Benzinga | Aug 5, 2021 06:08AM EDT

Regeneron Says Phase 3 Trial Of Libtayo With Chemotherapy Was Stopped Early After Meeting Overall Survival Primary Endpoint

Libtayo combined with chemotherapy increased median overall survival from 13 to 22 months, leading to a 29% reduction in the risk of death

Trial enrolled patients with locally advanced and metastatic disease with squamous or non-squamous histology, across all PD-L1 expression levels

Libtayo has now demonstrated improved overall survival as a monotherapy or in combination with chemotherapy in first-line advanced non-small cell lung cancer

Regeneron Pharmaceuticals, Inc. (NASDAQ: REGN) and Sanofi today announced the Phase 3 trial of PD-1 inhibitor Libtayo in combination with platinum-doublet chemotherapy was stopped early after meeting its overall survival (OS) primary endpoint in patients with advanced non-small cell lung cancer (NSCLC). Adding Libtayo to chemotherapy significantly improved OS, compared to chemotherapy alone, in the trial that enrolled patients with metastatic or locally advanced disease and tumors with either squamous or non-squamous histology and across all PD-L1 expression levels. These data are planned to form the basis of regulatory submissions in the U.S. and European Union.

"Libtayo in combination with chemotherapy increased median overall survival to 22 months in patients with advanced non-small cell lung cancer, compared to 13 months with chemotherapy alone," said Miranda Gogishvili, M.D., an oncologist at the High Technology Medical Center, University Clinic, in Tbilisi, Georgia and a trial investigator. "Notably, the Phase 3 trial enrolled patients with a variety of challenging-to-treat disease characteristics, as well as those with locally advanced disease. These data add to the growing body of evidence supporting Libtayo in advanced non-small cell lung cancer, which also include the pivotal results for Libtayo monotherapy in cases of high PD-L1 expression."

The decision to stop the trial early was based on a recommendation by the Independent Data Monitoring Committee (IDMC) during a protocol-specified interim analysis. In this top-line initial analysis of 466 patients, combining Libtayo with chemotherapy reduced the risk of death by 29% compared to chemotherapy alone (hazard ratio: 0.71; 95% confidence interval [CI]: 0.53-0.93; p=0.014). Median OS was 22 months (95% CI: 16 months to not evaluable) for Libtayo and chemotherapy, and 13 months (95% CI: 12 to 16 months) for chemotherapy alone. No new Libtayo safety signals were identified in the IDMC analysis, and additional detailed efficacy and safety data will be presented at an upcoming medical meeting.

Lung cancer is the leading cause of cancer death worldwide. In 2020, an estimated 2.2 million and 225,000 new cases were diagnosed globally and in the U.S., respectively. Approximately 84% of all lung cancers are NSCLC, with 75% of these cases diagnosed in advanced stages. While PD-1 inhibitor monotherapy has primarily advanced the treatment of NSCLC with ?50% PD-L1 expression, approximately 70% of all NSCLC cases will have <50% PD-L1 expression, making it the most common treatment setting.

The use of Libtayo in combination with chemotherapy for advanced NSCLC is currently under clinical investigation, and its safety and efficacy have not been fully evaluated by any regulatory authority.

About the Phase 3 Trial

The randomized, multicenter Phase 3 trial, called EMPOWER-Lung 3, investigated a first-line combination treatment of Libtayo and platinum-doublet chemotherapy, compared to platinum-doublet chemotherapy alone, in squamous or non-squamous advanced NSCLC irrespective of PD-L1 expression. Specifically, the trial included 466 patients who tested negative for ALK, EGFR and ROS1 mutations and had either previously untreated metastatic NSCLC (stage IV) or locally advanced NSCLC (stage IIIB/C) and were not candidates for definitive chemoradiation.

Patients were randomized 2:1 to receive either Libtayo 350 mg (n=312) or placebo (n=154) administered intravenously every three weeks for 108 weeks, plus platinum-doublet chemotherapy administered every three weeks for four cycles. The co-primary endpoints were OS and progression-free survival, and key secondary endpoints included objective response rate and best overall response.

Among trial patients, 30% (n=139) had tumors with <1% PD-L1 expression, 38% (n=175) had tumors with 1% to 49% PD-L1 expression, and 33% (n=152) had tumors with ?50% PD-L1 expression.

About Libtayo

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.

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 U.S. FDA. Libtayo is being jointly developed by Regeneron and Sanofi under a global collaboration agreement.

The extensive clinical program for Libtayo is focused on difficult-to-treat cancers. Libtayo is currently being investigated in advanced cervical cancer, as well as in trials combining Libtayo 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.