Positioning biologic agents in the treatment of Crohn's disease.

One decade after the emergence of biologic therapy for Crohn's disease (CD), our treatment algorithms are beginning to change. Once reserved for patients with refractory disease, disease unresponsive to conventional therapies, or those requiring multiple courses of corticosteroids, there is increasing evidence that early, aggressive interventions with immunosuppressants or biologic therapies targeting tumor necrosis factor-alpha or alpha-4 integrins can alter the natural history of CD by reducing the transmural complications of structuring and fistulization and the nearly inevitable requisite for surgical resections. More recent trials are beginning to suggest that intervention with combination therapy for selected patients with a poor prognosis may modify the long-term course of CD. Selection of patients with features predicting a complex or progressive course and early, combined intervention is now possible. Future studies are still needed to best identify predictors of response to individual agents with differing mechanisms of action, as well as to optimize the risk-benefit of long-term maintenance therapy.