A phase 3 trial evaluating cemiplimab, a programmed death receptor-1 (PD-1) blocking antibody, as monotherapy in patients with recurrent or metastatic cervical cancer previously treated with chemotherapy, will be stopped early based on significant overall survival data.

The open-label, randomized, multicenter phase 3 trial (ClinicalTrials.gov: NCT03257267) evaluated the efficacy and safety of cemiplimab in women 18 years of age and older (median age: 51 years) with recurrent or metastatic cervical cancer, including those with either squamous cell carcinoma or adenocarcinoma. Patients were randomly assigned to receive either cemiplimab 350mg intravenously every 3 weeks or an investigator’s choice of chemotherapy (pemetrexed, vinorelbine, topotecan, irinotecan or gemcitabine). 

Findings showed that treatment with cemiplimab was associated with a significant improvement in overall survival (primary end point). In the total population, cemiplimab reduced the risk of death by 31% with a median survival of 12 months compared with 8.5 months for chemotherapy (hazard ratio [HR] 0.69; 95% CI, 0.56-0.84; P <.001). 

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Additionally, treatment with cemiplimab reduced the risk of death by 27% in patients with squamous cell carcinoma, (median survival of 11.1 months vs 8.8 months for chemotherapy [HR 0.73; 95% CI, 0.58-0.91; P =.003]) and by 44% in patients with adenocarcinoma (median survival of 13.2 months vs 7 months for chemotherapy [HR 0.56; 95% CI, 0.36-0.85; P <.005]).

The decision to stop the trial was made based on a recommendation from the study’s independent Data Monitoring Committee (DMC). Detailed study results will be presented at an upcoming medical meeting and submitted to regulatory authorities later this year. There were no new safety signals identified.

“Libtayo monotherapy is the first medicine to demonstrate an improvement in overall survival in women with recurrent or metastatic cervical cancer following progression on platinum-based chemotherapy in a phase 3 trial,” said Krishnansu S. Tewari, MD, Professor and Director of the Division of Gynecologic Oncology at the University of California, Irvine and a trial investigator. “This landmark clinical achievement will bring hope to women with advanced cervical cancer who are often younger than patients with other cancers. This is reflected in this trial where the average age was 51.”

Cemiplimab is marketed under the trade name Libtayo® and is currently indicated for the treatment of metastatic or locally advanced cutaneous squamous cell carcinoma, metastatic or locally advanced basal cell carcinoma, and metastatic or locally advanced non-small cell lung cancer. 


Phase 3 trial of Libtayo® (cemiplimab) monotherapy in advanced cervical cancer stopped early for positive result on overall survival. [press release]. Tarrytown, NY and Paris, France: Regeneron Pharmaceuticals, Inc. and Sanofi; March 15, 2021.

This article originally appeared on MPR