ADULT BIPHENOTYPIC ACUTE-LEUKEMIA - AN ENTITY WITH POOR-PROGNOSIS WHICH IS RELATED TO UNFAVORABLE CYTOGENETICS AND P-GLYCOPROTEIN OVER-EXPRESSION

Biphenotypic acute leukaemia (BAL) patients represented 8% of the 287 de novo consecutive adult acute leukaemias (23 BAL, 230 acute myeloid leukaemia (AML) and 34 acute lymphoblastic leukaemia (ALL)) referred t o our department during the last 4-year period. Of these 23 BAL patien ts, 14 patients showed myeloid morphology and nine cases lymphoid morp hology according to FAB criteria. There were no differences between ly mphoid and myeloid BAL according to clinical and biological presentati on and treatment outcome. We confirm the poor prognosis of BAL when co mpared to AML or ALL seen during the same period of time, in terms of complete remission (47%, 62% and 82% respectively, BAL v AML, NS and B AL v ALL, P=0.006) and 4-year overall survival (8.1%, 25.8% and 23.8% respectively. BAL v AML, P=0.05 and BAL v ALL, P=0.003). Comparing adu lt BAL patients with AML patients, we found an increase in poor progno stic factors: CD34(+) phenotype (82% v 60% respectively, P=0.03), unfa vourable karyotype (60% v 20%, P<0.0001) and Pgp over-expression by RT -PCR (0.705 v 0.107, P<0.0001) and flow cytometry (0.824 v 0.391, P=0. 0001), MRP and LRP were not found to be poor prognostic factors. Compa ring BAL patients with ALL patients, we found also an increase in poor prognostic factors: age (51 v 39, P=0.003) and CD34(+) phenotype (82% v 50%, P=0.02). We conclude that BAL patients need a more aggressive treatment procedure, including high-dose AraC or the use of Pgp modula tors for first-line therapy.