What is the best treatment for acute promyelocytic leukemia?

The modern treatment of acute myelogenous leukemia (AML), consists of a polychemotherapeutic induction treatment followed by a post-remission therapy of variable intensity and duration and acute promyelocytic leukemia (APL) does not differ from this behavior. However, differently from the other AML subtypes, APL shows a high response rate to induction monochemotherapies with anthracycline drugs. This high response rate to anthracycline monochemotherapies is very peculiar of APL. Moreover, it has been suggested that maintenance treatment regimens incorporating the drugs Methotrexate and 6-Mercaptopurine, two drugs generally not utilized in the post-remission treatment of other AML subtypes, may be effective in prolonging the leukemia-free survival of APL. Furthermore, the results firstly obtained by a Chinese group in 1988 by using the vitamin A derivative all-trans retinoic acid (ATRA) have been successively confirmed by several other groups in the world. Therefore, at present the all-trans retinoic acid appears to be the best CR inducer in APL. However, these CRs are short lasting when maintained with ATRA alone and eventually all patients relapse. As a consequence, patients achieving CR with ATRA still require intensive post-remission chemotherapy to maintain the CR. As for bone marrow transplantation procedures, it is our opinion that they do not represent the treatment of choice of APL in first CR considering the very good results obtained with standard pharmacological approaches. In conclusion, only future randomized prospective trials will clarify which, among the several proposed therapeutic approaches, should be preferred in this very peculiar subtype of AML.