DIFFICULTIES IN COLLECTING PERIPHERAL-BLOOD STEM-CELLS IN CHRONIC MYELOID-LEUKEMIA RELATED TO PERSISTENCE OF THE LEUKEMIC-CELL CLONE

Eight chronic myeloid leukemia (CML) patients ineligible for allogenei c bone marrow transplantation (BMT) were intensively treated by a myel oablative chemotherapy identical to the treatment that we use in acute myeloid leukemia (AML). The objectives of such an intensive treatment were both to reduce the size of the leukemia stem cell mass as much a s possible and subsequently to allow a better mobilization of the resi dual Ph-negative (Ph-) stem cells. Cytogenetic analyses were systemati cally performed on blood-derived stem cells collected at the hematopoi etic recovery phase following post-chemotherapy aplasia. The length of aplasia did not correlate with the evolutive stage of the disease, bu t was negatively correlated with the total colony forming units-granul ocyte macrophage (CFU-GM) amounts collected. The cytogenetic abnormali ty remained present in most cases in all metaphases counted in leukaph eresis products. Three patients were transplanted with these leukapher esis products. One died due to sepsis before engraftment; the two othe rs engrafted very slowly, while Ph-positive (Ph+) cells were found at post-transplant controls. These disappointing results suggest that the myeloablative chemotherapy used in this study has not resulted in sat isfactory advantages for the proliferation of residual normal stem cel ls over the expansion of the Ph+ clone.