Quantitative evaluation of BCR-ABL amount of transcript post mobilization with G-CSF of peripheral blood stem cells from chronic myeloid leukemia patients in cytogenetic response

We studied nine patients affected by chronic myeloid leukemia (CML Ph+ and bcr-abl positive) and treated with alpha-interferon (alpha-INF) in order to : first, to evaluate the feasibility of a mobilization of peripheral blood stem cells induced by granulocyte-colony-stimulating factor (G-CSF) and the contamination by Ph+ cells and second, to quantify the amount of bcr-abl l eukemia associated transcript by a quantitative assay during mobilization p rocedures, and post mobilization follow-up. Eight achieved a complete karyo typic remission before mobilization obtained with discontinuation of alpha- INF for few days and G-CSF at a dosage of 15 mu g/kg/day for 5-7 consecutiv e days. By quantitative-competitive polymerase chain reaction (QC-PCR) assa y, all the leukaphereses and bone marrow samples during post mobilization f ollow up were studied to determine the amount of bcr-abl transcript, Karyot ypic and molecular analysis on evaluable leukapheresis showed that all the harvests were Ph negative and bcr-abl positive: in seven cases the levels o f bcr-abl transcript were higher or equal to the pre-apheresis status. In t hree out of four patients, who underwent more than one leukapheresis proced ure, we noticed a decreasing amount of bcr-abl contamination from the first to the last apheresis. Our results suggest that in patients who achieved a complete or major cytog enetic conversion with alpha-INF, it is possible to obtain a sufficient amo unt of PBSC for autografting by leukapheresis following priming G-CSF thera py and that the amount of neoplastic transcript does not seem to increase.