Five Prime Therapeutics, Inc. (NASDAQ: FPRX) skyrocketed Wednesday, more than 260%, after the developer of innovative protein therapeutics announced together with Zai Lab Limited positive topline results from the global, randomized, double-blind, placebo-controlled Phase 2 FIGHT trial. The trial compared bemarituzumab (FPA144), a potential first-in-class targeted therapy, in combination with mFOLFOX6 chemotherapy to placebo in combination with mFOLFOX6 in patients with fibroblast growth factor receptor 2b-positive (FGFR2b+), HER2-negative front-line advanced gastric or gastroesophageal junction (GEJ) cancer.
The report indicates that all three efficacy endpoints in the FIGHT trial – PFS, OS and ORR – achieved pre-specified statistical significance in the bemarituzumab arm compared to the placebo arm. The data shows that Phase 2 FIGHT trial results validate the importance of the novel target FGFR2b, which is overexpressed in approximately 30 percent of HER2- gastric cancers worldwide.
Five Prime Therapeutics and Zai Lab Limited elaborated that the incidence of all-grade adverse events was comparable in the treatment and control arms of the study (100% vs. 98.7%, respectively), as were serious adverse events (31.6% vs. 36.4%) and deaths due to adverse events (6.6% vs. 5.2%). Adverse events ≥ Grade 3 were reported more frequently in the treatment arm (82.9% vs. 74.0%). Corneal and stomatitis adverse events were reported more frequently in the bemarituzumab arm. No adverse events of retinal detachment or hyperphosphatemia were reported in the bemarituzumab arm. More patients discontinued bemarituzumab (34.2%) compared to placebo (5.2%) due to an adverse event.
“These results bring us one step closer to the first potential targeted therapy for advanced gastric cancer in over a decade,” said Helen Collins, M.D., Five Prime’s Executive Vice President and Chief Medical Officer. “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. We are excited about the results of the FIGHT trial and the opportunity to advance bemarituzumab, the first and only investigational treatment for patients with FGFR2b+ tumors, to the next phase of development. Five Prime is grateful to the patients and investigators who participated in our clinical trials, and we look forward to discussing next steps with health authorities worldwide.”