LAUSR

Cytopoenias are common in patients treated for rheumatoid arthritis (RA) with non-janus kinase 1 (JAK1)-selective inhibitors, possibly due to JAK2-mediated haematopoietic growth factor inhibition. We investigated the extent of cytopoenia in patients with active RA, despite prior treatment with biological disease-modifying antirheumatic drugs (bDMARDs), treated with the JAK1-selective inhibitor filgotinib (FIL), in a Phase 3 trial (FINCH2; NCT02873936). In the double-blind, Phase 3 FINCH2 trial, patients were randomised 1:1:1 to receive oral FIL 200mg, 100mg, or placebo (PBO) once daily for 24 weeks (W) + conventional synthetic DMARDs. We assessed shifts from baseline at 12 and 24 weeks in haemoglobin, platelets, neutrophils and lymphocytes. 448 patients were treated: FIL 200mg, n = 147; FIL 100mg, n = 153; PBO, n = 148. Overall, haemoglobin, platelet, lymphocyte and neutrophil levels remained consistent throughout the study. At baseline, 129 (28.8%), 4 (0.9%), 10 (2.2%) and 26 (5.8%) patients had mild-moderate low levels of haemoglobin, platelets, neutrophils and lymphocytes, respectively, and 5 (1.1%) had severely low levels of lymphocytes. Of the patients with mild-moderate low haemoglobin levels at baseline, 10-13% achieved normal levels by W24 vs 8% receiving PBO (Table). Of those with normal baseline haemoglobin levels, 6-10% had mild low levels at W24. All patients with baseline mild-moderate low platelets and neutrophils had normal levels at W24, except one patient with mild neutropoenia receiving FIL 100mg. Of the patients with normal platelet and neutrophil levels at baseline, >94% maintained these at W24 in all treatment groups. By W24, 3.2%, 5.2% and 2.2% of patients treated with FIL 200mg, FIL 100mg and PBO, respectively in the baseline mild-moderate subgroup and 1.7% in the severe subgroup treated with FIL 100mg had normal lymphocyte counts. In this study, most patients in the baseline normal cell count subgroups maintained this status over 24 weeks of FIL treatment. Of the patients with mild-to-moderately low haemoglobin at baseline, >9% shifted towards haemoglobin normalisation. Similar patterns of improvement from baseline were observed for platelet, lymphocyte and neutrophil counts. FIL appears not to increase the incidence of cytopenias in patients with active RA despite prior biologic therapies. D. Walker: Other; Received support from Lilly, Pfizer, Novartis, Roche. M.C. Genovese: Other; Received support from Gilead Sciences Inc., Galapagos NV, AbbVie Inc. Eli Lilly and Company, Pfizer. K. Kalunian: Grants/research support; Grand support from Gilead. J. Gottenberg: None. B. Bartok: Corporate appointments; Employee of Gilead Sciences, Inc. Shareholder/stock ownership; Shareholder of Gilead Sciences, Inc. Y. Tan: Corporate appointments; Employee of Gilead Sciences, Inc... Shareholder/stock ownership; Shareholder of Gilead Sciences, Inc. Y. Guo: Corporate appointments; Employee of Gilead Sciences, Inc. Shareholder/stock ownership; Shareholder of Gilead Sciences, Inc. C. Tasset: Other; Employee of Galapagos. J.S. Sundy: Corporate appointments; Employee of Gilead Sciences, Inc. Shareholder/stock ownership; Shareholder of Gilead Sciences, Inc. K. de Vlam: None. T. Takeuchi: None.