Anemia drugs cause blood clots with no change in transfusion needs

Kathleen Blanchard's picture
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New findings show that drugs given commonly to cancer patients to treat anemia could lead to complications from deep vein thrombosis or pulmonary embolism. The drugs, known as erythropoiesis-stimulating agents (ESA’s), increase the production of red blood cells to counteract the effects of chemotherapy drugs that destroy red blood cells. However, the new study shows that the high-cost anemia drugs also raise the risk of blood clots that can be life threatening, and do not reduce the need for blood transfusions.

ESA’s are also used in patients with kidney failure. The medications currently carry a black box warning from the FDA issued in 2007 regarding the risk of death from thrombosis (blood clot), heart attack, stroke and heart failure. In medical practice, clinicians are advised to use the medications to keep hemoglobin levels at the lowest level possible to avoid the need for blood transfusions. The new findings suggest the anemia drugs may carry more risks than benefits.

According to Dr. Hershman, the Florence Irving Assistant Professor of Medicine and Epidemiology at Columbia University Medical Center, "This research answers important questions about outcomes of ESAs when used in long-term clinical practice with oncology patients. While ESAs were given to reduce the need for blood transfusions, a substantial reduction in the use of blood transfusions was not observed. However, an increase risk of deep vein thrombosis or pulmonary embolism was confirmed."

The new finding comes from real life practice versus clinical trials. Dr. Hershman says, "This new finding is significant because where the meta-analysis looked at pooled data from randomized clinical trials, this data is from community practice – real-life clinical settings – where you can often see things that wouldn't necessarily show-up in a short-term, 12-week study. Additionally, this analysis included data from more than 50,000 patients– including those with more advanced cancer or high-risk status, who therefore might not have been candidates for clinical trials." Though the anemia drugs show increased risk for blood clots, Dr. Hershman says there is no increased risk of mortality associated with ESA’s given to cancer patients.

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Researchers looked at the incidence of deep vein thrombosis and pulmonary embolism among a large group of cancer patients most likely to receive ESA’s during chemotherapy, between 1991 and 2002. The study was also done during a time when use of the drugs to treat anemia increased ten-fold.

Roughly half of patient treated with chemotherapy were also receiving ESA’s by 2002, yet the rate of blood transfusion was 22 percent per year throughout the time period. More patients receiving the anemia drugs developed blood clots.

The authors say the drugs used to treat anemia are expensive, a point worth noting for public policy makers. Sales of ESAs were 10 billion dollars in 2006. Aranesp, one such drugs, was approved by the FDA in 2001 and was Amgen Pharmaceutical company's third biggest drug in 2008 - the company is also being sued for violating anti-kickback laws.

The authors write, “Further efforts at monitoring use and long-term toxicity of expensive oncology drugs should be put in place to ensure that for any drug the benefits outweigh the risks in community practice.”

Given the increased risk of blood clots associated with the drugs to treat anemia, combined with the findings that they did not decrease the need for blood transfusions among cancer patients, leads the study authors to suggest that eliminating the drugs could lead to decreased Medicare part B spending, decreasing the high cost of cancer treatment.

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