Pediatric AML with KMT2A::MLLT10 accounts for 10%-15% of KMT2A-rearranged AML and is associated with poor prognosis. Lately, the assessment of measurable residual disease (MRD) by reverse transcriptio Show more
Pediatric AML with KMT2A::MLLT10 accounts for 10%-15% of KMT2A-rearranged AML and is associated with poor prognosis. Lately, the assessment of measurable residual disease (MRD) by reverse transcription quantitative polymerase chain reaction (RT-qPCR) has become an important tool for disease management; however, in the pediatric setting, it lacks standardized protocols. Therefore, we investigated the prognostic relevance of MRD monitoring by RT-qPCR during high-dose polychemotherapy in pediatric patients with AML expressing KMT2A::MLLT10. Using RNA sequencing, we determined the fusion breakpoints and designed RT-qPCR assays for MRD monitoring. Bone marrow samples collected from 41 patients, who were treated in the AML-BFM or AIEOP study, were analyzed for MRD by RT-qPCR. MRD positivity after the second treatment course resulted in a significantly worse probability of overall survival (pOS) compared to MRD negative patients (33.3% ± 19.2% vs. 80.6% ± 7.8%, p = 0.032). Moreover, the probability of event-free survival (pEFS) (16.7% ± 15.2% vs. 76.9% ± 8.3%, p = 0.003) and cumulative incidence of relapse (CIR) (83.3% ± 40.8% vs. 19.2% ± 40.2%, p = 0.001) were significantly worse for patients in complete morphologic remission who remained MRD positive after the second treatment course. Thus, MRD monitoring enables the identification of a subgroup of pediatric patients with AML carrying KMT2A::MLLT10 in complete morphologic remission with a dismal prognosis despite the current intensive therapy regimen. AML-BFM study 2004: ClinicalTrials.gov Identifier: NCT00111345; AML-BFM registry 2012 and AML-BFM study 2012: EudraCT 2013-000018-39; AML-BFM registry 2017: DRKS number: DRKS00013030. Show less
New methods like panel-based RNA fusion sequencing (RNA-FS) promise improved diagnostics in various malignancies. We here analyzed the impact of RNA-FS on the initial diagnostics of 241 cases with ped Show more
New methods like panel-based RNA fusion sequencing (RNA-FS) promise improved diagnostics in various malignancies. We here analyzed the impact of RNA-FS on the initial diagnostics of 241 cases with pediatric acute myeloid leukemia (AML). We show that, compared to classical cytogenetics (CCG), RNA-FS reliably detected risk-relevant fusion genes in pediatric AML. In addition, RNA-FS strongly improved the detection of cryptic fusion genes like NUP98::NSD1, KMT2A::MLLT10 and CBFA2T3::GLIS2 and thereby resulted in an improved risk stratification in 25 patients (10.4%). Validation of additionally detected non-risk-relevant high confidence fusion calls identified PIM3::BRD1, C22orf34::BRD1, PSPC1::ZMYM2 and ARHGAP26::NR3C1 as common genetic variants and MYB::GATA1 as recurrent aberration, which we here describe in AML subtypes M0 and M7 for the first time. However, it failed to detect rare cytogenetically confirmed fusion events like MNX1::ETV6 and other chromosome 12p-abnormalities. As add-on benefit, the proportion of patients for whom measurable residual disease (MRD) monitoring became possible was increased by RNA-FS from 44.4 to 75.5% as the information on the fusion transcripts' sequence allowed the design of new MRD assays. Show less