SAN FRANCISCO - Anemia drugs sold by Amgen Inc. and Johnson & Johnson raise the risk of blood clots and death in cancer patients, according to the largest study to date that links the medicines to potential harm.
About 7.5 percent of cancer patients who took Amgen's Aranesp or J&J's Procrit for anemia developed blood clots, compared with 4.9 percent who took placebos in trials of 13,000 patients, an analysis of 20 years of clinical trials found. The study, published in this week's Journal of the American Medical Association, found that people on the anemia drugs had a 10 percent higher risk of dying.
Amgen lost 32 percent of its market value last year after its anemia drugs were tied to risk of heart attack, stroke, and death at high doses. The Food and Drug Administration urged doctors to use the lowest doses possible. More than 4 million patients have taken Amgen's anemia medicines since 1989, the company said.
"There's a real potential risk here, and we as physicians need to do a better job of incorporating that risk into our practice," said study coauthor Samuel Silver, a hematologist/oncologist at the University of Michigan Medical Center in Ann Arbor.
Silver stopped short of saying he'd discontinue prescribing the medicines. The risk should be balanced against the danger of blood transfusions that patients might need if their anemia goes untreated, he said. The risks were mostly seen among patients taking high doses, he said.
A previous analysis didn't show the increased risk of death, although the newer research found it when more trials were included, Silver said. The increased risk of dying was seen when researchers combined 51 trials. Researchers can't say for certain why the patients died, Silver said.
Amgen and J&J's anemia drugs are used to treat patients whose weakness and fatigue is caused by chronic kidney disease and from the side effects of chemotherapy. The medicines stimulate the production of oxygen-carrying red blood cells, which may boost patients' energy and strength.
The anemia treatments are among the world's best-selling pharmaceuticals. Epoetin alfa, marketed as J&J's Procrit and Eprex, as well as Amgen's Epogen, generated $5.37 billion in worldwide sales in 2007, a 5.6 percent drop from the previous year. Amgen's Aranesp generated $3.61 billion in worldwide sales last year, a 12 percent decline from 2006.
Debate over the drugs' safety involves how big a dose to use to raise concentrations of hemoglobin, the protein that carries the oxygen. An FDA advisory panel is scheduled to meet March 13 to review the latest clinical trial results.
The risks of the anemia drugs are "well-defined," and the newly published analysis "looks exactly like what we've seen before," said Roger Perlmutter, Amgen's head of research and development.
Many of the trials that showed higher risk of death were originally designed to ask whether higher than recommended doses of the anemia drugs would help patients live longer, Perlmutter said, without looking at safety of the recommended dose. Amgen is working with the FDA to design a study to examine safety of the recommended doses, Perlmutter said.
Ortho Biotech, the J&J unit that markets Procrit, said the new study does not "provide an accurate reflection of the safety profile" of the anemia drugs. The products are safe and effective when used according to product labeling, the company said.
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