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Multi drug resistance (MDR) is a major obstacle for cancer therapy. The three major candidates accounting for the development of MDR in acute myeloid leukaemia (AML) are multi drug resistance gene (MDR1), multi drug resistance-related protein gene (MRP1) and lung resistance protein gene(LRP). So far, the differential impact of resistance gene expression on treatment outcome in AML is not clear. Therefore, we examinedMDR1,MRP1andLRPgene expression at diagnosis in 331 adult AML patients in the context of other known prognostic factors, such as age, disease status, cytogenetics and FMS-like tyrosine kinase 3 (FLT3)-internal tandem duplication mutational status. Median observation time was longer than 5 years [64·1 months (40·0–87·6)].MDR1expression proved to be an independent prognostic factor for outcome of induction therapy (P < 0·001) and overall survival (P = 0·02), whereasMRP1expression was an independent predictor for disease-free survival (P = 0·01) in the multivariate analysis. This prognostic impact of both resistance genes was also found in patients with intermediate risk cytogenetics.LRPexpression, however, had no impact on treatment outcome in AML. Our study shows that resistance gene expression should be considered together with age, cytogenetics and FLT3 mutational status for risk-adapted treatment strategies in AML in the future. [ABSTRACT FROM AUTHOR]

Acute myeloid leukaemia (AML) carrying t(8;21) has an overall favourable prognosis. However, relapse occurs and the impact of multidrug resistance gene (MDR1) expression on recurring disease in this group of patients is not known. We determined quantifiable MDR1 expression in the bone marrow of 28 AML patients with t(8;21) by a validated real-time polymerase chain reaction assay. Using MDR1 expression, white blood cell count and CD56 expression at diagnosis we observed complete concordance of predicted and observed relapses. A calculated logit out of these three variables was a strong independent prognostic factor for overall (P = 0007) and disease-free survival (P = 0.002). [ABSTRACT FROM AUTHOR]