The EPO Saga: The Demise of a Blockbuster Drug
Erythropoietin (EPO) is a hormone (protein) that regulates red blood cell production in humans. Back in the 1980s, scientists at a fledgling biotechnology company called Amgen determined that recombinant EPO was highly effective for treating anemia. Amgen owned the intellectual property rights to the EPO gene and decided to sell the recombinant protein encoded by EPO (called epoetin) as a treatment for anemia.EPO is known to alleviate fatigue caused by anemia by stimulating red blood cell production.
Amgen’s first EPO product, called Epogen, was approved in 1989 to treat patients suffering from anemia associated with renal failure. Procrit, Johnson and Johnson’s version of EPO (which was licensed from Amgen) was approved four years later in 1993 to treat chemotherapy-induced anemia. Aranesp, a longer acting version of EPO which is also manufactured by Amgen was approved in 2001 for anemia associated with chronic renal failure and in 2002 for chemotherapy-induced anemia in cancer patients. All of the EPO drugs have gained blockbuster status and, over the past five years or so, the annual revenue generated by these drug is estimated to be $6.0 to $12 .0 billion.
Since their approvals, EPO, Aranesp and Procrit have been administered to tens of millions of kidney dialysis and cancer patients undergoing chemotherapy with minimal safety concerns and generally positive outcomes. However, with the looming specter of generic biologics (EPO lost patent protection in 2004) and competition from companies like Roche developing competing EPO products, Amgen stepped up its efforts to promote and sell EPO and Aranesp. This, in turn, caused EPO drugs to be used by many physicians, which ultimately resulted in additional safety warnings and a label change for all EPO products. The label change coupled with unrelenting negative publicity about Amgen’s promotion of its EPO franchise, caused its stock price to plummet and forced the company late last year to lay off 14% of its workforce.
Like other biotechnology and pharmaceutical companies, Amgen sought to find ne indications for its EPO products. To that end, there was some compelling evidence several years ago which suggested that EPOmight increase survival of cancer patients, when used with radiation and chemotherapy. The idea was that higher oxygen levels in the blood would make the radiation or chemotherapy being used to treat the patients' cancer more effective. With this in mind, several groups of investigators initiated human clinical trials to determine whether EPO treatment would benefit non-anemic cancer patients. Unfortunately, the New York Times reports that results from no fewer than eight clinical trials suggest that EPO drugs might actually promote rather than slow tumor growth and hasten the death of cancer patients.
Amgen believes that the increased trial deaths among EPO-treated patients resulted from blood clots rather than by promoting tumor progression or growth. The company contends that the amounts of EPO used in the trials exceeded what is recommended in the drug label and, at those levels, blood clots are a known common side effect. On the other hand, there is a growing body of evidence from a variety of sources which suggests that some types of human tumors express EPO receptors, which when stimulated by EPO binding, induces tumor cell proliferation. To make matters worse, when Procrit was first approved to treat chemotherapy-induced anemia, FDA regulators suggested in briefing documents that there may be a “hypothetical risk” that EPO could stimulate tumor cell growth. Nevertheless, neither FDA nor most EPO experts believe at this time that a direct link between EPO use and tumor growth has been established. Everyone agrees that more research must be conducted to verify or refute this idea.
Tomorrow, an advisory committee to FDA will consider placing further safety restrictions on the use of EPO drugs. If they feel that blood clots were responsible for increased death among EPO-treated cancer patients then the recommendation would be relatively simple–only use the recommended modest levels of EPO to treat cancer patients as indicated on the product label. However, if they believe that EPO directly stimulates tumor growth then even the currently recommended modest doses of the drug may be too risky to treat cancer patients. Regardless of the outcome of the tomorrow’s FDA advisory meeting, it is clear that Amgen’s flagship EPO franchise may be in serious jeopardy.
Until next time….
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