Effectiveness and Toxicity of Cemiplimab Therapy for Advanced Cutaneous Squamous Cell Skin Cancer in a Community Oncology Practice

Background: The immune checkpoint inhibitor cemiplimab has significant clinical activity in unresectable and metastatic cutaneous squamous cell carcinoma. There is limited real-world data available to assess the outcome of cemiplimab treatment in patients in a community practice setting. Methods: We conducted a retrospective analysis of treatment outcomes following cemiplimab treatment (350 mg iv every 3 weeks) of squamous cell skin cancer. An exploratory analysis was performed to evaluate patient subsets, including patients with locally advanced disease, regional or distant metastases, and "too numerous to count" primaries. Another small group of patients who did not respond to the initial 4 doses of cemiplimab were evaluated following added radiotherapy. Results: Of the 36 patients treated, 22 (61.1%) achieved complete remission, 10 (27.8%) experienced a partial response, 3 (8.3%) had stable disease, and 1 (2.8%) developed progressive disease. The median progression-free survival for the entire cohort was over 33 months. Overall, cemiplimab was well-tolerated, with no hospitalizations due to treatment-related toxicity. Discussion: Cemiplimab produced complete remissions in over 60% of patients with locally advanced and metastatic squamous cell skin cancers, allowing elective treatment discontinuation. Addition of radiotherapy in cemiplimab-refractory patients appeared to increase tumor responsiveness. In contrast, patients with TNTC primary tumors frequently developed new primary skin cancers. Thus, improved treatment options for this patient subset are still needed.