Interleukin-17 inhibition: role in psoriasis and inflammatory bowel disease

Introduction: Interleukin 17 (IL-17) antagonism provides a highly effective approach for treating psoriasis. Exacerbations of inflammatory bowel disease have been reported in anti-IL-17 psoriasis trials.Aim: To characterize the relationship between IL-17 inhibition and inflammatory bowel disease.Methods: A review of English-language articles was performed. Search terms included IL-17, psoriasis, inflammatory bowel disease, secukinumab, ixekizumab and brodalumab.Results: IL-17A inhibition, IL-17RA inhibition and IL-17 knockout led to induction or exacerbation of colitis in mouse models. The placebo groups fared better than the treatment group in controlled trials of anti-IL-17 antibody and anti-IL-17 receptor for Crohn's disease (CD). A brodalumab study (N=1576) revealed one reported CD case. An ixekizumab study (N=3736) evaluating moderate-to-severe psoriasis, four patients reported CD and seven reported UC while ixekizumab every 2weeks led to a moderate exacerbation of UC in one patient and new-onset CD in one patient. A secukinumab study (N=3430) revealed exposure adjusted incidence rates of 0.11 and 0.15 per 100 patient-years for CD and UC, respectively.Discussion: Anti-IL-17 medications are associated with IBD exacerbation. Caution should be used in prescribing these medications in patients with diagnosed IBD or personal history suggestive of IBD.