Bemarituzumab is a humanized monoclonal antibody designed to target the fibroblast growth factor receptor 2 (FGFR2), particularly FGFR2b isoform, which is overexpressed in certain epithelial cancers. Its primary application is in the treatment of advanced gastric or gastroesophageal junction (GEJ) cancers that overexpress FGFR2b and are negative for HER2.

The antibody works through multiple mechanisms: it blocks FGFR2b signaling pathways that drive tumor growth, induces antibody-dependent cellular cytotoxicity (ADCC) by engaging immune effector cells, and inhibits ligand binding (FGF and FGF3). This dual action—direct signaling inhibition and immune-mediated tumor cell killing—makes it a promising targeted therapy.

Bemarituzumab is being evaluated in clinical trials, notably in combination with standard chemotherapy (like mFOLFOX6), showing improved progression-free and overall survival in biomarker-selected patients. It represents a precision medicine approach, where patient selection is based on tumor biomarker status, enhancing treatment efficacy and minimizing unnecessary exposure in non-responders.

Its development marks a significant step in personalized oncology, especially for cancers with limited treatment options and poor prognosis.