Evaluating filgotinib for the treatment of rheumatoid arthritis

Introduction Despite the availability of an extensive armamentarium, rheumatoid arthritis (RA) remains a therapeutic challenge for rheumatologists. Janus kinase inhibitors (JAKi) are an emerging class of targeted therapies. The number of JAKi has been growing and to date, filgotinib is the latest JAKi to be approved for use in RA.Areas covered This review focuses on the pharmacodynamics, pharmacokinetics, efficacy and safety of filgotinib in patients with RA.Expert opinion Filgotinib is an oral targeted synthetic disease-modifying antirheumatic drug (DMARD) that specifically inhibits JAKi. Filgotinib monotherapy, or a combination regimen with conventional synthetic (cs) DMARDs, has demonstrated efficacy in decreasing disease activity, with a well-managed safety profile in patients with early RA naive to DMARDs, and in RA that does not adequately respond to csDMARDs and/or biologic DMARDs. The selective inhibition of JAK1 may confer an improved safety profile, but further study is required as a potential testicular toxicity has been suggested. Filgotinib offers several advantages: oral administration, rapidity of action, efficacy as monotherapy, and demonstrated activity in difficult to treat RA. However, the placement of filgotinib in the therapeutic arsenal for RA may be influenced by the ongoing collection of long-term safety data from JAKi as a class.