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Soo Park, MD
Soo Park, MD
Posted: Tuesday, January 21, 2025
In the phase III C-POST trial, adjuvant treatment with the PD-1 inhibitor cemiplimab-rwlc led to a statistically significant and clinically meaningful improvement in the primary endpoint of disease-free survival in patients with high-risk cutaneous squamous cell carcinoma after surgery, announced Regeneron Pharmaceuticals. Use of the monoclonal antibody yielded a 68% reduction in the risk of disease recurrence or death in these patients compared with placebo, with a median duration of follow-up of 24 months (range, 2–64 months), with a hazard ratio of 0.32; 95% confidence interval of 0.20–0.51, P < .0001.
C-POST enrolled 415 patients with high-risk cutaneous squamous cell carcinoma, who were randomly assigned to receive either cemiplimab or placebo for up to 48 weeks. Disease-free survival was defined as the time from randomization to the first documented disease recurrence or death from any cause. Trial participants are at high risk of recurrence because of nodal features (extracapsular extension or at least three involved lymph nodes) and/or non-nodal features (in-transit metastases, T4 lesion, perineural invasion, or locally recurrent tumor with at least one additional poor prognostic feature). For the first 12 weeks, cemiplimab at 350 mg or placebo is administered intravenously every 3 weeks, followed by cemiplimab at 700 mg or placebo administered intravenously every 6 weeks for 36 weeks.
Safety was assessed in 205 patients in the cemiplimab arm and 204 patients in the placebo arm. Adverse events of any grade occurred in 91% and 89% of patients in the cemiplimab arm and the placebo arm, respectively. Grade ≥ 3 adverse events were reported in 24% and 14% of patients in the cemiplimab arm and the placebo arm, respectively. Treatment discontinuations because of adverse reactions occurred in 10% and 1.5% of patients in the cemiplimab arm and the placebo arm, respectively. Two patients experienced an adverse event leading to death in each arm.
Following these interim results, C-POST will continue for additional follow-up, including an analysis of the key secondary endpoint of overall survival.
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