Advances in immunology and genetics have identified new therapeutic targets to 
control inflammation and symptoms in patients with inflammatory bowel diseases 
(IBD). Despite the success of anti-TNF therapies in the treatment of IBD, a 
considerable proportion of patients are refractory to treatment, highlighting an 
unmet medical need for new therapies. Molecules that direct the trafficking of 
inflammatory cells, such as the α4β7 integrin, are attractive targets for new 
drug candidates. The α4β7 integrin is involved in lymphocyte recruitment to the 
normal and inflamed gut mucosa, and the lymphoid tissue. The pan-α4 integrin 
neutralizing mAb, natalizumab, is not gut-selective but has demonstrated 
efficacy in IBD. However, treatment was associated with the occurrence of 
progressive multifocal leukoencephalopathy, which has limited its use, 
especially in Europe. Vedolizumab (MNL-0002), Millennium Pharmaceutical's 
gut-specific, α4β7 integrin-neutralizing mAb, does not affect peripheral blood 
cell counts and appears to lack systemic effects. Data from phase II clinical 
trials of vedolizumab demonstrated efficacy with an attractive safety profile, 
especially in ulcerative colitis. Large phase III, multicenter trials in both 
ulcerative colitis and Crohn's disease will provide valuable data for the 
ongoing development of vedolizumab, which might evolve as a new 
anti-inflammatory treatment option for the management of therapy-refractory 
patients.