Rheumatoid Arthritis Drugs' Link to Tuberculosis Examined
Aug. 17, 2001 (Gaithersburg, Md.) -- A committee of FDA experts urged continued close scrutiny of two established rheumatoid arthritis drugs for their links to serious side effects.
The drugs are Centocor's Remicade and Immunex's Enbrel, both of which became available in 1998. About 170,000 patients have taken Remicade, and more than 100,000 have taken Enbrel.
Centocor Friday briefed an FDA advisory panel on a new warning it is adding to Remicade labels. The warning will mention a possible tuberculosis (TB) risk in taking the drug and will urge doctors to give patients a TB skin test before prescribing the medication. If patients are diagnosed with TB, the warning says, doctors should begin treating the patient for TB before starting the drug.
The company says that Remicade appears to make it easier for inactive TB to become reactivated in some patients.
Remicade and Enbrel are a new class of medications that operate by reacting with a blood protein that is linked to the joint inflammation that characterizes rheumatoid arthritis. But by blocking this protein, the drugs also inhibit the immune system, making infections easier.
Most of the TB cases associated with the drug are with patients who were also taking corticosteroids or methotrexate, another medication used to treat rheumatoid arthritis, which can hinder the body's ability to fight infections.
Eighty-one Remicade patients have contracted TB since the drug hit the market, and 10 have died from the disease. According to Centocor, that boils down to a rate in the U.S. of 15 TB cases per 100,000 patients on the drug.
By contrast, Enbrel has been linked to just 11 TB cases since it came onto the market. Its label simply states that "rare" cases of the disease have occurred in patients on the drug.
FDA medical reviewer Jeffrey Siegel, MD, said that the drugs still provide enough benefit that they should remain available to patients.
Rheumatoid arthritis strikes an estimated 2.1 million Americans. Remicade is also approved to treat Crohn's disease, an inflammatory disease of the digestive tract, which affects about 500,000 Americans, according to Centocor.
The two medications got enthusiastic praise at the meeting from patients who said that the drugs had dramatically decreased their symptoms of rheumatoid arthritis or Crohn's disease, significantly improving their quality of life.
But both Enbrel and Remicade are associated with rare but serious side effects beyond TB, including other "opportunistic" infections. The drugs also have a link to worsened multiple sclerosis symptoms, lymphoma, lupus, aplastic anemia, and other abnormalities of the blood.
The drugs' labels already carry warnings containing this information. Enbrel has gone through five label revisions since it was approved, along with two broadly distributed letters to healthcare professionals on concerns with the drug.
Both drugmakers are in the midst of various safety studies to look at risks among thousands of patients on the medications.