Libtayo Monotherapy Trial in Advanced Cervical Cancer Stopped Early for OS Positive Result

Regeneron Pharmaceuticals and Sanofi announced positive results demonstrating an overall survival (OS) benefit from the Phase 3 trial investigating the PD-1 inhibitor Libtayo® (cemiplimab) monotherapy compared to chemotherapy, in patients previously treated with chemotherapy whose cervical cancer is recurrent or metastatic. The trial will be stopped early based on a unanimous recommendation by the Independent Data Monitoring Committee (IDMC), and the data will form the basis of regulatory submissions in 2021.

"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, M.D., 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."

This is the largest Phase 3 randomized clinical trial in advanced cervical cancer, and included women (median age: 51 years) with either squamous cell carcinoma or adenocarcinoma. Patients were randomized to receive Libtayo monotherapy (350 mg every 3 weeks) or an investigator's choice of commonly used chemotherapy (pemetrexed, vinorelbine, topotecan, irinotecan or gemcitabine).

The primary endpoint for the trial was OS, analyzed first among patients with squamous cell carcinoma, then in the total population. Per a protocol-specified interim analysis, the IDMC reviewed OS data when approximately 85% of events had occurred among patients with squamous cell carcinoma. Based on the highly significant effect on OS among these patients, the IDMC recommended stopping the trial. Detailed results will be presented at an upcoming medical meeting. The use of Libtayo in cervical cancer is investigational and has not been fully reviewed by any regulatory authority.

No new Libtayo safety signals were observed. Safety was assessed in patients who received at least 1 dose of study treatment: 300 patients in the Libtayo group (median duration of exposure: 15 weeks; range: 1-101 weeks) and 290 patients in the chemotherapy group (median duration of exposure: 10 weeks; range: 1-82 weeks). Adverse events (AEs) were observed in 88% of Libtayo patients and 91% of chemotherapy patients, with serious AEs occurring in 30% of Libtayo patients and 27% of chemotherapy patients. The 5 most common AEs were anemia (25% Libtayo, 45% chemotherapy), nausea (18% Libtayo, 33% chemotherapy), fatigue (17% Libtayo, 16% chemotherapy), vomiting (16% Libtayo, 23% chemotherapy) and constipation (15% Libtayo, 20% chemotherapy). Other AEs that occurred more often in the Libtayo group and in at least 10% of patients were fatigue (17% Libtayo, 16% chemotherapy), urinary tract infections (12% Libtayo, 9% chemotherapy), back pain (11% Libtayo, 9% chemotherapy) and arthralgia (10% Libtayo, 3% chemotherapy). Discontinuations due to AEs occurred in 8% of Libtayo patients and 5% of chemotherapy patients.

"Recurrent or metastatic cervical cancer is notoriously difficult to treat and has no approved standard of care after first-line chemotherapy," said Israel Lowy, M.D., Ph.D., Senior Vice President, Translational and Clinical Sciences, Oncology, at Regeneron. "This trial, which enrolled patients regardless of their PD-L1 status, demonstrated that Libtayo helped patients with recurrent or metastatic cervical cancer live longer after progression on prior chemotherapy. This is the fourth patient population in which Libtayo has shown clinical benefit and we look forward to submitting the results to regulatory authorities later this year."

"We are committed to developing therapies for cancers with high unmet needs including patients with advanced cervical cancer," said Peter C. Adamson, M.D., Global Development Head, Oncology and Pediatric Innovation at Sanofi. "Combined with data from our non-melanoma skin cancer and lung cancer studies, these data contribute to the growing evidence demonstrating the significant potential of Libtayo to treat a spectrum of difficult-to-treat cancers."

This open-label, randomized, multi-center, Phase 3 trial investigated Libtayo monotherapy versus an investigator's choice of chemotherapy in patients with recurrent or metastatic cervical cancer that has progressed on platinum-based chemotherapy. Patients were allowed to enroll regardless of PD-L1 expression status with 78% of patients having squamous cell carcinoma and 22% having adenocarcinoma. The trial included women from 14 countries: the U.S., Japan, Taiwan, China Region of China, South Korea, Canada, Russia, Poland, Spain, Brazil, Australia, the UK, Italy, Greece and Belgium.

Cervical cancer is the fourth leading cause of cancer death in women worldwide and is most frequently diagnosed in women between the ages of 35 and 44. Almost all cases are caused by human papillomavirus (HPV) infection, with approximately 80% classified as squamous cell carcinoma (arising from cells lining the bottom of the cervix) and the remainder largely adenocarcinomas (arising from glandular cells in the upper cervix). Cervical cancer is often curable when detected early and effectively managed, but treatment options are more limited in advanced stages.

It is estimated that there are approximately 570,000 women diagnosed with cervical cancer worldwide each year. In the U.S. there are 14,500 new patients diagnosed annually and approximately 4,000 women die each year.

Libtayo is a fully-human monoclonal antibody targeting the immune checkpoint receptor PD-1 on T-cells. By binding to PD-1, Libtayo has been shown to block cancer cells from using the PD-1 pathway to suppress T-cell activation.

In the U.S., Libtayo is approved for certain patients with advanced stages of CSCC, BCC and NSCLC with ≥50% PD-L1 expression. Outside of the U.S., Libtayo is approved for certain patients with advanced CSCC in the European Union and six other countries, including Australia, Brazil, the United Kingdom and Canada.

The generic name for Libtayo in its approved U.S. indications is cemiplimab-rwlc, with rwlc as the suffix designated in accordance with Nonproprietary Naming of Biological Products Guidance for Industry issued by the FDA. Outside of the U.S., the generic name for Libtayo in its approved indication is cemiplimab.