Aneuploidy as a marker of minimal residual disease in leukemia

Aneuploidy as an indication of abnormal cellular DNA content has recently been confirmed to be a reliable marker of malignant cells in human solid tumors and hematologic malignancies. Flow cytometry (FCM), measuring cellular DNA content in thousands of cells within seconds, is able to safely detect the "rare event cell," the rare aneuploid cell in a diploid cell population. This very fast and sensitive technique was combined with a newly developed cell separation technique. Cell separation prior to FCM enabled us to detect malignant cells at concentrations of 0.05% in blood, bone marrow, and lymph node cell suspensions of patients with leukemia. An illustration of this method is presented in conjunction with first clinical applications demonstrating that patients with minimal residual disease in clinically complete remission had significantly shorter survival times than patients in whom no minimal residual disease was detected with this new method.