Role of pharmacogenetics and clinical parameters on nevirapine plasma concertation among HIV-1 patients receiving Antiretroviral Therapy in Kenya

Abstract

Background: Patients’ clinical outcomes and pharmacogenetic factors are important predictors of nevirapine (NVP) plasma concentration. This study evaluated the association of socio-demographic factors and Cytochrome P450 2B6 (CYP2B6) polymorphisms with NVP plasma concentrations among patients receiving antiretroviral therapy (ART) treatment in western and coastal Kenya. Methods: Blood samples were collected from 377 consenting HIV adult patients receiving an NVP-based first-line ART regimen. A detailed sociodemographic questionnaire was administered. NVP plasma concentration was measured by liquid chromatography - tandem mass spectrometry (LC-MS/MS). CYP2B6 c.516 G>T rs3745274 and c.983T>C genotypes were evaluated using real-time polymerase chain reaction. HIV drug resistance mutations were detected using an in-house genotypic assay. Results: The patients’ mean age was 41.6 (SD ± 11.5) years and the majority (59.2%) were female. The mean duration of ART was 5.1 (SD ± 4.8) years. Overall NVP plasma levels ranged from 4-44207 ng/mL (median 6213 ng/mL, IQR 3097–8606.5 ng/mL). There were 105 (25.5%) participants with NVP levels of <3100 ng/mL, associated with poor viral suppression. Multivariate linear regression analysis showed CYP2B6 516 G>T polymorphism (β 0.71, 95% CI 0.4–0.98; p<0.0001), male gender (β 0.45, 95% CI 0.01–0.9; p=0.047) and presence of HIV drug-resistant virus (β 1.98, 95% CI 1.24–2.72; p<0.001) were the independent factors influencing NVP plasma concentration. Conclusions: The majority of patients receiving an NVP-based ART regimen had plasma concentrations within the therapeutic range. CYP2B6 516 G>T polymorphism, gender and presence of a HIV drug-resistant mutation significantly influences NVP plasma concentration. Routine pharmacogenetic testing and measurement of NVP plasma concentrations, considering gender and presence of HIV drug-resistant mutations are key to ensuring optimal ART treatment outcomes in Kenya.