Platelet production and related pathophysiology in acute myelogenous leukemia at first diagnosis: prognostic implications.

Among various laboratory and clinical features megakaryocytopoiesis and platelet (PLT) counts have been previously insufficiently evaluated for their prognostic significance in acute myelogenous leukaemia (AML). We studied several clinical and laboratory features of 108 first diagnosed AML patients in relation with their prognosis. Patients with favourable prognostic features were excluded from the study. This study focused on the prognostic impact of PLT counts and related molecular biology in AML patients at initial diagnosis. In particular, the PLT counts were correlated with the endogenous production of thrombopoietin (TPO), c-mpl expression, CD34+ leukemic blast cell proportion, cytogenetics, and a prognostic correlation was established. We found that the most favorable prognosis appeared in the AML patient group with PLTs <25x10(9)/l and correlated to cytogenetic findings (normal or abnormal karyotypes), while by far the most unfavorable prognosis was found in the patient group with PLTs > or =130x10(9)/l independent of the corresponding cytogenetics. It was demonstrated that AML patients with normal or elevated PLT counts at first presentation, may constitute a distinct patient group with particular characteristics such as higher levels of endogenous TPO production, high expression of CD34+ leukemic blast cells, higher expression of c-mpl and consequently low response to chemotherapy and a very poor prognosis. These correlations between PLTs production (megakaryothrombopoiesis), TPO serum levels and TPO receptor (c-mpl) expression may help in the determination of risk-adapted AML patient groups and of targeted therapeutic strategies.