Boyoon Choi

ABCB1 C3435T Genetic Polymorphism on Population Pharmacokinetics of Methotrexate After Hematopoietic Stem Cell Transplantation in Korean Patients: A Prospective Analysis

BACKGROUND Methotrexate (MTX) is often used to prevent graft-versus-host disease (GVHD) after allogeneic hematopoietic stem cell transplantation (HSCT). However, MTX has great pharmacokinetic variability and its use can result in fatal complications and/or infections after HSCT. OBJECTIVES The purposes of this study were to build a population pharmacokinetic model of MTX treatment in Korean patients who have undergone HSCT and to identify covariates, including genetic polymorphisms, that affect the pharmacokinetic properties of MTX. METHODS Clinical characteristics and MTX concentration data for 20 post-HSCT patients were collected. For each patient, ABCB1, ABCC2, ATIC, GGH, MTHFR, and TYMS genotyping was performed. Population pharmacokinetic analysis was performed using the NONMEM program. Analysis of MTX pharmacokinetic properties was accomplished using a 2-compartment pharmacokinetic model that incorporated first-order conditional estimation methods with interaction. The effects of a variety of demographic and genetic factors on MTX disposition were investigated. RESULTS The study population consisted of 12 men (60%) and 8 women (40%). Median age and body weight were 28 years (range, 18-49 years) and 55.6 kg (range, 44.8-80.8 kg), respectively. Within the study population, the estimated mean MTX clearance (CL) was 7.08 L/h, whereas the mean central compartment volume (V(1)) of MTX distribution was 19.4 L. MTX CL was significantly affected by glomerular filtration rate (GFR), penicillin use, and the ABCB1 3435 genotype. Interindividual variabilities for CL and V(1) were 21.6% and 73.3%. A 10-mL/min GFR increase was associated with a 32% increase in mean MTX CL, whereas penicillin use was associated with a decrease in MTX CL of 61%. MTX CL was significantly greater (by ∼21%) in patients with the ABCB1 3435 CC and CT genotype than in those with the ABCB1 3435 TT genotype (P < 0.001). CONCLUSIONS There was great interindividual variation in MTX pharmacokinetic properties in patients who had undergone HSCT. GFR, concurrent penicillin use, and the presence of the ABCB1 3435 C

CYP3A5 Polymorphism Effect on Cyclosporine Pharmacokinetics in Living Donor Renal Transplant Recipients: Analysis by Population Pharmacokinetics

BACKGROUND: Cyclosporine is often used to prevent allograft rejection in renal transplant recipients. However, cyclosporine has a narrow therapeutic window and large variability in its pharmacokinetics. Individual characteristics and genetic polymorphisms can cause the variation. Hence, it is important to determine the cause(s) of the variation in cyclosporine pharmacokinetics. To our knowledge, this is the first reported population pharmacokinetic study of cyclosporine in living donor renal transplant recipients that considered the genetic polymorphism as a covariate. OBJECTIVE: To build a population pharmacokinetic model of cyclosporine in living donor renal transplant recipients and identify covariates including CYP3A5*3, ABCB1 genetic polymorphisms that affect cyclosporine pharmacokinetic parameters. METHODS: Clinical characteristics and cyclosporine concentration data for 69 patients who received cyclosporine-based immunosuppressive therapy after living donor renal transplantation were collected retrospectively for up to 400 postoperative days. CYP3A5*1/*3 and ABCB1 C1236T, G2677T/A, C3435T genotyping was performed. A population pharmacokinetic analysis was conducted using a NONMEM program. After building the final model, 1000 bootstrappings were performed to validate the final model. RESULTS: In total, 2034 blood samples were collected. A 1-compartment open model with first-order absorption and elimination was chosen to describe the pharmacokinetics of cyclosporine. A population pharmacokinetic analysis showed that postoperative days, sex, and CYP3A5 genotype significantly affected the pharmacokinetics of cyclosporine. The final estimate of mean clearance was 56 L/h, and the mean volume of distribution was 4650 L. The interindividual variability for these parameters was 22.98% and 51.48%, respectively. CONCLUSIONS: Using the present model to calculate the dose of cyclosporine with CYP3A5 genotyping can be possible for the patients whose cyclosporine concentration is not within the therapeutic range even with therapeutic drug monitoring.

Population pharmacokinetics and pharmacodynamics of busulfan with GSTA1 polymorphisms in patients undergoing allogeneic hematopoietic stem cell transplantation.

AIM A population pharmacokinetic (PPK) analysis was conducted to describe the influence of GSTA1 polymorphisms on intravenous busulfan in adults undergoing allogeneic hematopoietic stem cell transplantation. PATIENTS & METHODS A PPK model was developed from 36 patients by a one-compartment model with first-order elimination. RESULTS The typical value of clearance and volume of distribution were 11.0 l/h and 42.4 l, respectively. Clearance decreased by 15% and area under the concentration-time curves (AUCs) increased with GSTA1 variants compared with wild-type (both p < 0.05). Subtherapeutic AUCs were seen only in wild-type patients. CONCLUSION To our knowledge, this is the first PPK study to suggest that GSTA1 polymorphisms in adults are associated with busulfan PK.

A meta-analysis of the effects of interleukin-6 -174 G>C genetic polymorphism on acute graft-versus-host disease susceptibility.

BACKGROUND The interleukin-6 (IL-6) -174 G>C genetic polymorphism has been implicated to play an important role in acute graft-versus-host disease (aGVHD). However, previous studies have yielded inconclusive results as to its role in patient susceptibility to aGVHD, and no study to date has systematically analyzed this polymorphism. OBJECTIVE A meta-analysis of the published evidence was conducted to estimate the true effect of the IL-6 -174 G>C genetic polymorphism in allogeneic hematopoietic stem cell transplantation (alloHSCT) patients and donors on the risk of aGVHD. METHODS Seven cohort studies, comprising 1287 recipient and donor pairs, were included after eliminating 62 studies that met the following exclusion criteria: irrelevant studies other than cohort studies, without sufficient data, and with overlapping data. Although interstudy heterogeneity existed, most studies were conducted in the United States or Europe and included adult patients with hematologic disease who received alloHSCT from human leukocyte antigen-matched or identical sibling donors. The effect of the polymorphism on aGVHD risk (grades I-IV, II-IV, and III-IV) was estimated from odds ratios with 95% confidence intervals for the dominant genetic model and recessive model, respectively. RESULTS Patients who received grafts from donors with the IL-6 G allele experienced more frequent grade I-IV aGVHD (odds ratio = 3.304 [95% confidence interval, 1.456-7.494]) and grade II-IV aGVHD (odds ratio = 1.738 [95% CI, 1.006 - 3.001]). CONCLUSIONS To our knowledge, this is the first meta-analysis to evaluate the relation between a non-human leukocyte antigen gene polymorphism and the risk of aGVHD. Our meta-analysis combined the results of several studies and demonstrated that the donor IL-6 G allele is associated with an increased risk of grades I-IV and II-IV aGVHD.

Population Pharmacokinetics of Cyclosporine in Hematopoietic Stem Cell Transplant Patients Consideration of Genetic Polymorphisms

Background: Cyclosporine (CsA), which is used for graft-versus-host disease prophylaxis in allogeneic hematopoietic stem cell transplant (allo-HSCT), has a narrow therapeutic range and large interindividual and intraindividual pharmacokinetic variability. Nevertheless, population pharmacokinetic (PopPK) studies of CsA in allo-HSCT are scarce. Objective: The goal of our study was to build a PopPK model of CsA in allo-HSCT in consideration of demographic, clinical, and genetic polymorphisms data. Methods: A total of 34 adult allo-HSCT patients who received CsA were enrolled prospectively. Demographic, clinical, and CYP3A5 *1/*3, CYP2C19 *1/*2/*3, ABCB1 3435C>T, 1236C>T, 2677G>T/A, ABCC2 -24C>T, 1249G>A, VDR Bsml, Apal polymorphisms data were collected. A PopPK modeling was conducted with NONMEM program. Results: A 1-compartment model with a 2-transit absorption compartment model was developed. After the stepwise covariate model building process, weight was incorporated into clearance (CL) as a power function model with the exponent value of 0.419. The final typical estimate of CL was 21.2 L/h; volume of distribution was 430 L; logit-transformed bioavailability was 1.49 (bioavailability: 81%); and transit compartment rate was 2.87/h. None of the genetic polymorphisms in CYP3A5, CYP2C19, ABCB1, ABCC2, and VDR were significant covariates in the pharmacokinetics of CsA. Conclusions: In our study, it was observed that weight had a significant effect on CL. Genetic polymorphisms did not affect CsA pharmacokinetics. Prospective studies with a larger number of participants is needed to validate the results of this study.

Strategic Priorities to Improve Effectiveness of Anti-smoking Interventions for the Korean Military: An Application of the Analytic Hierarchy Process

Introduction As South Korea remains technically at war with the North, higher smoking prevalence in the military might adversely affect the South Koreas military power and contribute to lifetime smoking in men with mandatory military service. This study was to identify priorities among the anti-smoking strategies to improve the existing smoking cessation programs for the Korean military. Methods The analytic hierarchy process model with a goal, decision criteria, and sub-criteria as well as candidate strategies, was developed following a literature search and expert group discussion. A survey for pairwise comparison was conducted to determine the priority of the (sub-)criteria and strategies by 14 experts. The Super-Decisions software was used to determine the priorities and to analyze their consistency ratios and sensitivities. The study was approved by the ethics committee of the Korea Ministry of Health and Welfare. Results Eight candidate strategies were developed to improve the effectiveness of military anti-smoking interventions as follows: (1) development of outcome enhancement plans for smoking cessation programs for the military, (2) development of differentiated smoking cessation programs for specific groups, (3) building of community network for continuity and accessibility of anti-smoking project, (4) building of industry-academia-government networks for anti-smoking project, (5) improvement of the perception of and strengthen the reward for smoking cessation, (6) development of a training system for army clinicians for the delivery of smoking cessation services, (7) creation of a certification system for smoking cessation programs, and (8) development of an evaluation system of project performance for smoking cessation. Through the analytic hierarchy process survey, the military specificity and its sub-criterion of practicality were selected as the top concerns of decision criteria for the anti-smoking strategies among the decision criteria of outcome improvement, military specificity, publicness, and economic efficiency. The most important strategy was to improve the perception of and strengthen the reward for smoking cessation. This strategy was most focused on the creation of an anti-smoking environment and improvement of the effectiveness of the projects. The creation of a training system for army clinicians for the delivery of smoking cessation services ranked second. Conclusion In conclusion, motivating smoking cessation and utilizing well-trained army clinicians were found to be the most important anti-smoking strategies for the Korean military. This study might provide valuable insights for policy makers to reduce tobacco use in the Korean military.

Current globalization of drug interventional clinical trials: characteristics and associated factors, 2011–2013

AbstractsBackgroundClinical trial globalization is a major trend for industry-sponsored clinical trials. There has been a shift in clinical trial sites towards emerging regions of Eastern Europe, Latin America, Asia, the Middle East, and Africa. Our study objectives were to evaluate the current characteristics of clinical trials and to find out the associated multiple factors which could explain clinical trial globalization and its implications for clinical trial globalization in 2011–2013.MethodsThe data elements of “phase,” “recruitment status,” “type of sponsor,” “age groups,” and “design of trial” from 30 countries were extracted from the ClinicalTrials.gov website. Ten continental representative countries including the USA were selected and the design elements were compared to those of the USA. Factors associated with trial site distribution were chosen for a multilinear regression analysis.ResultsThe USA, Germany, France, Canada, and United Kingdom were the “top five” countries which frequently held clinical trials. The design elements from nine continental representative countries were quite different from those of the USA; phase 1 trials were more prevalent in India (OR 1.517, p < 0.001) while phase 3 trials were much more prevalent in all nine representative countries than in the USA. A larger number of “child” age group trials was performed in Poland (OR 1.852, p < 0.001), Israel (OR 1.546, p = 0.005), and South Africa (OR 1.963, p < 0.001) than in the USA. Multivariate analysis showed that health care expenditure per capita, Economic Freedom Index, Human Capital Index, and Intellectual Property Rights Index could explain the variance of regional distribution of clinical trials by 63.6%.ConclusionsThe globalization of clinical trials in the emerging regions of Asia, South Africa, and Eastern Europe developed in parallel with the factors of economic drive, population for recruitment, and regulatory constraints.

Construction of a database for published phase II/III drug intervention clinical trials for the period 2009-2014 comprising 2,326 records, 90 disease categories, and 939 drug entities.

OBJECTIVES To construct a database of published clinical drug trials suitable for use 1) as a research tool in accessing clinical trial information and 2) in evidence-based decision-making by regulatory professionals, clinical research investigators, and medical practitioners. MATERIALS Comprehensive information obtained from a search of design elements and results of clinical trials in peer reviewed journals using PubMed (http://www.ncbi.nlm.ih.gov/pubmed). METHOD The methodology to develop a structured database was devised by a panel composed of experts in medical, pharmaceutical, information technology, and members of Ministry of Food and Drug Safety (MFDS) using a step by step approach. A double-sided system consisting of user mode and manager mode served as the framework for the database; elements of interest from each trial were entered via secure manager mode enabling the input information to be accessed in a user-friendly manner (user mode). Information regarding methodology used and results of drug treatment were extracted as detail elements of each data set and then inputted into the web-based database system. RESULTS Comprehensive information comprising 2,326 clinical trial records, 90 disease states, and 939 drugs entities and concerning study objectives, background, methods used, results, and conclusion could be extracted from published information on phase II/III drug intervention clinical trials appearing in SCI journals within the last 10 years. The extracted data was successfully assembled into a clinical drug trial database with easy access suitable for use as a research tool. The clinically most important therapeutic categories, i.e., cancer, cardiovascular, respiratory, neurological, metabolic, urogenital, gastrointestinal, psychological, and infectious diseases were covered by the database. Names of test and control drugs, details on primary and secondary outcomes and indexed keywords could also be retrieved and built into the database. The construction used in the database enables the user to sort and download targeted information as a Microsoft Excel spreadsheet. CONCLUSION Because of the comprehensive and standardized nature of the clinical drug trial database and its ease of access it should serve as valuable information repository and research tool for accessing clinical trial information and making evidence-based decisions by regulatory professionals, clinical research investigators, and medical practitioners.