Abstract
BACKGROUND AND AIMS: There is an unmet need in the treatment of perianal fistulising Crohn's disease [PFCD]. This study evaluated the efficacy and safety of the Janus kinase 1 preferential inhibitor, filgotinib, for the treatment of PFCD. METHODS: This phase 2, double-blind, multicentre trial enrolled adults with PFCD and prior treatment failure. Participants were randomised [2:2:1] to receive filgotinib 200 mg, filgotinib 100 mg, or placebo, once daily orally for up to 24 weeks. The primary endpoint was combined fistula response (reduction from baseline of at least one draining external opening determined by physical assessment, and no fluid collections >1 cm on pelvic magnetic resonance imaging [MRI]) at Week 24. RESULTS: Between April 2017 and July 2020, 106 individuals were screened and 57 were randomised. Discontinuations were lowest in the filgotinib 200 mg group (3/17 [17.6%] versus 13/25 [52.0%] for filgotinib 100 mg and 9/15 [60.0%] for placebo). The proportion of participants who achieved a combined fistula response at Week 24 was 47.1% (8/17; 90% confidence interval [CI] 26.0, 68.9%) in the filgotinib 200 mg group, 29.2% [7/24; 90% CI 14.6, 47.9%] in the filgotinib 100 mg group, and 25.0% [3/12; 90% CI 7.2, 52.7%] in the placebo group. Serious adverse events occurred more frequently with filgotinib 200 mg (5/17 [29.4%]) than with placebo (1/15 [6.7%]). There were no treatment-related serious adverse events or deaths. CONCLUSIONS: Filgotinib 200 mg was associated with numerical reductions in the number of draining perianal fistulas based on combined clinical and MRI findings compared with placebo, and was generally well tolerated [NCT03077412].