PDCD1 and neoplasm: Emerging evidence has indicated that radiotherapy could offer immunogenic effects, such as increased major histocompatibility complex (MHC) class I molecules with released neoantigens from tumors, enhanced tumor infiltration of CD8 + cytotoxic T lymphocytes (CTLs), and PD-L1 upregulation on tumor cells by IFNγ produced by CD8 + T cells, which offers plausible premises that radiotherapy exerts the synergistic effect with PD-1 blockage [5], [6], [7].