June 4, 2008 -- The FDA is investigating whether cancers in about 30 children and young adults are linked to the use of Remicade, Enbrel, Humira, or Cimzia to treat childhood arthritis, Crohn's, or other diseases.

The cancers occurred over a 10-year period beginning in 1998.

Remicade is approved for use in children to treat Crohn's disease. Enbrel and Humira are approved for use in children to treat juvenile idiopathic arthritis, formerly known as juvenile rheumatoid arthritis.

The drugs block a molecule, called tumor necrosis factor or TNF, thereby switching off immune responses that make joints and tissues swell and redden. The drugs help calm overactive TNF in patients with certain types of arthritis, Crohn's disease, severe psoriasis, and other autoimmune diseases. But TNF is also part of the body's defense against cancer.

On their labels, all of the drugs list cancer -- particularly lymphoma, a cancer of white blood cells -- among their serious possible side effects. The labels warn patients and their parents that the drugs lower the body's ability to fight off infections.

The FDA has asked the makers of the drugs approved for children to provide information about all cases of cancer reported in children taking the drugs. The maker of Cimzia is required to conduct a long-term safety study of the product, which will begin in 2009.

"At the current time, the FDA believes that the potential benefits of the use of TNF blockers outweigh the potential risks in certain children and young adults having one of the diseases for which the TNF blockers are approved to treat," the FDA says in an "early communication" statement. "Until the evaluation is completed, healthcare providers, parents, and caregivers should be aware of the possible risk of lymphoma and other cancers in children and young adults when deciding how to best treat these patients."

During its investigation, which is expected to take six months, the FDA says it will consult medical experts to assess the potential link between these drugs and cancer. The investigation will also look at whether there are certain children with juvenile arthritis or Crohn's disease who may be at particular risk of developing cancer.