* Some patients on TNF blockers had a rare blood cancer
* FDA updating some product labels
WASHINGTON, April 14 (Reuters) - U.S. health regulators have received more reports of rare blood cancer in young patients taking a class of anti-inflammatory drugs used to treat digestive disorders.
The drugs, called tumor necrosis factor (TNF) blockers, are used to treat Crohn's disease and ulcerative colitis that cause inflammation of the digestive system.
They include such widely used products as Merck & Co Inc's <MRK.N> and Johnson & Johnson's <JNJ.N> Remicade and Simponi, Amgen Inc's <AMGN.O> Enbrel, Abbott Laboratories Inc's <ABT.N> Humira and UCB SA's <UCB.BR> Cimzia.
The Food and Drug Administration has previously warned of an increased risk of lymphomas and other cancers associated with the use of TNF blockers in children and adolescents.
In its communication on Thursday, the FDA said the blood cancer, known as Hepatosplenic T-Cell Lymphoma or HSTCL, was reported primarily in adolescents and young adults who were taking TNF blockers, as well as other drugs such as azathioprine that also suppress the immune system and mercaptopurine, a leukemia drug.
The product labels for Remicade and Humira have been updated and the product labels for azathioprine and mercaptopurine were being updated to include warnings about HSTCL, the FDA said on its website.
The majority of the cases reported were in patients being treated for Crohn's disease or ulcerative colitis, the FDA said, but the reports also included a patient being treated for psoriasis and two patients being treated for rheumatoid arthritis.
TNF blockers suppress the immune system by blocking the activity of TNF, a substance in the body that can cause inflammation and lead to immune-system diseases. (Reporting by Esha Dey, editing by Gerald E. McCormick)
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