Libtayo Cuts CSCC Recurrence Risk by 68%, Submits EU, US Applications

Regeneron's Libtayo (cemiplimab) demonstrated a 68% reduction in the risk of disease recurrence or death in high-risk cutaneous squamous cell carcinoma patients after surgery, with 80% and 65% reductions in locoregional and distant recurrence, respectively, compared to placebo. Detailed results were presented at the 2025 ASCO Annual Meeting and published in the New England Journal of Medicine. Regulatory applications have been submitted in the US and EU.

Regeneron Pharmaceuticals, Inc. (NASDAQ: REGN) announced detailed results from the Phase 3 C-POST trial at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting, highlighting the efficacy of its PD-1 inhibitor Libtayo (cemiplimab) in high-risk cutaneous squamous cell carcinoma (CSCC) patients post-surgery. The trial demonstrated a 68% reduction in the risk of disease recurrence or death compared to placebo, with significant reductions in locoregional and distant recurrence rates.

The primary endpoint of the trial, disease-free survival (DFS), showed a 68% reduction in the risk of disease recurrence or death (hazard ratio [HR]: 0.32; 95% confidence interval [CI]: 0.20-0.51; p0.0001). Libtayo-treated patients had a median DFS not reached (versus 49 months for placebo). At two years, DFS was 87% with Libtayo versus 64% with placebo. The trial also demonstrated an 80% reduction in the risk of locoregional recurrence (HR: 0.20; 95% CI: 0.09-0.40) and a 65% reduction in the risk of distant recurrence (HR: 0.35; 95% CI: 0.17-0.72).

Regeneron submitted regulatory applications for Libtayo in the United States and European Union for the treatment of adjuvant CSCC. The trial enrolled 415 patients who were randomized to receive either Libtayo (n=209) or placebo (n=206) for up to 48 weeks. Safety data showed similar adverse event rates between the Libtayo and placebo arms, with the most common AEs including fatigue, pruritus, rash, and diarrhea.

The results of the C-POST trial provide additional insights into the potential of Libtayo in the adjuvant setting for high-risk CSCC, highlighting its potential to become a new standard of care. Regeneron is working with global regulatory authorities to bring this new option to patients as quickly as possible.

References:
[1] https://www.globenewswire.com/news-release/2025/05/31/3091406/0/en/Libtayo-cemiplimab-Phase-3-Data-in-the-Adjuvant-Treatment-of-Post-Surgical-High-Risk-Cutaneous-Squamous-Cell-Carcinoma-CSCC-Have-Potential-to-Be-Practice-Changing.html