Mobilization of peripheral blood stem cells with docetaxel and cyclophosphamide (CY) in patients with metastatic breast cancer: a randomized trial of 3 vs 4 g/m2 of CY

The purpose of this study was to develop a regimen of docetaxel, cyclophosphamide (CY) and filgrastim for mobilization of peripheral blood stem cells (PBSC) in patients with metastatic breast cancer (n = 66). A phase I trial of CY 2, 3 or 4 g/m2 with docetaxel 100 mg/m2, in consecutive cohorts of four patients each, did not reveal any dose-limiting toxicities and subsequent patients were randomized to receive 3 or 4 g/m2 of CY. The median yield of CD34+ cells from all patients was 11.06 × 106/kg (range, 0.03–84.77) from a median of two aphereses (range, 1–7); 6.52 × 106 CD34+ cells/kg/apheresis (range, 0.01–52.07). Target CD34+ cell doses ⩾2.5 and ⩾5.0 × 106/kg were achieved in 89% and 79%, respectively. There were no statistically significant differences in CD34+ cell yields or target CD34+ cell doses achieved following 3 or 4 g/m2 of CY. Patients with only one prior chemotherapy regimen yielded a median of 12.82 × 106 CD34+ cells/kg/ apheresis compared to 5.85 for those receiving ⩾2 regimens (P = 0.03). It was concluded that the combination of docetaxel, 100 mg/m2, CY 3 g/m2 without mesna could be administered with acceptable toxicity with collection of adequate quantities of PBSC from the majority of patients.