MDR1 RNA EXPRESSION AS A PROGNOSTIC FACTOR IN ACUTE MYELOID-LEUKEMIA - AN UPDATE

In order to confirm our initial report on the negative impact of MDR1 gene expression on the outcome of de novo acute myeloid leukemia (AML) , we present an update of our prospective study with a larger number o f patients and a longer duration of follow-up. At diagnosis, MDR1 RNA expression of the leukemic cells was negative in 37% and positive in 6 3% of the patients (N = 79). The complete remission rate of induction chemotherapy was 76% for MDR1 RNA negative and 54% for MDR1 RNA positi ve patients (p = 0.05). At a median observation duration of 33 months, the duration of overall survival was 19 months for the MDR1 RNA negat ive patients but only 8 months for the patients with MDR1 gene express ion (p = 0.02). Thus the long-term data also indicate that MDR1 gene e xpression is an unfavourable prognostic factor in AML.