Multicenter phase II study of trastuzumab in combination with epirubicin and docetaxel as first-line treatment for HER2-overexpressing metastatic breast cancer

The primary objective of study is to evaluate cardiac safety of trastuzumab in combination with epirubicin and docetaxel. HER2-overexpressing metastatic breast cancer patients were enrolled in a two-stage, multicenter phase II trial with weekly trastuzumab (4 and then 2 mg/kg) with epirubicin and docetaxel (either 75 mg/m2) on day 1 every 3 weeks. After eight courses of chemotherapy, trastuzumab was continued as a single agent. To assess cardiotoxicity, patients were evaluated for left ventricular ejection fraction (LVEF) at baseline, every two cycles during chemotherapy and trastuzumab, and every 3 months during trastuzumab alone. Cardiotoxicity was defined as signs and/or symptoms of congestive heart failure (CHF) and/or an absolute decrease in LVEF of ≥20 units or a decline to ≤45%. In the first stage of the study, three episodes of cardiotoxicity were observed (two asymptomatic declines of LVEF and one CHF) in 29 patients, and recruitment continued. During follow-up of patients who continued trastuzumab after chemotherapy, seven further cardiologic events occurred (three asymptomatic decline of LVEF and four CHF). Therefore, recruitment was interrupted after the 45th patient. The majority of cardiac events occurred late during trastuzumab alone, half were asymptomatic and all cases of CHF were resolved using cardiac therapy. Complete and partial responses were 20 and 47%, respectively, and the median time to progression was 15.7 months (95% CI, 11.6–19.0 months). In light of the cardiotoxicity experienced during this study, we currently recommend that this combination be used only in controlled clinical trials under vigilant cardiac monitoring.