0000950170-24-089249 | 10-Q | XBRL Viewer

Overview	6 Months Ended
Jun. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Overview	1. Overview Merus N.V. is a clinical-stage oncology company developing innovative antibody therapeutics, headquartered in Utrecht, the Netherlands. Merus US, Inc. is a wholly-owned subsidiary of Merus N.V. located at 139 Main Street, Cambridge, Massachusetts, United States (collectively, the “Company”). Since inception, the Company has generated an accumulated deficit of $837.6 million as of June 30, 2024. The Company expects to continue to incur significant expenses and operating losses for the foreseeable future as its antibody candidates advance through discovery, pre-clinical development and clinical trials and as it seeks regulatory approval and pursues commercialization of any approved antibody candidate. As a result, the Company may need additional financing to support its continuing operations. Until the Company can generate significant revenue from product sales, if ever, the Company expects to finance its operations through public equity offerings, debt financings, or other sources, which may include collaborations, business development and licensing opportunities with third parties. Adequate additional financing may not be available to the Company on acceptable terms, or at all. The Company’s inability to raise capital as and when needed would have a negative impact on its financial condition and ability to pursue its business strategy. The Company will need to generate significant revenues to achieve profitability and may never do so.

Overview

6 Months Ended

Jun. 30, 2024

Organization, Consolidation and Presentation of Financial Statements [Abstract]

1. Overview

Merus N.V. is a clinical-stage oncology company developing innovative antibody therapeutics, headquartered in Utrecht, the Netherlands. Merus US, Inc. is a wholly-owned subsidiary of Merus N.V. located at 139 Main Street, Cambridge, Massachusetts, United States (collectively, the “Company”).

Since inception, the Company has generated an accumulated deficit of $837.6 million as of June 30, 2024. The Company expects to continue to incur significant expenses and operating losses for the foreseeable future as its antibody candidates advance through discovery, pre-clinical development and clinical trials and as it seeks regulatory approval and pursues commercialization of any approved antibody candidate.

As a result, the Company may need additional financing to support its continuing operations. Until the Company can generate significant revenue from product sales, if ever, the Company expects to finance its operations through public equity offerings, debt financings, or other sources, which may include collaborations, business development and licensing opportunities with third parties. Adequate additional financing may not be available to the Company on acceptable terms, or at all. The Company’s inability to raise capital as and when needed would have a negative impact on its financial condition and ability to pursue its business strategy. The Company will need to generate significant revenues to achieve profitability and may never do so.

Employee Benefits

6 Months Ended

Jun. 30, 2024

Retirement Benefits [Abstract]

Employee Benefits

10. Employee Benefits

Share-Based Compensation

Share-based compensation expense is classified in the condensed consolidated statements of operations and comprehensive loss as follows:


	Three Months Ended June 30,				Six Months Ended June 30,
	2024		2023		2024		2023
	(in thousands)				(in thousands)
Research and development	$	5,220	$	3,042	$	7,115	$	5,900
General and administrative		6,466		3,411		9,364		6,303
Total	$	11,686	$	6,453	$	16,479	$	12,203

The weighted-average grant date fair value of options, estimated as of the grant date using the Black Scholes option pricing model was $23.93 per option for the 2,659,757 options granted during the six months ended June 30, 2024. The following assumptions were used to estimate the fair value of the options granted during the six months ended June 30, 2024.


Volatility	67.5	%
Risk-free interest rate	4.5	%
Expected holding period (in years)	6.2
Dividend yield	-

Contingent Share Option Awards

On February 1, 2024, the Board of Directors approved the grant of share options to purchase 2,446,045 shares of our common shares, at an exercise price of $36.09 per share, to employees as the annual grant for 2024. These share option grants were approved subject to Company's general meeting resolving upon, and the Board of Directors having implemented through an amendment to the Company's articles of association, an increase in the authorized share capital sufficient to satisfy the award set forth in the resolution (such shareholder resolution to be proposed to the Company's annual general meeting to be held in 2024) (the “Shareholder Approval Condition”), provided that such options will be forfeited if the Shareholder Approval Condition is not satisfied ultimately by January 1, 2025. On May 7, 2024, the shareholders approved the amendment to the Company’s articles of association, including the requisite increase in the authorized share capital satisfying the Shareholder Approval Condition, therefore the grant-date fair value of the contingent shares is based on the Black-Scholes valuation model based on the fair market value of the share on the shareholder approval date. Share-based compensation expense was recorded in the second quarter of 2024 relating to these contingent share option awards.

Employee Benefits - Summary of Assumptions Used to Estimate Fair Value of Options Granted (Details)	6 Months Ended
	Jun. 30, 2024
Share-Based Payment Arrangement [Abstract]
Volatility	67.50%
Risk-free interest rate	4.50%
Expected holding period (in years)	6 years 2 months 12 days

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 629,475	$ 204,246
Marketable securities	157,948	150,130
Accounts receivable	1,842	2,429
Prepaid expenses and other current assets	17,288	12,009
Total current assets	806,553	368,814
Marketable securities	58,961	57,312
Property and equipment, net	12,090	12,135
Operating lease right-of-use assets	10,291	11,362
Intangible assets, net	1,658	1,800
Deferred tax assets	543	1,199
Other assets	2,132	2,872
Total assets	892,228	455,494
Current liabilities:
Accounts payable	4,395	4,602
Accrued expenses and other liabilities	40,826	38,482
Income taxes payable	1,605	1,646
Current portion of lease obligation	1,688	1,674
Current portion of deferred revenue	32,350	22,685
Total current liabilities	80,864	69,089
Lease obligation	9,332	10,488
Deferred revenue, net of current portion	55,260	19,574
Total liabilities	145,456	99,151
Commitments and contingencies - Note 6
Shareholders' equity:
Common shares, EUR 0.09 par value; 105,000,000 shares authorized at June 30, 2024 and December 31, 2023; 67,852,920 and 57,825,879 shares issued and outstanding as at June 30, 2024 and December 31, 2023, respectively	6,863	5,883
Additional paid-in capital	1,616,367	1,126,054
Accumulated other comprehensive income	(38,899)	(22,533)
Accumulated deficit	(837,559)	(753,061)
Total shareholders' equity	746,772	356,343
Total liabilities and shareholders' equity	$ 892,228	$ 455,494

Summary of Significant Accounting Policies (Policies)	6 Months Ended
Summary of Significant Accounting Policies (Policies)	Jun. 30, 2024
Accounting Policies [Abstract]
Basis of Preparation	Basis of Presentation The Company prepared its unaudited consolidated condensed financial statements in compliance with generally accepted accounting principles in the U.S. ("U.S. GAAP"). Any reference in these notes to applicable guidance is meant to refer to authoritative U.S. GAAP as found in the Accounting Standards Codification ("ASC") and Accounting Standards Update ("ASU") of the Financial Accounting Standards Board ("FASB"). The unaudited condensed consolidated financial statements include the accounts of Merus N.V. and its wholly owned, controlled subsidiary, Merus US, Inc. All intercompany transactions and balances of subsidiaries have been eliminated in consolidation. In the opinion of management, these financial statements reflect all adjustments, all of which are of a normal and recurring nature, necessary for a fair presentation of the results for the reported interim periods. The Company considers events or transactions that occur after the balance sheet date but before the unaudited condensed consolidated financial statements are issued to provide additional evidence relative to certain estimates or to identify matters that require additional disclosure. The three months ended June 30, 2024 and 2023 are referred to as the second quarter of 2024 and 2023, respectively. The results of operations for interim periods are not necessarily indicative of results to be expected for the full year or any other interim period. The unaudited condensed consolidated financial statements presented herein do not contain the required disclosures under U.S. GAAP for annual financial statements. Therefore, these unaudited condensed consolidated financial statements should be read in conjunction with the annual audited consolidated financial statements and related notes as of and for the year ended December 31, 2023, included in the Annual Report on Form 10-K.
Going Concern	Going Concern At each reporting period, the Company evaluates whether there are conditions or events that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that the financial statements are issued. The Company is required to make certain additional disclosures if it concludes substantial doubt exists and it is not alleviated by the Company’s plans or when its plans alleviate substantial doubt about the Company’s ability to continue as a going concern. The Company’s evaluation entails analyzing prospective operating budgets and forecasts for expectations of the Company’s cash needs, and comparing those needs to the current cash, cash equivalent and marketable security balances. After considering the Company’s current research and development plans and the timing expectations related to the progress of its clinical-stage programs and its plans to pursue commercialization of any antibody candidate, if approved, and after considering its existing cash, cash equivalents and marketable securities as of June 30, 2024, the Company did not identify conditions or events that raise substantial doubt about the Company’s ability to continue as a going concern within one year from the date these financial statements were issued. Additional details of the Company’s cash runway are described in “Management’s Discussion and Analysis of Financial Condition and Results of Operations”.
New Accounting Pronouncements	New Accounting Pronouncements The Company considers the applicability and impact of any recent Accounting Standards Update ("ASU") issued by the Financial Accounting Standards Board ("FASB"). Based on the assessment, the ASUs were determined to be either not applicable or are expected to have minimal impact on the Company's condensed consolidated financial statements.

Summary of Significant Accounting Policies

6 Months Ended

Jun. 30, 2024

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

The principal accounting policies applied in the preparation of these unaudited condensed consolidated financial statements are described in the Company’s audited financial statements as of and for the year ended December 31, 2023, and the notes thereto, which are included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2023, filed with the SEC on February 28, 2024 (the “Annual Report on Form 10-K”). There have been no material changes in the Company’s significant accounting policies during the six months ended June 30, 2024.

Basis of Presentation

The Company prepared its unaudited consolidated condensed financial statements in compliance with generally accepted accounting principles in the U.S. ("U.S. GAAP"). Any reference in these notes to applicable guidance is meant to refer to authoritative U.S. GAAP as found in the Accounting Standards Codification ("ASC") and Accounting Standards Update ("ASU") of the Financial Accounting Standards Board ("FASB").

The unaudited condensed consolidated financial statements include the accounts of Merus N.V. and its wholly owned, controlled subsidiary, Merus US, Inc. All intercompany transactions and balances of subsidiaries have been eliminated in consolidation. In the opinion of management, these financial statements reflect all adjustments, all of which are of a normal and recurring nature, necessary for a fair presentation of the results for the reported interim periods. The Company considers events or transactions that occur after the balance sheet date but before the unaudited condensed consolidated financial statements are issued to provide additional evidence relative to certain estimates or to identify matters that require additional disclosure. The three months ended June 30, 2024 and 2023 are referred to as the second quarter of 2024 and 2023, respectively. The results of operations for interim periods are not necessarily indicative of results to be expected for the full year or any other interim period.

The unaudited condensed consolidated financial statements presented herein do not contain the required disclosures under U.S. GAAP for annual financial statements. Therefore, these unaudited condensed consolidated financial statements should be read in conjunction with the annual audited consolidated financial statements and related notes as of and for the year ended December 31, 2023, included in the Annual Report on Form 10-K.

Going Concern

At each reporting period, the Company evaluates whether there are conditions or events that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that the financial statements are issued. The Company is required to make certain additional disclosures if it concludes substantial doubt exists and it is not alleviated by the Company’s plans or when its plans alleviate substantial doubt about the Company’s ability to continue as a going concern.

The Company’s evaluation entails analyzing prospective operating budgets and forecasts for expectations of the Company’s cash needs, and comparing those needs to the current cash, cash equivalent and marketable security balances. After considering the Company’s current research and development plans and the timing expectations related to the progress of its clinical-stage programs and its plans to pursue commercialization of any antibody candidate, if approved, and after considering its existing cash, cash

equivalents and marketable securities as of June 30, 2024, the Company did not identify conditions or events that raise substantial doubt about the Company’s ability to continue as a going concern within one year from the date these financial statements were issued. Additional details of the Company’s cash runway are described in “Management’s Discussion and Analysis of Financial Condition and Results of Operations”.

New Accounting Pronouncements

The Company considers the applicability and impact of any recent Accounting Standards Update ("ASU") issued by the Financial Accounting Standards Board ("FASB"). Based on the assessment, the ASUs were determined to be either not applicable or are expected to have minimal impact on the Company's condensed consolidated financial statements.

Supplemental Balance Sheet Information (Tables)

6 Months Ended

Jun. 30, 2024

Balance Sheet Related Disclosures [Abstract]

Schedule of Prepaid Expenses and Other Current Assets

Prepaid expenses and other current assets consisted of the following:


	June 30, 2024		December 31, 2023
	(in thousands)
Prepaid research and development expenses	$	8,780	$	6,872
Prepaid general and administrative expenses		4,749		2,058
Interest receivable		2,053		1,552
Other		1,706		1,527
Total	$	17,288	$	12,009

Summary of Accrued Expenses and Other Liabilities

Accrued expenses and other liabilities consisted of the following:


	June 30, 2024		December 31, 2023
	(in thousands)
Accrued research and development expenses	$	26,420	$	27,970
Accrued personnel costs		4,266		8,348
Accrued general and administrative expenses		10,037		2,129
Other		103		35
Total	$	40,826	$	38,482

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2024	Jun. 30, 2023
Pay vs Performance Disclosure
Net Income (Loss)	$ (50,042)	$ (34,456)	$ (32,033)	$ (39,741)	$ (84,498)	$ (71,774)

- Definition

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

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+ Details

Supplemental Balance Sheet Information

6 Months Ended

Jun. 30, 2024

Balance Sheet Related Disclosures [Abstract]

Supplemental Balance Sheet Information

4. Supplemental Balance Sheet Information

Prepaid expenses and other current assets consisted of the following:


	June 30, 2024		December 31, 2023
	(in thousands)
Prepaid research and development expenses	$	8,780	$	6,872
Prepaid general and administrative expenses		4,749		2,058
Interest receivable		2,053		1,552
Other		1,706		1,527
Total	$	17,288	$	12,009

Accrued expenses and other liabilities consisted of the following:


	June 30, 2024		December 31, 2023
	(in thousands)
Accrued research and development expenses	$	26,420	$	27,970
Accrued personnel costs		4,266		8,348
Accrued general and administrative expenses		10,037		2,129
Other		103		35
Total	$	40,826	$	38,482

Commitments and Contingencies

6 Months Ended

Jun. 30, 2024

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

6. Commitments and Contingencies

Litigation

From time to time, the Company may be involved in various claims and legal proceedings relating to or arising out of the Company’s operations. The Company is not currently a party to any material legal proceedings.

On August 19, 2022, Kymab Limited ("Kymab"), a subsidiary of Sanofi, filed a notice of opposition against the Company's EP3456190 patent (the "'190 patent"), entitled "Antibody Producing Transgenic Murine Animal," in the European Opposition Division of the European Patent Office (the "EPO"). The notice asserted, as applicable, the '190 patent is contrary to the provision of Article 123(2) EPC, Article 75(1) EPC and Article 100(c) EPC, and alleges the '190 patent lacks novelty and/or is obvious contrary to the provisions of Articles 54 and/or 56 EPC, and Article 100(a) EPC, and that the specification of the '190 patent does not provide sufficient disclosure of the subject matter of the inventions contravening Article 83 EPC and Article 100(b). On January 17, 2023, the Company timely filed a response before the European Opposition Division of the EPO contesting each of these assertions, with further oral proceedings scheduled to follow on January 18, 2024. On June 2, 2023, the European Opposition Division issued a non-binding preliminary decision. On January 18, 2024, the European Opposition Division held oral proceedings addressing each allegation of invalidity raised by Kymab and maintained the '190 patent as granted, and issued a written decision documenting these conclusions on February 16, 2024. In April 2024, Kymab filed a notice of appeal before the Technical Board of Appeals, and Grounds of Appeal on June 17, 2024 with further submissions by the parties and proceedings to follow. The Company does not expect significant impact on its assets or liabilities as a result of the opposition proceeding.

Document and Entity Information - shares	6 Months Ended
Document and Entity Information - shares	Jun. 30, 2024	Jul. 25, 2024
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2024
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q2
Entity Registrant Name	MERUS N.V.
Trading Symbol	MRUS
Entity Central Index Key	0001651311
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Interactive Data Current	Yes
Entity Common Stock, Shares Outstanding		68,210,479
Entity File Number	001-37773
Entity Incorporation, State or Country Code	P7
Entity Tax Identification Number	00-0000000
Entity Address, Address Line One	Uppsalalaan 17
Entity Address, City or Town	Utrecht
Entity Address, Postal Zip Code	3584 CT
Entity Address, Country	NL
City Area Code	+31 85
Local Phone Number	016 2500
Document Quarterly Report	true
Document Transition Report	false
Title of 12(b) Security	Common shares, nominal value €0.09 per share
Security Exchange Name	NASDAQ

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (84,498)	$ (71,774)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization of property and equipment	1,160	1,159
Amortization of intangible assets	87	104
Foreign exchange losses (gains)	(16,187)	6,452
Share-based compensation expense	16,479	12,203
Amortization (accretion) of discount on investments	(2,145)	(2,446)
Deferred tax expense (benefit)	657	(1,015)
Changes in operating assets and liabilities:
Accounts receivable	516	1,283
Operating lease right-of-use assets and lease obligations	(47)	(40)
Prepaid expenses and other current assets	(4,990)	(1,963)
Accounts payable	(21)	(839)
Accrued expenses and other liabilities	3,131	(5,439)
Deferred revenue	47,103	(16,014)
Net cash used in operating activities	(38,755)	(78,329)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of marketable securities	(99,165)	(144,376)
Proceeds from maturities of marketable securities	91,857	115,420
Purchases of property and equipment	(1,539)	(3,969)
Net cash provided by (used in) investing activities	(8,847)	(32,925)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock, net	434,863	63,796
Payments of offering costs	(96)	(77)
Proceeds from share issuance - Gilead Collaboration	22,613	0
Proceeds from share options exercised	17,671	2,465
Net cash provided by financing activities	475,051	66,184
Foreign exchange impact on cash, cash equivalents and restricted cash	(2,236)	(1,514)
Net increase (decrease) in cash, cash equivalents and restricted cash	425,213	(46,584)
Cash, cash equivalents, and restricted cash, beginning of period	205,014	148,439
Cash, cash equivalents, and restricted cash, end of period	630,227	101,855
SUPPLEMENTAL DISCLOSURES:
Income taxes paid	2,800	3,103
Non-cash purchases of property, equipment and intangibles	0	0
Non-cash financing costs	(237)	0
Non-cash issuance of stock options	0	0
CASH, CASH EQUIVALENTS AND RESTRICTED CASH
Cash and cash equivalents	629,475	101,096
Restricted cash included in non-current other assets	752	759
Cash, cash equivalents, and restricted cash, end of period	$ 630,227	$ 101,855

Employee Benefits (Tables)

6 Months Ended

Jun. 30, 2024

Retirement Benefits [Abstract]

Summary of Share-based Compensation Expense Classified in Condensed Consolidated Statements of Operations and Comprehensive Loss

Share-based compensation expense is classified in the condensed consolidated statements of operations and comprehensive loss as follows:


	Three Months Ended June 30,				Six Months Ended June 30,
	2024		2023		2024		2023
	(in thousands)				(in thousands)
Research and development	$	5,220	$	3,042	$	7,115	$	5,900
General and administrative		6,466		3,411		9,364		6,303
Total	$	11,686	$	6,453	$	16,479	$	12,203

Summary of Assumptions Used to Estimate Fair Value of Options Granted

The following assumptions were used to estimate the fair value of the options granted during the six months ended June 30, 2024.


Volatility	67.5	%
Risk-free interest rate	4.5	%
Expected holding period (in years)	6.2
Dividend yield	-

Subsequent Events

6 Months Ended

Jun. 30, 2024

Subsequent Events [Abstract]

Subsequent Events

11. Subsequent Events

On June 30, 2024, the Board of Directors appointed Fabian Zohren, M.D., Ph.D. to serve as the Company’s Chief Medical Officer with a start date of July 1, 2024. In connection with Dr. Zohren’s appointment as the Company’s Chief Medical Officer, on June 30, 2024, Merus US, Inc., entered into an employment agreement with Dr. Zohren (the “Employment Agreement”) pursuant to which Dr. Zohren will serve as the Chief Medical Officer of the Company and Merus US and will be entitled to an annual base salary of $503,000 and an annual performance-based bonus targeted at 40% of his annual base salary. The Employment Agreement also provides that, Dr. Zohren was granted an option under the Company’s 2016 Incentive Award Plan to purchase 183,943 common shares of the Company. The option will vest and become exercisable (subject to Mr. Zohren’s continued employment with Merus US or the Company through each applicable vesting date) as to 25% of the underlying shares on the first anniversary of the Employment Agreement Effective Date, with the remaining underlying shares vesting in 36 substantially equal monthly installments thereafter, such that the option shall be vested and exercisable as to all shares on the fourth anniversary of the Employment Agreement Effective Date. Pursuant to the Employment Agreement, if Dr. Zohren’s employment is terminated by Merus US without cause or due to his resignation for good reason, then subject to him executing a general release of claims and continuing compliance with a proprietary information agreement, Dr. Zohren will be entitled to receive (i) base salary continuation payments for 12 months, (ii) payment for any earned but unpaid annual bonus for the year prior to the year of termination, and (iii) direct payment of or reimbursement for continued medical, dental or vision coverage pursuant to COBRA for up to 12 months. If Dr. Zohren’s employment is terminated by Merus US without cause or due to his resignation for good reason, in either case, within 12 months following a change in control of the Company, then subject to him executing a general release of claims and continuing compliance with a proprietary information agreement, Dr. Zohren will be entitled to receive, in lieu of the severance payments described above, (i) a lump sum payment equal to one times his base salary and target annual bonus, (ii) payment for any earned but unpaid annual bonus for the year prior to the year of termination, (iii) direct payment of or reimbursement for continued medical, dental or vision coverage pursuant to COBRA for up to 12 months, and (iv) provided that the date of termination occurs more than 12 months following the Employment Agreement Effective Date, accelerated vesting of any portion of his time-based equity awards in the Company that is unvested as of the date of such termination, with any awards that vest in whole or in part based on the attainment of performance-vesting conditions being governed by the terms of the applicable award agreement.

Effective as of July 1, 2024, the employment of Hui Liu, Ph.D., the Chief Business Officer of the Company and Head of Merus US, and Andrew Joe, M.D., the Company’s Chief Medical Officer, with Merus US ended. Dr. Liu and Dr. Joe each entered into a Separation Agreement and Release with Merus US (the "Liu Separation Agreement" and "Joe Separation Agreement" respectively). Pursuant to the Liu Separation Agreement and the Joe Separation Agreement, as applicable, each of Dr. Liu and Dr. Joe will be eligible to receive the following payments and benefits, subject to his execution and non-revocation of a release of claims in favor of Merus US and the Company: the severance payments and benefits set forth in his respective employment agreement with Merus US, subject to and in accordance with the previously disclosed terms of the applicable employment agreement. Subject to Dr. Liu’s continued compliance with the terms and conditions of the Liu Separation Agreement, he further: (i) received accelerated vesting of 3,000 restricted stock units in the Company granted on October 10, 2023; (ii) is eligible to receive a lump sum payment of $17,500 payable within sixty (60) days of his separation date; and (iii) has the time period to exercise any options to purchase common shares of the Company that are outstanding and vested as of July 1, 2024 extended to December 31, 2024. In addition, Dr. Liu is entitled to reimbursement of up to $10,000 in professional fees incurred in connection with the negotiation of the Liu Separation Agreement. Each of Dr. Liu and Dr. Joe have agreed to comply with a 12 month post-termination non-compete and to continued compliance with his respective proprietary information agreement with Merus US. In connection with Dr. Joe's termination of employment, on June 30,

2024 the Company entered into a Consultancy Agreement with Dr. Joe (the “Consulting Agreement”), pursuant to which Dr. Joe will provide consulting services to the Company for a period of three (3) months following his termination of employment in exchange for a monthly consulting fee of $41,000, with effect from July 1, 2024. Subject to Dr. Joe’s continued compliance with the terms and conditions of the Joe Separation Agreement, the time period to exercise any options to purchase common shares of the Company that are outstanding and vested as of July 1, 2024 shall generally be extended to the date that is three (3) months following the expiration of the Consulting Agreement. The Company will assess the impact of the separation agreements during the following quarter.

On July 24, 2024, the Company announced that the first patient has been dosed in the Company’s phase 3 trial evaluating the efficacy and safety of petosemtamab, a Biclonics® targeting EGFR and LGR5, compared to investigator’s choice of single agent chemotherapy or cetuximab in previously treated (2/3L) patients with recurrent/metastatic head and neck squamous cell carcinoma (r/m HNSCC) referred to as the LiGeR-HN2 trial. As a result of the first patient dosing, Merus shall make milestone payments of approximately €3.0 million, €1.0 million, and $0.5M pursuant to certain intellectual property rights agreements relating to petosemtamab, and €0.15 million pursuant to a license agreement concerning certain technology related to petosemtamab, respectively, during the third quarter of 2024.

Supplemental Balance Sheet Information - Summary of Accrued Expenses and Other Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Payables and Accruals [Abstract]
Accrued research and development expenses	$ 26,420	$ 27,970
Accrued personnel costs	4,266	8,348
Accrued general and administrative expenses	10,037	2,129
Other	103	35
Total	$ 40,826	$ 38,482

Overview - Additional Information (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accumulated deficit	$ (837,559)	$ (753,061)

- Definition

Amount of accumulated undistributed earnings (deficit).

+ References + Details

Collaborations - Summary of Company's Collaboration Arrangements Earned in Period to Be Billed and Collected in Next Period (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Collaboration Revenue
Collaborative Arrangement, Revenue Not from Contract with Customer, Statement of Income or Comprehensive Income [Extensible Enumeration]	Revenue from Contract with Customer, Excluding Assessed Tax	Revenue from Contract with Customer, Excluding Assessed Tax	Revenue from Contract with Customer, Excluding Assessed Tax	Revenue from Contract with Customer, Excluding Assessed Tax
Operating expenses:
Research and development	$ 49,119	$ 28,298	$ 87,703	$ 63,163
General and administrative	22,587	16,063	38,701	31,449
Total operating expenses	71,706	44,361	126,404	94,612
Incyte
Collaboration Revenue
Upfront payments	4,266	4,325	8,568	8,541
Reimbursement revenue	1,202	1,335	2,660	2,701
Milestones	0	0	1,000	2,501
Other	0	0	0	0
Total collaboration revenue	5,468	5,660	12,228	13,743
Operating expenses:
Research and development	0	0	24	0
General and administrative	0	0	0	0
Total operating expenses	0	0	24	0
Revenue recognized in the period	4,266	4,325	8,568	8,541
Lilly
Collaboration Revenue
Upfront payments	462	3,305	1,272	7,481
Reimbursement revenue	190	1,505	504	2,696
Milestones	0	0	0	0
Other	0	0	0	0
Total collaboration revenue	652	4,810	1,776	10,177
Operating expenses:
Research and development	0	0	0	0
General and administrative	0	0	0	0
Total operating expenses	0	0	0	0
Revenue recognized in the period	462	3,305	1,272	7,481
Gilead
Collaboration Revenue
Upfront payments	1,207	0	1,207	0
Reimbursement revenue	0	0	0	0
Milestones	0	0	0	0
Other	0	0	0	0
Total collaboration revenue	1,207	0	1,207	0
Operating expenses:
Research and development	0	0	0	0
General and administrative	0	0	0	0
Total operating expenses	0	0	0	0
Revenue recognized in the period	1,207	0	1,207	0
Other
Collaboration Revenue
Upfront payments	0	0	0	0
Reimbursement revenue	0	0	0	0
Milestones	0	0	0	0
Other	5	6	10	55
Total collaboration revenue	5	6	10	55
Operating expenses:
Research and development	0	0	0	0
General and administrative	0	0	0	0
Total operating expenses	0	0	0	0
Revenue recognized in the period	0	0	0	0
Collaboration Agreement
Collaboration Revenue
Upfront payments	5,935	7,630	11,047	16,022
Reimbursement revenue	1,392	2,840	3,164	5,397
Milestones	0	0	1,000	2,501
Other	5	6	10	55
Total collaboration revenue	7,332	10,476	15,221	23,975
Operating expenses:
Research and development	0	0	24	0
General and administrative	0	0	0	0
Total operating expenses	0	0	24	0
Revenue recognized in the period	$ 5,935	$ 7,630	$ 11,047	$ 16,022

Employee Benefits - Summary of Share-based Compensation Expense Classified in Condensed Consolidated Statements of Operations and Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total	$ 11,686	$ 6,453	$ 16,479	$ 12,203
Research and Development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total	5,220	3,042	7,115	5,900
General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total	$ 6,466	$ 3,411	$ 9,364	$ 6,303

- 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

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+ Details

Income Taxes - Additional Information (Details) - Dutch Tax Law € in Millions	6 Months Ended
	Jun. 30, 2024 EUR (€)
Income Tax Disclosure [Line Items]
Taxable income that exceeds €1.0 million, percentage	50.00%
Maximum
Income Tax Disclosure [Line Items]
Future taxable income offset limit	€ 1.0
Minimum
Income Tax Disclosure [Line Items]
Future taxable income exceeding limit	€ 1.0

Collaborations

6 Months Ended

Jun. 30, 2024

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Collaborations

8. Collaborations

Gilead

On March 5, 2024, the Company entered into a collaboration, option and license agreement (the “Gilead Collaboration Agreement”) and Share Subscription Agreement (the “Subscription Agreement”) with Gilead Sciences, Inc. (“Gilead”). Gilead agreed to pay the Company a $56.0 million, non-refundable upfront payment, and purchased 452,527 common shares at a stated price per share of $55.2454 for an aggregate purchase price of $25.0 million. Merus is also eligible to receive license option exercise payments, potential development and commercialization milestones, tiered royalties on product sales should Gilead successfully commercialize a therapy from the collaboration, and an initiation fee should Gilead exercise its right to include a third Program in the collaboration. Under the terms of the Gilead Collaboration Agreement, the Company and Gilead agreed to collaborate on the use of Merus’ proprietary Triclonics® platform to develop certain trispecific T-cell engaging multi-specific antibody products for the treatment of certain indications. The collaboration shall include at least two, but may include up to three, separate preclinical research programs (each, a “Program”) for the design and validation of candidates directed to the applicable Program targets selected by Gilead. On a Program-by-Program basis, the Company has granted Gilead an exclusive option to obtain an exclusive license for such Program. If Gilead exercises the license option with respect to a Program, Gilead will be responsible for clinical development and commercialization of the products arising from such Program. Upon exercise of its option to include the third Program in the collaboration, Gilead will pay the Company a non-refundable upfront initiation fee of $28.0 million, and Merus shall have the option to share in the worldwide net profit or loss, including development costs and expenses for the third Program only.

The initial term of the arrangement is the shorter of the completion of all activities under the applicable research plan or forty-eight months following the initiation of research plan activities. If, as of the fourth anniversary of the initiation of activities under the applicable Program, Merus has not completed the activities under the then current mutually agreed research plans in accordance with the timelines set forth therein (other than due to the act or omission of Gilead), the applicable term shall automatically be extended by an additional twelve months (for a maximum term of sixty months), unless otherwise extended by mutual agreement of the parties. Gilead's obligations under the collaboration to pay milestones and royalties, continues until the longer of an expiration of certain royalty bearing patents or fixed period after a first commercial sale. The arrangement may be terminated in its entirety or in relation to one or more Programs for any reason at any time upon ninety (90) days prior written notice to Merus.

At inception of the arrangement, the Company identified two performance obligations for each of the initial two Programs. The first is the License and Research single performance obligation comprised of a combined delivery of a nonexclusive license and related activities, including research activities associated with the Program and the activities of the joint steering committee. The second is the twelve-month extension (material right) for the Program. Merus accounted for the Program-by-Program options to obtain exclusive

licenses as a marketing offer because the exclusive license provides Gilead with additional clinical development and commercialization rights, and the license option exercise fee of $10.0 million on a Program-by-Program basis was estimated to be offered at the standalone selling price. The option to include a third Program was accounted for as a marketing offer because the non-refundable upfront initiation fee of $28.0 million was estimated to be offered at the standalone selling price.

The transaction price at inception was comprised of fixed consideration of $58.4 million that was derived from the $56.0 million non-refundable upfront payment and $25.0 million common shares purchase proceeds, net of the fair value of the common shares delivered to Gilead of $22.6 million. All other consideration under the arrangement was determined to be variable consideration and fully constrained at inception.

The fixed consideration was allocated equally between the Program #1 and Program #2 License and Research performance obligations. The equal allocation of the fixed consideration was based on the estimated standalone selling price of each performance obligation as each was materially the same.

The Company initially deferred $58.4 million allocated to the performance obligations to be recognized as revenue over time using an output method to measure progress towards completing the research activities dictated by each Program’s respective research plan. Development milestones, commercialization milestones and royalties are variable consideration, fully constrained, to be included in the transaction price for each performance obligation and recognized in future periods in accordance with the Company’s revenue recognition policy. The revenue recognized relating to each combined performance obligation is presented in the notes according to the source of consideration received (upfront and milestone), reflective of their differing timing of receipt.

As of June 30, 2024, research activities have commenced, but no milestones have been achieved. The Company received the $56.0 million upfront payment from Gilead in April 2024.

Lilly

On January 18, 2021, Eli Lilly and Company (“Lilly”) agreed to pay the Company a $40.0 million, non-refundable upfront payment, and purchased 706,834 common shares at a stated price per share of $28.295, for an aggregate purchase price of $20.0 million. The Company and Lilly agreed to collaborate with respect to the discovery and research of bispecific antibodies utilizing the Company’s proprietary Biclonics® bispecific technology platform. The collaboration encompasses up to three (3) independent programs directed to the generation of T-cell re-directing bispecific antibodies that bind CD3 and a tumor associated antigen target selected by Lilly to be the subject of each program.

The objective of each program is to develop a lead compound that Lilly would be able to continue to develop through clinical trials. Lilly agreed to fund the research activities the Company conducts for each program under an agreed research plan and budget. Lilly receives an exclusive, worldwide, royalty-bearing, sublicensable license, under certain patent rights and know-how to exploit certain compounds and products directed to designated targets in combination with targeting CD3, or directed to such designated target(s) alone as a monospecific antibody or monospecific antibody drug conjugate, subject to rights granted by Merus to third parties under one or more existing third party agreements. Merus retains all rights not granted to Lilly. Lilly has certain rights to replace selected targets, including the right to substitute a target selection after initial selection for a period of time. The Company may be entitled to further milestones and royalties in the future dependent on development and commercialization of any resulting product.

The initial term of the arrangement includes a three-year research term for the Company to perform research and development activities, subject to two extension terms of six months at Lilly’s discretion. While the arrangement may be terminated in its entirety or on a program-by-program basis at will by Lilly, there are no direct costs or penalties to Lilly to terminate the arrangement prior to the end of the initial term.

At inception of the arrangement, the Company identified a single performance obligation comprised of a combined delivery of a license and related activities, including research activities associated with a product candidate against the first target and the activities of the joint steering committee. The Company also identified two other combined performance obligations relating to options exercisable by Lilly to select a second and third target to advance a second and third product candidate against the selected targets through discovery and research.

The transaction price at inception was comprised of fixed consideration of $43.5 million that was derived from the $40.0 million upfront payment and $20.0 million share purchase proceeds, net of the fair value of the shares delivered to Lilly of $16.5 million, and variable consideration associated with the funding of research services for the product candidate against the first target at inception. All other consideration under the arrangement was determined to be variable consideration and fully constrained at inception.

The fixed consideration was allocated equally amongst the three performance obligations and the variable consideration associated with each target was allocated to the performance obligation of each respective target. The equal allocation of the fixed consideration was based on the estimated standalone selling price of each performance obligation as each was materially the same.

On February 12, 2021, the Company and Lilly completed the initial exchange of fixed consideration and transfer of common shares. The Company initially deferred $43.5 million allocated to the performance obligations to be recognized as revenue over time using a cost-to-cost measure of progress toward the development of a lead compound for each respective target, anticipated to be recognized as revenue within the initial research term, along with research funding. Development milestones, commercialization milestones and royalties are variable consideration, fully constrained, to be included in the transaction price for each performance obligation and recognized in future periods in accordance with the Company’s revenue recognition policy. The revenue recognized relating to each combined performance obligation is presented in the notes according to the source of consideration received (upfront, reimbursement revenue, milestone), reflective of their differing timing of receipt.

During the year ended December 31, 2022, Lilly substituted one of the target programs. Under the current research plan, for the program to be completed in collaboration with Merus, Lilly has extended the research term to 2025. Lilly exercised the first six month extension in October 2023 for which there was no associated fee. The program timeline has extended beyond this first extension, and such an extension into 2025 resulted in a fee of $0.5 million. Lilly exercised the second six month extension in May 2024 and the Company received the $0.5 million extension fee payment in July 2024. The $0.5 million extension is included in the Lilly cost-to-cost model as of June 30, 2024 and December 31, 2023.

As of June 30, 2024, research activities were on-going, and no milestones have been achieved.

Incyte

On January 23, 2017, the Company completed the sale of shares and exchange of a license with Incyte Corporation (“Incyte”). The Company initially deferred $152.6 million of the transaction price allocated to the license and related performance obligation as deferred revenue, to be recognized as revenue over time as the primary benefit of the license to Incyte is access to the Company’s intellectual property covering its Biclonics® technology platform for the generation of potential product candidates. Development milestones, commercialization milestones and royalties are variable consideration, fully constrained, to be recognized in future periods in accordance with the Company’s revenue recognition policy. Cost reimbursements for research services are recognized as they are performed over time as these are considered a separate performance obligation.

In January 2022, the Company announced that Incyte elected to opt-out of its ex-U.S. development of MCLA-145, from the parties joint collaboration agreement executed in 2017. At inception of the collaboration, for the designated product candidate (MCLA-145), the Company retained the exclusive right to develop and commercialize products and product candidates in the United States, while Incyte obtained the exclusive right to develop and commercialize products and product candidates arising from such program outside the United States. For MCLA-145, the parties conducted and shared equally the costs of mutually agreed global development activities. Incyte’s opt-out of ex-U.S. rights to MCLA-145 provides the Company the exclusive right to develop and commercialize potential MCLA-145 products globally. Under the collaboration, Incyte continued to support the program for a limited time while ex-U.S. activities transitioned to the Company. Incyte will retain a right to a residual royalty of up to 4% on sales of future commercialization of MCLA-145, if approved.

During the three months ended March 31, 2024, the Company recognized a $1.0 million milestone from Incyte related to candidate nomination. There were no development or commercialization milestones achieved during the three months ended June 30, 2024.

Ono

In April 2014, the Company granted Ono Pharmaceutical Co., Ltd. (“Ono”) an exclusive, worldwide, royalty-bearing license, with the right to sublicense, research, test, make, use and market a limited number of bispecific antibody candidates based on the Company’s Biclonics® technology platform against two undisclosed targets directed to a particular undisclosed target combination.

On March 14, 2018, the Company granted Ono an exclusive, worldwide, royalty-bearing license, with the right to sublicense, research, test, make, use and market a limited number of bispecific antibody candidates based on the Company’s Biclonics® technology platform against two undisclosed targets directed to a particular undisclosed target combination. Ono agreed to pay the Company an upfront, non-refundable payment of €0.7 million. In addition, the Company was entitled to €0.3 million intended to compensate the Company for research services already completed upon entering into the agreement, and €0.2 million to be paid to the Company over time for full-time equivalent funding. The Company is entitled to research and development milestones in addition to potential royalties on future sales of any bispecific antibody candidate that may be approved. The Company identified performance obligations for: (1) provision of a license for the target combination, and (2) research and development services. The Company concluded that Ono would be able to develop and benefit from the license, independent of the research and development services. Certain of the research and development services are capable of being performed by third parties with an appropriate sub-license, and are recognized over time as these services are delivered. Milestone payments are fully constrained as variable consideration to be recognized in future periods in accordance with the Company’s revenue recognition policy.

Amounts related to the provision of the licenses were amortized over the intended period of use. There were no development or commercialization milestones achieved during the six months ended June 30, 2024.

Contract Assets and Liabilities

The following tables provide amounts by year indicated and by line item included in the Company's accompanying condensed consolidated financial statements attributable to transactions arising from its collaboration arrangements. The dollar amounts in the tables below are in thousands.


	Incyte			Lilly			Gilead			Other			Total
CONTRACT ASSETS
Accounts receivable
Balance at January 1, 2024	$	—		$	—		$	—		$	—		$	—
Billings		4,055			1,629			55,999			13			61,696
Cash receipts		(4,055	)		(1,129	)		(55,999	)		(13	)		(61,196	)
Adjustments		—			—			—			—			—
Foreign exchange		—			—			—			—			—
Balance at June 30, 2024	$	—		$	500		$	—		$	—		$	500

Unbilled receivables
Balance at January 1, 2024	$	1,397		$	839		$	—		$	193		$	2,429
Accrued receivables		3,616			485			56,045			—			60,146
Billings		(4,055	)		(1,132	)		(56,045	)		—			(61,232	)
Adjustments		—			—			—			—			—
Foreign exchange		—			—			—			(1	)		(1	)
Balance at June 30, 2024	$	958		$	192		$	—		$	192		$	1,342

CONTRACT LIABILITIES
Deferred revenue
Balance at January 1, 2024	$	36,325		$	5,934		$	—		$	—		$	42,259
Additions to contract consideration		—			—			58,387			—			58,387
Revenue recognized in the period		(8,568	)		(1,272	)		(1,207	)		—			(11,047	)
Foreign exchange		(1,048	)		(172	)		(769	)		—			(1,989	)
Balance at June 30, 2024		26,709			4,490			56,411			—			87,610
Less: current portion		(17,059	)		(4,489	)		(10,802	)		—			(32,350	)
Non-current balance at June 30, 2024	$	9,650		$	1		$	45,609		$	—		$	55,260

The balance of unbilled receivables predominantly represents reimbursement revenue under the Company’s collaboration arrangements earned in the period to be billed and collected in the next period, generally quarterly.

Contract Revenues and Expenses


	Three Months Ended June 30, 2024
	(in thousands)
	Third Party
	Incyte		Lilly		Gilead		Other		Total
Collaboration Revenue
Upfront payments	$	4,266	$	462	$	1,207	$	—	$	5,935
Reimbursement revenue		1,202		190		—		—		1,392
Milestones		—		—		—		—		—
Other		—		—		—		5		5
Total collaboration revenue	$	5,468	$	652	$	1,207	$	5	$	7,332
Operating expenses:
Research and development expense	$	—	$	—	$	—	$	—	$	—
General and administrative expense		—		—		—		—		—
Total operating expenses from collaborations	$	—	$	—	$	—	$	—	$	—
Revenue recognized that was included in deferred revenue at the beginning of the period	$	4,266	$	462	$	1,207	$	—	$	5,935

	Three Months Ended June 30, 2023
	(in thousands)
	Third Party
	Incyte		Lilly		Gilead		Other		Total
Collaboration Revenue
Upfront payments	$	4,325	$	3,305	$	—	$	—	$	7,630
Reimbursement revenue		1,335		1,505		—		—		2,840
Milestones		—		—		—		—		—
Other		—		—		—		6		6
Total collaboration revenue	$	5,660	$	4,810	$	—	$	6	$	10,476
Operating expenses:
Research and development expense	$	—	$	—	$	—	$	—	$	—
General and administrative expense		—		—		—		—		—
Total operating expenses from collaborations	$	—	$	—	$	—	$	—	$	—
Revenue recognized that was included in deferred revenue at the beginning of the period	$	4,325	$	3,305	$	—	$	—	$	7,630


	Six Months Ended June 30, 2024
	(in thousands)
	Third Party
	Incyte		Lilly		Gilead		Other		Total
Collaboration Revenue
Upfront payments	$	8,568	$	1,272	$	1,207	$	—	$	11,047
Reimbursement revenue		2,660		504		—		—		3,164
Milestones		1,000		—		—		—		1,000
Other		—		—		—		10		10
Total collaboration revenue	$	12,228	$	1,776	$	1,207	$	10	$	15,221
Operating expenses:
Research and development expense	$	—	$	—	$	—	$	—	$	—
General and administrative expense		—		—		—		—		—
Total operating expenses from collaborations	$	—	$	—	$	—	$	—	$	—
Revenue recognized that was included in deferred revenue at the beginning of the period	$	8,568	$	1,272	$	1,207	$	—	$	11,047

	Six Months Ended June 30, 2023
	(in thousands)
	Third Party
	Incyte		Lilly		Gilead		Other		Total
Collaboration Revenue
Upfront payments	$	8,541	$	7,481	$	—	$	—	$	16,022
Reimbursement revenue		2,701		2,696		—		—		5,397
Milestones		2,501		—		—		—		2,501
Other		—		—		—		55		55
Total collaboration revenue	$	13,743	$	10,177	$	—	$	55	$	23,975
Operating expenses:
Research and development expense	$	24	$	—	$	—	$	—	$	24
General and administrative expense		—		—		—		—		—
Total operating expenses from collaborations	$	24	$	—	$	—	$	—	$	24
Revenue recognized that was included in deferred revenue at the beginning of the period	$	8,541	$	7,481	$	—	$	—	$	16,022

Income Taxes (Tables)

6 Months Ended

Jun. 30, 2024

Income Tax Disclosure [Abstract]

Summary of Components of Expense for (Benefit) from Income Taxes

The components of the income tax expense (benefit) from continuing operations are as follows:


	Three Months Ended June 30,						Six Months Ended June 30,
	2024			2023			2024		2023
	(in thousands)						(in thousands)
U.S. federal	$	1,827		$	1,544		$	1,951	$	1,451
U.S. state		756			637			807		601
Total current income tax expense (benefit)	$	2,583		$	2,181		$	2,758	$	2,052

U.S. federal	$	(188	)	$	(486	)	$	465	$	(718	)
U.S. state		(78	)		(201	)		192		(297	)
Total deferred income tax expense (benefit)	$	(266	)	$	(687	)	$	657	$	(1,015	)

Total income tax expense (benefit)	$	2,317		$	1,494		$	3,415	$	1,037

Leases (Tables)

6 Months Ended

Jun. 30, 2024

Leases [Abstract]

Summary of Components of Lease Cost

The components of lease expense for the three and six months ended June 30, 2024 and 2023 are as follows:


	Three Months Ended June 30,				Six Months Ended June 30,
	2024		2023		2024		2023
	(in thousands)				(in thousands)
Lease cost
Operating lease cost	$	518	$	514	$	1,034	$	1,226
Variable lease cost		63		56		118		84
Total lease cost included in operating expenses	$	581	$	570	$	1,152	$	1,310
Other information
Cash paid for amounts included in the measurement of lease liabilities included in operating cash flows	$	542	$	542	$	1,085	$	1,284

Common Share - Additional Information (Details)							1 Months Ended	3 Months Ended	6 Months Ended		12 Months Ended
Common Share - Additional Information (Details)	May 31, 2024 USD ($)	May 29, 2024 $ / shares shares	Mar. 05, 2024 USD ($) $ / shares shares	Aug. 14, 2023 USD ($)	Aug. 09, 2023 $ / shares shares	May 22, 2023 USD ($)	May 31, 2021 USD ($)	Jun. 30, 2023 USD ($) shares	Jun. 30, 2024 USD ($)	Jun. 30, 2023 USD ($)	Dec. 31, 2022 USD ($) shares	Jun. 30, 2024 € / shares	Jun. 30, 2024 USD ($) shares	May 29, 2024 € / shares	Feb. 29, 2024 USD ($)	Dec. 31, 2023 € / shares	Dec. 31, 2023 USD ($) shares	Aug. 09, 2023 € / shares
Class of Stock [Line Items]
Common shares, value, issued													$ 6,863,000				$ 5,883,000
Common shares, issued \| shares													67,852,920				57,825,879
Gross proceeds, before deducting sales agent commissions									$ 434,863,000	$ 63,796,000
Common shares, par value \| € / shares												€ 0.09				€ 0.09
Sales Agreement
Class of Stock [Line Items]
Common shares, issued \| shares											2,720,846
Common shares, sold \| shares								3,272,280
Gross proceeds, before deducting sales agent commissions								$ 65,500,000			$ 59,500,000
Sales agent commissions											$ 1,700,000
Net proceeds, after deducting sales agent fees, underwriting discounts and commissions						$ 124,900,000		$ 63,800,000
Sales Agreement \| Maximum
Class of Stock [Line Items]
Shares sale agreement authorized amount						$ 125,000,000	$ 125,000,000
Underwriting commissions rate of gross proceeds of shares sold							3.00%
Underwriting Agreement
Class of Stock [Line Items]
Common shares, sold \| shares					6,818,182
Net proceeds, after deducting sales agent fees, underwriting discounts and commissions				$ 162,200,000
Sale of shares, price per share \| $ / shares					$ 22
Common shares, par value \| € / shares																		€ 0.09
Additional common shares at public offering price \| shares					1,022,727
Gilead Collaboration Agreement
Class of Stock [Line Items]
Common shares, sold \| shares			452,527
Common shares stated purchase price per share \| $ / shares			$ 55.2454
Gross proceeds, before deducting sales agent commissions			$ 25,000,000
2024 Sales Agreement
Class of Stock [Line Items]
Common shares, issued \| shares													0
2024 Sales Agreement \| Maximum
Class of Stock [Line Items]
Shares sale agreement authorized amount															$ 300,000,000
Underwriting commissions rate of gross proceeds of shares sold									3.00%
2024 Underwriting Agreement
Class of Stock [Line Items]
Common shares, sold \| shares		7,550,000
Net proceeds, after deducting sales agent fees, underwriting discounts and commissions	$ 434,900,000
Sale of shares, price per share \| $ / shares		$ 53
Common shares, par value \| € / shares														€ 0.09
Additional common shares at public offering price \| shares		1,132,500

Income Taxes

6 Months Ended

Jun. 30, 2024

Income Tax Disclosure [Abstract]

Income Taxes

5. Income Taxes

The Company files income tax returns for its subsidiary Merus US, Inc. in the U.S. federal and Massachusetts jurisdictions as well as for the Company in the Netherlands. The components of the income tax expense (benefit) from continuing operations are as follows:


	Three Months Ended June 30,						Six Months Ended June 30,
	2024			2023			2024		2023
	(in thousands)						(in thousands)
U.S. federal	$	1,827		$	1,544		$	1,951	$	1,451
U.S. state		756			637			807		601
Total current income tax expense (benefit)	$	2,583		$	2,181		$	2,758	$	2,052

U.S. federal	$	(188	)	$	(486	)	$	465	$	(718	)
U.S. state		(78	)		(201	)		192		(297	)
Total deferred income tax expense (benefit)	$	(266	)	$	(687	)	$	657	$	(1,015	)

Total income tax expense (benefit)	$	2,317		$	1,494		$	3,415	$	1,037

After consideration of all positive and negative evidence, we believe that it is more-likely-than-not that the Netherlands deferred tax assets that are not supported by reversing temporary differences, will not be realized. As a result, we established a full valuation allowance against deferred tax assets of the Netherlands.

Under Dutch tax law, net operating loss carryforwards may be used to offset future taxable income in full up to €1.0 million and 50% of taxable income that exceeds €1.0 million. Effective as of January 1, 2022, these losses can be carried forward indefinitely.

- Definition

The entire disclosure for income tax.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-12

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 740
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-Name Accounting Standards Codification
-Section 55
-Paragraph 231
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
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-Paragraph 12C
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-URI https://asc.fasb.org/1943274/2147482685/740-10-50-12C

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-Section 50
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org/1943274/2147477891/740-270-50-1

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: 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 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-Name Accounting Standards Codification
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-URI https://asc.fasb.org/740/tableOfContent

Reference 10: 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 11: 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 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
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-Paragraph 17
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Reference 13: 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 14: 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

Collaborations - Summary of Company's Accompanying Consolidated Financial Statements Attributable to Transactions Arising From Collaboration Arrangements (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Incyte
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue recognized in the period	$ 4,266	$ 4,325	$ 8,568	$ 8,541
Incyte \| Accounts Receivable
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Billings			4,055
Cash receipts			(4,055)
Incyte \| Unbilled Receivables
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Balance at January 1, 2024			1,397
Accrued receivables			3,616
Billings			(4,055)
Balance at June 30, 2024	958		958
Incyte \| Deferred Revenue
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Balance at January 1, 2024	26,709		26,709		$ 36,325
Revenue recognized in the period			(8,568)
Foreign exchange			(1,048)
Balance at June 30, 2024	26,709		26,709		36,325
Less: current portion	(17,059)		(17,059)
Non-current balance at June 30, 2024	9,650		9,650
Lilly
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue recognized in the period	462	3,305	1,272	7,481
Lilly \| Accounts Receivable
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Billings			1,629
Cash receipts			(1,129)
Balance at June 30, 2024	500		500
Lilly \| Unbilled Receivables
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Balance at January 1, 2024			839
Accrued receivables			485
Billings			(1,132)
Balance at June 30, 2024	192		192
Lilly \| Deferred Revenue
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Balance at January 1, 2024	4,490		4,490		5,934
Revenue recognized in the period			(1,272)
Foreign exchange			(172)
Balance at June 30, 2024	4,490		4,490		5,934
Less: current portion	(4,489)		(4,489)
Non-current balance at June 30, 2024	1		1
Gilead
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue recognized in the period	1,207	0	1,207	0
Gilead \| Accounts Receivable
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Billings			55,999
Cash receipts			(55,999)
Gilead \| Unbilled Receivables
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Accrued receivables			56,045
Billings			(56,045)
Gilead \| Deferred Revenue
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Balance at January 1, 2024	56,411		56,411
Additions to contract consideration			58,387
Revenue recognized in the period			(1,207)
Foreign exchange			(769)
Balance at June 30, 2024	56,411		56,411
Less: current portion	(10,802)		(10,802)
Non-current balance at June 30, 2024	45,609		45,609
Other
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue recognized in the period	0	0	0	0
Other \| Accounts Receivable
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Billings			13
Cash receipts			(13)
Other \| Unbilled Receivables
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Balance at January 1, 2024			193
Foreign exchange			(1)
Balance at June 30, 2024	192		192
Collaboration Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue recognized in the period	5,935	$ 7,630	11,047	$ 16,022
Collaboration Agreement \| Accounts Receivable
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Billings			61,696
Cash receipts			(61,196)
Balance at June 30, 2024	500		500
Collaboration Agreement \| Unbilled Receivables
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Balance at January 1, 2024			2,429
Accrued receivables			60,146
Billings			(61,232)
Foreign exchange			(1)
Balance at June 30, 2024	1,342		1,342
Collaboration Agreement \| Deferred Revenue
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Balance at January 1, 2024	87,610		87,610		42,259
Additions to contract consideration			58,387
Revenue recognized in the period			(11,047)
Foreign exchange			(1,989)
Balance at June 30, 2024	87,610		87,610		$ 42,259
Less: current portion	(32,350)		(32,350)
Non-current balance at June 30, 2024	$ 55,260		$ 55,260

Collaborations - Additional Information (Details) $ / shares in Units, € in Millions					1 Months Ended		3 Months Ended		6 Months Ended		12 Months Ended
	Mar. 05, 2024 USD ($) $ / shares shares	Jan. 18, 2021 USD ($) $ / shares shares	Mar. 14, 2018 EUR (€)	Jan. 23, 2017 USD ($)	Jul. 31, 2024 USD ($)	Jan. 31, 2022	Jun. 30, 2024 USD ($) Milestone	Mar. 31, 2024 USD ($)	Jun. 30, 2024 USD ($) Milestone	Jun. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)	Apr. 30, 2024 USD ($)	Feb. 12, 2021 USD ($)
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Proceeds from issuance of common stock, net									$ 434,863,000	$ 63,796,000
Lilly Collaborations Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Non-refundable upfront payment receivable		$ 40,000,000
Issuance of common share, net, shares \| shares		706,834
Common shares stated purchase price per share \| $ / shares		$ 28.295
Proceeds from issuance of common stock, net		$ 20,000,000
Fixed consideration		43,500,000											$ 43,500,000
Fee incurred for extension of research term											$ 500,000
Upfront payment		40,000,000
Net fair value of shares		$ 16,500,000
Number of milestones achieved \| Milestone							0		0
Lilly Collaborations Agreement \| Subsequent Events
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Extension fee payment of research term received					$ 500,000
Incyte Collaboration and License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Development milestones recognized							$ 0	$ 1,000,000
Incyte Collaboration and License Agreement \| Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Residual royalty percentage						4.00%
Incyte Collaboration and License Agreement \| License and Related Activities
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaborations, transaction price as deferred revenue				$ 152,600,000
Second ONO Research and License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Non-refundable upfront payment receivable \| €			€ 0.7
Payment to compensate research services \| €			0.3
Over time payment for full time equivalent funding \| €			€ 0.2
Development milestones recognized									$ 0
Gilead Collaboration Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Non-refundable upfront payment receivable	$ 56,000,000
Issuance of common share, net, shares \| shares	452,527
Common shares stated purchase price per share \| $ / shares	$ 55.2454
Proceeds from issuance of common stock, net	$ 25,000,000
Fixed consideration	58,400,000
Net fair value of shares	22,600,000
Non-refundable upfront payment received												$ 56,000,000
Number of milestones achieved \| Milestone							0		0
Non-refundable upfront initiation fee	28,000,000
License option exercise fee	$ 10,000,000

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) (Parenthetical) - € / shares	Jun. 30, 2024	Dec. 31, 2023
Statement of Financial Position [Abstract]
Common shares, par value	€ 0.09	€ 0.09
Common shares, authorized	105,000,000	105,000,000
Common shares, issued	67,852,920	57,825,879
Common shares, outstanding	67,852,920	57,825,879

CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (UNAUDITED) - USD ($) $ in Thousands	Total	Public Offerings, Net of Underwriting Discounts and Commissions and Offering Cost [Member]	Gilead [Member]	Common Shares [Member]	Common Shares [Member] Public Offerings, Net of Underwriting Discounts and Commissions and Offering Cost [Member]	Common Shares [Member] Gilead [Member]	Additional Paid-In Capital [Member]	Additional Paid-In Capital [Member] Public Offerings, Net of Underwriting Discounts and Commissions and Offering Cost [Member]	Additional Paid-In Capital [Member] Gilead [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Beginning balance at Dec. 31, 2022	$ 247,055			$ 4,751			$ 870,874			$ (598,122)	$ (30,448)
Beginning balance, shares at Dec. 31, 2022				46,310,589
Exercise of share options and vesting of restricted share units	217			$ 3			214
Exercise of share options and vesting of restricted share units, shares				30,592
Share-based compensation	5,750						5,750
Currency translation adjustment	4,242										4,242
Net loss	(39,741)									(39,741)
Ending balance at Mar. 31, 2023	217,523			$ 4,754			876,838			(637,863)	(26,206)
Ending balance, shares at Mar. 31, 2023				46,341,181
Beginning balance at Dec. 31, 2022	247,055			$ 4,751			870,874			(598,122)	(30,448)
Beginning balance, shares at Dec. 31, 2022				46,310,589
Currency translation adjustment	3,737
Net loss	(71,774)
Ending balance at Jun. 30, 2023	257,405			$ 5,099			948,913			(669,896)	(26,711)
Ending balance, shares at Jun. 30, 2023				49,853,659
Beginning balance at Mar. 31, 2023	217,523			$ 4,754			876,838			(637,863)	(26,206)
Beginning balance, shares at Mar. 31, 2023				46,341,181
Issuance of common share		$ 63,719			$ 322			$ 63,397
Issuance of common share, net, shares					3,272,280
Exercise of share options and vesting of restricted share units	2,248			$ 23			2,225
Exercise of share options and vesting of restricted share units, shares				240,198
Share-based compensation	6,453						6,453
Currency translation adjustment	(505)										(505)
Net loss	(32,033)									(32,033)
Ending balance at Jun. 30, 2023	257,405			$ 5,099			948,913			(669,896)	(26,711)
Ending balance, shares at Jun. 30, 2023				49,853,659
Beginning balance at Dec. 31, 2023	356,343			$ 5,883			1,126,054			(753,061)	(22,533)
Beginning balance, shares at Dec. 31, 2023				57,825,879
Issuance of common share			$ 22,613			$ 45			$ 22,568
Issuance of common share, net, shares						452,527
Exercise of share options and vesting of restricted share units	7,543			$ 40			7,503
Exercise of share options and vesting of restricted share units, shares				409,145
Share-based compensation	4,793						4,793
Currency translation adjustment	(7,388)										(7,388)
Net loss	(34,456)									(34,456)
Ending balance at Mar. 31, 2024	349,448			$ 5,968			1,160,918			(787,517)	(29,921)
Ending balance, shares at Mar. 31, 2024				58,687,551
Beginning balance at Dec. 31, 2023	356,343			$ 5,883			1,126,054			(753,061)	(22,533)
Beginning balance, shares at Dec. 31, 2023				57,825,879
Currency translation adjustment	(16,366)
Net loss	(84,498)
Ending balance at Jun. 30, 2024	746,772			$ 6,863			1,616,367			(837,559)	(38,899)
Ending balance, shares at Jun. 30, 2024				67,852,920
Beginning balance at Mar. 31, 2024	349,448			$ 5,968			1,160,918			(787,517)	(29,921)
Beginning balance, shares at Mar. 31, 2024				58,687,551
Issuance of common share		$ 434,530			$ 848			$ 433,682
Issuance of common share, net, shares					8,682,500
Exercise of share options and vesting of restricted share units	10,128			$ 47			10,081
Exercise of share options and vesting of restricted share units, shares				482,869
Share-based compensation	11,686						11,686
Currency translation adjustment	(8,978)										(8,978)
Net loss	(50,042)									(50,042)
Ending balance at Jun. 30, 2024	$ 746,772			$ 6,863			$ 1,616,367			$ (837,559)	$ (38,899)
Ending balance, shares at Jun. 30, 2024				67,852,920

- Definition

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

+ References

+ Details

- Definition

Equity impact of the value of new stock issued during the period. Includes shares issued in an initial public offering or a secondary public offering.

+ References + Details

- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 210
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-Name Accounting Standards Codification
-Section S99
-Paragraph 1
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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-Section S99
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Reference 4: http://www.xbrl.org/2003/role/exampleRef
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-SubTopic 10
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-Section 55
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-URI https://asc.fasb.org/1943274/2147481372/852-10-55-10

Reference 5: http://www.xbrl.org/2003/role/exampleRef
-Topic 946
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-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479168/946-830-55-12

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 210
-Name Accounting Standards Codification
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-Subparagraph (SX 210.6-05(4))
-Publisher FASB
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Reference 8: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-3

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Subparagraph (SX 210.6-09(6))
-Publisher FASB
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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Reference 11: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
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-Paragraph 1
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-Publisher FASB
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Reference 12: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 323
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481687/323-10-50-3

Reference 13: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 825
-SubTopic 10
-Name Accounting Standards Codification
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-Paragraph 28
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-Publisher FASB
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Reference 14: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 310
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-Name Accounting Standards Codification
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-Paragraph 2
-Subparagraph (SAB Topic 4.E)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480418/310-10-S99-2

+ Details

Investments in Debt Securities

6 Months Ended

Jun. 30, 2024

Debt Securities [Abstract]

Investments in Debt Securities

3. Investments in Debt Securities

The following tables summarize the Company’s investments in debt securities and their presentation in the condensed consolidated balance sheet:


	June 30, 2024		December 31, 2023
	(in thousands)
Money market funds	$	20,246	$	24,273
Corporate paper and notes		150,988		146,415
U.S. government agency securities		60,215		39,456
U.S. treasuries		5,706		21,571
Total	$	237,155	$	231,715

Fair value of debt securities	$	236,880	$	231,945


	June 30, 2024		December 31, 2023
	(in thousands)
Cash equivalents	$	20,246	$	24,273
Current marketable securities		157,948		150,130
Non-current marketable securities		58,961		57,312
Total	$	237,155	$	231,715

The Company does not intend to sell and the Company believes it is unlikely that the Company will be required to sell the above investments before recovery of their amortized cost bases, which may be at maturity. The Company determined that there was no material change in the credit risk of any of its investments.

The fair value of money market funds is determined based on publicly available market price for these funds (Level 1). The fair value of other debt securities is determined based on the publicly available inputs which includes a market price for the same or similar instruments adjusted for estimates in interest yield (Level 2).

Collaborations (Tables)

6 Months Ended

Jun. 30, 2024

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Summary of Company's Accompanying Condensed Consolidated Financial Statements Attributable to Transactions Arising From Collaboration Arrangements


	Incyte			Lilly			Gilead			Other			Total
CONTRACT ASSETS
Accounts receivable
Balance at January 1, 2024	$	—		$	—		$	—		$	—		$	—
Billings		4,055			1,629			55,999			13			61,696
Cash receipts		(4,055	)		(1,129	)		(55,999	)		(13	)		(61,196	)
Adjustments		—			—			—			—			—
Foreign exchange		—			—			—			—			—
Balance at June 30, 2024	$	—		$	500		$	—		$	—		$	500

Unbilled receivables
Balance at January 1, 2024	$	1,397		$	839		$	—		$	193		$	2,429
Accrued receivables		3,616			485			56,045			—			60,146
Billings		(4,055	)		(1,132	)		(56,045	)		—			(61,232	)
Adjustments		—			—			—			—			—
Foreign exchange		—			—			—			(1	)		(1	)
Balance at June 30, 2024	$	958		$	192		$	—		$	192		$	1,342

CONTRACT LIABILITIES
Deferred revenue
Balance at January 1, 2024	$	36,325		$	5,934		$	—		$	—		$	42,259
Additions to contract consideration		—			—			58,387			—			58,387
Revenue recognized in the period		(8,568	)		(1,272	)		(1,207	)		—			(11,047	)
Foreign exchange		(1,048	)		(172	)		(769	)		—			(1,989	)
Balance at June 30, 2024		26,709			4,490			56,411			—			87,610
Less: current portion		(17,059	)		(4,489	)		(10,802	)		—			(32,350	)
Non-current balance at June 30, 2024	$	9,650		$	1		$	45,609		$	—		$	55,260

Summary of Company's Collaboration Arrangements Earned in Period to Be Billed and Collected in Next Period

Contract Revenues and Expenses


	Three Months Ended June 30, 2024
	(in thousands)
	Third Party
	Incyte		Lilly		Gilead		Other		Total
Collaboration Revenue
Upfront payments	$	4,266	$	462	$	1,207	$	—	$	5,935
Reimbursement revenue		1,202		190		—		—		1,392
Milestones		—		—		—		—		—
Other		—		—		—		5		5
Total collaboration revenue	$	5,468	$	652	$	1,207	$	5	$	7,332
Operating expenses:
Research and development expense	$	—	$	—	$	—	$	—	$	—
General and administrative expense		—		—		—		—		—
Total operating expenses from collaborations	$	—	$	—	$	—	$	—	$	—
Revenue recognized that was included in deferred revenue at the beginning of the period	$	4,266	$	462	$	1,207	$	—	$	5,935

	Three Months Ended June 30, 2023
	(in thousands)
	Third Party
	Incyte		Lilly		Gilead		Other		Total
Collaboration Revenue
Upfront payments	$	4,325	$	3,305	$	—	$	—	$	7,630
Reimbursement revenue		1,335		1,505		—		—		2,840
Milestones		—		—		—		—		—
Other		—		—		—		6		6
Total collaboration revenue	$	5,660	$	4,810	$	—	$	6	$	10,476
Operating expenses:
Research and development expense	$	—	$	—	$	—	$	—	$	—
General and administrative expense		—		—		—		—		—
Total operating expenses from collaborations	$	—	$	—	$	—	$	—	$	—
Revenue recognized that was included in deferred revenue at the beginning of the period	$	4,325	$	3,305	$	—	$	—	$	7,630


	Six Months Ended June 30, 2024
	(in thousands)
	Third Party
	Incyte		Lilly		Gilead		Other		Total
Collaboration Revenue
Upfront payments	$	8,568	$	1,272	$	1,207	$	—	$	11,047
Reimbursement revenue		2,660		504		—		—		3,164
Milestones		1,000		—		—		—		1,000
Other		—		—		—		10		10
Total collaboration revenue	$	12,228	$	1,776	$	1,207	$	10	$	15,221
Operating expenses:
Research and development expense	$	—	$	—	$	—	$	—	$	—
General and administrative expense		—		—		—		—		—
Total operating expenses from collaborations	$	—	$	—	$	—	$	—	$	—
Revenue recognized that was included in deferred revenue at the beginning of the period	$	8,568	$	1,272	$	1,207	$	—	$	11,047

	Six Months Ended June 30, 2023
	(in thousands)
	Third Party
	Incyte		Lilly		Gilead		Other		Total
Collaboration Revenue
Upfront payments	$	8,541	$	7,481	$	—	$	—	$	16,022
Reimbursement revenue		2,701		2,696		—		—		5,397
Milestones		2,501		—		—		—		2,501
Other		—		—		—		55		55
Total collaboration revenue	$	13,743	$	10,177	$	—	$	55	$	23,975
Operating expenses:
Research and development expense	$	24	$	—	$	—	$	—	$	24
General and administrative expense		—		—		—		—		—
Total operating expenses from collaborations	$	24	$	—	$	—	$	—	$	24
Revenue recognized that was included in deferred revenue at the beginning of the period	$	8,541	$	7,481	$	—	$	—	$	16,022

Leases - Additional Information (Details) - USD ($)	Mar. 31, 2023	Dec. 31, 2022
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Liability, to be Paid, Total		$ 100,000
Former Corporate Headquarters
Lessee, Lease, Description [Line Items]
Operating lease liability	$ 0

Subsequent Events - Additional Information (Details) € in Thousands		6 Months Ended
	Jul. 01, 2024 USD ($) shares	Jun. 30, 2024 USD ($) shares	Jul. 24, 2024 EUR (€)	Jul. 24, 2024 USD ($)
Subsequent Event [Line Items]
Number of options granted to purchase common shares \| shares		2,659,757
Subsequent Events \| Consulting Agreement
Subsequent Event [Line Items]
Consulting fee	$ 41,000
Subsequent Events \| Intellectual Property Rights Agreements relating to Petosemtamab One
Subsequent Event [Line Items]
Milestone payments to be made to certain intellectual property rights agreements \| €			€ 3,000
Subsequent Events \| Intellectual Property Rights Agreements relating to Petosemtamab Two
Subsequent Event [Line Items]
Milestone payments to be made to certain intellectual property rights agreements \| €			1,000
Subsequent Events \| Intellectual Property Rights Agreements relating to Petosemtamab Three
Subsequent Event [Line Items]
Milestone payments to be made to certain intellectual property rights agreements				$ 500,000
Subsequent Events \| License Agreement Concerning Certain Technology Related to Petosemtamab
Subsequent Event [Line Items]
Milestone payments to be made to certain intellectual property rights agreements \| €			€ 150
Chief Medical Officer
Subsequent Event [Line Items]
Amount of Annual base salary		$ 503,000
Annual performance based bonus percentage		40.00%
Chief Medical Officer \| 2016 Incentive Award Plan
Subsequent Event [Line Items]
Number of options granted to purchase common shares \| shares		183,943
Chief Medical Officer \| Subsequent Events \| 2016 Incentive Award Plan
Subsequent Event [Line Items]
Award vesting rights, percentage	25.00%
Award vesting rights, required service period	36 months
Chief Business Officer and Head \| Subsequent Events \| Separation Agreement and Release
Subsequent Event [Line Items]
Lump sum payment payable	$ 17,500
Chief Business Officer and Head \| Subsequent Events \| Maximum \| Separation Agreement and Release
Subsequent Event [Line Items]
Reimbursement of professional fees	$ 10,000
Chief Business Officer and Head \| Restricted Stock Units (RSUs) \| Subsequent Events \| Separation Agreement and Release
Subsequent Event [Line Items]
Accelerated vesting of restricted stock units granted \| shares	3,000

Leases

6 Months Ended

Jun. 30, 2024

Leases [Abstract]

Leases

7. Leases

The Company has noncancelable operating leases for offices and lab spaces expiring at various dates through 2032.

On December 7, 2022, the Company signed a second lease amendment terminating the lease for the former corporate headquarters as of January 1, 2023. The Company continued to make payments through mid-February 2023. The Company accounted for the second amendment as a lease modification and reduced the lease liability and right-of-use asset by approximately $0.1 million to equal to the remaining lease payments. As of March 31, 2023, the lease liability and right-of-use asset for the former corporate headquarters was $0. In July 2019, the Company entered into a lease agreement with Kadans Science Partner XIII B.V. for the Accelerator headquarters, which commenced in April 2022. On April 5, 2024, in accordance with the terms of the lease agreement, the annual rent for the Accelerator lease increased due to increases in the consumer price index (CPI). The portion of the rent payments related to the CPI index are included within variable lease costs. There have been no changes in the Company’s lease arrangements for the three months ended June 30, 2024.

The components of lease expense for the three and six months ended June 30, 2024 and 2023 are as follows:


	Three Months Ended June 30,				Six Months Ended June 30,
	2024		2023		2024		2023
	(in thousands)				(in thousands)
Lease cost
Operating lease cost	$	518	$	514	$	1,034	$	1,226
Variable lease cost		63		56		118		84
Total lease cost included in operating expenses	$	581	$	570	$	1,152	$	1,310
Other information
Cash paid for amounts included in the measurement of lease liabilities included in operating cash flows	$	542	$	542	$	1,085	$	1,284

Investments in Debt Securities (Tables)

6 Months Ended

Jun. 30, 2024

Debt Securities [Abstract]

Summary of Investments in Debt Securities in Condensed Consolidated Balance Sheet

The following tables summarize the Company’s investments in debt securities and their presentation in the condensed consolidated balance sheet:


	June 30, 2024		December 31, 2023
	(in thousands)
Money market funds	$	20,246	$	24,273
Corporate paper and notes		150,988		146,415
U.S. government agency securities		60,215		39,456
U.S. treasuries		5,706		21,571
Total	$	237,155	$	231,715

Fair value of debt securities	$	236,880	$	231,945


	June 30, 2024		December 31, 2023
	(in thousands)
Cash equivalents	$	20,246	$	24,273
Current marketable securities		157,948		150,130
Non-current marketable securities		58,961		57,312
Total	$	237,155	$	231,715

Income Taxes - Summary of Components of Expense for (Benefit) from Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Income Tax Disclosure [Abstract]
U.S. federal	$ 1,827	$ 1,544	$ 1,951	$ 1,451
U.S. state	756	637	807	601
Total current income tax expense (benefit)	2,583	2,181	2,758	2,052
U.S. federal	(188)	(486)	465	(718)
U.S. state	(78)	(201)	192	(297)
Total deferred income tax expense (benefit)	(266)	(687)	657	(1,015)
Total income tax expense (benefit)	$ 2,317	$ 1,494	$ 3,415	$ 1,037

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 270
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-Paragraph 1
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: 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

Supplemental Balance Sheet Information - Schedule of Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Prepaid Expense and Other Assets, Current [Abstract]
Prepaid research and development expenses	$ 8,780	$ 6,872
Prepaid general and administrative expenses	4,749	2,058
Interest receivable	2,053	1,552
Other	1,706	1,527
Total	$ 17,288	$ 12,009

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Jun. 30, 2024
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Leases - Summary of Components of Lease Cost (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Lease cost
Operating lease cost	$ 518	$ 514	$ 1,034	$ 1,226
Variable lease cost	63	56	118	84
Total lease cost included in operating expenses	581	570	1,152	1,310
Other information
Cash paid for amounts included in the measurement of lease liabilities included in operating cash flows	$ 542	$ 542	$ 1,085	$ 1,284

Common Share

6 Months Ended

Jun. 30, 2024

Equity [Abstract]

Common Share

9. Common Share

Share Issuances

In May 2021, the Company entered into an Open Market Sale Agreement (the “Sales Agreement”) with Jefferies LLC (“Jefferies”) to sell from time to time up to $125.0 million of the Company’s common shares through an “at-the-market” offering program under which Jefferies acts as the sales agent. Subject to the terms and conditions of the Sales Agreement, Jefferies could sell the common shares by any method deemed to be an “at-the-market” offering as defined in Rule 415 promulgated under the Securities Act of 1933, as amended (the “Securities Act”).

Jefferies was entitled to compensation at a commission rate of up to 3.0% of the gross proceeds of shares sold under the Sales Agreement. In connection with the sale of the common shares on the Company's behalf, Jefferies was deemed to be an “underwriter” within the meaning of the Securities Act and the compensation of Jefferies was deemed to be underwriting commissions or discounts. The Company agreed to provide indemnification and contribution to Jefferies with respect to certain liabilities, including liabilities under the Securities Act or the Securities Exchange Act of 1934, as amended (the "Exchange Act").

As of December 31, 2022, the Company, pursuant to the Sales Agreement, had issued and sold an aggregate of 2,720,846 shares of its common shares resulting in gross proceeds of $59.5 million, before deducting sales agent fees of $1.7 million.

During the three months ended June 30, 2023, the Company sold 3,272,280 shares of its common shares under the Sales Agreement for gross proceeds of approximately $65.5 million and net proceeds of approximately $63.8 million, after deducting sales agent fees. Having sold approximately $124.9 million of the $125.0 million available under the Sales Agreement, on May 22, 2023, the Company delivered written notice to Jefferies, effective as of such date, to terminate the Sales Agreement. The Company was not subject to any termination penalties related to the termination of the Sales Agreement.

On August 9, 2023, the Company entered into an underwriting agreement (the “Underwriting Agreement”) with Jefferies LLC, BofA Securities, Inc., Guggenheim Securities, LLC and William Blair & Company, L.L.C., as representatives of the several underwriters named therein (collectively, the “Underwriters”), in connection with the issuance and sale by the Company in a public offering of 6,818,182 common shares of the Company, nominal value €0.09 per share, at a public offering price of $22.00 per share, less underwriting discounts and commissions, pursuant to an effective shelf registration statement on Form S-3 and accompanying prospectus (Registration No. 333-255903), which became effective upon filing on May 7, 2021, and a prospectus supplement thereunder. Under the terms of the Underwriting Agreement, the Company also granted the Underwriters an option exercisable for 30 days to purchase up to an additional 1,022,727 common shares at the public offering price, less underwriting discounts and commissions. On August 10, 2023, the Underwriters exercised this option in full. The offering closed on August 14, 2023, and the Company received net proceeds of $162.2 million, after deducting underwriting discounts and fees.

In February 2024, the Company entered into an Open Market Sale Agreement (the “2024 Sales Agreement”) with Jefferies LLC to sell from time to time up to $300.0 million of the Company’s common shares through an “at-the-market” offering program under which Jefferies acts as the sales agent. Subject to the terms and conditions of the 2024 Sales Agreement, Jefferies could sell the common shares by any method deemed to be an “at-the-market” offering as defined in Rule 415 promulgated under Securities Act.

Jefferies was entitled to compensation at a commission rate of up to 3.0% of the gross proceeds of any shares sold under the 2024 Sales Agreement. In connection with any sale of the common shares on the Company's behalf, Jefferies would be deemed to be an “underwriter” within the meaning of the Securities Act and the compensation of Jefferies would be deemed to be underwriting commissions or discounts. The Company agreed to provide indemnification and contribution to Jefferies with respect to certain liabilities, including liabilities under the Securities Act or the Exchange Act. There have been no sales under the 2024 Sales Agreement through June 30, 2024.

In connection with entering into the Gilead Collaboration Agreement in March 2024, pursuant to the Subscription Agreement, Gilead purchased 452,527 common shares of the Company at a price per share of $55.2454 for aggregate gross proceeds to the Company of approximately $25.0 million. Gilead agreed not to transfer, sell, or otherwise dispose of the shares for a period of time following the purchase of the shares, subject to certain customary exceptions.

On May 29, 2024, the Company entered into an underwriting agreement (the “2024 Underwriting Agreement”) with Jefferies LLC, BofA Securities, Inc., Leerink Partners LLC, Guggenheim Securities, LLC and BMO Capital Markets Corp., as representatives of the several underwriters named therein (collectively, the “2024 Underwriters”), in connection with the issuance and sale by the Company in a public offering of 7,550,000 common shares of the Company, nominal value €0.09 per share, at a public offering price of $53.00 per share, less underwriting discounts and commissions, pursuant to an effective shelf registration statement on Form S-3 and accompanying prospectus (Registration No. 333-277465), which became effective upon filing on February 28, 2024, and a prospectus supplement thereunder. Under the terms of the 2024 Underwriting Agreement, the Company also granted the 2024 Underwriters an option exercisable for 30 days to purchase up to an additional 1,132,500 common shares at the public offering price, less underwriting discounts and commissions. On May 30, 2024, the Underwriters exercised this option in full. The offering closed on May 31, 2024, and the Company received net proceeds of $434.9 million, after deducting underwriting discounts and commissions.

- Definition

The entire disclosure for equity.

+ References

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

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Employee Benefits - Additional Information (Details) - $ / shares		6 Months Ended
	Feb. 01, 2024	Jun. 30, 2024
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average fair value of options granted		$ 23.93
Share-Based Payment Arrangement, Valuation Technique [Extensible Enumeration]		Black Scholes Option Pricing Model
Number of options granted		2,659,757
Contingent Stock Option [Member] \| Board of Directors
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of options granted	2,446,045
Weighted-average exercise price per share, granted	$ 36.09

- 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

Investments in Debt Securities - Summary of Investments in Debt Securities in Condensed Consolidated Balance Sheet (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Schedule Of Held To Maturity Securities [Line Items]
Total	$ 237,155	$ 231,715
Fair value of debt securities	236,880	231,945
Cash equivalents [member]
Schedule Of Held To Maturity Securities [Line Items]
Total	20,246	24,273
Current marketable securities [member]
Schedule Of Held To Maturity Securities [Line Items]
Total	157,948	150,130
Non-current marketable securities [member]
Schedule Of Held To Maturity Securities [Line Items]
Total	58,961	57,312
Money market funds [member]
Schedule Of Held To Maturity Securities [Line Items]
Total	20,246	24,273
Corporate paper and notes [member]
Schedule Of Held To Maturity Securities [Line Items]
Total	150,988	146,415
U.S. government agency securities [member]
Schedule Of Held To Maturity Securities [Line Items]
Total	60,215	39,456
U.S. treasuries [member]
Schedule Of Held To Maturity Securities [Line Items]
Total	$ 5,706	$ 21,571

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Total revenue	$ 7,332	$ 10,476	$ 15,221	$ 23,975
Operating expenses:
Research and development	49,119	28,298	87,703	63,163
General and administrative	22,587	16,063	38,701	31,449
Total operating expenses	71,706	44,361	126,404	94,612
Operating loss	(64,374)	(33,885)	(111,183)	(70,637)
Other income, net:
Interest income, net	7,130	2,795	12,047	4,790
Foreign exchange gains (loss)	9,519	551	18,053	(4,890)
Total other income (loss), net	16,649	3,346	30,100	(100)
Net loss before income taxes	(47,725)	(30,539)	(81,083)	(70,737)
Income tax expense	2,317	1,494	3,415	1,037
Net loss	(50,042)	(32,033)	(84,498)	(71,774)
Other comprehensive loss:
Currency translation adjustment	(8,978)	(505)	(16,366)	3,737
Comprehensive loss	$ (59,020)	$ (32,538)	$ (100,864)	$ (68,037)
Net loss per share attributable to common stockholders:
Basic	$ (0.81)	$ (0.66)	$ (1.41)	$ (1.52)
Diluted	$ (0.81)	$ (0.66)	$ (1.41)	$ (1.52)
Weighted-average common shares outstanding:
Basic	61,851,260	48,321,708	59,968,338	47,328,259
Diluted	61,851,260	48,321,708	59,968,338	47,328,259
Collaboration Revenue [Member]
Total revenue from contracts with customers	$ 7,332	$ 10,476	$ 15,221	$ 23,975