Merus Announces Petosemtamab in Metastatic Colorectal Cancer Abstract Selected for Plenary Session Oral Presentation at the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics

-   Plenary session oral presentation: Friday, October 24 10:00 -11:40 a.m. ET

-   Poster presentation on preclinical evaluation of petosemtamab on cancer stem cells: Friday, October 24 12:30-4:00 p.m. ET

UTRECHT, The Netherlands and CAMBRIDGE, Mass., Oct. 13, 2025 (GLOBE NEWSWIRE) -- (Nasdaq: MRUS) (Merus, the Company, we, or our), an oncology company developing innovative, full-length multispecific antibodies and antibody drug conjugates (Biclonics^®, Triclonics^® and ADClonics^®), today announced the acceptance of two abstracts on petosemtamab, a Biclonics^® targeting EGFR and LGR5, for presentation at the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics, being held in Boston, Massachusetts on October 22-26, 2025.

Initial interim data from the phase 2 trial evaluating petosemtamab in combination with standard chemotherapy in 1L and 2L metastatic colorectal cancer (mCRC), and as monotherapy in heavily pretreated (3L+) mCRC will be presented in a plenary session by Dr. Moh’d Khushman M.D., Washington University School of Medicine, St. Louis, MO. Merus will also present a poster regarding the preclinical evaluation of petosemtamab on cancer stem cells.

Presentations:

Title: Petosemtamab (MCLA-158) monotherapy or with chemotherapy in metastatic colorectal cancer: Preliminary antitumor activity and safety data from a phase 2 trial

Session Title: Plenary Session 4: Clinical Trials Plenary Session

Date and Time: Friday, October 24 10:00-11:40 a.m. ET

The same data will also be available in a poster:

Session Title: Poster Session B

Session Date and Time: Friday, October 24, 12:30-4:00 p.m. ET

Poster presentation:

Title: Preclinical evaluation of petosemtamab, an epidermal growth factor receptor (EGFR) and leucine-rich repeat-containing G protein-coupled receptor (LGR5) bispecific antibody, on cancer stem cells

Session Title: Poster Session B

Session Date and Time: Friday, October 24, 12:30-4:00 p.m. ET

The abstracts will be available in the conference app on Wednesday, October 22, 2025 at 12:00 p.m. ET. The full presentations are planned to be available on the Merus  at the start of each session.

About Petosemtamab

Petosemtamab, or MCLA-158, is a Biclonics^® low-fucose human full-length IgG1 antibody targeting the epidermal growth factor receptor (EGFR) and the leucine-rich repeat containing G-protein-coupled receptor 5 (LGR5). Petosemtamab is designed to exhibit three independent mechanisms of action including inhibition of EGFR-dependent signaling, LGR5 binding leading to EGFR internalization and degradation in cancer cells, and enhanced antibody-dependent cell-mediated cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP) activity.

About Merus N.V.

 is an oncology company developing innovative full-length human bispecific and trispecific antibody therapeutics, referred to as . 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’  and .

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. 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 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 volatility in the global economy, including global instability, including the ongoing conflicts in Europe and the Middle East; 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 Quarterly Report on Form 10-Q for the period ended June 30, 2025, filed with the Securities and Exchange Commission, or SEC, on August 5, 2025, 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.