CHICAGO Treating cancer patients with anemia drugs increases their risk of blood clots and death, U.S. researchers said on Tuesday, confirming concerns about these widely used drugs.
Researchers said the drugs, including Amgen Inc's Aranesp and Johnson & Johnson's Procrit, raised the risk of death by 10 percent in patients who took them, a finding that could not be explained by the higher blood clot risk alone.
"Our findings, in conjunction with basic science studies, raise the concern that the drug may be stimulating cancer and shortening cancer patients' survival," Dr. Charles Bennett of Northwestern University in Chicago said in a statement.
The study, which appears in the Journal of the American Medical Association, sent shares of both companies lower in extended-hours trading on Monday.
"The findings of mortality are new and are different from prior reports," Bennett said in a telephone interview. He said the drugs, erythropoiesis-stimulating agents (ESAs), also increased the risk of blood clots in the lungs and legs by 57 percent in cancer patients, confirming other findings.
An advisory panel to the U.S. Food and Drug Administration is due to discuss safety concerns about the drugs on March 13.
Eric Snyder, an analyst at Mehta Partners, said most investors expected the FDA panel meeting to result in tighter restrictions on the use of anemia drugs.
Worldwide sales of Aranesp fell 12 percent to $3.6 billion in 2007 compared with 2006, while sales of Procrit fell 9.4 percent to $2.9 billion over the same period.
Last March, the FDA warned of an increased risk of serious and life-threatening side effects in a public health advisory on ESAs. And last fall, the U.S. Centers for Medicare and Medicaid Services tightened its reimbursement policy for elderly cancer patients on ESAs.
The drugs generated up to $6 billion in cancer-anemia related sales last year for drug companies and represented Medicare's largest drug expenditure, Bennett said.
Anemia is a common complication of cancer treatment. Millions of cancer and kidney disease patients take ESAs, man-made versions of a human hormone that stimulate production of oxygen-carrying red blood cells.
Amgen spokeswoman Ashleigh Koss said the study does not define any new risks associated with ESAs, and the blood clot risk is included in current labeling.
She said doctors and patients need to weigh the drugs' benefit (avoiding a blood transfusion) and risks and use them appropriately.
J&J said in a statement the study's conclusions "do not provide an accurate reflection of the safety profile" of ESAs when used to treat chemotherapy-induced anemia.
"When used according to product labeling, ESAs remain safe and effective and are the only proven treatment alternative to blood transfusions for patients with chemotherapy-induced anemia," the company said.
Known as a meta-analysis, the study culled data from 51 clinical trials with 13,611 patients treated with ESAs or a placebo. It updates a 2006 report from the Cochrane Collaboration, which studies health-care issues, with additional data on 5,000 patients from 13 clinical trials, many of which addressed the issue of survival. The 2006 report did not show an increased risk of death.
The study is an update of a presentation Bennett made to the American Society of Clinical Oncology in June and includes data through January 17, 2008.
The drugs were approved by the FDA as a treatment for anemic cancer patients to avoid blood transfusions.
"The current FDA recommendation is these drugs are safe for cancer patients as long their hemoglobin levels aren't raised too high. Our data do not support that," Bennett said in a statement.
Dr. Michael Henke of the University of Freiburg, Germany, who worked on the latest analysis, said the study would likely affect treatment guidelines, and that more research was needed to understand the effects of the drugs on cancer patients.
"We suspect that ESAs activate survival pathways in cancer cells," Henke said.
J&J's shares fell 1.5 percent to $62.76 in after-hours trading, while shares of Amgen fell 1.9 percent to $46.90.
(Additional reporting by Deena Beasley; Editing by Toni Reinhold)