Paclitaxel plus epirubicin in advanced breast cancer

This phase I-II study aimed to determine the maximum tolerated dose (MTD) of paclitaxel (Taxol), infused over 3 hours, when combined with a fixed dose (90 mg/m²) of epirubicin. Other aims were to investigate the combination's plasma pharmacokinetics, toxicity, and activity in 50 patients with previously untreated metastatic breast cancer, as well as its ability to mobilize peripheral blood stem cells (PBSCs). The initial dose of paclitaxel, 135 mg/m², was increased by 20 mg/m² in subsequent cohorts of six patients until dose-limiting toxicity (DLT) occurred. The DLT of the combination was febrile neutropenia in two of eight patients who received paclitaxel at 225 mg/m². The concentration of epirubicinol, the major metabolite of epirubicin, decreased from 47.3 ± 9.4 ng/mL at 175 mg/m² of paclitaxel to 37.9 ± 7.5 ng/mL at the 225-mg/m² dose. The most relevant toxicity was grade 4 neutropenia (61% of all the courses). Cardiac toxicity included three patients (6%) developing congestive heart failure responsive to therapy. Among 49 evaluable patients, 41 responses (84%) were observed (95% confidence interval [CI], 70% to 92%] and 9 (19%) of these were complete. In 21 patients, we evaluated the mobilization of PBSCs after this regimen plus a colony-stimulating factor. The median number of CD34+ cells was 61.7/μL (range, 6.8 to 201/μL), and a median of 6.3 x 10⁶/kg of CD34+cells have been harvested with a single leukapheresis.