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Multiregional clinical trials (MRCTs) have become increasingly common during the development of new drugs to obtain simultaneous drug approvals worldwide. When planning MRCTs, a major statistical challenge is determination of the regional sample size. In general, the regional sample size must be determined as the sample size such that the regional consistency probability, defined as the probability of meeting the regional consistency criterion, is greater than a prespecified value. The Japanese Ministry of Health, Labour and Welfare proposed two criteria for regional consistency. Moreover, many researchers have proposed corresponding closed-form formulas for calculating regional consistency probabilities when the primary outcome is continuous. Although some researchers have argued that those formulas are also applicable to cases with binary outcomes, it remains questionable whether such an argument can be true. Based on simulation results, we demonstrate that the existing formulas are inappropriate for binary cases, even when the regional sample size is sufficiently large. To address this issue, we develop alternative formulas and use simulation to show that they provide accurate regional consistency probabilities. Furthermore, we present an application of our proposed formulas for an MRCT of advanced or metastatic clear-cell renal cell carcinoma., (© 2023 John Wiley & Sons Ltd.)

With recent advances in medical treatments for carotid artery stenosis (CS), indications for carotid surgery should be more carefully considered for asymptomatic CS (ACS). Accurate stratification of ACS should be based on the risk of cerebral infarction, and subgroups of patients more likely to benefit from surgical treatment should be differentiated. Magnetic resonance imaging (MRI) offers a non-invasive, accurate modality for characterizing carotid plaque. Intraplaque hemorrhage (IPH) seems the most promising feature of vulnerable plaque detectable by MRI. Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is a type II membrane protein of the C-type lectin family with an extracellular domain that can be proteolytically cleaved and released as a soluble form (sLOX-1). This sLOX-1 plays a key role in the pathogenesis of atherosclerosis, and elevated sLOX-1 concentrations correlate with thin or ruptured fibrous caps in patients with acute coronary syndrome. This ongoing study aims to clarify the incidence of ischemic stroke in patients with ACS and IPH confirmed by MRI, and to assess whether sLOX-1 could provide a biomarker for risk of future ischemic events. The study population comprises patients with ACS (>60% area stenosis) associated with MRI-diagnosed IPH receiving follow-up under medical treatment. Primary endpoints comprise transient ischemic attack, stroke or amaurosis resulting from concerned CS. Secondary endpoints comprise any stroke or surgical treatment for progressive luminal stenosis. The target number of patients is 120 and the observational period is 36 months. The study results could help identify individuals with ACS who are refractory to medical therapy.

Effects of intensive versus conventional therapy on the primary and secondary outcomes., (© 2018 The Authors. Journal of Diabetes Investigation published by Asian Association for the Study of Diabetes (AASD) and John Wiley & Sons Australia, Ltd.)

Clinical data on various ethnicities collected in multiregional clinical trials (MRCTs) have increased in regulatory review for drug approval. However, how such data should be included on the drug labels has not been discussed. We compared information related to ethnicities on the labels of drugs that were approved in both Japan and the United States, and discussed the issues to be considered for providing better information to healthcare professionals in this era of globalized drug development., (© 2015 The American Society for Clinical Pharmacology and Therapeutics.)

Multiregional clinical trials including Japanese subjects are playing a key role in new drug development in Japan. In addition to the consideration of differences in intrinsic and extrinsic ethnic factors, deciding the sample size of Japanese subjects is an important issue when a multiregional clinical trial is intended to be used for Japanese submission. Accumulated experience suggests that there are several points to consider, such as the basic principles described in the guidance document, drug development strategy, trial phase, and disease background. The difficulty of interpreting the results of Japanese trials should also be considered.

Multiregional clinical trials provide the potential to make safe and effective medical products simultaneously available to patients globally. As regulatory decisions are always made in a local context, this poses huge regulatory challenges. In this article we propose two conditional decision rules that can be used for medical product approval by local regulatory agencies based on the results of a multiregional clinical trial. We also illustrate sample size planning for such trials.

The 11th question-and-answer document (Q&A) for ICH E5 (1998) was published in 2006. This Q&A describes points to consider for evaluating the possibility of bridging among regions by a multiregional trial. The primary objective of a multiregional bridging trial is to show the overall efficacy of a drug in all participating regions while also evaluating the possibility of applying the overall trial results to each region. To apply the overall results to a specific region, it suggested that the results in that region should be consistent with the overall results. The Japanese Ministry of Health, Labor, and Welfare (MHLW) published the "Basic Principles on Global Clinical Trials" guidance document (2007) and proposed two methods to support the bridging claims. Due to the limited sample sizes allocated to the region, the regular interaction test for treatment by region is not practical. On the other hand, the sample size requirement for the Japanese region as described in Uyama et al. (2005) and Uesaka (2009) is to satisfy an 80% or greater power for the Japanese region, conditioning on the effect of the overall global trial. Quan et al. (2010) further extended the results to trials with various endpoints. Ko, Tsou, Liu and Hsiao (2010) focused on a specific region and established statistical criteria for consistency between the region of interest and overall results. The proposed method was based on the assumption that true effect size is uniform across regions. In this article, we propose to analyze a completed multiregional trial for any specific regional effect by controlling the type I error rate adjusted for the regional sample size and the planned power of the global trial. Accordingly, in order to attain the approval for a specific region, we propose to determine the sample size requirement for the specific regions using the overall power planned and a regional acceptable type I error rate.

In recent years, global collaboration has become a conventional strategy for new drug development. To accelerate the development process and shorten approval time, the design of multi-regional clinical trials (MRCTs) incorporates subjects from many countries/regions around the world under the same protocol. After showing the overall efficacy of a drug in a global trial, one can also simultaneously evaluate the possibility of applying the overall trial results to all regions and subsequently support drug registration in each region. However, most of the recent approaches developed for the design and evaluation of MRCTs focus on establishing criteria to examine whether the overall results from the MRCT can be applied to a specific region. In this paper, we use the consistency criterion of Method 1 from the Japanese Ministry of Health, Labour and Welfare (MHLW) guidance to assess whether the overall results from the MRCT can be applied to all regions. Sample size determination for the MRCT is also provided to take all the consistency criteria from each individual region into account. Numerical examples are given to illustrate applications of the proposed approach., (Copyright © 2012 John Wiley & Sons, Ltd.)

Investigator-initiated clinical trials are essential for improving the standard of care for cancer patients, because pharmaceutical companies do not conduct trials that evaluate combination chemotherapy using drugs from different companies, surgery, radiotherapy or multimodal treatments. Government-sponsored cooperative groups have played a vital role in developing cancer therapeutics since the 1950s in the USA; however, the establishment of these groups in Japan did not take place until 30 years later. Methodological standards for multicenter cancer clinical trials were established in the 1980s by the National Cancer Institute and cooperative groups. The Japan Clinical Oncology Group, one of the largest cooperative groups in the country, was instituted in 1990. Its data center and operations office, formed during the 1990s, applied the standard methods of US cooperative groups. At present, the Japan Clinical Oncology Group consists of 14 subgroups, a Data Center, an Operations Office, nine standing committees and an Executive Committee represented by the Japan Clinical Oncology Group Chair. Quality control and quality assurance at the Japan Clinical Oncology Group, including regular central monitoring, statistical methods, interim analyses, adverse event reporting and site visit audit, have complied with international standards. Other cooperative groups have also been established in Japan since the 1980s; however, nobody figures out all of them. A project involving the restructuring of US cooperative groups has been ongoing since 2005. Learning from the success of this project will permit further progress of the cancer clinical trials enterprise in Japan.

Background: Heart failure consists of two phenotypes: systolic heart failure and diastolic heart failure (DHF). A growing body of evidence demonstrated benefits of beta-blocker, angiotensin-converting enzyme inhibitor, and angiotensin II receptor blocker in systolic heart failure; however, evidence leading to therapeutic strategy of DHF is lacking., Methods and Results: The Japanese Diastolic Heart Failure Study (J-DHF) is a multicenter, prospective, randomized trial designed to assess effects of beta-blocker in patients with DHF. A total of 800 patients (400 patients in each group) will be enrolled. The primary outcome is a composite of cardiovascular death and unplanned admission to hospital for congestive heart failure. Other outcomes include all-cause mortality, worsening of the symptoms of heart failure, or a need for modification of the treatment for heart failure. Serial assessment of echocardiographic and neurohumoral parameters and cost analysis of the treatment regimen will be conducted. The follow-up period is a minimum of 2 years., Conclusion: This study will provide important evidences for the treatment of DHF.

Methodology to conduct phase I trials in the Early Clinical Trial Group (ECTG) in Europe was reviewed and compared with current status of the trials in Japan. Single dose acute toxicity studies and repeated dose toxicity studies were required in order to enter phase I trials in Europe, while in Japan those results and various other toxicity studies such as mutagenecity, carcinogenecity and reproductive toxicity were required. Since significant numbers of new anticancer drugs are dropped in the early stage of clinical investigations, it is recommended that unnecessary toxicological studies be avoided. Repeated administration and dose escalations in the same patients are allowed during phase I trials in ECTG, partly in consideration of the patient's desire to obtain antitumor effects. Dose intensity and quality of life are considered in order to decide the optimal dose and schedule in phase II trials.