Vishal A. Patel, MD, FAAD, FACMS, Discusses Cemiplimab’s Recent Approval for Adjuvant Treatment of High-Risk CSCC

In a recent interview with Dermatology Times, Vishal A. Patel, MD, FAAD, FACMS, discussed the FDA's recent approval of cemiplimab-rwlc (Libtayo) as the first adjuvant immunotherapy for adult patients with cutaneous squamous cell carcinoma (CSCC) at high risk of recurrence following surgery and radiation. This approval was supported by the phase 3 C-POST trial, which focused on a particularly high-risk subset of patients.

Patel, associate professor of dermatology at the George Washington School of Medicine & Health Sciences, and the director of the Cutaneous Oncology Program at the GW Cancer Center, emphasized the importance of clearly defining “high-risk” CSCC, noting that criteria vary across specialties. In the context of the C-POST trial, high-risk features were defined using data from prior studies, including a trial by the Tasmanian Radiation Oncology Group. These features include lymph node metastases—especially nodes >20 mm, those with extracapsular extension, or ≥3 involved nodes—as well as deeply invasive primary tumors (T4 by AJCC criteria), perineural invasion with large-caliber nerves or clinical symptoms, and in-transit or recurrent tumors with multiple high-risk features. 

The C-POST trial, a rigorous phase 3, randomized, double-blind, placebo-controlled study, enrolled 415 patients who had undergone surgery and radiation. Patients were then randomized to receive either placebo or cemiplimab, and the results were “exceptionally impressive,” according to Patel. Cemiplimab reduced the risk of recurrence or death by 68%, with a hazard ratio of 0.32—superior to those seen in many melanoma adjuvant trials. Importantly, the trial demonstrated benefit in both local/regional and distant metastasis, with consistent efficacy across subgroups. Regarding safety, cemiplimab was well tolerated. Grade 3 adverse events occurred in under 24% of patients, and treatment discontinuation rates were below 10%, consistent with other cemiplimab studies.

Patel also highlighted the trial’s challenges, including strict eligibility criteria, coordination of surgery, radiation, and systemic therapy, and the added difficulties posed by the COVID-19 pandemic. Despite these hurdles, the trial's successful completion led to a landmark approval—establishing cemiplimab as the first adjuvant immunotherapy option for high-risk CSCC patients post-surgery and radiation.

“I really commend the study team for really being committed to seeing this through, and in the end, it paid off with that really impressive outcome and now has led toward approval,” Patel said.