Steroid-tacrolimus drug-drug interaction and the effect of CYP3A genotypes.

AIMS: Tacrolimus, metabolized by CYP3A4 and CYP3A5 enzymes, is susceptible to drug-drug interactions (DDI). Steroids induce CYP3A genes to increase tacrolimus clearance, but the effect is variable. We hypothesized that the extent of the steroid-tacrolimus DDI differs by CYP3A4/5 genotypes. METHODS: Kidney transplant recipients (n = 2462) were classified by the number of loss of function alleles (LOF) (CYP3A5*3, *6 and *7 and CYP3A4*22) and steroid use at each tacrolimus trough in the first 6 months post-transplant. A population pharmacokinetic analysis was performed by nonlinear mixed-effect modelling (NONMEM) and stepwise covariate modelling to define significant covariates affecting tacrolimus clearance. A stochastic simulation was performed and translated into a Shiny application with the mrgsolve and Shiny packages in R. RESULTS: Steroids were associated with modestly higher (3%-11.8%) tacrolimus clearance. Patients with 0-LOF alleles receiving steroids showed the greatest increase (11.8%) in clearance compared to no steroids, whereas those with 2-LOFs had a negligible increase (2.6%) in the presence of steroids. Steroid use increased tacrolimus clearance by 5% and 10.3% in patients with 1-LOF and 3/4-LOFs, respectively. CONCLUSIONS: Steroids increase the clearance of tacrolimus but vary slightly by CYP3A genotype. This is important in individuals of African ancestry who are more likely to carry no LOF alleles, may more commonly receive steroid treatment, and will need higher tacrolimus doses.

Limited Sampling Strategies Fail to Accurately Predict Mycophenolic Acid Area Under the Curve in Kidney Transplant Recipients and the Impact of Enterohepatic Recirculation.

BACKGROUND: Therapeutic drug monitoring for mycophenolic acid (MPA) is challenging due to difficulties in measuring the area under the curve (AUC). Limited sampling strategies (LSSs) have been developed for MPA therapeutic drug monitoring but come with risk of unacceptable performance. The authors hypothesized that the poor predictive performance of LSSs were due to the variability in MPA enterohepatic recirculation (EHR). This study is the first to evaluate LSSs models performance in the context of EHR. METHODS: Adult kidney transplant recipients (n = 84) receiving oral mycophenolate mofetil underwent intensive MPA pharmacokinetic sampling. MPA AUC0-12hr and EHR were determined. Published MPA LSSs in kidney transplant recipients receiving tacrolimus were evaluated for their predictive performance in estimating AUC0-12hr in our full cohort and separately in individuals with high and low EHR. RESULTS: None of the evaluated LSS models (n = 12) showed good precision or accuracy in predicting MPA AUC0-12hr in the full cohort. In the high EHR group, models with late timepoints had better accuracy but low precision, except for 1 model with late timepoints at 6 and 10 hours postdose, which had marginally acceptable precision. For all models, the good guess of predicted AUC0-12hr (±15% of observed AUC0-12hr) was highly variable (range, full cohort = 19%-61.9%; high EHR = 4.5%-65.9%; low EHR = 27.5%-62.5%). CONCLUSIONS: The predictive performance of the LSS models varied according to EHR status. Timepoints ≥5 hours postdose in LSS models are essential to capture EHR. Models and strategies that incorporate EHR during development are required to accurately ascertain MPA exposure.

Higher number of tacrolimus dose adjustments in kidney transplant recipients who are extensive and intermediate CYP3A5 metabolizers.

Kidney transplant recipients carrying the CYP3A5*1 allele have lower tacrolimus troughs, and higher dose requirements compared to those with the CYP3A5*3/*3 genotype. However, data on the effect of CYP3A5 alleles on post-transplant tacrolimus management are lacking. The effect of CYP3A5 metabolism phenotypes on the number of tacrolimus dose adjustments and troughs in the first 6 months post-transplant was evaluated in 78 recipients (64% Caucasians). Time to first therapeutic concentration, percentage of time in therapeutic range (TTR), and estimated glomerular filtration rate (eGFR) were also evaluated. Fifty-five kidney transplant recipients were CYP3A5 poor metabolizers (PM), 17 were intermediate metabolizers (IM), and 6 were extensive metabolizers (EM). Compared to PMs, EMs/IMs had significantly more dose adjustments (6.1 vs. 8.1, p = .015). Overall, 33.82% of trough measurements resulted in a dose change. There was no difference in the number of tacrolimus trough measurements between PMs and EM/IMs. The total daily tacrolimus dose requirements were higher in EMs and IMs compared to PMs (<.001). TTR was ∼50% in the PMs and EMs/IMs groups. CYP3A5 EM/IM metabolizers have more tacrolimus dose changes and higher dose requirements which increases clinical management complexity. Larger studies are needed to assess the cost and benefits of including genotyping data to improve clinical management.

Exploring Potential for a Personalized Medicine Approach to Smoking Cessation With an American Indian Tribe.

INTRODUCTION: A potential precision medicine approach to smoking cessation is tailoring pharmacotherapy to a biomarker known as the nicotine metabolite ratio (NMR). Little is known about the potential impact and acceptability of this approach for American Indian (AI) persons. AIMS AND METHODS: Tribal-academic collaboration was formed and during 2019-2020 AI adults who smoke(N = 54) were recruited to (1) examine correlations between NMR, dependence, and smoking exposure; (2) assess the extent to which pharmacotherapy preference aligned with NMR-informed recommendations; (3) explore acceptability of NMR-informed pharmacotherapy selection. Participants provided samples for assessment of salivary NMR and urinary total nicotine equivalents (TNE) and completed a questionnaire that assessed cigarettes per day (CPD), Fagerstrom Test for Cigarette Dependence (FTCD), pharmacotherapy preference, and perceptions of NMR-informed pharmacotherapy selection. RESULTS: Significant positive correlations were observed between NMR and FTCD (r = 0.29;p = .0383) and its abbreviated version Heaviness of Smoking Index (HIS) (r = 0.28;p =.0426). Post-hoc analyses suggest that relationships between dependence and NMR were driven by time to first cigarette. Nonsignificant, but directionally consistent, relationships were observed between NMR and CPD (r = 0.21; p =0.1436) and TNE (r = 0.24;p = .2906). Most participants preferred nicotine replacement therapy (71%) over varenicline (29%) and preference for pharmacotherapy matched NMR-based recommendations in 54% of participants. NMR-informed pharmacotherapy selection was supported by 62% of participants. CONCLUSION: In a sample of AI adults who smoke, NMR was related to cigarette dependence and about one-half of participants' pharmacotherapy preference matched their NMR-informed recommendation. There was lower acceptability of NMR-informed approach in this sample of AI adults than prior studies among white or black/African American people who smoke. IMPLICATIONS: Relationships between NMR, dependence, and self-preference for pharmacotherapy suggest that NMR-informed pharmacotherapy selection may have potential for enhancing smoking quitting success in this Tribe. Lower acceptability of NMR-informed pharmacotherapy in this Tribe suggests that this approach may not be equitably utilized. Future work could include identifying community-driven solutions to mitigate precision medicine concerns.

Opportunities for personalizing colorectal cancer care: an analysis of SEER-medicare data.

United States clinical practice guidelines for metastatic colorectal cancer recommend use of medications impacted by genetic variants but do not recommend testing. We analyzed real-world treatment using a cancer registry and claims dataset to explore pharmacogenomic (PGx) medication treatment patterns and characterize exposure. In a cohort of 6957 patients, most (86.9%) were exposed to at least one chemotherapy medication with PGx guidelines. In a cohort of 2223 patients with retail pharmacy claims available, most (79.2%) were treated with at least one non-chemotherapy (79.2%) medication with PGx guidelines. PGx-associated chemotherapy exposure was associated with age, race/ethnicity, educational attainment, and rurality. PGx-associated non-chemotherapy exposure was associated with medication use and comorbidities. The potential impact of PGx testing is large and policies aimed at increasing PGx testing at diagnosis may impact treatment decisions for patients with metastatic colorectal cancer as most patients are exposed to medications with pharmacogenomics implications during treatment.

CYP2C19 Phenotype and Body Weight-Guided Voriconazole Initial Dose in Infants and Children after Hematopoietic Cell Transplantation.

Prophylactic voriconazole use is recommended for children undergoing hematopoietic cell transplantation (HCT). Dosing considerations are essential, due to the narrow therapeutic window of voriconazole. Known covariates do not sufficiently explain the large interindividual pharmacokinetic (PK) variability of voriconazole. Moreover, knowledge of voriconazole PK for age <2 years is limited. We investigated genetic and clinical covariate associations with voriconazole interindividual PK variability and subsequently simulated dosing regimens in children. This study was conducted as part of a single-institution, phase I study of intravenous voriconazole therapy for children undergoing HCT. We conducted a population PK analysis and tested covariate effects on voriconazole PK, including 67 genetic variants and clinical variables. We analyzed plasma voriconazole and N-oxide metabolite concentrations from 58 children <21 years of age (including 12 children <2 years of age). A two-compartment parent mixed linear/nonlinear model best described our data. The CYP2C19 phenotype and body weight were significant covariates (P < 0.05 for both). Our model performance for age <2 years was comparable to that for other age groups. Simulation of the final model suggested the following doses to attain target steady-state trough concentrations of 1.5 to 5.0 mg/liter for the CYP2C19 normal phenotype: 16 mg/kg (weight of <15 kg), 12 mg/kg (weight of 15 to 30 kg), or 10 mg/kg (weight of >30 kg); doses were 33 to 50% lower for CYP2C19 poor/intermediate phenotypes and 25 to 50% higher for CYP2C19 rapid/ultrarapid phenotypes. We propose a new starting-dose regimen, combined with therapeutic drug monitoring, for intravenous voriconazole therapy in children of all ages. Future studies should validate this dosing regimen.

Early detection of SARS-CoV-2 and other infections in solid organ transplant recipients and household members using wearable devices.

The increasing global prevalence of SARS-CoV-2 and the resulting COVID-19 disease pandemic pose significant concerns for clinical management of solid organ transplant recipients (SOTR). Wearable devices that can measure physiologic changes in biometrics including heart rate, heart rate variability, body temperature, respiratory, activity (such as steps taken per day) and sleep patterns, and blood oxygen saturation show utility for the early detection of infection before clinical presentation of symptoms. Recent algorithms developed using preliminary wearable datasets show that SARS-CoV-2 is detectable before clinical symptoms in >80% of adults. Early detection of SARS-CoV-2, influenza, and other pathogens in SOTR, and their household members, could facilitate early interventions such as self-isolation and early clinical management of relevant infection(s). Ongoing studies testing the utility of wearable devices such as smartwatches for early detection of SARS-CoV-2 and other infections in the general population are reviewed here, along with the practical challenges to implementing these processes at scale in pediatric and adult SOTR, and their household members. The resources and logistics, including transplant-specific analyses pipelines to account for confounders such as polypharmacy and comorbidities, required in studies of pediatric and adult SOTR for the robust early detection of SARS-CoV-2, and other infections are also reviewed.

CYP51A1 polymorphism and voriconazole-associated hepatotoxicity in children undergoing hematopoietic cell transplant.

Fungal CYP51A (14α-sterol demethylase) is the target of an azole antifungal, voriconazole (VCZ), which also partially inhibits human CYP51A1. Hepatotoxicity is a common adverse effect of azoles, which is reported to be caused by altered gene expressions secondary to cholesterol synthesis inhibition by azoles. This is a post-hoc analysis of a previously conducted phase 1 dose-finding study of prophylactic VCZ in 56 pediatric hematopoietic cell transplant recipients. We explored an association between variants in human CYP51A1 (rs2282976 and rs6465348) and VCZ-induced hepatotoxicity. Genotype A/G or G/G in rs6465348 showed lower odds of hepatotoxicity after adjusting for VCZ area-under-the-curve (OR: 0.10, 95% CI: 0.01 - 0.79, vs. A/A).

Impact of Obesity on Voriconazole Pharmacokinetics among Pediatric Hematopoietic Cell Transplant Recipients.

Voriconazole (VCZ) is an antifungal agent with wide inter- and intrapatient pharmacokinetic (PK) variability and narrow therapeutic index. Although obesity was associated with higher VCZ trough concentrations in adults, the impact of obesity had yet to be studied in children. We characterized the PK of VCZ in obese patients by accounting for age and CYP2C19 phenotype. We conducted intensive PK studies of VCZ and VCZ N-oxide metabolite in 44 hematopoietic stem cell transplantation (HSCT) recipients aged 2 to 21 years who received prophylactic intravenous VCZ every 12 hours (q12h). Blood samples were collected at 5 and 30 minutes; at 1, 3, 6, and 9 hours after infusion completion; and immediately before the next infusion start. We estimated PK parameters with noncompartmental analysis and evaluated for an association with obesity by multiple linear regression analysis. The 44 participants included 9 (20%) with obesity. CYP2C19 metabolism phenotypes were identified as normal in 22 (50%), poor/intermediate in 13 (30%), and rapid/ultrarapid in 9 patients (21%). Obesity status significantly affects the VCZ minimum concentration of drug in serum (Cmin) (higher by 1.4 mg/liter; 95% confidence interval [CI], 0.0 to 2.8; P = 0.047) and VCZ metabolism ratio (VCZRATIO) (higher by 0.4; 95% CI, 0.0 to 0.7; P = 0.03), while no association was observed with VCZ area under the curve (AUC) (P = 0.09) after adjusting for clinical factors. A younger age and a CYP2C19 phenotype were associated with lower VCZ AUC. Obesity was associated with decreased metabolism of VCZ to its inactive N-oxide metabolite and, concurrently, increased VCZ Cmin, which is deemed clinically meaningful. Future research should aim to further characterize its effects and determine a proper dosing regimen for the obese.

Pharmacogenomics in kidney transplant recipients and potential for integration into practice.

WHAT IS KNOWN AND OBJECTIVE: Pharmacogenomic biomarkers are now used in many clinical care settings and represent one of the successes of precision medicine. Genetic variants are associated with pharmacokinetic and pharmacodynamic changes leading to medication adverse effects and changes in clinical response. Actionable pharmacogenomic variants are common in transplant recipients and have implications for medications used in transplant, but yet are not broadly incorporated into practice. METHODS: From the Clinical Pharmacogenetics Implementation Consortium and Dutch Pharmacogenetics Working Group guidelines, and PharmGKB databases, 12 pharmacogenomic genes with 30 variants were selected and used to create diplotypes and actionable pharmacogenomic phenotypes. A total of 853 kidney allograft recipients who had genomic information available from a genome-wide association study were included. RESULTS: Each recipient had at least one actionable pharmacogenomic diplotype/phenotype, whereas the majority (58%) had three or four actionable diplotypes/phenotypes and 17.4% had five or more among the 12 genes. The participants carried actionable diplotypes/phenotypes for multiple medications, including tacrolimus, azathioprine, clopidogrel, warfarin, simvastatin, voriconazole, antidepressants and proton-pump inhibitors. WHAT IS NEW AND CONCLUSION: Pharmacogenomic variants are common in transplant recipients, and transplant recipients receive medications that have actionable variants. CLINICAL TRIAL: Genomics of Transplantation, clinicaltrials.gov (NCT01714440).

Tacrolimus troughs and genetic determinants of metabolism in kidney transplant recipients: A comparison of four ancestry groups.

Tacrolimus trough and dose requirements vary dramatically between individuals of European and African American ancestry. These differences are less well described in other populations. We conducted an observational, prospective, multicenter study from which 2595 kidney transplant recipients of European, African, Native American, and Asian ancestry were studied for tacrolimus trough, doses, and genetic determinants of metabolism. We studied the well-known variants and conducted a CYP3A4/5 gene-wide analysis to identify new variants. Daily doses, and dose-normalized troughs were significantly different between the four groups (P < .001). CYP3A5*3 (rs776746) was associated with higher dose-normalized tacrolimus troughs in all groups but occurred at different allele frequencies and had differing effect sizes. The CYP3A5*6 (rs10264272) and *7 (rs413003343) variants were only present in African Americans. CYP3A4*22 (rs35599367) was not found in any of the Asian ancestry samples. We identified seven suggestive variants in the CYP3A4/5 genes associated with dose-normalized troughs in Native Americans (P = 1.1 × 10-5 -8.8 × 10-6 ) and one suggestive variant in Asian Americans (P = 5.6 × 10-6 ). Tacrolimus daily doses and dose-normalized troughs vary significantly among different ancestry groups. We identified potential new variants important in Asians and Native Americans. Studies with larger populations should be conducted to assess the importance of the identified suggestive variants.

The impact of donor and recipient common clinical and genetic variation on estimated glomerular filtration rate in a European renal transplant population.

Genetic variation across the human leukocyte antigen loci is known to influence renal-transplant outcome. However, the impact of genetic variation beyond the human leukocyte antigen loci is less clear. We tested the association of common genetic variation and clinical characteristics, from both the donor and recipient, with posttransplant eGFR at different time-points, out to 5 years posttransplantation. We conducted GWAS meta-analyses across 10 844 donors and recipients from five European ancestry cohorts. We also analyzed the impact of polygenic risk scores (PRS), calculated using genetic variants associated with nontransplant eGFR, on posttransplant eGFR. PRS calculated using the recipient genotype alone, as well as combined donor and recipient genotypes were significantly associated with eGFR at 1-year posttransplant. Thirty-two percent of the variability in eGFR at 1-year posttransplant was explained by our model containing clinical covariates (including weights for death/graft-failure), principal components and combined donor-recipient PRS, with 0.3% contributed by the PRS. No individual genetic variant was significantly associated with eGFR posttransplant in the GWAS. This is the first study to examine PRS, composed of variants that impact kidney function in the general population, in a posttransplant context. Despite PRS being a significant predictor of eGFR posttransplant, the effect size of common genetic factors is limited compared to clinical variables.

Identification of genetic variants associated with tacrolimus metabolism in kidney transplant recipients by extreme phenotype sampling and next generation sequencing.

An extreme phenotype sampling (EPS) model with targeted next-generation sequencing (NGS) identified genetic variants associated with tacrolimus (Tac) metabolism in subjects from the Deterioration of Kidney Allograft Function (DeKAF) Genomics cohort which included 1,442 European Americans (EA) and 345 African Americans (AA). This study included 48 subjects separated into 4 groups of 12 (AA high, AA low, EA high, EA low). Groups were selected by the extreme phenotype of dose-normalized Tac trough concentrations after adjusting for common genetic variants and clinical factors. NGS spanned > 3 Mb of 28 genes and identified 18,661 genetic variants (3961 previously unknown). A group of 125 deleterious variants, by SIFT analysis, were associated with Tac troughs in EAs (burden test, p = 0.008), CYB5R2 was associated with Tac troughs in AAs (SKAT, p = 0.00079). In CYB5R2, rs61733057 (increased allele frequency in AAs) was predicted to disrupt protein function by SIFT and PolyPhen2 analysis. The variants merit further validation.

NPHP1 (Nephrocystin-1) Gene Deletions Cause Adult-Onset ESRD.

Background Nephronophthisis (NPH) is the most prevalent genetic cause for ESRD in children. However, little is known about the prevalence of NPH in adult-onset ESRD. Homozygous full gene deletions of the NPHP1 gene encoding nephrocystin-1 are a prominent cause of NPH. We determined the prevalence of NPH in adults by assessing homozygous NPHP1 full gene deletions in adult-onset ESRD.Methods Adult renal transplant recipients from five cohorts of the International Genetics and Translational Research in Transplantation Network (iGeneTRAiN) underwent single-nucleotide polymorphism genotyping. After quality control, we determined autosomal copy number variants (such as deletions) on the basis of median log2 ratios and B-allele frequency patterns. The findings were independently validated in one cohort. Patients were included in the analysis if they had adult-onset ESRD, defined as start of RRT at ≥18 years old.Results We included 5606 patients with adult-onset ESRD; 26 (0.5%) showed homozygous NPHP1 deletions. No donor controls showed homozygosity for this deletion. Median age at ESRD onset was 30 (range, 18-61) years old for patients with NPH, with 54% of patients age ≥30 years old. Notably, only three (12%) patients were phenotypically classified as having NPH, whereas most patients were defined as having CKD with unknown etiology (n=11; 42%).Conclusions Considering that other mutation types in NPHP1 or mutations in other NPH-causing genes were not analyzed, NPH is a relatively frequent monogenic cause of adult-onset ESRD. Because 88% of patients had not been clinically diagnosed with NPH, wider application of genetic testing in adult-onset ESRD may be warranted.

Tacrolimus trough and dose intra-patient variability and CYP3A5 genotype: Effects on acute rejection and graft failure in European American and African American kidney transplant recipients.

BACKGROUND: Suboptimal immunosuppression after kidney transplantation contributes to toxicity and loss of efficacy. Little is known regarding the impact of intra-patient variability of tacrolimus (TAC) doses and troughs in the early post-transplant period or the influence of genetic variants on variability. METHODS: Coefficients of variation (CV) of TAC troughs and doses of 1226 European American (EA) and 246 African American (AA) adult recipients enrolled in DeKAF Genomics were compared for association with acute rejection and graft failure. Additionally, the influence of recipients' number of CYP3A5 loss-of-function alleles was assessed. RESULTS: Acute rejection was associated with greater CV of dose in AA (P < 0.001) and EA recipients (P = 0.012). Graft failure was associated with a greater CV of dose (P = 0.022) and trough (P < 0.001) in AA, and higher CV of trough (P = 0.024) in EA recipients. In EA, CYP3A5 loss-of-function alleles were associated with decreased CV of trough (P = 0.0042) and increased CV of dose (P < 0.0001). CONCLUSION: CYP3A5 loss-of-function alleles influence intra-patient TAC trough and dose variability. High variability of TAC dose increases risk of acute rejection. High variability of TAC trough increases risk of graft failure. Early clinical recognition of TAC dose and trough variability may improve patient management and outcomes.

Urinary microbiome associated with chronic allograft dysfunction in kidney transplant recipients.

BACKGROUND: We performed a study to identify differences in the urinary microbiome associated with chronic allograft dysfunction (CAD) and compared the urinary microbiome of male and female transplant recipients with CAD. METHODS: This case-control study enrolled 67 patients within the Deterioration of Kidney Allograft Function (DeKAF) Genomics cohort at two transplant centers. CAD was defined as a greater than 25% rise in serum creatinine relative to a 3 month post-transplant baseline. Urine samples from patients with and without CAD were analyzed using 16S V4 bacterial ribosomal DNA sequences. RESULTS: Corynebacterium was more prevalent in female and male patients with CAD compared to non-CAD female patients (P = 0.0005). A total 21 distinct Operational Taxonomic Unit (OTUs) were identified as significantly different when comparing CAD and non-CAD patients using Kruskal-Wallis (P < 0.01). A subset analysis of female patients with CAD compared to non-CAD females identified similar differentially abundant OTUs, including the genera Corynebacterium and Staphylococcus (Kruskal-Wallis; P = 0.01; P = 0.004, respectively). Male CAD vs female CAD analysis showed greater abundance of phylum Proteobacteria in males. CONCLUSION: There were differences in the urinary microbiome when comparing female and male CAD patients with their female non-CAD counterparts and these differences persisted in the subset analysis limited to female patients only.

Genetics of acute rejection after kidney transplantation.

Treatment of acute rejection (AR) following kidney transplantation has improved in recent years, but there are still limitations to successful outcomes. This review article covers literature in regard to recipient and donor genetics of AR kidney and secondarily of liver allografts. Many candidate gene and some genome-wide association studies (GWASs) have been conducted for AR in kidney transplantation. Genetic associations with AR in kidney and liver are mostly weak, and in most cases, the associations have not been reproducible. A limitation in the study of AR is the lack of sufficiently large populations that account for population stratification to study the AR phenotype which in this era occurs in <10% of transplants. Furthermore, the AR phenotype has been difficult to define and the definitions of classifications have evolved over time. Literature related to the pharmacogenomics of tacrolimus is robust and has been validated in many studies. Associations between gene expression and AR are emerging as markers of outcomes and AR classification. In the future, combinations of pretransplant genotype for AR risk prediction, genotype-based immune suppressant dosing, and pharmacogenomic markers to select AR maintenance or treatment and expression markers from biopsies may provide valuable clinical tools for guiding treatment.

CRISPR/Cas9 Genetic Modification of CYP3A5 *3 in HuH-7 Human Hepatocyte Cell Line Leads to Cell Lines with Increased Midazolam and Tacrolimus Metabolism.

Clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 engineering of the CYP3A5 *3 locus (rs776746) in human liver cell line HuH-7 (CYP3A5 *3/*3) has led to three CYP3A5 *1 cell lines by deletion of the exon 3B splice junction or point mutation. Cell lines CYP3A5 *1/*3 sd (single deletion), CYP3A5 *1/*1 dd (double deletion), or CYP3A5 *1/*3 pm (point mutation) expressed the CYP3A5 *1 mRNA and had elevated CYP3A5 mRNA (P < 0.0005 for all engineered cell lines) and protein expression compared with HuH-7. In metabolism assays, HuH-7 had less tacrolimus (all P < 0.05) or midazolam (MDZ) (all P < 0.005) disappearance than all engineered cell lines. HuH-7 had less 1-OH MDZ (all P < 0.0005) or 4-OH (all P < 0.005) production in metabolism assays than all bioengineered cell lines. We confirmed CYP3A5 metabolic activity with the CYP3A4 selective inhibitor CYP3CIDE. This is the first report of genomic CYP3A5 bioengineering in human cell lines with drug metabolism analysis.

Rifampin-sirolimus-voriconazole interaction in a hematopoietic cell transplant recipient.

Purpose Patients undergoing hematopoietic cell transplantation are treated with multiple medications, potentially complicated by drug-drug interactions. Drug interactions with sirolimus, voriconazole, and rifampin are particularly difficult because of the complex and simultaneous enzyme inhibition and induction mechanisms. We report a hematopoietic cell transplantation patient receiving sirolimus and voriconazole who was given rifampin while being treated for presumed methicillin-resistant Staphylococcus aureus meningitis. Summary A 31 year-old female received a nonmyeloablative allogeneic umbilical cord hematopoietic cell transplantation for myelodysplastic syndrome transformed to acute myeloid leukemia (AML). Her graft versus host disease and antifungal prophylaxis included sirolimus and voriconazole, respectively. Therapeutic drug monitoring prior to admission revealed a stable outpatient sirolimus regimen of 0.4 mg orally daily (trough goal 3-12 mcg/L). She was admitted to the inpatient hematopoietic cell transplantation service and diagnosed with methicillin-resistant Staphylococcus aureus bacteremia and presumed bacterial meningitis 217 days after transplant. Intravenous rifampin and vancomycin were initiated and voriconazole was changed to micafungin. Sirolimus trough concentrations were undetectable two days after starting rifampin. Therapeutic sirolimus concentrations were achieved four days later, at a sirolimus dose of 16-18 mg orally daily. Rifampin was discontinued after nine days and the sirolimus dose was adjusted accordingly, maintaining therapeutic levels throughout follow-up. The patient suffered a flare of chronic skin graft versus host disease requiring etanercept, high-dose systemic steroids, and topical steroids. Conclusion To the best of our knowledge, this is the first report describing the management of sirolimus during the transition from voriconazole inhibition to rifampin induction. Clinicians should be aware of potential drug-drug interactions.

Sirolimus and Mycophenolate Mofetil as Calcineurin Inhibitor-Free Graft-versus-Host Disease Prophylaxis for Reduced-Intensity Conditioning Umbilical Cord Blood Transplantation.

The use of calcineurin inhibitors (CNIs) to reduce the risk of graft-versus-host disease (GVHD) after hematopoietic cell transplantation (HCT) requires intensive post-transplantation toxicity monitoring. Sirolimus-based GVHD prophylaxis is associated with a favorable toxicity profile and requires less intensive monitoring. However, the efficacy of sirolimus-based regimen compared with CNI-based regimen has not been evaluated in the setting of reduced-intensity conditioning (RIC) double umbilical cord blood (UCB) HCT. We compared outcomes of patients receiving sirolimus/mycophenolate mofetil (MMF) (n = 37) or cyclosporine (CSA)/MMF (n = 123) in an ongoing phase II study of RIC UCB transplantation. In multiple regression analysis, sirolimus/MMF did not influence the risk of grades II to IV or grades III and IV acute GVHD. In addition, there was no association between type of GVHD prophylaxis and hematopoietic engraftment. Infection density analysis found a significantly lower risk of infections with sirolimus/MMF between days +46 and +180 after HCT compared with CSA/MMF (3.4 versus 6.3 per 1000 patient-days, P = .03); however, no difference was observed before day +45. Sirolimus/MMF use resulted in no thrombotic microangiopathy, fewer instances of elevated serum creatinine >2 mg/dL (14% versus 45%; P <.01), and similar rates of sinusoidal obstruction syndrome (2.7% versus 4%; P = .68), compared with CSA/MMF. Disease-free survival at 1 year was 51% for sirolimus/MMF and 41% for CSA/MMF (P = .41), and sirolimus/MMF use did not influence the risk of nonrelapse mortality or survival. In conclusion, sirolimus/MMF GVHD prophylaxis was better tolerated and resulted in similar rates of GVHD and survival as compared to CSA/MMF after RIC double UCB transplantation.