Merus Announces First Patient Treated in Phase 1/2 Clinical Trial of MCLA-129 in Advanced Lung Cancer and Other Solid Tumors

Merus’ Fourth Sponsored Bispecific Antibody Currently in Clinical Trials

UTRECHT, The Netherlands and CAMBRIDGE, MA, USA I May 03, 2021 IMerus 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 that the first patient has been treated in its phase 1/2 dose escalation and expansion trial evaluating MCLA-129 for the treatment of patients with advanced non-small cell lung cancer (NSCLC) and other solid tumors. MCLA-129 is a Biclonics®, which binds to EGFR and c-MET. EGFR is an important oncogenic driver in many cancers, and upregulation of c-MET signaling has been associated with resistance to EGFR inhibition.

“The initiation of our phase 1/2 trial of MCLA-129 is an important step in our goal to provide meaningful treatments to patients with cancer, including NSCLC,” said Dr. Andrew Joe, Chief Medical Officer of Merus. “Despite the successes with targeted therapies, patients will often develop resistance to currently approved treatments. Based on our preclinical data and other data, we are excited to investigate MCLA-129 as a potential new treatment option for patients with lung and other cancers, especially those that do not respond to EGFR inhibitors.”

The phase 1/2, open-label clinical trial of MCLA-129 consists of dose escalation followed by dose expansion. Primary objectives of phase 1 are to determine the maximum tolerated dose and/or the recommended phase 2 dose, and the objectives of phase 2 are to evaluate safety, tolerability and potential clinical activity of the recommended phase 2 dose in patients with advanced solid tumors.

More details of the trial can be found at

MCLA-129 is the subject of a collaboration agreement between Merus and Betta Pharmaceuticals Co. Ltd. (Betta). In January 2019, Merus and Betta announced this strategic collaboration to develop MCLA-129, where Merus granted Betta an exclusive license to develop and potentially commercialize MCLA-129 in China, with Merus retaining all rights outside of China. In January 2021, Betta announced that the Chinese National Medical Product Administration accepted its Investigational New Drug application of MCLA-129 injection.

About MCLA-129
MCLA-129 is an antibody-dependent cellular cytotoxicity-enhanced Biclonics® that is designed to inhibit the EGFR and c-MET signaling pathways in solid tumors. Preclinical data have shown that MCLA-129 can effectively treat TKI-resistant NSCLC in xenograft models of cancer. MCLA-129 is designed to have two complementary mechanisms of action: blocking growth and survival pathways to stop tumor expansion and recruitment and enhancement of immune effector cells to eliminate the tumor.

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 and Twitter.


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