Radiation and anti-PD-L1 antibody combinatorial therapy induces T cell-mediated depletion of myeloid-derived suppressor cells and tumor regression

Tumor relapse after radiotherapy may be due to the upregulation of programmed cell death ligand 1 (PD-L1). We demonstrated that anti-PD-L1 antibody synergizes with radiation to control local and distal tumors. CD8⁺T cells mediated antitumor effects of the combination therapy by the reduction of myeloid-derived suppressor cells (MDSCs) via tumor-necrosis factor (TNF)-mediated signaling. Our study provides insight into immune- and radiation-based combinational therapies.