Merus presents interim data on MCLA-145 monotherapy, combo with pembrolizumab

Merus announced updated interim clinical data on MCLA-145 monotherapy and in combination with pembrolizumab were presented at the 2024 American Society of Clinical Oncology Annual Meeting taking place in Chicago May 31-June 4, 2024. MCLA-145: Solid Tumors – Interim data included in the presentation describe data from patients with advanced/metastatic solid tumors who received MCLA-145 Q2W in 28 day cycles or every three weeks in 21 day cycles. Patients treated with the combination of MCLA-145 and pembrolizumab had cancers that either relapsed after PD-(L)1 therapies or were immunotherapy naive. Rapid oral presentation title: Phase I study of MCLA-145, a bispecific antibody targeting CD137 and PD-L1, in solid tumors, as monotherapy or in combination with pembrolizumab. Observations in the presentation include: As of a January 3, 2024 data cutoff date, 72 pts with multiple cancer types were treated; 25% of pts had non-small cell lung cancer; All patients were heavily pre-treated with a median of 3 prior therapies; prior IO in 49% of the monotherapy pts and 100% of the combination pts; In monotherapy, 52 pts with a variety of tumor types and treated at different dose levels were evaluable for response; 5 partial responses were observed at different dose levels in glioblastoma, sarcoma, cervical, anal, and gastric cancer by Response Evaluation Criteria in Solid Tumors v1.1. per investigator assessment; 2 of 6 pts PRs were observed for pts treated at the recommended dose for expansion, 40 mg Q3W; 3 of 6 PRs were observed for pts with evaluable baseline tumor CD8 T-cell density of greater than or equal to 250 cells/mm2 responded; In combination with pembrolizumab, 19 pts with a variety of tumor types and treated at different dose levels were evaluable for response; 1 PR in Merkel cell carcinoma was observed at 25 mg Q3W; 1 complete response was observed in PD-L1+ NSCLC at the RDE 40 mg Q3W; 3 pts were continuing combination therapy at cutoff date; MCLA-145 monotherapy or in combination with pembrolizumab had a well-tolerated and manageable safety profile at the RDE, 40mg Q3W; Shifting from Q2W to Q3W resulted in a 50% reduction of Grade greater than or equal to3 treatment-emergent adverse events in both monotherapy and combination therapy; Liver toxicity, a common CD137 related adverse event, was controlled with no G4 events observed at Q3W.