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

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.

Systematic profiling of ATP response to acquired drug-resistant EGFR family kinase mutations

Kinase-targeted cancer therapy (KTCT) with ATP-competitive inhibitors has been widely applied in clinics. However, a number of kinase missense mutations were observed to confer acquired drug resistance during therapy, largely limiting the clinical application of kinase inhibitors in KTCT. Instead of directly influencing inhibitor binding, kinase mutations can also cause generic resistance to ATP-competitive inhibitors by increasing ATP affinity. Herein, the intermolecular interaction of the ATP molecule with clinically observed drug-resistant EGFR family kinase mutations involved in human cancer are systematically characterize. Rigorous quantum mechanics/molecular mechanics (QM/MM) calculation and empirical Poisson?Boltzmann/surface area (PB/SA) analysis as well as in vitro kinase assay and surface plasmon resonance analysis were integrated to explore the binding capability of ATP to mutant residues in the structural context of the kinase domain, which resulted in a comprehensive profile of ATP response to acquired drug-resistant mutations of four EGFR family kinases (EGFR/ErbB1, ErbB2, ErbB3 and ErbB4). From the profile, it was possible to identify those potent mutations that may influence ATP binding significantly; such mutations are potential candidates to cause generic resistance for ATP-competitive inhibitors. Consequently, the well documented generic drug-resistant mutation EGFR T790M and its counterpart ErbB2 T798M are found to increase ATP affinity by establishing an additional S?? interaction between the side-chain thioether group of the mutant Met residue and the aromatic adenine moiety of the ATP molecule, while EGFR D761Y is identified as a new generic drug-resistant mutation that can increase ATP affinity by eliminating unfavorable electrostatic repulsion. In contrast, ErbB2 K753E and T768I are considered to be two generic drug-sensitive mutations that can decrease ATP affinity by unfavorable charge reversal and by impairing favorable polar interaction, respectively. In addition, the EGFR L858R mutation is located at the kinase activation loop and nearby the kinase active site, thus largely complicating the multiply dependent relationship of kinase, ATP and inhibitor, which therefore exhibits divergent effects on different tested inhibitors.

Hepatitis B virus pre-existing drug resistant mutation is related to the genotype and disease progression

Introduction: Previous studies have indicated that the drug-resistant mutations of hepatitis B virus (HBV) are a major obstacle to antiviral therapy. However, it is still unclear whether there are pre-existent resistance mutations in patients with HBV infection and the relationship between drug-resistant mutation, genotypes, and progression of hepatitis B disease. Methodology: A total of 357 treatment-naïve patients with HBV infection were involved in this retrospective study. The drug-resistant mutations of HBV reverse transcriptase domain were screened by direct gene sequencing. Results: Lamivudine (LAM) resistance was detected in 8 patients (3.7%) with chronic hepatitis B (CHB), 13 (11.7%) patients with liver cirrhosis (LC), and 6 (21.4%) patients with hepatocellular carcinoma (HCC). Adefovir(ADV)-resistant mutations were detected in 10 (4.6%) patients with CHB, 15 (13.5%) patients with LC and 4 (14.5%) patients with HCC. Both LAM and ADV resistant mutations were detected in 2 patients (0.9%) with CHB, 1 patient (0.9%) with LC and 1 patient (3.6%) with HCC. Significant differences (p <0.01) were observed in the drug-resistance rates among patients with CHB, LC and HCC. Meanwhile, all the drug-resistant mutations were found in patients with HBV genotype C. Conclusions: This study demonstrated higher risk of pre-existing drug-resistant mutations in patients with HBV genotype C comparing to patients with HBV genotype B. Likewise, increasing prevalence of pre-existing drug-resistant mutations was shown, alongside with the progression of the disease.