The trend in patent infringement litigation against generic drugs or biosimilars in Japan

The timing of market entry for generic drugs or biosimilars based on patent expiration is not always clear for producers of generic drugs and biosimilars or brand-name drug companies, because of an uncertainty due to patent infringement, the market environment, and legislation. In Japan, the policy of promoting the use of generic drugs began in the early 2000s, and the government’s target for generic drug use rate is 80% by 2020. In addition to this drastic change in the market environment, changes in legislation have complicated the timing of market entry for generic drugs and biosimilars. Although there is a relatively low number of patent infringement lawsuits filed against producers of generic drugs and biosimilars each year, emerging litigation issues are likely influenced by recent changes in the market environment and legislation. This article provides an overview of recent legislative changes, analyzes the trends in patent infringement litigation, and discusses litigation issues related to the stable supply of generic drugs and biosimilars in Japan. In light of the emerging issues in this field, producers of generic drugs and biosimilars will require more diligence to avoid patent infringement, and institutional reforms are suggested to reduce an increase in patent infringement litigation