Primary analysis of phase 2 results of cemiplimab, a human monoclonal anti-PD-1, in patients (pts) with locally advanced cutaneous squamous cell carcinoma (laCSCC).

Abstract

6015 Background: Cemiplimab (REGN2810) produced substantial antitumor activity with durable responses in Phase 1 CSCC expansion cohorts and Phase 2 metastatic (m) CSCC cohort. We now present the primary analysis of the Phase 2 laCSCC cohort (NCT02760498; data cutoff date: Oct 10, 2018). Methods: Pts with laCSCC 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: 78 pts were enrolled (59 M/ 19 F; median age: 74 years; ECOG PS: 0 in 38 pts, 1 in 40 pts; primary CSCC site: head/neck in 79.5%; prior systemic therapy: 15.4%; prior radiotherapy: 55.1%). Median duration of follow-up was 9.3 months (range: 0.8–27.9). ORR by central review was 43.6% (95% CI: 32.4–55.3; 10 CRs and 24 PRs); investigator-assessed (INV) ORR was 52.6% (95% CI: 40.9–64.0; 13 CRs and 28 PRs). Median duration of response (DOR) has not been reached. The longest DOR at data cut-off was 24.2 months and was still ongoing. Durable disease control rate (stable disease or response for ≥16 weeks) was 62.8% (95% CI: 51.1–73.5). Median observed time to response was 1.9 months (range: 1.8–8.8). Median progression-free and overall survival have not been reached. Tumor PD-L1 status is available for 48/78 pts, tumor mutational burden analysis (from targeted exome panel) is ongoing for ≥40/78 pts; response correlation analyses are planned. The most common treatment-emergent adverse events (AEs; all grades, Grade ≥3) were fatigue (42.3%, 1.3%), diarrhea and pruritus (both 26.9%, 0%), and nausea (21.8%, 0%). INV grade ≥3 immune-related AEs occurred in 10.3% of pts. One pt died due to an unknown cause that was assessed as treatment-related. Conclusions: Cemiplimab 3 mg/kg Q2W showed substantial antitumor activity, durable responses, and acceptable safety profile in pts with laCSCC. These data strongly support the recent FDA approval of cemiplimab-rwlc for pts with mCSCC or laCSCC who are not candidates for curative surgery or curative radiation. Clinical trial information: NCT02760498.