TNF has the capacity to play both good guy and bad guy in the immune system. Normally, it helps mediate infection. But in people with rheumatoid arthritis, which is an immune disorder, excessive amounts of TNF in the bloodstream do harm by provoking debilitating joint inflammation. The new drugs, Remicade (currently used to treat Crohn’s disease and anticipating government approval for rheumatoid arthritis by the end of the year) and Enbrel (now on the market for the disease) work by soaking up TNF and deactivating it.
The data, while still preliminary, is encouraging. X-rays show that after one year of treatment, patients taking methotrexate (a standard rheumatoid-arthritis drug) and a placebo suffered about eight times more bone damage–such as holes and thinning–than patients taking Remicade with methotrexate, according to Dr. Daniel Furst, an investigator in Remicade’s ongoing trial. The combination worked so well that last month researchers made the unusual decision to allow placebo patients to switch to Remicade before the end of the study. Investigators for Enbrel say their X-ray data also shows declines in the normal rate of joint destruction.
There is reason for caution. The drugs don’t work for all. They require special administration: Enbrel is self-injected twice a week, Remicade given intravenously about every two months. They’re costly to manufacture and thus far pricier than standard treatments–at least $7,000 to $12,000 per year. While the drugs have caused few serious side effects so far, long-term reactions are unknown. Patients could be susceptible to infections and even some cancers since the drugs work by interfering with the immune system (Enbrel’s label warns off users with infections). For now, though, there is optimism about the anti-TNF approach as heralding a new era in the treatment of a ravaging disease.
