Etanercept, marketed under the name Enbrel, is a drug that belongs to the class of drugs known as tumor necrosis factor (TNF)-alpha blocker. It is used primarily to treat rheumatoid arthritis, but has also been approved for use in treating polyarticular juvenile idiopathic arthritis, psoriatic arthritis, ankylosing spondylitis, and psoriasis.

On May 1st, the U.S. Food and Drug Administration (FDA) announced that it has required a warning label be added to Enbrel to increase the awareness of the risk of infections, particularly tuberculosis. The updated warning recommends screening for latent tuberculosis infection (LTBI) before beginning treatment with Enbrel.

It also warns that patients be monitored for possible antimicrobial treatment if the develop an infection and to stop taking Enbrel if a serious infection develops.

“Tuberculosis has been observed in patients receiving TNF-blocking agents, including Enbrel,” according to the warning. “Tuberculosis may be due to reactivation of latent tuberculosis infection or to new infection. Data from clinical trials and preclinical studies suggest that the risk of reactivation of latent tuberculosis infection is lower with Enbrel than with TNF-blocking monoclonal antibodies. Nonetheless, postmarketing cases of tuberculosis reactivation have been reported for TNF blockers, including Enbel.”

The warning’s section on adverse events now says, “In global clinical studies of 20,070 patients (28,308 patient-years of therapy), tuberculosis was observed in approximately 0.01% of patients. In 15,438 patients (23,524 patient-years of therapy) from clinical studies in the U.S. and Canada, tuberculosis was observed in approximately 0.007% of patients. These studies include reports of pulmonary and extra-pulmonary tuberculosis.”

The changes were distributed to clinicians in a letter from Amgen and Wyeth, which market the drug for the manufacturer, Immunex.