Monosomal karyotype in acute myeloid leukemia predicts adverse treatment outcome and associates with high functional multidrug resistance activity.

Monosomal karyotype (MK) reflects highly unfavorable prognosis in patients with acute myeloid leukemia (AML). This study aimed to study the association of AML-MK with multidrug resistance (MDR) functional activity. A total of 369 AML patients (excluding APL) between 1995 and 2008 at a single center were included retrospectively. Functional MDR activity was evaluated with rhodamine-123 efflux activity with/without verapamil inhibition. MK was noted in 23 patients, only among whom classified into unfavorable cytogenetic risk group. Unfavorable cytogenetic subgroup with MK showed shorter OS (8.7 ± 5.9% vs. 23.5 ± 7.5% at 3 years, P = 0.030), EFS (8.7 ± 5.9% vs. 19.0 ± 6.9% at 3 years, P = 0.029), and a lower CR rate (34.8% vs. 65.7%, P = 0.031) compared with unfavorable subgroup without MK. Functional MDR activity was significantly higher in the unfavorable cytogenetic group with MK compared to all other cytogenetic risk groups taken as a whole (P = 0.026) and showed a trend toward statistical significance when compared with the unfavorable cytogenetic risk group without MK (P = 0.06). AML patients harboring MK showed a poor outcome in terms of lower CR rate and worse EFS/OS, and the presence of MK appeared to be associated with higher MDR functional activity of leukemic blasts.