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Soo Park, MD
Soo Park, MD
Posted: Tuesday, July 14, 2026
Historically, patients with T3-4/N+/M0 unresectable cutaneous squamous cell carcinoma (CSCC) have been treated with definitive radiotherapy with or without chemotherapy, but outcomes have remained poor. A response-adapted treatment strategy combining cemiplimab-rwlc with definitive radiotherapy produced encouraging survival outcomes in patients with locally advanced unresectable CSCC, according to results from the phase II RAMPART trial presented at the 2026 ASCO Annual Meeting. Christopher A. Barker, MD, of Memorial Sloan Kettering Cancer Center, and colleagues reported that the multicenter study met its primary endpoint, with an estimated 18-month event-free survival rate of 86%—substantially exceeding the historical benchmark of approximately 38% for radiotherapy alone.
The single-arm, multicenter phase II trial enrolled 34 patients with locally advanced unresectable CSCC between 2022 and 2024. Eligible patients had T3-4/N+/M0 disease by multidisciplinary consensus and an Eastern Cooperative Oncology Group performance status of ≤ 2. Participants initially received two doses of cemiplimab at 350 mg every 3 weeks. Patients who experienced disease progressed after two doses proceeded directly to definitive radiotherapy at 70 Gy in 35 fractions; those without progression received two additional doses of cemiplimab before undergoing response-adapted radiotherapy (50–70 Gy in 25–35 fractions) with concurrent cemiplimab, followed by adjuvant cemiplimab for up to 1 year. The primary endpoint was 18-month event-free survival, with secondary endpoints including safety, response, progression-free survival, overall survival, and quality of life.
The median patient age was 77 years, and 82% were men. A total of 41% had stage III disease, whereas 59% had stage IV/M0 disease. Treatment adherence was high, with 85% completing all four planned neoadjuvant doses of cemiplimab and 94% completing radiotherapy as planned.
After a median follow-up of 18 months (range = 2–36 months), the estimated 18-month event-free survival was 86% (one-sided 95% confidence interval lower bound = 73%). Estimated 18-month progression-free survival was also 86%, and estimated overall survival reached 92%. Adverse events were consistent with the known safety profiles of cemiplimab and radiotherapy, and quality-of-life analyses remain ongoing.
The investigators reported, “The study met its primary endpoint demonstrating the highest rate of event-free survival, progression-free survival, and overall survival after treatment of [locally advanced unresectable] CSCC ever reported.” They further concluded that, “As the largest prospective study of definitive radiotherapy for [locally advanced unresectable] CSCC, the data suggest integrating cemiplimab with radiotherapy may benefit appropriate patients. Future studies identifying patients who are best served with this approach are warranted.”
DISCLOSURE: For full disclosures of the study authors, visit coi.asco.org.
2026 ASCO Annual Meeting (Abstract 9506)
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