Figure 1.

Immune responses induced by radiotherapy include those caused by DNA damage and those that occur in the tumor microenvironment. The immune response to radiotherapy creates an environment in which immune checkpoint inhibitor can more effectively eliminate tumors. Immune response to DNA damage includes programmed death ligand 1 (PD-L1) upregulation, which contributes to immunosuppression, but can be a target of the PD-1/PD-L1 blockade. DAMP, damage-associated molecular pattern; DC, dendritic cell; IFN, interferon; MHC, major histocompatibility complex; TAA, tumor-associated antigen.