Immunotherapy Approved for High-Risk Cutaneous Squamous Cell Carcinoma
The Food and Drug Administration (FDA) approved cemiplimab-rwlc (Libtayo, Regeneron Pharmaceuticals Inc.) on October 8, 2025, for adults with cutaneous squamous cell carcinoma (CSCC) at high risk of the cancer returning after surgery and radiation treatment. This marks the first immunotherapy approved for use following these initial treatments, offering a new option for patients who previously had limited choices.
The approval was based on data from the C-POST trial (NCT03969004), a randomized, double-blind, placebo-controlled study involving 415 patients. Participants had already undergone surgery and radiation and were at significant risk of recurrence. The trial demonstrated a substantial reduction in the risk of disease recurrence or death with cemiplimab-rwlc compared to placebo, with a hazard ratio of 0.32 (95% confidence interval: 0.20, 0.51; p-value <0.0001). Median disease-free survival was not reached in the cemiplimab-rwlc arm, even as it was 49.4 months in the placebo arm.
Patients in the study were required to complete radiation therapy within two to ten weeks of beginning the trial. Individuals with autoimmune diseases requiring immunosuppressants, a history of organ transplant, certain viral infections (HIV, hepatitis B or C), or a compromised performance status were excluded from participation.
The recommended dosage of Libtayo is 350 mg administered intravenously every three weeks for the first 12 weeks, followed by 700 mg every six weeks, or 350 mg every three weeks, continuing until the disease returns or unacceptable side effects occur, or for up to 48 weeks.
The FDA evaluated Libtayo under Priority Review, a designation reserved for medications that offer significant improvements in treating serious conditions. According to Regeneron, a regulatory application is similarly under review in the European Union, with a decision anticipated in the first half of 2026.
The prescribing information for Libtayo includes warnings and precautions related to immune-mediated adverse reactions, infusion-related reactions, potential complications for those who have received stem cell transplants and risks to developing fetuses. This approval represents a potential shift in the treatment paradigm for CSCC, extending the benefits of immunotherapy to patients in an earlier stage of the disease, as noted in Pharmiweb.
“Patients whose CSCC is at a high risk of recurrence following surgery and radiation often have the poorest outcomes. Until now, we lacked options to help prevent a devastating recurrence and immunotherapy was only available for patients with advanced CSCC who were no longer candidates for curative surgery or curative radiation,” said Vishal A. Patel, M.D., Associate Professor of Dermatology and of Medicine (Hematology/Oncology), George Washington University School of Medicine & Health Sciences and Director, Cutaneous Oncology Program, GW Cancer Center.
Further information about Libtayo, including complete prescribing details, will be available on Drugs@FDA. The findings from the C-POST trial could influence future treatment guidelines and improve outcomes for individuals facing a high risk of CSCC recurrence.
