Globalization of anti-cancer therapies

摘要

Based on short reviews of lung, gastric, colorectal, prostate, breast and ovarian cancer, there remain significant differences between Japan and the West in the therapeutic regimen for most cancers. Some of the differences are due to differences in stage of disease at diagnosis or historical factors affecting availability of products. In both Japan and the West, there are initiatives to prepare treatment guidelines based on published data. For Japan this initiative is limited by the lack of Japanese clinical trial data or even safety data. When guidelines are prepared from international data, many of the products have limited indications in Japan and therefore not reimbursed. Availability of the most appropriate therapies to Japanese patients will depend on a facilitation of clinical trials in both primary and additional indications. However, the experience in other countries is that, even where data and registration approval are available, guidelines are hard to agree and are not uniformly accepted byprescribers. The ICH E5 guideline on the use of bridging studies to interpolate Western data to Japanese regulatory dossiers provides an opportunity to accelerate availability of new medicines to Japanese prescribers and patients. The use of bridging studies has so far been limited for anti-cancer therapies. Where relevant pharmacodynamic endpoints can be measured, (e.g. aromatase inhibition) there can increase confidence in bridging. The newer types of agent which act to stabilise disease rather than tumour shrinkage present a special problem. In some cases surrogate markers can be valuable but in each case they need to be validated. As globalization continues, an alternative approach is to include a significant cohort of Japanese patients in Japanese patients but this depends on sufficient similarity in the patient population and background therapy. The most significant limitation to either large outcome studies in Japan or for Japanese centers to join international trials has been the environment for conduct of clinical trials. There have been some recent improvements and further progress is expected so that Japanese doctors can play a full role in the evaluation of new therapies.