Interim Analysis of a Phase II study of epirubicin and paclitaxel as first-line therapy in patients with metastatic breast cancer.

Paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ), the first taxane to be used routinely in clinical practice, has aroused considerable interest for its high single-agent activity in breast cancer and its novel mechanism of action. The 4' epimer of doxorubicin, epirubicin is an agent with high activity against breast cancer but a lower rate of toxic side effects, especially cardiotoxic events, than its parent compound. Although the paclitaxel/doxorubicin combination has yielded response rates between 63% and 94% in phase I/II studies, some severe cardiotoxic events were reported. The rationale for our study was to evaluate the paclitaxel/epirubicin combination, focusing mainly on cardiotoxicity. In all, 57 patients with metastatic breast cancer entered the study, 28% of whom had primary metastatic breast cancer with large tumors at the primary site. Half of the patients had received adjuvant chemotherapy. Study medication consisted of 60 mg/m2 epirubicin given intravenously over 1 hour, followed by paclitaxel 175 mg/m2 administered as a 3-hour intravenous infusion after premedication with steroids, antihistamines, and H2 antagonists. The main toxicity was neutropenia (World Health Organization toxicity index grade 3/4, 72%). Other hematologic side effects were rare and no febrile neutropenia was reported. Peripheral neuropathy, arthralgia, and myalgia were mild (only World Health Organization grade 1 and 2). All patients had alopecia. The paclitaxel dose was escalated to 200 mg/m2 in eight patients, four of whom received a further escalation to 225 mg/m2. Severe neutropenia necessitated dose reductions in eight patients. No cardiac adverse events were reported. Of 41 patients evaluable for response, seven had complete remissions and 21 had partial remissions (68%). An additional 12 patients (29%) had stable disease. The combination of paclitaxel 175 mg/m2 and epirubicin 60 mg/m2 can be administered safely to patients with metastatic breast cancer. Although response was not the primary end point of this trial, the response data are nonetheless encouraging and suggest that further evaluation of the role of this combination in the first-line treatment of metastatic breast cancer is warranted.