Peficitinib: First Global Approval.

Peficitinib [Smyraf® (Astellas Pharma)] is a Janus kinase (JAK)1, JAK2, JAK3 and tyrosine kinase (Tyk)2 (pan-JAK) inhibitor recently approved in Japan for the treatment of rheumatoid arthritis. Inhibition of JAK suppresses the activation of cytokine signalling pathways involved in inflammation and joint destruction in rheumatoid arthritis. Peficitinib has been shown to significantly improve ACR20 and other measures of disease severity and to reduce the mean modified total Sharp score change from baseline in clinical trials. This article summarizes the milestones in the development of peficitinib leading to this first approval as a treatment for rheumatoid arthritis in patients who have an inadequate response to conventional therapies.