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 complete remission (CR) with all-trans retinoic acid (ATRA) underwent residual disease monitoring through reverse transcription polymerase chain reaction (PCR) for PML/retinoic acid receptor-alpha (PML/RAR alpha) fusion transcript. All received consolidation chemotherapy in CR, one in the form of autologous bone marrow transplantation (ABMT). In four of the patients PCR was positive for the PML/RAR alpha transcript immediately after ATRA treatment and/or after the first consolidation chemotherapy course. In the patient treated with ABMT, positivity was still detected 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 induction therapy for APL in various stages of the disease, but ATRA alone cannot cure the disease. PCR should be considered a fundamental assay for assessing minimal residual disease in CR that will influence further treatment strategies and permit evaluation of treatment results.