Focus on Filgotinib in Rheumatoid Arthritis: A Trial-Based Review

Janus kinases (JAK)/Signal Transducer and Activator of Transcription (STAT) pathway is involved in pathophysiologic cascade of a notable number of rheumatic diseases. The development of JAK inhibitors has expanded treatment choices in rheumatoid arthritis (RA) with a sustained class-effect efficacy. Filgotinib is a novel selective inhibitor of JAK1 isoform licensed for use in RA and ulcerative colitis. In this review we aim to present an analysis of filgotinib's efficacy and drug-specific safety warnings. Patients with RA with or without concomitant conventional synthetic Disease-Modifying Antirheumatic Drugs (csDMARDs) (naïve or experienced) and those who have failed biologic Disease-Modifying Antirheumatic Drugs (bDMARDs) were examined in randomised clinical trials. Filgotinib was also tested against placebo, methotrexate, or adalimumab. Long-term extension trials provide insights for up to four years of continuous filgotinib administration. Beneficial effects are depicted in both disease activity parameters and quality of life indexes in moderate or severe RA with a longitudinal efficacy. In head-to-head comparison with adalimumab, filgotinib 200 mg was non-inferior. Adverse effects alerts are marked by the elevated risk of infectious adverse effects with the exception of herpes zoster infection, which has a low incidence.