Etrolizumab is being developed for adults with moderate to severe Crohn’s disease (CD). CD is an inflammatory bowel disease (IBD) that can affect any part of the digestive system. It causes inflammation, which results in difficulty absorbing nutrients from food. Symptoms of moderate to severe CD include vomiting, abdominal pain, loss of weight, frequent diarrhoea, and digestive system obstruction. There is no cure for CD and current treatments focus on lessening and managing symptoms of the condition. Etrolizumab is a new biological entity which is given as an under the skin injection. This treatment prevents cell death caused by inflammation. It does so be blocking two receptors that are thought to have a role in IBD. If licenced, etrolizumab would offer an additional treatment option for patients with moderate to severe CD that cannot have other current treatments, or where treatments have stopped working.