A human immunoglobulin G1 (IgG1) monoclonal antibody directed against the fibroblast growth factor receptor type 3 (FGFR3), with potential antineoplastic activity. Upon intravenous administration, the anti-FGFR3 monoclonal antibody B-701 specifically binds to and inhibits both wild-type and mutated forms of FGFR3. This may result in the inhibition of FGFR3 phosphorylation, thereby preventing its activation and FGFR3-mediated signal transduction pathways. This results in the inhibition of cell proliferation and the induction of cell death in FGFR3-expressing tumor cells. FGFR3, a receptor tyrosine kinase upregulated or mutated in many tumor cell types, plays a key role in tumor cell proliferation.