New-onset inflammatory bowel diseases among IL-17 inhibitor-treated patients: results from the case-control MISSIL study.

OBJECTIVES: To describe new-onset IBD (new IBD) in patients treated with IL-17 inhibitors (IL-17i), to assess their incidence and to identify their risk factors in real life. METHODS: A French national registry (MISSIL) aimed to report all cases of new IBD in patients treated with IL-17i from January 2016 to December 2019. Using the estimated number of patients treated by IL-17 in France during the study period, the annual incidence rates of new IBD was reported in IL-17i-treated patients. A case-control study was performed with two controls per new IBD case matched by gender, age and underlying inflammatory disease. RESULTS: Thirty-one cases of new IBD under IL-17i were collected: 27 patients treated for spondyloarthritis and four patients for psoriasis. All were observed with secukinumab (SEK). The median time to onset of new IBD symptoms was 4.0 (1.5-7.5) months. SEK was discontinued in all patients. The evolution was favourable with complete resolution (17/31), improvement (7/31) or stabilization (5/31). Two patients died: one due to a massive myocardial infarction and one due to post-colectomy complications. The incidence of new IBD decreased from 0.69/100 patient-years [PY] (7/1010) in 2016 to 0.08/100 PY (6/7951) in 2019. No previous treatment with etanercept (odds ratio [OR] = 0.33, 95% CI: 0.14-0.80, P = 0.014) and low number of previous biologic therapies (OR = 0.67, 95% CI: 0.47, 0.94, P = 0.021) were significantly associated with new IBD. CONCLUSION: The incidence of new IBD was low and decreased from 2016 to 2019. The outcome was favourable in 24 out of 31 patients, but two patients died.