日米における適応的デザインを用いた臨床試験の現状

Clinical trials using adaptive designs(AD)are more flexible in study design and implementation compared to conventional fixed designs. In the US, the draft guidance documentËAdaptive Design Clinical Trials for Drugs and BiologicsÌwas issued by the FDA in 2010, and many studies using AD have been performed. On the other hand, the situation of practical application of AD to clinical trials in Japan has not been reported and no guidance has been issued. We investigated the use of AD in both Japan and the US by searching public clinical trial registration databases in both countries. Four databases were used for searching clinical trials carried out in Japan, and one database for the US. We included clinical trials using AD registered between January 1, 2013 and December 31, 2017. Twenty-four AD trials conducted in Japan and 97 conducted in the US were identified. The AD were used mainly in the early phase of clinical development. Of the 24 trials conducted in Japan, 23 were sponsored by pharmaceutical companies. In particular, AD were frequently used in clinical trials led by global pharmaceutical companies and overseas affiliate of Japanese companies. In the US, the numbers of domestic AD trials and multinational AD trials were almost the same, and some of them were led by academic institutions. These findings suggest that Japanese companies have limited experience in using AD, and that AD are not yet popular in Japan. Efforts to enhance understanding of AD, such as issuing guidance by regulatory authorities in Japan, are needed to promote diffusion of efficient clinical development using AD.