Cytogenetic response to autografting in chronic myelogenous leukemia correlates with the amount of BCR-ABL positive cells in the graft

Objective. An objective of autologous transplant in chronic myelogenous leu kemia is to reinfuse the patient stem cells with the lowest amount of Leuke mic progenitors. We analyzed if the cytogenetic response after autografting was correlated with the amount of BCR ABL-positive cells present in the gr aft. Materials and Methods. By BCR-ABL mRNA quantification, we studied the seria l pheresis product from 40 Philadelphia (Ph)-positive patients who received ICE/mini-ICE mobilization therapy and underwent autologous stem cell trans plant in our unit, Therefore, we correlated the residual disease in the gra ft reinfused to the patients with the cytogenetic response after autografti ng, taking into consideration only those responses that lasted 12 months or more. Results. Thirty-two patients had a graft with 0-35% Ph-metaphases and 19 ha d a craft with BCR-ABL/ABL ratio less than or equal to 0.01. After a median of 27 months (range, 12-50) from transplant, 18 patients achieved complete or major cytogenetic response lasting at least 12 months and 14 of them (7 8%) had a graft with BCR-ABL/ABL ratio less than or equal to 0.01 (range, 0 .0003-0.01), Twenty-two patients had short-lived response or showed to be > 35% Ph-positive in the marrow after transplant, but only 5 of them (23%) ha d a graft with BCR-ABL/ABL ratio less than or equal to 0.01 (range, 0.001-0 .01). Therefore, we found a strong association between BCR-ABL/ABL ratio le ss than or equal to 0.01 in the reinfused progenitor collections and the ac hievement of complete or major cytogenetic remission after autografting (ch i(2) test, p = 0.0001), Patients reinfused with low contaminated grafts als o showed a longer duration of the response (logrank test, P = 0.0009). Elev en patients were reinfused with the lowest-contaminated stem cell collectio ns, according to the BCR-ABL/ABL ratio. None of these patients had prolonge d neutropenia or thrombocytopenia following stem cell reinfusion and 9 of t hem had long-lasting complete or major cytogenetic response after transplan t. Conclusion. This study demonstrates that the amount of BCR-ABL positive cel ls present in the graft is an important predictive factor for the achieveme nt and the duration of cytogenetic response after autografting. (C) 2000 in ternational Society for Experimental Hematology. Published by Elsevier Scie nce Inc.