The list of warnings for a popular class of medicines that treats rheumatoid arthritis, Crohn’s and other autoimmune diseases continues to grow. The drugs will now include a boxed warning about the risk of cancer in children and adolescents, the FDA said today . The agency said its analysis of showed an increased risk of cancer, with cases occurring after an average of 30 months of treatment. The FDA said it’s working with the manufacturers to “explore new ways to further define the risk of cancer” in

children and adolescents. The medicines, which include J&J’s Remicade and Simponi, Amgen and Wyeth’s Enbrel, Abbott’s Humira and UCB’s Cimzia, must already warn against a potentially deadly fungal infection , histoplasmosis. The drugs work by inhibiting a protein called tumor necrosis factor. Among other functions, TNF plays a role in programmed cell death, so it makes sense that blocking TNF could theoretically raise the risk of cancer, which is uncontrolled cell growth.

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FDA: Rheumatoid Arthritis Drugs Raise Cancer Risks for Kids