Despite his long life, he died shortly before one last dogma was about to be demolished. those that have had more direct an impact in patient end result. Finally, we briefly discuss some of the unsolved issues and future difficulties in APL biology and treatment. The 1st statement on APL Liquiritigenin traces back to 1957, when the Norwegian hematologist LK Hillestad identified APL as a distinct medical entity, whose the majority of exceptional feature was its very rapidly downhill course of few weeks duration, a white blood cell picture dominated by promyelocytes and severe bleeding Liquiritigenin caused primarily by fibrinolysis.1A more detailed account of APL was given in 1959 by J Bernard (Hpital St. Louis, Paris) who reported a series of 20 individuals with the full definition of the disease and its association with promyelocytic proliferation, hyper-acute onset and catastrophic hemorrhagic events.2 Since the earlier reports, the life-threatening coagulopathy was recognized as the defining clinical feature of APL accounting for the majority of deaths at demonstration and during initial cytotoxic treatment, with most fatal events becoming intracranial and pulmonary hemorrhages. The hemostatic abnormalities were attributed to a Liquiritigenin disseminated intravascular coagulopathy in which fibrinolysis and procoagulant activity brought on by APL blasts played a major part. As explained by Randet al, hematologic remission resulted in the resolution of the coagulopathy.3It is worth noting that, despite the impressive improvement in end result achieved after the arrival ofAll-trans retinoic acid (ATRA, see below) the early death rate in APL has remained elevated even in recent years, mostly because many individuals die actually before they can start treatment.4,5,6This further highlights the importance of early recognition of the disease in order to promptly start anti-leukemic therapy and simultaneous transfusion support. A seminal contribution in APL treatment was made in the early 70s, again by J Bernard and co-workers, who reported a dramatic raise in full remission (CR) rates from 13% to 57% when using daunorubicin as monochemotherapy.7Following this landmark study, anthracycline-based regimens were used in Italy, Spain and France during the 70s and 80s. APL was indeed recognized as a distinct entity in these countries long before the arrival of ATRA and differentiation therapy, whereas in all other countries, including the USA, the disease was treated like the rest of AMLs until the early 90s, that is, without any specific distinction. Still nowadays, while novel experimental treatments are being tested Liquiritigenin and other providers have been shown to have UCHL2 high anti-leukemic activity in APL (e.g. arsenic trioxide, anti-CD33 antibodies), the standard recommended treatment for newly diagnosed APL consists of anthracycline monochemotherapy and ATRA.8,9No additional myeloid or lymphoid acute leukemia shows a similar pattern of chemosensitivity to a single agent, and, in fact, polychemotherapy schemes are the standard treatment in all non-APL acute leukemias. The biological reasons underlying such striking level Liquiritigenin of sensitivity of APL to anthracycline have not been clarified and should be a matter of investigation. Avvisatiet al. reported in 1990 similarly high CR rates using idarubicin instead of daunorubicin.10 The French-American-British classification of 1976 clearly recognized APL (M3 type) and its peculiar morphologic features: these included marrow infiltration by dysplastic promyelocytes with heavy granulations and sometimes bundles of Auer rods (“faggots”) accompanied by a strong myeloperoxidase (MPO) staining in the cytoplasm.11Few years later on, a microgranular variant (M3v) of the disease was recognized and identified in the updated FAB classification.12This variant accounts for 20% of cases approximately. Subsequent biologic studies showed that compared to the more common hypergranular form, the M3v subtype carries identical molecular features, while phenotypically it is characterized by more frequent hyperleucocytosis and manifestation of CD2.13Importantly, the variant form is equally responsive to anthracyclines, ATRA and arsenic trioxide (ATO), indicating that molecular identity corresponds to equal drug sensitivity in the two forms. In the biological level, a major breakthrough in APL was the description by J Rowley from your University of Chicago of a reciprocal balanced translocation between chromosomes 15 and 17 t(15:17) (q21;q22).14Subsequent studies showed that this translocation occurs in approximately 95% of APL cases and is unique to the disease. Karyotypic studies were pivotal to determine APL as.