P-GLYCOPROTEIN EXPRESSION AND PROGNOSTIC VALUE IN ACUTE MYELOID-LEUKEMIA

Background and Objective. Drug resistance has become a major cause of treatment failure in patients with acute leukemia. P-glycoprotein (Pgp ), which is associated with the multidrug resistance (MDR) phenotype, has been reported to be an important predictor of treatment outcome. T he aim of this study was to analyze the value of Pgp expression in bon e marrow or peripheral blood as a predictor of the response to remissi on induction chemotherapy as well as the duration of remission in pati ents with de novo acute myeloid leukemia (AML). Design and Methods. We examined the expression of Pgp in 82 patients with de novo AML using an immunocytochemical assay with the C219 monoclonal antibody. Results . Twenty-seven of the 82 patients (33%) were C219-positive in from 1% to 100% of their cells. Thirteen cases (16%) showed a positive reactio n in more than 50% of the leukemic cells. Only hyperleukocytosis was s ignificantly associated with higher expression of Pgp. Although 8 of t he 13 cases (62%) with more than 50% of cells having Pgp expression we re CD34-positive, this association was not statistically significant. A univariate analysis of resistance to induction therapy showed a sign ificantly higher resistance rate in patients with increased Pgp expres sion (P=0.01) as well as in those patients with decreased reactivity t o myeloperoxidase. The multivariate analysis revealed the independent prognostic value of Pgp expression. C219 reactivity did not have an in fluence on remission duration. Interpretation and Conclusions. Our dat a indicate that P-glycoprotein expression is a reliable marker of resi stance to Induction treatment in patients with de novo AML. (C)1998, F errata Storti foundation.