Merus Announces Presentation of Petosemtamab Abstract at AACR-NCI-EORTC International Conference

Merus announces the publication of an abstract on petosemtamab in metastatic colorectal cancer. Preliminary data shows the drug's efficacy and manageable safety profile when combined with FOLFOX/FOLFIRI in 1L and 2L mCRC and as monotherapy in 3L+ mCRC. The data will be presented at the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics.

Merus N.V. (Nasdaq: MRUS) has announced the publication of an abstract on petosemtamab, a bispecific antibody, in metastatic colorectal cancer (mCRC). The preliminary data, presented at the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics, demonstrates the drug's efficacy and manageable safety profile when combined with FOLFOX/FOLFIRI in 1L and 2L mCRC, as well as when used as monotherapy in 3L+ mCRC.

The abstract, titled "Petosemtamab (MCLA-158) monotherapy or with chemotherapy in metastatic colorectal cancer: Preliminary antitumor activity and safety data from a phase 2 trial," was presented by Dr. Moh’d Khushman, M.D., of Washington University School of Medicine, St. Louis, MO. The data cutoff date for the ongoing phase 2 trial was April 28, 2025.

In the 1L setting, petosemtamab in combination with FOLFOX/FOLFIRI showed promising results, with 6 ongoing patients out of 7 treated, including 1 unconfirmed complete response and 2 partial responses (PRs). In the 2L setting, 10 patients were treated, with 8 ongoing, and 4 PRs, 3 stable diseases (SDs), and 1 clinical deterioration observed.

In the 3L+ setting, 19 patients were treated with petosemtamab monotherapy, with 12 ongoing. The data showed 1 unconfirmed PR, 6 SDs, 6 progressive diseases, and 1 death unrelated to treatment.

The safety profile of petosemtamab was also manageable, with no fatal treatment-related adverse events observed in each cohort. The most frequent treatment-emergent adverse events (TEAEs) included dermatitis acneiform, constipation, fatigue, and peripheral neuropathy with FOLFOX; diarrhea, mucosal inflammation, and fatigue with FOLFIRI; and rash and nausea with monotherapy.

Merus, an oncology company developing innovative full-length human bispecific and trispecific antibody therapeutics, expects to provide a more mature clinical update at the conference. The company's Multiclonics®, Biclonics®, Triclonics®, and ADClonics® are manufactured using industry standard processes and have shown favorable clinical outcomes in preclinical and clinical studies.