ICOS and neoplasm: Preclinical studies have shown that mice receiving local radiotherapy in the liver have a higher proportion of T cells inducible T-cell costimulatory (ICOS), glucocorticoid-induced tumor necrosis factor receptor (GITR) and LAG3 CD8+ T cells and CD4+ T cells expressing 4-1BB, GITR and TIM-3 also expressed higher levels of PD-1/PD-L1 on the tumor cell surface, to promote systemic anti-tumor immunity (57–59).