Cytogenetic response to autografting in chronic myelogenous leukemia correlates with the amount of BCR-ABL positive cells in the graft (vol 28, pg 104, 2000)

Objective. An important step in successful autografting of patients with ch ronic myelogenous leukemia is the delivery of a leukemia-free graft. We con ducted this study to determine whether the cytogenetic response after autog rafting was correlated with the number of BCR ABL-positive cells present wi thin the stem cell grafts. Materials and Methods. By BCR-ABL mRNA quantification, we studied the seria l pheresis products from 10 Philadelphia (Ph)-positive patients who receive d ICE/mini-ICE mobilization therapy and underwent autologous stem cell tran splantation. We correlated the residual disease within the graft reinfused with the cytogenetic response following transplantation, taking into consid eration those responses that lasted 12 months or more. Results. Thirty-two patients received a graft with 0-35% Ph-metaphases and 19 received a graft with BCR-ABL/ABL ratio less than or equal to 0.01. Afte r a median of 27 months (range, 12-50) from transplant, 18 patients achieve d complete or major cytogenetic response lasting at least 12 months, and 14 of them (78%) received a graft with BCR-ABL/ABL ratio less than or equal t o 0.01 (range, 0.0003-0.01). Twenty-two patients experienced short-lived re sponses or had >35% Ph-positive cells in the marrow after transplant, but o nly 5 of them (23%) had a graft with BCR-ABL/ABL ratio less than or equal t o 0.01 (range, 0.001-0.01). Therefore, we found a strong association betwee n a BCR-ABL/ABL ratio less than or equal to 0.01 and the achievement of com plete or major cytogenetic remission after autografting (chi(2) test, p = 0 .0001). Patients reinfused with grafts contaminated at low levels with leuk emic cells also showed a longer duration of the response (log-rank test, p = 0.0009). Eleven patients were reinfused with the lowest level of contamin ated stem cell collections, according to the BCR-ABL/ABL ratio. None of the se patients experienced prolonged neutropenia or thrombocytopenia following stem cell reinfusion and nine of them had longlasting complete or major cy togenetic responses after transplant. Conclusion. This study demonstrates that the number of BCR-ABL positive cel ls present in a stem cell graft is an important predictive factor for the a chievement and the duration of cytogenetic response after autografting. (C) 2000 International Society for Experimental Hematology. Published by Elsev ier Science Inc.