This article is part of the Arthritis Archives.
Editor note: On November 2, 1998, the FDA announced the approval of Enbrel for the treatment of rheumatoid arthritis (RA).
Dateline: July 22, 1997
Data from an ongoing study of the drug Enbrel (etanercept), used for the treatment of rheumatoid arthritis, was presented last month in Singapore at the International League of Associations for Rheumatology conference. The open-label, multi-center study is designed to measure the long-term safety of Enbrel, generic name etanercept, developed by Immunex, in 106 rheumatoid arthritis patients. Patients also are being monitored for improvement in symptoms. All of the patients in the study had previously received the drug for a maximum of three months in an earlier trial and experienced a recurrence of symptoms when the drug was stopped.
How It Works
A genetically engineered protein in the drug Enbrel blocks a natural substance in the body called tumor necrosis factor, or TNF. TNF is present in the joints of rheumatoid arthritis sufferers and activates cells which cause pain and inflammation. Enbrel is used to disarm or counteract TNF.
In the study, clinical improvement is defined by at least a 20 percent improvement in tender, swollen joints. In this ongoing trial, 78 patients have received the drug for at least six months. At six months, it was found that 82 percent of patients showed improvement in swollen joints and 88 percent had an improvement in tender joints. 11 patients have received Enbrel for one year and 91 percent displayed a 20 percent improvement in swollen and painful joints. The results of laboratory tests were consistent with the clinical findings seen to date.
Enbrel was generally well tolerated by the patients in the ongoing study. Injection site reactions were relatively mild and infrequent, seen in only two percent of all injections given (163 out of 6,857 injections given). 39 out of 85 patients reported infections, including colds, during treatment during 547 patient months. All infections resolved and no patient withdrew from the study due to infections or injection site reactions. No antibodies against the drug have been found in patients tested to date.
Continuation Of The Study
The current retreatment trial will continue until all patients have received Enbrel for a minimum of one year. The study is part of a comprehensive program to investigate the drug's ability to reduce or eliminate the signs, symptoms, and progression of rheumatoid arthritis. A Phase III double-blind, randomized, placebo-controlled, multi-center study of Enbrel is also underway.
"We, as rheumatologists, need new therapies like TNF receptor to better treat the chronic disease of rheumatoid arthritis," said Larry Moreland, M.D., principal investigator, from the University of Alabama at Birmingham. "These data are exciting because they support the efficacy we have seen to date and at the same time show that the drug can be given safely over a longer period of time." However, the raging optimism for this new drug is being tempered by the advice of Dr.Gary S. Firestein and Nathan J. Zvaifler of the University of California at San Diego who have cautioned patients "to avoid excessive enthusiasm for the results of short-term studies." Firestein and Zvaifler stated that there could be consequences to blocking TNF (tumor necrosis factor) because it serves several useful functions in the body. They also noted that past new treatments for the rheumatoid arthritis turned out to have little value because they either lost effectiveness or produced serious side effects.
Related Resources - Enbrel (etanercept)
Sources: Drug Eases Pain Of Rheumatoid Arthritis, USA Today, July 17, 1997; New Drug May Ease Pain, Swelling Of Rheumatoid Arthritis, CNN Interactive, July 16, 1997
First published: 7/22/1997