0000950170-24-031150 | 10-K | XBRL Viewer | Monte Rosa Therapeutics INC

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Fair Value Measurements - Summary of Financial Assets Liabilities Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Current assets
Total assets measured at fair value	$ 236,420	$ 263,867
Level 1 [Member]
Current assets
Total assets measured at fair value	122,791	50,633
Level 2 [Member]
Current assets
Total assets measured at fair value	113,629	213,234
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	122,791	50,633
Money Market Funds [Member] \| Level 1 [Member]
Current assets
Total assets measured at fair value	122,791	50,633
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	9,317	5,320
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	9,317	5,320
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	79,816	127,351
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	79,816	127,351
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	24,496	80,563
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	24,496	80,563
US Treasury Securities [Member] \| Level 3 [Member]
Current assets
Total assets measured at fair value	$ 0	$ 0

Employee Retirement Plans - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Retirement Benefits [Abstract]
Company matching contributions to maximum employees eligible compensation	100.00%
Percentage of company's matching contribution with respect to each participant's contribution	4.00%
Total company contributions to 401 (k) plan	$ 0.6	$ 0.5

Combined and Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit
Balance (in shares) at Dec. 31, 2021		46,535,966
Balance, amount at Dec. 31, 2021	$ 347,515	$ 5	$ 471,566	$ (2,021)	$ (122,035)
Restricted common stock vesting, shares		136,058
Exercise of common stock options	439		439
Exercise of common stock options, shares		117,552
Stock-based compensation expense	11,664		11,664
Provision for pension benefit obligation	718			718
Issuance of common stock, net of issuance costs Shares		$ 2,482,008
Issuance of common stock, net of issuance costs	19,691		19,691
Unrealized loss on available-for-sale securities	(449)			(449)
Issuance of shares under employee stock purchase plan, Shares		51,947
Issuance of shares under employee stock purchase plan	336		336
Net Income (Loss)	(108,501)				(108,501)
Balance (in shares) at Dec. 31, 2022		49,323,531
Balance, amount at Dec. 31, 2022	271,413	$ 5	503,696	(1,752)	(230,536)
Restricted common stock vesting, shares		145,455
Exercise of common stock options	$ 2,030		2,030
Exercise of common stock options, shares	561,905	561,905
Stock-based compensation expense	$ 16,669		16,669
Provision for pension benefit obligation	(1,369)			(1,369)
Unrealized loss on available-for-sale securities	(397)			397
Issuance of shares under employee stock purchase plan, Shares		109,342
Issuance of shares under employee stock purchase plan	578		578
Issuance of pre-funded warrant, net of issuance costs	24,884		24,884
Net Income (Loss)	(135,352)				(135,352)
Balance (in shares) at Dec. 31, 2023		50,140,233
Balance, amount at Dec. 31, 2023	$ 179,250	$ 5	$ 547,857	$ (2,724)	$ (365,888)

Marketable securities

12 Months Ended

Dec. 31, 2023

Investments, Debt and Equity Securities [Abstract]

Marketable securities

4. Marketable securities

Marketable securities as of December 31, 2023 consisted of the following (in thousands):


	Amortized		Unrealized		Unrealized			Fair
	Cost		Gains		Losses			Value
Description
Corporate debt securities	$	79,870	$	4	$	(58	)		79,816
U.S Treasury securities		24,495		11		(10	)		24,496
Total	$	104,365	$	15	$	(68	)	$	104,312

Marketable securities as of December 31, 2022 consisted of the following (in thousands):


	Amortized		Unrealized		Unrealized			Fair
	Cost		Gains		Losses			Value
Description
Corporate debt securities	$	127,565	$	27	$	(241	)		127,351
U.S Treasury securities		80,798		2		(237	)		80,563
Total	$	208,363	$	29	$	(478	)	$	207,914

As of December 31, 2023, the Company held 28 marketable securities, 20 of which were in an unrealized loss position. The aggregate fair value of securities in a loss position was $72.9 million. As of December 31, 2022, the Company held 40 marketable securities, 31 of which were in an unrealized loss position. The aggregate fair value of securities in a loss position was $164.9 million. There were no individual securities that were in a significant unrealized loss position as of December 31, 2023 or 2022. The Company evaluates securities for other-than-temporary impairments based on quantitative and qualitative factors, and considers the decline in market value as of December 31, 2023 and 2022, to be primarily attributable to the then current economic and market conditions. The Company neither intends to sell these investments nor concludes that it is more-likely-than-not that the Company will have to sell them before recovery of their carrying values. The Company also believes that it will be able to collect both principal and interest amounts due to it at maturity.

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2023

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, 2022		7,436,339		$	9.14		8.5	$	12,440
Granted		3,388,425			7.36		—		—
Exercised		(561,905	)		3.61		—		—
Forfeited		(867,929	)		9.24		—		—
Outstanding—December 31, 2023		9,394,930		$	8.78		8.0	$	4,741
Vested or expected to vest—December 31, 2023		9,394,930		$	8.78		8.0	$	4,741
Exercisable—December 31, 2023		3,922,618		$	8.93		7.3	$	3,442

Schedule of Fair Value of each Award Estimated Using Assumption

The fair value of options granted were estimated using the following weighted-average assumptions:


	Year ended December 31,
	2023			2022
Expected term (years)		6.24			6.25
Expected volatility		82.72	%		78.82	%
Risk-free interest rate		3.95	%		2.02	%
Expected dividend yield		—	%		—	%

Schedule of Restricted Stock Award Activity

The following summarizes restricted stock activity:


	Number of shares			Weighted average grant date fair value
Unvested restricted stock as of December 31, 2022		122,271		$	1.04
Vested		(101,855	)	$	0.82
Forfeited		(5,720	)	$	2.00
Unvested restricted stock as of December 31, 2023		14,696		$	2.19

Schedule of Restricted Stock Unit Activity

The following summarizes restricted stock unit activity:


	Number of shares			Weighted average grant date fair value
Unvested restricted stock units as of December 31, 2022		91,000		$	10.11
Granted		206,665		$	7.55
Vested		(43,600	)	$	10.11
Forfeited		(17,546	)	$	8.41
Unvested as of December 31, 2023		236,519		$	8.00

Schedule of Stock Based Compensation Expense

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


	Year ended December 31,
	2023		2022
Research and development	$	8,939	$	5,582
General and administrative		7,730		6,082
Total stock-based compensation expense	$	16,669	$	11,664

Stock-based compensation - Schedule of Restricted Stock Unit Activity (Details)	12 Months Ended
	Dec. 31, 2023 $ / shares shares
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of options, forfeited	(867,929)
Restricted stock units
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of Outstanding Shares, Beginning Balance	91,000
Number of shares, Granted	206,665
Number of Shares, Vested	43,600
Number of options, forfeited	(17,546)
Number of shares, Unvested, ending balance	236,519
Weighted average grant date fair value, Granted \| $ / shares	$ 7.55
Weighted Average Grant Date Fair Value, Beginning Balance \| $ / shares	10.11
Weighted Average Grant Date Fair Value, Vested \| $ / shares	10.11
Weighted Average Grant Date Fair Value, Forfeited \| $ / shares	8.41
Weighted average grant date fair value, ending balance \| $ / shares	$ 8

Accrued Expenses And Other Current Liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Accounts Payable and Accrued Liabilities, Current [Abstract]
Compensation and benefits	$ 7,593	$ 5,624
Accrued research and development	5,336	3,936
Other	1,671	5,020
Total other current liabilities	$ 14,600	$ 14,580

Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Common stock, shares, issued	50,154,929	49,445,802
Research and development	$ 111,272	$ 85,061

Stock-Based Compensation - Summary of Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share-Based Payment Arrangement [Abstract]
Number of options, beginning balance	7,436,339
Number of options, granted	3,388,425
Number of options, exercised	(561,905)
Number of options, forfeited	(867,929)
Number of options, vested or expected to vest	9,394,930
Number of options, ending balance	9,394,930	7,436,339
Number of options, exercisable	3,922,618
Weighted average exercise price, beginning balance	$ 9.14
Weighted average exercise price, granted	7.36
Weighted average exercise price, exercised	3.61
Weighted average exercise price, forfeited	9.24
Weighted average exercise price, vested or expected to vest	8.78
Weighted average exercise price, ending balance	8.78	$ 9.14
Weighted average exercise price, exercisable	$ 8.93
Weighted average remaining contractual term (years)	8 years	8 years 6 months
Weighted average remaining contractual term (years), vested or expected to vest	8 years
Weighted average remaining contractual term (years), exercisable	7 years 3 months 18 days
Aggregate intrinsic value, beginning balance	$ 12,440
Aggregate intrinsic value, ending balance	4,741	$ 12,440
Aggregate intrinsic value, vested or expected to vest	4,741
Aggregate intrinsic value, exercisable	$ 3,442

Net loss per common share - Schedule of Earnings Per Share, Basic and Diluted (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Earnings Per Share [Abstract]
Net Income (Loss)	$ (135,352)	$ (108,501)
Net loss per share attributable to common stockholders - basic	$ (2.63)	$ (2.3)
Net loss per share attributable to common stockholders - diluted	$ (2.63)	$ (2.3)
Weighted-average number of shares outstanding used in computing net loss per common share - basic	51,396,961	47,227,370
Weighted-average number of shares outstanding used in computing net loss per common share - diluted	51,396,961	47,227,370

- Definition

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

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Summary of Significant Accounting Policies - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Summary Of Significant Accounting Policies [Line Items]
Restricted cash	$ 4,580	$ 5,278
Impairment of long-lived assets	0
Other comprehensive loss	1,000	300
Operating lease right-of-use assets	28,808	34,832
Security Deposits [Member]
Summary Of Significant Accounting Policies [Line Items]
Restricted cash	$ 4,600	$ 4,600

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Amount after tax and reclassification adjustments of other comprehensive income (loss).

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Income Taxes - Schedule of Domestic And Foreign Components of Net Loss (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Income Tax Disclosure [Abstract]
United States	$ (19,543)	$ (17,232)
Foreign	(115,471)	(91,269)
Net loss before income taxes	$ (135,014)	$ (108,501)

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

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Stock-Based Compensation - Schedule of Restricted Stock Award Activity (Detail) - Restricted Stock Awards	12 Months Ended
	Dec. 31, 2023 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Outstanding Shares, Beginning Balance \| shares	122,271
Number of Shares, Vested \| shares	(101,855)
Number of Shares, Forfeited \| shares	5,720
Number of shares, Unvested, ending balance \| shares	14,696
Weighted Average Grant Date Fair Value, Beginning Balance \| $ / shares	$ 1.04
Weighted Average Grant Date Fair Value, Vested \| $ / shares	0.82
Weighted Average Grant Date Fair Value, Forfeited \| $ / shares	2
Weighted average grant date fair value, ending balance \| $ / shares	$ 2.19

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

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Reference 26: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(iii)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 27: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(iv)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 28: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(v)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

+ Details

Equity (Additional Information) (Details) - USD ($) $ / shares in Units, $ in Thousands			1 Months Ended	12 Months Ended
	Oct. 30, 2023	Jul. 31, 2022	Oct. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Class Of Stock [Line Items]
Common stock, shares authorized				500,000,000	500,000,000
Common stock, shares, issued				50,154,929	49,445,802
Purchase price of stock				$ 0.0001	$ 0.0001
Common stock shares outstanding				50,140,233	49,323,531
Dividends declared				$ 0
Dividends paid				$ 0
Common stock, voting rights				one
Preferred stock, shares authorized				10,000,000	10,000,000
Preferred stock, par value				$ 0.0001	$ 0.0001
Preferred stock, shares Issued				0	0
Preferred Stock, Shares Outstanding				0	0
Jefferies LLC [Member]
Class Of Stock [Line Items]
Common stock, shares, issued during the period					2,482,008
Gross Proceeds from sale of Common Stock		$ 100,000			$ 19,700
Percentage of Commission payable to Related Party		3.00%
Other Ownership Interests, Offering Costs					$ 1,000
Pre-Funded Warrant [Member]
Class Of Stock [Line Items]
Number of securities purchase agreement warrants			10,000,400
Proceeds from Issuance Initial Public Offering	$ 24,900
Share excercisable price	$ 0.0001
Purchase price of stock	$ 2.4999
Offering Cost	$ 100
Restricted Stock Awards
Class Of Stock [Line Items]
Vesting term				4 years
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

Property and Equipment, net

12 Months Ended

Dec. 31, 2023

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment, net

5. Property and equipment, net

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


	December 31, 2023			December 31, 2022
Laboratory equipment	$	22,079		$	17,766
Computer hardware and software		1,052			499
Furniture and fixtures		1,099			388
Leasehold improvements		20,893			2,660
Construction in process		924			12,013
Total property and equipment, at cost	$	46,047		$	33,326
Less: accumulated depreciation		(12,244	)		(6,251	)
Property and equipment, net	$	33,803		$	27,075

Depreciation expense for the years ended December 31, 2023 and 2022 was $6.2 million and $3.7 million, respectively.

Property and Equipment, net - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Abstract]
Depreciation	$ 6,222	$ 3,745

Income Taxes

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Income Taxes

12. Income Taxes

The Company has incurred net operating losses for all the periods presented. The Company has not reflected the benefit of any such net operating loss carryforwards in the accompanying consolidated financial statements. Domestic and foreign components of net loss are as follows (in thousands):


	Year ended December 31,
	2023			2022
United States	$	(19,543	)	$	(17,232	)
Foreign		(115,471	)		(91,269	)
Net loss	$	(135,014	)	$	(108,501	)

The effective tax rate for the years ended December 31, 2023 and 2022 is different from the federal statutory rate primarily due to the valuation allowance against deferred tax assets as a result of insufficient sources of income. The reconciliation of the federal statutory income tax rate to the Company’s effective income tax rate is as follows:


	Year ended December 31,
	2023			2022
Income tax benefit at the federal statutory rate		21.0	%		21.0	%
State income taxes, net of federal benefit		6.2	%		6.2	%
Research and development tax credits		(0.1	)%		0.0	%
Foreign rate differential		(6.8	)%		(6.7	)%
Other		(0.7	)%		(0.7	)%
Change in valuation allowance		(19.5	)%		(19.8	)%
Total		0.1	%		0.0	%

Deferred income taxes reflect the net effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. The principal components of the Company’s deferred tax assets consisted of the following (in thousands):


	December 31,
	2023			2022
Deferred tax assets
Federal and state net operating loss carryforwards	$	41,888		$	26,136
Research and development tax credits		2,245			1,715
Capitalized research and development		3,679			1,151
Lease liability		12,403			13,173
Compensation related items		6,283			4,022
Other		147			149
Total deferred tax assets	$	66,645		$	46,346
Less: valuation allowance		(54,465	)		(33,084	)
Total net deferred tax assets	$	12,180		$	13,262
Deferred tax liabilities
Right-of-use asset		(7,573	)		(11,766	)
Defined benefit plan adjustment		(332	)		(375	)
Prepaid insurance		—			(252	)
Depreciation		(4,275	)		(869	)
Total deferred tax liabilities		(12,180	)		(13,262	)
Net deferred tax assets	$	—		$	—

The Company has incurred annual net operating losses in each year since inception. The Company has not reflected the benefit of any such net operating loss carryforwards in the financial statements. Due to the Company’s history of losses, and lack of other positive evidence, the Company has determined that it is more likely than not that its net deferred tax assets will not be realized, and therefore, the net deferred tax assets are fully offset by a valuation allowance at December 31, 2023 and 2022. The Company increased its valuation allowance by $21.4 million for the year ended December 31, 2023 in order to maintain a full valuation allowance against its deferred tax assets.

As of December 31, 2023, the Company had federal net operating loss carryforwards, or NOLs, of $0.5 million and federal tax credits of $1.0 million available to offset tax liabilities. The Company’s federal NOLs have an indefinite life and federal tax credit carryforwards begin to expire in 2040. The Company also had gross foreign

NOLs of $288.0 million that begin to expire in 2026. The Company also had gross state tax credits of $0.5 million which are available to offset state tax liabilities and begin to expire in 2034. Federal and state NOLs and tax credit carryforwards are also subject to annual limitations in the event that cumulative changes in the ownership interests of significant stockholders exceed 50% over a three-year period, as defined under Sections 382 and 383 of the Internal Revenue Code of 1986. The Company has not completed an analysis to determine if the NOLs and tax credits are limited due to a change in ownership. Should there be ownership changes that occurred, the Company’s ability to utilize existing carryforwards could be substantially restricted.

The Company determines its uncertain tax positions based on whether and how much of a tax benefit taken by the Company in its tax filings is more likely than not to be sustained upon examination by the relevant income tax authorities.

A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows (in thousands):


	Year ended December 31,
	2023			2022
Unrecognized tax benefits, beginning of year	$	2,235		$	—
Additions for tax positions of prior years		2,369			2,235
Reductions for tax provisions of prior years		(129	)		—
Unrecognized tax benefits, end of year	$	4,475		$	2,235

The Company recognizes interest and penalties related to unrecognized tax benefits in U.S. Federal, state, and foreign income tax expense. For the years ended December 31, 2023 and 2022, the unrecognized tax benefits generated was related to a reserve for the Federal and State Research and Development Credit. The Company had approximately $4.5 million and $2.2 million of unrecognized tax benefit as of December 31, 2023 and 2022, respectively.

The Company files income tax returns in the U.S., Switzerland and Massachusetts. The Company is not currently under examination by any taxing authority for any open tax year. Due to net operating loss carryforwards, all years remain open for income tax examination. To the extent the Company has tax attribute carryforwards, the tax years in which the attribute was generated may still be adjusted upon examination by the Internal Revenue Service, or IRS, or state tax authorities to the extent utilized in a future period. No federal, foreign, or state tax audits are currently in process.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480990/946-20-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(h)(2))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//740/tableOfContent

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-14

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 21
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-21

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 270
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482526/740-270-50-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 17
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-17

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 6.I.5.Q1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479360/740-10-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 11.C)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479360/740-10-S99-2

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482603/740-30-50-2

+ Details

Condensed Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Statement of Cash Flows [Abstract]
Issuance of common stock, net of underwriting discount	$ 620	$ 620

Collaboration and license agreements (Additional Information) (Details) - Collaboration and License Agreement [Member] - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Nov. 30, 2023	Dec. 31, 2023
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Non-Refundable Upfront Payment	$ 50.0
One Time Upfront Payment		$ 50.0
Upfront payment receive	28.0
Minimum [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Potential pre-clinical, clinical, commercial and sales milestones	1,000.0
Potential clinical, commercial and sales milestones	2,000.0
Pre-Clinical Milestones	$ 172.0

Employee Retirement Plans (Tables)

12 Months Ended

Dec. 31, 2023

Retirement Benefits [Abstract]

Schedule of Changes in Benefit Obligations, Plan Assets and Net Amount Recognized in Balance Sheets

The following table represents the changes in benefit obligations and plan assets and the net amount recognized on the consolidated balance sheets (in thousands):


	Year ended December 31,
	2023			2022
Change in benefit obligation:
Benefit obligation—beginning of period	$	6,851		$	5,975
Service cost employer		774			549
Contributions paid by employees		657			299
Interest cost		198			19
Contributions paid by plan participants		2,752			1,302
Benefits paid		(594	)		(452	)
Plan Amendment		(1,463	)		(67	)
Actuarial (gain) loss		2,854			(774	)
Benefit obligation—end of period	$	12,029		$	6,851
Change in plan assets:
Fair value of plan assets—beginning of period	$	5,318		$	3,799
Actual return on plan assets		(96	)		(240	)
Contributions paid by employer		1,279			610
Contributions paid by employees		657			299
Contributions paid by plan participants		2,752			1,302
Benefits paid		(594	)		(452	)
Fair value of plan assets—end of period	$	9,316		$	5,318
Defined benefit plan liability	$	2,713		$	1,533

Schedule of Net Pension Costs

The net pension costs was as follows (in thousands):


	Year ended December 31,
	2023		2022
Service cost	$	774	$	549
Interest cost		198		19
Net pension cost	$	972	$	568

Schedule of Provision for Defined Benefit Plan Obligation Recognized in Other Comprehensive Loss

The provision for pension benefit obligation recognized in other comprehensive loss was as follows (in thousands):


	Year ended December 31,
	2023			2022
Actuarial gain (loss) arising from experience adjustments	$	(1,614	)	$	774
Actuarial gain (loss) arising from changes in financial assumptions		(1,240	)		—
Defined benefit cost for the year recognized in other comprehensive loss	$	(2,854	)	$	774

Schedule of Assumptions Used to Measure Projected Benefit Obligation and Net Pension Costs

The assumptions used to measure the projected benefit obligation and net pension costs were as follows:


	Year ended December 31,
	2023	2022
Inflation rate	1.25%	1.25%
Discount rate	1.50%	2.30%
Interest rate on savings accounts	1.00%	1.00%
Expected rate of return on assets	1.50%	2.30%
Salary increase	1.25%	1.25%
Social Security increase	1.25%	1.25%
Pension increase	0.00%	0.00%
Retirement age	100% Male 65 Female 64	100% Male 65 Female 64
Mortality and disability rates	BVG 2020 Table	BVG 2020 Table

Schedule of Estimated Future Benefit Payments

Estimated benefit payments, which reflect future expected service, are expected to be paid as follows (in thousands):


	December 31,
2024	$	1,052
2025	$	1,075
2026	$	1,092
2027	$	1,106
2028	$	1,122
2029-2033	$	6,300

Net loss per common share - Schedule of Antidilutive Securities Excluded from Earnings Per Share Calculation (Detail) - shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Options to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of EPS	9,394,930	7,436,339
Restricted Stock Awards
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of EPS	14,696	122,271
Restricted Stock Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of EPS	236,519	91,000

Pay vs Performance Disclosure - USD ($) $ in Thousands	12 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Pay vs Performance Disclosure
Net Income (Loss)	$ (135,352)	$ (108,501)

- Definition

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

+ References

+ Details

Description of Business and Liquidity

12 Months Ended

Dec. 31, 2023

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 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 Corp. 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.

Risks and uncertainties

The Company is subject to risks common to companies in the biotechnology industry including, but not limited to, the successful discovery and development of its product candidates, new technological innovations, protection of proprietary technology, dependence on key personnel, compliance with government regulations and the need to obtain additional financing.

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 the issuance of convertible preferred shares and public offerings of the Company's common stock.

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 December 31, 2023, the Company had an accumulated deficit of $365.9 million. The Company has incurred losses and negative cash flows from operations since inception, including net losses of $135.4 million and $108.5 million for the years ended December 31, 2023 and 2022, respectively. 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 $232.4 million as of December 31, 2023, will be sufficient to fund operating expenses and capital requirements for at least 12 months from the date the consolidated financial statements are issued. However, additional funding will be necessary to fund future discovery research, pre-clinical 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, even the ability to continue operations.

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

Schedule of Property and Equipment Estimated Useful Life

Depreciation is calculated using the straight-line method over the estimated useful life of the asset as follows:


Asset	Estimated useful life
Laboratory equipment	Five years
Computer hardware	Three years
Furniture and fixtures	Five Years
Leasehold Improvements	Shorter of useful life or remaining lease term

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Schedule of Domestic And Foreign Components of Net Loss


	Year ended December 31,
	2023			2022
United States	$	(19,543	)	$	(17,232	)
Foreign		(115,471	)		(91,269	)
Net loss	$	(135,014	)	$	(108,501	)

Schedule of Reconciliation of Federal Statutory Income Tax Rate to Effective Income Tax Rate


	Year ended December 31,
	2023			2022
Income tax benefit at the federal statutory rate		21.0	%		21.0	%
State income taxes, net of federal benefit		6.2	%		6.2	%
Research and development tax credits		(0.1	)%		0.0	%
Foreign rate differential		(6.8	)%		(6.7	)%
Other		(0.7	)%		(0.7	)%
Change in valuation allowance		(19.5	)%		(19.8	)%
Total		0.1	%		0.0	%

Summary of Components of Deferred Tax Assets (Liabilities)


	December 31,
	2023			2022
Deferred tax assets
Federal and state net operating loss carryforwards	$	41,888		$	26,136
Research and development tax credits		2,245			1,715
Capitalized research and development		3,679			1,151
Lease liability		12,403			13,173
Compensation related items		6,283			4,022
Other		147			149
Total deferred tax assets	$	66,645		$	46,346
Less: valuation allowance		(54,465	)		(33,084	)
Total net deferred tax assets	$	12,180		$	13,262
Deferred tax liabilities
Right-of-use asset		(7,573	)		(11,766	)
Defined benefit plan adjustment		(332	)		(375	)
Prepaid insurance		—			(252	)
Depreciation		(4,275	)		(869	)
Total deferred tax liabilities		(12,180	)		(13,262	)
Net deferred tax assets	$	—		$	—

Summary of Income Tax Contingencies [Table Text Block]


	Year ended December 31,
	2023			2022
Unrecognized tax benefits, beginning of year	$	2,235		$	—
Additions for tax positions of prior years		2,369			2,235
Reductions for tax provisions of prior years		(129	)		—
Unrecognized tax benefits, end of year	$	4,475		$	2,235

Property and Equipment, net - Schedule of Property, Plant and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Property Plant And Equipment [Line Items]
Total property and equipment, at cost	$ 46,047	$ 33,326
Less: accumulated depreciation	(12,244)	(6,251)
Property and equipment, net	33,803	27,075
Laboratory Equipment
Property Plant And Equipment [Line Items]
Total property and equipment, at cost	22,079	17,766
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Total property and equipment, at cost	1,099	388
Computer Hardware and Software
Property Plant And Equipment [Line Items]
Total property and equipment, at cost	1,052	499
Leasehold Improvements
Property Plant And Equipment [Line Items]
Total property and equipment, at cost	20,893	2,660
Construction in Process
Property Plant And Equipment [Line Items]
Total property and equipment, at cost	$ 924	$ 12,013

Leases

12 Months Ended

Dec. 31, 2023

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 consolidated balance sheets. The Company has no finance leases as of December 31, 2023.

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.

Klybeck Lease

In March 2021, the Company entered into an operating lease agreement for office and lab space with Wincasa AG, or the landlord, that occupies approximately 21,422 square feet located at Klybeckstrasse 191, 4057 Basel, Basel-City, Switzerland. In April 2023, the Company and the Landlord amended the Klybeck Lease which increased the office and lab space square footage from 21,422 square feet to 44,685 square feet and extended the term of the lease through June 30, 2027. The amendment was accounted for as a lease modification and resulted in an increases to the related ROU asset and operating lease liability of $1.8 million.

Harrison Avenue Lease

In December 2021, the Company entered into a non-cancelable lease agreement for 63,327 square feet of office and laboratory space to support its expanding operations, or the Harrison Avenue Lease. 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. As of the lease commencement date, 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 $95.00 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.

Pursuant to the terms of the Harrison Avenue Lease, the landlord reimbursed the Company for $13 million of tenant improvements. The Company reduced the related ROU asset by the amounts reimbursed by the landlord and capitalized the leasehold improvements as fixed assets on the consolidated balance sheet.

The components of lease expense for the year ended December 31, 2023, are as follows (in thousands):


	Year ended December 31,
	2023		2022
Operating lease expense	$	7,141	$	6,924
Variable lease expense		2,317		1,898
Total lease expense	$	9,458	$	8,822

The variable lease expenses generally include common area maintenance and property taxes. Of the total lease expense recorded in the consolidated statements of operations and comprehensive income (loss), $7.9 million and $7.8 million were recorded within research and development expenses and $1.6 million and $1.0 million were recorded in general and administrative expenses for the years ended December 31, 2023 and 2022, respectively. There were no short-term lease costs in the years ended December 31, 2023 and 2022.

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


	December 31, 2023			December 31, 2022
Weighted average remaining lease term (years)		8.6			9.7
Weighted average discount rate		9.8	%		9.9	%

Supplemental cash flow information relating to the Company's leases for the year ended December 31, 2023 are as follows (in thousands):


	Year ended December 31,
	2023		2022
Right-of-use assets obtained in exchange for operating lease obligations	$	1,871	$	48,488
Cash paid for amounts included in the measurement of lease liabilities	$	2,995	$	1,654

The amortization of the ROU assets for the year ended December 31, 2023 and 2022 was $2.5 million and $3.3 million, respectively.

Future undiscounted lease payments under non-cancelable leases as of December 31, 2023 for each of the years ending December 31st are as follows (in thousands):


Undiscounted lease payments
2024	$	7,443
2025		7,743
2026		7,944
2027		7,655
2028		7,360
Thereafter		31,026
Total undiscounted minimum lease payments		69,171
Less: Imputed interest		(23,132	)
Total operating lease liability	$	46,039

Marketable securities (Additional Information) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($) Security	Dec. 31, 2022 USD ($) Security
Investments, Debt and Equity Securities [Abstract]
Debt Securities, Available-for-Sale, Unrealized Loss Position \| $	$ 72.9	$ 164.9
Number of marketable securities held \| Security	28	40

Stock-Based Compensation - Schedule of Stock Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 16,669	$ 11,664
Research and Development [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	8,939	5,582
General and Administrative [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 7,730	$ 6,082

- Definition

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

+ References

+ Details

Related parties - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Related Party Transaction [Line Items]
Research and development	$ 111,272	$ 85,061
General and administrative	$ 32,039	$ 27,323

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 128,101	$ 54,912
Marketable securities	104,312	207,914
Other receivables	505	7,656
Prepaid expenses and other current assets	3,294	4,444
Current restricted cash	0	960
Total current assets	236,212	275,886
Property and equipment, net	33,803	27,075
Operating lease right-of-use assets	28,808	34,832
Restricted cash, net of current	4,580	4,318
Other long-term assets	352	278
Total assets	303,755	342,389
Current liabilities:
Accounts payable	11,152	7,862
Accrued expenses and other current liabilities	14,600	14,580
Current deferred revenue	17,678	0
Current portion of operating lease liability	3,162	3,127
Total current liabilities	46,592	25,569
Deferred revenue, net of current	32,323	0
Defined benefit plan liability	2,713	1,533
Operating lease liability	42,877	43,874
Total liabilities	124,505	70,976
Commitments and contingencies
Stockholders equity (deficit)
Preferred stock, $0.0001 par value, 10,000,000 shares authorized, no shares issued and outstanding	0	0
Common stock, $0.0001 par value; 500,000,000 shares authorized, 50,154,929 shares issued and 50,140,233 shares outstanding as of December 31, 2023; and 500,000,000 shares authorized, 49,445,802 shares issued and 49,323,531 shares outstanding as of December 31, 2022	5	5
Additional paid-in capital	547,857	503,696
Accumulated other comprehensive loss	(2,724)	(1,752)
Accumulated deficit	(365,888)	(230,536)
Total stockholders' equity	179,250	271,413
Total liabilities and stockholders' equity	$ 303,755	$ 342,389

Commitments and Contingencies

12 Months Ended

Dec. 31, 2023

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 December 31, 2023, the Company is not a party to any litigation and does not have a contingency reserve established for any litigation liabilities.

Indemnification

The Company, as permitted under Delaware law and in accordance with its certification of incorporation and bylaws and pursuant to indemnification agreements with certain of its officers and directors, indemnifies its

officers and directors for certain events or occurrences, subject to certain limits, which the officer or director is or was serving at the Company’s request in such capacity.

The Company enters into certain types of contracts that contingently require the Company to indemnify various parties against claims from third parties. These contracts primarily relate to (i) the Company’s bylaws, under which the Company must indemnify directors and executive officers, and may indemnify other officers and employees, for liabilities arising out of their relationship, (ii) contracts under which the Company must indemnify directors and certain officers and consultants for liabilities arising out of their relationship, and (iii) procurement, service or license agreements under which the Company may be required to indemnify vendors, service providers or licensees for certain claims, including claims that may be brought against them arising from the Company’s acts or omissions with respect to the Company’s products, technology, intellectual property or services.

From time to time, the Company may receive indemnification claims under these contracts in the normal course of business. In the event that one or more of these matters were to result in a claim against the Company, an adverse outcome, including a judgment or settlement, may cause a material adverse effect on the Company’s future business, operating results or financial condition. As of December 31, 2023 and 2022, the Company was not aware of any claims under indemnification arrangements and does not expect significant claims related to these indemnification obligations and, consequently, concluded that the fair value of these obligations is negligible. Therefore, no related reserves have been established.

Employee Retirement Plans - Schedule of Changes in Benefit Obligations, Plan Assets and Net Amount Recognized in Balance Sheets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Change in benefit obligation:
Benefit obligation—beginning of period	$ 6,851	$ 5,975
Service cost employer	774	549
Contributions paid by employees	657	299
Interest cost	198	19
Contributions paid by plan participants	2,752	1,302
Benefits paid	(594)	(452)
Plan Amendment	(1,463)	(67)
Actuarial (gain) loss	2,854	(774)
Benefit obligation—end of period	12,029	6,851
Change in plan assets:
Fair value of plan assets—beginning of period	5,318	3,799
Actual return on plan assets	(96)	(240)
Contributions paid by employer	1,279	610
Contributions paid by employees	657	299
Contributions paid by plan participants	2,752	1,302
Benefits paid	(594)	(452)
Fair value of plan assets—end of period	9,316	5,318
Change in defined benefit plan liability	$ 2,713	$ 1,533

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

Risks And Uncertainties

Risks and uncertainties

Liquidity Consideration

Liquidity considerations

Basis of Presentation

Basis of presentation

The accompanying consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America, 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.

Use of Estimates

Use of estimates

The preparation of the consolidated financial statements in conformity with GAAP requires the Company to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements and reported amounts of expenses during the reporting periods. Actual results could differ from those estimates. On an ongoing basis, the Company evaluates its estimates, including those related to accrued research and development expenses, other long-lived assets, pension benefit obligation, stock-based compensation and the valuation of deferred tax assets. The Company bases its estimates using historical experience, Company forecasts and future plans, current economic conditions, and information from third-party professionals that management believes to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying value of assets and liabilities and recorded amounts of expenses that are not readily apparent from other sources and adjusts those estimates and assumptions when facts and circumstances dictate.

Currency and Currency Translation

Currency and currency translation

The consolidated financial statements are presented in U.S. dollars, the Company’s reporting currency. The functional currency of the Company’s wholly owned subsidiary, Monte Rosa Therapeutics AG, is the U.S. dollar. Adjustments that arise from exchange rate changes on transactions denominated in a currency other than the functional currency are included in foreign currency exchange gain (loss), net in the consolidated statements of operations.

Cash, Cash Equivalents and Restricted Cash

Cash, cash equivalents and restricted cash

The Company considers all highly liquid investments with original maturities at the date of purchase of three months or less to be cash equivalents. Cash and cash equivalents are stated at fair value and may include money market funds, U.S. Treasury and U.S. government-sponsored agency securities, corporate debt, commercial paper and certificates of deposit. The Company’s cash equivalents at December 31, 2023 and 2022 consist of bank demand deposits and money market fund investments.

The Company had restricted cash of $4.6 million as of December 31, 2023 and 2022, primarily related to security deposits on its leases for offices in Boston, Massachusetts and Basel, Switzerland.

Marketable Securities

Marketable securities

Investments in marketable securities are classified as available-for-sale. Available-for-sale securities are measured and reported at fair value using quoted prices in active markets for similar securities. Unrealized gains and losses on available-for-sale securities are reported as a separate component of stockholders’ equity. Premiums or discounts from par value are amortized to investment income over the life of the underlying investment. All of the Company’s available-for-sale securities are available to the Company for use in current operations. As a result, the Company classified all of these securities as current assets even though the stated maturity of some individual securities may be one year or more beyond the balance sheet date.

The cost of securities sold is determined on a specific identification basis, and realized gains and losses are included in other income (expense) within the consolidated statements of operations and comprehensive loss. If any adjustment is required to reflect a decline in the value of the investment that the Company considers to be “other than temporary”, the Company recognizes a charge to the consolidated statement of operations and comprehensive loss. No such adjustments were necessary during the periods presented.

Concentrations of Credit Risk and Off-Balance Sheet Risk

Concentrations of credit risk and off-balance sheet risk

Financial instruments that potentially subject the Company to a concentration of credit risk consist primarily of cash and cash equivalents. The Company has invested in cash and cash equivalents at December 31, 2023 and 2022, held in a financial institution that management believes is creditworthy. These deposits may exceed federally insured limits. The Company has not experienced any losses historically in these accounts and believes it in not exposed to significant credit risk in its cash and cash equivalents. The Company has no significant off-balance sheet concentrations of credit risk, such as foreign currency exchange contracts, option contracts, or other hedging arrangements.

Fair Value of Financial Instruments

Fair value of financial instruments

Assets and liabilities recorded at fair value on a recurring basis in the balance sheets are categorized based upon the level of judgment associated with the inputs used to measure their fair values. Fair value is defined as the exchange price that would be received for an asset or an exit price that would be paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market

participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The authoritative guidance on fair value measurements establishes a three-tier fair value hierarchy for disclosure of fair value measurements as follows:

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

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

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

To the extent that the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value instrument.

Property and Equipment

Property and equipment

Property and equipment are stated at cost, subject to adjustments for impairments, less accumulated depreciation. Purchased assets that are not yet in service are classified as construction-in-process and no depreciation expense is recorded. Depreciation is calculated using the straight-line method over the estimated useful life of the asset as follows:


Asset	Estimated useful life
Laboratory equipment	Five years
Computer hardware	Three years
Furniture and fixtures	Five Years
Leasehold Improvements	Shorter of useful life or remaining lease term

Maintenance and repairs that do not improve or extend the life of the respective asset are expensed as incurred. Upon disposal of an asset, the related cost and accumulated depreciation are removed from the accounts and any resulting gain or loss is included in the results of operations. Leasehold improvements are amortized over the shorter of the useful life or remaining term of the lease.

Impairment of Long-Lived Assets

Impairment of long-lived assets

The Company evaluates whether current facts or circumstances indicate that the carrying values of its long-lived assets may not be recoverable. If such facts or circumstances are determined to exist, an estimate of the undiscounted future cash flows of these assets is compared to the carrying value the assets to determine whether impairment exists. If the assets are determined to be impaired, the loss is measured based on the difference between the fair value and carrying value of the assets. No material impairment losses were recorded during the periods presented.

Research and Development Expenses

Research and development expenses

Research and development costs are expensed as incurred. The Company’s research and development expenses consist primarily of costs incurred for the research and development of its product candidates and include expenses incurred under agreements with consultants to conduct preclinical and clinical studies, costs to acquire supplies for preclinical and clinical studies, salaries and related personnel costs, including stock-based compensation, depreciation and other allocated facility-related and overhead expenses.

Accrued Research and Development Costs

Accrued research and development costs

The Company records accruals for estimated costs of discovery research activities, preclinical, and clinical studies. A portion of the Company’s research and development activities are conducted by third-party service providers. The financial terms of these contracts are subject to negotiation, which vary by contract and may result in payments that do not match the periods over which materials or services are provided. The Company accrues the costs incurred under the agreements based on an estimate of actual work completed in accordance with the agreements. In the event the Company makes advance payments for goods or services that will be used or rendered for future research and development activities, the payments are deferred and capitalized as a prepaid

expense and recognized as expense as the goods are received or the related services are rendered. Such payments are evaluated for current or long-term classification based on when they are expected to be realized. If the Company does not identify costs that have begun to be incurred or if the Company underestimates or overestimates the level of services performed or the costs of these services, actual expenses could differ from the Company’s estimates.

Share-Based Compensation

Stock-based compensation

Stock-based compensation expense related to stock options granted to employees, directors and non-employees is recognized based on the grant-date estimated fair values of the awards using the Black-Scholes option pricing model, or Black-Scholes. Stock-based compensation expense related to stock options and other stock based awards granted to employees and non-employees is recognized based on the grant-date fair value of the Company’s common stock. The value is recognized as expense ratably over the requisite service period, which is generally the vesting term of the award. For stock options with performance-based vesting conditions, the Company records the expense for these awards based upon the fair value of the awards on the date of grant and the number of shares expected to vest based on the terms of the underlying award agreement and the requisite service periods. The Company adjusts the expense for actual forfeitures as they occur. Stock-based compensation expense is classified in the accompanying consolidated statements of operations based on the function to which the related services are provided.

Income Taxes

Income taxes

The Company uses the liability method to account for income taxes. Under this method, deferred tax assets and liabilities are determined based on differences between the financial statement carrying amounts of existing assets and liabilities and their tax bases. Deferred tax assets and liabilities are measured using enacted tax rates applied to taxable income in the years in which those temporary differences are expected to be recovered or settled. A valuation allowance is established when necessary to reduce deferred tax assets to the amount expected to be realized.

The Company assesses the likelihood of deferred tax assets being realized. A valuation allowance is provided when it is more likely than not that some portion or all of a deferred tax asset will not be realized. In assessing the realizability of deferred tax assets, the Company considers whether it is more likely than not that some portion or all of the deferred tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which the temporary differences representing net future deductible amounts become deductible.

The Company files U.S. federal and state income tax returns, as well as Swiss income tax returns. The Company’s tax positions are subject to audit. Financial statement effects of uncertain tax positions are recognized when it is more likely than not, based on the technical merits of the position, that it will be sustained upon examination. The Company evaluates uncertain tax positions on a regular basis. The evaluations are based on a number of factors, including changes in facts and circumstances, changes in tax law, correspondence with tax authorities during the course of the audit, and effective settlement of audit issues. Interest and penalties related to unrecognized tax benefits are included within the provision for income tax. To date, the Company has not been subject to any interest and penalties.

Defined Pension Benefit Obligation

Defined pension benefit obligation

The Company maintains a mandatory pension for its employees in Switzerland through affiliation with the Swiss Life Collective BVG Foundation. All benefits in accordance with the regulations are reinsured in their entirety with Swiss Life Ltd within the framework of the corresponding contract. This plan is considered to be a defined benefit plan under GAAP.

The Company recognizes an asset for the plan’s overfunded status or a liability for the plan’s underfunded status in its consolidated balance sheets. Additionally, the Company measures the plan’s assets and obligations that determine its funded status as of the end of the year and recognizes the change in the funded status within the consolidated statements of operations and comprehensive loss.

The Company uses an actuarial valuation to determine its pension benefit costs and credits. The amounts calculated depend on a variety of key assumptions, including discount rates and expected return on plan assets. Details of the assumptions used to determine the net funded status are described in Note 13. The Company’s pension plan assets are assigned to their respective levels in the fair value hierarchy in accordance with the valuation principles described in the Fair Value of Financial Instruments section above.

Segments

Operating segments are defined as components of an entity for which separate financial information is available and that is regularly reviewed by the chief operating decision maker, or CODM, in deciding how to allocate resources to an individual segment and in assessing performance. The Company’s CODM is its chief executive officer. The Company manages its operations as a single segment for the purposes of assessing performance and making operating decisions.

Revenue recognition

On October 16, 2023, the Company entered into a Collaboration and License Agreement with Roche for the discovery, generation and research of compounds that may become product candidates. The Company’s arrangement with Roche includes promises related to licenses of intellectual property, research services and options to purchase additional goods and/or services. The Company recognizes revenue in accordance with ASC No. 606, Revenue from Contracts with Customers, or ASC 606. ASC 606 applies to all contracts with customers, except for certain contracts that are within the scope of other guidance. Accordingly, the Company recognizes revenue when its customer obtains control of the promised goods and/or services in an amount that reflects the consideration it expects to receive in exchange for those goods and/or services. To determine the appropriate amount of revenue to be recognized, the Company performs the following steps: (i) Identify the contract(s) with the customer, (ii) Identify the promised goods and/or services in the contract and determine which promised goods and/or services represent performance obligations, (iii) Measure the transaction price, (iv) Allocate the transaction price to the performance obligations in the contract and (v) Recognize revenue when (or as) each performance obligation is satisfied.

Pursuant to the guidance in ASC 606, the Company accounts for a contract with a customer that is within the scope of ASC 606 when all of the following criteria are met: (i) The arrangement has been approved by the parties and the parties are committed to perform their respective obligations, (ii) Each party’s rights regarding the goods and/or services to be transferred can be identified, (iii) The payment terms for the goods and/or services to be transferred can be identified, (iv) The arrangement has commercial substance and (v) Collection of substantially all of the consideration to which the Company will be entitled in exchange for the goods and/or services that will be transferred to the customer is probable.

The Company assesses the goods and/or services promised within a contract that contains multiple promises to evaluate which promises are distinct. Promises are considered to be distinct and therefore, accounted for as separate performance obligations, provided that: (i) The customer can benefit from the good or service either on its own or together with other resources that are readily available to the customer and (ii) The promise to transfer the good or service to the customer is separately identifiable from other promises in the contract. The Company determines that a customer can benefit from a good or service if it could be used, consumed, or sold for an amount that is greater than scrap value, or otherwise held in a way that generates economic benefits. Factors that are considered in determining whether or not two or more promises are not separately identifiable include, but are not limited to, the following: (i) The Company provides a significant service of integrating goods and/or services with other goods and/or services promised in the contract, (ii) One or more of the goods and/or services significantly modifies or customizes, or are significantly modified or customized by, one or more of the other goods and/or services promised in the contract and (iii) The goods and/or services are highly interdependent or highly interrelated. In assessing whether promised goods and/or services are distinct from the other promises, the Company considers factors such as the stage of development of the underlying intellectual property, the capabilities of the collaborative partner and the availability of the associated expertise in the marketplace. The Company also considers whether the customer can benefit from a promise for its intended purpose without the receipt of the remaining promises, whether the value of a promise is dependent on the unsatisfied promises, whether there are other vendors that could provide the remaining promises and whether a promise is separately identifiable from the remaining promises. Individual goods or services (or bundles of goods and/or services) that meet both criteria for being distinct are accounted for as separate performance obligations. Promises that are not distinct at contract inception are combined into a single performance obligation.

The Company considers a customer’s right to elect to obtain additional goods and/or services at such customer’s discretion to be an option if it is not presently obligated to provide the goods and/or services and it is not entitled to compensation in exchange for the associated goods and/or services. Options to acquire additional goods and/or services are evaluated to determine if the option provides a material right to the customer that it would not have received without entering into the contract. If so, the option is accounted for as a separate performance obligation. If not, the option is considered a marketing offer which would be accounted for as a separate contract upon the customer’s exercise. Situations in which a customer has an ability to acquire additional goods and/or

services for free or at significantly discounted rates are considered to provide the customer with a material right. Options to purchase goods and/or services at prices that reflect the standalone selling prices of the associated goods and/or services are accounted for as marketing offers.

The Company’s arrangement with Roche provides for payments of the following: (i) Non-refundable, up-front fee, (ii) Research, development, regulatory and first sale milestones, (iii) Sales-based milestones, (iv) Royalties on net sales of licensed products and (v) Customer option fees for additional goods and/or services. Accordingly, the transaction price is comprised of a fixed fee due a specified number of days from contract execution and an estimate of variable consideration. The Company measures the transaction price based on the amount of consideration to which it expects to be entitled in exchange for transferring the promised goods and/or services to the customer. The Company utilizes either the expected value method or the most likely amount method to estimate the amount of variable consideration, depending on which method is expected to better predict the amount of consideration to which it will be entitled. Amounts of variable consideration are included in the transaction price to the extent that it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is subsequently resolved. There is considerable judgment involved in determining whether it is probable that a significant revenue reversal would not occur. With respect to research, development, regulatory and first sale milestone payments, at the inception of the arrangement, the Company evaluates whether the associated event is considered probable of achievement and estimates the amount to be included in the transaction price using the most likely amount method. As part of the evaluation for research and development milestone payments, the Company considers several factors, including the stage of development of the targets included in the arrangement, the risk associated with the remaining research and development work required to achieve the particular milestone and whether or not the achievement of the specific milestone event is within the Company’s control. Milestone events that are not within the control of the Company or the licensee, such as those dependent upon receipt of regulatory approval or the first sale of a commercialized product, are not considered to be probable of achievement until the triggering event occurs. With respect to royalties, including milestone payments based upon the achievement of a certain level of product sales, wherein the license is deemed to be the sole or predominant item to which the payments relate, the Company recognizes revenue upon the later of: (i) When the related sales occur or (ii) When the performance obligation to which some or all of the payment has been allocated has been satisfied (or partially satisfied). To date, the Company has not recognized any research, development, regulatory or sales-based milestone payments or royalty revenue resulting from its collaboration arrangement.

The Company updates its assessment of the estimated transaction price, including the constraint on variable consideration, at the end of each reporting period and as uncertain events are resolved or other changes in circumstances occur. Any adjustments to the transaction price are recorded on a cumulative catch-up basis, which affect revenue and net loss in the period of adjustment. Amounts to be received with respect to customer options are included in the transaction price upon exercise. And payments associated with milestone events that may only be achieved after the exercise of a customer option are excluded from the initial determination of the transaction price.

The Company generally allocates the transaction price to each performance obligation identified in the contract on a relative standalone selling price basis. However, certain components of variable consideration are allocated specifically to one or more particular performance obligations to the extent both of the following criteria are met: (i) The terms of the payment relate specifically to the efforts to satisfy the performance obligation or transfer the distinct good or service and (ii) Allocating the variable amount of consideration entirely to the performance obligation or the distinct good or service is consistent with the allocation objective of the standard whereby the amount allocated depicts the amount of consideration to which the entity expects to be entitled in exchange for transferring the promised goods or services. Option exercise fees are allocated to the goods and/or services underlying the associated option. The Company develops assumptions that require judgment to determine the standalone selling price for each performance obligation identified in the contract. The key assumptions utilized in determining the standalone selling price for each performance obligation include projected development timelines, estimated research costs, likelihood of exercise and probabilities of technical success.

Revenue is recognized based on the amount of the transaction price that is allocated to each respective performance obligation when or as the performance obligation is satisfied by transferring a promised good and/or service to the customer. For performance obligations that are satisfied at a point in time, the Company recognizes revenue when control of the goods and/or services are transferred to the customer. For performance obligations that are satisfied over time, the Company recognizes revenue by measuring the progress toward complete satisfaction of the performance obligation using a single method of measuring progress which depicts the performance in transferring control of the associated goods and/or services to the customer. The Company uses

input methods to measure the progress toward the complete satisfaction of performance obligations satisfied over time. With respect to promises related to licenses to intellectual property that is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenue from amounts allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. For licenses that are bundled with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. Any such adjustments are recorded on a cumulative catch-up basis, which affect revenue and net loss in the period of adjustment. Amounts allocated to material rights are recognized as revenue the earlier of: (i) When or as the option is exercised and the underlying future goods and/or services are transferred or (ii) When the option expires.

Significant judgments and estimates made in accounting for contracts with customers include: identifying the performance obligations in the contract, measuring the amount of variable consideration to include in the transaction price, estimating the standalone selling prices of the individual performance obligations, assessing the nature of a combined performance obligation to determine whether control is transferred over time or at a point in time, selecting the appropriate method of measuring progress used to recognize revenue for performance obligations satisfied over time and updating measures of progress to reflect revisions in the outcome of performance obligations. Certain of these judgments and estimates are subject to change over the course of the arrangement, particularly with respect to estimating variable consideration and updating the measure of progress, which would impact the revenue recognized. Significant changes in these assumptions and estimates could have a material impact on the timing and amount of revenue recognized in future periods.

The Company receives payments from its licensee based on billing schedules established in the contract. Amounts received or due prior to the Company performing its obligations under the arrangement are recorded as deferred revenue. Amounts expected to be recognized as revenue within the 12 months following the balance sheet date are classified as current deferred revenue. Amounts not expected to be recognized as revenue within the 12 months following the balance sheet date are classified as deferred revenue, net of current portion. Amounts payable to the Company are recorded as accounts receivable when the Company’s right to the consideration is unconditional.

Warrants

The Company accounts for common stock warrants as either equity-classified or liability-classified instruments based on an assessment of the warrant’s specific terms and applicable authoritative guidance in ASC 480, Distinguishing Liabilities from Equity, or ASC 480, and ASC 815, Derivatives and Hedging, or ASC 815. The assessment considers whether the warrants are freestanding financial instruments pursuant to ASC 480, whether the warrants meet the definition of a liability pursuant to ASC 480, and whether the warrants meet all of the requirements for equity classification under ASC 815, including whether the warrants are indexed to the Company’s own common stock and whether the warrant holders could potentially require “net cash settlement” in a circumstance outside of the Company’s control, among other conditions for equity classification. This assessment, which requires the use of professional judgment, is conducted at the time of warrant issuance and as of each subsequent quarterly period end date while the warrants are outstanding.

For issued or modified warrants that meet all of the criteria for equity classification, the warrants are required to be recorded as a component of additional paid-in capital at the time of issuance. For issued or modified warrants that do not meet all the criteria for equity classification, the warrants are required to be recorded at their initial fair value on the date of issuance and remeasured each balance sheet date thereafter. Changes in the estimated fair value of the liability-classified warrants are recognized as a non-cash gain or loss in the accompanying consolidated statements of operations and comprehensive loss.

Comprehensive income (loss)

Comprehensive income (loss) is defined as the change in equity of a business enterprise during a period from transactions and other events and circumstances from non-owner sources. The Company’s other comprehensive income (loss) includes adjustments to unrecognized pension benefit costs for Monte Rosa Therapeutics AG and changes in unrealized gains and losses from available-for-sale investments. The Company reported other comprehensive loss of $1.0 million for the year ended December 31, 2023 and other comprehensive income of $0.3 million for the year ended December 31, 2022.

Recently Adopted 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 (JOBS Act).

In August 2020, the FASB issued ASU No. 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging Contracts in Entity s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity. ASU 2020-06 will simplify the accounting for convertible instruments by reducing the number of accounting models for convertible debt instruments and convertible preferred stock. Limiting the accounting models results in fewer embedded conversion features being separately recognized from the host contract as compared with current GAAP. Convertible instruments that continue to be subject to separation models are (i) those with embedded conversion features that are not clearly and closely related to the host contract, that meet the definition of a derivative, and that do not qualify for a scope exception from derivative accounting and (ii) convertible debt instruments issued with substantial premiums for which the premiums are recorded as paid-in capital. ASU 2020-06 also amends the guidance for the derivatives scope exception for contracts in an entity’s own equity to reduce form-over-substance-based accounting conclusions. ASU 2020-06 will be effective for the Company beginning after December 15, 2023. Early adoption is permitted, but no earlier than fiscal years beginning after December 15, 2020, including interim periods within those fiscal years. The Company does not expect for ASU 2020-06 to have a material impact on its financial statements.

In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures, which is intended to provide enhanced segment disclosures. The standard will require disclosures about significant segment expenses and other segment items and identifying the Chief Operating Decision Maker and how they use the reported segment profitability measures to assess segment performance and allocate resources. These enhanced disclosures are required for all entities on an interim and annual basis, even if they have only a single reportable segment. The standard is effective for years beginning after December 15, 2023, and interim periods within annual periods beginning after December 15, 2024 and early adoption is permitted. The Company is evaluating this standard to determine if adoption will have a material impact on the Company’s consolidated financial statements.

In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures, which is intended to provide enhancements to annual income tax disclosures. The standard will require more detailed information in the rate reconciliation table and for income taxes paid, among other enhancements. The standard is effective for years beginning after December 15, 2024 and early adoption is permitted. The Company is evaluating this standard to determine if adoption will have a material impact on the Company’s consolidated financial statements.

Recently adopted accounting pronouncements

In June 2016, the FASB issued Accounting Standards Update No. 2016-13, Financial Instruments-Credit Losses: Measurement of Credit Losses on Financial Instruments. ASU 2016-13 requires measurement and recognition of expected credit losses for financial assets. In April 2019, the FASB issued clarification to ASU 2016-13 within ASU 2019-04, Codification Improvements to Topic 326, Financial Instruments-Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments, or ASU 2016-13. The guidance is effective for fiscal years beginning after December 15, 2022. The Company adopted ASU 2016-13 on January 1, 2023. The adoption of the standard was immaterial to the accompanying consolidated financial statements.

Combined and Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Net issuance costs	$ 116	$ 984

Employee Retirement Plans - Schedule of Net Pension Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Retirement Benefits [Abstract]
Service cost employer	$ 774	$ 549
Interest cost	198	19
Net pension cost	$ 972	$ 568

Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Operating expenses:
Research and development	$ 111,272	$ 85,061
General and administrative	32,039	27,323
Total operating expenses	143,311	112,384
Loss from operations	(143,311)	(112,384)
Other income (expense):
Interest income	9,334	3,764
Foreign currency exchange gain (loss), net	(930)	10
Gain on disposal of fixed assets	24	109
Loss on sale of marketable securities	(131)	0
Total other income	8,297	3,883
Net loss before income taxes	(135,014)	(108,501)
Provision for income taxes	(338)	0
Net loss	$ (135,352)	$ (108,501)
Net loss per share attributable to common stockholders - basic	$ (2.63)	$ (2.3)
Net loss per share attributable to common stockholders - diluted	$ (2.63)	$ (2.3)
Weighted-average number of shares outstanding used in computing net loss per common share - basic	51,396,961	47,227,370
Weighted-average number of shares outstanding used in computing net loss per common share - diluted	51,396,961	47,227,370
Comprehensive loss:
Net Income (Loss)	$ (135,352)	$ (108,501)
Other comprehensive gain (loss):
Provision for pension benefit obligation	(1,369)	718
Unrealized gain (loss) on available-for-sale securities	397	(449)
Comprehensive loss	$ (136,324)	$ (108,232)

Net loss per common share (Tables)

12 Months Ended

Dec. 31, 2023

Earnings Per Share [Abstract]

Schedule of Earnings Per Share, Basic and Diluted

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


	Year ended December 31,
	2023			2022
Net loss	$	(135,352	)	$	(108,501	)
Net loss per share attributable to common stockholders—basic and diluted	$	(2.63	)	$	(2.30	)
Weighted-average number of common shares used in computing net loss per share—basic and diluted		51,396,961			47,227,370

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 per common share, as their effect is anti-dilutive:


	December 31,		December 31,
	2023		2022
Stock options to purchase common stock		9,394,930		7,436,339
Restricted common stock		14,696		122,271
Restricted stock units		236,519		91,000

Stock-based Compensation

12 Months Ended

Dec. 31, 2023

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 effectiveness of the 2021 Plan (as defined below), no further issuances will be made under the 2020 plan.

2021 Stock 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 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, 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, which will be automatically increased on 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 determined by the Company’s compensation, nomination and corporate governance committee. As of December 31, 2023, 3,323,465 shares of common stock were available for issuance under 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 which 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 31 or (iii) such lesser number of shares of the Company’s common stock as determined by the plan administrator of the 2021 ESPP. As of December 31, 2023, 1,158,258 shares of common stock remained available for issuance under the 2021 ESPP.

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, 2022		7,436,339		$	9.14		8.5	$	12,440
Granted		3,388,425			7.36		—		—
Exercised		(561,905	)		3.61		—		—
Forfeited		(867,929	)		9.24		—		—
Outstanding—December 31, 2023		9,394,930		$	8.78		8.0	$	4,741
Vested or expected to vest—December 31, 2023		9,394,930		$	8.78		8.0	$	4,741
Exercisable—December 31, 2023		3,922,618		$	8.93		7.3	$	3,442

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. The weighted average grant date fair value of options granted in during the years ended December 31, 2023 and 2022 was $5.40 and $8.44 per share, respectively.

Fair value of stock option awards

The Company estimates the fair value of stock option awards on the grant date using Black-Scholes. The fair value of options granted were estimated using the following weighted-average assumptions:


	Year ended December 31,
	2023			2022
Expected term (years)		6.24			6.25
Expected volatility		82.72	%		78.82	%
Risk-free interest rate		3.95	%		2.02	%
Expected dividend yield		—	%		—	%

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

Expected term: The Company’s expected term represents the period that options are expected to be outstanding and is determined using the simplified method. The Company does not have sufficient historical data to use any other method to estimate expected term.

Expected volatility: The Company has limited information on the volatility of stock options as the shares were not actively traded on any public markets prior to June 24, 2021. The expected volatility was derived from historical stock volatilities of comparable peer public companies within its industry based on their similarities to the Company, including life cycle stage, therapeutic focus and size over a period equivalent to the expected term of the stock-based awards.

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

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

Restricted stock award activity

Unvested restricted stock awards, or RSAs, as of December 31, 2023 and 2022, were granted to employees under the 2020 Plan. Restricted stock awards generally vest over a four year period provided the individual remains in continuous service of the Company.

The following summarizes restricted stock activity:


	Number of shares			Weighted average grant date fair value
Unvested restricted stock as of December 31, 2022		122,271		$	1.04
Vested		(101,855	)	$	0.82
Forfeited		(5,720	)	$	2.00
Unvested restricted stock as of December 31, 2023		14,696		$	2.19

The aggregate fair value of restricted stock that vested during the year ended December 31, 2023 and 2022 was $0.7 million and $1.5 million, respectively. The weighted average grant date fair value of restricted stock that vested during the year ended December 31, 2023 and 2022 was $0.82 and $0.78 per share, respectively.

Restricted stock unit activity

Starting in 2022, the Company granted restricted stock units, or 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 granted over two 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 restricted stock unit activity:


	Number of shares			Weighted average grant date fair value
Unvested restricted stock units as of December 31, 2022		91,000		$	10.11
Granted		206,665		$	7.55
Vested		(43,600	)	$	10.11
Forfeited		(17,546	)	$	8.41
Unvested as of December 31, 2023		236,519		$	8.00

The aggregate fair value of restricted stock that vested during the year ended December 31, 2023 was $0.3 million. The weighted average grant date fair value of restricted stock that vested during the year was $10.11 per share. No RSUs vested during the year ended December 31, 2022.

Stock-based compensation expense

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


	Year ended December 31,
	2023		2022
Research and development	$	8,939	$	5,582
General and administrative		7,730		6,082
Total stock-based compensation expense	$	16,669	$	11,664

As of December 31, 2023, total unrecognized stock–based compensation cost related to unvested stock options and restricted stock units was $33.8 million and $1.3 million, respectively. The Company expects to recognize this remaining cost over a weighted average period of 2.4 years and 1.3 years, respectively. Total unrecognized stock-based compensation cost related to unvested restricted stock awards is immaterial.

Employee Retirement Plans - Schedule of Provision for Defined Benefit Plan Obligation Recognized in Other Comprehensive Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Retirement Benefits [Abstract]
Actuarial gain (loss) arising from experience adjustments	$ (1,614)	$ 774
Actuarial gain (loss) arising from changes in financial assumptions	(1,240)	0
Defined benefit cost for the year recognized in other comprehensive loss	$ (2,854)	$ 774

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Dec. 31, 2023 shares
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false
Owen Wallace [Member]
Trading Arrangements, by Individual
Name	Owen Wallace
Title	Chief Scientific Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	December 8, 2023
Termination Date	March 1, 2025
Aggregate Available	100,000

Income Taxes - Schedule of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Unrecognized Tax Benefits, Beginning Balance	$ 2,235	$ 0
Additions for tax positions of prior years	2,369	2,235
Reductions for tax provisions of prior years	(129)	0
Unrecognized Tax Benefits, Ending Balance	$ 4,475	$ 2,235

Collaboration and license agreements

12 Months Ended

Dec. 31, 2023

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 Rose Therapeutics AG, a wholly-owned subsidiary of Monte Rosa Therapeutics, Inc, or the Company, entered into a collaboration and license agreement with Roche. Pursuant to the 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 platform for an initial set of targets in oncology and neuroscience selected by Roche, with Roche having an option to expand the collaboration to include additional option targets, wherein a certain number of targets selected by Roche are subject to replacement rights owned by Roche. The Company will lead pre-clinical discovery and research activities with Roche leading late pre-clinical and clinical development activities.

Under the 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 Agreement will be overseen by a joint research committee.

Unless earlier terminated, the Agreement will remain in effect for each product licensed under the Agreement until expiration of the royalty term for the applicable product. The parties have included termination provisions in the agreement, allowing termination of the 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 agreement, the Company expects to be entitled to receive from Roche certain variable consideration including potential pre-clinical milestones up to $172 million, and potential clinical, commercial and sales milestones exceeding $2 billion. For the additional option targets, upon Roche’s exercise of their option, the Company is entitled to receive an upfront payment of up to $28 million and potential pre-clinical, clinical, commercial and sales milestones exceeding $1 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.

As of December 31, 2023 the Company is not entitled to any of the variable consideration because all of such payments are due subsequent to the exercise of Roche's options.

Accounting

This agreement represents a transaction with a customer and therefore is accounted for under ASC 606.

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

•

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 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: The transaction price allocated to the options 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 an option right, the Company will recognize the portion of the transaction price allocated using the input method described above. Any payments made to exercise option rights will be added to the allocated value and recognized as the related services are performed.

The transaction price is determined to be $50.0 million upfront payment received in November 2023. As of December 31, 2023, the $50.0 million upfront payment is recorded as deferred revenue in the liabilities section of the consolidated balance sheets. No customer options had been exercised through December 31, 2023.

Net loss per common share

12 Months Ended

Dec. 31, 2023

Earnings Per Share [Abstract]

Net Loss Per Common Share

14. Net loss per common share

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


	Year ended December 31,
	2023			2022
Net loss	$	(135,352	)	$	(108,501	)
Net loss per share attributable to common stockholders—basic and diluted	$	(2.63	)	$	(2.30	)
Weighted-average number of common shares used in computing net loss per share—basic and diluted		51,396,961			47,227,370

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


	December 31,		December 31,
	2023		2022
Stock options to purchase common stock		9,394,930		7,436,339
Restricted common stock		14,696		122,271
Restricted stock units		236,519		91,000

Leases - Schedule of components of lease expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Leases [Abstract]
Operating lease expense	$ 7,141	$ 6,924
Variable lease expense	2,317	1,898
Total lease expense	$ 9,458	$ 8,822

Income Taxes - Schedule of Reconciliation of Federal Statutory Income Tax Rate to Effective Income Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Income tax benefit at the federal statutory rate	21.00%	21.00%
State income taxes, net of federal benefit	6.20%	6.20%
Research and development tax credits	0.10%	0.00%
Foreign rate differential	(6.80%)	(6.70%)
Other	(0.70%)	(0.70%)
Change in valuation allowance	(19.50%)	(19.80%)
Total	0.10%	0.00%

Accrued expenses and other current liabilities

12 Months Ended

Dec. 31, 2023

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):


	December 31,		December 31,
	2023		2022
Compensation and benefits	$	7,593	$	5,624
Accrued research and development		5,336		3,936
Other		1,671		5,020
Total other current liabilities	$	14,600	$	14,580

Stock-Based Compensation - Schedule of Fair Value of each Award Estimated Using Assumption (Detail)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share-Based Payment Arrangement [Abstract]
Expected term (years)	6 years 2 months 26 days	6 years 3 months
Expected volatility	82.72%	78.82%
Risk-free interest rate	3.95%	2.02%
Expected dividend yield	0.00%	0.00%

Employee Retirement Plans - Schedule of Assumptions Used to Measure Projected Benefit Obligation and Net Pension Costs (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Retirement Benefits [Abstract]
Inflation rate%	1.25%	1.25%
Discount rate%	1.50%	2.30%
Interest rate on savings accounts%	1.00%	1.00%
Expected rate of return on assets%	1.50%	2.30%
Salary increase%	1.25%	1.25%
Social Security increase%	1.25%	1.25%
Pension increase%	0.00%	0.00%
Retirement age	100% Male 65 Female 64	100% Male 65 Female 64
Mortality and disability rates	BVG 2020 Table	BVG 2020 Table

Description of Business and Liquidity - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Subsidiary Or Equity Method Investee [Line Items]
Common stock, shares, issued	50,154,929	49,445,802
Common stock, par or stated value per share	$ 0.0001	$ 0.0001
Proceeds from issuance of common stock, net of underwriting discount of $620	$ 0	$ 20,055
Accumulated deficit	(365,888)	(230,536)
Net Income (Loss)	(135,352)	(108,501)
Restricted Cash and Cash Equivalents	232,400
Cash and cash equivalents and restricted cash	$ 132,681	$ 60,190	$ 351,409

- 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 - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average grant fair value, granted	$ 5.4	$ 8.44
Restricted Stock Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average grant fair value, granted	$ 0.82	$ 0.78
Aggregate fair value of restricted stock vested	$ 0.7	$ 1.5
Unrecognized stock based compensation cost, units	$ 1.3
Expected remaining cost, weighted average period, units	1 year 3 months 18 days
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average grant fair value, granted		$ 10.11
Aggregate fair value of restricted stock vested	$ 0.3
Unvested Stock Option [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized stock based compensation cost	$ 33.8
Weighted average remaining period	2 years 4 months 24 days
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%
Issuance of common stock	3,323,465
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%
Issuance of common stock	1,158,258
Number of share increase	439,849

Employee Retirement Plans

12 Months Ended

Dec. 31, 2023

Retirement Benefits [Abstract]

Employee Retirement Plans

13. Employee retirement plans

Defined benefit plan

The Company, in compliance with Swiss Law, is contracted with the Swiss Life Collective BVG Foundation for the provision of pension benefits. All benefits are reinsured in their entirety with Swiss Life Ltd within the framework of the contract.

The technical administration and management of the savings account are guaranteed by Swiss Life on behalf of the collective foundation. Insurance benefits due are paid directly to the entitled persons by Swiss Life in the name of and for the account of the collective foundation. The pension plan is financed by contributions of both employees and employer.

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 or by mandated parties. The risks of disability, death and longevity are reinsured in their entirety with Swiss Life Ltd.

The following table represents the changes in benefit obligations and plan assets and the net amount recognized on the consolidated balance sheets (in thousands):


	Year ended December 31,
	2023			2022
Change in benefit obligation:
Benefit obligation—beginning of period	$	6,851		$	5,975
Service cost employer		774			549
Contributions paid by employees		657			299
Interest cost		198			19
Contributions paid by plan participants		2,752			1,302
Benefits paid		(594	)		(452	)
Plan Amendment		(1,463	)		(67	)
Actuarial (gain) loss		2,854			(774	)
Benefit obligation—end of period	$	12,029		$	6,851
Change in plan assets:
Fair value of plan assets—beginning of period	$	5,318		$	3,799
Actual return on plan assets		(96	)		(240	)
Contributions paid by employer		1,279			610
Contributions paid by employees		657			299
Contributions paid by plan participants		2,752			1,302
Benefits paid		(594	)		(452	)
Fair value of plan assets—end of period	$	9,316		$	5,318
Defined benefit plan liability	$	2,713		$	1,533

The net pension costs was as follows (in thousands):


	Year ended December 31,
	2023		2022
Service cost	$	774	$	549
Interest cost		198		19
Net pension cost	$	972	$	568

The provision for pension benefit obligation recognized in other comprehensive loss was as follows (in thousands):


	Year ended December 31,
	2023			2022
Actuarial gain (loss) arising from experience adjustments	$	(1,614	)	$	774
Actuarial gain (loss) arising from changes in financial assumptions		(1,240	)		—
Defined benefit cost for the year recognized in other comprehensive loss	$	(2,854	)	$	774

The assumptions used to measure the projected benefit obligation and net pension costs were as follows:


	Year ended December 31,
	2023	2022
Inflation rate	1.25%	1.25%
Discount rate	1.50%	2.30%
Interest rate on savings accounts	1.00%	1.00%
Expected rate of return on assets	1.50%	2.30%
Salary increase	1.25%	1.25%
Social Security increase	1.25%	1.25%
Pension increase	0.00%	0.00%
Retirement age	100% Male 65 Female 64	100% Male 65 Female 64
Mortality and disability rates	BVG 2020 Table	BVG 2020 Table

Estimated benefit payments, which reflect future expected service, are expected to be paid as follows (in thousands):


	December 31,
2024	$	1,052
2025	$	1,075
2026	$	1,092
2027	$	1,106
2028	$	1,122
2029-2033	$	6,300

Defined contribution plan

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. The Company recorded $0.6 million and $0.5 million matching 401(k) contribution related expense during the years ended December 31, 2023 and 2022, respectively.

- Definition

The entire disclosure for retirement benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-Paragraph 1
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480266/715-60-50-3

+ Details

Condensed Consolidated Balance Sheets - Parenthetical (Unaudited) - $ / shares	Dec. 31, 2023	Dec. 31, 2022
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares Issued	0	0
Preferred stock, shares outstanding	0	0
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	50,154,929	49,445,802
Common stock shares outstanding	50,140,233	49,323,531

Document And Entity Information - USD ($) $ in Millions	12 Months Ended
Document And Entity Information - USD ($) $ in Millions	Dec. 31, 2023	Mar. 11, 2024	Jun. 30, 2023
Cover [Abstract]
Document Type	10-K
Document Period End Date	Dec. 31, 2023
Amendment Flag	false
Trading Symbol	GLUE
Entity Registrant Name	Monte Rosa Therapeutics, Inc.
Entity Central Index Key	0001826457
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	No
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Shell Company	false
Document Fiscal Period Focus	FY
Entity Public Float			$ 234.3
Entity Common Stock, Shares Outstanding		50,154,073
Entity Ex Transition Period	false
ICFR Auditor Attestation Flag	false
Entity File Number	001-40522
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
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common stock, par value $0.0001 per share
Security Exchange Name	NASDAQ
Entity Incorporation, State or Country Code	DE
Document Annual Report	true
Document Transition Report	false
Documents Incorporated by Reference	Portions of registrant's definitive proxy statement for its annual meeting of shareholders to be filed within 120 days after the close of the registrant's fiscal year are incorporated by reference to into Part III of this annual report on Form 10-K.
Document Financial Statement Error Correction [Flag]	false
Auditor Name	Deloitte & Touche LLP
Auditor Location	Boston, Massachusetts
Auditor Firm ID	34

Summary of Significant Accounting Policies - Schedule of Property and Equipment Estimated Useful Life (Details)	12 Months Ended
	Dec. 31, 2023
Laboratory Equipment
Property Plant And Equipment [Line Items]
Property and equipment, useful life	5 years
Computer Hardware
Property Plant And Equipment [Line Items]
Property and equipment, useful life	3 years
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Property and equipment, useful life	5 years
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property, Plant and Equipment, Useful Life, Description	Shorter of useful life or remaining lease term

Fair value measurements

12 Months Ended

Dec. 31, 2023

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 December 31, 2023
	Level 1		Level 2		Level 3		Total
Current assets
Money market funds	$	122,791	$	—	$	—	$	122,791
Pension plan assets		—		9,317		—		9,317
Corporate debt securities		—		79,816		—		79,816
U.S Treasury securities		—		24,496		—		24,496
Total assets measured at fair value	$	122,791	$	113,629	$	—	$	236,420


	As of December 31, 2022
	Level 1		Level 2		Level 3		Total
Current assets
Money market funds	$	50,633	$	—	$	—	$	50,633
Pension plan assets		—		5,320		—		5,320
Corporate debt securities		—		127,351		—		127,351
U.S Treasury securities		—		80,563		—		80,563
Total assets measured at fair value	$	50,633	$	213,234	$	—	$	263,867

Money market funds are highly liquid investments and are actively traded. The pricing information on the Company’s money market funds are 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 Swiss Life Collective BVG Foundation collective investment fund and are 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 years ended December 31, 2023 or 2022.

Convertible preferred stock - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Class Of Stock [Line Items]
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares Issued	0	0
Net issuance costs	$ 116	$ 984
Common stock, par or stated value per share	$ 0.0001	$ 0.0001

- 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/exampleRef
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Reference 2: http://www.xbrl.org/2003/role/recommendedDisclosureRef
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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://www.xbrl.org/2003/role/disclosureRef
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+ Details

Marketable securities (Tables)

12 Months Ended

Dec. 31, 2023

Investments, Debt and Equity Securities [Abstract]

Summary of Marketable securities

Marketable securities as of December 31, 2023 consisted of the following (in thousands):


	Amortized		Unrealized		Unrealized			Fair
	Cost		Gains		Losses			Value
Description
Corporate debt securities	$	79,870	$	4	$	(58	)		79,816
U.S Treasury securities		24,495		11		(10	)		24,496
Total	$	104,365	$	15	$	(68	)	$	104,312

Marketable securities as of December 31, 2022 consisted of the following (in thousands):


	Amortized		Unrealized		Unrealized			Fair
	Cost		Gains		Losses			Value
Description
Corporate debt securities	$	127,565	$	27	$	(241	)		127,351
U.S Treasury securities		80,798		2		(237	)		80,563
Total	$	208,363	$	29	$	(478	)	$	207,914

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Subparagraph (a)
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Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 10: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 12: http://www.xbrl.org/2009/role/commonPracticeRef
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-Section 50
-Paragraph 3
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

+ Details

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Cash flows from operating activities:
Net loss	$ (135,352)	$ (108,501)
Adjustments to reconcile net loss to net cash used in operating activities
Stock-based compensation expense	16,669	11,664
Depreciation	6,222	3,745
Noncash lease expense	0	4,814
Net accretion of discounts/premiums on marketable securities	(3,914)	(1,945)
Loss on sale of marketable securities	131	0
Gain on disposal of property and equipment	(24)	(109)
Changes in operating assets and liabilities
Other receivables	1,897	(187)
Prepaid expenses and other current assets	1,077	(2,127)
Accounts payable	5,758	(744)
Accrued expenses and other current liabilities	3,557	1,031
Defined benefit plan liability	(188)	74
Right-of-use assets and operating lease liabilities	10,365	(181)
Deferred revenue	50,000	0
Net cash used in operating activities	(43,802)	(92,466)
Cash flows from investing activities:
Purchases of property and equipment	(19,041)	(12,911)
Proceeds from sale of property and equipment	62	109
Purchases of marketable securities	(103,151)	(384,417)
Proceeds from sale of marketable securities	45,631	0
Proceeds from maturities of marketable securities	165,300	178,000
Net cash provided by (used in) investing activities	88,801	(219,219)
Cash flows from financing activities:
Proceeds from issuance of common stock, net of underwriting discount of $620	0	20,055
Proceeds from issuance of pre-funded warrants	25,000	0
Proceeds from exercise of employee stock options	2,030	439
Proceeds from employee stock purchase plan	578	336
Payment of common stock issuance costs	0	(364)
Payment of pre-funded warrant issuance costs	(116)	0
Net cash provided by financing activities	27,492	20,466
Net decrease in cash, cash equivalents and restricted cash	72,491	(291,219)
Cash, cash equivalents and restricted cash—beginning of year	60,190	351,409
Cash, cash equivalents and restricted cash—end of year	132,681	60,190
Reconciliation of cash, cash equivalents and restricted cash
Cash and cash equivalents	128,101	54,912
Restricted cash	4,580	5,278
Total cash, cash equivalents and restricted cash	132,681	60,190
Supplemental disclosure of noncash items
Reduction of right-of-use assets for lease incentives receivable	5,253	7,469
Purchases of property and equipment in accounts payable and accrued expenses	$ 237	$ 6,240

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. Summary of significant accounting policies

Basis of presentation

Use of estimates

Currency and currency translation

Cash, cash equivalents and restricted cash

The Company had restricted cash of $4.6 million as of December 31, 2023 and 2022, primarily related to security deposits on its leases for offices in Boston, Massachusetts and Basel, Switzerland.

Marketable securities

Concentrations of credit risk and off-balance sheet risk

Fair value of financial instruments

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

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

Property and equipment


Asset	Estimated useful life
Laboratory equipment	Five years
Computer hardware	Three years
Furniture and fixtures	Five Years
Leasehold Improvements	Shorter of useful life or remaining lease term

Impairment of long-lived assets

Research and development expenses

Accrued research and development costs

Stock-based compensation

Income taxes

Defined pension benefit obligation

Segments

Revenue recognition

Warrants

Comprehensive income (loss)

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 (JOBS Act).

Recently adopted accounting pronouncements

Fair value measurements (Tables)

12 Months Ended

Dec. 31, 2023

Fair Value Disclosures [Abstract]

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


	As of December 31, 2023
	Level 1		Level 2		Level 3		Total
Current assets
Money market funds	$	122,791	$	—	$	—	$	122,791
Pension plan assets		—		9,317		—		9,317
Corporate debt securities		—		79,816		—		79,816
U.S Treasury securities		—		24,496		—		24,496
Total assets measured at fair value	$	122,791	$	113,629	$	—	$	236,420


	As of December 31, 2022
	Level 1		Level 2		Level 3		Total
Current assets
Money market funds	$	50,633	$	—	$	—	$	50,633
Pension plan assets		—		5,320		—		5,320
Corporate debt securities		—		127,351		—		127,351
U.S Treasury securities		—		80,563		—		80,563
Total assets measured at fair value	$	50,633	$	213,234	$	—	$	263,867

Employee Retirement Plans - Schedule of Estimated Future Benefit Payments (Details) $ in Thousands	Dec. 31, 2023 USD ($)
Retirement Benefits [Abstract]
2024	$ 1,052
2025	1,075
2026	1,092
2027	1,106
2028	1,122
2029-2033	$ 6,300

Income Taxes - Summary of Significant Components of Deferred Tax Assets (Liabilities) (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred tax assets
Federal and state net operating loss carryforwards	$ 41,888	$ 26,136
Research and development tax credits	2,245	1,715
Capitalized research and development	3,679	1,151
Lease liability	12,403	13,173
Compensation related items	6,283	4,022
Other	147	149
Total deferred tax assets	66,645	46,346
Less: valuation allowance	(54,465)	(33,084)
Total net deferred tax assets	12,180	13,262
Deferred tax liabilities
Right-of-Use Asset	(7,573)	(11,766)
Defined benefit plan adjustment	(332)	(375)
Prepaid insurance	0	(252)
Depreciation	(4,275)	(869)
Total deferred tax liabilities	(12,180)	(13,262)
Net deferred tax assets	$ 0	$ 0

Leases - Schedule of Lease Terms and Discount Rate (Details)	Dec. 31, 2023	Dec. 31, 2022
Leases [Abstract]
Weighted average remaining lease term (years)	8 years 7 months 6 days	9 years 8 months 12 days
Weighted average discount rate	9.80%	9.90%

Property and Equipment, net (Tables)

12 Months Ended

Dec. 31, 2023

Property, Plant and Equipment [Abstract]

Schedule of Property and Equipment

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


	December 31, 2023			December 31, 2022
Laboratory equipment	$	22,079		$	17,766
Computer hardware and software		1,052			499
Furniture and fixtures		1,099			388
Leasehold improvements		20,893			2,660
Construction in process		924			12,013
Total property and equipment, at cost	$	46,047		$	33,326
Less: accumulated depreciation		(12,244	)		(6,251	)
Property and equipment, net	$	33,803		$	27,075

Equity

12 Months Ended

Dec. 31, 2023

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 December 31, 2023.

Common Stock

The Company had 500,000,000 shares of common stock authorized, of which 50,154,929 shares were issued and 50,140,233 shares were outstanding at December 31, 2023.

The holders of common stock are entitled to dividends when and if declared by the board of directors, subject to the preferences applicable to outstanding shares of Convertible Preferred Stock. The 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.

The Company has issued restricted stock to founders, employees and consultants, and expense for this restricted stock is recognized on a straight-line basis (see Note 11). The restricted stock generally vests monthly over 4 years.

Pre-Funded Warrant

On October 30, 2023, the Company sold in a registered direct offering pursuant to a securities purchase agreement pre-funded warrants to purchase 10,000,400 shares of the Company’s common stock to an accredited investor at a purchase price of $2.4999 per pre-funded warrant resulting in proceeds to the Company of $24.9

million, net of offering costs of $0.1 million. The pre-funded warrants are immediately exercisable at an exercise price of $0.0001 per share, and may be exercised at any time until the pre-funded warrants are exercised in full.

The Company has assessed the Pre-Funded Warrant for appropriate equity or liability classification pursuant to the Company’s accounting policy described in Note 2, “Summary of Significant Accounting Policies.” During this assessment, the Company determined the Pre-Funded Warrant is 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 Warrant is indexed to the Company’s common stock and meets 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 Warrant is a freestanding equity-linked financial instrument that meets the criteria for equity classification under ASC 480 and ASC 815. Accordingly, the Pre-Funded Warrant is classified as equity and is accounted for as a component of additional paid-in capital at the time of issuance. The Company also determined that the Pre-Funded Warrant should be included in the determination of basic and diluted earnings per share in accordance with ASC 260, Earnings per Share.

At-the-Market Offering

In July 2022, the Company entered into a sales agreement, (the “Sales Agreement”), with Jefferies LLC, or Jefferies, pursuant to which the Company may offer and sell shares of its common stock having aggregate gross proceeds of up to $100 million from time to time in “at-the-market” offerings through Jefferies, as the Company’s sales agent. 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 year ended December 31, 2022, the Company sold 2,482,008 shares of its common stock resulting in proceeds to the Company of $19.7 million, net of offering costs of $1.0 million

- Definition

The entire disclosure for equity.

+ References

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

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-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 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-14

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481062/946-235-50-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481062/946-235-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 505
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481004/946-505-50-6

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480237/815-40-50-6

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480008/505-10-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(e)(1))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 505
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//505/tableOfContent

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-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 - Schedule of Schedule Of Supplemental Cash Flow Information Related To Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Leases [Abstract]
Right-of-use assets obtained in exchange for operating lease obligations	$ 1,871	$ 48,488
Cash paid for amounts included in the measurement of lease liabilities	$ 2,995	$ 1,654

Leases (Additional Information) (Details)		1 Months Ended	12 Months Ended
Leases (Additional Information) (Details)	Dec. 14, 2021 USD ($) ft²	Apr. 30, 2023 USD ($) ft²	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Mar. 01, 2021 ft²
Lessee, Lease, Description [Line Items]
Finance Lease			$ 0
Short-Term Lease			0	$ 0
Amortization of the ROU assets			2,500,000	3,300,000
Tenant Improvements			13,000,000
Lease expenses			9,458,000	8,822,000
Hochbergerstrasse (Member)
Lessee, Lease, Description [Line Items]
Land Subject to Ground Leases \| ft²					21,422
Right of Use Assets Decreased Limit, Amount		$ 1,800,000
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%
Minimum [Member] \| Hochbergerstrasse (Member)
Lessee, Lease, Description [Line Items]
Land Subject to Ground Leases \| ft²		21,422
Maximum [Member] \| Hochbergerstrasse (Member)
Lessee, Lease, Description [Line Items]
Land Subject to Ground Leases \| ft²		44,685
Research and Development [Member]
Lessee, Lease, Description [Line Items]
Short-Term Lease			1,600,000	1,000,000
General and Administrative [Member]
Lessee, Lease, Description [Line Items]
Short-Term Lease			$ 7,900,000	$ 7,800,000

Accrued expenses and other current liabilities (Tables)

12 Months Ended

Dec. 31, 2023

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):


	December 31,		December 31,
	2023		2022
Compensation and benefits	$	7,593	$	5,624
Accrued research and development		5,336		3,936
Other		1,671		5,020
Total other current liabilities	$	14,600	$	14,580

Marketable securities - Summary of Marketable securities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Marketable Securities [Line Items]
Amortized Cost	$ 104,365	$ 208,363
Unrealized Gains	15	29
Unrealized Losses	(68)	(478)
Fair Value	104,312	207,914
Corporate debt securities
Marketable Securities [Line Items]
Amortized Cost	79,870	127,565
Unrealized Gains	4	27
Unrealized Losses	(58)	(241)
Fair Value	79,816	127,351
U.S Treasury securities
Marketable Securities [Line Items]
Amortized Cost	24,495	80,798
Unrealized Gains	11	2
Unrealized Losses	(10)	(237)
Fair Value	$ 24,496	$ 80,563

Leases (Tables)

12 Months Ended

Dec. 31, 2023

Leases [Abstract]

Summary of Lease Expense

The components of lease expense for the year ended December 31, 2023, are as follows (in thousands):


	Year ended December 31,
	2023		2022
Operating lease expense	$	7,141	$	6,924
Variable lease expense		2,317		1,898
Total lease expense	$	9,458	$	8,822

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:


	December 31, 2023			December 31, 2022
Weighted average remaining lease term (years)		8.6			9.7
Weighted average discount rate		9.8	%		9.9	%

Schedule Of Supplemental Cash Flow Information Related To Leases

Supplemental cash flow information relating to the Company's leases for the year ended December 31, 2023 are as follows (in thousands):


	Year ended December 31,
	2023		2022
Right-of-use assets obtained in exchange for operating lease obligations	$	1,871	$	48,488
Cash paid for amounts included in the measurement of lease liabilities	$	2,995	$	1,654

Schedule of Future Minimum Lease Payments Under Non-Cancelable Leases

Future undiscounted lease payments under non-cancelable leases as of December 31, 2023 for each of the years ending December 31st are as follows (in thousands):


Undiscounted lease payments
2024	$	7,443
2025		7,743
2026		7,944
2027		7,655
2028		7,360
Thereafter		31,026
Total undiscounted minimum lease payments		69,171
Less: Imputed interest		(23,132	)
Total operating lease liability	$	46,039

Leases - Schedule of Future Minimum Payments Under Non -cancelable Operating Leases (Details) - Non-cancelable leases [Member] $ in Thousands	Dec. 31, 2023 USD ($)
Finite-Lived Intangible Assets [Line Items]
2024	$ 7,443
2025	7,743
2026	7,944
2027	7,655
2028	7,360
Thereafter	31,026
Total undiscounted lease payments	69,171
Less: Imputed interest	(23,132)
Operating Lease liability	$ 46,039

Fair Value Measurements - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
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

Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disclosure - Income Taxes - Additional Information (Detail) [Line Items]
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	$ 21,400
Unrecognized tax benefits	4,475	$ 2,235	$ 0
Federal and state research and development credit	2,369	2,235
Federal
Disclosure - Income Taxes - Additional Information (Detail) [Line Items]
Operating Loss Carryforwards	500
Tax Credit Carryforward, Amount	$ 1,000
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2040
Foreign
Disclosure - Income Taxes - Additional Information (Detail) [Line Items]
Operating Loss Carryforwards	$ 288,000
State
Disclosure - Income Taxes - Additional Information (Detail) [Line Items]
Unrecognized tax benefits	4,500	$ 2,200
Operating Loss Carryforwards	$ 500
Ownership Interests of Significant Stockholders	50.00%
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2034