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Approval based on results of landmark Phase 3 C-POST trial that show Libtayo is first immunotherapy to significantly improve disease-free survival in CSCC in the adjuvant setting, reducing the risk of recurrence or death by 68% (hazard ratio: 0.32; 95% confidence interval: 0.20-0.51; p<0.0001)
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Libtayo is the current standard of care in advanced CSCC in Europe, and this approval has the potential to change the treatment paradigm for patients in an earlier setting
TARRYTOWN, N.Y., Nov. 19, 2025 (GLOBE NEWSWIRE) -- Regeneron Pharmaceuticals, Inc. (NASDAQ: REGN) today announced that the European Commission (EC) has approved the PD-1 inhibitor Libtayo® (cemiplimab) as an adjuvant treatment for adult patients with cutaneous squamous cell carcinoma (CSCC) at high risk of recurrence after surgery and radiation. This expands the existing European Union (EU) indication for Libtayo in advanced CSCC to include patients at high risk of disease recurrence. Libtayo was also recently approved by the U.S. Food and Drug Administration (FDA) in October for the same indication.
“While CSCC can often be treated successfully with surgery and radiation, some patients face the persistent threat of disease recurrence and potentially fatal outcomes. This highlights a critical need for earlier intervention, but immunotherapy has until now been reserved just for advanced cases,” said Paolo Bossi, M.D., Head of the Head and Neck Medical Oncology Unit and Associate Professor of Medical Oncology, Humanitas University and Humanitas Cancer Center, Milan, Italy. “As the only immunotherapy shown to improve disease-free survival in this setting, Libtayo could change the outlook for these earlier-stage patients in need.”
The approval is supported by data from the global Phase 3 C-POST trial, which evaluated adjuvant Libtayo versus placebo in patients with CSCC at high risk of recurrence following surgery and radiation. Libtayo demonstrated a 68% reduction in the risk of disease recurrence or death compared to placebo (hazard ratio: 0.32; 95% confidence interval: 0.20-0.51; p<0.0001). Detailed data were published in the New England Journal of Medicine (NEJM) in May 2025.
The safety profile of Libtayo as adjuvant treatment of patients with CSCC at high risk of recurrence after surgery and radiation is consistent with the known safety profile for Libtayo monotherapy in advanced cancers. In the trial, grade ≥3 adverse events (AEs) occurred in 24% of patients receiving Libtayo and 14% receiving placebo. The most common AEs occurring in at least 10% of patients who received Libtayo were fatigue, pruritus, rash, diarrhea, arthralgia, hypothyroidism and maculo-papular rash. AEs led to permanent discontinuation of treatment in 10% of patients who received Libtayo and 2% of patients who received placebo. Two patients in each arm experienced an AE leading to death.
“CSCC is one of the fastest-growing forms of skin cancer, and the approval of Libtayo by the European Commission reflects a meaningful shift in how this disease could be treated in the adjuvant setting,” said George D. Yancopoulos, M.D., Ph.D., Board co-Chair, President and Chief Scientific Officer of Regeneron. “Building on our existing indication in advanced CSCC, this is the sixth approval for Libtayo in the European Union and underscores our commitment to delivering innovative treatments across cancers where patients continue to face some of the greatest gaps in care.”
CSCC is a type of non-melanoma skin cancer (NMSC), and one of the most common cancers in the world. In the EU, the incidence of NMSC overall is expected to increase by 40% in the coming decades. CSCC can often be treated successfully with surgery, but many patients may have a “high risk” form and face an increased risk of recurrence.
Libtayo is also currently approved in the EU for the treatment of certain patients with advanced CSCC, advanced basal cell carcinoma (BCC), advanced non-small cell lung cancer (NSCLC) and recurrent or metastatic cervical cancer.
About the Phase 3 Trial
C-POST was a randomized, placebo-controlled, double-blind, multicenter, global Phase 3 trial investigating Libtayo versus placebo as adjuvant treatment for patients with features associated with a high risk of CSCC recurrence and who had completed surgery and post-operative radiation therapy. Trial participants were at high risk of recurrence due to nodal features (extracapsular extension or ≥3 involved lymph nodes) and/or non-nodal features (in-transit metastases, T4 lesion, perineural invasion, or locally recurrent tumor with ≥1 additional poor prognostic features).
The trial enrolled 415 patients who were randomized to receive either Libtayo (n=209) or placebo (n=206) for up to 48 weeks. For the first 12 weeks, Libtayo 350 mg or placebo was administered intravenously every three weeks, followed by Libtayo 700 mg or placebo administered intravenously every six weeks for 36 weeks.
About Regeneron in Cancer
We aspire to turn revolutionary discoveries into medicines that can transform the lives of those impacted by cancer. Our team around the world is driven to solve the needs and challenges of those affected by one of the most serious diseases of our time.
Backed by our legacy of scientific innovation and a deep understanding of biology, genetics and the immune system, we’re pursuing potential therapies across more than 30 types of solid tumors and blood cancers. Our cancer strategy is powered by cutting-edge technologies and therapies that can be flexibly combined to investigate potentially transformative treatments for patients. Oncology assets in clinical development comprise nearly half of Regeneron’s pipeline, and include checkpoint inhibitors, bispecific antibodies and costimulatory bispecific antibodies. Our approved PD-1 inhibitor Libtayo serves as the backbone of many of our investigational combinations.
To complement our extensive in-house capabilities, we collaborate with patients, healthcare providers, governments, biopharma companies and each other to further our shared goals. Together, we are united in the mission to serve as a beacon of transformation in cancer care.
About Libtayo
Libtayo is a fully human monoclonal antibody targeting the immune checkpoint receptor PD-1 on T cells and was invented using Regeneron's proprietary VelocImmune® technology. By binding to PD-1, Libtayo has been shown to block cancer cells from using the PD-1 pathway to suppress T-cell activation. Libtayo has been approved by regulatory authorities in more than 30 countries in one or more indications, including for certain adult patients with advanced basal cell carcinoma (BCC), CSCC that is advanced or at high risk of recurrence, advanced non-small cell lung cancer (NSCLC) and advanced cervical cancer.
In the U.S., the generic name for Libtayo in its approved indications is cemiplimab-rwlc, with rwlc as the suffix designated in accordance with Nonproprietary Naming of Biological Products Guidance for Industry issued by the U.S. FDA. Outside of the U.S., the generic name of Libtayo in its approved indications is cemiplimab.
The extensive clinical program for Libtayo is focused on difficult-to-treat cancers. Libtayo is currently being investigated in trials as a monotherapy, as well as in combination with either conventional or novel therapeutic approaches for other solid tumors and blood cancers. These potential uses are investigational, and their safety and efficacy have not been evaluated by any regulatory authority.
About Regeneron's VelocImmune Technology
Regeneron's VelocImmune technology utilizes a proprietary genetically engineered mouse platform endowed with a genetically humanized immune system to produce optimized fully human antibodies. When Regeneron's co-Founder, President and Chief Scientific Officer George D. Yancopoulos was a graduate student with his mentor Frederick W. Alt in 1985, they were the first to envision making such a genetically humanized mouse, and Regeneron has spent decades inventing and developing VelocImmune and related VelociSuite® technologies. Dr. Yancopoulos and his team have used VelocImmune technology to create a substantial proportion of all original, FDA-approved or authorized fully human monoclonal antibodies. This includes Dupixent® (dupilumab), Libtayo, Praluent® (alirocumab), Kevzara® (sarilumab), Evkeeza® (evinacumab-dgnb), Inmazeb® (atoltivimab, maftivimab and odesivimab-ebgn) and Veopoz® (pozelimab-bbfg). In addition, REGEN-COV® (casirivimab and imdevimab) had been authorized by the FDA during the COVID-19 pandemic until 2024.
About Regeneron
Regeneron (NASDAQ: REGN) is a leading biotechnology company that invents, develops and commercializes life-transforming medicines for people with serious diseases. Founded and led by physician-scientists, our unique ability to repeatedly and consistently translate science into medicine has led to numerous approved treatments and product candidates in development, most of which were homegrown in our laboratories. Our medicines and pipeline are designed to help patients with eye diseases, allergic and inflammatory diseases, cancer, cardiovascular and metabolic diseases, neurological diseases, hematologic conditions, infectious diseases, and rare diseases.
Regeneron pushes the boundaries of scientific discovery and accelerates drug development using our proprietary technologies, such as VelociSuite®, which produces optimized fully human antibodies and new classes of bispecific antibodies. We are shaping the next frontier of medicine with data-powered insights from the Regeneron Genetics Center® and pioneering genetic medicine platforms, enabling us to identify innovative targets and complementary approaches to potentially treat or cure diseases.