Myeong Gyu Kim

Population pharmacokinetic-pharmacogenetic model of tacrolimus in the early period after kidney transplantation.

As tacrolimus has a rather narrow therapeutic range and high individual variability in its pharmacokinetics, it is important to determine the cause of the variation in tacrolimus pharmacokinetics. The purpose of this study was to establish a population pharmacokinetic–pharmacogenetic model of tacrolimus and identify covariates that affect pharmacokinetic parameters to prevent fluctuations in the tacrolimus trough concentration during the early period after transplantation. Data from 1501 trough concentrations and 417 densely collected concentrations were compiled from 122 patients who were on post‐operative days 10–20 and analysed with a nonlinear mixed‐effect model. The first‐order conditional estimation (FOCE) with interaction method was used to fit the model using the NONMEM program. Clinical/laboratory data were also collected for the same period, and CYP3A5 and ABCB1 genotypes were analysed for use in modelling from all included patients. An empirical Bayesian approach was used to estimate individual pharmacokinetic profiles. A one‐compartment model with first absorption and elimination and lag time best described the data. The estimated population mean of clearance (CL/F), volume of distribution (V/F) and absorption rate (Ka) were 21.9 L/hr, 205 L, and 3.43/hr, respectively, and the lag time was fixed at 0.25 hr. Clearance increased with days after transplantation and decreased with CYP3A5*3/*3 about 18.4% compared with CYP3A5*1 carriers (p < 0.001). A population pharmacokinetic model was developed for tacrolimus in early post‐kidney transplantation recipients to identify covariates that affect tacrolimus pharmacokinetics. Post‐operative days and CYP3A5 genotype were confirmed as critical factors of tacrolimus pharmacokinetics.

Copy number variability analysis of pharmacogenes in patients with lymphoma, leukemia, hepatocellular, and lung carcinoma using The Cancer Genome Atlas data.

Objective Individual differences in drug efficacy and toxicity remain an important clinical concern. We investigated copy number variation (CNV) frequencies for pharmacogenes using The Cancer Genome Atlas dataset. Materials and methods One hundred and fifty-two pharmacogenes were selected from liver hepatocellular carcinoma, lung squamous cell carcinoma (LUSC), acute myeloid leukemia, and lymphoid neoplasm diffuse large B-cell lymphoma (DLBL). The germ line and somatic CNV frequencies were analyzed. Results We found CNVs with more than 1% frequency in drug-metabolizing enzymes including CYP2A6, CYP2D6, GSTP1, CYP2E1, GSTM1, GSTT1, and SULT1A1, drug transporters such as SLC19A1 and SLC28A1, and targets such as FHIT in normal tissue or blood. GSTM1 had the highest frequency for gene gain (45.45, 39.18, 31.01, and 34.77%, respectively) and for gene loss (18.18, 29.38, 20.89, and 26.68%, respectively) in DLBL, acute myeloid leukemia, liver hepatocellular carcinoma, and LUSC. P2RY12 and P2RY1 had the highest frequency for gene gain in LUSC (26.95 and 26.68%, respectively) whereas ABCB1 and ABL2 had the highest frequency for gene gain in DLBL (27.27%) in cancer tissue or blood. Conclusion Germ line and somatic CNVs of pharmacogenes may play a role in determining individual variations in drug responses. Inclusion of CNVs in pharmacogenetic variations holds promise as biomarkers that can increase the benefits and reduce the risks of drug therapy on an individual level.

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.

Topical Recombinant Human Epidermal Growth Factor for Oral Mucositis Induced by Intensive Chemotherapy with Hematopoietic Stem Cell Transplantation: Final Analysis of a Randomized, Double-Blind, Placebo-Controlled, Phase 2 Trial

The aim of this study was to evaluate the efficacy and safety of recombinant human epidermal growth factor (rhEGF) oral spray for oral mucositis (OM) induced by intensive chemotherapy with hematopoietic stem cell transplantation. In this phase 2 study, patients were randomized to either rhEGF (50 microg/mL) or placebo in a 1:1 ratio. The primary endpoint was incidence of National Cancer Institute (NCI) grade ≥2 OM. A total of 138 patients were enrolled in this study. In the intention-to-treat analysis, rhEGF did not reduce the incidence of NCI grade ≥2 OM (p = 0.717) nor reduce its duration (p = 0.725). Secondary endpoints including the day of onset and duration of NCI grade ≥2 OM, the incidence of NCI grade ≥3 OM and its duration, and patient-reported quality of life were also similar between the two groups. In the per-protocol analysis, however, the duration of opioid analgesic use was shorter in the rhEGF group (p = 0.036), and recipients in the rhEGF group required a lower cumulative dose of opioid analgesics than those in the placebo group (p = 0.046), among patients with NCI grade ≥2 OM. Adverse events were mild and transient. This study found no evidence to suggest that rhEGF oral spray reduces the incidence of OM. However, further studies are needed to investigate the effect of rhEGF on OM-induced pain reduction after intensive chemotherapy.

Genetic polymorphisms of CASR and cancer risk: evidence from meta-analysis and HuGE review.

Background CASR gene appears to be involved in cancer biology and physiology. However, a number of studies investigating CASR polymorphisms and cancer risks have presented inconclusive results. Thus, a systematic review and a meta-analysis of the effect of CASR polymorphisms on several cancer risks were performed to suggest a statistical evidence for the association of CASR polymorphisms with cancer risks. Methods MEDLINE, EMBASE, Web of Science, Scopus, and the HuGE databases were searched. Nineteen articles of case–control and cohort studies were included for the final analysis. Results The colorectal cancer risk was reduced in proximal (odds ratio [OR] =0.679, P=0.001) and distal (OR =0.753, P=0.026) colon sites with GG genotype of CASR rs1042636 and increased in distal colon site (OR =1.418, P=0.039) with GG genotype of rs1801726 by additive genetic model. The rs17251221 demonstrated noticeable associations that carrying a homozygote variant increases breast and prostate cancer risk considerably. Conclusion The significant association of CASR polymorphisms with several cancer risks was observed in this review. In particular, the act of CASR polymorphisms as a tumor suppressor or an oncogene differs by cancer site and can be the research target for tumorigenesis.

Meta-analysis of the impact of thioprine S-methyltransferase polymorphisms on the tolerable 6-mercaptopurine dose considering initial dose and ethnic difference

A meta-analysis was conducted to decide whether to reduce an initial 6-mercaptopurine (6-MP) dose in TPMT heterozygote in the case of an initial 6-MP dose of <75 mg/m2/d and to compare the tolerable 6-MP dose among different ethnic groups. The study was undertaken according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The differences in mean values of the tolerable 6-MP dose were calculated by using Comprehensive Meta-Analysis version 3. The results of the meta-analysis indicated that the tolerable 6-MP dose was significantly lower in the TPMT heterozygote group (difference in mean values =11.729, 95% confidence interval =7.617–15.842, P<0.001) even when the initial 6-MP dose was <75 mg/m2/d. The TPMT*3C allele-dominant ethnic group (Asian) needed less reduction in mean 6-MP dose in comparison to the TPMT*3A allele-dominant ethnic group (Caucasian, Mediterranean, South American) (difference in mean values =8.884 vs 15.324). In conclusion, the initial 6-MP dose needs to be reduced in TPMT heterozygote when compared to the wild-type, and ethnic difference might influence the tolerable 6-MP dose in TPMT heterozygotes.

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.

Impact of depression on change in coronary heart disease risk status: the Korean Genome and Epidemiology Study (KoGES)

Purpose The objective of this study was to evaluate the association between depression and change in coronary heart disease (CHD) risk status by an analysis of examination data in the general Korean population. Patients and methods We examined 1,851 men and 1,689 women (aged 43–73 years) for the Korean Genome and Epidemiology Study Ansan between 2005 and 2012. The estimated CHD risk score of participants was calculated using the Framingham CHD risk score in baseline and after 8-year follow-up period. Among them, population with low Framingham CHD risk score (<10%) in baseline (n=1,582) was used for further analyses. The low Framingham CHD risk score participants were assigned to one of two groups based on the Beck depression inventory (BDI) score: no depression (BDI <10) and depression (BDI ≥10). Multivariate logistic regression was performed to test whether depression was associated with participants’ status change to intermediate or high CHD risk score (≥10%) in men and women, respectively, after 8-year follow-up period. Results Women with depression showed significant higher rates of changing to intermediate or high CHD risk score status when compared with women without depression even after adjusting for age, systolic blood pressure, high-density lipoprotein, and smoking (adjusted odds ratio [OR], 1.54; 95% CI, 1.08–2.03). However, depression was not associated with intermediate or high CHD risk score status in men (adjusted OR, 1.38; 95% CI, 0.95–1.82). Conclusion This general population-based cohort study provides evidence that depression can affect the risk of changing CHD risk score status in women.

Increased Exposure of Tacrolimus by Co-administered Mycophenolate Mofetil: Population Pharmacokinetic Analysis in Healthy Volunteers

The objective of the study was to investigate the pharmacokinetic drug-drug interactions between tacrolimus (TAC) and mycophenolate mofetil (MMF) in healthy Korean male volunteers. Seventeen volunteers participated in a three-period, single-dose, and fixed sequence study. They sequentially received MMF, TAC, and the combination. Concentrations of TAC, mycophenolic acid (MPA), and its metabolites MPA 7-O-glucuronide and MPA acyl glucuronide were measured. The variants of CYP3A4, CYP3A5, SLCO1B1, SLCO1B3, ABCC2, UGT1A9, and UGT2B7 were genotyped. Drug interaction was evaluated with a non-compartmental analysis and population pharmacokinetic modelling to quantify the interaction effect. A total of 1,082 concentrations of those analytes were analysed. AUC0-inf of TAC increased by 22.1% (322.4 ± 174.1 to 393.6 ± 121.7 ng·h/mL; P < 0.05) when co-administered with MMF, whereas the pharmacokinetic parameters of MPA and its metabolites were not changed by TAC. Apparent clearance (CL/F) of TAC was 17.8 L/h [relative standard error (RSE) 11%] or 13.8 L/h (RSE 11%) without or with MMF, respectively. Interaction was explained by the exponential model. The CYP3A5 genotype was the only significant covariate. The population estimate of CL/F of TAC was 1.48-fold (RSE 16%) in CYP3A5 expressers when compared to nonexpressers. CL/F of TAC was decreased when co-administered with MMF in these subjects.