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Five Prime Therapeutics' FGFR Inhibitor Improves Survival in Gastric Cancer Trial

This article has been updated to clarify that the prevalence of FGFR2b-positive, HER2-negative gastric cancers is an observation outside of the FIGHT trial. 

NEW YORK – Five Prime Therapeutics on Tuesday announced topline results from its Phase II trial of bemarituzumab in advanced gastric or gastroesophageal junction (GEJ) cancer that overexpresses FGFR2b.

The 155-patient FIGHT trial is comparing bemarituzumab plus chemotherapy against just chemotherapy as a front-line treatment for FGFR2b-positive, non-HER2-positive, gastric cancer patients. According to the company, the addition of bemarituzumab to chemo improved median progression-free survival compared to those receiving only chemo — to 9.5 months versus 7.4 months — and improved the overall response rate by 13.1 percent. Median overall survival for patients receiving only chemotherapy was 12.9 months and was not reached for bemarituzumab.

The company will continue to evaluate the data and will share the full results at a future medical conference.

Bemarituzumab is a targeted antibody that blocks fibroblast growth factors (FGFs) from binding and activating FGFR2b, inhibiting several downstream pathways. Approximately 30 percent of HER2-negative gastric cancers worldwide are FGFR2b positive. FGFR2b is also overexpressed in other cancers, including squamous non-small cell lung cancer, triple-negative breast cancer, ovarian cancer, pancreatic cancer, and intrahepatic cholangiocarcinoma.

"These results bring us one step closer to the first potential targeted therapy for advanced gastric cancer in over a decade," Helen Collins, chief medical officer at Five Prime, said in a statement. "Benefit was observed in patients whose tumors overexpressed FGFR2b, even without evidence of amplification, and that may broaden the therapeutic potential of bemarituzumab in more cancer types."