U.S. FDA to ask panel about anemia drug limits

U.S. health officials will ask an advisory panel whether they should withdraw the approval of Amgen Inc and Johnson & Johnson anemia drugs for cancer chemotherapy patients or take other steps to minimize risks, documents released on Tuesday said.

Food and Drug Administration staff pointed to eight studies that showed evidence of harmful effects, including shorter survival or faster tumor growth, when used at high doses.

“There is now mounting evidence of documented effects on survival, tumor progression, and thrombotic (clotting) events which require a reassessment of the net benefits of this class of drugs,” FDA staff wrote in an analysis prepared for a panel of outside experts that meets Thursday.

The panel is set to review the risks of the drugs - which include Amgen’s best-selling drug, Aranesp, and Johnson & Johnson’s Procrit - when given to cancer patients. The drugs also are sold for patients with kidney disease.

Amgen shares fell 1.3 percent to $44.12 in afternoon trading on Nasdaq. Shares of Johnson & Johnson gained 1 percent to $61.93 on the New York Stock Exchange.

Aranesp sales were $3.6 billion in 2007, while Procrit sales hit $2.9 billion. Procrit is much less important to diversified health-care company Johnson & Johnson than Aranesp is to the smaller Amgen.

The drugs, known as erythropoiesis-stimulating agents (ESAs), are genetically engineered versions of a protein that boosts production of oxygen-carrying red blood cells.

The companies said the drugs’ benefits outweighed risks for chemotherapy patients when used appropriately.

Each of the eight studies cited by FDA staff involved high doses to drive blood hemoglobin above levels now recommended.

FDA staff said for most cancers there was “insufficient” data to rule out a risk of deaths or tumor growth when the drugs are used at recommended doses, and new results may not be available for years.

“The uncertainty regarding the risks of ESAs when used in accordance with product labeling has not been satisfactorily addressed,” FDA staff said.

The advisory panel will be asked about various options, including whether to remove approval for all chemotherapy patients or restrict the drugs for patients with certain types of cancer or who cannot be cured, the FDA documents said.

Industry analysts said they expected the panel to back some restrictions but it was unclear how drastic they would be.

JP Morgan analyst Geoffrey Meacham said in a report that withdrawing all use for chemotherapy-induced anemia was “unlikely” but would be a “disaster scenario” if it were to happen, possibly cutting $1 billion from 2008 revenue estimates for Amgen.

Michael King, an analyst with Rodman & Renshaw, estimated a 10 percent chance the panel would take that approach, and 30 percent that it would call for an end to use in breast cancer.

In a note to clients, King said it was encouraging the FDA said it would ask the panel to weigh other strategies such as limited distribution programs or changes to patient consent forms.

Amgen and J&J, in a summary also prepared for the FDA panel, said the drugs “continue to provide significant benefits,” including the reduction of blood transfusions, that outweigh risks when used appropriately.

FDA staff said studies showed the drugs reduce the chances of getting a blood transfusion by 20 to 30 percent but do not eliminate them. Risk of serious infections from blood transfusions also has decreased since the first ESA drug was approved for chemotherapy patients in 1993, FDA staff said.

The companies said “the weight of evidence has not indicated a clear effect of ESAs on mortality or tumor progression” when used as directed.

They added that “real concerns remain that these risks have not been adequately excluded” when used according to prescribing instructions. The makers said communicating safety concerns through product labeling and education “will minimize risk as the necessary data are acquired” from new and ongoing studies.