Acute Promyelocytic Leukemia
Acute promyelocytic leukemia (APL) is a relatively rare subtype of acute myeloid leukemia (AML), although the exact incidence statistics are unknown. In APL, there is an abnormal accumulation of promyelocytes, an immature form of granulocytes. APL is characterized by a specific chromosomal translocation of the retinoic acid receptor alpha (RARA) gene. Interestingly, the age association of APL differs markedly from other types of AML, where the risk of developing the disease increases with age. APL is uncommon in children, with incidence increasing during the teenage years, reaching a plateau from early adulthood, and then declining after the age of 60.
APL is a key example of the effectiveness of modern molecularly targeted therapy. Previously a highly fatal condition, the majority of APL can now be cured with all-trans retinoic acid (ATRA) and arsenic trioxide (ATO).
Challenges remaining in APL include improving the early identification and treatment of patients, developing strategies for high-risk patients, and examining maintenance therapies in low-risk patients.