Neutralizing antibody to FGFR2 can act as a selective biomarker and potential therapeutic agent for gastric cancer with FGFR2 amplification.

Fibroblast growth factor receptor 2 (FGFR2) amplification has been reported in 5-10% of gastric cancer (GC) and is associated with poor prognosis. In this study, we characterized the anti-tumor effect of PRO-007, a newly developed recombinant monoclonal antibody that targets FGFR2, in GC cell lines KATO III (with FGFR2 amplification) and NCI-N87 (without FGFR2 amplification). Validation was performed in parallel using two patient-derived tumor cells (PDCs) from patients with GC. Cell viability assays were performed using FGFR2-transfected NCI-N87 cells and FGFR2-knockdown KATO III cells that were generated using short hairpin RNA (shRNA). PRO-007 reduced KATO III cell viability (P = 0.0034) but not that of NCI-N87 cells (P = 0.3710). PRO-007 also significantly reduced KATO III cell invasiveness (P < 0.0001) but not NCI-N87 cell invasiveness (P = 0.8136). Immunoblot analysis showed that PRO-007 treatment decreased the levels of phosphorylated AKT and ERK. The FGFR2-inhibitory activity of PRO-007 was confirmed in genetically modified GC cell lines. Cell viability of FGFR2-overexpressing NCI-N87 cells was significantly decreased by PRO-007, while KATO III cells were significantly resistant to the treatment when FGFR2 was knocked down by FGFR2 shRNA transfection. Furthermore, PRO-007 had a synergistic effect with ramucirumab on the invasiveness of cancer cells with FGFR2 amplification. Consistent results were obtained using PDCs from patients with GC. Overall, these preclinical data support the further clinical development of PRO-007 as a potential therapeutic agent for patients with FGFR2-amplified GC.