Acute Promyelocytic Leukemia (APL)

Acute promyelocytic leukemia (APL) is an aggressive type of acute myeloid leukemia (AML). It happens when there are too many of the blood-forming cells called promyelocytes in the blood and bone marrow. A buildup of promyelocytes leads to a shortage of other kinds of blood cells, including red cells, white cells, and platelets.

APL usually occurs in middle-aged adults, but it can happen at any age.

Symptoms of APL

The symptoms of APL are due to the shortage of normal blood cells. They include fevers, fatigue, loss of appetite, and frequent infections. People with APL are also at an increased risk of bleeding and forming blood clots. This is because of the shortage of platelets in their blood and changes in the level of abnormal proteins in the blood.

Diagnosis of APL

APL happens because of a change in a person’s chromosomes. Chromosomes are inside all cells and carry our genes. In APL, the PML gene on chromosome 15 fuses with the RARA gene on chromosome 17. A defective protein forms as a result. Tests can detect this protein in the blood and bone marrow.

Learn more about diagnosing leukemia.

Treatment for Acute Promyelocytic Leukemia

APL is treated differently than other forms of AML. Many people with APL are first treated with a drug called all-trans-retinoic acid, also called tretinoin (Vesanoid®), which is given in combination with another drug called arsenic trioxide (Trisenox®). Both of these drugs were pioneered at Memorial Sloan Kettering. 

Learn more about treatment for APL.