• 60% response rate observed among 10 evaluable patients
• Favorable safety profile in 26 patients enrolled as of the abstract cutoff date, with no significant overlapping toxicities observed
  
• Conference call on Tuesday, May 28 at 8:00 a.m. ET to discuss full ASCO^® data set

UTRECHT, The Netherlands and CAMBRIDGE, Mass., May 23, 2024 (GLOBE NEWSWIRE) -- Merus N.V. (Nasdaq: MRUS) (Merus, the Company, we, or our), a clinical-stage oncology company developing innovative, full-length multispecific antibodies (Biclonics^® and Triclonics^®), today announced the publication of an abstract regarding petosemtamab in combination with pembrolizumab on the 2024 American Society of Clinical Oncology^® (ASCO^®) Annual Meeting website. The abstract presents interim clinical data from a cohort of 26 patients enrolled as of the abstract cutoff date, evaluating the combination in first line (1L) recurrent/metastatic (r/m) head and neck squamous cell carcinoma (HNSCC) for presentation at the 2024 ASCO^® Annual Meeting taking place in Chicago, May 31-June 4, 2024.

The full dataset for these patients will be discussed on a conference call on Tuesday, May 28 at 8:00 a.m. ET.

“We believe petosemtamab continues to demonstrate potential best in class safety and efficacy in head and neck cancer. We are encouraged with the well tolerated safety profile of the combination of petosemtamab and pembrolizumab, particularly with a low rate of Grade 3 or greater adverse events, and a low rate of infusion-related reactions observed,” said Bill Lundberg, M.D., President, Chief Executive Officer of Merus. “These data in the abstract provide encouraging efficacy albeit from an early cutoff date, with less mature data. And we look forward to our conference call, Tuesday May 28, to discuss the more mature clinical update from a later cutoff date where the response rate further improved.”

Petosemtamab (MCLA-158: EGFR x LGR5 Biclonics^®): Solid Tumors

Rapid oral presentation title: Petosemtamab (MCLA-158) with pembrolizumab as first-line (1L) treatment of recurrent/metastatic (r/m) head and neck squamous cell carcinoma (HNSCC): Phase 2 study.
Observations in the abstract include:  

• As of a November 6, 2023 data cutoff date, 26 patients (pts) were treated; with 24 continuing therapy
  • 10 pts were evaluable for response (≥2 cycles and ≥1 post-baseline scan, or early progressive disease [PD]) and 6 responses were observed. This included 1 confirmed complete response, 2 confirmed partial responses, and 3 unconfirmed partial responses (2 confirmed as of the abstract submission and the 3^rd also subsequently confirmed) by Response Evaluation Criteria in Solid Tumors v1.1
  • The combination was well tolerated and no significant overlapping toxicities were observed. Treatment-emergent adverse events were reported in all patients, most were Grade 1 or 2 in severity. Infusion related reactions (composite term) were reported in 26.9% (all Grades) of which 3.8% were Grade 3, and all occurred during first infusion and resolved.

Presentation Details:
Abstract #: 6014 
Session Title: Head and Neck Cancer 
Session Date and Time: June 3, 2024, 8:00-9:30 a.m. CT 

As full presentations become available at the 2024 ASCO^® Annual Meeting, they will contemporaneously be available on the Merus website.

Company Conference Call and Webcast Information
Merus will hold a conference call and webcast for investors on Tuesday, May 28, 2024 at 8:00 a.m. ET. A replay will be available after the completion of the call in the Investors and Media section of our website for a limited time. 

Date & Time: May 28, 2024 at 8:00 a.m. ET
Webcast link: Available on our website
Dial-in: Toll Free: 1 (800) 715-9871/ International: 1 (646) 307-1963
Conference ID: 4160163

About Merus N.V.  

Merus is a clinical-stage oncology company developing innovative full-length human bispecific and trispecific antibody therapeutics, referred to as Multiclonics^®. Multiclonics^® are manufactured using industry standard processes and have been observed in preclinical and clinical studies to have several of the same features of conventional human monoclonal antibodies, such as long half-life and low immunogenicity. For additional information, please visit Merus’ website, http://www.merus.nl  
and https://twitter.com/MerusNV.  

Forward-Looking Statements

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. All statements contained in this press release that do not relate to matters of historical fact should be considered forward-looking statements, including without limitation statements regarding the clinical development of our clinical candidates, including petosemtamab, future clinical trial results or interim data, clinical activity and safety profile, and development plans in the on-going trials and described in forthcoming posters or presentations; our belief that petosemtamab continues to demonstrate potential best in class safety and efficacy in head and neck cancer; the observations of response rate and safety profile of the combination of petosemtamab and pembrolizumab, and any impact on future patients treated with this combination. These forward-looking statements are based on management’s current expectations. These forward-looking statements are based on management’s current expectations. These statements are neither promises nor guarantees, but involve known and unknown risks, uncertainties and other important factors that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements, including, but not limited to, the following: our need for additional funding, which may not be available and which may require us to restrict our operations or require us to relinquish rights to our technologies or Biclonics^®, Triclonics^® and multispecific antibody candidates; potential delays in regulatory approval, which would impact our ability to commercialize our product candidates and affect our ability to generate revenue; the lengthy and expensive process of clinical drug development, which has an uncertain outcome; the unpredictable nature of our early stage development efforts for marketable drugs; potential delays in enrollment of patients, which could affect the receipt of necessary regulatory approvals; our reliance on third parties to conduct our clinical trials and the potential for those third parties to not perform satisfactorily; impacts of the market volatility; we may not identify suitable Biclonics^® or bispecific antibody candidates under our collaborations or our collaborators may fail to perform adequately under our collaborations; our reliance on third parties to manufacture our product candidates, which may delay, prevent or impair our development and commercialization efforts; protection of our proprietary technology; our patents may be found invalid, unenforceable, circumvented by competitors and our patent applications may be found not to comply with the rules and regulations of patentability; we may fail to prevail in potential lawsuits for infringement of third-party intellectual property; and our registered or unregistered trademarks or trade names may be challenged, infringed, circumvented or declared generic or determined to be infringing on other marks.

These and other important factors discussed under the caption “Risk Factors” in our Annual Report on Form 10-Q for the quarter ended March 31, 2024 filed with the Securities and Exchange Commission, or SEC, on May 8, 2024, and our other reports filed with the SEC, could cause actual results to differ materially from those indicated by the forward-looking statements made in this press release. Any such forward-looking statements represent management’s estimates as of the date of this press release. While we may elect to update such forward-looking statements at some point in the future, we disclaim any obligation to do so, even if subsequent events cause our views to change, except as required under applicable law. These forward-looking statements should not be relied upon as representing our views as of any date subsequent to the date of this press release.

Multiclonics^®, Biclonics^® and Triclonics^® are registered trademarks of Merus N.V.