New score predicting for prognosis in PML-RARA+, AML1-ETO+, or CBFBMYH11+ acute myeloid leukemia based on quantification of fusion transcripts.

To evaluate the prognostic significance of quantitative PML-RARA, AML1-ETO, and CBFB-MYH11 fusion transcript expression, real-time polymerase chain reaction was used to analyze bone marrow samples of 349 such patients at diagnosis and 522 samples of 142 patients also during therapy (total analyses, n = 859; median number of follow-up samples, 4/patient; median duration of assessment, 12 months). Lower expression levels at diagnosis correlated with better overall and event-free survival in all 3 leukemia subtypes. By combining the median expression ratio after consolidation therapy and the 75th percentile of the expression ratio at diagnosis, a new score was established that separates a group with 100% EFS from a significantly worse group (P <.0001) in each of the 3 acute myeloid leukemia subgroups. Eight patients showed increasing levels of expression during follow-up and all had relapse. In conclusion, patients at high risk for treatment failure can be identified by high levels of fusion gene expression at diagnosis or less than 3 logs of tumor reduction during the first 3 to 4 months of therapy. By combining the transcription ratios at these 2 checkpoints, a new powerful prognostic score has been established.