PD-L1-IN-3 (Compound 4a) is a compound that targets PD-1/PD-L1, the IC50 value and EC50 value is 4.97nM and 2.70 μM for inhibit PD-L1 and Jurkat T cells, respectively. PD-L1-IN-3 can bind PD-L1 dimer to prevent PD-1 binding to PD-L1, therefore blocking PD-1 signaling. PD-L1-IN-3 can be used for lung cancer and melanoma diseases research[1].