A Participant- and Investigator-blind, Randomised, Placebo-controlled Phase II Study to Evaluate Safety, Tolerability, and Mucosal Repair with AZD7798 in Patients with Active Ileal Crohn’s Disease and an Ileostomy (CALLISTO)

Researchers are looking for a better way to treat Crohn’s disease. People with Crohn’s disease have inflammation in their digestive tract, which can cause symptoms like pain, diarrhoea, fatigue, and weight loss. One type of Crohn’s disease is ileal Crohn's disease. This means a person’s Crohn’s disease is specifically affecting their ileum, which is the end part of the small intestine, also called the small bowel. Some people with Crohn’s disease need to have their colon (large bowel) removed and an ileostomy formed, which is a surgical procedure where the ileum is brought to the surface of the tummy (abdomen) to create an opening for waste to exit the body. The trial drug AZD7798 targets and reduces the number of a specific group of immune cells that have the protein CCR9 on their surface. These cells are present throughout the bowel but are particularly common in the small bowel. Researchers think these cells contribute to gut inflammation in Crohn’s disease. AZD7798 has already been tested in people with Crohn's disease, and now researchers want to see how safe it is and how well it works in people with ileal Crohn’s disease and an ileostomy. This trial will have 2 parts. Part 1 will be 12 weeks long and participants will receive either AZD7798 or the placebo. The placebo looks like AZD7798 but does not have any medicine in it. Part 2 will be 40 weeks long and all participants still in the trial will receive AZD7798. Treatments and Procedures: AZD7798 and the placebo are given as an injection just under the skin.