Abstract
BACKGROUND: To provide pooled longer term data from three groups of a phase 2 study of cemiplimab in patients with advanced cutaneous squamous cell carcinoma (CSCC), and to determine duration of response (DOR) and impact on quality of life (QoL). METHODS: Patients received cemiplimab 3 mg/kg every 2 weeks (group 1, metastatic CSCC [mCSCC], n=59; group 2, locally advanced CSCC, n=78) or cemiplimab 350 mg every 3 weeks (group 3, mCSCC, n=56). Primary endpoint was objective response rate (ORR) per independent central review (ICR). QoL was repeatedly measured at day 1 of each treatment cycle (groups 1 and 2: 8 weeks; group 3: 9 weeks). RESULTS: Median duration of follow-up was 15.7 months. Overall, ORR per ICR was 46.1% (95% CI: 38.9% to 53.4%). Complete response (CR) rates were 20.3%, 12.8%, and 16.1% for groups 1, 2, and 3, respectively. Median time to CR was 11.2 months. Among patients with partial response or CR, the estimated proportion of patients with ongoing response at 12 months from the first objective response was 87.8% (95% CI: 78.5% to 93.3%), with median DOR not reached. Kaplan-Meier estimated probability of overall survival (OS) was 73.3% (95% CI: 66.1% to 79.2%) at 24 months, with median OS not reached. Global Health Status (GHS)/QoL improvements were observed as early as cycle 2 and were significantly improved and durable until last assessment. Kaplan-Meier estimate of median time to first clinically meaningful improvement for pain was 2.1 (95% CI: 2.0 to 3.7) months and was significantly improved in responders versus non-responders (p<0.0001). CONCLUSIONS: This is the largest (n=193) clinical dataset for a programmed cell death-1 inhibitor against advanced CSCC, confirming the sustained substantial clinical activity of cemiplimab in these patients, including new findings of improved CR rates over time, increasing DOR, and durable pain control and GHS/QoL improvement. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov Registry (NCT02760498), https://clinicaltrialsgov/ct2/show/NCT02760498.