CD274 and melanoma: Mechanistic investigation demonstrated that N. caninum administration enhanced the production of Th1 cytokines including interferon-γ (IFN-γ), IL-2, IL-10, IL-12, programmed death-ligand 1 (PD-L1) and tumor necrosis factor-α (TNF-α) in the TME of melanoma-bearing mice, resulting in extensive tumor cell death.