GJ19 is a PD-L1 inhibitor with an IC50 of 32.06 nM. It binds effectively to human and mouse PD-L1 proteins, exhibiting KD values of 171 nM and 290 nM, respectively. In a co-culture model of HepG2/hPD-L1 and Jurkat T/hPD-1 cells, GJ19 promotes HepG2 cell death in a concentration-dependent manner. In the B16-F10 melanoma mouse model, GJ19 demonstrates significant tumor growth inhibition. GJ19 is applicable in tumor immunotherapy research.

GJ19 demonstrates the most potent PD-L1 inhibitory effect in an HTRF assay (48 h) with an IC50 value of 32.06 nM, surpassing the positive control BMS-202 (IC50 = 62.1 nM). GJ19 effectively binds human/murine PD-L1 protein within the range of 0.1-10 μM, with KD values of 171 nM and 290 nM, respectively. After 48 hours, GJ19 shows minimal cytotoxicity against tested tumor cells, including murine/human melanoma cell lines B16-F10/A375, human liver cancer cell line HepG2, human breast cancer cells MDA-MB-231, and Jurkat T cells, with toxicity only appearing in co-culture with T cells. In a co-cultural system with HepG2/Jurkat T cells, GJ19 (12.3-1000 nM, 24 h) significantly increases HepG2 cell death in a dose-dependent manner and at 1000 nM exhibits a higher killing rate of HepG2 cells than BMS-202.

GJ19 (5-15mg/kg, i.p.) exhibits significant antitumor activity in the B16-F10 melanoma mouse model, with a tumor growth inhibition rate (TGI) of 56.8% at a dosage of 15 mg/kg.