Definition

A conditionally active biologic (CAB) and monoclonal antibody directed against the human T-cell-expressed receptor cytotoxic T-lymphocyte-associated antigen 4 (CTLA4; CTLA-4), with potential immune checkpoint inhibitory and antineoplastic activities. Upon administration and specific activation in the tumor microenvironment (TME) due to the unique microphysical conditions that are present in the TME, anti-CTLA-4 monoclonal antibody BA3071 targets and binds to CTLA-4 expressed on T cells within the TME and inhibits the CTLA-4-mediated downregulation of T-cell activation. This leads to a cytotoxic T-lymphocyte (CTL)-mediated immune response against cancer cells, thereby killing cancer cells. CTLA-4, an inhibitory receptor and member of the immunoglobulin superfamily (IgSF), plays a key role in the downregulation of the immune system. By using a CAB anti-CTLA-4 antibody, systemic toxicity may be reduced.