Is acute promyelocytic leukemia a curable disease? Treatment strategy for a long-term survival.

The major cause of early death in acute promyelocytic leukemia (APL), the high risk of a bleeding diathesis is now successfully counteracted within a few days by differentiation therapy using ATRA. Moreover, no resistance to this drug has been recorded during induction when the usual presence of PML/RAR alpha was confirmed by molecular study (some M3 cases do lack rearrangement of PML/RAR alpha). Paradoxically, a hypercoagulable clotting tendency may occur in these patients during the first month of ATRA treatment. Leucocyte activation (retinoic acid syndrome), often secondary to hyperleukocytosis, is prevented by early addition of chemotherapy when WBCs exceed defined limits, and is successfully treated by high dose corticosteroids. Routine acquired progressive in vivo resistance to all trans retinoic acid (ATRA) requires consolidation of ATRA-induced complete remission (CR) with intensive chemotherapy. Prevention of relapses using maintenance therapy is questionable and has not been tested in randomized trials. Actually the event-free survival of APL patients treated by the combination of ATRA and chemotherapy is 80% at 1 year, and the cure of 50% of patients is within our reach.