[A clinical study on multidrug resistance gene (MDR1) expression in acute leukemia].

The authors established a highly sensitive, specific and quantitative method-RT-PCR for measuring the levels of MDR1 mRNA in 91 acute leukemic samples (including 30 untreated cases, 32 remission cases, 29 refractory and relapse cases). The results showed that MDR1 mRNA positive rate for refractory and relapse cases, untreated cases and remission cases were 82.8%, 40.0%, 28.1% respectively. In untreated patients, it was found that the first complete remission rate differed significantly between MDR1 positive (41.7%) and MDR1 negative groups (88.9%) (P < 0.05). In remission group, MDR1 positive cases had a higher relapse rate than MDR1 negative case (66.7%; 13.0% P < 0.01) and all these cases relapsed of MDR1 gene overexpression (6 cases) were resistant to further treatment. It is concluded that the expression of MDR1 mRNA might be an unfavorable prognostic factor for patients with acute leukaemia and could predict the efficacy of intensive chemotherapy and serve as a high risk factor for early and resistant relapse.