The Food and Drug Administration approved Immunex Corp.'s genetically engineered drug, Enbrel, for treatment of the debilitating symptoms in advanced rheumatoid arthritis. It is one of a wave of biotechnology medicines expected to come to market to treat illnesses believed to be caused by the immune system.
In a study of 234 patients with advanced disease, 59 percent who took Enbrel for six months improved significantly, compared with 11 percent who received placebo injections. About 40 percent of Enbrel patients saw their disease symptoms cut in half. Patients require injections of the drug twice weekly, costing about $200 a week.
Enbrel targets tumor necrosis factor, or TNF, an immune system protein that also causes rheumatoid inflammation. Enbrel is a genetically engineered copy of a cell "receptor," the spot where TNF normally hooks onto cells to do its damage. When Enbrel is injected, it sops up excess TNF in the patients' blood before the substance can reach the joint. It appears to have few side effects.
Scientists disclosed data at the American College of Rheumatology meeting last month showing that a genetically engineered arthritis drug called Remicade, can provide relief to patients with rheumatoid arthritis. Like Enbrel, the experimental drug being developed by Centocor, Inc., blocks TNF. Remicade was recently approved for treating Crohn's disease. It could be approved for use for rheumatoid arthritis by next summer. Centocor is studying the use of Remicade in asthma and psoriasis. Meanwhile, Amgen, Inc. is in the early stages of testing a drug similar to Enbrel.
At the same meeting, Hoecht AG released data that its drug, Arava, can slow the progression of joint damage in arthritis patients.
The FDA also has granted priority review status for the G.D. Searle's celecoxib (Celebrix) for acute and chronic use in the treatment of osteoarthritis and rheumatoid arthritis and for the management of pain. The drug is a member of the class of cyclooxygenase-2, or COX-2, inhibitors which are believed to block production of inflammation-causing prostaglandins. Pfizer will copromote the drug with Searle. Merck will soon file for approval of its COX-2 inhibitor, MK-966 (Vioxx). SmithKlein Beecham and Wyeth-Ayerst currently sell COX-2 inhibitors.