Filgotinib in Moderate to Severe Rheumatoid Arthritis in a Real-World Setting: Up to 6-Month Effectiveness,...

FILOSOPHY (NCT04871919) and PARROTFISH (NCT05323591) are ongoing, prospective observational European phase 4 studies of filgotinib in patients with rheumatoid arthritis (RA) in a real-world setting. We report the study design, baseline characteristics, and interim results for disease activity measures, patient-reported outcomes (PROs), and treatment persistence up to 6 months and safety up to 24 months.

Eligible patients had moderate to severe RA and were prescribed filgotinib for the first time in daily practice. In this interim analysis, measures include the proportion of patients achieving low disease activity (LDA), according to Disease Activity Score for 28 joint count using C-reactive protein (DAS28-CRP) or Clinical Disease Activity Index (CDAI), and the proportion achieving a clinically meaningful change from baseline in visual analog scale (VAS) pain (≥ 10 mm reduction) and in Functional Assessment of Chronic Illness Therapy (FACIT)-Fatigue score (≥ 4.0 increase). Treatment persistence was estimated using the Kaplan-Meier method. Treatment-emergent adverse events (TEAEs) are reported.

From May 2021 to April 2025, 1431 patients initiated filgotinib treatment; 93.0% had completed at least 6 months of follow-up (median follow-up 706 days). Improvements in DAS28-CRP and CDAI occurred from month 1. By month 6, DAS28-CRP ≤ 2.6 was reported for 58.1% (494/850) of patients and CDAI remission for 25.7% (221/859). The proportion with LDA was 71.4% (607/850) based on DAS28-CRP and 69.8% (600/859) based on CDAI. The proportion with a clinically meaningful change from baseline in VAS pain and FACIT-Fatigue score was 44.1% (178/404) and 43.8% (176/402), respectively, at week 1, increasing to 69.6% (227/326) and 62.5% (202/323), respectively, at month 6. Treatment persistence (95% CI) at month 6 was 84.0% (82.0, 85.8). Up to month 24, the exposure-adjusted incidence rates per 100 patient-years of exposure (95% CI) of any TEAEs and serious TEAEs were 89.8 (84.1, 95.8) and 9.4 (8.0, 10.8), respectively.

Interim data from FILOSOPHY/PARROTFISH showed improvement of disease activity from month 1 and PROs from week 1, high treatment persistence at 6 months, and no new safety signals. These findings continue to support the safety and effectiveness of filgotinib in daily clinical practice.

ClinicalTrials.gov: NCT04871919 (2021-04-29), NCT05323591(2022-04-05).