Merus announces interim clinical data on petosemtamab with pembrolizumab

Merus announced interim clinical data as of a March 6, 2024 data cutoff from the ongoing phase 1/2 trial of the bispecific antibody petosemtamab in combination with pembrolizumab. These data will be presented by Dr. Jerome Fayette M.D. Ph.D., Centre Leon Berard, Lyon, France at the 2024 American Society of Clinical Oncology Annual Meeting on Monday, June 3 at 8 a.m. CT. Petosemtamab: Solid Tumors: Rapid oral presentation title: Petosemtamab with pembrolizumab as first-line treatment of recurrent/metastatic head and neck squamous cell carcinoma: Phase 2 study. Observations in the presentation include: As of a March 6, 2024 data cutoff date, 45 patients were treated; 26 patients were enrolled as of the abstract cutoff date; The efficacy population consisted of 24 patients who had the opportunity for 4 or more months follow up, with greater than or equal to2 treatment cycles and greater than or equal to1 post-baselinetumor assessment; or whodiscontinued early due to diseaseprogression or death; Two patients were not included: One patient withdrew consent prior to first tumor assessment and the other patient discontinued due to toxicity with less than 2 cycles of treatment; Response rates overall: 67%, including 1 confirmed complete response, 12 confirmed partial responses and 3 unconfirmed PRs by Response Evaluation Criteria in Solid Tumors v1.1. per investigator assessment, including; 3 of 4 patients with HPV associated cancer responded; Responses observed across PD-L1 levels; At the time of data cutoff, 32 patients of the 45 enrolled, remained on treatment, including 14 of 16 responders and 18 of the initial 26 patients enrolled; Median follow up of 3.6 months for the 45 patients; In 45 patients the combination was well tolerated and no significant overlapping toxicities with pembrolizumab were observed; Treatment-emergent adverse events were reported in 45 pts; Most were Grade 1 or 2 in severity; Infusion-related reactions were reported in 38% and 7% of pts, most occurred during the first infusion and resolved.