Extended follow-up outcomes of patients with advanced cutaneous squamous cell carcinoma treated with cemiplimab on EMPOWER-CSCC-1: A retrospective cohort study.

[BACKGROUND] The international phase 2 EMPOWER-CSCC-1 study established the programmed cell death protein-1 inhibitor cemiplimab as standard of care for patients with locally advanced or metastatic cutaneous squamous cell carcinoma, however, long-term durability of responses are unknown.

[OBJECTIVE] This study aimed to evaluate outcomes for patients in Australia treated on the EMPOWER-CSCC-1 study, beyond trial protocol follow-up. Outcomes for patients receiving cemiplimab retreatment were evaluated for those who progressed after completing fixed-duration treatment.

[METHODS] A retrospective multicenter analysis was conducted at 5 Australian sites. Primary outcomes were duration of response, progression-free survival (PFS), and overall survival (OS).

[RESULTS] Fifty-four patients (91% men) were identified, median age 71 years. Median follow-up was 77 (interquartile range, 72-86 months) months. Of 39 (72%) responders, 5-year duration of response was 65% (95% confidence interval [CI], 47-78). The median PFS was 56.4 months (95% CI, 19.2-not reached [NR]) and median OS NR (95% CI, 52.8-NR), with 5-year PFS and OS of 48% (95% CI, 34-61) and 60% (95% CI, 45-72), respectively. Four patients received retreatment with cemiplimab, with 3 of these patients remaining progression-free at data cut-off.

[LIMITATIONS] Those inherent to small retrospective analyses.

[CONCLUSIONS] Long-term follow-up confirms durable responses with cemiplimab in patients with advanced cutaneous squamous cell carcinoma in Australia treated on the EMPOWER-CSCC-1 trial.