TNF blockers and cancer in children and young people

The US Food and Drug Administration (FDA) is investigating a possible link between tumour necrosis factor (TNF) blockers (sold as Remicade, Enbrel, Humira and Cimzia) and lymphoma and other cancers in children and young adults. TNF blockers are used to treat juvenile idiopathic arthritis (JIA, formerly called juvenile rheumatoid arthritis), Crohn's disease and other conditions.

About 30 cases of cancer were reported in children and young adults over the ten years from 1998, when the first TNF blocker was approved, to 29 April 2008. They had started TNF blockers at 18 or younger, often together with other immune-suppressing drugs such as methotrexate, azathioprine or 6-mercaptopurine, for JIA, Crohn's disease or other conditions. About half the cancers were lymphomas, both Hodgkin's and non-Hodgkin's (lymphoma is a cancer of immune system cells, and isn't a usual complication of JIA or Crohn's disease). Others included leukaemia, melanoma and solid organ cancers. As these cancers can occur in children anyway, long-term studies are needed, especially because cancer takes a long time to develop.

TNF blockers suppress the immune system by blocking TNF, a substance in the body that drives inflammation and immune diseases. Four are approved in the United States for one or more immune diseases, including JIA, rheumatoid arthritis, psoriatic arthritis, plaque psoriasis, Crohn's disease and ankylosing spondylitis. Remicade is approved for Crohn's disease in children and Enbrel for JIA.

The labels of all four already warn of a possible cancer risk, and since 2006 the Remicade label has warned of hepatosplenic T-cell lymphoma in teenagers and young adults with Crohn's disease treated with Remicade plus azathioprine or 6-mercaptopurine. The FDA asked the makers of Remicade, Enbrel and Humira to report all cancers in children using them, and the makers of Cimzia will run a ten-year study of long-term risks starting in 2009.

For now, the FDA believes the benefits of TNF blockers outweigh the possible risks in children and young adults. Patients shouldn't stop treatment without talking to their doctor.