FDA Approves Cemiplimab as Adjuvant Treatment for Cutaneous Squamous Cell Carcinoma

The FDA approved cemiplimab-rwlc (Libtayo; Regeneron Pharmaceuticals) for the adjuvant treatment of adults with cutaneous squamous cell carcinoma (CSCC) who are at a high risk of recurrence following surgery and radiation.

In a clinical trial, cemiplimab demonstrated superiority to placebo when treating patients with CSCC.¹

Cemiplimab is a fully human monoclonal antibody that targets the immune checkpoint receptor PD-1 on T cells. By binding to PD-1, cemiplimab has been shown to block cancer cells from using the PD-1 pathway to suppress T-cell activation. Additionally, the agent has been approved by regulatory authorities for use in certain adult patients with advanced basal cell carcinoma, CSCC that is advanced or at high risk of recurrence, advanced non–small cell lung cancer, and advanced cervical cancer.^1,2

“CSCC is one of the most common skin cancers in the world, with an estimated 1.8 million cases diagnosed each year in the US alone. While it can often be treated successfully with surgery and radiation, many patients face serious risk of advanced disease recurrences,” Samantha R. Guild, president of AIM at the Skin Cancer Foundation, said in a news release from Regeneron.²

What Do the Data Show?

The approval of cemiplimab is supported by pivotal data from the randomized, placebo-controlled, double-blind phase 3 clinical trial, C-POST (NCT03969004), which assessed adjuvant cemiplimab compared with placebo following surgery and radiation therapy in 415 patients with high-risk CSCC. The study consisted of a treatment portion and an optional portion in which patients initially receiving placebo have the choice to receive treatment with cemiplimab—upon investigators’ approval of eligibility—if their cancer recurs.^1,3

In the treatment portion of C-POST, patients were randomly assigned to receive either cemiplimab (n = 209; 350 mg) or placebo (n = 206) intravenously over 30 minutes every 3 weeks for 12 weeks, followed by a dose increase (700 mg) every 6 weeks for up to 36 weeks. The primary end point was disease-free survival (DFS), and secondary end points included overall survival (OS), freedom from distant recurrence, and frequency and incidence of adverse events (AEs), among others. Results were published in The New England Journal of Medicine.^3,4

The median follow-up was approximately 24 months. The findings indicated that cemiplimab was superior to placebo regarding DFS (24 vs 65 events; HR for disease recurrence or death, 0.32 [95% CI, 0.20–0.51]; P < .001). The estimated 24-month DFS was approximately 87.1% (95% CI, 80.3–91.6) with cemiplimab and 64.1% (95% CI, 55.9–71.1) with placebo. Additionally, cemiplimab was observed to lead to lower risks of locoregional recurrence (9 vs 40 events; HR, 0.20 [95% CI, 0.09–0.40]) and distant recurrence (10 vs 26 events; HR, 0.35 [95% CI, 0.17–0.72]).⁴

"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,” Vishal A. Patel, MD, associate professor of dermatology and of medicine (hematology/oncology) and director of medicine and health sciences at George Washington University School of Medicine & Health Sciences, and director of the Cutaneous Oncology Program, GW Cancer Center, said in the news release.²

During the trial, AEs of grade 3 or higher occurred in approximately 23.9% of the patients who received cemiplimab and in 14.2% of those who received placebo. Discontinuation because of these AEs occurred in 9.8% and 1.5% of patients, respectively.⁴

“Many patients who undergo surgical resection of their CSCC are later found, on full pathological evaluation, to be at high risk of recurrence. As the first and only immunotherapy approved in the adjuvant setting, [cemiplimab] represents a practice-changing opportunity for this patient population, backed by compelling data showcasing its ability to significantly improve disease-free survival,” Patel said in the news release.²

REFERENCES

1. US Food & Drug Administration. FDA approves cemiplimab-rwlc for adjuvant treatment of cutaneous squamous cell carcinoma. News release. October 8, 2025. Accessed October 8, 2025. https://www.fda.gov/drugs/resources-information-approved-drugs/fda-approves-cemiplimab-rwlc-adjuvant-treatment-cutaneous-squamous-cell-carcinoma?utm_medium=email&utm_source=govdelivery

2. Regeneron. Libtayo® (cemiplimab-rwlc) Approved in the U.S. as First and Only Immunotherapy for Adjuvant Treatment of Cutaneous Squamous Cell Carcinoma (CSCC) with a High Risk of Recurrence After Surgery and Radiation. News release. October 8, 2025. Accessed October 8, 2025. https://investor.regeneron.com/news-releases/news-release-details/libtayor-cemiplimab-rwlc-approved-us-first-and-only

3. Study of Adjuvant Cemiplimab Versus Placebo After Surgery and Radiation Therapy in Patients With High Risk Cutaneous Squamous Cell Carcinoma. ClinicalTrials.gov identifier: NCT03969004. Updated September 19, 2025. Accessed October 8, 2025. https://clinicaltrials.gov/study/NCT03969004

4. Rischin D, Porceddu S, Day F, et al. Adjuvant Cemiplimab or Placebo in High-Risk Cutaneous Squamous-Cell Carcinoma. N Engl J Med. 2025;393(8):774-785. doi:10.1056/NEJMoa2502449