Five Prime Therapeutics Presents Data from Safety Lead-in to Phase 3 FIGHT Trial of Bemarituzumab at 2019 American Society of Clinical Oncology (ASCO) Gastrointestinal (GI) Cancers Symposium

Five Prime Therapeutics, Inc. (NASDAQ: FPRX), a clinical-stage biotechnology company focused on discovering and developing innovative immuno-oncology protein therapeutics, announced today that a poster entitled “Phase 1 Results from the Phase 1/3 FIGHT Study Evaluating Bemarituzumab and mFOLFOX6 in Advanced Gastric/GEJ Cancer” was presented today at the ASCO Gastrointestinal Cancer Symposium in San Francisco. The poster (Board J1, Abstract #91) can be found online at Five Prime Therapeutics Scientific Publications.

“Gastric cancer with FGFR2b overexpression or FGFR2 gene amplification is associated with a poor prognosis for patients with advanced disease,” said Helen Collins, M.D., senior vice president and chief medical officer of Five Prime. “We completed the Phase 1 safety lead-in and saw no dose-limiting toxicities with the combination of bemarituzumab and mFOLFOX6. Additionally, we are encouraged to see evidence of clinical activity with the combination. The FIGHT Phase 3 study is currently enrolling patients worldwide with newly diagnosed advanced gastric and gastroesophageal junction cancer whose tumors overexpress FGFR2b with the goal of providing a better first-line treatment option for these patients.”

The Phase 1 portion of the study achieved the primary objective of determining a recommended dose of bemarituzumab in combination with mFOLFOX6 to initiate the Phase 3 portion of the FIGHT trial. Key inclusion criteria for the Phase 1 patient population included: adults with incurable GI cancer for whom mFOLFOX6 was an appropriate therapy, an ECOG score of 0-1, and evaluable disease by RECIST v1.1. The patient population was not selected for FGFR2b status or limited to patients without prior chemotherapy treatment for advanced or metastatic disease. At the time of publication, 2 patients with gastric/esophageal cancer were confirmed to be FGFR2 positive with 1 achieving a PR and the other demonstrating a complete metabolic response.

FIGHT Trial

In December 2017, Five Prime initiated the Phase 1 portion (NCT03343301) of the Phase 1/3 FIGHT (FGFR2b Inhibition in Gastric and Gastroesophageal Junction Cancer Treatment) global registrational trial. The Phase 1 safety lead-in portion of the trial was designed to identify a recommended dose of bemarituzumab in combination with the modified FOLFOX6 standard-of-care chemotherapy regimen (mFOLFOX6) to support the initiation of the Phase 3 portion of the trial.