BACKGROUND: Filgotinib (GLPG0634, GS-6034) is a once-daily, orally administered, 
Janus kinase 1 (JAK1)-selective inhibitor. The FITZROY study examined the 
efficacy and safety of filgotinib for the treatment of moderate-to-severe 
Crohn's disease.
METHODS: We did a randomised, double-blind, placebo-controlled phase 2 study, 
which recruited patients from 52 centres in nine European countries. We enrolled 
eligible patients aged 18-75 years with a documented history of ileal, colonic, 
or ileocolonic Crohn's disease for 3 months or more before screening, as 
assessed by colonoscopy and supported by histology, and a Crohn's Disease 
Activity Index (CDAI) score during screening between 220 and 450 inclusive. 
Patients were randomly assigned (3:1) to receive filgotinib 200 mg once a day or 
placebo for 10 weeks. Patients were stratified according to previous anti-tumour 
necrosis factor alpha exposure, C-reactive protein concentration at screening 
(≤10 mg/L or >10 mg/L), and oral corticosteroid use at baseline, using an 
interactive web-based response system. The primary endpoint was clinical 
remission, defined as CDAI less than 150 at week 10. After week 10, patients 
were assigned based on responder status to filgotinib 100 mg once a day, 
filgotinib 200 mg once a day, or placebo for an observational period lasting a 
further 10 weeks. The filgotinib and placebo treatment groups were compared 
using ANCOVA models and logistic regression models containing baseline values 
and randomisation stratification factors as fixed effects. Analyses were done on 
the intention-to-treat non-responder imputation set. The trial was registered at 
ClinicalTrials.gov, number NCT02048618.
FINDINGS: Between Feb 3, 2014, and July 10, 2015, we enrolled 174 patients with 
active Crohn's disease confirmed by centrally read endoscopy (130 in the 
filgotinib 200 mg group and 44 in the placebo group). In the intention-to-treat 
population, 60 (47%) of 128 patients treated with filgotinib 200 mg achieved 
clinical remission at week 10 versus ten (23%) of 44 patients treated with 
placebo (difference 24 percentage points [95% CI 9-39], p=0·0077). In a pooled 
analysis of all periods of filgotinib and placebo exposure over 20 weeks, 
serious treatment-emergent adverse effects were reported in 14 (9%) of 152 
patients treated with filgotinib and three (4%) of 67 patients treated with 
placebo.
INTERPRETATION: Filgotinib induced clinical remission in significantly more 
patients with active Crohn's disease compared with placebo, and had an 
acceptable safety profile.
FUNDING: Galapagos.