PDCD1 and neoplasm: In preclinical tumor models, surufatinib combined with anti–PD-1 or anti–PD-L1 could reverse immunosuppressive tumor microenvironment by inhibiting tumor angiogenesis, increasing activated cytotoxic T-cell infiltration, elevating the ratio of CD8 + T/Treg and reducing M2 tumor associated macrophages [14].