The small molecule inhibitor of S1R 1-(4-Iodophenyl)-3-(2-adamantyl)guanidine (IPAG) was shown to decrease the expression of the programmed death receptor ligand 1 (PD-L1) and suppress PD-L1 interaction with its PD-1 receptor in T-cell, and in cell lines of PC3 prostate cancer and MDA-MB-231 triple negative breast cancer (Maher et al., 2018). This evidence concerns the gene CD274 and triple-negative breast carcinoma.