Cardiac Toxicity of Trastuzumab-Related Regimens in HER2-Overexpressing Breast Cancer

The pivotal trial by Slamon and colleagues of trastuzumab combined with chemotherapy in metastatic breast cancer showed a high incidence of congestive heart failure (CHF) among patients who had received trastuzumab and anthracycline-based therapy simultaneously. As a result, the development of nonanthracyclinebased treatment options for patients with HER2-overexpressing breast cancer has garnered significant attention. This review discusses the cardiac toxic effects of trastuzumab and trastuzumab-related regimens and how their mechanisms of action and physiologic effects differ from cardiac toxicity typically associated with anthracycline use. An overview of cardiac safety data from selected trials of trastuzumab in combination with a taxane after anthracyclines for HER2-overexpressing early-stage breast cancer shows rates of symptomatic or severe CHF of < 4% and asymptomatic declines in left ventricular ejection fractions of > 10 points in ≤ 30% of patients. For metastatic breast cancer, severe CHF has been reported in 2% of patients and ejection fraction declines in 6%–18% of patients. However, interstudy comparisons of chemotherapy-induced cardiac dysfunction are difficult because of the use of different definitions of cardiac dysfunction and different parameters for assessing cardiac safety. Recent data on cardiac safety of taxane/trastuzumab–based combination regimens demonstrate that the docetaxel/carboplatin/trastuzumab triple combination can offer clinical efficacy with a low risk of cardiac dysfunction in patients with HER2-overexpressing early-stage breast cancer as well as in patients with metastatic breast cancer.