COLLECTION OF CIRCULATING PROGENITOR CELLS AFTER EPIRUBICIN, PACLITAXEL AND FILGRASTIM IN PATIENTS WITH METASTATIC BREAST-CANCER

The efficacy of high-dose chemotherapy (HDC) and circulating progenito r cell (CPC) transplantation in metastatic breast cancer (MBC) relies mainly on giving this treatment after a response to conventional induc tion chemotherapy has been achieved, For this reason an optimal mobili zation regimen should be therapeutically effective while minimizing th e number of leucaphereses required to support the myeloablative therap y. The combination of an anthracycline and paclitaxel in chemotherapy- untreated MBC has produced impressive response rates. We evaluated the CPC-mobilizing capacity of the combination epirubicin (90 mg m(-2)) a cid paclitaxel (135 mg m(-2)) followed by filgrastim (5 mu g kg(-1) da y(-1)) starting 48 h after chemotherapy administration in ten patients with MBC who were eligible for an HDC and CPC transplantation program me. Leucaphereses were performed by processing at least two blood volu mes per procedure at recovery from neutrophil nadir when CD34(+) cells in the peripheral blood exceeded 20 mu l(-1). In most patients (six o ut of 10) more than 2.5 x 10(6) CD34(+) cells kg(-1), a threshold cons idered to be sufficient for haematopoietic reconstitution, were collec ted with a single apheresis. In the remaining four patients an additio nal procedure, performed the following day, was enough to reach the re quired number of progenitors. These data suggest that the epirubicin-p aclitaxel combination, besides being a very active regimen in MBC, is effective in releasing large amounts of progenitor cells into circulat ion.