Novel Resorcinol Dibenzyl Ether-Based PD-L1 Inhibitors Modulate Lipid Metabolism for Enhanced Tumor Immunotherapy

As a critical immune checkpoint molecule, PD-L1 not only
suppresses
antitumor immunity but also directly promotes tumor progression by
reprogramming lipid metabolism. In this study, we designed and synthesized
a novel series of compounds by introducing a tail group at the biphenyl
core to develop potent small-molecule PD-1/PD-L1 inhibitors. Among
these, compound ZQ8 exhibited the highest PD-L1 inhibitory
activity (IC50 = 6.9 nM), significantly surpassing the
reference compounds NP19 and BMS-202. Furthermore, ZQ8 demonstrated functional activity by inhibiting lipid accumulation
via suppression of the mTOR-SREBP1 pathway, decreasing cholesterol
and triglycerides in steatotic HepG2 cells. In vivo studies using a HEPA1-6 mouse tumor model revealed that ZQ8 achieved 86.2% tumor growth inhibition at 20 mg/kg, accompanied
by enhanced CD3+CD8+ T-cell infiltration and
reduced lipid accumulation in serum. Collectively, ZQ8 represents a promising PD-1/PD-L1 inhibitor with immune- and lipid
metabolism-modulating effects, warranting further study as a potential
anticancer agent.