Analysis of treatment failure in patients with minimally differentiated acute myeloid leukemia (AML-M0).

patients in whom an adequate number of mitoses could be evaluated. No single abnormality prevailed, the most common findings being trisomy 8 (three cases) and aberrations of chromosome 7 (two cases). Antileukemic treatment differed according to age, but for remission induction, all patients received a combination of cytosine arabinoside and an anthracycline ITH THE DEVELOPMENT of intensive induction chemotherapy and the substantial improvement of supportive care, complete remission (CR) rates of 50% to 80% have been achieved in adults with de novo acute myeloid leukemia (AML); approximately 25% of these appear to be cured.’,’ Attempts to improve these results were aimed at the identification of parameters that would predict different chances of survival and response to therapy, thus aiding in the choice for the most appropriate treatment for an individual patient. Age at diagnosis and a preceding myelodysplastic syndrome remain the most important pretreatment clinical factors, whereas among the biologic characteristics of the leukemic cell, the cytogenetic pattern appears to contribute the most prognostic information.’ Controversial results have been obtained concerning the predictive value of immunophenotyping and of the morphologic and cytochemical classification of the FrenchAmerican-British (FAB) group. Integrated classifications that consider information from various fields have led to a more precise reassessment of the leukemic syndromes and provided new prognostic insight^.^^' As a matter of fact, the recognition of new distinct entities has represented the main result of these classifications. Minimally differentiated AML (AML-MO) is a recently established subtype of acute leukemia whose diagnosis cannot be made on morphologic grounds alone and always requires the confirmation by immunologic and/or ultrastructural method^.',^ The clinical features and outcome of patients with this form of leukemia have remained largely controversial because of the lack of studies including an adequate sample size as well as a&quate follow-up information. In an attempt to further individualize treatment strategies, we examined the therapeutic results of I5 AML-MO patients, and focused on the causes of treatment failure. W