the Company granted 3DMed a sublicensable, royalty-bearing license, under certain intellectual property owned or controlled by the Company, to develop, manufacture and have manufactured, and commercialize GPS and heptavalent GPS product candidates for all therapeutic and other diagnostic uses in mainland China, Hong Kong, Macau and Taiwan ("3DMed Territory"). To date, the Company has received $10.5 million in upfront payments and certain technology transfer and regulatory milestones. The participation of 3DMed in the Company's REGAL Phase 3 clinical trial in China will trigger two development milestone payments totaling $13.0 million to the Company, which the Company expects to receive in the first half of 2023. A total of $191.5 million in potential future development, regulatory, and sales milestones, not including future royalties, remains under the 3DMed License Agreement as of December 31, 2022, which milestones are all variable in nature and not under the Company's control. The Company will require substantial additional financing to commercially develop any current or future product candidates. If the Company is unable to obtain additional funding on a timely basis, it will be required to scale back its plans and place certain activities on hold. Other than the Sales Agreement, the Company currently does not have any commitments to obtain additional funds. The Company's management continues to evaluate different strategies to obtain the required funding for future operations. These strategies may include utilizing the Sales Agreement, public and private placements of equity and/or debt securities and payments from potential strategic research and development collaborations. Additionally, the Company may pursue discussions with global and regional pharmaceutical companies for licensing and/or co-development rights to its product candidates. The Company has prepared its consolidated financial statements assuming that it will continue as a going concern, which contemplates the realization of assets and the satisfaction of liabilities in the normal course of business.

Basis of Presentation and Signi

Basis of Presentation and Significant Accounting Policies	12 Months Ended
	Dec. 31, 2022
Accounting Policies [Abstract]
Basis of Presentation and Significant Accounting Policies	Basis of Presentation and Significant Accounting Policies Basis of Presentation The accompanying consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States (“U.S. GAAP”). Any reference in these notes to applicable guidance is meant to refer to U.S. GAAP as found in the Accounting Standards Codification ("ASC") and Accounting Standards Updates (“ASU”) of the Financial Accounting Standards Board (“FASB”). Principles of Consolidation The consolidated financial statements include the financial statements of the Company and its wholly owned subsidiaries. All significant intercompany accounts and transactions have been eliminated upon consolidation. Unless the context otherwise indicates, reference in these notes to the "Company" refer to SELLAS Life Sciences Group, Inc., and its wholly owned subsidiaries, Private SELLAS, SLSG Limited, LLC, Sellas Life Sciences Limited, and Apthera, Inc. The functional currency of the Company's non-U.S. operations is the U.S. dollar. Use of Estimates The preparation of these consolidated financial statements in accordance with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. On an ongoing basis, the Company evaluates its estimates using historical experience and other factors, including the current economic environment. Significant items subject to such estimates are assumptions used for purposes of determining stock-based compensation, carrying value of goodwill, accounting for deferred income taxes, and accounting for research and development activities. Management believes its estimates to be reasonable under the circumstances. Actual results could differ significantly from those estimates. Segment Information Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company views its operations and manages its business in one segment. Fair Value of Financial Instruments The Company measures certain financial assets and liabilities at fair value on a recurring basis. Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or a liability. A three-tier fair value hierarchy is established as a basis for considering such assumptions and for inputs used in the valuation methodologies in measuring fair value: Level 1—Quoted prices in active markets for identical assets or liabilities. Level 2—Inputs other than quoted prices included within Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. As of December 31, 2022 and 2021, the carrying amounts of the Company’s financial instruments, including cash equivalents and accounts payable, approximate fair value due to the short-term nature of those instruments and were categorized as Level 1. As of December 31, 2022 and 2021, the carrying amounts of the Company’s contingent consideration and liability-classified warrants are each recorded at their estimated fair value. The fair value of the contingent consideration and warrants utilize certain unobservable inputs that fall within Level 3 of the fair value hierarchy. See Note 6 for additional information on the fair value of certain financial assets and liabilities. Concentration of Credit Risk Financial instruments that potentially expose the Company to concentrations of credit risk consist principally of cash on deposit with financial institutions, the balances of which frequently exceed federally insured limits. On March 10, 2023, Silicon Valley Bank ("SVB") was closed by the California Department of Financial Protection and Innovation, which appointed the Federal Deposit Insurance Corporation ("FDIC") as receiver. If any of the financial institutions with whom we do business were to be placed into receivership, we may be unable to access to the cash we have on deposit with such institutions. Impact of COVID-19 Public health crises such as pandemics or similar outbreaks could adversely impact our business. Notably, the COVID-19 pandemic continues to evolve. The extent to which COVID-19 impacts our operations or those of our collaborators, contractors, suppliers, CROs, clinical sites, CMOs and other material business relations and governmental agencies will depend on future developments, which are highly uncertain and cannot be predicted with confidence, including the ultimate duration of the outbreak, new information that will emerge concerning the severity of the virus and the actions to contain it or treat its impact, among others. Previously, our clinical trial operations were directly and indirectly adversely impacted, and could continue to be directly and indirectly adversely impacted, by the COVID-19 pandemic. While the potential economic impact brought by, and the ultimate duration of, the COVID-19 pandemic, have been, and continue to be, difficult to assess or predict, the spread of COVID-19 has caused a broad impact globally. The extent to which the COVID-19 pandemic may impact our business continues to be highly uncertain and cannot be predicted with confidence. Cash and Cash Equivalents The Company considers any highly liquid investments, such as money market funds, with an original maturity of three months or less to be cash and cash equivalents. Restricted Cash and Cash Equivalents Restricted cash consists of certificates of deposit on hand with the Company’s financial institutions as collateral for its corporate credit cards. The following table provides a reconciliation of the components of cash, cash equivalents, restricted cash, and restricted cash equivalents reported in the Company's consolidated balance sheets to the total amount presented in the consolidated statements of cash flows (in thousands): December 31, 2022 2021 Cash and cash equivalents $ 17,125 $ 21,355 Restricted cash and cash equivalents 100 100 Total cash, cash equivalents, restricted cash, and restricted cash equivalents $ 17,225 $ 21,455 The Company maintained $0.1 million as of December 31, 2022 and 2021, on hand with the Company's financial institutions as collateral for its corporate credit cards. Goodwill Goodwill is the excess of the cost of an acquired entity over the net amounts assigned to tangible and intangible assets acquired and liabilities assumed. Goodwill is not amortized but is subject to an annual impairment test. The Company has a single reporting unit and all goodwill relates to that reporting unit. The Company performs its annual goodwill impairment test in the fourth quarter of each fiscal year or more frequently if changes in circumstances or the occurrence of events suggest that an impairment exists. The Company did not recognize any impairment of goodwill during the years ended December 31, 2022 and 2021. Contingent Consideration The consideration for Galena's acquisition of Apthera, Inc. in 2011 includes future payments that are contingent upon the achievement of certain events related to the development and commercialization of nelipepimut-S ("NPS"). Contingent consideration, and the obligations for such contingent consideration payments, is required to be recognized at fair value as of the acquisition date. The contingent consideration obligations are then evaluated each reporting period and changes in the fair value of contingent consideration, other than changes due to payments, are recognized as a gain or loss and recorded within the change in the fair value of contingent consideration in the Company's consolidated statements of operations. The fair value of development and regulatory milestones are estimated utilizing a probability adjusted, discounted cash flow approach. The fair value of net sales milestones is based on probability adjusted sales estimates and estimated discount rates and utilizes an option pricing model with Monte Carlo simulation to simulate a range of possible payment scenarios, and the average of the payments in these scenarios is then discounted to calculate present fair value. The discount rates used are an estimated measure of credit risk associated with the years of expected payments based on the current development stage of the associated product candidate, the Company's specific development plan for that product candidate adjusted for the probability of completing the stages of development and when the contingent payments would be triggered. In estimating the probability of success, the Company utilizes data regarding similar milestone events from several sources, including industry studies and the Company's experience. The fair value of the contingent consideration is classified as a Level 3 liability as the valuation requires substantial judgment and estimation of factors that are not currently observable in the market. If different assumptions were used for the various inputs to the valuation, including but not limited to, assumptions involving the probability of success, estimated discount rate, and projected years of payment, the estimated fair value could be significantly higher or lower than the fair value determined. See Note 6 for additional information on the contingent consideration. Leases The Company accounts for its leasing arrangements under ASU No. 2016-02, Leases (Topic 842) (“Topic 842”). Under Topic 842, all significant lease arrangements are generally recognized at lease commencement. Operating lease right-of-use ("ROU"), assets and lease liabilities are recognized at the commencement date. An ROU asset and corresponding lease liability is not recorded for leases with an initial term of 12 months or less (short term leases) and the Company recognizes lease expense for these leases as incurred over the lease term. ROU assets represent the Company’s right to use an underlying asset during the reasonably certain lease terms and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. The Company’s lease terms may include options to extend or terminate the lease when it is reasonably certain that the option will be exercised. Operating lease ROU assets and liabilities are recognized at commencement date based on the present value of lease payments over the lease term. The Company primarily uses its incremental borrowing rate, based on the information available at commencement date, in determining the present value of lease payments. The operating lease ROU asset also includes any lease payments related to initial direct cost and prepayments and excludes lease incentives. Lease expense is recognized on a straight-line basis over the lease term. The Company’s lease agreements contain lease and non-lease components, which are generally accounted for separately. See Note 8 for discussion of the Company’s facility lease. Revenue Recognition The Company records revenue in accordance with ASC Topic 606, Revenue From Contracts with Customers ("Topic 606"). This standard applies to all contracts with customers, except for contracts that are within the scope of other standards, such as leases, insurance, collaboration arrangements and financial instruments. Under Topic 606, an entity recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration that the entity expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that an entity determines are within the scope of Topic 606, the entity 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 entity satisfies a performance obligation. The Company only applies the five step model to contracts when it is probable that the entity will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, once the contract is determined to be within the scope of Topic 606, the Company assesses the goods or services promised within each contract and determines those that are performance obligations, and assesses whether each promised good or service is distinct. The Company then allocates the transaction price to each distinct performance obligation based on its relative standalone selling price. The Company recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied. See Note 11 for further discussion of the Company's revenue recognition associated with the 3DMed License Agreement. Development, Regulatory and Sales Milestones and Other Payments At the inception of each arrangement that includes regulatory or development milestone payments, the Company evaluates whether the milestones are considered probable of being achieved and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the control of the Company or the licensee, such as regulatory approvals, are not considered probable of being achieved until those approvals are received. The Company evaluates factors such as the scientific, clinical, regulatory, commercial, and other risks that must be overcome to achieve the particular milestone in making this assessment. There is considerable judgment involved in determining whether it is probable that a significant revenue reversal would not occur. At the end of each subsequent reporting period, the Company reevaluates the probability of achievement of all milestones subject to constraint and, if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect revenues and earnings in the period of adjustment. For arrangements that include sales-based royalties, including milestone payments upon first commercial sales and milestone payments based on a level of sales, which are the result of a customer-vendor relationship and for which the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied or partially satisfied. To date, the Company has not recognized any royalty revenue resulting from any of its licensing arrangements. Acquired In-Process Research and Development Costs incurred in obtaining technology licenses are immediately recognized as acquired in-process research and development expense, provided the technology licensed has no alternative future use as the technology and know-how acquired are not currently commercially viable. Payments related to contingent consideration such as development milestones, commercial milestones and royalties (Note 8) will be recognized when the contingency is probable and reasonably estimable in accordance with ASC 450, Contingencies . Research and Development Expenses Research and development costs are expensed as incurred. Research and development costs that are paid in advance of performance are capitalized as a prepaid expense and recognized as research and development expenses as the services are provided. Clinical study costs, a component of research and development expenses, are accrued over the service periods specified in the contracts and adjusted as necessary based on an ongoing review of the level of effort and costs actually incurred. Research and development expenses consist primarily of development research performed by contract research organizations ("CROs"), personnel costs, including salaries, benefits and stock-based compensation, clinical drug supply, investigator grants, materials and supplies, consulting fees, licenses and fees, preclinical studies, and overhead allocations consisting of various support and facility-related costs. Stock-based Compensation The Company measures employee and non-employee director share-based awards at their grant-date fair value and records compensation expense on a straight-line basis over the vesting period of the awards. Estimating the fair value of share-based awards requires the input of subjective assumptions, including the expected life of the options and stock price volatility. The Company accounts for forfeitures for stock option awards as they occur. The Company uses the Black-Scholes option pricing model to value its stock option awards. The assumptions used in estimating the fair value of share-based awards represent management’s estimate and involve inherent uncertainties and the application of management’s judgment. As a result, if factors change and management uses different assumptions, share-based compensation expense could be materially different for future awards. The expected life of the stock options is estimated using the “simplified method,” as the Company has limited historical information from which to develop reasonable expectations about future exercise patterns and post-vesting employment termination behavior for its stock option grants. The simplified method is the midpoint between the vesting period and the contractual term of the option. The stock price volatility assumption is based on the historical volatility of the Company's publicly traded common stock. The risk-free rate is based on the U.S. Treasury yield curve commensurate with the expected life of the option. Restricted Stock Units with Performance and Service Conditions The Company's Board of Directors has granted restricted stock units ("RSUs") to certain employees that vest based on performance and service conditions. The fair values of the performance-based RSUs are measured on the date of grant and are based on the Company's closing stock price on such date. Compensation expense is recognized for the number of performance-based RSUs expected to be earned, provided the requisite service period has been rendered, after assessing the probability that certain performance criteria will be met. Cumulative adjustments are recorded each quarter to reflect the estimated outcome of the performance-related conditions until the date results are determined and settled. The Company accounts for forfeitures of performance-based RSUs when they occur. If performance criteria are not met or are not expected to be met, any compensation expense previously recognized to date associated with the performance-based RSUs will be reversed. Restricted Stock Units with Service Conditions Only The Board of Directors has granted RSUs to certain employees that vest based on continuous service. Time-vested RSUs awarded to employees vest one-fourth per year annually over four years, provided the employee remains employed with the Company. The fair values of the time-vested RSUs are measured on the date of grant and are based on the Company's closing stock price on such date. Compensation expense for time-vested RSUs with service conditions only are recognized straight-line over the applicable service period. The Company accounts for forfeitures of time-vested RSUs when they occur. Previously recognized compensation expense for forfeited RSUs are reversed in the period the time-vested RSUs are forfeited. Income Taxes The Company uses the asset and liability method of accounting for income taxes. Deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and operating loss and credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. A valuation allowance is provided when it is more likely than not that some portion or all of a deferred tax asset will not be realized. The Company recognizes the benefit of an uncertain tax position that it has taken or expects to take on its income tax returns, if such a position is more likely than not to be sustained. Potential interest and penalties associated with unrecognized tax positions are recognized in income tax expense. No interest or penalties were recognized in either of the years ended December 31, 2022 or 2021. The Company recognizes liabilities or assets for the deferred tax consequences of temporary differences between the tax basis of assets or liabilities and their reported amounts in the consolidated financial statements in accordance with FASB ASC 740-10, “ Accounting for Income Taxes” (“ASC 740-10”). These temporary differences will result in taxable or deductible amounts in future years when the reported amounts of the assets or liabilities are recovered or settled. ASC 740-10 requires that a valuation allowance be established when management determines that it is more likely than not that all or a portion of a deferred asset will not be realized. The Company evaluates the realizability of its net deferred income tax assets and valuation allowances as necessary, at least on an annual basis. During this evaluation, the Company reviews its forecasts of income in conjunction with other positive and negative evidence surrounding the realizability of its deferred income tax assets to determine if a valuation allowance is required. Adjustments to the valuation allowance will increase or decrease the Company’s income tax provision or benefit. The recognition and measurement of benefits related to the Company’s tax positions requires significant judgment, as uncertainties often exist with respect to new laws, new interpretations of existing laws, and rulings by taxing authorities. Differences between actual results and the Company’s assumptions or changes in the Company’s assumptions in future periods are recorded in the period they become known. Net Loss Per Share Basic loss per share is computed by dividing net loss applicable to common stockholders by the weighted average number of shares of common stock outstanding during each period. Diluted loss per share includes the effect, if any, from the potential exercise or conversion of securities, such as warrants, stock options and unvested restricted stock that would result in the issuance of incremental shares of common stock. In computing the basic and diluted net loss per share, the weighted average number of shares remains the same for both calculations due to the fact that when a net loss exists, dilutive shares are not included in the calculation as the impact is anti-dilutive. The following potentially dilutive securities outstanding have been excluded from the computation of diluted weighted average shares outstanding, as their impact would be anti-dilutive (in thousands): December 31, 2022 2021 Common stock warrants 5,141 519 Stock options 1,040 534 Restricted stock units 255 200 6,436 1,253 Recent Accounting Pronouncements Adopted In May 2021, the FASB issued ASU No. 2021-04, Issuer’s Accounting for Certain Modifications of Exchanges of Freestanding Equity-Classified Written Call Options, to clarify the accounting for modifications or exchanges of freestanding equity-classified written call options, such as warrants, that remain equity classified after modification or exchange. This ASU became effective for the Company on January 1, 2022 and did not have a material impact on the Company's consolidated financial statements. Recent Accounting Standards Not Yet Adopted In August 2020, the FASB issued ASU No. 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity, which, among other things, simplifies the accounting models for the allocation of proceeds attributable to the issuance of a convertible debt instrument. As a result, after adopting the ASU’s guidance, entities will not separately present in equity an embedded conversion feature in such debt. Instead, they will account for a convertible debt instrument wholly as debt, and for convertible preferred stock wholly as preferred stock (i.e., as a single unit of account), unless (i) a convertible instrument contains features that require bifurcation as a derivative under ASC 815 or (ii) a convertible debt instrument was issued at a substantial premium. The standard becomes effective for the Company in the first quarter of 2024 and

Goodwill and Intangible Assets

Goodwill and Intangible Assets	12 Months Ended
	Dec. 31, 2022
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	Goodwill and Intangible Assets A reconciliation of the change in goodwill and intangible assets for the years ended December 31, 2022 and 2021 is as follows (in thousands): In-Process Research and Development Goodwill December 31, 2020 $ 5,700 $ 1,914 Impairment charge (5,700) — December 31, 2021 — 1,914 Impairment charge — — December 31, 2022 $ — $ 1,914 The Company completes its annual impairment test on October 1 each year, or more frequently if triggering events indicate a possible impairment. The Company continually evaluates financial performance, economic conditions and other relevant developments in assessing if an interim period impairment test is necessary. The Company's goodwill balance at December 31, 2022 and 2021 was $1.9 million. As of December 31, 2022 and 2021, there were no accumulated impairment losses related to goodwill.

Collaboration and In-License Ag

Collaboration and In-License Agreements	12 Months Ended
	Dec. 31, 2022
License Agreements [Abstract]
Collaboration and In-License Agreements	Collaboration and In-License Agreements As part of its business, the Company enters into in-licensing agreements with third parties that often require milestone and royalty payments based on the progress of the licensed asset through development and commercial stages. Milestone payments may be required, for example, upon approval of the product for marketing by a regulatory agency, and the Company may be required to make royalty payments based upon a percentage of net sales of the product. The expenditures required under these arrangements in any period may be material and are likely to fluctuate from period to period. These arrangements may permit the Company to unilaterally terminate development of the product and thereby avoid future contingent payments; however, the Company is unlikely to cease development if the compound successfully achieves clinical testing objectives. Exclusive License Agreement with GenFleet Therapeutics (Shanghai) Inc. On March 31, 2022, the Company entered into an exclusive license agreement with GenFleet pursuant to which GenFleet granted to the Company a sublicensable, royalty-bearing license, under certain of its intellectual property, to develop, manufacture, and commercialize GFH009 for the treatment, diagnosis or prevention of disease in humans and animals in all countries and territories of the world other than mainland China, Hong Kong, Macau and Taiwan (the "GFH009 Territory"). GFH009 is currently in a Phase 1 clinical trial in the United States and China. In consideration for the exclusive license, the Company has agreed to pay to GenFleet (i) an upfront and technology transfer fee of $10.0 million, $4.5 million of which was payable within 30 days of the effective date of the license agreement which was March 31, 2022, and $5.5 million of which is due upon the first day of the 15th calendar month following the effective date of the license agreement, (ii) development and regulatory milestone payments for up to three indications totaling up to $48.0 million in the aggregate, and (iii) sales milestone payments totaling up to $92.0 million in the aggregate upon the achievement of certain net sales thresholds in a given calendar year. The Company has also agreed to pay GenFleet single-digit tiered royalties based upon a percentage of annual net sales of GFH009 in the GFH009 Territory, with the royalty rate escalating based on the level of annual net sales and ranging from the low to high single digits. During the year ended December 31, 2022, the Company expensed $10.0 million related to the acquired technology as in-process research and development based on the assessment that the technology has no alternative future use as the technology and know-how acquired are not currently commercially viable, $4.5 million of which was paid in April 2022 and the remaining $5.5 million expected to be paid by the end of the second quarter of 2023 for which the Company has recorded an acquired in-process research and development payable as of December 31, 2022. Exclusive License Agreement with Memorial Sloan Kettering Cancer Center ("MSK") On September 4, 2014, the Company entered into a license agreement (the “Original MSK License Agreement”) with MSK under which the Company was granted an exclusive license to develop and commercialize MSK’s WT1 peptide vaccine technology. The Original MSK License Agreement, unless terminated earlier in accordance with the terms of the Original MSK License Agreement, will continue on a country-by-country and licensed product-by-licensed product basis, until the later of: (i) expiration of the last valid claim embracing such licensed product; (ii) expiration of any market exclusivity period granted by law with respect to such licensed product; or (iii) ten (10) years from the first commercial sale in such country. On May 25, 2017, the Company and MSK entered into an Amended and Restated Exclusive License Agreement (the “MSK A&R License Agreement”). Under the MSK A&R License Agreement, the Company expanded its license under the original MSK License Agreement, as amended, to include a license to commercially develop certain additional WT1 peptides through a program of exploiting certain patents and other rights covering such peptides. The MSK A&R License Agreement, among other changes, added certain milestone payments for each additional patent licensed product as defined in the MSK A&R License Agreement. On October 11, 2017, the Company and MSK entered into a second Amended and Restated Exclusive License Agreement (the “Second MSK A&R License Agreement”). Under the Second MSK A&R License Agreement, the Company and MSK extended certain milestone dates for the Company in exchange for increased milestone payments. The Compan y incurred $0.1 million of guaranteed minimum royalty payments under the Second MSK A&R License Agreement during the years ended December 31, 2022 and 2021. Such expenses have been included in research and development costs. The Compan y incurred $0.1 million and $0.2 million of sublicensing fees payable under the Second MSK A&R License Agreement in connection with the 3DMed Agreement during the years ended December 31, 2022 and 2021, respectively, included in cost of revenue. Merck & Co., Inc. Clinical Trial Collaboration and Supply Agreement On September 21, 2017, the Company entered into a clinical trial collaboration and supply agreement (the "Merck Agreement") through a Merck & Co., Inc. subsidiary, Merck Sharp & Dohme B.V. (“Merck subsidiary”), whereby the Company agreed with the Merck subsidiary to collaborate in a research program to evaluate GPS as it is administered in combination with Merck’s PD1 blocker pembrolizumab in a Phase 1/2 clinical trial enrolling patients in up to five cancer indications, including both hematologic malignancies and solid tumors assessing the efficacy and safety of the combination, comparing overall response rates and immune response markers achieved with the combination compared to prespecified rates based on those seen with pembrolizumab alone in comparable patient populations. In the fourth quarter of 2018, pursuant to the Merck Agreement, the Company initiated a Phase 1/2 multi-arm ("basket" type) clinical study of GPS in combination with Merck & Co., Inc.’s anti-PD-1 therapy, pembrolizumab (Keytruda) in patients with WT1+ relapsed or refractory tumors. In July 2019, the Company dosed the first patient in this trial. In 2020, the Company, together with Merck determined to focus on ovarian cancer (second or third line). In November 2022, the Company reported topline clinical and initial immune response data from the clinical trial which showed that treatment with the combination of GPS and pembrolizumab compared favorably to treatment with anti-PD-1 therapy alone in a similar patient population. The Company plans to present final data from this study at a medical conference in the first half of 2023. The University of Texas M. D. Anderson Cancer Center and The Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc. On September 11, 2006, the Company acquired rights and assumed obligations under a license agreement among Apthera and The University of Texas M. D. Anderson Cancer Center (“MDACC”) and The Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc. (“HJF”) which grants exclusive worldwide rights to a U.S. patent covering NPS and several U.S. and foreign patents and patent applications covering methods of using the peptide as a vaccine. Under the terms of this license, the Company is required to pay an annual maintenance fee of $0.2 million, up to $3.8 million for clinical milestone payments, and to pay a tiered royalty in the mid-single digits based on sales of NPS or other therapeutic products developed from the licensed technologies. The Company incurred the annual maintenance fee during the years ended December 31, 2022 and 2021 and the expenses have been included in research and development costs.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2022
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The following tables present information about the Company's assets and liabilities measured at fair value on a recurring basis in the consolidated balance sheets (in thousands): Description December 31, 2022 Quoted Prices In Significant Other Unobservable Assets: Cash equivalents $ 16,609 $ 16,609 $ — $ — Restricted cash equivalents 100 100 — — Total assets measured and recorded at fair value $ 16,709 $ 16,709 $ — $ — Liabilities: Warrants potentially settleable in cash $ 4 $ — $ — $ 4 Contingent consideration — — — — Total liabilities measured and recorded at fair value $ 4 $ — $ — $ 4 Description December 31, 2021 Quoted Prices In Significant Other Unobservable Assets: Cash equivalents $ 21,000 $ 21,000 $ — $ — Restricted cash equivalents 100 100 — — Total assets measured and recorded at fair value $ 21,100 $ 21,100 $ — $ — Liabilities: Warrants potentially settleable in cash $ 40 $ — $ — $ 40 Contingent consideration 296 — — 296 Total liabilities measured and recorded at fair value $ 336 $ — $ — $ 336 The Company did not transfer any financial instruments into or out of Level 3 classification during the years ended December 31, 2022 and 2021. See Note 10 for a reconciliation of the changes in the fair value of the warrant liability for the year ended December 31, 2022. The Company presents the contingent consideration liability at fair value and it is measured at the end of each reporting period using Level 3 inputs. The contingent consideration relates to Galena’s acquisition of Apthera, Inc. in 2011 and the future contingent payments based on the achievement of certain regulatory and net sales milestones relating to NPS. The contingent consideration is payable at the election of the Company in either cash or shares of common stock, provided that the Company may not issue any shares in satisfaction of any contingent consideration unless it has first obtained approval of its stockholders in accordance with Rule 5635(a) of the Nasdaq Marketplace Rules. A reconciliation of the change in the fair value of the contingent consideration liability for the year ended December 31, 2022 and 2021 is as follows (in thousands): Fair Value Contingent consideration, December 31, 2020 $ 4,633 Change in the estimated fair value of the contingent consideration (4,337) Contingent consideration, December 31, 2021 296 Change in the estimated fair value of the contingent consideration (296) Contingent consideration, December 31, 2022 $ — During the year ended December 31, 2022, the significant unobservable inputs were adjusted in connection with ceasing all development activities of NPS and concluding the Company's extensive out-licensing efforts. See Note 2 for further discussion on how the Company determines the fair value of its contingent consideration. The following significant unobservable inputs were used in the valuation of the contingent consideration liability: Unobservable input As of December 31, 2022 As of December 31, 2021 Potential milestone payments $0 - $30 million $0 - $30 million Discount rate n/a 15.5 % Cumulative probability of success — % 5.3 % Projected years of payments n/a 2028 - 2031

Balance Sheet Accounts

Balance Sheet Accounts	12 Months Ended
	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Balance Sheet Accounts	Balance Sheet Accounts Prepaid expenses and other current assets consist of the following (in thousands): December 31, 2022 2021 Clinical trial costs $ 184 $ 1,309 Insurance 219 217 Professional fees 82 36 Other 46 27 Prepaid expenses and other current assets $ 531 $ 1,589 Accrued expenses and other current liabilities consist of the following (in thousands): December 31, 2022 2021 Clinical trial costs $ 4,509 $ 1,325 Compensation and related benefits 1,439 989 Professional fees 338 165 Other — 161 Accrued expenses and other current liabilities $ 6,286 $ 2,640

Legal Proceedings, Commitments

Legal Proceedings, Commitments and Contingencies	12 Months Ended
	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Legal Proceedings, Commitments and Contingencies	Legal Proceedings, Commitments and Contingencies Legal Proceedings From time to time, the Company is subject to various pending or threatened legal actions and proceedings, including those that arise in the ordinary course of its business, which may include employment matters, breach of contract disputes and stockholder litigation. Such actions and proceedings are subject to many uncertainties and to outcomes that are not predictable with assurance and that may not be known for extended periods of time. The Company records a liability in its consolidated financial statements for costs related to claims, including future legal costs, settlements and judgments, when the Company has assessed that a loss is probable and an amount can be reasonably estimated. If the reasonable estimate of a probable loss is a range, the Company records the most probable estimate of the loss or the minimum amount when no amount within the range is a better estimate than any other amount. The Company discloses a contingent liability even if the liability is not probable or the amount is not estimable, or both, if there is a reasonable possibility that a material loss may have been incurred. As of December 31, 2022, there was no pending or threatened litigation. Contingent Consideration related to Development, Regulatory and Commercial Milestone Payments and Business Combinations The Company acquires assets still in development and enters into research and development arrangements with third parties that often require milestone and royalty payments based on the progress of the asset through development stages. Milestone payments may be required, for example, upon approval of the product for marketing by a regulatory agency. In certain agreements, the Company is required to make royalty payments based upon a percentage of the sales. These arrangements may be material individually, and in the unlikely event that milestones for multiple products covered by these arrangements were reached in the same period, the aggregate charge to expense could be material to the results of operations. In addition, these arrangements often give the Company the discretion to unilaterally terminate development of the product, which would allow the Company to avoid making the contingent payments; however, the Company is unlikely to cease development if the compound successfully achieves clinical testing objectives. See Note 5 for additional information on the Company’s commitments under collaboration and license agreements and commitments of contingent consideration. Leases The Company has a non-cancelable operating lease for certain executive, administrative, and general business office space for its headquarters in New York, New York, which began June 5, 2020, was amended in February 2022 to add additional space, and has a term through December 31, 2024. The Company assessed the lease amendment for the additional space and determined it should be accounted for as a separate contract. The weighted average discount rate used to account for the Company's operating lease under ASC 842, Leases, is approximately 13.95%. As of December 31, 2022, the leases have a remaining term of 2.0 years. Rent expense related to the Company's operating lease was approximately $0.5 million and $0.3 million for the years ended December 31, 2022 and 2021, respectively. The Company made cash payments related to operating leases of approximately $0.5 million and $0.3 million during the years ended December 31, 2022 and 2021, respectively. Future minimum rental payments under the Company's non-cancelable operating lease are as follows as of December 31, 2022 (in thousands): Total minimum lease payments: 2023 $ 518 2024 533 Total future minimum lease payments 1,051 Less: imputed interest (106) Operating lease liabilities $ 945

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2022
Equity [Abstract]
Stockholders' Equity	Stockholders’ Equity Preferred Stock The Company has authorized up to 5,000,000 shares of preferred stock, $0.0001 par value per share, for issuance. There were no preferred shares outstanding as of December 31, 2022 and 2021. Common Stock The Company has authorized up to 350,000,000 shares of common stock, $0.0001 par value per share, for issuance. On April 5, 2022, the Company consummated an underwritten public offering (the "April 2022 Offering"), issuing 4,629,630 shares of common stock and accompanying common stock warrants to purchase an aggregate of 4,629,630 shares of common stock. The shares of common stock and accompanying common stock warrants were sold at a combined price of $5.40 per share and accompanying common stock warrant. Each common stock warrant sold with the shares of common stock represents the right to purchase one share of the Company’s common stock at an exercise price of $5.40 per share. The common stock warrants are exercisable immediately and will expire on April 5, 2027, five years from the date of issuance. The net proceeds to the Company from the April 2022 Offering, after deducting the underwriting discounts and commissions and other offering expenses, and excluding the exercise of any warrants, were approximately $23.0 million. On April 16, 2021, the Company entered into the Sales Agreement with Cantor Fitzgerald & Co. (the "Agent"). From time to time during the term of the Sales Agreement, the Company may offer and sell shares of common stock having an aggregate offering price up to a total of $50.0 million in gross proceeds. The Agent will collect a fee equal to 3% of the gross sales price of all shares of common stock sold. During the year ended December 31, 2022, the Company sold 415,005 shares of common stock pursuant to the Sales Agreement at an average price of $2.60 per share for aggregate net proceeds of approximately $1.0 million. Subsequent to December 31, 2022, the Company sold 76,882 shares of common stock pursuant to the Sales Agreement at an average price of $3.59 for aggregate net proceeds of approximately $0.3 million. There remains approximately $39.2 million available for future sales of shares of common stock under the Sales Agreement. Other than the Sales Agreement, the Company currently does not have any commitments to obtain additional funds. Shares of common stock reserved for future issuance are as follows (in thousands): December 31, 2022 Warrants outstanding 5,141 Stock options outstanding 1,040 Restricted stock units outstanding 255 Options reserved for future issuance under the Company’s 2019 Equity Incentive Plan 641 Shares reserved for future issuance under the Employee Stock Purchase Plans 275 Total shares of common stock reserved for future issuance 7,352

Warrants to Acquire Shares of C

Warrants to Acquire Shares of Common Stock	12 Months Ended
	Dec. 31, 2022
Warrants and Rights Note Disclosure [Abstract]
Warrants to Acquire Shares of Common Stock	Warrants to Acquire Shares of Common Stock The following is a summary of the Company's warrants to acquire shares of common stock activity for the year ended December 31, 2022 (in thousands, except per share data): Warrant Issuance Outstanding, December 31, 2021 Granted Canceled/Expired Outstanding, December 31, 2022 Exercise Price Per Share Expiration Warrants classified as equity: April 2022 Offering — 4,630 — 4,630 $ 5.40 April 2027 January 2020 Offering 309 — — 309 $ 3.93 July 2025 July 2020 PIPE Offering 25 — — 25 $ 3.30 August 2025 July 2018 Offering 132 — — 132 $ 7.50 July 2023 March 2019 Exercise Agreement 30 — — 30 $ 7.50 March 2024 Other 9 — (7) 2 $ 7.50 June 2024 505 4,630 (7) 5,128 Warrants classified as liability: 14 — (1) 13 $ 7.50 September 2023 - November 2023 519 4,630 (8) 5,141 On February 28, 2023, in connection with closing of the February 2023 Offering, the Company entered into amendments to an aggregate of 3,438,851 warrants issued by the Company in the April 2022 Offering to reduce the exercise price of such warrants to $3.62, the average closing price of the Company’s common stock, as reported on the Nasdaq Capital Market, for the five trading days immediately preceding the pricing of the February 2023 Offering. Warrants to acquire shares of common stock primarily consist of equity-classified warrants. In addition, warrants to acquire shares of common stock that may require the Company to settle in cash are liability-classified warrants. Warrants Classified as Equity Equity-classified warrants consist of warrants to acquire common stock issued in connection with previous equity financings. During its evaluation of equity classification for warrants to acquire shares of common stock, the Company considered the conditions as prescribed within ASC 815-40, Derivatives and Hedging, Contracts in an Entity’s own Equity (“ASC 815-40”). The conditions within ASC 815-40 are not subject to a probability assessment. The warrants to acquire shares of common stock do not fall under the liability criteria within ASC 480, Distinguishing Liabilities from Equity , as they are not puttable and do not represent an instrument that has a redeemable underlying security. The warrants to acquire shares of common stock do meet the definition of a derivative instrument under ASC 815, but are eligible for the scope exception as they are indexed to the Company’s own stock and would be classified in permanent equity if freestanding. Warrants Classified as Liabilities Liability-classified warrants consist of warrants to acquire common stock issued in connection with previous equity financings. These warrants may be settled in cash and were determined to not be indexed to the Company’s common stock. The liability-classified warrants are grouped within other warrants outstanding in the table above. The estimated fair value of outstanding warrants accounted for as liabilities is determined at each balance sheet date. Any decrease or increase in the estimated fair value of the warrant liability since the most recent balance sheet date is recorded in the consolidated statement of operations as a change in fair value of warrant liability. The fair value of the warrants accounted for as liabilities is estimated using a Black-Scholes pricing model with the following inputs: As of December 31, 2022 2021 Risk free interest rate 4.75 % 0.65 % Volatility 120.60% 131.04% Expected term (years) 0.75 1.75 Expected dividend yield — % — % Strike price $ 7.50 $ 7.50 The changes in fair value of the warrant liability for the year ended December 31, 2022 and 2021 were as follows (in thousands): Warrant Liability Warrant liability, December 31, 2020 $ 55 Change in fair value of warrants (15) Warrant liability, December 31, 2021 40 Change in fair value of warrants (36) Warrant liability, December 31, 2022 $ 4

License Revenue with 3D Medicin

License Revenue with 3D Medicines, Inc.	12 Months Ended
	Dec. 31, 2022
Revenue from Contract with Customer [Abstract]
License Revenue with 3D Medicines, Inc.	License Revenue with 3D Medicines, Inc. Exclusive License Agreement with 3D Medicines, Inc. In December 2020, the Company, together with its wholly-owned subsidiary, SLSG Limited, LLC, entered into the 3DMed License Agreement with 3DMed, pursuant to which the Company granted 3DMed a sublicensable, royalty-bearing license, under certain intellectual property owned or controlled by the Company, to develop, manufacture and have manufactured, and commercialize GPS and heptavalent GPS (referred to as GPS Plus) product candidates ("GPS Licensed Products") for all therapeutic and other diagnostic uses in the 3DMed Territory. The license is exclusive except with respect to certain know-how that has been non-exclusively licensed to the Company and is sublicensed to 3DMed on a non-exclusive basis. The Company has retained development, manufacturing and commercialization rights with respect to the GPS Licensed Products in the rest of the world. In partial consideration for the rights granted by the Company, 3DMed agreed to pay the Company (i) a one-time upfront cash payment of $7.5 million, and (ii) milestone payments totaling up to $194.5 million in the aggregate upon the achievement of certain technology transfer, development and regulatory milestones, as well as sales milestones based on certain net sales thresholds of GPS Licensed Products in the 3DMed Territory in a given calendar year. 3DMed also agreed to pay tiered royalties based upon a percentage of annual net sales of GPS Licensed Products in the 3DMed Territory ranging from the high single digits to the low double digits. Revenue Recognition The Company evaluated the 3DMed License Agreement and concluded that 3DMed was a customer and the contract should be evaluated under ASC 606. In determining the appropriate amount of revenue to be recognized under ASC 606 as the Company fulfills its obligations under the Agreement, the Company performs the following steps: (i) identifies the promised goods or services in the contract; (ii) determines whether the promised goods or services are performance obligations including whether they are distinct in the context of the contract; (iii) measures the transaction price, including any constraints on variable consideration; (iv) allocates the transaction price to the performance obligations; and (v) recognizes revenue when (or as) the Company satisfies each performance obligation. The Company determined the initial transaction price of the single performance obligation to be $9.5 million, which includes the $7.5 million upfront fee as well as $2.0 million in development milestones that were assessed to be probable of being achieved at the inception of the 3DMed License Agreement and therefore were not constrained. During the year ended December 31, 2021, the Company recognized the remaining $7.6 million of the initial transaction price as license revenue. As of December 31, 2021, the full $9.5 million initial transaction price was fully recognized as licensing revenue. The Company determined that the remaining $192.5 million in certain future development, regulatory, and sales milestones is variable consideration subject to constraint at inception. At the end of each reporting period, the Company reevaluates the probability of achievement of the future development, regulatory, and sales milestones subject to constraint and, if necessary, will adjust its estimate of the overall transaction price. Any such adjustments will be recorded on a cumulative catch-up basis, which would affect revenues and earnings in the period of adjustment. On March 31, 2022, the Company announced that an IND application filed by 3DMed for a small Phase 1 clinical trial investigating safety of GPS in China was approved by China's NMPA. The IND approval by the NMPA triggered a $1.0 million milestone payment to the Company which was recognized as licensing revenue in the first quarter of 2022 and payment was received in May 2022. An additional $191.5 million in potential future development, regulatory, and sales milestones, not including future royalties, remains under the 3DMed License Agreement as of December 31, 2022, which milestones are variable in nature and not under the Company's control. For the sales-based royalties, the Company will recognize revenue when the related sales occur. To date, the Company has not recognized any royalty revenue resulting from any of its licensing arrangements. Cost of Contract Acquisition The Company incurred contract acquisition costs (commissions) recorded as a contract asset amounting to approximately $1.4 million at inception of the 3DMed License Agreement which were capitalized under ASC 340-40 as incremental costs of obtaining the 3DMed License Agreement. These costs were amortized through general and administrative expense over the technology transfer period, commensurate with when the license revenue was recognized. The Company recognized $1.1 million in expense associated with these costs during the year ended December 31, 2021. There were no such costs during the year ended December 31, 2022. Cost of License Revenue

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2022
Share-Based Payment Arrangement [Abstract]
Stock-Based Compensation	Stock-Based Compensation 2017 Equity Incentive Plan On December 29, 2017, the 2017 Equity Incentive Plan was approved by the stockholders of the Company, and currently allows for issuance of up to approximately 22,000 shares of common stock underlying stock options granted prior to September 10, 2019. The 2017 Equity Incentive Plan was terminated upon the approval of the 2019 Incentive Plan subject to outstanding stock options granted under the 2017 Equity Incentive Plan that remain exercisable through maturity for the Company's employees and directors. 2019 Equity Incentive Plan On September 10, 2019, the 2019 Equity Incentive Plan was approved by the stockholders of the Company, which currently allows for issuance of up to approximately 1,964,000 shares of common stock in connection with the grant of stock-based awards, including stock options, restricted stock, restricted stock units, stock appreciation rights and other types of awards as deemed appropriate. The number of shares reserved for issuance under the 2019 Equity Incentive Plan automatically increased on January 1 of each year up to and including January 1, 2023, by an amount equal to the lesser of (i) 5% of the total number of shares of common stock outstanding at the end of the prior fiscal year; and (ii) an amount determined by the board of directors or authorized committee. As of December 31, 2022, approximately 641,000 shares of common stock were reserved for future grants under the 2019 Equity Incentive Plan. The number of shares reserved for issuance under the 2019 Equity Incentive Plan was automatically increased to approximately 1,691,000 on January 1, 2023. The following table summarizes the components of stock-based compensation expense in the consolidated statements of operations for the years ended December 31, 2022 and 2021, respectively (in thousands): Years Ended December 31, 2022 2021 Research and development $ 270 $ 126 General and administrative 1,456 885 Total stock-based compensation $ 1,726 $ 1,011 Options to Purchase Shares of Common Stock The Company uses the Black-Scholes option-pricing model to estimate the fair value of stock-based awards and the following assumptions were used for stock options granted during the years ended December 31, 2022 and 2021, respectively: Years Ended December 31, 2022 2021 Risk free interest rate 1.96 % 1.05 % Volatility 131.51 % 121.53 % Expected lives (years) 6.18 6.18 Expected dividend yield — % — % The weighted-average grant date fair value of options granted during the years ended December 31, 2022 and 2021 was $4.52 and $6.98, respectively. The Company’s expected common stock price volatility assumption is based upon the Company's own implied volatility in combination with the implied volatility of a basket of comparable companies. The expected life assumptions for employee grants were based upon the simplified method, which averages the contractual term of the Company’s options of ten years with the average vesting term of four years for an average of six years. The expected life assumptions for non-employees were based upon the contractual term of the option. The dividend yield assumption is zero because the Company has never paid cash dividends and presently has no intention to do so. The risk-free interest rate used for each grant was also based upon prevailing short-term interest rates. The Company accounts for forfeitures as they occur, therefore, outstanding stock options equal vested and expected to vest stock options. As of December 31, 2022, there was $2.9 million of unrecognized compensation cost related to outstanding stock options that is expected to be recognized as a component of the Company’s operating expenses over a weighted-average period of 2.55 years. The following table summarizes stock option activity of the Company for the years ended December 31, 2022 and 2021, respectively: Total Weighted Weighted Average Remaining Contractual Term (in years) Aggregate Outstanding at January 1, 2021 208 $ 13.38 Granted 326 8.00 Outstanding at December 31, 2021 534 10.09 Granted 546 5.01 Canceled (40) 6.17 Outstanding at December 31, 2022 1,040 $ 7.57 8.48 $ 91 Vested and exercisable at December 31, 2022 313 $ 12.38 7.63 $ 66 The aggregate intrinsic values of outstanding and exercisable stock options at December 31, 2022 were calculated based on the closing price of the Company’s common stock as reported on the Nasdaq Capital Market on December 31, 2022 of $2.36 per share. The aggregate intrinsic value equals the positive difference between the closing fair market value of the Company’s common stock and the exercise price of the underlying stock options. Time-Vested RSUs and RSUs with Performance Conditions The Company granted RSUs pursuant to the Company's 2019 Equity Incentive Plan that will settle in shares of common stock. As of December 31, 2021, there was $0.8 million of unrecognized compensation cost related to outstanding RSUs that is expected to be recognized as a component of the Company’s operating expenses over a weighted-average period of 1.97 years. The following table summarizes RSU activity of the Company for the years ended December 31, 2022 and 2021, respectively: Total Number of Shares Weighted Average Grant Date Fair Value Per Share Unvested at January 1, 2021 170 $ 1.89 Granted 40 $ 8.00 Vested (10) $ 8.00 Unvested at December 31, 2021 200 $ 2.81 Granted 97 $ 5.34 Vested (40) $ 6.01 Canceled (2) $ 5.34 Unvested at December 31, 2022 255 $ 3.25 2021 Employee Stock Purchase Plan On April 22, 2021, the Board of Directors adopted the 2021 Employee Stock Purchase Plan ("2021 ESPP") which was approved by the Company's stockholders on June 8, 2021. The 2021 ESPP allows employees to contribute up to 20% of their cash earnings, subject to a maximum of $25,000 per year under Internal Revenue Service rules, to be used to purchase shares of the Company's common stock on semi-annual purchase dates. The 2021 ESPP allows eligible employees to purchase shares of common stock at a price per share equal to 85% of the lower of the fair market value of the common stock at the beginning or end of each six-month offering period during the term of the 2021 ESPP.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company's loss before income taxes is as follows (in thousands): As of December 31, 2022 2021 U.S. $ (17,825) $ (6,956) Non - U.S. (23,476) (13,980) $ (41,301) $ (20,936) The components of federal and state income tax benefit are as follows (in thousands): As of December 31, 2022 2021 Current Federal $ — $ — State — 2 Foreign — — Total current — 2 Deferred expense Federal — (239) State — — Foreign — — Total deferred — (239) Total income tax benefit $ — $ (237) The components of net deferred tax assets are as follows (in thousands): As of December 31, 2022 2021 Net operating loss carryforwards $ 10,529 $ 9,059 Stock-based compensation 229 140 Licensing deduction deferral 4,503 3,236 Contingent consideration — 62 Lease liability 198 170 Capitalized Section 174 research and development 765 — Other 282 217 Gross deferred tax assets 16,506 12,884 Valuation allowance (16,322) (12,732) Net deferred tax assets $ 184 $ 152 The components of gross deferred tax liabilities are as follows (in thousands): As of December 31, 2022 2021 Right of use asset $ 184 $ 152 Gross deferred tax liability $ 184 $ 152 The net deferred tax liabilities are as follows (in thousands): As of December 31, 2022 2021 Net deferred tax asset $ 184 $ 152 Gross deferred tax liability (184) (152) Net deferred tax liability $ — $ — The provision for income taxes differs from the provision computed by applying the federal statutory rate to net loss before income taxes as follows: As of December 31, 2022 2021 U.S. federal statutory income tax rate (21.0) % (21.0) % State and local taxes, net of federal benefit (0.1) % (0.2) % Foreign rate differential 11.9 % 14.0 % Valuation allowance 8.7 % 5.8 % Permanent differences 0.2 % 0.2 % Other 0.3 % 0.1 % Effective income tax rate — % (1.1) % There was no income tax benefit or expense for the year ended December 31, 2022. The income tax benefit for the year ended December 31, 2021 primarily related to indefinite lived deferred tax liabilities. In assessing the realizability of deferred tax assets, management considers whether it is more-likely-than-not that some portion or all of the deferred tax assets will not be realized in the near term. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences become deductible. The valuation allowance increased by approximately $3.6 million for the year ended December 31, 2022, which was primarily driven by the acquired in-process research and development and NOL carryforwards. At December 31, 2022, the Company had domestic federal and state net operating loss carryforwards of approximately $49.4 million and $2.6 million, respectively, available to reduce future taxable income, which expire beginning in 2027. Under the provisions of the Internal Revenue Code, the net operating losses (“NOL”) and tax credit carryforwards are subject to review and possible adjustment by the Internal Revenue Service and state tax authorities. NOL and tax credit carryforwards may become subject to an annual limitation in the event of certain cumulative changes in the ownership interest of significant shareholders over a three-year period in excess of 50%, as defined under Sections 382 and 383 of the Internal Revenue Code of 1986, respectively, as well as similar state tax provisions. This could limit the amount of tax attributes that the Company can utilize annually to offset future taxable income or tax liabilities. The amount of the annual limitation, if any, will be determined based on the value of the Company immediately prior to the ownership change. Subsequent ownership changes may further affect the limitation in future years. The Company has completed several financings since its inception, which may have resulted in a change in control as defined by Sections 382 and 383 of the Internal Revenue Code, or could result in a change in control in the future. Utilization of the net operating loss and tax credits carryforwards may be limited by “ownership change” rules, as defined in Section 382 of the Internal Revenue Code of 1986, as amended, and similar state provisions. This annual limitation may result in the expiration of the net operating losses and credits before utilization. The Company files income tax returns in the United States and various state jurisdictions. For U.S. federal and state income tax purposes, the statute of limitations currently remains open for the years ending December 31, 2019 to present and December 31, 2018 to present, respectively. In addition, all of the net operating losses and research and development credit carryforwards that may be utilized in future years may be subject to examination. The Company does not recognize tax benefits that are not more-likely-than-not to be supported based upon the technical merits of the tax position taken. In assessing its unrecognized tax benefits, the Company has analyzed its tax return filing positions in all of the federal, state and foreign filing jurisdictions where it is required to file income tax returns, as well as all open years in those jurisdictions.

Employee Benefit Plan

Employee Benefit Plan	12 Months Ended
	Dec. 31, 2022
Retirement Benefits [Abstract]
Employee Benefit Plan	Employee Benefit PlanThe Company sponsors a 401(k) Plan. Employees become eligible for participation upon the start of employment. Participants may elect to have a portion of their salary deferred and contributed to the 401(k) Plan up to the limit allowed under the Internal Revenue Code. The Company makes a matching contribution to the plan for each participant who has elected to make tax-deferred contributions for the plan year. The Company made matching contributions which amounted to approximately $129,000 and $75,000 for the years ended December 31, 2022 and 2021, respectively. These amounts were charged to the consolidated statements of operations. The employer contributions vest immediately.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2022
Subsequent Events [Abstract]
Subsequent Events	Subsequent EventsThe Company evaluated all events or transactions that occurred after December 31, 2022 up through the date these consolidated financial statements were issued. Other than as disclosed elsewhere in the notes to the consolidated financial statements, the Company did not have any material subsequent events.

Basis of Presentation and Sig_2

Basis of Presentation and Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2022
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States (“U.S. GAAP”). Any reference in these notes to applicable guidance is meant to refer to U.S. GAAP as found in the Accounting Standards Codification ("ASC") and Accounting Standards Updates (“ASU”) of the Financial Accounting Standards Board (“FASB”).
Principles of Consolidation	Principles of Consolidation The consolidated financial statements include the financial statements of the Company and its wholly owned subsidiaries. All significant intercompany accounts and transactions have been eliminated upon consolidation. Unless the context otherwise indicates, reference in these notes to the "Company" refer to SELLAS Life Sciences Group, Inc., and its wholly owned subsidiaries, Private SELLAS, SLSG Limited, LLC, Sellas Life Sciences Limited, and Apthera, Inc. The functional currency of the Company's non-U.S. operations is the U.S. dollar.
Use of Estimates	Use of Estimates The preparation of these consolidated financial statements in accordance with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. On an ongoing basis, the Company evaluates its estimates using historical experience and other factors, including the current economic environment. Significant items subject to such estimates are assumptions used for purposes of determining stock-based compensation, carrying value of goodwill, accounting for deferred income taxes, and accounting for research and development activities. Management believes its estimates to be reasonable under the circumstances. Actual results could differ significantly from those estimates.
Segment Information	Segment InformationOperating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The Company measures certain financial assets and liabilities at fair value on a recurring basis. Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or a liability. A three-tier fair value hierarchy is established as a basis for considering such assumptions and for inputs used in the valuation methodologies in measuring fair value: Level 1—Quoted prices in active markets for identical assets or liabilities. Level 2—Inputs other than quoted prices included within Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. As of December 31, 2022 and 2021, the carrying amounts of the Company’s financial instruments, including cash equivalents and accounts payable, approximate fair value due to the short-term nature of those instruments and were categorized as Level 1. As of December 31, 2022 and 2021, the carrying amounts of the Company’s contingent consideration and liability-classified warrants are each recorded at their estimated fair value.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments that potentially expose the Company to concentrations of credit risk consist principally of cash on deposit with financial institutions, the balances of which frequently exceed federally insured limits. On March 10, 2023, Silicon Valley Bank ("SVB") was closed by the California Department of Financial Protection and Innovation, which appointed the Federal Deposit Insurance Corporation ("FDIC") as receiver. If any of the financial institutions with whom we do business were to be placed into receivership, we may be unable to access to the cash we have on deposit with such institutions.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers any highly liquid investments, such as money market funds, with an original maturity of three months or less to be cash and cash equivalents.
Restricted Cash and Cash Equivalents	Restricted Cash and Cash Equivalents Restricted cash consists of certificates of deposit on hand with the Company’s financial institutions as collateral for its corporate credit cards.
Goodwill	GoodwillGoodwill is the excess of the cost of an acquired entity over the net amounts assigned to tangible and intangible assets acquired and liabilities assumed. Goodwill is not amortized but is subject to an annual impairment test. The Company has a single reporting unit and all goodwill relates to that reporting unit. The Company performs its annual goodwill impairment test in the fourth quarter of each fiscal year or more frequently if changes in circumstances or the occurrence of events suggest that an impairment exists.
Contingent Consideration	Contingent Consideration The consideration for Galena's acquisition of Apthera, Inc. in 2011 includes future payments that are contingent upon the achievement of certain events related to the development and commercialization of nelipepimut-S ("NPS"). Contingent consideration, and the obligations for such contingent consideration payments, is required to be recognized at fair value as of the acquisition date. The contingent consideration obligations are then evaluated each reporting period and changes in the fair value of contingent consideration, other than changes due to payments, are recognized as a gain or loss and recorded within the change in the fair value of contingent consideration in the Company's consolidated statements of operations. The fair value of development and regulatory milestones are estimated utilizing a probability adjusted, discounted cash flow approach. The fair value of net sales milestones is based on probability adjusted sales estimates and estimated discount rates and utilizes an option pricing model with Monte Carlo simulation to simulate a range of possible payment scenarios, and the average of the payments in these scenarios is then discounted to calculate present fair value.
Leases	Leases The Company accounts for its leasing arrangements under ASU No. 2016-02, Leases (Topic 842) (“Topic 842”). Under Topic 842, all significant lease arrangements are generally recognized at lease commencement. Operating lease right-of-use ("ROU"), assets and lease liabilities are recognized at the commencement date. An ROU asset and corresponding lease liability is not recorded for leases with an initial term of 12 months or less (short term leases) and the Company recognizes lease expense for these leases as incurred over the lease term.
Revenue Recognition	Revenue Recognition The Company records revenue in accordance with ASC Topic 606, Revenue From Contracts with Customers ("Topic 606"). This standard applies to all contracts with customers, except for contracts that are within the scope of other standards, such as leases, insurance, collaboration arrangements and financial instruments. Under Topic 606, an entity recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration that the entity expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that an entity determines are within the scope of Topic 606, the entity 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 entity satisfies a performance obligation. The Company only applies the five step model to contracts when it is probable that the entity will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, once the contract is determined to be within the scope of Topic 606, the Company assesses the goods or services promised within each contract and determines those that are performance obligations, and assesses whether each promised good or service is distinct. The Company then allocates the transaction price to each distinct performance obligation based on its relative standalone selling price. The Company recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied. See Note 11 for further discussion of the Company's revenue recognition associated with the 3DMed License Agreement. Development, Regulatory and Sales Milestones and Other Payments At the inception of each arrangement that includes regulatory or development milestone payments, the Company evaluates whether the milestones are considered probable of being achieved and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the control of the Company or the licensee, such as regulatory approvals, are not considered probable of being achieved until those approvals are received. The Company evaluates factors such as the scientific, clinical, regulatory, commercial, and other risks that must be overcome to achieve the particular milestone in making this assessment. There is considerable judgment involved in determining whether it is probable that a significant revenue reversal would not occur. At the end of each subsequent reporting period, the Company reevaluates the probability of achievement of all milestones subject to constraint and, if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect revenues and earnings in the period of adjustment. For arrangements that include sales-based royalties, including milestone payments upon first commercial sales and milestone payments based on a level of sales, which are the result of a customer-vendor relationship and for which the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied or partially satisfied. To date, the Company has not recognized any royalty revenue resulting from any of its licensing arrangements.
Acquired In-Process Research and Development	Acquired In-Process Research and Development Costs incurred in obtaining technology licenses are immediately recognized as acquired in-process research and development expense, provided the technology licensed has no alternative future use as the technology and know-how acquired are not currently commercially viable. Payments related to contingent consideration such as development milestones, commercial milestones and royalties (Note 8) will be recognized when the contingency is probable and reasonably estimable in accordance with ASC 450, Contingencies .
Research and Development Expenses	Research and Development Expenses Research and development costs are expensed as incurred. Research and development costs that are paid in advance of performance are capitalized as a prepaid expense and recognized as research and development expenses as the services are provided. Clinical study costs, a component of research and development expenses, are accrued over the service periods specified in the contracts and adjusted as necessary based on an ongoing review of the level of effort and costs actually incurred. Research and development expenses consist primarily of development research performed by contract research organizations ("CROs"), personnel costs, including salaries, benefits and stock-based compensation, clinical drug supply, investigator grants, materials and supplies, consulting fees, licenses and fees, preclinical studies, and overhead allocations consisting of various support and facility-related costs.
Stock-based Compensation	Stock-based Compensation The Company measures employee and non-employee director share-based awards at their grant-date fair value and records compensation expense on a straight-line basis over the vesting period of the awards. Estimating the fair value of share-based awards requires the input of subjective assumptions, including the expected life of the options and stock price volatility. The Company accounts for forfeitures for stock option awards as they occur. The Company uses the Black-Scholes option pricing model to value its stock option awards. The assumptions used in estimating the fair value of share-based awards represent management’s estimate and involve inherent uncertainties and the application of management’s judgment. As a result, if factors change and management uses different assumptions, share-based compensation expense could be materially different for future awards. The expected life of the stock options is estimated using the “simplified method,” as the Company has limited historical information from which to develop reasonable expectations about future exercise patterns and post-vesting employment termination behavior for its stock option grants. The simplified method is the midpoint between the vesting period and the contractual term of the option. The stock price volatility assumption is based on the historical volatility of the Company's publicly traded common stock. The risk-free rate is based on the U.S. Treasury yield curve commensurate with the expected life of the option. Restricted Stock Units with Performance and Service Conditions The Company's Board of Directors has granted restricted stock units ("RSUs") to certain employees that vest based on performance and service conditions. The fair values of the performance-based RSUs are measured on the date of grant and are based on the Company's closing stock price on such date. Compensation expense is recognized for the number of performance-based RSUs expected to be earned, provided the requisite service period has been rendered, after assessing the probability that certain performance criteria will be met. Cumulative adjustments are recorded each quarter to reflect the estimated outcome of the performance-related conditions until the date results are determined and settled. The Company accounts for forfeitures of performance-based RSUs when they occur. If performance criteria are not met or are not expected to be met, any compensation expense previously recognized to date associated with the performance-based RSUs will be reversed. Restricted Stock Units with Service Conditions Only
Income Taxes	Income Taxes The Company uses the asset and liability method of accounting for income taxes. Deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and operating loss and credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. A valuation allowance is provided when it is more likely than not that some portion or all of a deferred tax asset will not be realized. The Company recognizes the benefit of an uncertain tax position that it has taken or expects to take on its income tax returns, if such a position is more likely than not to be sustained. Potential interest and penalties associated with unrecognized tax positions are recognized in income tax expense. No interest or penalties were recognized in either of the years ended December 31, 2022 or 2021. The Company recognizes liabilities or assets for the deferred tax consequences of temporary differences between the tax basis of assets or liabilities and their reported amounts in the consolidated financial statements in accordance with FASB ASC 740-10, “ Accounting for Income Taxes” (“ASC 740-10”). These temporary differences will result in taxable or deductible amounts in future years when the reported amounts of the assets or liabilities are recovered or settled. ASC 740-10 requires that a valuation allowance be established when management determines that it is more likely than not that all or a portion of a deferred asset will not be realized. The Company evaluates the realizability of its net deferred income tax assets and valuation allowances as necessary, at least on an annual basis. During this evaluation, the Company reviews its forecasts of income in conjunction with other positive and negative evidence surrounding the realizability of its deferred income tax assets to determine if a valuation allowance is required. Adjustments to the valuation allowance will increase or decrease the Company’s income tax provision or benefit. The recognition and measurement of benefits related to the Company’s tax positions requires significant judgment, as uncertainties often exist with respect to new laws, new interpretations of existing laws, and rulings by taxing authorities. Differences between actual results and the Company’s assumptions or changes in the Company’s assumptions in future periods are recorded in the period they become known.
Net Loss Per Share	Net Loss Per Share Basic loss per share is computed by dividing net loss applicable to common stockholders by the weighted average number of shares of common stock outstanding during each period. Diluted loss per share includes the effect, if any, from the potential exercise or conversion of securities, such as warrants, stock options and unvested restricted stock that would result in the issuance of incremental shares of common stock. In computing the basic and diluted net loss per share, the weighted average number of shares remains the same for both calculations due to the fact that when a net loss exists, dilutive shares are not included in the calculation as the impact is anti-dilutive.
Recent Accounting Pronouncements Adopted and Recent Accounting Standards Not Yet Adopted	Recent Accounting Pronouncements Adopted In May 2021, the FASB issued ASU No. 2021-04, Issuer’s Accounting for Certain Modifications of Exchanges of Freestanding Equity-Classified Written Call Options, to clarify the accounting for modifications or exchanges of freestanding equity-classified written call options, such as warrants, that remain equity classified after modification or exchange. This ASU became effective for the Company on January 1, 2022 and did not have a material impact on the Company's consolidated financial statements. Recent Accounting Standards Not Yet Adopted In August 2020, the FASB issued ASU No. 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity, which, among other things, simplifies the accounting models for the allocation of proceeds attributable to the issuance of a convertible debt instrument. As a result, after adopting the ASU’s guidance, entities will not separately present in equity an embedded conversion feature in such debt. Instead, they will account for a convertible debt instrument wholly as debt, and for convertible preferred stock wholly as preferred stock (i.e., as a single unit of account), unless (i) a convertible instrument contains features that require bifurcation as a derivative under ASC 815 or (ii) a convertible debt instrument was issued at a substantial premium. The standard becomes effective for the Company in the first quarter of 2024 and

Basis of Presentation and Sig_3

Basis of Presentation and Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2022
Accounting Policies [Abstract]
Schedule of Cash and Cash Equivalents	The following table provides a reconciliation of the components of cash, cash equivalents, restricted cash, and restricted cash equivalents reported in the Company's consolidated balance sheets to the total amount presented in the consolidated statements of cash flows (in thousands): December 31, 2022 2021 Cash and cash equivalents $ 17,125 $ 21,355 Restricted cash and cash equivalents 100 100 Total cash, cash equivalents, restricted cash, and restricted cash equivalents $ 17,225 $ 21,455
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	The following potentially dilutive securities outstanding have been excluded from the computation of diluted weighted average shares outstanding, as their impact would be anti-dilutive (in thousands): December 31, 2022 2021 Common stock warrants 5,141 519 Stock options 1,040 534 Restricted stock units 255 200 6,436 1,253

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2022
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Intangible Assets and Goodwill	A reconciliation of the change in goodwill and intangible assets for the years ended December 31, 2022 and 2021 is as follows (in thousands): In-Process Research and Development Goodwill December 31, 2020 $ 5,700 $ 1,914 Impairment charge (5,700) — December 31, 2021 — 1,914 Impairment charge — — December 31, 2022 $ — $ 1,914

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2022
Fair Value Disclosures [Abstract]
Assets and Liabilities Measured at Fair Value	The following tables present information about the Company's assets and liabilities measured at fair value on a recurring basis in the consolidated balance sheets (in thousands): Description December 31, 2022 Quoted Prices In Significant Other Unobservable Assets: Cash equivalents $ 16,609 $ 16,609 $ — $ — Restricted cash equivalents 100 100 — — Total assets measured and recorded at fair value $ 16,709 $ 16,709 $ — $ — Liabilities: Warrants potentially settleable in cash $ 4 $ — $ — $ 4 Contingent consideration — — — — Total liabilities measured and recorded at fair value $ 4 $ — $ — $ 4 Description December 31, 2021 Quoted Prices In Significant Other Unobservable Assets: Cash equivalents $ 21,000 $ 21,000 $ — $ — Restricted cash equivalents 100 100 — — Total assets measured and recorded at fair value $ 21,100 $ 21,100 $ — $ — Liabilities: Warrants potentially settleable in cash $ 40 $ — $ — $ 40 Contingent consideration 296 — — 296 Total liabilities measured and recorded at fair value $ 336 $ — $ — $ 336
Reconciliation of Level 3 Liabilities	A reconciliation of the change in the fair value of the contingent consideration liability for the year ended December 31, 2022 and 2021 is as follows (in thousands): Fair Value Contingent consideration, December 31, 2020 $ 4,633 Change in the estimated fair value of the contingent consideration (4,337) Contingent consideration, December 31, 2021 296 Change in the estimated fair value of the contingent consideration (296) Contingent consideration, December 31, 2022 $ —
Schedule of Fair Value Measurement Inputs and Valuation Techniques	The following significant unobservable inputs were used in the valuation of the contingent consideration liability: Unobservable input As of December 31, 2022 As of December 31, 2021 Potential milestone payments $0 - $30 million $0 - $30 million Discount rate n/a 15.5 % Cumulative probability of success — % 5.3 % Projected years of payments n/a 2028 - 2031

Balance Sheet Accounts (Tables)

Balance Sheet Accounts (Tables)	12 Months Ended
	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Prepaid Expenses and Other Current Assets	Prepaid expenses and other current assets consist of the following (in thousands): December 31, 2022 2021 Clinical trial costs $ 184 $ 1,309 Insurance 219 217 Professional fees 82 36 Other 46 27 Prepaid expenses and other current assets $ 531 $ 1,589
Schedule of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consist of the following (in thousands): December 31, 2022 2021 Clinical trial costs $ 4,509 $ 1,325 Compensation and related benefits 1,439 989 Professional fees 338 165 Other — 161 Accrued expenses and other current liabilities $ 6,286 $ 2,640

Legal Proceedings, Commitment_2

Legal Proceedings, Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Lease Payments	Future minimum rental payments under the Company's non-cancelable operating lease are as follows as of December 31, 2022 (in thousands): Total minimum lease payments: 2023 $ 518 2024 533 Total future minimum lease payments 1,051 Less: imputed interest (106) Operating lease liabilities $ 945

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2022
Equity [Abstract]
Schedule of Common Stock Reserved for Future Issuance	Shares of common stock reserved for future issuance are as follows (in thousands): December 31, 2022 Warrants outstanding 5,141 Stock options outstanding 1,040 Restricted stock units outstanding 255 Options reserved for future issuance under the Company’s 2019 Equity Incentive Plan 641 Shares reserved for future issuance under the Employee Stock Purchase Plans 275 Total shares of common stock reserved for future issuance 7,352

Warrants to Acquire Shares of_2

Warrants to Acquire Shares of Common Stock (Tables)	12 Months Ended
	Dec. 31, 2022
Warrants and Rights Note Disclosure [Abstract]
Schedule of Warrant Activity	The following is a summary of the Company's warrants to acquire shares of common stock activity for the year ended December 31, 2022 (in thousands, except per share data): Warrant Issuance Outstanding, December 31, 2021 Granted Canceled/Expired Outstanding, December 31, 2022 Exercise Price Per Share Expiration Warrants classified as equity: April 2022 Offering — 4,630 — 4,630 $ 5.40 April 2027 January 2020 Offering 309 — — 309 $ 3.93 July 2025 July 2020 PIPE Offering 25 — — 25 $ 3.30 August 2025 July 2018 Offering 132 — — 132 $ 7.50 July 2023 March 2019 Exercise Agreement 30 — — 30 $ 7.50 March 2024 Other 9 — (7) 2 $ 7.50 June 2024 505 4,630 (7) 5,128 Warrants classified as liability: 14 — (1) 13 $ 7.50 September 2023 - November 2023 519 4,630 (8) 5,141
Schedule of Fair Value of Warrants is Estimated Using Black-Scholes Option Pricing Model	The fair value of the warrants accounted for as liabilities is estimated using a Black-Scholes pricing model with the following inputs: As of December 31, 2022 2021 Risk free interest rate 4.75 % 0.65 % Volatility 120.60% 131.04% Expected term (years) 0.75 1.75 Expected dividend yield — % — % Strike price $ 7.50 $ 7.50
Schedule of Changes in Fair Value of Warrant Liability	The changes in fair value of the warrant liability for the year ended December 31, 2022 and 2021 were as follows (in thousands): Warrant Liability Warrant liability, December 31, 2020 $ 55 Change in fair value of warrants (15) Warrant liability, December 31, 2021 40 Change in fair value of warrants (36) Warrant liability, December 31, 2022 $ 4

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2022
Share-Based Payment Arrangement [Abstract]
Schedule of Allocated Stock-based Compensation Expense	The following table summarizes the components of stock-based compensation expense in the consolidated statements of operations for the years ended December 31, 2022 and 2021, respectively (in thousands): Years Ended December 31, 2022 2021 Research and development $ 270 $ 126 General and administrative 1,456 885 Total stock-based compensation $ 1,726 $ 1,011
Schedule of Assumptions for Option Grants Issued	The Company uses the Black-Scholes option-pricing model to estimate the fair value of stock-based awards and the following assumptions were used for stock options granted during the years ended December 31, 2022 and 2021, respectively: Years Ended December 31, 2022 2021 Risk free interest rate 1.96 % 1.05 % Volatility 131.51 % 121.53 % Expected lives (years) 6.18 6.18 Expected dividend yield — % — %
Schedule of Stock Option Activity	The following table summarizes stock option activity of the Company for the years ended December 31, 2022 and 2021, respectively: Total Weighted Weighted Average Remaining Contractual Term (in years) Aggregate Outstanding at January 1, 2021 208 $ 13.38 Granted 326 8.00 Outstanding at December 31, 2021 534 10.09 Granted 546 5.01 Canceled (40) 6.17 Outstanding at December 31, 2022 1,040 $ 7.57 8.48 $ 91 Vested and exercisable at December 31, 2022 313 $ 12.38 7.63 $ 66
Schedule of RSU Activity	The following table summarizes RSU activity of the Company for the years ended December 31, 2022 and 2021, respectively: Total Number of Shares Weighted Average Grant Date Fair Value Per Share Unvested at January 1, 2021 170 $ 1.89 Granted 40 $ 8.00 Vested (10) $ 8.00 Unvested at December 31, 2021 200 $ 2.81 Granted 97 $ 5.34 Vested (40) $ 6.01 Canceled (2) $ 5.34 Unvested at December 31, 2022 255 $ 3.25

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Schedule of Components of Income Tax Expense (Benefit)	The Company's loss before income taxes is as follows (in thousands): As of December 31, 2022 2021 U.S. $ (17,825) $ (6,956) Non - U.S. (23,476) (13,980) $ (41,301) $ (20,936)
Schedule of Components of Income Tax Expense (Benefit)	The components of federal and state income tax benefit are as follows (in thousands): As of December 31, 2022 2021 Current Federal $ — $ — State — 2 Foreign — — Total current — 2 Deferred expense Federal — (239) State — — Foreign — — Total deferred — (239) Total income tax benefit $ — $ (237)
Schedule of Deferred Tax Assets and Liabilities	The components of net deferred tax assets are as follows (in thousands): As of December 31, 2022 2021 Net operating loss carryforwards $ 10,529 $ 9,059 Stock-based compensation 229 140 Licensing deduction deferral 4,503 3,236 Contingent consideration — 62 Lease liability 198 170 Capitalized Section 174 research and development 765 — Other 282 217 Gross deferred tax assets 16,506 12,884 Valuation allowance (16,322) (12,732) Net deferred tax assets $ 184 $ 152 The components of gross deferred tax liabilities are as follows (in thousands): As of December 31, 2022 2021 Right of use asset $ 184 $ 152 Gross deferred tax liability $ 184 $ 152 The net deferred tax liabilities are as follows (in thousands): As of December 31, 2022 2021 Net deferred tax asset $ 184 $ 152 Gross deferred tax liability (184) (152) Net deferred tax liability $ — $ —
Schedule of Effective Income Tax Rate Reconciliation	The provision for income taxes differs from the provision computed by applying the federal statutory rate to net loss before income taxes as follows: As of December 31, 2022 2021 U.S. federal statutory income tax rate (21.0) % (21.0) % State and local taxes, net of federal benefit (0.1) % (0.2) % Foreign rate differential 11.9 % 14.0 % Valuation allowance 8.7 % 5.8 % Permanent differences 0.2 % 0.2 % Other 0.3 % 0.1 % Effective income tax rate — % (1.1) %

Liquidity and Going Concern (De

Liquidity and Going Concern (Details) - USD ($)					1 Months Ended	3 Months Ended	12 Months Ended
	Feb. 28, 2023	Dec. 31, 2022	Apr. 05, 2022	Apr. 16, 2021	May 31, 2022	Mar. 16, 2023	Dec. 31, 2022	Dec. 31, 2021
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Accumulated deficit		$ 179,904,000					$ 179,904,000	$ 138,603,000
Net loss							41,301,000	20,699,000
Cash used in operating activities							23,809,000	26,021,000
Cash and cash equivalents		$ 17,125,000					17,125,000	21,355,000
Milestone payment received					$ 1,000,000		$ 13,000,000
Shares of common stock reserved for issuance (in shares)		7,352,000					7,352,000
Upfront fee and milestone payments							$ 10,500,000
Potential milestone payments to be received		$ 191,500,000					$ 191,500,000	$ 192,500,000
Underwriting Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of shares of stock (in shares)			4,629,630
Common stock to be called by warrants (in shares)			4,629,630
Offering (in dollars per share)			$ 5.40
Common stock warrant, shares to purchase			1
Warrant exercise price (in dollars per share)			$ 5.40
Warrant term			5 years
Net proceeds of common stock			$ 23,000,000
Underwriting Agreement | Subsequent Event
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of shares of stock (in shares)	7,220,217
Common stock to be called by warrants (in shares)	7,220,217
Offering (in dollars per share)	$ 2.77
Common stock warrant, shares to purchase	1
Warrant exercise price (in dollars per share)	$ 2.77
Warrant term	5 years
Net proceeds of common stock	$ 18,500,000
Sales Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of shares of stock (in shares)							415,005
Net proceeds of common stock							$ 1,000,000
Sale of stock, authorized amount				$ 50,000,000
Sale of stock, agent fee, percentage of gross proceeds				3%
Sale of stock, price per share (in dollars per share)		$ 2.60					$ 2.60
Shares of common stock reserved for issuance (in shares)		39,200,000					39,200,000
Sales Agreement | Subsequent Event
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of shares of stock (in shares)						76,882
Net proceeds of common stock						$ 300,000
Sale of stock, price per share (in dollars per share)						$ 3.59

Basis of Presentation and Sig_4

Basis of Presentation and Significant Accounting Policies - Narrative (Details)	12 Months Ended
	Dec. 31, 2022 USD ($) segment	Dec. 31, 2021 USD ($)
Finite-Lived Intangible Assets [Line Items]
Number of segment | segment	1
Restricted cash and cash equivalents	$ 100,000	$ 100,000
In-process research and development impairment charge	0	5,700,000
Goodwill impairment	$ 0	0
Fair Value, Recurring Basis, Unobservable Input Reconciliation, Liability, Gain (Loss),Statement Of Other Comprehensive Income, Extensible List, Not Disclosed Flag	consolidated statements of operations
Interest or penalties	$ 0	0
Restricted stock units
Finite-Lived Intangible Assets [Line Items]
Vesting percentage	25%
Award vesting period	4 years
Corporate Credit Cards
Finite-Lived Intangible Assets [Line Items]
Restricted cash and cash equivalents	$ 100,000	$ 100,000

Basis of Presentation and Sig_5

Basis of Presentation and Significant Accounting Policies - Components of Cash (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Accounting Policies [Abstract]
Cash and cash equivalents	$ 17,125	$ 21,355
Restricted cash and cash equivalents	100	100
Total cash, cash equivalents, restricted cash, and restricted cash equivalents	$ 17,225	$ 21,455	$ 35,402

Basis of Presentation and Sig_6

Basis of Presentation and Significant Accounting Policies - Earnings Per Share (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	6,436	1,253
Common stock warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	5,141	519
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	1,040	534
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	255	200

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	$ 1,914,000	$ 1,914,000	$ 1,914,000
Accumulated impairment loss related to goodwill	0	0
In-process research and development impairment charge	$ 0	5,700,000
Indefinite-lived intangible assets (excluding goodwill), fair value disclosure		$ 0

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets - Reconciliation Of Change In Intangible Assets (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Indefinite-lived Intangible Assets [Roll Forward]
In-process research and development Beginning Balance	$ 0	$ 5,700,000
Impairment charge	0	(5,700,000)
In-process research and development Ending Balance	0	0
Goodwill [Roll Forward]
Goodwill, Beginning Balance	1,914,000	1,914,000
Impairment charge	0	0
Goodwill, Ending Balance	$ 1,914,000	$ 1,914,000

Collaboration and In-License _2

Collaboration and In-License Agreements (Details) - USD ($)				1 Months Ended	12 Months Ended
	Mar. 31, 2022	Sep. 04, 2014	Sep. 11, 2006	Apr. 30, 2022	Dec. 31, 2022	Dec. 31, 2021
License And Collaboration Agreements [Line Items]
Cash paid for acquisition of in-process research and development					$ 4,500,000	$ 0
Acquired in-process research and development					10,000,000	0
Cost of licensing revenue					100,000	200,000
GenFleet Therapeutics (Shanghai) Inc
License And Collaboration Agreements [Line Items]
Upfront fee	$ 10,000,000
Cash paid for acquisition of in-process research and development				$ 4,500,000
Acquired in-process research and development payable, non-current	5,500,000				5,500,000
Eligible payment from collaboration for development and regulatory milestone achievement under collaborations agreement	48,000,000
Acquired in-process research and development					10,000,000
Collaborative Arrangement, Maximum Aggregate Sales Milestone Payments	$ 92,000,000
The University of Texas M. D. Anderson Cancer Center and The Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc.
License And Collaboration Agreements [Line Items]
Annual maintenance fee			$ 200,000
Milestone payments			$ 3,800,000
Memorial Sloan Kettering Cancer Center
License And Collaboration Agreements [Line Items]
License agreement expiration term		10 years
Minimum annual royalty payment					$ 100,000	$ 100,000

Fair Value Measurements - Conti

Fair Value Measurements - Contingent Purchase Price Consideration, Measured at Estimated Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Liabilities:
Warrants potentially settleable in cash	$ 4	$ 40
Fair Value, Measurements, Recurring
Assets:
Cash equivalents	16,609	21,000
Restricted cash equivalents	100	100
Total assets measured and recorded at fair value	16,709	21,100
Liabilities:
Warrants potentially settleable in cash	4	40
Contingent consideration	0	296
Total liabilities measured and recorded at fair value	4	336
Fair Value, Measurements, Recurring | Quoted Prices In  Active Markets (Level 1)
Assets:
Cash equivalents	16,609	21,000
Restricted cash equivalents	100	100
Total assets measured and recorded at fair value	16,709	21,100
Liabilities:
Warrants potentially settleable in cash	0	0
Contingent consideration	0	0
Total liabilities measured and recorded at fair value	0	0
Fair Value, Measurements, Recurring | Significant Other Observable  Inputs (Level 2)
Assets:
Cash equivalents	0	0
Restricted cash equivalents	0	0
Total assets measured and recorded at fair value	0	0
Liabilities:
Warrants potentially settleable in cash	0	0
Contingent consideration	0	0
Total liabilities measured and recorded at fair value	0	0
Fair Value, Measurements, Recurring | Unobservable  Inputs (Level 3)
Assets:
Cash equivalents	0	0
Restricted cash equivalents	0	0
Total assets measured and recorded at fair value	0	0
Liabilities:
Warrants potentially settleable in cash	4	40
Contingent consideration	0	296
Total liabilities measured and recorded at fair value	$ 4	$ 336

Fair Value Measurements - Recon

Fair Value Measurements - Reconciliation of Level 3 Liabilities (Details) - Unobservable  Inputs (Level 3) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Contingent consideration, beginning balance	$ 296	$ 4,633
Change in the estimated fair value of the contingent consideration	(296)	(4,337)
Contingent consideration, ending balance	$ 0	$ 296

Fair Value Measurements - Signi

Fair Value Measurements - Significant Unobservable Inputs (Details) - Apthera	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration payable, minimum amount	$ 0	$ 0
Contingent consideration payable, maximum amount	$ 30,000,000	$ 30,000,000
Discount rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Business combination, contingent consideration, measurement input (as a percent)		0.155
Cumulative probability of success
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Business combination, contingent consideration, measurement input (as a percent)	0	0.053

Balance Sheet Accounts - Prepai

Balance Sheet Accounts - Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Clinical trial costs	$ 184	$ 1,309
Insurance	219	217
Professional fees	82	36
Other	46	27
Prepaid expenses and other current assets	$ 531	$ 1,589

Balance Sheet Accounts - Accrue

Balance Sheet Accounts - Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Clinical trial costs	$ 4,509	$ 1,325
Compensation and related benefits	1,439	989
Professional fees	338	165
Other	0	161
Accrued expenses and other current liabilities	$ 6,286	$ 2,640

Legal Proceedings, Commitment_3

Legal Proceedings, Commitments and Contingencies - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Operating lease, discount rate (as a percent)	13.95%
Operating lease, remaining term	2 years
Rent expense	$ 0.5	$ 0.3
Cash payments related to operating lease	$ 0.5	$ 0.3

Legal Proceedings, Commitment_4

Legal Proceedings, Commitments and Contingencies - Future Minimum Rental Payments for Operating Leases (Details) $ in Thousands	Dec. 31, 2022 USD ($)
Commitments and Contingencies Disclosure [Abstract]
2023	$ 518
2024	533
Total future minimum lease payments	1,051
Less: imputed interest	(106)
Operating lease liabilities	$ 945

Stockholders' Equity - Narrativ

Stockholders' Equity - Narrative (Details) - USD ($)				3 Months Ended	12 Months Ended
	Feb. 28, 2023	Apr. 05, 2022	Apr. 16, 2021	Mar. 16, 2023	Dec. 31, 2022	Dec. 31, 2021
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)					5,000,000	5,000,000
Preferred stock, par value (in dollars per share)					$ 0.0001	$ 0.0001
Preferred stock, shares outstanding (in shares)					0	0
Common stock, shares authorized (in shares)					350,000,000	350,000,000
Common stock, par value (in dollars per share)					$ 0.0001	$ 0.0001
Shares of common stock reserved for issuance (in shares)					7,352,000
Underwriting Agreement
Class of Stock [Line Items]
Number of shares of stock (in shares)		4,629,630
Common stock to be called by warrants (in shares)		4,629,630
Offering (in dollars per share)		$ 5.40
Common stock warrant, shares to purchase		1
Warrant exercise price (in dollars per share)		$ 5.40
Warrant term		5 years
Net proceeds of common stock		$ 23,000,000
Underwriting Agreement | Subsequent Event
Class of Stock [Line Items]
Number of shares of stock (in shares)	7,220,217
Common stock to be called by warrants (in shares)	7,220,217
Offering (in dollars per share)	$ 2.77
Common stock warrant, shares to purchase	1
Warrant exercise price (in dollars per share)	$ 2.77
Warrant term	5 years
Net proceeds of common stock	$ 18,500,000
Sales Agreement
Class of Stock [Line Items]
Number of shares of stock (in shares)					415,005
Net proceeds of common stock					$ 1,000,000
Sale of stock, authorized amount			$ 50,000,000
Sale of stock, agent fee, percentage of gross proceeds			3%
Sale of stock, price per share (in dollars per share)					$ 2.60
Shares of common stock reserved for issuance (in shares)					39,200,000
Sales Agreement | Subsequent Event
Class of Stock [Line Items]
Number of shares of stock (in shares)				76,882
Net proceeds of common stock				$ 300,000
Sale of stock, price per share (in dollars per share)				$ 3.59

Stockholders' Equity - Common S

Stockholders' Equity - Common Stock are Reserved for Future Issuance (Details) - shares shares in Thousands	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants outstanding (in shares)	5,141	519
Stock options outstanding (in shares)	1,040	534	208
Total shares of common stock reserved for future issuance (in shares)	7,352
2019 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for future issuance (in shares)	641
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for future issuance (in shares)	275
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units outstanding (in shares)	255	200	170

Warrants to Acquire Shares of_3

Warrants to Acquire Shares of Common Stock - Warrants Outstanding (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2022 $ / shares shares
Class of Warrant or Right, Outstanding [Roll Forward]
Outstanding, beginning of period (in shares)	519
Granted (in shares)	4,630
Canceled/Expired (in shares)	(8)
Outstanding, end of period (in shares)	5,141
Common stock warrants
Class of Warrant or Right, Outstanding [Roll Forward]
Outstanding, beginning of period (in shares)	505
Granted (in shares)	4,630
Canceled/Expired (in shares)	(7)
Outstanding, end of period (in shares)	5,128
April 2022 Offering | Common stock warrants
Class of Warrant or Right, Outstanding [Roll Forward]
Outstanding, beginning of period (in shares)	0
Granted (in shares)	4,630
Canceled/Expired (in shares)	0
Outstanding, end of period (in shares)	4,630
Exercise price (in dollars per share) | $ / shares	$ 5.40
January 2020 Offering | Common stock warrants
Class of Warrant or Right, Outstanding [Roll Forward]
Outstanding, beginning of period (in shares)	309
Granted (in shares)	0
Canceled/Expired (in shares)	0
Outstanding, end of period (in shares)	309
Exercise price (in dollars per share) | $ / shares	$ 3.93
July 2020 PIPE Offering | Common stock warrants
Class of Warrant or Right, Outstanding [Roll Forward]
Outstanding, beginning of period (in shares)	25
Granted (in shares)	0
Canceled/Expired (in shares)	0
Outstanding, end of period (in shares)	25
Exercise price (in dollars per share) | $ / shares	$ 3.30
July 2018 Offering | Common stock warrants
Class of Warrant or Right, Outstanding [Roll Forward]
Outstanding, beginning of period (in shares)	132
Granted (in shares)	0
Canceled/Expired (in shares)	0
Outstanding, end of period (in shares)	132
Exercise price (in dollars per share) | $ / shares	$ 7.50
March 2019 Exercise Agreement | Common stock warrants
Class of Warrant or Right, Outstanding [Roll Forward]
Outstanding, beginning of period (in shares)	30
Granted (in shares)	0
Canceled/Expired (in shares)	0
Outstanding, end of period (in shares)	30
Exercise price (in dollars per share) | $ / shares	$ 7.50
Other | Common stock warrants
Class of Warrant or Right, Outstanding [Roll Forward]
Outstanding, beginning of period (in shares)	9
Granted (in shares)	0
Canceled/Expired (in shares)	(7)
Outstanding, end of period (in shares)	2
Exercise price (in dollars per share) | $ / shares	$ 7.50
Warrants classified as liability:
Class of Warrant or Right, Outstanding [Roll Forward]
Outstanding, beginning of period (in shares)	14
Granted (in shares)	0
Canceled/Expired (in shares)	(1)
Outstanding, end of period (in shares)	13
Exercise price (in dollars per share) | $ / shares	$ 7.50

Warrants to Acquire Shares of_4

Warrants to Acquire Shares of Common Stock - Narrative (Details) - Underwriting Agreement - $ / shares	Feb. 28, 2023	Apr. 05, 2022
Class of Warrant or Right [Line Items]
Common stock to be called by warrants (in shares)		4,629,630
Warrant exercise price (in dollars per share)		$ 5.40
Subsequent Event
Class of Warrant or Right [Line Items]
Common stock to be called by warrants (in shares)	7,220,217
Warrant exercise price (in dollars per share)	$ 2.77
April 2022 Offering | Subsequent Event
Class of Warrant or Right [Line Items]
Common stock to be called by warrants (in shares)	3,438,851
Warrant exercise price (in dollars per share)	$ 3.62

Warrants to Acquire Shares of_5

Warrants to Acquire Shares of Common Stock - Fair Value of Warrants is Estimated Using Black-Scholes Option Pricing Model (Details)	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Risk free interest rate
Class of Warrant or Right [Line Items]
Warrants, measurement input	0.0475	0.0065
Volatility
Class of Warrant or Right [Line Items]
Warrants, measurement input	1.2060	1.3104
Expected term (years)
Class of Warrant or Right [Line Items]
Warrants, measurement input	0.75	1.75
Expected dividend yield
Class of Warrant or Right [Line Items]
Warrants, measurement input	0	0
Strike price
Class of Warrant or Right [Line Items]
Warrants, measurement input	7.50		7.50

Warrants to Acquire Shares of_6

Warrants to Acquire Shares of Common Stock - Changes in Fair Value of Warrant Liability (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Class of Warrant or Right, Fair Value [Roll Forward]
Warrant liability, Beginning balance	$ 40	$ 55
Change in fair value of warrants	(36)	(15)
Warrant liability, Ending balance	$ 4	$ 40

License Revenue with 3D Medic_2

License Revenue with 3D Medicines, Inc. - Narrative (Details) - USD ($)		1 Months Ended		12 Months Ended
	Dec. 31, 2022	May 31, 2022	Dec. 31, 2020	Dec. 31, 2022	Dec. 31, 2021
Revenue from Contract with Customer [Abstract]
Upfront cash payment received			$ 7,500,000	$ 7,500,000
Future milestone payments received			$ 194,500,000
Performance obligation, amount	$ 9,500,000			9,500,000
Milestones probable of being achieved				2,000,000
Licensing revenue					$ 7,600,000
Deferred revenue recognized license					9,500,000
Potential milestone payments to be received	191,500,000			191,500,000	192,500,000
Milestone payment received		$ 1,000,000		13,000,000
Contract acquisition costs	$ 1,400,000			1,400,000
Capitalized contract cost, amortization				0	1,100,000
Cost of revenue				$ 100,000	$ 200,000

Stock-Based Compensation - Narr

Stock-Based Compensation - Narrative (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands			12 Months Ended
	Apr. 22, 2021	Sep. 10, 2019	Dec. 31, 2022	Dec. 31, 2021	Jan. 01, 2023	Dec. 29, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock reserved for issuance (in shares)			7,352
Weighted average exercise price, granted (in dollars per share)			$ 4.52	$ 6.98
Averages contractual term			10 years
Expected dividend yield			0%	0%
Unrecognized compensation cost, options			$ 2,900
Closing price of the company's common stock (in dollars per share)			$ 2.36
Proceeds from employee stock plan purchases			$ 85	$ 0
Total shares of common stock reserved for future issuance (in shares)			7,352
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost, period for recognition			2 years 6 months 18 days
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average exercise price, granted (in dollars per share)			$ 5.34	$ 8
Unrecognized compensation cost, period for recognition			1 year 11 months 19 days
Unrecognized compensation cost			$ 800
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Average vesting term			6 years
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Average vesting term			4 years
2017 Equity Incentive Plan | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock authorized for issuance (in shares)						22
2019 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock authorized for issuance (in shares)		1,964
Increase in number of shares available for future issuance under stock based awards (as a percent)		5%
Shares of common stock reserved for issuance (in shares)			641
Total shares of common stock reserved for future issuance (in shares)			641
2019 Equity Incentive Plan | Subsequent Event
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock reserved for issuance (in shares)					1,691
Total shares of common stock reserved for future issuance (in shares)					1,691
2021 Employee Stock Purchase Plan | Employee Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock reserved for issuance (in shares)			275
Maximum employee subscription rate	20%
Share-based compensation arrangement by share-based payment award, purchase price of common stock, percent	85%
Share based compensation arrangement by share based payment award offering period	6 months
Number of shares purchased (in shares)			25
Proceeds from employee stock plan purchases			$ 100
Total shares of common stock reserved for future issuance (in shares)			275

Stock-Based Compensation - Allo

Stock-Based Compensation - Allocated Stock-based Compensation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated share based compensation expense	$ 1,726	$ 1,011
Research and development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated share based compensation expense	270	126
General and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated share based compensation expense	$ 1,456	$ 885

Stock-Based Compensation - Assu

Stock-Based Compensation - Assumptions for Option Grants Issued (Details)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Share-Based Payment Arrangement [Abstract]
Risk free interest rate	1.96%	1.05%
Volatility	131.51%	121.53%
Expected lives (years)	6 years 2 months 4 days	6 years 2 months 4 days
Expected dividend yield	0%	0%

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock Option Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding, beginning balance (in shares)	1,040	534	208
Granted (in shares)	546	326
Canceled (in shares)	(40)
Outstanding, ending balance (in shares)	1,040	534
Vested and exercisable (In shares)	313
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Weighted average exercise price, beginning balance (in dollars per share)	$ 10.09	$ 13.38
Weighted average exercise price, granted (in dollars per share)	5.01	8
Weighted average exercise price, canceled (in dollars per share)	6.17
Weighted average exercise price, ending balance (in dollars per share)	7.57	$ 10.09
Weighted average exercise price, vested and exercisable (in dollars per share)	$ 12.38
Weighted average remaining contractual term, outstanding (in years)	8 years 5 months 23 days
Weighted average remaining contractual term, vested and exercisable (in years)	7 years 7 months 17 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Aggregate Intrinsic Value [Roll Forward]
Aggregate intrinsic value, outstanding	$ 91
Aggregate intrinsic value, vested and exercisable	$ 66

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of RSU Activity (Details) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Granted (in dollars per share)	$ 4.52	$ 6.98
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Beginning balance (in shares)	200	170
Granted (in shares)	97	40
Vested (in shares)	(40)	(10)
Canceled (in shares)	(2)
Ending balance (in shares)	255	200
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Beginning balance (in dollars per share)	$ 2.81	$ 1.89
Granted (in dollars per share)	5.34	8
Vested (in dollars per share)	6.01	8
Canceled (in dollars per share)	5.34
Ending balance (in dollars per share)	$ 3.25	$ 2.81

Income Taxes - Schedule of Loss

Income Taxes - Schedule of Loss Before Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
U.S.	$ (17,825)	$ (6,956)
Non - U.S.	(23,476)	(13,980)
Loss before income taxes	$ (41,301)	$ (20,936)

Income Taxes - Components of In

Income Taxes - Components of Income Tax Expense (Benefit) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Current
Federal	$ 0	$ 0
State	0	2,000
Foreign	0	0
Total current	0	2,000
Deferred expense
Federal	0	(239,000)
State	0	0
Foreign	0	0
Total deferred	0	(239,000)
Total income tax benefit	$ 0	$ (237,000)

Income Taxes - Components of Ne

Income Taxes - Components of Net Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Net operating loss carryforwards	$ 10,529	$ 9,059
Stock-based compensation	229	140
Licensing deduction deferral	4,503	3,236
Contingent consideration	0	62
Lease liability	198	170
Capitalized Section 174 research and development	765	0
Other	282	217
Gross deferred tax assets	16,506	12,884
Valuation allowance	(16,322)	(12,732)
Net deferred tax assets	$ 184	$ 152

Income Taxes - Components of _2

Income Taxes - Components of Net Deferred Tax Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Right of use asset	$ 184	$ 152
Gross deferred tax liability	$ 184	$ 152

Income Taxes - Schedule of Defe

Income Taxes - Schedule of Deferred Income Taxes (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Net deferred tax asset	$ 184	$ 152
Gross deferred tax liability	(184)	(152)
Net deferred tax liability	$ 0	$ 0

Income Taxes - Schedule of Prov

Income Taxes - Schedule of Provision Computed by Applying Federal Statutory Rate (Details)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
U.S. federal statutory income tax rate	(21.00%)	(21.00%)
State and local taxes, net of federal benefit	(0.10%)	(0.20%)
Foreign rate differential	11.90%	14%
Valuation allowance	8.70%	5.80%
Permanent differences	0.20%	0.20%
Other	0.30%	0.10%
Effective income tax rate	0%	(1.10%)

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Tax Credit Carryforward [Line Items]
Income tax benefit	$ 0	$ (237,000)
Valuation allowance, deferred tax asset, increase, amount	3,600,000
Domestic Tax Authority
Tax Credit Carryforward [Line Items]
Operating loss carryforwards	49,400,000
State and Local Jurisdiction
Tax Credit Carryforward [Line Items]
Operating loss carryforwards	$ 2,600,000

Employee Benefit Plan (Details)

Employee Benefit Plan (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Retirement Benefits [Abstract]
Contribution by employer	$ 129	$ 75