Long-term survival after anti-PD-1 discontinuation in advanced cutaneous squamous cell carcinoma (cSCC): a proof of concept of benefit of concomitant cemiplimab and radiotherapy.

BACKGROUND: In a princeps study we conducted in patients with advanced cutaneous squamous cell carcinoma treated with concomitant anti-Programmed cell death protein 1 (PD-1) and radiotherapy, we demonstrated a clinico radiological response to cemiplimab that appeared to persist over time, 1 year after treatment discontinuation.

METHOD: We conducted a single-center descriptive study at Caen Hospital from September 1, 2021 to September 2023, in 14 patients with advanced carcinoma treated with cemiplimab until September 1, 2021. The aim of this update is to examine clinical and radiological follow-up 2 years after discontinuation of cemiplimab.

RESULTS: Of the 12 patients with a partial or complete response, we report 8 (66.7%) persistent responses 2 years after stopping cemiplimab, with only 2 patients progressing to distant disease, one lost to follow-up, and one death a priori unrelated to the disease.

CONCLUSION: Our study confirms a long-term and persistent effect despite discontinuation of cemiplimab at least up to 2 years later.