Low MDR1 and BAALC expression Identifies a New Subgroup of Adult Cytogenetically Normal Acute Myeloid Leukemia with a Favorable Outcome

Abstract

Abstract 4312 OBJECTIVE:Cytogenetically normal acute myeloid leukemia (AML) is a heterogeneous disease, in terms of genetic/molecular abnormalities resulting into marked differences in outcome. We demonstrated that MDR1, BAALC expression was of prognostic significance and high MDR1 expression correlated with a high BAALC expression (r=0.487, P<0.001) in cytogenetically normal AML in the prophase study then we hypothesized that MDR1 and BAALC expression together would better identify the patient’s risk profile. METHODS:Pretreatment bone marrow samples from 92 cytogenetically normal AML patients were analyzed for MDR1 and BAALC mRNA expression by real-time reverse transcriptase polymerase chain reaction. Patients were divided into low MDR1 and BAALC expression group and combined group (high MDR1 and/or high BAALC expression) according to MDR1 and BAALC levels and were compared for clinical outcome. RESULTS:73 cases of 92 cytogenetically normal AML patients got CR after the first block with a CR rate being 79.3%. However, 29 cases of the CR patients relapsed with the relapsed rate being 39.7%. In contrast, Patients with low expression of both MDR1 and BAALC had a higher CR rate (93.3%vs72.6%, P=0.021), lower relapse rate (7.1% vs. 42.5%, P=0.000), longer OS (50.3% vs 17.8%,P=0.001) than high MDR1 and/or high BAALC expression (combined group) in cytogenecally normal AML. Results showed no statistical difference in CR rate (93.3%vs85.7%, P=0.341),relapse rate (7.1% vs. 8.8%, P=0.000) and OS (50.3% vs 63.1%,P=0.431) for cytogenetically normal patients with both MDR1 and BAALC low expression comparing to those with low-risk cytogenetically abnormal. CONCLUSION:The combined assessment of BAALC and MDR1 expression can improve treatment stratification in adult cytogenetically normal AML. Low expression of both MDR1 and BAALC identifies cytogenetically normal AML patients with a favorable long-term outcome. Disclosures:No relevant conflicts of interest to declare.