Efficacy and safety of cosibelimab in advanced cutaneous squamous cell carcinoma: Results from a Pivotal Open-label Study with a median follow-up of ≥2 years

Abstract

Background Cosibelimab-ipdl, a high-affinity, programmed death-ligand 1–blocking antibody, is approved by the US Food and Drug Administration for treatment of adults with metastatic cutaneous squamous cell carcinoma (mCSCC) or locally advanced CSCC (laCSCC) who are not candidates for curative surgery or radiation. Objective To report long-term efficacy and safety outcomes from a pivotal study of cosibelimab in mCSCC or laCSCC. Methods Patients received intravenous cosibelimab 800 mg every 2 weeks (mCSCC and laCSCC cohorts) or 1200 mg every 3 weeks (mCSCC cohort). The primary endpoint was objective response rate (ORR). Secondary endpoints included duration of response (DOR) and safety. Results With a median follow-up duration of 29.3 months for the mCSCC cohort (n = 78), ORR was 50.0% (complete response [CR], 12.8%), median DOR was not reached, and estimated 24-month DOR was 72.1%. With a median follow-up duration of 24.1 months for the laCSCC cohort (n = 31), ORR was 54.8% (CR, 25.8%), median DOR was not reached, and the estimated 24-month DOR was 80.2%. Immune-related adverse event rate was 27.6%; 3.6% grade 3, no grade ≥4 events. Limitations Nonrandomized; limited biomarker analysis. Conclusion Cosibelimab demonstrated robust and durable ORRs with increasing CR rates in advanced CSCC and low rates of severe immune-related adverse events.