Regulators in the USA have given notice that they are conducting a safety review into the possible link between the use of tumour necrosis factor blockers and the development of lymphomas and other cancers in children and young adults.

The US Food and Drug Administration is investigating approximately 30 reports of cancer in youngsters who were treated with TNF blockers (along with other immuno-suppressive drugs) such as methotrexate, azathioprine or 6-mercaptopurine) for juvenile idiopathic arthritis and Crohn’s disease. The review, which covers the last ten years, has shown that about half of the cancers were lymphomas and included both Hodgkin’s and non-Hodgkin’s lymphoma.

The TNF blockers that are being looked at are Johnson & Johnson/Schering-Plough's Remicade (infliximab), Abbott Laboratories' Humira (adalimumab), Amgen's and Wyeth's Enbrel (etanercept) and UCB's Cimzia (certolizumab pegol). The FDA noted that the prescribing information for all four TNF blockers warns about the possible risk of cancer, while Remicade’s label already includes a warning of the risk of hepatosplenic T cell lymphoma in children and young adults with Crohn’s disease.

The agency has asked the drugmakers of the TNF blockers approved for use in children (Remicade, Enbrel and Humira) to provide information about all cases of cancer reported in that group of patients. It is also requiring Nektar Therapeutics, which makes Cimzia for UCB, to conduct a study to assess long-term risks, including lymphoma and other cancers, to begin in 2009. It will take about 10 years to complete.

Wyeth and Amgen responded quickly to the news of the review and said that they are continuing to work with the agency to evaluate the overall risk benefit of Enbrel in paediatric patients. However they stressed that in the FDA’s early communication, the agency stated that at the current time, it believes that “the potential benefits of the use of TNF blockers outweigh the potential risks” in youngsters having one of the aforementioned diseases.

The FDA concluded by saying that until its evaluation is completed, “healthcare providers, parents, and caregivers should be aware of the possible risk…when deciding how to best treat these patients”.