October 5, 2004
System Helps Curb Severe Anemia
CHICAGO—Cooperation among international adverse event reporting agencies has led to an 83 percent decline in a rare, potentially life-threatening form of anemia associated with recombinant human erythropoietin (epoetin), a widely used product for anemia that occurs among cancer patients or persons undergoing dialysis.
Epoetin is the most successful biotechnology product marketed today, with annual worldwide sales of $10 million.
The predominant formulation associated with this surprising and serious toxicity was EprexÂ®, a formulation of epoetin that is sold in Canada, Europe, Asia, and Australia but not the United States.
Almost 200 patients with chronic kidney disease worldwide have developed an extremely rare syndrome called pure red-cell aplasia, in which antibodies to recombinant erythropoietin develop and attack a natural hormone in the body that is responsible for producing red blood cells. The resultant anemia is extremely severe and requires almost daily blood transfusions
In an article in the September 30 issue of the New England Journal of Medicine, Charles L. Bennett, MD, PhD, and a group of researchers from Northwestern University, the Jesse Brown VA Medical Center, and institutions in Italy and France describe how national health agencies in Europe and Canada collaborated with pharmaceutical manufacturers of epoetin to find the cause of and reduce the incidence of pure red-cell aplasia associated with use of the drug.
Dr. Bennett is professor of medicine in the Division of Hematology/Oncology at Northwestern University’s Feinberg School of Medicine and a leading investigator at The Robert H. Lurie Comprehensive Cancer Center of Northwestern University, as well as associate director of the Veterans Affairs Midwest Center for Health Services Research and Policy Studies.
Worldwide, 191 reports of epoetin-associated pure red cell aplasia were recorded; 92 percent of cases involved the use of subcutaneous administration of Eprex to persons receiving renal dialysis. Although epoetin is widely used by cancer patients, none of the cases of pure red-cell aplasia occurred in cancer patients.
The number of cases of epoetin-associated pure red-cell aplasia began to increase dramatically in patients with chronic kidney disease in France, England, Spain, and Canada in 1998 and peaked in 2001 in the three European countries and in Canada in 2002.
In 1998 the formulation of Eprex marketed in Europe was changed in response to concern that the human serum albumin used to manufacture the drug could transmit a variant of Creutzfeldt-Jakob disease.
Also, countries with large numbers of cases had been administering the new formulation of Eprex subcutaneously to dialysis patients, while countries without any cases administered the product intravenously.
Beginning in 2002 in Europe and one year later in Canada, after improvements were made in storing and handling Eprex and switching to intravenous administration to patients with chronic kidney disease, the incidence of Eprex-associated pure red-cell aplasia decreased by 83 percent, dropping nearly to pre-1998 levels, Dr. Bennett said.