Definition

A bispecific antibody consisting of a cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) inhibitory protein fused to an OX40 agonistic human immunoglobulin G1 (IgG1) antibody, with potential immunostimulating and antineoplastic activities. Upon administration, anti-CTLA-4/OX40 bispecific antibody ATOR-1015 simultaneously binds to CTLA-4 and OX40, which may inhibit CTLA-4-mediated downregulation of T-cell activation and induce proliferation of memory and effector T lymphocytes via OX40 activation. Both CTLA-4, an inhibitory receptor and member of the immunoglobulin superfamily (IgSF), and OX40, a cell surface glycoprotein and member of the tumor necrosis factor receptor superfamily (TNFRSF), are overexpressed by regulatory T cells (Tregs) in the tumor microenvironment. ATOR-1015 may reduce the number of Tregs and promote the activation of effector T cells, thereby enhancing the immune-mediated anti-tumor response.