Definition

A monoclonal antibody directed against the myeloid-enriched immune inhibitory receptor leukocyte immunoglobulin-like receptor B member 4 (LILRB4; ILT3; ILT-3), with potential immune checkpoint inhibitory and antineoplastic activities. Upon administration, anti-LILRB4 monoclonal antibody NGM831 targets, binds to and blocks LILRB4, thereby preventing the interaction with its ligands, such as fibronectin, in the tumor microenvironment (TME). This prevents the activation of LILRB4-mediated downstream signaling pathways. This may abrogate LILRB4-mediated promotion of myeloid cell immunosuppression and inhibition of antitumor immunity. This may restore immune function by activating dendritic cells (DCs) and T cells, and may promote T-cell-mediated immune responses against tumor cells. LILRB4, an inhibitory immune receptor highly expressed on tumor-associated myeloid cells, primarily tolerogenic DCs, myeloid-derived suppressor cells (MDSCs) and M2 macrophages, functions as an immune checkpoint that negatively regulates DC- and T-cell activation. It is upregulated in several tumor types and plays an important role in tumor infiltration, immunosuppression and immune tolerance.