FDA Ruling Is a Relief for Amgen's Anemia Drugs, but the Storm's Not Over Yet

(MoneyWatch)  The FDA's new safety plan for Amgen (AMGN)'s $5 billion anemia-drug franchise could have been worse, but the perfect storm battering these drugs is far from over.

Aranesp (darbepoetin alfa) and Epogen (epoetin alfa) are Amgen's biggest money-makers, with a combined $5.2 billion in 2009 sales. The anemia drugs are used for kidney disease and cancer, but studies linking them to shortened survival in some cancer patients, as well as to heart problems at high doses, have decimated sales.

R.W. Baird analyst Chris Raymond wrote recently that the number of cancer patients taking the drugs -- known collectively, along with Johnson & Johnson (JNJ)'s Procrit (epoetin alfa), as Erythropoiesis-Stimulating Agents (ESAs) -- fell from 60 percent in 2007 to just 29 percent today.

But ESAs got a little (relatively) good news this week. The FDA approved a plan to monitor use of the drugs in cancer, and it wasn't as harsh as it could have been. It requires doctors to get trained on the risks and benefits of ESA use, and to counsel prospective patients and provide them with a medication guide. But it doesn't mandate a patient registry or prior authorization, as some analysts had feared.

The reprieve, however, may be short-lived. As BNET has noted before, a Medicare advisory panel is set to review ESA use and reimbursement in kidney disease next month, and the FDA has said it too will convene a panel this year to review ESAs in kidney disease.

Then, in the second quarter, potential competitor Affymax (AFFY) will have data from four Phase III trials of Hematide. The drug is a synthetic, long-acting ESA that may show fewer side effects.

All of which makes Amgen's bone drug Prolia (denosumab), which Raymond called the big biotech's "key growth driver," all the more important.