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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., (© 2023. The Author(s), under exclusive licence to The Drug Information Association, Inc.)

Although the "drug lag"-namely, the delay in drug approval time in Japan relative to the United States and/or European Union (US/EU)-has been shortened for drugs approved in Japan, there remain many new drugs that have been approved in the US/EU, but not in Japan. To assess the possibility of a future drug lag, this study has examined the current lag in drug development in Japan based on "ClinicalTrials.gov" data from multiregional clinical trials (MRCTs) conducted in the US/EU and East Asia. Among 828 MRCTs registered as of April 5th, 2021, the percentage of MRCTs in which Japan participated (jMRCTs) was 57.1%. jMRCTs were common for some diseases such as "nervous system" and "visual system" disorders, but less common for "neoplasm," infection," "mental," and "circulatory" disorders. Regarding the investigational drugs in non-jMRCTs (i.e., MRCTs without Japanese participation) in the latter four therapeutic areas (i.e., neoplasm, infection, mental and circulatory disorders), approximately 80% (313/399) of drugs were not being developed in Japan. Furthermore, many of these drugs were being developed by the top 50 pharmaceutical companies by sales, and the majority would be recognized as a new active ingredient with a new mode of action in Japan. This study has highlighted the possibility of a future drug lag in Japan, especially in the therapeutic areas of neoplasm, infection, mental, and circulatory disorders. Such a lag may arise not only between Japan and the US/EU, but also between Japan and other countries in the East Asian region., (© 2022. The Drug Information Association, Inc.)

During oncology drug development, it is important that ethnic differences are evaluated to determine the optimal dose and administration schedule in a new region based on the clinical data from other regions. The objective of this study was to explore the possibility of detecting ethnic differences in toxicity during early-phase clinical trials. Data were reviewed from phase I clinical trials for new drug applications conducted in Japan and Western countries. The maximum tolerated doses (MTDs), recommended phase II doses (RP2Ds), and approved doses in Japan were compared with those in Western countries. There were 4 of 28 drugs eligible for analysis that showed differences in MTDs or RP2Ds between Japanese and Western patients. Differences in MTDs or RP2Ds in 2 phase I trials were associated with ethnic differences in toxicity. It may be worthwhile to evaluate ethnic differences in toxicity during early-phase clinical trials for oncology drugs.