Johnson & Johnson (JNJ) is warning doctors that patients taking its rheumatoid arthritis drug Remicade (search) may have a higher risk of lymphoma (search), a blood cancer, the company said on Friday.

Remicade is not related to the arthritis drug Vioxx (search), which was pulled off the market last week by Merck & Co. Inc. (MRK) after a study showed it doubled the risk of heart attack and stroke.

Remicade's label will be revised to warn of a three-fold increase in the risk of lymphoma for rheumatoid arthritis patients taking the drug, said Michael Parks, a spokesman for Centocor, the J&J unit that markets Remicade.

The change means the drug's safety profile will be more closely aligned with that of rival drugs in the same class: Amgen Inc.'s (AMGN) Enbrel (search) and Abbott Laboratories Inc.'s (ABT) Humira (search). All three drugs block an inflammation-causing protein called tumor necrosis factor (search), or TNF.

The TNF-blockers have been among the most successful of all biotechnology drugs, with combined sales of $4.1 billion in 2003. Those sales show no sign of slowing. But some analysts say the revised label for Remicade casts an additional shadow over a class that is already attracting a small but growing amount of concern.

In August, U.S. health officials said 12 Californians who had taken Remicade or Enbrel had tested positive for tuberculosis. Two of those infected died, and a report from the Centers for Disease Control and Prevention (search) said that as the use of these blocking agents expands, associated cases of TB might increase.

"This just spotlights the fact that there is no long-term safety data on this class of drugs and it's not clear what else is going to come out of the closet," said Henry Dummett, an analyst at World Markets Research Center. "That represents a downside risk to their long-term sales potential."

J&J said it would send a letter to doctors on Monday alerting them to the revised label for Remicade.

It will be the second time in three months that Remicade's label has been changed. In August, J&J added the risk of certain blood-related disorders such as leukopenia (search), in which the white blood cell count is too low, and thrombocytopenia (search), when blood platelets are too low.

Thomas Schaible, vice president of medical affairs at Centocor, said the company has been working with the Food and Drug Administration (search) since the agency last year indicated it would request similar warning labels for Remicade, Enbrel and Humira. Abbott changed its label early this year, and Amgen changed late last year.

Schaible said J&J submitted its change of label request to the FDA in March and received the agency's sign-off only recently.

"I don't think its a coincidence that J&J is doing this now, right after Vioxx and the troubles GlaxoSmithKline has had," said David Webster, president of Webster Consulting Group. "I think that pharmaceutical companies are going to get very conservative about serious side effects, especially in populations with non-life-threatening conditions."

In June, New York Attorney General Eliot Spitzer (search) accused GlaxoSmithKline Plc (GSK) of suppressing important, negative information about the use of its antidepressant Paxil (search) in children.

Rheumatoid arthritis affects about 2.1 million people in the United States. Remicade was approved in 1998 to treat Crohn's disease. It was approved for rheumatoid arthritis in 1999.

J&J shares were down 56 cents, or 1 percent, to $55.36 in midday trading on the New York Stock Exchange.