Health Canada has issued a Notice of Compliance for Regeneron’s immunotherapy Libtayo as an adjuvant treatment for adults with high-risk cutaneous squamous cell carcinoma, following Phase 3 clinical trial results showing a 68 percent reduction in disease recurrence or death compared to placebo.
Regeneron Canada Company announced that Health Canada has approved Libtayo, known generically as cemiplimab, for a new adjuvant indication targeting adult patients with cutaneous squamous cell carcinoma who face a high risk of recurrence following surgery and radiation. The regulatory milestone makes the PD-1 inhibitor the first and only positive, randomized trial-backed adjuvant treatment option authorized for this specific form of skin cancer in Canada.
Clinical Evidence From the C-POST Trial
The Health Canada authorization rests on findings from the international, phase 3 C-POST trial, which enrolled 415 patients. Participants were assigned to receive either cemiplimab (n=209) or a placebo (n=206). After a median follow-up of 24 months, the efficacy data revealed a pronounced reduction in recurrence and mortality risks.
“The approval of this new indication for cemiplimab demonstrates continued advancement in the management of high-risk CSCC in Canada as the first and only positive, randomized trial evaluating adjuvant treatment for this disease. The highly significant and clinically meaningful hazard ratio of 0.32 offers clinicians a new option to address the needs of patients,”
Dr. Marcus Butler, Melanoma/Skin Oncology Site Lead, Princess Margaret Cancer Centre
The trial tracked disease-free survival as its primary endpoint, alongside secondary measures that included freedom from locoregional recurrence, freedom from distant recurrence, and safety assessments. Investigators reported a 68% reduction in the risk of disease recurrence or death, registering 24 events in the cemiplimab arm against 65 events in the placebo arm, with a hazard ratio of 0.32.
Safety Profile and Adverse Events in Adjuvant Care
Adverse events observed during the adjuvant trial matched the established safety profile of cemiplimab monotherapy in advanced malignancies.
Understanding High-Risk Cutaneous Squamous Cell Carcinoma
Cutaneous squamous cell carcinoma represents the second most common form of skin cancer, originating in the squamous cells that make up the outer layers of the skin known as the epidermis. Most cases develop on areas exposed to ultraviolet radiation, such as the face, neck, and backs of the hands. While surgical intervention and radiation therapy successfully treat the majority of cases, specific tumors are classified as high-risk due to features like nerve or bone involvement, lymph node status, or prior surgical site recurrence.
Libtayo operates as a fully human monoclonal antibody designed to target the immune checkpoint receptor PD-1 on T cells. By binding to this receptor, the therapy blocks cancer cells from utilizing the PD-1 pathway to suppress T-cell activation, thereby allowing the immune system to recognize and attack malignant cells.
Broader Regulatory Landscape and Global Approvals
The Canadian decision mirrors a similar regulatory milestone in the United States, where the U.S. Food and Drug Administration approved Libtayo for the same adjuvant indication. The FDA approval, granted under Priority Review, was likewise anchored in the C-POST trial data published in the New England Journal of Medicine.
Beyond high-risk CSCC, the drug maintains a growing therapeutic footprint across multiple oncology indications in Canada. Current authorizations cover advanced cutaneous squamous cell carcinoma, locally advanced basal cell carcinoma previously treated with a hedgehog pathway inhibitor, non-small cell lung cancer both as a monotherapy and in combination with platinum-based chemotherapy, and recurrent or metastatic cervical cancer.
What Lies Ahead for European Regulators
As health authorities in North America establish adjuvant cemiplimab as a standard clinical option for high-risk surgical patients, European regulators are reviewing parallel applications. An additional regulatory submission is under review in the European Union, with a formal decision anticipated by mid-2026.
