Northwest Biotherapeutics (NWBO) 10-K 28 Feb 23 2022 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2022	Feb. 24, 2023	Jun. 30, 2022
Document and Entity Information
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2022
Document Transition Report	false
Entity File Number	001-35737
Entity Registrant Name	NORTHWEST BIOTHERAPEUTICS, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	94-3306718
Entity Address, Address Line One	Delaware
Entity Address, Address Line Two	Suite 800
Entity Address, City or Town	Bethesda
Entity Address, State or Province	MD
Entity Address, Postal Zip Code	20814
City Area Code	240
Local Phone Number	497-9024
Title of 12(b) Security	Common Stock, par value $0.001 per share
Trading Symbol	NWBO
Security Exchange Name	NONE
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 630,474,000
Entity Common Stock, Shares Outstanding		1,072,879,079
Entity Central Index Key	0001072379
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2022
Current Fiscal Year End Date	--12-31
Amendment Flag	false
Auditor Name	Cherry Bekaert LLP
Auditor Firm ID	677
Auditor Location	Tampa, Florida

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 6,965	$ 15,169
Prepaid expenses and other current assets	2,460	2,121
Total current assets	9,425	17,290
Non-current assets:
Property, plant and equipment, net	13,418	15,027
Construction in progress	2,028
Right-of-use asset, net	4,189	4,889
Indefinite-lived intangible asset	1,292	1,292
Goodwill	626	626
Other assets	345	1,036
Total non-current assets	21,898	22,870
TOTAL ASSETS	31,323	40,160
Current liabilities:
Accounts payable and accrued expenses	10,687	6,976
Accounts payable and accrued expenses to related parties and affiliates	6,955	3,971
Convertible notes, net	135	135
Notes payable, net	15,403	7,104
Contingent payable derivative liability	8,668	8,232
Warrant liability	80,559	106,784
Investor advances	2,566	250
Share liability	678
Lease liabilities	354	317
Total current liabilities	126,005	133,769
Non-current liabilities:
Notes payable, net of current portion, net	5,991	25,156
Lease liabilities, net of current portion	4,370	5,226
Total non-current liabilities	10,361	30,382
Total liabilities	136,366	164,151
COMMITMENTS AND CONTINGENCIES
Mezzanine equity:
Series C Convertible Preferred Stock, 10,000,000 shares designated; 1.4 million and 0 shares issued and outstanding as of December 31, 2022 and 2021, respectively; aggregate liquidation preference of $22.3 million	23,060
Stockholders' deficit:
Preferred stock ($0.001 par value); 100,000,000 shares authorized as of December 31, 2022 and 2021, respectively
Common stock ($0.001 par value); 1,200,000,000 shares authorized; 1,068.4 million and 948.4 million shares issued and outstanding as of December 31, 2022 and 2021, respectively	1,068	948
Additional paid-in capital	1,164,885	1,066,873
Stock subscription receivable	(79)	(79)
Accumulated deficit	(1,297,122)	(1,192,090)
Accumulated other comprehensive income	3,145	357
Total stockholders' deficit	(128,103)	(123,991)
TOTAL LIABILITIES, MEZZANINE EQUITY AND STOCKHOLDERS' DEFICIT	$ 31,323	$ 40,160

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized	100,000,000	100,000,000
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	1,200,000,000	1,200,000,000
Common stock, shares issued	1,068,400,000	948,400,000
Common stock, shares outstanding	1,068,400,000	948,400,000
Series C Convertible Preferred Stock
Temporary equity, shares designated	10,000,000	10,000,000
Temporary equity, shares issued	1,400,000	0
Temporary equity, shares outstanding	1,400,000	0
Temporary equity, aggregate liquidation preference	$ 22.3

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Revenues:
Research and other	$ 1,683	$ 1,005	$ 1,291
Total revenues	1,683	1,005	1,291
Operating costs and expenses:
Research and development	35,511	20,308	33,637
General and administrative	33,353	33,399	54,259
Total operating costs and expenses	68,864	53,707	87,896
Loss from operations	(67,181)	(52,702)	(86,605)
Other income (expense):
Change in fair value of derivative liabilities	(25,821)	239,347	(435,351)
Change in fair value of share liabilities	33
Loss from extinguishment of debt	(2,691)	(165)	(1,582)
Interest expense	(6,068)	(5,011)	(8,544)
Inducement expense		(647)
Foreign currency transaction (loss) gain	(3,304)	(1,696)	2,261
Total other (loss) income	(37,851)	231,828	(443,216)
Net (loss) income	(105,032)	179,126	(529,821)
Other comprehensive income (loss)
Foreign currency translation adjustment	2,788	1,505	(1,984)
Total comprehensive (loss) income	$ (102,244)	$ 180,631	$ (531,805)
Net (loss) earnings per share applicable to common stockholders, Basic	$ (0.10)	$ 0.21	$ (0.73)
Net (loss) earnings per share applicable to common stockholders, Diluted	$ (0.10)	$ (0.06)	$ (0.73)
Weighted average shares used in computing basic (loss) earnings per share	1,015,852	873,517	725,129
Weighted average shares used in computing diluted (loss) earnings per share	1,015,852	1,007,869	725,129

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN MEZZANINE EQUITY AND STOCKHOLDERS' DEFICIT - USD ($) $ in Thousands	Series C convertible preferred stock Preferred Stock	Common Stock	Additional Paid-in Capital	Subscription Receivable	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)	Total
Balance at the beginning at Dec. 31, 2019	$ 0	$ 614	$ 794,900	$ (10)	$ (841,395)	$ 836	$ (45,055)
Balance at the beginning (in shares) at Dec. 31, 2019	0	614,292,000
Issuance of common stock for cash		$ 98	16,462	(69)			16,491
Issuance of common stock for cash (in shares)		97,981,000
Issuance of common stock and warrants for conversion of debt and accrued interest		$ 58	19,591				19,649
Issuance of common stock and warrants for conversion of debt and accrued interest (in shares)		58,368,000
Warrants exercised for cash		$ 48	13,867				13,915
Warrants exercised for cash (in shares)		47,511,000
Reclassification of warrant liabilities related to warrants exercised for cash			22,701				$ 22,701
Cashless warrants and stock options exercise		$ 7	(7)
Cashless warrants and stock options exercise (in shares)		7,086,000
Cashless option exercise (in shares)		71,000					94,000
Reclassification of warrant liabilities related to cashless warrants exercise			9,478				$ 9,478
Beneficial conversion feature related to amended convertible note			44				44
Issuance of common stock in connection with Flaskworks acquisition		$ 1	1,132				1,133
Issuance of common stock in connection with Flaskworks acquisition (in shares)		655,000
Stock-based compensation		$ 4	52,205				52,209
Stock-based compensation (in shares)		3,667,000
Reclassification of warrant liabilities related to sequencing policy			78,292				78,292
Net (loss) income					(529,821)		(529,821)
Cumulative translation adjustment						(1,984)	(1,984)
Balance at the end at Dec. 31, 2020		$ 830	1,008,665	(79)	(1,371,216)	(1,148)	(362,948)
Balance at the end (in shares) at Dec. 31, 2020		829,631,000
Issuance of common stock for cash		$ 6	4,064				4,070
Issuance of common stock for cash (in shares)		6,272,000
Issuance of common stock and warrants for conversion of debt and accrued interest		$ 5	7,495				7,500
Issuance of common stock and warrants for conversion of debt and accrued interest (in shares)		5,145,000
Warrants and stock options exercised for cash (in shares)		86,910,000
Warrants exercised for cash		$ 87	19,888				19,975
Reclassification of warrant liabilities related to warrants exercised for cash			68,692				$ 68,692
Cashless warrants and stock options exercise		$ 20	(20)
Cashless warrants and stock options exercise (in shares)		20,439,000
Cashless option exercise (in shares)							4,720,000
Reclassification of warrant liabilities related to cashless warrants exercise			2,369				$ 2,369
Stock-based compensation			15,571				15,571
Stock-based compensation (in shares)		48,000
Reclassification of warrant liabilities based on authorized shares			(59,851)				(59,851)
Net (loss) income					179,126		179,126
Cumulative translation adjustment	$ 0	$ 0	0	0	0	1,505	1,505
Balance at the end at Dec. 31, 2021		$ 948	1,066,873	(79)	(1,192,090)	357	(123,991)
Balance at the end (in shares) at Dec. 31, 2021		948,445,000
Issuance of stock for cash	$ 18,669
Issuance of stock for cash (in shares)	1,157,000
Issuance of stock in lieu of debt redemption	$ 3,527
Issuance of stock in lieu of debt redemption (in shares)	203
Issuance of stock by common stock warrant exercise	$ 329
Issuance of stock by common stock warrant exercise (in shares)	55
Issuance of common stock for cash		$ 13	9,676				9,689
Issuance of common stock for cash (in shares)		13,147,000
Issuance of common stock and warrants for conversion of debt and accrued interest		$ 19	13,787				13,806
Issuance of common stock and warrants for conversion of debt and accrued interest (in shares)		18,139,000
Warrants exercised for cash		$ 45	11,060				11,105
Warrants exercised for cash (in shares)		45,298,000
Reclassification of warrant liabilities related to warrants exercised for cash	$ 535		24,434				$ 24,434
Cashless warrants and stock options exercise		$ 34	(34)
Cashless warrants and stock options exercise (in shares)		34,224,000
Cashless option exercise (in shares)							8,187,000
Stock-based compensation		$ 9	12,289				$ 12,298
Stock-based compensation (in shares)		9,141,000
Reclassification of warrant liabilities based on authorized shares			26,800				26,800
Net (loss) income					(105,032)		(105,032)
Cumulative translation adjustment						2,788	2,788
Balance at the end at Dec. 31, 2022	$ 23,060	$ 1,068	$ 1,164,885	$ (79)	$ (1,297,122)	$ 3,145	$ (128,103)
Balance at the end (in shares) at Dec. 31, 2022	1,415	1,068,394,000

CONSOLIDATED STATEMENTS OF CH_2

CONSOLIDATED STATEMENTS OF CHANGES IN MEZZANINE EQUITY AND STOCKHOLDERS' DEFICIT (Parenthetical) - Direct Offering $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($)
Warrant liability	$ 10.3
Payments of stock issuance costs	$ 0.6

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Cash Flows from Operating Activities:
Net (loss) income	$ (105,032,000)	$ 179,126,000	$ (529,821,000)
Reconciliation of net (loss) income to net cash used in operating activities:
Depreciation and amortization	1,252,000	324,000	87,000
Amortization of debt discount	2,771,000	2,301,000	3,013,000
Change in fair value of derivatives	25,821,000	(239,347,000)	435,351,000
Change in fair value of contingent liability			913,000
Change in fair value of share liabilities	33,000
Loss from extinguishment of debt	2,691,000	165,000	1,582,000
Inducement expense		647,000
Amortization of operating lease right-of-use asset	248,000	262,000	338,000
Stock-based compensation for services	12,298,000	15,498,000	52,209,000
Non-cash interest expense			4,270,000
Subtotal of non-cash charges	45,048,000	(220,150,000)	497,763,000
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(397,000)	3,475,000	(2,350,000)
Other non-current assets	625,000	(179,000)	(31,000)
Accounts payable and accrued expenses	3,492,000	77,000	1,702,000
Related party accounts payable and accrued expenses	3,354,000	(674,000)	431,000
Lease liabilities	135,000	26,000	213,000
Net cash used in operating activities	(52,775,000)	(38,299,000)	(32,093,000)
Cash Flows from Investing Activities:
Purchase of equipment and construction in progress	(2,902,000)	(6,015,000)	(6,610,000)
Acquisition of Flaskworks, net of cash			(1,532,000)
Net cash used in investing activities	(2,902,000)	(6,015,000)	(8,142,000)
Cash Flows from Financing Activities:
Proceeds from issuance of Series C convertible preferred stock	18,669,000
Proceeds from issuance of Series C convertible preferred stock by common stock warrant exercise, net of debt redemption	52,000
Proceeds from issuance of common stock, net	9,465,000	4,070,000	26,814,000
Proceeds from exercise of warrants and stock options	11,105,000	19,975,000	13,915,000
Proceeds from issuance of notes payable, net	5,600,000	29,665,000	8,557,000
Proceeds from warrants modification			4,000
Proceeds from issuance of convertible notes payable, net			5,115,000
Proceeds from issuance of convertible notes payable to related party			315,000
Investor advances	2,566,000	250,000
Repayment of notes payable	(5,489,000)	(5,828,000)	(1,556,000)
Repayment of notes payable to related parties			(379,000)
Repayment of convertible notes payable			(89,000)
Net cash provided by financing activities	41,968,000	48,132,000	52,696,000
Effect of exchange rate changes on cash and cash equivalents	5,505,000	1,368,000	(2,850,000)
Net (decrease) increase in cash and cash equivalents	(8,204,000)	5,186,000	9,611,000
Cash and cash equivalents, beginning of the period	15,169,000	9,983,000	372,000
Cash and cash equivalents, end of the period	6,965,000	15,169,000	9,983,000
Supplemental schedule of non-cash investing and financing activities:
Issuance of common stock as consideration related to Flaskworks acquisition			220,000
Cashless warrants and stock options exercise	34,000	20,000	7,000
Reclassification of warrant liabilities related to warrants exercised for cash	24,969,000	68,692,000	22,701,000
Reclassification of warrant liabilities related to cashless warrants exercise	26,800,000	2,369,000	9,478,000
Reclassification of warrant liabilities based on authorized shares		59,851,000	78,292,000
Issuance of common stock and warrants for conversion of debt and accrued interest	11,541,000	7,487,000	8,230,000
Offering cost related to warrant liability			4,876,000
Issuance of Series C convertible preferred stock in lieu of debt redemption	3,408,000
Exercise common stock warrants by debt redemption	277,000
Reclassification between shares payable and equity	250,000
Capital expenditures included in accounts payable	699,000	33,000	1,088,000
Capital expenditures included in accounts payable and accrued expenses to related parties and affiliates		370,000
Issuance of common shares to settle accrued service liability		73,000
Issuance of warrants in conjunction with convertible note payable			153,000
Issuance of warrants in connection with debt modification			395,000
Warrant modification in connection with debt amendment			91,000
Beneficial conversion feature related to amended convertible note			44,000
Notes payable
Supplemental disclosure of cash flow information
Interest payments on notes payable			(11,000)
Convertible notes payable
Supplemental disclosure of cash flow information
Interest payments on notes payable			(9,000)
Related party | Notes payable
Supplemental disclosure of cash flow information
Interest payments on notes payable	$ (912,000)	$ (1,730,000)
Related party | Convertible notes payable
Supplemental disclosure of cash flow information
Interest payments on notes payable			$ (19,000)

Organization and Description of

Organization and Description of Business	12 Months Ended
	Dec. 31, 2022
Organization and Description of Business
Organization and Description of Business	1. Organization and Description of Business Northwest Biotherapeutics, Inc. and its wholly owned subsidiaries Flaskworks, Aracaris Ltd, Aracaris Capital, Ltd, Northwest Biotherapeutics B.V., and NW Bio GmbH (collectively, the “Company”, “we”, “us” and “our”) were organized to discover and develop innovative immunotherapies for cancer. The Company has developed DCVax® platform technologies for both operable and inoperable solid tumor cancers. The Company has wholly owned subsidiaries in Boston, in the U.K. and in the Netherlands. The Company relies upon contract manufacturers for production of its DCVax products, research and development services, distribution and logistics, and related services, in compliance with the Company’s specifications and the applicable regulatory requirements. On August 28, 2020, the Company acquired Flaskworks, LLC (“Flaskworks”), a company that has developed a system designed to close and automate the manufacturing of cell therapy products such as DCVax®. The Company has completed a Phase 3 clinical trial of its DCVax-L product for glioblastoma brain cancer, has publicly reported the results in a peer reviewed publication in a medical journal as well as at a medical conference, and is working on prerequisites and preparations for filing an application for regulatory approval of the product.

Financial Condition, Going Conc

Financial Condition, Going Concern and Management Plans	12 Months Ended
	Dec. 31, 2022
Financial Condition, Going Concern and Management Plans
Financial Condition, Going Concern and Management Plans	2. Financial Condition, Going Concern and Management Plans The Company has incurred annual net operating losses since its inception. The Company had a net loss of $105.0 million for the year ended December 31, 2022. The Company used approximately $52.8 million of cash in its operating activities during the year ended December 31, 2022. The Company does not expect to generate material revenue in the near future from the sale of products and is subject to all of the risks and uncertainties that are typically faced by biotechnology companies that devote substantially all of their efforts to research and development (“R&D”) and clinical trials and do not yet have commercial products. The Company expects to continue incurring annual losses for the foreseeable future. The Company’s existing liquidity is not sufficient to fund its operations, anticipated capital expenditures, working capital and other financing requirements until the Company reaches significant revenues. Until that time, the Company will need to obtain additional equity and/or debt financing, especially if the Company experiences downturns in its business that are more severe or longer than anticipated, or if the Company experiences significant increases in expense levels resulting from being a publicly-traded company or from expansion of operations. If the Company attempts to obtain additional equity or debt financing, the Company cannot assume that such financing will be available to the Company on favorable terms, or at all. Because of recurring operating losses and operating cash flow deficits, there is substantial doubt about the Company’s ability to continue as a going concern within one year from the date of this filing. The consolidated financial statements have been prepared assuming that the Company will continue as a going concern, and do not include any adjustments to reflect the possible future effects on the recoverability and classification of assets, or the amounts and classification of liabilities that may result from the outcome of this uncertainty. As previously reported, coronavirus-related difficulties have impacted the Company’s programs, especially with the successive waves of COVID-19 cases in many areas. Although the impact was reduced as the pandemic abated during 2022, the impacts from prior periods continued to affect the Company’s programs. There were supply chain difficulties in regard to certain necessary supplies and reagents. The independent service firms on which the Company relies for a variety of functions had limited capacity, and restrictions on operations. Key experts at certain specialized service providers were unavailable for periods of time due to illness in their family. Other experts went on extended leave due to restrictions on operations. Clinical trial sites did not allow personnel from the contract research organization (CRO) managing the trial, or other service providers, to visit the sites for trial matters such as data monitoring and collection activities. Clinical trial site personnel were unavailable due to being reassigned for COVID-19, and the limited site personnel had to work under restrictions. Committee processes and regulatory processes were focused on COVID-19 matters and delayed on other matters. Firms such as the ones storing the Phase III trial tissue samples that were needed for certain analyses, and the firms conducting such analyses had limited operations. Even logistical matters such as the shipping of materials were subjected to substantial restrictions and delays.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2022
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	3. Summary of Significant Accounting Policies Basis of Presentation The accompanying consolidated financial statements of the Company were prepared in accordance with generally accepted accounting principles in the U.S. (“U.S. GAAP”) and include the assets, liabilities, revenues and expenses of the wholly owned subsidiaries in Germany, United Kingdom and Netherlands. All intercompany transactions and accounts have been eliminated in consolidation. Consolidation The Company’s policy is to consolidate all entities in which it can vote a majority of the outstanding voting stock. In addition, the Company consolidates entities that meet the definition of a variable interest entity (“VIE”) for which the Company is the primary beneficiary, if any. The primary beneficiary is the party who has the power to direct the activities of a VIE that most significantly impact the entity’s economic performance and who has an obligation to absorb losses of the entity or a right to receive benefits from the entity that could potentially be significant to the VIE. As of December 31, 2022 and 2021, the Company did not consolidate any VIE’s as the Company has concluded that it is not the primary beneficiary. Use of Estimates In preparing consolidated financial statements in conformity with U.S. GAAP, management is required 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, as well as the reported amounts of expenses during the reporting period. Due to inherent uncertainty involved in making estimates, actual results reported in future periods may be affected by changes in these estimates. On an ongoing basis, the Company evaluates its estimates and judgments, including valuing equity securities in share-based payment arrangements, estimating the fair value of financial instruments recorded as derivative liabilities, useful lives of depreciable assets and whether impairment charges may apply. The Company bases its estimates on historical experience and on various other assumptions that it believes to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities and the reported amounts of revenues and expenses that are not readily apparent from other sources. Actual results could differ from those estimates, particularly given the significant social and economic disruptions and uncertainties associated with the ongoing coronavirus pandemic (“COVID-19”) and the COVID-19 control responses. Concentration of Credit Risk Financial instruments that potentially subject the Company to concentration of credit risk consist of cash accounts in a financial institution, which at times may exceed the Federal depository insurance coverage (“FDIC”) of $250,000. As of December 31, 2022, of the total $7.0 million in cash and cash equivalents, $0.4 million was held by foreign subsidiaries. As of December 31, 2021, of the total $15.2 million in cash and cash equivalents, $0.5 million was held by foreign subsidiaries. The Company had not experienced losses on these accounts and management believes the Company is not exposed to significant risks on such accounts. Property, Plant and Equipment Property and equipment are stated at cost. Depreciation and amortization are provided for using straight-line methods, in amounts sufficient to charge the cost of depreciable assets to operations over their estimated service lives. Repairs and maintenance costs are charged to operations as incurred. Costs for capital assets not yet placed into service are capitalized as construction in progress on the consolidated balance sheets and will be depreciated once placed into service. In October 2021, approval was received from the UK Human Tissue Authority (“HTA”) of a license for collection and processing of human cells and tissues for medical purposes at the Company’s Sawston, UK facility. In December 2021, approval was received from the UK Medicines and Healthcare Products Regulatory Agency (“MHRA”) of a license for manufacture at the Sawston facility of GMP (clinical grade) cell therapy products for compassionate use and clinical trials. All costs associated with the facility buildout (Phase 1A) were reclassified from construction in progress to leasehold improvements, and the costs began to be amortized over the estimated useful life of the asset and/or leasehold lease. During 2022, the Company the Company commenced the next phase of the Sawston facility buildout: Phase 1B. The Company incurred additional construction works related to Phase 1B build out during the year ended December 31, 2022. Phase 1B is expected to be completed and placed in use by approximately the end of Q2 2023. Those costs were classified as construction in progress on the consolidated balance sheet as of December 31, 2022. The Company assesses its long-lived assets for impairment whenever facts and circumstances indicate that the carrying amounts may not be fully recoverable. To analyze recoverability, the Company projects undiscounted net future cash flows over the remaining lives of such assets. If these projected undiscounted net future cash flows are less than the carrying amounts, an impairment loss would be recognized, resulting in a write-down of the assets with a corresponding charge to earnings. The impairment loss is measured based upon the difference between the carrying amounts and the fair values of the assets. Goodwill and Intangible Assets Goodwill is the excess of purchase price over the fair value of identified net assets of businesses acquired. The Company’s intangible asset with an indefinite life is related to in-process research and development (“IPR&D”) programs acquired in the Flaskworks Acquisition, as the Company expects future research and development on these programs to provide the Company with substantial benefit for a period that extends beyond the foreseeable horizon. Intangible assets with indefinite useful lives are measured at their respective fair values as of the acquisition date. The Company does not amortize goodwill and intangible assets with indefinite useful lives. Intangible assets related to IPR&D projects are considered to be indefinite lived until the completion or abandonment of the associated R&D efforts. If and when development is complete, which generally occurs if and when regulatory approval to market a product is obtained, the associated assets would be deemed finite lived and would then be amortized based on their respective estimated useful lives at that point in time. The Company has one operating segment and one reporting unit. The Company reviews goodwill and indefinite-lived intangible assets at least annually for possible impairment. Goodwill and indefinite-lived intangible assets are reviewed for possible impairment between annual tests if an event occurs or circumstances change that would more likely than not reduce the fair value of the reporting unit or the indefinite-lived intangible assets below their carrying values. No impairment charge was recognized for the year ended December 31, 2022 and 2021. Fair Value of Financial Instruments ASC 820, Fair Value Measurements, provides guidance on the development and disclosure of fair value measurements. Under this accounting guidance, fair value is defined as 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 at the measurement date. 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. The accounting guidance classifies fair value measurements in one of the following three categories for disclosure purposes: Level 1: Quoted prices in active markets for identical assets or liabilities. Level 2: Inputs other than Level 1 prices for similar assets or liabilities that are directly or indirectly observable in the marketplace. Level 3: Unobservable inputs which are supported by little or no market activity and values determined using pricing models, discounted cash flow methodologies, or similar techniques, as well as instruments for which the determination of fair value requires significant judgment or estimation. The Company accounts for the issuance of common stock purchase warrants issued in connection with the equity offerings in accordance with the provisions of ASC 815, Derivatives and Hedging (“ASC 815”). The Company classifies as equity any contracts that (i) require physical settlement or net-share settlement or (ii) gives the Company a choice of net-cash settlement or settlement in its own shares (physical settlement or net-share settlement). The Company accounts for certain common stock warrants outstanding as a liability at fair value and adjusts the instruments to fair value at each reporting period. This liability is subject to re-measurement at each balance sheet date until exercised, and any change in fair value is recognized in its Consolidated Statements of Operations and Comprehensive Loss. The fair value of the warrants issued by the Company has been estimated using Monte Carlo simulation and or a Black Scholes model. The warrant liabilities are valued using Level 3 valuation inputs (see Note 4). Embedded Conversion Features The Company evaluates embedded conversion features within convertible debt instruments to determine whether the embedded conversion feature(s) should be bifurcated from the host instrument and accounted for as a derivative at fair value with changes in fair value recorded in the Statement of Operations. If the conversion feature does not require recognition of a bifurcated derivative, the convertible debt instrument is evaluated for consideration of any beneficial conversion feature (“BCF”) requiring separate recognition. When the Company records a BCF, the intrinsic value of the BCF is recorded as a debt discount against the face amount of the respective debt instrument (offset to additional paid-in capital) and amortized to interest expense over the life of the debt. Derivative Financial Instruments The Company has derivative financial instruments that are not hedges and do not qualify for hedge accounting. Changes in the fair value of these instruments are recorded in other income (expense), on a net basis in the Consolidated Statements of Operations and Comprehensive Loss. Contingent payable derivative liability During the year ended December 31, 2019, the Company entered into a settlement agreement with Cognate BioServices, resolving past matters and providing for the restart of DCVax®-Direct Production. As part of this overall settlement, the Company also provided a contingent note payable (the “Contingent Payable Derivative”) of $10.0 million, which is only payable upon the Company’s first financing after DCVax product approval in or outside the U.S. If such product approval has not been obtained by the seventh anniversary of the agreement, such Contingent Payable Derivative will expire without becoming payable. On a quarterly basis, management makes estimates for key performance milestones and uses the expected dates as the inputs for valuation. The fair value of the Contingent Payable Derivative has been estimated using Monte Carlo simulation, which are valued using Level 3 valuation inputs. Leases The Company recognizes a lease asset for its right to use the underlying asset and a lease liability for the corresponding lease obligation. The Company determines whether an arrangement is or contains a lease at contract inception. Operating leases with a duration greater than one year are included in right-of-use assets, lease liabilities, and lease liabilities, net of current portion in the Company’s consolidated balance sheets. Right-of-use assets and liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. In determining the net present value of lease payments, the Company uses its incremental borrowing rate based on the information available at the lease commencement date. The incremental borrowing rate represents the interest rate the Company would incur at lease commencement to borrow an amount equal to the lease payments on a collateralized basis over the term of a lease. The Company considers a lease term to be the non-cancelable period that it has the right to use the underlying asset. The operating lease right-of-use assets also include any lease payments made and exclude lease incentives. Lease expense is recognized on a straight-line basis over the expected lease term. Variable lease expenses are recorded when incurred. Foreign Currency Translation and Transactions The Company has operations in the United Kingdom and Netherlands in addition to the U.S. The Company translated its assets and liabilities into U.S. dollars using end of period exchange rates, and revenues and expenses are translated into U.S. dollars using weighted average rates. Foreign currency translation adjustments are reported as a separate component of accumulated other comprehensive income (loss) within stockholders’ equity deficit. The Company converts receivables and payables denominated in other than the Company’s functional currency at the exchange rate as of the balance sheet date. The resulting transaction exchange gains or losses related to intercompany receivable and payables, are included in other income and expense. Comprehensive Loss The Company reports comprehensive loss and its components in its consolidated financial statements. Comprehensive loss consists of net loss and foreign currency translation adjustments, affecting stockholders’ equity deficit that, under U.S, GAAP, is excluded from net loss. Revenue Recognition The Company recognizes revenue in accordance with the terms stipulated under the applicable service contract. In various situations, the Company receives certain credits against invoices for manufacturing of patient treatments by its contract manufacturer. These payments are assessed and recognized in accordance with ASC 606 in the period when the performance obligation has been met. Accrued Outsourcing Costs Substantial portions of our preclinical studies and clinical trials are performed by third-party laboratories, medical centers, contract research organizations and other vendors (collectively “CROs”). These CROs generally bill monthly or quarterly for services performed, or bill based upon milestones achieved. For clinical studies, expenses are accrued when services are performed. The Company monitors patient enrollment, the progress of clinical studies and related activities through internal reviews of data that is tracked by the CROs under contractual arrangements, correspondence with the CROs and visits to clinical sites. Research and Development Costs Research and development costs are charged to operations as incurred and consist primarily of clinical trial related costs (including costs for collection, validation and analysis of trial results), related party manufacturing costs, consulting costs, contract research and development costs, clinical site costs and compensation costs. Income Taxes The Company evaluates its tax positions and estimates its current tax exposure along with assessing temporary differences that result from different book to tax treatment of items not currently deductible for tax purposes. These differences result in deferred tax assets and liabilities on the Company’s Consolidated Balance Sheets, which are estimated based upon the difference between the financial statement and tax bases of assets and liabilities using the enacted tax rates that will be in effect when these differences reverse. In general, deferred tax assets represent future tax benefits to be received when certain expenses previously recognized in the Company’s Consolidated Statements of Comprehensive Loss become deductible expenses under applicable income tax laws or loss or credit carryforwards are utilized. Accordingly, realization of the Company’s deferred tax assets is dependent on future taxable income against which these deductions, losses and credits can be utilized. The Company must assess the likelihood that the Company’s deferred tax assets will be recovered from future taxable income, and to the extent the Company believes that recovery is not more likely than not, the Company must establish a valuation allowance. Management judgment is required in determining the Company’s provision for income taxes, the Company’s deferred tax assets and liabilities and any valuation allowance recorded against the Company’s net deferred tax assets. Excluding foreign operations, the Company recorded a full valuation allowance at each balance sheet date presented because, based on the available evidence, the Company believes it is more likely than not that it will not be able to utilize all of its deferred tax assets in the future. The Company intends to maintain the full valuation allowance until sufficient evidence exists to support the reversal of the valuation allowance. Stock-Based Compensation The Company measures stock-based compensation to employees, consultants, and Board members at fair value on the grant date of the award. Compensation cost is recognized as expense on a straight-line basis over the requisite service period of the award. For awards that have a performance condition, compensation cost is measured based on the fair value of the award on the grant date, the date performance targets are established, and is expensed over the requisite service period for each separately vesting tranche when achievement of the performance condition becomes probable. The Company assess the probability of the performance conditions being met on a continuous basis. Forfeitures are recognized when they occur. Prior to January 1, 2019, share-based compensation cost for non-employees was re-measured at every reporting period. The Company estimates the fair value of stock or option grants that do not contain market-based vesting conditions using the Black-Scholes option pricing model and the assumptions used in calculating the fair value of stock-based awards represent management’s best estimates and involve inherent uncertainties and the application of management’s judgment. Expected Term Expected Volatility Risk-Free Interest Rate Expected Dividend The Company is also required to make estimates as to the probability of achieving the specific performance conditions. If actual results are not consistent with the Company’s assumptions and judgments used in making these estimates, the Company may be required to increase or decrease compensation expense, which could be material to the Company’s consolidated results of operations. Debt Extinguishment The Company accounts for the income or loss from extinguishment of debt by comparing the difference between the reacquisition price and the net carrying amount of the debt being extinguished and recognizes this as gain or loss when the debt is extinguished. The gain or loss from debt extinguishment is recorded in the consolidated statements of operations under “other income (expense)” as loss from extinguishment of convertible debt. Sequencing The Company adopted a sequencing policy under ASC 815-40-35 whereby in the event that reclassification of contracts from equity to liabilities is necessary pursuant to ASC 815 due to the Company’s inability to demonstrate it has sufficient authorized shares. This was previously the result of certain financial instruments with a potentially indeterminable number of shares and most recently due to the company committing more shares than authorized. While temporary suspensions are in place to keep the potential exercises beneath the number authorized, certain instruments are classified as liabilities, after allocating available authorized shares on the basis of the earliest grant date of potentially dilutive instruments. Pursuant to ASC 815, issuance of stock-based awards to the Company’s employees, nonemployees or directors are not subject to the sequencing policy. Income (Loss) per Share Basic income (loss) per share is computed on the basis of the weighted average number of shares outstanding for the reporting period. Diluted income (loss) per share is computed on the basis of the weighted average number of common shares plus dilutive potential common shares outstanding using the treasury stock method. Diluted weighted average shares reflect the dilutive effect, if any, of potential common shares. To the extent their effect is dilutive, employee equity awards and other commitments to be settled in common stock are included in the calculation of diluted income per share based on the treasury stock method. Potential common shares are excluded from the calculation of dilutive weighted average shares outstanding if their effect would be anti-dilutive at the balance sheet date based on a treasury stock method or due to a net loss. Recently Adopted Accounting Standards Income Taxes In December 2019, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2019-12, “Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (“ASU 2019-12”), which is intended to simplify various aspects related to accounting for income taxes. ASU 2019-12 removes certain exceptions to the general principles in Topic 740 and also clarifies and amends existing guidance to improve consistent application. This guidance is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020, with early adoption permitted. On January 1, 2021, the Company adopted this standard without any material impact on its consolidated financial statements and related disclosures. Debt 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 simplifies accounting for convertible instruments by removing major separation models required under current GAAP. The ASU removes certain settlement conditions that are required for equity contracts to qualify for the derivative scope exception and it also simplifies the diluted earnings per share calculation in certain areas. This ASU is effective for annual reporting periods beginning after December 15, 2021, including interim periods within those fiscal years. Early adoption was permitted, but no earlier than fiscal years beginning after December 15, 2020. This update permits the use of either the modified retrospective or fully retrospective method of transition. The Company has adopted the new standard as of January 1, 2021 without any material impact on its consolidated financial statements and related disclosures. Modifications or Exchanges of Freestanding Equity-Classified Written Call Options In May 2021, the FASB issued ASU 2021-04, Earnings Per Share (Topic 260), Debt-Modifications and Extinguishments (Subtopic 470-50), Compensation-Stock Compensation (Topic 718), and Derivatives and Hedging-Contracts in Entity’s Own Equity (Subtopic 815-40). This ASU reduces diversity in an issuer’s accounting for modifications or exchanges of freestanding equity-classified written call options (for example, warrants) that remain equity classified after modification or exchange. This ASU provides guidance for a modification or an exchange of a freestanding equity-classified written call option that is not within the scope of another Topic. It specifically addresses: (1) how an entity should treat a modification of the terms or conditions or an exchange of a freestanding equity-classified written call option that remains equity classified after modification or exchange; (2) how an entity should measure the effect of a modification or an exchange of a freestanding equity-classified written call option that remains equity classified after modification or exchange; and (3) how an entity should recognize the effect of a modification or an exchange of a freestanding equity-classified written call option that remains equity classified after modification or exchange. This ASU will be effective for all entities for fiscal years beginning after December 15, 2021. An entity should apply the amendments prospectively to modifications or exchanges occurring on or after the effective date of the amendments. Early adoption is permitted, including adoption in an interim period. On January 1, 2022, the Company adopted this standard without any material impact on the Company’s consolidated financial statements or disclosures. ​ Recently Issued Accounting Standards Not Yet Adopted Fair Value Measurement of Equity Securities Subject to Contractual Sale Restrictions In June 2022, the FASB issued ASU 2022-03, ASC Subtopic 820 “Fair Value Measurement of Equity Securities Subject to Contractual Sale Restrictions”. The FASB is issuing this Update (1) to clarify the guidance in Topic 820, Fair Value Measurement, when measuring the fair value of an equity security subject to contractual restrictions that prohibit the sale of an equity security, (2) to amend a related illustrative example, and (3) to introduce new disclosure requirements for equity securities subject to contractual sale restrictions that are measured at fair value in accordance with Topic 820. For public business entities, the amendments in this Update are effective for fiscal years beginning after December 15, 2023, and interim periods within those fiscal years. Early adoption is permitted for both interim and annual financial statements that have not yet been issued or made available for issuance. The Company is still evaluating the impact of this pronouncement on the consolidated financial statements. ​

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2022
Fair Value Measurements
Fair Value Measurements	4. Fair Value Measurements In accordance with ASC 820 (Fair Value Measurements and Disclosures), the Company uses various inputs to measure the outstanding warrants, certain embedded conversion feature associated with convertible debt and contingent payable to Cognate BioServices on a recurring basis to determine the fair value of the liability. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair value measured at December 31, 2022 ​ ​ ​ Quoted prices in active Significant other Significant ​ ​ Fair value at ​ markets ​ observable inputs ​ unobservable inputs ​ ​ December 31, 2022 ​ (Level 1) ​ (Level 2) ​ (Level 3) Warrant liability ​ $ 80,559 ​ $ — ​ $ — ​ $ 80,559 Embedded redemption option ​ ​ 807 ​ ​ — ​ ​ — ​ ​ 807 Contingent payable derivative liability ​ ​ 8,668 ​ ​ — ​ ​ — ​ ​ 8,668 Share liability ​ 678 ​ — ​ — ​ 678 Total fair value ​ $ 90,712 ​ $ — ​ $ — ​ $ 90,712 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair value measured at December 31, 2021 ​ ​ ​ Quoted prices in active Significant other Significant ​ ​ Fair value at ​ markets ​ observable inputs ​ unobservable inputs ​ ​ December 31, 2021 ​ (Level 1) ​ (Level 2) ​ (Level 3) Warrant liability ​ $ 106,784 ​ $ — ​ $ — ​ $ 106,784 Embedded redemption option ​ 988 ​ — ​ — ​ 988 Contingent payable derivative liability ​ 8,232 ​ — ​ — ​ 8,232 Total fair value ​ $ 116,004 ​ $ — ​ $ — ​ $ 116,004 ​ There were no transfers between Level 1, 2 or 3 during the years ended December 31, 2022 and 2021. The following table presents changes in Level 3 liabilities measured at fair value for the years ended December 31, 2022 and 2021. Both observable and unobservable inputs were used to determine the fair value of positions that the Company has classified within the Level 3 category. Unrealized gains and losses associated with liabilities within the Level 3 category include changes in fair value that were attributable to both observable (e.g., changes in market interest rates) and unobservable (e.g., changes in unobservable long- dated volatilities) inputs (in thousands). ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Warrant ​ Embedded ​ Contingent Payable ​ Share ​ ​ ​ ​ Liability Redemption Option Derivative Liability Liability Total Balance - January 1, 2021 ​ $ 354,972 ​ $ 2,507 ​ $ 8,275 ​ $ — ​ $ 365,754 Additional warrant liability ​ ​ 1,785 ​ ​ — ​ ​ — ​ ​ — ​ ​ 1,785 Additional embedded redemption option ​ ​ — ​ ​ 947 ​ ​ — ​ ​ — ​ ​ 947 Reclassification of warrant liabilities ​ ​ (11,210) ​ ​ — ​ ​ — ​ ​ — ​ ​ (11,210) Debt conversion ​ ​ — ​ ​ (1,925) ​ ​ — ​ ​ — ​ ​ (1,925) Change in fair value ​ ​ (238,763) ​ ​ (541) ​ ​ (43) ​ ​ — ​ ​ (239,347) Balance – December 31, 2021 ​ ​ 106,784 ​ ​ 988 ​ ​ 8,232 ​ ​ — ​ ​ 116,004 Additional warrant liability ​ ​ 184 ​ ​ 7 ​ ​ — ​ ​ — ​ ​ 191 Additional share liability ​ ​ — ​ ​ — ​ ​ — ​ ​ 711 ​ ​ 711 Debt redemption ​ ​ — ​ ​ (213) ​ ​ — ​ ​ — ​ ​ (213) Reclassification of warrant liabilities ​ ​ (51,769) ​ ​ — ​ ​ — ​ ​ — ​ ​ (51,769) Change in fair value ​ ​ 25,360 ​ ​ 25 ​ ​ 436 ​ ​ (33) ​ ​ 25,788 Balance - December 31, 2022 ​ $ 80,559 ​ $ 807 ​ $ 8,668 ​ $ 678 ​ $ 90,712 ​ A summary of the weighted average (in aggregate) significant unobservable inputs (Level 3 inputs) used in measuring the Company’s warrant liabilities and embedded conversion feature (excluding the piggy-back right, which was based on key milestone estimates, see Note 8 for piggy-back rights) that are categorized within Level 3 of the fair value hierarchy as of December 31, 2022 and 2021 is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2022 ​ Warrant Share ​ Contingent Payable ​ ​ Liability ​ Liability ​ Derivative Liability Strike price ​ $ 0.31 ​ $ 0.78 * $ 0.78 * Contractual term (years) ​ 1.5 ​ ​ 0.1 ​ 0.6 ​ Volatility (annual) ​ 86 % ​ 76 % 77 % Risk-free rate ​ 4.3 % ​ 2.0 % 4.8 % Dividend yield (per share) ​ 0 % ​ 0 % 0 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2021 ​ ​ Warrant ​ Contingent Payable ​ ​ Liability Derivative Liability Strike price ​ $ 0.30 ​ $ 0.70 * Contractual term (years) ​ 1.0 ​ 1.6 ​ Volatility (annual) ​ 90 % 72 % Risk-free rate ​ 0.1 % 0.6 % Dividend yield (per share) ​ 0 % 0 % * Contingent payable derivative liability based on stock price as of December 31, 2022 and 2021.

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2022
Stock-Based Compensation
Stock-Based Compensation	5. Stock-Based Compensation The following table summarizes total stock-based compensation expense recognized for the years ended December 31, 2022, 2021 and 2020 (in thousands). ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the years ended ​ ​ December 31, ​ 2022 2021 2020 Research and development ​ $ 1,918 ​ $ 7,607 ​ $ 19,792 Research and development - Advent ​ ​ ​ ​ ​ ​ ​ ​ ​ Milestones achieved (1) ​ ​ 5,870 ​ ​ — ​ ​ — Future milestones (2) ​ ​ 3,573 ​ ​ — ​ ​ — General and administrative ​ ​ 937 ​ 7,964 ​ 32,163 Total stock-based compensation expense ​ $ 12,298 ​ $ 15,571 ​ $ 51,955 ​ The related party amounts were for milestone incentives that either were earned or are deemed probable to be achieved in the future and become issuable at that time (as detailed below in Restricted Stock Awards). (1) During the year ended December 31, 2022, for 8 one-time milestones that were earned, the Company recognized and expensed approximately $5.9 million for 7.5 million shares. (2) For 2 further one-time milestones that are anticipated to be achieved and earned in the future, the Company recognized and expensed (but did not issue shares for) the pro-rata portion on the remaining potential milestone stock awards during the year ended December 31, 2022, of $3.5 million. During the year ended December 31, 2022, the Company reversed approximately $1.4 million and $0.3 million of stock-based compensation expense in research and development and general and administrative, respectively, which were related to the cancellation of certain unvested performance-based awards. The Black-Scholes option pricing model is used to estimate the fair value of stock options granted. The weighted average assumptions used in calculating the fair values of stock options that were granted during the years ended December 31, 2022, 2021 and 2020: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the years ended ​ ​ December 31, ​ 2022 2021 2020 Exercise price ​ $ 0.65 ​ $ 0.92 ​ $ 0.26 ​ Expected term (years) ​ ​ 3.9 ​ 5.3 ​ 5.2 ​ Expected stock price volatility ​ ​ 99 % 97 % 98 % Risk-free rate ​ ​ 3.3 % ​ 1 % ​ 0 % Dividend yield (per share) ​ ​ 0 % 0 % 0 % ​ The total unrecognized compensation cost was approximately $1.6 million as of December 31, 2022 and will be recognized over the next 1.3 years. Stock Options Equity Compensation Plan On May 29, 2020, the Board of Directors of the Company approved a new equity compensation plan (the “Plan”). The Company’s prior plan was adopted in 2007, was updated in amended and restated plans that were approved by shareholders in 2012 and 2013 and expired in 2017 (the “Prior Plan”). The Plan is substantially similar to the Prior Plan. The Plan still has a 10-year life, and allows for awards to employees, directors and consultants of the Company. The Plan allows for any type of equity security to be awarded, as did the Prior Plan. The awards and their terms (including vesting) will be determined by the Board and applicable Committees, as was the case under the Prior Plan. The Plan establishes a pool for equity compensation equal to twenty percent of the outstanding securities of the Company, which is on an evergreen basis as under the Prior Plan. On February 25, 2022, the Company amended its existing Equity Compensation Plan, which was adopted in 2020 as previously reported. The amendment provides that the possible forms of awards under the Plan include awards paid in cash or awards paid in a combination of cash and equity, in addition to the existing provisions for awards made in any form of equity. The amendment also clarifies that a delegation of authority from the Board to a Committee may be either a general delegation or a delegation for a specific occasion. The following table summarizes stock option activity under the Company’s option plans (including awards to key external consultants and vendors in addition to internal parties) during the years ended December 31, 2022, 2021 and 2020 (in thousands, except per share number): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ ​ Weighted ​ Average ​ ​ ​ ​ ​ ​ ​ Average ​ Remaining ​ Total ​ ​ Number of ​ Exercise ​ Contractual ​ Intrinsic ​ ​ Shares ​ Price ​ Life (in years) ​ Value Outstanding as of January 1, 2020 104,659 ​ $ 0.24 8.4 ​ $ — Granted (Approved 2018-2020) (1) ​ 208,525 ​ ​ 0.37 (2) 10.0 ​ ​ — Cashless exercise ​ (94) ​ ​ 0.34 ​ — ​ ​ — Forfeited/expired ​ (4,250) ​ ​ 0.22 ​ — ​ ​ — Outstanding as of December 31, 2020 308,840 ​ 0.33 ​ 8.9 ​ 372,219 Granted 910 ​ 0.92 8.6 ​ — Cash exercised (183) ​ ​ 0.25 — ​ ​ — Cashless exercise ​ (4,720) ​ ​ 0.25 ​ — ​ ​ — Outstanding as of December 31, 2021 ​ 304,847 ​ ​ 0.33 ​ 8.0 ​ ​ 114,803 Granted (3) ​ 8,005 ​ ​ 0.65 ​ 4.4 ​ ​ — Cashless exercised ​ (8,187) ​ ​ 0.27 ​ — ​ ​ — Forfeited/expired ​ (3,402) ​ ​ 0.88 ​ — ​ ​ — Outstanding as of December 31, 2022 ​ 301,263 ​ $ 0.34 ​ 7.0 ​ $ 135,225 Options vested (4) 282,271 ​ $ 0.33 7.0 ​ $ 127,951 (1) The options granted during the year ended December 31, 2020 included options already approved at various times during the three years 2018 - 2020 but not issued until Q3 2020, and also included options that will vest for performance and milestones going forward over the next two years. The options included awards to key external consultants and vendors in addition to internal parties. (2) The weighted average exercise price of the Q3 2020 options was initially $0.25 . However subsequently, the exercise price was amended to a weighted average exercise price of $0.36 . (3) Awards granted to Flaskworks employees and consultants. (4) Approximately 83.3 million options were not exercisable until January 12, 2023, and 153.3 million options are not exercisable until at least April 30, 2023. The existing options and warrants held by Ms. Linda Powers, the Company’s Chief Executive Officer, and Mr. Leslie Goldman, the Company’s Senior Vice President, General Counsel are subject to a voluntary blocking agreement under which they cannot be exercised except upon at least 61 days’ prior notice to the Company. Stock Options Modification On April 30, 2020, the Company’s CEO, Linda Powers agreed to not exercise approximately 39.2 million existing options held by her for six months, until November 1, 2020 and correspondingly extended the contractual term for six months. The Company recognized approximately $78,000 of incremental stock-based compensation for this modification during the year ended December 31, 2020, based on the following weighted average assumptions: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Post Modification Pre Modification Exercise price ​ $ 0.23 ​ $ 0.23 ​ Expected term (years) ​ 4.3 ​ 4.0 ​ Expected stock price volatility ​ 97 % 97 % Risk-free rate of interest ​ 0 % 0 % ​ For another former officer, on August 5, 2020, the Company cancelled 1.75 million options which were originally issued in December 2019 and issued 3.0 million options (the “Replacement Options”) with an exercise price of $0.22 and vesting of 1/3 immediately and the remaining 2/3 vesting ratably over the following 24 months from the grant date. The incremental stock-based compensation for this modification was approximately $0.3 million based on the following weighted average assumptions, which will be amortized over the new vesting terms. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Post Modification Pre Modification Exercise price ​ $ 0.22 ​ $ 0.22 ​ Expected term (years) ​ 5.3 ​ 4.7 ​ Expected stock price volatility ​ 96 % 97 % Risk-free rate of interest ​ 0 % 0 % ​ Flaskworks On August 28, 2020, the Company entered into a Unit Purchase Agreement (the “Agreement”) to acquire Flaskworks. Included in the consideration pursuant to the Agreement was Stock Consideration in the amount of approximately $2.0 million. This Stock Consideration is issued in the form of Rights to receive such value in shares issued pursuant to and subject to the vesting criteria set forth in a Rights Issuance Agreement entered into in connection with the closing of Flaskworks Acquisition. Because the Rights were subject to future employment and performance conditions, the Stock Consideration was not included in consideration payable for the Flaskworks Acquisition but rather was recorded as contingent consideration payable to employees for accounting purposes. The Company anticipates that the treatment of this Stock Consideration for tax purposes may be different than for accounting purposes and will reflect the fact that this Stock Consideration was payment for acquisition of the ownership interests of certain shareholders of Flaskworks. On December 1, 2020, the Company issued 1.5 million shares of common stock based upon the Flaskworks team having completed a significant milestone, in accordance with the Rights Issuance Agreement entered on August 28, 2020. During the year ended December 31, 2022, the Company reversed approximately $1.2 million stock-based compensation due to cancellation of certain unvested performance-based awards. Approximately $0.3 million was reversed from general and administrative and $0.9 million was reversed from research and development during the year ended December 31, 2022. During the years ended December 31, 2021 and 2020, the Company recognized approximately $0.7 million and $1.0 million stock-based compensation related to the Flaskworks Acquisition, respectively. Approximately $0.1 million was recognized in general and administrative and $0.5 million was recognized in research and development during the year ended December 31, 2021. Approximately $0.5 million was recognized in general and administrative and $0.5 million was recognized in research and development during the year ended December 31, 2020. ​ Restricted Stock Awards During April 2022, the Company’s Board approved, and the Company entered into a Statement of Work #6 (the “SOW 6”) with Advent BioServices, a related party of the Company, for five workstreams that are prerequisites for an application for regulatory approval of DCVax-L, for three required licenses for the Sawston facility, and for drafting of key portions of the application. The SOW provides for baseline costs and for milestone incentives for successful completion of each of the workstreams, for the completion and submission of each application for product approval, and for obtaining regulatory approval of each of the three Sawston licenses. The milestone incentives will be a combination of cash and stock and are not paid until they are achieved. On September 26, 2022, the Company amended the SOW6 (the “Amended SOW6”) to (1) extend the service period through September 30, 2023, and (2) clarify the assessment and application of the milestones, and (3) add a sixth workstream. (The potential cost for all unearned stock awards for milestones not yet achieved was re-measured on the modification date and will be further re-measured until the date the milestone award is achieved and the stock awards are earned.) If all of the 10 one-time milestones are achieved (i.e., for all six workstreams that are prerequisites for an application for product approval, for obtaining all three licenses required for the Sawston facility, and for the completion of key portions of the application for product approval), the aggregate stock-based compensation under the Amended SOW 6 will be 13.5 million shares (including the shares already earned and issued for the milestones already achieved). As of December 31, 2022, the 13.5 million shares had an aggregate fair value of $10.1 million. During the year ended December 31, 2022, the Company recognized and expensed (but only partly paid) approximately $4.0 million related to the cash component of seven one-time milestones that were completed and earned during the period. The seven completed milestones included five of the workstreams, and the regulatory approvals of two licenses required for the Sawston facility. (An eighth milestone was partly completed and the stock component of that milestone was earned, as described below, but the cash portion of that eighth milestone was not yet earned). For the cash components of three further one-time milestones under Amended SOW6 that are anticipated to be achieved and earned in the future, the Company recognized and expensed (but did not pay) during the year ended December 31, 2022, the pro-rata portion of $3.7 million. For the stock component of the eight one-time milestones that were earned during the year ended December 31, 2022 (as also described above, in Stock Based Compensation), the Company recognized and expensed $5.9 million for the 7.5 million shares. For two further one-time milestones that are anticipated to be achieved and earned in the future, the Company recognized and expensed (but did not issue) the pro-rata portion of the remaining potential milestone stock awards during the year ended December 31, 2022, of $3.5 million (as also described above, in Stock Based Compensation). Other Service Agreement On August 22, 2022, the Company issued 1.6 million shares of common stock to certain unrelated vendors who provided professional services for the Company. The fair value of the common shares on the issuance date was approximately $1.0 million and was recognized as part of general and administrative expenses.

Property, Plant and Equipment

Property, Plant and Equipment	12 Months Ended
	Dec. 31, 2022
Property, Plant and Equipment
Property, Plant and Equipment	6. Property, Plant and Equipment Property, plant and equipment consist of the following at December 31, 2022 and 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, December 31, Estimated ​ ​ 2022 ​ 2021 ​ Useful Life Leasehold improvements ​ $ 13,070 ​ $ 13,910 Lesser of lease term or estimated useful life Office furniture and equipment ​ 300 ​ 310 3-5 years Computer and manufacturing equipment and software ​ 2,238 ​ 1,799 3-5 years Land in the United Kingdom ​ ​ 82 ​ ​ 92 ​ NA ​ ​ 15,690 ​ 16,111 ​ NA Less: accumulated depreciation ​ (2,272) ​ (1,084) Total property, plant and equipment, net ​ $ 13,418 ​ $ 15,027 ​ ​ ​ ​ ​ ​ ​ ​ ​ Construction in progress ​ $ 2,028 ​ $ — ​ Depreciation expense was approximately $1.3 million, $0.3 million and $87,000 for the years ended December 31, 2022, 2021 and 2020, respectively. Construction in Progress In connection with the Company’s manufacturing facility in U.K, the Company has incurred and is incurring costs with certain vendors and contractors to design and build out certain stages of the facility. Additionally, the Company purchased certain manufacturing equipment that has been or will be installed in connection with the buildout. These costs were all capitalized and recorded as part of construction in progress at December 31, 2020. The Company received approval of an HTA license for collection and processing of human cells and tissues, and received an MHRA license for manufacture of cell therapy products for clinical trials and compassionate use at its Sawston, UK facility in December 2021. All costs associated with the facility buildout (Phase 1A) were reclassified from construction in progress to leasehold improvements effective December 2021 as a result of the receipt of the MHRA license, and are being amortized over the estimated useful life of the facility. During the year ended December 31, 2022, the Company started Phase 1B buildout to expand the operational portions of its UK facility. The additional costs related to the buildout were classified as construction in progress on the consolidated balance sheet as of December 31, 2022.

Notes Payable

Notes Payable	12 Months Ended
	Dec. 31, 2022
Notes Payable
Notes Payable	7. Notes Payable 2022 Activities ​ The following tables summarize outstanding debt as of December 31, 2022 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Stated ​ ​ ​ ​ ​ ​ Embedded ​ ​ ​ ​ ​ ​ ​ Interest ​ Conversion ​ ​ ​ ​ Remaining ​ Redemption ​ Carrying ​ ​ Maturity Date ​ Rate ​ Price ​ Face Value ​ Debt Discount ​ Option ​ Value Short term convertible notes payable ​ ​ ​ ​ ​ ​ ​ 6% unsecured ​ Due ​ 6 % $ 3.09 ​ $ 135 ​ $ — ​ $ — ​ $ 135 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 135 ​ ​ — ​ ​ — ​ ​ 135 Short term notes payable ​ ​ ​ ​ ​ ​ ​ ​ ​ 8% unsecured ​ Various ​ 8 % N/A ​ 14,540 ​ (1,300) ​ 807 ​ 14,047 9% unsecured ​ Various ​ 9 % N/A ​ 793 ​ — ​ — ​ 793 12% unsecured ​ On Demand ​ 12 % N/A ​ 563 ​ — ​ — ​ 563 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 15,896 ​ (1,300) 807 ​ ​ 15,403 Long term notes payable ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 8% unsecured ​ 7/26/2024 ​ 8 % N/A ​ 5,505 ​ (432) ​ — ​ 5,073 6% secured ​ 3/25/2025 ​ ​ 6 % ​ N/A ​ ​ 918 ​ — — ​ ​ 918 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 6,423 ​ ​ (432) ​ ​ — ​ ​ 5,991 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Ending balance as of December 31, 2022 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 22,454 ​ $ (1,732) ​ $ 807 ​ $ 21,529 ​ On September 26, 2022, the Company entered into a Commercial Loan Agreement (the “Commercial Loan”) with a commercial lender for an aggregate principal amount of $5.5 million. The Commercial Loan bears interest at 8% per annum with a 22-month term. There are no principal repayments during the first eight months of the term. The Commercial Loan is amortized in 14 installments starting on May 26, 2023. The Commercial Loan carries an original issue discount of $0.5 million. During the year ended December 31, 2022, the Company entered into multiple four-month note agreements (the “Notes”) with various individual lenders (the “Holders”) with an aggregate principal amount of $0.6 million for net proceeds of $0.6 million. The Notes have a 9% interest rate, a 5% original issue discount (“OID”), and contain a conditional right to independently purchase shares from the Company in a future raise of Capital (the “Piggy-back Right”), under which the Company agrees that if it (i) publicly releases top line data from the Phase III trial of its DCVax®-L vaccine (such eventuality, the “Release”) and (ii) consummates the first private placement offering of its common stock following such Release (the “Next Offering”), then Holder shall have the conditional right, at its sole option, typically exercisable within seven (7) days following the Next Offering, to independently purchase from the Company up to a number of shares equal in value to (a) 50% of the principal amount of the loan, (b) 50% of the value of the exercised warrant shares, and (c) exchange some or all of the outstanding loan amount for a variable number of shares (the “Contingent Rights”). The Contingent Right (a) and (b) above shall be priced at a 12% discount from the Next Offering, resulting in either an elimination of, or a reduced cash amount repayable under the loan agreement. The Company accounted for the Contingent Right (a) and (b) as a freestanding financial instrument, which was classified as a liability at fair value on the Consolidated Balance Sheet with changes in fair value recognized in the Consolidated Statement of Operations. The Company accounted for the Contingent Right (c) as an embedded derivative liability at fair value, which requires it to be bifurcated, with changes in fair value recognized in the Consolidated Statement of Operations. During the year ended December 31, 2022, the Company entered into multiple note extension agreements whereby the maturity date of the notes was extended for an additional two The Company received two loans under the Coronavirus Aid, Relief and Economic Security (“CARES”) Act’s Paycheck Protection Program (“PPP”) in 2021 for the amount of $0.4 million. On February 22, 2022, the PPP loans were approved for forgiveness. The Company recorded approximately $0.4 million debt extinguishment gain from the forgiveness of these PPP loans. During the year ended December 31, 2022, the Company issued approximately 18.1 million shares of common stock at fair value of $13.8 million to certain lenders in lieu of cash payments of $11.3 million debt, including $1.8 million accrued interest. The Company also extinguished approximately $0.2 million embedded derivative liability upon the conversion. The Company recognized approximately $2.3 million debt extinguishment loss during the year ended December 31, 2022. Additionally, pursuant to exchange agreements executed various holders, the Company is required to potentially issue additional common stock (the “Share liability”) if the stock price is less than the price defined in the exchange agreement as of the true-up date. The Company recognized additional $0.7 million debt extinguishment loss related to the Share liability during the year ended December 31, 2022. During the year ended December 31, 2022, the Company issued approximately 0.2 million shares of Series C preferred stock at fair value of $3.5 million to certain lenders in lieu of cash payments of $3.4 million debt, including $0.4 million accrued interest. The Company recognized approximately $0.1 million debt extinguishment loss. See Note 10. During the year ended December 31, 2022, the Company made aggregate cash payments of $6.4 million on notes payable, including $0.9 million of interest payment. For the year ended December 31, 2022, interest expense related to notes payable totaled approximately $2.9 million including amortization of debt discounts totaling $2.8 million. The Company also accrued approximately $0.4 million interest expense related to German taxes during the year ended December 31, 2022 (see Note 12). 2021 Activities The following tables summarize outstanding debt as of December 31, 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Stated ​ ​ ​ ​ ​ ​ Embedded ​ ​ ​ ​ ​ ​ Interest ​ Conversion ​ ​ ​ ​ Remaining ​ Redemption ​ Carrying ​ ​ Maturity Date ​ Rate ​ Price ​ Face Value ​ Debt Discount ​ Option ​ Value Short term convertible notes payable ​ ​ ​ ​ ​ ​ ​ 6% unsecured ​ Due ​ 6 % $ 3.09 ​ $ 135 ​ $ — ​ $ — ​ $ 135 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 135 ​ ​ — ​ — ​ 135 Short term notes payable ​ ​ ​ ​ ​ ​ ​ 8% unsecured ​ Various ​ 8 % N/A ​ 2,320 ​ (118) ​ — ​ 2,202 9% unsecured ​ Various ​ 9 % N/A ​ 4,232 ​ (80) ​ 47 ​ 4,199 12% unsecured ​ On Demand ​ 12 % N/A ​ 703 ​ — ​ — ​ 703 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 7,255 ​ (198) 47 ​ 7,104 Long term notes payable ​ ​ ​ ​ ​ ​ ​ ​ 1% unsecured ​ Various ​ 1 % N/A ​ 433 ​ — ​ — ​ 433 8% unsecured ​ 9/22/2023 ​ 8 % N/A ​ 25,938 ​ (3,638) ​ 941 ​ 23,241 6% secured ​ 3/25/2025 ​ 6 % N/A ​ 1,482 ​ — ​ — ​ 1,482 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 27,853 ​ (3,638) 941 ​ 25,156 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Ending balance as of December 31, 2021 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 35,243 ​ $ (3,836) ​ $ 988 ​ $ 32,395 ​ On March 1, 2021, the Company entered into a Commercial Loan Agreement (the “Commercial Loan”) with a commercial lender for an aggregate principal amount of $10.0 million. The Commercial Loan bears interest at 8% per annum with a 22-month term. There are no principal repayments during the first eight months of the term. The Commercial Loan is amortized in 14 installments starting on November 1, 2021. The Commercial Loan carries an original issue discount of $1.0 million. In April 2021, the Company received two additional PPP loans (“2021 PPP Loans”). The 2021 PPP Loans were received on April 9, 2021 in the amount of $0.4 million total. The current term of the 2021 PPP Loans is five years with a maturity date of March 2026 and it contains a favorable fixed annual interest rate of 1.00%. Payments of principal and interest on the 2021 PPP Loans are deferred for the first 10 months of the term of the 2021 PPP Loans. The Company is using the loan to make payments for payroll, health and disability insurance and rent. On February 22, 2022, the 2021 PPP loans were approved for forgiveness. Between June and December, 2021, the Company entered into multiple four-month note agreements (the “Notes”) with various individual lenders (the “Holders”) with an aggregate principal amount of $4.4 million for net proceeds of $4.2 million. The Notes have a 9% interest rate, a 5% original issue discount (“OID”), and contain a conditional right to independently purchase shares from the Company in a future raise of Capital (the “Piggy-back Right”), under which the Company agrees that if it (i) publicly releases top line data from the Phase III trial of its DCVax®-L vaccine (such eventuality, the “Release”) and (ii) consummates the first offering of its common stock following such Release (the “Next Offering”), then Holder shall have the conditional right, at its sole option typically exercisable within seven (7) days following the Next Offering, to independently purchase from the Company up to a number of shares equal in value to (a) 50% of the principal amount of the loan and (b) exchange some or all of the outstanding loan amount for a variable number of shares (the “Contingent Rights”). Both (a) and (b) above shall be priced at a 12% discount from the Next Offering, resulting in either an elimination of, or a reduced cash amount repayable under the loan agreement. The Company accounted for the Contingent Right (a) as a freestanding financial instrument, which was classified as a liability at fair value on the Consolidated Balance Sheet with changes in fair value recognized in the Consolidated Statement of Operations. The Company accounted for the Contingent Right (b) as an embedded derivative liability at fair value, which requires it to be bifurcated, with changes in fair value recognized in the Consolidated Statement of Operations. Between October and December 2021, the Company entered into multiple note extension agreements whereby the maturity date of the notes was extended for additional 2-4 months. The Company recognized $0.2 million debt extinguishment loss on the Consolidated Statement of Operations due to the extensions. On November 22, 2021, the Company entered into a Commercial Loan Agreement (the “Loan”) with a commercial lender for an aggregate principal amount of $16.5 million. The Loan bears interest at 8% per annum with a 22-month term. There are no principal repayments during the first eight months of the term. The Loan is amortized in 14 equal monthly installments of principal at 110% of the pro rata amount, plus accrued interest. The Loan carries an original issue discount of $1.5 million. The Loan allows pre-payment at any time at the Company’s election. Upon announcement of the top line data (“TLD”) from the Company’s Phase III clinical trial of DCVax®-L for glioblastoma brain cancer, the Lender has a then-springing right to exchange the outstanding balance of the loan for common shares priced at the price of the first private placement transaction following TLD less a 12% discount and to purchase another 50% of that number of shares at the same price. This then-springing right expires 14 days after the post-TLD private placement. During the year ended December 31, 2021, $5.6 million of debt and interest was independently exchanged by the lender into 5.1 million shares of common stock and 0.8 million warrants. The fair value of common stock and warrants for these conversions were approximately $7.5 million, extinguishing approximately $1.9 million in liability from the note conversions. During the year ended December 31, 2021, the Company made aggregate cash payments of $5.8 million on notes payable. Interest Expenses Summary The following table summarizes total interest expenses related to outstanding debt for the years ended December 31, 2022, 2021 and 2020, respectively (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the years ended ​ ​ December 31, ​ 2022 2021 2020 Interest expenses related to outstanding notes: ​ ​ ​ ​ ​ ​ Contractual interest ​ $ 2,890 ​ $ 2,347 ​ $ 1,231 Amortization of debt discount ​ 2,771 ​ 2,301 ​ ​ 2,891 Total interest expenses related to outstanding notes ​ 5,661 ​ 4,648 ​ ​ 4,122 Interest expenses related to outstanding notes to related parties: ​ ​ ​ ​ ​ ​ Contractual interest ​ — ​ — ​ ​ 20 Amortization of debt discount ​ — ​ — ​ ​ 122 Total interest expenses related to outstanding notes to related parties ​ — ​ — ​ ​ 142 Interest expenses related to forbearance of debt to related parties ​ ​ — ​ ​ — ​ ​ 4,270 Interest expenses related to payables to Advent BioServices ​ ​ — ​ ​ 140 ​ ​ — Other interest expenses ​ 407 ​ 223 ​ ​ 10 Total interest expense ​ $ 6,068 ​ $ 5,011 ​ $ 8,544 ​ The following table summarizes the principal amounts of the Company’s debt obligations as of December 31, 2022 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Payment Due by Period ​ ​ ​ ​ ​ Less than ​ 1 to 2 ​ 3 to 5 ​ Total 1 Year Years Years Short term convertible notes payable ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 6% unsecured ​ $ 135 ​ $ 135 ​ $ — ​ $ — Short term notes payable ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 8% unsecured ​ ​ 14,540 ​ ​ 14,540 ​ ​ — ​ ​ — 9% unsecured ​ ​ 793 ​ ​ 793 ​ ​ ​ ​ ​ ​ 12% unsecured ​ ​ 563 ​ ​ 563 ​ ​ — ​ ​ — Long term notes payable ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 8% unsecured ​ ​ 5,505 ​ ​ — ​ ​ 5,505 ​ ​ — 6% secured ​ ​ 918 ​ ​ — ​ ​ — ​ ​ 918 Total ​ $ 22,454 ​ $ 16,031 ​ $ 5,505 ​ $ 918 ​

Net (Loss) Earnings per Share A

Net (Loss) Earnings per Share Applicable to Common Stockholders	12 Months Ended
	Dec. 31, 2022
Net (Loss) Earnings per Share Applicable to Common Stockholders
Net (Loss) Earnings per Share Applicable to Common Stockholders	8. Net (Loss) Earnings per Share Applicable to Common Stockholders Basic (loss) earnings per common share is computed by dividing net (loss) earnings by the weighted average number of common shares outstanding during the reporting period. Diluted earnings (loss) per common share is computed similar to basic (loss) earnings per common share except that it reflects the potential dilution that could occur if dilutive securities or other obligations to issue common stock were exercised or converted into common stock. Diluted weighted average common shares include common stock potentially issuable under the Company’s convertible notes, warrants and vested and unvested stock options. For the year ended December 31, 2021, net income is adjusted for gain from change in fair value of warrant liabilities. The following table sets forth the computation of earnings (loss) per share for the years ended December 31, 2022, 2021 and 2020 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the years ended ​ ​ December 31, ​ ​ 2022 ​ 2021 ​ 2020 Net (loss) earnings - basic ​ $ (105,032) ​ $ 179,126 ​ $ (529,821) Reversal of gain due to change in fair value of warrant liability ​ — ​ (239,347) ​ — Net loss - diluted ​ ​ (105,032) ​ $ (60,221) ​ $ (529,821) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average shares outstanding - basic ​ 1,015,852 ​ 873,517 ​ 725,129 Diluted shares- Options ​ — ​ 38,496 ​ — Diluted shares- Warrants ​ — ​ 95,780 ​ — Convertible notes and interest ​ — ​ 76 ​ — Weighted average shares outstanding - diluted ​ 1,015,852 ​ 1,007,869 ​ 725,129 ​ The following securities were not included in the diluted earnings (loss) per share calculation because their effect was anti-dilutive as of the periods presented (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ For the years ended ​ ​ December 31, ​ 2022 2021 2020 Series C convertible preferred stock ​ 35,384 ​ — ​ — Common stock options ​ 301,263 ​ 266,350 ​ 308,840 Common stock warrants ​ 141,048 ​ 129,689 ​ 328,979 Contingently issuable warrants ​ — ​ — ​ 2,774 Convertible notes and accrued interest ​ 78 — ​ 2,617 Potentially dilutive securities ​ 477,773 ​ 396,039 ​ 643,210 ​

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2022
Related Party Transactions
Related Party Transactions	9. Related Party Transactions Advent BioServices Services Agreements The Company had three operational programs with Advent during 2022: (a) an ongoing manufacturing program at the existing GMP facility in London, (b) an ongoing development and manufacturing program at the Sawston facility, and (c) a one-time program for specialized work, organized into 10 sets of one-time milestones, for the following: ● Qualifying for and obtaining 3 required licenses for the Sawston facility: a license from the Human Tissue Authority to collect and process human cells and tissues, a license from the MHRA for manufacturing for clinical trials and compassionate use cases, and a license from the MHRA for commercial manufacturing; ● 6 workstreams relating to product matters required for an application for regulatory approval of DCVax-L, including Comparability, Stability, Potency, Product Profile, Mechanism of Action and Fill/Finish. ● Drafting of key portions of the application for product approval itself. Each of the three operational programs is covered by a separate contract. The ongoing manufacturing in the London facility is covered by a Manufacturing Services Agreement (“MSA”) entered into on May 14, 2018, as previously reported. The development and manufacturing program at the Sawston facility is covered by an Ancillary Services Agreement entered into on November 18, 2019, as previously reported. The specialized work associated with the 10 one-time milestones is covered by an SOW 6 entered into under the Ancillary Services Agreement as of April 1, 2022 and amended on September 26, 2022. The Ancillary Services Agreement establishes a structure under which the Company and Advent negotiate and agree upon the scope and terms for Statements of Work (“SOWs”) for facility development activities and compassionate use program activities. After an SOW is agreed and approved by the Company, Advent will proceed with, or continue, the applicable services and will invoice the Company pursuant to the SOW. Since both the facility development and the compassionate use program involve pioneering and uncertainties in most aspects, the invoicing under the Ancillary Services Agreement is on the basis of costs incurred plus fifteen percent. The SOWs may involve ongoing activities or specialized one-time projects and related one-time milestone payments. The current term of the Ancillary Services Agreement ends in July 2023. SOW 6 provides for ongoing baseline costs for manufacturing at the Sawston facility and one-time milestone incentives for (a) regulatory approval of each of the 3 licenses required for the Sawston facility, (b) successful completion of each of the 6 workstreams and (c) completion of drafting key portions of an application for product approval. The milestone incentives are a combination of cash and stock, and are not paid until the milestone is achieved and earned. During the year ended December 31, 2022, the Company paid an aggregate of $3.0 million in cash and 7.5 million shares at fair value of approximately $5.9 million combined for completion of 7 one-time milestones and partial completion of an 8 th The following table summarizes total research and development costs from Advent for the years ended December 31, 2022, 2021 and 2020, respectively (in thousands). ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the Year ended December 31, 2021 ​ ​ 2022 ​ 2021 ​ 2020 Advent BioServices ​ ​ ​ Manufacturing cost in London ​ $ 5,675 ​ $ 6,625 ​ $ 5,288 Manufacturing cost at Sawston facility ​ 5,766 ​ 792 ​ 2,255 SOW 6 one-time milestones - Shares ​ ​ ​ Expensed and paid (milestone complete) (1) ​ 5,120 ​ — ​ — Expensed and paid (partial milestone earned) (2) ​ 750 ​ — ​ — Expensed but unpaid, not yet due (milestone not yet complete) (3) ​ 3,573 ​ — ​ — SOW 6 one-time milestones - Cash ​ ​ ​ ​ ​ ​ Expensed and paid (milestone complete) (4) ​ 3,000 ​ — ​ — Expensed and due, but unpaid (milestone complete) (5) ​ 1,000 ​ — ​ — Expensed but unpaid, not yet due (milestone not yet complete) (6) ​ 3,700 ​ — ​ — Total ​ $ 28,584 ​ $ 7,417 ​ $ 7,543 (1) This payment covers 7 one-time milestones: 5 workstreams (Comparability, Stability, Potency, Product Profile, Fill/Finish), and 2 required licenses for the Sawston facility (licenses from the Human Tissue Authority and from the MHRA for manufacturing for clinical trials and compassionate use cases). (2) This covers the one-time milestone workstream: Mechanism of Action. (3) This covers the one-time milestone for obtaining a commercial manufacturing license from the MHRA, and the one-time milestone for drafting key portions of the application for product approval. (4) This payment covers 5 one-time milestones: 3 workstreams (Comparability, Potency, Fill/Finish ), and 2 required licenses for the Sawston facility (licenses from the Human Tissue Authority and from the MHRA for manufacturing for clinical trials and compassionate use cases). (5) This covers the 2 one-time milestone workstreams: Product Profile and Stability. (6) This covers 3 one-time milestones: Mechanism of Action, milestone for obtaining a commercial manufacturing license from the MHRA, and the milestone for drafting key portions of the application for product approval. Additionally, the Company capitalized $28,000 and $3.2 million costs related to the Sawston buildout as of December 31, 2022 and 2021, respectively. The buildout contractors and process were overseen by Advent, and buildout costs were reviewed and invoiced by Advent. Advent BioServices Sublease Agreement On December 31, 2021, the Company entered into a Sub-lease Agreement (the “Agreement”) with Advent. The Agreement permits use by Advent of a portion of the space in the Sawston facility, which is leased by the Company under a separate head lease with a different counterparty (Huawei) that commenced on December 14, 2018. The Company subleased approximately 14,459 square feet of the 88,000 square foot building interior space, plus corresponding exterior support space and parking. The lease payments amount under the Agreement are two times the £5.75 (approximate $6.96 per square foot based on exchange rate as of December 31, 2022) rate per square foot payable under the head lease, but subject to a cap of $10 per square foot. Accordingly, the monthly lease payments under the Sublease are based on $145,000 annually for 2022. The total lease payments paid by the Company to Huawei for the facility, exterior spaces and parking under the head lease are 500,000 pounds (approximately $600,000) per year. The term of the Agreement shall end on the same date as the head lease term ends. During the year ended December 31, 2022, the Company recognized sub-lease income of $145,000. Related Party Accounts Payable As of December 31, 2022, there was approximately $0.4 million unpaid board compensation to one of our Directors that was included in the accounts payable to related party on the consolidated balance sheets. As of December 31, 2022, there were outstanding unpaid accounts payable and accrued expenses owed to Advent as summarized in the following table (in thousands). These unpaid amounts are part of the Related Party expenses reported in the above section. The 2021 balance also included certain expenses incurred in prior periods. ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 December 31, 2021 Advent BioServices - amount invoiced but unpaid ​ $ 1,844 ​ $ 3,046 Advent BioServices - amount accrued and unpaid ​ ​ 4,736 ​ ​ — Accounts payable and accrued expenses owed to Advent BioServices ​ $ 6,580 ​ $ 3,046 ​ Related Parties Loans Loan from Advent BioServices Advent BioServices provided a short-term loan to the Company in the amount of $65,000 on September 26, 2018. The loan bore interest at 10% per annum, and is payable upon demand, with seven days’ prior written notice to the Company. During the year ended December 31, 2020, the Company made full repayment of $73,000 to Advent, including all outstanding interest. Loan from Leslie Goldman During the year ended December 31, 2020, the Company’s Senior Vice President and General Counsel, Leslie Goldman, loaned the Company $0.3 million pursuant to various convertible notes (the “Notes”). The Notes bore interest rate at 10% per annum and 50% During the year ended December 31, 2020, the Company made full repayment of $0.3 million to Mr. Goldman, including all outstanding interest. Warrants issued to Linda Powers On July 2, 2020, the Company issued approximately 15.2 million warrants (the “Forbearance Warrants”) to Ms. Powers in consideration for Ms. Powers’ previously reported forbearance and extension of loans of $5.4 million from Ms. Powers to the Company. These warrants were approved by the Board in November 2018 when the loans were long overdue, as previously reported, and the warrants were re-approved in January 2020, but were not issued until July 2, 2020. The Forbearance Warrants have an exercise price of $0.21 per share with 5-year

Preferred Stock

Preferred Stock	12 Months Ended
	Dec. 31, 2022
Preferred Stock.
Preferred Stock	10. Preferred Stock Series C Convertible Preferred Stock On July 20, 2022, the Company filed a Certificate of Elimination with the Secretary of State of the State of Delaware with respect to the Company’s Series A Preferred Stock and Series B Preferred Stock pursuant to which both series were eliminated and returned to the status of authorized and unissued preferred shares of the Company, as there are no longer any Series A or Series B Preferred shares outstanding. Also on July 20, 2022, the Company filed the Certificate of Designations for Series C Preferred Stock (the “Series C Certificate of Designations”) with the Secretary of State of the State of Delaware, setting forth the terms of the Series C Preferred Stock. The Series C Certificate of Designations, effective as of July 20, 2022, that was created out of the authorized and unissued shares of preferred stock of the Company, provides for 10,000,000 shares, par value $0.001 per share, and establishes the rights, preferences and privileges of the Series C. During the year ended December 31, 2022, the Company entered into various Subscription Agreements (the “Series C Subscription Agreements”) with certain investors (the “Series C Investors”). Pursuant to the Series C Subscription Agreements, the Company issued the Series C Investors an aggregate of 1.4 million shares of the Company’s Series C convertible preferred stock, par value $0.001 per share (the “Series C Shares”), at a weighted purchase price of $16.15 per share for gross proceeds of approximately $22.0 million. Pursuant to some of the Series C Subscription Agreements, certain Series C investors chose to purchase the Series C Shares by debt redemption. During the year ended December 31, 2022, the Company extinguished approximately $3.4 million debt, including $0.4 million of accrued interest in lieu of partial consideration received for issuance the Series C Shares. The Company received approximately $18.7 million net proceeds from issuance of the Series C Shares. Additionally, as a partial consideration for certain Series C investors, the Company agreed to amend the terms of the warrants that are currently held by them. On August 12, 2022, an unrelated investor exercised existing warrants to purchase 1.4 million common shares at a weighted average exercise price of $0.24 per share and a total purchase price of approximately $329,000. The warrant holder agreed to receive Series C Preferred Shares instead of common shares and agreed that these Series C shares could not be converted for a period of three months. Since Series C Preferred shares are convertible into common shares at a ratio of 1 Each of the Series C Shares which were sold for prices between $15.00 and $21.25 per share will be convertible into 25 shares of common stock (equivalent to prices of $0.60 to $0.85 per share of common stock) at the option of the holder three months after the effective date of purchase. The Company determined that the Series C Shares contain contingent redemption provisions allowing redemption by the holder upon certain defined events (“deemed liquidation events”). As the event that may trigger the redemption of the Series C Shares is not solely within the Company’s control, the Series C Shares are classified as mezzanine equity (temporary equity) in the Company’s consolidated balance sheets.

Stockholders' Deficit

Stockholders' Deficit	12 Months Ended
	Dec. 31, 2022
Stockholders' Deficit
Stockholders' Deficit	11. Stockholders’ Deficit 2022 Activities Common Stock Common Stock Issued for Cash During the year ended December 31, 2022, the Company received $9.5 million from issuance of 13.1 million shares of common stock to various investors. Warrants Exercised for Cash During the year ended December 31, 2022, the Company received $11.1 million from the exercise of warrants issued in the past with an exercise price between $0.18 and $0.85. The Company issued approximately 45.3 million shares of common stock and 0.3 million Series C convertible preferred stock in lieu of common stock upon these warrant exercises. Warrants and Options Cashless Exercise During the year ended December 31, 2022, certain warrant holders elected to exercise some of their warrants pursuant to cashless exercise formulas. The Company issued approximately 29.0 million shares of common stock for exercise of 36.0 million warrants at exercise prices between $0.18 and $0.52. During the year ended December 31, 2022, certain options holders elected to exercise some of their options pursuant to cashless exercise formulas. The Company issued approximately 5.2 million shares of common stock for exercise of 8.2 million options at exercise prices between $0.23 and $0.34. Debt Redemption During the year ended December 31, 2022, the Company issued approximately 18.1 million shares of common stock to certain lenders in lieu of cash payments on $11.3 million outstanding debt, including $1.8 million interest. 2021 Activities Common stock Issued for Cash During the year ended December 31, 2021, the Company received $4.1 million from issuance of 6.3 million shares of common stock to various investors. The Company also received $0.3 million partial proceeds pursuant to one security purchase agreement. Accordingly, such amounts are included in Investor advances in the accompanying consolidated balance sheet as of December 31, 2021. Warrants and Stock Options Exercised for Cash During the year ended December 31, 2021, the Company received $20.0 million from the exercise of warrants and stock options issued in the past with an exercise price between $0.175 and $0.40. The Company issued approximately 86.9 million shares of common stock upon these warrant and stock option exercises. The Company also entered into certain warrant exercise agreements which contain a conditional right to purchase shares directly from the Company in a future raise of capital (the “Piggy-back Right”). In exchange for these exercises, the Company agreed that if the Company (i) publicly releases top line data from the Phase III trial of its DCVax®-L vaccine (such eventuality, the “Release”) and (ii) consummates the first offering of its common stock following such Release (the “Next Offering”) then Holder shall have the conditional right, at its sole option exercisable typically within seven days following the Next Offering, to independently purchase from the Company up to a number of shares equal in value to 50% of the Total Exercise Amount provided that: the price per share paid by Holder shall be equal to the Next Offering price per share less 12%. This Piggy-back Right was granted to the warrant holders in connection with their early exercise of warrants prior to the Release. The Company recognized approximately $0.6 million inducement expense during the year ended December 31, 2021. Warrants and Stock Options Cashless Exercise During the year ended December 31, 2021, certain warrant and stock option holders elected to exercise some of their warrants and stock options pursuant to cashless exercise formulas. The Company issued approximately 20.4 million shares of common stock for exercise of 24.5 million warrants and stock options. The exercise prices were between $0.20 and $0.52. 2020 Activities Registered Direct Offering Between January and February 2020, the Company issued an aggregate of 34.5 million shares of its common stock in a registered direct offering (the “Offering”). The net proceeds from the Offering were approximately $5.7 million, after deducting offering costs of $0.4 million paid by the Company. In connection with the Offering, the Company also issued approximately 8.5 million 2-year 2-year During April 2020, the Company issued an aggregate of 19.9 million shares of its common stock and 11.3 million new issued warrants in a registered direct offering (the “April Financing”). The common stock was offered at a price of $0.153 per share. The warrants are exercisable at $0.20 per share. The net proceeds from the April Financing were approximately $3.0 million, after deducting offering costs of $68,000 paid by the Company. An approximate $0.8 million of proceeds were allocated to warrant liabilities. During May 2020, the Company issued an aggregate 14.2 million shares of its common stock and 5.6 million new issued warrants in a registered direct offering (the “May Financing”). The common stock was offered at a price between $0.17 and $0.225 per share. The warrants have an exercise price between $0.22 and $0.23 per share and an exercise period between 1.5-2.5 years. The Company received approximately $2.9 million from the May Financing. An approximate $0.9 million of proceeds were allocated to warrant liabilities. All of the warrants issued in the May Financings were not exercisable until November 1, 2020. In addition, as part of these agreements, the investors who have existing outstanding warrants that had not already been suspended until November 1, suspended approximately 14.6 million existing warrants until November 1, 2020. On August 5, 2020, the Company entered into financings totaling approximately $8.0 million (the “August Financing”). The financings were comprised of: ● Approximately $7.0 million from an offering at $0.32 per share of newly registered common stock of approximately 21.8 million shares with 20 - 35% warrants coverage. The warrants are exercisable at $0.34 per share for approximately 5.3 million shares, with an exercise period of 18 to 30 months . The fair value of these 5.3 million warrants was approximately $1.5 million. ● $1.0 million from a convertible note (the “August Note”) which is convertible at $0.345 per share. The August Note carries no warrants unless it is converted. If, and only to the extent, the note is converted it will carry 35% warrants exercisable at $0.34 per share. ● All of the new warrants issued in the August Financing were suspended until December 15, 2020. ● In addition, as part of these agreements, the investors who have existing outstanding warrants that had not yet been suspended, suspended approximately 75.5 million additional existing warrant exercise shares until December 15, 2020. In consideration for the suspension of the 75.5 million existing warrant shares as part of the August Financing, the Company issued approximately 12.5 million warrants with an exercise price of $0.34 per share and an exercise period ranging from approximately 13.5 to 25.5 months following the termination of the suspensions. These suspension consideration warrants were also suspended until the same December date. ● Only the common stock sold directly or underlying the warrants and convertible note were registered in this transaction. On October 12, 2020, the Company entered into financings totaling approximately $11.9 million (the “Offering”). The financings were comprised of: ● Approximately $10.0 million from an offering at $0.816 per share (based upon the average 10 day closing price ending on October 12, 2020) of newly registered common stock of approximately 12.2 million shares with 30% warrants coverage. The warrants are exercisable at an exercise price of $2.00 per share for approximately 3.6 million shares, with an exercise period of 12 months (following a 3-month suspension after issuance). The fair value of these 3.6 million warrants was approximately $1.2 million. ● Approximately $1.9 million from a convertible note which is convertible at $0.85 per share (the “Note”). The Note carries no warrants unless it is converted. If, and only to the extent, the Note is converted it will carry 30% warrants with an exercise price of $2.00 per share and an exercise period of 12 months (following a 3-month suspension after issuance). ● All of the new warrants issued in the Offering are suspended until January 15, 2021. In addition, as part of these agreements, certain investors who have existing outstanding warrants that have not yet been suspended are now suspending approximately 3.5 million additional existing warrant exercise shares until January 15, 2021. In consideration for the suspension of the 3.5 million existing warrant shares as part of the Offering, the Company issued approximately 261,000 warrants with an exercise price of $2.00 per share and an exercise period of 12 months (following a 3-month suspension after issuance). These suspension consideration warrants are also suspended until the same January date. Warrants Exercised for Cash During the year ended December 31, 2020, the Company issued 47.5 million shares of its common stock from warrants exercised for cash. The Company received $13.9 million in cash. Cashless Warrants Exercise During the year ended December 31, 2020, The Company issued approximately 7.1 million shares of common stock upon 8.6 million warrant cashless exercises with weighted average exercise price of $0.22. Debt Conversion During the year ended December 31, 2020, the Company converted approximately $13.9 million outstanding debt and interest into 58.4 million shares of common stock and 6.2 million warrants. Flaskworks Shares Issuance On December 1, 2020, the Company issued 1.5 million shares of common stock based upon the Flaskworks team having completed a significant milestone, in accordance with the Rights Issuance Agreement entered on August 28, 2020. On December 25, 2020, upon the seller’s election, the Company issued 0.7 million shares in equivalent of $0.2 million special consideration payment pursuant to the Unit Purchase Agreement. The $0.336 per share price was established by the Unit Purchase Agreement. The incremental change in fair value of the shares resulting from market price increase was approximately $0.9 million, which was recognized as additional general and administrative expense on the consolidated statement of operations. Stock Purchase Warrants The following is a summary of warrant activity for the years ended December 31, 2022, 2021 and 2020 (in thousands, except per share data): ​ ​ ​ ​ ​ ​ ​ ​ ​ Number of Weighted Average Remaining ​ ​ Warrants ​ Exercise Price ​ Contractual Term Outstanding as of January 1, 2020 359,473 ​ $ 0.27 1.42 Warrants granted 88,658 ​ 0.22 ​ Contingently issuable warrants (1) 2,774 ​ 1.48 ​ Warrants exercised for cash (47,511) ​ 0.29 ​ Cashless warrants exercise (8,631) ​ ​ 0.22 ​ Warrants expired and cancellation ​ (63,010) ​ ​ 0.32 ​ ​ Outstanding as of December 31, 2020 331,753 ​ $ 0.28 1.61 Warrants granted 1,209 ​ 1.39 ​ Warrants exercised for cash ​ (86,726) ​ ​ 0.23 ​ ​ Cashless warrants exercise (19,743) ​ 0.22 ​ Warrants expired and cancellation (1,024) ​ ​ 2.95 ​ Outstanding as of December 31, 2021 ​ 225,469 ​ $ 0.30 ​ 0.96 Warrants exercised for cash ​ (46,671) ​ ​ 0.25 ​ ​ Cashless warrants exercise ​ (35,951) ​ ​ 0.23 ​ ​ Warrants expired and cancellation ​ (1,799) ​ ​ 1.58 ​ ​ Outstanding as of December 31, 2022 ​ 141,048 ​ $ 0.31 ​ 1.46 ​ The options and warrants held by Ms. Powers and Mr. Goldman are subject to an ongoing suspension on a rolling basis pursuant to the Blocker Letter. In addition, other executive officers and directors extended their suspensions to various dates until at least April 30, 2023. At December 31, 2022, of the 141 million total outstanding warrants listed above, approximately 137 million warrants were under block or suspension agreements. The Company’s total authorized shares for common stock were increased by 500 million shares as described in the Note 15. Subsequent events. As of February 28, 2023, approximately 59 million warrants are still under block or suspension agreements.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2022
Commitments and Contingencies.
Commitments and Contingencies	12. Commitments and Contingencies Operating Lease- Lessee Arrangements Company has operating leases for corporate offices in the U.S. and U.K., and for manufacturing facilities in the U.K. The Leases with an initial term of 12 months or less are not recorded in the balance sheet. The Company has elected the practical expedient to account for each separate lease component of a contract and its associated non-lease components as a single lease component, thus causing all fixed payments to be capitalized. The Company also elected the package of practical expedients permitted within the new standard, which among other things, allows the Company to carry forward historical lease classification. The lease renewal options have not been included in the calculation of the lease liabilities and right-of-use (“ROU”) assets as the Company has not yet determined whether to exercise the options. Variable lease payment amounts that cannot be determined at the commencement of the lease such as increases in lease payments based on changes in index rates or usage, are not included in the ROU assets or liabilities. These are expensed as incurred and recorded as variable lease expense. At December 31, 2022, the Company had operating lease liabilities of approximately $4.7 million for both the 20-year Operating Lease- Lessor Arrangements On December 31, 2021, the Company entered into a Sub-lease Agreement (the “Agreement”) with Advent, a related party as discussed in Note 8. The Agreement permits use by Advent of a portion of the space in the Sawston facility which is leased by the Company under a separate head lease with a different counterparty that commenced on December 14, 2018. The Company subleased approximately 14,459 square feet of 88,000 square foot building interior space, plus corresponding exterior support space and parking located in Sawston, UK. Lease payments under the Agreement are two times the £5.75 (approximate $6.96 per square foot based on exchange rate as of December 31, 2022) rate per square foot payable under the head lease, subject to a cap of $10 per square foot. Accordingly, the lease payments under the Sublease are set at $145,000 per year. The total lease payments paid by the Company for the overall building, exterior space and parking under the head lease are 500,000 pounds per year. The term of the Agreement shall end on the same date as the head lease term ends. As the Agreement was effective on December 31, 2021, the Company started to recognize sub-lease income on January 1, 2022. The following summarizes quantitative information about the Company’s operating leases (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the Year ended ​ ​ December 31, 2022 ​ U.K U.S Total Lease cost ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating lease cost ​ $ 588 ​ $ 260 ​ $ 848 Short-term lease cost ​ ​ 79 ​ ​ — ​ ​ 79 Variable lease cost ​ ​ — ​ ​ 13 ​ ​ 13 Sub-lease income ​ ​ (145) ​ ​ — ​ ​ (145) Total ​ $ 522 ​ $ 273 ​ $ 795 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other information ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating cash flows from operating leases ​ $ (619) ​ $ (290) ​ $ (909) Weighted-average remaining lease term – operating leases ​ ​ 8.5 ​ ​ 1.3 ​ ​ ​ Weighted-average discount rate – operating leases ​ ​ 12 % ​ 12 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the Year ended ​ ​ December 31, 2021 ​ U.K U.S Total Lease cost ​ ​ ​ Operating lease cost ​ $ 653 ​ $ 277 ​ $ 930 Short-term lease cost ​ 51 ​ — ​ 51 Variable lease cost ​ 48 ​ 5 ​ 53 Total ​ $ 752 ​ $ 282 ​ $ 1,034 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other information ​ ​ ​ ​ ​ ​ Operating cash flows from operating leases ​ $ (688) ​ $ (178) ​ $ (866) Weighted-average remaining lease term – operating leases ​ 9.0 ​ 1.8 ​ ​ Weighted-average discount rate – operating leases ​ 12 % 12 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the Year ended ​ ​ December 31, 2020 ​ ​ U.K ​ U.S ​ Total Lease cost ​ ​ ​ Operating lease cost ​ $ 610 ​ $ 330 ​ $ 940 Short-term lease cost ​ 44 ​ — ​ 44 Variable lease cost ​ 45 ​ 20 ​ 65 Total ​ $ 699 ​ $ 350 ​ $ 1,049 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other information ​ ​ ​ ​ ​ ​ Operating cash flows from operating leases ​ $ (661) ​ $ (332) ​ $ (993) Weighted-average remaining lease term – operating leases ​ 9.1 ​ 0.2 ​ Weighted-average discount rate – operating leases ​ 12 % 12 % ​ The Company recorded lease costs as a component of general and administrative expense during the years ended December 31, 2022, 2021 and 2020. ​ Maturities of our operating leases, excluding short-term leases and sublease agreement, are as follows: ​ ​ ​ ​ ​ Year ended December 31, 2023 $ 903 Year ended December 31, 2024 ​ ​ 809 Year ended December 31, 2025 ​ ​ 604 Year ended December 31, 2026 ​ ​ 604 Year ended December 31, 2027 ​ ​ 604 Thereafter ​ ​ 6,631 Total ​ ​ 10,155 Less present value discount ​ ​ (5,431) Operating lease liabilities included in the Consolidated Balance Sheet at December 31, 2022 ​ $ 4,724 ​ Maturities of our operating leases under the sublease agreement, are as follows: ​ ​ ​ ​ ​ Year ended December 31, 2023 $ 145 Year ended December 31, 2024 ​ 145 Year ended December 31, 2025 ​ 145 Year ended December 31, 2026 ​ 145 Thereafter ​ 1,740 Total ​ $ 2,320 ​ Advent BioServices Services Agreement The Company had three operational programs with Advent during 2022: (a) an ongoing manufacturing program at the existing GMP facility in London, (b) an ongoing development and manufacturing program at the Sawston facility, and (c) a one-time program for specialized work, organized into 10 sets of one-time milestones, for the following: ● Qualifying for and obtaining 3 required licenses for the Sawston facility: a license from the Human Tissue Authority to collect and process human cells and tissues, a license from the MHRA for manufacturing for clinical trials and compassionate use cases, and a license from the MHRA for commercial manufacturing; ● 6 workstreams relating to product matters required for an application for regulatory approval of DCVax-L, including Comparability, Stability, Potency, Product Profile, Mechanism of Action and Fill/Finish. ● Drafting of key portions of the application for product approval itself. On May 14, 2018, the Company entered into a DCVax®-L Manufacturing and Services Agreement (“MSA”) with Advent BioServices, a related party which was formerly part of Cognate BioServices and was spun off separately as part of an institutional financing of Cognate. The MSA provides for manufacturing of DCVax-L products at an existing facility in London. The MSA is structured in the same manner as the Company’s prior agreements with Cognate BioServices. The MSA provides for certain payments for achievement of milestones and, as was the case under the prior agreement with Cognate BioServices, the Company is required to pay certain fees for dedicated production capacity reserved exclusively for DCVax production and pay for manufacturing of DCVax-L products for a certain minimum number of patients, whether or not the Company fully utilizes the dedicated capacity and number of patients. The MSA remains in force until five years after the first commercial sales of DCVax-L products pursuant to a marketing authorization, accelerated approval or other commercial approval, unless cancelled. Either party may terminate the MSA on twelve months’ notice, to allow for transition arrangements by both parties. During the notice period services would still be provided. Minimum required payments for this notice period are anticipated to total approximately £4.4 million ($5.3 million). On November 8, 2019, the Company and Advent entered into an Ancillary Services Agreement with an 8-month Term for U.K. Facility Development Activities and Compassionate Use Program Activities. The Ancillary Services Agreement establishes a structure under which Advent develops Statements of Work (“SOWs”) for the U.K. Facility Development Activities and Compassionate Use Program Activities and delivers those SOWs to the Company for review and approval. After an SOW is approved by the Company, Advent will proceed with, or continue, the applicable services and will invoice the Company pursuant to the SOW. Since both the U.K. Facility Development and the Compassionate Use Program involve pioneering and uncertainties in most aspects, the invoicing under the Ancillary Services Agreement is on the basis of costs incurred plus fifteen percent. The Agreement also provides for Statements of Work (SOWs) with operational milestones and related payments. The Ancillary Services Agreement had an original term of eight months, which ended in July 2020. The Company and Advent have entered into a series of modifications which have expanded the milestones to be achieved and extended the term to September 2023. The Company entered into SOW 6 with Advent, which was incorporated into the Ancillary Services Agreement on April 1, 2022 and amended on September 26, 2022. The amended SOW 6 provides for six workstreams that are prerequisites for an application for regulatory approval of DCVax-L, for drafting of key portions of the application, and for obtaining three required licenses for the Sawston facility. The SOW provides for baseline costs and provides for milestone incentives for completion of each of the workstreams, for obtaining regulatory approval of each of the three Sawston licenses, and for the completion of the key portions of an application for product approval. The milestone incentives involve a combination of cash and stock and are not paid until they are achieved and earned, as described in Note 9. German Tax Matter The German tax authorities have audited our wholly owned subsidiary, NW Bio GmbH, for 2013-2015. The NW Bio GmbH submitted substantial documentation to refute certain aspects of the assessments and the German tax authorities agreed in principle with the Company’s proposed revised approach and settlement offer. A final settlement bill was received from the German Tax Authority confirming that only a portion of the original bill was owed, €277,000 (approximately $329,000 ), for corporate taxes, interest, and reduced penalty for the period under audit, which the Company paid on September 2, 2021. The Company also received and paid the final settlement bill from the local authority for trade taxes for the audit period in the amount of €231,000 (approximately $272,000 ). On November 4, 2021, the Company received a letter from the local tax authorities asking for additional late fees of €513,000 (now approximately $535,000 ) on reimbursable withholding taxes that had been waived during the settlement process. On December 8, 2021, the Company appealed the assessment of additional late fees. Additionally, the Company requested that NW Bio GmbH be deregistered from the trade register, as it no longer had current operations. The deregistration was granted effective December 31, 2021. Between January 2022 and July 2022, the Company received tax bills for the corporate and trade taxes for the 2016-2020 tax years that totaled approximately €222,000 (approximately $232,000 ). On July 27, 2022, the Company was informed that the German Tax Authorities were prepared to waive €135,000 (approximately $141,000 ) of the penalties. The Company offered to pay this reduced penalty if an extended payment plan was approved. A response was received dated November 14, 2022 indicating that the tax authority would not be able to grant a further deferral of payment of these penalties. In a letter dated December 27, 2022, the Leipzig tax authority sent letters to the former and current managing directors of NW Bio GmbH giving 30 days to respond to a tax liability questionnaire. The Company currently has accrued for the current amounts owed for these penalties of €377,000 (approximately $403,000 ) as well as for all unpaid taxes as of December 31, 2022. Based on the Company’s current operating state in Germany and the negotiations, the Company believes, based on its evaluation under ASC 740, that the resolution of these tax matters will not likely result in a net material charge to the Company.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2022
Income Taxes
Income Taxes	13. Income Taxes No provision was made for U.S. taxes on undistributed foreign earning as such earnings are considered to be permanently reinvested. It is not practicable to determine the amount of additional tax, if any that might be payable on those earnings if repatriated. The tax effects of temporary differences and tax loss and credit carry forwards that give rise to significant portions of deferred tax assets and liabilities at December 31, 2022 and 2021 are comprised of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2022 As of December 31, 2021 Deferred tax asset ​ ​ ​ ​ ​ ​ Net operating loss carryforward ​ $ 202,525 ​ $ 193,605 Research and development credit carry forwards ​ ​ 17,989 ​ ​ 17,982 Capitalized research and experimental expenditures ​ ​ 9,144 ​ ​ — Stock based compensation and other ​ ​ 18,021 ​ ​ 23,637 Total deferred tax assets ​ ​ 247,679 ​ ​ 235,224 Valuation Allowance ​ ​ (247,679) ​ ​ (235,224) Deferred tax asset, net of allowance ​ $ — ​ $ — ​ The Company has identified the United States, Maryland, Germany and United Kingdom as significant tax jurisdictions. The Company’s U.S. net operating loss (“NOL”) carryforwards for tax purposes as of December 31, 2022, are approximately $709.9 million. Unused NOL carryforwards from years prior to 2018 of $527.4 million will begin to expire in 2021 through 2037. NOL incurred in 2018 and later amount to $182.5 million and shall carryforward indefinitely. NOL carryforwards are generally available to offset future taxable income; however, the utilization of NOL may be limited under the Internal Revenue Code Section 382 as a result of changes in ownership of the Company’s stock over the loss periods and prior to utilization of the carryforwards, and such limitation could be material. The Company also has approximately $18.0 million in research and development tax credits available to offset federal income tax in future periods. If unused, these credits expire through 2037. The Company’s NOL carryforwards for foreign tax purposes as of December 31, 2022 are $39.7 million. NOL in the United Kingdom and Germany of $21.4 million and $17.9 million respectively do not expire over time. NOL in the Netherlands of $0.4 million will begin to expire in 2025 through 2032. The Company’s tax years are still open under statute from 2017 to present, although NOL carryovers from prior tax years are subject to examination and adjustments to the extent utilized in future years. In assessing the realization of deferred tax assets, management considers whether it is more likely than not that some portion or all of the deferred tax assets will be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the period in which those temporary differences become deductible. Management considers the scheduled reversal of deferred tax liabilities, projected future taxable income and taxing strategies in making this assessment. In case the deferred tax assets will not be realized in future periods, the Company has provided a valuation allowance for the full amount of the deferred tax assets at December 31, 2022 and 2021. The expected tax expense (benefit) based on the U.S. federal statutory rate is reconciled with actual tax expense (benefit) as follow (dollars in thousands): ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2022 As of December 31, 2021 Statutory federal income tax rate 21.0 % 21.0 % State taxes, net of federal tax benefit 4.6 % (2.0) % Tax rate differential on foreign income (0.2) % 0.1 % Derivative gain or loss (5.2) % (28.0) % Expiration of net operating losses (2.6) % 3.9 % Other permanent items and true ups (6.0) % 0.1 % R&D Credit 0.0 % 0.3 % Change in rate 0.1 % 0.0 % Change in valuation allowance (11.7) % 4.6 % Income tax provision (benefit) 0.0 % 0.0 % ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2022 As of December 31, 2021 Federal ​ ​ Current ​ $ — ​ $ — Deferred ​ (8,868) ​ (5,765) State ​ ​ ​ ​ Current ​ — ​ — Deferred ​ (3,097) ​ (1,975) Foreign ​ ​ ​ ​ Current ​ ​ ​ ​ Deferred ​ (489) ​ (599) Change in valuation allowance ​ 12,454 ​ 8,339 Income tax provision (benefit) ​ $ — ​ $ — ​ ASC 740 prescribes a recognition threshold and a measurement attribute for the financial statement recognition and measurement of tax positions taken or expected to be taken in a tax return. For those benefits to be recognized, a tax position must be more-likely-than-not to be sustained upon examination by taxing authorities. As of December 31, 2022, 2021, and 2020, there were no uncertain tax positions. The Company’s policy for recording interest and penalties associated with uncertain tax positions is to record such expense as a component of income tax expense. There were no amounts accrued for penalties or interest during the year ended December 31, 2022, 2021 and 2020. Management is currently unaware of any issues under review that could result in significant payments, accruals or material deviations from its position

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2022
Subsequent Events
Subsequent Events	14. Subsequent Events On January 9, 2023, the Company filed a Certificate of Amendment of its Seventh Amended and Restated Certificate of Incorporation (the “Certificate of Amendment”) with the Secretary of the State of Delaware, which effected an increase in the Company’s authorized shares of common stock, from 1,200,000,000 to 1,700,000,000, par value $0.001 per share. During the period from January 1 to February 24, 2023, the Company received an additional $2.5 million through equity subscriptions and warrant exercises. Between January and February 2023, the Company entered into various Subscription Agreements (the “Series C Subscription Agreements”) with certain investors (the “Series C Investors”). Pursuant to the Series C Subscription Agreements, the Company issued to the Series C Investors an aggregate of 146,948 shares of the Company’s Series C Convertible Preferred Stock, par value $0.001 per share (the “Series C Shares”) for proceeds of approximately $2.4 million. Each Series C Preferred share is convertible to 25 common shares at the option of the holder approximate 15 days after the effective date of purchase. Between January and February 2023, 0.3 million shares of common stock were issued upon warrant exercises for proceeds of approximately $0.1 million. During January 2023, the Company issued approximately 3.4 million shares of common stock to certain lenders in lieu of cash payments on $2.1 million outstanding debt, including $0.1 million interest. Between January and February 2023, the Company issued 43,401 share of Series C preferred stock in lieu of cash payments of $0.7 million of outstanding notes, including $0.1 million accrued interest. During January 2023, certain options holders elected to exercise some of their options pursuant to cashless exercise formulas. The Company issued approximately 0.6 million shares of common stock for exercise of 1.1 million options at exercise prices between $0.34 and $0.35. On February 15, 2023, the Company issued 150,000 shares of common stock upon conversion of 6,000 shares of Series C preferred stock. During February 2023, the Company extended approximate 37.7 million warrants with maturity dates through March 15, 2023 in order to finalize ongoing financing transactions. The holders of these 37.7 million warrants had cash deposit of approximately $2.6 million in December 2022, which was recognized as a cash advance as of December 31, 2022 on the Company’s consolidated balance sheet.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2022
Summary of Significant Accounting Policies
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements of the Company were prepared in accordance with generally accepted accounting principles in the U.S. (“U.S. GAAP”) and include the assets, liabilities, revenues and expenses of the wholly owned subsidiaries in Germany, United Kingdom and Netherlands. All intercompany transactions and accounts have been eliminated in consolidation.
Consolidation	Consolidation The Company’s policy is to consolidate all entities in which it can vote a majority of the outstanding voting stock. In addition, the Company consolidates entities that meet the definition of a variable interest entity (“VIE”) for which the Company is the primary beneficiary, if any. The primary beneficiary is the party who has the power to direct the activities of a VIE that most significantly impact the entity’s economic performance and who has an obligation to absorb losses of the entity or a right to receive benefits from the entity that could potentially be significant to the VIE. As of December 31, 2022 and 2021, the Company did not consolidate any VIE’s as the Company has concluded that it is not the primary beneficiary.
Use of Estimates	Use of Estimates In preparing consolidated financial statements in conformity with U.S. GAAP, management is required 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, as well as the reported amounts of expenses during the reporting period. Due to inherent uncertainty involved in making estimates, actual results reported in future periods may be affected by changes in these estimates. On an ongoing basis, the Company evaluates its estimates and judgments, including valuing equity securities in share-based payment arrangements, estimating the fair value of financial instruments recorded as derivative liabilities, useful lives of depreciable assets and whether impairment charges may apply. The Company bases its estimates on historical experience and on various other assumptions that it believes to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities and the reported amounts of revenues and expenses that are not readily apparent from other sources. Actual results could differ from those estimates, particularly given the significant social and economic disruptions and uncertainties associated with the ongoing coronavirus pandemic (“COVID-19”) and the COVID-19 control responses.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments that potentially subject the Company to concentration of credit risk consist of cash accounts in a financial institution, which at times may exceed the Federal depository insurance coverage (“FDIC”) of $250,000. As of December 31, 2022, of the total $7.0 million in cash and cash equivalents, $0.4 million was held by foreign subsidiaries. As of December 31, 2021, of the total $15.2 million in cash and cash equivalents, $0.5 million was held by foreign subsidiaries. The Company had not experienced losses on these accounts and management believes the Company is not exposed to significant risks on such accounts.
Property, Plant and Equipment	Property, Plant and Equipment Property and equipment are stated at cost. Depreciation and amortization are provided for using straight-line methods, in amounts sufficient to charge the cost of depreciable assets to operations over their estimated service lives. Repairs and maintenance costs are charged to operations as incurred. Costs for capital assets not yet placed into service are capitalized as construction in progress on the consolidated balance sheets and will be depreciated once placed into service. In October 2021, approval was received from the UK Human Tissue Authority (“HTA”) of a license for collection and processing of human cells and tissues for medical purposes at the Company’s Sawston, UK facility. In December 2021, approval was received from the UK Medicines and Healthcare Products Regulatory Agency (“MHRA”) of a license for manufacture at the Sawston facility of GMP (clinical grade) cell therapy products for compassionate use and clinical trials. All costs associated with the facility buildout (Phase 1A) were reclassified from construction in progress to leasehold improvements, and the costs began to be amortized over the estimated useful life of the asset and/or leasehold lease. During 2022, the Company the Company commenced the next phase of the Sawston facility buildout: Phase 1B. The Company incurred additional construction works related to Phase 1B build out during the year ended December 31, 2022. Phase 1B is expected to be completed and placed in use by approximately the end of Q2 2023. Those costs were classified as construction in progress on the consolidated balance sheet as of December 31, 2022. The Company assesses its long-lived assets for impairment whenever facts and circumstances indicate that the carrying amounts may not be fully recoverable. To analyze recoverability, the Company projects undiscounted net future cash flows over the remaining lives of such assets. If these projected undiscounted net future cash flows are less than the carrying amounts, an impairment loss would be recognized, resulting in a write-down of the assets with a corresponding charge to earnings. The impairment loss is measured based upon the difference between the carrying amounts and the fair values of the assets.
Goodwill and Intangible Assets	Goodwill and Intangible Assets Goodwill is the excess of purchase price over the fair value of identified net assets of businesses acquired. The Company’s intangible asset with an indefinite life is related to in-process research and development (“IPR&D”) programs acquired in the Flaskworks Acquisition, as the Company expects future research and development on these programs to provide the Company with substantial benefit for a period that extends beyond the foreseeable horizon. Intangible assets with indefinite useful lives are measured at their respective fair values as of the acquisition date. The Company does not amortize goodwill and intangible assets with indefinite useful lives. Intangible assets related to IPR&D projects are considered to be indefinite lived until the completion or abandonment of the associated R&D efforts. If and when development is complete, which generally occurs if and when regulatory approval to market a product is obtained, the associated assets would be deemed finite lived and would then be amortized based on their respective estimated useful lives at that point in time. The Company has one operating segment and one reporting unit. The Company reviews goodwill and indefinite-lived intangible assets at least annually for possible impairment. Goodwill and indefinite-lived intangible assets are reviewed for possible impairment between annual tests if an event occurs or circumstances change that would more likely than not reduce the fair value of the reporting unit or the indefinite-lived intangible assets below their carrying values. No impairment charge was recognized for the year ended December 31, 2022 and 2021.
Fair Value of Financial Instruments	Fair Value of Financial Instruments ASC 820, Fair Value Measurements, provides guidance on the development and disclosure of fair value measurements. Under this accounting guidance, fair value is defined as 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 at the measurement date. 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. The accounting guidance classifies fair value measurements in one of the following three categories for disclosure purposes: Level 1: Quoted prices in active markets for identical assets or liabilities. Level 2: Inputs other than Level 1 prices for similar assets or liabilities that are directly or indirectly observable in the marketplace. Level 3: Unobservable inputs which are supported by little or no market activity and values determined using pricing models, discounted cash flow methodologies, or similar techniques, as well as instruments for which the determination of fair value requires significant judgment or estimation. The Company accounts for the issuance of common stock purchase warrants issued in connection with the equity offerings in accordance with the provisions of ASC 815, Derivatives and Hedging (“ASC 815”). The Company classifies as equity any contracts that (i) require physical settlement or net-share settlement or (ii) gives the Company a choice of net-cash settlement or settlement in its own shares (physical settlement or net-share settlement). The Company accounts for certain common stock warrants outstanding as a liability at fair value and adjusts the instruments to fair value at each reporting period. This liability is subject to re-measurement at each balance sheet date until exercised, and any change in fair value is recognized in its Consolidated Statements of Operations and Comprehensive Loss. The fair value of the warrants issued by the Company has been estimated using Monte Carlo simulation and or a Black Scholes model. The warrant liabilities are valued using Level 3 valuation inputs (see Note 4).
Embedded Conversion Features	Embedded Conversion Features The Company evaluates embedded conversion features within convertible debt instruments to determine whether the embedded conversion feature(s) should be bifurcated from the host instrument and accounted for as a derivative at fair value with changes in fair value recorded in the Statement of Operations. If the conversion feature does not require recognition of a bifurcated derivative, the convertible debt instrument is evaluated for consideration of any beneficial conversion feature (“BCF”) requiring separate recognition. When the Company records a BCF, the intrinsic value of the BCF is recorded as a debt discount against the face amount of the respective debt instrument (offset to additional paid-in capital) and amortized to interest expense over the life of the debt.
Derivative Financial Instruments	Derivative Financial Instruments The Company has derivative financial instruments that are not hedges and do not qualify for hedge accounting. Changes in the fair value of these instruments are recorded in other income (expense), on a net basis in the Consolidated Statements of Operations and Comprehensive Loss.
Contingent payable derivative liability	Contingent payable derivative liability During the year ended December 31, 2019, the Company entered into a settlement agreement with Cognate BioServices, resolving past matters and providing for the restart of DCVax®-Direct Production. As part of this overall settlement, the Company also provided a contingent note payable (the “Contingent Payable Derivative”) of $10.0 million, which is only payable upon the Company’s first financing after DCVax product approval in or outside the U.S. If such product approval has not been obtained by the seventh anniversary of the agreement, such Contingent Payable Derivative will expire without becoming payable. On a quarterly basis, management makes estimates for key performance milestones and uses the expected dates as the inputs for valuation. The fair value of the Contingent Payable Derivative has been estimated using Monte Carlo simulation, which are valued using Level 3 valuation inputs.
Leases	Leases The Company recognizes a lease asset for its right to use the underlying asset and a lease liability for the corresponding lease obligation. The Company determines whether an arrangement is or contains a lease at contract inception. Operating leases with a duration greater than one year are included in right-of-use assets, lease liabilities, and lease liabilities, net of current portion in the Company’s consolidated balance sheets. Right-of-use assets and liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. In determining the net present value of lease payments, the Company uses its incremental borrowing rate based on the information available at the lease commencement date. The incremental borrowing rate represents the interest rate the Company would incur at lease commencement to borrow an amount equal to the lease payments on a collateralized basis over the term of a lease. The Company considers a lease term to be the non-cancelable period that it has the right to use the underlying asset. The operating lease right-of-use assets also include any lease payments made and exclude lease incentives. Lease expense is recognized on a straight-line basis over the expected lease term. Variable lease expenses are recorded when incurred.
Foreign Currency Translation and Transactions	Foreign Currency Translation and Transactions The Company has operations in the United Kingdom and Netherlands in addition to the U.S. The Company translated its assets and liabilities into U.S. dollars using end of period exchange rates, and revenues and expenses are translated into U.S. dollars using weighted average rates. Foreign currency translation adjustments are reported as a separate component of accumulated other comprehensive income (loss) within stockholders’ equity deficit. The Company converts receivables and payables denominated in other than the Company’s functional currency at the exchange rate as of the balance sheet date. The resulting transaction exchange gains or losses related to intercompany receivable and payables, are included in other income and expense.
Comprehensive Loss	Comprehensive Loss The Company reports comprehensive loss and its components in its consolidated financial statements. Comprehensive loss consists of net loss and foreign currency translation adjustments, affecting stockholders’ equity deficit that, under U.S, GAAP, is excluded from net loss.
Revenue Recognition	Revenue Recognition The Company recognizes revenue in accordance with the terms stipulated under the applicable service contract. In various situations, the Company receives certain credits against invoices for manufacturing of patient treatments by its contract manufacturer. These payments are assessed and recognized in accordance with ASC 606 in the period when the performance obligation has been met.
Accrued Outsourcing Costs	Accrued Outsourcing Costs Substantial portions of our preclinical studies and clinical trials are performed by third-party laboratories, medical centers, contract research organizations and other vendors (collectively “CROs”). These CROs generally bill monthly or quarterly for services performed, or bill based upon milestones achieved. For clinical studies, expenses are accrued when services are performed. The Company monitors patient enrollment, the progress of clinical studies and related activities through internal reviews of data that is tracked by the CROs under contractual arrangements, correspondence with the CROs and visits to clinical sites.
Research and Development Costs	Research and Development Costs Research and development costs are charged to operations as incurred and consist primarily of clinical trial related costs (including costs for collection, validation and analysis of trial results), related party manufacturing costs, consulting costs, contract research and development costs, clinical site costs and compensation costs.
Income Taxes	Income Taxes The Company evaluates its tax positions and estimates its current tax exposure along with assessing temporary differences that result from different book to tax treatment of items not currently deductible for tax purposes. These differences result in deferred tax assets and liabilities on the Company’s Consolidated Balance Sheets, which are estimated based upon the difference between the financial statement and tax bases of assets and liabilities using the enacted tax rates that will be in effect when these differences reverse. In general, deferred tax assets represent future tax benefits to be received when certain expenses previously recognized in the Company’s Consolidated Statements of Comprehensive Loss become deductible expenses under applicable income tax laws or loss or credit carryforwards are utilized. Accordingly, realization of the Company’s deferred tax assets is dependent on future taxable income against which these deductions, losses and credits can be utilized. The Company must assess the likelihood that the Company’s deferred tax assets will be recovered from future taxable income, and to the extent the Company believes that recovery is not more likely than not, the Company must establish a valuation allowance. Management judgment is required in determining the Company’s provision for income taxes, the Company’s deferred tax assets and liabilities and any valuation allowance recorded against the Company’s net deferred tax assets. Excluding foreign operations, the Company recorded a full valuation allowance at each balance sheet date presented because, based on the available evidence, the Company believes it is more likely than not that it will not be able to utilize all of its deferred tax assets in the future. The Company intends to maintain the full valuation allowance until sufficient evidence exists to support the reversal of the valuation allowance.
Stock-Based Compensation	Stock-Based Compensation The Company measures stock-based compensation to employees, consultants, and Board members at fair value on the grant date of the award. Compensation cost is recognized as expense on a straight-line basis over the requisite service period of the award. For awards that have a performance condition, compensation cost is measured based on the fair value of the award on the grant date, the date performance targets are established, and is expensed over the requisite service period for each separately vesting tranche when achievement of the performance condition becomes probable. The Company assess the probability of the performance conditions being met on a continuous basis. Forfeitures are recognized when they occur. Prior to January 1, 2019, share-based compensation cost for non-employees was re-measured at every reporting period. The Company estimates the fair value of stock or option grants that do not contain market-based vesting conditions using the Black-Scholes option pricing model and the assumptions used in calculating the fair value of stock-based awards represent management’s best estimates and involve inherent uncertainties and the application of management’s judgment. Expected Term Expected Volatility Risk-Free Interest Rate Expected Dividend The Company is also required to make estimates as to the probability of achieving the specific performance conditions. If actual results are not consistent with the Company’s assumptions and judgments used in making these estimates, the Company may be required to increase or decrease compensation expense, which could be material to the Company’s consolidated results of operations.
Debt Extinguishment	Debt Extinguishment The Company accounts for the income or loss from extinguishment of debt by comparing the difference between the reacquisition price and the net carrying amount of the debt being extinguished and recognizes this as gain or loss when the debt is extinguished. The gain or loss from debt extinguishment is recorded in the consolidated statements of operations under “other income (expense)” as loss from extinguishment of convertible debt.
Sequencing	Sequencing The Company adopted a sequencing policy under ASC 815-40-35 whereby in the event that reclassification of contracts from equity to liabilities is necessary pursuant to ASC 815 due to the Company’s inability to demonstrate it has sufficient authorized shares. This was previously the result of certain financial instruments with a potentially indeterminable number of shares and most recently due to the company committing more shares than authorized. While temporary suspensions are in place to keep the potential exercises beneath the number authorized, certain instruments are classified as liabilities, after allocating available authorized shares on the basis of the earliest grant date of potentially dilutive instruments. Pursuant to ASC 815, issuance of stock-based awards to the Company’s employees, nonemployees or directors are not subject to the sequencing policy.
Income (Loss) per Share	Income (Loss) per Share Basic income (loss) per share is computed on the basis of the weighted average number of shares outstanding for the reporting period. Diluted income (loss) per share is computed on the basis of the weighted average number of common shares plus dilutive potential common shares outstanding using the treasury stock method. Diluted weighted average shares reflect the dilutive effect, if any, of potential common shares. To the extent their effect is dilutive, employee equity awards and other commitments to be settled in common stock are included in the calculation of diluted income per share based on the treasury stock method. Potential common shares are excluded from the calculation of dilutive weighted average shares outstanding if their effect would be anti-dilutive at the balance sheet date based on a treasury stock method or due to a net loss.
Recently Adopted Accounting Standards	Recently Adopted Accounting Standards Income Taxes In December 2019, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2019-12, “Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (“ASU 2019-12”), which is intended to simplify various aspects related to accounting for income taxes. ASU 2019-12 removes certain exceptions to the general principles in Topic 740 and also clarifies and amends existing guidance to improve consistent application. This guidance is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020, with early adoption permitted. On January 1, 2021, the Company adopted this standard without any material impact on its consolidated financial statements and related disclosures. Debt 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 simplifies accounting for convertible instruments by removing major separation models required under current GAAP. The ASU removes certain settlement conditions that are required for equity contracts to qualify for the derivative scope exception and it also simplifies the diluted earnings per share calculation in certain areas. This ASU is effective for annual reporting periods beginning after December 15, 2021, including interim periods within those fiscal years. Early adoption was permitted, but no earlier than fiscal years beginning after December 15, 2020. This update permits the use of either the modified retrospective or fully retrospective method of transition. The Company has adopted the new standard as of January 1, 2021 without any material impact on its consolidated financial statements and related disclosures. Modifications or Exchanges of Freestanding Equity-Classified Written Call Options In May 2021, the FASB issued ASU 2021-04, Earnings Per Share (Topic 260), Debt-Modifications and Extinguishments (Subtopic 470-50), Compensation-Stock Compensation (Topic 718), and Derivatives and Hedging-Contracts in Entity’s Own Equity (Subtopic 815-40). This ASU reduces diversity in an issuer’s accounting for modifications or exchanges of freestanding equity-classified written call options (for example, warrants) that remain equity classified after modification or exchange. This ASU provides guidance for a modification or an exchange of a freestanding equity-classified written call option that is not within the scope of another Topic. It specifically addresses: (1) how an entity should treat a modification of the terms or conditions or an exchange of a freestanding equity-classified written call option that remains equity classified after modification or exchange; (2) how an entity should measure the effect of a modification or an exchange of a freestanding equity-classified written call option that remains equity classified after modification or exchange; and (3) how an entity should recognize the effect of a modification or an exchange of a freestanding equity-classified written call option that remains equity classified after modification or exchange. This ASU will be effective for all entities for fiscal years beginning after December 15, 2021. An entity should apply the amendments prospectively to modifications or exchanges occurring on or after the effective date of the amendments. Early adoption is permitted, including adoption in an interim period. On January 1, 2022, the Company adopted this standard without any material impact on the Company’s consolidated financial statements or disclosures. ​ Recently Issued Accounting Standards Not Yet Adopted Fair Value Measurement of Equity Securities Subject to Contractual Sale Restrictions In June 2022, the FASB issued ASU 2022-03, ASC Subtopic 820 “Fair Value Measurement of Equity Securities Subject to Contractual Sale Restrictions”. The FASB is issuing this Update (1) to clarify the guidance in Topic 820, Fair Value Measurement, when measuring the fair value of an equity security subject to contractual restrictions that prohibit the sale of an equity security, (2) to amend a related illustrative example, and (3) to introduce new disclosure requirements for equity securities subject to contractual sale restrictions that are measured at fair value in accordance with Topic 820. For public business entities, the amendments in this Update are effective for fiscal years beginning after December 15, 2023, and interim periods within those fiscal years. Early adoption is permitted for both interim and annual financial statements that have not yet been issued or made available for issuance. The Company is still evaluating the impact of this pronouncement on the consolidated financial statements.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2022
Fair Value Measurements
Schedule of fair value assets and liabilities measured on recurring basis	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair value measured at December 31, 2022 ​ ​ ​ Quoted prices in active Significant other Significant ​ ​ Fair value at ​ markets ​ observable inputs ​ unobservable inputs ​ ​ December 31, 2022 ​ (Level 1) ​ (Level 2) ​ (Level 3) Warrant liability ​ $ 80,559 ​ $ — ​ $ — ​ $ 80,559 Embedded redemption option ​ ​ 807 ​ ​ — ​ ​ — ​ ​ 807 Contingent payable derivative liability ​ ​ 8,668 ​ ​ — ​ ​ — ​ ​ 8,668 Share liability ​ 678 ​ — ​ — ​ 678 Total fair value ​ $ 90,712 ​ $ — ​ $ — ​ $ 90,712 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair value measured at December 31, 2021 ​ ​ ​ Quoted prices in active Significant other Significant ​ ​ Fair value at ​ markets ​ observable inputs ​ unobservable inputs ​ ​ December 31, 2021 ​ (Level 1) ​ (Level 2) ​ (Level 3) Warrant liability ​ $ 106,784 ​ $ — ​ $ — ​ $ 106,784 Embedded redemption option ​ 988 ​ — ​ — ​ 988 Contingent payable derivative liability ​ 8,232 ​ — ​ — ​ 8,232 Total fair value ​ $ 116,004 ​ $ — ​ $ — ​ $ 116,004 ​
Schedule of changes in Level 3 liabilities measured at fair value	The following table presents changes in Level 3 liabilities measured at fair value for the years ended December 31, 2022 and 2021. Both observable and unobservable inputs were used to determine the fair value of positions that the Company has classified within the Level 3 category. Unrealized gains and losses associated with liabilities within the Level 3 category include changes in fair value that were attributable to both observable (e.g., changes in market interest rates) and unobservable (e.g., changes in unobservable long- dated volatilities) inputs (in thousands). ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Warrant ​ Embedded ​ Contingent Payable ​ Share ​ ​ ​ ​ Liability Redemption Option Derivative Liability Liability Total Balance - January 1, 2021 ​ $ 354,972 ​ $ 2,507 ​ $ 8,275 ​ $ — ​ $ 365,754 Additional warrant liability ​ ​ 1,785 ​ ​ — ​ ​ — ​ ​ — ​ ​ 1,785 Additional embedded redemption option ​ ​ — ​ ​ 947 ​ ​ — ​ ​ — ​ ​ 947 Reclassification of warrant liabilities ​ ​ (11,210) ​ ​ — ​ ​ — ​ ​ — ​ ​ (11,210) Debt conversion ​ ​ — ​ ​ (1,925) ​ ​ — ​ ​ — ​ ​ (1,925) Change in fair value ​ ​ (238,763) ​ ​ (541) ​ ​ (43) ​ ​ — ​ ​ (239,347) Balance – December 31, 2021 ​ ​ 106,784 ​ ​ 988 ​ ​ 8,232 ​ ​ — ​ ​ 116,004 Additional warrant liability ​ ​ 184 ​ ​ 7 ​ ​ — ​ ​ — ​ ​ 191 Additional share liability ​ ​ — ​ ​ — ​ ​ — ​ ​ 711 ​ ​ 711 Debt redemption ​ ​ — ​ ​ (213) ​ ​ — ​ ​ — ​ ​ (213) Reclassification of warrant liabilities ​ ​ (51,769) ​ ​ — ​ ​ — ​ ​ — ​ ​ (51,769) Change in fair value ​ ​ 25,360 ​ ​ 25 ​ ​ 436 ​ ​ (33) ​ ​ 25,788 Balance - December 31, 2022 ​ $ 80,559 ​ $ 807 ​ $ 8,668 ​ $ 678 ​ $ 90,712 ​
Schedule of Company's warrant liabilities and embedded conversion feature that are categorized within Level 3 of the fair value hierarchy	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2022 ​ Warrant Share ​ Contingent Payable ​ ​ Liability ​ Liability ​ Derivative Liability Strike price ​ $ 0.31 ​ $ 0.78 * $ 0.78 * Contractual term (years) ​ 1.5 ​ ​ 0.1 ​ 0.6 ​ Volatility (annual) ​ 86 % ​ 76 % 77 % Risk-free rate ​ 4.3 % ​ 2.0 % 4.8 % Dividend yield (per share) ​ 0 % ​ 0 % 0 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2021 ​ ​ Warrant ​ Contingent Payable ​ ​ Liability Derivative Liability Strike price ​ $ 0.30 ​ $ 0.70 * Contractual term (years) ​ 1.0 ​ 1.6 ​ Volatility (annual) ​ 90 % 72 % Risk-free rate ​ 0.1 % 0.6 % Dividend yield (per share) ​ 0 % 0 % * Contingent payable derivative liability based on stock price as of December 31, 2022 and 2021.

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2022
Stock-Based Compensation
Schedule of stock based compensation	The following table summarizes total stock-based compensation expense recognized for the years ended December 31, 2022, 2021 and 2020 (in thousands). ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the years ended ​ ​ December 31, ​ 2022 2021 2020 Research and development ​ $ 1,918 ​ $ 7,607 ​ $ 19,792 Research and development - Advent ​ ​ ​ ​ ​ ​ ​ ​ ​ Milestones achieved (1) ​ ​ 5,870 ​ ​ — ​ ​ — Future milestones (2) ​ ​ 3,573 ​ ​ — ​ ​ — General and administrative ​ ​ 937 ​ 7,964 ​ 32,163 Total stock-based compensation expense ​ $ 12,298 ​ $ 15,571 ​ $ 51,955 ​ The related party amounts were for milestone incentives that either were earned or are deemed probable to be achieved in the future and become issuable at that time (as detailed below in Restricted Stock Awards). (1) During the year ended December 31, 2022, for 8 one-time milestones that were earned, the Company recognized and expensed approximately $5.9 million for 7.5 million shares. (2) For 2 further one-time milestones that are anticipated to be achieved and earned in the future, the Company recognized and expensed (but did not issue shares for) the pro-rata portion on the remaining potential milestone stock awards during the year ended December 31, 2022, of $3.5 million. During the year ended December 31, 2022, the Company reversed approximately $1.4 million and $0.3 million of stock-based compensation expense in research and development and general and administrative, respectively, which were related to the cancellation of certain unvested performance-based awards.
Schedule of weighted average assumptions for stock options modification	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the years ended ​ ​ December 31, ​ 2022 2021 2020 Exercise price ​ $ 0.65 ​ $ 0.92 ​ $ 0.26 ​ Expected term (years) ​ ​ 3.9 ​ 5.3 ​ 5.2 ​ Expected stock price volatility ​ ​ 99 % 97 % 98 % Risk-free rate ​ ​ 3.3 % ​ 1 % ​ 0 % Dividend yield (per share) ​ ​ 0 % 0 % 0 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Post Modification Pre Modification Exercise price ​ $ 0.23 ​ $ 0.23 ​ Expected term (years) ​ 4.3 ​ 4.0 ​ Expected stock price volatility ​ 97 % 97 % Risk-free rate of interest ​ 0 % 0 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Post Modification Pre Modification Exercise price ​ $ 0.22 ​ $ 0.22 ​ Expected term (years) ​ 5.3 ​ 4.7 ​ Expected stock price volatility ​ 96 % 97 % Risk-free rate of interest ​ 0 % 0 % ​
Schedule of stock option activity	The following table summarizes stock option activity under the Company’s option plans (including awards to key external consultants and vendors in addition to internal parties) during the years ended December 31, 2022, 2021 and 2020 (in thousands, except per share number): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ ​ Weighted ​ Average ​ ​ ​ ​ ​ ​ ​ Average ​ Remaining ​ Total ​ ​ Number of ​ Exercise ​ Contractual ​ Intrinsic ​ ​ Shares ​ Price ​ Life (in years) ​ Value Outstanding as of January 1, 2020 104,659 ​ $ 0.24 8.4 ​ $ — Granted (Approved 2018-2020) (1) ​ 208,525 ​ ​ 0.37 (2) 10.0 ​ ​ — Cashless exercise ​ (94) ​ ​ 0.34 ​ — ​ ​ — Forfeited/expired ​ (4,250) ​ ​ 0.22 ​ — ​ ​ — Outstanding as of December 31, 2020 308,840 ​ 0.33 ​ 8.9 ​ 372,219 Granted 910 ​ 0.92 8.6 ​ — Cash exercised (183) ​ ​ 0.25 — ​ ​ — Cashless exercise ​ (4,720) ​ ​ 0.25 ​ — ​ ​ — Outstanding as of December 31, 2021 ​ 304,847 ​ ​ 0.33 ​ 8.0 ​ ​ 114,803 Granted (3) ​ 8,005 ​ ​ 0.65 ​ 4.4 ​ ​ — Cashless exercised ​ (8,187) ​ ​ 0.27 ​ — ​ ​ — Forfeited/expired ​ (3,402) ​ ​ 0.88 ​ — ​ ​ — Outstanding as of December 31, 2022 ​ 301,263 ​ $ 0.34 ​ 7.0 ​ $ 135,225 Options vested (4) 282,271 ​ $ 0.33 7.0 ​ $ 127,951 (1) The options granted during the year ended December 31, 2020 included options already approved at various times during the three years 2018 - 2020 but not issued until Q3 2020, and also included options that will vest for performance and milestones going forward over the next two years. The options included awards to key external consultants and vendors in addition to internal parties. (2) The weighted average exercise price of the Q3 2020 options was initially $0.25 . However subsequently, the exercise price was amended to a weighted average exercise price of $0.36 . (3) Awards granted to Flaskworks employees and consultants. (4) Approximately 83.3 million options were not exercisable until January 12, 2023, and 153.3 million options are not exercisable until at least April 30, 2023. The existing options and warrants held by Ms. Linda Powers, the Company’s Chief Executive Officer, and Mr. Leslie Goldman, the Company’s Senior Vice President, General Counsel are subject to a voluntary blocking agreement under which they cannot be exercised except upon at least 61 days’ prior notice to the Company.

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	12 Months Ended
	Dec. 31, 2022
Property, Plant and Equipment
Schedule of property and equipment	Property, plant and equipment consist of the following at December 31, 2022 and 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, December 31, Estimated ​ ​ 2022 ​ 2021 ​ Useful Life Leasehold improvements ​ $ 13,070 ​ $ 13,910 Lesser of lease term or estimated useful life Office furniture and equipment ​ 300 ​ 310 3-5 years Computer and manufacturing equipment and software ​ 2,238 ​ 1,799 3-5 years Land in the United Kingdom ​ ​ 82 ​ ​ 92 ​ NA ​ ​ 15,690 ​ 16,111 ​ NA Less: accumulated depreciation ​ (2,272) ​ (1,084) Total property, plant and equipment, net ​ $ 13,418 ​ $ 15,027 ​ ​ ​ ​ ​ ​ ​ ​ ​ Construction in progress ​ $ 2,028 ​ $ — ​

Notes Payable (Tables)

Notes Payable (Tables)	12 Months Ended
	Dec. 31, 2022
Notes Payable
Schedule of outstanding debt	The following tables summarize outstanding debt as of December 31, 2022 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Stated ​ ​ ​ ​ ​ ​ Embedded ​ ​ ​ ​ ​ ​ ​ Interest ​ Conversion ​ ​ ​ ​ Remaining ​ Redemption ​ Carrying ​ ​ Maturity Date ​ Rate ​ Price ​ Face Value ​ Debt Discount ​ Option ​ Value Short term convertible notes payable ​ ​ ​ ​ ​ ​ ​ 6% unsecured ​ Due ​ 6 % $ 3.09 ​ $ 135 ​ $ — ​ $ — ​ $ 135 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 135 ​ ​ — ​ ​ — ​ ​ 135 Short term notes payable ​ ​ ​ ​ ​ ​ ​ ​ ​ 8% unsecured ​ Various ​ 8 % N/A ​ 14,540 ​ (1,300) ​ 807 ​ 14,047 9% unsecured ​ Various ​ 9 % N/A ​ 793 ​ — ​ — ​ 793 12% unsecured ​ On Demand ​ 12 % N/A ​ 563 ​ — ​ — ​ 563 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 15,896 ​ (1,300) 807 ​ ​ 15,403 Long term notes payable ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 8% unsecured ​ 7/26/2024 ​ 8 % N/A ​ 5,505 ​ (432) ​ — ​ 5,073 6% secured ​ 3/25/2025 ​ ​ 6 % ​ N/A ​ ​ 918 ​ — — ​ ​ 918 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 6,423 ​ ​ (432) ​ ​ — ​ ​ 5,991 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Ending balance as of December 31, 2022 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 22,454 ​ $ (1,732) ​ $ 807 ​ $ 21,529 ​ The following tables summarize outstanding debt as of December 31, 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Stated ​ ​ ​ ​ ​ ​ Embedded ​ ​ ​ ​ ​ ​ Interest ​ Conversion ​ ​ ​ ​ Remaining ​ Redemption ​ Carrying ​ ​ Maturity Date ​ Rate ​ Price ​ Face Value ​ Debt Discount ​ Option ​ Value Short term convertible notes payable ​ ​ ​ ​ ​ ​ ​ 6% unsecured ​ Due ​ 6 % $ 3.09 ​ $ 135 ​ $ — ​ $ — ​ $ 135 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 135 ​ ​ — ​ — ​ 135 Short term notes payable ​ ​ ​ ​ ​ ​ ​ 8% unsecured ​ Various ​ 8 % N/A ​ 2,320 ​ (118) ​ — ​ 2,202 9% unsecured ​ Various ​ 9 % N/A ​ 4,232 ​ (80) ​ 47 ​ 4,199 12% unsecured ​ On Demand ​ 12 % N/A ​ 703 ​ — ​ — ​ 703 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 7,255 ​ (198) 47 ​ 7,104 Long term notes payable ​ ​ ​ ​ ​ ​ ​ ​ 1% unsecured ​ Various ​ 1 % N/A ​ 433 ​ — ​ — ​ 433 8% unsecured ​ 9/22/2023 ​ 8 % N/A ​ 25,938 ​ (3,638) ​ 941 ​ 23,241 6% secured ​ 3/25/2025 ​ 6 % N/A ​ 1,482 ​ — ​ — ​ 1,482 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 27,853 ​ (3,638) 941 ​ 25,156 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Ending balance as of December 31, 2021 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 35,243 ​ $ (3,836) ​ $ 988 ​ $ 32,395 ​
Schedule of total interest expenses related to outstanding debt	The following table summarizes total interest expenses related to outstanding debt for the years ended December 31, 2022, 2021 and 2020, respectively (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the years ended ​ ​ December 31, ​ 2022 2021 2020 Interest expenses related to outstanding notes: ​ ​ ​ ​ ​ ​ Contractual interest ​ $ 2,890 ​ $ 2,347 ​ $ 1,231 Amortization of debt discount ​ 2,771 ​ 2,301 ​ ​ 2,891 Total interest expenses related to outstanding notes ​ 5,661 ​ 4,648 ​ ​ 4,122 Interest expenses related to outstanding notes to related parties: ​ ​ ​ ​ ​ ​ Contractual interest ​ — ​ — ​ ​ 20 Amortization of debt discount ​ — ​ — ​ ​ 122 Total interest expenses related to outstanding notes to related parties ​ — ​ — ​ ​ 142 Interest expenses related to forbearance of debt to related parties ​ ​ — ​ ​ — ​ ​ 4,270 Interest expenses related to payables to Advent BioServices ​ ​ — ​ ​ 140 ​ ​ — Other interest expenses ​ 407 ​ 223 ​ ​ 10 Total interest expense ​ $ 6,068 ​ $ 5,011 ​ $ 8,544 ​
Schedule of principal amounts of the Company's debt obligations	The following table summarizes the principal amounts of the Company’s debt obligations as of December 31, 2022 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Payment Due by Period ​ ​ ​ ​ ​ Less than ​ 1 to 2 ​ 3 to 5 ​ Total 1 Year Years Years Short term convertible notes payable ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 6% unsecured ​ $ 135 ​ $ 135 ​ $ — ​ $ — Short term notes payable ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 8% unsecured ​ ​ 14,540 ​ ​ 14,540 ​ ​ — ​ ​ — 9% unsecured ​ ​ 793 ​ ​ 793 ​ ​ ​ ​ ​ ​ 12% unsecured ​ ​ 563 ​ ​ 563 ​ ​ — ​ ​ — Long term notes payable ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 8% unsecured ​ ​ 5,505 ​ ​ — ​ ​ 5,505 ​ ​ — 6% secured ​ ​ 918 ​ ​ — ​ ​ — ​ ​ 918 Total ​ $ 22,454 ​ $ 16,031 ​ $ 5,505 ​ $ 918

Net (Loss) Earnings per Share_2

Net (Loss) Earnings per Share Applicable to Common Stockholders (Tables)	12 Months Ended
	Dec. 31, 2022
Net (Loss) Earnings per Share Applicable to Common Stockholders
Schedule of computation of earnings (loss) per share	The following table sets forth the computation of earnings (loss) per share for the years ended December 31, 2022, 2021 and 2020 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the years ended ​ ​ December 31, ​ ​ 2022 ​ 2021 ​ 2020 Net (loss) earnings - basic ​ $ (105,032) ​ $ 179,126 ​ $ (529,821) Reversal of gain due to change in fair value of warrant liability ​ — ​ (239,347) ​ — Net loss - diluted ​ ​ (105,032) ​ $ (60,221) ​ $ (529,821) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average shares outstanding - basic ​ 1,015,852 ​ 873,517 ​ 725,129 Diluted shares- Options ​ — ​ 38,496 ​ — Diluted shares- Warrants ​ — ​ 95,780 ​ — Convertible notes and interest ​ — ​ 76 ​ — Weighted average shares outstanding - diluted ​ 1,015,852 ​ 1,007,869 ​ 725,129 ​
Schedule of antidilutive securities were not included in the diluted net earnings (loss) per share	The following securities were not included in the diluted earnings (loss) per share calculation because their effect was anti-dilutive as of the periods presented (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ For the years ended ​ ​ December 31, ​ 2022 2021 2020 Series C convertible preferred stock ​ 35,384 ​ — ​ — Common stock options ​ 301,263 ​ 266,350 ​ 308,840 Common stock warrants ​ 141,048 ​ 129,689 ​ 328,979 Contingently issuable warrants ​ — ​ — ​ 2,774 Convertible notes and accrued interest ​ 78 — ​ 2,617 Potentially dilutive securities ​ 477,773 ​ 396,039 ​ 643,210

Related Party Transactions (Tab

Related Party Transactions (Tables)	12 Months Ended
	Dec. 31, 2022
Related Party Transactions
Schedule of outstanding unpaid accounts payable and accrued expenses held by related parties	As of December 31, 2022, there were outstanding unpaid accounts payable and accrued expenses owed to Advent as summarized in the following table (in thousands). These unpaid amounts are part of the Related Party expenses reported in the above section. The 2021 balance also included certain expenses incurred in prior periods. ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 December 31, 2021 Advent BioServices - amount invoiced but unpaid ​ $ 1,844 ​ $ 3,046 Advent BioServices - amount accrued and unpaid ​ ​ 4,736 ​ ​ — Accounts payable and accrued expenses owed to Advent BioServices ​ $ 6,580 ​ $ 3,046 ​

Stockholders' Deficit (Tables)

Stockholders' Deficit (Tables)	12 Months Ended
	Dec. 31, 2022
Stockholders' Deficit
Schedule of warrant activity	The following is a summary of warrant activity for the years ended December 31, 2022, 2021 and 2020 (in thousands, except per share data): ​ ​ ​ ​ ​ ​ ​ ​ ​ Number of Weighted Average Remaining ​ ​ Warrants ​ Exercise Price ​ Contractual Term Outstanding as of January 1, 2020 359,473 ​ $ 0.27 1.42 Warrants granted 88,658 ​ 0.22 ​ Contingently issuable warrants (1) 2,774 ​ 1.48 ​ Warrants exercised for cash (47,511) ​ 0.29 ​ Cashless warrants exercise (8,631) ​ ​ 0.22 ​ Warrants expired and cancellation ​ (63,010) ​ ​ 0.32 ​ ​ Outstanding as of December 31, 2020 331,753 ​ $ 0.28 1.61 Warrants granted 1,209 ​ 1.39 ​ Warrants exercised for cash ​ (86,726) ​ ​ 0.23 ​ ​ Cashless warrants exercise (19,743) ​ 0.22 ​ Warrants expired and cancellation (1,024) ​ ​ 2.95 ​ Outstanding as of December 31, 2021 ​ 225,469 ​ $ 0.30 ​ 0.96 Warrants exercised for cash ​ (46,671) ​ ​ 0.25 ​ ​ Cashless warrants exercise ​ (35,951) ​ ​ 0.23 ​ ​ Warrants expired and cancellation ​ (1,799) ​ ​ 1.58 ​ ​ Outstanding as of December 31, 2022 ​ 141,048 ​ $ 0.31 ​ 1.46 ​

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2022
Commitments and Contingencies.
Schedule of quantitative information about the company's operating leases	The following summarizes quantitative information about the Company’s operating leases (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the Year ended ​ ​ December 31, 2022 ​ U.K U.S Total Lease cost ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating lease cost ​ $ 588 ​ $ 260 ​ $ 848 Short-term lease cost ​ ​ 79 ​ ​ — ​ ​ 79 Variable lease cost ​ ​ — ​ ​ 13 ​ ​ 13 Sub-lease income ​ ​ (145) ​ ​ — ​ ​ (145) Total ​ $ 522 ​ $ 273 ​ $ 795 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other information ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating cash flows from operating leases ​ $ (619) ​ $ (290) ​ $ (909) Weighted-average remaining lease term – operating leases ​ ​ 8.5 ​ ​ 1.3 ​ ​ ​ Weighted-average discount rate – operating leases ​ ​ 12 % ​ 12 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the Year ended ​ ​ December 31, 2021 ​ U.K U.S Total Lease cost ​ ​ ​ Operating lease cost ​ $ 653 ​ $ 277 ​ $ 930 Short-term lease cost ​ 51 ​ — ​ 51 Variable lease cost ​ 48 ​ 5 ​ 53 Total ​ $ 752 ​ $ 282 ​ $ 1,034 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other information ​ ​ ​ ​ ​ ​ Operating cash flows from operating leases ​ $ (688) ​ $ (178) ​ $ (866) Weighted-average remaining lease term – operating leases ​ 9.0 ​ 1.8 ​ ​ Weighted-average discount rate – operating leases ​ 12 % 12 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the Year ended ​ ​ December 31, 2020 ​ ​ U.K ​ U.S ​ Total Lease cost ​ ​ ​ Operating lease cost ​ $ 610 ​ $ 330 ​ $ 940 Short-term lease cost ​ 44 ​ — ​ 44 Variable lease cost ​ 45 ​ 20 ​ 65 Total ​ $ 699 ​ $ 350 ​ $ 1,049 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other information ​ ​ ​ ​ ​ ​ Operating cash flows from operating leases ​ $ (661) ​ $ (332) ​ $ (993) Weighted-average remaining lease term – operating leases ​ 9.1 ​ 0.2 ​ Weighted-average discount rate – operating leases ​ 12 % 12 % ​
Schedule of maturities of our operating leases, excluding short-term leases	​ ​ ​ ​ ​ Year ended December 31, 2023 $ 903 Year ended December 31, 2024 ​ ​ 809 Year ended December 31, 2025 ​ ​ 604 Year ended December 31, 2026 ​ ​ 604 Year ended December 31, 2027 ​ ​ 604 Thereafter ​ ​ 6,631 Total ​ ​ 10,155 Less present value discount ​ ​ (5,431) Operating lease liabilities included in the Consolidated Balance Sheet at December 31, 2022 ​ $ 4,724 ​ ​ ​ ​ ​ ​ Year ended December 31, 2023 $ 145 Year ended December 31, 2024 ​ 145 Year ended December 31, 2025 ​ 145 Year ended December 31, 2026 ​ 145 Thereafter ​ 1,740 Total ​ $ 2,320 ​

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2022
Income Taxes
Schedule of Deferred Tax Assets and Liabilities	The tax effects of temporary differences and tax loss and credit carry forwards that give rise to significant portions of deferred tax assets and liabilities at December 31, 2022 and 2021 are comprised of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2022 As of December 31, 2021 Deferred tax asset ​ ​ ​ ​ ​ ​ Net operating loss carryforward ​ $ 202,525 ​ $ 193,605 Research and development credit carry forwards ​ ​ 17,989 ​ ​ 17,982 Capitalized research and experimental expenditures ​ ​ 9,144 ​ ​ — Stock based compensation and other ​ ​ 18,021 ​ ​ 23,637 Total deferred tax assets ​ ​ 247,679 ​ ​ 235,224 Valuation Allowance ​ ​ (247,679) ​ ​ (235,224) Deferred tax asset, net of allowance ​ $ — ​ $ — ​
Schedule of Effective Income Tax Rate Reconciliation	​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2022 As of December 31, 2021 Statutory federal income tax rate 21.0 % 21.0 % State taxes, net of federal tax benefit 4.6 % (2.0) % Tax rate differential on foreign income (0.2) % 0.1 % Derivative gain or loss (5.2) % (28.0) % Expiration of net operating losses (2.6) % 3.9 % Other permanent items and true ups (6.0) % 0.1 % R&D Credit 0.0 % 0.3 % Change in rate 0.1 % 0.0 % Change in valuation allowance (11.7) % 4.6 % Income tax provision (benefit) 0.0 % 0.0 % ​
Schedule of Components of Income Tax Expense (Benefit)	​

Financial Condition, Going Co_2

Financial Condition, Going Concern and Management Plans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Financial Condition, Going Concern and Management Plans
Net loss	$ 105,032	$ (179,126)	$ 529,821
Payments for operating activities	$ 52,800

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Details)	12 Months Ended
	Dec. 31, 2022 USD ($) segment	Dec. 31, 2021 USD ($)
Summary of Significant Accounting Policies
Federal depository insurance coverage	$ 250,000
Cash and cash equivalents uninsured amount	7,000,000	$ 15,200,000
Cash and cash equivalents held by foreign subsidiaries	$ 400,000	500,000
Number of Operating Segments | segment	1
Number of reporting segments | segment	1
Impairment charge	$ 0	$ 0
Short term contingent note | Cognate Bio Services Notes
Summary of Significant Accounting Policies
Deferred Accounts Payable	$ 10,000,000

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Fair Value Measurements
Warrant liability	$ 80,559	$ 106,784
Embedded redemption option	807	988
Contingent payable derivative liability	8,668	8,232
Share liability	678
Total fair value	90,712	116,004
Level 1
Fair Value Measurements
Warrant liability	0	0
Embedded redemption option	0	0
Contingent payable derivative liability	0	0
Share liability	0
Total fair value	0	0
Level 2
Fair Value Measurements
Warrant liability	0	0
Embedded redemption option	0	0
Contingent payable derivative liability	0	0
Share liability	0
Total fair value	0	0
Level 3
Fair Value Measurements
Warrant liability	80,559	106,784
Embedded redemption option	807	988
Contingent payable derivative liability	8,668	8,232
Share liability	678
Total fair value	$ 90,712	$ 116,004

Fair Value Measurements - Chang

Fair Value Measurements - Changes in Level 3 liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Fair Value Measurements
Balance	$ 116,004	$ 365,754
Additional warrant liability	191	1,785
Additional embedded redemption option		947
Additional share liability	711
Reclassification of warrant liabilities	(51,769)	(11,210)
Debt conversion		(1,925)
Debt redemption	213
Change in fair value	25,788	(239,347)
Balance	$ 90,712	$ 116,004
Fair Value, Liability, Recurring Basis, Still Held, Unrealized Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Derivative, Gain (Loss) on Derivative, Net	Derivative, Gain (Loss) on Derivative, Net
Warrant Liability
Fair Value Measurements
Balance	$ 106,784	$ 354,972
Additional warrant liability	184	1,785
Reclassification of warrant liabilities	(51,769)	(11,210)
Change in fair value	25,360	(238,763)
Balance	80,559	106,784
Embedded Redemption Option
Fair Value Measurements
Balance	988	2,507
Additional warrant liability	7
Additional embedded redemption option		947
Debt conversion		(1,925)
Debt redemption	213
Change in fair value	25	(541)
Balance	807	988
Contingent Payable Derivative Liability
Fair Value Measurements
Balance	8,232	8,275
Change in fair value	436	(43)
Balance	8,668	$ 8,232
Share liability
Fair Value Measurements
Additional share liability	711
Change in fair value	(33)
Balance	$ 678

Fair Value Measurements - Weigh

Fair Value Measurements - Weighted average (in aggregate) significant unobservable inputs (Details) - $ / shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Warrant Liability
Fair Value Measurements
Strike price	$ 0.31	$ 0.30
Contractual term (years)	1 year 6 months	1 year
Volatility (annual)	86%	90%
Risk-free rate	4.30%	0.10%
Dividend yield (per share)	0%	0%
Contingent Payable Derivative Liability
Fair Value Measurements
Strike price	$ 0.78	$ 0.70
Contractual term (years)	7 months 6 days	1 year 7 months 6 days
Volatility (annual)	77%	72%
Risk-free rate	4.80%	0.60%
Dividend yield (per share)	0%	0%
Share liability
Fair Value Measurements
Strike price	$ 0.78
Contractual term (years)	1 month 6 days
Volatility (annual)	76%
Risk-free rate	2%
Dividend yield (per share)	0%

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of stock-based compensation expense (Details) - USD ($) $ in Thousands, shares in Millions		12 Months Ended
	Sep. 26, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Stock-Based Compensation
Total stock-based compensation expense		$ 12,298	$ 15,571	$ 51,955
Total unrecognized compensation cost		1,600
Share-based compensation arrangement by share-based payment award, shares issued in period	13.5
Milestone achieved
Stock-Based Compensation
Total unrecognized compensation cost		$ 5,900
Share-based compensation arrangement by share-based payment award, shares issued in period		7.5
Future milestone
Stock-Based Compensation
Remaining share awards recognized		$ 3,500
Research and development
Stock-Based Compensation
Total stock-based compensation expense		1,918	7,607	19,792
Stock based compensation		1,400
Milestone achieved
Stock-Based Compensation
Total stock-based compensation expense		5,870
Future milestone
Stock-Based Compensation
Total stock-based compensation expense		3,573
General and administrative
Stock-Based Compensation
Total stock-based compensation expense		937	$ 7,964	$ 32,163
Stock based compensation		$ 300

Stock-Based Compensation - Assu

Stock-Based Compensation - Assumptions (Details) - $ / shares		12 Months Ended
	Aug. 05, 2020	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Stock-Based Compensation
Exercise price		$ 0.65	$ 0.92	$ 0.26
Expected term (years)		3 years 10 months 24 days	5 years 3 months 18 days	5 years 2 months 12 days
Expected stock price volatility		99%	97%	98%
Risk-free rate		3.30%	1%	0%
Dividend yield (per share)		0%	0%	0%
Post Modification
Stock-Based Compensation
Exercise price	$ 0.22		$ 0.23
Expected term (years)	5 years 3 months 18 days		4 years 3 months 18 days
Expected stock price volatility	96%		97%
Risk-free rate	0%		0%
Pre Modification
Stock-Based Compensation
Exercise price	$ 0.22		$ 0.23
Expected term (years)	4 years 8 months 12 days		4 years
Expected stock price volatility	97%		97%
Risk-free rate	0%		0%

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock option activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended	12 Months Ended
	Aug. 05, 2020	Sep. 30, 2020	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Stock-Based Compensation
Number of Shares, Outstanding			304,847	308,840	104,659
Number of Shares, Granted			8,005	910	208,525
Number of Shares, Cash exercised				(183)
Number of Shares, Cashless exercised			(8,187)	(4,720)	(94)
Number of Shares, Forfeited/expired			(3,402)		(4,250)
Number of Shares, Outstanding	3,000		301,263	304,847	308,840	104,659
Number of Shares, Options vested			282,271
Weighted Average Exercise Price, Outstanding			$ 0.33	$ 0.33	$ 0.24
Weighted Average Exercise Price, Granted	$ 0.22	$ 0.25	0.65	0.92	0.37
Weighted Average Exercise Price, Cash exercise				0.25
Weighted Average Exercise Price, Cashless exercised			0.27	0.25	0.34
Weighted Average Exercise Price, Forfeited/expired			0.88		0.22
Weighted Average Exercise Price, Outstanding			0.34	$ 0.33	$ 0.33	$ 0.24
Weighted Average Exercise Price, Options vested			$ 0.33
Weighted Average Remaining Contractual Life (in years), Outstanding			7 years	8 years	8 years 10 months 24 days	8 years 4 months 24 days
Weighted Average Remaining Contractual Life (in years), Granted			4 years 4 months 24 days	8 years 7 months 6 days	10 years
Weighted Average Remaining Contractual Life (in years), Options vested			7 years
Total Intrinsic Value, Outstanding			$ 114,803	$ 372,219
Total Intrinsic Value, Outstanding			135,225	$ 114,803	$ 372,219
Total Intrinsic Value, Options vested			$ 127,951

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) - USD ($)						1 Months Ended	3 Months Ended	12 Months Ended
	Sep. 26, 2022	Aug. 22, 2022	Dec. 01, 2020	Aug. 28, 2020	Aug. 05, 2020	Apr. 30, 2020	Sep. 30, 2020	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Stock-Based Compensation
Total unrecognized compensation cost								$ 1,600,000
Share-based compensation arrangement by share-based payment award, shares issued in period	13,500,000
Unrecognized compensation cost recognized period (in years)								1 year 3 months 18 days
Weighted Average Exercise Price, Granted					$ 0.22		$ 0.25	$ 0.65	$ 0.92	$ 0.37
Share Based Compensation Arrangement By Share Based Payment Award Period Of Notice For Exercising Any Option								61 days
Existing options that the Company's CEO has agreed to not exercise until the specified period (in shares)						39,200,000
Extended contractual term of the options held by the Company's CEO						6 months
Incremental stock-based compensation for stock options modification					$ 300,000			$ 78,000,000
Share-based compensation arrangement by share-based payment award, options, cancelled in period					1,750,000
Number of shares, outstanding					3,000,000			301,263,000	304,847,000	308,840,000	104,659,000
Total stock-based compensation expense								$ 12,298,000	$ 15,571,000	$ 51,955,000
Aggregate shares issued value								135,225,000	$ 114,803,000	$ 372,219,000
Period during which the Company's CEO has agreed to not exercise the options						6 months
Milestone achieved
Stock-Based Compensation
Total unrecognized compensation cost								$ 5,900,000
Share-based compensation arrangement by share-based payment award, shares issued in period								7,500,000
Future milestone
Stock-Based Compensation
Remaining share awards recognized								$ 3,500,000
Common Stock
Stock-Based Compensation
Issuance of common stock for cash (in shares)								13,147,000	6,272,000	97,981,000
Flaskworks
Stock-Based Compensation
Share-based Compensation				$ 2,000,000
Additional stock options agreed to be issued			1,500,000
Total stock-based compensation expense								$ 700,000	$ 1,000,000
January Options
Stock-Based Compensation
Options exercisable								83,300,000
April Options
Stock-Based Compensation
Options exercisable								153,300,000
Options
Stock-Based Compensation
Weighted Average Exercise Price, Granted								$ 0.36
Performance shares
Stock-Based Compensation
Stock based compensation				1,200,000
Restricted stock
Stock-Based Compensation
Share-based compensation arrangement by share-based payment award, shares issued in period								13,500,000
Remaining share awards recognized								$ 4,000,000
Aggregate shares issued value								10,100,000
Restricted stock | Milestone achieved
Stock-Based Compensation
Total unrecognized compensation cost								$ 5,900,000
Share-based compensation arrangement by share-based payment award, shares issued in period								7,500,000
Restricted stock | Future milestone
Stock-Based Compensation
Remaining share awards recognized								$ 3,700,000
Restricted stock | Common Stock
Stock-Based Compensation
Issuance of common stock for cash (in shares)		1,600,000						1,000,000
General and administrative
Stock-Based Compensation
Stock based compensation								$ 300,000
Total stock-based compensation expense								937,000	7,964,000	$ 32,163,000
General and administrative | Flaskworks
Stock-Based Compensation
Total stock-based compensation expense								100,000	500,000
Research and development
Stock-Based Compensation
Stock based compensation								1,400,000
Total stock-based compensation expense								1,918,000	$ 7,607,000	$ 19,792,000
Research and development | Flaskworks
Stock-Based Compensation
Total stock-based compensation expense			$ 500,000					500,000
Research and development | Performance shares
Stock-Based Compensation
Stock based compensation				$ 300,000				$ 900,000

Property, Plant and Equipment_2

Property, Plant and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment
Construction in progress	$ 2,028
Total property, plant and equipment, net	13,418	$ 15,027
Domestic
Property, Plant and Equipment
Property, plant and equipment, gross	15,690	16,111
Less: accumulated depreciation	(2,272)	(1,084)
Construction in progress	$ 2,028
Leasehold improvements
Property, Plant and Equipment
Leasehold improvements useful life	Lesser of lease term or estimated useful life
Leasehold improvements | Domestic
Property, Plant and Equipment
Property, plant and equipment, gross	$ 13,070	13,910
Office furniture and equipment | Maximum
Property, Plant and Equipment
Property, plant and equipment, useful life	5 years
Office furniture and equipment | Minimum
Property, Plant and Equipment
Property, plant and equipment, useful life	3 years
Office furniture and equipment | Domestic
Property, Plant and Equipment
Property, plant and equipment, gross	$ 300	310
Computer equipment and software | Maximum
Property, Plant and Equipment
Property, plant and equipment, useful life	5 years
Computer equipment and software | Minimum
Property, Plant and Equipment
Property, plant and equipment, useful life	3 years
Computer equipment and software | Domestic
Property, Plant and Equipment
Property, plant and equipment, gross	$ 2,238	1,799
Land | U.K
Property, Plant and Equipment
Property, plant and equipment, gross	$ 82	$ 92

Property, Plant and Equipment -

Property, Plant and Equipment - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment
Depreciation	$ 1,300,000	$ 300,000	$ 87,000

Notes Payable (Details)

Notes Payable (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Apr. 30, 2021	Dec. 31, 2018
Notes Payable
Stated Interest Rate			1%	10%
Face Value	$ 22,454	$ 35,243
Remaining Debt Discount	(1,732)	(3,836)
Embedded Redemption Option	807	988
Carrying Value	21,529	32,395
Short term convertible notes payable
Notes Payable
Face Value	135	135
Carrying Value	$ 135	$ 135
Short term convertible notes payable | 6% Unsecurble
Notes Payable
Maturity Date, Description	Due	Due
Stated Interest Rate	6%	6%
Conversion Price	$ 3.09	$ 3.09
Face Value	$ 135	$ 135
Carrying Value	135	135
Short term notes payable
Notes Payable
Face Value	15,896	7,255
Remaining Debt Discount	(1,300)	(198)
Embedded Redemption Option	807	47
Carrying Value	$ 15,403	$ 7,104
Short term notes payable | 8% unsecured
Notes Payable
Maturity Date, Description	Various	Various
Stated Interest Rate	8%	8%
Face Value	$ 14,540	$ 2,320
Remaining Debt Discount	(1,300)	(118)
Embedded Redemption Option	807
Carrying Value	$ 14,047	$ 2,202
Short term notes payable | 9% unsecured
Notes Payable
Maturity Date, Description	Various	Various
Stated Interest Rate	9%	9%
Face Value	$ 793	$ 4,232
Remaining Debt Discount		(80)
Embedded Redemption Option		47
Carrying Value	$ 793	$ 4,199
Short term notes payable | 12% Unsecured
Notes Payable
Maturity Date, Description	On Demand	On Demand
Stated Interest Rate	12%	12%
Face Value	$ 563	$ 703
Carrying Value	563	$ 703
Short term convertible notes payable - related parties | 1% unsecured
Notes Payable
Maturity Date, Description		Various
Stated Interest Rate		1%
Face Value		$ 433
Carrying Value		433
Long term notes payable
Notes Payable
Face Value	6,423	27,853
Remaining Debt Discount	(432)	(3,638)
Embedded Redemption Option		941
Carrying Value	$ 5,991	$ 25,156
Long term notes payable | 6% Unsecurble
Notes Payable
Maturity Date, Description	3/25/2025
Stated Interest Rate	6%
Face Value	$ 918
Carrying Value	$ 918
Long term notes payable | 8% unsecured
Notes Payable
Maturity Date, Description	7/26/2024	9/22/2023
Stated Interest Rate	8%	8%
Face Value	$ 5,505	$ 25,938
Remaining Debt Discount	(432)	(3,638)
Embedded Redemption Option		941
Carrying Value	5,073	$ 23,241
Long term notes payable | 6% secured
Notes Payable
Maturity Date, Description		3/25/2025
Stated Interest Rate		6%
Face Value	$ 918	$ 1,482
Carrying Value		$ 1,482

Notes Payable - Mortgage Loan (

Notes Payable - Mortgage Loan (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Notes Payable
Other interest expenses	$ 407,000	$ 223,000	$ 10,000
Total interest expense	6,068,000	5,011,000	8,544,000
Forbearance of debt to related parties
Notes Payable
Interest expenses			4,270,000
Advent BioServices
Notes Payable
Interest expenses		140,000
Interest expenses related to outstanding notes
Notes Payable
Contractual interest	2,890,000	2,347,000	1,231,000
Amortization of debt discount	2,771,000	2,301,000	2,891,000
Total interest expenses	$ 5,661,000	$ 4,648,000	4,122,000
Interest expenses related to outstanding notes to related parties
Notes Payable
Contractual interest			20,000
Amortization of debt discount			122,000
Total interest expenses			$ 142,000

Notes Payable - summary of the

Notes Payable - summary of the company's contractual obligations on debt principal (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Notes Payable
Aggregate principal amount	$ 22,454	$ 35,243
Short term convertible note | 6% unsecured
Notes Payable
Aggregate principal amount	135
Short term notes payable
Notes Payable
Aggregate principal amount	15,896	7,255
Short term notes payable | 8% unsecured
Notes Payable
Aggregate principal amount	14,540	2,320
Short term notes payable | 9% unsecured
Notes Payable
Aggregate principal amount	793	4,232
Short term notes payable | 12% Unsecured
Notes Payable
Aggregate principal amount	563	703
Long term notes payable
Notes Payable
Aggregate principal amount	6,423	27,853
Long term notes payable | 8% unsecured
Notes Payable
Aggregate principal amount	5,505	25,938
Long term notes payable | 6% secured
Notes Payable
Aggregate principal amount	918	$ 1,482
Less than 1 Year
Notes Payable
Aggregate principal amount	16,031
Less than 1 Year | Short term convertible note | 6% unsecured
Notes Payable
Aggregate principal amount	135
Less than 1 Year | Short term notes payable | 8% unsecured
Notes Payable
Aggregate principal amount	14,540
Less than 1 Year | Short term notes payable | 9% unsecured
Notes Payable
Aggregate principal amount	793
Less than 1 Year | Short term notes payable | 12% Unsecured
Notes Payable
Aggregate principal amount	563
1 to 2 Years
Notes Payable
Aggregate principal amount	5,505
1 to 2 Years | Long term notes payable | 8% unsecured
Notes Payable
Aggregate principal amount	5,505
3 to 5 Years
Notes Payable
Aggregate principal amount	918
3 to 5 Years | Long term notes payable | 6% secured
Notes Payable
Aggregate principal amount	$ 918

Notes Payable - Additional Info

Notes Payable - Additional Information (Details) $ in Thousands							1 Months Ended	3 Months Ended	7 Months Ended	12 Months Ended
	Sep. 26, 2022 USD ($) installment	Nov. 22, 2021 USD ($) installment	Nov. 01, 2021 installment	Apr. 09, 2021 USD ($)	Mar. 01, 2021 USD ($)	Jan. 15, 2021 shares	Apr. 30, 2021	Dec. 31, 2021 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2022 USD ($) loan shares	Dec. 31, 2021 USD ($) shares	Dec. 31, 2018
Notes Payable
Percentage of aggregate principal amount for next offering											50%
Discount rate (as a percent)											12%
Debt amount converted											$ 5,600
Det converted to common stock (in shares) | shares											5,100,000
Det converted to warrants (in shares) | shares						261,000					800,000
Cash payments											$ 5,800
Fair value of debt converted								$ 7,500	$ 7,500	$ 5,900	7,500
Aggregate principal amount								$ 35,243	$ 35,243	$ 22,454	35,243
Extinguishment of debt upon conversion											$ 1,900
Debt instrument, interest rate							1%					10%
Original issue discount		$ 1,500
Notes
Notes Payable
Percentage of aggregate principal amount for next offering										50%
Percentage of exercised warrant shares for next offering										50%
Discount rate (as a percent)									12%	12%
Cash payments										$ 11,300
Original issue discount rate								5%	5%	5%	5%
Interest Rate		110
Number of shares issued to lenders in lieu of cash payments | shares										18,100,000
Conversion of share settled debt into common stock										$ 13,800
Aggregate principal amount		$ 16,500						$ 4,400	$ 4,400	600	$ 4,400
Accrued interest expense on debt										1,800
Extinguishment of debt upon conversion										200
Gain (loss) from debt extinguishment										(2,300)
Additional debt extinguishment loss										(700)
Aggregate cash payments made										6,400
Interest expense on debt										900
Interest expense including amortization of debt discount										2,900
Amortization of debt discount										2,800
Interest expense related to german taxes										$ 400
Debt instrument, interest rate		8%						9%	9%	9%	9%
Number of installments for amortization | installment		14
Proceeds from issuance of debt									$ 4,200	$ 600
Notes | Series C Convertible Preferred Stock
Notes Payable
Number of shares issued to lenders in lieu of cash payments | shares										200,000
Conversion of share settled debt into common stock										$ 3,500
Aggregate principal amount										3,400
Accrued interest expense on debt										400
Gain (loss) from debt extinguishment										$ (100)
Commercial Loan
Notes Payable
Aggregate principal amount	$ 5,500				$ 10,000
Debt instrument, interest rate	8%				8%
Term of debt instrument	22 months				22 months
Term when no principal repayments was made					8 months
Number of installments for amortization | installment	14		14
Original issue discount	$ 500				$ 1,000
Paycheck Protection Program Loan
Notes Payable
Number of additional loans received | loan										2
Extinguishment of debt upon conversion										$ 400
Gain (loss) from debt extinguishment										$ 400
Term of debt instrument							5 years
Proceeds from issuance of debt				$ 400
Four-month note agreements
Notes Payable
Percentage of aggregate principal amount for next offering		50%							50%
Discount rate (as a percent)		12%
Extended term of debt		14 days
Multiple Notes
Notes Payable
Extinguishment of debt upon conversion								$ 200
Multiple Notes | Minimum
Notes Payable
Extended term of debt								2 months		2 months
Multiple Notes | Maximum
Notes Payable
Extended term of debt								4 months		4 months

Net (Loss) Earnings per Share_3

Net (Loss) Earnings per Share Applicable to Common Stockholders - Computation of earnings (loss) per share (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Net (Loss) Earnings per Share Applicable to Common Stockholders
Net (loss) earnings - basic	$ (105,032)	$ 179,126	$ (529,821)
Reversal of gain due to change in fair value of warrant liability		(239,347)
Net loss - diluted	$ (105,032)	$ (60,221)	$ (529,821)
Weighted average shares outstanding - basic	1,015,852	873,517	725,129
Convertible notes and interest		76
Weighted average shares outstanding - diluted	1,015,852	1,007,869	725,129
Warrants
Net (Loss) Earnings per Share Applicable to Common Stockholders
Diluted shares		95,780
Options
Net (Loss) Earnings per Share Applicable to Common Stockholders
Diluted shares		38,496

Net (Loss) Earnings per Share_4

Net (Loss) Earnings per Share Applicable to Common Stockholders (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Net (Loss) Earnings per Share Applicable to Common Stockholders
Potentially dilutive securities	477,773	396,039	643,210
Series C convertible preferred stock
Net (Loss) Earnings per Share Applicable to Common Stockholders
Potentially dilutive securities	35,384
Common stock options
Net (Loss) Earnings per Share Applicable to Common Stockholders
Potentially dilutive securities	301,263	266,350	308,840
Common stock warrants
Net (Loss) Earnings per Share Applicable to Common Stockholders
Potentially dilutive securities	141,048	129,689	328,979
Contingently issuable warrants
Net (Loss) Earnings per Share Applicable to Common Stockholders
Potentially dilutive securities			2,774
Convertible notes and accrued interest
Net (Loss) Earnings per Share Applicable to Common Stockholders
Potentially dilutive securities	78		2,617

Related Party Transactions - (D

Related Party Transactions - (Details)				12 Months Ended
	Sep. 26, 2022 item	Jul. 02, 2020 USD ($) shares	May 14, 2018	Dec. 31, 2022 USD ($) ft² Milestone item $ / shares shares	Dec. 31, 2022 GBP (£) Milestone item shares	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Aug. 12, 2022 $ / shares	Apr. 30, 2021	Jan. 15, 2021 $ / shares	Dec. 31, 2018	Sep. 26, 2018 USD ($)
Related Party Transactions
Lease payments				$ 909,000		$ 866,000	$ 993,000
Sub-lease income				145,000
Short-term debt												$ 65,000
Debt instrument, interest rate									1%		10%
Repayment of notes payable to related parties							(379,000)
Warrants exercise price | $ / shares								$ 0.24		$ 2
Amount recognized and expensed related to current cash component				3,000,000
Amount recognized and expensed related to cash component				$ 3,700,000
Shares in milestone cost | shares				7,500,000	7,500,000
Fair value of debt converted				$ 5,900,000		7,500,000
Amount recognized and expensed related to stock component				$ 3,600,000
Number of milestones completed | Milestone				7	7
Capitalized costs to related party				$ 28,584,000		$ 7,417,000	7,543,000
Accounts payable to related party
Related Party Transactions
Unpaid board compensation				$ 400,000
Senior Vice President
Related Party Transactions
Percentage of warrant coverage						50
Convertible notes payable						$ 300,000
Forbearance Warrants
Related Party Transactions
Class of warrant or right, warrant issued | shares		15,200,000
Extension of loans		$ 5,400,000
Warrants exercise price | $ / shares				$ 0.21
Term of debt instrument				5 years	5 years
Accrued interest expense				$ 4,300,000
Advent BioServices - amount invoiced but unpaid
Related Party Transactions
Number of workstreams | item				6	6
Accounts payable and accrued expenses				$ 1,844,000		$ 3,046,000
Term (in months)			12 months
Advent BioServices Notes
Related Party Transactions
Repayment of notes payable to related parties							(73,000)
Advent BioServices Notes | Senior Vice President
Related Party Transactions
Debt instrument, interest rate						10%
Advent BioServices
Related Party Transactions
Area of sublease (in sqft)				14,459
Total area of lease (in sqft) | ft²				88,000
Number of times calculated for lease payment under sub-lease | item				2	2
Rate per square foot under sub-lease				$ 6.96	£ 5.75
Cap rate per square foot under sub-lease				10
Sub-lease payments receivable				145,000
Lease payments | £					£ 500,000
Accounts payable and accrued expenses				6,580,000		$ 3,046,000
Capitalized cost				28,000,000,000
Capitalized costs to related party						$ 3,200,000
Approximate lease payments				600,000
Advent BioServices - amount accrued and unpaid
Related Party Transactions
Number of workstreams | item	6
Accounts payable and accrued expenses				$ 4,736,000
Mr. Goldman
Related Party Transactions
Repayment of notes payable to related parties							$ (300,000)

Related Party Transactions - Re

Related Party Transactions - Research and development Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Related Party Transactions
Total	$ 28,584	$ 7,417	$ 7,543
Expensed and paid (milestone complete)
Related Party Transactions
Related party costs, SOW 6 one-time milestones - Shares	5,120
Related party costs, SOW 6 one-time milestones - Cash	3,000
Expensed and paid (partial milestone earned)
Related Party Transactions
Related party costs, SOW 6 one-time milestones - Shares	750
Related party costs, SOW 6 one-time milestones - Cash	1,000
Expensed and due, but unpaid (milestone complete)
Related Party Transactions
Related party costs, SOW 6 one-time milestones - Shares	3,573
Related party costs, SOW 6 one-time milestones - Cash	3,700
Advent BioServices
Related Party Transactions
Total		3,200
Advent BioServices | Manufacturing cost in London
Related Party Transactions
Related party costs, Manufacturing costs	5,675	6,625	5,288
Advent BioServices | Manufacturing cost at Sawston facility
Related Party Transactions
Related party costs, Manufacturing costs	$ 5,766	$ 792	$ 2,255

Preferred Stock (Details)

Preferred Stock (Details)		12 Months Ended
	Aug. 12, 2022 USD ($) $ / shares shares	Dec. 31, 2022 USD ($) $ / shares shares	Dec. 31, 2021 USD ($) $ / shares shares	Dec. 31, 2020 USD ($) shares	Jul. 20, 2022 $ / shares shares	Jan. 15, 2021 $ / shares
Preferred Stock
Extinguishment of debt including accrued interest | $			$ 1,900,000
Proceeds from issuance of Series C convertible preferred stock | $		$ 18,669,000
Warrants to purchase shares | shares	1,400,000			8,500,000
Warrants exercise price	$ 0.24					$ 2
Proceeds from exercise of warrants and stock options | $	$ 329,000	$ 11,105,000	$ 19,975,000	$ 13,915,000
Term by which preferred shares cannot be converted into common stock	3 months
Minimum
Preferred Stock
Warrants exercise price		$ 0.18	$ 0.175
Maximum
Preferred Stock
Warrants exercise price		$ 0.85	$ 0.40
Series C Convertible Preferred Stock
Preferred Stock
Temporary equity, shares designated | shares		10,000,000	10,000,000		10,000,000
Temporary equity, par value					$ 0.001
Warrants to purchase shares | shares	54,847
Conversion ratio from preferred stock to common stock	0.04
Series C Convertible Preferred Stock | Common Stock
Preferred Stock
Convertible per share | shares		25
Series C Convertible Preferred Stock | Minimum
Preferred Stock
Purchase price		$ 15
Price per share		15
Series C Convertible Preferred Stock | Minimum | Common Stock
Preferred Stock
Purchase price		0.60
Price per share		0.60
Series C Convertible Preferred Stock | Maximum
Preferred Stock
Purchase price		21.25
Price per share		21.25
Series C Convertible Preferred Stock | Maximum | Common Stock
Preferred Stock
Purchase price		0.85
Price per share		0.85
Series C Convertible Preferred Stock | Series C Subscription Agreements | Series C Investors
Preferred Stock
Temporary equity, par value		$ 0.001
Issuance of stock for cash (in shares) | shares		1,400,000
Purchase price		$ 16.15
Gross proceeds from issuance of shares | $		$ 22,000,000
Extinguishment of debt including accrued interest | $		3,400,000
Extinguishment of accrued interest | $		400,000
Proceeds from issuance of Series C convertible preferred stock | $		$ 18,700,000
Price per share		$ 16.15

Stockholders' Deficit - Additio

Stockholders' Deficit - Additional Information (Details) - USD ($)

1 Months Ended

12 Months Ended

Aug. 12, 2022

Oct. 12, 2021

Jan. 15, 2021

Dec. 25, 2020

Dec. 01, 2020

Oct. 12, 2020

Aug. 05, 2020

Jan. 31, 2023

May 31, 2020

Apr. 30, 2020

Dec. 31, 2022

Dec. 31, 2021

Dec. 31, 2020

Feb. 28, 2023

Jan. 09, 2023

Nov. 01, 2020

Feb. 29, 2020

Dec. 31, 2019

Stockholders' Deficit

Proceeds from exercise of warrants and stock options

$ 329,000

$ 11,105,000

$ 19,975,000

$ 13,915,000

Warrants exercise price

$ 0.24

$ 2

Warrants exercise period

12 months

Stock issued on exercise of warrants

45,300,000

86,900,000

Number of Warrants, Cashless warrants exercise

(35,951)

(19,743)

(8,631)

Number of shares issued for repayments of debt

18,100,000

Amount of debt redeemed from issuance of shares

$ 11,300,000

Amount of interest on debt redeemed from issuance of shares

1,800,000

Percentage of aggregate principal amount for next offering

50%

Discount rate (as a percent)

12%

Inducement expense

$ 647,000

Warrants to purchase shares

1,400,000

8,500,000

Class of warrant or right, warrant term

2 years

Proceeds from issuance of common stock, net

$ 9,465,000

$ 4,070,000

$ 26,814,000

Class of warrant or right, agreed to be suspended

3,500,000

14,600,000

Warrants not settleable in cash, fair value disclosure

$ 5,300,000

Number of warrants suspended

137,000,000

Number of warrants issued

261,000

800,000

Debt amount converted

$ 5,600,000

Shares issued during period shares, upon exercise of warrants

47,500,000

Weighted average exercise price, cashless warrants exercise

$ 0.23

$ 0.22

$ 0.22

Det converted to common stock (in shares)

5,100,000

General and administrative expenses

$ 33,353,000

$ 33,399,000

$ 54,259,000

Number of common stock issued

7,100,000

Increase in common stock shares authorized

500,000,000

Common stock, shares issued

1,068,400,000

948,400,000

Number of warrants outstanding

141,048

225,469

331,753

359,473

Subsequent event

Stockholders' Deficit

Number of warrants outstanding

37,700,000

Flaskworks

Stockholders' Deficit

Weighted average exercise price, cashless warrants exercise

$ 0.336

Issue of common stock upon completion of significant milestone

700,000

1,500,000

General and administrative expenses

$ 900,000

Special consideration payment

$ 200,000

Convertible Preferred Stock

Stockholders' Deficit

Issuance of stock by common stock warrant exercised for cash

300,000

Warrants issued as consideration for warrants suspension

Stockholders' Deficit

Number of warrants outstanding

141,000,000

Cashless Warrants Exercise

Stockholders' Deficit

Stock issued on exercise of warrants

29,000,000

20,400,000

Number of Warrants, Cashless warrants exercise

(8,200,000)

(24,500,000)

Convertible Debt Securities

Stockholders' Deficit

Number of warrants issued

6,200,000

Debt amount converted

$ 13,900,000

Det converted to common stock (in shares)

58,400,000

Registered Direct Offering

Stockholders' Deficit

Warrants exercise price

$ 0.25

Proceeds from Issuance Initial Public Offering

$ 5,700,000

Payments for repurchase of initial public offering

$ 400,000

Common stock, shares issued

34,500,000

April Financing

Stockholders' Deficit

Warrants exercise price

$ 0.20

Number of shares issued during the period

19,900,000

Warrants to purchase shares

11,300,000

Strike price

$ 0.153

Proceeds from issuance of common stock, net

$ 3,000,000

Payments of stock issuance costs

68,000

Proceeds from issuance of warrants

$ 800,000

May Financing

Stockholders' Deficit

Number of shares issued during the period

14,200,000

Warrants to purchase shares

5,600,000

Proceeds from issuance of common stock, net

$ 2,900,000

Proceeds from issuance of warrants

$ 900,000

August Financing

Stockholders' Deficit

Amount of financing

$ 8,000,000

Number of warrants suspended

75,500,000

Number of warrants issued

12,500,000

August Financing | Subsequent event

Stockholders' Deficit

Number of warrants suspended

59,000,000

August Financing | Warrants issued as consideration for warrants suspension

Stockholders' Deficit

Warrants exercise price

$ 0.34

August Financing | Convertible notes payable

Stockholders' Deficit

Warrants exercise price

$ 0.34

Proceeds from issuance of convertible notes payable, net

$ 1,000,000

Conversion price

$ 0.345

Class of warrant or right, percentage of warrants issued on conversion

35%

August Financing

Stockholders' Deficit

Warrants exercise period

3 months

Warrants to purchase shares

3,600,000

Incremental change in fair value of warrants

$ 1,200,000

Strike price

$ 0.816

Class of warrant or right, agreed to be suspended

3,600,000

Amount of financing

$ 11,900,000

Debt amount converted

$ 10,000,000

August Financing | Convertible notes payable

Stockholders' Deficit

Warrants exercise price

$ 2

Warrants exercise period

12 months

Proceeds from issuance of convertible notes payable, net

$ 1,900,000

Conversion price

$ 0.85

Class of warrant or right, percentage of warrants issued on conversion

30%

Placement Agent

Stockholders' Deficit

Warrants to purchase shares

800,000

Class of warrant or right, warrant term

2 years

Minimum

Stockholders' Deficit

Warrants exercise price

$ 0.18

$ 0.175

Minimum | Subsequent event

Stockholders' Deficit

Increase in common stock shares authorized

1,200,000,000

Minimum | Cashless Warrants Exercise

Stockholders' Deficit

Warrants exercise price

0.18

0.20

Minimum | May Financing

Stockholders' Deficit

Warrants exercise price

$ 0.22

Class of warrant or right, warrant term

1 year 6 months

Strike price

$ 0.17

Minimum | August Financing | Warrants issued as consideration for warrants suspension

Stockholders' Deficit

Warrants exercise period

13 months 15 days

Minimum | Placement Agent

Stockholders' Deficit

Warrants exercise price

$ 0.17

Maximum

Stockholders' Deficit

Warrants exercise price

0.85

0.40

Maximum | Subsequent event

Stockholders' Deficit

Increase in common stock shares authorized

1,700,000,000

Maximum | Cashless Warrants Exercise

Stockholders' Deficit

Warrants exercise price

$ 0.52

$ 0.52

Maximum | May Financing

Stockholders' Deficit

Warrants exercise price

$ 0.23

Class of warrant or right, warrant term

2 years 6 months

Strike price

$ 0.225

Maximum | August Financing | Warrants issued as consideration for warrants suspension

Stockholders' Deficit

Warrants exercise period

25 months 15 days

Maximum | Placement Agent

Stockholders' Deficit

Warrants exercise price

$ 0.21

Common Stock

Stockholders' Deficit

Proceeds from issuance of common stock to investors

$ 9,500,000

$ 4,100,000

Stock issued on exercise of warrants

5,200,000

Number of Warrants, Cashless warrants exercise

(8,600,000)

Number of shares issued during the period

6,300,000

Proceeds from issuance of common stock

$ 300,000

Percentage of warrants exercisable

30%

Issue of common stock upon completion of significant milestone

655,000

Common Stock | Cashless Warrants Exercise

Stockholders' Deficit

Number of Warrants, Cashless warrants exercise

(36,000,000)

Common Stock | Cashless Warrants Exercise | Subsequent event

Stockholders' Deficit

Stock issued on exercise of warrants

600,000

Number of Warrants, Cashless warrants exercise

(1,100,000)

Common Stock | August Financing

Stockholders' Deficit

Proceeds from issuance of common stock to investors

$ 7,000,000

Warrants exercise price

$ 0.34

Number of shares issued during the period

21,800,000

Incremental change in fair value of warrants

$ 1,500,000

Strike price

$ 0.32

Number of warrants exercisable

5,300,000

Common Stock | August Financing

Stockholders' Deficit

Warrants exercise price

$ 2

Warrants exercise period

12 months

Number of shares issued during the period

12,200,000

Common Stock | Investors

Stockholders' Deficit

Proceeds from issuance of common stock to investors

$ 13,100,000

Common Stock | Minimum | Cashless Warrants Exercise

Stockholders' Deficit

Warrants exercise price

$ 0.23

Common Stock | Minimum | Cashless Warrants Exercise | Subsequent event

Stockholders' Deficit

Warrants exercise price

$ 0.34

Common Stock | Minimum | August Financing

Stockholders' Deficit

Warrants exercise period

18 years

Percentage of warrants exercisable

20%

Common Stock | Maximum | Cashless Warrants Exercise

Stockholders' Deficit

Warrants exercise price

$ 0.34

Common Stock | Maximum | Cashless Warrants Exercise | Subsequent event

Stockholders' Deficit

Warrants exercise price

$ 0.35

Common Stock | Maximum | August Financing

Stockholders' Deficit

Warrants exercise period

30 months

Percentage of warrants exercisable

35%

Warrants | Registered Direct Offering

Stockholders' Deficit

Incremental change in fair value of warrants

$ 2,500,000

Warrants | Placement Agent

Stockholders' Deficit

Warrants to purchase shares

1,000,000

Stockholders' Deficit - Stock P

Stockholders' Deficit - Stock Purchase Warrants (Details) - $ / shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Stockholders' Deficit
Number of Warrants, Outstanding	225,469	331,753	359,473
Number of Warrants, Warrants granted		(1,209)	88,658
Number of Warrants, Contingently issuable warrants			(2,774)
Number of Warrants, Warrants exercised for cash	(46,671)	(86,726)	(47,511)
Number of Warrants, Cashless warrants exercise	(35,951)	(19,743)	(8,631)
Number of Warrants, Warrants expired and cancellation	(1,799)	(1,024)	(63,010)
Number of Warrants, Outstanding	141,048	225,469	331,753	359,473
Weighted Average Exercise Price - Outstanding	$ 0.30	$ 0.28	$ 0.27
Weighted Average Exercise Price - Warrants granted		1.39	0.22
Weighted Average Exercise Price - Contingently issuable warrants			1.48
Weighted Average Exercise Price - Warrants exercised for cash	0.25	0.23	0.29
Weighted Average Exercise Price, Cashless warrants exercise	0.23	0.22	0.22
Weighted Average Exercise Price, Warrants expired and cancellation	1.58	2.95	0.32
Weighted Average Exercise Price - Outstanding	$ 0.31	$ 0.30	$ 0.28	$ 0.27
Remaining Contractual Term	1 year 5 months 15 days	11 months 15 days	1 year 7 months 9 days	1 year 5 months 1 day

Commitments and Contingencies_2

Commitments and Contingencies (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Lease cost
Operating lease cost	$ 848,000	$ 930,000	$ 940,000
Short-term lease cost	79,000	51,000	44,000
Variable lease cost	13,000	53,000	65,000
Sub-lease income	(145,000)
Total	795,000	1,034,000	1,049,000
Other information
Operating cash flows from operating leases	(909,000)	(866,000)	(993,000)
U.K
Lease cost
Operating lease cost	588,000	653,000	610,000
Short-term lease cost	79,000	51,000	44,000
Variable lease cost		48,000	45,000
Sub-lease income	(145,000)
Total	522,000	752,000	699,000
Other information
Operating cash flows from operating leases	$ (619,000)	$ (688,000)	$ (661,000)
Weighted-average remaining lease term - operating leases	8 years 6 months
Weighted-average remaining lease term - operating leases	8 years 6 months	9 years	9 years 1 month 6 days
Weighted-average discount rate - operating leases	12%	12%	12%
U.S
Lease cost
Operating lease cost	$ 260,000	$ 277,000	$ 330,000
Variable lease cost	13,000	5,000	20,000
Total	273,000	282,000	350,000
Other information
Operating cash flows from operating leases	$ (290,000)	$ (178,000)	$ (332,000)
Weighted-average remaining lease term - operating leases		1 year 3 months 18 days
Weighted-average remaining lease term - operating leases	1 year 3 months 18 days	1 year 9 months 18 days	2 months 12 days
Weighted-average discount rate - operating leases	12%	12%	12%

Commitments and Contingencies -

Commitments and Contingencies - Maturities of our operating leases (Details) $ in Thousands	Dec. 31, 2022 USD ($)
Commitments and Contingencies
Year ended December 31, 2023	$ 903
Year ended December 31, 2024	809
Year ended December 31, 2025	604
Year ended December 31, 2026	604
Year ended December 31, 2027	604
Thereafter	6,631
Total	10,155
Less present value discount	(5,431)
Operating lease liabilities included in the Consolidated Balance Sheet at December 31, 2022	4,724
Sublease agreement
Commitments and Contingencies
Year ended December 31, 2023	145
Year ended December 31, 2024	145
Year ended December 31, 2025	145
Year ended December 31, 2026	145
Thereafter	1,740
Total	$ 2,320

Commitments and Contingencies_3

Commitments and Contingencies - Additional Information (Details) £ in Millions

12 Months Ended

Sep. 26, 2022 item

Jul. 27, 2022 USD ($)

Jul. 27, 2022 EUR (€)

Jun. 30, 2022 USD ($)

Jun. 30, 2022 EUR (€)

Nov. 04, 2021 USD ($)

Nov. 04, 2021 EUR (€)

May 14, 2018 USD ($)

May 14, 2018 GBP (£)

Dec. 31, 2022 USD ($) item

Dec. 31, 2022 EUR (€) item

Dec. 31, 2022 EUR (€)

Dec. 31, 2021 USD ($)

Commitments and Contingencies

Operating lease liabilities | $

$ 4,724,000

Lease, practical expedient, lessor single lease component [true false]

true

true

Operating lease, term of contract

20 years

20 years

ROU asset | $

$ 4,189,000

$ 4,889,000

Original term of the agreement

8 months

8 months

Litigation settlement waiver of penalty

$ 141,000

€ 135,000

Loss contingency accrual

$ 403,000

€ 377,000

Office space taken under lease agreement

The Company subleased approximately 14,459 square feet of 88,000 square foot building interior space, plus corresponding exterior support space and parking located in Sawston, UK. Lease payments under the Agreement are two times the £5.75 (approximate $6.96 per square foot based on exchange rate as of December 31, 2022) rate per square foot payable under the head lease, subject to a cap of $10 per square foot. Accordingly, the lease payments under the Sublease are set at $145,000 per year. The total lease payments paid by the Company for the overall building, exterior space and parking under the head lease are 500,000 pounds per year

The Company subleased approximately 14,459 square feet of 88,000 square foot building interior space, plus corresponding exterior support space and parking located in Sawston, UK. Lease payments under the Agreement are two times the £5.75 (approximate $6.96 per square foot based on exchange rate as of December 31, 2022) rate per square foot payable under the head lease, subject to a cap of $10 per square foot. Accordingly, the lease payments under the Sublease are set at $145,000 per year. The total lease payments paid by the Company for the overall building, exterior space and parking under the head lease are 500,000 pounds per year

Advent Bioscience accrued

Commitments and Contingencies

Number of workstreams | item

6

Advent Bio services agreement

Commitments and Contingencies

Term of agreement

12 months

12 months

Number of workstreams | item

6

6

Advent Bio services agreement | Minimum

Commitments and Contingencies

Minimum required payments for this notice period

$ 5,300,000

£ 4.4

German tax authority

Commitments and Contingencies

Settlement expense

$ 329,000

€ 277,000

Received tax bills

$ 232,000

€ 222,000

State and local jurisdiction

Commitments and Contingencies

Settlement expense

$ 272,000

€ 231,000

Additional late fees

$ 535,000

€ 513,000

Income Taxes - Summary of Defer

Income Taxes - Summary of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Deferred tax asset
Net operating loss carryforward	$ 202,525	$ 193,605
Research and development credit carry forwards	17,989	17,982
Capitalized research and experimental expenditures	9,144
Stock based compensation and other	18,021	23,637
Total deferred tax assets	247,679	235,224
Valuation Allowance	$ (247,679)	$ (235,224)

Income Taxes - Reconcilation of

Income Taxes - Reconcilation of U.S. Federal Statutory Tax Expense (Benefit) (Details)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Income Taxes
Statutory federal income tax rate	21%	21%
State taxes, net of federal tax benefit	4.60%	(2.00%)
Tax rate differential on foreign income	(0.20%)	0.10%
Derivative gain or loss	(5.20%)	(28.00%)
Expiration of net operating losses	(2.60%)	3.90%
Other permanent items and true ups	(6.00%)	0.10%
R&D Credit	0%	0.30%
Change in rate	0.10%	0%
Change in valuation allowance	(11.70%)	4.60%
Income tax provision (benefit)	0%	0%

Income Taxes - Summary of Tax P

Income Taxes - Summary of Tax Provision Benefit (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Federal
Current	$ 0	$ 0
Deferred	(8,868)	(5,765)
State
Current	0	0
Deferred	(3,097)	(1,975)
Foreign
Deferred	(489)	(599)
Change in valuation allowance	12,454	8,339
Income tax provision (benefit)	$ 0	$ 0

Income Taxes - Additional infor

Income Taxes - Additional information (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Taxes
Operating Loss Carryforwards	$ 709,900
Deferred Tax Assets Tax Credit Carry Forward Unused Research And Development	527,400
Deferred Tax Assets, Tax Credit Carryforwards, Research	17,989	$ 17,982
Deferred Tax Assets, Tax Credit Carryforwards, Foreign	39,700
Amounts accrued for penalties or interest	0	$ 0	$ 0
U.K
Income Taxes
Deferred Tax Assets, Tax Credit Carryforwards, Foreign	21,400
Germany
Income Taxes
Deferred Tax Assets, Tax Credit Carryforwards, Foreign	17,900
Netherland
Income Taxes
Deferred Tax Assets, Tax Credit Carryforwards, Foreign	400
Foreign Tax Authorities | Germany
Income Taxes
Operating Loss Carryforwards	$ 182,500

Subsequent Events (Details)

Subsequent Events (Details) - USD ($)

1 Months Ended

2 Months Ended

3 Months Ended

12 Months Ended

Feb. 15, 2023

Aug. 12, 2022

Jan. 31, 2023

Feb. 28, 2023

Feb. 24, 2023

Dec. 31, 2021

Dec. 31, 2022

Dec. 31, 2021

Dec. 31, 2020

Jan. 09, 2023

Nov. 22, 2021

Jan. 15, 2021

Dec. 31, 2019

Subsequent Events

Increase in common stock shares authorized

500,000,000

Common stock, par value (in dollars per share)

$ 0.001

$ 0.001

$ 0.001

Preferred stock, par value (in dollars per share)

$ 0.001

$ 0.001

$ 0.001

Proceeds from exercise of warrants and stock options

$ 329,000

$ 11,105,000

$ 19,975,000

$ 13,915,000

Aggregate principal amount

$ 35,243,000

$ 22,454,000

$ 35,243,000

Number of shares issued to employees

5,100,000

Amount of debt converted

$ 5,600,000

Stock issued on exercise of warrants

45,300,000

86,900,000

Number of Warrants, cashless warrants exercise

35,951

19,743

8,631

Warrants exercise price

$ 0.24

$ 2

Number of warrants outstanding

225,469

141,048

225,469

331,753

359,473

Cash deposit recognized as cash advance

$ 2,600,000

Cashless Warrants Exercise

Subsequent Events

Stock issued on exercise of warrants

29,000,000

20,400,000

Number of Warrants, cashless warrants exercise

8,200,000

24,500,000

Common Stock

Subsequent Events

Stock issued on exercise of warrants

5,200,000

Number of Warrants, cashless warrants exercise

8,600,000

Common Stock | Cashless Warrants Exercise

Subsequent Events

Number of Warrants, cashless warrants exercise

36,000,000

Minimum

Subsequent Events

Warrants exercise price

$ 0.175

$ 0.18

$ 0.175

Minimum | Cashless Warrants Exercise

Subsequent Events

Warrants exercise price

0.20

0.18

0.20

Minimum | Common Stock | Cashless Warrants Exercise

Subsequent Events

Warrants exercise price

0.23

Maximum

Subsequent Events

Warrants exercise price

0.40

0.85

0.40

Maximum | Cashless Warrants Exercise

Subsequent Events

Warrants exercise price

$ 0.52

0.52

$ 0.52

Maximum | Common Stock | Cashless Warrants Exercise

Subsequent Events

Warrants exercise price

$ 0.34

Series C convertible preferred stock | Common Stock

Subsequent Events

Conversion of Series C Preferred share

25

Series C convertible preferred stock | Minimum

Subsequent Events

Purchase price

$ 15

Series C convertible preferred stock | Minimum | Common Stock

Subsequent Events

Purchase price

0.60

Series C convertible preferred stock | Maximum

Subsequent Events

Purchase price

21.25

Series C convertible preferred stock | Maximum | Common Stock

Subsequent Events

Purchase price

0.85

Series C convertible preferred stock | Series C Subscription Agreements | Series C Investors

Subsequent Events

Purchase price

$ 16.15

Multiple Notes | Minimum

Subsequent Events

Extended term of debt

2 months

2 months

Multiple Notes | Maximum

Subsequent Events

Extended term of debt

4 months

4 months

Notes

Subsequent Events

Aggregate principal amount

$ 4,400,000

$ 600,000

$ 4,400,000

$ 16,500,000

Number of shares issued to lenders in lieu of cash payments

18,100,000

Conversion of share settled debt into common stock

$ 13,800,000

Notes | Series C convertible preferred stock

Subsequent Events

Aggregate principal amount

$ 3,400,000

Number of shares issued to lenders in lieu of cash payments

200,000

Conversion of share settled debt into common stock

$ 3,500,000

Subsequent event

Subsequent Events

Common stock, par value (in dollars per share)

$ 0.001

Number of warrants outstanding

37,700,000

Subsequent event | Common Stock

Subsequent Events

Number of shares issued to lenders in lieu of cash payments

150,000

3,400,000

Interest expense on debt

$ 100,000

Subsequent event | Common Stock | Cashless Warrants Exercise

Subsequent Events

Stock issued on exercise of warrants

600,000

Number of Warrants, cashless warrants exercise

1,100,000

Subsequent event | Minimum

Subsequent Events

Increase in common stock shares authorized

1,200,000,000

Subsequent event | Minimum | Common Stock | Cashless Warrants Exercise

Subsequent Events

Warrants exercise price

$ 0.34

Subsequent event | Maximum

Subsequent Events

Increase in common stock shares authorized

1,700,000,000

Subsequent event | Maximum | Common Stock | Cashless Warrants Exercise

Subsequent Events

Warrants exercise price

$ 0.35

Subsequent event | Series C Subscription Agreements | Series C Investors

Subsequent Events

Number of common stock issued upon warrant exercises

146,948

Subsequent event | Series C convertible preferred stock

Subsequent Events

Preferred stock, par value (in dollars per share)

$ 0.001

Proceeds from exercise of warrants and stock options

$ 2,400,000

Conversion of Series C Preferred share

25

Conversion effective period

15 days

Aggregate principal amount

$ 700,000

Number of shares issued to employees

43,401

Amount of debt converted

$ 100,000

Shares converted

6,000

Subsequent event | Multiple Notes

Subsequent Events

Additional proceeds from equity subscriptions and warrant exercises

$ 2,500,000

Subsequent event | Multiple Notes | Common Stock

Subsequent Events

Conversion of share settled debt into common stock

$ 2,100,000

Subsequent event | Notes Agreement

Subsequent Events

Number of common stock issued upon warrant exercises

300,000

Value of common stock issued upon warrant exercises

$ 100,000