Phase 2 study of cemiplimab, a human monoclonal anti-PD-1, in patients (pts) with metastatic cutaneous squamous cell carcinoma (mCSCC; Group 1): 12-month follow-up.

Abstract

9526 Background: Primary analysis (Oct 2017) of cemiplimab (REGN2810) in pts with mCSCC in a Phase 2 study demonstrated substantial antitumor activity, durable responses, and acceptable safety profile. We now report 12-month follow-up data from these pts (NCT02760498; data cutoff date: Sep 20, 2018). Methods: Pts with mCSCC received cemiplimab 3 mg/kg IV every 2 weeks (Q2W). Tumor measurements were performed Q8W. The primary objective was to evaluate objective response rate (ORR; complete response [CR] + partial response [PR]) according to independent central review (per RECIST 1.1 for scans; modified WHO criteria for photos). Results: 59 pts (median age: 71 years) were enrolled. Median duration of follow-up was 16.5 months (range: 1.1–26.6). ORR by central review was 49.2% (95% CI: 35.9–62.5; 10 CRs and 19 PRs [4 CRs and 25 PRs by investigator-assessment (INV)]). Median duration of response (DOR) has not been reached. The longest DOR at data cut-off was 21.6 months and was still ongoing. Observed DOR exceeded 12 months in 22/29 pts (75.9%) with response. Durable disease control rate (stable disease or response for ≥16 weeks) was 62.7% (95% CI: 49.1–75.0). Median observed time to response was 1.9 months (range: 1.7–9.1). Median progression-free survival was 18.4 months (95% CI: 7.3–not evaluable); median overall survival has not been reached. The most common treatment-emergent adverse events (all grades, Grade ≥3) were diarrhea (28.8%, 1.7%), fatigue (25.4%, 1.7%), and nausea (23.7%, 0%). By INV, grade ≥3 immune-related adverse events occurred in 13.6% of pts. Conclusions: This analysis demonstrates substantial antitumor activity and increasing DOR with cemiplimab 3 mg/kg Q2W in pts with mCSCC. There were no new safety signals. These data strongly support the recent FDA approval of cemiplimab-rwlc for pts with mCSCC or locally advanced CSCC who are not candidates for curative surgery or curative radiation. Clinical trial information: NCT02760498.