The latest data on cases of antibody-mediated pure red cell aplasia associated with Johnson & Johnson subsidiary Janssen-Cilag's erythropoietin product Eprex/Erypo (epoetin alfa) have suggested that measures put in place to enhance the safety of the drug have been effective, according to a Merill Lynch analysis. The finding also suggests that manufacturing issues may not in fact have lain at the heart of the problem.
PRCA, a serious and sometimes life-threatening adverse reaction, first emerged at the end of 2001 in a number of patients with chronic renal failure treated with Eprex. It has been suggested that a change in the manufacturing of the drug may be at fault. Eprex is made at a plant in Puerto Rico for sale outside the USA, while in J&J's home market, the drug is manufactured by Amgen, and the latter's version has not been linked to PRCA.
At the time, J&J maintained that the fault lay in a widespread switch from intravenous to subcutaneous administration in the mid-to late-1990s. Last year, J&J altered the labelling to advise against SC administration of its product.
As of end-December 2002, 224 confirmed and suspected cases of PRCA had been brought to the attention of regulators, up from 188 at the last review in October of that year. New Eprex cases in 2002 increased from 22 to 43, while cases with a rival EPO product increased to nine from six.
"The jump in Eprex cases may concern some investors," noted the analysts. "However, our checks with the company indicate that the number of new cases actually declined in second-half 2002 following the label changes." Specifically, of the 43 Eprex-related PRCA cases reported as of December, 29 occurred in the January-June timeframe (prior to the label change) with just 12 in July-December.
Merrill Lynch believes that the effect of PRCA on Eprex sales going forward will be minimal, and they are forecasting 2003 sales will rise 10 per cent to $4.7 billion.