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/m 2 with docetaxel 100 mg/m 2 , 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/m 2 of CY. The median yield of CD34 + cells from all patients was 11.06 x 10 6 /kg (range, 0.03-84.77) from a median of two aphereses (range, 1-7); 6.52 x 10 6 CD34 + cells/kg/apheresis (range, 0.01-52.07). Target CD34 + cell doses ≥2.5 and ≥5.0 x 10 6 /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/m 2 of CY. Patients with only one prior chemotherapy regimen yielded a median of 12.82 x 10 6 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/m 2 , CY 3 g/m 2 without mesna could be administered with acceptable toxicity with collection of adequate quantities of PBSC from the majority of patients.