Drugs Known as ESAs Can Increase Risk of Tumor Growth and Death
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Reviewed By Louise Chang, MD
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FDA officials say Aranesp, Epogen, and Procrit will now carry "black-box" warnings alerting patients and doctors to lessen the risk of blood clots by using the lowest dose of medication needed to avoid the need for blood transfusion. The new boxed warning also includes information that they can increase risk for death or serious medical complication if used too aggressively in some patients.
The agency is also telling researchers to consider ending clinical trials involving the drugs.
Aranesp, Epogen, and Procrit are in a class of drugs called erythropoiesis-stimulating agents (ESAs) used to stimulate the production of red blood cells. The drugs are widely used in patients with chronic kidney failure (such as those with end-stage renal disease who require dialysis) and patients undergoing cancer treatments.
"Recent reports of studies with erythropoiesis-stimulating agents (ESAs) have shown a higher chance of serious and life-threatening side effects and greater number of deaths in patients treated with these agents," an FDA public health advisory says.
Quality-of-Life Claims Questioned
The drugs are used to prevent the need for blood transfusions in kidney failure and cancer patients. But officials indicated that doctors have increasingly used ESAs to boost red blood cells higher than the level needed to avoid transfusion in an effort to prevent fatigue in patients.
Six studies showing increased risks when ESAs were used to boost red cell counts to the higher levels led to Friday's warnings, the FDA says.
"The FDA reminds physicians that erythropoiesis-stimulating agents are approved for the reduction in red cell transfusion. For oncology patients these products have not been shown to improve or relieve symptoms of anemia or to improve quality of life," says Richard Pazdur, MD director of FDA's office of oncology drug products.
Amgen Inc. sold $4.1 billion worth of Aranesp last year, making it one of the company's top selling drugs.
Johnson & Johnson claimed Procrit can improve energy and quality of life in its direct-to-consumer advertisements, a claim the FDA now says it should no longer make.
Amgen and Johnson & Johnson are WebMD sponsors.
A web site for Procrit urged cancer patients to "find your energy during chemo using Procrit."
"That would not be appropriate at this time," Pazdur says.
He says the agency is also reviewing data that lead to quality-of-life indications for ESAs in kidney failure patients.
Internet sites promoting Aranesp and Procrit were taken down following an FDA news briefing Friday afternoon.
Both companies say they are informing doctors of the labeling changes.
"We remain confident in the safety and efficacy of Procrit when used according to its label," says Craig Tendler, a vice president at Ortho Biotech Products, a Johnson & Johnson division.
Tumor Promotion a Mystery
ESAs can lead to cardiovascular problems by increasing the risk of blood clots. But the drugs also appear to spur tumor growth, a fact that so far has perplexed scientists.
"We have no explanation for the mechanism," says Patricia Keegan, MD, director of the FDA's division of biologic oncology products.
The agency urged researchers to inform all study subjects participating in ESAs trials of new evidence of risks and to obtain written consents from them before continuing the studies.
"Investigators should re-evaluate whether clinical investigations should continue in light of this new safety data," Pazdur says.
SOURCES: FDA public health advisory, March 9, 2006. Richard Pazdur, MD, director, FDA's office of oncology drug products. Craig Tendler, vice president, Ortho Biotech Products. Patricia Keegan, MD, director, FDA's division of biologic oncology products.
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