Detection of minimal residual disease in acute promyelocytic leukemia by polymerase chain reaction assay for PML/RARalpha (retinoic acid receptor-alpha) fusion transcript

Seven patients with acute promyelocytic leukemia (APL)treated with all-trans retinoic acid (ATRA) for remission (CR) induction and with chemotherapy (CT) for consolidation of CR underwent residual disease monitoring through reverse transcription polymerase chain reaction (PCR) for PML/retinoic acid receptor alpha (PML/RAR alpha) fusion transcript. In six patients PCR was positive immediately after ATRA induced CR and/or after the first CT course.Two patients became PCR negative following repeated courses of CT and they are in remission 7 and 14 months, respectively. Four other patients relapsed. This pilot study indicates that PCR for PML/RAR alpha is very sensitive assay for detection of residual disease in APL.