Superior results on detection of minimal residual disease(MRD) in acute myelogenous leukemia by hypermetaphase-fluorescence in situ hybrhization(fish)

Abstract

Recently, we have proved the usefulness of hypermetaphase-FISH(HMF) to detect Ph clones after allo-BMT in CML(Seong et al, J Clin Oncol 2000;18(9):1831-1836). Meanwhile, non-random acquired chromosome abnormalities are probably present in all patients with AML. In the present study, we evaluated whether HMF is useful to detect the known cytogenetic abnormalities during therapy or in complete remission in AML. A technique("Hypermetaphase") to achieve maximum metaphase collection, which involves 24 hours culture of bone marrow followed by addition of colcemid and culture for an additional 24 hours was used for FISH. Double blind experiments as well as non-blinded experiments were carried out on 56 treated AML patients, who have cytogenetic abnormalities included -5, -7, +8, t(8;21) and t(15;17). Thirteen normal individuals were also included in the study. The technique known as HMF detected minimal residual disease(MRD) in 21 out of 56 patients. Two important factors are the lack of false positives and the ability to analyze a relatively large number of cells in metaphase(i.e. 500), allowing a detection of <1% cells with a chromosome aberration. Alteration of the frequency of the abnormality can be detected with high confidence levels. We conclude that HMF is a sensitive and reliable method for monitoring MRD in AML patients during therapy or in complete remission. Using this data, we may be in position to design better strategies to eliminate residual leukemia cells before hematologic relapse.