Phase I studies of combined paclitaxel/epirubicin and paclitaxel/epirubicin/cyclophosphamide in patients with metastatic offast cancer: the French experience.

In an attempt to develop new, active, and convenient outpatient combination-chemotherapy regimens for patients with metastatic breast cancer, we performed two phase I studies combining paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) plus anthracycline for the first-line treatment of metastatic disease, without the use of hematopoietic growth factors. Study I was designed to test the tolerability and antitumor activity of a 3-hour infusion of paclitaxel in combination with an epirubicin intravenous bolus. Study 2 explored a three-drug chemotherapy regimen: a 3-hour paclitaxel infusion with epirubicin and cyclophosphamide. Courses were repeated every 3 weeks. If any dose-limiting events occurred in two or more of six patients in the first course of a given dose level, that dose level was defined as the maximum tolerated dose. Dose-limiting criteria included the following: neutrophils less than 0.25 x 10(9)/L lasting for > or = 5 days, any febrile neutropenia, World Health Organization grade 4 thrombocytopenia, World Health Organization grade > or = 3 nonhematologic toxicity or grade > or = 3 mucositis for more than 5 days, and absence of hematologic recovery at day 35. In both studies, paclitaxel doses were escalated in subsequent groups of three to six patients. For study I, the initial dose level consisted of paclitaxel (110 mg/m2)/epirubicin (50 mg/m2). To date 40 patients have entered the study at eight dose levels. Of the 181 cycles evaluated, grade 3 or 4 neutropenic episodes were observed in 63% of courses, with only five episodes of febrile neutropenia. Grade 2 or 3 neurotoxicity was observed in 43% of patients. Two patients experienced clinical heart failure. The dose-limiting toxicity has not been reached so far. At dose level 7 (paclitaxel [250 mg/m2]/epirubicin [50 mg/m2]), only one patient of six experienced febrile neutropenia. We are currently testing paclitaxel (200 mg/m2)/epirubicin (75 mg/m2). Preliminary evaluation of response documents two complete and 16 partial responses in 37 evaluable patients (48% overall response rate). In study 2, the initial dose level consisted of paclitaxel (150 mg/m2)/epirubicin (50 mg/m2)/cyclophosphamide (500 mg/m2). To date, three dose levels have been investigated in 16 evaluable patients (82 cycles). Grade 3 or 4 neutropenic episodes were observed in 80% of courses, and five episodes were associated with neutropenic fever. Grade 2 neurotoxicity was observed in 28% of patients. The dose-limiting toxicity has not been reached, and we are currently investigating dose level 4 (paclitaxel 225 mg/m2). These trials confirm the tolerability of combined paclitaxel/epirubicin and paclitaxel/epirubicin/cyclophosphamide. The antitumor activity is encouraging.