IMPORTANCE - Trastuzumab is a life-saving therapy but is associated with symptomatic and asymptomatic left ventricular ejection fraction (LVEF) decline. We report the cardiac toxic effects of a nonanthracycline and trastuzumab-based treatment for patients with early-stage human epidermal growth factor receptor 2 (ERBB2, formerly HER2 or HER2/neu)-positive breast cancer.
OBJECTIVE - To determine the cardiac safety of paclitaxel with trastuzumab and the utility of LVEF monitoring in patients with node-negative, ERBB2-positive breast cancer.
DESIGN, SETTING, AND PARTICIPANTS - In this secondary analysis of an uncontrolled, single group study across 14 medical centers, enrollment of 406 patients with node-negative, ERBB2-positive breast cancer 3 cm, or smaller, and baseline LVEF of greater than or equal to 50% occurred from October 9, 2007, to September 3, 2010. Patients with a micrometastasis in a lymph node were later allowed with a study amendment. Median patient age was 55 years, 118 (29%) had hypertension, and 30 (7%) had diabetes. Patients received adjuvant paclitaxel for 12 weeks with trastuzumab, and trastuzumab was continued for 1 year. Median follow-up was 4 years.
INTERVENTIONS - Treatment consisted of weekly 80-mg/m2 doses of paclitaxel administered concurrently with trastuzumab intravenously for 12 weeks, followed by trastuzumab monotherapy for 39 weeks. During the monotherapy phase, trastuzumab could be administered weekly 2-mg/kg or every 3 weeks as 6-mg/kg. Radiation and hormone therapy were administered per standard guidelines after completion of the 12 weeks of chemotherapy. Patient LVEF was assessed at baseline, 12 weeks, 6 months, and 1 year.
MAIN OUTCOMES AND MEASURES - Cardiac safety data, including grade 3 to 4 left ventricular systolic dysfunction (LVSD) and significant asymptomatic LVEF decline, as defined by our study, were reported.
RESULTS - Overall, 2 patients (0.5%) (95% CI, 0.1%-1.8%) developed grade 3 LVSD and came off study, and 13 (3.2%) (95% CI, 1.9%-5.4%) had significant asymptomatic LVEF decline, 11 of whom completed study treatment. Median LVEF at baseline was 65%; 12 weeks, 64%; 6 months, 64%; and 1 year, 64%.
CONCLUSIONS AND RELEVANCE - Cardiac toxic effects from paclitaxel with trastuzumab, manifesting as grade 3 or 4 LVSD or asymptomatic LVEF decline, were low. Patient LVEF was assessed at baseline, 12 weeks, 6 months, and 1 year, and our findings suggest that LVEF monitoring during trastuzumab therapy without anthracyclines could be simplified for many individuals.