Two decades ago, the first reports of the use of monoclonal antibodies targeting 
tumour-necrosis factor α heralded a revolution in treatment options for moderate 
to severe Crohn's disease and ulcerative colitis. Nonetheless, patients with 
refractory disease or loss of treatment response are all too familiar to 
gastroenterologists. Preventing the infiltration of the gastrointestinal mucosa 
by circulating cells of the immune system using antibodies targeting the 
adhesion molecules involved represents an attractive new treatment option. 
Vedolizumab has recently received European and US regulatory approval for 
treatment of ulcerative colitis and Crohn's disease on the basis of encouraging 
results from one of the largest phase III trial programmes ever conducted in the 
field of inflammatory bowel diseases and promising safety data. Are we now 
seeing another revolution in the management of inflammatory bowel disease, and 
how can this new drug best be used in clinical practice?