What is the primary treatment for acute promyelocytic leukemia (M3)?

The primary treatment for acute promyelocytic leukemia (APML or M3) is all-trans retinoic acid (ATRA). APML is characterized by a specific genetic alteration involving the promyelocytic leukemia (PML) gene and the retinoic acid receptor α (RARA) gene, resulting in the formation of a promyelocytic leukemia gene (PML-RARA) fusion protein. This fusion protein interferes with normal myeloid differentiation and leads to the accumulation of promyelocytes in the bone marrow and peripheral blood.

All-trans retinoic acid plays a crucial role in reversing the differentiation block caused by the PML-RARA fusion. ATRA induces the maturation of these abnormal promyelocytes into more mature granulocytes, facilitating their normal development and apoptosis. This differentiation therapy is particularly effective in managing APML and can lead to remission, particularly when combined with arsenic trioxide in some treatment protocols.

While chemotherapy, bone marrow transplant, and immunotherapy are relevant treatment modalities for other types of leukemia or certain cases of APML, they are not the primary therapy for the initial treatment of acute promyelocytic leukemia. The success of ATRA has significantly improved outcomes for patients with this specific subtype of leukemia