Efficient clinical trials in Japan: Bridging studies versus participation in global clinical trials.

The required number of Japanese subjects was compared between the Bridging (BG) filing strategy described in ICH-E5 for drugs approved from 1998 to 2012, in which foreign phase 3 results were used together with a BG study conducted to confirm optimum Japanese dose, and global clinical trial (GCT) strategies in which the number was simulated from the foreign phase 3 studies. The simulated number from the GCT strategy was smaller than that of the BG, suggesting that the GCT strategy could be expected to reduce Japanese clinical trial costs. However, two exceptions were found, namely for preventive drugs and drugs for children, because of the large scales of foreign phase 3 studies.