Monitoring by quantitative rt-pcr of ph+ cell mobilization induced by granulocyte colonystimulating factor (g-csf) in chronic myeloid leukemia

Autologous stem cell transplantation (ASCT) is a potential eradicative approach for treatment of Ph+ chronic myeloid leukemia (Ph+ CML). Methods to obtain Ph- autografts may include the harvest of Ph- stem cell either at time of diagnosis or after in vitro or in vivo purging. We report here on 5 cases of Ph+ CML in whom: i) a complete and stable cytogenetic response was obtained with IFN-a, ii) hemopoietic progenitors were collected from the peripheral blood after administration of granulocyte colony stimulating factor (G-CSF), and iii) minimal residual disease was tested by means of a quantitative reverse transcriptase polymerase cell reaction (RT-PCR). G-CSF was administered at a dose of 16 ug/kg/day (s.c.) after discontinuation of IFN-a therapy. Stem cell harvest was performed daily, from day 5 of G-CSF therapy through standard blood volume aphérèses using a Cobe Spectra blood separator. By means 3 to 4 aphérèses a median of 1.37 x 106/kg CD34+ ceils was collected (range 0.34-3.0). In all of the patients the number of bcr/abl transcripits /|i RNA in the first apheresis product was from 10 to 7(30 fold higher than the number of bcr/abl transcripits of the preapheresesis bone marrow. However, the Ph+ cell contamination significantly decreased between the the first and last apheresis. In the last apharesis the number of bcr/abl transcripts was comparable to the one of the pre-apheresesis bone marrow. These results show that in the Ph+ CML patients who are chronically treated with IFN-a and have a complete and stable cytogenetic it is possible to collect hemopoietic progenitors that are low contamineted by Ph+ cells.