A comparison of toxicity following two different doses of cyclophosphamidefor mobilization of peripheral blood progenitor cells in 116 multiple myeloma patients

High-dose cyclophosphamide (HDC) has been shown to be an effective regimen for collecting PBPC in multiple myeloma (MM) patients, but the optimal dose to be used remains controversial. Two historical cohorts of MM patients wh o received G- or GM-CSF and HDC at the dose of either 7 g/m(2) (HDC7, n = 7 4) or 4 g/m (HDC4 n = 42) were compared, As patients in the HDC4 group were more likely to have received G-CSF than GM-CSF (P < 10(-3)) and fewer prev ious alkylating agents (P = 0.004), multivariate logistic regression analys is was performed. In the HDC4 group, patients had a shorter median duration of neutropenia (P < 10(-4)), fewer RBC (P < 10(-3)) and platelet transfusi ons (P < 10(-3)) with fewer patients with platelets <20 x 10(9)/1 (P = 0.00 4). Moreover, fewer febrile episodes (P < 10(-3)) and less need of intraven ous antibiotics (P < 10(-3)) were found in the HDC4 group, No statistical d ifference was observed with regard to CD34(+) cell collection efficiency. T hus, the use of HDC at the dose of 4 g/m(2) for the collection of PBPC in M M patients decreases hematological and extrahematological toxicity with an equivalent CD34(+) cell collection efficiency.