Chronic Myeloid Leukemia Developing After Successful Treatment of Acute Promyelocytic Leukemia

Acute promyelocytic leukemia (APL) has been regarded as a highly curable disease. Therapy-related leukemia is one of the important late complications that affect long-term survival rates in APL patients. Therapy-related acute myeloid leukemia and myelodysplastic syndrome are the major forms of therapy-related leukemias. We report a rare event of chronic myeloid leukemia (CML) that developed after successful treatment of APL with all-trans-retinoic acid in combination with chemotherapy. Rather unexpectedly, CML developed 7 years after APL. Cytogenetic and molecular studies proved the independence of these two entities. It was found that CML progressed rapidly after a short-term response to a combination therapy with hydroxyurea, interferon-α and arsenic trioxide. We propose that optimization of chemotherapy regimen and treatment intensity may reduce the risk of developing a secondary leukemia, while long-term monitoring cytogenetics of APL patients after treatment may help determine the development of a secondary leukemia at early stage.