HMGB1 and neoplasm: In light of this, the enhanced anti‐tumor metastasis induced by the combination of therapy with anti‐CTLA‐4 checkpoint inhibitor might be explained by the synergistic anti‐cancer immune response triggered by PDT and hyperthermia‐induced ICDs including releasing HMGB1 and proinflammatory TNF‐α, IFN‐γ, and IL‐6, which facilitate the DCs maturation, enhanced CTLs infiltration, and Treg inhibition.