By generating all 15 possible combinatorial heterodimeric biparatopic antibodies from 6 optimized monospecific antibodies that bind to distinct epitopes along the FGFR2 ECD, we identified 2 anti-FGFR2 biparatopic antibodies that are markedly superior to their parental bivalent antibodies in their potency against FGFR2-fusion driven cancers. The gene discussed is FGFR2; the disease is cancer.