Impact of Concomitant Thiopurine on the Efficacy and Safety of Filgotinib in Patients with Ulcerative Colitis: Post hoc Analysis of the Phase 2b/3 SELECTION Study.

BACKGROUND AND AIMS: SELECTION is the first study to assess the impact of concomitant thiopurine and other immunomodulator [IM] use on the efficacy and safety of a Janus kinase inhibitor, filgotinib, in patients with ulcerative colitis. METHODS: Data from the phase 2b/3 SELECTION study were used for this post hoc analysis. Patients were randomized [2:2:1] to two induction studies [biologic-naive, biologic-experienced] to filgotinib 200 mg, 100 mg, or placebo. At week 10, patients receiving filgotinib were re-randomized [2:1] to continue filgotinib or switch to placebo until week 58 [maintenance]. Outcomes were compared between subgroups with and without concomitant IM use. RESULTS: At week 10, a similar proportion of patients in +IM and -IM groups treated with filgotinib 200 mg achieved Mayo Clinic Score [MCS] response [biologic-naive: 65.8% vs 66.9%; biologic-experienced: 61.3% vs 50.5%] and clinical remission [biologic-naive: 26.0% vs 26.2%; biologic-experienced: 11.3% vs 11.5%]. At week 58, a similar proportion of patients in +IM and -IM groups treated with filgotinib 200 mg achieved MCS response [biologic-naive: 74.2% vs 75.0%; biologic-experienced: 45.5% vs 61.4%] and clinical remission [biologic-naive: 51.6% vs 47.4%; biologic-experienced: 22.7% vs 24.3%]. The probability of protocol-specified disease worsening during the maintenance study in patients treated with filgotinib 200 mg did not differ between +IM and -IM groups [p = 0.6700]. No differences were observed in the incidences of adverse events between +IM and -IM groups in induction/maintenance studies. CONCLUSIONS: The efficacy and safety profiles of filgotinib treatment in SELECTION did not differ with or without concomitant IM use.