ICOS and neoplasm: Other molecules such as lymphocyte-activation gene 3 (LAG-3), T cell immunoglobulin and mucin domain-containing 3 (TIM-3), T cell immunoreceptor with Ig and ITIM domains (TIGIT), inducible costimulator (ICOS), glucocorticoid-induced tumor necrosis factor-related receptor (GITR) and CD27 are unregulated on Ti-Tregs and contributed to their immunosuppressive activity in tumor treatment (67).