Beyond Single Nucleotide Polymorphisms: CYP3A5∗3 ∗6 ∗7 Composite and ABCB1 Haplotype Associations to Tacrolimus Pharmacokinetics in Black and White Renal Transplant Recipients

Interpatient variability in tacrolimus pharmacokinetics is attributed to metabolism by cytochrome P-450 3A5 (CYP3A5) isoenzymes and membrane transport by P-glycoprotein. Interpatient pharmacokinetic variability has been associated with genotypic variants for both CYP3A5 or ABCB1. Tacrolimus pharmacokinetics was investigated in 65 stable Black and Caucasian post-renal transplant patients by assessing the effects of multiple alleles in both CYP3A5 and ABCB1. A metabolic composite based upon the CYP3A5 polymorphisms: ∗3(rs776746), ∗6(10264272), and ∗7(41303343), each independently responsible for loss of protein expression was used to classify patients as extensive, intermediate and poor metabolizers. In addition, the role of ABCB1 on tacrolimus pharmacokinetics was assessed using haplotype analysis encompassing the single nucleotide polymorphisms: 1236C \u3e T (rs1128503), 2677G \u3e T/A(rs2032582), and 3435C \u3e T(rs1045642). Finally, a combined analysis using both CYP3A5 and ABCB1 polymorphisms was developed to assess their inter-related influence on tacrolimus pharmacokinetics. Extensive metabolizers identified as homozygous wild type at all three CYP3A5 loci were found in 7 Blacks and required twice the tacrolimus dose (5.6 ± 1.6 mg) compared to Poor metabolizers [2.5 ± 1.1 mg (P \u3c 0.001)]; who were primarily Whites. These extensive metabolizers had 2-fold faster clearance (P \u3c 0.001) with 50% lower AUC∗ (P \u3c 0.001) than Poor metabolizers. No differences in C12 h were found due to therapeutic drug monitoring. The majority of blacks (81%) were classified as either Extensive or Intermediate Metabolizers requiring higher tacrolimus doses to accommodate the more rapid clearance. Blacks who were homozygous for one or more loss of function SNPS were associated with lower tacrolimus doses and slower clearance. These values are comparable to Whites, 82% of who were in the Poor metabolic composite group. The ABCB1 haplotype analysis detected significant associations of the wildtype 1236T-2677T-3435T haplotype to tacrolimus dose (P = 0.03), CL (P = 0.023), CL/LBW (P = 0.022), and AUC∗ (P = 0.078). Finally, analysis combining CYP3A5 and ABCB1 genotypes indicated that the presence of the ABCB1 3435 T allele significantly reduced tacrolimus clearance for all three CPY3A5 metabolic composite groups. Genotypic associations of tacrolimus pharmacokinetics can be improved by using the novel composite CYP3A5∗3∗4∗5 and ABCB1 haplotypes. Consideration of multiple alleles using CYP3A5 metabolic composites and drug transporter ABCB1 haplotypes provides a more comprehensive appraisal of genetic factors contributing to interpatient variability in tacrolimus pharmacokinetics among Whites and Blacks

Race and sex associations with tacrolimus pharmacokinetics in stable kidney transplant recipients

Study Objective: This study investigated race and sex differences in tacrolimus pharmacokinetics and pharmacodynamics in stable kidney transplant recipients. Design and Setting: A cross-sectional, open-label, single center, 12-h pharmacokinetic-pharmacodynamic study was conducted. Tacrolimus pharmacokinetic parameters included area under the concentration-time curve (AUC0–12), AUC0–4, 12-h troughs (C12 h), maximum concentrations (Cmax), oral clearance (Cl), with dose-normalized AUC0–12, troughs, and Cmax with standardized adverse effect scores. Statistical models were used to analyze end points with individual covariate-adjustment including clinical factors, genotypic variants CYP3A5*3, CYP3A5*6, CYP3A5*7(CYP3A5*3*6*7) metabolic composite, and ATP binding cassette gene subfamily B member 1 (ABCB1) polymorphisms. Patients: 65 stable, female and male, Black and White kidney transplant recipients receiving tacrolimus and mycophenolic acid ≥6 months post-transplant were evaluated. Measurements and Main Results: Black recipients exhibited higher tacrolimus AUC0–12 (Race: p = 0.005), lower AUC* (Race: p \u3c 0.001; Race × Sex: p = 0.068), and higher Cl (Race: p \u3c 0.001; Sex: p = 0.066). Greater cumulative (Sex: p \u3c 0.001; Race × Sex: p = 0.014), neurologic (Sex: p = 0.021; Race × Sex: p = 0.005), and aesthetic (Sex: p = 0.002) adverse effects were found in females, with highest scores in Black women. In 84.8% of Black and 68.8% of White patients, the target AUC0–12 was achieved (p = 0.027). In 31.3% of White and 9.1% of Black recipients, AUC0–12 was \u3c100 \u3eng‧h/ml despite tacrolimus troughs in the target range (p = 0.027). The novel CYP3A5*3*6*7 metabolic composite was the significant covariate accounting for 15%–19% of tacrolimus variability in dose (p = 0.002); AUC0–12 h* (p \u3c 0.001), and Cl (p \u3c 0.001). Conclusions: Tacrolimus pharmacokinetics and adverse effects were different among stable kidney transplant recipient groups based upon race and sex with interpatient variability associated with the CYP3A5*3*6*7 metabolic composite. More cumulative, neurologic, and aesthetic adverse effects were noted among females. Tacrolimus regimens that consider race and sex may reduce adverse effects and enhance allograft outcomes by facilitating more patients to achieve the targeted AUC0–12 h

Inhibition of Dihydrotestosterone Synthesis in Prostate Cancer by Combined Frontdoor and Backdoor Pathway Blockade

Androgen deprivation therapy (ADT) is palliative and prostate cancer (CaP) recurs as lethal castration-recurrent/resistant CaP (CRPC). One mechanism that provides CaP resistance to ADT is primary backdoor androgen metabolism, which uses up to four 3α-oxidoreductases to convert 5α-androstane-3α,17β-diol (DIOL) to dihydrotestosterone (DHT). The goal was to determine whether inhibition of 3α-oxidoreductase activity decreased conversion of DIOL to DHT. Protein sequence analysis showed that the four 3α-oxidoreductases have identical catalytic amino acid residues. Mass spectrometry data showed combined treatment using catalytically inactive 3α-oxidoreductase mutants and the 5α-reductase inhibitor, dutasteride, decreased DHT levels in CaP cells better than dutasteride alone. Combined blockade of frontdoor and backdoor pathways of DHT synthesis provides a therapeutic strategy to inhibit CRPC development and growth

A contemporary analysis of morbidity and outcomes in cytoreduction/hyperthermic intraperitoneal chemoperfusion

The risks and benefits of cytoreductive surgery combined with hyperthermic intraperitoneal chemotherapy ( CS / HIPEC ) continue to be debated by the oncology community. A retrospective analysis of contemporary data (2003–2011) was performed to provide objective information regarding surgical morbidity, mortality, and survival for patients undergoing CS / HIPEC at a comprehensive cancer center. While procedure‐associated morbidity was comparable to other major surgical oncology procedures, there was no operative or 30‐day mortality and 60‐day mortality was 2.7%. Increasing numbers of bowel resections were found to correlate to an increased incidence of deep surgical site infections (including abscess and enterocutaneous fistula) and need for reoperation which was in turn associated with a decreased overall survival ( OS ) and progression‐free survival ( PFS ). Five‐year OS rates varied by site of tumor origin and histology (disseminated peritoneal adenomucinosis [91.3%], Mesothelioma [80.8%], Appendiceal Adenocarcinoma [38.7%], and Colorectal Adenocarcinoma [38.2%]). With an acceptable morbidity and mortality rate, CS / HIPEC should be included as an effective treatment modality in the multidisciplinary care of select patients with peritoneal metastases. In the contemporary setting, cytoreductive surgery and hyperthermic intraperitoneal chemotherapy ( CS / HIPEC ) are associated with a low mortality and improved survival. When present, complications are associated with a decreased overall survival. This treatment modality should be considered within the context of multidisciplinary care for select peritoneal carcinomatosis patients.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98274/1/cam480.pd