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 an 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.