ICOS and neoplasm: However, there are other immune checkpoints that could be targeted, such as, B7-H3, B7-H4, T cell immunoglobulin and mucin domain-containing protein 3 (TIM-3), and several co-stimulatory molecules, such as CD137, glucocorticoid-induced tumour necrosis factor receptor family-related protein (GITR), inducible co-stimulator (ICOS), regulating T-cell mediated anti-tumor response [36, 48, 71].