MOBILIZATION OF PHILADELPHIA-NEGATIVE PERIPHERAL-BLOOD PROGENITOR CELLS WITH CHEMOTHERAPY AND RHUG-CSF IN CHRONIC MYELOGENOUS LEUKEMIA PATIENTS WITH A POOR RESPONSE TO INTERFERON-ALPHA

The purpose of this cooperative study was to evaluate the quantity and quality of Phl-negative progenitor cells mobilized in the peripheral blood of patients with chronic myelogenous leukaemia soon after aplasi a induced by chemotherapy, 32 patients ineligible for allografting who were cytogenetically refractory to interferon-alpha (IFN-alpha) were entered into this study. The chronic phase varied widely, with a media n duration of 17 months (range 3-90 months). All patients were treated with intensive conventional chemotherapy regimens and recombinant hum an granulocyte colony-stimulating factor (rhuG-CSF, lenograstim). Peri pheral blood progenitor cells (PBPC) were harvested by leukaphereses d uring early recovery from chemotherapy-induced aplasia. A total of 119 leukaphereses were performed. Median numbers of CD34(+) cells and CFU -GM collected were 2.04 x 10(6)/kg and 2.9 x 10(4)/kg, respectively. T here was a significant co;relation between white cell count and number of CD34(+) cells in the leukaphereses (P = 0.0001, r(2) = 0.41, n = 1 04). A strict correlation between the number of CD34(+) cells and CFU- GM in the leukapheretic product (P = 0.0001, r(2) = 0.39. n = 110) was observed, 21% of evaluable patients (6/29) achieved a complete cytoge netic remission in the leukapheretic product and the other four patien ts achieved a major cytogenetic response for an overall response of 35 % (10/22 patients). To date, 16 patients have been autografted and are alive. Five of them are Ph-1-negative (three patients) or partially P h-1-negative (two patients). In conclusion, despite the high-risk char acteristics of this study population, Ph-1-negative PBPC were successf ully mobilized in more than one-quarter of patients using a chemothera py plus rhuG-CSF regimen. The importance of this achievement is increa sed by the current lack of other practical methods of rescuing Ph-1-ne gative cells in such patients.