Fig. 7

The targets of small molecules in the field of cancer immunotherapy. Tumor cells are encased by various immune cells, including Tregs, Teffs, MDSCs, TAMs, and DCs. Scientists are exploring various proteins and receptors found on tumor and immune cells as potential targets for cancer immunotherapy. The targets encompass PD-1/PD-L1, RORγt, chemokine receptors, and TGF-β, linked to the adaptive immune response; Sting and TLR, associated with the innate immune response; and IDO, arginase, and A2 A adenosine receptor, which are relevant to the tumor microenvironment. The most promising and therapeutically developed targets consist of immune checkpoint proteins like PD-L1 (found on tumor cells), PD-1 (located on effector T cells), and CTLA4 (present on Tregs). Additional targets being examined in immuno-oncology encompass IDO/TDO and arginases, which play a role in the inherent processes of cancer cells [271]