Overview of Libtayo, First New FDA-Approved Drug for Metastatic Cutaneous Squamous Cell Carcinoma (CSCC)
CancerCancer Treatment

Overview of Libtayo, First FDA-Approved Drug for Metastatic Cutaneous Squamous Cell Carcinoma (CSCC) When Surgery or Radiation Isn’t an Option

Overview of Libtayo, First FDA-Approved Drug for Metastatic Cutaneous Squamous Cell Carcinoma (CSCC) When Surgery or Radiation Isn’t an Option
Photo Courtesy of Sanofi
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Updated on January 29, 2026
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Cemiplimab (Libtayo) is a type of immunotherapy drug that treats cutaneous squamous cell carcinoma (CSCC), a type of skin cancer. It is considered a first-line treatment for CSCC in people who are not a candidate for surgery and radiation.

Libtayo belongs to a class of drugs called immune checkpoint inhibitors, which help the immune system fight cancer. It is the first drug approved by the U.S. Food and Drug Administration (FDA) to treat cutaneous squamous cell carcinoma.

How Does Libtayo Work?

Libtayo and other immune checkpoint inhibitors are types of monoclonal antibodies. They work by blocking checkpoint proteins, which act like switches to turn your immune response on or off.

PD-1 is a type of checkpoint protein found on your immune cells. It attaches to proteins called PD-L1 proteins on normal cells, telling your body to avoid them.

Some cancer cells can also have PD-L1 proteins, which allows them to avoid being attacked by your immune system. Libtayo and other PD-1 inhibitors can block PD-1 from binding, boosting your immune response against cancer cells.

Other types of PD-1 inhibitors include nivolumab (Opdivo and Opdivo Qvantig) and pembrolizumab (Keytruda and Keytruda Qlex). Drugs that target PD-L1 include atezolizumab (Tecentriq and Tecentriq Hybreza), avelumab (Bavencio), and durvalumab (Imfinzi).

What Are the Possible Side Effects of Libtayo?

Because immune checkpoint inhibitors affect the way your immune system functions, they can cause immune-related side effects, also called immune-related adverse events.

Common side effects of Libtayo include:

  • Cough
  • Diarrhea
  • Mild fever or chills
  • Hoarseness
  • Lower back or side pain
  • Painful urination
  • Skin rash or itching
More serious side effects are less common, but can include:

  • Feeling dizzy or lightheaded
  • Trouble breathing
  • High fever
  • Nausea or vomiting
  • Extreme fatigue

Contact your doctor right away if you experience any serious side effects while receiving Libtayo or other immunotherapy drugs.

What Are the Potential Risks of Libtayo?

Libtayo and other immune checkpoint inhibitor drugs remove one of the safeguards on your immune system. While rare, this can cause widespread inflammation, which may be serious and potentially life-threatening.

 Depending on which organs are affected, this can lead to:

  • Liver inflammation
  • Ulcerative colitis (bowel inflammation)
  • Kidney inflammation and impaired kidney function
  • Inflammation of hormone-producing glands (adrenal, pituitary, and thyroid)
  • Changes in blood sugar levels due to inflammation in the pancreas
  • Serious skin reactions
  • Inflammation of the lungs
Contact your doctor or care team immediately if you experience any of the following symptoms.

  • Trouble breathing
  • Stomach pain or tenderness
  • Bloody stool
  • Bloody or cloudy urine
  • Unusual tiredness or weakness
  • Swelling of the face, feet, or lower legs
  • Blistering, peeling, or loosening of the skin
  • Unusual weight gain
The following factors may increase your risk of serious side effects while taking Libtayo.

Libtayo can potentially harm a fetus. Talk with your doctor if you are pregnant or may be pregnant before taking Libtayo. Also, there are currently no adequate studies on the risks for infants if you're taking Libtayo while breastfeeding.

The Takeaway

  • Libtayo is the first immunotherapy drug approved by the FDA specifically for treating cutaneous squamous cell carcinoma (CSCC) when surgery or radiation aren't options. It is a type of immune checkpoint inhibitor, which enhances the immune response against cancer cells.
  • Because Libtayo affects your immune system, it can cause immune-related side effects, such as cough, diarrhea, painful urination, and skin rash or itching.
  • In rare cases, Libtayo can lead to life-threatening inflammation. Contact your doctor immediately if you experience severe side effects, such as trouble breathing, bloody stool or urine, extreme fatigue, or blistering or peeling of the skin.
  • Factors that can increase the risk of serious side effects from Libtayo include complementary therapies or medications, vaccines, existing health conditions, alcohol and tobacco use, and pregnancy.

Resources We Trust

EDITORIAL SOURCES
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
Resources
  1. LIBTAYO (cemiplimab-rwlc). Regeneron Pharmaceuticals.
  2. Squamous Cell Carcinoma. Cleveland Clinic. April 15, 2022.
  3. Immune Checkpoint Inhibitors and Their Side Effects. American Cancer Society. October 9, 2025.
  4. Cemiplimab-rwlc (intravenous route). Mayo Clinic. August 1, 2025.
  5. Immune Checkpoint Inhibitors. National Cancer Institute. April 7, 2022.
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Tingting Tan, MD, PhD

Medical Reviewer

Tingting Tan, MD, PhD, is a medical oncologist at City of Hope National Medical Center.

Dr. Tan's research has been published in multiple medical and scientific journals, including Oncologists, Cancer Cell, and Genes and Development.

A graduate of the Beijing Medical University, Tan holds an M.D. from Peking University Health Science Center and a Ph.D. from Rutgers University. Her training includes fellowships at the University of California San Francisco Cancer Research Institute and the Fox Chase Cancer Center at Temple University.

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Susan K. Treiman

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Susan (Sue) Treiman is an award-winning newspaper reporter, television producer, website executive, and corporate communications expert. She is passionate about writing on health, medicine, and wellness. She has been published in every New York City newspaper, produced television programs for ABC News, CBS News, and Paramount Pictures, headed up the editorial work on ABC's original flagship website, ABC.com, and launched the network's first children's website.

More recently, Treiman has served as the in-house journalist for several international management consulting firms. At Everyday Health, she has written about women's health, stress, sleep medicine, and psychology, and has written for various other publications, including Linkwell Health and In the Groove.

Treiman is based in New York, and is an abstract artist who enjoys painting in her free time.
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