Libtayo Shows Promise for Patients with Advanced Cervical Cancer


Together, biopharmaceutical company Sanofi and biotechnology company Regeneron Pharmaceuticals, Inc. (“Regeneron”) have been working to develop Libtayo (cemiplimab) for patients with advanced cervical cancer. According to a press release, the companies decided to stop a Phase 3 clinical trial evaluating the drug. However, this is actually positive news! Libtayo showed so much promise as a monotherapy in improving overall survival (OS) rates over chemotherapy (pemetrexed, vinorelbine, topotecan, irinotecan or gemcitabine) that the Independent Data Monitoring Committee (IDMC) believed enough data had already been found showing the drug’s efficaciousness. Considering cervical cancer’s notorious treatment difficulties, Libtayo shows promise for fulfilling an unmet need.


During the Phase 3 clinical trial, researchers evaluated Libtayo, as compared to chemotherapy, in patients with recurrent or metastatic cervical cancer. Patients could enroll despite PD-L1 expression status. Altogether, 78% had squamous cell carcinoma (SCC) and 22% had adenocarcinoma. The mean patient age was 51. Patients received either chemotherapy or 350mg Libtayo every three weeks. 300 patients received Libtayo, while 290 received chemotherapy.

Libtayo is a fully-human monoclonal antibody which targets and binds to PD-1, an immune checkpoint receptor. According to the American Cancer Society:

Monoclonal antibodies are man-made proteins that act like human antibodies in the immune system.

In this case, Libtayo prevents cancer cells from stopping T-cells (a type of immune cell) from activating. The drug was developed using Regeneron’s proprietary VelocImmune technology. The company describes VelocImmune as:

[creating] a multitude of optimized antibody drug candidates efficiently and directly from immunized mice. This approach overcomes the limitations of traditional platforms by rapidly creating fully human antibodies that tightly bind to therapeutic targets and avoid potential immune responses that may occur in patients receiving antibodies that contain nonhuman (typically mouse) components.

Outside of cervical cancer, Libtayo is indicated for the treatment of non-small cell lung cancer (NSCLC), basal cell carcinoma (BCC), and cutaneous squamous cell carcinoma (CSCC). Libtayo is not approved for use in children.

Cervical Cancer Clinical Trial

During the trial, researchers discovered the following:

  • Libtayo, as opposed to chemotherapy, reduced the overall risk of death by 31%.
  • As compared to chemotherapy, Libtayo reduced the overall death risk by 27% in patients with SCC.
  • In patients with adenocarcinoma, Libtayo was especially effective. The drug reduced the overall death risk by 44%.
  • Libtayo was relatively safe and well-tolerated. However, some adverse reactions did occur. These were higher in the chemotherapy group than the Libtayo group. These included:
    • Anemia (low red blood cell count)
    • Nausea and vomiting
    • Constipation
  • Some adverse reactions did occur more in the Libtayo group. These included:
    • Fatigue
    • Urinary tract infections (UTIs)
    • Back and joint pain

Safety Information

If you are taking Libtayo and experience any of the following symptoms, please see your doctor immediately:

  • Bloody urine or stool
  • Appetite loss
  • Changes in the amount of urine produced
  • Swelling of the ankles
  • Cough, shortness of breath
  • Jaundice (yellowing of the skin and eyes)
  • Severe nausea, vomiting, and diarrhea
  • Abdominal, chest, bone, or joint pain
  • Easy bruising and bleeding
  • Severe headache and light sensitivity
  • Unintended weight gain or weight loss
  • Rash
  • Confusion or changes in mood/behavior

Cervical Cancer

According to the American Cancer Institute, cervical cancer is a type of cancer which forms:

in the cells lining the cervix — the lower part of the uterus (womb). The cervix connects the body of the uterus (the upper part where a fetus grows) to the vagina (birth canal).

Nearly all cervical cancer diagnoses are caused by human papillomavirus (HPV) infection. Additionally, smoking and HIV infection increase the risk. Largely, most diagnoses are SCC while the rest are adenocarcinomas. All females are at risk of developing cervical cancer. However, it more frequently occurs over age 30 and before age 45. Gynecological screening can help with early diagnosis and treatment. Symptoms of cervical cancer include:

  • Pelvic pain
  • Pain or bleeding during intercourse
  • Vaginal bleeding after menopause or outside of the menstrual cycle
  • Watery and bloody vaginal discharge
    • Note: This discharge may be heavy/thick and have a foul smell.

Learn more about cervical cancer here.

Jessica Lynn

Jessica Lynn

Jessica Lynn has an educational background in writing and marketing. She firmly believes in the power of writing in amplifying voices, and looks forward to doing so for the rare disease community.

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