Prognostic value of real-time quantitative PCR (RQ-PCR) in AML with t(8;21)

Despite the favorable prognosis of patients with acute myeloid leukemia ( AML) with t( 8; 21)( q22; q22) translocation, relapses still occur in about 30% of the cases but no initial factors can strongly predict the risk of relapse. Several recent studies suggest that monitoring minimal residual disease ( MRD) may identify patients at risk of relapse. We prospectively monitored AML1 - ETO rearrangement by real- time quantitative PCR ( RQ-PCR) in 21 patients uniformly treated in our center. Blood ( PB) and bone marrow ( BM) samples were collected during and after therapy. At diagnosis, levels of AML1 - ETO transcript showed large variations and there was a trend for a higher relapse rate in patients with high pretreatment expression levels ( P = 0.065). After induction therapy, absolute transcript levels ( below 10(-3), compared to Kasumi cell line), or a greater than 3 log decrease by comparison to diagnosis levels, were significant predictors of the absence of relapse ( P = 0.02 and P = 0.02, respectively). MRD levels after consolidation therapy were also significant indicators of relapse ( P = 10(-5)). Comparison of BM and PB samples showed similar sensitivity for detecting AML1 - ETO transcript. In conclusion, RQ- PCR appears to be an early predictive factor of the relapse risk in AML with t( 8; 21). PB samples can be used adequately to evaluate the level of MRD by this technique.