MOLECULAR MONITORING OF MINIMAL RESIDUAL DISEASE IN ACUTE PROMYELOCYTIC LEUKEMIA BY THE POLYMERASE CHAIN-REACTION ASSAY FOR THE PML RAR-ALPHA (RETINOIC ACID RECEPTOR-ALPHA) FUSION TRANSCRIPT IN PATIENTS TREATED WITH ALL-TRANS-RETINOIC ACID FOLLOWED BY CHEMOTHERAPY/

Five acute promyelocytic leukemia (APL) patients who achieved a comple te remission (CR) with all-trans retinoic acid (ATRA) underwent residu al disease monitoring through reverse transcription polymerase chain r eaction (PCR) for PML/retinoic acid receptor-alpha (PML/RAR alpha) fus ion transcript. Ah received consolidation chemotherapy in CR, one in t he form of autologous bone marrow transplantation (ABMT). In four of t he patients PCR was positive for the PML/RAR alpha transcript immediat ely after ATRA treatment and/or after the first consolidation chemothe rapy course. In the patient treated with ABMT, positivity was still de tected six months after ABMT. One patient given five repeated courses of chemotherapy was PCR negative for PML/RAR alpha after 14 months in CR. Our pilot study confirmed that ATRA. is a highly efficient inducti on therapy for APL in various stages of the disease, but ATRA alone ca nnot cure the disease. PCR should be considered a fundamental assay fo r assessing minimal residual disease in CR that will influence further treatment strategies and permit evaluation of treatment results.