Effects of 26 Recombinant CYP3A4 Variants on Brexpiprazole Metabolism

As a new atypical antipsychotic, brexpiprazole is primarily metabolized by cytochrome P450 3A4 (CYP3A4). However, genetic polymorphisms in CYP3A4 cause wide variability in individuals' responses to brexpiprazole, leading to unpredictable adverse side effects or even therapeutic failure. The present study was designed to systematically study the effects of 26 recombinant CYP3A4 variants on the metabolism of brexpiprazole and investigate their enzymatic activity. Wild-type CYP3A4 and the 26 variants were incubated with the substrate brexpiprazole for 30 min at 37 °C. The metabolite DM-3411 was detected using ultraperformance liquid chromatography-tandem mass spectrometry. The activity of the wild-type CYP3A4 and 26 of its variants was analyzed. Then, the mechanism underlying the changes in enzyme function was observed using molecular dynamics simulations and molecular docking. Compared with CYP3A4.1, the enzymatic activities of CYP3A4.19, -.24, and -.28 were not significantly different (from 91.82% to 96.25%), but CYP3A4.14 and CYP3A4.15 exhibited higher enzyme activity (from 117.9 to 127.5%). The remaining 21 isoforms, including CYP3A4.2, -.3, -.4, -.5, -.7, -.8, -.9, -.10, -.11, -.12, -.13, -.16, -.17, -.18, -.20, -.23, -.29, -.31, -.32, -.33 and -.34, displayed lower enzymatic activities (from 2.90% to 75.72%). The results obtained from computer modeling indicated that weak binding affinity impaired the function of CYP3A4.32. Mutations that occur around the active site might lead to a loss of enzymatic activity, while the variants located far away from the active site perhaps had little effect on function of CYP3A4. These comprehensive data provide a reference and prediction for treatment strategies and risk assessments of brexpiprazole.