Stock-Based Compensation - Additional Information (Details) - USD ($) $ in Millions	1 Months Ended				12 Months Ended
	Nov. 30, 2025	May 31, 2025	Nov. 30, 2024	May 31, 2024	Dec. 31, 2025	Jun. 30, 2025
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Shares reserved for issuance (in shares)						1,703,333
Unrecognized stock-based compensation expense					$ 4.6
Unrecognized stock-based compensation expense expected to be recognized, term					1 year 3 months 18 days
2018 ESPP
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Maximum shares available for purchase by employees (in shares)						225,000
Percentage of payroll deductions in ESPP					15.00%
Purchase price after discount (in percent)					85.00%
Number of common stock purchased by employees	34,624	34,696	7,685	7,252
Common stock, capital shares reserved for future issuance					86,097

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Dec. 31, 2025
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

Pay vs Performance Disclosure - USD ($) $ in Thousands	12 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Pay vs Performance Disclosure
Net Income (Loss)	$ (6,122)	$ (40,177)

- Definition

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

+ References

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+ Details

Operating Leases - Schedule of Quantitative Information of Operating Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Lease cost
Operating lease cost	$ 851	$ 1,417
Short-term lease cost	0	1
Variable lease cost	817	727
Total lease cost, net	$ 1,668	$ 2,145

Stock-Based Compensation - Summary of Stock Option Activity and Related Information (Details) - Employee Stock Option - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Number of Shares
Options, Outstanding at beginning of period	942,193
Option, Granted	275,225
Options , Exercised	(5,743)
Option, Forfeited	(11,584)
Option, Expired	(6,649)
Option, Outstanding at end of period	1,193,442	942,193
Options vested and exercisable	714,173
Options expected to vest	1,193,442
Weighted Average Exercise Price Per Share
Options, Outstanding at beginning of period	$ 54.24
Option, Granted	11.14
Options , Exercised	22.58
Option, Forfeited	109.69
Options , Expired	123.26
Option, Outstanding at end of period	43.53	$ 54.24
Options vested and exercisable	64.31
Options expected to vest	$ 43.53
Options Outstanding, Weighted Average Remaining Contractual Term (Years)	7 years	7 years 3 months 18 days
Options Vested and Exercisable, Weighted Average Remaining Contractual Term (Years)	5 years 10 months 24 days
Options expected to vest, Weighted Average Remaining Contractual Term (Years)	7 years
Total Intrinsic Value
Option, Outstanding at beginning of period	$ 17,215	$ 1,383
Options , Outstanding at end of period	17,215	$ 1,383
Options vested and exercisable	6,934
Options expected to vest	$ 17,215
Weighted-average grant-date fair value of options granted	$ 8.23	$ 10.04
Total intrinsic value of options exercised	$ 44	$ 2

Investments in Marketable Securities

12 Months Ended

Dec. 31, 2025

Investments, Debt and Equity Securities [Abstract]

Investments in Marketable Securities

Note 4 - Investments in Marketable Securities

Investments in marketable available-for-sale securities consisted of the following (in thousands):


	December 31, 2025
	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss		Fair Value
Cash equivalents
Money market fund	$	57,994	$	—	$	—	$	57,994
Total cash equivalents		57,994		—		—		57,994
Short-term marketable securities
Corporate debt securities		37,329		34		—		37,363
Asset-backed securities		11,970		19		—		11,989
U.S. treasury securities		123,267		170		—		123,437
Commercial paper		16,858		9		—		16,867
Total short-term marketable securities		189,424		232		—		189,656
Total cash equivalents and marketable securities	$	247,418	$	232	$	—	$	247,650


	December 31, 2024
	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss			Fair Value
Cash equivalents
Money market fund	$	29,066	$	—	$	—		$	29,066
U.S. treasury securities		8,437		—		—			8,437
Total cash equivalents		37,503		—		—			37,503
Short-term marketable securities
Corporate debt securities		20,971		20		(3	)		20,988
U.S. treasury securities		48,077		40		—			48,117
Commercial paper		4,625		5		—			4,630
Total short-term marketable securities		73,673		65		(3	)		73,735
Total cash equivalents and marketable securities	$	111,176	$	65	$	(3	)	$	111,238

Short-term marketable securities held as of December 31, 2025 and 2024 had contractual maturities of less than one year.

The realized gains on investments in marketable debt securities for the year ended December 31, 2025 were not material. There were no realized gains and losses for the years ended December 31, 2024.

There were no investments in an unrealized loss position as of December 31, 2025. As of December 31, 2024, investments which were in an unrealized loss position were not material and generally due to interest rate fluctuations, as opposed to declines in credit quality. The Company determined it has the intent and ability to hold all marketable securities that have been in a continuous loss position until recovery of their amortized cost basis, which may be until maturity. As a result, the Company did not recognize any credit losses related to its investments and all unrealized gains and losses on available-for-sale securities are recorded in accumulated other comprehensive loss on the consolidated balance sheets during the years ended December 31, 2025 and 2024.

Accrued interest receivable was $1.5 million and $0.4 million as of December 31, 2025 and 2024, respectively, and was recorded in prepaid expenses and other current assets on the consolidated balance sheets. The Company did not write off any accrued interest receivable during the years ended December 31, 2025 and 2024.

Fair Value Measurement

The following tables presents the Company’s financial assets measured at fair value on a recurring basis by level within the fair value hierarchy (in thousands):


	December 31, 2025
	Level 1		Level 2		Level 3		Fair Value
Cash equivalents
Money market fund	$	57,994	$	—	$	—	$	57,994
Total cash equivalents		57,994		—		—		57,994
Short-term marketable securities
Corporate debt securities		—		37,363		—		37,363
Asset-backed securities		—		11,989		—		11,989
U.S. treasury securities		—		123,437		—		123,437
Commercial paper		—		16,867		—		16,867
Total short-term marketable securities		—		189,656		—		189,656
Total assets measured at fair value	$	57,994	$	189,656	$	—	$	247,650


	December 31, 2024
	Level 1		Level 2		Level 3		Fair Value
Cash equivalents
Money market fund	$	29,066	$	—	$	—	$	29,066
U.S. treasury securities		—		8,437		—		8,437
Total cash equivalents		29,066		8,437		—		37,503
Short-term marketable securities
Corporate debt securities		—		20,988		—		20,988
U.S. treasury securities		—		48,117		—		48,117
Commercial paper		—		4,630		—		4,630
Total short-term marketable securities		—		73,735		—		73,735
Total assets measured at fair value	$	29,066	$	82,172	$	—	$	111,238

Money market funds are highly liquid and actively traded marketable securities that generally transact at a stable $1.00 net asset value representing its estimated fair value. The Company estimates the fair value of its U.S. and foreign corporate debt securities, U.S. treasury securities and U.S. and foreign commercial paper by taking into consideration valuations obtained from third-party pricing services. The pricing services utilize industry standard valuation models, including both income and market-based approaches, for which all significant inputs are observable, either directly or indirectly, to estimate fair value. These inputs include reported trades of and broker/dealer quotes on the same or similar securities, issuer credit spreads; benchmark securities; prepayment/default projections based on historical data; and other observable inputs.

There were no transfers between Level 1, Level 2 or Level 3 for any of the years presented.

Summary of Significant Accounting Policies and Recent Accounting Pronouncements (Tables)

12 Months Ended

Dec. 31, 2025

Accounting Policies [Abstract]

Schedule of Earnings Per Share, Basic and Diluted

A reconciliation of the numerators and the denominators of the basic and diluted net loss per common share computations is as follows (in thousands, except for share and per share amounts):


	Year Ended December 31,
	2025			2024
Numerator:
Net loss	$	(6,122	)	$	(40,177	)
Denominator:
Weighted average common shares outstanding - basic and diluted		11,210,934			6,004,560
Net loss per share - basic and diluted	$	(0.55	)	$	(6.69	)

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share

Securities excluded from the computation of diluted net loss per share because including them would have been antidilutive are as follows:


	December 31,
	2025		2024
Warrants to purchase common stock		9,487,477		814,000
Options to purchase common stock		1,193,442		942,193
Common stock subject to purchase under ESPP		6,093		9,386
Unvested RSUs		85,583		52,222
Unvested PSUs		240,832		15,832
Total		11,013,427		1,833,633

Collaboration Agreements (Tables)

12 Months Ended

Dec. 31, 2025

Collaboration Agreement [Abstract]

Schedule of Changes in Contract Liabilities

The following table presents changes in the Company’s contract liabilities under the Gilead Agreements (in thousands):


	Year Ended December 31,
Contract liabilities:	2025			2024
Deferred revenue balance at beginning of period	$	73,000		$	86,294
Cash received		35,233			10,000
Accounts receivable from collaboration with a related party		974			—
Premium on purchase of the Company's common stock		—			5,226
Revenue recognized		(72,303	)		(28,520	)
Deferred revenue balance at end of period	$	36,904		$	73,000
Less: current portion	$	(36,904	)	$	(37,622	)
Deferred revenue from a related party - long-term	$	—		$	35,378

Schedule of Collaboration Revenue Recognized with the Period


	Year Ended December 31,
	2025		2024
Collaboration revenue from a related party recognized in the period from:
Amounts included in deferred revenue from a related party at the beginning of the period	$	36,841	$	28,271
Performance obligations satisfied in previous period	$	—	$	—

Other Accrued Expenses - Schedule of Other Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Accrued expenses:
Accrued compensation	$ 7,523	$ 6,478
Accrued professional fees and other	226	384
Total accrued expenses	$ 7,749	$ 6,862

Summary of Significant Accounting Policies and Recent Accounting Pronouncements - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Aug. 31, 2025
Impairment of long-lived assets	$ 0	$ 0
Accounts receivable from collaboration	$ 974,000	$ 0
Pre-funded warrants sold to purchase common stock			1,040,820
Pre-funded warrants exercise price per share			$ 0.001
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]	true
Change in Accounting Principle, Accounting Standards Update, Adoption Date	Dec. 31, 2025
Accounting Standards Update [Extensible Enumeration]	us-gaap:AccountingStandardsUpdate202309Member
Revenue from Contract with Customer Benchmark \| Customer Concentration Risk \| Gilead Sciences, Inc.
Revenue percentage	100.00%

Investments in Marketable Securities - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2025
Investments in marketable securities:
Investment, Type [Extensible Enumeration]	Cash Equivalents [Member]	Cash Equivalents [Member]
Realized gains and losses	$ 0
Unrealized loss position		$ 0
Accrued interest receivable	400,000	1,500,000
Fair value assets transfers between level 1, level 2 or level 3	$ 0	$ 0
Maximum
Investments in marketable securities:
Available for sale securities maturity term	1 year	1 year
Investment, Type [Extensible Enumeration]	Short Term Marketable Securities [Member]	Short Term Marketable Securities [Member]

- Definition

Indicates type of investment. Includes, but is not limited to, common stock, preferred stock, convertible security, fixed income security, government security, option purchased, warrant, loan participation and assignment, commercial paper, bankers' acceptance, certificates of deposit, short-term security, repurchase agreement, and other investment company.

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- 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

Summary of Significant Accounting Policies and Recent Accounting Pronouncements - Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share (Details) - shares	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive securities excluded from computation of loss per share	11,013,427	1,833,633
Warrants to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive securities excluded from computation of loss per share	9,487,477	814,000
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive securities excluded from computation of loss per share	1,193,442	942,193
Common stock subject to purchase under ESPP
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive securities excluded from computation of loss per share	6,093	9,386
Unvested RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive securities excluded from computation of loss per share	85,583	52,222
Unvested PSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive securities excluded from computation of loss per share	240,832	15,832

Summary of Significant Accounting Policies and Recent Accounting Pronouncements - Schedule of Earnings Per Share, Basic and Diluted (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Numerator:
Net loss	$ (6,122)	$ (40,177)
Denominator:
Weighted average common shares outstanding, basic	11,210,934	6,004,560
Weighted average common shares outstanding, diluted	11,210,934	6,004,560
Net loss per share - basic	$ (0.55)	$ (6.69)
Net loss per share - diluted	$ (0.55)	$ (6.69)

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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-URI https://asc.fasb.org/1943274/2147483621/220-10-S99-2

Reference 21: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(27))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478524/942-220-S99-1

Reference 22: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(23))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477250/944-220-S99-1

Reference 23: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482689/260-10-45-7

Reference 24: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 65
-Paragraph 4
-Subparagraph (f)(4)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481538/470-20-65-4

+ Details

- Definition

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

+ References

+ Details

Insider Trading Policies and Procedures	12 Months Ended
Insider Trading Policies and Procedures	Dec. 31, 2025
Insider Trading Policies and Procedures [Line Items]
Insider Trading Policies and Procedures Adopted	true

Operating Leases (Tables)

12 Months Ended

Dec. 31, 2025

Lease, Cost [Abstract]

Schedule of Quantitative Information of Operating Leases

The following summarizes quantitative information about the Company’s operating leases (in thousands):


	Year Ended December 31,
	2025		2024
Lease cost
Operating lease cost	$	851	$	1,417
Short-term lease cost		—		1
Variable lease cost		817		727
Total lease cost, net	$	1,668	$	2,145

Schedule of Maturities Operating Lease Liabilities

As of December 31, 2025, the maturities of the Company’s operating lease liabilities were as follows (in thousands):


2026	$	806
2027		834
2028		863
2029		671
Total		3,174
Less: present value discount		(546	)
Operating lease liabilities	$	2,628

Investments in Marketable Securities - Schedule of Fair Value of Financial Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Short-term marketable securities
Short-term marketable securities	$ 189,656	$ 73,735
Corporate debt securities
Short-term marketable securities
Short-term marketable securities	37,363	20,988
Asset-backed securities
Short-term marketable securities
Short-term marketable securities	11,989
U.S. treasury securities
Short-term marketable securities
Short-term marketable securities	123,437	48,117
Commercial paper
Short-term marketable securities
Short-term marketable securities	16,867	4,630
Recurring
Cash equivalents
Cash equivalents	57,994	37,503
Short-term marketable securities
Short-term marketable securities	189,656	73,735
Total assets measured at fair value	247,650	111,238
Recurring \| Money market fund
Cash equivalents
Cash equivalents	57,994	29,066
Recurring \| Corporate debt securities
Short-term marketable securities
Short-term marketable securities	37,363	20,988
Recurring \| Asset-backed securities
Short-term marketable securities
Short-term marketable securities	11,989
Recurring \| U.S. treasury securities
Cash equivalents
Cash equivalents		8,437
Short-term marketable securities
Short-term marketable securities	123,437	48,117
Recurring \| Commercial paper
Short-term marketable securities
Short-term marketable securities	16,867	4,630
Recurring \| Level 1
Cash equivalents
Cash equivalents	57,994	29,066
Short-term marketable securities
Short-term marketable securities	0	0
Total assets measured at fair value	57,994	29,066
Recurring \| Level 1 \| Money market fund
Cash equivalents
Cash equivalents	57,994	29,066
Recurring \| Level 1 \| Corporate debt securities
Short-term marketable securities
Short-term marketable securities	0	0
Recurring \| Level 1 \| Asset-backed securities
Short-term marketable securities
Short-term marketable securities	0
Recurring \| Level 1 \| U.S. treasury securities
Cash equivalents
Cash equivalents		0
Short-term marketable securities
Short-term marketable securities	0	0
Recurring \| Level 1 \| Commercial paper
Short-term marketable securities
Short-term marketable securities	0	0
Recurring \| Level 2
Cash equivalents
Cash equivalents	0	8,437
Short-term marketable securities
Short-term marketable securities	189,656	73,735
Total assets measured at fair value	189,656	82,172
Recurring \| Level 2 \| Money market fund
Cash equivalents
Cash equivalents	0	0
Recurring \| Level 2 \| Corporate debt securities
Short-term marketable securities
Short-term marketable securities	37,363	20,988
Recurring \| Level 2 \| Asset-backed securities
Short-term marketable securities
Short-term marketable securities	11,989
Recurring \| Level 2 \| U.S. treasury securities
Cash equivalents
Cash equivalents		8,437
Short-term marketable securities
Short-term marketable securities	123,437	48,117
Recurring \| Level 2 \| Commercial paper
Short-term marketable securities
Short-term marketable securities	16,867	4,630
Recurring \| Level 3
Cash equivalents
Cash equivalents	0	0
Short-term marketable securities
Short-term marketable securities	0	0
Total assets measured at fair value	0	0
Recurring \| Level 3 \| Money market fund
Cash equivalents
Cash equivalents	0	0
Recurring \| Level 3 \| Corporate debt securities
Short-term marketable securities
Short-term marketable securities	0	0
Recurring \| Level 3 \| Asset-backed securities
Short-term marketable securities
Short-term marketable securities	0
Recurring \| Level 3 \| U.S. treasury securities
Cash equivalents
Cash equivalents		0
Short-term marketable securities
Short-term marketable securities	0	0
Recurring \| Level 3 \| Commercial paper
Short-term marketable securities
Short-term marketable securities	$ 0	$ 0

Stockholders' Equity - Summary of Warrants and Pre-funded Warrants to Purchase Shares of Common Stock Issued and Outstanding (Parenthetical) (Details) $ in Millions	1 Months Ended
	Aug. 31, 2025 USD ($) Patients
Class A Warrants
Subsidiary, Sale of Stock [Line Items]
Warrant expiration term	30 days
Number of patients \| Patients	200
Class B Warrants
Subsidiary, Sale of Stock [Line Items]
Aggregate non-dilutive capital \| $	$ 75.0

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2025

Share-Based Payment Arrangement [Abstract]

Summary of Stock Option Activity and Related Information

The following tables summarize the stock option activity and related information for 2025 (in thousands, except for share and per share amounts):


	Number of Shares			Weighted Average Exercise Price Per Share		Weighted Average Remaining Contractual Term (Years)		Total Intrinsic Value (in thousands)
Outstanding as of December 31, 2024		942,193		$	54.24		7.3	$	1,383
Granted		275,225			11.14
Exercised		(5,743	)		22.58
Forfeited		(11,584	)		109.69
Expired		(6,649	)		123.26
Outstanding as of December 31, 2025		1,193,442		$	43.53		7.0	$	17,215
Options vested and exercisable as of December 31, 2025		714,173		$	64.31		5.9	$	6,934
Options expected to vest as of December 31, 2025		1,193,442		$	43.53		7.0	$	17,215


	Year Ended December 31,
	2025		2024
Weighted-average grant-date fair value of options granted	$	8.23	$	10.04
Total intrinsic value of options exercised	$	44	$	2

Summary of Assumptions Used to Estimate Fair Values of Stock Options Grants

The fair value of stock options granted during the periods indicated was estimated using the Black-Scholes option pricing model, based on the following assumptions:


	Year Ended December 31,
	2025	2024
Exercise price	$10.62 - $24.61	$12.90 - $16.75
Expected volatility	81.1% - 86.4%	79.1% - 86.9%
Risk-free rate	3.70% - 4.42%	3.50% - 4.57%
Expected term (years)	5.5 - 7.0	5.5 - 7.5
Expected dividend yield	0%	0%

Summary of Restricted Stock Units and Related Information

The following tables summarize RSU activity and related information for 2025 (in thousands, except for share and per share amounts):


	Number of RSUs			Weighted Average Fair Value Per RSU at Grant Price
Nonvested as of December 31, 2024		52,222		$	17.99
Granted		53,933			10.69
Vested		(18,855	)		21.87
Forfeited		(1,717	)		11.85
Nonvested as of December 31, 2025		85,583		$	12.65


	Year Ended December 31,
	2025		2024
Total fair value of RSUs vested and settled	$	412	$	1,131
Total intrinsic value of RSUs vested and settled	$	203	$	228

Summary of Performence Stock Units and Related Information

The following tables summarize PSU activity and related information for 2025 (in thousands, except for share and per share amounts):


	Number of PSUs		Weighted Average Fair Value Per PSU at Grant Price
Nonvested as of December 31, 2024		15,832	$	20.88
Granted		225,000		17.24
Nonvested as of December 31, 2025		240,832	$	17.48


	Year Ended December 31,
	2025		2024
Total fair value of PSUs vested and settled	$	—	$	1,029
Total intrinsic value of PSUs vested and settled	$	—	$	488

Schedule of Recognized Stock-Based Compensation Expense

The Company recognized stock-based compensation expense included in the consolidated statement of operations and comprehensive loss for the years presented (in thousands), classified by expense type and award type:


	Year Ended December 31,
	2025		2024
Research and development	$	2,628	$	1,531
General and administrative		2,049		1,589
Total stock-based compensation expense	$	4,677	$	3,120


	Year Ended December 31,
	2025		2024
Stock options	$	2,387	$	2,511
RSUs		427		368
PSUs		1,552		139
ESPP		311		102
Total stock-based compensation expense	$	4,677	$	3,120

Operating Leases - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended
	Aug. 31, 2023	Dec. 31, 2025	Dec. 31, 2024
Leases [Abstract]
Lease expiration, month and year	2025-10
Lessee, operating lease, lease not yet commenced, option to extend	through September 2029
Operating lease, liability		$ 2,628
Operating lease, right-of-use asset		$ 2,508	$ 3,069
Weighted-average remaining lease term - operating leases		3 years 9 months 18 days
Weighted-average discount rate - operating leases		10.00%

Segment Reporting - Additional Information (Details)	12 Months Ended
Segment Reporting - Additional Information (Details)	Dec. 31, 2025 Segment
Segment Reporting [Abstract]
Number of operating segment	1
Segment reporting, CODM, individual title and position or group name	srt:ChiefExecutiveOfficerMember
Segment reporting, CODM, profit (loss) measure	The measure of segment profit or loss used by the CODM to evaluate performance and allocate resources is consolidated net loss as reported in the Company's consolidated statements of operations. This measure is used by the CODM to assess its cash runway and make strategic decisions about resource allocation. The CODM does not use asset measures to evaluate segment performance or make resource allocation decisions.
Segment reporting, expense information used by CODM	Operating expenses include all costs necessary to operate the Company's business, primarily consisting of research and development and general and administrative expenses directly related to advancing the Company's programs. These expenses are reviewed by the CODM on a consolidated basis as part of evaluating the Company's overall financial performance.

Summary of Significant Accounting Policies and Recent Accounting Pronouncements (Policies)

12 Months Ended

Dec. 31, 2025

Accounting Policies [Abstract]

Basis of Presentation

These consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (U.S. 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 U.S. GAAP requires management to make estimates and assumptions that may affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and reported amounts of expenses during the reporting period. Actual results could differ from those estimates.

Significant estimates inherent in the preparation of the accompanying consolidated financial statements include estimates for revenue recognition, including the standalone selling price (SSP) for the allocation of transaction price to performance obligations and cost-based inputs, as well as estimates of costs incurred but not yet invoiced for research and development accruals.

The Company’s estimates could be affected by external conditions, including those unique to the Company and general economic conditions. It is reasonably possible these external factors could have an effect on the Company’s estimates and could cause actual results to differ materially from those estimates and assumptions.

Other Risks and Uncertainties

U.S. and global financial markets have experienced and may continue to experience volatility and disruption due to macroeconomic and geopolitical events such as rising inflation, changes in interest rates to combat inflation, the war between Russia and Ukraine, the conflicts in the Middle East, including the recent hostilities involving Iran, and in Venezuela, tensions between China and Taiwan, as well as tariffs or the imposition and enforceability of tariffs, trade wars, barriers or restrictions, or threats of such actions and the related uncertainty thereof, including uncertainties regarding the ability to obtain refunds for previously paid tariffs that have subsequently been invalidated. The Company cannot predict at this time to what extent, if at all, it and its employees, contract research organizations (CROs), vendors and/or collaborators could potentially be negatively impacted by these events.

Cash and Cash Equivalents

All highly liquid investments with original maturities of three months or less at the time of purchase are considered to be cash equivalents. All of the Company’s cash equivalents have liquid markets and high credit ratings.

Investments in Marketable Securities

The Company has designated its investments in marketable securities as available-for-sale and measures these securities at their respective fair values. The Company reviews all available-for-sale securities at each period end to determine if they remain available-for-sale based on their current intent and ability to sell the security if it is required to do so. Marketable securities are classified as short-term or long-term based on the maturity date and their availability to meet current operating requirements. Marketable securities that mature in one year or less from the consolidated balance sheet date are classified as short-term available-for-sale securities, while marketable securities with maturities in one year or beyond one year from the consolidated balance sheet date are classified as long-term.

The Company periodically reviews its marketable securities for declines in fair value below the amortized cost basis to determine whether the impairment, if any, is due to credit-related or other factors. This review includes the credit worthiness of the security issuers, the severity of the unrealized losses, whether the Company has the intent to sell the securities and whether it is more likely than not the Company will be required to sell the securities before the recovery of the amortized cost basis. Unrealized gains and losses on available-for-sale securities are reported in other comprehensive loss, and as a component of stockholders' equity until their disposition, with the exception of unrealized losses believed to be related to credit losses which are recognized as an allowance for credit losses on the consolidated balance sheet with the corresponding charge in other income in the period the impairment occurs. Impairment assessments are made at the individual security level each reporting period. The Company elected to exclude accrued interest receivable from the amortized cost basis of its available-for-sale debt securities and to not measure an allowance for credit losses for accrued interest receivable. To date, there have been no credit-related declines in value or other impairments of the Company’s investments in marketable securities. Realized gains and losses from the sale of marketable securities, if any, are calculated using the specific-identification method.

Leases

All of the Company’s leases are operating leases for facilities and equipment. The Company recognizes a lease asset for its right to use the underlying asset and a lease liability for the corresponding lease obligation. The Company determines if an arrangement is or contains a lease at inception or modification of the arrangement. Operating leases with a duration greater than one year are included in operating lease ROU assets, operating lease liabilities - short-term, and operating lease liabilities - long-term in the Company’s consolidated balance sheets. The Company elected the short-term lease exception policy, permitting it to not apply the recognition requirements to leases with terms of less than one year (short-term leases) for all classes of assets. Operating lease ROU assets and liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. In determining the net present value of lease payments, the Company uses its incremental borrowing rate based on the information available at the lease commencement date. The incremental borrowing rate represents the interest rate the Company would incur at lease commencement to borrow an amount equal to the lease payments on a collateralized basis over

the term of a lease. The Company considers a lease term to be the noncancelable period that it has the right to use the underlying asset, including any periods where it is reasonably assured the Company will exercise the option to extend the contract. Periods covered by an option to extend are included in the lease term if the lessor controls the exercise of that option.

The operating lease ROU assets also include any lease payments made and exclude lease incentives. Lease expense is recognized on a straight-line basis over the expected lease term. Variable lease expenses are recorded when incurred. The Company has elected not to separate lease and non-lease components for its leased assets and accounts for all lease and non-lease components of its agreements as a single lease component.

Impairment of Long-Lived Assets

The Company monitors the carrying value of long-lived assets, including ROU operating lease assets, for potential impairment and tests the recoverability of such assets whenever events or changes in circumstances indicate the carrying amounts may not be recoverable. If a change in circumstance occurs, the Company performs a test of recoverability by comparing the carrying value of the asset or asset group to its undiscounted expected future cash flows. If cash flows cannot be separately and independently identified for a single asset, the Company will determine whether impairment has occurred for the group of assets for which the Company can identify the projected cash flows. If the carrying values are in excess of undiscounted expected future cash flows, the Company measures any impairment by comparing the fair value of the asset or asset group to its carrying value. There was no impairment of long-lived assets during the years ended December 31, 2025 and 2024.

Fair Value Measurements

The Company follows accounting guidance on fair value measurements for financial instruments measured on a recurring basis, as well as for certain assets and liabilities that are initially recorded at their estimated fair values. Fair value is defined as the exit price, or the amount that would be received from selling an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The Company uses the following three-level hierarchy that maximizes the use of observable inputs and minimizes the use of unobservable inputs to value its financial instruments:

Level 1: Observable inputs such as unadjusted quoted prices in active markets for identical instruments.

Level 2: Quoted prices for similar instruments that are directly or indirectly observable in the marketplace.

Level 3: Significant unobservable inputs which are supported by little or no market activity and that are financial instruments whose values are determined using pricing models, discounted cash flow methodologies, or similar techniques, as well as instruments for which the determination of fair value requires significant judgment or estimation.

Financial instruments measured at fair value are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The assessment of the significance of a particular input to the fair value measurement in its entirety requires the Company to make judgments and consider factors specific to the asset or liability. The use of different assumptions and/or estimation methodologies may have a material effect on estimated fair values. Accordingly, the fair value estimates disclosed or initial amounts recorded may not be indicative of the amount the Company or holders of the instruments could realize in a current market exchange.

The carrying amounts of cash equivalents and marketable securities approximate their fair value based upon quoted market prices. Certain of the Company’s financial instruments are not measured at fair value on a recurring basis but are recorded at amounts which approximate their fair value due to their liquid or short-term nature, such as cash, accounts receivable, accounts payable and accrued expenses.

Revenue Recognition and Accounts Receivable from Collaborations

Revenue Recognition and Accounts Receivable from Collaboration

The Company analyzes its collaboration arrangements to assess whether such arrangements, or transactions between arrangement participants, involve joint operating activities performed by parties that are both active participants in the activities and exposed to significant risks and rewards dependent on the commercial success of such activities or are more akin to a vendor-customer relationship. In making this evaluation, the Company considers whether the activities of the collaboration are considered to be distinct and deemed to be within the scope of the collaborative arrangement accounting standard and those that are more reflective of a vendor-customer relationship and, therefore, within the scope of the revenue with contracts with customers accounting standard. This assessment is performed throughout the life of the arrangement based on changes in the responsibilities of all parties in the arrangement.

For elements of collaboration arrangements that are not accounted for pursuant to the revenue from contracts with customers accounting standard, an appropriate recognition method is determined and applied consistently, generally by analogy to the revenue from contracts with customers accounting standard. Amounts related to transactions with a counterparty in a collaborative arrangement that is not a customer are presented on a separate line item from revenue recognized from contracts with customers, if any, in the Company’s consolidated statements of operations and comprehensive loss.

Under certain agreements under the scope of the collaborative arrangements accounting standard, the Company has been reimbursed for a portion of its research and development expenses or participates in the cost-sharing of such research and development expenses. Such reimbursements and cost-sharing arrangements are reflected as a reduction of research and development expense in the Company’s consolidated statements of operations and comprehensive loss.

For arrangements or transactions between arrangement participants determined to be within the scope of the contracts with customers accounting standard, the Company evaluates the term of the arrangement and recognizes revenue when the customer obtains control of promised goods or services in a contract for an amount that reflects the consideration the Company expects to receive in exchange for those goods or services. For contracts with customers, the Company applies the following five-step model in order to determine this amount: (1) identification of the contract(s) with a customer; (2) identification of the performance obligations in the contract, including whether they are distinct in the context of the contract; (3) measurement of the transaction price, including the constraint on variable consideration; (4) allocation of the transaction price to the performance obligations; and (5) recognition of revenue when (or as) the Company satisfies each performance obligation. Amounts of variable consideration are included in the transaction price to the extent it is probable a significant reversal in the amount of cumulative revenue recognized will not occur and when the uncertainty associated with the variable consideration is subsequently resolved.

The Company has provided standard indemnification and protection of licensed intellectual property for its customers. These provisions are part of assurance the licenses meet the agreements, representations and are not obligations to provide goods or services.

The Company only applies the five-step model to contracts when it is probable the Company will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. As part of the accounting for contracts with customers, the Company must develop assumptions that require judgment to determine the estimated relative SSP of each performance obligation identified in the contract. The Company then allocates the total transaction price to each performance obligation based on the SSP of each performance obligation. The Company recognizes the amount of the transaction price that is allocated to the respective performance obligation when the performance obligation is satisfied or as it is satisfied as revenue.

Contract modifications, defined as changes in the scope or price (or both) of a contract that are approved by the parties to the contract, such as a contract amendment, exist when the parties to a contract approve a modification that either creates new, or changes existing, enforceable rights and obligations of the parties to the contract. The Company accounts for contract modifications using one of the following methods depending on facts and circumstances: (i) as a separate contract if the modification adds distinct goods or services and the price reflects the SSP of those additional goods or services; (ii) as a termination of the existing contract and creation of a new contract if the remaining goods or services are distinct from those transferred before the modification; or (iii) as a cumulative catch-up adjustment to the original contract if the remaining goods or services are not distinct from those transferred before the modification.

Licenses

If a license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenues from license fees based on the relative value prescribed to the license compared to the total value of the arrangement. The revenue is recognized when the license is transferred to the collaborator and the collaborator is able to use and benefit from the license. For licenses that are not distinct from other obligations identified in the arrangement, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time. If the combined performance obligation is satisfied over time, the Company applies an appropriate method of measuring progress for purposes of recognizing revenue from license fees. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition.

Research and Development Services

The promises under the Company’s agreements may include research and development services to be performed by the Company on behalf of the counterparty. If these services are determined to be distinct from the other promises or performance obligations identified in the arrangement, the Company recognizes the transaction price allocated to these services as revenue over time based on an appropriate measure of progress when the performance by the Company does not create an asset with an alternative use and the Company either has received or has an enforceable right to payment for the performance completed to date. If these services are determined not to be distinct from the other promises or performance obligations identified in the arrangement, the Company recognizes the transaction price allocated to the combined performance obligation as the related performance obligations are satisfied.

Customer Options

If an arrangement contains customer options, the Company evaluates whether the options are material rights because they allow the customer to acquire additional goods or services for free or at a discount. If the customer options are determined to represent a material right, the material right is recognized as a separate performance obligation at the outset of the arrangement. The identification of a material right, and if identified as a material right, the allocation of the transaction price to it, is based on the SSP, which is determined using assumptions regarding estimated costs, discount rates, post-option development timeline, the probability of technical and regulatory success and the probability the customer will exercise the option. Amounts allocated to a material right are not recognized as revenue until, at the earliest, the option is exercised or expires. If the options are deemed not to be a material right, they are considered marketing offers which are excluded as performance obligations at the outset of the arrangement.

Development and Regulatory Milestone Payments

Depending on facts and circumstances, the Company may record revenues from certain milestones in a reporting period before the milestone is achieved if the Company concludes achievement of the milestone is probable and recognition of revenue related to the milestone will not result in a significant reversal in amounts recognized in future periods. The Company records a corresponding contract asset when this conclusion is reached. Milestone payments that have not been included in the transaction price to date are fully constrained. The Company re-evaluates the probability of achievement of such milestones and any related constraint each reporting period. The Company adjusts its estimate of the overall transaction price, including the amount of collaborative revenue that was recorded, if necessary.

Sales-based Milestone and Royalty Payments

The Company’s customers may be required to pay the Company sales-based milestone payments or royalties on future sales of commercial products. The Company recognizes revenues related to sales-based milestone and royalty payments upon the later to occur of (i) achievement of the collaborator’s underlying sales or (ii) satisfaction of any performance obligation(s) related to these sales, in each case assuming the Company’s licensed intellectual property is deemed to be the predominant item to which the sales-based milestones and/or royalties relate.

The Company receives payments from its customers based on billing schedules established in the contract. Upfront payments and fees are recorded as deferred revenue upon receipt or when due until the Company performs its obligations under the arrangement. If the related performance obligation is expected to be satisfied within the next twelve months, these amounts will be classified in current liabilities. The Company recognizes a contract asset relating to its conditional right to consideration that is not subject to a constraint. Amounts are recorded as accounts receivable when the Company’s right to consideration is unconditional.

A net contract asset or liability is presented for each contract with a customer. The Company does not assess whether a contract has a significant financing component if the expectation at contract inception is such that the period between payment by the customer and the transfer of the promised goods or services to the customer will be one year or less.

At December 31, 2025, all accounts receivable from collaboration with a related party are deemed collectible. There were no accounts receivable from collaboration as of December 31, 2024.

Warrants and Pre-Funded Warrants

The Company determines the accounting classification of warrants it issues as either liability or equity-classified based on an assessment of the warrant’s specific terms. The assessment considers whether the warrants are freestanding

financial instruments, whether the warrants meet the definition of a liability and whether the warrants meet all the requirements for equity classification. Equity classified warrants are accounted for using a relative fair value allocation method, with fair values determined at issuance using a Black-Scholes model.

Stock-Based Compensation

The Company measures stock-based compensation to employees and board members at fair value on the grant date of the award. The fair value of RSUs is determined based on the number of shares granted and the quoted market price of the Company’s common stock on the date of grant. The fair value of performance stock units (PSUs), which include awards with performance conditions and market conditions, are determined as follows: (i) PSUs with performance conditions are measured based on the fair value of the award on the grant date, the date performance targets are established, and is expensed over the requisite service period for each separately vesting tranche when achievement of the performance condition becomes probable, and (ii) PSUs with market conditions are measured based on the grant-date fair value of the award and is expensed over the derived service period regardless of whether the underlying market condition is met.

The Company estimates the fair value of stock option grants that do not contain market-based vesting conditions using the Black-Scholes option pricing model. The assumptions used in estimating the fair value of these awards, such as expected term, expected dividend yield, volatility and risk-free interest rate, represent management’s best estimates and involve inherent uncertainties and the application of management’s judgment. The Company calculates the weighted average expected term of options using the simplified method where permitted by accounting guidance for stock-based compensation when there is limited history of relevant stock option exercise activity. The Company uses an expected dividend yield of zero as the Company currently does not intend to pay dividends in the foreseeable future. The Company calculates the expected volatility based on the Company’s historical stock prices. The risk-free interest rate assumption is based on the rates for U.S. Treasury zero-coupon bonds with maturities similar to those of the expected term of the stock option being valued.

If stock-based awards are granted in contemplation of or shortly before a planned release of material nonpublic information, and such information is expected to result in a material increase in the Company’s share price, the Company considers whether an adjustment to the observable market price is required when estimating fair values. Compensation cost is recognized as expense on a straight-line basis over the requisite service period of the award. Stock-based awards with graded vesting schedules are recognized using the accelerated attribution method on a straight-line basis over the requisite service period for each separately vesting portion of the award. Forfeitures are recognized when they occur.

The Company assesses the probability of the performance conditions being met on a continuous basis and is also required to make estimates as to the probability of achieving the specific performance conditions. If actual results are not consistent with the Company’s assumptions and judgments used in making these estimates, the Company may be required to increase or decrease compensation expense, which could be material to the Company’s consolidated results of operations.

Research and Development Expense and Accruals

Research and development costs include personnel-related costs, outside contracted services including clinical study costs, facilities costs, fees paid to consultants, milestone payments prior to FDA approval, license fees prior to FDA approval, professional services, travel costs, dues and subscriptions, depreciation and materials used in clinical trials and research and development and costs incurred under the Company’s collaboration agreements. Research and development costs are expensed as incurred unless there is an alternative future use in other research and development projects. Payments made prior to the receipt of goods or services to be used in research and development are capitalized until the goods or services are received. Such payments are evaluated for current or long-term classification based on when they will be realized or consumed.

The Company records expenses related to clinical studies and manufacturing development activities based on its estimates of the services received and efforts expended pursuant to contracts with multiple CROs and manufacturing vendors that conduct and manage these activities on its behalf. The financial terms of these agreements are subject to negotiation, vary from contract to contract, and may result in uneven payment flows. There may be instances in which payments made to the Company’s vendors will exceed the level of services provided and result in a prepayment of the expense. Payments under some of these contracts depend on factors such as the successful enrollment of subjects and

the completion of clinical study milestones. In amortizing or accruing service fees, the Company estimates the time period over which services will be performed, enrollment of subjects, number of sites activated and the level of effort expended in each period. If the actual timing of the performance of services or the level of effort varies from the Company’s estimate, the Company will adjust the accrued or prepaid expense balance accordingly. To date, there have been no material differences from the Company’s estimates to the amounts actually incurred.

The Company has entered and may continue to enter into license agreements to access and utilize certain technology. In each case, the Company evaluates if the license agreement results in the acquisition of an asset or a business. To date, none of the Company’s license agreements have been considered to be acquisitions of businesses. For asset acquisitions, the upfront payments to acquire such licenses, as well as any future milestone payments, are immediately recognized as research and development expense when paid, provided there is no alternative future use of the rights in other research and development projects. These license agreements may also include contingent consideration in the form of cash payments to be made for future milestone events. The Company assesses whether such contingent consideration meets the definition of a derivative and to date the Company has determined that such contingent consideration are not derivatives.

Income Taxes

The Company records income taxes using the asset and liability method. Deferred income tax assets and liabilities are recognized for the future tax effects attributable to temporary differences between the financial statement carrying amounts of existing assets and liabilities and their respective income tax bases, and operating loss and tax credit carryforwards. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in income in the period that includes the enactment date. The Company establishes a valuation allowance if it is more likely than not the deferred tax assets will not be realized based on an evaluation of objective verifiable evidence.

The Company recognizes and measures tax benefits from uncertain tax positions only if it is more likely than not the tax position will be sustained in an audit, including resolution of any related appeals or litigation processes. The tax benefit recognized for a particular tax position is based on the largest amount that is more than 50% likely to be realized upon ultimate settlement. Significant judgment is required to evaluate uncertain tax positions. The Company evaluates uncertain tax positions on a regular basis. The evaluations are based on a number of factors, including changes in facts and circumstances, changes in tax law, correspondence with tax authorities during the course of the audit, and effective settlement of audit issues. The provision for income taxes includes the effects of any accruals which the Company believes are appropriate. It is the Company’s policy to recognize interest and penalties related to income tax matters in income tax expense.

In July 2025, the U.S. enacted tax reform legislation through the One Big Beautiful Bill Act (OBBBA). Some of the provisions of the new tax law affecting corporations include but are not limited to current deduction of domestic research expenses, increasing the limit of the deduction of interest expense deduction to thirty percent of earnings before interest, tax, depreciation and amortization, and one hundred percent bonus depreciation on eligible property acquired after January 19, 2025. The Company has evaluated the impact the new tax law had on its financial condition and results of operations. The impact of the tax law changes from the OBBBA is included in the Company’s consolidated financial statements.

Net Loss per Share

Basic net loss per common share excludes dilution and is computed by dividing net loss by the weighted average number of common shares outstanding during the period. Diluted net loss per common share reflects the potential dilution that could occur if securities or other contracts to issue common stock were exercised or converted into common stock or resulted in the issuance of common stock that then shared in the earnings of the entity unless inclusion of such shares would be anti-dilutive. Diluted net loss per share is the same as basic net loss per share in the years reported, since the effects of potentially dilutive securities are antidilutive given the net loss for each year presented.

A reconciliation of the numerators and the denominators of the basic and diluted net loss per common share computations is as follows (in thousands, except for share and per share amounts):


	Year Ended December 31,
	2025			2024
Numerator:
Net loss	$	(6,122	)	$	(40,177	)
Denominator:
Weighted average common shares outstanding - basic and diluted		11,210,934			6,004,560
Net loss per share - basic and diluted	$	(0.55	)	$	(6.69	)

Securities excluded from the computation of diluted net loss per share because including them would have been antidilutive are as follows:


	December 31,
	2025		2024
Warrants to purchase common stock		9,487,477		814,000
Options to purchase common stock		1,193,442		942,193
Common stock subject to purchase under ESPP		6,093		9,386
Unvested RSUs		85,583		52,222
Unvested PSUs		240,832		15,832
Total		11,013,427		1,833,633

In August 2025, the Company sold pre-funded warrants to purchase up to 1,040,820 shares of common stock (see Note 6 - Stockholders' Equity). The pre-funded warrants are exercisable at $0.001 per share. The shares of common stock into which the pre-funded warrants may be exercised are considered outstanding for purposes of computing earnings per share because the shares may be issued for little or no consideration, they are fully vested, and are exercisable after the original issuance date.

Comprehensive Loss

Comprehensive loss is comprised of net loss and adjustments for the change in unrealized gains and losses on investments in available-for-sale marketable securities. The Company displays comprehensive loss and its components in the consolidated statements of operations and comprehensive loss, net of tax effects if any.

Concentrations of Risk

Credit Risk

Financial instruments which potentially subject the Company to credit risk consist primarily of cash, cash equivalents and marketable securities. The Company holds these investments in highly rated financial institutions, and, by policy, limits the amounts of credit exposure to any one financial institution. These amounts as of and at times during the year ended December 31, 2025 exceeded federally insured limits. The Company has not experienced any credit losses in such accounts and does not believe it is exposed to any significant credit risk on these funds. The Company has no off-balance sheet concentrations of credit risk, such as foreign currency exchange contracts, option contracts or other hedging arrangements.

Supplier Risk

Certain materials and key components the Company utilizes in its operations are obtained through single suppliers. Since the suppliers of key components and materials must be named in a New Drug Application filed with the FDA for a product, significant delays can occur if the qualification of a new supplier is required. If delivery of material from the Company’s suppliers were interrupted for any reason, the Company may be unable to supply any of its product candidates for clinical trials.

Customer Risk

During the year ended December 31, 2025, 100% of the Company's collaboration revenue was recognized from a related party, Gilead, under the Gilead Collaboration Agreement (see Note 8 - Collaboration Agreements). If the collaboration with Gilead does not result in the successful development and commercialization of products or if Gilead terminates the Gilead Collaboration Agreement, the Company may not receive any future payments under the collaboration.

Recently Adopted Accounting Standards and Accounting Pronouncements to Be Adopted

Recently Adopted Accounting Standards

In December 2023, the Financial Accounting Standards Board (the FASB) issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures (ASU 2023-09). The update requires a public business entity to disclose, on an annual basis, a tabular rate reconciliation using both percentages and currency amounts, broken out into specified categories with certain reconciling items further broken out by nature and jurisdiction to the extent those items exceed a specified threshold. In addition, all entities are required to disclose income taxes paid, net of refunds received disaggregated by federal, state/local, and foreign and by jurisdiction if the amount is at least 5% of total income tax payments, net of refunds received. The Company adopted ASU 2023-09 on a prospective basis during the year ended December 31, 2025. See Note 10 - Income Taxes for further details.

Accounting Pronouncements to Be Adopted

In November 2024, the FASB issued ASU 2024-03, Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses (ASU 2024-03), which requires the disaggregation of certain expense captions into specified categories in disclosures within the notes to the financial statements to provide enhanced transparency into the expense captions presented on the face of the income statement. ASU 2024-03 is effective for annual reporting periods beginning after December 15, 2026 and interim periods beginning after December 15, 2027, with early adoption permitted, and may be applied either prospectively or retrospectively to financial statements issued for reporting periods after the effective date of ASU 2024-03 or retrospectively to any or all prior periods presented in the financial statements. The Company does not expect the potential impact of adopting ASU 2024-03 to have a material impact on its disclosures.

In December 2025, the FASB issued ASU 2025-11, Interim Reporting (Topic 270): Narrow-Scope Improvements (ASU 2025-11), which clarifies the guidance in Topic 270 to improve the consistency of interim financial reporting. The ASU provides a comprehensive list of required interim disclosures and introduces a disclosure principle requiring entities to disclose events since the end of the last annual reporting period that have a material impact on the entity. ASU 2025-11 is effective for fiscal years beginning after December 15, 2027, including interim periods within those fiscal years, with early adoption permitted. The Company does not expect the impact of adopting ASU 2025-11 to have a material impact on its financial statements.

Investments in Marketable Securities - Schedule of Investments in Marketable Available-for-Sale Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Investments in marketable securities:
Amortized Cost	$ 58,450	$ 38,344
Investment, Type [Extensible Enumeration]	Cash equivalents	Cash equivalents
Amortized Cost, Short-term marketable securities	$ 189,424	$ 73,673
Gross Unrealized Gain, Short-term marketable securities	232	65
Gross Unrealized Loss, Short-term marketable securities	0	(3)
Fair Value, Short-term marketable securities	189,656	73,735
Amortized Cost	247,418	111,176
Gross Unrealized Gain	232	65
Gross Unrealized Loss	0	(3)
Fair Value	247,650	111,238
Cash equivalents
Investments in marketable securities:
Amortized Cost	57,994	37,503
Gross Unrealized Gain	0	0
Gross Unrealized Loss	0	0
Fair Value	57,994	37,503
Cash equivalents \| Money market fund
Investments in marketable securities:
Amortized Cost	57,994	29,066
Gross Unrealized Gain	0	0
Gross Unrealized Loss	0	0
Fair Value	57,994	29,066
Corporate debt securities
Investments in marketable securities:
Amortized Cost, Short-term marketable securities	37,329	20,971
Gross Unrealized Gain, Short-term marketable securities	34	20
Gross Unrealized Loss, Short-term marketable securities	0	(3)
Fair Value, Short-term marketable securities	37,363	20,988
Asset-backed securities
Investments in marketable securities:
Amortized Cost, Short-term marketable securities	11,970
Gross Unrealized Gain, Short-term marketable securities	19
Gross Unrealized Loss, Short-term marketable securities	0
Fair Value, Short-term marketable securities	11,989
U.S. treasury securities
Investments in marketable securities:
Amortized Cost, Short-term marketable securities	123,267	48,077
Gross Unrealized Gain, Short-term marketable securities	170	40
Gross Unrealized Loss, Short-term marketable securities	0	0
Fair Value, Short-term marketable securities	123,437	48,117
U.S. treasury securities \| Cash equivalents
Investments in marketable securities:
Amortized Cost		8,437
Gross Unrealized Gain		0
Gross Unrealized Loss		0
Fair Value		8,437
Commercial paper
Investments in marketable securities:
Amortized Cost, Short-term marketable securities	16,858	4,625
Gross Unrealized Gain, Short-term marketable securities	9	5
Gross Unrealized Loss, Short-term marketable securities	0	0
Fair Value, Short-term marketable securities	$ 16,867	$ 4,630

Operating Leases - Schedule of Maturities Operating Lease Liabilities (Details) $ in Thousands	Dec. 31, 2025 USD ($)
Lease, Cost [Abstract]
2026	$ 806
2027	834
2028	863
2029	671
Total	3,174
Less: present value discount	(546)
Operating lease liabilities	$ 2,628

Stock-Based Compensation - Summary of Restricted Stock Units and Related Information (Details) - RSUs - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Number of Shares
Beginning of period	52,222
Granted	53,933
Vested	(18,855)
Forfeited	(1,717)
Ending of period	85,583	52,222
Weighted Average Fair Value Per RSU at Grant Price
Beginning of period	$ 17.99
Granted	10.69
Vested	21.87
Forfeited	11.85
Ending of period	$ 12.65	$ 17.99
Total fair value of awards vested and settled	$ 412	$ 1,131
Total intrinsic value of awards vested and settled	$ 203	$ 228

Stock-Based Compensation

12 Months Ended

Dec. 31, 2025

Share-Based Payment Arrangement [Abstract]

Stock-Based Compensation

Note 7 - Stock-Based Compensation

Equity Incentive Plans

In June 2025, the Company's stockholders approved an amendment to the Assembly Biosciences, Inc. Amended and Restated 2018 Stock Incentive Plan (the 2018 Plan), which increased the aggregate number of shares of common stock reserved under the 2018 Plan to 1,703,333.

As of December 31, 2025, the Company had awards outstanding under the following shareholder approved plans: 2010 Equity Incentive Plan (the 2010 Plan), which has been frozen since 2016; the Assembly Biosciences, Inc.

Amended and Restated 2014 Stock Incentive Plan (the 2014 Plan); and the 2018 Plan. Shares of common stock underlying awards forfeited under the 2010 Plan on or after June 2, 2016 become available for issuance under the 2014 Plan. As of December 31, 2025, the Company also had awards outstanding under the following plans that are not approved by shareholders: the Assembly Biosciences, Inc. 2017 Inducement Award Plan, the Assembly Biosciences, Inc. 2019 Inducement Award Plan, and the Assembly Biosciences, Inc. 2020 Inducement Award Plan.

The Company issues new shares of common stock to settle options exercised and vested RSUs or PSUs. The Company also issues new shares of common stock in connection with purchases of shares of common stock by eligible employees under the ESPP.

Stock Plan Activity

Stock Options

The following tables summarize the stock option activity and related information for 2025 (in thousands, except for share and per share amounts):


	Number of Shares			Weighted Average Exercise Price Per Share		Weighted Average Remaining Contractual Term (Years)		Total Intrinsic Value (in thousands)
Outstanding as of December 31, 2024		942,193		$	54.24		7.3	$	1,383
Granted		275,225			11.14
Exercised		(5,743	)		22.58
Forfeited		(11,584	)		109.69
Expired		(6,649	)		123.26
Outstanding as of December 31, 2025		1,193,442		$	43.53		7.0	$	17,215
Options vested and exercisable as of December 31, 2025		714,173		$	64.31		5.9	$	6,934
Options expected to vest as of December 31, 2025		1,193,442		$	43.53		7.0	$	17,215


	Year Ended December 31,
	2025		2024
Weighted-average grant-date fair value of options granted	$	8.23	$	10.04
Total intrinsic value of options exercised	$	44	$	2

The fair value of stock options granted during the periods indicated was estimated using the Black-Scholes option pricing model, based on the following assumptions:


	Year Ended December 31,
	2025	2024
Exercise price	$10.62 - $24.61	$12.90 - $16.75
Expected volatility	81.1% - 86.4%	79.1% - 86.9%
Risk-free rate	3.70% - 4.42%	3.50% - 4.57%
Expected term (years)	5.5 - 7.0	5.5 - 7.5
Expected dividend yield	0%	0%

RSUs

The following tables summarize RSU activity and related information for 2025 (in thousands, except for share and per share amounts):


	Number of RSUs			Weighted Average Fair Value Per RSU at Grant Price
Nonvested as of December 31, 2024		52,222		$	17.99
Granted		53,933			10.69
Vested		(18,855	)		21.87
Forfeited		(1,717	)		11.85
Nonvested as of December 31, 2025		85,583		$	12.65


	Year Ended December 31,
	2025		2024
Total fair value of RSUs vested and settled	$	412	$	1,131
Total intrinsic value of RSUs vested and settled	$	203	$	228

PSUs

The following tables summarize PSU activity and related information for 2025 (in thousands, except for share and per share amounts):


	Number of PSUs		Weighted Average Fair Value Per PSU at Grant Price
Nonvested as of December 31, 2024		15,832	$	20.88
Granted		225,000		17.24
Nonvested as of December 31, 2025		240,832	$	17.48


	Year Ended December 31,
	2025		2024
Total fair value of PSUs vested and settled	$	—	$	1,029
Total intrinsic value of PSUs vested and settled	$	—	$	488

ESPP

In June 2025, the Company's stockholders approved an amendment to the ESPP, which increased the aggregate number of shares of common stock available for purchase by employees up to 225,000 shares at a discount to the market price.

Eligible employees may participate through payroll deductions of up to 15% of such employee’s compensation for each pay period subject to annual statutory limits.

Eligible employees can purchase the Company’s common stock at the end of a predetermined offering period at 85% of the lower of the fair market value at the beginning or end of the offering period. Under the ESPP, the offering periods end on the last business day occurring on or before May 14 or November 14. The ESPP is compensatory and results in stock-based compensation expense.

In May and November 2025, employees purchased 34,696 and 34,624 shares of common stock, respectively, under the ESPP. In May and November 2024, employees purchased 7,252 and 7,685 shares of common stock, respectively, under the ESPP. As of December 31, 2025, 86,097 shares of common stock are available for future sale under the Company’s ESPP.

The fair value of ESPP purchase rights were not material for any period presented.

Stock-Based Compensation Expense


	Year Ended December 31,
	2025		2024
Research and development	$	2,628	$	1,531
General and administrative		2,049		1,589
Total stock-based compensation expense	$	4,677	$	3,120


	Year Ended December 31,
	2025		2024
Stock options	$	2,387	$	2,511
RSUs		427		368
PSUs		1,552		139
ESPP		311		102
Total stock-based compensation expense	$	4,677	$	3,120

As of December 31, 2025, there was $4.6 million of total unrecognized stock-based compensation cost related to outstanding unvested equity awards, which is expected to be recognized over a weighted average remaining amortization period of 1.3 years.

Stockholders' Equity - Additional Information (Details) $ / shares in Units, $ in Millions			1 Months Ended				12 Months Ended
	Feb. 09, 2024 shares	Feb. 08, 2024 shares	Aug. 31, 2025 USD ($) $ / shares shares	Dec. 31, 2024 USD ($) $ / shares shares	Jun. 30, 2024 USD ($) $ / shares shares	Jan. 31, 2024	Dec. 31, 2025 USD ($) shares	Dec. 31, 2024 USD ($) $ / shares shares	Nov. 30, 2024 USD ($)
Subsidiary Sale Of Stock [Line Items]
Preferred stock, shares authorized				5,000,000			5,000,000	5,000,000
Common stock, shares authorized				150,000,000			150,000,000	150,000,000
Preferred stock, shares issued				0			0	0
Preferred stock, shares outstanding				0			0	0
Reverse stock split ratio		0.0833				0.0833
Reverse stock split description							In January 2024, the Company's stockholders approved a reverse stock split of its common stock at a range of ratios between 1-for-7 to 1-for-17, and the Company's board of directors approved the implementation of the reverse stock split at a ratio of 1-for-12 (the Reverse Stock Split). The Reverse Stock Split was undertaken to enable the Company to regain compliance with the minimum bid price requirement for continued listing on the Nasdaq Global Select Market, as referenced in the deficiency notice received from the Nasdaq Listing Qualifications Department in September 2023. The Reverse Stock Split became effective in February 2024, at which time the Company regained compliance with the minimum bid price requirement.
Common stock shares outstanding due to reverse stock split	5,500,000	65,800,000
Number of shares issued in connection with reverse stock split	0
Warrants to purchase			1,040,820
Warrant exercised				0				0
Class A Warrants
Subsidiary Sale Of Stock [Line Items]
Warrant exercised							255,103
pre-funded warrant
Subsidiary Sale Of Stock [Line Items]
Total proceeds from the issuance of warrants \| $			$ 16.4
pre-funded warrant \| Class A Warrants
Subsidiary Sale Of Stock [Line Items]
Total proceeds from the issuance of warrants \| $			24.6
pre-funded warrant \| Class B Warrants
Subsidiary Sale Of Stock [Line Items]
Total proceeds from the issuance of warrants \| $			$ 1.2
Maximum
Subsidiary Sale Of Stock [Line Items]
Reverse stock split ratio						0.0588
Minimum
Subsidiary Sale Of Stock [Line Items]
Reverse stock split ratio						0.1429
Registered Direct Offering \| Common Stock
Subsidiary Sale Of Stock [Line Items]
Number of shares sold					634,500
Registered Direct Offering \| Common Stock and Warrant
Subsidiary Sale Of Stock [Line Items]
Sale of stock, price per share \| $ / shares					$ 15.46
Gross proceeds from issuance of common stock and warrant \| $					$ 9.8
Net proceeds from issuance of common stock \| $					$ 9.7
Registered Direct Offering \| Maximum \| Warrants to purchase common stock
Subsidiary Sale Of Stock [Line Items]
Number of shares sold					634,500
Private Placement \| Gilead Sciences, Inc.
Subsidiary Sale Of Stock [Line Items]
Warrants to purchase			2,295,920
Gross proceeds from issuance of common stock and warrant \| $			$ 45.0		$ 2.8
Net proceeds from issuance of common stock \| $			$ 42.8		$ 2.7
Private Placement \| Gilead Sciences, Inc. \| Class A Warrants
Subsidiary Sale Of Stock [Line Items]
Warrants to purchase			1,147,960
Private Placement \| Gilead Sciences, Inc. \| Class B Warrants
Subsidiary Sale Of Stock [Line Items]
Warrants to purchase			1,147,960
Private Placement \| Gilead Sciences, Inc. \| Common Stock
Subsidiary Sale Of Stock [Line Items]
Number of shares sold			2,295,920		179,500
Sale of stock, price per share \| $ / shares			$ 19.6
Private Placement \| Gilead Sciences, Inc. \| Common Stock and Warrant
Subsidiary Sale Of Stock [Line Items]
Sale of stock, price per share \| $ / shares					$ 15.46
Private Placement \| Gilead Sciences, Inc. \| Gilead Equity Agreements \| Common Stock
Subsidiary Sale Of Stock [Line Items]
Number of shares sold				940,499
Sale of stock, price per share \| $ / shares				$ 21.37				$ 21.37
Proceeds received from transaction \| $				$ 20.1
Premium on purchase of common stock \| $				5.2
Fair value of common stock purchased \| $				$ 14.9
Number of trading days volume considered for weighted average price to calculate premium				30 days
Private Placement \| Maximum \| Gilead Sciences, Inc. \| Warrants to purchase common stock
Subsidiary Sale Of Stock [Line Items]
Number of shares sold					179,500
Private Placement \| Maximum \| Gilead Sciences, Inc. \| Gilead Equity Agreements \| Common Stock
Subsidiary Sale Of Stock [Line Items]
Percentage of premium to weighted average price immediately prior to date of purchase				35.00%
Underwritten Offering
Subsidiary Sale Of Stock [Line Items]
Warrants to purchase			6,632,660
Gross proceeds from issuance of common stock and warrant \| $			$ 130.0
Net proceeds from issuance of common stock \| $			$ 123.6
Underwritten Offering \| Class A Warrants
Subsidiary Sale Of Stock [Line Items]
Warrants to purchase			3,316,330
Underwritten Offering \| Class B Warrants
Subsidiary Sale Of Stock [Line Items]
Warrants to purchase			3,316,330
Underwritten Offering \| Common Stock
Subsidiary Sale Of Stock [Line Items]
Number of shares sold			5,591,840
Sale of stock, price per share \| $ / shares			$ 19.6
Underwritten Offering \| pre-funded warrant
Subsidiary Sale Of Stock [Line Items]
Sale of stock, price per share \| $ / shares			$ 19.599
Underwritten Offering \| Maximum \| pre-funded warrant
Subsidiary Sale Of Stock [Line Items]
Number of shares sold			1,040,820
2020 At the Market Offerings
Subsidiary Sale Of Stock [Line Items]
Net proceeds from the issuance of common stock through equity plans \| $							$ 1.9
2024 At the Market Offerings
Subsidiary Sale Of Stock [Line Items]
Number of shares sold							161,645	152,666
Net proceeds from the issuance of common stock through equity plans \| $								$ 2.0
2024 At the Market Offerings \| Maximum
Subsidiary Sale Of Stock [Line Items]
Initial public offering value of shares authorized \| $									$ 75.0

Income Taxes - Components of Deferred Taxes (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Deferred tax assets:
Federal and state-operating loss carryforwards	$ 123,615	$ 131,994
Stock-based compensation	7,359	7,078
Capitalized research expense	29,377	35,593
Deferred revenue	9,382	18,484
Operating lease liabilities	668	782
Research and development credits	5,377	18,436
Other	32	53
Total deferred tax assets	175,810	212,420
Valuation allowance	(175,113)	(211,614)
Deferred tax asset, net of valuation allowance	697	806
Deferred tax liabilities:
Operating lease right-of-use assets	(638)	(777)
Other	(59)	(29)
Total deferred tax liabilities	(697)	(806)
Net deferred tax liability	$ 0	$ 0

Collaboration Agreements - Schedule of Collaboration Revenue Recognized with the Period (Details) - Related Party - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Collaboration revenue from a related party recognized in the period from:
Amounts included in deferred revenue at the beginning of the period	$ 36,841	$ 28,271
Performance obligations satisfied in previous period	$ 0	$ 0

Income Taxes - Effective Income Tax Rate Reconciliation (Details) - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2025

Dec. 31, 2024

Amount

Tax computed at federal statutory rate

$ (1,286)

State tax, net of federal income tax effect

^[1]

(118)

Non-taxable or nondeductible items:

Permanent items

Covered employee compensation

121

Share-based payment awards

615

Changes in valuation allowance

(12,986)

Tax credits:

Federal research and development tax credits

17,027

Changes in unrecognized tax benefits

(3,397)

Income tax expense

$ 0

$ 330

Percent

Tax computed at federal statutory rate

21.00%

State tax, net of federal income tax effect

1.90%

^[1]

8.10%

Non-taxable or nondeductible items:

Permanent items

(0.40%)

Covered employee compensation

(2.00%)

Share-based payment awards

(10.00%)

(8.40%)

Other

(0.50%)

Changes in valuation allowance

212.10%

(22.90%)

Tax credits:

Federal research and development tax credits

(278.10%)

8.40%

Return to provision adjustments

(4.80%)

Uncertain tax positions

(1.70%)

Changes in unrecognized tax benefits

55.50%

Effective tax rate

0.00%

(0.80%)

[1]	State taxes in California comprise the majority (greater than 50.0%) of the tax effect in this category.

Stock-Based Compensation - Schedule of Recognized Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Compensation expense:
Stock-based compensation expense	$ 4,677	$ 3,120
Stock options
Compensation expense:
Stock-based compensation expense	2,387	2,511
Employee Stock Purchase Plan
Compensation expense:
Stock-based compensation expense	311	102
RSUs
Compensation expense:
Stock-based compensation expense	427	368
PSUs
Compensation expense:
Stock-based compensation expense	1,552	139
Research and Development
Compensation expense:
Stock-based compensation expense	2,628	1,531
General and Administrative
Compensation expense:
Stock-based compensation expense	$ 2,049	$ 1,589

Stockholders' Equity

12 Months Ended

Dec. 31, 2025

Equity [Abstract]

Stockholders' Equity

Note 6 - Stockholders’ Equity

The Company is authorized to issue 5,000,000 shares of preferred stock as of December 31, 2025 and 2024. As of December 31, 2025 and 2024, no shares of preferred stock were issued and outstanding. The Company is authorized to issue 150,000,000 shares of common stock as of December 31, 2025 and 2024.

Reverse Stock Split

In January 2024, the Company's stockholders approved a reverse stock split of its common stock at a range of ratios between 1-for-7 to 1-for-17, and the Company's board of directors approved the implementation of the reverse stock split at a ratio of 1-for-12 (the Reverse Stock Split). The Reverse Stock Split was undertaken to enable the Company to regain compliance with the minimum bid price requirement for continued listing on the Nasdaq Global Select Market, as referenced in the deficiency notice received from the Nasdaq Listing Qualifications Department in September 2023. The Reverse Stock Split became effective in February 2024, at which time the Company regained compliance with the minimum bid price requirement.

As of the effective time of the Reverse Stock Split, every 12 issued and outstanding shares of the Company’s common stock was automatically reclassified into one issued and outstanding share of the Company’s common stock. This reduced the number of shares outstanding from 65.8 million shares to 5.5 million shares. No fractional shares of common stock were issued in connection with the Reverse Stock Split and all fractional shares were rounded down to the nearest whole share with respect to outstanding shares of common stock. Any holders of common stock who would

have otherwise received a fractional share of common stock pursuant to the Reverse Stock Split, received cash in lieu of the fractional share. The Reverse Stock Split did not affect the par value of the common stock. The Company's authorized shares of common stock remained at 150,000,000 and its authorized shares of preferred stock remained at 5,000,000.

Sale of Common Stock and Warrants

At-The-Market Offering

In November 2024, the Company entered into a sales agreement under which the Company may offer and sell shares of its common stock having an aggregate offering price of up to $75.0 million through "at-the-market" offerings (the ATM), pursuant to its shelf registration statement on Form S-3 (File No. 333-270760), which became effective in April 2023. During the year ended December 31, 2025, the Company issued and sold 161,645 shares of its common stock under the ATM, for which the Company received net proceeds of $1.9 million, after deducting commissions, fees and expenses. During the year ended December 31, 2024, the Company issued and sold 152,666 shares of its common stock under the ATM, for which the Company received net proceeds of $2.0 million, after deducting commissions, fees and expenses.

Registered Direct Offering

In June 2024, the Company issued and sold 634,500 shares of common stock and a warrant to purchase up to 634,500 shares of common stock in a registered direct offering pursuant to its shelf registration statement on Form S-3 on file with the SEC (the June 2024 Registered Direct Offering). The common stock and warrant were sold at a combined offering price of $15.46 per share for aggregate gross proceeds to the Company of $9.8 million. After deducting issuance costs, net proceeds totaled $9.7 million.

Underwritten Offering

In August 2025, the Company issued and sold an aggregate of 5,591,840 shares of common stock and pre-funded warrants to purchase up to 1,040,820 shares of common stock, together with accompanying 3,316,330 Class A and 3,316,330 Class B warrants to purchase up to an aggregated total of 6,632,660 shares of common stock in an underwritten offering (the August 2025 Underwritten Offering). The combined price per share of common stock with the accompanying Class A and Class B warrants was $19.60, while the combined price per pre-funded warrant with accompanying Class A and Class B warrants was $19.599. The offering generated aggregate gross proceeds to the Company of $130.0 million. After deducting issuance costs, net proceeds totaled $123.6 million.

Private Placements

In June 2024, the Company issued and sold 179,500 shares of common stock and a warrant to purchase up to 179,500 shares of common stock under the June 2024 Private Placement with Gilead (as defined in Note 3 - Related Party). This transaction was executed concurrently with the June 2024 Registered Direct Offering pursuant to anti-dilution provisions in the Investor Rights Agreement, with the common stock and warrant sold at the same combined offering price of $15.46 per share for aggregate gross proceeds to the Company of $2.8 million. After deducting issuance costs, net proceeds totaled $2.7 million.

In December 2024, Gilead exercised its right under the Gilead Equity Agreements to purchase an additional 940,499 shares of common stock from the Company at a purchase price of $21.37 per share, which represents a 35% premium to the 30 trading day volume weighted average price immediately prior to the date of purchase. The Company received aggregate proceeds of $20.1 million, of which $5.2 million was determined to be a premium on the purchase of the Company’s common stock and allocated to the single combined performance obligation under the Gilead Collaboration Agreement (see Note 8 - Collaboration Agreements). The fair value of Gilead's common stock purchase was $14.9 million.

In August 2025, the Company entered into the August 2025 Private Placement (as defined in Note 3 - Related Party) with Gilead, which involved the issuance and sale of 2,295,920 shares of common stock and accompanying 1,147,960 Class A and 1,147,960 Class B warrants to purchase up to an aggregate of 2,295,920 shares of common stock in a private placement. This transaction was executed concurrently with the August 2025 Underwritten Offering.

The combined price per share of common stock with the accompanying Class A and Class B warrants was $19.60, generating aggregate gross proceeds of $45.0 million. After deducting issuance costs, net proceeds totaled $42.8 million. These warrants have the same exercise price and terms as the warrants sold in the August 2025 Underwritten Offering.

Warrants

The following warrants and pre-funded warrants to purchase shares of the Company's common stock were issued and outstanding:


					December 31,
Issue Date	Exercisable Date	Expiration Date	Exercise Price per Share		2025		2024
6/16/2024	6/16/2024	6/18/2029	$	17.00		634,500		634,500
6/17/2024	6/17/2024	6/18/2029	$	17.00		179,500		179,500
8/11/2025	8/11/2025	No expiration	$	0.001		1,040,820		—
8/11/2025	8/11/2025	8/11/2030 (1)	$	21.60		4,209,187		—
8/11/2025	11/15/2026 (2)	12/31/2026 (2)	$	21.60		4,464,290		—
						10,528,297		814,000

(1)

These Class A warrants will expire 30 days following the public announcement that the Company completed enrollment (of at least 200 patients total) in the ABI-5366 Phase 2 clinical study if prior to August 11, 2030.

(2)

These Class B warrants will be cancelled if the Company publicly announces the receipt of at least $75.0 million in the aggregate of non-dilutive capital in connection with a collaboration agreement prior to November 15, 2026.

There were 255,103 Class A warrants exercised during December 31, 2025. No warrants were exercised during December 31, 2024.

The Company’s warrants and pre-funded warrants are classified as a component of permanent stockholders’ equity within additional paid-in capital and were recorded at their respective issuance date using a relative fair value allocation method. Of the total proceeds from the issuance of warrants in the August 2025 Underwritten Offering and the August 2025 Private Placement, $16.4 million was allocated to pre-funded warrants, $24.6 million to Class A warrants and $1.2 million to Class B warrants.

The warrants and pre-funded warrants are equity classified because they are freestanding financial instruments that are legally detachable and separately exercisable from the equity instruments, do not embody an obligation for the Company to repurchase its shares, permit the holders to receive a fixed number of common shares upon exercise, are indexed to the Company’s common stock and meet the equity classification criteria. In addition, such warrants and pre-funded warrants do not provide any guarantee of value or return.

Holders of all warrants and pre-funded warrants cannot exercise any portion of the warrants to the extent they would beneficially own more than the limits defined in the warrant agreements. The exercise price and number of shares of the Company's common stock issuable upon the exercise of the warrants are subject to adjustment in the event of any stock dividends and distributions, stock splits, stock combinations or stock reclassifications, as described in the respective warrant agreements. Under certain circumstances, the warrants may be exercised on a “cashless” basis.

- Definition

The entire disclosure for equity.

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+ Details

Document And Entity Information - USD ($) $ in Millions	12 Months Ended
Document And Entity Information - USD ($) $ in Millions	Dec. 31, 2025	Mar. 13, 2026	Jun. 30, 2025
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Transition Report	false
Document Period End Date	Dec. 31, 2025
Entity File Number	001-35005
Entity Registrant Name	ASSEMBLY BIOSCIENCES, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-8729264
Entity Address, Address Line One	Two Tower Place
Entity Address, Address Line Two	7th Floor
Entity Address, City or Town	South San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94080
City Area Code	833
Local Phone Number	509-4583
Amendment Flag	false
Document Fiscal Year Focus	2025
Document Fiscal Period Focus	FY
Entity Central Index Key	0001426800
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Trading Symbol	ASMB
Security Exchange Name	NASDAQ
Title of 12(b) Security	Common Stock, $0.001 Par Value
Entity Common Stock, Shares Outstanding		15,862,705
ICFR Auditor Attestation Flag	false
Entity Shell Company	false
Entity Emerging Growth Company	false
Entity Small Business	true
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Public Float			$ 97.8
Auditor Name	Ernst & Young LLP
Auditor Firm ID	42
Auditor Location	San Jose, California
Auditor Opinion	Opinion on the Financial Statements We have audited the accompanying consolidated balance sheets of Assembly Biosciences, Inc. (the Company) as of December 31, 2025 and 2024, the related consolidated statements of operations and comprehensive loss, changes in stockholders’ equity and cash flows for each of the two years in the period ended December 31, 2025, and the related notes (collectively referred to as the “consolidated financial statements”). In our opinion, the consolidated financial statements present fairly, in all material respects, the financial position of the Company at December 31, 2025 and 2024, and the results of its operations and its cash flows for each of the two years in the period ended December 31, 2025, in conformity with U.S. generally accepted accounting principles.
Documents Incorporated by Reference	Part III of this Annual Report on Form 10-K incorporates information by reference to portions of the definitive proxy statement for the Company’s Annual Meeting of Stockholders to be held in 2026, to be filed within 120 days of the registrant’s fiscal year ended December 31, 2025.
Document Financial Statement Error Correction [Flag]	false

Stock-Based Compensation - Summary of Assumptions Used to Estimate Fair Values of Stock Options Grants (Details) - $ / shares	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Share-based Compensation Arrangement by Share-based Payment Award
Expected dividend yield	0.00%	0.00%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award
Exercise price	$ 10.62	$ 12.9
Expected volatility	81.10%	79.10%
Risk-free rate	3.70%	3.50%
Expected term (years)	5 years 6 months	5 years 6 months
Maximum
Share-based Compensation Arrangement by Share-based Payment Award
Exercise price	$ 24.61	$ 16.75
Expected volatility	86.40%	86.90%
Risk-free rate	4.42%	4.57%
Expected term (years)	7 years	7 years 6 months

- 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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Reference 29: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

HBV Research Agreement with Indiana University

12 Months Ended

Dec. 31, 2025

Research Agreement [Abstract]

HBV Research Agreement with Indiana University

Note 9 – HBV Research Agreement with Indiana University

Since September 2013, the Company was party to an exclusive License Agreement with Indiana University Research and Technology Corporation (IURTC) from whom it licensed aspects of the Company’s HBV program held by IURTC. The license agreement required the Company to make milestone payments based upon the successful accomplishment of clinical and regulatory milestones. The aggregate amount of all performance milestone payments under the IURTC license agreement, if all milestones through development were met, was $0.8 million, with a portion having been paid. The Company was obligated to pay IURTC royalty payments based on net sales of the licensed technology as well as a portion of any sublicensing revenue Assembly received. The Company was also required to pay diligence maintenance fees each year to the extent that the royalty, sublicensing, and milestone payments to IURTC were less than such fees for that year. The Company terminated the IURTC license agreement effective April 2024. The Company paid IURTC $0.1 million in diligence maintenance fees during the year ended December 31, 2024, which were included in research and development expenses in the consolidated statements of operations and comprehensive loss.

Stock-Based Compensation - Summary of Performance Stock Units and Related Information (Details) - PSUs - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding [Roll Forward]
Beginning of period	15,832
Granted	225,000
Ending of period	240,832	15,832
Weighted Average Fair Value Per PSU at Grant Price
Beginning of period	$ 20.88
Granted	17.24
Ending of period	$ 17.48	$ 20.88
Total fair value of awards vested and settled	$ 0	$ 1,029
Total intrinsic value of awards vested and settled	$ 0	$ 488

Segment Reporting

12 Months Ended

Dec. 31, 2025

Segment Reporting [Abstract]

Segment Reporting

Note 13 - Segment Reporting

The Company operates as a single operating segment focusing on developing innovative therapeutics targeting serious viral diseases. The Company's chief operating decision maker (CODM) is its Chief Executive Officer and President, who reviews financial information presented on a consolidated basis for purposes of making operating decisions, assessing financial performance, and allocating resources.

The measure of segment profit or loss used by the CODM to evaluate performance and allocate resources is consolidated net loss as reported in the Company's consolidated statements of operations. This measure is used by the CODM to assess its cash runway and make strategic decisions about resource allocation. The CODM does not use asset measures to evaluate segment performance or make resource allocation decisions.

Operating expenses include all costs necessary to operate the Company's business, primarily consisting of research and development and general and administrative expenses directly related to advancing the Company's programs. These expenses are reviewed by the CODM on a consolidated basis as part of evaluating the Company's overall financial performance. During the years ended December 31, 2025 and 2024, the Company generated all of its collaboration revenue from Gilead, who is a related party (see Notes 3 - Related Party and 8 - Collaboration Agreements). For the years ended December 31, 2025 and 2024, all of the Company's revenue and long-lived assets were in the United States.

The following table presents the significant segment expenses and other segment items regularly reviewed by the Company's CODM:


	Year Ended December 31,
	2025			2024
Collaboration revenue from a related party	$	72,303		$	28,520
Less:
External program expenses:
ABI-5366		9,353			6,215
ABI-1179		8,119			4,239
ABI-6250		5,780			6,396
ABI-4334		890			2,646
ABI-7272 (1)		2,300			—
Research and discovery		8,161			8,985
Vebicorvir		—			(43	)	(2)
Total external program expenses		34,603			28,438
Employee and contractor-related expenses (3)		26,729			23,819
Facility and other expenses		3,481			3,676
Total research and development		64,813			55,933
General and administrative (3)		19,608			18,007
Interest and other income, net		(5,996	)		(5,573	)
Income tax expense		—			330
Net loss	$	(6,122	)	$	(40,177	)

(1)

In October 2025, the Company transitioned its discovery and development from ABI-7423 to its parent molecule, ABI-7272, which is currently in regulatory filing-enabling preclinical studies.

(2)

Reflects net amounts refundable to the Company after the final reconciliation of costs of the clinical trial conducted pursuant to the Arbutus Biopharma Agreement, which was terminated in February 2023.

(3)

Includes stock-based compensation expense, see Note 7 - Stock-Based Compensation for further details.

- 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.

+ References

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-SubTopic 10
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Property and Equipment, Net - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Property, Plant and Equipment
Property and equipment, net	$ 221	$ 284

Stockholders' Equity - Summary of Warrants and Pre-funded Warrants to Purchase Shares of Common Stock Issued and Outstanding (Details) - $ / shares

12 Months Ended

Dec. 31, 2025

Dec. 31, 2024

Aug. 31, 2025

Subsidiary, Sale of Stock [Line Items]

Warrant Exercise Price per Share

$ 0.001

Warrant Issued

10,528,297

814,000

Warrant Outstanding

10,528,297

814,000

June 16 2024 warrants

Subsidiary, Sale of Stock [Line Items]

Warrant Issue Date

Jun. 16, 2024

Warrant Exercisable Date

Jun. 16, 2024

Warrant Expiration Date

Jun. 18, 2029

Warrant Exercise Price per Share

$ 17

Warrant Issued

634,500

Warrant Outstanding

634,500

June 17 2024 warrants

Subsidiary, Sale of Stock [Line Items]

Warrant Issue Date

Jun. 17, 2024

Warrant Exercisable Date

Jun. 17, 2024

Warrant Expiration Date

Jun. 18, 2029

Warrant Exercise Price per Share

$ 17

Warrant Issued

179,500

Warrant Outstanding

179,500

August 11 2025 Warrants

Subsidiary, Sale of Stock [Line Items]

Warrant Issue Date

Aug. 11, 2025

Warrant Exercisable Date

Aug. 11, 2025

Warrant Exercise Price per Share

$ 0.001

Warrant Issued

1,040,820

Warrant Outstanding

1,040,820

August 11 2025 One Warrants

Subsidiary, Sale of Stock [Line Items]

Warrant Issue Date

Aug. 11, 2025

Warrant Exercisable Date

Aug. 11, 2025

Warrant Expiration Date

^[1]

Aug. 11, 2030

Warrant Exercise Price per Share

$ 21.6

Warrant Issued

4,209,187

Warrant Outstanding

4,209,187

August 11 2025 Two Warrants

Subsidiary, Sale of Stock [Line Items]

Warrant Issue Date

Aug. 11, 2025

Warrant Exercisable Date

^[2]

Nov. 15, 2026

Warrant Expiration Date

^[2]

Dec. 31, 2026

Warrant Exercise Price per Share

$ 21.6

Warrant Issued

4,464,290

Warrant Outstanding

4,464,290

[1]	These Class A warrants will expire 30 days following the public announcement that the Company completed enrollment (of at least 200 patients total) in the ABI-5366 Phase 2 clinical study if prior to August 11, 2030.
[2]	These Class B warrants will be cancelled if the Company publicly announces the receipt of at least $75.0 million in the aggregate of non-dilutive capital in connection with a collaboration agreement prior to November 15, 2026.

Income Taxes

12 Months Ended

Dec. 31, 2025

Income Tax Disclosure [Abstract]

Income Taxes

Note 10 - Income Taxes

Income tax expense is as follows (in thousands):


	Year Ended December 31,
	2025		2024
Current:
State	$	—	$	330
Income tax expense	$	—	$	330

The Company adopted ASU 2023-09 prospectively for the year ended December 31, 2025. Prior period disclosures have not been retrospectively adjusted and may not be comparable to the current year presentation under the new standard. The reconciliation between the federal statutory tax rate applied to loss before income taxes and the Company's effective tax rate is summarized as follows (in thousands, except percentages):


	Year Ended December 31,
	2025
	Amount			Percent
Tax computed at federal statutory rate	$	(1,286	)		21.0	%
State tax, net of federal income tax effect (1)		(118	)		1.9	%
Non-taxable or nondeductible items:
Permanent items		24			-0.4	%
Covered employee compensation		121			-2.0	%
Share-based payment awards		615			-10.0	%
Changes in valuation allowance		(12,986	)		212.1	%
Tax credits:
Federal research and development tax credits		17,027			-278.1	%
Changes in unrecognized tax benefits		(3,397	)		55.5	%
Income tax expense / Effective tax rate		—			0.0	%

(1)

State taxes in California comprise the majority (greater than 50.0%) of the tax effect in this category.

The effective tax rate of the Company's provision for income taxes differs from the federal statutory rate as follows:


		Year Ended December 31,
		2024
Statutory federal income tax rate		21.0%
State taxes, net of federal tax benefit		8.1%
Research and development tax credits		8.4%
Return to provision adjustments		-4.8%
Uncertain tax positions		-1.7%
Stock-based compensation		-8.4%
Other		-0.5%
Change in valuation allowance		-22.9%
Income taxes provision (benefit)		-0.8%

Income taxes paid, net of refunds received, were not material during the year ended December 31, 2025. The Company paid $0.4 million of income taxes during the year ended December 31, 2024.

Significant components of the Company’s deferred taxes are as follows (in thousands):


	As of December 31,
	2025			2024
Deferred tax assets:
Federal and state-operating loss carryforwards	$	123,615		$	131,994
Stock-based compensation		7,359			7,078
Capitalized research expense		29,377			35,593
Deferred revenue		9,382			18,484
Operating lease liabilities		668			782
Research and development credits		5,377			18,436
Other		32			53
Total deferred tax assets		175,810			212,420
Valuation allowance		(175,113	)		(211,614	)
Deferred tax asset, net of valuation allowance	$	697		$	806

Deferred tax liabilities:
Operating lease right-of-use assets	$	(638	)	$	(777	)
Other		(59	)		(29	)
Total deferred tax liabilities		(697	)		(806	)
Net deferred tax liability	$	—		$	—

The Company maintains a valuation allowance on deferred tax assets due to the uncertainty regarding the ability to utilize these deferred tax assets in the future. The valuation allowance decreased by $36.5 million for the year ended December 31, 2025, primarily due to a reduction in the Company's research and development credits and federal and state net operating loss carryforwards resulting from an ownership change under Internal Revenue Code (IRC) Sections 382 and 383 (see below). The valuation allowance increased by $9.2 million for the year ended December 31, 2024, primarily due to an increase in the Company’s federal and state net operating loss carryforwards generated during the year.

Net operating loss and tax credit carryforwards as of December 31, 2025 are as follows (in thousands):


	Amount		Expiration Years
Net operating losses, federal (post December 31, 2017)	$	432,835	Indefinite
Net operating losses, federal (pre January 1, 2018)		67,208	2029 - 2037
Net operating loss, state (Indefinite)		880	Indefinite
Net operating loss, state (Definite)		315,530	2029 - 2054
Research and development tax credits, federal		793	2040 - 2045
Research and development tax credits, state		7,521	Indefinite

Pursuant to IRC Sections 382 and 383, use of the Company’s U.S. federal and state net operating loss and research and development income tax credit carryforwards may be limited in the event of a cumulative change in ownership of more than 50% within a three-year period. The Company performed an ownership change study through August 2025 and determined a change in ownership, as defined by IRC Section 382, occurred in December 2010, January 2013, October 2014 and August 2025. As a result, the Company adjusted its federal and California deferred tax assets for net operating loss and research and development carryforwards to reflect attributes which will expire due to the limitation, with a corresponding change to the valuation allowance recorded against such assets. The Company has not completed a similar analysis with respect to its other remaining state net operating loss carryforwards, which totaled $224.1 million as of December 31, 2025, and accordingly, it is possible additional limitations or expirations exist that have not yet been reflected. If further ownership changes occur, additional net operating loss and tax credit carryforwards could be eliminated or restricted. If eliminated, the related deferred tax asset would be removed with a corresponding reduction in the valuation allowance.

The following table summarizes activity related to the Company’s gross unrecognized tax benefits (in thousands):


	As of December 31,
	2025			2024
Balances as of beginning of year	$	5,175		$	4,495
Decreases related to prior year tax positions		(3,687	)		(31	)
Increases related to current year tax positions		317			711
Balances as of end of year	$	1,805		$	5,175

The unrecognized tax benefits, if recognized, would not have an impact on the Company’s effective tax rate assuming the Company continues to maintain a full valuation allowance position. Based on the prior year’s operations and experience, the Company does not expect a significant change to its unrecognized tax benefits over the next twelve months. The unrecognized tax benefits may increase or change during the next year for unexpected or unusual items that arise in the ordinary course of business. In subsequent periods, any interest and penalties related to uncertain tax positions will be recognized as a component of income tax expense. Interest and penalties related to unrecognized tax benefits were not material for the years ended December 31, 2025 and 2024.

The Company files income tax returns in the U.S. federal, California and other state and foreign jurisdictions and is not currently under examination by federal, state, or local taxing authorities for any open tax years. Due to net operating loss carryforwards, all years effectively remain open for income tax examination by tax authorities in the U.S. and states in which the Company files tax returns.

- Definition

The entire disclosure for income tax.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-Subparagraph (SAB Topic 11.C)
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-URI https://asc.fasb.org/1943274/2147479360/740-10-S99-2

Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482603/740-30-50-2

+ Details

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2025

Income Tax Disclosure [Abstract]

Schedule of Income Tax Expense

Income tax expense is as follows (in thousands):


	Year Ended December 31,
	2025		2024
Current:
State	$	—	$	330
Income tax expense	$	—	$	330

Effective Income Tax Rate Reconciliation

The reconciliation between the federal statutory tax rate applied to loss before income taxes and the Company's effective tax rate is summarized as follows (in thousands, except percentages):


	Year Ended December 31,
	2025
	Amount			Percent
Tax computed at federal statutory rate	$	(1,286	)		21.0	%
State tax, net of federal income tax effect (1)		(118	)		1.9	%
Non-taxable or nondeductible items:
Permanent items		24			-0.4	%
Covered employee compensation		121			-2.0	%
Share-based payment awards		615			-10.0	%
Changes in valuation allowance		(12,986	)		212.1	%
Tax credits:
Federal research and development tax credits		17,027			-278.1	%
Changes in unrecognized tax benefits		(3,397	)		55.5	%
Income tax expense / Effective tax rate		—			0.0	%

(1)

State taxes in California comprise the majority (greater than 50.0%) of the tax effect in this category.

The effective tax rate of the Company's provision for income taxes differs from the federal statutory rate as follows:


		Year Ended December 31,
		2024
Statutory federal income tax rate		21.0%
State taxes, net of federal tax benefit		8.1%
Research and development tax credits		8.4%
Return to provision adjustments		-4.8%
Uncertain tax positions		-1.7%
Stock-based compensation		-8.4%
Other		-0.5%
Change in valuation allowance		-22.9%
Income taxes provision (benefit)		-0.8%

Components of Deferred Taxes

Significant components of the Company’s deferred taxes are as follows (in thousands):


	As of December 31,
	2025			2024
Deferred tax assets:
Federal and state-operating loss carryforwards	$	123,615		$	131,994
Stock-based compensation		7,359			7,078
Capitalized research expense		29,377			35,593
Deferred revenue		9,382			18,484
Operating lease liabilities		668			782
Research and development credits		5,377			18,436
Other		32			53
Total deferred tax assets		175,810			212,420
Valuation allowance		(175,113	)		(211,614	)
Deferred tax asset, net of valuation allowance	$	697		$	806

Deferred tax liabilities:
Operating lease right-of-use assets	$	(638	)	$	(777	)
Other		(59	)		(29	)
Total deferred tax liabilities		(697	)		(806	)
Net deferred tax liability	$	—		$	—

Summary of Net Operating Loss and Tax Credit Carryforwards

Net operating loss and tax credit carryforwards as of December 31, 2025 are as follows (in thousands):


	Amount		Expiration Years
Net operating losses, federal (post December 31, 2017)	$	432,835	Indefinite
Net operating losses, federal (pre January 1, 2018)		67,208	2029 - 2037
Net operating loss, state (Indefinite)		880	Indefinite
Net operating loss, state (Definite)		315,530	2029 - 2054
Research and development tax credits, federal		793	2040 - 2045
Research and development tax credits, state		7,521	Indefinite

The following table summarizes activity related to the Company’s gross unrecognized tax benefits (in thousands):


	As of December 31,
	2025			2024
Balances as of beginning of year	$	5,175		$	4,495
Decreases related to prior year tax positions		(3,687	)		(31	)
Increases related to current year tax positions		317			711
Balances as of end of year	$	1,805		$	5,175

Summary of Significant Accounting Policies and Recent Accounting Pronouncements

12 Months Ended

Dec. 31, 2025

Accounting Policies [Abstract]

Summary of Significant Accounting Policies and Recent Accounting Pronouncements

Note 2 - Summary of Significant Accounting Policies and Recent Accounting Pronouncements

Basis of Presentation

Use of Estimates

Other Risks and Uncertainties

Cash and Cash Equivalents

Investments in Marketable Securities

Leases

Impairment of Long-Lived Assets

Fair Value Measurements

Level 1: Observable inputs such as unadjusted quoted prices in active markets for identical instruments.

Level 2: Quoted prices for similar instruments that are directly or indirectly observable in the marketplace.

Revenue Recognition and Accounts Receivable from Collaboration

Licenses

Research and Development Services

Customer Options

Development and Regulatory Milestone Payments

Sales-based Milestone and Royalty Payments

At December 31, 2025, all accounts receivable from collaboration with a related party are deemed collectible. There were no accounts receivable from collaboration as of December 31, 2024.

Warrants and Pre-Funded Warrants

Stock-Based Compensation

Research and Development Expense and Accruals

Income Taxes

Net Loss per Share

A reconciliation of the numerators and the denominators of the basic and diluted net loss per common share computations is as follows (in thousands, except for share and per share amounts):


	Year Ended December 31,
	2025			2024
Numerator:
Net loss	$	(6,122	)	$	(40,177	)
Denominator:
Weighted average common shares outstanding - basic and diluted		11,210,934			6,004,560
Net loss per share - basic and diluted	$	(0.55	)	$	(6.69	)

Securities excluded from the computation of diluted net loss per share because including them would have been antidilutive are as follows:


	December 31,
	2025		2024
Warrants to purchase common stock		9,487,477		814,000
Options to purchase common stock		1,193,442		942,193
Common stock subject to purchase under ESPP		6,093		9,386
Unvested RSUs		85,583		52,222
Unvested PSUs		240,832		15,832
Total		11,013,427		1,833,633

Comprehensive Loss

Concentrations of Risk

Credit Risk

Supplier Risk

Customer Risk

Recently Adopted Accounting Standards

Accounting Pronouncements to Be Adopted

Employee Benefit Plan - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Retirement Benefits [Abstract]
Defined Contribution Plan, Employer Discretionary Contribution Amount	$ 0.8	$ 0.7

Collaboration Agreements - Schedule of Changes in Contract Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue recognized	$ (72,303)	$ (28,520)
Less: current portion	(36,904)	(37,622)
Deferred revenue from a related party - long-term	0	35,378
Related Party
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Deferred revenue balance at beginning of period	73,000	86,294
Cash received	35,233	10,000
Accounts receivable from collaboration with a related party	974	0
Premium on purchase of the Company's common stock	0	5,226
Revenue recognized	(72,303)	(28,520)
Deferred revenue balance at end of period	36,904	73,000
Less: current portion	(36,904)	(37,622)
Deferred revenue from a related party - long-term	$ 0	$ 35,378

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 220
-SubTopic 40
-Name Accounting Standards Codification
-Section 55
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147476153/220-40-55-4

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 220
-SubTopic 40
-Name Accounting Standards Codification
-Section 55
-Paragraph 14
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147476153/220-40-55-14

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 41
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-41

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 42
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-42

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-7

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-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 7: http://www.xbrl.org/2003/role/disclosureRef
-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 8: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-32

Reference 9: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-32

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 924
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 11.L)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479941/924-10-S99-1

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-5

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 30
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-30

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-22

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 40
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-40

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-22

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-4

+ Details

Segment Reporting - Schedule of Segment Expenses and Other Segment Items (Details) - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2025

Dec. 31, 2024

Segment Reporting Information [Line Items]

Collaboration revenue from a related party

$ 72,303

$ 28,520

Less:

Total external program expenses

34,603

28,438

Employee and contractor-related expenses

^[1]

26,729

23,819

Facility and other expenses

3,481

3,676

Total research and development

64,813

55,933

General and administrative

^[1]

19,608

18,007

Interest and other income, net

(5,996)

(5,573)

Income tax expense

330

Net loss

(6,122)

(40,177)

ABI-5366

Less:

Total external program expenses

9,353

6,215

ABI-1179

Less:

Total external program expenses

8,119

4,239

ABI-6250

Less:

Total external program expenses

5,780

6,396

ABI-4334

Less:

Total external program expenses

890

2,646

ABI-7272

Less:

Total external program expenses

^[2]

2,300

Research And Discovery

Less:

Total external program expenses

8,161

8,985

Vebicorvir

Less:

Total external program expenses

$ (0)

$ (43)

^[3]

[1]	Includes stock-based compensation expense, see Note 7 - Stock-Based Compensation for further details.
[2]	In October 2025, the Company transitioned its discovery and development from ABI-7423 to its parent molecule, ABI-7272, which is currently in regulatory filing-enabling preclinical studies.
[3]	Reflects net amounts refundable to the Company after the final reconciliation of costs of the clinical trial conducted pursuant to the Arbutus Biopharma Agreement, which was terminated in February 2023.

Collaboration Agreements - Additional Information (Details) $ in Thousands	1 Months Ended			12 Months Ended
	Dec. 31, 2025 USD ($)	Jul. 31, 2025 USD ($)	Oct. 31, 2023 USD ($) Timepoint Program	Dec. 31, 2025 USD ($)	Dec. 31, 2024 USD ($)
Research And Development Arrangement Contract To Perform For Others [Line Items]
Future collaboration-related payments received					$ 10,000
Collaboration revenue from a related party				$ 72,303	28,520
Research and development expense				64,813	55,933
Option, License and Collaboration Agreement \| Gilead Sciences, Inc.
Research And Development Arrangement Contract To Perform For Others [Line Items]
Proceeds received in collaboration agreement			$ 100,000
Collaboration term			12 years
Number of timepoints of program \| Timepoint			2
Non-refundable payment received					10,000
Percentage cover of research and development costs			40.00%
Percentage share of profits and operating loss for products			40.00%
Percentage share of costs and profits			40.00%
Number of fellow-contributed programs \| Program			2
Contract liability/deferred revenue	$ 54,400			54,400
Variable consideration for reimbursable costs	1,500			1,500
Initial non-cancellable term			3 years
Collaboration revenue from a related party				37,300	28,500
Reimbursable expenses				100	300
Option, License and Collaboration Agreement \| Gilead Sciences, Inc. \| Common Stock
Research And Development Arrangement Contract To Perform For Others [Line Items]
Proceeds received in collaboration agreement					20,100
Premium on common stock received					5,200
Option, License and Collaboration Agreement \| Minimum \| Gilead Sciences, Inc.
Research And Development Arrangement Contract To Perform For Others [Line Items]
Threshold payment of opt-in fee			$ 45,000
Option, License and Collaboration Agreement \| Maximum \| Gilead Sciences, Inc.
Research And Development Arrangement Contract To Perform For Others [Line Items]
Threshold payment of opt-in fee			125,000
Reimburse agreed amount		$ 1,500
Option, License and Collaboration Agreement \| Regulatory and Commercial Milestones \| Maximum \| Gilead Sciences, Inc.
Research And Development Arrangement Contract To Perform For Others [Line Items]
Potential milestone payments			330,000
Seventh Year of Collaboration Agreement \| Gilead Sciences, Inc.
Research And Development Arrangement Contract To Perform For Others [Line Items]
Potential proceeds from collaboration extension fees			$ 75,000
HPI Program License \| Gilead Sciences, Inc.
Research And Development Arrangement Contract To Perform For Others [Line Items]
Proceeds received in collaboration agreement	$ 35,000
Percentage share of costs and profits	40.00%
Collaboration revenue from a related party				$ 35,000
Proceeds from option fee	$ 45,000
Payment of opt-in fee	35,000
HPI Program License \| Regulatory and Commercial Milestones \| Maximum \| Gilead Sciences, Inc.
Research And Development Arrangement Contract To Perform For Others [Line Items]
Potential milestone payments	$ 330,000
Arbutus Biopharma Agreement
Research And Development Arrangement Contract To Perform For Others [Line Items]
Research and development expense					$ 300

HBV Research Agreement with Indiana University - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2025
Research Agreement [Abstract]
Potential milestone payment		$ 0.8
Milestone payment, diligence maintenance fees	$ 0.1

CONSOLIDATED BALANCE SHEETS - USD ($)	Dec. 31, 2025	Dec. 31, 2024
Current assets
Cash and cash equivalents	$ 58,450,000	$ 38,344,000
Marketable securities	189,656,000	73,735,000
Accounts receivable from collaboration with a related party	974,000	0
Prepaid expenses and other current assets	5,469,000	3,424,000
Total current assets	254,549,000	115,503,000
Property and equipment, net	221,000	284,000
Operating lease right-of-use (ROU) assets	2,508,000	3,069,000
Other assets	312,000	312,000
Total assets	257,590,000	119,168,000
Current liabilities
Accounts payable	1,171,000	585,000
Accrued research and development expenses	2,387,000	2,273,000
Other accrued expenses	7,749,000	6,862,000
Deferred revenue from a related party - short-term	36,904,000	37,622,000
Operating lease liabilities - short-term	569,000	461,000
Total current liabilities	48,780,000	47,803,000
Deferred revenue from a related party - long-term	0	35,378,000
Operating lease liabilities - long-term	2,059,000	2,628,000
Total liabilities	50,839,000	85,809,000
Commitments and contingencies
Stockholders' equity
Preferred stock, $0.001 par value; 5,000,000 shares authorized; no shares issued or outstanding
Common stock, $0.001 par value; 150,000,000 shares authorized as of December 31, 2025 and December 31, 2024; 15,855,329 and 7,457,240 shares issued and outstanding as of December 31, 2025 and December 31, 2024, respectively	16,000	7,000
Additional paid-in capital	1,038,823,000	859,488,000
Accumulated other comprehensive loss	(41,000)	(211,000)
Accumulated deficit	(832,047,000)	(825,925,000)
Total stockholders' equity	206,751,000	33,359,000
Total liabilities and stockholders' equity	$ 257,590,000	$ 119,168,000

Income Taxes - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Operating Loss Carryforwards [Line Items]
Income taxes paid, net of (refunds received)		$ 0.4
Increase (decrease) in valuation allowance	$ (36.5)	$ 9.2
State
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$ 224.1

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2025

Dec. 31, 2024

Collaboration revenue from a related party

$ 72,303

$ 28,520

Operating expenses

Research and development

64,813

55,933

General and administrative

^[1]

19,608

18,007

Total operating expenses

84,421

73,940

Loss from operations

(12,118)

(45,420)

Other income

Interest and other income, net

5,996

5,573

Total other income

5,996

5,573

Loss before income taxes

(6,122)

(39,847)

Income tax expense

330

Net loss

(6,122)

(40,177)

Other comprehensive loss

Unrealized gain (loss) on marketable securities

170

(130)

Comprehensive loss

$ (5,952)

$ (40,307)

Net loss per share - basic

$ (0.55)

$ (6.69)

Net loss per share - diluted

$ (0.55)

$ (6.69)

Weighted average common shares outstanding, basic

11,210,934

6,004,560

Weighted average common shares outstanding, diluted

11,210,934

6,004,560

[1]	Includes stock-based compensation expense, see Note 7 - Stock-Based Compensation for further details.

Other Accrued Expenses

12 Months Ended

Dec. 31, 2025

Payables and Accruals [Abstract]

Other Accrued Expenses

Note 5 – Other Accrued Expenses

Other accrued expenses consist of the following (in thousands):


	December 31,
	2025		2024
Accrued expenses:
Accrued compensation	$	7,523	$	6,478
Accrued professional fees and other		226		384
Total accrued expenses	$	7,749	$	6,862

Related Party

12 Months Ended

Dec. 31, 2025

Related Party

Note 3 - Related Party

In October 2023, the Company entered into the Option, License and Collaboration Agreement (Gilead Collaboration Agreement), and a Common Stock Purchase Agreement and an Investor Rights Agreement (collectively, the Gilead Equity Agreements) with Gilead. Following the Company entering into the Gilead Equity Agreements, and as of December 31, 2025, Gilead is considered a related party based on its ownership of the Company's common stock.

Gilead Equity Agreements

In June 2024, the Company entered into a Securities Purchase Agreement with Gilead for the issuance and sale of 179,500 shares of common stock and a warrant to purchase up to 179,500 shares of common stock in a private

placement (the June 2024 Private Placement). This transaction, which generated aggregate gross proceeds of $2.8 million, was executed concurrently with the June 2024 Registered Direct Offering (as defined below). See Note 6 - Stockholders' Equity for additional details. Also in June 2024, the Gilead Equity Agreements were amended. The amendments did not have an impact on the Company’s consolidated financial statements.

In December 2024, Gilead exercised its right under the Gilead Equity Agreements to purchase additional shares of common stock from the Company at a purchase price of $21.37 per share, for aggregate proceeds of $20.1 million, resulting in Gilead owning 29.9% of the Company's then-outstanding voting common stock.

In August 2025, the Company entered into a Securities Purchase Agreement with Gilead for the issuance and sale of 2,295,920 shares of common stock and accompanying Class A and Class B warrants to purchase up to an aggregate of 2,295,920 shares of common stock in a private placement (collectively, the August 2025 Private Placement). This transaction, which generated aggregate gross proceeds of $45.0 million, was executed concurrently with the August 2025 Underwritten Offering (as defined below). See Note 6 - Stockholders' Equity for additional details.

Gilead Collaboration Agreement

In July 2025, the Company entered into a letter agreement with Gilead under which Gilead has agreed to reimburse the Company up to $1.5 million for certain nonclinical study activities, subject to the terms and conditions set forth in the agreement. The letter agreement does not amend any terms of the Gilead Collaboration Agreement.

In December 2025, Gilead exercised its combined option to obtain an exclusive license to the Company's HPI program, including 5366 and 1179. Upon exercise of the option, the Company received an opt-in payment of $35.0 million.

As of December 31, 2025, the Company recorded $1.0 million in accounts receivable from collaboration on the consolidated balance sheet for reimbursable costs incurred under the Gilead Collaboration Agreement.

The Company recognized $72.3 million and $28.5 million of collaboration revenue under the Gilead Collaboration Agreement during the years ended December 31, 2025 and 2024, respectively. See Note 8 - Collaboration Agreement for additional details.

- Definition

The entire disclosure for related party transactions. Examples of related party transactions include transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners; and (d) affiliates.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483326/850-10-50-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480990/946-20-50-2

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480990/946-20-50-5

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480990/946-20-50-6

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477968/946-235-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477968/946-235-50-2

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(g)(3))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(c))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(e))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org/850/tableOfContent

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483326/850-10-50-6

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483326/850-10-50-1

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483326/850-10-50-1

+ Details

Employee Benefit Plan

12 Months Ended

Dec. 31, 2025

Retirement Benefits [Abstract]

Employee Benefit Plan

Note 12 - Employee Benefit Plan

In January 2018, the Company established a defined contribution 401(k) plan (the Plan) for all employees who are at least 21 years of age. Employees are eligible to participate in the Plan upon commencement of employment. Under the terms of the Plan, employees may make voluntary contributions as a percentage of compensation. The Plan also permits the Company to make discretionary matching contributions. The Company made discretionary matching contributions of $0.8 million and $0.7 million for the Plan during the years ended December 31, 2025 and 2024, respectively.

Income Taxes - Activity Related to Gross Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Income Tax Disclosure [Abstract]
Balances as of beginning of year	$ 5,175	$ 4,495
Decreases related to prior year tax positions	(3,687)	(31)
Increases related to current year tax positions	317	711
Balances as of end of year	$ 1,805	$ 5,175

Related Party - Additional Information (Details) $ / shares in Units, $ in Thousands	1 Months Ended					12 Months Ended
	Dec. 31, 2025 USD ($)	Aug. 31, 2025 USD ($) shares	Jul. 31, 2025 USD ($)	Dec. 31, 2024 USD ($) $ / shares	Jun. 30, 2024 USD ($) shares	Dec. 31, 2025 USD ($)	Dec. 31, 2024 USD ($) $ / shares
Related Party Transaction [Line Items]
OptInPaymentReceivedUponExerciseOfOption	$ 35,000
Revenue recognized						$ 72,303	$ 28,520
Option, License and Collaboration Agreement
Related Party Transaction [Line Items]
Accounts receivable from collaboration						1,000
Gilead Sciences, Inc. \| Common Stock \| Securities Purchase Agreement \| Private Placement
Related Party Transaction [Line Items]
Number of shares sold \| shares		2,295,920			179,500
Gilead Sciences, Inc. \| Warrants to purchase common stock \| Securities Purchase Agreement \| Maximum \| Private Placement
Related Party Transaction [Line Items]
Number of shares sold \| shares		2,295,920			179,500
Gilead Sciences, Inc. \| Common Stock and Warrant \| Securities Purchase Agreement \| Private Placement
Related Party Transaction [Line Items]
Gross proceeds from issuance of common stock and warrant		$ 45,000			$ 2,800
Gilead Sciences, Inc. \| Gilead Equity Agreements \| Common Stock
Related Party Transaction [Line Items]
Gross proceeds from issuance of common stock and warrant				$ 20,100
Purchase price per share of additional shares description				In December 2024, Gilead exercised its right under the Gilead Equity Agreements to purchase additional shares of common stock from the Company at a purchase price of $21.37 per share, for aggregate proceeds of $20.1 million, resulting in Gilead owning 29.9% of the Company's then-outstanding voting common stock.
Purchase price per share \| $ / shares				$ 21.37			$ 21.37
Percentage of outstanding voting of common stock held				0.299			0.299
Gilead Sciences, Inc. \| Option, License and Collaboration Agreement
Related Party Transaction [Line Items]
Non-refundable payment received				$ 10,000
Revenue recognized						$ 72,300	$ 28,500
Gilead Sciences, Inc. \| Option, License and Collaboration Agreement \| Maximum
Related Party Transaction [Line Items]
Reimburse agreed amount			$ 1,500

Nature of Business - Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2025 USD ($) Segment Product
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Operating segments (in segments) \| Segment	1
FDA approved products (in products) \| Product	0
Cash, cash equivalents and marketable securities \| $	$ 248.1

Income Taxes - Summary of Net Operating Loss and Tax Credit Carryforwards (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Income Taxes [Line Items]
Research and development credits	$ 5,377	$ 18,436
Federal
Income Taxes [Line Items]
Net operating losses	432,835
Net operating losses	67,208
Research and development credits	$ 793
Federal \| Minimum
Income Taxes [Line Items]
Expiration Years	2029
Federal \| Minimum \| Research Tax Credit Carryforward
Income Taxes [Line Items]
Expiration Years	2040
Federal \| Maximum
Income Taxes [Line Items]
Expiration Years	2037
Federal \| Maximum \| Research Tax Credit Carryforward
Income Taxes [Line Items]
Expiration Years	2045
State
Income Taxes [Line Items]
Net operating losses	$ 880
Net operating losses	315,530
Research and development credits	$ 7,521
State \| Minimum
Income Taxes [Line Items]
Expiration Years	2029
State \| Maximum
Income Taxes [Line Items]
Expiration Years	2054

Nature of Business

12 Months Ended

Dec. 31, 2025

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Nature of Business

Note 1 - Nature of Business

Overview

Assembly Biosciences, Inc. (together with its subsidiaries, Assembly or the Company), incorporated in Delaware in October 2005, is a biotechnology company developing innovative therapeutics targeting serious viral diseases with the potential to improve the lives of patients worldwide. The Company's pipeline includes multiple clinical-stage investigational therapies, including: (1) two long-acting helicase-primase inhibitors (HPI) for the treatment of recurrent genital herpes; (2) an orally bioavailable hepatitis delta virus entry inhibitor; and (3) a highly potent next-generation capsid assembly modulator designed to disrupt the replication cycle of hepatitis B virus (HBV) at several key points. The Company's pipeline also includes a novel, oral broad-spectrum non-nucleoside polymerase inhibitor (NNPI) for the treatment of transplant-related herpesviruses, which is currently undergoing studies to enable a regulatory filing, and it has additional research programs against multiple antiviral targets. In December 2025, pursuant to the collaboration with Gilead Sciences, Inc. (Gilead), Gilead exercised its option to license the Company's HPI program, including its long-acting investigational candidates ABI-1179 (1179) and ABI-5366 (5366). For additional information see Note 8 - Collaboration Agreements. The Company operates in one segment and is headquartered in South San Francisco, California (see Note 13 - Segment Reporting).

Liquidity

The Company has not derived any revenue from product sales to date and currently has no approved products. Once a product has been developed, it will need to be approved for sale by the U.S. Food and Drug Administration (FDA) or an applicable foreign regulatory agency. Since the Company’s initial public offering, its operations have been financed through the sale of equity securities and payments related to collaboration agreements. The Company has incurred losses from operations since inception and expects to continue to incur substantial losses for the next several years as it continues its product development efforts. The Company intends to obtain any additional funding it requires through strategic relationships, public or private equity or debt financings, grants or other arrangements. The Company cannot assure such funding will be available on reasonable terms, if at all. As of December 31, 2025, the Company held cash, cash equivalents and marketable securities of $248.1 million. Management believes the Company currently has sufficient funds to meet its operating requirements beyond one year from the date these consolidated financial statements are issued.

Cybersecurity Risk Management, Strategy, and Governance	12 Months Ended
Cybersecurity Risk Management, Strategy, and Governance	Dec. 31, 2025
Cybersecurity Risk Management, Strategy, and Governance [Line Items]
Cybersecurity Risk Management Processes for Assessing, Identifying, and Managing Threats [Text Block]	Item 1C. Cybersecurity Risk Management and Strategy We recognize the critical importance of developing, implementing, and maintaining robust cybersecurity measures to help maintain the security, confidentiality, integrity, and availability of our business systems and confidential information, including personal information and intellectual property. Our cybersecurity program includes systems and processes that are designed to assess, identify and manage material risks from cybersecurity threats and includes: maintenance and monitoring of information security policies aligned with global regulatory controls; user and employee awareness of cyber policies and practices; simulated phishing exercises; information systems configuration management; identity and information asset protection; infrastructure security systems; and cyber threat operations with regular monitoring and threat hunting, including system penetration tests through a third-party service provider. This program includes processes to oversee and identify material risks from cybersecurity threats associated with our use of third-party service providers. We also maintain a cyber incident response plan designed to assist us in identifying, responding to and recovering from cybersecurity incidents. We use the findings from these and other processes to help us improve our information security practices, procedures and technologies. We also collaborate with third parties to assess the effectiveness of our cybersecurity program. These include cybersecurity assessors, consultants, and other external cybersecurity experts to assist in the identification, verification, and validation of material risks from cybersecurity threats, as well as to support associated mitigation plans when necessary. Cybersecurity is integrated into our overall risk management systems, including our annual enterprise risk management, internal controls, business continuity and crisis management, third-party risk management, insurance risk management, and employee compliance processes. Our Cyber Incident Response Team, comprised of our Vice President, General Counsel and Corporate Secretary, our Vice President, Finance, and our Executive Director, Information Technology, consults with, or provides input to each of these programs to ensure that material risks from cybersecurity threats are appropriately assessed, identified, and managed. As of the date of this report, there have been no cybersecurity threats, including as a result of any previous cybersecurity incidents, that have materially affected or are reasonably likely to materially affect us, including our business, strategy, results of operations, or financial condition. For additional description of cybersecurity risks and potential related impacts on the Company, refer to the risk factor captioned “Significant disruptions of information technology systems or breaches of data security, including cybersecurity incidents, could materially and adversely affect our business, results of operations and financial condition” in “Item 1A. Risk Factors.” Governance While our board of directors has oversight responsibility for risk management generally, the Audit Committee is specifically responsible for overseeing our cybersecurity risk management program to ensure cybersecurity risks are identified, assessed, managed, and monitored. Our Executive Director, Information Technology, who has over 15 years of experience in the cybersecurity field and regularly attends cybersecurity conferences and actively implements new technologies to keep our systems up to date and secure, provides periodic updates to the Audit Committee in this regard, and details our cybersecurity program supported by key performance indicators across the range of cybersecurity functions related to risk management and governance, identity and information asset protection, core security and endpoint security, and cyber threat operations. These updates include descriptions of cybersecurity incidents, including those associated with our third-party service providers. The Audit Committee is responsible for updating our full board of directors on material risks from cybersecurity incidents or threats.
Cybersecurity Risk Management Processes Integrated [Flag]	true
Cybersecurity Risk Management Processes Integrated [Text Block]	Cybersecurity is integrated into our overall risk management systems, including our annual enterprise risk management, internal controls, business continuity and crisis management, third-party risk management, insurance risk management, and employee compliance processes.
Cybersecurity Risk Management Third Party Engaged [Flag]	true
Cybersecurity Risk Third Party Oversight and Identification Processes [Flag]	true
Cybersecurity Risk Materially Affected or Reasonably Likely to Materially Affect Registrant [Flag]	false
Cybersecurity Risk Board of Directors Oversight [Text Block]	While our board of directors has oversight responsibility for risk management generally, the Audit Committee is specifically responsible for overseeing our cybersecurity risk management program to ensure cybersecurity risks are identified, assessed, managed, and monitored. Our Executive Director, Information Technology, who has over 15 years of experience in the cybersecurity field and regularly attends cybersecurity conferences and actively implements new technologies to keep our systems up to date and secure, provides periodic updates to the Audit Committee in this regard, and details our cybersecurity program supported by key performance indicators across the range of cybersecurity functions related to risk management and governance, identity and information asset protection, core security and endpoint security, and cyber threat operations. These updates include descriptions of cybersecurity incidents, including those associated with our third-party service providers. The Audit Committee is responsible for updating our full board of directors on material risks from cybersecurity incidents or threats.
Cybersecurity Risk Board Committee or Subcommittee Responsible for Oversight [Text Block]	While our board of directors has oversight responsibility for risk management generally, the Audit Committee is specifically responsible for overseeing our cybersecurity risk management program to ensure cybersecurity risks are identified, assessed, managed, and monitored.
Cybersecurity Risk Process for Informing Board Committee or Subcommittee Responsible for Oversight [Text Block]	Our Executive Director, Information Technology, who has over 15 years of experience in the cybersecurity field and regularly attends cybersecurity conferences and actively implements new technologies to keep our systems up to date and secure, provides periodic updates to the Audit Committee in this regard, and details our cybersecurity program supported by key performance indicators across the range of cybersecurity functions related to risk management and governance, identity and information asset protection, core security and endpoint security, and cyber threat operations. These updates include descriptions of cybersecurity incidents, including those associated with our third-party service providers. The Audit Committee is responsible for updating our full board of directors on material risks from cybersecurity incidents or threats.
Cybersecurity Risk Role of Management [Text Block]	Our Cyber Incident Response Team, comprised of our Vice President, General Counsel and Corporate Secretary, our Vice President, Finance, and our Executive Director, Information Technology, consults with, or provides input to each of these programs to ensure that material risks from cybersecurity threats are appropriately assessed, identified, and managed.
Cybersecurity Risk Management Positions or Committees Responsible [Flag]	true
Cybersecurity Risk Management Positions or Committees Responsible [Text Block]	Our Cyber Incident Response Team, comprised of our Vice President, General Counsel and Corporate Secretary, our Vice President, Finance, and our Executive Director, Information Technology, consults with, or provides input to each of these programs to ensure that material risks from cybersecurity threats
Cybersecurity Risk Management Expertise of Management Responsible [Text Block]	Our Executive Director, Information Technology, who has over 15 years of experience in the cybersecurity field and regularly attends cybersecurity conferences and actively implements new technologies to keep our systems up to date and secure, provides periodic updates to the Audit Committee in this regard
Cybersecurity Risk Process for Informing Management or Committees Responsible [Text Block]	The Audit Committee is responsible for updating our full board of directors on material risks from cybersecurity incidents or threats.
Cybersecurity Risk Management Positions or Committees Responsible Report to Board [Flag]	true

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Cash flows from operating activities
Net loss	$ (6,122)	$ (40,177)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	129	129
Stock-based compensation	4,677	3,120
Net accretion of investments in marketable debt securities	(2,346)	(3,658)
Non-cash rent expense	851	1,417
Realized gain on investments in marketable debt securities	(3)	0
Changes in operating assets and liabilities:
Accounts receivable from collaboration	(974)	43
Prepaid expenses and other current assets	(2,045)	73
Accounts payable	586	124
Accrued research and development expenses	114	1,388
Other accrued expenses	887	1,118
Deferred revenue from a related party	(36,096)	(13,294)
Operating lease liabilities	(751)	(1,400)
Net cash used in operating activities	(41,093)	(51,117)
Cash flows from investing activities
Proceeds from maturities of marketable securities	116,432	130,700
Purchases of marketable securities	(229,834)	(90,501)
Purchases of property and equipment	(66)	(28)
Net cash (used in) provided by investing activities	(113,468)	40,171
Cash flows from financing activities
Proceeds from the issuance of common stock, pre-funded warrants and warrants in an underwritten offering, net of issuance costs	123,600	0
Proceeds from the issuance of common stock and warrants in private placements to a related party, net of issuance costs	42,785	17,602
Proceeds from the exercise of warrants	5,510	0
Proceeds from the issuance of common stock under ATM equity offering program, net of issuance costs	1,922	2,030
Proceeds from the issuance of common stock under ESPP	725	150
Proceeds from the exercise of stock options	125	5
Proceeds from the issuance of common stock and warrants in a registered direct offering, net of issuance costs	0	9,662
Net cash provided by financing activities	174,667	29,449
Net increase in cash and cash equivalents	20,106	18,503
Cash and cash equivalents at the beginning of the year	38,344	19,841
Cash and cash equivalents at the end of the year	58,450	38,344
Supplemental non-cash investing and financing activities
Operating lease liabilities arising from obtaining ROU assets	$ 0	$ 1,966

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2025	Dec. 31, 2024
Statement of Financial Position [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares issued	15,855,329	7,457,240
Common stock, shares outstanding	15,855,329	7,457,240

Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2025

Equity [Abstract]

Summary of Warrants and Pre-funded Warrants to Purchase Shares of Common Stock Issued and Outstanding

The following warrants and pre-funded warrants to purchase shares of the Company's common stock were issued and outstanding:


					December 31,
Issue Date	Exercisable Date	Expiration Date	Exercise Price per Share		2025		2024
6/16/2024	6/16/2024	6/18/2029	$	17.00		634,500		634,500
6/17/2024	6/17/2024	6/18/2029	$	17.00		179,500		179,500
8/11/2025	8/11/2025	No expiration	$	0.001		1,040,820		—
8/11/2025	8/11/2025	8/11/2030 (1)	$	21.60		4,209,187		—
8/11/2025	11/15/2026 (2)	12/31/2026 (2)	$	21.60		4,464,290		—
						10,528,297		814,000

(1)

(2)

Investments in Marketable Securities (Tables)

12 Months Ended

Dec. 31, 2025

Investments, Debt and Equity Securities [Abstract]

Schedule of Investments in Marketable Available-for-Sale Securities

Investments in marketable available-for-sale securities consisted of the following (in thousands):


	December 31, 2025
	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss		Fair Value
Cash equivalents
Money market fund	$	57,994	$	—	$	—	$	57,994
Total cash equivalents		57,994		—		—		57,994
Short-term marketable securities
Corporate debt securities		37,329		34		—		37,363
Asset-backed securities		11,970		19		—		11,989
U.S. treasury securities		123,267		170		—		123,437
Commercial paper		16,858		9		—		16,867
Total short-term marketable securities		189,424		232		—		189,656
Total cash equivalents and marketable securities	$	247,418	$	232	$	—	$	247,650


	December 31, 2024
	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss			Fair Value
Cash equivalents
Money market fund	$	29,066	$	—	$	—		$	29,066
U.S. treasury securities		8,437		—		—			8,437
Total cash equivalents		37,503		—		—			37,503
Short-term marketable securities
Corporate debt securities		20,971		20		(3	)		20,988
U.S. treasury securities		48,077		40		—			48,117
Commercial paper		4,625		5		—			4,630
Total short-term marketable securities		73,673		65		(3	)		73,735
Total cash equivalents and marketable securities	$	111,176	$	65	$	(3	)	$	111,238

Schedule of Fair Value of Financial Assets

The following tables presents the Company’s financial assets measured at fair value on a recurring basis by level within the fair value hierarchy (in thousands):


	December 31, 2025
	Level 1		Level 2		Level 3		Fair Value
Cash equivalents
Money market fund	$	57,994	$	—	$	—	$	57,994
Total cash equivalents		57,994		—		—		57,994
Short-term marketable securities
Corporate debt securities		—		37,363		—		37,363
Asset-backed securities		—		11,989		—		11,989
U.S. treasury securities		—		123,437		—		123,437
Commercial paper		—		16,867		—		16,867
Total short-term marketable securities		—		189,656		—		189,656
Total assets measured at fair value	$	57,994	$	189,656	$	—	$	247,650


	December 31, 2024
	Level 1		Level 2		Level 3		Fair Value
Cash equivalents
Money market fund	$	29,066	$	—	$	—	$	29,066
U.S. treasury securities		—		8,437		—		8,437
Total cash equivalents		29,066		8,437		—		37,503
Short-term marketable securities
Corporate debt securities		—		20,988		—		20,988
U.S. treasury securities		—		48,117		—		48,117
Commercial paper		—		4,630		—		4,630
Total short-term marketable securities		—		73,735		—		73,735
Total assets measured at fair value	$	29,066	$	82,172	$	—	$	111,238

Collaboration Agreements

12 Months Ended

Dec. 31, 2025

Collaboration Agreement [Abstract]

Collaboration Agreements

Note 8 - Collaboration Agreements

The following table presents changes in the Company’s contract liabilities under the Gilead Agreements (in thousands):


	Year Ended December 31,
Contract liabilities:	2025			2024
Deferred revenue balance at beginning of period	$	73,000		$	86,294
Cash received		35,233			10,000
Accounts receivable from collaboration with a related party		974			—
Premium on purchase of the Company's common stock		—			5,226
Revenue recognized		(72,303	)		(28,520	)
Deferred revenue balance at end of period	$	36,904		$	73,000
Less: current portion	$	(36,904	)	$	(37,622	)
Deferred revenue from a related party - long-term	$	—		$	35,378


	Year Ended December 31,
	2025		2024
Collaboration revenue from a related party recognized in the period from:
Amounts included in deferred revenue from a related party at the beginning of the period	$	36,841	$	28,271
Performance obligations satisfied in previous period	$	—	$	—

Gilead Agreements

In October 2023, the Company entered into the Gilead Collaboration Agreement and the Gilead Equity Agreements under which it received total proceeds of $100.0 million. Under the Gilead Collaboration Agreement, Gilead exclusively licensed to the Company its HPI program and NNPI program, while retaining opt-in rights to these programs and has an option to take an exclusive license, on a program-by-program basis, to all of the Company’s other current and future pipeline programs. During the 12-year collaboration term (subject to payment of certain

extension fees) and for a specified period thereafter, Gilead may exercise its opt-in rights, on a program-by-program basis, at one of two timepoints—completion of a certain Phase 1 study or, upon payment of a deferral fee and completion of a certain Phase 2 study for the first product within the program—upon payment of an opt-in fee ranging from $45.0 million to $125.0 million per program depending on the type of program and when the option is exercised.

In December 2024, the Company and Gilead entered into the First Amendment to the Gilead Collaboration Agreement, which restructured the timing of specific options exercisable in the agreement and the fees payable to the Company to support an accelerated development plan for 6250. To facilitate this development plan, the Company received a non-refundable payment of $10.0 million from Gilead and the opt-in fee payable by Gilead in connection with 6250 was restructured, though it remains in the range of opt-in fees detailed above. The $10.0 million payment received in connection with the First Amendment to the Gilead Collaboration Agreement is creditable towards future collaboration-related payments payable by Gilead. This credit was applied toward Gilead's opt-in fee paid for the HPI program in December 2025.

If Gilead exercises its opt-in right to any current or future program under the collaboration, the Company is eligible to receive up to $330.0 million in potential regulatory and commercial milestones on that program, in addition to royalties ranging from the high single-digits to high teens, depending on the clinical stage of the program at the time of the opt-in. Following Gilead’s exercise of its option for each program, the Company may opt-in to cover 40% of the research and development costs in the United States and share 40% of the profits and operating loss in the United States for products within the program in lieu of receiving milestones and royalties for that program in the United States, unless the Company later opts out of the cost/profit share for the program. Prior to Gilead’s potential exercise of its opt-in, the Company will be primarily responsible for all discovery, research and development on its programs and the two Gilead-contributed programs. Following Gilead’s opt-in, Gilead will control the further discovery, research, development, and commercialization on any optioned programs, and is responsible for all related costs unless the Company opts in to share 40% of all costs and profits in the United States. During the term, Gilead will continue to support the collaboration through extension fees of $75.0 million in each of the third, fifth and seventh anniversaries of the collaboration.

The Gilead Collaboration Agreement is subject to termination by either party for the other party’s uncured, material breach or insolvency. Subject to certain limitations, the Company and Gilead both have certain termination for convenience rights, upon sufficient prior written notice, with respect to programs that one party in-licenses from the other (subject to Gilead’s option rights), and with respect to Gilead, for programs it has option rights to (subject to certain time limitations with respect to existing Company programs). Gilead also has a right to terminate the collaborative activities under the Gilead Collaboration Agreement at certain specified points during the collaboration term. Other customary termination rights are further provided in the Gilead Collaboration Agreement.

R&D Services

At the commencement of the arrangement, the Company concluded Gilead was a customer and accordingly, the Gilead Collaboration Agreement was within the scope of the revenue from contracts with customers guidance. The Company initially identified a single combined performance obligation for the discovery, research and development services (the R&D Services) consisting of a series of distinct services that are substantially the same and have the same pattern of transfer. The Company concluded the R&D Services were distinct from Gilead's right to obtain an exclusive license to any of the Company's programs as Gilead benefits from the knowledge and expertise gained from the R&D Services and the Company's know-how is not highly specialized in nature. Gilead could perform the R&D Services themselves, particularly considering Gilead contributed its HPI and NNPI programs and Gilead may continue to conduct development activities on programs being developed under the Gilead Collaboration Agreement. None of the options in the contract were deemed to be separate performance obligations as the options did not provide any discounts or other rights which would be considered a material right in the arrangement.

In December 2024, Gilead exercised its right under the Gilead Equity Agreements to purchase additional shares of the Company's common stock for aggregate proceeds of $20.1 million, of which $5.2 million was determined to be a

premium on the purchase of the Company’s common stock and allocated to the single combined performance obligation under the Gilead Collaboration Agreement.

In December 2024, the Company determined the First Amendment to the Gilead Collaboration Agreement represented a contract modification within the scope of the revenue from contracts with customers guidance. In July 2025, upon its execution, the Company similarly concluded the letter agreement represented a contract modification under the same guidance. For both modifications, the Company determined no new distinct performance obligations were introduced, there continues to be a single combined performance obligation consisting of a series of distinct R&D Services, and therefore, the remaining services under the modified Gilead Collaboration Agreement are distinct from the R&D Services already provided.

Accordingly, the Company accounted for each modification as a termination of the existing contract and the creation of a new contract. The Company reassessed the transaction price upon each modification and recognized revenue prospectively by reassessing the transaction price and allocating it to the remaining R&D Services.

The amended transaction price as a result of the modification upon entering into the letter agreement in July 2025 was determined to be $54.4 million, consisting of the unrecognized portion of the transaction price under the contract immediately before the modification and $1.5 million of variable consideration for reimbursable costs expected to be incurred pursuant to the letter agreement.

The variable consideration related to the regulatory milestones has not been included in the transaction price as of December 31, 2025, as these amounts remain highly susceptible to factors outside the Company's influence. Any variable consideration related to commercial milestones and royalties will be recognized when the related sales occur pursuant to the Gilead Collaboration Agreement. The Company will reevaluate the transaction price in each reporting period as uncertain events are resolved or other changes in circumstances occur.

The transaction price is reflected as collaboration revenue when realized in the Company’s consolidated statements of operations. The Company recognizes revenue over time using a cost-based input method, based on internal and external labor cost effort to perform the services, over the initial non-cancellable term of three years since this method best reflects the transfer of services to Gilead. In applying a cost-based input method of revenue recognition, the Company uses actual costs incurred relative to estimated total costs to fulfill each performance obligation. A cost-based input method of revenue recognition requires the Company to make estimates of costs to complete the performance obligation. The cumulative effect of any revisions to estimated costs to complete the performance obligation and associated variable consideration will be recorded in the period in which changes are identified and amounts can be reasonably estimated. A significant change in these assumptions and estimates could have a material impact on the timing and amount of revenue recognized in future periods.

The Company recognized $37.3 million and $28.5 million of collaboration revenue for R&D Services performed under the Gilead Collaboration Agreement during the years ended December 31, 2025 and 2024, respectively. The Company incurred $0.1 million and $0.3 million in reimbursable expenses due to Gilead during the years ended December 31, 2025 and 2024, respectively.

HPI Program License

In December 2025, Gilead exercised its option to exclusively license the Company's HPI program for the treatment of recurrent genital herpes, including 5366 and 1179. Under the terms of the Gilead Collaboration Agreement, the Company received a $35.0 million payment in connection with Gilead’s exercise of its HPI program. The $35.0 million payment reflects a $45.0 million option fee, net of $10.0 million in accelerated funding the Company received under the First Amendment to the Gilead Collaboration Agreement, which was creditable against future payments. Gilead received an exclusive license to 5366 and 1179 and will have the sole right and responsibility for further clinical development and commercialization of the HPI program.

The Company remains eligible to receive up to $330.0 million in regulatory and commercial milestones, as well as tiered royalties on net sales ranging from the high single-digits to low teens. The Company also has the right to opt in to share 40% of all costs and profits in the United States (the Profit-Share) in lieu of receiving milestones and royalties for that program in the United States after receipt of a development plan and budget from Gilead; The Company has not opted into the Profit-Share as of the date of this report.

The Company determined the exclusive license granted to Gilead for the HPI program was a new contract under the contracts from customers accounting standard as it was deemed an exercise of a marketing offer made pursuant to the original terms of the Gilead Collaboration Agreement and First Amendment. The Company concluded the exclusive license granted to Gilead for the HPI program represents a distinct performance obligation because Gilead can benefit from the license together with readily available resources and its ability to sublicense the rights. The $35.0 million opt-in fee is included in the fixed transaction price. Variable consideration related to regulatory and commercial milestone payments, royalties and cost reimbursements are constrained because such amounts are highly susceptible to factors outside the Company's influence.

The Company recognized $35.0 million of collaboration revenue related to the exclusive license granted for the HPI program at a point in time upon transfer of the license, when Gilead obtained the ability to use and benefit from the license, during the year ended December 31, 2025.

Arbutus Biopharma Agreement

In August 2020, the Company and Arbutus Biopharma Corporation (Arbutus Biopharma) entered into a Clinical Trial Collaboration Agreement (the Arbutus Biopharma Agreement) to conduct a randomized, multi-center, open-label Phase 2 clinical trial to explore the safety, pharmacokinetics and antiviral activity of the triple combination of vebicorvir (VBR), AB-729 and a nucleos(t)ide analog reverse transcriptase inhibitor (NrtI) compared to the double combinations of VBR with a NrtI and AB-729 with a NrtI. Under the Arbutus Biopharma Agreement, Assembly and Arbutus Biopharma shared responsibility for the costs of the trial equally, excluding manufacturing supply which were the burden of each company to supply their respective drugs, VBR and AB-729. Assembly was responsible for conducting this clinical trial with Arbutus Biopharma reimbursing Assembly its share of expenses. In February 2023, Assembly and Arbutus Biopharma terminated the Phase 2 clinical trial early, at the end of the 48-week on-treatment period.

The Arbutus Biopharma Agreement was within the scope of the collaborative arrangements guidance as both parties were active participants and were exposed to significant risks and rewards dependent on the success of the collaborative activity. Reimbursements and cost-sharing portions from Arbutus Biopharma were reflected as a reduction of research and development expense when realized in the Company’s consolidated statements of operations. During the year ended December 31, 2024, the Company recognized research and development expenses of $0.3 million for net amounts refundable to Arbutus Biopharma after the final reconciliation of clinical trial costs.

Amounts refundable to Arbutus Biopharma were recorded as accrued research and development expenses on the consolidated balance sheet as of December 31, 2024.

Other Accrued Expenses (Tables)

12 Months Ended

Dec. 31, 2025

Payables and Accruals [Abstract]

Schedule of Other Accrued Expenses

Other accrued expenses consist of the following (in thousands):


	December 31,
	2025		2024
Accrued expenses:
Accrued compensation	$	7,523	$	6,478
Accrued professional fees and other		226		384
Total accrued expenses	$	7,749	$	6,862

CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit
Balance at Dec. 31, 2023	$ 41,097	$ 5	$ 826,921	$ (81)	$ (785,748)
Balance (in shares) at Dec. 31, 2023		5,482,752
Issuance of common stock under at-the-market (ATM) equity offering program, net of issuance costs	2,030		2,030
Issuance of common stock under at-the-market (ATM) equity offering program, net of issuance costs (in shares)		152,666
Issuance of common stock and warrants in a registered direct offering, net of issuance costs	9,662	$ 1	9,661
Issuance of common stock and warrants in a registered direct offering, net of issuance costs (in shares)		634,500
Issuance of common stock and warrants in private placements to a related party, net of issuance costs	17,602	$ 1	17,601
Issuance of common stock and warrants in private placements to a related party, net of issuance costs (in shares)		1,119,999
Issuance of common stock upon exercise of stock options	5		5
Issuance of common stock upon exercise of stock options (in shares)		514
Issuance of common stock under Employee Stock Purchase Plan (ESPP)	150		150
Issuance of common stock under Employee Stock Purchase Plan (ESPP) (in shares)		14,937
Issuance of common stock for settlement of restricted stock units (RSUs) (in shares)		51,872
Unrealized gain (loss) on marketable debt securities	(130)			(130)
Stock-based compensation	3,120		3,120
Net Income (Loss)	(40,177)				(40,177)
Balance at Dec. 31, 2024	33,359	$ 7	859,488	(211)	(825,925)
Balance (in shares) at Dec. 31, 2024		7,457,240
Issuance of common stock under at-the-market (ATM) equity offering program, net of issuance costs	1,922	$ 1	1,921
Issuance of common stock under at-the-market (ATM) equity offering program, net of issuance costs (in shares)		161,645
Issuance of common stock, pre-funded warrants and warrants in an underwritten offering, net of issuance costs	123,600	$ 6	123,594
Issuance of common stock, pre-funded warrants and warrants in an underwritten offering, net of issuance costs (in shares)		5,591,840
Issuance of common stock and warrants in private placements to a related party, net of issuance costs	42,785	$ 2	42,783
Issuance of common stock and warrants in private placements to a related party, net of issuance costs (in shares)		2,295,920
Issuance of common stock upon exercise of stock options	125		125
Issuance of common stock upon exercise of stock options (in shares)		5,406
Issuance of common stock upon exercise of warrants	5,510		5,510
Issuance of common stock upon exercise of warrants (in Shares)		255,103
Issuance of common stock under Employee Stock Purchase Plan (ESPP)	725		725
Issuance of common stock under Employee Stock Purchase Plan (ESPP) (in shares)		69,320
Issuance of common stock for settlement of restricted stock units (RSUs) (in shares)		18,855
Unrealized gain (loss) on marketable debt securities	170			170
Stock-based compensation	4,677		4,677
Net Income (Loss)	(6,122)				(6,122)
Balance at Dec. 31, 2025	$ 206,751	$ 16	$ 1,038,823	$ (41)	$ (832,047)
Balance (in shares) at Dec. 31, 2025		15,855,329

Segment Reporting (Tables)

12 Months Ended

Dec. 31, 2025

Segment Reporting [Abstract]

Schedule of Segment Expenses and Other Segment Items

The following table presents the significant segment expenses and other segment items regularly reviewed by the Company's CODM:


	Year Ended December 31,
	2025			2024
Collaboration revenue from a related party	$	72,303		$	28,520
Less:
External program expenses:
ABI-5366		9,353			6,215
ABI-1179		8,119			4,239
ABI-6250		5,780			6,396
ABI-4334		890			2,646
ABI-7272 (1)		2,300			—
Research and discovery		8,161			8,985
Vebicorvir		—			(43	)	(2)
Total external program expenses		34,603			28,438
Employee and contractor-related expenses (3)		26,729			23,819
Facility and other expenses		3,481			3,676
Total research and development		64,813			55,933
General and administrative (3)		19,608			18,007
Interest and other income, net		(5,996	)		(5,573	)
Income tax expense		—			330
Net loss	$	(6,122	)	$	(40,177	)

(1)

In October 2025, the Company transitioned its discovery and development from ABI-7423 to its parent molecule, ABI-7272, which is currently in regulatory filing-enabling preclinical studies.

(2)

(3)

Includes stock-based compensation expense, see Note 7 - Stock-Based Compensation for further details.

Income Taxes - Schedule of Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Current:
State	$ 0	$ 330
Income tax expense	$ 0	$ 330

- Definition

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References

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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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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 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
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-Section 50
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483443/250-10-50-9

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-22

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
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-Paragraph 1
-Subparagraph (SX 210.7-04(9))
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Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Name Accounting Standards Codification
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Reference 16: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Operating Leases

12 Months Ended

Dec. 31, 2025

Lease, Cost [Abstract]

Operating Leases

Note 11 - Operating Leases

In August 2023, the Company entered into a sublease agreement for office and laboratory space in South San Francisco, California to serve as the Company's corporate headquarters. The sublease originally expired in October 2025, with an option to extend through September 2029. In December 2024, the Company amended the sublease to extend the term through September 2029 and modify the base rent payments beginning in January 2025, with scheduled annual rent increases over the remaining lease term. The Company dissolved its China subsidiary in 2024, allowing the lease for its registrational office in Shanghai to expire in March 2024. The Company also leased certain laboratory equipment accounted for as operating leases, the last of which expired in 2025.

When the Company cannot determine the implicit rate in its leasing arrangements, the Company uses its incremental borrowing rate as the discount rate when measuring operating lease liabilities. The incremental borrowing rate represents an estimate of the interest rate the Company would incur at lease commencement to borrow an amount equal to the lease payments on a collateralized basis over the term of a lease within a particular currency environment.

At December 31, 2025, the Company had operating lease liabilities of $2.6 million and ROU assets of $2.5 million.

The following summarizes quantitative information about the Company’s operating leases (in thousands):


	Year Ended December 31,
	2025		2024
Lease cost
Operating lease cost	$	851	$	1,417
Short-term lease cost		—		1
Variable lease cost		817		727
Total lease cost, net	$	1,668	$	2,145

As of December 31, 2025, the weighted-average remaining lease term for operating leases was 3.8 years and the weighted-average discount rate for operating leases was 10.0%.

As of December 31, 2025, the maturities of the Company’s operating lease liabilities were as follows (in thousands):


2026	$	806
2027		834
2028		863
2029		671
Total		3,174
Less: present value discount		(546	)
Operating lease liabilities	$	2,628