Biological therapy for inflammatory bowel disease

Biological therapy refers to the use of medication that is tailored to specifically target an immune or genetic mediator of disease. Even for diseases of unknown cause, molecules that are involved in the disease process have been identified, and can be targeted for biological therapy; many of these molecules, which are mainly cytokines, are directly involved in the immune system. Biological therapy has found a niche in the management of cancer,autoimmune diseases, and diseases of unknown cause that result in symptoms due to immune related mechanisms.

Inflammatory bowel disease, or IBD, is a collection of systemic diseases involving inflammation of the gastrointestinal tract. IBD includes two (or three) diseases of unknown causation: ulcerative colitis, which affects only the large bowel; Crohn's disease, which can affect the entire gastrointestinal tract; and, indeterminate colitis, which consists of large bowel inflammation that shows elements of both Crohn's disease and ulcerative colitis.

Although the causes of these diseases are unknown, genetic, environmental, immune and other mechanisms have been proposed. Of these, the immune system plays a large role in the development of symptoms. Given this, a variety of biological therapies have been developed for the treatment of these diseases. These have changed the way physicians treat Crohn's disease and ulcerative colitis.

Prior to the development of biological therapy as a modality to treat IBD, other medications that modulate the immune system—including 5-aminosalicylates, steroids, azathioprine, and other immunosuppressants—were primarily used in treatment. Patients with Crohn's disease that developed complications, including fistulae (= abnormal connections to the bowel) were treated with surgery. Patients with ulcerative colitis who do not respond to medications are still treated with colectomy (= removal of the colon).

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