Conditions influencing the expansion of the circulating hemopoietic progenitor cell compartment

Eighteen patients (6 breast cancer, 10 non-Hodgkin's lymphoma, 2 Hodgkin's disease) were treated with high-dose cyclophosphamide (7 gr/mq), while 12 (2 breast cancer, 5 non-Hodgkin's lymphoma, 5 multiple myeloma) were additionally treated with rhGM-CSF for 14 days after cyclophosphamide. During recovery, increased peak values of circulating CFU-GM were observed in 23 out of 30 patients (13 patients after cyclophosphamide, median: 5,000 CFU-GM/ml; 10 patients after cyclophosphamide + rhGM-CSF, median: 20,150 CFU-GM/ml); five of these "high releaser patients" were in 1st relapse after MACOP-B. Seven patients showed low release of CFU-GM; they had either a history of multiple exposures to chemoradiotherapeutic treatments or bone marrow replacement by neoplastic cells or both. Four out of 23 patients with high CFU-GM release were subsequently studied after administration of high-dose etoposide (2 gr/mq): increased levels of circulating progenitors were seen again, although peak values were reduced when compared to post-cyclophosphamide period. Three patients with low release and bone marrow involvement had a clear increase of circulating CFU-GM after etoposide. The results show the influence of high-dose chemotherapy, rhGM-CSF, type of previous treatment and bone marrow involvement on the degree of circulating CFU-GM release.