An epirubicin/paclitaxel combination mobilizes large amounts of hematopoietic progenitor cells in patients with metastatic breast cancer showing optimal response to the same chemotherapy regimen

Background and Objectives. Based on our preliminary experience, we have further evaluated the capacity of the paclitaxel/epirubicin combination (at the dose of 175 and 90 mg/m(2), respectively) plus G-CSF to mobilize hematopoietic progenitors into the circulation. Design and Methods. The study was conducted in a homogeneous cohort of 25 stage IV breast cancer patients showing response to three cycles of the same chemotherapy regimen and who were included in a high-dose chemotherapy program. Results. In most cases (68%) more than 5x10(6) CD34(+) cells/kg b.w. (the threshold fixed in our study) were collected by a single leukapheresis, 28% and 4% of patients requiring 2 and 3 procedures, respectively. Based on the CD34(+) cell count in the peripheral blood, most of the leukaphereses (53%) were performed on day 11 after chemotherapy. More than 50 CD34(+) cells/mL along with a preleukapheresis WBC count between 10 and 20x10(9)/L predicted that only a single harvest would be required in 100% of cases. The evaluation of the clonogenic potential of collected cells showed that a large number of committed colony-forming cells (CFCs) and more primitive longterm culture-initiating cell (LTC-IC) hematopoietic progenitors were present in 20 harvests studied. Interpretations and Conclusions. These data demonstrate that the epirubicin/paclitaxel combination followed by G-CSF, besides being a very active regimen in MBC, is effective in releasing large amounts of progenitor cells into the circulation which can then be safely employed to support myeloablative regimens. (C)1999, Ferrata Storti Foundation.