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Study finds no clinically significant difference in effectiveness of drugs for managing anemia in patients undergoing cancer treatment

Cancer patients who are undergoing chemotherapy or radiation treatment often suffer from anemia, a deficiency of red blood cells that is measured by hemoglobin concentration. A blood transfusion can quickly restore a low hemoglobin concentration, and adverse events related to transfusion are uncommon.

Drugs that mimic the actions of erythropoietin, a hormone that helps regulate red blood cell production, can be used to correct anemia and reduce the need for transfusions. Two such erythropoietic stimulant drugs are commercially available in the United States—epoetin alfa (sold as Epogen and Procrit) and darbepoetin alfa (sold as Aranesp), a newer, longer acting drug that requires fewer injections. The two drugs, epoetin and darbepoetin, show no clinically significant difference in improving hemoglobin concentration and reducing the need for transfusion, according to the latest comparative effectiveness review by the Agency for Healthcare Research and Quality.

The report, Comparative Effectiveness of Epoetin and Darbepoetin for Managing Anemia in Patients Undergoing Cancer Treatment, was produced by AHRQ's Effective Health Care Program, the first Federal program designed to compare alternative treatments for significant health conditions and make the findings public. The program is intended to help patients, health care providers, and others in choosing the most effective treatments.

The review compared the effectiveness and safety of the two drugs. Both epoetin and darbepoetin reduce the need for transfusion. However, there is no evidence that the drugs, when added to cancer treatment, improve survival. The report finds that many other significant questions remain unanswered about the safety and best use of both drugs.

In particular, the review sought to determine whether darbepoetin differed from epoetin in its ability to achieve key treatment goals. For some of these goals, such as reducing transfusion need, the evidence showed the drugs did not differ significantly. For others, such as improving quality of life, it was uncertain whether either drug had a meaningful effect.

The review also sought evidence to define the most effective use of the drugs, including the appropriate target hemoglobin level, patient characteristics for predicting responses to treatment, when treatment should be initiated or discontinued, optimum dosing strategies, and duration of treatment. In general, the data were insufficient to answer these questions.

The review identified significant research gaps, including the effects on survival, tumor progression, and the risk of adverse events when the drugs are administered as currently recommended. Most studies did not provide complete reporting on adverse events. The report also said that more research is needed to determine whether small improvements in quality of life survey scores translate into noticeable improvements for patients.

Key findings of the report included the following:

• The evidence shows no clinically significant difference between epoetin and darbepoetin in hemoglobin response. The two drugs were equally effective in increasing hemoglobin concentration.
• No statistically significant difference was found between epoetin and darbepoetin in reducing the need for transfusion. Pooled results of trials showed approximately 30 percent of patients treated with epoetin or darbepoetin underwent transfusion, compared with 50 percent of untreated patients.
• Studies directly comparing epoetin and darbepoetin showed no statistically significant difference in the rates of thromboembolic events (blood clotting). While these rates varied widely, pooled results showed approximately 7 percent of patients treated with either drug experienced a thromboembolic event, compared with 4 percent of untreated patients. Some studies sought to maintain hemoglobin levels higher than recommended on product labels, but the evidence was insufficient to determine whether this increased the risk of thromboembolic events.
• Overall, quality of life measures tended to favor treatment with either drug, but the selection of measures and reporting of results were inconsistent. Individual trial results were variable and, more important, the clinical significance of study results on quality of life is uncertain.
• The limited evidence available suggests that the drugs do not improve solid tumor response to cancer therapy. One study reported that erythropoietic stimulants might decrease survival, and another study suggested that the drugs might accelerate progression of some cancers; however, both of these findings remain uncertain.

Under the Effective Health Care Program, the review of epoetin and darbepoetin will be updated as significant new evidence becomes available. The report is available at http://www.effectivehealthcare.ahrq.gov. Copies of the executive summary of the report (AHRQ Publication No. 06-EHC008-1) are available from the AHRQ Publication Clearinghouse.

Editor's note: The report on drugs for anemia in patients undergoing cancer treatment was prepared by the Blue Cross and Blue Shield Association Technology Evaluation Center Evidence-based Practice Center (Chicago), one of 13 such centers working under contract with AHRQ to generate syntheses of evidence regarding health care issues for AHRQ's Effective Health Care Program. The program compares the effectiveness of different interventions, including drugs, to better inform consumers, health care providers, and others as they make treatment choices. The Effective Health Care Program Web site (http://www.effectivehealthcare.ahrq.gov) includes features for the public to participate in the Effective Health Care Program. Users can sign up to receive notification when new reports are available. They can also be notified when draft reports and other features are posted for comment, and comments can be submitted through the Web site. The public is also invited to use the Web site to nominate topics for review by the Effective Health Care Program.

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