Biologic therapy in Crohn's disease: review of the evidence.

It is expected that within a few months, there will be commercially available in the United States a total of 3 biologic agents with inhibition of tumor necrosis factor-a (TNF-a) as the primary mechanism of action: infliximab, adalimumab, and certolizumab pegol. The primary efficacy data for each of these agents are reviewed. All 3 agents appear to be efficacious for both induction and maintenance of remission in Crohn's disease. There are no trials comparing these agents, but one can infer from available data that they have broadly similar efficacy. Adverse events associated with anti-TNF-a therapy, including infection, infusion reactions, autoimmunity, risk of malignancy, and neurologic events, are reviewed.