No abstract

Single nucleotide polymorphisms in drug-metabolizing genes may affect tacrolimus pharmacokinetics. Here, we investigated the influence of genotypes of CYP3A5, CYP2C19, and POR on the concentration/dose (C/D) ratio of tacrolimus and episodes of acute graft-versus-host disease (GVHD) in Japanese recipients of allogeneic hematopoietic stem cell transplantation (HSCT). Thirty-six patients receiving the first HSCT using tacrolimus-based GVHD prophylaxis were enrolled with written informed consent. During continuous intravenous infusion, HSCT recipients carrying the CYP3A5*1 allele, particularly those with at least one POR*28 allele, had a significantly lower tacrolimus C/D ratio throughout all three post-HSCT weeks compared to that in recipients with POR*1/*1 (p < 0.05). The CYP3A5*3/*3 genotype and the concomitant use of voriconazole were independent predictors of an increased tacrolimus C/D ratio during the switch from continuous intravenous infusion to oral administration (p < 0.05). In recipients receiving concomitant administration of voriconazole, our results suggest an impact of not only CYP3A5 and CYP2C19 genotypes, but also plasma voriconazole concentration. Although switching from intravenous to oral administration at a ratio of 1:5 was seemingly appropriate in recipients with CYP3A5*1, a lower conversion ratio (1:2–3) was appropriate in recipients with CYP3A5*3/*3. Our results suggest that CYP3A5, POR, and CYP2C19 polymorphisms are useful biomarkers for individualized dosage adjustment of tacrolimus in HSCT recipients.

Background: Therapeutic drug monitoring of tacrolimus is necessary for appropriate dose adjustment for a successful immunosuppressive therapy. Several commercial immunoassays are available for tacrolimus measurements. This study aimed at simultaneously evaluating the analytical performances of 4 such immunoassays, using liquid chromatography-tandem mass spectrometry (LC-MS/MS) as a standard. For the first time, cross-reactivity to tacrolimus metabolites was assessed at concentrations frequently observed in clinical settings, as opposed to the higher concentrations tested by assay manufacturers. Methods: An affinity column-mediated immunoassay (ACMIA), using upgraded flex reagents; released in 2015, a chemiluminescence immunoassay (CLIA), an electrochemiluminescence immunoassay (ECLIA), and a latex agglutination turbidimetric immunoassay (LTIA) were evaluated using frozen whole blood samples collected from transplantation patients. Cross-reactivities to 3 major tacrolimus metabolites (13-O-demethyl-tacrolimus [M-I], 31-O-demethyl-tacrolimus [M-II], and 15-O-demethyl-tacrolimus [M-III]) were evaluated. Results: Each immunoassay correlated well with LC-MS/MS, and the Pearson's correlation coefficients (R) were 0.974, 0.977, 0.978, and 0.902 for ACMIA, CLIA, ECLIA, and LTIA, respectively. Using Bland–Altman difference plots to compare the immunoassays with LC-MS/MS, the calculated average biases were −6.73%, 6.07%, 7.46%, and 12.27% for ACMIA, CLIA, ECLIA, and LTIA, respectively. The cross-reactivities of ACMIA to the tacrolimus metabolites M-II and M-III were 81% and 78%, respectively, when blood was spiked at 2 ng/mL, and 94% and 68%, respectively, when it was spiked at 5 ng/mL. Conclusions: Each immunoassay was useful, but had its own characteristics. ACMIA cross-reactivities to M-II and M-III were much higher than the respective 18% and 15% reported on its package insert, suggesting that cross-reactivity should be examined at clinically relevant concentrations.

Disopyramide (DP) [4-diisopropylamino-2-phenyl-2-(2-pyridyl)butyramide] is a widely used antiarrhythmic drug with class Ia activity, according to the Vaughan and Williams classification.1,2 It has pharmacological effects on the heart that are qualitatively similar to those of quinidine and procainamide.3 Because of a relative narrow therapeutic range (2 -5 µg ml -1 ) in serum or plasma, the monitoring of DP in blood is essential.

Objective: Acute rejection after kidney transplant is a complicated clinical problem. Autophagy is the intracellular lysosomal degradation and recycling of proteins and organelles, and is reported to be involved in various diseases. Microtubule-associated protein light chain 3 (LC3) is a widely used marker to monitor autophagic activity. The involvement of autophagy in acute rejection after kidney transplantation remains unknown. This prospective study aimed to investigate the utility of urinary LC3 to predict acute rejection after kidney transplant. Methods: The study included 28 patients who underwent kidney transplantation between 2014 and 2016. All patients gave informed consent. Patients were divided in 2 groups, according to the biopsy diagnosis at 3 months after kidney transplantation. Three patients showed biopsy-proven T cell-mediated rejection (TCMR group), and 25 patients showed no signs of rejection (Control group). Urine samples were collected at 7, 28, 56, and 84 days after transplantation. Urinary LC3 was measured using an enzyme-linked immunosorbent assay (ELISA) kit. The present study was approved by the Kyushu University Hospital ethics committee. Results: Compared to the Control group, the TCMR group showed no significant renal dysfunction as measured by serum Cr and eGFR before kidney transplantation. There was no significant difference in the urinary LC3 concentration at 7 and 28 days, between the two groups. However, the urinary LC3 concentration in the TCMR group was twofold higher compared to that in the Control group at 56 and 84 days post transplantation (P < 0.05). Conclusion: Our small study suggests that urinary LC3 may be used as a novel biomarker of acute rejection in kidney transplant recipients.