Efficacy/Effectiveness, Safety and Treatment Persistence of Filgotinib in Rheumatoid Arthritis: A Narrative Review of Clinical Trials and Real-World Evidence

Filgotinib (FIL) is a Janus kinase preferential inhibitor, classified as a targeted synthetic disease-modifying anti-rheumatic drug (tsDMARD). It is approved for patients with rheumatoid arthritis (RA) who have failed treatment with methotrexate (MTX), a conventional synthetic DMARD (csDMARD). Randomized controlled trials (RCTs) investigating 100 and 200 mg doses of FIL + MTX have demonstrated rapid effects in reducing disease activity, pain, and fatigue and improving functional outcomes compared with MTX monotherapy or adalimumab (a biologic) + MTX. FIL's efficacy in reducing disease activity and improving functional outcomes was sustained in the long-term (3 years), while also minimizing radiographic progression. In particular, 200 mg FIL + MTX significantly reduced radiographic progression uncoupled from disease activity, outperforming adalimumab + MTX in patients with medium or high disease activity. Adverse events were similar among FIL, MTX, and adalimumab over 52 weeks in RCTs, with a consistent safety profile in the long term (> 8 years). FIL persistence rates were generally high, regardless of dose. Evidence from real-world observational studies complements and underscores the effectiveness and safety of FIL demonstrated in RCTs. These findings support FIL's potential as a therapeutic option in the management of RA. Guidelines currently recommend a starting dose of 200 mg FIL ± MTX; a 100 mg starting dose can be used if the patient is elderly (Europe); at increased risk of venous thromboembolism, major adverse cardiovascular events or malignancy (Europe); or has impaired renal function (Japan). Furthermore, patients should only initiate FIL after inadequate response to MTX or other csDMARDs. In clinical practice, there may be additional considerations that could impact outcomes, including persistence and variations in patient profiles and treatment backgrounds. Future results from ongoing studies can be expected to provide further insights into the long-term effectiveness, such as joint outcomes and safety of FIL, in the real-world context.Graphical abstract available for this article.