SERIAL QUANTIFICATION OF MINIMAL RESIDUAL DISEASE OF T(8-21) ACUTE MYELOGENOUS LEUKEMIA WITH RT-COMPETITIVE PCR ASSAY

The chromosomal translocation (8;21)(q22;q22) in the AML M2 subtype ac cording to the FAB classification, results in the production of a nove l fusion gene AML1/ETO. The chimaeric AML1/ETO transcript is useful fo r the detection of minimal residual disease (MRD). Recently, several s tudies on the detection of AML1/ETO transcripts in t(8;21) AML have be en reported. However, the clinical significance of a small number of A ML1/ETO transcripts by a reverse transcription-polymerase chain reacti on (RT-PCR) remains to be elucidated. We have developed a novel quanti tative RT-competitive PCR assay and evaluated the clinical usefulness of this method by the monitoring of MRD in eight patients with t(8;21) AML. In four patients in first continuous complete remission (CR) the value of MRD was always <0.1 fg of the competitor dose throughout the ir courses, whereas in four relapsed patients there was an increase in the value of MRD to > 0.1 fg of the competitor dose before cytogeneti c relapse. We conclude that the detection of the presence of cells wit h AML1/ETO fusion transcripts by our RT-competitive PCR assay may be u seful to monitor disease progression and to predict subsequent relapse .