Biphenyl-substituted five-membered heterocyclic compound as well as preparation method, pharmaceutical composition and application thereof

The invention discloses a biphenyl-substituted five-membered heterocyclic compound as well as a preparation method, a pharmaceutical composition and application of the biphenyl-substituted five-membered heterocyclic compound. The structure of the biphenyl-substituted five-membered heterocyclic compound is shown as a formula (I), and the biphenyl-substituted five-membered heterocyclic compound also comprises stereoisomers, meso-isomers, racemes, prodrugs, crystals, pharmaceutically acceptable salts or a mixture of the stereoisomers, the meso-isomers, the racemes, the prodrugs, the crystals and the pharmaceutically acceptable salts. The compound has PD-L1 inhibitor activity, can remarkably inhibit PD-1/PD-L1 protein-protein interaction and block a PD-1/PD-L1 signal channel, so that the compound can be widely applied to preparation of immunomodulator drugs for preventing and/or treating tumors, infectious diseases, inflammatory diseases, autoimmune diseases and organ transplantation rejection, and can be used fo