Definition

A combination formulation containing fixed doses of the two monoclonal antibodies pembrolizumab and quavonlimab, with potential immune checkpoint inhibitory and antineoplastic activities. Upon administration of pembrolizumab/quavonlimab MK-1308A, pembrolizumab, a monoclonal antibody directed against the human cell surface receptor PD-1 (programmed death-1 or programmed cell death-1), targets and binds to PD-1, an inhibitory signaling receptor expressed on the surface of activated T cells, and blocks the binding to and activation of PD-1 by its ligands, which results in the activation of T-cell-mediated immune responses against tumor cells. The ligands for PD-1 include programmed cell death ligand 1 (PD-L1), overexpressed on certain cancer cells, and programmed cell death ligand 2 (PD-L2), which is primarily expressed on antigen presenting cells (APCs). Activated PD-1 negatively regulates T-cell activation and plays a key role in in tumor evasion from host immunity. Quavonlimab, a monoclonal antibody directed against the human T-cell-expressed receptor cytotoxic T-lymphocyte-associated antigen 4 (CTLA4; CTLA-4), targets and binds to CTLA4 expressed on T cells and inhibits the CTLA4-mediated downregulation of T-cell activation. This leads to a cytotoxic T-lymphocyte (CTL)-mediated immune response against cancer cells. CTLA4, an inhibitory receptor and member of the immunoglobulin superfamily, plays a key role in the downregulation of the immune system.