Etrolizumab is in clinical development for the treatment of adult patients with moderately to severely active ulcerative colitis. Ulcerative colitis is a long-term condition where the colon and rectum (parts of the bowel), become inflamed. Small ulcers can develop on the colon’s lining, which can cause rectal bleeding and recurring diarrhoea. The symptoms of ulcerative colitis often follow a pattern where individuals with the condition have periods of no symptoms or mild symptoms (remission) followed by periods where their symptoms are particularly troublesome (flare-ups or relapses).
Etrolizumab is a new monoclonal antibody (an immune protein) delivered by subcutaneous injection. The treatment works by targeting molecules called integrins to control the immune response and prevent the accumulation of immune molecules, which cause inflammation in individuals with a form of ulcerative colitis where inflammation is not mediated by a signalling protein called tumour necrosis factors (TNF) alpha ('non-TNF-alpha’) and who are therefore intolerant to TNF blockers. This represents a new target group as current therapies focus mainly on anti-TNF inflammation. In one study, etrolizumab showed a greater reduction of intestinal lymphocyte infiltration in comparison to standard treatment.