Definition

An Fc-attenuated human immunoglobulin G1 (IgG1) monoclonal antibody directed against the C-type lectin-like receptor cluster of differentiation 161 (CD161), with potential immunomodulatory and antineoplastic activities. Upon administration, anti-CD161 monoclonal antibody IMT-009 selectivity targets, binds to and blocks CD161. This disrupts the interaction of CD161 with its ligand lectin-like transcript-1 (CLEC2D; LLT1; OCIL), prevents CD161-mediated signaling, abrogates the CLEC2D/ CD161-mediated suppression of CD161-positive T and natural killer (NK) cells, and restores the activation of effector functions of both CD161-positive T and NK cells against tumor cells, thereby enhancing cytotoxicity towards tumor cells. CD161, an inhibitory immune checkpoint, is broadly expressed on NK and a subset of memory CD4+ and CD8+ T cells. It plays a key role in cancer immune surveillance and its expression is associated with many types of cancer. CLEC2D is expressed on the surface of both malignant cells and immune cells, including activated B cells and myeloid cells.