Merus Petosemtamab phase 2 mCRC results show high response rates

Merus announced interim clinical data (29 July 2025 cutoff) from the ongoing phase 2 trial of petosemtamab (EGFR x LGR5 bispecific antibody) + standard of care FOLFOX/FOLFIRI (chemo) in 1L, 2L metastatic CRC (mCRC) and petosemtamab monotherapy in 3L+ mCRC. The results were presented at the AACR-NCI-EORTC, and confirm and build upon the responses reported from an initial dataset with a previous cut-off date (28 April 2025). We view the numbers as competitive vs. cetuximab (EGFR antibody) + FOLFOX, which has shown a 65% ORR in the 1L setting, and a 30% ORR in the 2L setting, and point to the candidate's potential beyond its lead indication of head and neck cancer. As a reminder, Merus is in the process of being acquired by Genmab for $ 8b. BUY maintained.