Validation of a New Flow Cytometry-Based Method to Discriminate Malignant From Normal Stem Cells In CML

Abstract Abstract 4474 Introdution: Previously, leukemic stem cells in Chronic Myelogenous Leukemia could only be identified indirectly by using culture techniques. Jeroen J.W et al have developed a new flow cytometric approach that allows a direct discrimination of CML stem cells from their normal counterparts within single patient samples. CD34+CD38- leukemic stem cells could be discriminated from normal stem cells by high CD90 expression, which is a specific feature of CML stem cells, while CD90 expression is low on their normal counterparts. Material: A total of 8 patients and 3 health controls were included in this study. Result: Health controls did not present CD90 molecular expression in stem cells. 100% of the patients presented different levels of CD90 in CD34+/CD38- cells. Our patients seemed to show an asociation between CD34+/CD38- stem cells which express CD90+ and bcr-abl levels. We have evolutive studies of 4 patients who are under treatment with imatinib; in those patients we apreciate decrease in the level of CD90 related to good response. Conclusion: Our results confirm Jeroen's data; we think that this new technique will expand our possibilities to identify CML stem cell specific targets and may improve efficacy assessment of CML treatment as well. Disclosures: García: Celgene: Research Funding.