Wednesday, October 11, 2000
WASHINGTON -- Doctors should be cautious in prescribing a new rheumatoid arthritis treatment to patients who also have multiple sclerosis, and should watch out for serious anemia in anyone who uses the drug, the manufacturer warned yesterday.
There's no proof that Enbrel actually causes or worsens MS symptoms, or that it causes dangerous anemia, the Food and Drug Administration said.
But Seattle's Immunex Corp. wrote 100,000 doctors and pharmacists yesterday to alert them that rare cases of such problems have been reported in Enbrel users, and thus physicians should consider precautions when treating certain patients.
Among the reports: 11 cases of certain "demyelinating" diseases -- a specific type of nerve disorder that includes MS -- and 10 cases of blood-cell shortages, including dangerous aplastic anemia, that leave patients vulnerable to infection. Five blood-disorder patients died.
Enbrel has been driving Immunex's stock price since its approval two years ago. The drug has been widely seen as Immunex's first big blockbuster with sales potential of $2 billion a year by 2003.
Analysts have estimated that sales of the drug, which has been approved for use in both children (juvenile arthritis) and adults with both early and late-stage rheumatoid arthritis, could hit as much as $839 million this year compared with $541.7 million last year.
Reports of anemia and MS symptoms among drug users are rare -- more than 80,000 people have taken Enbrel since the FDA approved it in late 1998. It is considered highly effective at treating painful rheumatoid arthritis, and at slowing the disease's joint destruction.
But last year, the FDA warned that six Enbrel users had died of infections, and said doctors should watch for serious side effects.
Because the anemia can be life-threatening, patients should seek medical care if they develop such symptoms as persistent fever, bruising, bleeding or pallor, Immunex warned. Doctors should consider stopping the drug if patients have significant blood abnormalities.
As for MS, there is no evidence it strikes Enbrel users more often than it strikes the general population, said the FDA's Dr. Karen Weiss. But other studies suggest that people with arthritis should be cautious in picking a treatment.
Shares of the biotechnology company rose 4.7 percent to close at $42
in trading yesterday on the Nasdaq Stock Market.
P-I staff contributed to this report.
© 2000 Bloomberg News Service