0001193125-26-210358 | 10-Q | XBRL Viewer | Monte Rosa Therapeutics INC

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Leases - Components of Lease Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Leases [Abstract]
Operating lease expense	$ 1,638	$ 1,634
Variable lease expense	758	852
Total lease expense	$ 2,396	$ 2,486

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Mar. 31, 2026	Mar. 31, 2025	Dec. 31, 2025
Pay vs Performance Disclosure
Net Income (Loss)	$ (44,503)	$ 46,885	$ (38,600)

- Definition

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

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+ Details

Condensed Consolidated Statements of Cash Flows (unaudited) (Parenthetical) $ in Thousands	3 Months Ended
	Mar. 31, 2026 USD ($)
Statement of Cash Flows [Abstract]
Underwriter's discount on underwritten public offering cost	$ 20,700

Net (loss) income per common share - Schedule of Anti-Dilutive Shares Excluded from Earnings Per Share Calculation (Details) - shares	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Stock Options to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of EPS	15,989,324	14,422,833
Restricted stock units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of EPS	1,149,012	815,941

Leases - Summarizes lease expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total lease expense	$ 2,396	$ 2,486
Research and development
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total lease expense	2,244	2,078
General and Administrative
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total lease expense	$ 152	$ 408

Marketable securities

3 Months Ended

Mar. 31, 2026

Investments, Debt and Equity Securities [Abstract]

Marketable Securities

4. Marketable securities

Marketable securities as of March 31, 2026 consisted of the following (in thousands):


	Amortized		Unrealized		Unrealized			Fair
	Cost		Gains		Losses			Value
Description
Corporate debt securities	$	268,690	$	10	$	(501	)		268,199
U.S Treasury securities		238,480		7		(325	)		238,162
Total	$	507,170	$	17	$	(826	)	$	506,361

Marketable securities as of December 31, 2025 consisted of the following (in thousands):


	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
Description
Corporate debt securities	$	99,543	$	53	$	—		99,596
U.S Treasury securities		147,514		111		—		147,625
Total	$	247,057	$	164	$	—	$	247,221

As of March 31, 2026, unrealized gain and losses on marketable securities are recorded in accumulated other comprehensive loss in equity on the accompanying condensed consolidated balance sheet. There were no realized gains or losses recognized on the sale or maturity of marketable securities for the three months ended March 31, 2026 and 2025 and, as a result, the Company did not reclassify any amounts out of accumulated other comprehensive loss for the same periods.

The Company holds debt securities of companies with high credit quality and has determined that there was no material change in the credit risk of any of its debt securities. The Company also believes that it will be able to collect both principal and interest amounts due to it at maturity.

Segment data

3 Months Ended

Mar. 31, 2026

Segment Reporting [Abstract]

Segment data

15. Segment data

The Company defines its segments based on the way in which internally reported financial information is regularly reviewed by the chief operating decision maker, or CODM, to analyze financial performance, make decisions, and allocate resources. The Company manages its operations as a single operating and reportable segment committed to developing a portfolio of novel and proprietary MGDs. MGDs are small molecule drugs that employ the body’s natural protein destruction mechanisms to selectively degrade therapeutically-relevant proteins. As the internal reporting is based on the consolidated results, the Company has identified one operating and reportable segment. The CODM uses net (loss) income in the budget and forecasting process and considers budget-to-actual variances on a quarterly basis when making decisions about the allocation of operating and capital resources. The measure of the operating segment assets is reported on the condensed consolidated balance sheet as total assets.

The accounting policies used in the segment reporting are the same as those described in the summary of significant accounting policies. (See Note 2 in our annual report on Form 10-K for the year ended December 31, 2025.) The Company’s CODM is the Chief Executive Officer.

The Company's reportable segment net revenues and (loss) income for the three months ended March 31, 2026 and 2025 consisted of the following (in thousands):


	Three months ended March 31,
	2026			2025
Revenue:
Collaboration revenue	$	4,210		$	84,929
Operating expense:
Research and development:
External research and development expenses:
MRT-2359		2,381			1,945
MRT-6160		11			3,981
MRT-8102		6,781			1,882
CCNE1		1,703			762
Other development and discovery programs		9,589			4,040
Personnel expense		13,493			11,352
Overhead and administrative expense		10,111			8,228
General and administrative expenses:
Personnel expense		6,420			5,679
Professional services		2,143			1,478
Facility costs and other expense		1,612			1,546
Interest and other income, net		5,583			3,671
Income tax provision		(52	)		(822	)
Net (loss) income	$	(44,503	)	$	46,885

Other development and discovery expenses are related to the development of our QuEENTM discovery engine and our disclosed and undisclosed programs, including CDK2. The Company's tangible assets are held in the U.S. and Switzerland with 32% and 29% of the assets held in Switzerland as of March 31, 2026 and December 31, 2025, respectively. All of the Company's collaboration revenue was generated in Switzerland during each of the three months ended March 31, 2026 and 2025.

- Definition

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

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+ Details

Accrued expenses and other current liabilities (Tables)

3 Months Ended

Mar. 31, 2026

Accounts Payable and Accrued Liabilities, Current [Abstract]

Schedule Of Accrued Expenses And Other Current Liabilities

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


	March 31,		December 31,
	2026		2025
Accrued compensation and benefits	$	5,047	$	9,998
Accrued research and development		16,641		15,118
Accrued fixed asset purchase		2,670		57
Other		1,236		1,521
Total accrued expenses and other current liabilities	$	25,594	$	26,694

Property and equipment, net - Schedule of Property, Plant and Equipment (Detail) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Property Plant And Equipment [Line Items]
Total property and equipment, at cost	$ 58,053	$ 53,599
Less: accumulated depreciation	(29,644)	(27,613)
Property and equipment, net	28,409	25,986
Laboratory Equipment
Property Plant And Equipment [Line Items]
Total property and equipment, at cost	28,024	27,022
Computer Hardware and Software
Property Plant And Equipment [Line Items]
Total property and equipment, at cost	1,388	1,388
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Total property and equipment, at cost	1,402	1,402
Leasehold Improvements
Property Plant And Equipment [Line Items]
Total property and equipment, at cost	23,794	23,669
Construction in process
Property Plant And Equipment [Line Items]
Total property and equipment, at cost	$ 3,445	$ 118

Net (loss) income per common 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) earnings per share are as follows (in thousands except share and per share amounts):


	Three months ended March 31,
	2026			2025
Net (loss) income	$	(44,503	)	$	46,885
Basic weighted average shares outstanding		99,883,878			82,148,719
Effect of potentially dilutive securities:
Stock options to purchase common stock		—			729,311
Restricted stock units		—			78,393
Diluted weighted average shares outstanding		99,883,878			82,956,423

Basic net (loss) earnings per share	$	(0.45	)	$	0.57
Diluted net (loss) earnings per share	$	(0.45	)	$	0.57

Schedule of Antidilutive Securities Excluded from Earnings Per Share Calculation

The following outstanding potentially dilutive securities have been excluded from the calculation of diluted net (loss) earnings per common share, as their effect is anti-dilutive:


	Three months ended March 31,
	2026		2025
Stock options to purchase common stock		15,989,324		14,422,833
Restricted stock units		1,149,012		815,941

Fair Value Measurements - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Measure at fair value, transfers among Level 1, Level 2 or Level 3	$ 0	$ 0

Segment data (Tables)

3 Months Ended

Mar. 31, 2026

Segment Reporting [Abstract]

Schedule of Company's reportable segment net revenues and loss

The Company's reportable segment net revenues and (loss) income for the three months ended March 31, 2026 and 2025 consisted of the following (in thousands):


	Three months ended March 31,
	2026			2025
Revenue:
Collaboration revenue	$	4,210		$	84,929
Operating expense:
Research and development:
External research and development expenses:
MRT-2359		2,381			1,945
MRT-6160		11			3,981
MRT-8102		6,781			1,882
CCNE1		1,703			762
Other development and discovery programs		9,589			4,040
Personnel expense		13,493			11,352
Overhead and administrative expense		10,111			8,228
General and administrative expenses:
Personnel expense		6,420			5,679
Professional services		2,143			1,478
Facility costs and other expense		1,612			1,546
Interest and other income, net		5,583			3,671
Income tax provision		(52	)		(822	)
Net (loss) income	$	(44,503	)	$	46,885

Employee retirement plans (Tables)

3 Months Ended

Mar. 31, 2026

Retirement Benefits [Abstract]

Schedule of pension expense incurred

The following table summarizes pension expense incurred (in thousands):


	Three months ended March 31,
	2026		2025
Pension expense	$	350	$	388

Schedule of defined contribution expense incurred

The following table summarizes defined contribution expenses incurred (in thousands):


	Three months ended March 31,
	2026		2025
Defined contribution expense	$	478	$	409

Insider Trading Arrangements

3 Months Ended

Mar. 31, 2026

Trading Arrangements, by Individual

Material Terms of Trading Arrangement

Rule 10b5-1 Trading Plans

During the fiscal quarter ended on March 31, 2026, none of our directors and officers (as defined in Rule 16a-1(f) under the Exchange Act) adopted, modified or terminated a “Rule 10b5-1 trading arrangement” or “non-Rule 10b5-1 trading arrangement,” as those terms are defined in Item 408(a) of Regulation S-K.


Name and Title	Action	Action Date	Duration of Trading Arrangements	Rule 10b5-1 Trading Arrangement? (Y/N)*	Aggregate Number of Securities Subject to Trading Arrangement
Jennifer Champoux Chief Operating Officer	Adopt	February 19, 2026	May 22, 2026 - December 15, 2026	Y	Up to 30,456 shares of common stock underlying stock options to be sold
Sharon Townson Chief Scientific Officer	Adopt	February 27, 2026	May 29 2026 - January 29, 2027	Y	Up to 50,000 shares of common stock underlying stock options to be sold
Filip Janku Chief Medical Officer	Adopt	March 4, 2026	June 3, 2026 - February 5, 2027	Y	Up to 74,304 shares of common stock to be sold, consisting of up to 68,459 shares underlying stock options and up to 5,485 shares underlying restricted stock units

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

Rule 10b5-1 Arrangement Modified

false

Non-Rule 10b5-1 Arrangement Modified

false

Jennifer Champoux [Member]

Trading Arrangements, by Individual

Name

Jennifer Champoux

Title

Chief Operating Officer

Rule 10b5-1 Arrangement Adopted

true

Adoption Date

February 19, 2026

Arrangement Duration

208 days

Aggregate Available

30,456

Sharon Townson [Member]

Trading Arrangements, by Individual

Name

Sharon Townson

Title

Chief Scientific Officer

Rule 10b5-1 Arrangement Adopted

true

February 27, 2026

246 days

50,000

Trading Arrangements, by Individual

Name

Filip Janku

Title

Chief Medical Officer

Rule 10b5-1 Arrangement Adopted

true

Adoption Date

March 4, 2026

Arrangement Duration

248 days

Aggregate Available

74,304

Collaboration and license agreements (Tables)

3 Months Ended

Mar. 31, 2026

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Summary of deferred revenue amounts allocated to performance obligations

The following table summarizes the deferred revenue amounts allocated to the Roche Agreement performance obligations (in thousands):


	March 31,		December 31,
	2026		2025
Roche Agreement performance obligations
Research and development of initial targets	$	12,775	$	14,140
Research and development for replacement targets		8,217		8,517
Total Roche Agreement deferred revenue	$	20,992	$	22,657

Schedule of Transaction Price Allocated To Performance Obligations [Table Text Block]

The following table summarizes the unearned amount of the 2025 Novartis Agreement transaction price allocated to the performance obligations (in thousands):


	March 31,		December 31,
	2026		2025
2025 Novartis Agreement performance obligations
License and research services for named immunology target	$	6,814	$	7,019
Research services to support immunology license options		83,357		85,698
Material right - first immunology license option		49,091		49,091
Material right - second immunology license option		36,439		36,439
Total unearned amount of transaction price	$	175,701	$	178,247

Marketable securities (Additional Information) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Investments, Debt and Equity Securities [Abstract]
Debt securities available for realized gain or loss	$ 0	$ 0

Leases (Additional Information) (Details)		3 Months Ended
Leases (Additional Information) (Details)	Dec. 14, 2021 USD ($) ft²	Mar. 31, 2026 USD ($)	Mar. 31, 2025 USD ($)	Apr. 30, 2023 ft²	Mar. 31, 2021 ft²
Lessee, Lease, Description [Line Items]
Finance Lease		$ 0
Right-of-use assets and operating lease liabilities		(434,000)	$ (283,000)
Amortization of ROU assets		643,000	$ 574,000
Hochbergerstrasse [Member]
Lessee, Lease, Description [Line Items]
Land Subject to Ground Leases \| ft²					21,422
Hochbergerstrasse [Member] \| Maximum [Member]
Lessee, Lease, Description [Line Items]
Land Subject to Ground Leases \| ft²				44,685
Hochbergerstrasse [Member] \| Minimum [Member]
Lessee, Lease, Description [Line Items]
Land Subject to Ground Leases \| ft²				21,422
Harrison Street [Member]
Lessee, Lease, Description [Line Items]
Land Subject to Ground Leases \| ft²	63,327
Lease commencement date	Apr. 01, 2022
Initial lease term	128 months
Renewal term	5 years
Lease annual base rent per square foot	$ 95
Increase in annual base rent (Percentage)	3.00%
Klybeckstrasse Lease [Member]
Lessee, Lease, Description [Line Items]
Right-of-use assets and operating lease liabilities		$ 1,000,000

Property and equipment, net (Tables)

3 Months Ended

Mar. 31, 2026

Property, Plant and Equipment [Abstract]

Schedule of Property and Equipment

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


	March 31, 2026			December 31, 2025
Laboratory equipment	$	28,024		$	27,022
Computer hardware and software		1,388			1,388
Furniture and fixtures		1,402			1,402
Leasehold improvements		23,794			23,669
Construction in process		3,445			118
Total property and equipment, at cost	$	58,053		$	53,599
Less: accumulated depreciation		(29,644	)		(27,613	)
Property and equipment, net	$	28,409		$	25,986

Net (loss) income per common share - Schedule of Earnings Per Share, Basic and Diluted (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Dec. 31, 2025
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Net (loss) income	$ (44,503)	$ 46,885	$ (38,600)
Basic weighted average shares outstanding	99,883,878	82,148,719
Effect of potentially dilutive securities:
Diluted weighted average shares outstanding	99,883,878	82,956,423
Basic net (loss) earnings per share	$ (0.45)	$ 0.57
Diluted net (loss) earnings per share	$ (0.45)	$ 0.57
Options to purchase common stock
Effect of potentially dilutive securities:
Potentially dilutive securities	0	729,311
Restricted stock units
Effect of potentially dilutive securities:
Potentially dilutive securities	0	78,393

Employee retirement plans - Schedule of Defined Contribution Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Retirement Benefits [Abstract]
Defined contribution expense	$ 478	$ 409

Employee Retirement Plans

3 Months Ended

Mar. 31, 2026

Retirement Benefits [Abstract]

Employee Retirement Plans

14. Employee retirement plans

The Company, in compliance with Swiss Law, is contracted with the AXA Leben AG, or AXA, for the provision of pension benefits in a defined benefit plan. All benefits are organized in a semi-autonomous collective foundation within the framework of the contract with AXA. Insurance benefits due are paid directly to the entitled persons by AXA in the name of and for the account of the collective foundation. The pension plan is financed by contributions of both employees and the Company. The contract between the Company and the collective foundation can be terminated by either side. In the event of a termination, the Company would have an obligation to find alternative pension arrangements for its employees. Because there is no guarantee that the employee pension arrangements would be continued under the same conditions, there is a risk, albeit remote, that a pension obligation may fall on the Company. The pension assets are pooled for all affiliated companies; the investment of assets is done by the governing bodies of the collective foundation.

The following table summarizes pension expense incurred (in thousands):


	Three months ended March 31,
	2026		2025
Pension expense	$	350	$	388

In February 2021, the Company adopted a defined contribution plan intended to qualify under Section 401(k) of the Internal Revenue Code covering all eligible U.S. based employees of the Company. All employees are eligible to become participants of the plan immediately upon hire. Each active employee may elect, voluntarily, to contribute a percentage of

their compensation to the plan each year, subject to certain limitations. The Company reserves the right, but is not obligated, to make additional contributions to this plan. The Company makes safe-harbor match contributions of 100% of the first 4% of each participant’s eligible compensation. In January 2024, the Company adopted a defined contribution supplemental pension plan for eligible Swiss based employees defined by Swiss Law Art.1e BVV 2, or the 1e Plan. Employees earning above a defined threshold are eligible and automatically enrolled in the 1e Plan and required contributions are determined by age and salary under Swiss Law. The Company and the employee share the costs of the 1e Plan.

The following table summarizes defined contribution expenses incurred (in thousands):


	Three months ended March 31,
	2026		2025
Defined contribution expense	$	478	$	409

- Definition

The entire disclosure for retirement benefits.

+ References

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

Fair Value Measurements - Summary of Financial Assets Liabilities Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Current assets
Total assets measured at fair value	$ 678,091	$ 388,940
Level 1 [Member]
Current assets
Total assets measured at fair value	159,238	129,279
Level 2 [Member]
Current assets
Total assets measured at fair value	518,853	259,661
Level 3 [Member]
Current assets
Total assets measured at fair value	0	0
Money Market Funds [Member]
Current assets
Total assets measured at fair value	159,238	129,279
Money Market Funds [Member] \| Level 1 [Member]
Current assets
Total assets measured at fair value	159,238	129,279
Money Market Funds [Member] \| Level 2 [Member]
Current assets
Total assets measured at fair value	0	0
Money Market Funds [Member] \| Level 3 [Member]
Current assets
Total assets measured at fair value	0	0
Pension Plan Assets [Member]
Current assets
Total assets measured at fair value	12,492	12,440
Pension Plan Assets [Member] \| Level 1 [Member]
Current assets
Total assets measured at fair value	0	0
Pension Plan Assets [Member] \| Level 2 [Member]
Current assets
Total assets measured at fair value	12,492	12,440
Pension Plan Assets [Member] \| Level 3 [Member]
Current assets
Total assets measured at fair value	0	0
Corporate Debt Securities Member
Current assets
Total assets measured at fair value	268,199	99,596
Corporate Debt Securities Member \| Level 1 [Member]
Current assets
Total assets measured at fair value	0	0
Corporate Debt Securities Member \| Level 2 [Member]
Current assets
Total assets measured at fair value	268,199	99,596
Corporate Debt Securities Member \| Level 3 [Member]
Current assets
Total assets measured at fair value	0	0
US Treasury Securities Member
Current assets
Total assets measured at fair value	238,162	147,625
US Treasury Securities Member \| Level 1 [Member]
Current assets
Total assets measured at fair value	0	0
US Treasury Securities Member \| Level 2 [Member]
Current assets
Total assets measured at fair value	238,162	147,625
US Treasury Securities Member \| Level 3 [Member]
Current assets
Total assets measured at fair value	$ 0	$ 0

Employee Retirement Plans - Additional Information (Details)	3 Months Ended
	Mar. 31, 2026
Retirement Benefits [Abstract]
Percentage of company's matching contribution with respect to each participant's contribution	4.00%
Company matching contributions to maximum employees eligible compensation	100.00%

Leases - Schedule of Supplemental Cash Flow Information Related To Leases (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Leases [Abstract]
Cash paid for amounts included in the measurement of lease liabilities	$ 1,998	$ 908
Amortization of ROU assets	$ 643	$ 574

- Definition

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets.

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-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147476148/220-40-50-6

+ Details

Leases

3 Months Ended

Mar. 31, 2026

Leases [Abstract]

Leases

7. Leases

The Company determines if an arrangement is a lease at inception. Operating leases are included in operating lease right-of-use, or ROU, assets and operating lease liabilities in the condensed consolidated balance sheets. The Company has no finance leases as of March 31, 2026.

ROU assets represent the right to use an underlying asset for the lease term and lease liabilities represent the obligation to make lease payments arising from the lease. Operating lease ROU assets and liabilities are recognized at commencement date based on the present value of lease payments over the lease term. As the Company’s leases do not provide an implicit rate, management estimated the incremental borrowing rate based on the rate of interest the Company would have to pay to borrow a similar amount on a collateralized basis over a similar term. The Company uses its incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments.

Klybeckstrasse Lease

In March 2021, the Company entered into an operating lease agreement, or the Klybeckstrasse Lease, for office and laboratory space with Wincasa AG, or the Basel Landlord, that occupies approximately 21,422 square feet located at Klybeckstrasse 191, 4057 Basel, Basel-City, Switzerland. In April 2023, the Company and the Basel Landlord amended the Klybeckstrasse Lease which increased the office and laboratory space square footage from 21,422 square feet to 44,685 square feet and extended the term of the lease through June 30, 2027. In March 2026, the Company and the Basel Landlord again amended the Klybeckstrasse Lease, the Second Amendment, to extend the term of the lease through June 30, 2028. The Second Amendment was accounted for as a lease modification and resulted in increases to the related ROU asset and operating lease liability of $1.0 million.

Harrison Avenue Lease

In December 2021, the Company entered into a non-cancelable lease agreement, or the Harrison Avenue Lease, for 63,327 square feet of office and laboratory space to support its expanding operations. The term of the lease commenced on April 1, 2022 and the Company’s obligation to pay rent began on December 21, 2022. The initial term of the lease is 128 months following the commencement date, at which point the Company has the option to extend the lease an additional 5 years. The Company has determined that it is not reasonably certain to exercise the option to extend the lease and has not included the extension period in the lease term. The annual base rent under the Harrison Avenue Lease is $95 per square foot for the first year, which is subject to scheduled annual increases of 3%, plus certain costs, operating expenses and property management fees.

The components of lease expense for the three months ended March 31, 2026 and 2025 are as follows (in thousands):


	Three months ended March 31,
	2026		2025
Operating lease expense	$	1,638	$	1,634
Variable lease expense		758		852
Total lease expense	$	2,396	$	2,486

The variable lease expenses generally include common area maintenance and property taxes.

The following table summarizes lease expense incurred (in thousands):


	Three months ended March 31,
	2026		2025
Research and development	$	2,244	$	2,078
General and administrative		152		408
Total lease expense	$	2,396	$	2,486

Short-term lease costs for the three months ended March 31, 2026 and 2025 were immaterial.

The weighted average remaining lease term and discount rate related to the Company's leases are as follows:


	March 31, 2026			December 31, 2025
Weighted average remaining lease term (years)		6.5			6.8
Weighted average discount rate		9.8	%		9.9	%

Supplemental cash flow information and other information relating to the Company's leases for the three months ended March 31, 2026 and 2025 is as follows (in thousands):


	Three months ended March 31,
	2026		2025
Cash paid for amounts included in the measurement of lease liabilities	$	1,998	$	908
Amortization of ROU assets	$	643	$	574

Future minimum lease payments under non-cancelable leases as of March 31, 2026 for each of the years ending December 31 are as follows (in thousands):


Undiscounted lease payments
2026	$	5,992
2027		8,208
2028		7,894
2029		7,575
2030		7,802
Thereafter		15,624
Total undiscounted minimum lease payments		53,095
Less: Imputed interest		(14,031	)
Total operating lease liability	$	39,064

Property and equipment, net - Summarized Depreciation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 2,029	$ 2,048

Stock-Based Compensation - Schedule of Stock Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 5,949	$ 5,298
Research and Development [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	3,374	3,135
General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 2,575	$ 2,163

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (f)(2)
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-Paragraph 1D
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-URI https://asc.fasb.org/1943274/2147480483/718-10-35-1D

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org/1943274/2147480483/718-10-35-3

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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Reference 18: http://www.xbrl.org/2003/role/disclosureRef
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Reference 19: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Collaboration and License Agreements (Additional Information) (Details) - USD ($) $ in Thousands			1 Months Ended	3 Months Ended		9 Months Ended	12 Months Ended
	Mar. 31, 2026	Sep. 30, 2025	Nov. 30, 2023	Mar. 31, 2026	Mar. 31, 2025	Sep. 30, 2025	Dec. 31, 2024	Dec. 31, 2025
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration Revenue				$ 4,210	$ 84,929
Deferred Revenue	$ 103,635			103,635				$ 111,332
Liabilities Current	71,036			71,036				64,212
Milestone Payments				$ 60,000
Research and Development Target Months				The Company expects that the remaining deferred revenue for the initial targets will be recognized within 18 months. The Company expects that deferred revenue related to replacement targets will be recognized within 30 months. Due to the uncertain nature of the research and development being performed by the Company, it may take longer than anticipated to recognize revenue related to the performance obligations for the initial and replacement targets. Any amounts remaining in deferred revenue will be recognized at the conclusion of the Roche Agreement in October 2028.As of March 31, 2026, potential research, development and regulatory milestone payments that the Company is eligible to receive were excluded from the transaction price as they were fully constrained by uncertain events. The Company will reevaluate the transaction price at the end of each reporting period and as uncertain events are resolved or other changes in circumstances occur, and if necessary, the Company will adjust its estimate of the transaction price. Any additions to the transaction price would be reflected in the period as a cumulative revenue catch-up based on the ratio of costs incurred to the total estimated costs expected applied to the revised transaction price. Sales-based royalties and milestone payments, which predominantly relate to the license, will be recognized if and when the related sales occur.
Collaboration and License Agreement [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Non-Refundable Upfront Payment			$ 50,000
Collaboration Revenue				$ 48,000
Liabilities Current	10,500			10,500
Liabilities Noncurrent	10,500			10,500
One Time Upfront Payment				21,000
Collaboration and License Agreement [Member] \| Research and Development [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Non-Refundable Upfront Payment				16,000
Collaboration and License Agreement [Member] \| Collaboration Revenue [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Pre-clinical milestones				3,000
Collaboration and License Agreement [Member] \| Minimum [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Potential clinical, commercial and sales milestones			2,000,000
Collaboration and License Agreement [Member] \| Maximum [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Pre-clinical milestones			$ 172,000
Roche Agreement [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Deferred Revenue	20,992			20,992				$ 22,657
Novartis License Agreement [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration Revenue				180,000
Total transaction amount				180,000
2024 Novartis License Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Non-Refundable Upfront Payment							$ 150,000
Maximum Amount To Be Received In Total							$ 2,100,000
Collaboration Revenue		$ 150,000
Incremental cost reimbursements recognized as collaboration revenue						$ 1,200
Profits And Losses Percentage							30.00%
Total Transaction Upfront Price							$ 150,000
2024 Novartis License Agreement \| Minimum [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Potential clinical, commercial and sales milestones							$ 1,500,000
2025 Novartis License Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Non-Refundable Upfront Payment						120,000
Potential pre-clinical, clinical, commercial, and sales milestones						5,400,000
Collaboration Revenue	4,300
Deferred Revenue	115,700			115,700
Liabilities Current	22,500			22,500
Liabilities Noncurrent	$ 93,200			93,200
Program and Option Exercise Payments		$ 180,000				180,000
One Time Upfront Payment				$ 120,000
Collaboration funds receivable						60,000
Milestone Payments						2,200,000
Potential sales milestones payment						$ 3,200,000
Research and Development Target Months				The Company expects that that the remaining deferred revenue for the license and research services for a named immunology target and research services for two additional immunology targets to be recognized within 54 months. The deferred revenue related to material right license options will be recognized when Novartis exercises such options rights or at the expiration of the option rights. Due to the uncertain nature of the research and development being performed by the Company, it may take longer than anticipated to recognize revenue related to the performance obligations related to research services.
2025 Novartis License Agreement \| Maintenance [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
One Time Upfront Payment				$ 60,000

Stock-Based Compensation - Schedule of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2026	Dec. 31, 2025
Share-Based Payment Arrangement [Abstract]
Number of options, beginning balance	14,064,599
Number of options, granted	2,569,325
Number of options, exercised	(574,839)
Number of shares, forfeited	(69,761)
Number of options, ending balance	15,989,324	14,064,599
Number of options, vested or expected to vest	15,989,324
Number of options, exercisable	8,921,922
Weighted average exercise price, beginning balance	$ 7.74
Weighted average exercise price, granted	15.46
Weighted average exercise price, exercised	7.87
Weighted average exercise price, forfeited	8.1
Weighted average exercise price, ending balance	8.98	$ 7.74
Weighted average exercise price, vested or expected to vest	8.98
Weighted average exercise price, exercisable	$ 8.32
Weighted average remaining contractual term (years), balance	7 years 6 months	7 years 2 months 12 days
Weighted average remaining contractual term (years), vested or expected to vest	7 years 6 months
Weighted average remaining contractual term (years), exercisable	6 years 4 months 24 days
Aggregate intrinsic value, beginning balance	$ 115,245
Aggregate intrinsic value, ending balance	122,640	$ 115,245
Aggregate intrinsic value, vested or expected to vest	122,640
Aggregate intrinsic value, exercisable	$ 75,433

Collaboration and license agreements - Summarizes the deferred revenue amounts allocated to performance obligations (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total Roche Agreement deferred revenue	$ 103,635	$ 111,332
Roche Agreement [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total Roche Agreement deferred revenue	20,992	22,657
Roche Agreement [Member] \| Research and Development of Intial Targets [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total Roche Agreement deferred revenue	12,775	14,140
Roche Agreement [Member] \| Research and Development for Replacement Targets [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total Roche Agreement deferred revenue	$ 8,217	$ 8,517

Accrued expenses and other current liabilities

3 Months Ended

Mar. 31, 2026

Accounts Payable and Accrued Liabilities, Current [Abstract]

Accrued expenses and other current liabilities

6. Accrued expenses and other current liabilities

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


	March 31,		December 31,
	2026		2025
Accrued compensation and benefits	$	5,047	$	9,998
Accrued research and development		16,641		15,118
Accrued fixed asset purchase		2,670		57
Other		1,236		1,521
Total accrued expenses and other current liabilities	$	25,594	$	26,694

Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2026	May 01, 2026
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2026
Document Fiscal Year Focus	2026
Document Fiscal Period Focus	Q1
Entity Registrant Name	Monte Rosa Therapeutics, Inc.
Entity Central Index Key	0001826457
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		84,479,418
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Title of 12(b) Security	Common stock, par value $0.0001 per share
Trading Symbol	GLUE
Security Exchange Name	NASDAQ
Securities Act File Number	001-40522
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	84-3766197
Entity Address, Address Line One	321 Harrison Avenue
Entity Address, Address Line Two	Suite 900
Entity Address, City or Town	Boston
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02118
City Area Code	617
Local Phone Number	949-2643
Document Quarterly Report	true
Document Transition Report	false

Leases - Schedule of Lease Terms and Discount Rate (Details)	Mar. 31, 2026	Dec. 31, 2025
Leases [Abstract]
Weighted average remaining lease term (years)	6 years 6 months	6 years 9 months 18 days
Weighted average discount rate	9.80%	9.90%

Collaboration And License Agreements

3 Months Ended

Mar. 31, 2026

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Collaboration and license agreements

9. Collaboration and license agreements

Roche collaboration and license agreement

Description

In October 2023, Monte Rosa Therapeutics AG, a wholly-owned subsidiary of Monte Rosa Therapeutics, Inc, or the Company, entered into a collaboration and license agreement, or the Roche Agreement, with Roche. Pursuant to the Roche Agreement, the parties will seek to identify and develop molecular glue degraders, or MGDs, against cancer or neurological disease targets using the Company’s proprietary drug discovery engine for an initial set of targets in oncology and neuroscience selected by Roche, wherein a certain number of targets selected by Roche are for a limited time subject to replacement rights owned by Roche. The Company will lead preclinical discovery and research activities with Roche leading late preclinical and clinical development activities.

Under the Roche Agreement, Roche will have a worldwide, exclusive license under patents and know-how controlled by the Company to develop and commercialize products directed to applicable targets. The license exclusivity is subject to the Company’s retained rights solely to fulfill its obligations under the arrangement.

The research collaboration activities governed by the Roche Agreement are overseen by a joint research committee.

Unless earlier terminated, the Roche Agreement will remain in effect for each product licensed under the Roche Agreement until expiration of the royalty term for the applicable product. The parties have included termination provisions in the Roche Agreement, allowing termination of the Roche Agreement in its entirety, on a country-by-country or a target-by-target basis.

Pricing

In November 2023, the Company received a $50.0 million non-refundable upfront payment for the initial set of targets. Pursuant to the terms of the Roche Agreement, the Company expects to be entitled to receive from Roche certain variable consideration including potential preclinical milestones up to $172 million, and potential clinical, commercial and sales milestones exceeding $2 billion. The Company is also eligible to receive tiered royalties ranging from high-single-digits to low-teens on any products that are commercialized by Roche as a result of the collaboration.

To date through March 31, 2026, the Company has received $16.0 million related to Roche's decision to pay preclinical milestones and $3.0 million related to Roche's decision to exercise its option rights to replace certain targets for research and development services. The related payments are initially classified as deferred revenue in the accompanying condensed consolidated balance sheet and recognized in revenue as the related research and development services are performed.

Accounting

This agreement represents a transaction with a customer and therefore is accounted for under ASC 606, Revenue From Contracts With Customers.

The Company determined that the development and commercialization licenses for each of the collaboration targets is neither capable of being distinct nor distinct within the context from the promised initial research services. In addition, the Company has determined that each target in the agreement is distinct from other targets because: (i) Roche can benefit from the license and research services for a given target on their own since the results related thereto can be evaluated discretely and (ii) the results of the research and development of each target does not affect either the Company’s ability to perform or Roche’s ability to assess the results for any other target. As such, the Company has identified certain performance obligations within the agreement as follows:

•

Performance obligations for the research and development of initial targets; and

•

Performance obligations for the research and development services related to Roche’s option to replace certain targets.

The total transaction price of the Roche Agreement is allocated to the performance obligations based on their relative standalone selling price. The Company developed the standalone selling price for the performance obligations included in the Roche Agreement by determining the total estimated costs to fulfill each performance obligation identified with the objective of determining the price at which it would sell such an item if it were to be sold regularly on a standalone basis. The allocated transaction price is recognized as revenue from collaboration agreements in one of two ways:

•

Research and development of the initial targets: The Company recognizes the portion of the transaction price allocated to each of the research and development performance obligations as the research and development services are provided, using an input method, in proportion to costs incurred to date for each research development target as compared to total costs incurred and expected to be incurred in the future to satisfy the underlying obligation related to said research and development target. The transfer of control occurs over this period and, in management’s judgment, is the best measure of progress towards satisfying the performance obligation.

•

Option rights to replace targets: The transaction price allocated to the replacement option rights, which are considered material rights, is deferred until the period that Roche elects to exercise or elects to not exercise its option right to license and commercialize the underlying research and development target. Upon Roche's exercise of a replacement option right, the Company will recognize the portion of the transaction price allocated using the input method described above. Any payments made to exercise replacement option rights will be added to the allocated value and recognized as the related services are performed.

To date through March 31, 2026, $48.0 million related to the Roche Agreement has been recognized as collaboration revenue in the condensed consolidated statements of operations and comprehensive loss. The remaining $21.0 million of the upfront payment and subsequent milestone and replacement target payments related to customer options are recorded as deferred revenue in the liabilities section of the condensed consolidated balance sheet, with $10.5 million included in current liabilities and $10.5 million included in non-current liabilities.

The following table summarizes the deferred revenue amounts allocated to the Roche Agreement performance obligations (in thousands):


	March 31,		December 31,
	2026		2025
Roche Agreement performance obligations
Research and development of initial targets	$	12,775	$	14,140
Research and development for replacement targets		8,217		8,517
Total Roche Agreement deferred revenue	$	20,992	$	22,657

The Company expects that the remaining deferred revenue for the initial targets will be recognized within 18 months. The Company expects that deferred revenue related to replacement targets will be recognized within 30 months. Due to the uncertain nature of the research and development being performed by the Company, it may take longer than anticipated

to recognize revenue related to the performance obligations for the initial and replacement targets. Any amounts remaining in deferred revenue will be recognized at the conclusion of the Roche Agreement in October 2028.

As of March 31, 2026, potential research, development and regulatory milestone payments that the Company is eligible to receive were excluded from the transaction price as they were fully constrained by uncertain events. The Company will reevaluate the transaction price at the end of each reporting period and as uncertain events are resolved or other changes in circumstances occur, and if necessary, the Company will adjust its estimate of the transaction price. Any additions to the transaction price would be reflected in the period as a cumulative revenue catch-up based on the ratio of costs incurred to the total estimated costs expected applied to the revised transaction price. Sales-based royalties and milestone payments, which predominantly relate to the license, will be recognized if and when the related sales occur.

2024 Novartis License Agreement

Description

In October 2024, Monte Rosa Therapeutics AG, a wholly-owned subsidiary of the Company, entered into a license agreement with Novartis, or the 2024 Novartis Agreement. Pursuant to the 2024 Novartis Agreement, the Company granted to Novartis an exclusive, royalty-bearing, sublicensable and transferable license to develop, manufacture, and commercialize VAV1 MGDs, including MRT-6160, which is currently in Phase 1 clinical development for immune-mediated conditions. The Company was responsible for completing the Phase 1 clinical study and Novartis is responsible for all subsequent development and commercial activities starting at Phase 2.

Pricing

In December 2024, the Company received a $150 million non-refundable upfront payment. Pursuant to the 2024 Novartis Agreement, the Company is entitled to receive from Novartis up to $2.1 billion in development, regulatory, and sales milestones, beginning upon initiation of Phase 2 studies including (a) potential development and regulatory milestone payments, exceeding $1.5 billion if multiple indications achieve regulatory approval in multiple territories, (b) potential sales milestone payments in connection with sales outside of the U.S., and tiered royalties on sales outside of the U.S. Novartis will be responsible for costs associated with Phase 2 clinical studies. The Company and Novartis also agreed to a net profit and loss sharing arrangement, pursuant to which the Company could co-fund any global clinical development from Phase 3 onwards and will share 30% of any profits and losses associated with the manufacturing and commercialization of the licensed products in the U.S. The Company has defined opportunities to opt out of the net profit and loss sharing arrangement prior to the initiation of Phase 3 clinical trials, in such case, sales in the U.S. would be entitled to the potential sales milestone payments and tiered royalties as sales outside of the U.S. Any costs for any co-funded development and commercialization activities are subject to budgets reviewed by the Company and Novartis.

Accounting

The goods and services that the Company was obligated to deliver and perform (the License and Licensor Clinical Trial) were accounted for under ASC 606 as they represented a transaction with a customer.

The Company has concluded that the License and the completion of the Licensor Clinical Trial promises are treated as a single, combined performance obligation. The Company has determined the total transaction price to be $150 million, which consists solely of the upfront payment. All milestone payments were constrained as the achievement of the milestones are contingent upon the success of the underlying research and development activities and are generally outside the control of the Company. The Company’s options to share in further development and commercialization efforts via its opt-in/opt-out rights will be assessed and accounted for as separate units of accounting under the relevant guidance if, and when, such options are exercised by the Company.

The revenue the Company recognized associated with the combined performance obligation was recognized over time using a cost-based input methodology. The transfer of control occurred over the course of the Licensor Clinical Trial promise and, in management’s judgment, was the best measure of progress towards satisfying the combined performance obligation.

As of September 30, 2025, the total transaction price of $150 million plus $1.2 million of incremental cost reimbursements related to the Novartis Agreement has been recognized as collaboration revenue in the condensed consolidated statements of operations and comprehensive loss.

2025 Novartis License Agreement

Description

In September 2025, Monte Rosa Therapeutics AG, a wholly-owned subsidiary of the Company, entered into a collaboration, option, and license agreement with Novartis, or the 2025 Novartis Agreement. Pursuant to the 2025

Novartis Agreement, the Company granted to Novartis an exclusive, royalty-bearing, sublicensable and transferable license to degraders for one immunology and inflammation, or I&I program, or the First Licensed Program, and the option to obtain exclusive, royalty-bearing, sublicensable and transferable licenses with respect to two additional programs from the Company’s growing preclinical immunology portfolio, or the Options, and the programs, or the Optioned I&I Programs. Such Options are individually exercisable at Novartis’ discretion until a program meets criteria for investigational new drug application-filing-readiness. On a program-by-program basis, if Novartis does not exercise an Option, all rights with respect to such program are retained by the Company; if Novartis does exercise its Option, such program becomes a Licensed Program, or together, with the First Licensed Program, the Licensed Programs. Under the 2025 Novartis Agreement, the Company will apply its proprietary AI/ML-enabled QuEEN™ engine for the discovery and development of degraders for the First Licensed Program and the Optioned I&I Programs. The Licensed Programs will be further developed and commercialized by Novartis, unless otherwise agreed to by the parties in accordance with the 2025 Novartis Agreement. Research activities for the Licensed Programs governed by the Agreement will be overseen by a Joint Research Committee.

Pricing

In September 2025, the Company received a $120.0 million non-refundable upfront payment from Novartis. Pursuant to the 2025 Novartis Agreement, the Company is entitled to receive from Novartis payments to maintain the Options totaling up to $60.0 million, and is eligible to receive from Novartis (1) preclinical milestone payments relating to the First Licensed Program and option exercise payments related to the Options of up to $180.0 million, (2) up to $5.4 billion in clinical development, regulatory, and sales milestones relating to the First Licensed Program and the two Optioned I&I Programs, beginning upon initiation of Phase 1 studies, including (a) potential development and regulatory milestone payments up to $2.2 billion if regulatory approval is achieved for multiple indications in multiple territories and (b) potential sales milestone payments up to $3.2 billion, allocated across licensed products, and (3) tiered royalties on global net sales in the high-single to low double-digit range for the First Licensed Program and in the low double-digit range for the two Optioned I&I Programs. The Company will be responsible for costs related to research activities, while Novartis will be responsible for costs related to development and commercialization activities.

Accounting

The goods and services that the Company is obligated to deliver and perform under the 2025 Novartis Agreement will be accounted for under ASC 606 as they represent a transaction with a customer.

The Company has concluded that the transaction price at inception is $180 million, which consists of the $120 million upfront payment and $60 million of option maintenance payments due over the course of the contract term. The Company has identified the following performance obligations in the contract:

•

License and research services for an immunology target

•

Research services for certain immunology targets to support the Immunology License Options

•

Material Right First Immunology License Option

•

Material Right Second Immunology License Option

The total transaction price of the 2025 Novartis Agreement is allocated to the performance obligations based on their relative standalone selling prices, or the price at which it would sell such an item if it were to be sold regularly on a standalone basis. The standalone selling price of performance obligations related to license and research services were determined using a cost-plus margin approach. The standalone selling price related to material rights for immunology license options were determined by benchmarking to comparable transactions, probability adjusted for the likelihood of exercise.

The allocated transaction price is recognized as revenue from collaboration agreements in one of two ways:

•

License and research services for immunology targets: The Company recognizes the portion of the transaction price allocated to each of the research performance obligations as the research services are provided, using an input method, in proportion to costs incurred to date for each research development target as compared to total costs incurred and expected to be incurred in the future to satisfy the underlying obligation related to said research services. The transfer of control occurs over this period and, in management’s judgment, is the best measure of progress towards satisfying the performance obligation.

•

Material option rights: The transaction price allocated to the options rights, which are considered material rights, is deferred until the period that Novartis elects to exercise its option right to license and commercialize the underlying immunology program. The Company will recognize the portion of the transaction price allocated to the option rights

upon exercise. The Company has no further obligations to perform research services subsequent to the option exercise.

To date through March 31, 2026, $4.3 million of revenue related to the 2025 Novartis Agreement has been recognized as collaboration revenue in the condensed consolidated statements of operations and comprehensive (loss) income. The remaining $115.7 million has been recorded as deferred revenue on the condensed consolidated balance sheets, with $22.5 million included in current liabilities related to performance obligations expected to be completed within 12 months from March 31, 2026 and $93.2 million included in non-current liabilities related to performance obligations expected to be completed later than 12 months from March 31, 2026. The total transaction price of $180 million includes $60 million of future option maintenance payments which are not included in deferred revenue on the condensed consolidated balance sheet.

The following table summarizes the unearned amount of the 2025 Novartis Agreement transaction price allocated to the performance obligations (in thousands):


	March 31,		December 31,
	2026		2025
2025 Novartis Agreement performance obligations
License and research services for named immunology target	$	6,814	$	7,019
Research services to support immunology license options		83,357		85,698
Material right - first immunology license option		49,091		49,091
Material right - second immunology license option		36,439		36,439
Total unearned amount of transaction price	$	175,701	$	178,247

The Company expects that that the remaining deferred revenue for the license and research services for a named immunology target and research services for two additional immunology targets to be recognized within 54 months. The deferred revenue related to material right license options will be recognized when Novartis exercises such options rights or at the expiration of the option rights. Due to the uncertain nature of the research and development being performed by the Company, it may take longer than anticipated to recognize revenue related to the performance obligations related to research services.

Leases - Schedule of Future Minimum Payments Under Non -cancelable Operating Leases (Details) - Non-cancelable leases [Member] $ in Thousands	Mar. 31, 2026 USD ($)
Finite-Lived Intangible Assets [Line Items]
2026	$ 5,992
2027	8,208
2028	7,894
2029	7,575
2030	7,802
Thereafter	15,624
Total undiscounted minimum lease payments	53,095
Less: Imputed interest	(14,031)
Total operating lease liability	$ 39,064

Net (loss) income per common share

3 Months Ended

Mar. 31, 2026

Earnings Per Share [Abstract]

Net (loss) income per common share

13. Net (loss) earnings per common share

Basic and diluted net (loss) earnings per share is calculated based upon the weighted-average number of shares of common stock outstanding during the period. Shares of the Company's common stock underlying pre-funded warrants are included in the calculation of the basic and diluted earnings per share.

Basic and diluted net (loss) earnings per share are as follows (in thousands except share and per share amounts):


	Three months ended March 31,
	2026			2025
Net (loss) income	$	(44,503	)	$	46,885
Basic weighted average shares outstanding		99,883,878			82,148,719
Effect of potentially dilutive securities:
Stock options to purchase common stock		—			729,311
Restricted stock units		—			78,393
Diluted weighted average shares outstanding		99,883,878			82,956,423

Basic net (loss) earnings per share	$	(0.45	)	$	0.57
Diluted net (loss) earnings per share	$	(0.45	)	$	0.57

The following outstanding potentially dilutive securities have been excluded from the calculation of diluted net (loss) earnings per common share, as their effect is anti-dilutive:


	Three months ended March 31,
	2026		2025
Stock options to purchase common stock		15,989,324		14,422,833
Restricted stock units		1,149,012		815,941

Marketable securities - Summary of Marketable securities (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Marketable Securities [Line Items]
Amortized Cost	$ 507,170	$ 247,057
Unrealized Gains	17	164
Unrealized Losses	(826)	0
Fair Value	506,361	247,221
Corporate Debt Securities Member
Marketable Securities [Line Items]
Amortized Cost	268,690	99,543
Unrealized Gains	10	53
Unrealized Losses	(501)	0
Fair Value	268,199	99,596
US Treasury Securities Member
Marketable Securities [Line Items]
Amortized Cost	238,480	147,514
Unrealized Gains	7	111
Unrealized Losses	(325)	0
Fair Value	$ 238,162	$ 147,625

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
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Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
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Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 4: http://www.xbrl.org/2003/role/exampleRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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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/exampleRef
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Reference 10: http://www.xbrl.org/2003/role/exampleRef
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Reference 11: http://www.xbrl.org/2003/role/exampleRef
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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
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Reference 14: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 15: http://www.xbrl.org/2003/role/disclosureRef
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Reference 16: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Accrued expenses and other current liabilities - Summery Of Accrued Expenses And Other Current Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Accounts Payable and Accrued Liabilities, Current [Abstract]
Accrued compensation and benefits	$ 5,047	$ 9,998
Accrued research and development	16,641	15,118
Accrued fixed asset purchase	2,670	57
Other	1,236	1,521
Total accrued expenses and other current liabilities	$ 25,594	$ 26,694

Equity

3 Months Ended

Mar. 31, 2026

Equity [Abstract]

Equity

10. Equity

Undesignated preferred stock

The Company had 10,000,000 shares authorized of undesignated preferred stock, par value of $0.0001, of which no shares were issued and outstanding as of March 31, 2026.

Common stock

The Company had 500,000,000 shares of common stock authorized, of which 84,321,705 shares were issued and outstanding as of March 31, 2026.

Additionally, as of March 31, 2026, the Company has 16,997,266 outstanding pre-funded warrants to purchase shares of the Company's common stock to accredited investors. The pre-funded warrants are immediately exercisable at an exercise price of $0.0001 per share at any time after the date of issuance. A holder of a pre-funded warrant may not exercise such pre-funded warrant if the holder, together with its affiliates, would beneficially own more than 4.99% (or, at the election of the holder, up to 19.99%) of the number of shares of the Company’s common stock outstanding immediately after giving effect to such exercise.

The Company has assessed the pre-funded warrants for appropriate equity or liability classification. During this assessment, the Company determined the pre-funded warrants are a freestanding instrument that does not meet the definition of a liability pursuant to ASC 480 and does not meet the definition of a derivative pursuant to ASC 815. The pre-funded warrants are indexed to the Company’s common stock and meet all other conditions for equity classification under ASC 480 and ASC 815. Based on the results of this assessment, the Company concluded that the pre-funded warrants are a freestanding equity-linked financial instrument that meets the criteria for equity classification under ASC 480 and ASC 815. Accordingly, the pre-funded warrants are classified as equity and are accounted for as a component of additional paid-in capital at the time of issuance. The Company also determined that the pre-funded warrants should be included in the determination of basic and diluted earnings per share in accordance with ASC 260, Earnings per Share.

The holders of common stock are entitled to dividends when and if declared by the Company's board of directors, subject to the preferences applicable to any outstanding shares of preferred stock. The Company's board of directors has not declared any dividends and the Company has not paid any dividends.

The holders of common stock are entitled to one vote per share on all matters to be voted upon by the stockholders.

During the three months ended March 31, 2026, 5,016,658 pre-funded warrants were exercised. These exercises included net-settlements pursuant to the terms of the applicable pre-funded warrant agreements, whereby the holders elected to have pre-funded warrants withheld in a cashless exercise in lieu of paying the $0.0001 per share exercise price. As a result, 30 pre-funded warrants were withheld to cover the aggregate exercise price, resulting in the issuance of a total of 5,016,628 shares of common stock from the exercise of pre-funded warrants during the three months ended March 31, 2026. During the three months ended March 31, 2025, no pre-funded warrants were exercised.

As of March 31, 2026 and December 31, 2025, the Company has reserved the following shares of common stock for the exercise of stock options, vesting of restricted stock and pre-funded warrants:


	March 31, 2026		December 31, 2025
Options to purchase common stock		15,989,324		14,064,599
Unvested restricted common stock units		1,149,012		775,765
Pre-funded warrants		16,997,296		20,638,924
		34,135,632		35,479,288

At-the-market offerings

In July 2022, the Company entered into a sales agreement, or the 2022 Sales Agreement, with Jefferies LLC, or Jefferies, as amended on March 20, 2025, pursuant to which the Company could offer and sell shares of its common stock pursuant to the then-effective prospectus from time to time in “at-the-market” offerings through Jefferies, as the Company’s sales agent. Effective January 7, 2026, the Company terminated the prospectus pursuant to which it had been able to sell shares from time to time in at-the-market offerings under the 2022 Sales Agreement.

On February 11, 2026, the Company filed a registration statement on Form S-3ASR (File No. 333-293389) with the SEC, or the 2026 Automatic Shelf Registration Statement, in relation to the registration of common stock, preferred stock, debt securities, warrants and/or units of any combination thereof for the purposes of selling, from time to time, our common stock, debt securities or other equity securities in one or more offerings. In connection with the ATM Program and pursuant to the 2026 Automatic Shelf Registration Statement, the Company filed a new prospectus supplement with the SEC on February 11, 2026, for the offer and sale of up to $100.0 million of shares of common stock from time to time through Jefferies.

The Company agreed to pay Jefferies a commission of up to 3.0% of the gross proceeds of any shares sold by Jefferies under the Sales Agreement. During the three months ended March 31, 2026 and 2025, the Company did not sell shares of common stock under the Sales Agreement.

Underwritten public offerings

In May 2024, the Company entered into an underwriting agreement with TD Securities (USA) LLC, as representative of the several underwriters, related to an underwritten public offering, or the 2024 Offering, of 10,638,476 shares of common stock at a price of $4.70 per share, and, in lieu of common stock to certain investors, pre-funded warrants to purchase 10,638,524 shares of common stock at a price of $4.6999 per pre-funded warrant, which represents the price per share at which shares of common stock were sold in this 2024 Offering, minus $0.0001, which is the exercise price of each pre-funded warrant. The pre-funded warrants are immediately exercisable and may be exercised at any time until the pre-funded warrants are exercised in full. Aggregate gross proceeds from the 2024 Offering were $100 million, or aggregate net proceeds of $96.4 million after deducting the underwriter discounts, commissions, and other offering costs.

In January 2026, the Company entered into an underwriting agreement with Jefferies LLC, TD Securities (USA) LLC, and Piper Sandler & Co. as representatives of the several underwriters, related to an underwritten public offering, or the 2026 Offering, of 13,000,000 shares of common stock at a price of $24.00 per share, and, in lieu of common stock to certain investors, pre-funded warrants to purchase 1,375,000 shares of common stock at a price of $23.9999 per pre-funded warrant, which represents the price per share at which shares of common stock were sold in the 2026 Offering, minus $0.0001, which is the exercise price of each pre-funded warrant. The pre-funded warrants are immediately exercisable and may be exercised at any time until the pre-funded warrants are exercised in full. Aggregate gross proceeds from the 2026 Offering were $345.0 million, or aggregate net proceeds of $323.8 million after deducting the underwriter discounts, commissions, and other offering costs.

- 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
-Paragraph 8A
-Publisher FASB
-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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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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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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Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
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-URI https://asc.fasb.org/1943274/2147481112/505-10-50-13

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-13

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

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

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

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

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

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

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

+ Details

Leases (Tables)

3 Months Ended

Mar. 31, 2026

Leases [Abstract]

Component of Lease Expense

The components of lease expense for the three months ended March 31, 2026 and 2025 are as follows (in thousands):


	Three months ended March 31,
	2026		2025
Operating lease expense	$	1,638	$	1,634
Variable lease expense		758		852
Total lease expense	$	2,396	$	2,486

Summarizes Lease Expense

The following table summarizes lease expense incurred (in thousands):


	Three months ended March 31,
	2026		2025
Research and development	$	2,244	$	2,078
General and administrative		152		408
Total lease expense	$	2,396	$	2,486

Schedule of Lease Terms and Discount Rate

The weighted average remaining lease term and discount rate related to the Company's leases are as follows:


	March 31, 2026			December 31, 2025
Weighted average remaining lease term (years)		6.5			6.8
Weighted average discount rate		9.8	%		9.9	%

Schedule Of Supplemental Cash Flow Information Related To Leases

Supplemental cash flow information and other information relating to the Company's leases for the three months ended March 31, 2026 and 2025 is as follows (in thousands):


	Three months ended March 31,
	2026		2025
Cash paid for amounts included in the measurement of lease liabilities	$	1,998	$	908
Amortization of ROU assets	$	643	$	574

Schedule of Future Minimum Payments Under Non -cancelable Operating Leases

Future minimum lease payments under non-cancelable leases as of March 31, 2026 for each of the years ending December 31 are as follows (in thousands):


Undiscounted lease payments
2026	$	5,992
2027		8,208
2028		7,894
2029		7,575
2030		7,802
Thereafter		15,624
Total undiscounted minimum lease payments		53,095
Less: Imputed interest		(14,031	)
Total operating lease liability	$	39,064

Summary of significant accounting policies	3 Months Ended
Summary of significant accounting policies	Mar. 31, 2026
Accounting Policies [Abstract]
Summary of significant accounting policies	2. Summary of significant accounting policies Basis of presentation The accompanying condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the U.S., or GAAP, and are stated in U.S. dollars. Any reference in these notes to applicable guidance is meant to refer to the authoritative GAAP as found in the Accounting Standards Codification and Accounting Standards Updates, or ASUs, of the Financial Accounting Standards Board, or FASB. All intercompany balances and transactions have been eliminated in consolidation. Unaudited financial information The Company’s condensed consolidated financial statements included herein have been prepared in conformity with GAAP and pursuant to the rules and regulations of the Securities and Exchange Commission, or the SEC. In the Company’s opinion, the information furnished reflects all adjustments, all of which are of a normal and recurring nature, necessary for a fair presentation of the financial position and results of operations for the reported interim periods. The Company considers events or transactions that occur after the balance sheet date but before the financial statements are issued to provide additional evidence relative to certain estimates or to identify matters that require additional disclosure. The results of operations for interim periods are not necessarily indicative of results to be expected for the full year or any other interim period. Recently issued accounting pronouncements The Company has elected to use the extended transition period for complying with new or revised accounting standards as available under the Jumpstart Our Business Startups Act, or the JOBS Act. In November 2024, the FASB issued ASU 2024-03, Income Statement Reporting Comprehensive Income—Expense Disaggregation Disclosures (Subtopic 220-40), which requires disaggregated disclosure of income statement expenses for public business entities. ASU 2024-03 requires disclosure of, in a tabular presentation, each relevant expense caption on the face of the income statement that includes any of the following natural expenses: (1) purchases of inventory, (2) employee compensation, (3) depreciation, (4) intangible asset amortization, and (5) depreciation, depletion, and amortization (DD&A) recognized as part of oil- and gas-producing activities or other types of depletion expenses. The tabular disclosure would also include certain other expenses, when applicable. The standard is effective for fiscal years beginning after December 15, 2026, and interim periods within fiscal years beginning after December 15, 2027. The Company is currently evaluating the impact the adoption of this standard will have on its consolidated financial statements and related disclosures. \\\

Employee retirement plans - Schedule of Pension Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Retirement Benefits [Abstract]
Pension expense	$ 350	$ 388

Collaboration and license agreements - Summarizes the transaction price allocated to performance obligations (Details) - 2025 Novartis License Agreement - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total unearned amount of transaction price	$ 175,701	$ 178,247
License and research services for named immunology target [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total unearned amount of transaction price	6,814	7,019
Research services to support immunology license options [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total unearned amount of transaction price	83,357	85,698
Material right - first immunology license option [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total unearned amount of transaction price	49,091	49,091
Material right - second immunology license option [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total unearned amount of transaction price	$ 36,439	$ 36,439

Segment data - Schedule of Company's reportable segment net revenues and loss (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Dec. 31, 2025
Revenue:
Collaboration Revenue	$ 4,210	$ 84,929
External research and development expenses:
Other development and discovery programs	9,589	4,040
Personnel expense	6,420	5,679
Overhead and administrative expense	10,111	8,228
General and administrative expenses:
Personnel expense	13,493	11,352
Professional services	2,143	1,478
Facility costs and other expense	1,612	1,546
Other income (expense):
Interest and other income, net	5,583	3,671
Income tax provision	(52)	(822)
Net (loss) income	(44,503)	46,885	$ (38,600)
MRT-2359
External research and development expenses:
External research and development expenses	2,381	1,945
MRT-6160
External research and development expenses:
External research and development expenses	11	3,981
MRT-8102
External research and development expenses:
External research and development expenses	6,781	1,882
CCNE1
External research and development expenses:
External research and development expenses	$ 1,703	$ 762

Equity - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		3 Months Ended
	Jan. 31, 2026	May 31, 2024	Mar. 31, 2026	Mar. 31, 2025	Feb. 11, 2026	Dec. 31, 2025
Class of Stock [Line Items]
Common stock, shares authorized			500,000,000			500,000,000
Common stock shares issued			84,321,705			65,543,723
Preferred stock, shares authorized			10,000,000			10,000,000
Pre funded warrants were exercised			5,016,658	0
Pre-funded warrants withheld in cashless exercise			30
Preferred stock, par value			$ 0.0001			$ 0.0001
Common stock shares outstanding			84,321,705			65,543,723
Description of Pre Funded Warrants			A holder of a pre-funded warrant may not exercise such pre-funded warrant if the holder, together with its affiliates, would beneficially own more than 4.99% (or, at the election of the holder, up to 19.99%) of the number of shares of the Company’s common stock outstanding immediately after giving effect to such exercise.
Share exercise price			$ 0.0001
Dividends declared			$ 0
Dividends paid			$ 0
Common stock, voting rights			one
Warrant [Member]
Class of Stock [Line Items]
Pre-funded warrants to purchase			16,997,266
Pre funded warrants were exercised			5,016,628
Pre-funded warrants exercisable, exercise price			$ 0.0001
Common Stock
Class of Stock [Line Items]
Common stock shares issued			84,321,705
Underwritten public offering	13,000,000	10,638,476
Common stock shares outstanding			84,321,705
Pre-funded warrants exercisable, exercise price	$ 0.0001	$ 0.0001
Jefferies LLC [Member]
Class of Stock [Line Items]
Common stock, shares, issued during the period			0
TD Securities (USA) LLC [Member]
Class of Stock [Line Items]
Gross Proceeds from sale of Common Stock	$ 345,000	$ 100,000
Aggregate net proceeds after deduction	$ 323,800	$ 96,400
TD Securities (USA) LLC [Member] \| Warrant [Member]
Class of Stock [Line Items]
Purchase of pre-funded warrants shares	1,375,000	10,638,524
Common stock price	$ 23.9999	$ 4.6999
TD Securities (USA) LLC [Member] \| Common Stock
Class of Stock [Line Items]
Common stock price	$ 24	$ 4.7
At-the-Market Offering [Member]
Class of Stock [Line Items]
Common stock offering amount					$ 100,000
At-the-Market Offering [Member] \| Jefferies LLC [Member]
Class of Stock [Line Items]
Percentage of commission paid under sales agreement			3.00%
Undesignated Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares authorized			10,000,000
Preferred stock, par value			$ 0.0001
Preferred stock shares issued			0
Preferred stock, shares outstanding			0

Equity - Schedule of Common Stock for Potential Conversion Outstanding Preferred Stock (Details) - shares	Mar. 31, 2026	Dec. 31, 2025
Class Of Stock [Line Items]
Common stock reserved for future issuance	34,135,632	35,479,288
Options to purchase common stock
Class Of Stock [Line Items]
Common stock reserved for future issuance	15,989,324	14,064,599
Restricted stock units
Class Of Stock [Line Items]
Common stock reserved for future issuance	1,149,012	775,765
Pre-funded warrants
Class Of Stock [Line Items]
Common stock reserved for future issuance	16,997,296	20,638,924

- Definition

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

+ References

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

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-2

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480738/235-10-S50-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 480
-SubTopic 10
-Name Accounting Standards Codification
-Section S50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479857/480-10-S50-1

Reference 5: http://www.xbrl.org/2003/role/exampleRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-13

Reference 6: http://www.xbrl.org/2003/role/recommendedDisclosureRef
-Topic 272
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483014/272-10-45-3

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 272
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482987/272-10-50-1

Reference 8: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(d))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480678/235-10-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-13

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

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (e)
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-URI https://asc.fasb.org/1943274/2147481112/505-10-50-13

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-13

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-14

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

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
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-Name Accounting Standards Codification
-Section S99
-Paragraph 1
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Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(28))
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Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Subparagraph (SX 210.6-03(i)(2))
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-URI https://asc.fasb.org/1943274/2147479886/946-10-S99-3

Reference 19: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 10
-Name Accounting Standards Codification
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-Paragraph 3
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Reference 20: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 10
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-Subparagraph (SX 210.6-03(i)(2)(i))
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-URI https://asc.fasb.org/1943274/2147479886/946-10-S99-3

Reference 21: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Subparagraph (SX 210.6-03(i)(2)(ii))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479886/946-10-S99-3

+ Details

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Current assets:
Cash and cash equivalents	$ 159,859	$ 129,883
Marketable securities	506,361	247,221
Collaboration receivable	0	7,000
Other receivables	4,609	4,600
Prepaid expenses and other current assets	6,718	4,481
Total current assets	677,547	393,185
Property and equipment, net	28,409	25,986
Operating lease right-of-use assets	24,693	24,386
Restricted cash	4,947	4,954
Other long-term assets	832	148
Total assets	736,428	448,659
Current liabilities:
Accounts payable	7,900	3,550
Accrued expenses and other current liabilities	25,594	26,694
Current deferred revenue	33,059	29,571
Current portion of operating lease liability	4,483	4,397
Total current liabilities	71,036	64,212
Deferred revenue, net of current	103,635	111,332
Defined benefit plan liability	5,260	5,265
Operating lease liability, net of current	34,581	34,794
Total liabilities	214,512	215,603
Commitments and contingencies (Note 8)
Stockholders' equity
Preferred stock, $0.0001 par value, 10,000,000 shares authorized	0	0
Common stock, $0.0001 par value 500,000,000 shares authorized, 84,321,705 and 65,543,723 shares issued and outstanding as of March 31, 2026 and December 31, 2025, respectively	8	7
Additional paid-in capital	1,048,371	714,090
Accumulated other comprehensive loss	(4,746)	(3,827)
Accumulated deficit	(521,717)	(477,214)
Total stockholders' equity	521,916	233,056
Total liabilities and stockholders' equity	$ 736,428	$ 448,659

Stock-based compensation - Schedule of Restricted Stock Unit Activity (Details)	3 Months Ended
	Mar. 31, 2026 $ / shares shares
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of shares, forfeited	(69,761)
Restricted stock units
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of shares, Unvested restricted stock, beginning balance	775,765
Number of shares, Granted	568,550
Number of shares, Vested	(186,515)
Number of shares, forfeited	(8,788)
Number of shares, Unvested restricted stock, ending balance	1,149,012
Weighted average grant date fair value, beginning balance \| $ / shares	$ 7.05
Weighted average grant date fair value, Granted \| $ / shares	15.46
Weighted average grant date fair value, vested \| $ / shares	7.06
Weighted average grant date fair value, Forfeited \| $ / shares	8.84
Weighted average grant date fair value, ending balance \| $ / shares	$ 11.2

Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Income Statement [Abstract]
Collaboration Revenue	$ 4,210	$ 84,929
Operating expenses:
Research and development	44,069	32,190
General and administrative	10,175	8,703
Total operating expenses	54,244	40,893
(Loss) income from operations	(50,034)	44,036
Other income:
Interest income	5,591	3,439
Foreign currency exchange (loss) gain	(8)	173
Gain on disposal of property and equipment	0	59
Total other income	5,583	3,671
Net (loss) income before income taxes	(44,451)	47,707
Income tax benefit (provision)	(52)	(822)
Net (loss) income	(44,503)	46,885
Comprehensive loss (income):
Provision for pension benefit obligation	55	48
Unrealized loss on available-for-sale securities	(974)	(21)
Comprehensive (loss) income	$ (45,422)	$ 46,912
(Loss) earnings per share:
Basic	$ (0.45)	$ 0.57
Diluted	$ (0.45)	$ 0.57
Weighted average number of shares outstanding:
Basic	99,883,878	82,148,719
Diluted	99,883,878	82,956,423

Property and equipment, net

3 Months Ended

Mar. 31, 2026

Property, Plant and Equipment [Abstract]

Property and Equipment, net

5. Property and equipment, net

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


	March 31, 2026			December 31, 2025
Laboratory equipment	$	28,024		$	27,022
Computer hardware and software		1,388			1,388
Furniture and fixtures		1,402			1,402
Leasehold improvements		23,794			23,669
Construction in process		3,445			118
Total property and equipment, at cost	$	58,053		$	53,599
Less: accumulated depreciation		(29,644	)		(27,613	)
Property and equipment, net	$	28,409		$	25,986

Depreciation expense for each of the three months ended March 31, 2026 and 2025 was $2.0 million.

Fair Value Measurements

3 Months Ended

Mar. 31, 2026

Fair Value Disclosures [Abstract]

Fair value measurements

3. Fair value measurements

The following tables present information about the Company’s financial assets and liabilities measured at fair value on a recurring basis and indicate the level of the fair value hierarchy utilized to determine such fair values (in thousands):


	As of March 31, 2026
	Level 1		Level 2		Level 3		Total
Current assets
Money market funds	$	159,238	$	—	$	—	$	159,238
Pension plan assets		—		12,492		—		12,492
Corporate debt securities		—		268,199		—		268,199
U.S Treasury securities		—		238,162		—		238,162
Total assets measured at fair value	$	159,238	$	518,853	$	—	$	678,091


	As of December 31, 2025
	Level 1		Level 2		Level 3		Total
Current assets
Money market funds	$	129,279	$	—	$	—	$	129,279
Pension plan assets		—		12,440		—		12,440
Corporate debt securities		—		99,596		—		99,596
U.S Treasury securities		—		147,625		—		147,625
Total assets measured at fair value	$	129,279	$	259,661	$	—	$	388,940

Money market funds are highly liquid investments and are actively traded. The pricing information on the Company’s money market funds is based on quoted prices in active markets for identical securities. This approach results in the classification of these securities as Level 1 of the fair value hierarchy.

The fair value of pension plan assets has been determined as the surrender value of the portfolio of active insured members held within the Columna Collective Foundation Group investment fund and is classified within Level 2 of the fair value hierarchy.

Marketable securities consist of corporate debt securities and U.S. Treasury securities which are classified as available-for-sale pursuant to ASC 320, Investments—Debt and Equity Securities. Marketable securities are classified within Level 2 of the fair value hierarchy because pricing inputs are other than quoted prices in active markets. The fair values of these investments are estimated 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 based on historical data and other observable inputs.

There were no transfers among Level 1, Level 2 or Level 3 categories in the three months ended March 31, 2026 and 2025.

Income taxes

3 Months Ended

Mar. 31, 2026

Income Tax Disclosure [Abstract]

Income taxes

12. Income taxes

For the three months ended March 31, 2026 and 2025, the Company recorded an income tax provision of $0.1 million and $0.8 million, respectively. For the three months ended March 31, 2026, the income tax provision was primarily related to

interest income on marketable securities in Massachusetts. For the three months ended March 31, 2025, the income tax provision was primarily related to interest income on marketable securities in Massachusetts and income generated from the capitalization of research and development expenses, which, prior to the enactment of the One Big Beautiful Bill Act, were taxable in the U.S.

The Company continues to maintain a full valuation allowance against all of its deferred tax assets. The Company has evaluated the positive and negative evidence involving its ability to realize its deferred tax assets. The Company has considered its history of cumulative net losses incurred since inception and its lack of any commercial products. The Company has concluded that it is more likely than not that it will not realize the benefits of its deferred tax assets. The Company reevaluates the positive and negative evidence at each reporting period.

- Definition

The entire disclosure for income tax.

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+ Details

Income taxes - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Collaboration Revenue	$ 4,210	$ 84,929
Income tax provision	(52)	$ (822)
Novartis License Agreement [Member]
Collaboration Revenue	$ 180,000

- Definition

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

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- Definition

Amount, including 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.

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+ Details

Description of Business and Liquidity - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Dec. 31, 2025
Accounting Policies [Abstract]
Cash and Equivalents And Marketable Securities	$ 666,200
Accumulated deficit	(521,717)		$ (477,214)
Net (loss) income	$ (44,503)	$ 46,885	$ (38,600)

- Definition

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

+ References

+ Details

- Definition

Amount of accumulated undistributed earnings (deficit).

+ References + Details

Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2026

Share-Based Payment Arrangement [Abstract]

Schedule of Stock Option Activity

The following summarizes stock option activity:


	Number of options			Weighted average exercise price		Weighted average remaining contractual term (years)		Aggregate intrinsic value (in thousands)
Outstanding—December 31, 2025		14,064,599		$	7.74		7.2	$	115,245
Granted		2,569,325			15.46
Exercised		(574,839	)		7.87
Forfeited		(69,761	)		8.10
Outstanding—March 31, 2026		15,989,324		$	8.98		7.5	$	122,640
Vested or expected to vest—March 31, 2026		15,989,324		$	8.98		7.5	$	122,640
Exercisable—March 31, 2026		8,921,922		$	8.32		6.4	$	75,433

Schedule of Restricted Stock Unit Activity

The following summarizes RSU activity:


	Number of shares			Weighted average grant date fair value
Unvested restricted stock units as of December 31, 2025		775,765		$	7.05
Granted		568,550		$	15.46
Vested		(186,515	)	$	7.06
Forfeited		(8,788	)	$	8.84
Unvested restricted stock units as of March 31, 2026		1,149,012		$	11.20

Schedule of Stock Based Compensation Expense

Stock-based compensation expense is classified as follows (in thousands):


	Three months ended March 31,
	2026		2025
Research and development	$	3,374	$	3,135
General and administrative		2,575		2,163
Total stock-based compensation expense	$	5,949	$	5,298

Income taxes - Schedule of income tax provision recorded (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Income Tax Disclosure [Abstract]
Income tax provision	$ (52)	$ (822)

- Definition

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

+ References

+ Details

Description of business and liquidity

3 Months Ended

Mar. 31, 2026

Accounting Policies [Abstract]

Description of business and liquidity

1. Description of business and liquidity

Business

Monte Rosa Therapeutics, Inc. is a biotechnology company developing a portfolio of novel small molecule precision medicines that employ the body’s natural mechanisms to selectively degrade therapeutically-relevant proteins. As used in these condensed consolidated financial statements, unless the context otherwise requires, references to the Company or Monte Rosa refer to Monte Rosa Therapeutics, Inc. and its wholly owned subsidiaries Monte Rosa Therapeutics AG and Monte Rosa Therapeutics Securities Corporation. Monte Rosa Therapeutics AG, a Swiss operating company, was incorporated under the laws of Switzerland in April 2018. Monte Rosa Therapeutics, Inc. was incorporated in Delaware in November 2019. The Company is headquartered in Boston, Massachusetts with research operations in both Boston and Basel, Switzerland.

Liquidity considerations

Since inception, the Company has devoted substantially all its efforts to business planning, research and development, recruiting management and technical staff, and raising capital and has financed its operations primarily through issuance and sale of convertible promissory notes, convertible preferred stock, public offerings of common stock or warrants to purchase common stock, registered direct offerings, and through its collaborations with F. Hoffman-La Roche Ltd. and Hoffman-La Roche Inc., or Roche, and with Novartis AG, or Novartis.

The Company’s continued discovery and development of its product candidates 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 product development efforts are successful, it is uncertain when, if ever, the Company will realize significant revenue from product sales.

As of March 31, 2026, the Company had an accumulated deficit of $521.7 million. The Company has incurred losses and negative cash flows from operations since inception, including net losses of $44.5 million for the three months ended March 31, 2026 and $38.6 million for the year ended December 31, 2025. The Company expects that its operating losses and negative cash flows will continue for the foreseeable future as the Company continues to develop its product candidates. The Company currently expects that its cash, cash equivalents, and marketable securities of $666.2 million as of March 31, 2026 will be sufficient to fund operating expenses and capital requirements for at least 12 months from the date the first quarter interim condensed consolidated financial statements are issued. However, additional funding will be necessary to fund future discovery research, preclinical and clinical activities. The Company will seek additional funding through public financings, debt financings, collaboration agreements, strategic alliances and licensing arrangements. Although it has been successful in raising capital in the past, there is no assurance that the Company will be successful in obtaining such additional financing on terms acceptable to it, if at all, and the Company may not be able to enter into collaborations or other arrangements. If the Company is unable to obtain funding, it could be forced to delay, reduce or eliminate its research and development programs, product portfolio expansion or commercialization efforts, which could adversely affect the Company’s business prospects, and even the ability to continue operations.

Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Cash flows from operating activities:
Net loss	$ (44,503)	$ 46,885
Adjustments to reconcile net loss to net cash used in operating activities
Stock-based compensation expense	5,949	5,298
Depreciation	2,029	2,048
Net accretion of discounts/premiums on marketable securities	(985)	(1,029)
Gain on disposal of property and equipment	0	(59)
Changes in operating assets and liabilities
Collaboration receivable	7,000	0
Other receivables	(9)	(1,235)
Prepaid expenses and other assets	(2,921)	(4)
Accounts payable	4,377	(10,874)
Accrued expenses and other current liabilities	(3,712)	(2,606)
Defined benefit plan liability	49	307
Right-of-use assets and operating lease liabilities	(434)	(283)
Deferred revenue	(4,209)	(83,940)
Net cash used in operating activities	(37,369)	(45,492)
Cash flows from investing activities:
Purchases of property and equipment	(1,868)	(1,587)
Purchases of marketable securities	(331,997)	(138,014)
Proceeds from maturities of marketable securities	72,868	39,372
Net cash used in investing activities	(260,997)	(100,229)
Cash flows from financing activities:
Proceeds from exercise of employee stock options	4,522	14
Proceeds from underwritten public offering, net of underwriter's commission of $20,700	324,300	0
Payment of offering costs	(487)	0
Net cash provided by financing activities	328,335	14
Net decrease in cash, cash equivalents and restricted cash	29,969	(145,707)
Cash, cash equivalents and restricted cash—beginning of period	134,837	229,117
Cash, cash equivalents and restricted cash-end of period	164,806	83,410
Reconciliation of cash, cash equivalents and restricted cash
Cash and cash equivalents	159,859	78,530
Restricted cash	4,947	4,880
Total cash, cash equivalents and restricted cash	164,806	83,410
Supplemental disclosure of noncash items
Purchases of property and equipment in accounts payable and accrued expenses	$ 2,736	$ 304

Condensed Combined and Consolidated Statements of Stockholders' Equity (Deficit) (Unaudited) (Parenthetical) $ in Thousands	3 Months Ended
	Mar. 31, 2026 USD ($)
Common Stock \| Underwritten Public Offiering
Net issuance costs	$ 21,187

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - $ / shares	Mar. 31, 2026	Dec. 31, 2025
Statement of Financial Position [Abstract]
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	10,000,000	10,000,000
Common stock, par or stated value per share	$ 0.0001	$ 0.0001
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares, issued	84,321,705	65,543,723
Common stock shares outstanding	84,321,705	65,543,723

Marketable securities (Tables)

3 Months Ended

Mar. 31, 2026

Investments, Debt and Equity Securities [Abstract]

Summary of Marketable securities

Marketable securities as of March 31, 2026 consisted of the following (in thousands):


	Amortized		Unrealized		Unrealized			Fair
	Cost		Gains		Losses			Value
Description
Corporate debt securities	$	268,690	$	10	$	(501	)		268,199
U.S Treasury securities		238,480		7		(325	)		238,162
Total	$	507,170	$	17	$	(826	)	$	506,361

Marketable securities as of December 31, 2025 consisted of the following (in thousands):


	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
Description
Corporate debt securities	$	99,543	$	53	$	—		99,596
U.S Treasury securities		147,514		111		—		147,625
Total	$	247,057	$	164	$	—	$	247,221

- Definition

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

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-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef
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-Section 50
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-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

Reference 7: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 8: http://www.xbrl.org/2009/role/commonPracticeRef
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-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

Reference 9: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
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-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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-Section 50
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Reference 11: http://www.xbrl.org/2009/role/commonPracticeRef
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-Subparagraph (c)
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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

Summary of significant accounting policies (Policies)	3 Months Ended
Summary of significant accounting policies (Policies)	Mar. 31, 2026
Accounting Policies [Abstract]
Liquidity consideration	Liquidity considerations Since inception, the Company has devoted substantially all its efforts to business planning, research and development, recruiting management and technical staff, and raising capital and has financed its operations primarily through issuance and sale of convertible promissory notes, convertible preferred stock, public offerings of common stock or warrants to purchase common stock, registered direct offerings, and through its collaborations with F. Hoffman-La Roche Ltd. and Hoffman-La Roche Inc., or Roche, and with Novartis AG, or Novartis. The Company’s continued discovery and development of its product candidates 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 product development efforts are successful, it is uncertain when, if ever, the Company will realize significant revenue from product sales. As of March 31, 2026, the Company had an accumulated deficit of $521.7 million. The Company has incurred losses and negative cash flows from operations since inception, including net losses of $44.5 million for the three months ended March 31, 2026 and $38.6 million for the year ended December 31, 2025. The Company expects that its operating losses and negative cash flows will continue for the foreseeable future as the Company continues to develop its product candidates. The Company currently expects that its cash, cash equivalents, and marketable securities of $666.2 million as of March 31, 2026 will be sufficient to fund operating expenses and capital requirements for at least 12 months from the date the first quarter interim condensed consolidated financial statements are issued. However, additional funding will be necessary to fund future discovery research, preclinical and clinical activities. The Company will seek additional funding through public financings, debt financings, collaboration agreements, strategic alliances and licensing arrangements. Although it has been successful in raising capital in the past, there is no assurance that the Company will be successful in obtaining such additional financing on terms acceptable to it, if at all, and the Company may not be able to enter into collaborations or other arrangements. If the Company is unable to obtain funding, it could be forced to delay, reduce or eliminate its research and development programs, product portfolio expansion or commercialization efforts, which could adversely affect the Company’s business prospects, and even the ability to continue operations.
Basis of presentation	Basis of presentation The accompanying condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the U.S., or GAAP, and are stated in U.S. dollars. Any reference in these notes to applicable guidance is meant to refer to the authoritative GAAP as found in the Accounting Standards Codification and Accounting Standards Updates, or ASUs, of the Financial Accounting Standards Board, or FASB. All intercompany balances and transactions have been eliminated in consolidation.
Unaudited Financial information	Unaudited financial information The Company’s condensed consolidated financial statements included herein have been prepared in conformity with GAAP and pursuant to the rules and regulations of the Securities and Exchange Commission, or the SEC. In the Company’s opinion, the information furnished reflects all adjustments, all of which are of a normal and recurring nature, necessary for a fair presentation of the financial position and results of operations for the reported interim periods. The Company considers events or transactions that occur after the balance sheet date but before the financial statements are issued to provide additional evidence relative to certain estimates or to identify matters that require additional disclosure. The results of operations for interim periods are not necessarily indicative of results to be expected for the full year or any other interim period.
Recently issued accounting pronouncements	Recently issued accounting pronouncements The Company has elected to use the extended transition period for complying with new or revised accounting standards as available under the Jumpstart Our Business Startups Act, or the JOBS Act. In November 2024, the FASB issued ASU 2024-03, Income Statement Reporting Comprehensive Income—Expense Disaggregation Disclosures (Subtopic 220-40), which requires disaggregated disclosure of income statement expenses for public business entities. ASU 2024-03 requires disclosure of, in a tabular presentation, each relevant expense caption on the face of the income statement that includes any of the following natural expenses: (1) purchases of inventory, (2) employee compensation, (3) depreciation, (4) intangible asset amortization, and (5) depreciation, depletion, and amortization (DD&A) recognized as part of oil- and gas-producing activities or other types of depletion expenses. The tabular disclosure would also include certain other expenses, when applicable. The standard is effective for fiscal years beginning after December 15, 2026, and interim periods within fiscal years beginning after December 15, 2027. The Company is currently evaluating the impact the adoption of this standard will have on its consolidated financial statements and related disclosures. \\\

Commitments and contigencies

3 Months Ended

Mar. 31, 2026

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

8. Commitments and contingencies

Legal proceedings

From time to time, the Company may be subject to legal proceedings, claims and disputes that arise in the ordinary course of business. The Company accrues a liability for such matters when it is probable that future expenditures will be made and that such expenditures can be reasonably estimated. As of March 31, 2026, the Company is not a party to any litigation and does not have a contingency reserve established for any litigation liabilities.

Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2026

Fair Value Disclosures [Abstract]

Schedule of Fair Value of Assets and Liabilities Measured On Recurring Basis


	As of March 31, 2026
	Level 1		Level 2		Level 3		Total
Current assets
Money market funds	$	159,238	$	—	$	—	$	159,238
Pension plan assets		—		12,492		—		12,492
Corporate debt securities		—		268,199		—		268,199
U.S Treasury securities		—		238,162		—		238,162
Total assets measured at fair value	$	159,238	$	518,853	$	—	$	678,091


	As of December 31, 2025
	Level 1		Level 2		Level 3		Total
Current assets
Money market funds	$	129,279	$	—	$	—	$	129,279
Pension plan assets		—		12,440		—		12,440
Corporate debt securities		—		99,596		—		99,596
U.S Treasury securities		—		147,625		—		147,625
Total assets measured at fair value	$	129,279	$	259,661	$	—	$	388,940

Condensed Combined and Consolidated Statements of Stockholders' Equity (Deficit) (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit
Balance (In shares), beginning at Dec. 31, 2024		61,507,446
Balance beginning period at Dec. 31, 2024	$ 222,936	$ 6	$ 664,874	$ (3,356)	$ (438,588)
Exercise of common stock options	14		14
Exercise of common stock options, Shares		2,375
Provision for pension benefit obligation	48			48
Stock-based compensation expense	5,298		5,298
Unrealized gain loss on available-for-sale securities	(21)			(21)
Net (loss) income	46,885				46,885
Balance end period at Mar. 31, 2025	275,160	$ 6	670,186	(3,329)	(391,703)
Balance (In shares), period end at Mar. 31, 2025		61,509,821
Balance (In shares), beginning at Dec. 31, 2024		61,507,446
Balance beginning period at Dec. 31, 2024	222,936	$ 6	664,874	(3,356)	(438,588)
Net (loss) income	(38,600)
Balance end period at Dec. 31, 2025	233,056	$ 7	714,090	(3,827)	(477,214)
Balance (In shares), period end at Dec. 31, 2025		65,543,723
Restricted common stock vesting, Shares		186,515
Exercise of pre-funded warrants		5,016,628
Exercise of common stock options	$ 4,522		4,522
Exercise of common stock options, Shares	574,839	574,839
Provision for pension benefit obligation	$ 55			55
Stock-based compensation expense	5,949		5,949
Unrealized gain loss on available-for-sale securities	$ (974)			(974)
Issuance of common stock, Share	13,000,000
Issuance of common stock	$ 323,811	$ 1	323,810
Net (loss) income	(44,503)				(44,503)
Balance end period at Mar. 31, 2026	$ 521,916	$ 8	$ 1,048,371	$ (4,746)	$ (521,717)
Balance (In shares), period end at Mar. 31, 2026		84,321,705

Equity (Tables)

3 Months Ended

Mar. 31, 2026

Equity [Abstract]

Common Stock Reserved for Potential Conversion of Outstanding Preferred Stock, Vesting of Restricted Stock and Exercise of Stock Options

As of March 31, 2026 and December 31, 2025, the Company has reserved the following shares of common stock for the exercise of stock options, vesting of restricted stock and pre-funded warrants:


	March 31, 2026		December 31, 2025
Options to purchase common stock		15,989,324		14,064,599
Unvested restricted common stock units		1,149,012		775,765
Pre-funded warrants		16,997,296		20,638,924
		34,135,632		35,479,288

Stock-Based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Dec. 31, 2025	Jun. 17, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance	34,135,632		35,479,288
Restricted common stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized stock based compensation cost, units	$ 12.0
Expected remaining cost, weighted average period	3 years 3 months 18 days
Unvested Stock Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized stock based compensation cost	$ 49.4
Expected remaining cost, weighted average period	2 years 8 months 12 days
Restricted stock units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Aggregate fair value of restricted stock vested	$ 2.9	$ 0.0
Weighted average grant fair value, granted	$ 7.06
2021 Stock Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance				4,903,145
Increase in share percentage	5.00%
Number of share increase	3,277,186
Available For Issuance Under the Plan, Shares	2,489,188
2021 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance	439,849
Increase in share percentage	1.00%
Number of share increase	439,849
Available For Issuance Under the Plan, Shares	2,125,604
2026 Inducement Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance	1,500,000
Available For Issuance Under the Plan, Shares	1,500,000

Segment data (Additional Information) (Details) - Segment	3 Months Ended	12 Months Ended
	Mar. 31, 2026	Dec. 31, 2025
Segment Reporting Information [Line Items]
Number of reportable segments	1
Number of operating segments	1
Switzerland
Segment Reporting Information [Line Items]
Percentage Of Assets Held	32.00%	29.00%

Stock-Based Compensation

3 Months Ended

Mar. 31, 2026

Share-Based Payment Arrangement [Abstract]

Stock-Based Compensation

11. Stock-based compensation

2020 Stock incentive plan

The Company’s 2020 Stock Option and Grant Plan, or the 2020 Plan, provided for the Company to grant stock options, restricted stock and other stock awards, to employees, non-employee directors, and consultants. Upon the effectiveness of the 2021 Plan (as defined below), no further issuances were made under the 2020 Plan.

2021 Stock Option and Incentive Plan

The Company’s 2021 Stock Option and Incentive Plan, or the 2021 Plan, was approved by the Company’s board of directors on May 28, 2021 and the Company’s stockholders on June 17, 2021 and became effective on the date immediately prior to the date on which the registration statement for the Company’s initial public offering, or IPO, was declared effective. The 2021 Plan provides for the grant of incentive stock options; non-qualified stock options; stock appreciation rights; restricted stock units, or RSUs; restricted stock awards; unrestricted stock awards; cash-based awards and dividend equivalent rights to the Company’s officers, employees, directors and consultants. The number of shares initially reserved for issuance under the 2021 Plan was 4,903,145. Under the evergreen provision of the 2021 Plan, the shares available for issuance under the 2021 Plan will be automatically increased each January 1st by 5% of the outstanding number of shares of the Company’s common stock on the immediately preceding December 31st or such lesser number of shares as may be determined by the Company’s compensation, nomination and corporate governance committee. Effective January 1, 2026 the number of shares available under the 2021 Plan automatically increased by 3,277,186 shares pursuant to the evergreen provision of the 2021 Plan. As of March 31, 2026, 2,489,188 shares were available for issuance under the 2021 Plan.

2021 Employee Stock Purchase Plan

The Company’s 2021 Employee Stock Purchase Plan, or the 2021 ESPP, was approved by the Company’s board of directors on May 28, 2021 and the Company’s stockholders on June 17, 2021 and became effective on the date immediately prior to the date on which the registration statement for the Company’s IPO was declared effective. A total of 439,849 shares of the Company’s common stock were initially reserved for issuance under the 2021 ESPP. The shares available for issuance under the 2021 ESPP will be automatically increased on each January 1st, through January 1, 2031, by the least of (i) 439,849 shares of the Company’s common stock, (ii) 1% of the outstanding number of shares of the Company’s common stock on the immediately preceding December 31st or (iii) such lesser number of shares of the Company’s common stock as determined by the plan administrator of the 2021 ESPP. Effective January 1, 2026 the number of shares available under the 2021 ESPP automatically increased by 439,849 shares pursuant to the evergreen provision of the 2021 ESPP. As of March 31, 2026, 2,125,604 shares were available for issuance under the 2021 ESPP.

2026 Inducement Plan

The Company’s 2026 Inducement Plan, or the 2026 Plan, was approved by the Company’s board of directors on March 16, 2026 and became effective on the same date. The 2026 Plan provides for the grant of non-qualified stock options, stock appreciation rights, RSUs, restricted stock awards, unrestricted stock awards, and dividend equivalent rights exclusively to individuals who were not previously employees or directors of the Company, as an inducement material to the individuals' entry into employment with the Company and in accordance with the requirements of Nasdaq Stock Market Rule 5635(c)(4). The number of shares reserved for issuance under the 2026 Plan was 1,500,000. As of March 31, 2026, 1,500,000 shares were available for issuance under the 2026 Plan.

Stock option activity

The Company has granted stock options to employees, non-employee directors, and others under the 2021 Plan.

The following summarizes stock option activity:


	Number of options			Weighted average exercise price		Weighted average remaining contractual term (years)		Aggregate intrinsic value (in thousands)
Outstanding—December 31, 2025		14,064,599		$	7.74		7.2	$	115,245
Granted		2,569,325			15.46
Exercised		(574,839	)		7.87
Forfeited		(69,761	)		8.10
Outstanding—March 31, 2026		15,989,324		$	8.98		7.5	$	122,640
Vested or expected to vest—March 31, 2026		15,989,324		$	8.98		7.5	$	122,640
Exercisable—March 31, 2026		8,921,922		$	8.32		6.4	$	75,433

The aggregate intrinsic value of options granted is calculated as the difference between the exercise price of the options and the estimated fair value of the Company’s common stock.

Restricted stock unit activity

The Company has granted RSUs to employees under the 2021 Plan. Each of the RSUs represents the right to receive one share of the Company’s common stock upon vesting. The RSUs will typically vest over two or four years provided the individual remains in continuous service of the Company. Accordingly, stock-based compensation expense for each RSU is recognized on a straight-line basis over the vesting term. The fair value of each RSU is based on the closing price of the Company’s common stock on the date of grant.

The following summarizes RSU activity:


	Number of shares			Weighted average grant date fair value
Unvested restricted stock units as of December 31, 2025		775,765		$	7.05
Granted		568,550		$	15.46
Vested		(186,515	)	$	7.06
Forfeited		(8,788	)	$	8.84
Unvested restricted stock units as of March 31, 2026		1,149,012		$	11.20

The aggregate fair value of RSUs that vested during three months ended March 31, 2026 was $2.9 million. The weighted average grant date fair value of RSUs that vested during three months ended March 31, 2026 was $7.06 per share. No RSUs vested during the three months ended March 31, 2025.

Stock-based compensation expense

Stock-based compensation expense is classified as follows (in thousands):


	Three months ended March 31,
	2026		2025
Research and development	$	3,374	$	3,135
General and administrative		2,575		2,163
Total stock-based compensation expense	$	5,949	$	5,298

As of March 31, 2026 total unrecognized stock-based compensation cost related to unvested stock options and restricted stock units was $49.4 million and $12.0 million, respectively. The Company expects to recognize this remaining cost over a weighted average period of 2.7 years and 3.3 years, respectively.