Herceptin Heart Failure, Cardiomyopathy Risk Highlighted in New Study

Potential side effects of Herceptin, Roche Holding’s breast cancer drug that is manufactured by Genetech, may pose a greater risk than originally believed, according to new research. 

A study conducted by the Group Health Research Institute and published this week online by the Journal of the National Cancer Institute found the risk of heart failure or cardiomyopathy among breast cancer patients who use Herceptin appears to be much higher than expected.

Herceptin, also known under its clinical name trastuzumab, is commonly used to treat HER2 positive breast cancer tumors. Breast cancer is one of the most common cancers found in the U.S with more than 232,000 new diagnoses reported in 2011 alone, and Herceptin is the leading treatment for HER2 breast cancer. The medication is often used with other anticancer chemotherapy drugs known as anthracyclines.

According to the findings of the study, conducted by Erin Aiello Bowles and co-authors at the Group Health Research Institute, the risk of heart failure was 1.4 times higher in the women treated with an anthracycline. However, the women treated with Herceptin alone, had more than a four times risk of heart problems compared to women who took no medication during treatment.

The highest increase in risk of heart failure was found in women who used both Herceptin and anthracyclines. These patients showed a risk seven times normal at their five-year assessments.

The study evaluated 12,500 women who were diagnosed with invasive breast cancer between 1999 and 2007 at eight different health facilities. The average age of each woman was 60, but the women’s ages ranged from 22 to 99. Each women received follow-up care and were evaluated between two and seven years following the onset of treatment.

Incidence of heart problems increased over time, but was found to pose the most threat when Herceptin and anthracyclines were used.

According to a prior study on the risk of heart failure with Herceptin, which was published last year in the Annals of Oncology, found patients who have used Herceptin were more likely to develop signs of asymptomatic cardiotoxicity and symptomatic congestive heart failure.

“Our study demonstrates the added value and potential of observational administrative data to complement clinical trials to achieve a more complete picture of cancer treatment safety,” wrote Bowles and co-authors of this new study.

Other studies have found that women treated with cancer drugs such as Herceptin and anthracycline chemotherapy drugs alone are at a higher risk for heart failure. However, the Group Health Research trial highlights not only the increased risk factor of using Herceptin alone, but of the increase in risk when it is used together with anthracyclines.