The most recent 2018 American College of Gastroenterology guidelines recommend the use of UST in patients who failed previous treatment with corticosteroids, thiopurines, methotrexate, or anti-TNF inhibitors or who have had no prior exposure to anti-TNF inhibitors.10 Persistence and treatment patterns for biologics can serve as useful proxies for their effectiveness in CD patients, and real-world evidence on such endpoints remains limited for UST in CD. Here, TNF is linked to Cowden disease.