FDA Approves Libtayo as First Adjuvant Immunotherapy for High-Risk CS Cell Carcinoma

The U.S. Food and Drug Administration (FDA) has approved the PD-1 inhibitor Libtayo® (cemiplimab-rwlc) as the first and only immunotherapy for the adjuvant treatment of cutaneous squamous cell carcinoma (CSCC) at high risk of recurrence after surgery and radiation. The approval is based on results from the Phase 3 C-POST trial, in which Libtayo reduced the risk of disease recurrence or death by 68% compared with placebo.

A New Option for High-Risk CSCC

While most cases of CSCC can be successfully treated with surgery and radiation, a subset of patients face a substantial risk of relapse—often with poor outcomes. Until now, there has been no approved systemic therapy to prevent recurrence in these patients.

"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 Dr. Vishal A. Patel, Associate Professor of Dermatology and Medicine at George Washington University. “As the first and only immunotherapy approved in the adjuvant setting, Libtayo represents a practice-changing opportunity for this patient.”

The C-POST trial (NCT03969004) enrolled 415 patients with CSCC at high risk of recurrence after completing surgery and radiation. Participants were randomized to receive Libtayo or placebo. Median disease-free survival (DFS) was not reached in the Libtayo arm, compared with 49.4 months in the placebo arm, underscoring a durable benefit.

Safety Data

The safety profile of Libtayo in this setting was consistent with prior experience in advanced cancers. The most common adverse reactions (≥10%, and ≥3% more frequent than placebo) included rash, pruritus, and hypothyroidism. Serious adverse events occurred in 18% of patients; the most frequent (≥1%) were pneumonia, rash, diarrhea, adrenal insufficiency, and arrhythmia. The prescribing information also includes standard warnings for immune-mediated reactions and infusion-related events.

Expanding the Role of PD-1 Blockade

“This approval provides patients with CSCC at high risk of disease recurrence following surgery and radiation a much-needed option, as Libtayo is the only immunotherapy to demonstrate efficacy in this setting,” said Dr. George D. Yancopoulos, Regeneron’s President and Chief Scientific Officer. “Now with five FDA-approved indications, Libtayo is firmly established as a strong and versatile PD-1 inhibitor option for patients with a variety of cancers.”

About Libtayo

Libtayo is a fully human monoclonal antibody targeting the PD-1 receptor on T cells, developed using Regeneron’s VelocImmune® technology. By blocking PD-1, the therapy restores T-cell activity against cancer cells. It is approved in more than 30 countries for various malignancies, including advanced CSCC, basal cell carcinoma, non-small cell lung cancer, and cervical cancer.

With this latest indication, Libtayo moves from treating advanced disease to preventing recurrence in earlier-stage patients—a milestone that could redefine the standard of care in CSCC. Regulatory review is also underway in the European Union, with a decision expected in the first half of 2026.