TOKYO, May 31, 2018  - Astellas Pharma Inc. (President and CEO: Kenji Yasukawa, Ph.D., “Astellas” ) today announced that it has submitted an application for marketing approval of peficitinib hydrobromide (generic name; development code: ASP015K, “peficitinib”) for the treatment of rheumatoid arthritis (including prevention of structural joint damage) in patients who have an inadequate response to conventional therapy in Japan.

Peficitinib, an orally available Janus kinase (JAK) inhibitor discovered by Astellas, suppresses activation and proliferation of inflammatory cells involved in synovial inflammation and joint destruction in rheumatoid arthritis patients through inhibition of various inflammatory cytokine signaling pathways.

The submission is based mainly on the results obtained from two Phase 3 trials (RAJ3 and RAJ4) of peficitinib in rheumatoid arthritis patients who had an inadequate response to conventional therapy. The primary endpoint of RAJ3*1 was “ACR*220 response rate at Week 12 (percentage of patients with improvement of at least 20% in various rheumatoid arthritis endpoints).” The co-primary endpoints of RAJ4*3 trial were “ACR20 response rate at Week 12” and “suppression of joint destruction at Week 28 (change in mTSS*4 from baseline).” Both trials demonstrated superiority over placebo and met the primary endpoints. The safety analysis of these trial appears consistent with the safety profile of peficitinib in previous clinical trials and no new safety signals were observed. It is also planned to present them in detail at a future medical conference.

According to epidemiological data, the number of rheumatoid arthritis patients is approximately 0.7 to 0.8 million in Japan. With this submission, Astellas expects to contribute to treatments of rheumatoid arthritis patients with an inadequate response to conventional therapy, such as Methotrexate (MTX) and disease-modifying antirheumatic drugs (DMARDs)*5, by providing peficitinib as a new therapeutic option.

Further, Astellas intends to discuss the data with the regulatory authorities in Asian countries to support filing new drug application.