Tumor cells benefit from some certain signals, which are referred to as “immune checkpoints”, to escape immune-mediated destruction. With that in mind, it is believed that the blockade of these points, such as programmed cell death Ligand-1 (PD-L1) and programmed cell death 1 (PD-1), can restore an adaptative immune response against tumoral cells. In this study, we have designed and synthesized some novel peptidomimetics with a 2-aminobenzathiazole scaffold, which targets the PD-1/PDL-1 pathway. In the viability assay, it was found that these compounds decreased the proliferation of peripheral blood mononuclear cells in the concentration of 10 uM. Overall, our results indicate that these novel compounds are potential checkpoint inhibitors for cancer immunotherapy.