A recombinant B7-DC Fc-fusion protein composed of the extracellular domain of the PD-1 ligand programmed cell death ligand 2 (PD-L2, B7-DC) and the Fc region of human immunoglobulin (Ig) G1, with potential immune checkpoint inhibitory and antineoplastic activities. Anti-PD-1 fusion protein AMP-224 specifically binds to PD-1 on chronically stimulated T-cells and reduces their proliferation. This may restore immune function and may result in the activation of cytotoxic T-cells and cell-mediated immune responses against tumor cells. PD-1, a transmembrane protein of Ig superfamily and inhibitor receptor expressed on activated T-cells, negatively regulates T-cell activation and effector function when activated by its ligands, and plays an important role in tumor evasion from host immunity. AMP-224 does not bind normal activated T-cells.