Rifampin modulation of xeno- and endobiotic conjugating enzyme mRNA expression and associated microRNAs in human hepatocytes

Rifampin is a pleiotropic inducer of multiple drug metabolizing enzymes and transporters. This work utilized a global approach to evaluate rifampin effects on conjugating enzyme gene expression with relevance to human xeno- and endo-biotic metabolism. Primary human hepatocytes from 7 subjects were treated with rifampin (10 μmol/L, 24 hours). Standard methods for RNA-seq library construction, EZBead preparation, and NextGen sequencing were used to measure UDP-glucuronosyl transferase UGT, sulfonyltransferase SULT, N acetyltransferase NAT, and glutathione-S-transferase GST mRNA expression compared to vehicle control (0.01% MeOH). Rifampin-induced (>1.25-fold) mRNA expression of 13 clinically important phase II drug metabolizing genes and repressed (>1.25-fold) the expression of 3 genes (P < .05). Rifampin-induced miRNA expression changes correlated with mRNA changes and miRNAs were identified that may modulate conjugating enzyme expression. NAT2 gene expression was most strongly repressed (1.3-fold) by rifampin while UGT1A4 and UGT1A1 genes were most strongly induced (7.9- and 4.8-fold, respectively). Physiologically based pharmacokinetic modeling (PBPK) was used to simulate the clinical consequences of rifampin induction of CYP3A4- and UGT1A4-mediated midazolam metabolism. Simulations evaluating isolated UGT1A4 induction predicted increased midazolam N-glucuronide exposure (~4-fold) with minimal reductions in parent midazolam exposure (~10%). Simulations accounting for simultaneous induction of both CYP3A4 and UGT1A4 predicted a ~10-fold decrease in parent midazolam exposure with only a ~2-fold decrease in midazolam N-glucuronide metabolite exposure. These data reveal differential effects of rifampin on the human conjugating enzyme transcriptome and potential associations with miRNAs that form the basis for future mechanistic studies to elucidate the interplay of conjugating enzyme regulatory elements

Healthcare outcomes in undocumented immigrants undergoing two emergency dialysis approaches

BACKGROUND: Current estimates suggest 6,500 undocumented end-stage renal disease (ESRD) patients in the United States are ineligible for scheduled hemodialysis and require emergent dialysis. In order to remain in compliance with Emergency Medicaid, an academic health center altered its emergency dialysis criteria from those emphasizing interdialytic interval to a set emphasizing numerical thresholds. We report the impact of this administrative change on the biochemical parameters, utilization, and adverse outcomes in an undocumented patient cohort. METHODS: This retrospective case series examines 19 undocumented ESRD patients during a 6-month transition divided into three 2-month periods (P1, P2, P3). In P1, patients received emergent dialysis based on interdialytic interval and clinical judgment. In P2 (early transition) and P3 (equilibrium), patients were dialyzed according to strict numerical criteria coupled with clinical judgment. RESULTS: Emergent criteria-based dialysis (P2 and P3) was associated with increased potassium, blood urea nitrogen (BUN), and acidosis as compared to P1 (p < 0.05). Overnight hospitalizations were more common in P2 and P3 (p < 0.05). More frequent adverse events were noted in P2 as compared to P1 and P3, with an odds ratio (OR) for the composite endpoint (intubation, bacteremia, myocardial infarction, intensive care unit admission) of 48 (5.9 - 391.2) and 16.5 (2.5 - 108.6), respectively. Per-patient reimbursement-to-cost ratios increased during criteria-based dialysis periods (P1: 1.49, P2: 2.3, P3: 2.49). DISCUSSION: Strict adherence to criteria-based dialysis models increases biochemical abnormalities while improving Medicaid reimbursement for undocumented immigrants. Alternatives to emergent dialysis are required which minimize cost, while maintaining dignity, safety, and quality of life.

Drug–gene and drug–drug interactions associated with tramadol and codeine therapy in the INGENIOUS trial

Background: Tramadol and codeine are metabolized by CYP2D6 and are subject to drug-gene and drug-drug interactions. Methods: This interim analysis examined prescribing behavior and efficacy in 102 individuals prescribed tramadol or codeine while receiving pharmaco-genotyping as part of the INGENIOUS trial (NCT02297126). Results: Within 60 days of receiving tramadol or codeine, clinicians more frequently prescribed an alternative opioid in ultrarapid and poor metabolizers (odds ratio: 19.0; 95% CI: 2.8-160.4) as compared with normal or indeterminate metabolizers (p = 0.01). After adjusting the CYP2D6 activity score for drug-drug interactions, uncontrolled pain was reported more frequently in individuals with reduced CYP2D6 activity (odds ratio: 0.50; 95% CI: 0.25-0.94). Conclusion: Phenoconversion for drug-drug and drug-gene interactions is an important consideration in pharmacogenomic implementation; drug-drug interactions may obscure the potential benefits of genotyping

Implementation of a Renal Precision Medicine Program: Clinician Attitudes and Acceptance

A precision health initiative was implemented across a multi-hospital health system, wherein a panel of genetic variants was tested and utilized in the clinical care of chronic kidney disease (CKD) patients. Pharmacogenomic predictors of antihypertensive response and genomic predictors of CKD were provided to clinicians caring for nephrology patients. To assess clinician knowledge, attitudes, and willingness to act on genetic testing results, a Likert-scale survey was sent to and self-administered by these nephrology providers (N = 76). Most respondents agreed that utilizing pharmacogenomic-guided antihypertensive prescribing is valuable (4.0 ± 0.7 on a scale of 1 to 5, where 5 indicates strong agreement). However, the respondents also expressed reluctance to use genetic testing for CKD risk stratification due to a perceived lack of supporting evidence (3.2 ± 0.9). Exploratory sub-group analyses associated this reluctance with negative responses to both knowledge and attitude discipline questions, thus suggesting reduced exposure to and comfort with genetic information. Given the evolving nature of genomic implementation in clinical care, further education is warranted to help overcome these perception barriers

Interindividual Variability in Lymphocyte Stimulation and Transcriptomic Response Predicts Mycophenolic Acid Sensitivity in Healthy Volunteers

Mycophenolic acid (MPA) is an immunosuppressant commonly used to prevent renal transplant rejection and treat glomerulonephritis. MPA inhibits IMPDH2 within stimulated lymphocytes, reducing guanosine synthesis. Despite the widespread use of MPA, interindividual variability in response remains with rates of allograft rejection up to 15% and approximately half of individuals fail to achieve complete remission to lupus nephritis. We sought to identify contributors to interindividual variability in MPA response, hypothesizing that the HPRT1 salvage guanosine synthesis contributes to variability. MPA sensitivity was measured in 40 healthy individuals using an ex vivo lymphocyte viability assay. Measurement of candidate gene expression (n ± 40) and single‐cell RNA‐sequencing (n ± 6) in lymphocytes was performed at baseline, poststimulation, and post‐MPA treatment. After stimulation, HPRT1 expression was 2.1‐fold higher in resistant individuals compared with sensitive individuals (P ± 0.049). Knockdown of HPRT1 increased MPA sensitivity (12%; P ± 0.003), consistent with higher expression levels in resistant individuals. Sensitive individuals had higher IMPDH2 expression and 132% greater stimulation. In lymphocyte subpopulations, differentially expressed genes between sensitive and resistant individuals included KLF2 and LTB. Knockdown of KLF2 and LTB aligned with the predicted direction of effect on proliferation. In sensitive individuals, more frequent receptor‐ligand interactions were observed after stimulation (P ± 0.0004), but fewer interactions remained after MPA treatment (P ± 0.0014). These data identify a polygenic transcriptomic signature in lymphocyte subpopulations predictive of MPA response. The degree of lymphocyte stimulation, HPRT1, KLF2, and LTB expression may serve as markers of MPA efficacy

Lessons Learned When Introducing Pharmacogenomic Panel Testing into Clinical Practice

Objectives: Implementing new programs to support precision medicine in clinical settings is a complex endeavor. We describe challenges and potential solutions based on the Indiana GENomics Implementation: an Opportunity for the Underserved (INGenious) program at Eskenazi Health-one of six sites supported by the Implementing GeNomics In pracTicE network grant of the National Institutes of Health/National Human Genome Research Institute. INGenious is an implementation of a panel of genomic tests. Methods: We conducted a descriptive case study of the implementation of this pharmacogenomics program, which has a wide scope (14 genes, 27 medications) and a diverse population (patients who often have multiple chronic illnesses, in a large urban safety-net hospital and its outpatient clinics). Challenges: We placed the clinical pharmacogenomics implementation challenges into six categories: patient education and engagement in care decision making; clinician education and changes in standards of care; integration of technology into electronic health record systems; translational and implementation sciences in real-world clinical environments; regulatory and reimbursement considerations, and challenges in measuring outcomes. A cross-cutting theme was the need for careful attention to workflow. Our clinical setting, a safety-net health care system, presented some distinctive challenges. Patients often had multiple chronic illnesses and sometimes were taking more than one pharmacogenomics-relevant medication. Reaching patients for recruitment or follow-up was another challenge. Conclusions: New, large-scale endeavors in health care are challenging. A description of the challenges that we encountered and the approaches that we adopted to address them may provide insights for those who implement and study innovations in other health care systems

Pharmacogenomics of Hypertension in CKD: The CKD-PGX Study.

BACKGROUND: Patients with CKD often have uncontrolled hypertension despite polypharmacy. Pharmacogenomic drug-gene interactions (DGIs) may affect the metabolism or efficacy of antihypertensive agents. We report changes in hypertension control after providing a panel of 11 pharmacogenomic predictors of antihypertensive response. METHODS: A prospective cohort with CKD and hypertension was followed to assess feasibility of pharmacogenomic testing implementation, self-reported provider utilization, and BP control. The analysis population included 382 subjects with hypertension who were genotyped for cross-sectional assessment of DGIs, and 335 subjects followed for 1 year to assess systolic BP (SBP) and diastolic BP (DBP). RESULTS: Most participants (58%) with uncontrolled hypertension had a DGI reducing the efficacy of one or more antihypertensive agents. Subjects with a DGI had 1.85-fold (95% CI, 1.2- to 2.8-fold) higher odds of uncontrolled hypertension, as compared with those without a DGI, adjusted for race, health system (safety-net hospital versus other locations), and advanced CKD (eGFR <30 ml/min). CYP2C9-reduced metabolism genotypes were associated with losartan response and uncontrolled hypertension (odds ratio [OR], 5.2; 95% CI, 1.9 to 14.7). CYP2D6-intermediate or -poor metabolizers had less frequent uncontrolled hypertension compared with normal metabolizers taking metoprolol or carvedilol (OR, 0.55; 95% CI, 0.3 to 0.95). In 335 subjects completing 1-year follow-up, SBP (-4.0 mm Hg; 95% CI, 1.6 to 6.5 mm Hg) and DBP (-3.3 mm Hg; 95% CI, 2.0 to 4.6 mm Hg) were improved. No significant difference in SBP or DBP change were found between individuals with and without a DGI. CONCLUSIONS: There is a potential role for the addition of pharmacogenomic testing to optimize antihypertensive regimens in patients with CKD