Background/Purpose: FILOSOPHY (NCT04871919) and PARROTFISH (NCT05323591) are ongoing, prospective, observational Phase 4 studies of filgotinib in patients (pts) with rheumatoid arthritis (RA) in Europe. In this interim analysis, pooled data from the studies are reported up to 2 years.

Methods: The studies enrolled adults with moderate to severe active RA who were prescribed filgotinib for the first time in daily practice. Disease activity assessments included Clinical Disease Activity Index (CDAI) and Disease Activity Score in 28 joints using C-reactive protein (DAS28-CRP). The following patient-reported outcomes (PROs) were collected: visual analog scale (VAS) pain, Functional Assessment of Chronic Illness Therapy (FACIT)–Fatigue and Health Assessment Questionnaire–Disability Index (HAQ-DI) scores. A ≥10-mm reduction in VAS pain score or a ≥4-point increase in FACIT-Fatigue score were considered clinically meaningful changes from baseline. Outcomes were assessed in biologic (b)DMARD-naïve and -experienced pts. Treatment persistence (Kaplan–Meier estimate) and treatment adherence (5-Item Compliance Questionnaire for Rheumatology [CQR5]) were reported up to Month 12. CQR5 scores >80% indicate good adherence. Treatment-emergent adverse events (TEAEs) were reported. All data are on-treatment.

Results: From May 2021 to September 2024, 1,423 pts were treated with filgotinib (median follow-up: 550 days); baseline characteristics are shown in Table 1. 38.9% of pts were bDMARD naïve; 61.1% were bDMARD experienced. 91.2% received filgotinib 200 mg; 8.8% received filgotinib 100 mg. The proportion of pts with a CDAI score ≤10 increased from baseline to Month 24 (Figure A). In bDMARD-naïve pts, median (IQR) CDAI score decreased from 22.0 (16.0–31.0) at baseline (n=424) to 8.0 (4.0–14.0) at Month 1 (n=311) and 3.0 (0.0–7.5) at Month 24 (n=112), and in bDMARD-experienced pts from 24.0 (17.0–33.0) at baseline (n=694) to 10.5 (6.0–18.0) at Month 1 (n=444) and 6.0 (3.0–12.0) at Month 24 (n=157). Similar improvements were seen for DAS28-CRP. For PROs, median (IQR) HAQ-DI score decreased from 1.3 (0.8–1.8) at baseline (n=335) to 0.8 (0.3–1.3) at Month 1 (n=227) and 0.6 (0.3–1.1) at Month 18 (n=73). A clinically meaningful change in VAS pain score occurred in 43.9% of pts (177/403) at Week 1 and 63.5% (54/85) at Month 24; for FACIT-Fatigue, the proportions were 43.6% (175/401) at Week 1 and 55.3% (47/85) at Month 24. Improvements in PROs were seen in bDMARD-naïve and -experienced pts. At Month 12, treatment persistence (95% CI) was 74.6% (72.1, 76.9) (Figure B), and 79.8% of pts had a CQR5 score >80%. There were 9 deaths, 7 of which were considered unrelated to study treatment by the investigator. TEAEs of interest are shown in Table 2.

Conclusion: Pts treated with filgotinib in FILOSOPHY and PARROTFISH showed improvements in disease activity and HAQ-DI from Month 1, and in pain and fatigue from Week 1. Improvements were maintained up to Month 24 (Month 18 for HAQ-DI) and were seen regardless of prior bDMARD exposure. At Month 12, treatment persistence was high (75%) and 80% of pts showed good adherence. Safety data were consistent with those previously reported from randomized controlled trials of filgotinib.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/early-and-sustained-improvements-in-disease-activity-and-patient-reported-outcomes-in-patients-treated-with-filgotinib-for-rheumatoid-arthritis-up-to-2-year-interim-real-world-data-from-filosophy-and/