Molecular follow-up of patients with promyelocytic leukaemia treated with all-trans retinoic acid

Six consecutive patients with promyelocytic leukaemia displaying the PML/RAR‐α fusion messenger ribonucleic acid (mRNA) – the molecular marker of the disease – were prospectively treated with all‐trans retinoic acid: Haematological complete remission was achieved in all of them. However, in three of them the PML/RAR‐α mRNA persisted. Subsequent treatment with ablative chemotherapy rendered the molecular remission in all cases. Two of the patients that did not achieve the molecular remission with ATRA were autografted with peripheral blood stem cells after clearing the PML/RAR‐α fusion mRNA. One patient with tretinoin‐induced molecular remission relapsed two years after diagnosis and died; the remaining five survive in complete haematological and molecular remission for periods ranging from 405 to 1695 days. Additional studies are needed to clarify the significance of the molecular follow‐up of patients with PML.