P219 Long-term safety of filgotinib in patients with PsA: week 52 safety data from a Phase 2 open-label extension study

Background Filgotinib (FIL) is an orally administered, selective janus kinase 1 (JAK1) inhibitor in development for psoriatic arthritis (PsA). Efficacy and safety of FIL in patients with active PsA were evaluated in a 16-week phase 2 study (EQUATOR, NCT03101670). After 16 weeks, patients could roll-over to an Open Label Extension (OLE) Study (EQUATOR2, NCT03320876) for the purpose of evaluating long-term safety and efficacy. The aim of this analysis was to assess safety and efficacy through 52 weeks of exposure to filgotinib. Methods Patients who completed the randomised, double-blind, placebo-controlled study were eligible for participation in the OLE, during which all patients received once daily (qd) open-label FIL 200mg. In this interim analysis of OLE, for the safety analysis, all data were included from the screening in the core study up to the data cut of 18 April 2019 in the OLE. For the efficacy analysis, all data until OLE Week 52 visit for each patient were included (observed case analysis). Results Of the 131 patients randomised and dosed in EQUATOR, 124 (95%) completed the study and 122 (93%) enrolled in EQUATOR2; 50% were female and mean age was 50. At this interim analysis, 106/122 (87%) remained in the OLE (premature discontinuations during OLE due to: 4 for safety, 11 withdrew consent, and 1 for other reasons). Cumulative patient years of exposure (PYE) on FIL were 160, median time on FIL was 66 weeks. Key safety data are summarised in Table 1. Key ≥Grade 2 treatment-emergent laboratory abnormalities seen with FIL arm (N = 128) compared with PBO (N = 66) were lymphocyte decrease 11.1% vs 4.5%, neutrophil decrease 5.5% vs 0%, ALT increase 1.6% vs 1.5% and creatinine increase 0.8% vs 0%, respectively. At week 52, 34% of the patients fulfilled criteria for minimal disease activity and 81%, 55%, and 33% of patients, respectively, achieved ACR20/50/70 responses. Conclusion FIL 200mg qd was generally well tolerated and the safety profile in PsA was comparable to that observed in the FIL rheumatoid arthritis studies. The data from this interim analysis suggest that further improvement of the patient condition can be expected beyond 16 weeks of treatment. Disclosures L. Coates: Other; Received support from Abbvie, Amgen, Celgene, Galapagos, Janssen, Lilly, Novartis, Pfizer, Prothena, Sun pharma, and UCB. P. Mease: Other; Received support from Abbvie, Amgen, BMS, Celgene, Galapagos, Genentech, Gilead, Janssen, Eli Lilly, Merck, Novartis, Pfizer, SUN, and UCB. D. Gladman: Other; Received support from Abbvie, Amgen, Celgene, Eli Lilly, Gilead, Janssen, Novartis, Pfizer, UCB, BMS, and Galapagos. F. Van den Bosch: Other; Received support from Abbvie, Bristol-Myers Squibb, Eli Lilly, Galapagos, Janssen, Merck, Novartis, Pfizer, and UCB. A. Rychlewska-Hanczewska: Other; Received support from Galapagos and Gilead Sciences. C. Tasset: Corporate appointments; Employee of Galapagos NV. L. Meuleners: Corporate appointments; Employee of Galapagos NV. M. Trivedi: 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. R. Besuyen: Other; Employee of Galapagos NV. P. Helliwell: Other; Received support from Abbvie, Amgen, Celgene, Galapagos, Janssen, Novartis, Pfizer, and UCB.