THURSDAY, March 13 (HealthDay News) -- When a U.S. Food and Drug Administration advisory panel meets Thursday to weigh whether blood-boosting drugs are safe to use in cancer patients suffering from anemia, the question will not be an easy one to answer.

According to FDA briefing documents filed this week, there are now a total of eight clinical trials that suggest these widely used medications, sold as Epogen and Aranesp by Amgen Inc. and as Procrit by Johnson&Johnson, actually speed the growth of tumors and shorten the lives of cancer victims. Known as erythropoiesis-stimulating agents (ESAs), they work by stimulating red blood cell production.

"Whereas at the time of approval safety concerns were theoretical, there is now mounting evidence of documented effects on survival, tumor progression, and thrombotic events which require a re-assessment of the net benefits of this class of drugs," FDA officials stated. "Based on data provided to FDA, there is no evidence that ESAs improve quality of life or cancer outcomes."

Although Thursday's meeting is only the latest in a long string of FDA actions concerning the potential dangers of these drugs since their approval in the early 1990s, the panel will be considering the possibility of completely withdrawing approval of these medications for use in cancer patients. The panel will also look at less drastic options that include less severe restrictions for patients with certain cancers or no hope of a cure and a plan that would require cancer patients to sign consent forms before starting the anemia treatments.

This isn't the only group of patients using ESAs that concerns the FDA. In kidney patients, past research has found that if these drugs are used to raise hemoglobin levels above 12 grams per deciliter of blood, the risk of death increases.

The growing body of evidence led the U.S. Food and Drug Administration to have the drugs' manufacturers add a "black box" warning to the medications last November. The warning indicates that the medications should be used at the lowest possible doses to avoid risks such as blood clots, heart attacks, stroke, congestive heart failure, increased tumor growth and an increased risk of death. The FDA also noted the trials generally indicated an increased risk when blood levels were raised above 12 grams per deciliter.

"This new information further underscores the safety concerns regarding the use of ESAs in patients with cancer, which [the] FDA addressed in previous communications," Dr. Janet Woodcock, director of the Center for Drug Evaluation and Research, said in a statement last November.

Just last week, Amgen, which manufactures all three drugs, agreed to expand the "black box" warning to include information about tumor growth and death in patients with early-stage breast cancer and cervical cancer.

When Procrit was first approved in 1989, the drugs were touted as a treatment to lessen fatigue and improve quality of life among cancer and HIV patients with anemia, but the revised label states there was no evidence to back that claim. The label change was the fifth such change since Procrit's approval, FDA officials said.

Results of two studies released in February were not among the six studies that led to the November label revision, but they will be part of the evidence that the FDA panel examines during its meeting Thursday. Taken together, all eight studies show more rapid tumor growth or shortened survival when patients with breast, non-small cell lung, head and neck, lymphoid or cervical cancers received ESAs compared to patients who didn't get this therapy, the FDA said.

In statements released this week, both companies defended the safety of their drugs, when used according to recommended dosages, for the treatment of chemotherapy-induced anemia. However, FDA documents noted there is no evidence to suggest lower doses are any safer.

More information

For more on ESAs, go to the U.S. Food and Drug Administration.

SOURCES: March 11, 2008, briefing documents, U.S. Food and Drug Administration; March 12, 2008, statement, Johnson&Johnson

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