Background: Filgotinib (FIL), a preferential Janus Kinase (JAK)1 inhibitor has demonstrated efficacy in rheumatoid arthritis (RA) in pivotal clinical trials. Limited data exist on the real-world effectiveness of FIL in RA.

Objectives: To examine the short-term effectiveness of FIL compared to other modes of action in a heterogeneous Belgian RA population.

Methods: Patients were included from the electronic platform “Tool for Administrative Reimbursement Drug Information Sharing” (TARDIS). Data from all Belgian RA patients on biologic and targeted therapy are collected in this platform during the submission of a request for initiation or prolongation of reimbursement of these drugs.

Adult patients ≥18 years- and a Disease Activity Score 28 (DAS28 score) >3.7 starting FIL or a comparator population treated with bDMARDs were selected between August 2021 and December 2023. Patients who attended a first follow-up moment, structurally planned in TARDIS after 3 months (FIL) or 6 months (bDMARDs) were included. Effectiveness was determined by the patient proportion achieving remission (DAS28CRP <2.6, if DAS28-CRP was unavailable DAS28-ESR was used), Low Disease Activity (LDA) (DAS28 ≤3.2), Health Assessment Questionnaire Disability Index (HAQ-DI) ≤0.25 (HAQ25), HAQ-DI ≤0.5 (HAQ50) and minimum HAQ-DI-decrease (MCID_HAQ) since baseline of 0.22. Logistic regression was adjusted for confounding variables.

Results: In total, 714 patients on FIL and 3741 patients on bDMARDs were included (Table 1). Disease duration was longer in FIL population (9.9±10.0 years) versus the bDMARD population (6.5±8.1 years). Remission and LDA was reached respectively in 45.1% (322/714) and 58.3% (416/714) FIL versus 29.7% (1110/3741) and 38.1% (1425/3741) bDMARD patients (p<0.001). MCID_HAQ was reached in 53.5% (382/714) FIL versus 34.0% (1272/3741) bDMARD patients (p<0.001). Logistic regression models adjusted for baseline age, disease duration, joint counts, Patient Global Assessment, DAS28, HAQ-DI, and treatment line confirmed these results. Odds Ratio (CI95%) for remission was 2.4 (2.0-2.8, p<0.001), for LDA 2.6 (2.2-3.1, p<0.001), for MCID_HAQ 2.6 (2.2-3.1, p<0.001), for HAQ25 2.5 (1.9-3.2, p<0.001), and finally for HAQ50 2.3 (1.9-2.9, p<0.001). FIL efficacy slightly decreased with increasing line of therapy (Figure 1).

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Figure 1.

Effectiveness outcomes of FIL per treatment line remission (DAS28<2.6), LDA - low disease activity (DAS28≤3.2), HAQ-DI≤0.25 or ≤0. 5 (HAQ25/50) and minimum HAQ-DI-decrease (MCID_HAQ) since baseline=0.22.

Conclusion: FIL treatment showed enhanced clinical and functional outcomes versus a contemporary bDMARD cohort on the short-term in moderately to severely active RA in real-world data. Although adjusted analyses were used, selection bias still could influence the results. Moreover, remission based on CRP was mostly used, and this could bias remission rates towards FIL.

REFERENCES: NIL.

Acknowledgements: This work was supported by Galapagos.

Disclosure of Interests: None declared.