Five Prime Therapeutics and Zai Lab start Phase 3 study of bemarituzumab for advanced gastric cancer

California-based Five Prime Therapeutics and Chinese biopharma Zai Lab have initiated a pivotal Phase 3 trial of bemarituzumab (FPA144) in combination with chemotherapy for patients with advanced gastric cancer (GC) or gastroesophageal junction (GEJ) cancer. The trial, named FIGHT, represents a significant milestone in the development of targeted therapies for these challenging cancers.

The FIGHT trial aims to evaluate the efficacy of bemarituzumab, an isoform-selective FGF receptor 2b (FGFR2b) antibody, when used alongside modified FOLFOX6 (mFOLFOX6) chemotherapy. This late-stage study will involve approximately 550 patients with advanced GC or GEJ cancer whose tumors overexpress FGFR2b and who have not received any prior treatment for their condition.

Five Prime Therapeutics, headquartered in California, has developed bemarituzumab as a targeted therapy specifically designed to combat tumors that express FGFR2b. Zai Lab, a prominent biopharma company based in China, is responsible for the regulatory and development aspects of the global Phase 3 trial.

Bemarituzumab Trial Overview

The FIGHT trial will administer bemarituzumab at a dose of 15 mg/kg or a placebo every two weeks, in combination with mFOLFOX6 chemotherapy. The first patient in this global study has been dosed at an investigative site in China, marking a notable achievement in the collaboration between a U.S. and a Chinese biotechnology company.

Dr. Yongjiang Hei, Chief Medical Officer of Zai Lab, highlighted the significance of this trial: “This is the first time that the first patient dosed in a global registrational trial came from China as a result of the collaboration between a U.S. biotechnology company and a Chinese biotechnology company. Gastric cancer is the fifth most common cancer worldwide and the second most common in China. There is an urgent need globally, and particularly in China, for more effective and well-tolerated targeted therapies for gastric cancer patients.”

The partnership between Five Prime Therapeutics and Zai Lab will see the latter managing the Phase 3 trial in China, where nearly half of the trial’s participants are expected to be enrolled. The primary endpoint of the FIGHT trial is overall survival (OS), while secondary endpoints include progression-free survival (PFS), objective response rate (ORR), safety, and pharmacokinetic (PK) parameters.

Expert Insights on Bemarituzumab

Helen Collins, Senior Vice President and Chief Medical Officer of Five Prime Therapeutics, commented on the trial’s potential: “Tumors overexpressing FGFR2b are associated with a poor prognosis, and a targeted therapy that provides improved efficacy when added to standard therapy could transform treatment options for these patients. Bemarituzumab has demonstrated encouraging monotherapy activity in the late-line setting, and we hope to provide greater benefit by combining it with chemotherapy in the front-line setting.”

Bemarituzumab is a first-in-class FGFR2b antibody developed as a targeted immune therapy. Unlike other treatments, bemarituzumab is designed to specifically target FGFR2b without interfering with normal cellular processes such as metabolic regulation or glucose management. It works through two mechanisms: inhibiting the binding of fibroblast growth factors that promote tumor growth and facilitating immune-based destruction of tumor cells via antibody-dependent cell-mediated cytotoxicity.

As Five Prime Therapeutics and Zai Lab advance their clinical research with bemarituzumab, the FIGHT trial stands to significantly impact the treatment landscape for advanced gastric and gastroesophageal junction cancers. The collaboration exemplifies the growing international partnerships aimed at tackling complex medical challenges through innovative therapies.