0001789769-25-000017 | 10-K | XBRL Viewer

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Income Taxes - Unrecognized Tax Benefits (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2024 USD ($)
Unrecognized Tax Benefits [Roll Forward]
Balance at December 31, 2023	$ 2,339
Additions in 2024	0
Balance at December 31, 2024	$ 2,339

Fair Value Measurement - Narrative (Details) $ in Millions	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2020
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Prepaid expenses and other current assets	Prepaid expenses and other current assets
Measurement Input, Discount Rate
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Measurement input			0.08
Minimum
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Payment probability			0.00%
Maximum
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Payment probability			5.00%
Secured Mortgage Loan \| Level 2 \| Loans Payable
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of loan	$ 84.7	$ 72.3

Fair Value Measurement - Financial Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Financial Assets
U.S. Treasury bills	$ 104,510	$ 141,161
Fair Value, Recurring
Financial Assets
Derivative financial instrument		1,055
Total	110,142	171,061
Financial Liabilities
Contingent consideration	948	4,858
Fair Value, Recurring \| U.S. Treasury bills
Financial Assets
U.S. Treasury bills	104,510	164,322
Fair Value, Recurring \| Money market funds
Financial Assets
Money market funds	5,632	5,684
Fair Value, Recurring \| Level 1
Financial Assets
Derivative financial instrument		0
Total	5,632	5,684
Financial Liabilities
Contingent consideration	0	0
Fair Value, Recurring \| Level 1 \| U.S. Treasury bills
Financial Assets
U.S. Treasury bills	0	0
Fair Value, Recurring \| Level 1 \| Money market funds
Financial Assets
Money market funds	5,632	5,684
Fair Value, Recurring \| Level 2
Financial Assets
Derivative financial instrument		1,055
Total	104,510	165,377
Financial Liabilities
Contingent consideration	0	0
Fair Value, Recurring \| Level 2 \| U.S. Treasury bills
Financial Assets
U.S. Treasury bills	104,510	164,322
Fair Value, Recurring \| Level 2 \| Money market funds
Financial Assets
Money market funds	0	0
Fair Value, Recurring \| Level 3
Financial Assets
Derivative financial instrument		0
Total	0	0
Financial Liabilities
Contingent consideration	948	4,858
Fair Value, Recurring \| Level 3 \| U.S. Treasury bills
Financial Assets
U.S. Treasury bills	0	0
Fair Value, Recurring \| Level 3 \| Money market funds
Financial Assets
Money market funds	$ 0	$ 0

Fair Value Measurement

12 Months Ended

Dec. 31, 2024

Fair Value Disclosures [Abstract]

Fair Value Measurement

The fair value of cash and cash equivalents approximates carrying value since cash and cash equivalents consist of short-term highly liquid investments with maturities of less than three months at the time of purchase. Cash and cash equivalents are quoted market prices in active markets for identical assets and are therefore classified as Level 1 assets. Money market funds are open-end mutual funds that invest in cash, government securities, and/or repurchase agreements that are collateralized fully. To the extent that these funds are valued based upon the reported net asset value, they are categorized in Level 1 of the fair value hierarchy.

Short-term and long-term marketable securities comprised U.S. Treasury bills that are classified within Level 2 of the fair value hierarchy are valued based on other observable inputs, including broker or dealer quotations, alternative pricing sources or U.S. Government Treasury yield of appropriate term.

The following tables provide information by level for assets and liabilities that are measured at fair value on a recurring and nonrecurring basis:


	December 31, 2024
	Level 1		Level 2		Level 3		Total
	(In thousands)
Financial Assets
Money market funds	$	5,632	$	—	$	—	$	5,632
U.S. Treasury bills	—		104,510		—		104,510
Total	$	5,632	$	104,510	$	—	$	110,142
Financial Liabilities
Contingent consideration	$	—	$	—	$	948	$	948

	December 31, 2023
	Level 1		Level 2		Level 3		Total
	(In thousands)
Financial Assets
Money market funds	$	5,684	$	—	$	—	$	5,684
U.S. Treasury bills	—		164,322		—		164,322
Derivative financial instrument	—		1,055		—		1,055
Total	$	5,684	$	165,377	$	—	$	171,061
Financial Liabilities
Contingent consideration	$	—	$	—	$	4,858	$	4,858

There were no transfers in or out of Level 1, 2 and 3 measurements for the years ended December 31, 2024 and 2023. As of December 31, 2024 and 2023, there were no securities within Level 3 of the fair value hierarchy. The derivative financial instrument above relates to the interest rate swap discussed in Note 8, and is included in prepaid expenses and current assets in the consolidated balance sheets.

As of December 31, 2024 and 2023, the fair value of the Company’s Loan (as defined in Note 8) was $84.7 million and $72.3 million, respectively. The fair value was determined on the basis of its net present value and is considered Level 2 in the fair value hierarchy.

The following table sets forth a summary of the changes in the fair value of the Company’s Level 3 financial liabilities (in thousands):


	Level 3 Financial Liabilities
Fair value, beginning balance as of December 31, 2022	$	8,242
Change in fair value	(3,384)
Fair value, ending balance as of December 31, 2023	4,858
Change in fair value	(3,910)
Fair value, ending balance as of December 31, 2024	$	948

The Company’s acquisition of Immetacyte involved the potential for the payment of future contingent consideration upon the achievement of (i) certain product development milestones including, approval of studies and commencement and completion of certain product trials, or (ii) various other performance conditions including, receipt of final approval for the first marketing authorization and first commercial sale in certain geographical markets. Contingent consideration is recorded at the estimated fair value of the contingent payments on the acquisition date. The fair value of the contingent consideration is remeasured at the estimated fair value at each

reporting period with the change in fair value recognized as income or expense within research and development expense in the consolidated statements of operations and comprehensive loss.

During the year of acquisition, the Company determined the fair value of the contingent consideration by probability weighting scenarios of milestone achievements to determine the expected future contingent consideration payment, discounted to present value using an 8% discount rate based on the Company’s pre-tax cost of debt on the acquisition date. The probability of payments ranged from 0% to 5% and the timing of future payments ranged from 2026 to 2028. Determinations of the likelihood of milestone achievements, which trigger payouts related to the contingent consideration, as well as the probabilities for various scenarios used in the Company’s calculations, were based on internal unobservable projections.

During the years ended December 31, 2024 and 2023, the change of fair value related to the contingent consideration was due to the discontinuation of the ITIL-306-202 development program, the change in present value for the passage of time, as well as expected dates and probabilities of milestone achievement revisions.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

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+ Details

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 8,805	$ 9,195
Restricted cash	1,830	1,501
Marketable securities	104,510	141,161
Prepaid expenses and other current assets	9,325	8,902
Total current assets	124,470	160,759
Property, plant and equipment, net	129,406	138,684
Operating lease right-of-use assets	934	2,387
Long-term investments	0	23,161
Other long-term assets	8,757	639
Total assets	263,567	325,630
Current liabilities:
Accounts payable	659	1,212
Accrued expenses and other current liabilities	7,237	9,347
Total current liabilities	7,896	10,559
Contingent consideration	948	4,858
Operating lease liabilities, non-current	1,017	2,877
Loan payable	84,187	81,427
Other long-term liabilities	83	80
Total liabilities	94,131	99,801
Commitments and contingencies (Note 8)
Stockholders’ equity:
Preferred stock, par value $0.000001 per share; 10,000,000 shares authorized; zero shares issued and outstanding as of December 31, 2024, and 2023	0	0
Common stock, par value $0.000001 per share; 300,000,000 shares authorized; 6,525,887 and 6,503,913 shares issued and outstanding as of December 31, 2024, and 2023	0	0
Additional paid-in capital	824,780	807,158
Accumulated other comprehensive loss	(228)	(348)
Accumulated deficit	(655,116)	(580,981)
Total stockholders’ equity	169,436	225,829
Total liabilities and stockholders’ equity	$ 263,567	$ 325,630

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Cash flows from operating activities:
Net loss	$ (74,135)	$ (156,087)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	17,257	18,166
Non-cash lease expense	212	640
Foreign exchange remeasurement loss (gain)	275	(680)
Impairment of fixed assets	4,325	60,088
Impairment of right-of-use assets	827	7,724
Change in fair value of contingent consideration	(3,910)	(3,384)
Depreciation	3,610	4,756
In-process research and development expenses	10,000	0
Accretion on invested securities	(4,327)	(6,775)
Non-cash interest expense	962	1,015
Non-cash loss on debt extinguishment	415	0
Change in fair value of derivative financial instrument	1,055	1,147
Loss on disposals of property and equipment	343	377
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(221)	(241)
Other long-term assets	(8,630)	1,543
Accounts payable	(556)	(1,129)
Operating lease liabilities	(1,377)	(1,404)
Long-term liabilities	77	(12)
Accrued expenses and other current liabilities	(1,898)	(7,773)
Net cash used in operating activities	(55,696)	(82,029)
Cash flows from investing activities:
Purchase of marketable securities	(134,009)	(301,466)
Maturities of marketable securities	198,100	361,700
Purchases of property, plant and equipment	0	(20,663)
Cash received from held for sale assets	866	1,557
Acquired in-process research and development	(10,000)	0
Cash received from termination of derivative financial instrument	605	0
Purchase of derivative financial instrument	(1,588)	0
Net cash provided by investing activities	53,974	41,128
Cash flows from financing activities:
Proceeds on Construction Loan Agreements	0	8,669
Proceeds from the Loan	85,600	0
Principal payments on Construction Loan Agreements	(82,838)	(587)
Proceeds from exercise of stock options	365	0
Loan agreement closing costs	(1,372)	0
Net cash provided by financing activities	1,755	8,082
Net increase (decrease) in cash, cash equivalents, and restricted cash	33	(32,819)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(94)	(201)
Cash, cash equivalents and restricted cash—beginning of period	10,696	43,716
Cash, cash equivalents and restricted cash—end of period	10,635	10,696
Supplemental disclosure of cash flow information:
Cash paid for interest, net of amounts capitalized	$ 7,997	$ 6,639

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2024

Commitments and Contingencies Disclosure [Abstract]

Schedule of Lease Cost

The Company’s lease costs consist of the following (in thousands):


	Year Ended December 31,
	2024		2023
Operating lease cost	$	1,315	$	2,185
Variable lease cost	801		1,170
Total lease cost	$	2,116	$	3,355

The following table summarizes cash flow information related to the Company’s lease obligations (in thousands):


	Year Ended December 31,
	2024		2023
Cash paid for operating lease liabilities	$	2,279	$	2,308

The following table summarizes the Company’s lease assets and liabilities (in thousands):


	December 31,
	2024		2023
Operating lease right-of-use assets	$	934	$	2,387
Current operating lease liabilities	$	1,682	$	1,750
Non-current operating lease liabilities	$	1,017	$	2,877

The following table summarizes other supplemental information related to the Company’s lease obligations:


	December 31,
	2024		2023
Weighted-average remaining lease term (in years)	1.70		2.60
Weighted-average discount rate	6.75	%	6.75	%

Schedule of Future Minimum Lease Payments

Future minimum lease payments under operating lease liabilities were (in thousands):


	December 31, 2024
2025	$	1,817
2026	1,219
Total future lease payments	3,036
Less: imputed interest	337
Total lease liability balance	2,699
Less: current portion of operating lease liabilities	1,682
Total operating lease liabilities, non-current	$	1,017

Schedule of Lease Income Related to the Operating Lease

The Lease is classified as an operating lease and revenue is recognized on a straight-line basis and will be recorded within the consolidated statements of operations and comprehensive loss in the line item “Other rental income” as this is not a part of the Company’s core operations. Rental income related to the operating lease was as follows (in thousands):


	Year Ended December 31,
	2024		2023
Rental income	$	4,267	$	—

Schedule of Future Fixed Contractual Lease Payments to be Received

Approximate future straight-lined contractual lease income to be recognized under a non-cancelable operating lease in effect as of December 31, 2024, are as follows (in thousands):


	December 31, 2024
2025	$	8,968
2026	8,968
2027	8,968
2028	8,968
Thereafter	94,910
Total	$	130,782

Schedule of Net Carrying Amount of the Debt

The net carrying amount of the liability component of the debt was as follows (in thousands):


	December 31,
	2024		2023
Principal amount	$	85,600	$	82,837
Unamortized debt issuance cost	(1,413)		(1,410)
Net carrying amount	$	84,187	$	81,427

Schedule of Interest Expense Related to the Debt

The following table sets forth the interest expense recognized related to the debt (in thousands):


	Year Ended December 31,
	2024		2023
Contractual interest expense	$	7,997	$	4,214
Amortization of debt issuance cost	995		995
Total interest expense related to the Debt	$	8,992	$	5,209

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

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+ Details

Income Taxes

12 Months Ended

Dec. 31, 2024

Income Tax Disclosure [Abstract]

Income Taxes

The geographical breakdown of loss before provision for income taxes is as follows (in thousands):


	Year Ended December 31,
	2024		2023
Domestic	$	(60,382)	$	(144,570)
Foreign	(13,753)		(11,517)
Loss before income taxes	$	(74,135)	$	(156,087)

The company has nil income tax expense for both Domestic and Foreign jurisdictions for the years ended December 31, 2024 and 2023.

The following table presents a reconciliation of the Company’s statutory federal income tax rate and effective tax rate:


	Year Ended December 31,
	2024		2023
U.S. federal taxes at statutory rate	21.0	%	21.0	%
Stock-based compensation	(6.7)	%	(1.8)	%
Permanent differences and other	0.3	%	0.8	%
Statutory tax rate differences	4.4	%	3.4	%
Change in valuation allowance	(19.0)	%	(23.4)	%
Total	—	%	—	%

The components of deferred tax liabilities consist of the following (in thousands):


	Year Ended December 31,
	2024		2023
Deferred tax assets:
Net operating loss carryforwards	$	95,773	$	88,408
Research and development credits	4,915		4,915
Accrued compensation and benefits	646		107
Stock-based compensation	2,008		3,570
Capitalized research and development	20,920		19,432
Other temporary differences	10,201		8,279
Intangible assets	2,841		97
Fixed assets	4,827		1,496
Other	426		335
Total gross deferred tax assets	142,557		126,639
Less: valuation allowance	(141,367)		(126,639)
Total deferred tax assets, net	1,190		—
Deferred tax liabilities:
Rent receivable	(1,190)		—
Total gross deferred tax liabilities	(1,190)		—
Net deferred tax assets (liabilities)	$	—	$	—

The components of unrecognized tax benefits consist of the following (in thousands):


Balance at December 31, 2023	$	2,339
Additions in 2024	—
Balance at December 31, 2024	$	2,339

In assessing the realizability of deferred tax assets, the Company considers whether it is more likely than not that some portion or all of the deferred tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences become deductible. Due to the uncertainty of the business in which the Company operates, projections of future profitability are difficult and past profitability is not necessarily indicative of future profitability. The Company does not believe it is more likely than not that the deferred tax assets will be realized, and accordingly, the valuation allowance increased $14.7 million for the year ended December 31, 2024. As of December 31, 2024, the Company had net operating loss carryforwards for federal income tax purposes of $348.3 million, which will carryforward indefinitely, but may only offset 80% of the Company’s taxable income. This limitation on the net operating loss may require the Company to pay federal income taxes in future years despite generating a loss for federal income tax purposes in prior years. In addition, the Company has $132.3 million of California net operating loss carryforwards available to reduce future state taxable income as of the year ended December 31, 2024. The state net operating loss carryforwards will begin to expire, if not utilized, in 2043.

The Company has R&D credits of $4.1 million, and $3.7 million for federal and California, respectively, as of December 31, 2024. The federal R&D credits expire in 2042 and the California R&D credits carryforward indefinitely.

The Company files income tax returns in the U.S. federal jurisdiction, various states where the Company has employees and/or significant business activities, and the United Kingdom. As of December 31, 2024, the Company’s federal and state returns through 2021 are still open to examination. The UK returns starting from 2023 are open to examination. The Company had uncertain tax positions as of December 31, 2023 of $2.3 million and this

balance remained unchanged during December 31, 2024. The Company does not anticipate that the amount of existing unrecognized tax benefits will significantly increase or decrease during the next 12 months. The Company had no accrued interest or penalties related to uncertain tax positions as of December 31, 2024.

The Company has not completed a Section 382 study to assess whether an ownership change has occurred or whether there have been multiple ownership changes since the Company’s formation. Pursuant to Internal Revenue Code Sections 382 and 383, annual use of the Company’s net operating loss and research and development tax credit carryforwards may be limited in the event a cumulative change in ownership of more than 50% occurs within a three-year period. Due to the existence of the valuation allowance, limitations created by future ownership changes, if any, are not anticipated to impact the Company’s effective tax rate.

- Definition

The entire disclosure for income tax.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
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+ Details

Commitments and Contingencies - Net Carrying Amount of the Liability Component of the Debt (Details) - Secured Mortgage Loan - Loans Payable - USD ($)	Dec. 31, 2024	Dec. 31, 2023	Jun. 30, 2022
Debt Instrument [Line Items]
Principal amount	$ 85,600,000	$ 82,837,000	$ 52,100,000
Unamortized debt issuance cost	(1,413,000)	(1,410,000)
Net carrying amount	$ 84,187,000	$ 81,427,000

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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+ Details

- Definition

Amount, after deduction of unamortized premium (discount) and debt issuance cost, of long-term debt. Excludes lease obligation.

+ References + Details

Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2024

Investments, Debt and Equity Securities [Abstract]

Schedule of Marketable Securities and Long-Term Investments

Marketable securities and long-term investments classified as available-for-sale on December 31, 2024 and 2023 consisted of the following (in thousands):


	December 31, 2024
	Maturity	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
U.S. Treasury bills	Less than one year	$	104,445	$	99	$	(34)	$	104,510


	December 31, 2023
	Maturity	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
U.S. Treasury bills	Less than one year	$	141,075	$	86	$	—	$	141,161
U.S. Treasury bills	Between one and two years	23,134		27		—		23,161
		$	164,209	$	113	$	—	$	164,322

- Definition

Tabular disclosure of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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+ Details

Fair Value Measurement - Level 3 Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	$ 4,858	$ 8,242
Change in fair value	(3,910)	(3,384)
Fair value, ending balance	$ 948	$ 4,858

Corporate Restructuring - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Restructuring Cost and Reserve [Line Items]
Total restructuring and impairment charges	$ 7,493	$ 72,012
Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Total restructuring and impairment charges	7,493	$ 72,012
Restructuring charges	$ 2,900

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References + Details

Stock-Based Compensation - Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	$ 17,257	$ 18,166
Research and development expense
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	2,066	1,549
General and administrative expense
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	$ 15,191	$ 16,617

Commitments and Contingencies - Schedule of Lease Income Related to the Operating Lease (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Other rental income	$ 4,267	$ 0

Stock-Based Compensation - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2024	Dec. 31, 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Additional shares authorized (in shares)	433,000	325,196	0
Shares available for future issuance (in shares)		512,993
Term to authorize additional shares		10 years
Percentage of outstanding capital stock		5.00%
Options exercised (in shares)		(21,974)	0
Intrinsic value of stock options exercised		$ 100	$ 0
Options granted, weighted-average grant date fair value (in dollars per share)		$ 22.85	$ 8.74
Unrecognized compensation cost		$ 16,600	$ 22,400
Unrecognized compensation cost, recognition period		2 years 3 months	1 year 4 months 20 days
Options granted (in shares)		546,800	271,921
Total stock-based compensation expense		$ 17,257	$ 18,166
Minimum number of additional shares to be authorized (in shares)	123,700
Stock options to purchase common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield		0.00%	0.00%
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost		$ 0	$ 5,100
Options granted (in shares)		0	4,796
Total stock-based compensation expense		$ 0
Employee Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of outstanding capital stock	1.00%
Shares authorized (in shares)	61,850
Weighted Average \| Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			4 months 13 days
Share-based Payment Arrangement, Tranche One \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		4 years
Share-based Payment Arrangement, Tranche One \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		1 year
2018 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future issuance (in shares)		209,722

Segment Reporting

12 Months Ended

Dec. 31, 2024

Segment Reporting [Abstract]

Segment Reporting

The Company manages its business activities on a consolidated basis and has one reportable segment relating to the research and development of its novel therapies. The Chief Executive Officer, who serves as the Company’s chief operating decision maker (“CODM”), is responsible for the overall supervision, direction, and management of the business and its officers.

The CODM reviews net loss, as reported in the consolidated statement of operations and comprehensive loss, as well as the progress of the Company’s program(s). The CODM does not review assets in evaluating the results of the segment, and therefore, such information is not presented. The accounting policies of the segment are the same as those described in Note 2.

The following table is a summary of the segment loss, including significant segment expenses for the years ended December 31, 2024 and 2023 (in thousands):


	Year Ended December 31,
	2024		2023
In-process research and development	$	10,000	$	—
AXN-2510/IMM2510 and AXN-27M/IMM27M	1,291		—
Other program expenses(1) (2)	9,901		35,567
General and administrative(1)	41,246		46,834
Restructuring charges	7,493		72,012
Depreciation	3,610		4,756
Interest income	(6,987)		(8,866)
Interest expense	8,992		5,209
Other (income) expense, net	(1,411)		575
Segment and consolidated net loss	$	74,135	$	156,087

______________________________________________________________

(1) Depreciation expense is removed from both “General and administrative” and “Other program expense” and is disclosed separately.

(2) Other program expenses consist of costs related to the Company’s past development of its CoStAR-TIL technology.

The Company’s long-lived tangible assets, as well as the Company’s operating lease right-of-use assets, recognized on the consolidated balance sheets is as follows (in thousands):


	Year Ended December 31,
	2024		2023
United States	$	130,340	$	133,974
United Kingdom	$	—	$	7,097

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

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+ Details

Stock-Based Compensation - Valuation Assumption (Details) - Stock option - $ / shares	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility, minimum	86.92%	76.19%
Expected volatility, maximum	100.06%	77.56%
Risk-free interest rate, minimum	3.53%	3.54%
Risk-free interest rate, maximum	4.57%	4.01%
Expected dividend yield	0.00%	0.00%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	5 years 3 months 7 days	5 years 3 months 10 days
Fair Value of Common Stock (in dollars per share)	$ 10.50	$ 11.18
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	6 years 29 days	6 years 29 days
Fair Value of Common Stock (in dollars per share)	$ 66.10	$ 15.20

Corporate Restructuring

12 Months Ended

Dec. 31, 2024

Restructuring and Related Activities [Abstract]

Corporate Restructuring

Corporate Restructuring Plan

In January 2023, the Board of Directors approved a restructuring plan (referred to as the “2023 Plan”) and the Company announced the consolidation of the ITIL-306 Phase 1 clinical trial and related manufacturing of CoStAR-TIL to its operations in Manchester, UK and stopped recruiting for the ITIL-306 clinical trial.

In January 2024, the Board of Directors approved a comprehensive restructuring plan, which included the closure of the Company’s UK manufacturing facility and clinical trial operations. In September 2024, the Board of Directors approved additional UK restructuring actions, which resulted in the elimination of the majority of the remaining UK workforce in the fall of 2024, with the remaining reduction and restructuring activities substantially completed by the end of 2024. Collectively, these actions are referred to as the “2024 Plan.”

The 2023 Plan and 2024 Plan are collectively referred to as the “Plan.”

Restructuring and Impairment Charges

As a result of the Plan, the Company recorded charges of $7.5 million and $72.0 million within the consolidated statements of operations and comprehensive loss in the line item “restructuring and impairment charges” for the years ended December 31, 2024 and 2023, respectively.

These charges relate to asset impairments, contract terminations, severance payments and other employee-related costs incurred. The following table summarizes the restructuring and impairment charges by category (in thousands):


	Year Ended December 31,
	2024		2023
Asset impairment for leasehold improvements	$	343	$	2,644
One-time employee termination benefits	2,721		1,844
Building and construction work in progress impairment	—		41,542
Contract terminations	(723)		1,987
Right-of-use asset impairment	827		7,724
Impairment of long-lived assets held for sale	4,325		16,271
Total restructuring and impairment charges	$	7,493	$	72,012

Restructuring Liability

As a result of the Plan, the restructuring liability was recorded in the consolidated balance sheets under “Accrued expenses and other current liabilities” and was measured at the amount expected to be paid, or that was paid. During the year ended December 31, 2024, the Company paid $2.9 million of restructuring costs, and expects to pay the remainder of the restructuring costs by the first quarter of 2025. The following table shows the liability related to the Plan (in thousands):


	Employee Benefits		Contract Terminations		Total
Restructuring liability as of December 31, 2023	$	—	$	3,136	$	3,136
Additions, net	2,420		733		3,153
Payments	(2,289)		(578)		(2,867)
Adjustments	—		(1,349)		(1,349)
Total restructuring liability as of December 31, 2024	$	131	$	1,942	$	2,073

CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive (Loss) Income	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2022		6,503,913
Beginning balance at Dec. 31, 2022	$ 363,605	$ 0	$ 788,992	$ (493)	$ (424,894)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	18,166		18,166
Net loss	(156,087)				(156,087)
Other comprehensive income	$ 145			145
Ending balance (in shares) at Dec. 31, 2023	6,503,913	6,503,913
Ending balance at Dec. 31, 2023	$ 225,829	$ 0	807,158	(348)	(580,981)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares of common stock issued in connection with incentive stock plan (in shares)		21,974
Shares of common stock issued in connection with incentive stock plan	365		365
Stock-based compensation	17,257		17,257
Net loss	(74,135)				(74,135)
Other comprehensive income	$ 120			120
Ending balance (in shares) at Dec. 31, 2024	6,525,887	6,525,887
Ending balance at Dec. 31, 2024	$ 169,436	$ 0	$ 824,780	$ (228)	$ (655,116)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-3

Reference 11: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
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-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(g)(1)(ii))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480678/235-10-S99-1

Reference 12: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 323
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481687/323-10-50-3

Reference 13: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 825
-SubTopic 10
-Name Accounting Standards Codification
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-Paragraph 28
-Subparagraph (f)
-Publisher FASB
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-Paragraph 2
-Subparagraph (SAB Topic 4.E)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480418/310-10-S99-2

+ Details

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2024

Accounting Policies [Abstract]

Basis of Presentation

The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) and include the accounts of the Company and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation.

Use of Estimates

The preparation of the consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of expenses during the reporting period. Significant estimates and assumptions made in the accompanying consolidated financial statements include but are not limited to the fair value of contingent consideration payable, assets held for sale, fair value of the Company’s building, contract termination liabilities, and stock-based compensation. The Company evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors and adjusts those estimates and assumptions when facts and circumstances dictate. Actual results could differ from those estimates.

Concentration of Credit Risk

Financial Instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash and cash equivalents, restricted cash, marketable securities and long-term investments. The Company’s cash and cash equivalents are held by two financial institutions in the United States (“U.S.”) and one financial institution in the United Kingdom (“UK”), which management believes to be financially sound, and accordingly, minimal credit risk exists with respect to the financial institutions. At times, the Company’s deposits held in the U.S. and UK may exceed the Federal Depository Insurance Corporation and Financial Services Compensation Scheme, respectively, insured limits.

Risks and Uncertainties

The Company is subject to a number of risks similar to other development-stage biopharmaceutical companies, including but not limited to, dependency on the clinical and commercial success of its product candidates, ability to obtain regulatory approval of its product candidates, uncertainty of broad adoption of its approved products, if any, by physicians and patients, manufacturing, the need to obtain adequate additional funding, significant competition, and protection of its intellectual property portfolio.

Segments

Operating segments are identified as components of an entity for which separate discrete financial information is available and that is regularly reviewed by the chief operating decision maker, the Company’s Chief Executive Officer, in deciding how to allocate resources to an individual segment and in assessing performance. The Company has determined it operates in a single operating segment and has one operating segment. See Note 3 for further information.

Cash, Cash Equivalents, Restricted Cash, Marketable Securities and Long-Term Investments

Cash, Cash Equivalents, Restricted Cash, Marketable Securities, and Long-Term Investments

The Company considers all highly liquid investments purchased with original maturities of three months or less from the purchase date to be cash equivalents. Cash equivalents include amounts invested in money market accounts.

Restricted cash consists of a cash reserve which serves as collateral for the Company’s Construction Loan Agreements (as defined in Note 8) during the year ended December 31, 2023 and the Loan (as defined in Note 8) during the year ended December 31, 2024 on the consolidated balance sheet as of December 31, 2024. There was $1.8 million and $1.5 million restricted cash as of December 31, 2024 and 2023, respectively, on the consolidated balance sheet.

Marketable Securities

The Company’s investments in marketable securities and long-term investments have been classified and accounted for as available-for-sale. The Company classifies its maturities as either short-term or long-term based on each instrument’s underlying contractual maturity date, which are carried at their fair values based on the quoted market prices of the securities. Unrealized gains and losses are reported as accumulated other comprehensive income (loss). Realized gains and losses on available-for-sale securities are included in net loss in the period earned or incurred. As of December 31, 2024 and 2023, marketable securities consisted of U.S. Treasury bills.

The Company periodically reviews whether its securities may be other-than-temporarily impaired, including whether or not (i) the Company has the intent to sell the security or (ii) it is more likely than not that the Company will be required to sell the security before its anticipated recovery. If one of these factors is met, the Company will record an impairment loss associated with its impaired investment. The impairment loss will be recorded as a write-down of investments in the consolidated balance sheets and a realized loss within other expense in the consolidated statements of operations and comprehensive loss. For the years ended December 31, 2024 and 2023, there were no impairment losses for the investments.

Fair Value Measurement

Assets and liabilities recorded at fair value on a recurring basis in the balance sheets are categorized based upon the level of judgment associated with the inputs used to measure their fair values. Fair value is defined as the exchange price that would be received for an asset or an exit price that would be paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value maximize the use of observable inputs and minimize the use of unobservable inputs. The Company measures fair value based on a three-tier hierarchy, which prioritizes the inputs used in the valuation methodologies in measuring fair value as follows:

Level 1 —Observable inputs such as unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date.

Level 2 —Inputs (other than quoted prices included in Level 1) are either directly or indirectly observable for the assets or liabilities. These include quoted prices for similar assets or liabilities in active markets and quoted prices for identical or similar assets or liabilities in markets that are not active.

Level 3 —Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

In determining fair value, the Company utilize quoted market prices, or valuation techniques that maximize the use of unobservable inputs to the extent possible as well as considers counterparty credit risk in its assessment of fair value.

Property, Plant and Equipment, Net

Property, plant and equipment, with the exception of land, is stated at cost less accumulated depreciation. Depreciation is computed on a straight-line basis over the estimated useful lives of the related assets. Maintenance and repairs are charged to operations as incurred. Upon sale or retirement of assets, the cost and related accumulated depreciation are removed from the balance sheets and the resulting gain or loss is reflected in the consolidated statement of operations and comprehensive loss. The estimated useful lives of the Company’s property, plant and equipment are as follows:


Laboratory equipment			5 years
Manufacturing equipment			5 years
Office and computer equipment			3 years
Buildings			35 years
Leasehold improvements			Shorter of remaining lease term or estimated useful life

The Company owns land and buildings and, as described in Note 4, the clinical and commercial manufacturing building has been completed and has been leased. See Note 8 for details. A variety of costs were incurred in the development of a property. After determination is made to capitalize a cost, it is allocated to the specific component of a project that is benefited. The capitalized costs include pre-construction costs essential to the development of the property, development costs, and construction costs. When the Tarzana development project was completed and available for occupancy, the Company ceased capitalization of costs other than costs to improve the functionality or

extend the useful lives of property, plant and equipment included as part of the project. During the year ended December 31, 2024 and 2023, the Company recorded a building impairment of zero and $41.5 million, respectively, recognized in the consolidated statements of operations and comprehensive loss in the line item “restructuring and impairment charges.” See Note 4 for more information.

Assets Held for Sale

The Company classifies long-lived assets or disposal groups to be sold as held for sale in the period in which all of the following criteria are met: management, having the authority to approve the action, commits to a plan to sell the asset or disposal group; the asset or disposal group is available for immediate sale in its present condition subject only to terms that are usual and customary for sales of such assets or disposal group; the sale of the asset or disposal group is probable, and transfer of the asset or disposal group is expected to qualify for recognition as a completed sale within one year, except if events or circumstances beyond the Company’s control extend the period of time required to sell the asset or disposal group beyond one year; the asset or disposal group is being actively marketed for sale at a price that is reasonable in relation to its current fair value; and actions required to complete the plan to sell have been initiated.

The Company initially measures a long-lived asset or disposal group that is held for sale at the lower of its carrying value or fair value less any costs to sell. Fair value is estimated by the Company through evaluations of quoted market prices received for other comparable held for sale assets sold by the Company. Any loss resulting from this measurement is recognized in the period in which the held for sale criteria are met. Conversely, gains are not recognized on the sale of a long-lived asset or disposal group until the date of sale. The Company assesses the fair value of a long-lived asset or disposal group less any costs to sell each reporting period it remains classified as held for sale and reports any subsequent changes as an adjustment to the carrying value of the asset or disposal group, as long as the new carrying value does not exceed the carrying value of the asset at the time it was initially classified as held for sale. Upon determining that a long-lived asset or disposal group meets the criteria to be classified as held for sale, the Company ceases depreciation and reports long-lived assets in the line item “assets held for sale” in its consolidated balance sheet.

Impairment of Long-Lived Assets

The Company reviews its long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable or that the useful life is shorter than originally estimated. Recoverability of assets is measured by comparing the carrying amount of an asset to future undiscounted net cash flows expected to be generated by the asset over its remaining useful life. If such assets are impaired, the impairment recognized is measured by the amount by which the carrying amount of the assets exceeds the fair value of the assets. If the useful life is shorter than originally estimated, the Company depreciates or amortizes the remaining carrying value over the revised shorter useful life. Assets to be disposed of by sale are reflected at the lower of their carrying amount or fair value less costs to sell. To date, the Company has recorded impairment losses on long-lived assets associated with a sustained decrease in the Company’s stock price and in connection with the Plan as defined below in Note 13. The Company recognized a non-cash impairment charge of $0.3 million during the year ended December 31, 2024 and $2.6 million during the year ended December 31, 2023 related to leasehold improvements. Additionally, the Company recognized impairment charges of $41.5 million for the year ended December 31, 2023 relating to the Tarzana facility. These impairment charges were recorded in the consolidated statements of operations and comprehensive loss in the line item “restructuring and impairment charges.” See Notes 8 and 13 for more information.

Grant Proceeds

The Company receives government grants in the UK for the furtherance of certain research and development projects. Grant proceeds are recognized when all conditions of such grants are fulfilled or there is a reasonable

assurance that they will be fulfilled. Grant proceeds are classified as a reduction of research and development expenses.

Research and Development Expenses

Research and development costs are expensed as incurred. Clinical trial and other development costs incurred by third parties are expensed as the contracted work is performed. The Company accrues for costs incurred as the services are being provided by monitoring the status of the trial or project and the invoices received from its external service providers. The Company adjusts its accrual as actual costs become known. Where contingent milestone payments are due to third parties under research and development arrangements or license agreements, the milestone payment obligations are expensed when the milestone results are achieved.

Stock-Based Compensation

The Company measures its stock-based awards granted to employees, non-employee directors, consultants and independent advisors based on the estimated grant date fair value of the awards. For stock-based awards with only service conditions, compensation expense is recognized over the requisite service period using the straight-line method. For stock-based awards that include performance conditions, compensation expense is not recognized until the performance condition is probable to occur. The Company uses the Black-Scholes option pricing model to estimate the fair value of its stock-based awards. The Black-Scholes option pricing model requires the Company to make assumptions and judgements about the variables used in the calculations, including the fair value of common stock, expected term, expected volatility of the Company’s common stock, risk-free interest rate and expected dividend yield. The Company accounts for forfeitures of stock-based awards as they occur.

Income Taxes

Income taxes are accounted for using the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts or existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using the enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period of enactment. The Company records a valuation allowance to reduce deferred tax assets to an amount expected to be realized.

The Company recognizes the tax benefit from an uncertain tax position if it is more likely than not that the tax position will be sustained upon examination by the tax authorities, based on the merits of the position. The Company’s policy is to recognize interest and penalties related to the underpayment of income taxes as a component of income tax expense or benefit. To date, there have been no interest or penalties charged in relation to the unrecognized tax benefits.

Foreign Currency

The Company’s reporting currency is the U.S. dollar. The functional currency of the Company’s subsidiary located in the United Kingdom is the British pound sterling. Balance sheets prepared in the functional currency are translated to the reporting currency at exchange rates in effect at the end of the accounting period, except for stockholders’ deficit accounts, which are translated at rates in effect when these balances were originally recorded. Revenue and expense accounts are translated using an average exchange rate in effect during the period. The resulting foreign currency translation adjustments are recorded as a separate component of accumulated other comprehensive loss in the accompanying consolidated balance sheets.

Gains and losses resulting from exchange rate changes on intercompany transactions denominated in a currency other than the local currency are included in earnings as incurred as the related amounts are expected to be repaid in the foreseeable future.

Net Loss Per Share

Basic net loss per share is calculated by dividing the net loss by the weighted-average number of shares of the Company’s common stock outstanding for the period, without consideration for potential dilutive shares of common stock. For purposes of the diluted net loss per share calculation, convertible preferred stock and common stock options are considered to be potentially dilutive securities. Diluted net loss per share is the same as basic net loss per share for each period presented since the effects of potentially dilutive securities are antidilutive given the net loss of the Company.

Comprehensive Loss

Comprehensive loss is defined as a change in equity during a period from transactions and other events and circumstances from non-owner sources. For the years ended December 31, 2024 and 2023, comprehensive loss consists of foreign currency translation adjustments and unrealized loss on available-for-sale securities net of tax.

Leases

The Company determines if an arrangement is or contains a lease at contract inception by assessing whether the arrangement contains an identified asset and whether the lessee has the right to control such asset. Lessees are required to classify leases as either finance or operating leases and to record a right-of-use (“ROU”) asset and a lease liability for all leases with a term greater than 12 months regardless of the lease classification. The lease classification will determine whether the lease expense is recognized based on an effective interest rate method or on a straight-line basis over the term of the lease. The Company determines the initial classification and measurement of its ROU assets and lease liabilities at the lease commencement date and thereafter if modified. For leases with a term greater than 12 months, the Company records the lease liability at the present value of lease payments over the term. The term of the Company’s leases equals the non-cancellable period of the lease, including any rent-free periods provided by the lessor, and also includes options to extend or terminate the lease that the Company is reasonably certain to exercise. The ROU asset equals the carrying amount of the related lease liability, adjusted for any lease payments made prior to lease commencement, any deferred rent upon adoption, and lease incentives provided by the lessor.

The Company has elected, for all classes of underlying assets, not to recognize ROU assets and lease liabilities for leases with a term of 12 months or less. Lease cost for short-term leases is recognized on a straight-line basis over the lease term. The Company estimates its incremental borrowing rate based on the rate of interest that the Company would have to pay to borrow on a collateralized basis over a similar term, an amount equal to the lease payments in a similar economic environment.

Variable lease payments are expensed as incurred and do not factor into the measurement of the applicable ROU asset or lease liability. Lease payments may be fixed or variable; however, only fixed payments are included in the Company’s lease liability calculation. Lease costs for the Company’s operating leases are recognized on a straight-line basis within operating expenses over the lease term. The Company’s lease agreements may contain non-lease components such as common area maintenance, operating expenses or other costs, which are expensed as incurred for all classes of assets. The Company’s leases do not contain any residual value guarantees. See Note 8 for further information below.

Recent Accounting Pronouncements Adopted and Not Yet Adopted

Recent Accounting Pronouncements Adopted

In November 2023, the FASB issued ASU No. 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures which requires public entities to disclose information about their reportable segments’ significant expenses on an interim and annual basis. ASU 2023-07 is effective for annual periods beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024, with early adoption permitted. The Company adopted this standard on December 31, 2024. See Note 3 for further information.

Recent Accounting Pronouncements Not Yet Adopted

In December 2023, the FASB issued ASU 2023-09 “Income Taxes (Topics 740): Improvements to Income Tax Disclosures” to expand the disclosure requirements for income taxes, specifically related to the rate reconciliation and income taxes paid. ASU 2023-09 is effective for annual periods beginning after December 15, 2024, with early adoption permitted. The Company is currently evaluating the impact of this ASU 2023-09 on its consolidated financial statements and related disclosures.

In November 2024, the FASB issued ASU no. 2024-03, Income Statement-Reporting Comprehensive Income-Expense Disaggregation Disclosures (Subtopic 220-40). The amendments in this update require disclosure, in the notes to the financial statements, of specific expense categories present within expense captions presented on the face of the income statement within continuing operations of public business entities. The amendments in this update are effective for annual periods beginning after December 15, 2026 and interim periods beginning after December 15, 2027. The Company is currently evaluating the impact of this ASU 2024-03 on its consolidated financial statements and related disclosures.

A variety of proposed or otherwise potential accounting standards are currently being studied by standard-setting organizations and certain regulatory agencies. Because of the tentative and preliminary nature of such proposed standards, the Company has not yet determined the effect, if any, that the implementation of such proposed standards would have on the Company’s consolidated financial statements.

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Operating expenses:
In-process research and development	$ 10,000	$ 0
Research and development	11,838	39,604
General and administrative	44,210	47,553
Restructuring and impairment charges	7,493	72,012
Total operating expenses	73,541	159,169
Loss from operations	(73,541)	(159,169)
Interest income	6,987	8,866
Interest expense	(8,992)	(5,209)
Other rental income	4,267	0
Other expense, net	(2,856)	(575)
Net loss	(74,135)	(156,087)
Other comprehensive income:
Foreign currency translation	168	(433)
Unrealized (loss) gain on available-for-sale securities, net	(48)	578
Net comprehensive loss	$ (74,015)	$ (155,942)
Net loss per share, basic (in dollars per share)	$ (11.39)	$ (24.00)
Net loss per share, diluted (in dollars per share)	$ (11.39)	$ (24.00)
Weighted-average shares used in computing net loss per share, basic (in shares)	6,510,138	6,503,913
Weighted-average shares used in computing net loss per share, diluted (in shares)	6,510,138	6,503,913

Equity	12 Months Ended
Equity	Dec. 31, 2024
Equity [Abstract]
Equity	Equity Common Stock Each share of common stock has the right to one vote. The holders of common stock are also entitled to receive dividends whenever funds are legally available and if declared by the Company’s Board of Directors (the “Board of Directors”), subject to the prior rights of holders of all classes of stock outstanding having priority rights as to dividends. No cash dividends have been declared by the Board of Directors from inception. As of December 31, 2024 and 2023, the Company had 6,525,887 and 6,503,913 shares of common stock outstanding, respectively. Preferred Stock The Company’s current amended and restated certificate of incorporation authorizes the Company to issue up to 10,000,000 shares of preferred stock at $0.000001 par value per share. The Board of Directors is authorized to provide for the issuance of the preferred stock in one or more series, and to fix the number of shares and to determine or alter for each such series, such voting powers, full or limited, or no voting powers, and such designation, preferences, and relative, participating, optional, or other rights and such qualifications, limitations, or restrictions thereof, as shall be stated and expressed in subsequent resolution or resolutions adopted by the board providing for the issuance of such shares. As of December 31, 2024 and 2023 there were no shares of preferred stock issued or outstanding.

- Definition

The entire disclosure for equity.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org/1943274/2147481112/505-10-50-13

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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-Paragraph 2
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org/505/tableOfContent

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
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-Section 50
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-Subparagraph (i)
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-URI https://asc.fasb.org/1943274/2147481112/505-10-50-13

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Name Accounting Standards Codification
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Reference 15: http://www.xbrl.org/2003/role/disclosureRef
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Reference 16: http://www.xbrl.org/2003/role/disclosureRef
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Reference 17: http://www.xbrl.org/2003/role/disclosureRef
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Reference 18: http://www.xbrl.org/2003/role/disclosureRef
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Reference 19: http://www.xbrl.org/2003/role/disclosureRef
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-Section 50
-Paragraph 18
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-18

+ Details

Commitments and Contingencies - Interest Expense Related to the Debt (Details) - Secured Mortgage Loan - Loans Payable - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Interest Expense Related to the Loan [Line Items]
Contractual interest expense	$ 7,997	$ 4,214
Amortization of debt issuance cost	995	995
Total interest expense related to the Debt	$ 8,992	$ 5,209

Net Loss Per Share (Details) - shares	12 Months Ended
Net Loss Per Share (Details) - shares	Dec. 31, 2024	Dec. 31, 2023
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares (in shares)	1,249,459	799,622
Stock options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares (in shares)	1,249,459	799,622

Balance Sheet Components - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 3.6	$ 4.8
Construction in Progress
Property, Plant and Equipment [Line Items]
Interest related to qualifying expenditures	$ 0.0	$ 2.4

Income Taxes - Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Income Tax Disclosure [Abstract]
U.S. federal taxes at statutory rate	21.00%	21.00%
Stock-based compensation	(6.70%)	(1.80%)
Permanent differences and other	0.30%	0.80%
Statutory tax rate differences	4.40%	3.40%
Change in valuation allowance	(19.00%)	(23.40%)
Total	0.00%	0.00%

Balance Sheet Components - Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accrued compensation and benefits	$ 2,691	$ 1,026
Accrued operational expenses	582	1,412
Accrued restructuring costs	2,073	3,136
Accrued research, development and clinical trial expenses	209	1,833
Operating lease liabilities, current	1,682	1,750
Other current liabilities	0	190
Total accrued expenses and other current liabilities	$ 7,237	$ 9,347
Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Total accrued expenses and other current liabilities	Total accrued expenses and other current liabilities

Cover - USD ($) $ in Millions	12 Months Ended
Cover - USD ($) $ in Millions	Dec. 31, 2024	Feb. 28, 2025	Jun. 28, 2024
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2024
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-40215
Entity Registrant Name	Instil Bio, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	83-2072195
Entity Address, Address Line One	3963 Maple Avenue, Suite 350
Entity Address, City or Town	Dallas
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	75219
City Area Code	972
Local Phone Number	499-3350
Title of 12(b) Security	Common Stock, $0.000001 par value per share
Trading Symbol	TIL
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
ICFR Auditor Attestation Flag	false
Document Financial Statement Error Correction	false
Entity Shell Company	false
Entity Public Float			$ 38.6
Entity Common Stock, Shares Outstanding		6,525,887
Documents Incorporated by Reference	DOCUMENTS INCORPORATED BY REFERENCE Portions of the registrant’s definitive proxy statement to be filed with the Securities and Exchange Commission (SEC) subsequent to the date hereof pursuant to Regulation 14A in connection with the registrant’s 2025 Annual Meeting of Stockholders are incorporated by reference into Part III of this Annual Report on Form 10-K. Such proxy statement will be filed with the SEC not later than 120 days after the conclusion of the registrant’s fiscal year ended December 31, 2024.
Amendment Flag	false
Entity Central Index Key	0001789769
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2024

Insider Trading Policies and Procedures	12 Months Ended
Insider Trading Policies and Procedures	Dec. 31, 2024
Insider Trading Policies and Procedures [Line Items]
Insider Trading Policies and Procedures Adopted	true

Segment Reporting - Summary of the Segment Loss, Including Significant Segment Expenses (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2024 USD ($) segment	Dec. 31, 2023 USD ($)
Segment Reporting [Abstract]
Number of reportable segments \| segment	1
Segment Reporting Information [Line Items]
In-process research and development	$ 11,838	$ 39,604
AXN-2510/IMM2510 and AXN-27M/IMM27M	1,291	0
Restructuring charges	7,493	72,012
Interest income	(6,987)	(8,866)
Interest expense	8,992	5,209
Other (income) expense, net	2,856	575
Loss before income taxes	(74,135)	(156,087)
Reportable Segment
Segment Reporting Information [Line Items]
In-process research and development	10,000	0
Other program expenses	9,901	35,567
General and administrative	41,246	46,834
Restructuring charges	7,493	72,012
Depreciation	3,610	4,756
Interest income	(6,987)	(8,866)
Interest expense	8,992	5,209
Other (income) expense, net	(1,411)	575
Loss before income taxes	$ 74,135	$ 156,087

Equity (Details)	Dec. 31, 2024 vote $ / shares shares	Dec. 31, 2023 $ / shares shares
Equity [Abstract]
Common stock, votes per share \| vote	1
Common stock, shares outstanding (in shares)	6,525,887	6,503,913
Preferred stock authorized (in shares)	10,000,000	10,000,000
Common stock, par value (in dollars per share) \| $ / shares	$ 0.000001	$ 0.000001
Convertible preferred stock issued (in shares)	0	0

Financial Instruments - Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Investments, Debt and Equity Securities [Abstract]
Available-for-sale	$ 104,510	$ 141,161
Long-term investments	$ 0	$ 23,161

- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 103
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482078/820-10-55-103

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 820
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-Name Accounting Standards Codification
-Section 55
-Paragraph 100
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482078/820-10-55-100

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
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-Name Accounting Standards Codification
-Section 50
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-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
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-Paragraph 2
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-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
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-Section 50
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-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
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-Paragraph 2
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
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-Name Accounting Standards Codification
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-Paragraph 1
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-Publisher FASB
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479130/326-30-45-1

+ Details

Fair Value Measurement (Tables)

12 Months Ended

Dec. 31, 2024

Fair Value Disclosures [Abstract]

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis

The following tables provide information by level for assets and liabilities that are measured at fair value on a recurring and nonrecurring basis:


	December 31, 2024
	Level 1		Level 2		Level 3		Total
	(In thousands)
Financial Assets
Money market funds	$	5,632	$	—	$	—	$	5,632
U.S. Treasury bills	—		104,510		—		104,510
Total	$	5,632	$	104,510	$	—	$	110,142
Financial Liabilities
Contingent consideration	$	—	$	—	$	948	$	948

	December 31, 2023
	Level 1		Level 2		Level 3		Total
	(In thousands)
Financial Assets
Money market funds	$	5,684	$	—	$	—	$	5,684
U.S. Treasury bills	—		164,322		—		164,322
Derivative financial instrument	—		1,055		—		1,055
Total	$	5,684	$	165,377	$	—	$	171,061
Financial Liabilities
Contingent consideration	$	—	$	—	$	4,858	$	4,858

Schedule of Reconciliation of Level 3 Financial Liabilities

The following table sets forth a summary of the changes in the fair value of the Company’s Level 3 financial liabilities (in thousands):


	Level 3 Financial Liabilities
Fair value, beginning balance as of December 31, 2022	$	8,242
Change in fair value	(3,384)
Fair value, ending balance as of December 31, 2023	4,858
Change in fair value	(3,910)
Fair value, ending balance as of December 31, 2024	$	948

Corporate Restructuring (Tables)

12 Months Ended

Dec. 31, 2024

Restructuring and Related Activities [Abstract]

Schedule of Total Amount Expected to be Incurred and Liability

The following table summarizes the restructuring and impairment charges by category (in thousands):


	Year Ended December 31,
	2024		2023
Asset impairment for leasehold improvements	$	343	$	2,644
One-time employee termination benefits	2,721		1,844
Building and construction work in progress impairment	—		41,542
Contract terminations	(723)		1,987
Right-of-use asset impairment	827		7,724
Impairment of long-lived assets held for sale	4,325		16,271
Total restructuring and impairment charges	$	7,493	$	72,012

Schedule of Realignment Non-cash Charges

The following table shows the liability related to the Plan (in thousands):


	Employee Benefits		Contract Terminations		Total
Restructuring liability as of December 31, 2023	$	—	$	3,136	$	3,136
Additions, net	2,420		733		3,153
Payments	(2,289)		(578)		(2,867)
Adjustments	—		(1,349)		(1,349)
Total restructuring liability as of December 31, 2024	$	131	$	1,942	$	2,073

Organization and Description of Business	12 Months Ended
Organization and Description of Business	Dec. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Description of Business	Organization and Description of Business Instil Bio, Inc. (the “Company”) is a clinical-stage biopharmaceutical company focused on developing a pipeline of novel therapies. The Company is advancing the development of its lead product candidate, AXN-2510 (formerly SYN-2510)/IMM2510, a bispecific antibody targeting both programmed death-ligand 1 (“PD-L1”) and vascular endothelial growth factor (“VEGF”) in solid tumor cancers, and seeks to in-license or acquire and develop additional novel therapeutic candidates in diseases with significant unmet medical need. In August 2024, the Company’s wholly owned subsidiary, Axion Bio, Inc. (formerly SynBioTx, Inc.) (“Axion Bio”), in-licensed certain bispecific antibodies, including AXN-2510/IMM2510, and AXN-27M (formerly SYN-27M)/IMM27M, a monoclonal antibody targeting cytotoxic T-lymphocyte associated antigen 4 (“CTLA-4”) from ImmuneOnco Biopharmaceuticals (Shanghai) Inc. (“ImmuneOnco”). AXN-2510/IMM2510, the lead in-licensed product candidate, is a novel and differentiated PD-L1xVEGF bispecific antibody in development for the treatment of multiple solid tumor cancers. Pursuant to the license and collaboration agreement with ImmuneOnco (the “IO Collaboration Agreement”), Axion Bio has an exclusive license to research, develop, manufacture and commercialize these product candidates globally, including in the United States, Europe and Japan, excluding mainland China, Hong Kong, Macau and Taiwan (“Greater China”). ImmuneOnco retains development and commercialization rights in Greater China.

Net Loss Per Share (Tables)

12 Months Ended

Dec. 31, 2024

Earnings Per Share [Abstract]

Schedule of Antidilutive Securities Excluded from Computation of Net Loss Per Share

The following outstanding potentially dilutive shares have been excluded from the calculation of diluted net loss per share for the periods presented due to their anti-dilutive effect:


	December 31,
	2024	2023
Stock options to purchase common stock	1,249,459	799,622
Total	1,249,459	799,622

Stock-Based Compensation

12 Months Ended

Dec. 31, 2024

Share-Based Payment Arrangement [Abstract]

Stock-Based Compensation

2021 Equity Incentive Plan

In March 2021, the Company adopted the 2021 Equity Incentive Plan (the “2021 Plan”), which became effective in connection with the Company’s initial public offering (“IPO”). The 2021 Plan was approved by the Board of Directors and stockholders in March 2021. The 2021 Plan is an equity incentive plan pursuant to which the Company may grant the following awards: (i) incentive stock options; (ii) nonstatutory stock options; (iii) stock appreciation rights; (iv) restricted stock awards; (v) restricted stock unit awards; (vi) performance awards; and (vii) other forms of stock awards to employees, directors, and consultants, including employees and consultants of the Company’s affiliates. The 2021 Plan is a successor to the Company’s 2018 Stock Incentive Plan (the “2018 Plan”). Following the effectiveness of the 2021 Plan, no further grants may be made under the 2018 Plan; however, any outstanding equity awards granted under the 2018 Plan will continue to be governed by the terms of the 2018 Plan.

The number of shares available for future issuance under the 2021 Plan is the sum of (1) 433,000 new shares of common stock, (2) 209,722 remaining shares of common stock reserved under the 2018 Plan that became available for issuance upon the effectiveness of the 2021 Plan and (3) the number of shares of common stock subject to outstanding awards under the 2018 Plan when the 2021 Plan became effective that thereafter expire or are forfeited, canceled, withheld to satisfy tax withholding or to purchase or exercise an award, repurchased by the Company or are otherwise terminated. The number of shares of common stock reserved for issuance under the 2021 Plan will automatically increase on January 1 of each year, for a period of ten years, from January 1, 2022 continuing through January 1, 2031, by 5% of the total number of shares of common stock outstanding on December 31 of the preceding calendar year, or a lesser number of shares as may be determined by the Company’s Board of Directors. Stock options granted by the Company to employees generally vest over four years with a one-year cliff.

As of December 31, 2024, 512,993 shares of common stock remained available for issuance under the 2021 Plan.

The following summarizes option activity under the 2021 Plan as of December 31, 2024:


	Shares Available for Grant	Shares Issuable Under Options	Weighted- Average Exercise Price		Weighted- Average Remaining Contract Term (in years)	Aggregate Intrinsic Value (in thousands)
Balance, December 31, 2022	405,233	1,053,997	$	112.25	7.22	$	711
Additional shares authorized	—
Options granted(1)	(271,921)	271,921	$	12.68
Options forfeited	526,296	(526,296)	$	97.80
Options exercised	—	—	$	—
Balance, December 31, 2023	659,608	799,622	$	87.90	7.18	$	101
Additional shares authorized	325,196
Options granted(1)	(546,800)	546,800	$	29.19
Options forfeited	74,989	(74,989)	$	132.63
Options exercised	—	(21,974)	$	16.64
Balance, December 31, 2024	512,993	1,249,459	$	60.78	7.31	$	4,827
Exercisable, December 31, 2024		642,832	$	81.70	5.77	$	1,972
Vested and expected to vest, December 31, 2024		642,832	$	81.70	5.77	$	1,972

______________________________________________________________

(1) Includes zero and 4,796 stock options during the years ended December 31, 2024 and 2023, respectively, subject to only performance conditions.

The aggregate intrinsic value disclosed in the above table is based on the difference between the exercise price of the stock option and the estimated fair value of the Company’s common stock as of the respective period-end dates. There were 21,974 and zero stock options exercised during the years ended December 31, 2024 and 2023, respectively. The aggregate intrinsic value of stock options exercised was $0.1 million and zero during the years ended December 31, 2024 and 2023, respectively. The weighted-average grant date fair value of stock options granted during the years ended December 31, 2024 and 2023, was $22.85 and $8.74 per share, respectively.

The following table sets forth stock-based compensation included in the Company’s statements of operations and comprehensive loss (in thousands):


	Year Ended December 31,
	2024		2023
Research and development expense	$	2,066	$	1,549
General and administrative expense	15,191		16,617
Total stock-based compensation expense	$	17,257	$	18,166

As of December 31, 2024 and 2023, there was $16.6 million and $22.4 million, respectively, of total unrecognized compensation cost related to unvested stock options granted under the 2018 Plan and 2021 Plan, which is expected to be recognized over a weighted average period of 2.25 years and 1.39 years, respectively.

The fair value of the Company’s stock option awards was estimated at the date of grant using a Black-Scholes option pricing model with the following assumptions:


	Year Ended December 31,
	2024				2023
Expected term (in years)	5.27		—	6.08	5.28		—	6.08
Expected volatility	86.92	%	—	100.06%	76.19	%	—	77.56%
Risk-free interest rate	3.53	%	—	4.57%	3.54	%	—	4.01%
Fair value of common stock	$10.50		—	$66.10	$11.18		—	$15.20
Expected dividend yield	—%				—%

The Black-Scholes option pricing model requires the use of highly subjective assumptions which determine the fair value of stock-based awards. These assumptions include:

Expected term—The expected term represents the period that stock-based awards are expected to be outstanding and is determined as the average of the time-to-vesting and the contractual life of the awards.

Expected volatility—Since the Company is privately held and does not have any trading history for its common stock, the expected volatility was estimated based on the average volatility for comparable publicly traded biotechnology companies over a period equal to the expected term of the stock option grants. The comparable companies were chosen based on their similar size, stage in the life cycle or area of specialty.

Risk-free interest rate—The risk-free interest rate is based on the U.S. Treasury zero coupon issues in effect at the time of grant for periods corresponding with the expected term of awards.

Expected dividend yield—The Company has never paid dividends on its common stock and has no plans to pay dividends on its common stock. Therefore, the Company used an expected dividend yield of zero.

Performance Awards

During the years ended December 31, 2024 and 2023, zero and 4,796 stock options were granted to both employees and non-employees based upon performance conditions and strategic transactions. As of December 31, 2023, the 2023 performance grants were expected to be recognized over a weighted average period of 0.37 years. A strategic transaction has been defined as (a) a change in control, or (b) certain corporate and business goals specific to the employee’s performance or employment agreement. Stock-based compensation expense related to awards where performance conditions were achieved for the year ended December 31, 2024 was zero. As of December 31, 2024 and 2023, the Company had zero and $5.1 million of unrecognized compensation cost relating to these performance awards, calculated using the accelerated attribution method and the grant date fair value of the awards, respectively.

Employee Stock Purchase Plan

In March 2021, the Company adopted the Employee Stock Purchase Plan (the “ESPP”), which became effective in connection with the IPO. The ESPP was adopted by the Board of Directors and stockholders in March 2021, but the Company has not yet commenced offerings to employees under the ESPP. The ESPP initially provides participating employees with the opportunity to purchase up to an aggregate of 61,850 shares of common stock. The number of shares reserved under the ESPP automatically increases on January 1 of each year through and until January 1, 2031, in an amount equal to the lesser of (i) 1% of the total number of shares of common stock outstanding on December 31 of the preceding calendar year, and (ii) 123,700 shares; provided, however, that before the date of any such increase, the Board of Directors may determine that such increase will be less than the amount set forth in clauses (i) and (ii).

Net Loss Per Share

12 Months Ended

Dec. 31, 2024

Earnings Per Share [Abstract]

Net Loss Per Share

The following outstanding potentially dilutive shares have been excluded from the calculation of diluted net loss per share for the periods presented due to their anti-dilutive effect:


	December 31,
	2024	2023
Stock options to purchase common stock	1,249,459	799,622
Total	1,249,459	799,622

Corporate Restructuring - Restructuring Liability (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2024 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring liability as of December 31, 2023	$ 3,136
Total restructuring liability as of December 31, 2024	2,073
2023 Plan
Restructuring Cost and Reserve [Line Items]
Restructuring liability as of December 31, 2023	3,136
Additions, net	3,153
Payments	(2,867)
Adjustments	(1,349)
Total restructuring liability as of December 31, 2024	2,073
2023 Plan \| Employee Benefits
Restructuring Cost and Reserve [Line Items]
Restructuring liability as of December 31, 2023	0
Additions, net	2,420
Payments	(2,289)
Adjustments	0
Total restructuring liability as of December 31, 2024	131
2023 Plan \| Contract Terminations
Restructuring Cost and Reserve [Line Items]
Restructuring liability as of December 31, 2023	3,136
Additions, net	733
Payments	(578)
Adjustments	(1,349)
Total restructuring liability as of December 31, 2024	$ 1,942

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References + Details

Income Taxes - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
Income Taxes - Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Operating Loss Carryforwards [Line Items]
Increase in valuation allowance	$ (14,700)
Operating loss carryforwards, offset of taxable income, percentage	80.00%
Uncertain tax positions	$ 2,339	$ 2,339
Federal
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	348,300
Federal \| Research & Development credits
Operating Loss Carryforwards [Line Items]
Tax credits carryforward	4,100
State \| California Franchise Tax Board
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	132,300
State \| Research & Development credits
Operating Loss Carryforwards [Line Items]
Tax credits carryforward	$ 3,700

Corporate Restructuring - Restructuring costs by category (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Restructuring Cost and Reserve [Line Items]
Restructuring Incurred Cost Statement Of Income Or Comprehensive Income Extensible Enumeration Not Disclosed Flag	Contract terminations	Contract terminations
Impairment of right-of-use assets	$ 827	$ 7,724
Total restructuring and impairment charges	7,493	72,012
Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring charges	2,900
Impairment of right-of-use assets	827	7,724
Impairment of long lived asset held for use	4,325	16,271
Total restructuring and impairment charges	7,493	72,012
Restructuring Plan \| One-time employee termination benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges	2,721	1,844
Restructuring Plan \| Contract terminations
Restructuring Cost and Reserve [Line Items]
Restructuring charges	(723)	1,987
Restructuring Plan \| Asset impairment for leasehold improvements
Restructuring Cost and Reserve [Line Items]
Non-cash impairment charge	343	2,644
Restructuring Plan \| Building and construction work in progress impairment
Restructuring Cost and Reserve [Line Items]
Non-cash impairment charge	$ 0	$ 41,542

Pay vs Performance Disclosure - USD ($) $ in Thousands	12 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Pay vs Performance Disclosure
Net loss	$ (74,135)	$ (156,087)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

+ Details

License and Collaboration Agreement with ImmuneOnco	12 Months Ended
License and Collaboration Agreement with ImmuneOnco	Dec. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
License and Collaboration Agreement with ImmuneOnco	License and Collaboration Agreement with ImmuneOnco On August 1, 2024, Axion Bio and ImmuneOnco entered into the IO Collaboration Agreement pursuant to which Axion Bio in-licensed certain bispecific antibodies, including AXN-2510/IMM2510 and AXN-27M/IMM27M, from ImmuneOnco. Pursuant the IO Collaboration Agreement, Axion Bio paid ImmuneOnco a $10.0 million upfront payment and prepaid ImmuneOnco $5.0 million in development costs in the year ended December 31, 2024. ImmuneOnco is eligible to receive additional potential near-term payments of up to $35.0 million, up to $2.1 billion in commercial, development and regulatory milestones (including up to $270.0 million in longer term development and regulatory milestones and up to $1.8 billion in commercial milestones) plus single-digit to low double-digit percentage royalties on global net sales of the licensed products outside of Greater China. The expenses recognized in connection with the IO Collaboration Agreement were $10.0 million for the year ended December 31, 2024, recorded as a component of In-process research and development on the consolidated statements of operations and comprehensive loss. As of December 31, 2024, no additional milestones had been accrued as the underlying contingencies had not yet been resolved.

License and Collaboration Agreement with ImmuneOnco (Details) - Axion - USD ($) $ in Millions		12 Months Ended
	Aug. 01, 2024	Dec. 31, 2024
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Upfront payment	$ 10.0
Development cost		$ 5.0
Collaboration agreement costs incurred		$ 10.0
Maximum \| License Agreement Terms
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Licensing agreement compensation	35.0
Maximum \| Commercial, development and regulatory milestones
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Licensing agreement compensation	2,100.0
Maximum \| Long-Term regulatory milestones
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Licensing agreement compensation	270.0
Maximum \| Commercial Milestones
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Licensing agreement compensation	$ 1,800.0

Commitments and Contingencies - Future Minimum Payments (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2025	$ 1,817
2026	1,219
Total future lease payments	3,036
Less: imputed interest	(337)
Total lease liability balance	2,699
Less: current portion of operating lease liabilities	(1,682)	$ (1,750)
Total operating lease liabilities, non-current	$ 1,017	$ 2,877

Financial Instruments

12 Months Ended

Dec. 31, 2024

Investments, Debt and Equity Securities [Abstract]

Financial Instruments

Marketable securities and long-term investments classified as available-for-sale on December 31, 2024 and 2023 consisted of the following (in thousands):


	December 31, 2024
	Maturity	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
U.S. Treasury bills	Less than one year	$	104,445	$	99	$	(34)	$	104,510


	December 31, 2023
	Maturity	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
U.S. Treasury bills	Less than one year	$	141,075	$	86	$	—	$	141,161
U.S. Treasury bills	Between one and two years	23,134		27		—		23,161
		$	164,209	$	113	$	—	$	164,322

As of December 31, 2024 and 2023, marketable securities that had contractual maturities less than one year are classified as current because management considers these marketable securities to be available for current operations. As of December 31, 2024 and 2023, marketable securities that had contractual maturities between one and two years are classified as long-term because management considers these marketable securities to be available for operations beyond one year. The Company does not intend to sell its marketable securities and it is not likely that the Company will be required to sell these securities before recovery of their amortized cost basis. There were $104.5 million of marketable securities classified as available-for-sale as of December 31, 2024. There were $141.2 million of marketable securities and $23.2 million of long-term investments maturing in less than two years classified as available-for-sale as of December 31, 2023.

Income Taxes - Loss before Income Tax Provision (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Domestic	$ (60,382)	$ (144,570)
Foreign	(13,753)	(11,517)
Loss before income taxes	$ (74,135)	$ (156,087)

- Definition

Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-22

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 48
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482785/280-10-55-48

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-32

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 30
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-30

Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 270
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482964/270-10-50-1

Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (ee)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-32

Reference 7: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-32

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(11))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477250/944-220-S99-1

Reference 9: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 31
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-31

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 235
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-05(b)(2))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477314/942-235-S99-1

Reference 11: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(10))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483621/220-10-S99-2

Reference 12: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 942
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(15))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478524/942-220-S99-1

+ Details

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2024

Accounting Policies [Abstract]

Schedule of Cash, Cash Equivalents and Restricted Cash

The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the consolidated balance sheets that sum to the amounts shown in the consolidated statements of cash flows (in thousands):


	December 31,
	2024		2023
Cash and cash equivalents	$	8,805	$	9,195
Restricted cash	1,830		1,501
Cash, cash equivalents and restricted cash	$	10,635	$	10,696

Schedule of Cash, Cash Equivalents and Restricted Cash


	December 31,
	2024		2023
Cash and cash equivalents	$	8,805	$	9,195
Restricted cash	1,830		1,501
Cash, cash equivalents and restricted cash	$	10,635	$	10,696

Schedule of Useful Lives

The estimated useful lives of the Company’s property, plant and equipment are as follows:


Laboratory equipment			5 years
Manufacturing equipment			5 years
Office and computer equipment			3 years
Buildings			35 years
Leasehold improvements			Shorter of remaining lease term or estimated useful life

Property, plant and equipment, net consist of the following (in thousands):


	December 31,
	2024		2023
Land	$	31,243	$	31,243
Laboratory equipment	—		8,291
Buildings	102,433		102,433
Office and computer equipment	509		831
Leasehold improvements	—		1,424
Manufacturing equipment	—		2,017
Total property, plant and equipment, gross	134,185		146,239
Less: accumulated depreciation	(4,779)		(7,555)
Total property, plant and equipment, net	$	129,406	$	138,684

Income Taxes - Deferred Income Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Deferred tax assets:
Net operating loss carryforwards	$ 95,773	$ 88,408
Research and development credits	4,915	4,915
Accrued compensation and benefits	646	107
Stock-based compensation	2,008	3,570
Capitalized research and development	20,920	19,432
Other temporary differences	10,201	8,279
Intangible assets	2,841	97
Fixed assets	4,827	1,496
Other	426	335
Total gross deferred tax assets	142,557	126,639
Less: valuation allowance	(141,367)	(126,639)
Total deferred tax assets, net	1,190	0
Deferred tax liabilities:
Rent receivable	(1,190)	0
Total gross deferred tax liabilities	(1,190)	0
Net deferred tax assets (liabilities)	$ 0	$ 0

Segment Reporting (Tables)

12 Months Ended

Dec. 31, 2024

Segment Reporting [Abstract]

Schedule of Segment Reporting Information, by Segment

The following table is a summary of the segment loss, including significant segment expenses for the years ended December 31, 2024 and 2023 (in thousands):


	Year Ended December 31,
	2024		2023
In-process research and development	$	10,000	$	—
AXN-2510/IMM2510 and AXN-27M/IMM27M	1,291		—
Other program expenses(1) (2)	9,901		35,567
General and administrative(1)	41,246		46,834
Restructuring charges	7,493		72,012
Depreciation	3,610		4,756
Interest income	(6,987)		(8,866)
Interest expense	8,992		5,209
Other (income) expense, net	(1,411)		575
Segment and consolidated net loss	$	74,135	$	156,087

______________________________________________________________

(1) Depreciation expense is removed from both “General and administrative” and “Other program expense” and is disclosed separately.

(2) Other program expenses consist of costs related to the Company’s past development of its CoStAR-TIL technology.

Schedule of Long-Lived Assets, by Geographical Areas

The Company’s long-lived tangible assets, as well as the Company’s operating lease right-of-use assets, recognized on the consolidated balance sheets is as follows (in thousands):


	Year Ended December 31,
	2024		2023
United States	$	130,340	$	133,974
United Kingdom	$	—	$	7,097

Balance Sheet Components - Property, Plant and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	$ 134,185	$ 146,239
Less: accumulated depreciation	(4,779)	(7,555)
Total property, plant and equipment, net	129,406	138,684
Land
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	31,243	31,243
Laboratory equipment
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	0	8,291
Buildings
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	102,433	102,433
Office and computer equipment
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	509	831
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	0	1,424
Manufacturing equipment
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	$ 0	$ 2,017

Balance Sheet Components - Schedule of Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Prepaid general and administration	$ 1,316	$ 1,033
Prepaid research and development	4,146	300
Tax-related receivable	2,622	3,643
Prepaid contract research organization expenses	282	1,322
Other current assets	959	2,604
Total prepaid and other current assets	$ 9,325	$ 8,902

Audit Information	12 Months Ended
Audit Information	Dec. 31, 2024
Audit Information [Abstract]
Auditor Firm ID	34
Auditor Name	Deloitte & Touche LLP
Auditor Location	San Diego, California

Commitments and Contingencies - Schedule of Future Fixed Contractual Lease Payments to be Received (Details) $ in Thousands	Dec. 31, 2024 USD ($)
Commitments and Contingencies Disclosure [Abstract]
2025	$ 8,968
2026	8,968
2027	8,968
2028	8,968
Thereafter	94,910
Total	$ 130,782

Balance Sheet Components (Tables)

12 Months Ended

Dec. 31, 2024

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Schedule of Prepaid Expenses and Other Current Assets

Prepaid and other current assets consist of the following (in thousands):


	December 31,
	2024		2023
Prepaid general and administration	$	1,316	$	1,033
Prepaid research and development	4,146		300
Tax-related receivable	2,622		3,643
Prepaid contract research organization expenses	282		1,322
Other current assets	959		2,604
Total prepaid and other current assets	$	9,325	$	8,902

Schedule of Property, Plant and Equipment, Net

The estimated useful lives of the Company’s property, plant and equipment are as follows:


Laboratory equipment			5 years
Manufacturing equipment			5 years
Office and computer equipment			3 years
Buildings			35 years
Leasehold improvements			Shorter of remaining lease term or estimated useful life

Property, plant and equipment, net consist of the following (in thousands):


	December 31,
	2024		2023
Land	$	31,243	$	31,243
Laboratory equipment	—		8,291
Buildings	102,433		102,433
Office and computer equipment	509		831
Leasehold improvements	—		1,424
Manufacturing equipment	—		2,017
Total property, plant and equipment, gross	134,185		146,239
Less: accumulated depreciation	(4,779)		(7,555)
Total property, plant and equipment, net	$	129,406	$	138,684

Schedule of Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consist of the following (in thousands):


	December 31,
	2024		2023
Accrued compensation and benefits	$	2,691	$	1,026
Accrued operational expenses	582		1,412
Accrued restructuring costs	2,073		3,136
Accrued research, development and clinical trial expenses	209		1,833
Operating lease liabilities, current	1,682		1,750
Other current liabilities	—		190
Total accrued expenses and other current liabilities	$	7,237	$	9,347

Commitments and Contingencies

12 Months Ended

Dec. 31, 2024

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

Leases

Company as a Lessee: Operating Lease Obligations

The Company currently leases office spaces and laboratory spaces located in Thousand Oaks, California, Dallas, Texas, and Alderley Park in the United Kingdom. The Company’s leased facilities have original lease terms ranging from 2 to 5 years that predominately require the Company to provide a security deposit, while certain leases provide the right for the Company to renew the lease upon the expiration of the initial lease term, and various leases have scheduled rent increases on an annual basis. The exercise of lease renewal options for the Company’s existing leases is at the Company’s sole discretion, and not included in the measurement of right-of-use asset or lease liability as they are not reasonably certain to be exercised. Certain leases have leasehold improvements and are being amortized over the shorter of the estimated useful life of the improvements or the remaining life of the lease. Such improvements incurred by the Company will revert to the landlord at the expiration of the lease and will be removed from Company’s consolidated balance sheets.

The Company’s lease costs consist of the following (in thousands):


	Year Ended December 31,
	2024		2023
Operating lease cost	$	1,315	$	2,185
Variable lease cost	801		1,170
Total lease cost	$	2,116	$	3,355

The following table summarizes cash flow information related to the Company’s lease obligations (in thousands):


	Year Ended December 31,
	2024		2023
Cash paid for operating lease liabilities	$	2,279	$	2,308

The following table summarizes the Company’s lease assets and liabilities (in thousands):


	December 31,
	2024		2023
Operating lease right-of-use assets	$	934	$	2,387
Current operating lease liabilities	$	1,682	$	1,750
Non-current operating lease liabilities	$	1,017	$	2,877

The following table summarizes other supplemental information related to the Company’s lease obligations:


	December 31,
	2024		2023
Weighted-average remaining lease term (in years)	1.70		2.60
Weighted-average discount rate	6.75	%	6.75	%

Future minimum lease payments under operating lease liabilities were (in thousands):


	December 31, 2024
2025	$	1,817
2026	1,219
Total future lease payments	3,036
Less: imputed interest	337
Total lease liability balance	2,699
Less: current portion of operating lease liabilities	1,682
Total operating lease liabilities, non-current	$	1,017

During the years ended December 31, 2024 and 2023, the Company evaluated its remaining right-of-use assets for impairment, as the Plan (as defined below in Note 13) has resulted in a cessation of use for several locations. The Company determined these assets were impaired, and has recognized an impairment loss of $0.8 million and $7.2 million for the years ended December 31, 2024 and 2023, respectively, which are recorded in the line item “restructuring and impairment charges” in the consolidated statements of operations and comprehensive loss.

Company as a Lessor: Tarzana Facility Lease with AstraZeneca

On July 10, 2024, Complex Therapeutics LLC entered into a lease with AstraZeneca Pharmaceuticals LP (“Tenant”) (the “Lease”) pursuant to which the Tenant is leasing the Company’s facility located in Tarzana, California. The Lease has an initial term of approximately 15 years, beginning on July 10, 2024 and ending on July 31, 2039, with Tenant having two consecutive options to extend the term for a five-year period each and a one-time option to terminate the Lease on the tenth anniversary of the commencement of the Lease, which, if exercised, obligates Tenant to pay Complex Therapeutics LLC a termination fee. The initial base rent is $0.6 million per month ($7.5 million annually) and the base rent will escalate by 3% per annum. Tenant is also required to pay certain operating expenses and tax expenses as additional rent. There is rent abatement during the first year of the Lease such that Tenant will pay no rent or reduced rent during this period. Tenant also has a right of first offer to purchase the premises that are subject to the Lease.


	Year Ended December 31,
	2024		2023
Rental income	$	4,267	$	—

Approximate future straight-lined contractual lease income to be recognized under a non-cancelable operating lease in effect as of December 31, 2024, are as follows (in thousands):


	December 31, 2024
2025	$	8,968
2026	8,968
2027	8,968
2028	8,968
Thereafter	94,910
Total	$	130,782

Legal Proceedings

From time to time, the Company may have certain contingent liabilities that arise in the ordinary course of its business activities. The Company accrues a liability for such matters when it is probable that future expenditures will be made and that such expenditures can be reasonably estimated. Significant judgment is required to determine both probability and the estimated amount. The Company does not expect that the resolution of these matters will have a material adverse effect on its financial position, results of operations or cash flows.

Debt

In June 2022, the Company’s wholly owned subsidiary, Complex Therapeutics Mezzanine LLC, and the Company’s wholly owned subsidiary, Complex Therapeutics LLC, entered into a mortgage construction loan and mezzanine construction loan (together, the “Construction Loan Agreements”) secured by its Tarzana, California land and building. The initial principal amount of the Construction Loan Agreements was $52.1 million, with additional future principal of up to $32.9 million to fund ongoing construction costs. Construction had been completed, and on July 10, 2024, Complex Therapeutics LLC entered into the Lease. The Construction Loan Agreements were guaranteed by the Company and secured by the Property, and bears interest at the one-month Secured Overnight Financing Rate, plus 5.25% per annum. The Company discontinued capitalizing interest in June 2023 as the building was substantially complete at such time. During the year ended December 31, 2024, the Company refinanced the outstanding principal amount under the Construction Loan Agreements and treated it as a loan extinguishment for accounting purposes and recorded the $0.4 million of unamortized debt issuance costs associated with the Construction Loan Agreement as a loss on debt extinguishment recognized in other expense, net in the consolidated statement of operations and comprehensive loss for the year ended December 31, 2024. On December 20, 2024, Complex Therapeutics LLC, entered into a Term Loan Agreement (the “Loan”) and related loan documents with Midland National Life Insurance Company (the “Lender”), pursuant to which Lender loaned Complex Therapeutics LLC a term loan in the principal amount of $85.6 million to refinance loans secured by the facility in Tarzana, California owned by Complex Therapeutics LLC. Substantially all of the Loan proceeds were used to repay in full the loans related to the construction and development of the Tarzana facility made pursuant to the Construction Loan Agreements. As of December 31, 2024, the outstanding principal amount under the Loan was $85.6 million and unamortized debt issuance costs were $1.4 million.

The Loan has a term of two years with a one-year extension option. The extension option is subject to certain conditions being met, including: (a) no potential default or event of default, (b) payment of a 0.35% extension fee and the costs and expenses of Lender incurred in connection with the extension, (c) replenishing of all reserve funds as reasonably determined by Lender, and (d) compliance with minimum debt yield and debt service coverage ratio requirements. The Loan bears interest at a fixed rate of 6.35% per annum, with interest-only payments during the term of the Loan and the principal balance due in full at maturity.

The Loan may be prepaid in whole but not in part. If the Loan is prepaid on or prior to the 12-month anniversary of the Closing Date, a prepayment fee is required (other than in connection with a casualty or condemnation event) to make Lender whole for the interest it would have otherwise earned on the Loan during the first 12 months. There is no prepayment fee due if the Loan is prepaid after the 12-month anniversary of the Closing Date.

The net carrying amount of the liability component of the debt was as follows (in thousands):


	December 31,
	2024		2023
Principal amount	$	85,600	$	82,837
Unamortized debt issuance cost	(1,413)		(1,410)
Net carrying amount	$	84,187	$	81,427

The following table sets forth the interest expense recognized related to the debt (in thousands):


	Year Ended December 31,
	2024		2023
Contractual interest expense	$	7,997	$	4,214
Amortization of debt issuance cost	995		995
Total interest expense related to the Debt	$	8,992	$	5,209

Indemnifications

The Company has entered into indemnification agreements with its directors and officers that may require the Company to indemnify its directors and officers against liabilities that may arise by reason of their status or service as directors or officers to the fullest extent permitted by Delaware corporate law. The Company currently has directors’ and officers’ insurance coverage that reduces its exposure and enables the Company to recover a portion of any future amounts paid. No liability associated with such indemnifications was recorded as of December 31, 2024 and 2023.

Other Commitments

In the normal course of business, the Company enters into contracts and various purchase agreements commitments with third-party vendors for clinical research services, products and other services from third parties for operating purposes. These agreements generally provide for termination or cancellation, other than for costs already incurred. As of December 31, 2024 and 2023, the Company had $0.1 million and zero outstanding liabilities, respectively, in commitments for employee benefits as part of the Plan. As of December 31, 2024 and 2023, the Company had $1.9 million and $3.1 million, respectively, in commitments for contract terminations as part of the Plan. (see Note 13).

The Company entered into an agreement in 2023 with a third-party collaborator related to the development of the Company’s CoStAR-TIL technology. Milestone payments of $2.6 million and $0.3 million were made during the year ended December 31, 2024 and 2023, respectively, and were recorded within research and development expense in the consolidated statements of operations and comprehensive loss

Commitments and Contingencies

Leases

Company as a Lessee: Operating Lease Obligations

The Company’s lease costs consist of the following (in thousands):


	Year Ended December 31,
	2024		2023
Operating lease cost	$	1,315	$	2,185
Variable lease cost	801		1,170
Total lease cost	$	2,116	$	3,355

The following table summarizes cash flow information related to the Company’s lease obligations (in thousands):


	Year Ended December 31,
	2024		2023
Cash paid for operating lease liabilities	$	2,279	$	2,308

The following table summarizes the Company’s lease assets and liabilities (in thousands):


	December 31,
	2024		2023
Operating lease right-of-use assets	$	934	$	2,387
Current operating lease liabilities	$	1,682	$	1,750
Non-current operating lease liabilities	$	1,017	$	2,877

The following table summarizes other supplemental information related to the Company’s lease obligations:


	December 31,
	2024		2023
Weighted-average remaining lease term (in years)	1.70		2.60
Weighted-average discount rate	6.75	%	6.75	%

Future minimum lease payments under operating lease liabilities were (in thousands):


	December 31, 2024
2025	$	1,817
2026	1,219
Total future lease payments	3,036
Less: imputed interest	337
Total lease liability balance	2,699
Less: current portion of operating lease liabilities	1,682
Total operating lease liabilities, non-current	$	1,017

Company as a Lessor: Tarzana Facility Lease with AstraZeneca


	Year Ended December 31,
	2024		2023
Rental income	$	4,267	$	—

Approximate future straight-lined contractual lease income to be recognized under a non-cancelable operating lease in effect as of December 31, 2024, are as follows (in thousands):


	December 31, 2024
2025	$	8,968
2026	8,968
2027	8,968
2028	8,968
Thereafter	94,910
Total	$	130,782

Legal Proceedings

Debt

The net carrying amount of the liability component of the debt was as follows (in thousands):


	December 31,
	2024		2023
Principal amount	$	85,600	$	82,837
Unamortized debt issuance cost	(1,413)		(1,410)
Net carrying amount	$	84,187	$	81,427

The following table sets forth the interest expense recognized related to the debt (in thousands):


	Year Ended December 31,
	2024		2023
Contractual interest expense	$	7,997	$	4,214
Amortization of debt issuance cost	995		995
Total interest expense related to the Debt	$	8,992	$	5,209

Indemnifications

Other Commitments

Balance Sheet Components

12 Months Ended

Dec. 31, 2024

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Balance Sheet Components

Prepaid and other current assets

Prepaid and other current assets consist of the following (in thousands):


	December 31,
	2024		2023
Prepaid general and administration	$	1,316	$	1,033
Prepaid research and development	4,146		300
Tax-related receivable	2,622		3,643
Prepaid contract research organization expenses	282		1,322
Other current assets	959		2,604
Total prepaid and other current assets	$	9,325	$	8,902

Property, Plant and Equipment, Net

Property, plant and equipment, net consist of the following (in thousands):


	December 31,
	2024		2023
Land	$	31,243	$	31,243
Laboratory equipment	—		8,291
Buildings	102,433		102,433
Office and computer equipment	509		831
Leasehold improvements	—		1,424
Manufacturing equipment	—		2,017
Total property, plant and equipment, gross	134,185		146,239
Less: accumulated depreciation	(4,779)		(7,555)
Total property, plant and equipment, net	$	129,406	$	138,684

Depreciation expense was $3.6 million and $4.8 million for the years ended December 31, 2024 and 2023, respectively, in the consolidated statements of operations and comprehensive loss.

The Company capitalized interest of nil and $2.4 million during the years ended December 31, 2024 and 2023, respectively, related to qualifying expenditures for construction work-in-progress for the Company’s Tarzana manufacturing facility.

Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consist of the following (in thousands):


	December 31,
	2024		2023
Accrued compensation and benefits	$	2,691	$	1,026
Accrued operational expenses	582		1,412
Accrued restructuring costs	2,073		3,136
Accrued research, development and clinical trial expenses	209		1,833
Operating lease liabilities, current	1,682		1,750
Other current liabilities	—		190
Total accrued expenses and other current liabilities	$	7,237	$	9,347

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Dec. 31, 2024
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2024

Income Tax Disclosure [Abstract]

Schedule of Geographical Breakdown of Loss before Provision for Income Taxes

The geographical breakdown of loss before provision for income taxes is as follows (in thousands):


	Year Ended December 31,
	2024		2023
Domestic	$	(60,382)	$	(144,570)
Foreign	(13,753)		(11,517)
Loss before income taxes	$	(74,135)	$	(156,087)

Schedule of Effective Income Tax Rate Reconciliation

The following table presents a reconciliation of the Company’s statutory federal income tax rate and effective tax rate:


	Year Ended December 31,
	2024		2023
U.S. federal taxes at statutory rate	21.0	%	21.0	%
Stock-based compensation	(6.7)	%	(1.8)	%
Permanent differences and other	0.3	%	0.8	%
Statutory tax rate differences	4.4	%	3.4	%
Change in valuation allowance	(19.0)	%	(23.4)	%
Total	—	%	—	%

Schedule of Deferred Tax Assets and Liabilities

The components of deferred tax liabilities consist of the following (in thousands):


	Year Ended December 31,
	2024		2023
Deferred tax assets:
Net operating loss carryforwards	$	95,773	$	88,408
Research and development credits	4,915		4,915
Accrued compensation and benefits	646		107
Stock-based compensation	2,008		3,570
Capitalized research and development	20,920		19,432
Other temporary differences	10,201		8,279
Intangible assets	2,841		97
Fixed assets	4,827		1,496
Other	426		335
Total gross deferred tax assets	142,557		126,639
Less: valuation allowance	(141,367)		(126,639)
Total deferred tax assets, net	1,190		—
Deferred tax liabilities:
Rent receivable	(1,190)		—
Total gross deferred tax liabilities	(1,190)		—
Net deferred tax assets (liabilities)	$	—	$	—

Schedule of Unrecognized Tax Benefits Roll Forward

The components of unrecognized tax benefits consist of the following (in thousands):


Balance at December 31, 2023	$	2,339
Additions in 2024	—
Balance at December 31, 2024	$	2,339

Stock-Based Compensation - Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Shares Available for Grant
Beginning balance (in shares)		659,608	405,233
Additional shares authorized (in shares)	433,000	325,196	0
Options granted (in shares)		(546,800)	(271,921)
Options forfeited (in shares)		74,989	526,296
Ending balance (in shares)		512,993	659,608	405,233
Shares Issuable Under Options
Beginning balance (in shares)		799,622	1,053,997
Options granted (in shares)		546,800	271,921
Options forfeited (in shares)		(74,989)	(526,296)
Options exercised (in shares)		(21,974)	0
Ending balance (in shares)		1,249,459	799,622	1,053,997
Exercisable (in shares)		642,832
Vested and expected to vest (in shares)		642,832
Weighted- Average Exercise Price
Beginning balance (in dollars per share)		$ 87.90	$ 112.25
Options granted (in dollars per share)		29.19	12.68
Options forfeited (in dollars per share)		132.63	97.80
Options exercised (in dollars per share)		16.64	0
Ending balance (in dollars per share)		60.78	$ 87.90	$ 112.25
Exercisable, weighted-average exercise price (in dollars per share)		81.70
Vested and expected to vest, weighted-average exercise price (in dollars per share)		$ 81.70
Balance, weighted-average remaining contract term		7 years 3 months 21 days	7 years 2 months 4 days	7 years 2 months 19 days
Exercisable, weighted-average remaining contract term		5 years 9 months 7 days
Vested and expected to vest, weighted-average remaining contract term		5 years 9 months 7 days
Balance, aggregate intrinsic value		$ 4,827	$ 101	$ 711
Exercisable, aggregate intrinsic value		1,972
Vested and expected to vest, aggregate intrinsic value		$ 1,972
Performance Shares
Shares Available for Grant
Options granted (in shares)		0	(4,796)
Shares Issuable Under Options
Options granted (in shares)		0	4,796

Commitments and Contingencies - Narrative (Details)	1 Months Ended	12 Months Ended
Commitments and Contingencies - Narrative (Details)	Jun. 30, 2022 USD ($)	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Jul. 10, 2024 USD ($) option
Lessee, Lease, Description [Line Items]
Impairment (gain) loss		$ 800,000	$ 7,200,000
Number of extension options \| option				2
Additional milestone payments		2,600,000	300,000
Restructuring Plan
Lessee, Lease, Description [Line Items]
Restructuring charges		2,900,000
Contract terminations \| Restructuring Plan
Lessee, Lease, Description [Line Items]
Restructuring charges		(723,000)	1,987,000
One-time employee termination benefits \| Restructuring Plan
Lessee, Lease, Description [Line Items]
Restructuring charges		2,721,000	1,844,000
Non Cancelable Purchase Commitments with Contract Research Organizations \| Contract terminations \| Restructuring Plan
Lessee, Lease, Description [Line Items]
Restructuring costs		1,900,000	3,100,000
Non Cancelable Purchase Commitments with Contract Research Organizations \| One-time employee termination benefits \| Restructuring Plan
Lessee, Lease, Description [Line Items]
Restructuring charges		100,000	0
Secured Mortgage Loan \| Loans Payable
Lessee, Lease, Description [Line Items]
Initial principal amount	$ 52,100,000	85,600,000	82,837,000
Basis interest	5.25%
Unamortized debt issuance cost		$ (1,413,000)	$ (1,410,000)
Debt instrument, extension fee, percentage		0.35%
Bears interest, percentage		6.35%
Construction Loan Agreement
Lessee, Lease, Description [Line Items]
Unamortized debt issuance cost		$ (400,000)
Construction Loan Agreement \| Loans Payable
Lessee, Lease, Description [Line Items]
Initial principal amount		85,600,000
Unamortized debt issuance cost		$ (1,400,000)
Debt instrument term (in years)		2 years
Debt instrument, extension option, term (in years)		1 year
Complex Therapeutics LLC
Lessee, Lease, Description [Line Items]
Term of contract (in years)				15 years
Renewal term (in years)				5 years
Base rent, per month				$ 600,000
Base rent, per annually				$ 7,500,000
Rents increase in percentage				3.00%
Minimum
Lessee, Lease, Description [Line Items]
Original lease terms		2 years
Maximum
Lessee, Lease, Description [Line Items]
Original lease terms		5 years
Maximum \| Secured Mortgage Loan \| Loans Payable
Lessee, Lease, Description [Line Items]
Additional future principal (upto)	$ 32,900,000

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2024

Share-Based Payment Arrangement [Abstract]

Schedule of Option Activity

The following summarizes option activity under the 2021 Plan as of December 31, 2024:


	Shares Available for Grant	Shares Issuable Under Options	Weighted- Average Exercise Price		Weighted- Average Remaining Contract Term (in years)	Aggregate Intrinsic Value (in thousands)
Balance, December 31, 2022	405,233	1,053,997	$	112.25	7.22	$	711
Additional shares authorized	—
Options granted(1)	(271,921)	271,921	$	12.68
Options forfeited	526,296	(526,296)	$	97.80
Options exercised	—	—	$	—
Balance, December 31, 2023	659,608	799,622	$	87.90	7.18	$	101
Additional shares authorized	325,196
Options granted(1)	(546,800)	546,800	$	29.19
Options forfeited	74,989	(74,989)	$	132.63
Options exercised	—	(21,974)	$	16.64
Balance, December 31, 2024	512,993	1,249,459	$	60.78	7.31	$	4,827
Exercisable, December 31, 2024		642,832	$	81.70	5.77	$	1,972
Vested and expected to vest, December 31, 2024		642,832	$	81.70	5.77	$	1,972

______________________________________________________________

(1) Includes zero and 4,796 stock options during the years ended December 31, 2024 and 2023, respectively, subject to only performance conditions.

Schedule of Stock-Based Compensation Expense

The following table sets forth stock-based compensation included in the Company’s statements of operations and comprehensive loss (in thousands):


	Year Ended December 31,
	2024		2023
Research and development expense	$	2,066	$	1,549
General and administrative expense	15,191		16,617
Total stock-based compensation expense	$	17,257	$	18,166

Schedule of Valuation Assumptions

The fair value of the Company’s stock option awards was estimated at the date of grant using a Black-Scholes option pricing model with the following assumptions:


	Year Ended December 31,
	2024				2023
Expected term (in years)	5.27		—	6.08	5.28		—	6.08
Expected volatility	86.92	%	—	100.06%	76.19	%	—	77.56%
Risk-free interest rate	3.53	%	—	4.57%	3.54	%	—	4.01%
Fair value of common stock	$10.50		—	$66.10	$11.18		—	$15.20
Expected dividend yield	—%				—%

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2024

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

Basis of Presentation

Use of Estimates

Concentration of Credit Risk

Risks and Uncertainties

Reverse Stock Split

Effective December 7, 2023, the Company effected a 1-for-20 reverse stock split of its outstanding shares of common stock. Where applicable, all share and per share amounts in these consolidated financial statements have been adjusted to reflect the effect of the reverse stock split.

Segments

Cash, Cash Equivalents, Restricted Cash, Marketable Securities, and Long-Term Investments


	December 31,
	2024		2023
Cash and cash equivalents	$	8,805	$	9,195
Restricted cash	1,830		1,501
Cash, cash equivalents and restricted cash	$	10,635	$	10,696

Fair Value Measurement

Level 1 —Observable inputs such as unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date.

Level 3 —Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

Property, Plant and Equipment, Net


Laboratory equipment			5 years
Manufacturing equipment			5 years
Office and computer equipment			3 years
Buildings			35 years
Leasehold improvements			Shorter of remaining lease term or estimated useful life

Assets Held for Sale

Impairment of Long-Lived Assets

Grant Proceeds

assurance that they will be fulfilled. Grant proceeds are classified as a reduction of research and development expenses. For each of the years ended December 31, 2024 and 2023, $0.1 million of grant proceeds were recognized in research and development expenses on the Company’s consolidated statements of operations and comprehensive loss.

Research and Development Expenses

Stock-Based Compensation

Income Taxes

Foreign Currency

Net Loss Per Share

Comprehensive Loss

Leases

Recent Accounting Pronouncements Adopted

Recent Accounting Pronouncements Not Yet Adopted

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2024	Dec. 31, 2023
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.000001	$ 0.000001
Preferred stock authorized (in shares)	10,000,000	10,000,000
Preferred stock issued (in shares)	0	0
Preferred stock outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.000001	$ 0.000001
Common stock, shares authorized (in shares)	300,000,000	300,000,000
Common stock, shares issued (in shares)	6,525,887	6,503,913
Common stock, shares outstanding (in shares)	6,525,887	6,503,913

Segment Reporting - Schedule of Long-Lived Assets, by Geographical Areas (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
United States
Segment Reporting Information [Line Items]
Long-lived assets	$ 130,340	$ 133,974
United Kingdom
Segment Reporting Information [Line Items]
Long-lived assets	$ 0	$ 7,097

Summary of Significant Accounting Policies - Useful Life (Details)	Dec. 31, 2024
Laboratory equipment
Property, Plant and Equipment [Line Items]
Useful life	5 years
Manufacturing equipment
Property, Plant and Equipment [Line Items]
Useful life	5 years
Office and computer equipment
Property, Plant and Equipment [Line Items]
Useful life	3 years
Buildings
Property, Plant and Equipment [Line Items]
Useful life	35 years

Financial Instruments - Schedule of Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Amortized Cost
Amortized Cost		$ 164,209
Gross Unrealized Gains
Gross Unrealized Gains		113
Gross Unrealized Losses
Gross Unrealized Losses		0
Fair Value
Fair Value		164,322
U.S. Treasury bills
Amortized Cost
Less than one year	$ 104,445	141,075
Between one and two years		23,134
Gross Unrealized Gains
Less than one year	99	86
Between one and two years		27
Gross Unrealized Losses
Less than one year	(34)	0
Between one and two years		0
Fair Value
Less than one year	$ 104,510	141,161
Between one and two years		$ 23,161

Summary of Significant Accounting Policies - Narrative (Details) $ in Thousands		12 Months Ended
	Dec. 07, 2023	Dec. 31, 2024 USD ($) institution segment	Dec. 31, 2023 USD ($)
Subsidiary, Sale of Stock [Line Items]
Stock split	0.05
Number of segments \| segment		1
Restricted cash		$ 1,830	$ 1,501
Impairment recognized		4,325	60,088
Grant proceeds		100	100
Restructuring Plan
Subsidiary, Sale of Stock [Line Items]
Impairment of long lived asset held for use		4,325	16,271
Leasehold improvements
Subsidiary, Sale of Stock [Line Items]
Impairment recognized		300	2,600
Land
Subsidiary, Sale of Stock [Line Items]
Impairment recognized			41,500
Level 2 \| Buildings and Construction in Progress
Subsidiary, Sale of Stock [Line Items]
Impairment recognized		$ 0	$ (41,500)
Cash and Cash Equivalents \| United States \| Geographic Concentration Risk
Subsidiary, Sale of Stock [Line Items]
Number of financial institution \| institution		2
Cash and Cash Equivalents \| United Kingdom \| Geographic Concentration Risk
Subsidiary, Sale of Stock [Line Items]
Number of financial institution \| institution		1

Summary of Significant Accounting Policies - Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Accounting Policies [Abstract]
Cash and cash equivalents	$ 8,805	$ 9,195
Restricted cash	1,830	1,501
Cash, cash equivalents and restricted cash	$ 10,635	$ 10,696	$ 43,716

Commitments and Contingencies - Lease Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Operating lease cost	$ 1,315	$ 2,185
Variable lease cost	801	1,170
Total lease cost	2,116	3,355
Cash paid for operating lease liabilities	2,279	2,308
Operating lease right-of-use assets	934	2,387
Current operating lease liabilities	1,682	1,750
Non-current operating lease liabilities	$ 1,017	$ 2,877
Weighted-average remaining lease term (in years)	1 year 8 months 12 days	2 years 7 months 6 days
Weighted-average discount rate	6.75%	6.75%