Pharmacokinetics/genotype associations for major cytochrome P450 enzymes in native and first- and third-generation Japanese populations: comparison with Korean, Chinese, and Caucasian populations

Exploring the impact of ethnicity on drug pharmacokinetics using PBPK models: A case study with lansoprazole in Japanese subjects

AIMS

The aim of this study is to demonstrate the use of PBPK modelling to explore the impact of ethnic differences on drug PK.

METHODS

A PBPK model developed for lansoprazole was used to predict the clinical PK of lansoprazole in Japanese subjects by incorporating the physiological parameters of a Japanese population into the model. Further verification of the developed Japanese population with clinical studies involving eight other CYP substrates-omeprazole, ticlopidine, alprazolam, midazolam, nifedipine, cinacalcet, paroxetine and dextromethorphan-was also carried out.

RESULTS

The PK of lansoprazole in both Caucasian and Japanese subjects was well predicted by the model as the observed data were within the 5th and 95th percentiles across all the clinical studies. In age- and sex-matched simulations in both the Caucasian and Japanese populations, the predicted PK (mean ± SD) of a single oral dose of 30-mg lansoprazole was higher in the Japanese population in all cases, with more than twofold higher AUC of 5.98 ± 6.43 mg/L.h (95% CI: 4.72, 7.24) vs. 2.46 ± 2.45 mg/L.h (95% CI: 1.98, 2.94) in one scenario. In addition, in two out of the nine clinical DDIs of lansoprazole and the additional CYP substrates simulated using the Japanese population, the predicted DDI in Japanese was more than 1.25-fold that in Caucasians, indicating an increased DDI liability.

CONCLUSIONS

By accounting for various physiological parameters that characterize a population in a PBPK model, the impact of the different identified interethnic differences on the drug's PK can be explored, which can inform the adoption of drugs from one region to another.

A randomized phase I study of the safety and pharmacokinetics of BI 1291583 in healthy Japanese male subjects

AIMS

Bronchiectasis patients face an unmet need for treatment options that reduce inflammation. Cathepsin C inhibition is expected to achieve this by reducing the activation of neutrophil-derived serine proteases. Here, we present safety and pharmacokinetic (PK) data from a Phase I trial evaluating the novel cathepsin C inhibitor BI 1291583 in healthy Japanese male subjects.

METHODS

This randomized, double-blind, placebo-controlled, parallel-group study investigated BI 1291583 in healthy Japanese male subjects (jRCT2071210111) and consisted of a single-rising-dose (SRD) part and a multiple-dose (MD) part. The primary endpoint was the percentage of subjects with drug-related treatment-emergent adverse events (AEs). Secondary PK endpoints (SRD: AUC0-∞ and Cmax; MD: AUCτ,1 and Cmax,1 after first dose and AUCτ,ss and Cmax,ss after last dose), as well as further safety and PK endpoints, were also assessed.

RESULTS

Overall, 36 subjects (n = 24 for SRD part; n = 12 for MD part) entered this Phase I trial. BI 1291583 was safe and well tolerated across the doses tested. All AEs were of mild intensity, with no drug-related treatment-emergent AEs, deaths, serious AEs or AEs of special interest reported in either part of the trial. Following both SRD and MD administration, BI 1291583 was readily absorbed, and PK was supraproportional over the doses assessed.

CONCLUSION

The results show that BI 1291583 has an appropriate benefit-risk ratio for Japanese patients, with no safety or exposure concerns at the doses studied. Japanese patients with bronchiectasis can be safely integrated into future global clinical trials of BI 1291583, with no dose adjustment required.

The Diversity of CYP2C19 Polymorphisms in the Thai Population: Implications for Precision Medicine

Introduction

CYP2C19 plays a major role in the metabolism of various drugs. The most common genetic variants were the CYP2C19*2 and *3 alleles (rs4244285 and rs4986893, non-functional variants). In previous studies, we found that genetic polymorphisms in CYP2C19 variants influenced the active metabolites of clopidogrel and caused major adverse cardiovascular and cerebrovascular effects. However, the distribution of CYP2C19 varies among ethnic groups and according to adverse drug reactions. This study aimed to investigate the frequency of CYP2C19 genetic polymorphisms in the Thai population and analyze the differences in the frequency of CYP2C19 genetic polymorphisms between Thai and other populations.

Methods

This study enrolled 211 unrelated healthy Thai individuals in total. We performed a real-time polymerase chain reaction to genotype CYP2C19*2 (681G > A) and CYP2C19*3 (636G > A).

Results

In the Thai population, the CYP2C19*1 allele was the most prevalent at 70.14%, while the CYP2C19*2 and *3 alleles were found at frequencies of 25.36% and 4.50%, respectively. Conversely, the CYP2C19*3 allele was not detected in Caucasian, Hispanic, African, Italian, Macedonian, Tanzanian, or North Indian populations. The phenotypic profile of this gene revealed that the frequency of intermediate metabolizers (IMs) is nearly equal to that of extensive metabolizers (EMs), at 42.65% and 48.82% respectively, with genotypes *1/*2 (36.02%) and *1/*3 (6.63%). Likewise, poor metabolizers (PMs) with genotypes *2/*2 (6.16%), *2/*3 (2.37%), and *3/*3 (<1%) are more prevalent in our population as well.

Conclusion

The distribution of CYP2C19 genotype and phenotype influenced by non-functional alleles has potential as a pharmacogenomics biomarker for precision medicine and is dependent on an ethnic-specific genetic variation database.

Assessing the ability of the Cancer and Aging Research Group tool to predict chemotherapy toxicity in older Japanese patients: A prospective observational study

INTRODUCTION

The Cancer and Aging Research Group (CARG) prediction tool was designed in the United States to predict grade ≥ 3 chemotherapy-related adverse events (CRAE) in older patients. However, its usefulness among Japanese people, who have different sensitivities to anticancer drugs and life expectancy, remains unknown. We aimed to prospectively evaluate the utility of the CARG tool for predicting severe CRAE in older Japanese patients with cancer.

MATERIAL AND METHODS

Patients with solid tumors aged 65 years and older who commenced anticancer drug regimens from April 2018 to October 2020 were divided into three groups (low, medium, and high-risk) based on their CARG risk scores. Toxicity was prospectively observed by a pharmacist. The primary objective was to evaluate the correlation between the incidence of grade ≥ 3 CRAE and the CARG risk score. The secondary objective was to evaluate hematological and non-hematological toxicities. CRAE incidence was compared among the three groups using a closed testing procedure: (1) Cochran-Armitage test for trend and (2) chi-square test for paired comparison.

RESULTS

The patients (N = 165) had a median age of 71 years (range: 65-89 years). CRAE in patients divided into low-, medium-, and high-risk groups, based on CARG risk scores, were 39%, 55%, and 82%, respectively (low vs high; p < 0.001, medium vs high; p < 0.01). The incidence of severe hematologic toxicity was 37%, 35%, and 50% in the low-, medium-, and high-risk groups, respectively; the incidence of severe non-hematologic toxicity was 15%, 36%, and 65%, respectively (low vs medium; p < 0.01, low vs high; p < 0.001, and medium vs high; p < 0.01).

DISCUSSION

To our knowledge, this is the first prospective observational study to validate the CARG prediction tool in older Japanese patients with cancer. The CARG risk score may be effective in predicting the development of non-hematologic toxicities. These results should be considered when administering chemotherapy to older Japanese patients with advanced solid tumors.

An Investigation in the Comparability of the Exposure and Recommended Dose of Selected Pfizer Drugs in East Asian Countries: Is Mutual Usage of Clinical Data Among East Asian Countries Feasible?

The current regulatory path for new drug registration in East Asian countries has led to significant delay of the new medicines in these countries. A unified regulatory path and allowance of mutual usage of clinical data in East Asian countries would lead to cost saving in drug development and expedite the new drug registration in these countries. The objectives of the present analysis are to compare the approval dates of a selection of products developed by Pfizer in the United States and East Asian countries (China, Japan, Korea) and compare the pharmacokinetics and recommended doses of these products in East Asian countries. Eighteen products (20 drugs, 2 products with 2 combination drugs) with exposure data available in at least 2 of the 3 East Asian countries across different therapeutic areas were included in the analyses. The results showed that most products had delayed approval in East Asian countries (up to 8 years) after US or EU approval. No distinct differences were observed in the drug exposure and recommended doses for the selected products in East Asian countries. These results together with literature data of genetic similarity of the East Asian populations support the mutual usage of the clinical data in the East Asian countries for expedited regulatory submission and approval.

Associations between ondansetron and the incidence of postoperative nausea and vomiting and food intake in Japanese female undergoing laparoscopic gynecological surgery: a retrospective study

PURPOSE

Prevention of postoperative nausea and vomiting (PONV) is important to achieve DREAM (drinking, eating, mobilization). Ondansetron inhibits PONV, but its effects on postoperative food intake have not been investigated. This study aimed to examine associations between ondansetron and PONV incidence, and postoperative food intake.

METHODS

This retrospective study included adult patients (n = 632) who underwent laparoscopic gynecological surgery at Kyushu University Hospital between January 2017 and June 2023. Outcomes were PONV on the day of surgery, PONV up to the day after surgery, and food intake, which was assessed for breakfast and lunch on the day after surgery. Odds ratios (ORs) for PONV incidence and postoperative no-food intake were calculated between those with and without ondansetron during surgery. Multivariable-adjusted analysis was performed using possible confounding factors for PONV. Synergistic effects of combining ondansetron with dexamethasone or total intravenous anesthesia (TIVA) were assessed.

RESULTS

Multivariable-adjusted ORs for PONV on the day of surgery and up to the day after surgery were 0.56 (95% confidence interval, 0.32-0.99, p = 0.04) and 0.52 (0.30-0.93, p = 0.03), respectively, in the ondansetron group (n = 84) compared with the non-ondansetron group (n = 548). In contrast, multivariable-adjusted ORs for no-food intake of breakfast and lunch the day after surgery in the ondansetron group compared with the non-ondansetron group were not significant. Analysis of synergistic effects on PONV showed no significant interaction between ondansetron and dexamethasone or ondansetron and TIVA combinations.

CONCLUSION

Ondansetron administration during surgery was significantly associated with decreased PONV risk but was not associated with food intake the day after surgery.

Clinical pharmacokinetics and pharmacodynamics of ivosidenib in Chinese patients with relapsed or refractory IDH1-mutated acute myeloid leukemia

PURPOSE

This study aimed to assess the pharmacokinetics (PK) and pharmacodynamics (PD) of ivosidenib in Chinese patients with relapsed or refractory acute myeloid leukemia (R/R AML) carrying the mIDH1 mutation.

METHODS

A bridging study (NCT04176393) was conducted involving 29 Chinese patients who received a daily dose of ivosidenib 500 mg in 28-day cycles. Plasma concentrations of ivosidenib and D-2-hydroxyglutarate (2-HG) were measured before and after treatment. Non-compartmental analysis (NCA) was employed to evaluate the PK, and an established population pharmacokinetic (popPK) model developed from non-Chinese patients was externally validated.

RESULTS

The findings revealed comparable PD effects of ivosidenib in Chinese patients with mIDH1 R/R AML. After adjusting for concomitant drug effects, PK characteristics were similar between Chinese and non-Chinese patients. Furthermore, the popPK model offered additional insights into the possible causes of the apparent ethnic difference in PK exposure.

CONCLUSION

The study indicates that ivosidenib can be used effectively in Chinese patients, and the observed ethnic differences in PK exposure can be explained by concomitant drug effects. The popPK model contributes to a better understanding and optimization of personalized dosing in Chinese patients with mIDH1 R/R AML.

CYP2C19 *2/*2 Genotype is a Risk Factor for Multi-Site Arteriosclerosis: A Hospital-Based Cohort Study

Background

Vascular diseases such as atherosclerosis usually affect multiple organs. Genetic factors have a certain proportion in the risk factors of atherosclerosis. The purpose was to investigate the relationship of cytochrome P450 2C19 (CYP2C19) polymorphisms with multi-site atherosclerosis.

Methods

The study included 410 patients with single-site atherosclerosis and 529 patients with multi-site atherosclerosis. The relationship between CYP2C19 rs4244285 and rs4986893 polymorphisms and single-site atherosclerosis and multi-site atherosclerosis was analyzed.

Results

The proportion of CYP2C19 rs4244285 A allele (35.9% vs 29.9%, P=0.007) and rs4986893 G allele (97.7% vs 94.8%, P=0.001) in multi-site atherosclerosis group was significantly higher than that in single-site atherosclerosis group. The distribution of CYP2C19 genotypes was significantly different between the two groups (P=0.002). The results of univariate logistic regression indicated that CYP2C19 *1/*3 genotype (*1/*3 vs *1/*1: odds ratio (OR) 0.456, 95% confidence interval (CI): 0.231-0.902, P=0.024) may decrease risk of multi-site atherosclerosis, while *2/*2 genotype (*2/*2 vs *1/*1: OR 1.780, 95% CI: 1.100-2.880, P=0.019) may increase risk of multi-site atherosclerosis. Multivariate logistic regression (adjusted for gender, age, smoking, drinking, hypertension, and diabetes) indicated that CYP2C19 *1/*3 genotype (*1/*3 vs *1/*1: OR 0.459, 95% CI: 0.231-0.909, P=0.026) may be an independent protective factor for multi-site atherosclerosis, while *2/*2 genotype (*2/*2 vs *1/*1: OR 1.767, 95% CI: 1.091-2.864, P=0.021) may be an independent risk factor for multi-site atherosclerosis.

Conclusion

CYP2C19 *1/*3 genotype may be an independent protective factor for multi-site atherosclerosis, while *2/*2 genotype may be an independent risk factor for multi-site atherosclerosis.

Model-based meta-analysis of ethnic differences and their variabilities in clearance of oral drugs classified by clearance mechanism

In this study, the ethnic ratios (ERs) of oral clearance between Japanese and Western populations were subjected to model-based meta-analysis (MBMA) for 81 drugs evaluated in 673 clinical studies. The drugs were classified into eight groups according to the clearance mechanism, and the ER for each group was inferred together with interindividual variability (IIV), interstudy variability (ISV), and inter-drug variability within a group (IDV) using the Markov chain Monte Carlo (MCMC) method. The ER, IIV, ISV, and IDV were dependent on the clearance mechanism, and, except for particular groups such as drugs metabolized by polymorphic enzymes or their clearance mechanism is not confirmative, the ethnic difference was found to be generally small. The IIV was well-matched across ethnicities, and the ISV was approximately half of the IIV as the coefficient of variation. To adequately assess ethnic differences in oral clearance without false detections, phase I studies should be designed with full consideration of the mechanism of clearance. This study suggests that the methodology of classifying drugs based on the mechanism that causes ethnic differences and performing MBMA with statistical techniques such as MCMC analysis is helpful for a rational understanding of ethnic differences and for strategic drug development.

Asia-Inclusive Clinical Research and Development Enabled by Translational Science and Quantitative Clinical Pharmacology: Toward a Culture That Challenges the Status Quo

Access lag to innovative therapies in Asian populations continues to present a challenge to global health. Recent progressive changes in the global regulatory landscape, including newer guidelines, are enabling simultaneous global drug development and near-simultaneous global drug registration. The International Conference on Harmonization (ICH) E17 guideline outlines general principles for the design and analysis of multiregional clinical trials (MRCTs). We posit that translational research and quantitative clinical pharmacology tools are core enablers for Asia-inclusive global drug development aligned with ICH E17 principles. Assessment of ethnic sensitivity should be initiated early in the development lifecycle to inform the need for, and extent of, Asian phase I ethno-bridging data. Relevant ethno-bridging data may be generated as standalone Asian phase I trials, as part of Western First-In-Human trials, or under accelerated development settings as a lead-in phase in an MRCT. Quantitative understanding of human clearance mechanisms and pharmacogenetic factors is vital to forecasting ethnic sensitivity in drug exposure using physiologically-based pharmacokinetic models. Stratification factors to control heterogeneity in MRCTs can be identified by reverse translational research incorporating pharmacometric disease models and model-based meta-analyses. Because epidemiological variations can extend to the molecular level, quantitative systems pharmacology models may be useful in forecasting how molecular variation in therapeutic targets or pathway proteins across populations might impact treatment outcomes. Through prospective evaluation of conservation in drug- and disease-related intrinsic and extrinsic factors, a pooled East Asian region can be implemented in Asia-inclusive MRCTs to maximize efficiency in substantiating evidence of benefit-risk for the region at-large with a Totality of Evidence approach.

Pharmacokinetics, Bioequivalence, and Safety Evaluation of Dienogest in Healthy Subjects Under Fasting and Fed Conditions

Dienogest is effective in reducing endometriosis-related pain symptoms. This study aims to investigate and compare the pharmacokinetic profiles and safety of test formulations to reference formulations of dienogest in healthy Chinese female volunteers under fasting or fed conditions. The purpose of this single-center, randomized, open-label, 2-sequence, 2-period crossover clinical trial was to evaluate the safety and pharmacokinetic profiles of the 2 formulations under fasting and fed conditions. Additionally, 48 healthy female volunteers were selected and divided at random into the fasting and the fed group. After dosing, the venous blood was collected through indwelling catheters. Dienogest plasma concentrations were measured using liquid chromatography-tandem mass spectrometry after the plasma samples were prepared with the protein precipitation method. Under either fasting or fed conditions, the pharmacokinetic parameters (maximum observed concentration, area under the concentration-time curve [AUC] from time 0 to the last measurable concentration, and AUC from time 0 to infinity) for dienogest between the test and reference products, geometric mean ratio, and 90%CI were all within the range of 80%-125%. The 2 dienogest products were bioequivalent. Based on maximum observed concentration and AUC from time 0 to the last measurable concentration, the generic dienogest was bioequivalent to the original dienogest in this study conducted under fasting and fed conditions in healthy Chinese women (study CTR20190063 on chinadrugtrials.org.cn registry).

Comparison of Pharmacokinetics of the GalNAc-Conjugated Antisense Oligonucleotide GSK3389404 in Participants with Chronic Hepatitis B Infection across the Asia-Pacific Region

GSK3389404, an N-acetyl galactosamine-conjugated antisense oligonucleotide (ASO), was in clinical development for chronic hepatitis B (CHB) treatment. Few studies have examined ASOs in Asian participants. In this analysis, the plasma pharmacokinetics (PK) of GSK3389404 were characterized and compared in patients with CHB across the Asia-Pacific region (N = 64), including mainland China (n = 16), Hong Kong (n = 8), Japan (n = 21), South Korea (n = 12), Singapore (n = 4), and the Philippines (n = 3), from a phase 2a, multicenter, randomized, double-blind, placebo-controlled study (NCT03020745). Hepatitis B(e) antigen-positive and -negative patients (on or not on stable nucleos[t]ide regimens) received single (30 mg or 120 mg) or multiple (30 mg, 60 mg, or 120 mg weekly or 120 mg biweekly) subcutaneous GSK3389404 injections. The plasma concentrations were measured on day 1 in all cohorts as well as on days 29 and 57 in the multiple-dose cohorts. The GSK3389404 plasma PK were similar to those reported in a previous study in non-Asian healthy participants with a median time to peak concentration (t_max) of 1 to 4 h postdose, a mean half-life of 3 to 5 h across cohorts, and no accumulation following repeat dosing. The GSK3389404 plasma t_max and half-life values were dose-independent. The increase in the plasma peak concentration (C_max) and the area under the concentration versus time curve (AUC) was dose-proportional from 60 to 120 mg and greater than dose-proportional from 30 to 60 or 120 mg. The GSK3389404 plasma concentration versus time profiles, half-life, t_max, C_max, and AUC values were all comparable across the Asia-Pacific populations. Given the similarity of the PK among ASOs, this analysis suggests that the PK from any Asia-Pacific population may be used to guide ASO dose selection in the Asia-Pacific region.

Pharmacokinetic, Safety, and Tolerability Evaluations of Gepotidacin (GSK2140944) in Healthy Japanese Participants

Gepotidacin is a novel, bactericidal, first-in-class triazaacenaphthylene antibiotic in late-phase development for uncomplicated urinary tract infection and uncomplicated urogenital gonorrhea. Two clinical studies were conducted to assess the pharmacokinetics (PK) and interethnic comparisons of oral gepotidacin (free-base and to-be-marketed mesylate formulations) administered as single doses ranging from 1500 to 3000 mg in fed and fasted states, and as 2 × 3000-mg doses given 12 hours apart under fed conditions in healthy participants of Japanese ancestry. Dose proportionality was observed in plasma exposures, and comparable area under the concentration-time curve (AUC) and maximum concentration were observed in fed and fasted states. Interethnic comparisons for Japanese versus non-Japanese participant data showed slightly higher plasma maximum concentration (7%-30%) yet similar plasma AUCs; slightly lower urine AUCs (11%-18%) were observed. The slightly higher plasma exposures in healthy Japanese versus White participants in the same study were attributed to lower mean body weights (64 kg versus ≈80 kg). Adverse events were primarily gastrointestinal, and when administered with food, gastrointestinal tolerability was improved. Overall, the gepotidacin PK and safety-risk profiles in healthy Japanese support potential evaluation of the global clinical doses in future studies.

Variations in the Frequencies of Polymorphisms in the CYP450s Genes in Eight Major Ethnicities of Iran: A Review of the Human Data

Genetic polymorphisms in cytochrome P450 genes can cause variation in metabolism. Thus, single nucleotide variants significantly impact drug pharmacokinetics, toxicity factors, and efficacy and safety of medicines. The distribution of CYP450 alleles varies drastically across ethnicities, with significant implications for personalized medicine and the healthcare system. We combined whole-genome and exome sequencing data to provide a review of CYP450 allele polymorphisms with clinical importance. Data were collected from 800 unrelated Iranians (100 subjects from 8 major ethnicities of Iran), more than 32,000 unrelated Europeans (other than Caucasian), and four Middle Eastern countries. We analyzed the frequencies and similarities of 17 CYP450 frequent alleles related to nine important CYP450 isoenzymes and homozygous and heterozygous genotypes based on these alleles in eight major Iranian ethnics by integrating these data with population-specific linkage information and compared these datasets with mentioned populations.

Physiologically based pharmacokinetic (PBPK) modeling of the role of CYP2D6 polymorphism for metabolic phenotyping with dextromethorphan

The cytochrome P450 2D6 (CYP2D6) is a key xenobiotic-metabolizing enzyme involved in the clearance of many drugs. Genetic polymorphisms in CYP2D6 contribute to the large inter-individual variability in drug metabolism and could affect metabolic phenotyping of CYP2D6 probe substances such as dextromethorphan (DXM). To study this question, we (i) established an extensive pharmacokinetics dataset for DXM; and (ii) developed and validated a physiologically based pharmacokinetic (PBPK) model of DXM and its metabolites dextrorphan (DXO) and dextrorphan O-glucuronide (DXO-Glu) based on the data. Drug-gene interactions (DGI) were introduced by accounting for changes in CYP2D6 enzyme kinetics depending on activity score (AS), which in combination with AS for individual polymorphisms allowed us to model CYP2D6 gene variants. Variability in CYP3A4 and CYP2D6 activity was modeled based on in vitro data from human liver microsomes. Model predictions are in very good agreement with pharmacokinetics data for CYP2D6 polymorphisms, CYP2D6 activity as described by the AS system, and CYP2D6 metabolic phenotypes (UM, EM, IM, PM). The model was applied to investigate the genotype-phenotype association and the role of CYP2D6 polymorphisms for metabolic phenotyping using the urinary cumulative metabolic ratio (UCMR), DXM/(DXO + DXO-Glu). The effect of parameters on UCMR was studied via sensitivity analysis. Model predictions indicate very good robustness against the intervention protocol (i.e. application form, dosing amount, dissolution rate, and sampling time) and good robustness against physiological variation. The model is capable of estimating the UCMR dispersion within and across populations depending on activity scores. Moreover, the distribution of UCMR and the risk of genotype-phenotype mismatch could be estimated for populations with known CYP2D6 genotype frequencies. The model can be applied for individual prediction of UCMR and metabolic phenotype based on CYP2D6 genotype. Both, model and database are freely available for reuse.

Pharmacokinetics of Caffeine: A Systematic Analysis of Reported Data for Application in Metabolic Phenotyping and Liver Function Testing

Caffeine is by far the most ubiquitous psychostimulant worldwide found in tea, coffee, cocoa, energy drinks, and many other beverages and food. Caffeine is almost exclusively metabolized in the liver by the cytochrome P-450 enzyme system to the main product paraxanthine and the additional products theobromine and theophylline. Besides its stimulating properties, two important applications of caffeine are metabolic phenotyping of cytochrome P450 1A2 (CYP1A2) and liver function testing. An open challenge in this context is to identify underlying causes of the large inter-individual variability in caffeine pharmacokinetics. Data is urgently needed to understand and quantify confounding factors such as lifestyle (e.g., smoking), the effects of drug-caffeine interactions (e.g., medication metabolized via CYP1A2), and the effect of disease. Here we report the first integrative and systematic analysis of data on caffeine pharmacokinetics from 141 publications and provide a comprehensive high-quality data set on the pharmacokinetics of caffeine, caffeine metabolites, and their metabolic ratios in human adults. The data set is enriched by meta-data on the characteristics of studied patient cohorts and subjects (e.g., age, body weight, smoking status, health status), the applied interventions (e.g., dosing, substance, route of application), measured pharmacokinetic time-courses, and pharmacokinetic parameters (e.g., clearance, half-life, area under the curve). We demonstrate via multiple applications how the data set can be used to solidify existing knowledge and gain new insights relevant for metabolic phenotyping and liver function testing based on caffeine. Specifically, we analyzed 1) the alteration of caffeine pharmacokinetics with smoking and use of oral contraceptives; 2) drug-drug interactions with caffeine as possible confounding factors of caffeine pharmacokinetics or source of adverse effects; 3) alteration of caffeine pharmacokinetics in disease; and 4) the applicability of caffeine as a salivary test substance by comparison of plasma and saliva data. In conclusion, our data set and analyses provide important resources which could enable more accurate caffeine-based metabolic phenotyping and liver function testing.

CYP2C19 Genotyping May Provide a Better Treatment Strategy when Administering Escitalopram in Chinese Population

Depression disorder is one of the most serious mental illnesses in the world. Escitalopram is the essential first-line medication for depression disorder. It is the substrate of hepatic cytochrome P450 (CYP) enzyme CYP2C19 with high polymorphism. The effect of CYP2C19 on pharmacokinetics and pharmacodynamics on Caucasian population has been studied. The Clinical Pharmacogenetics Implementation Consortium Guideline provides dosing recommendations for escitalopram on CYP2C19 genotypes on the basis of the studies on Caucasian population. However, the gene frequency of the alleles of CYP2C19 showed racial differences between Chinese and Caucasian populations. Representatively, the frequency of the *2 and *3 allele, which were considered as poor metabolizer, has been shown to be three times higher in Chinese than in Caucasians. In addition, the environments might also lead to different degrees of impacts on genotypes. Therefore, the guidelines based on the Caucasians may not be applicable to the Chinese, which induced the establishment of a guideline in China. It is necessary to provide the evidence of individual treatment of escitalopram in Chinese by studying the effect of CYP2C19 genotypes on the pharmacokinetics parameters and steady-state concentration on Chinese. In this study, single-center, randomized, open-label, two-period, two-treatment crossover studies were performed. Ninety healthy Chinese subjects finished the trials, and they were included in the statistical analysis. The pharmacokinetics characteristics of different genotypes in Chinese were obtained. The results indicate that the poor metabolizer had higher exposure, and increased half-life than the extensive metabolizer and intermediate metabolite. The prediction of steady-state concentration based on the single dose trial on escitalopram shows that the poor metabolizer might have a higher steady-state concentration than the extensive metabolizer and intermediate metabolite in Chinese. The results indicate that the genetic testing before medication and the adjustment of escitalopram in the poor metabolizer should be considered in the clinical treatments in Chinese. The results provide the evidence of individual treatment of escitalopram in Chinese, which will be beneficial for the safer and more effective application of escitalopram in the Chinese population. Clinical Trial Registration: identifier ChiCTR1900027226.

Frequency of Important CYP450 Enzyme Gene Polymorphisms in the Iranian Population in Comparison with Other Major Populations: A Comprehensive Review of the Human Data

Genetic polymorphisms in cytochrome P450 genes can cause alteration in metabolic activity of clinically important medicines. Thus, single nucleotide variants (SNVs) and copy number variations (CNVs) in CYP genes are leading factors of drug pharmacokinetics and toxicity and form pharmacogenetics biomarkers for drug dosing, efficacy, and safety. The distribution of cytochrome P450 alleles differs significantly between populations with important implications for personalized drug therapy and healthcare programs. To provide a meta-analysis of CYP allele polymorphisms with clinical importance, we brought together whole-genome and exome sequencing data from 800 unrelated individuals of Iranian population (100 subjects from 8 major ethnics of Iran) and 63,269 unrelated individuals of five major human populations (EUR, AMR, AFR, EAS and SAS). By integrating these datasets with population-specific linkage information, we evolved the frequencies of 140 CYP haplotypes related to 9 important CYP450 isoenzymes (CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1, CYP3A4 and CYP3A5) giving a large resource for major genetic determinants of drug metabolism. Furthermore, we evaluated the more frequent Iranian alleles and compared the dataset with the Caucasian race. Finally, the similarity of the Iranian population SNVs with other populations was investigated.

Functional Characterization of 21 Rare Allelic CYP1A2 Variants Identified in a Population of 4773 Japanese Individuals by Assessing Phenacetin O-Deethylation

Cytochrome P450 1A2 (CYP1A2), which accounts for approximately 13% of the total hepatic cytochrome content, catalyzes the metabolic reactions of approximately 9% of frequently used drugs, including theophylline and olanzapine. Substantial inter-individual differences in enzymatic activity have been observed among patients, which could be caused by genetic polymorphisms. Therefore, we functionally characterized 21 novel CYP1A2 variants identified in 4773 Japanese individuals by determining the kinetic parameters of phenacetin O-deethylation. Our results showed that most of the evaluated variants exhibited decreased or no enzymatic activity, which may be attributed to potential structural alterations. Notably, the Leu98Gln, Gly233Arg, Ser380del Gly454Asp, and Arg457Trp variants did not exhibit quantifiable enzymatic activity. Additionally, three-dimensional (3D) docking analyses were performed to further understand the underlying mechanisms behind variant pharmacokinetics. Our data further suggest that despite mutations occurring on the protein surface, accumulating interactions could result in the impairment of protein function through the destabilization of binding regions and changes in protein folding. Therefore, our findings provide additional information regarding rare CYP1A2 genetic variants and how their underlying effects could clarify discrepancies noted in previous phenotypical studies. This would allow the improvement of personalized therapeutics and highlight the importance of identifying and characterizing rare variants.

Points to Consider for Implementation of the ICH E17 Guideline: Learning from Past Multiregional Clinical Trials in Japan

We identified the major points that are described in the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) E17 guideline but have not been considered in the past multiregional clinical trials (MRCTs) used for drug approval in Japan to elucidate potential challenges in the implementation of the ICH E17 guideline in Japan. Based on the analysis of 167 MRCTs of 130 drugs, several points, such as the same dose setting and consistency between the overall and Japanese populations, in addition to good clinical practice compliance, have been well considered in ≥ 75% of MRCTs. In contrast, the use of relevant guidelines for disease and primary end point definitions, standardization of efficacy/safety information, sample size allocation, as well as training/validation on subject selection and primary end point, have been addressed less adequately and may need to be considered when planning future MRCTs. This study provides useful information for the implementation of the ICH E17 guideline in Japan.

Efficacy and safety of lemborexant in adults with insomnia: comparing Japanese and non-Japanese subgroups from the global, phase 3, randomized, double-blind, placebo-controlled SUNRISE 2 study

STUDY OBJECTIVE

Whether there are racial differences in the efficacy/safety of hypnotics has not been sufficiently investigated. We aimed to evaluate the efficacy/safety of lemborexant 5 mg and lemborexant 10 mg vs placebo once daily in a subset of Japanese patients with insomnia and to compare the results with those of non-Japanese patients.

METHODS

This subanalysis reports the results of the first 6 months (period 1, placebo-controlled) of SUNRISE 2, a 12-month, global, randomized, double-blind, phase 3 study. Changes in patient-reported sleep onset latency, patient-reported sleep efficiency, and patient-reported wake after sleep onset with lemborexant 5 mg or lemborexant 10 mg vs placebo were evaluated. Treatment-emergent adverse events were evaluated for safety.

RESULTS

In total, 949 patients were randomized (Japanese, n = 161; non-Japanese, n = 788). Groups were balanced at baseline except for the male/female ratio (P = .0002) and body mass index (P < .0001) in the Japanese vs non-Japanese subgroups. Overall, the efficacy and safety of lemborexant were similar between subgroups. In the Japanese subgroup, the subjective sleep onset latency change from baseline was significant after 7 nights and 6 months with lemborexant 10 mg vs placebo, the subjective sleep efficiency change from baseline was significant after 7 nights with lemborexant 10 mg vs placebo, and the subjective wake after sleep onset change from baseline was significant at 6 months with lemborexant 5 mg vs placebo. The incidence and severity of treatment-emergent adverse events were consistent between both subgroups.

CONCLUSIONS

Lemborexant 5 mg and 10 mg improved sleep onset and sleep maintenance over 6 months and was well-tolerated in both the Japanese and non-Japanese patients. The safety profiles of lemborexant 5 mg and 10 mg were consistent between the subgroups.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Name: Long-term Study of Lemborexant in Insomnia Disorder (SUNRISE 2); URL: https://clinicaltrials.gov/ct2/show/NCT02952820; Identifier: NCT02952820; and Registry: ClinicalTrialsRegister.eu; Identifier: 2015-001463-39.

The relationship between plasma clozapine concentration and clinical outcome: a cross-sectional study

OBJECTIVE

There is no report that statistically evaluates the therapeutic reference (350-600 ng/ml) and adverse drug reaction (ADR) range (>1000 ng/ml) of clozapine (CLZ) recommended by the Arbeitsgemeinschaft für Neuropsychopharmakologie und Pharmakopsychiatrie (AGNP) consensus guidelines in an isolated and large sampling study.

METHODS

We administered CLZ to 131 Japanese patients with treatment-resistant schizophrenia in a multicenter cross-sectional study. Plasma CLZ concentrations were assayed by high-performance liquid chromatography using trough sampling. The Brief Psychiatric Rating Scale (BPRS) and severe dose-dependent ADR (sedation, myoclonus, and seizures) were analyzed statistically after adjusting for possible confounders.

RESULTS

The daily CLZ dosage showed a moderately positive relationship with the plasma concentration (r = 0.49, p < 0.001). Every 100 ng/ml increase in plasma CLZ concentration improved the total BPRS score 1.95% (95% CI: 0.89-3.01, p < 0.001) and the odds ratio (OR) 1.38 (95% CI: 1.14-1.66, p = 0.001) for BPRS response. Compared with concentrations below 350 ng/ml CLZ, 350-600 ng/ml (11.12%; 95% CI: 2.52-19.72, p = 0.012) and 600-1000 ng/ml (11.05%; 95% CI: 2.40-19.71, p = 0.013) showed significant improvement in the total BPRS score. Dosages above 1000 ng/ml showed greater improvement (25.36%; 95% CI: 13.08-37.64, p < 0.001) of the total BPRS score but more severe ADRs than dosages below 1000 ng/ml (OR: 31.72; 95% CI: 1.04-968.81, p = 0.048).

CONCLUSION

The AGNP therapeutic reference range (350-600 ng/ml) is useful, and a dose above 1000 ng/ml is potentially more effective but carries the risk of severe ADRs in the central nervous system.

Pharmacokinetics of indacaterol, glycopyrronium and mometasone furoate administered as an inhaled fixed-dose combination in Japanese and Caucasian healthy subjects

BACKGROUND

A once-daily (o.d.) fixed-dose combination of indacaterol acetate (IND), glycopyrronium bromide (GLY), and mometasone furoate (MF) delivered via the Breezhaler® device (IND/GLY/MF) is being developed for treatment of asthma. This study compared steady-state pharmacokinetics of IND, GLY and MF between Japanese and Caucasian male subjects after multiple inhalations of IND/GLY/MF o.d.

METHODS

This was a single-center, open-label, 2-treatment crossover study with a 21-day washout period. Japanese and Caucasian subjects received IND/GLY/MF 150/50/80 μg (inhaled corticosteroid [ICS] medium-dose) or 150/50/160 μg o.d. (ICS high-dose) for 14 days in each period. Pharmacokinetics were characterized up to 24 h post-dose on Days 1 and 14.

RESULTS

In total, 16 Japanese (median age 31 years [range 20-40 years], mean weight 68.3 kg) and 17 Caucasian subjects (median age 27 years [range 21-43 years], mean weight 75.0 kg) were randomized. Geometric mean ratios (Japanese/Caucasian) [90% confidence interval (CI)] for Cmax for IND, GLY and MF at the high ICS dose on Day 14 were 1.31 [1.13, 1.51] 1.38 [1.13, 1.69] and 1.07 [0.969, 1.18], respectively. Geometric mean ratios (Japanese/Caucasian) [90% CI] for AUC0-24h on Day 14 for IND, GLY and MF at the high ICS dose were 1.17 [1.01, 1.35], 1.05 [0.920, 1.20] and 1.15 [1.05, 1.27] respectively. Similar trends were noted for all components for the medium ICS dose treatment. IND/GLY/MF was safe and well tolerated; no AEs suspected to be study drug-related were observed.

CONCLUSION

Pharmacokinetics of IND, GLY and MF (high and medium dose) when delivered as a fixed-dose combination were comparable between Japanese and Caucasian subjects. The IND/GLY/MF combination at the administrated doses was safe and well tolerated in both ethnic groups.

TRIAL REGISTRATION

Japan Registry of Clinical Trial: jRCT2031200227, retrospectively registered on 04, December, 2020.

Efficacy Comparison for a Schizophrenia and a Dysuria Drug Among East Asian Populations: A Retrospective Analysis Using Multi-regional Clinical Trial Data

BACKGROUND AND OBJECTIVES

Multi-regional clinical trials (MRCTs) are an efficient drug development strategy for eliminating drug lag in East Asian countries. In planning MRCTs according to the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use E17 guideline, it is expected that East Asian populations with relatively similar ethnicity can be pooled as one population. However, evidence supporting this assumption is limited. This study aimed to investigate population/regional differences considering influencing factors among East Asian regions using MRCT data as a research model.

METHODS

A retrospective analysis was conducted to determine the efficacy of two drugs, asenapine, a schizophrenia drug, and tadalafil, a dysuria drug for benign prostatic hyperplasia, using MRCT data from Japan, Korea, and Taiwan. First, predictive factors and effect modifiers were evaluated. Then, population/regional differences were evaluated using multivariate regression models, with the interaction term Region-by-Treatment group and adjustment for influencing intrinsic/extrinsic factors.

RESULTS

Among the 4 outcomes for the two drugs, no significant population/regional differences were detected (P > 0.05) by the adjusted regression models. The effect modifiers, such as pretreatment drug status or concurrent diseases, were common among countries.

CONCLUSIONS

No significant population/regional efficacy differences were found for the two drugs among the three regions. This finding supported the possible applicability of the region pooling strategy for MRCTs in East Asia, emphasizing the benefits of exploring ethnic difference/influencing factors at an early stage to design further confirmatory studies. However, further evidence for various drugs should be accumulated.

Physiologically Based Pharmacokinetic/Pharmacodynamic Modeling to Predict the Impact of CYP2C9 Genetic Polymorphisms, Co-Medication and Formulation on the Pharmacokinetics and Pharmacodynamics of Flurbiprofen

Physiologically based pharmacokinetic/pharmacodynamic (PBPK/PD) models can serve as a powerful framework for predicting the influence as well as the interaction of formulation, genetic polymorphism and co-medication on the pharmacokinetics and pharmacodynamics of drug substances. In this study, flurbiprofen, a potent non-steroid anti-inflammatory drug, was chosen as a model drug. Flurbiprofen has absolute bioavailability of ~95% and linear pharmacokinetics in the dose range of 50–300 mg. Its absorption is considered variable and complex, often associated with double peak phenomena, and its pharmacokinetics are characterized by high inter-subject variability, mainly due to its metabolism by the polymorphic CYP2C9 (fmCYP2C9 ≥ 0.71). In this study, by leveraging in vitro, in silico and in vivo data, an integrated PBPK/PD model with mechanistic absorption was developed and evaluated against clinical data from PK, PD, drug-drug and gene-drug interaction studies. The PBPK model successfully predicted (within 2-fold) 36 out of 38 observed concentration-time profiles of flurbiprofen as well as the CYP2C9 genetic effects after administration of different intravenous and oral dosage forms over a dose range of 40–300 mg in both Caucasian and Chinese healthy volunteers. All model predictions for C_max, AUC_inf and CL/F were within two-fold of their respective mean or geometric mean values, while 90% of the predictions of C_max, 81% of the predictions of AUC_inf and 74% of the predictions of Cl/F were within 1.25 fold. In addition, the drug-drug and drug-gene interactions were predicted within 1.5-fold of the observed interaction ratios (AUC, C_max ratios). The validated PBPK model was further expanded by linking it to an inhibitory E_max model describing the analgesic efficacy of flurbiprofen and applying it to explore the effect of formulation and genetic polymorphisms on the onset and duration of pain relief. This comprehensive PBPK/PD analysis, along with a detailed translational biopharmaceutic framework including appropriately designed biorelevant in vitro experiments and in vitro-in vivo extrapolation, provided mechanistic insight on the impact of formulation and genetic variations, two major determinants of the population variability, on the PK/PD of flurbiprofen. Clinically relevant specifications and potential dose adjustments were also proposed. Overall, the present work highlights the value of a translational PBPK/PD approach, tailored to target populations and genotypes, as an approach towards achieving personalized medicine.

Exploring pharmacogenetic difference using adverse event database: an example of clopidogrel and cardiovascular events

Background: Poor clopidogrel metabolizers, carrying a cytochrome P450 2C19 loss-of-function allele, are more frequent among East Asians than Caucasians/White. Materials & methods: The Korea adverse event reporting system database and a case/noncase study design were used to examine the disproportionality of cardiovascular events following clopidogrel use. The US FDA's adverse event reporting system database was also analyzed for comparison. Results: In the Korea adverse event reporting system data, the clopidogrel reporting odds ratio for cardiovascular events was 7.34, more than double that of ticagrelor. In the FDA's adverse event reporting system data, the clopidogrel reporting odds ratio was 4.69, lower than that of ticagrelor. Adjustment for covariates did not change the trend. Conclusion: Considering the prevalence of poor clopidogrel metabolizers and the reported cardiovascular events among Koreans, rigorous clinical management is required for clopidogrel users.

Multiple-Dose Pharmacokinetics, Safety, and Tolerability of Aprocitentan, a Dual Endothelin Receptor Antagonist, in Healthy Japanese and Caucasian Subjects

Aprocitentan is an orally active dual endothelin receptor antagonist currently in development for treatment of difficult-to-control (resistant) hypertension. In phase 1 and 2 studies, aprocitentan has been characterized predominantly in Caucasian subjects. In this bridging, double-blind study, 20 healthy Japanese and Caucasian male and female subjects received 25 mg of aprocitentan or placebo once daily for 10 days and were monitored until 216 hours after the last dosing. The pharmacokinetics of aprocitentan were similar between ethnicities. At steady state, maximum plasma concentration was reached at 4 and 3 hours, and elimination half-life was 49.1 and 48.8 hours for Japanese and Caucasian subjects, respectively. The accumulation index was around 3 for both populations. Geometric means ratios for maximum plasma concentration and area under the plasma concentration-time curve during 1 dosing interval were around 1, with 90% confidence interval ranging from 0.87 to 1.30. Aprocitentan was safe and well tolerated in both groups. As no clinically relevant differences were found between Japanese and Caucasian subjects, it is unlikely that the pharmacokinetics of aprocitentan would differ significantly between Caucasian subjects and other ethnicities. Aprocitentan can therefore be administered at a dose level of up to 25 mg in any ethnicity without dose adjustment.

Racial disparities and cardiovascular disease: One size fits all approach?

BACKGROUND

Despite recent advancements in prevention, treatment, and management options, cardiovascular diseases contribute to one of the leading causes of morbidity and mortality. Several studies highlight the compelling evidence for the existence of healthcare inequities and disparities in the treatment and management control of cardiovascular diseases.

AIMS

To explore the role of racial disparities in the treatment of various cardiovascular diseases, highlighting the role of socioeconomic and cultural factors, and ultimately postulate solutions to eliminate the disparities.

METHODS

A comprehensive review of the literature was conducted using appropriate keywords on search engines of SCOPUS, Wiley, PubMed, and SAGE Journals.

CONCLUSION

By continued research to eliminate healthcare inequalities, there exists a potential to improve health-related outcomes in minority populations.

Serum interleukin-18 levels as a predictor for patients with genetic dysfunction of cytochrome P450 2C19 in dual antiplatelet therapy with clopidogrel

BACKGROUND

P2Y₁₂ reaction unit (PRU) is an index of platelet activity upon treatment with clopidogrel. In spite of suitable P2Y₁₂ reactions in dual antiplatelet therapy (DAPT) with clopidogrel after percutaneous coronary intervention (PCI), cardiovascular events actually occur in some patients, possibly due to a genetic dysfunction of cytochrome P450 2C19 (CYP2C19), which is a major metabolic enzyme of clopidogrel. As testing the CYP2C19 phenotypes to predict such patients may lack general versatility in daily clinical practice, the aim of this study was to examine whether measuring the blood levels of some cytokines in patients showing desirable PRUs in DAPT with clopidogrel could be a substitute for testing the CYP2C19 phenotypes.

METHODS

We analyzed relationships among PRU, serum levels of 51 cytokines, and CYP2C19 phenotypes in 22 patients receiving DAPT with aspirin and clopidogrel after PCI.

RESULTS

Seventeen, 18, and 19 of 22 patients indicated PRU ≤ 208, PRU ≤ 230, and PRU ≤ 262, respectively. Approximately 60% of the patients had a genetically metabolic dysfunction of CYP2C19, and the serum levels of interleukin-18 were independently increased in those patients (p = 0.024 in patients with PRU ≤ 208, p = 0.021 with PRU ≤ 230, and p = 0.020 with PRU ≤ 262). The area under the curves in plot receiver operating characteristics curves for the serum levels of interleukin-18 were 0.94, 0.96, and 0.90 in the non-extensive metabolizer patients with PRU ≤ 208, PRU ≤ 230, and PRU ≤ 262, respectively.

CONCLUSIONS

The serum levels of interleukin-18 may be a predictor to diagnose patients who receive undesirable DAPT with clopidogrel, possibly due to the genetic dysfunction of CYP2C19 in spite of suitable P2Y₁₂ reactions after PCI.

Metabolic Pathway Analysis and Effectiveness of Tamoxifen in Danish Breast Cancer Patients

BACKGROUND

Tamoxifen and its metabolites compete with estrogen to occupy the estrogen receptor. The conventional dose of adjuvant tamoxifen overwhelms estrogen in this competition, reducing breast cancer recurrence risk by nearly half. Phase I metabolism generates active tamoxifen metabolites, and phase II metabolism deactivates them. No earlier pharmacogenetic study has comprehensively evaluated the metabolism and transport pathways, and no earlier study has included a large population of premenopausal women.

METHODS

We completed a cohort study of 5,959 Danish nonmetastatic premenopausal breast cancer patients, in whom 938 recurrences occurred, and a case-control study of 541 recurrent cases in a cohort of Danish predominantly postmenopausal breast cancer patients, all followed for 10 years. We collected formalin-fixed paraffin-embedded tumor blocks and genotyped 32 variants in 15 genes involved in tamoxifen metabolism or transport. We estimated conventional associations for each variant and used prior information about the tamoxifen metabolic path to evaluate the importance of metabolic and transporter pathways.

RESULTS

No individual variant was notably associated with risk of recurrence in either study population. Both studies showed weak evidence of the importance of phase I metabolism in the clinical response to adjuvant tamoxifen therapy.

CONCLUSIONS

Consistent with prior knowledge, our results support the role of phase I metabolic capacity in clinical response to tamoxifen. Nonetheless, no individual variant substantially explained the modest phase I effect on tamoxifen response.

IMPACT

These results are consistent with guidelines recommending against genotype-guided prescribing of tamoxifen, and for the first time provide evidence supporting these guidelines in premenopausal women.

Prasugrel effectively reduces the platelet reactivity units in patients with genetically metabolic dysfunction of cytochrome P450 2C19 who are treated with long-term dual antiplatelet therapy after undergoing drug-eluting stent implantation

Dual antiplatelet therapy (DAPT) with aspirin and P2Y12 inhibitor is administered following percutaneous coronary intervention (PCI) with coronary stent implantation. Several studies have reported the effects of switching between P2Y12 inhibitors on platelet reactivity (P2Y12 reaction units: PRU), from acute to late phase after PCI. However, the effect of switching at very late phase is unknown. This study examined the effect on PRU in Japanese coronary heart disease patients with long-term DAPT (aspirin + clopidogrel) when switching from clopidogrel to prasugrel. Ninety-six patients were enrolled in this study. The median DAPT duration at enrollment was 1824.0 days. Twenty-three patients with PRU ≥ 208 at enrollment were randomly assigned into either continuing to receive clopidogrel (Continued Group; n = 11) or switching to prasugrel (Switched Group; n = 12). The primary endpoint was the rate of patients who achieved PRU < 208 at the end of 12 weeks of treatment, which was significantly higher in Switched Group relative to Continued Group (90.0% vs. 36.4%; P = 0.024). The secondary endpoint was the PRU at week 12 in groups subdivided according to cytochrome P450 (CYP) 2C19 genotypes. At week 12, extensive metabolizers (EM Group) had 202.3 ± 60.0 and 174.5 ± 22.3 in Continued Group and Switched Group (P = 0.591), respectively; intermediate and poor metabolizers (non-EM Group) had 229.4 ± 36.9 and 148.4 ± 48.4 in Continued Group and Switched Group (P = 0.002), respectively. The PRU for non-EM Group was significantly reduced in Switched Group. Thus, for patients with long-term DAPT (aspirin + clopidogrel) after PCI with coronary stent implantation, switching from clopidogrel to prasugrel resulted in a stable reduction in PRU, regardless of CYP2C19 polymorphism.

Evaluation of the Pharmacokinetics, Safety, and Tolerability of a Single Oral Dose of Pyrimethamine in Healthy Male Subjects of Japanese and European Ancestry

The pharmacokinetics of pyrimethamine have been evaluated in various populations but have not been reported in subjects of Japanese ancestry following administration as a single-agent tablet. Furthermore, although pyrimethamine pharmacokinetics after a single dose of the single-agent tablet studied in Western countries have been reported, these studies are old, and the ancestry of the subjects was not specified. Consequently, this study investigated the pharmacokinetics and safety of a single oral 50-mg dose of pyrimethamine in healthy male subjects of Japanese and European ancestry. Seven subjects of each ancestry group were administered pyrimethamine, along with calcium folinate. After absorption, pyrimethamine was eliminated, with a mean half-life of 122.8 hours in Japanese subjects and 99.5 hours in European subjects. The mean C_max and AUC_0-t were 433.8 ng/mL and 59.63 µg·h/mL in Japanese subjects and 372.7 ng/mL and 42.83 µg·h/mL in European subjects. No safety concerns were reported during the study. Although pyrimethamine exposure was slightly higher in subjects of Japanese than of European ancestry, a considerable overlap in the range of parameter values was observed. Considering the range of pyrimethamine exposure reported previously, difference in exposure observed in this study would not be considered of note.

New paradigm for expediting drug development in Asia

Some Asian regulators currently require Phase I data in Asians before joining global Phase II/III trials. Here, we discuss inherent limitations of Phase I ethnic sensitivity studies (ESS) to identify potential interethnic differences. We review recent new drug applications (NDAs) for Japan and China to critically assess the value of separate ESSs in Asian populations. Given that the observed value of ESS was limited, we propose a new global drug development paradigm: if relevant safety, pharmacokinetic (PK), and pharmacogenetic (PG) data are available from the original Phase I study population, it might be possible to extrapolate those data to Asian populations for their inclusion in Phase II/III trials, without an ESS. This could help to streamline drug development in Asia while still addressing regulatory requirements.

Safety, pharmacokinetics and pharmacodynamics of the selective glucocorticoid receptor modulator AZD7594, following inhalation in healthy Japanese volunteers

Introduction

AZD7594 is a non-steroidal, selective, glucocorticoid receptor modulator (SGRM), currently in development for the treatment of asthma and chronic obstructive pulmonary disease. This paper reports a randomized placebo-controlled dose escalation study in healthy Japanese male subjects.

Methods

Inhaled AZD7594 was administered as one single dose at day 1 (day 1-4), with subsequent multiple daily doses (day 5-16) via a multiple-dose dry powder inhaler for 12 days of once-daily treatment. At each dose level, subjects were randomized to AZD7594 (n=7) or placebo (n=2). The safety, pharmacokinetics (PK) and pharmacodynamics (PD) of AZD7594 were evaluated.

Results

Inhaled AZD7594 was safe and well tolerated up to and including the highest dose 1600 µg tested. Plasma exposure suggested dose-proportional PK. The urinary excretion of AZD7594 was negligible (<0.02%). Dose-related effects were observed for 24 hrs plasma cortisol; however, significant cortisol suppression (25%) was only seen at the highest dose level following multiple doses. There were no or only marginal effects on other biomarkers tested (dehydroepiandrosterone sulfate [DHEA-S] and osteocalcin).

Conclusion

In conclusion, the early clinical evaluation of inhaled AZD7594 suggests that this novel SGRM is well tolerated in the dose range investigated and also in a Japanese population. It shows dose-proportional plasma exposure, moderate accumulation and has limited impact on systemic markers of glucocorticoid activity.

Phase 1 Dose-Escalation Study to Evaluate the Pharmacokinetics, Safety, and Tolerability of Tofacitinib in Japanese Healthy Volunteers

The aim of the study was to characterize the pharmacokinetics, safety, and tolerability of tofacitinib, an oral Janus kinase inhibitor for the treatment of rheumatoid arthritis, psoriatic arthritis, and ulcerative colitis in healthy Japanese volunteers, and to compare these outcomes with those of healthy Western volunteers. Twenty‐five volunteers (Japanese, n = 16; Western [white], n = 9) were randomized to receive either 3 escalating single doses of tofacitinib (1, 5, and 30 mg), single‐dose tofacitinib (15 mg) followed by multiple doses (15 mg twice daily for 5 days), or placebo. No significant differences in systemic exposure to tofacitinib were detected between the 2 ethnicities. Following single tofacitinib 1, 5, and 30 mg doses, mean area under the plasma concentration–time curve from time zero to infinity ratio (Japanese/Western) values were 96.6%, 93.5%, and 95.6%, respectively. Similarly, mean maximum observed plasma concentration ratio values were 99.5%, 118%, and 119%, respectively. Mean renal clearance was also similar, ranging across doses from 134 mL/min (5 mg) to 162 mL/min (1 mg) in Japanese volunteers, and 124 mL/min (30 mg) to 160 mL/min (1 mg) in Western volunteers. In both ethnicities, most adverse events were mild. No serious adverse events or deaths were reported. The pharmacokinetics of tofacitinib were well characterized in healthy Japanese volunteers and were similar to those in Western volunteers.

Efficacy and Safety of Palbociclib and Fulvestrant in Japanese Patients With ER+/HER2- Advanced/Metastatic Breast Cancer

BACKGROUND/AIM

Published data have shown that palbociclib-fulvestrant can significantly improve the progression-free survival (PFS) of estrogen receptor-positive/human epidermal growth factor receptor 2-negative (ER+/HER2-) metastatic breast cancer patients, but not of Japanese patients. We conducted this retrospective study to verify the efficacy and safety of palbociclib-fulvestrant in Japanese patients.

PATIENTS AND METHODS

ER+/HER2- metastatic breast cancer patients treated with fulvestrant (n=39) or palbociclib-fulvestrant (n=31) at the Saitama Medical Center from July 2012 to November 2018 were evaluated.

RESULTS

Overall response rates (ORRs) were 2.6% (fulvestrant) and 41.9% (palbociclib-fulvestrant) (p<0.001), and clinical benefit rates (CBRs) were 23.1% and 61.3% (p=0.002), respectively. The palbociclib-fulvestrant group had significantly higher CBR and PFS (hazard ratio(HR):0.272, 95% confidence interval(95CI):0.128-0.574 for PFS). Grade 3/4 neutropenia occurred in 80.6% of the palbociclib-fulvestrant group, while febrile neutropenia was not detected.

CONCLUSION

Japanese ER+/HER2- metastatic breast cancer patients tolerated palbociclib-fulvestrant, with significantly improved clinical outcomes.

Development of a Korean-specific virtual population for physiologically based pharmacokinetic modelling and simulation

Physiologically based pharmacokinetic (PBPK) modelling and simulation is a useful tool in predicting the PK profiles of a drug, assessing the effects of covariates such as demographics, ethnicity, genetic polymorphisms and disease status on the PK, and evaluating the potential of drug-drug interactions. We developed a Korean-specific virtual population for the SimCYP® Simulator (version 15 used) and evaluated the population's predictive performance using six substrate drugs (midazolam, S-warfarin, metoprolol, omeprazole, lorazepam and rosuvastatin) of five major drug metabolizing enzymes (DMEs) and two transporters. Forty-three parameters including the proportion of phenotypes in DMEs and transporters were incorporated into the Korean-specific virtual population. The simulated concentration-time profiles in Koreans were overlapped with most of the observed concentrations for the selected substrate drugs with a < 2-fold difference in clearance. Furthermore, we found some drug models within the SimCYP® library can be improved, e.g., the minor allele frequency of ABCG2 and the fraction metabolized by UGT2B15 should be incorporated for rosuvastatin and lorazepam, respectively. The Korean-specific population can be used to evaluate the impact of ethnicity on the PKs of a drug, particularly in various stages of drug development.

Frequency of the CYP2C19*17 polymorphism in a Chilean population and its effect on voriconazole plasma concentration in immunocompromised children

Invasive fungal infections (IFIs) are the most frequent cause of morbidity and mortality in immunocompromised children. Voriconazole is the first-line antifungal choice in the treatment of IFIs like aspergillosis. Voriconazole pharmacokinetics vary widely among patients and voriconazole is metabolized mainly in the liver by the CYP2C19 enzyme, which is highly polymorphic. The CYP2C19*17 allele is characterized by the presence of four single nucleotide polymorphisms expressing an ultra-rapid enzyme phenotype with an accelerated voriconazole metabolism, is associated with low (sub-therapeutic) plasma levels in patients treated with the standard dose. Considering that in our center a high percentage of children have sub-therapeutic levels of voriconazole when treated with standard doses, we sought to determine the frequency of the CYP2C19*17 polymorphism (rs12248560) in a Chilean population and determine the association between voriconazole concentrations and the rs12248560 variant in immunocompromised children. First, we evaluated the frequency of the rs12248560 variant in a group of 232 healthy Chilean children, and we found that 180 children (77.6%) were non-carriers of the rs12248560 variant, 49 children (21.1%) were heterozygous carriers for rs12248560 variant and only 3 children (1.3%) were homozygous carriers for rs12248560 variant, obtaining an allelic frequency of 12% for variant in a Chilean population. To determine the association between voriconazole concentrations and the rs12248560 variant, we analyzed voriconazole plasma concentrations in a second group of 33 children treated with voriconazole. In these patients, carriers of the rs12248560 variant presented significantly lower voriconazole plasma concentrations than non-carriers (p = 0,011). In this study, we show the presence of the rs12248560 variant in a Chilean population and its accelerating effect on the pharmacokinetics of voriconazole in pediatric patients. From these data, it would be advisable to consider the variant of the patient prior to calculating the dosage of voriconazole.

Effect of itraconazole, food, and ethnic origin on the pharmacokinetics of ivosidenib in healthy subjects

PURPOSE

To assess the effect of ethnicity, food, and itraconazole (strong CYP3A4 inhibitor) on the pharmacokinetics of ivosidenib after single oral doses in healthy subjects.

METHODS

Three phase 1 open-label studies were performed. Study 1: Japanese and Caucasian subjects received single doses of 250, 500, or 1000 mg ivosidenib (NCT03071770). Part 1 of study 2 (a two-period crossover study): subjects received 500 mg ivosidenib after either an overnight fast or a high-fat meal. Subjects received 1000 mg ivosidenib after an overnight fast in the single period of part 2 (NCT02579707). Study 3: in period 1, subjects received 250 mg ivosidenib; then, in period 2, subjects received oral itraconazole (200 mg once daily) on days 1-18, plus 250 mg ivosidenib on day 5 (NCT02831972).

RESULTS

Ivosidenib was well tolerated in all three studies. Study 1: pharmacokinetic profiles were generally comparable, although AUC and C_max were slightly lower in Japanese subjects than in Caucasian subjects, by ~ 30 and 17%, respectively. Study 2: AUC increased by ~ 25% and C_max by ~ 98%, when ivosidenib was administered with a high-fat meal compared with a fasted state. Study 3: co-administration of itraconazole increased ivosidenib AUC by 169% (90% CI 145-195) but had no effect on ivosidenib C_max.

CONCLUSIONS

No ivosidenib dose adjustment is deemed necessary for Japanese subjects. High-fat meals should be avoided when ivosidenib is taken with food. When co-administered with strong CYP3A4 inhibitors, monitoring for QT interval prolongation (a previously defined adverse event of interest) is recommended and an ivosidenib dose interruption or reduction may be considered. CLINICALTRIALS.GOV : NCT03071770, NCT02579707, and NCT02831972.

A post hoc analysis of the long-term safety and efficacy of perampanel in Asian patients with epilepsy

This post hoc analysis assessed the long-term safety, tolerability, and efficacy of perampanel in Asian patients with refractory focal seizures; an additional analysis assessed the effect of perampanel on focal impaired awareness seizures (FIAS) with focal to bilateral tonic-clonic (FBTC) seizures. In this subanalysis, data from Asian patients ≥12 years of age who had focal seizures with FBTC seizures despite taking one to 3 concomitant antiepileptic drugs at baseline, and who had entered either the long-term extension phase of 3 phase-3 perampanel trials (study 307) or the 10-week extension phase of study 335, were analyzed for the effect of perampanel on duration of exposure, safety, and seizure outcomes. Of 874 Asian patients included in the analysis, 205 had previously received placebo during the double-blind phase-3 trials and 669 had previously received perampanel 2-12 mg/day; 313 had FIAS with FBTC seizures at core study baseline. The median duration of exposure to perampanel was 385.0 days, and the retention rate at one year was 62.6%. Overall, during the first 52 weeks of perampanel treatment, 777 patients (88.9%) had treatment-emergent adverse events (TEAEs), most of which were mild to moderate in severity. The most frequent TEAEs were dizziness (47.1%), somnolence (22.3%), and nasopharyngitis (17.4%). During the first 52 weeks of perampanel treatment, median percent change in seizure frequency per 28 days from pre-perampanel baseline for all focal seizures was -28.1%, and -51.7% for FIAS with FBTC seizures. The 50% responder rate relative to pre-perampanel baseline for all focal seizures was 33.8%, and 51.1% for FIAS with FBTC seizures. Long-term treatment with perampanel in Asian patients had safety, tolerability, and efficacy similar to that of the global population in the phase-3 trials and extension study 307. The safety profile and response rate suggest benefit for an Asian population of patients with refractory epilepsy.

Population/regional differences in efficacy of 3 drug categories (antidiabetic, respiratory and psychotropic agents) among East Asians: A retrospective study based on multiregional clinical trials

AIMS

This study aimed to identify population/regional differences in drug efficacy and the influencing factors among East Asians to be considered when planning multiregional clinical trials (MRCTs) to facilitate rapid drug approval in Asians.

METHODS

A retrospective analysis of efficacy (intergroup difference in endpoint between control and study drug treatment) among East Asian populations for 3 drug categories, antidiabetic, respiratory and psychotropic agents, was conducted in collaboration with pharmaceutical companies using their MRCT data. Common endpoints by drug category were selected; background factors that commonly affected the endpoints among regions were analysed first; then the population/regional differences were evaluated by the interaction term region-by-treatment using an analysis of covariance model after adjusting for background factors.

RESULTS

Among 17 endpoints for eight pharmaceutical products from 3 drug categories, no substantial population/regional differences were detected in the 3 drug categories examined (P > .05), except for haemoglobin A1c change between Japan and Korea for an antidiabetic drug, insulin glulisine (P = .0068). However, no such regional differences were evident in patients with clinically important higher haemoglobin A1c baseline values (majority subgroup). Variability in disease severity at baseline and concomitant drugs were determined to be potential influencing factors for regional differences.

CONCLUSIONS

This study suggests that the regional variability in efficacy of these 3 drug categories is not large among East Asians, and reveals the importance of considering background factors when planning MRCTs. Further studies are needed to evaluate regional variability in the efficacy of other drug categories and clarify the factors leading to regional differences in East Asians.

Ataluren Pharmacokinetics in Healthy Japanese and Caucasian Subjects

To evaluate the potential for ethnicity-related differences in ataluren pharmacokinetics (PK) and safety, a phase 1 single-dose study was conducted in 48 healthy (24 Japanese and 24 Caucasian subjects), nonsmoking male volunteers who were equally divided into 3 cohorts of oral doses at 5, 10, and 20 mg/kg. Blood samples were collected until 48 hours postdose. PK results demonstrated rapid absorption of ataluren, with peak plasma levels (C_max ) being attained between 0.875 and 2.5 hours after dosing. The mean C_max and area under the concentration-time curve (AUC_(0-last) ) increased with each increasing dose level in both Japanese and Caucasian subjects. Although the C_max was similar across all subjects at each dose regardless of ethnicity, Japanese subjects had a mean AUC_(0-last) approximately 14% to 34% lower than that of Caucasian subjects across the 3 dose levels. This difference was likely due to the higher variability of AUC values in Caucasian subjects and the relatively small study population. In conclusion, similar ataluren PK profiles were observed in healthy Japanese and Caucasian subjects following single oral administration of ataluren at all dose levels.

Palbociclib in combination with letrozole in patients with estrogen receptor-positive, human epidermal growth factor receptor 2-negative advanced breast cancer: PALOMA-2 subgroup analysis of Japanese patients

Background

In PALOMA-2, palbociclib–letrozole significantly improved progression-free survival (PFS) vs placebo–letrozole in women with estrogen receptor–positive, human epidermal growth factor receptor 2–negative (ER+/HER2–) advanced breast cancer (ABC) in the first-line setting. We evaluated the efficacy, safety, and pharmacokinetics of palbociclib in Japanese women in PALOMA-2.

Methods

In this phase 3 study, 666 postmenopausal women with ER+/HER2– ABC were randomized 2:1 to palbociclib (125 mg/day [3 weeks on/1 week off]) plus letrozole (2.5 mg daily) or placebo plus letrozole. A prespecified, exploratory, subgroup analysis of Japanese patients (n = 46) was conducted to compare results with those of the overall population.

Results

At the February 26, 2016 cutoff, median PFS among the 46 Japanese patients was 22.2 months (95%CI, 13.6‒not estimable) with palbociclib–letrozole vs 13.8 months (5.6‒22.2) with placebo–letrozole (hazard ratio, 0.59 [95%CI, 0.26−1.34]). The most common adverse events (AEs) were hematologic and more frequent among Japanese patients than the overall population (neutropenia: 93.8% [87.5% grade 3/4] vs 79.5% [66.4%]; leukopenia: 62.5% [43.8%] vs 39.0% [24.8%]); no Japanese patients had febrile neutropenia. Palbociclib dose reductions due to toxicity (mainly neutropenia) were more common in Japanese patients (62.5% vs 36.0%); few permanently discontinued due to AEs. Although mean palbociclib trough concentration was higher in Japanese patients vs non-Asians (95.4 vs 61.7 ng/mL), the range of individual values of the Japanese patients was within that of non-Asians.

Conclusions

These results from PALOMA-2 suggest that palbociclib–letrozole merits consideration as a first-line treatment option for postmenopausal Japanese patients with ER+/HER2‒ ABC. ClinicalTrials.gov: NCT01740427.

Electronic supplementary material

The online version of this article (10.1007/s10147-018-1353-9) contains supplementary material, which is available to authorized users.