As reported at the 2018 ASCO Annual Meeting (Abstract 9519) and in The New England Journal of Medicine by Migden et al, results of early-phase testing show activity of the programmed cell death protein 1 (PD-1) inhibitor cemiplimab in advanced cutaneous squamous cell carcinoma. Currently, no systemic therapies are approved in advanced disease; activity of immune therapy is posited on the basis of characteristic high mutation burden and association of disease with immunosuppression.
The current report involves 26 evaluable patients with locally advanced or metastatic disease in a phase I expansion cohort and 59 patients with metastatic disease in a phase II trial. All patients received cemiplimab at 3 mg/kg every 2 weeks.
In the expansion cohort of the phase I study, objective response was observed in 13 (50%) of 26 patients (all partial responses). In the metastatic disease cohort of the phase II study, objective response was observed in 28 (47%) of 59 patients, with complete response in 4 patients.
In the phase II study, the median follow-up was 7.9 months. Among the 28 responders in the phase II study, the duration of response was > 6 months in 57%, and 82% had maintained response and continued to receive cemiplimab at data cutoff.
In the phase I population, the most common adverse events of any grade were fatigue (27%), followed by constipation, decreased appetite, diarrhea, hypercalcemia, hypophosphatemia, nausea, and urinary tract infection (15% each). In the phase II population, the most common adverse events were diarrhea (27%), fatigue (24%), nausea (17%), constipation (15%), and rash (15%). In this population, 7% of patients discontinued treatment due to adverse events.
Adverse events of grade ≥ 3 occurring in > 1 patient were cellulitis, pneumonitis, hypercalcemia, pleural effusion, and death. Adverse events led to death in 1 patient in the phase I population and 3 patients in the phase II population.
The investigators concluded, “Among patients with advanced cutaneous squamous cell carcinoma, cemiplimab induced a response in approximately half the patients and was associated with adverse events that usually occur with immune checkpoint inhibitors.”
The study was funded by Regeneron Pharmaceuticals and Sanofi.
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