Overview
Bemarituzumab (anti-FGFR2b) is an Fc-optimized monoclonal antibody that is designed to block fibroblast growth factors (FGFs) from binding and activating FGFR2b, inhibiting several downstream pro-tumor signaling pathways and potentially slowing cancer progression. The FIGHT trial evaluated bemarituzumab plus chemotherapy (mFOLFOX6) versus placebo plus chemotherapy alone in patients with FGFR2b positive, HER2 negative frontline advanced gastric or GEJ cancer. In the study, treatment with bemarituzumab plus chemotherapy demonstrated clinically significant and substantial improvements in the primary endpoint of progression-free survival (PFS) and secondary endpoint of overall survival (OS) in the patient population with FGFR2b overexpression which accounts for 30% of HER2 negative patients. Based on this, the FDA granted bemarituzumab Breakthrough Therapy Designation. Zai Lab has an exclusive license for bemarituzumab in greater China, and we collaborated with Five Prime (subsequently acquired by Amgen) on the Phase 2 FIGHT trial in greater China. Two global phase 3 clinical studies for FGFR2b overexpression in first-line patients with advanced gastric or GEJ cancer are ongoing (with China’s participation).
Mechanism of Action
Bemarituzumab acts through a two-pronged approach. First, it selectively inhibits FGFR2b signaling with downstream effects on cancer cell proliferation. Second, the afucosylated structure of bemarituzumab leads to activation of FcγRIIIa/CD16a, which increases the affinity of bemarituzumab for natural killer cells, thereby enhancing its antibody-dependent cellular cytotoxicity against FGFR2b-expressing tumor cells.