A Comprehensive Review of Acute Promyelocytic Leukemia in Children

The outcome of patients with acute promyelocytic leukemia (APL) has substantially improved since the successful introduction of tretinoin, and nowadays combining tretinoin with chemotherapy is potentially curative for at least 70-75% of patients with newly diagnosed APL. In most pediatric series, APL represents < or = 10% of childhood acute myelogenous leukemia. APL in children is more common in girls and in obese children. It is characterized by a higher incidence of hyperleukocytosis, an increased incidence of microgranular morphology and by more frequent occurrence of the PML/RARalpha isoforms bcr 2 and bcr 3 compared to adults. Tretinoin-based therapy is curative for the majority of children with APL. Recent data indicate that > or = 2 negative RT-PCR assays for PML/RARalpha on bone marrow performed at least 1 month apart after completing therapy are strongly associated with long-term remissions, while conversion to PCR positivity for PML/RARalpha during remission is highly predictive of impending relapse. Data from recent studies in adults and limited data from children show that arsenic trioxide is the single most effective agent in APL and deserves immediate study in newly diagnosed children in an effort to further improve prognosis and to limit exposure to conventional cytotoxic chemotherapy.