On October 8, 2025 Regeneron Pharmaceuticals, Inc. (NASDAQ: REGN) reported that the U.S. Food and Drug Administration (FDA) has approved the PD-1 inhibitor Libtayo (cemiplimab-rwlc) as an adjuvant treatment for adult patients with cutaneous squamous cell carcinoma (CSCC) at high risk of recurrence after surgery and radiation (Press release, Regeneron, OCT 8, 2025, View Source [SID1234656514]). The FDA evaluated Libtayo under Priority Review, which is reserved for medicines that represent potentially significant improvements in efficacy or safety in the treatment of serious conditions. An additional regulatory application is also under review in the European Union, with a decision expected by the first half of 2026.
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"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 Vishal A. Patel, M.D., Associate Professor of Dermatology and of Medicine (Hematology/Oncology), George Washington University School of Medicine & Health Sciences and Director, Cutaneous Oncology Program, GW Cancer Center. "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, Libtayo represents a practice-changing opportunity for this patient population, backed by compelling data showcasing its ability to significantly improve disease-free survival."
The FDA approval is based on data from the pivotal Phase 3 C-POST trial investigating adjuvant Libtayo versus placebo in patients with CSCC at high risk of recurrence after surgery and radiation. Results from the study, which were published in the New England Journal of Medicine and presented at the American Society of Clinical Oncology (ASCO) (Free ASCO Whitepaper) 2025 Annual Meeting earlier this year, showed that Libtayo demonstrated a 68% reduction in the risk of disease recurrence or death compared to placebo in patients with CSCC at high risk of recurrence after surgery and radiation (hazard ratio [HR]: 0.32; 95% confidence interval [CI]: 0.20-0.51; p<0.0001).
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. The most common adverse reactions as a single agent in adjuvant CSCC at high risk of recurrence (≥10%, with a difference between arms of ≥3% compared to placebo) were rash, pruritus, and hypothyroidism. Serious adverse reactions occurred in 18% of patients and those that occurred in ≥1% of patients in the Libtayo arm were pneumonia (1.5%), rash (1.5%), diarrhea (1.5%), adrenal insufficiency (1%), and arrhythmia (1%).
"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 George D. Yancopoulos, M.D., Ph.D., Board co-Chair, President and Chief Scientific Officer of Regeneron. "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."
"CSCC is one of the most common skin cancers in the world, with an estimated 1.8 million cases diagnosed each year in the U.S. alone. While it can often be treated successfully with surgery and radiation, many patients face serious risk of advanced disease recurrences," said Samantha R. Guild, President, AIM at Skin Cancer Foundation. "This approval is wonderful news for people living with CSCC, and we commend Regeneron for its long-standing commitment to addressing needs in non-melanoma skin cancer through its pioneering research."
Regeneron is committed to helping patients who have been prescribed Libtayo access their medication. The company has launched Libtayo Surround, which offers financial and educational resources to help support patients throughout their treatment journey. For more information, patients can call 1-877-LIBTAYO (1-877-542-8296).
The approved supplemental Biologics License Application (sBLA) did not include Catalent Indiana, LLC as a filling site.
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.
U.S. FDA-approved Indications
Libtayo is a prescription medicine used to treat:
Adults with a type of skin cancer called cutaneous squamous cell carcinoma (CSCC):
that has spread or cannot be cured by surgery or radiation, or
to help prevent CSCC from coming back if your CSCC is at high risk of coming back after it has been removed by surgery and radiation.
Adults with a type of skin cancer called basal cell carcinoma (BCC) when your BCC cannot be removed by surgery (locally advanced BCC) or when it has spread (metastatic BCC) and have received treatment with a hedgehog pathway inhibitor (HHI), or cannot receive treatment with a HHI.
Adults with a type of lung cancer called non-small cell lung cancer (NSCLC).
LIBTAYO may be used in combination with chemotherapy that contains a platinum medicine as your first treatment when your lung cancer has not spread outside your chest (locally advanced lung cancer) and you cannot have surgery or chemotherapy with radiation, or your lung cancer has spread to other areas of your body (metastatic lung cancer), and your tumor does not have an abnormal "EGFR," "ALK," or "ROS1" gene.
LIBTAYO may be used alone as your first treatment when your lung cancer has not spread outside your chest (locally advanced lung cancer) and you cannot have surgery or chemotherapy with radiation, or your lung cancer has spread to other areas of your body (metastatic lung cancer), and your tumor tests positive for high "PD-L1," and your tumor does not have an abnormal "EGFR," "ALK," or "ROS1" gene.
It is not known if Libtayo is safe and effective in children.
IMPORTANT SAFETY INFORMATION FOR U.S. PATIENTS
What is the most important information I should know about LIBTAYO?
LIBTAYO is a medicine that may treat certain cancers by working with your immune system. LIBTAYO can cause your immune system to attack normal organs and tissues in any area of your body and can affect the way they work. These problems can sometimes become severe or life-threatening and can lead to death. You can have more than one of these problems at the same time. These problems may happen anytime during treatment or even after your treatment has ended.
Call or see your healthcare provider right away if you develop any new or worsening signs or symptoms, including:
Lung problems: cough, shortness of breath, or chest pain
Intestinal problems: diarrhea (loose stools) or more frequent bowel movements than usual, stools that are black, tarry, sticky or have blood or mucus, or severe stomach-area (abdomen) pain or tenderness
Liver problems: yellowing of your skin or the whites of your eyes, severe nausea or vomiting, pain on the right side of your stomach-area (abdomen), dark urine (tea colored), or bleeding or bruising more easily than normal
Hormone gland problems: headache that will not go away or unusual headaches, eye sensitivity to light, eye problems, rapid heartbeat, increased sweating, extreme tiredness, weight gain or weight loss, feeling more hungry or thirsty than usual, urinating more often than usual, hair loss, feeling cold, constipation, your voice gets deeper, dizziness or fainting, or changes in mood or behavior, such as decreased sex drive, irritability, or forgetfulness
Kidney problems: decrease in your amount of urine, blood in your urine, swelling of your ankles, or loss of appetite
Skin problems: rash, itching, skin blistering or peeling, painful sores or ulcers in mouth or nose, throat, or genital area, fever or flu-like symptoms, or swollen lymph nodes
Problems can also happen in other organs and tissues. These are not all of the signs and symptoms of immune system problems that can happen with LIBTAYO. Call or see your healthcare provider right away for any new or worsening signs or symptoms, which may include: chest pain, irregular heartbeat, shortness of breath or swelling of ankles, confusion, sleepiness, memory problems, changes in mood or behavior, stiff neck, balance problems, tingling or numbness of the arms or legs, double vision, blurry vision, sensitivity to light, eye pain, changes in eyesight, persistent or severe muscle pain or weakness, muscle cramps, low red blood cells, or bruising
Infusion reactions that can sometimes be severe or life-threatening. Signs and symptoms of infusion reactions may include: nausea, vomiting, chills or shaking, itching or rash, flushing, shortness of breath or wheezing, dizziness, feel like passing out, fever, back or neck pain, or facial swelling
Rejection of a transplanted organ or tissue. Your healthcare provider should tell you what signs and symptoms you should report and monitor you, depending on the type of organ or tissue transplant that you have had
Complications, including graft-versus-host disease (GVHD), in people who have received a bone marrow (stem cell) transplant that uses donor stem cells (allogeneic). These complications can be serious and can lead to death. These complications may happen if you underwent transplantation either before or after being treated with LIBTAYO. Your healthcare provider will monitor you for these complications
Getting medical treatment right away may help keep these problems from becoming more serious. Your healthcare provider will check you for these problems during your treatment with LIBTAYO. Your healthcare provider may treat you with corticosteroid or hormone replacement medicines. Your healthcare provider may also need to delay or completely stop treatment with LIBTAYO if you have severe side effects.
Before you receive LIBTAYO, tell your healthcare provider about all your medical conditions, including if you:
have immune system problems such as Crohn’s disease, ulcerative colitis, or lupus
have received an organ or tissue transplant, including corneal transplant
have received or plan to receive a stem cell transplant that uses donor stem cells (allogeneic)
have received radiation treatment to your chest area
have a condition that affects your nervous system, such as myasthenia gravis or Guillain-Barré syndrome
are pregnant or plan to become pregnant. LIBTAYO can harm your unborn baby
Females who are able to become pregnant:
Your healthcare provider will give you a pregnancy test before you start treatment
You should use an effective method of birth control during your treatment and for at least 4 months after your last dose of LIBTAYO. Talk to your healthcare provider about birth control methods that you can use during this time
Tell your healthcare provider right away if you become pregnant or think you may be pregnant during treatment with LIBTAYO
are breastfeeding or plan to breastfeed. It is not known if LIBTAYO passes into your breast milk. Do not breastfeed during treatment and for at least 4 months after the last dose of LIBTAYO
Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements.
The most common side effects of LIBTAYO when used alone to treat CSCC that has spread or cannot be cured by surgery or radiation, BCC or NSCLC include tiredness, muscle or bone pain, rash, diarrhea, and low levels of red blood cells (anemia).
The most common side effects of LIBTAYO when used alone to help prevent CSCC from coming back include rash and itching.
The most common side effects of LIBTAYO when used in combination with platinum-containing chemotherapy to treat NSCLC include hair loss, muscle or bone pain, nausea, tiredness, numbness, pain, tingling, or burning in your hands or feet, and decreased appetite.
These are not all the possible side effects of LIBTAYO. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088. You may also report side effects to Regeneron Pharmaceuticals at 1-877-542-8296.