FPA144 gains rare disease nod from FDA

SOUTH SAN FRANCISCO, Calif.—Five Prime Therapeutics Inc., a clinical-stage biotechnology company focused on discovering and developing innovative immuno-oncology protein therapeutics, announced July 5 that the U.S. Food and Drug Administration (FDA) has granted Orphan Drug Designation to FPA144 for the treatment of gastric cancer, including cancer of the gastroesophageal junction in patients whose tumors overexpress FGFR2b. FPA144 is an anti-FGF receptor 2b (FGFR2b) humanized monoclonal antibody in clinical development as a targeted immune therapy.

“Patients with advanced gastric cancer whose tumors overexpress FGFR2b have a significant unmet medical need, and the literature suggests that they have an especially poor prognosis,” said Dr. Robert Sikorski, senior vice president and chief medical officer of Five Prime. “The initial single-agent efficacy and safety data seen so far during the ongoing FPA144 Phase 1 study is encouraging, and we look forward to further exploring FPA144 as a potential treatment for patients with gastric cancer.”

Orphan Drug Designation is granted by the FDA Office of Orphan Drug Products to products that treat rare diseases. The FDA defines rare diseases as those affecting fewer than 200,000 people in the United States. Orphan Drug Designation provides the sponsor certain benefits and incentives, including a period of marketing exclusivity if regulatory approval is received for the designated indication, as well as potential tax credits and waiver of certain administrative fees.

Globally, gastric cancer is the sixth most common malignancy with the third highest mortality. The prevalence of gastric cancer worldwide is approximately 1.5 million patients, of which an estimated 5 percent, or approximately 80,000 patients, have FGFR2 gene-amplified tumors that overexpress FGFR2b. There are an estimated 76,000 gastric cancer patients in the United States, but the prevalence of gastric cancer is much higher in Asia and other regions of the world.

FPA144 is an anti-FGF receptor 2b (FGFR2b) humanized monoclonal antibody in clinical development as a targeted immune therapy for tumors that over-express FGFR2b, as determined by a proprietary immunohistochemistry (IHC) diagnostic assay. FGFR2 gene amplification (as identified by FISH) is found in a number of tumors, including in approximately 5 percent of gastric cancer patients, and is associated with poor prognosis.

FPA144 is designed to block tumor growth through two distinct mechanisms. First, it has been engineered to drive immune-based killing of tumor cells by antibody-dependent cell-mediated cytotoxicity (ADCC) and the recruitment of natural killer cells and T cells. Second, it binds specifically to FGFR2b and prevents the binding of certain fibroblast growth factors that promote tumor growth. When combined with PD-1 blockade, FPA144 has shown an additive effect in tumor growth inhibition in preclinical models. Five Prime retains global development and commercialization rights to FPA144.