OUTCOME OF PERIPHERAL-BLOOD STEM-CELL MOBILIZATION IN ADVANCED PHASESOF CML IS DEPENDENT ON THE TYPE OF CHEMOTHERAPY APPLIED

High-dose chemotherapy with autologous transplantation of in vivo purg ed PBSC is a novel investigational approach to treating chronic myelog enous leukemia (CML) patients not responsive to conventional therapy w ith interferon-alpha (IFN-alpha) and not eligible for allogeneic trans plantation. PBSC mobilization using either '5 + 2/7 + 3'-type chemothe rapy or 'mini-ICE/ICE' chemotherapy was investigated in 43 patients wi th advanced phases of Philadelphia (Ph)-positive CML. Thirty patients were in late chronic phase (> 12 months post diagnosis) and 13 patient s in accelerated phase (AP) or blast crisis (BC). Contamination with P h-positive cells was evaluated in harvests from 37/43 patients. The ou tcome of PBSC mobilization was dependent on the type of chemotherapy a dministered: a complete or major cytogenetic response (< 35% Ph-positi ve metaphases) in leukapheresis collections was obtained in ten of 15 patients treated with 'mini-ICE/ICE' but in only three of 28 patients treated with '5 + 2/7 + 3' chemotherapy. One patient (1/43) in blast c risis died during mobilization therapy (2%). Twenty-five patients unde rwent PBSC transplantation and all of them engrafted successfully. Tra nsplantation-related mortality was 0%. The data show that in advanced phases of CML the chance of harvesting Ph-negative peripheral blood st em cells depends on the type of chemotherapy used for mobilization.