CHICAGO – Rheumatoid arthritis patients taking Humira or Remicade face triple the risk of developing several kinds of cancer and double the risk of getting serious infections, a study led by the Mayo Clinic found.
The analysis builds on previous reports about the risks associated with Abbott Laboratories' Humira and Centocor's Remicade. But the earlier research focused mostly on one kind of cancer — lymphoma — and infections such as tuberculosis and pneumonia.
The new study found an apparent link to other cancers, too, including skin, gastrointestinal, breast and lung tumors. It also quantifies the risks and says high doses appear to be the riskiest.
While the drugs' packaging information mentions some of the risks, the manufacturers said the new study does not prove that the medication is at fault, and they said the research was flawed.
Study co-author Dr. Eric Matteson, a Mayo Clinic rheumatologist, stressed the overall chances of developing cancer while using these drugs is still small. The researchers also noted that the medications' benefits include improving flexibility and range of movement, easing pain and increasing life expectancy, which arthritis can shorten.
In addition, the researchers noted that the risks for individual patients probably vary widely. Older, sicker people who have taken the drugs for several years probably face the highest risks, they said.
Still, the researchers said patients should be made aware of the dangers and told to seek medical help if they develop fevers, coughs or other symptoms of infection. They should also be sure to undergo the cancer screenings recommended for the general public, the researchers said.
Their study appears in Wednesday's Journal of the American Medical Association.
Matteson is working with Centocor in developing a new drug that works similarly, and he and co-author Dr. Tim Bongartz have been paid consultants to Abbott for unrelated work, but neither company funded the study. The Mayo Foundation sponsored the research.
Rheumatoid arthritis affects more than 2 million Americans, and involves a malfunctioning immune system that attacks joints throughout the body, causing pain, deformities and disability.
Dr. John Klippel, president of the Arthritis Foundation, said the study will probably not change doctors' minds, because scores of patients have benefited from the drugs. Remicade was approved in 1998, Humira in 2002.
More than a half-million patients have been treated with the two injectable drugs and a third similar medication, Enbrel, all of which block production of a protein linked with inflammation.
Enbrel was not included in the study because it differs at the molecular level, Matteson said. He said he is getting paid by Enbrel marketers Wyeth and Amgen to do a similar analysis on Enbrel alone.
The researchers analyzed data from nine studies comparing Humira or Remicade with placebos and pooled the results. There were 29 cancers in 3,493 patients who received at least one dose of either drug, compared with three cancers in 1,512 patients on placebos.
Serious infections occurred in 126 patients on drugs and 26 on placebos. They included pneumonia and cellulitis.
Tom Schaible, Centocor vice president of medical affairs, said most of the analyzed studies used higher-than-recommended Remicade doses. "There's clearly a favorable benefits-risks ratio" with recommended doses, Schaible said.