CYP2C19 Polymorphisms Account for Inter-individual Variability of Drug Metabolism in Cynomolgus Macaques

CYP2C19 (formerly known as CYP2C75), highly homologous to human CYP2C19, has been identified in cynomolgus and rhesus macaques, non-human primate species widely used in drug metabolism studies. CYP2C19 is predominantly expressed in liver and encodes a functional drug-metabolizing enzyme. Genetic variants in human CYP2C genes account for the inter-individual variability in drug metabolism; however, genetic variants have not been investigated in macaque CYP2C19. In the present study, re-sequencing of CYP2C19 in 78 cynomolgus and 36 rhesus macaques identified 34 non-synonymous variants. Among these, 6 were located in substrate recognition sites, the domains important for protein function. Eighteen and 6 variants were unique to cynomolgus and rhesus macaques, respectively. Four variants were characterized by site-directed mutagenesis and metabolic assays, and 3 variants (p.Phe100Asn, p.Ala103Val, and p.Ile112Leu) showed substantially reduced activity as compared with wild type in flurbiprofen 4'-hydroxylation, omeprazole 5-hydroxylation, and R-/S-warfarin 7-hydroxylation. These variants, co-segregating in the animals analyzed, influenced metabolic activities because the homozygotes and/or heterozygotes showed significantly reduced catalytic activities in liver toward flurbiprofen 4'-hydroxylation and omeprazole 5-hydroxylation as compared with wild type. Kinetic analysis for R-warfarin 7-hydroxylation and docking simulation indicated that CYP2C19 Ala103Val would change the function and conformation of this enzyme. Ala103Val variation diminished homotropic cooperativity of CYP2C19 with R-warfarin yielding low metabolic capacity. These results indicated that the interindividual variability of CYP2C-dependent drug metabolism is at least partly accounted for by CYP2C19 variants in cynomolgus macaques.