Biologic Response Modifiers

Infliximab (Remicade) is the first genetically-engineered drug to be approved for Crohn's disease and ulcerative colitis. The drug is a specially designed antibody (monoclonal antibody) which acts against tumour necrosis factor (TNF?) — a cytokine associated with the inflammatory process in IBD. Infliximab is given as an intravenous infusion, initially 3 times over 6 weeks and then every 8 weeks.

Trials have shown infliximab can heal fistulas and help patients with moderate to severe Crohn's disease who have not responded to standard treatments. The most common side effects are: headache, chills, and fever associated with the infusion of the drug. Some patients have experienced breathing problems, joint swelling, autoimmune reactions, and increased rates of infections, although these effects are rare. Of concern are reports of some cases of lymphoma (a rare cancer of the lymph glands) and an increased susceptibility to reactivation of tuberculosis infection in people who have been previously exposed to the infection. The risk of tuberculosis can be significantly reduced by screening for the infection before treatment with infliximab and the risk of lymphoma may be related more to the use of other immunosuppressive drugs, such as azathioprine or 6-mercaptopurine, than to infliximab.

Adalimumab (Humira) is also an antibody that has been specially designed to block the action of tumour necrosis factor (TNF?). Adalimumab is given as a subcutaneous injection (under the skin) every second week.

Adalimumab has been approved for use in the treatment of Crohn’s disease, where it has been shown to improve symptoms and induce and maintain remission. There is also data from studies that suggest that it is effective in healing fistulas in Crohn’s disease and in keeping them healed.

The most common side effect with adalimumab is irritation of the skin around the injection site. This is usually mild. As with infliximab there is an increased risk of infections and there have also been reports of lymphoma (a rare cancer of the lymph glands). There is also the potential for reactivation of tuberculosis infection in people who have been previously exposed to the infection. The risk of tuberculosis can be significantly reduced by screening for the infection before treatment with adalimumab and the risk of lymphoma may be related more to the use of other immunosuppressive drugs, such as azathioprine or 6-mercaptopurine, than to adalimumab.

Other biologic response modifiers that alter other aspects of the body's immune response are under investigation.