Real world safety outcomes using cemiplimab for cutaneous squamous cell carcinoma

Locally advanced or metastatic cutaneous squamous cell carcinoma (cSCC) mostly affects older and frail patients. Cemiplimab is an anti-PD1 antibody used in this indication since its approval by the FDA and the EMA in 2019 after encouraging results from phase II trials. We aimed to evaluate cemiplimab safety in patients from daily practice.

Retrospective and monocentric study including all patients who received at least one infusion of cemiplimab between August 2018 and September 2019. Adverse effects (AEs), treatment interruption, and efficacy were recorded (data cut-off, November 1st 2020).

Twenty-two patients were included, median age was 83 [55-93], 73% were Eastern Cooperative Oncology Group (ECOG) 0 or 1, 36% were immune compromised. After a median time on treatment of six months [0.7-22], seventeen patients (77%) experienced 24 AEs, comprising 45% serious AEs (SAEs) grade ≥ 3 and one SAE grade 5 (myositis). Patients who presented SAEs were all >65 years old. Nine patients (41%) definitively discontinued treatment due to AEs. Seventeen patients were evaluable, after a median follow-up of eleven months [1-22], 32% had an objective response (2 complete and 5 partial responses), 47% had controlled disease and 35% experienced progression.

In our cohort, safety seemed to be worse than in phase II trial with more treatment discontinuations due to cemiplimab toxicity, probably reflecting the distinct demographic and medical characteristics of patients in daily care.