[Current Status and Issues in Drug Development for Rare Cancers]

Since 1993, the"R & D Promotion System for Orphan Drugs and Orphan Medical Devices"has been in operation to support the development of orphan drugs in Japan. Various supportive measures are in place for indications that target less than 50,000 patients, have high medical needs and high probability of successful development(which means regulatory approval). However, recently a trend was observed that the designation for orphan drugs occurred most often in late phase of development, because clinical data for late stage clinical studies were required to show the high probability of successful regulatory approval. The Ministry of Health, Labour and Welfare are trying to make efforts to expand the orphan drug designation, and have made the decision to include the related expenses will be included in the FY 2023 budget request. It is expected that the expansion of orphan drug designation will lead to promote drug development in rare disease area. On the other hand, fundamental reform is considered necessary for this system. Among the approved anti-cancer drugs that obtained orphan designation in the U. S. and EU as of 2020, there are 24 drugs that have not been approved in Japan. Of these, there are at least 16 drugs approved in either China, Taiwan, and South Korea. From viewpoint of development pathway of an orphan drug, participation in a multi-regional clinical trial(MRCT)is useful, but there are cases that Japan cannot join MRCT in time due to the requirement of Japanese safety data prior to the participation. In that case, it is impossible to conduct a separate clinical trial to obtain Japan regulatory approval due to very limited patients(eg several to several tens of Ultra-Orphan). A review system that allows earlier patient access is desired.