The US Food and Drug Administration (FDA) is investigating a possible link between tumor necrosis factor (TNF) blockers, a class of drugs for treating arthritis and other conditions, and cancer risk in children.

In an early communication issued yesterday, 4th June, the FDA’s Center for Drug Evaluation and Research (CDER) said it was investigating the possible link between TNF blockers and the development of lymphoma and other cancers in children and young adults.

TNF drugs on sale in the US are marketed as Remicade, Enbrel, Humira, and Cimzia. They are used to treat children and young adults with Juvenile Idiopathic Arthritis (JIA, used to be called JRA, Juvenile Rheumatoid Arthritis), Crohn’s, and other diseases.

The federal agency is looking into about 30 reports of cancer in children and young adults, received via its Adverse Events Reporting System since TNF blockers were approved in 1998.

The reports describe cancer developing in children and young adults who started taking TNF blockers, as well as other drugs that suppress the immune system (such as methotrexate, azathioprine and 6-mercaptopurine). The patients were all under 18 when they started on the drugs and they were being treated for JIA, Crohn’s, and other diseases.

About half the cancers were of the lymphoma type, a cancer that affects the cells of the immune system and not recognized as a side effect of JIA or Crohn’s disease. The reports on these included both Hodgkin’s and non-Hodgkin’s lymphoma.

The reports also included leukemia, melanoma, and solid organ cancers.

The FDA said long term studies are needed to find out if TNF blockers increase cancer in children; short term studies are not enough to track cancers that take a long time to develop.

TNF blockers suppress the action of tumor necrosis factor, a protein that can cause inflammation and lead to immune system-related diseases. However, TNF is also involved in the signalling of cell death or apoptosis, a response used by the immune system when tumor cells are detected.

In the US, there are four drugs in the TNF blocker class: Remicade, Enbrel, Humira, and Cimzia, approved for the treatment of one or more of the following immune system diseases:

The prescribing information for these drugs already warns about the potential risk of cancer, and also, since 2006, the prescribing information for Remicade, warns about risk of hepatosplenic T cell lymphoma in children and young adults with Crohn’s disease treated with Remicade and immunosuppressive drugs such as azathioprine or 6-mercaptopurine.

The FDA has asked the makers of Remicade, Enbrel, and Humira to provide information about all reported cases of children on TNF getting cancer.

The makers of Cimzia have been asked to carry out a 10 year study of the drug’s long term risks, including cancer and lymphoma in particular.

The agency has also contacted experts to assess the possible link between TNF blockers and cancers such as lymphoma and to find out if there are particular groups of children and young adults with JIA and Crohn’s disease who may be at risk.

The FDA urged healthcare professionals and patients to report all side effects from using Remicade, Enbrel, Humira, and Cimzia. They can do this via the agency’s MedWatch Adverse Event Reporting program at

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Written by: Catharine Paddock, PhD