A Bayesian approach based on discounting factor for consistency assessment in multi-regional clinical trial

Multi-regional clinical trial (MRCT) is an efficient design to accelerate drug approval globally. Once the global efficacy of test drug is demonstrated, each local regulatory agency is required to prove effectiveness of test drug in their own population. Meanwhile, the ICH E5/E17 guideline recommends using data from other regions to help evaluate regional drug efficacy. However, one of the most challenges is how to manage to bridge data among multiple regions in an MRCT since various intrinsic and extrinsic factors exist among the participating regions. Furthermore, it is critical for a local agency to determine the proportion of information borrowing from other regions given the ethnic differences between target region and non-target regions. To address these issues, we propose a discounting factor weighted Z statistic to adaptively borrow information from non-target regions. In this weighted Z statistic, the weight is derived from a discounting factor in which the discounting factor denotes the proportion of information borrowing from non-target regions. We consider three ways to construct discounting factors based on the degree of congruency between target and non-target regions either using control group data, or treatment group data, or all data. We use the calibrated power prior to construct discounting factor based on scaled Kolmogorov-Smirnov statistic. Comprehensive simulation studies show that our method has desirable operating characteristics. Two examples are used to illustrate the applications of our proposed approach.

Less participation by Japan in multi-regional clinical trials (MRCTs) is one of concerns that leads to drug loss in Japan, but the characteristics of Japan's participation in MRCTs have not been well studied. This study investigated Japan's situation in global drug development by characterizing its participation in MRCTs compared with East and South-East Asian countries/regions, with a focus on MRCTs sponsored by small-medium companies to discuss necessary measures in further promoting drug development in Japan. Data from MRCTs conducted in East and South-East Asia during the period from January 1, 2013 to December 31, 2022 were analyzed. Japan's participation in MRCTs conducted in Asia (East Asia and South-East Asia) was limited. In particular, Japan participated in only 15-16% of MRCTs sponsored by Small/Medium-pharma (mainly US-based companies), with even less participation in Early Phase MRCTs. Japan's participation in MRCTs was markedly lower than other Asian countries/regions such as Singapore, South Korea, and Taiwan, although it was relatively higher in MRCTs that targeted neoplasms compared with other diseases. Results of this study raise significant concern about future potential drug loss in Japan. It is urgent to increase the participation of Japan in MRCTs in order to continuously provide new globally developed drugs to patients in Japan. For that purpose, an integrated approach that includes continuous improvement in pharmaceutical regulations and the clinical trial environment, as well as market attractiveness, will be necessary in parallel with strengthening of collaborations between Japan and other Asian countries/regions.

Although the percentage of multi-regional clinical trials (MRCTs) submitted for drug approval in Japan increased significantly since the 2007 publication of the regulatory guideline, "Basic principles on global clinical trials", strategic collaborations between Asian countries will be important to promote MRCTs in accordance with the ICH E17 guideline published in 2017. In this study, characteristics of MRCTs reviewed for drug approval in Japan, especially those with participation by South-East Asia and East Asia, were investigated to explore opportunities for collaborations on global drug development in Asia. More than 90% of reviewed trials were conducted as global MRCTs. In addition to Japan, South-East Asia has participated in various types of MRCTs in terms of total numbers of subjects and countries. However, South-East Asia participation was lower in large-size MRCTs (total sample size ≥ 1000) than in middle- (500 ≤ total sample size < 1000) and small-size MRCTs (total sample size < 500). Furthermore, similar clinical trials for the same indications to the MRCTs without South-East Asia were rarely conducted separately in South-East Asia. Participation of other Asian countries did not affect the percentage of Japanese subjects enrolled in an MRCT, but did significantly increase the percentage of participating Asian subjects. These results suggest that additional opportunities for collaboration on MRCTs may be possible between Japan and other Asian countries, especially more collaborations with South-East Asia in the large-size MRCTs. More data of Asian populations from MRCTs will be useful for exploring an important ethnic factor affecting drug response, and will provide a sound scientific basis in considering the application of the pooled data concept in Asia, as described in the ICH E17 guideline.

The ICH E17 guidelines (2014-2017) on Multiregional Clinical Trials (MRCT) was a joint effort by the regulators and industry to facilitate simultaneous global drug development and registration through taking a strategic approach for clinical trials. In other words, the objective was to reduce the time it takes to bringing medications to patients around the world through minimizing unnecessary duplication of local or regional studies, which may add the regulatory burden to cost and time of bringing new therapies to patients. Under the auspices of ICH, training materials were created and provided to various stakeholders. Despite the successful promotion of the benefits of ICH E17 MRCT guidelines across the different regions, the uptake of some concepts (e.g., pooling strategy) in the ICH E17 guidelines has been slow. This paper describes various factors which could affect the conduct of MRCT at a global level, including ambiguity in definition of "region" (in MRCT), new regulatory requirements to enroll a diverse patient population, the use of decentralized clinical trials, use of data sources other than randomized clinical trials (e.g., use of Real Word Data), and the impact of the COVID-19 pandemic on the conduct of MRCT.

ABSTRACTMany methods have been proposed to account for the potential impact of ethnic/regional factors when extrapolating results from multiregional clinical trials (MRCTs) to targeted ethnic (TE) patients, i.e., “bridging.” Most of them either focused on TE patients in the MRCT (i.e., internal bridging) or a separate local clinical trial (LCT) (i.e., external bridging). Huang et al. (2012) integrated both bridging concepts in their method for the Simultaneous Global Drug Development Program (SGDDP) which designs both the MRCT and the LCT prospectively and combines patients in both trials by ethnic origin, i.e., TE vs. non-TE (NTE). The weighted Z test was used to combine information from TE and NTE patients to test with statistical rigor whether a new treatment is effective in the TE population. Practically, the MRCT is often completed before the LCT. Thus to increase the power for the SGDDP and/or obtain more informative data in TE patients, we may use the final results from the MRCT to re-evaluate initial assumptions (e.g., effect sizes, variances, weight), and modify the LCT accordingly. We discuss various adaptive strategies for the LCT such as sample size reassessment, population enrichment, endpoint change, and dose adjustment. As an example, we extend a popular adaptive design method to re-estimate the sample size for the LCT, and illustrate it for a normally distributed endpoint.

Proposal for the revision of guidelines for clinical trials of vaccines to prevent infectious diseases in Japan

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.

Drug time lags occur between the date that new drugs are first approved, often in the USA, and approval is granted in other countries. Multi-regional clinical trials (MRCTs) are a key strategy for simultaneous global development and regulatory submission of new drugs. However, no studies have evaluated the impact of MRCT versus local development on key time points in the drug development lifecycle between the USA and Japan. It is important for pharmaceutical companies planning drug development in Japan to understand when they can start development, when they can catch up in case of development initiation delay, length of time the development period might take, and amount of time that market exclusivity is lost, if Japan does not participate in the MRCT. The aim of this study was to investigate differences in drug lag in development initiation, New Drug Application (NDA) submission and drug approval, as well as differences in the development and review periods, by local trials and MRCTs between Japan and the USA. We also assessed the advantages and disadvantages of MRCTs for these lags in Japan. We analyzed drug approvals in Japan between 2016 and 2020 and divided them into local and MRCT groups. Lags in development initiation, NDA submission, and approval of new drugs were calculated by subtracting each date in Japan from the corresponding date in the USA. Our study period was divided into three periods based on the International Conference on Harmonization (ICH) E17 guideline, published in 2017, and the guideline for the Phase I trials in the Japanese population prior to MRCTs, published in 2014. In addition, subgroup analyses by therapeutic area, regulatory background, modality, capital style, and sales ranking (2020) were conducted. We analyzed 174 approvals in Japan and the USA. The differences in the drug lags for development initiation, NDA submission, and approval between the local and MRCT groups were 4.9, 3.5, and 3.2 years, respectively. All three lag times were shorter for the MRCT group than the local group. A development initiation lag in the local group has expanded since publication of the guidelines. For the people of Japan, important drug lags were identified in development initiation, NDA submission, and drug approval dates between local trials and MRCTs that include Japan. It is difficult to recover fully from the delay caused by local development, and it is important to understand the further expansion of drug lags, in cases where Japan is not involved in the MRCT.

It is important to recognize regional and racial differences in drug efficacy and safety when performing multi-regional clinical trials (MRCTs). To understand regional differences, we compared the efficacy results in Japanese patients and the overall population in the MRCTs of anticancer drugs. All new approvals of oncology drugs in Japan from January 2009 to December 2018 were searched using the Pharmaceuticals and Medical Devices Agency web site to find phase 3 MRCTs for the analysis. As the supporting data source, a literature search was performed in PubMed and Google Scholar. Linear regression analysis was performed and Pearson correlation coefficients (r) were calculated to compare the overall survival (OS), progression-free survival (PFS), and objective response rate (ORR) between Japanese patients and the overall population. Seventy MRCTs were identified. The correlation of hazard ratios (HRs) for OS between Japanese patients and the overall population was moderate (r = 0.45), and OS was 1.31 times longer in Japanese patients than in the overall population, although the correlation of median OS was strong (r = 0.91). The HRs for PFS were moderately correlated (r = 0.70) and the correlation of median PFS was strong (r = 0.90). The correlation of ORR was very strong (r = 0.96). The PFS and ORR were consistent between Japanese patients and the overall population. A longer median OS was observed in Japanese patients. Our results would be a useful reference when planning and conducting MRCTs that include Japan for global simultaneous drug development.

ABSTRACTThe primary objective of a multiregional clinical trial (MRCT) is to assess the efficacy of all participating regions and evaluate the probability of applying the overall results to a specific region. The consistency assessment of the target region with the overall results is the most common way of evaluating the efficacy in a specific region. Recently, Huang et al. (2012) proposed an additional trial in the target region to an MRCT to evaluate the efficacy in the target ethnic (TE) population under the framework of simultaneous global drug development program (SGDDP). However, the operating characteristics of this statistical framework were not well considered. Therefore, a nested group sequential program for regional efficacy evaluation is proposed in this paper. It is an extension of Huang’s SGDDP framework and allows interim analysis after MRCT and in the course of local clinical trial (LCT) phase. It is able to well control the family-wise type I error in the program level and enhances the flexibility of the program. In LCT sample size estimation, we introduce virtual trial, which is transformed from the original program by using discounting factor, and an iteration method is employed to calculate the sample size and stopping boundaries of interim analyses. The proposed sample size estimation method is validated in the simulations and the effect of varied weight, effect size of TE population, and design setting is explored. Examples with normal end point, binary end point, and survival end point are shown to illustrate the application of the proposed nested group sequential program.

The globalization of drug development has resulted in an increasing implementation of multiregional clinical trials (MCTs) in Japan. However, ethnic variations and low Japanese patient population in MCTs may impact post-marketing drug safety. This study compared the frequency of safety-related package insert revisions between drugs developed through MCTs and those developed otherwise (non-MCTs) in Japan and the United States. The analysis also investigated factors contributing to racial differences and the prevalence of MCTs. We retrospectively analyzed 227 new active-ingredient drugs approved in Japan between 2012 and 2021. Data on package insert revisions within 5 years of approval were collected from the Pharmaceuticals and Medical Devices Agency and the U.S. Food and Drug Administration databases. Comparisons were made by development method (MCT vs. non-MCT), metabolic enzyme polymorphisms, drug classification, approval process, and manufacturer. In Japan, the mean number of package insert revisions within 5 years was significantly higher for MCT drugs than for non-MCT drugs (0.28 vs. 0.17, p = 0.040). In the United States, no significant difference between MCT and non-MCT drugs was observed. Antineoplastic drugs and immunosuppressants demonstrated higher revision frequencies in both countries, with overall revisions greater in the United States than in Japan. MCT-developed drugs and antineoplastic/immunosuppressant drugs require careful post-marketing safety evaluation in Japanese patients. Differences in regulatory systems and post-marketing surveillance likely contribute to the observed variation in revision frequency between Japan and the United States.

The application of multi-regional clinical trials (MRCTs) is a preferred strategy for rapid global new drug development. In a MRCT, besides the other subgroup factors that are in general well defined, region is a special subgroup factor which can be a surrogate of many intrinsic and extrinsic factors. The definition of a region for a MRCT may be trial specific. It depends on where the MRCT will be conducted and how the sample sizes will be allocated across the regions. As a regional health authority will carefully review the regional treatment effect before the approval of the drug for the patients of the region, special attention should be paid to the regional subgroup analysis. In this chapter, we will discuss subgroup analysis in design and analysis of multi-regional clinical trials focusing on regional subgroup analysis. These include the considerations on region definition, analysis model, consistency assessment of regional treatment effects, regional sample size allocation and trial result interpretation. Numerical and real trial examples will be used to illustrate the applications of the methods.

Ethnic factors pose major challenge to evaluating the treatment effect of a new drug in a targeted ethnic (TE) population in emerging regions based on the results from a multiregional clinical trial (MRCT). To address this issue with statistical rigor, Huang et al. (2012) proposed a new design of a simultaneous global drug development program (SGDDP) which used weighted Z tests to combine the information collected from the nontargeted ethnic (NTE) group in the MRCT with that from the TE group in both the MRCT and a simultaneously designed local clinical trial (LCT). An important and open question in the SGDDP design was how to downweight the information collected from the NTE population to reflect the potential impact of ethnic factors and ensure that the effect size for TE patients is clinically meaningful. In this paper, we will relate the weight selection for the SGDDP to Method 1 proposed in the Japanese regulatory guidance published by the Ministry of Health, Labour and Welfare (MHLW) in 2007. Method 1 is only applicable when true effect sizes are assumed to be equal for both TE and NTE groups. We modified the Method 1 formula for more general scenarios, and use it to develop a quantitative method of weight selection for the design of the SGDDP which, at the same time, also provides sufficient power to descriptively check the consistency of the effect size for TE patients to a clinically meaningful magnitude.

The landscape of drug development evolves with the globalization of the health industry as an integral part of the economy as well as public health worldwide. It is recognized that there are major advantages of being involved in conducting Multi-Regional Clinical Trials (MRCTs) as a part of it: Increasing drug development efficiency, promoting local or regional clinical research, providing local regulatory authorities a large body of data including their own patients studied under the same standard to evaluate the medical product, benefiting citizen patients to access new drugs around the same times as other nations. For these reasons, participating in various MRCTs globally is a rising trend for China as an emergent country in its biopharmaceutical industry and medical-health policy. China has joined the ICH as a member country in 2017. ICH E-17 contains general principles of MRCTs but lacks specifics. In this article, we highlight pertinent design and analysis issues with MRCTs and discuss current common approaches from the statistical aspects.

Multi-regional Clinical Trial (MRCT) for simultaneous global new drug development presents a unique global clinical development strategy. The regulatory authorities across regions and countries could accept the data from MRCTs as the primary sources of evidence to support global marketing drug approval simultaneously. There are many nice advantages of MRCT since it can speed up patient enrollment and drug approval, and it makes effective therapies available to patients all over the world simultaneously. At the same time, there are many challenges both operationally and scientifically in conducting drug development globally. One of many important questions to answer for the design of a multi-regional trial is how to partition sample size into each individual region. In this chapter, the regional sample size formula is reviewed for the regional sample size allocation in the multi-regional equivalence and non-inferiority trials. A non-inferiority vaccine trial is used to illustrate the approaches.