0001628280-26-031726 | 10-Q | XBRL Viewer

Fair Value Measurements and Investments

3 Months Ended

Mar. 31, 2026

The following tables present the Company’s fair value hierarchy for its assets that are measured at fair value on a recurring basis and indicate the level of the fair value hierarchy utilized to determine such fair value:


	As of March 31, 2026:
(in thousands)	Level 1		Level 2		Level 3		Total
Cash equivalents:
Money market funds	$	—	$	62,762	$	—	$	62,762
Corporate debt securities	—		1,000		—		1,000

Short-term investments:
U.S. Treasury and government securities	—		47,374		—		47,374
Corporate debt securities	—		24,017		—		24,017
Total cash equivalents and investments	$	—	$	135,153	$	—	$	135,153


	As of December 31, 2025:
(in thousands)	Level 1		Level 2		Level 3		Total
Cash equivalents:
Money market funds	$	—	$	57,282	$	—	$	57,282
U.S. Treasury and government securities	—		2,739		—		2,739
Corporate debt securities	—		2,698		—		2,698
Short-term investment:
U.S. Treasury and government securities	—		78,152		—		78,152
Corporate debt securities			36,496				36,496
Total cash equivalents and investments	$	—	$	177,367	$	—	$	177,367

The Company classifies its investments as short-term based on each instrument’s underlying contractual maturity date. The fair value of investments classified as Level 2 are valued using observable inputs to quoted market prices, benchmark yields, reported trades, broker/dealer quotes or alternative pricing sources with reasonable levels of price transparency.

Investments in Debt Securities

Unrealized gains and losses of investments in debt securities consisted of the following:


	As of March 31, 2026:
(in thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
Short-term investments in debt securities:
U.S. Treasury and government securities	$	47,363	$	12	$	(1)	$	47,374
Corporate debt securities	24,029		—		(12)		24,017


Total short-term investments in debt securities	$	71,392	$	12	$	(13)	$	71,391


	As of December 31, 2025:
(in thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
Short-term investments in debt securities:
U.S. Treasury and government securities	$	78,074	$	78	$	—	$	78,152
Corporate debt securities	36,492		7		(3)		36,496
Total short-term investments in debt securities	$	114,566	$	85	$	(3)	$	114,648

The contractual maturities of the Company’s investments in debt securities were as follows:


(in thousands)	March 31, 2026		December 31, 2025
Due within one year	$	71,391	$	114,648

Marketable securities in unrealized loss positions consisted of the following:


	As of March 31, 2026:
(in thousands, except number of securities)	Number of Securities	Fair Value		Gross Unrealized Losses
Investments in continuous loss position for less than 12 months:
U.S. Treasury and government securities	3	$	2,487	$	(1)
Corporate debt securities	19	$	21,774	$	(12)

Based on factors such as historical experience, market data, issuer-specific factors, and current economic conditions, the Company did not record an allowance for credit losses as of March 31, 2026 related to these investments. Further, given the lack of significant change in the credit risk, the Company does not consider these investments to be impaired.

- Definition

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

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+ Details

Summary of Significant Accounting Policies

3 Months Ended

Mar. 31, 2026

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

The Company’s significant accounting policies are disclosed in Note 2, Summary of significant accounting policies, in the audited consolidated financial statements for the year ended December 31, 2025, and notes thereto, included in the Company’s Annual Report on Form 10-K that was filed with the SEC on March 3, 2026. Since the date of those financial statements, there have been no material changes to its significant accounting policies, except as noted below.

Use of Estimates

The preparation of the Company’s condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements

and the reported amounts of revenues and expenses during the reporting periods. Significant estimates and assumptions reflected within these condensed consolidated financial statements include, but are not limited to, the valuation of the Company’s common stock and stock-based awards. The Company bases its estimates on historical experience, known trends and other market-specific or other relevant factors that it believes to be reasonable under the circumstances. On an ongoing basis, management evaluates its estimates, as there are changes in circumstances, facts and experience. Actual results may differ materially from those estimates or assumptions.

Segment Information

Under ASC 280, Segment Reporting, operating segment is a component of a public entity that 1) engages in business activities from which it may recognize revenues and incur expenses, 2) its operating results are regularly reviewed by the entity’s chief operating decision maker, or CODM, to make decisions about resource allocation or performance assessment, and 3) its discrete financial information is available. The Company operates and manages its business as a single segment for the purposes of assessing performance and making operating decisions.

Our chief executive officer, who is the CODM, manages and allocates resources to the operations of our company on a total company basis by assessing the overall level of resources available and how to best deploy these resources across functions and research and development projects that are in line with our long-term company-wide strategic goals. In making these decisions, the CODM uses consolidated financial information for purposes of evaluating performance, forecasting future period financial results, allocating resources and setting incentive targets. The CODM performs this assessment based on the Company’s consolidated net loss. Through this analysis, the CODM assesses performance by comparing actual net loss verses the budget, and then decides how to allocate resources to invest in the Company’s research and development programs. The measure of segment assets is reported on the condensed consolidated balance sheets as total assets.

The following table contains additional information on our consolidated net loss, including significant segment expenses:


	Three Months Ended March 31,
(in thousands)		2026		2025
Total revenue		$	856	$	1,454
Operating expenses:
Research and development expenses
Personnel expenses		11,053		14,800
Facility related		10,266		10,969
Research costs		7,260		11,036
General and administrative expenses:
Personnel expenses		5,532		7,156
Other segment items (1)		17,399		9,885
Total operating expenses		51,510		53,846
Total other income, net		1,532		502

Net loss		$	(49,122)	$	(51,890)

(1) Other segment items consist of professional and consultant fees, license and intellectual property fees, and general and administrative facility costs.

Recently Issued Accounting Pronouncements Not Yet Adopted

In November 2024, the FASB issued ASU 2024-03, Disaggregation of Income Statement Expenses, which requires more detailed information about specified categories of expenses included in certain expense captions presented on the face of the income statement. This ASU is effective for fiscal years beginning after December 15, 2026, and for interim periods within fiscal years beginning after December 15, 2027. Early adoption is permitted. The amendments may be applied either (1) prospectively to financial statements issued for reporting periods after the

effective date of this ASU or (2) retrospectively to all prior periods presented in the financial statements. The Company is currently evaluating the impact this ASU will have on its disclosures.

In September 2025, the FASB issued ASU No. 2025-07, Derivatives and Hedging (Topic 815) and Revenue from Contracts with Customers (Topic 606): Derivatives Scope Refinements and Scope Clarification for Share-Based Noncash Consideration from a Customer in a Revenue Contract. This update introduces a scope exception to derivative accounting for certain contracts with underlyings tied to operations or activities specific to one of the parties. Additionally, the update clarifies that share-based noncash consideration received from a customer should be accounted for under Topic 606 until the right to receive or retain the consideration becomes unconditional. The amendments can be applied prospectively or modified retrospectively and are effective for annual and interim periods beginning after December 15, 2026. The Company is currently evaluating the impact to the Company’s consolidated financial statements.

In December 2025, the FASB issued ASU No. 2025-11, Interim Reporting (Topic 270): Narrow-scope Improvements, which improves the navigability of interim reporting guidance. The ASU also addresses the form and content of financial statements, adds lists to ASC 270 of the interim disclosures required by all other codification topics, and establishes a principle under which an entity must “disclose events since the end of the last annual reporting period that have a material impact on the entity.” This ASU is effective for interim reporting periods within annual reporting periods beginning after December 15, 2027, with early adoption permitted. The Company is currently evaluating the impact this ASU will have on its interim disclosures.

Other accounting standards that have been issued by the FASB or other standards-setting bodies that do not require adoption until a future date are not expected to have a material impact on the Company’s financial statements upon adoption.

Stock-Based Compensation

3 Months Ended

Mar. 31, 2026

Share-Based Payment Arrangement [Abstract]

Stock-Based Compensation

2019 Stock Option and Grant Plan

The Company’s 2019 Stock Option and Grant Plan, or the 2019 Plan, provided for the Company to grant incentive stock options, non-qualified stock options, unrestricted stock awards, restricted stock awards and other stock-based awards to the officers, employees, consultants and other key persons of the Company. In October 2022, in

connection with the closing of the Company’s initial public offering, the Board of Directors determined that no further awards would be granted under the 2019 Plan.

2022 Stock Option and Incentive Plan

On February 9, 2022, the Board of Directors adopted, and on October 10, 2022, the Company’s stockholders approved, the 2022 Stock Option and Incentive Plan, or the 2022 Plan, which became effective on October 18, 2022. The 2022 Plan allows the Company to make equity-based and cash-based incentive awards to its officers, employees, directors, and consultants. The 2022 Plan provides for the grant of incentive stock options, non-qualified stock options, stock appreciation rights, restricted stock awards, restricted stock units and other stock-based awards.

The shares of common stock underlying any awards under the 2022 Plan and the 2019 Plan that are forfeited, cancelled, held back upon exercise or settlement of an award to satisfy the exercise price or tax withholding, reacquired by the Company prior to vesting, satisfied without the issuance of stock, expire, or are otherwise terminated (other than by exercise) will be added back to the shares of common stock available for issuance under the 2022 Plan. The number of shares reserved and available for issuance under the 2022 Plan increased on January 1, 2023 and will increase on each January 1 hereafter, by five percent of the outstanding number of shares of common stock on the immediately preceding December 31 or such lesser number of shares as determined by the Compensation Committee of the Board of Directors. On January 1, 2026, the annual increase resulted in an additional 9,025,700 shares authorized being added to the 2022 Plan. As of March 31, 2026, the Company had 34,482,330 shares reserved under the 2022 Plan and the 2019 Plan, and 11,573,377 shares available for issuance under the 2022 Plan.

2022 Employee Stock Purchase Plan

On February 9, 2022, the Board of Directors adopted, and on October 10, 2022, the Company’s stockholders approved, the 2022 Employee Stock Purchase Plan, or the 2022 ESPP, which became effective on October 18, 2022.

The number of shares of common stock that may be issued under the 2022 ESPP cumulatively increased beginning on January 1, 2023 and shall increase on each January 1 hereafter through January 1, 2032, by the least of (i) 971,350 shares of common stock, (ii) one percent of the outstanding number of shares of common stock on the immediately preceding December 31, or (iii) such number of shares of common stock as determined by the administrator of the 2022 ESPP. There was no annual increase for the 2022 ESPP on January 1, 2026. As of March 31, 2026, the Company had 1,522,025 shares available for issuance under the 2022 ESPP.

During the three months ended March 31, 2026, the Company issued no shares of the Company’s common stock under the 2022 ESPP.

Stock Options

The following table summarizes the Company’s time-based stock option activity for the three months ended March 31, 2026:


	Number of Shares	Weighted-Average Exercise Price
Outstanding at December 31, 2025	15,637,303	$	3.76
Granted	5,369,115	3.59
Exercised	(101,500)	3.86
Cancelled or forfeited	(25,529)	6.83
Outstanding at March 31, 2026	20,879,389	$	3.71
Options vested and exercisable at March 31, 2026	7,875,474	$	4.69
Options vested and expected to vest at March 31, 2026	20,879,389	$	3.71

As of March 31, 2026, there was $36.5 million of total unrecognized compensation cost related to time-based stock options, including incremental expense related to the Company’s option repricing announced in August 2025. The Company expects to recognize such amount over a remaining weighted-average period of 2.9 years.

Performance-Based Stock Options

The following table summarizes the Company’s performance-based stock option activity for the three months ended March 31, 2026:


	Number of Shares	Weighted-Average Exercise Price
Outstanding at December 31, 2025	2,029,564	$	4.10
Granted	—	—
Exercised	—	—
Cancelled or forfeited	—	—
Outstanding at March 31, 2026	2,029,564	$	4.10
Vested and exercisable at March 31, 2026	813,480	$	5.26

As of March 31, 2026, there was $3.1 million of total unrecognized compensation cost related to performance-based stock options.

Stock-Based Compensation

The following table below summarizes the classification of the Company’s stock-based compensation expense related to stock options and restricted common stock awards in the condensed consolidated statements of operations and comprehensive loss:


	Three Months Ended March 31,
(in thousands)		2026		2025
Stock-based compensation expense:
Research and development		$	2,453	$	2,856
General and administrative		2,191		2,825
Total stock-based compensation expense		$	4,644	$	5,681

Significant Agreements (Tables)

3 Months Ended

Mar. 31, 2026

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Schedule of Supplemental Information related to the BMS Collaboration Agreement

Supplemental information related to the Research Collaboration and License Agreement, or the BMS Collaboration Agreement, with Juno Therapeutics, Inc., a wholly-owned subsidiary of the Bristol-Myers Squibb Company, or BMS, consisted of the following:


(in thousands)	March 31, 2026		December 31, 2025

Deferred revenue — related party	$	7,320	$	7,824
Deferred revenue, net of current — related party	$	57,775	$	58,127


	Three Months Ended March 31,
(in thousands)		2026		2025
Revenue recognized that was included in contract liability at the beginning of the period		$	856	$	1,419

Fair Value Measurements and Investments - Schedule of Short-Term Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	$ 71,392	$ 114,566
Unrealized Gains	12	85
Unrealized Losses	(13)	(3)
Fair Value	71,391	114,648
U.S. Treasury and government securities
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	47,363	78,074
Unrealized Gains	12	78
Unrealized Losses	(1)	0
Fair Value	47,374	78,152
Corporate debt securities
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	24,029	36,492
Unrealized Gains	0	7
Unrealized Losses	(12)	(3)
Fair Value	$ 24,017	$ 36,496

- Definition

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

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- Definition

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+ Details

Net Loss per Share - Schedule of Earnings Per Share, Basic and Diluted (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Numerator:
Net loss attributable to common stockholders, basic	$ (49,122)	$ (51,890)
Net loss attributable to common stockholders, diluted	$ (49,122)	$ (51,890)
Denominator:
Weighted-average common shares outstanding, basic (in shares)	177,096,225	130,884,490
Weighted-average common shares outstanding, diluted (in shares)	177,096,225	130,884,490
Net loss per share attributable to common stockholders, basic (in dollars per share)	$ (0.28)	$ (0.40)
Net loss per share attributable to common stockholders, diluted (in dollars per share)	$ (0.28)	$ (0.40)

- 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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+ Details

- Definition

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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+ Details

- Definition

Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities; of income (loss) available to common shareholders.

+ References

+ Details

- Definition

Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities, and addition from assumption of issuance of common shares for dilutive potential common shares; of income (loss) available to common shareholders.

+ References + Details

Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Payables and Accruals [Abstract]
Research and clinical costs	$ 2,197	$ 1,997
Employee compensation and benefits	2,190	7,337
License fee	1,562	1,562
Other	2,149	1,704
Total accrued expenses and other current liabilities	$ 8,098	$ 12,600

Stock-Based Compensation - Schedule of Stock-Based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Share-based compensation expense	$ 4,644	$ 5,681
Research and development
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Share-based compensation expense	2,453	2,856
General and administrative
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Share-based compensation expense	$ 2,191	$ 2,825

Stockholder’s Equity (Details) $ / shares in Units, $ in Millions	1 Months Ended
	Nov. 30, 2023 USD ($)	Mar. 31, 2026 vote $ / shares
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Common stock, par value under amendment (in dollars per share) \| $ / shares		$ 0.00001
Number of votes per common share \| vote		1
2023 ATM Program \| Common Stock
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Sale of stock, consideration received	$ 200.0
Sales Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Sale of stock, consideration received	300.0
Additional supplements	100.0
Sales Agreement \| 2023 ATM Program \| Common Stock
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Sale of stock, consideration received	$ 300.0

Leases (Details) $ in Thousands	Mar. 31, 2026 USD ($)
Leases [Abstract]
Remaining in 2026	$ 16,352
2027	22,355
2028	22,294
2029	21,478
2030	22,123
Thereafter	74,478
Total undiscounted lease payments	179,080
Less: imputed interest	(64,568)
Total operating lease liability	$ 114,512

Property and Equipment, Net

3 Months Ended

Mar. 31, 2026

Property, Plant and Equipment [Abstract]

Property and Equipment, Net

Property and equipment, net consisted of the following:


(in thousands)	March 31, 2026		December 31, 2025
Property and equipment:
Laboratory equipment	$	30,019	$	29,744
Leasehold improvement	7,911		7,911
Furniture and fixture	1,864		1,864
Computer hardware and software	1,122		1,122
Construction in progress	190		365
Total property and equipment	41,106		41,006
Less: Accumulated depreciation	(22,290)		(20,434)
Total property and equipment, net	$	18,816	$	20,572

Depreciation expense related to property and equipment is as follows:


	Three Months Ended March 31,
(in thousands)		2026		2025
Depreciation expense		$	1,856	$	1,700

Fair Value Measurements and Investments - Schedule of Marketable Securities In Unrealized Loss Position (Details) $ in Thousands	Mar. 31, 2026 USD ($) security
U.S. Treasury and government securities
Investments in continuous loss position for less than 12 months:
Number of Securities \| security	3
Fair Value	$ 2,487
Gross Unrealized Losses	$ (1)
Corporate debt securities
Investments in continuous loss position for less than 12 months:
Number of Securities \| security	19
Fair Value	$ 21,774
Gross Unrealized Losses	$ (12)

Significant Agreements - Schedule of Supplemental Information related to the BMS Collaboration Agreement (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Dec. 31, 2025
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Deferred revenue — related party	$ 7,320		$ 7,824
Deferred revenue, net of current — related party	57,775		58,127
Juno Therapeutics, Inc. \| Collaborative Arrangement, Research Collaboration and License Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Deferred revenue — related party	7,320		7,824
Deferred revenue, net of current — related party	57,775		$ 58,127
Revenue recognized that was included in contract liability at the beginning of the period	$ 856	$ 1,419

Fair Value Measurements and Investments - Schedule of Hierarchy For Assets and Liabilities Measured At Fair Value On A Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	$ 71,391	$ 114,648
Total assets	135,153	177,367
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	62,762	57,282
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	1,000	2,698
Short-term investments	24,017	36,496
U.S. Treasury and government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents		2,739
Short-term investments	47,374	78,152
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Level 1 \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Level 1 \| Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Short-term investments	0
Level 1 \| U.S. Treasury and government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents		0
Short-term investments	0	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	135,153	177,367
Level 2 \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	62,762	57,282
Level 2 \| Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	1,000	2,698
Short-term investments	24,017	36,496
Level 2 \| U.S. Treasury and government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents		2,739
Short-term investments	47,374	78,152
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Level 3 \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Level 3 \| Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Short-term investments	0
Level 3 \| U.S. Treasury and government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents		0
Short-term investments	$ 0	$ 0

Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2026

Share-Based Payment Arrangement [Abstract]

Schedule of Share-Based Payment Arrangement, Option, Activity

The following table summarizes the Company’s time-based stock option activity for the three months ended March 31, 2026:


	Number of Shares	Weighted-Average Exercise Price
Outstanding at December 31, 2025	15,637,303	$	3.76
Granted	5,369,115	3.59
Exercised	(101,500)	3.86
Cancelled or forfeited	(25,529)	6.83
Outstanding at March 31, 2026	20,879,389	$	3.71
Options vested and exercisable at March 31, 2026	7,875,474	$	4.69
Options vested and expected to vest at March 31, 2026	20,879,389	$	3.71

The following table summarizes the Company’s performance-based stock option activity for the three months ended March 31, 2026:


	Number of Shares	Weighted-Average Exercise Price
Outstanding at December 31, 2025	2,029,564	$	4.10
Granted	—	—
Exercised	—	—
Cancelled or forfeited	—	—
Outstanding at March 31, 2026	2,029,564	$	4.10
Vested and exercisable at March 31, 2026	813,480	$	5.26

Schedule of Stock-Based Compensation


	Three Months Ended March 31,
(in thousands)		2026		2025
Stock-based compensation expense:
Research and development		$	2,453	$	2,856
General and administrative		2,191		2,825
Total stock-based compensation expense		$	4,644	$	5,681

Stock-Based Compensation - Schedule of Stock Option Activity (Details)	3 Months Ended
	Mar. 31, 2026 $ / shares shares
Number of Shares
Beginning of period (in shares) \| shares	15,637,303
Granted (in shares) \| shares	5,369,115
Exercised (in shares) \| shares	(101,500)
Cancelled or forfeited (in shares) \| shares	(25,529)
End of period (in shares) \| shares	20,879,389
Options vested and exercisable, end of period (in shares) \| shares	7,875,474
Options vested and expected to vest, end of period (in shares) \| shares	20,879,389
Weighted-Average Exercise Price
Beginning of period (in dollars per share) \| $ / shares	$ 3.76
Granted (in dollars per share) \| $ / shares	3.59
Exercised (in dollars per share) \| $ / shares	3.86
Cancelled or forfeited (in dollars per share) \| $ / shares	6.83
End of period (in dollars per share) \| $ / shares	3.71
Options vested and exercisable, end of period (in dollars per share) \| $ / shares	4.69
Options vested and expected to vest, end of period (in dollars per share) \| $ / shares	$ 3.71
Performance-Based Stock Options
Number of Shares
Beginning of period (in shares) \| shares	2,029,564
Granted (in shares) \| shares	0
Exercised (in shares) \| shares	0
Cancelled or forfeited (in shares) \| shares	0
End of period (in shares) \| shares	2,029,564
Options vested and exercisable, end of period (in shares) \| shares	813,480
Weighted-Average Exercise Price
Beginning of period (in dollars per share) \| $ / shares	$ 4.10
Granted (in dollars per share) \| $ / shares	0
Exercised (in dollars per share) \| $ / shares	0
Cancelled or forfeited (in dollars per share) \| $ / shares	0
End of period (in dollars per share) \| $ / shares	4.10
Options vested and exercisable, end of period (in dollars per share) \| $ / shares	$ 5.26

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Mar. 31, 2026
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

Net Loss per Share - Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share (Details) - shares	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive common stock equivalents (in shares)	25,165,415	19,391,733
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive common stock equivalents (in shares)	21,692,869	15,919,190
Unvested performance-based restricted common stock awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive common stock equivalents (in shares)	3,472,546	3,472,543

Net Loss per Share

3 Months Ended

Mar. 31, 2026

Earnings Per Share [Abstract]

Net Loss per Share

Basic and diluted net loss per common share attributable to common stockholders was calculated as follows:


	Three Months Ended March 31,
(in thousands, except share and per share amounts)		2026		2025
Numerator:



Net loss attributable to common stockholders		$	(49,122)	$	(51,890)
Denominator:
Weighted-average common shares outstanding, basic and diluted		177,096,225		130,884,490
Net loss per share attributable to common stockholders, basic and diluted		$	(0.28)	$	(0.40)

Diluted net loss per share available to common stockholders is computed by giving effect to all potentially dilutive common stock equivalents outstanding for the period. For purposes of this calculation, outstanding time-based stock options to purchase common stock, vested performance-based stock options to purchase common stock, and unvested performance-based restricted stock awards were considered common stock equivalents but had been excluded from the calculation of diluted net loss per share available to common stockholders as their effect was anti-dilutive. In periods in which the Company reports a net loss available to common stockholders, diluted net loss per share available to common stockholders is the same as basic net loss per share available to common stockholders, since dilutive common shares are not assumed to have been issued if their effect is anti-dilutive.

The following common stock equivalents were excluded from the calculation of diluted net loss per share applicable to common stockholders for the periods indicated because including them would have had an anti-dilutive effect:


	As of March 31,
	2026	2025
Anti-dilutive common stock equivalents:
Options to purchase common stock	21,692,869	15,919,190
Unvested performance-based restricted common stock awards	3,472,546	3,472,543
Total anti-dilutive common stock equivalents:	25,165,415	19,391,733

Cover - shares	3 Months Ended
Cover - shares	Mar. 31, 2026	Apr. 30, 2026
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2026
Document Transition Report	false
Entity File Number	001-41536
Entity Registrant Name	Prime Medicine, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	84-3097762
Entity Address, Address Line One	60 First Street
Entity Address, City or Town	Cambridge
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02141
City Area Code	(617)
Local Phone Number	465-0013
Title of 12(b) Security	Common stock, par value $0.00001 per share
Trading Symbol	PRME
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		180,617,451
Entity Central Index Key	0001894562
Amendment Flag	false
Document Fiscal Year Focus	2026
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	--12-31

Summary of Significant Accounting Policies (Tables)

3 Months Ended

Mar. 31, 2026

Accounting Policies [Abstract]

Schedule of Segment Reporting Information, by Segment

The following table contains additional information on our consolidated net loss, including significant segment expenses:


	Three Months Ended March 31,
(in thousands)		2026		2025
Total revenue		$	856	$	1,454
Operating expenses:
Research and development expenses
Personnel expenses		11,053		14,800
Facility related		10,266		10,969
Research costs		7,260		11,036
General and administrative expenses:
Personnel expenses		5,532		7,156
Other segment items (1)		17,399		9,885
Total operating expenses		51,510		53,846
Total other income, net		1,532		502

Net loss		$	(49,122)	$	(51,890)

(1) Other segment items consist of professional and consultant fees, license and intellectual property fees, and general and administrative facility costs.

Leases (Tables)

3 Months Ended

Mar. 31, 2026

Leases [Abstract]

Schedule of Operating Lease Liability

The table below reconciles the undiscounted future annual lease payments to the total operating lease liabilities recorded in the condensed consolidated balance sheet as of March 31, 2026:


(in thousands)	Undiscounted Amounts
Undiscounted lease payments:
Remaining in 2026	$	16,352
2027	22,355
2028	22,294
2029	21,478
2030	22,123
Thereafter	74,478
Total undiscounted lease payments	179,080

Less: imputed interest	(64,568)
Total operating lease liability	$	114,512

Significant Agreements - Narrative (Details) $ in Millions	Mar. 31, 2026 USD ($)
Juno Therapeutics, Inc. \| Collaborative Arrangement, Research Collaboration and License Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Aggregate amount of the transaction price allocated to performance obligations that are partially unsatisfied	$ 65.1

Fair Value Measurements and Investments (Tables)

3 Months Ended

Mar. 31, 2026

Fair Value Disclosures [Abstract]

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


	As of March 31, 2026:
(in thousands)	Level 1		Level 2		Level 3		Total
Cash equivalents:
Money market funds	$	—	$	62,762	$	—	$	62,762
Corporate debt securities	—		1,000		—		1,000

Short-term investments:
U.S. Treasury and government securities	—		47,374		—		47,374
Corporate debt securities	—		24,017		—		24,017
Total cash equivalents and investments	$	—	$	135,153	$	—	$	135,153


	As of December 31, 2025:
(in thousands)	Level 1		Level 2		Level 3		Total
Cash equivalents:
Money market funds	$	—	$	57,282	$	—	$	57,282
U.S. Treasury and government securities	—		2,739		—		2,739
Corporate debt securities	—		2,698		—		2,698
Short-term investment:
U.S. Treasury and government securities	—		78,152		—		78,152
Corporate debt securities			36,496				36,496
Total cash equivalents and investments	$	—	$	177,367	$	—	$	177,367

Schedule of Debt Securities, Available-for-Sale

Unrealized gains and losses of investments in debt securities consisted of the following:


	As of March 31, 2026:
(in thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
Short-term investments in debt securities:
U.S. Treasury and government securities	$	47,363	$	12	$	(1)	$	47,374
Corporate debt securities	24,029		—		(12)		24,017


Total short-term investments in debt securities	$	71,392	$	12	$	(13)	$	71,391


	As of December 31, 2025:
(in thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
Short-term investments in debt securities:
U.S. Treasury and government securities	$	78,074	$	78	$	—	$	78,152
Corporate debt securities	36,492		7		(3)		36,496
Total short-term investments in debt securities	$	114,566	$	85	$	(3)	$	114,648

Marketable securities in unrealized loss positions consisted of the following:


	As of March 31, 2026:
(in thousands, except number of securities)	Number of Securities	Fair Value		Gross Unrealized Losses
Investments in continuous loss position for less than 12 months:
U.S. Treasury and government securities	3	$	2,487	$	(1)
Corporate debt securities	19	$	21,774	$	(12)

Schedule of Investments Classified by Contractual Maturity Date

The contractual maturities of the Company’s investments in debt securities were as follows:


(in thousands)	March 31, 2026		December 31, 2025
Due within one year	$	71,391	$	114,648

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-9

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-3

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
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-Section 50
-Paragraph 2
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-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (aa)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

Reference 7: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
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-Name Accounting Standards Codification
-Section 50
-Paragraph 2
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

Reference 8: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

Reference 9: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-3

Reference 10: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
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-Name Accounting Standards Codification
-Section 50
-Paragraph 3
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-3

Reference 11: http://www.xbrl.org/2009/role/commonPracticeRef
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-Name Accounting Standards Codification
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-Paragraph 3
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-URI https://asc.fasb.org/1943274/2147481800/320-10-50-3

Reference 12: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-3

+ Details

Fair Value Measurements and Investments - Schedule of Investments Classified by Contractual Maturity Date (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Fair Value Disclosures [Abstract]
Due within one year	$ 71,391	$ 114,648

Leases

3 Months Ended

Mar. 31, 2026

Leases [Abstract]

Leases

The Company leases office and laboratory space under various non-cancelable operating leases. The Company’s significant lease agreements are disclosed in Note 9, Leases, in the audited consolidated financial statements for the year ended December 31, 2025, and notes thereto, included in the Company’s Annual Report on Form 10-K that was filed with the SEC on March 3, 2026. Since the date of those financial statements, there have been no changes to the Company’s significant agreements.

The table below reconciles the undiscounted future annual lease payments to the total operating lease liabilities recorded in the condensed consolidated balance sheet as of March 31, 2026:


(in thousands)	Undiscounted Amounts
Undiscounted lease payments:
Remaining in 2026	$	16,352
2027	22,355
2028	22,294
2029	21,478
2030	22,123
Thereafter	74,478
Total undiscounted lease payments	179,080

Less: imputed interest	(64,568)
Total operating lease liability	$	114,512

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Current assets:
Cash and cash equivalents	$ 64,106	$ 63,032
Short-term investments	71,391	114,648
Prepaid expenses	1,971	2,939
Other current assets	421	674
Total current assets	137,889	181,293
Property and equipment, net	18,816	20,572
Operating lease right-of-use assets	123,334	126,177
Restricted cash	13,691	13,691
Other assets	1,000	1,000
Total assets	294,730	342,733
Current liabilities:
Accounts payable	12,325	8,887
Accrued expenses and other current liabilities	8,098	12,600
Deferred revenue — related party	7,320	7,824
Operating lease liability	8,546	8,137
Total current liabilities	36,289	37,448
Deferred revenue, net of current — related party	57,775	58,127
Operating lease liability, net of current	105,966	108,290
Research and development funding liability	18,000	18,000
Total liabilities	218,030	221,865
Commitments and contingencies
Stockholders’ equity
Common stock, par value of $0.00001 per share; 775,000,000 shares authorized; 180,615,514 and 180,514,014 shares issued and outstanding as of March 31, 2026 and December 31, 2025, respectively	2	2
Additional paid-in capital	1,014,175	1,009,138
Accumulated other comprehensive (loss) income	(1)	82
Accumulated deficit	(937,476)	(888,354)
Total stockholders’ equity	76,700	120,868
Total liabilities and stockholders’ equity	$ 294,730	$ 342,733

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Operating expenses:
Research and development	$ 34,105	$ 40,562
General and administrative	17,405	13,284
Total operating expenses	51,510	53,846
Loss from operations	(50,654)	(52,392)
Other income:
Interest income	1,021	1,182
Accretion (amortization) of investments	460	339
Change in fair value of short-term investment — related party	0	(1,056)
Other income, net	51	37
Total other income, net	1,532	502
Net loss attributable to common stockholders, basic	(49,122)	(51,890)
Net loss attributable to common stockholders, diluted	$ (49,122)	$ (51,890)
Net loss per share attributable to common stockholders, basic (in dollars per share)	$ (0.28)	$ (0.40)
Net loss per share attributable to common stockholders, diluted (in dollars per share)	$ (0.28)	$ (0.40)
Weighted-average common shares outstanding, basic (in shares)	177,096,225	130,884,490
Weighted-average common shares outstanding, diluted (in shares)	177,096,225	130,884,490
Comprehensive loss:
Net loss	$ (49,122)	$ (51,890)
Change in unrealized (loss) income on investments, net of tax	(83)	(16)
Comprehensive loss	(49,205)	(51,906)
Related Party
Collaboration revenue	$ 856	$ 1,454

Significant Agreements

3 Months Ended

Mar. 31, 2026

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Significant Agreements

The Company’s significant agreements are disclosed in Note 9, License and Collaboration Agreements, in the audited consolidated financial statements for the year ended December 31, 2025, and notes thereto, included in the Company’s Annual Report on Form 10-K that was filed with the SEC on March 3, 2026. Since the date of those financial statements, there have been no changes to the Company’s significant agreements except those discussed below.

Bristol-Myers Squibb — Related Party


(in thousands)	March 31, 2026		December 31, 2025

Deferred revenue — related party	$	7,320	$	7,824
Deferred revenue, net of current — related party	$	57,775	$	58,127


	Three Months Ended March 31,
(in thousands)		2026		2025
Revenue recognized that was included in contract liability at the beginning of the period		$	856	$	1,419

As of March 31, 2026, the aggregate amount of the transaction price allocated to performance obligations under the BMS Collaboration Agreement that are partially unsatisfied was $65.1 million. The Company recognizes the portion of the transaction price as the single performance obligation is satisfied, using an input method, in proportion to costs incurred to date as compared to total costs incurred and expected to be incurred in the future to satisfy the underlying obligation.

Beam Collaboration Agreement — Related Party

The Company is currently engaged in arbitration proceedings with Beam Therapeutics, Inc., or Beam, regarding the parties’ collaboration and license agreement, or the Agreement. A dispute arose between the parties following the Company’s March 18, 2025 announcement that it is developing a Prime Editing-based treatment for alpha-1 antitrypsin deficiency, or AATD. On April 16, 2025, Beam filed an arbitration demand with the American Arbitration Association, or AAA, alleging that the Company has breached the Agreement by developing a product for the treatment of AATD and by allegedly not complying with certain obligations to transfer technical information to Beam pursuant to the Agreement. Beam also made related claims for trade secret misappropriation and various business torts based on similar allegations. Beam seeks both declaratory, injunctive, and monetary relief. On April 18, 2025, the Company filed an arbitration demand with the AAA seeking a declaration that the Company’s AATD program is within our “Field” as defined by the Agreement. The arbitrations were consolidated and a hearing was conducted earlier this year. The Company is currently waiting for the arbitrators’ decision and final resolution. If the final resolution of the matter is adverse to the Company, the arbitration panel may provide Beam with relief including, among other things, monetary damages and/or an order that the Company cease work on its AATD program and transfer such program to Beam.

Stockholder’s Equity	3 Months Ended
Stockholder’s Equity	Mar. 31, 2026
Equity [Abstract]
Stockholder’s Equity	Stockholder’s Equity Common Stock Under the Company’s Third Amended and Restated of Certificate of Incorporation, as amended, the Company’s common stock had a par value of $0.00001 and each share of common stock entitles the holder to one vote on all matters submitted to the stockholders for a vote. The holders of common stock are entitled to receive dividends, if any, as declared by the Company’s Board of Directors, or the Board of Directors. At-The-Market Equity Program In November 2023, the Company entered into Open Market Sale AgreementSM, or the Sales Agreement, with Jefferies LLC, or Jefferies, acting as the Company’s agent and/or principal, or the Sales Agent, with respect to an “at the market offering” program under which the Company may, from time to time, at its sole discretion, issue and sell shares of its common stock having an aggregate offering price of up to $300.0 million through the Sales Agent, or the 2023 ATM Program. Pursuant to the Sales Agreement, any shares will be sold pursuant to the shelf registration statement on Form S-3 (File No. 333-291348), originally filed with the SEC on Form S-3ASR on November 7, 2025, and converted to Form S-3 by post-effective amendments effective March 4, 2026, including the base prospectus and sales agreement prospectus contained therein (as amended), or the New Registration Statement. Any shares will be sold pursuant to the New Registration Statement and the sales agreement prospectus filed therewith, or the ATM Prospectus, which covers the offer and sale of shares of the Company’s common stock under the 2023 ATM Program having an aggregate offering price of up to $200.0 million of the $300.0 million authorized under the Sales Agreement. If the Company wishes to offer and sell additional shares of its common stock under the Sales Agreement in excess of the $200.0 million registered under the New Registration Statement, for up to an additional $100.0 million, the Company must file with the SEC one or more additional prospectus supplements to register under the Securities Act, the offer and sale of any such additional shares. The common stock will be sold at prevailing market prices at the time of the sale, and as a result, prices may vary. As of March 31, 2026 and as of the date these condensed consolidated financial statements are issued, the Company has not sold any shares of common stock under the ATM Prospectus.

- Definition

The entire disclosure for equity.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
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-URI https://asc.fasb.org/1943274/2147480434/815-10-50-8A

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-13

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org/1943274/2147481112/505-10-50-14

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 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Accrued Expenses and Other Current Liabilities (Tables)

3 Months Ended

Mar. 31, 2026

Payables and Accruals [Abstract]

Schedule of Accrued Liabilities

Accrued expenses and other current liabilities consisted of the following:


(in thousands)	March 31, 2026		December 31, 2025
Accrued expenses and other current liabilities
Research and clinical costs	$	2,197	$	1,997
Employee compensation and benefits	2,190		7,337

License fee	1,562		1,562

Other	2,149		1,704
Total accrued expenses and other current liabilities	$	8,098	$	12,600

Stock-Based Compensation - Narrative (Details) - USD ($) $ in Millions		3 Months Ended
	Feb. 09, 2022	Mar. 31, 2026	Jan. 01, 2023
Options to purchase common stock \| 2022 Stock Option and Incentive Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Percentage of annual increase in shares reserved for future issuance (as a percent)	5.00%
Shares issuable under plan (in shares)			9,025,700
Shares available for grant (in shares)		11,573,377
Options to purchase common stock \| 2022 Stock Option and Incentive Plan and 2019 Equity Incentive Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Shares issuable under plan (in shares)		34,482,330
Employee Stock \| 2022 Employee Stock Purchase Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Percentage of annual increase in shares reserved for future issuance (as a percent)	1.00%
Shares available for grant (in shares)		1,522,025
Additional shares allowable under plan (in shares)	971,350
Shares issued under ESPP (in shares)		0
Time-Based Stock Options
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Unrecognized compensation cost		$ 36.5
Unrecognized compensation costs, period of recognition (in years)		2 years 10 months 24 days
Performance-Based Stock Options
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Unrecognized compensation cost		$ 3.1

Property and Equipment, Net - Schedule of Depreciation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 1,856	$ 1,700

- Definition

The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets.

+ References + Details

Accrued Expenses and Other Current Liabilities

3 Months Ended

Mar. 31, 2026

Payables and Accruals [Abstract]

Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consisted of the following:


(in thousands)	March 31, 2026		December 31, 2025
Accrued expenses and other current liabilities
Research and clinical costs	$	2,197	$	1,997
Employee compensation and benefits	2,190		7,337

License fee	1,562		1,562

Other	2,149		1,704
Total accrued expenses and other current liabilities	$	8,098	$	12,600

Nature of the Business and Basis of Presentation	3 Months Ended
Nature of the Business and Basis of Presentation	Mar. 31, 2026
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of the Business and Basis of Presentation	Nature of the Business and Basis of Presentation Prime Medicine, Inc., together with its consolidated subsidiary, or the Company, is a biotechnology company committed to delivering a new class of differentiated one-time curative treatments. The Company is deploying Prime Editing technology, which it believes is a versatile, precise, and efficient gene editing technology. The Company was incorporated in the State of Delaware in September 2019. Its principal offices are in Cambridge, Massachusetts. Liquidity and Capital Resources Since its inception, the Company has devoted substantially all of its resources to building its Prime Editing platform and advancing development of its portfolio of programs, establishing and protecting its intellectual property, conducting research and development activities, organizing and staffing the company, business planning, raising capital and providing general and administrative support for these operations. To date, the Company has funded its operations primarily with proceeds from sales of preferred stock, from public offerings, and private placement of its common stock, and through payments from its collaboration partners. Since its inception, the Company has incurred substantial losses and, as of March 31, 2026, the Company had an accumulated deficit of $937.5 million. The Company expects to generate operating losses and negative operating cash flows for the foreseeable future. As of March 31, 2026, the Company maintains cash, cash equivalents, and short-term investments of $135.5 million. Going Concern In accordance with Accounting Standards Codification, or ASC, 205-40, Going Concern, or ASC 205-40, the Company evaluated whether there are conditions and events, considered in the aggregate, that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date on which this Quarterly Report on Form 10-Q is filed. Based on the Company's cash, cash equivalents, and short-term investments as of March 31, 2026, the Company's current and forecasted level of operations, and its forecasted cash flows, the Company’s ability to continue as a going concern is dependent upon its ability to obtain the necessary financing to meet its obligations and repay its liabilities arising from normal business operations when they come due. Management plans to provide for the Company’s capital requirements through financing or other transactions, and selling shares under the Company's “at the market offering” program. There can be no assurance that the Company will be able to raise additional capital to fund operations with terms acceptable to the Company, or at all. Because certain elements of management’s plans to mitigate the conditions that raised substantial doubt about the Company’s ability to continue as a going concern are outside of the Company’s control, including the ability to raise capital through an equity or other financing, those elements cannot be considered probable according to ASC 205-40, and therefore cannot be considered in the evaluation of mitigating factors. As a result, management has concluded that substantial doubt exists about the Company’s ability to continue as a going concern for 12 months from the date these condensed consolidated financial statements are issued. The condensed consolidated financial statements as of March 31, 2026 have been prepared under the assumption that the Company will continue as a going concern for the next 12 months and that contemplates the realization of assets and satisfaction of liabilities and commitments in the normal course of business. The Company’s ability to continue as a going concern is dependent upon its uncertain ability to obtain additional capital, reduce expenditures and/or execute on its business plan. These condensed consolidated financial statements do not include any adjustments that might result from the outcome of this uncertainty. Risks and Uncertainties The Company is subject to risks and uncertainties common to early stage companies in the biotechnology industry, including, but not limited to, completing preclinical studies and clinical trials, obtaining regulatory approval for product candidates, market acceptance of products, development by competitors of new technological innovations, dependence on key personnel, the ability to attract and retain qualified employees, reliance on third-party organizations, protection of proprietary technology, compliance with government regulations, and the ability to raise additional capital to fund operations. The Company’s product candidates currently under development will require significant additional research and development efforts, including extensive preclinical and clinical testing and regulatory approval prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel and infrastructure, and extensive compliance-reporting capabilities. Even if the Company’s development efforts are successful, it is uncertain when, if ever, the Company will realize significant revenue from product sales. The Company will need to raise additional capital to support its continuing operations and to pursue its growth strategy. Until such time as the Company can generate significant revenue from product sales, if ever, it expects to finance its operations through a combination of private and public equity offerings, debt financings, collaborations, strategic alliances, licensing, or other arrangements with third parties, or other similar transactions. The Company may be unable to raise additional capital or enter into such other agreements when needed on favorable terms or at all. The inability to raise capital as and when needed would have a negative impact on the Company’s financial condition and its ability to pursue its business strategy. The Company will need to generate significant revenue to achieve profitability, and it may never do so. Basis of Presentation The accompanying condensed consolidated financial statements reflect the operations of the Company and its wholly-owned subsidiary. Intercompany balances and transactions have been eliminated in consolidation. The accompanying condensed consolidated financial statements have been prepared in conformity with generally accepted accounting principles in the United States of America, or the U.S. GAAP. Any reference in these notes to applicable guidance is meant to refer to the authoritative U.S. GAAP as found in the ASC and Accounting Standards Updates, or ASU, of the Financial Accounting Standards Board, or FASB. The accompanying condensed consolidated financial statements of Prime Medicine, Inc. are unaudited. The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited annual consolidated financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair statement of the Company’s financial position as of March 31, 2026, the results of its operations for the three months ended March 31, 2026 and 2025, the condensed consolidated statements of stockholders’ equity for the three months ended March 31, 2026 and 2025, and its cash flows for the three months ended March 31, 2026 and 2025. The financial data and other information disclosed in these notes related to the three months ended March 31, 2026 and 2025 are also unaudited. The results for the three months ended March 31, 2026 are not necessarily indicative of results to be expected for the year ending December 31, 2026, any other interim periods, or any future year or period. The condensed consolidated balance sheet data as of December 31, 2025 was derived from our audited financial statements, but does not include all disclosures required by U.S. GAAP. These interim financial statements should be read in conjunction with the audited financial statements as of and for the year ended December 31, 2025, and notes thereto, which are included in the Company’s Annual Report on Form 10-K that was filed with the SEC on March 3, 2026.

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2024		131,160,842
Beginning balance at Dec. 31, 2024	$ 153,149	$ 2	$ 840,358	$ 1	$ (687,212)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation expense	5,681		5,681
Change in unrealized income (loss) on investments, net of tax	(16)			(16)
Net loss	(51,890)				(51,890)
Ending balance (in shares) at Mar. 31, 2025		131,160,842
Ending balance at Mar. 31, 2025	$ 106,924	$ 2	846,039	(15)	(739,102)
Beginning balance (in shares) at Dec. 31, 2025	180,514,014	180,514,014
Beginning balance at Dec. 31, 2025	$ 120,868	$ 2	1,009,138	82	(888,354)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)	101,500	101,500
Issuance of common stock upon exercise of stock options	$ 393		393
Stock-based compensation expense	4,644		4,644
Change in unrealized income (loss) on investments, net of tax	(83)			(83)
Net loss	$ (49,122)				(49,122)
Ending balance (in shares) at Mar. 31, 2026	180,615,514	180,615,514
Ending balance at Mar. 31, 2026	$ 76,700	$ 2	$ 1,014,175	$ (1)	$ (937,476)

- Definition

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

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- Definition

Amount of equity (deficit) attributable to parent. Excludes temporary equity and equity attributable to noncontrolling interest.

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+ Details

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Mar. 31, 2026	Dec. 31, 2025
Statement of Financial Position [Abstract]
Common stock, par or stated value (in dollars per share)	$ 0.00001	$ 0.00001
Common stock, shares authorized (in shares)	775,000,000	775,000,000
Common stock, shares issued (in shares)	180,615,514	180,514,014
Common stock, shares outstanding (in shares)	180,615,514	180,514,014

Summary of Significant Accounting Policies - Schedule of Segment Information (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2026 USD ($) segment	Mar. 31, 2025 USD ($)
General and administrative expenses:
Total operating expenses	$ 51,510	$ 53,846
Total other income, net	1,532	502
Net loss	$ (49,122)	(51,890)
Number of operating segments \| segment	1
Number of reportable segments \| segment	1
Reportable Segment
Segment Reporting Information [Line Items]
Total revenue	$ 856	1,454
Research and development expenses
Personnel expenses	11,053	14,800
Facility related	10,266	10,969
Research costs	7,260	11,036
General and administrative expenses:
Personnel expenses	5,532	7,156
Other segment items	17,399	9,885
Total operating expenses	51,510	53,846
Total other income, net	1,532	502
Net loss	$ (49,122)	$ (51,890)

Net Loss per Share (Tables)

3 Months Ended

Mar. 31, 2026

Earnings Per Share [Abstract]

Schedule of Earnings Per Share, Basic and Diluted

Basic and diluted net loss per common share attributable to common stockholders was calculated as follows:


	Three Months Ended March 31,
(in thousands, except share and per share amounts)		2026		2025
Numerator:



Net loss attributable to common stockholders		$	(49,122)	$	(51,890)
Denominator:
Weighted-average common shares outstanding, basic and diluted		177,096,225		130,884,490
Net loss per share attributable to common stockholders, basic and diluted		$	(0.28)	$	(0.40)

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share


	As of March 31,
	2026	2025
Anti-dilutive common stock equivalents:
Options to purchase common stock	21,692,869	15,919,190
Unvested performance-based restricted common stock awards	3,472,546	3,472,543
Total anti-dilutive common stock equivalents:	25,165,415	19,391,733

Summary of Significant Accounting Policies (Policies)	3 Months Ended
Summary of Significant Accounting Policies (Policies)	Mar. 31, 2026
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying condensed consolidated financial statements reflect the operations of the Company and its wholly-owned subsidiary. Intercompany balances and transactions have been eliminated in consolidation. The accompanying condensed consolidated financial statements have been prepared in conformity with generally accepted accounting principles in the United States of America, or the U.S. GAAP. Any reference in these notes to applicable guidance is meant to refer to the authoritative U.S. GAAP as found in the ASC and Accounting Standards Updates, or ASU, of the Financial Accounting Standards Board, or FASB. The accompanying condensed consolidated financial statements of Prime Medicine, Inc. are unaudited. The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited annual consolidated financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair statement of the Company’s financial position as of March 31, 2026, the results of its operations for the three months ended March 31, 2026 and 2025, the condensed consolidated statements of stockholders’ equity for the three months ended March 31, 2026 and 2025, and its cash flows for the three months ended March 31, 2026 and 2025. The financial data and other information disclosed in these notes related to the three months ended March 31, 2026 and 2025 are also unaudited. The results for the three months ended March 31, 2026 are not necessarily indicative of results to be expected for the year ending December 31, 2026, any other interim periods, or any future year or period. The condensed consolidated balance sheet data as of December 31, 2025 was derived from our audited financial statements, but does not include all disclosures required by U.S. GAAP. These interim financial statements should be read in conjunction with the audited financial statements as of and for the year ended December 31, 2025, and notes thereto, which are included in the Company’s Annual Report on Form 10-K that was filed with the SEC on March 3, 2026.
Use of Estimates	Use of Estimates The preparation of the Company’s condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements and the reported amounts of revenues and expenses during the reporting periods. Significant estimates and assumptions reflected within these condensed consolidated financial statements include, but are not limited to, the valuation of the Company’s common stock and stock-based awards. The Company bases its estimates on historical experience, known trends and other market-specific or other relevant factors that it believes to be reasonable under the circumstances. On an ongoing basis, management evaluates its estimates, as there are changes in circumstances, facts and experience. Actual results may differ materially from those estimates or assumptions.
Segment Information	Segment Information Under ASC 280, Segment Reporting, operating segment is a component of a public entity that 1) engages in business activities from which it may recognize revenues and incur expenses, 2) its operating results are regularly reviewed by the entity’s chief operating decision maker, or CODM, to make decisions about resource allocation or performance assessment, and 3) its discrete financial information is available. The Company operates and manages its business as a single segment for the purposes of assessing performance and making operating decisions. Our chief executive officer, who is the CODM, manages and allocates resources to the operations of our company on a total company basis by assessing the overall level of resources available and how to best deploy these resources across functions and research and development projects that are in line with our long-term company-wide strategic goals. In making these decisions, the CODM uses consolidated financial information for purposes of evaluating performance, forecasting future period financial results, allocating resources and setting incentive targets. The CODM performs this assessment based on the Company’s consolidated net loss. Through this analysis, the CODM assesses performance by comparing actual net loss verses the budget, and then decides how to allocate resources to invest in the Company’s research and development programs. The measure of segment assets is reported on the condensed consolidated balance sheets as total assets.
Recently Issued Accounting Pronouncements Not Yet Adopted	Recently Issued Accounting Pronouncements Not Yet Adopted In November 2024, the FASB issued ASU 2024-03, Disaggregation of Income Statement Expenses, which requires more detailed information about specified categories of expenses included in certain expense captions presented on the face of the income statement. This ASU is effective for fiscal years beginning after December 15, 2026, and for interim periods within fiscal years beginning after December 15, 2027. Early adoption is permitted. The amendments may be applied either (1) prospectively to financial statements issued for reporting periods after the effective date of this ASU or (2) retrospectively to all prior periods presented in the financial statements. The Company is currently evaluating the impact this ASU will have on its disclosures. In September 2025, the FASB issued ASU No. 2025-07, Derivatives and Hedging (Topic 815) and Revenue from Contracts with Customers (Topic 606): Derivatives Scope Refinements and Scope Clarification for Share-Based Noncash Consideration from a Customer in a Revenue Contract. This update introduces a scope exception to derivative accounting for certain contracts with underlyings tied to operations or activities specific to one of the parties. Additionally, the update clarifies that share-based noncash consideration received from a customer should be accounted for under Topic 606 until the right to receive or retain the consideration becomes unconditional. The amendments can be applied prospectively or modified retrospectively and are effective for annual and interim periods beginning after December 15, 2026. The Company is currently evaluating the impact to the Company’s consolidated financial statements. In December 2025, the FASB issued ASU No. 2025-11, Interim Reporting (Topic 270): Narrow-scope Improvements, which improves the navigability of interim reporting guidance. The ASU also addresses the form and content of financial statements, adds lists to ASC 270 of the interim disclosures required by all other codification topics, and establishes a principle under which an entity must “disclose events since the end of the last annual reporting period that have a material impact on the entity.” This ASU is effective for interim reporting periods within annual reporting periods beginning after December 15, 2027, with early adoption permitted. The Company is currently evaluating the impact this ASU will have on its interim disclosures. Other accounting standards that have been issued by the FASB or other standards-setting bodies that do not require adoption until a future date are not expected to have a material impact on the Company’s financial statements upon adoption

- Definition

Disclosure of accounting policy for segment reporting.

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+ Details

Nature of the Business and Basis of Presentation (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accumulated deficit	$ 937,476	$ 888,354
Cash, cash equivalents, and investments	$ 135,500

- Definition

Amount of accumulated undistributed earnings (deficit).

+ References + Details

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Cash flows used in operating activities:
Net loss	$ (49,122)	$ (51,890)
Adjustments to reconcile net loss to net cash used in operating activities
Stock-based compensation expense	4,644	5,681
Non cash lease expense	2,843	2,413
Depreciation expense	1,856	1,700
Amortization of premiums and discount on short-term investments	(431)	(164)
Change in fair value of short-term investment — related party	0	1,056
Changes in operating assets and liabilities:
Collaboration receivable — related party	0	(17)
Prepaid expenses and other current assets	1,221	(789)
Accounts payable	3,552	1,884
Accrued expenses and other current liabilities	(4,502)	(6,655)
Deferred revenue — related party	(856)	(1,438)
Lease liabilities	(1,915)	(638)
Net cash used in operating activities	(42,710)	(48,857)
Cash flows provided by (used in) investing activities:
Maturities of investments	50,888	3,000
Purchases of investments	(7,283)	(48,320)
Purchases of property and equipment	(214)	(2,422)
Net cash provided by (used in) investing activities	43,391	(47,742)
Cash flows provided by financing activities:
Net proceeds from stock option exercises	393	0
Proceeds from research and development funding liability	0	6,000
Net cash provided by financing activities	393	6,000
Net change in cash, cash equivalents, and restricted cash	1,074	(90,599)
Cash, cash equivalents, and restricted cash at beginning of period	76,723	196,538
Cash, cash equivalents, and restricted cash at end of period	77,797	105,939
Reconciliation of cash, cash equivalents and restricted cash:
Cash, cash equivalents, and restricted cash at end of period	77,797	105,939
Less: restricted cash	13,691	14,062
Total cash, and cash equivalents	64,106	91,877
Supplemental cash flow information:
Right-of-use assets obtained in exchange for new operating lease liabilities	0	83,757
Decrease in right-of-use assets due to lease termination	0	3,120
Supplemental disclosure of non-cash investing and financing activities:
Purchases of property and equipment included in accounts payable and accrued expenses	$ 0	$ 985

Property and Equipment, Net - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 41,106	$ 41,006
Less: Accumulated depreciation	(22,290)	(20,434)
Total property and equipment, net	18,816	20,572
Laboratory equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	30,019	29,744
Leasehold improvement
Property, Plant and Equipment [Line Items]
Total property and equipment	7,911	7,911
Furniture and fixture
Property, Plant and Equipment [Line Items]
Total property and equipment	1,864	1,864
Computer hardware and software
Property, Plant and Equipment [Line Items]
Total property and equipment	1,122	1,122
Construction in progress
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 190	$ 365

Property and Equipment, Net (Tables)

3 Months Ended

Mar. 31, 2026

Property, Plant and Equipment [Abstract]

Schedule of Property and Equipment, Net and Depreciation Expense

Property and equipment, net consisted of the following:


(in thousands)	March 31, 2026		December 31, 2025
Property and equipment:
Laboratory equipment	$	30,019	$	29,744
Leasehold improvement	7,911		7,911
Furniture and fixture	1,864		1,864
Computer hardware and software	1,122		1,122
Construction in progress	190		365
Total property and equipment	41,106		41,006
Less: Accumulated depreciation	(22,290)		(20,434)
Total property and equipment, net	$	18,816	$	20,572

Depreciation expense related to property and equipment is as follows:


	Three Months Ended March 31,
(in thousands)		2026		2025
Depreciation expense		$	1,856	$	1,700