Design, Synthesis, and Antitumor Activity Evaluation of 2-Arylmethoxy-4-(2,2-dihalogen-substituted biphenyl-3-ylmethoxy) Benzylamine Derivatives as Potent PD-1/PD-L1 Inhibitors

Novel 2-arylmethoxy-4-(2,2 & PRIME;-dihalogen-substitutedbiphenyl-3-ylmethoxy)benzylamine derivatives were designed, synthesized, and evaluated in vitro and in vivo against cancers asPD-1/PD-L1 inhibitors. Through the computer-aided structural optimizationand the homogeneous time-resolved fluorescence (HTRF) assay, compound A56 was found to most strongly block the PD-1/PD-L1 interactionwith an IC50 value of 2.4 & PLUSMN; 0.8 nM and showed themost potent activity. H-1 NMR titration results indicatedthat A56 can tightly bind to the PD-L1 protein with K (D) < 1 & mu;M. The X-ray diffraction datafor the cocrystal structure of the A56/PD-L1 complex(3.5 & ANGS;) deciphered a novel binding mode in detail, which canaccount for its most potent inhibitory activity. Cell-based assaysfurther demonstrated the strong ability of A56 as anhPD-1/hPD-L1 blocker. Especially in an hPD-L1 MC38 humanized mousemodel, A56 significantly inhibited tumor growth withoutobvious toxicity, with a TGI rate of 55.20% (50 mg/kg, i.g.). In conclusion, A56 is a promising clinical candidate worthy of further development.