Icrucumab, fully human immunoglobulin G1 (IgG1) monoclonal antibody directed against human vascular endothelial growth factor receptor 1 (VEGFR-1/FLT-1). It functions as a specific VEGFR-1 inhibitor with potential antiangiogenic and antitumor activity. By binding with high affinity to VEGFR-1, icrucumab blocks the interaction between the receptor and its primary ligands, vascular endothelial growth factor A (VEGF-A) and placental growth factor (PlGF). This blockade inhibits the downstream signaling pathways mediated by VEGFR-1, which are involved in promoting angiogenesis (the formation of new blood vessels), vascular permeability, and the recruitment of pro-tumorigenic myeloid cells. As an IgG1 antibody, it may also engage immune effector functions such as antibody-dependent cellular cytotoxicity (ADCC) against VEGFR-1-expressing cells.