Herceptin (chemical name: trastuzumab) is a targeted therapy medicine used to treat HER2-positive breast cancer. Heart muscle damage and heart failure are potentially serious side effects of Herceptin.
A small study has found that after 3 months of Herceptin treatment, nearly 58% of women had some loss of heart function. The study used heart ultrasounds (echocardiograms) to evaluate the women's heart health. The results suggest that heart problems caused by Herceptin are more common and may happen earlier than many doctors think. The results also suggest that monitoring for possible heart problems should be done regularly from the start of Herceptin treatment.
The results were presented at the European Society of Cardiology EuroEcho meeting.
HER2-positive breast cancers make too much of the HER2 protein. The HER2 protein sits on the surface of cancer cells and receives signals that tell the cancer to grow and spread. About one out of every four breast cancers is HER2-positive. HER2-positive breast cancers tend to be more aggressive and harder to treat than HER2-negative breast cancers.
Herceptin works by attaching to the HER2 protein and blocking it from receiving growth signals. Herceptin, which is given intravenously, is approved by the U.S. Food and Drug Administration (FDA) to:
- treat advanced-stage, HER2-positive breast cancers
- lower the risk of recurrence (the cancer coming back) of early-stage, HER2-positive breast cancers with a high risk of recurrence
A newer form of Herceptin, Herceptin Hylecta (chemical name: trastuzumab and hyaluronidase-oysk), can be given as an injection.
Women treated with Herceptin may have side effects, including:
- high blood pressure
- joint and back pain
- hot flashes
Some women on Herceptin will have a loss of heart function during treatment. In rare cases, heart failure develops. Heart function can recover when Herceptin treatment stops.
Other research has shown that heart problems caused by Herceptin are more likely to happen in:
- older women
- women with diabetes
- women with preexisting cardiovascular risk factors such as high blood pressure, high cholesterol, and obesity
In this small study, researchers monitored heart function in 51 women being treated with Herceptin for advanced-stage HER2-positive breast cancer. The women's average age was 55 and many of them had heart risk factors such as high blood pressure, high cholesterol, and being obese. Before starting Herceptin, all the women had an echocardiogram to evaluate heart function. After 3 months of Herceptin, the women had another echocardiogram.
After 3 months:
- 57.9% of the women showed some signs of heart function problems (reduction in left ventricular systolic function)
- 19.4% of the women showed signs of the beginning of heart failure (impaired ventricular relaxation)
The results suggest that heart problems related to Herceptin are more common and may happen earlier than many doctors think. The researchers who did this study believe that a baseline echocardiogram should be done before treatment with Herceptin is started and that regular heart function monitoring should be done when Herceptin treatment starts -- as frequently as every 3 to 4 weeks.
If Herceptin is or will be part of your breast cancer treatment plan, you may want to ask your doctor about this study. It's a good idea to ask your doctor about your personal risk of Herceptin-related heart damage and how your heart function will be evaluated before and during Herceptin treatment.
In the Breastcancer.org Herceptin pages, you can learn more about how Herceptin works, when it's used, and what to expect during treatment.
Editor’s Note: This article was updated with information about Herceptin Hylecta, which the FDA approved on Feb. 28, 2019.