Adebrelimab (Anti-B7-H1 / PD-L1 / CD274) is a humanized immunoglobulin G4 (IgG4) monoclonal antibody directed against the immunosuppressive ligand programmed cell death-1 ligand 1 (PD-L1, cluster of differentiation 274, CD274) with promising antitumor activity in solid tumors including extensive-stage small-cell lung cancer (SCLC). MW: 145.8 kD.