MUNICH — Roughly one in four breast cancer patients will develop trastuzumab-mediated cardiomyopathy when the monoclonal antibody is used with adjuvant chemotherapy in real-world settings.
In the clinical trial setting, 5%–10% of women treated with trastuzumab (Herceptin) in the adjuvant setting experience asymptomatic left ventricular systolic dysfunction and 1% develop symptomatic heart failure, noted Dr. Deepa Wadhwa of the University of Manitoba, Winnipeg, at the annual congress of the European Society of Cardiology. Predictors of trastuzumab-mediated cardiomyopathy are preexisting hypertension, family history of premature coronary artery disease, and a smoking history.
Of 152 consecutive women who received trastuzumab in the setting of adjuvant chemotherapy for breast cancer, 36 (24%) developed trastuzumab-mediated cardiomyopathy. Serial multiple-gated acquisition scans showed that the mean left ventricular ejection fraction (LVEF) in affected patients fell from 63% at baseline to 51% after 3 months of trastuzumab, to 40% at 6 months, and to 38% at 9 months before partially rebounding to 44% at 12 months.
Of those 36 women, 31 remained asymptomatic, of whom 17 experienced at least partial recovery of LVEF within a year. So did three of the five women with symptomatic heart failure. The LVEF continued to decline further in six patients.
Dr. Wadhwa stressed the need for vigilance in the diagnosis and monitoring of trastuzumab-mediated cardiomyopathy. In the adjuvant setting, trastuzumab results in a 50% reduction in the risk of relapse and a 33% reduction in the risk of mortality from breast cancer. About one in four breast cancer patients has tumors that overexpress the HER-2 protein, making them eligible for trastuzumab.
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