Measurable residual disease (MRD) is an important biomarker in acute myeloid leukemia (AML) that is used for prognostic, predictive, monitoring, and efficacy-response assessments. The European LeukemiaNet (ELN) MRD working party evaluates standardization and harmonization of MRD in an ongoing manner and has updated the 2018 ELN MRD recommendations based on significant developments in the field. New and revised recommendations were established during in-person and online meetings, and a two-stage Delphi poll was conducted to optimize consensus. All recommendations are graded by levels of evidence and agreement. Major changes include technical specifications for next generation sequencing (NGS)-based MRD testing and integrative assessments of MRD irrespective of technology. Other topics include use of MRD as a prognostic and surrogate endpoint for drug testing; selection of the technique, material, and appropriate time points for MRD assessment; and clinical implications of MRD assessment. In addition to technical recommendations for flow- and molecular- MRD analysis, we provide MRD thresholds and define MRD response, and detail how MRD results should be reported and combined if several techniques are used. MRD assessment in AML is complex and clinically relevant, and standardized approaches to application, interpretation, technical conduct, and reporting are of critical importance.

Genetic heterogeneity contributes to clinical outcome and progression of most tumors. Yet, little is known regarding allelic diversity for epigenetic compartments and almost no data exists for acute myeloid leukemia (AML). Here we examined epigenetic heterogeneity as assessed by cytosine methylation within defined genomic loci with four CpGs (epigenetic alleles), somatic mutations and transcriptomes of AML patient samples at serial time points. We observe that epigenetic allele burden is linked to inferior outcome and varies considerably during disease progression. Epigenetic and genetic allelic burden and patterning follow different patterns and kinetics during disease progression. We observed a subset of AMLs with high epiallele and low somatic mutation burden at diagnosis, a subset with high somatic mutation and lower epiallele burdens at diagnosis, and a subset with a mixed profile, suggesting distinct modes of tumor heterogeneity. Genes linked to promoter-associated epiallele shifts during tumor progression display increased single-cell transcriptional variance and differential expression, suggesting functional impact on gene regulation. Thus, genetic and epigenetic heterogeneity can occur with distinct kinetics, each likely able to impact biological and clinical features of tumors.

We investigated the effect on outcome of measurable or minimal residual disease (MRD) status after each induction course to evaluate the extent of its predictive value for acute myeloid leukemia (AML) risk groups, including NPM1 wild-type (wt) standard risk, when incorporated with other induction response criteria. MethodsAs part of the NCRI AML17 trial, 2,450 younger adult patients with AML or high-risk myelodysplastic syndrome had prospective multiparameter flow cytometric MRD (MFC-MRD) assessment. After course 1 (C1), responses were categorized as resistant disease (RD), partial remission (PR), and complete remission (CR) or complete remission with absolute neutrophil count , 1,000/mL or thrombocytopenia , 100,000/mL (CRi) by clinicians, with CR/CRi subdivided by MFC-MRD assay into MRD+ and MRD2. Patients without high-risk factors, including Flt3 internal tandem duplication wt/2NPM1-wt subgroup, received a second daunorubicin/cytosine arabinoside induction; course 2 (C2) was intensified for patients with high-risk factors. ResultsSurvival outcomes from PR and MRD+ responses after C1 were similar, particularly for good-to standard-risk subgroups (5-year overall survival [OS], 27% RD v 46% PR v 51% MRD+ v 70% MRD2; P , .001). Adjusted analyses confirmed significant OS differences between C1 RD versus PR/MRD+ but not PR versus MRD+. CRi after C1 reduced OS in MRD+ (19% CRi v 45% CR; P = .001) patients, with a smaller effect after C2. The prognostic effect of C2 MFC-MRD status (relapse: hazard ratio [HR], 1.88 [95% CI, 1.50 to 2.36], P , .001; survival: HR, 1.77 [95% CI, 1.41 to 2.22], P , .001) remained significant when adjusting for C1 response. MRD positivity appeared less discriminatory in poor-risk patients by stratified analyses. For the NPM1-wt standard-risk subgroup, C2 MRD+ was significantly associated with poorer outcomes (OS, 33% v 63% MRD2, P = .003; relapse incidence, 89% when MRD+ $ 0.1%); transplant benefit was more apparent in patients with MRD+ (HR, 0.72; 95% CI, 0.31 to 1.69) than those with MRD2 (HR, 1.68 [95% CI, 0.75 to 3.85]; P = .16 for interaction). ConclusionMFC-MRD can improve outcome stratification by extending the definition of partial response after first induction and may help predict NPM1-wt standard-risk patients with poor outcome who benefit from transplant in the first CR. J Clin Oncol 36:1486-1497. © 2018 by American Society of Clinical Oncology INTRODUCTIONIn acute myeloid leukemia (AML), failure to achieve morphologic complete remission (CR) after a first cycle of induction in previously untreated patients is an established independent prognostic factor from earlier studies. 1-3 Thus, morphologic response at this time point is often incorporated with genetic and pretreatment clinical parameters to guide further therapy, 4 including second induction courses, choice of consolidation, and whether intensification from allogeneic stemcell transplantation (SCT) may be appropriate in otherwise intermediate-risk patients. Despite morphologic response criteria being standard, a differe...

Relapse remains the most common cause of treatment failure for patients with acute myeloid leukemia (AML) who undergo allogeneic stem cell transplantation (alloSCT), and carries a grave prognosis. Multiple studies have identified the presence of measurable residual disease (MRD) assessed by flow cytometry before alloSCT as a strong predictor of relapse, but it is not clear how these findings apply to patients who test positive in molecular MRD assays, which have far greater sensitivity. We analyzed pretransplant blood and bone marrow samples by reverse-transcription polymerase chain reaction in 107 patients with NPM1-mutant AML enrolled in the UK National Cancer Research Institute AML17 study. After a median follow-up of 4.9 years, patients with negative, low (<200 copies per 105ABL in the peripheral blood and <1000 copies in the bone marrow aspirate), and high levels of MRD had an estimated 2-year overall survival (2y-OS) of 83%, 63%, and 13%, respectively (P < .0001). Focusing on patients with low-level MRD before alloSCT, those with FLT3 internal tandem duplications(ITDs) had significantly poorer outcome (hazard ratio [HR], 6.14; P = .01). Combining these variables was highly prognostic, dividing patients into 2 groups with 2y-OS of 17% and 82% (HR, 13.2; P < .0001). T-depletion was associated with significantly reduced survival both in the entire cohort (2y-OS, 56% vs 96%; HR, 3.24; P = .0005) and in MRD-positive patients (2y-OS, 34% vs 100%; HR, 3.78; P = .003), but there was no significant effect of either conditioning regimen or donor source on outcome. Registered at ISRCTN (http://www.isrctn.com/ISRCTN55675535).

Epigenetic regulators, such as EZH2, are frequently mutated in cancer, and loss-of-function EZH2 mutations are common in myeloid malignancies. We have examined the importance of cellular context for Ezh2 loss during the evolution of acute myeloid leukemia (AML), where we observed stage-specific and diametrically opposite functions for Ezh2 at the early and late stages of disease. During disease maintenance, WT Ezh2 exerts an oncogenic function that may be therapeutically targeted. In contrast, Ezh2 acts as a tumor suppressor during AML induction. Transcriptional analysis explains this apparent paradox, demonstrating that loss of Ezh2 derepresses different expression programs during disease induction and maintenance. During disease induction, Ezh2 loss derepresses a subset of bivalent promoters that resolve toward gene activation, inducing a feto-oncogenic program that includes genes such as Plag1, whose overexpression phenocopies Ezh2 loss to accelerate AML induction in mouse models. Our data highlight the importance of cellular context and disease phase for the function of Ezh2 and its potential therapeutic implications.

PURPOSE Reduced-intensity conditioning (RIC) regimens have extended the curative potential of allogeneic stem-cell transplantation to older adults with high-risk acute myeloid leukemia (AML) and myelodysplasia (MDS) but are associated with a high risk of disease relapse. Strategies to reduce recurrence are urgently required. Registry data have demonstrated improved outcomes using a sequential transplant regimen, fludarabine/amsacrine/cytarabine-busulphan (FLAMSA-Bu), but the impact of this intensified conditioning regimen has not been studied in randomized trials. PATIENTS AND METHODS Two hundred forty-four patients (median age, 59 years) with high-risk AML (n = 164) or MDS (n = 80) were randomly assigned 1:1 to a fludarabine-based RIC regimen or FLAMSA-Bu. Pretransplant measurable residual disease (MRD) was monitored by flow cytometry (MFC-MRD) and correlated with outcome. RESULTS There was no difference in 2-year overall survival (hazard ratio 1.05 [85% CI, 0.80 to 1.38] P = .81) or cumulative incidence of relapse (CIR) (hazard ratio 0.94 [95%CI, 0.60 to 1.46] P = .81) between the control and FLAMSA-Bu arms. Detectable pretransplant MFC-MRD was associated with an increased CIR (2-year CIR 41.0% v 20.0%, P = .01) in the overall trial cohort with a comparable prognostic impact when measured by an unsupervised analysis approach. There was no evidence of interaction between MRD status and conditioning regimen intensity for relapse or survival. Acquisition of full donor T-cell chimerism at 3 months abrogated the adverse impact of pretransplant MRD on CIR and overall survival. CONCLUSION The intensified RIC conditioning regimen, FLAMSA-Bu, did not improve outcomes in adults transplanted for high-risk AML or MDS regardless of pretransplant MRD status. Our data instead support the exploration of interventions with the ability to accelerate acquisition of full donor T-cell chimerism as a tractable strategy to improve outcomes in patients allografted for AML.

Clinical recommendations for Acute Myeloid Leukemia (AML) classification and risk-stratification remain heavily reliant on cytogenetic findings at diagnosis, which are present in <50% of patients. Using comprehensive molecular profiling data from 3,653 patients we characterize and validate 16 molecular classes describing 100% of AML patients. Each class represents diverse biological AML subgroups, and is associated with distinct clinical presentation, likelihood of response to induction chemotherapy, risk of relapse and death over time. Secondary AML-2, emerges as the second largest class (24%), associates with high-risk disease, poor prognosis irrespective of flow Minimal Residual Disease (MRD) negativity, and derives significant benefit from transplantation. Guided by class membership we derive a 3-tier risk-stratification score that re-stratifies 26% of patients as compared to standard of care. This results in a unified framework for disease classification and risk-stratification in AML that relies on information from cytogenetics and 32 genes. Last, we develop an open-access patient-tailored clinical decision support tool.

Summary Based on promising results in older adults with acute myeloid leukaemia (AML), we treated patients with NPM1mut measurable residual disease (MRD) using off‐label venetoclax in combination with low‐dose cytarabine or azacitidine. Twelve consecutive patients were retrospectively identified, including five with molecular persistence and seven with molecular relapse/progression. All patients with molecular persistence achieved durable molecular complete remission (CRMRD‐) without transplantation. Six of seven patients with molecular relapse/progression achieved CRMRD‐ after 1–2 cycles of venetoclax. This paper highlights the promising efficacy of venetoclax‐based therapy to reduce the relapse risk in patients with persistent or rising NPM1mut MRD.