Efficacy of budesonide and vedolizumab for IBD-U associated with Muckle-Wells syndrome.

Cryopyrin-associated periodic syndrome (CAPS) is a rare, autosomal dominant inflammatory disorder linked to interleukin (IL)-1β dysregulation. Muckle-Wells syndrome (MWS) is a clinical subtype of CAPS that is often managed with canakinumab, an anti-IL-1β monoclonal antibody. Canakinumab has been approved for all phenotypes of CAPS, with no age restrictions, since 2011. Despite its efficacy in controlling systemic inflammation, its gastrointestinal side effects remain unclear. This report presents the case of a 28 year-old man who developed abdominal pain and diarrhea during treatment with canakinumab for MWS. Colonoscopy revealed findings suggestive of inflammatory bowel disease, and a diagnosis of IBD-unclassified (IBD-U) was made after exclusion of other conditions. Treatment with oral budesonide and vedolizumab led to marked clinical and endoscopic improvements, maintaining remission after budesonide discontinuation. Although the usefulness of systemic prednisolone and anti-TNFα antibody preparations for treating IBD-U in patients with MWS has been previously reported, to the best of our knowledge, this is the first report to highlight the therapeutic effects of budesonide and vedolizumab. Therefore, IBD-U should be considered in the differential diagnosis of patients with CAPS who develop gastrointestinal symptoms. Considering their favorable side-effect profiles, budesonide and vedolizumab may serve as promising treatment alternatives in the future.