P372 Effects of filgotinib on anaemia, thrombocytopenia and leukopenia: Phase 3 study results in patients with active rheumatoid arthritis and prior inadequate response/intolerance to biological DMARDs

• Published in: Journal of Crohn's and colitis 2020-01, Vol.14 (Supplement_1), p.S350-S352
• Main Authors: Besuyen, R, Genovese, M, de Vlam, K, Gottenberg, J E, Kalunian, K, Bartok, B, Tan, Y, Guo, Y, Tasset, C, Sundy, J, Walker, D, Takeuchi, T
• Format: Article
• Language: English
• ISSN: 1873-9946; 1876-4479
• DOI: 10.1093/ecco-jcc/jjz203.501

Abstract Background Anaemia, thrombocytopenia and leukopenia in rheumatoid arthritis (RA) patients treated with non-Janus Kinase 1 (JAK1) selective inhibitors may be due to inhibition of haematopoietic growth factors signalling through JAK2. Therefore, we investigated anaemia, thrombocytopenia and leukopenia in patients with active RA with prior inadequate response/intolerance to biologic disease-modifying anti-rheumatic drugs (bDMARDs) treated with filgotinib (FIL), a selective JAK1 inhibitor (FINCH-2; NCT02873936). Methods In the randomised, double-blind, placebo-controlled Phase 3 FINCH-2 trial, patients were randomised 1:1:1 to oral FIL 200 mg, 100 mg, or placebo (PBO) once daily plus conventional synthetic DMARDs for 24 weeks. In this subgroup analysis, we assessed shifts from baseline (BL) in haemoglobin (hgb), platelets (plt), neutrophils and lymphocytes. Results A total of 448 patients were treated; FIL 200 mg, n = 147; FIL 100 mg, n = 153; PBO, n = 148. Hgb, plt, lymphocyte and neutrophil counts remained consistent throughout the study. At BL, 28.8%, 0.9%, 2.2% and 5.8% patients had mild–moderate low hgb, plt, neutrophil and lymphocyte, respectively, and 1.1% had severely low lymphocyte levels. Of patients with mild–moderate hgb levels at BL, 13.1% with FIL 200 mg, 9.5% FIL 100 mg, and 7.6% PBO achieved normal hgb at Week 24, respectively (Table). Of those with normal BL hgb, only 6–9.8% had mild low levels at Week 24. Patients with BL mild-moderate low plts and neutrophils had normal levels at Week 24, except one with mild neutropenia on FIL 100 mg. Of patients with normal plt and neutrophil levels at BL, >94% maintained these at Week 24 in all treatment groups. By Week 24, 3.2%, 5.2% and 2.2% of patients treated with FIL 200 mg, FIL 100 mg and PBO, respectively, in the mild–moderate subgroup and 1.7% in the severe subgroup treated with FIL 100 mg had normal lymphocyte counts. Conclusion In this subgroup analysis, most patients with normal hgb, plt, lymphocyte and neutrophil at BL maintained them over 24 weeks of FIL treatment. Of the patients with mild–moderately low hgb at BL, >9% shifted towards normalisation. Similar patterns of improvement were observed for plt, lymphocyte and neutrophil counts. These results suggest that FIL does not increase the incidence of anaemia, thrombocytopenia or leukopenia in patients who entered the study with active RA despite prior bDMARDs.