MOBILIZATION OF PERIPHERAL-BLOOD PROGENIT OR CELLS WITH CONVENTIONAL CHEMOTHERAPY

Autologous peripheral blood progenitor cells (PBPC) rescue after high- dose chemotherapy has been used progressively as a form of treatment i n some solid and hematologic tumors. This increasing use can be explai ned by both advantages of PBPC rescue over bone marrow rescue (decreas e in the duration of marrow aplasia, reduction of platelet transfusion s, earlier discharge from hospital, potential use in patients with ina dequate bone marrow reserve) and the low number of aphereses (one or t wo) needed to collect a sufficient number of progenitor cells for auto grafting. High-dose chemotherapy is likely to be increasingly used aft er the results of two recently reported studies in which treatment wit h high-dose compared with standard-dose chemotherapy increases overall survival in metastatic breast cancer patients and relapsed lymphoma p atients. After the initial use of unselected mobilizing regimens regar dless of the patient characteristics and the tumor type, now it seems more useful to optimize this approach. Mobilization of PBPC can be obt ained by several approaches, Moderate or high doses of single agent al one (e.g. cyclophosphamide 4-7 g/m(2)) or some hematopoietic growth fa ctors alone (e.g. G-CSF, GM-CSF) have been proven to be adequate mobil izing agents. However, the use of hematopoietic growth factors alone m ay disadvantageously delay the start of an effective chemotherapy. An efficient mobilizing regimen requires the use of both chemotherapy and hematopoietic growth factors: the efficiency of mobilization was grea ter and with less side effects than chemotherapy alone. It was postula ted that PBPC mobilization could be achieved only at hematopoietic rec overy following myeloablative chemotherapy, Recently, it has been demo nstrated that some standard-dose chemotherapy regimens associated with hematopoietic growth factors are efficient priming agents. We reporte d that standard-dose CEF chemotherapy plus filgrastim is a disease spe cific regimen (breast cancer) allowing PBPC mobilization without any r elevant toxicity. The maximum release of PBPC has been observed at day 11. The optimal time for PBPC collection is predictable and aphereses can be guided by WBC counts. In conclusion, both standard and high do se chemotherapy are effective priming regimens. So presently a mobiliz ing regimen should be an effective disease specific chemotherapy progr am and should contain a hematopoietic growth factor. The choice betwee n standard and high-dose chemotherapy can be based on patients charact eristic and disease status.