May 21 2006
Anti-TNF (tumor necrosis factor) therapies are a tried and tested type of medication used for treating rheumatoid arthritis and the drugs provide benefit to many of thousands of patients worldwide.
Rheumatoid arthritis is a chronic autoimmune disease which causes chronic inflammation of the lining of the joints and can cause long-term joint damage, chronic pain, immobility and disability.
According to the Arthritis Foundation as many as 2 million Americans suffer from rheumatoid arthritis.
But now a new but controversial review is saying that rheumatoid arthritis patients treated with the new and potent "TNF-blocking" drugs have a higher risk of developing cancer and serious infections.
Dr. Eric Matteson, a professor of medicine and consultant in rheumatology at the Mayo Clinic says the review findings clearly indicate that the drugs contribute to the risk.
However this view is not consistent with other published studies examining the relationship between anti-TNF therapy in rheumatoid arthritis and malignancy and many and other experts disagree.
They query whether the drugs or the disease itself is responsible for the increased risk and say it is difficult to ascertain to what degree the drugs play a role.
The study says that more than half a million patients have been treated with TNF-blocking antibodies mainly because they have not responded to other treatments.
There are currently two types of anti-TNF agents available, infliximab (Remicade) and adalimumab (Humira).
Both drugs work by neutralizing the tumor necrosis factor(TNF), a protein believed to play a major role in rheumatoid arthritis and they are recognised as increasing the risk of serious infection.
In the new study the authors reviewed and analyzed nine randomized, placebo-controlled trials of the two drugs.
The trials involved as many as 3,500 patients receiving anti-TNF antibody treatment and more than 1,500 controls receiving a placebo treatment.
The researchers say they found that patients taking one of the two TNF-based treatments had a 3.3 times higher risk of developing cancer and 2.2 times the risk of serious infection than patients taking the placebo.
They also say that malignancies were significantly more common in people receiving higher doses, compared with patients receiving lower doses of anti-TNF antibodies.
According to the researchers one in every 154 people treated with either drug developed a cancer within six to 12 months, and one in 59 people developed a serious infection within three to 12 months.
An explanation for such a drug-related risk remains unclear but experts suggest that the drugs possibly interfere with the body's normal defenses against infection and against cancerous cells.
The general consensus appears to be that even if the drugs are responsible, the benefits probably outweigh the risks.
Matteson and his colleagues are now hoping to use the same methods to assess other medicines in their post-marketing phase.
Patients taking Anti-TNF medications are advised to continue to take their medication and discuss any concerns with their doctor.
The review is published in the current issue of the Journal of the American Medical Association.
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