Interlaboratory cross validation of acute myeloid leukemia fusion genes and mutational targets detected by PCR: Performance of PETHEMA central laboratories.

The rapid and accurate laboratory identification of targetable therapeutic genes, together with the implementation of measurable residual disease (MRD) based decision is essential for optimal clinical management in acute myeloid leukemia (AML). The PETHEMA (Programa Español de Tratamientos en Hematología) cooperative group comprises nine laboratories that perform centralized molecular studies by conventional PCR and Real-time quantitative PCR (RT-qPCR) for AML patients. With the aim to validate laboratories performances, we conducted three rounds of interlaboratory cross validation (ICV) for the quantification of CBFB::MYH11, RUNX1::RUNX1T1 and NPM1 and one round to determine the mutational status of NPM1, FLT3 (ITD and TKD2) IDH1 and IDH2. For RT-qPCR a total of 19 samples were tested and only 3 (15.8 %) failed to achieve 100 % concordance, corresponding to samples with low target gene mean ratios (ICV1-S4, ICV2-S1, ICV2-S6). For mutation detection in a total of 227 returned results, concordance rate ranged from 95 % to 100 %. FLT3-ITD and NPM1 mutation detection had 100 % concordant results. One false negative was reported for IDH2- R140 mutation and 4 false positives were detected: 2 FLT3-TKD2 and 2 IDH1-R132, likely reflecting differences in assay sensitivity. Overall, the results were highly satisfactory, particularly regarding MRD assessment, and highlighted key points for improvement, especially in baseline detection of FLT3-TKD2 and IDH1 mutations. This study represents the first collaborative initiative to evaluate performance of AML molecular targets within a laboratory network and underscores the importance of regular exercises to monitor performance, identify and resolve technical or interpretive discrepancies to ultimately ensure accurate clinical decision-making.