Supplementary Material for: New onset Ulcerative Colitis After Secukinumab Initiation: A Case Report

Introduction Secukinumab is an anti-interleukin-17 used in the treatment of rheumatological conditions such as ankylosing spondylitis and psoriasis. Despite elevated IL-17A levels in inflammatory bowel disease (IBD) patients, clinical trials suggest IL-17 inhibition may exacerbate disease activity in IBD. Multiple sclerosis (MS) also has a suspected association with inflammatory bowel diseases. Case Presentation A 22-year-old man with a family history of MS was started on secukinumab for suspected ankylosing spondylitis. Three months after secukinumab initiation, he developed new gastrointestinal symptoms and was diagnosed with ulcerative colitis. He responded to a course of corticosteroids and his secukinumab was stopped. He remains in clinical and endoscopic remission 5 months after completing his course of steroids. Conclusion This case highlights the potential association between IL-17 inhibition and new onset IBD in a patient with a family history of MS. In patients who are to start an anti-IL-17 agent, a personal and family history of IBD as well as other risk factors that increase the risk of IBD, such as MS, should be highlighted, and the patient should be closely monitored for new gastrointestinal symptoms.