Molecular Minimal Residual Disease in Acute Myeloid Leukemia

Prognostic impact of co-mutations in adults with IDH1/2-mutated acute myeloid leukemia

Acute myeloid leukemia (AML) is characterized by the accumulation of cytogenetic and molecular abnormalities. Isocitrate dehydrogenase 1 and 2 (IDH1/2) mutations occur in 11% to 20% of adults with AML. The outcome of IDH1/2-mutated AML is heterogeneous and affected by co-mutational patterns. We retrospectively analyzed 118 patients with IDH1/2-mutated AML who were retrieved from 1597 patients newly diagnosed with AML and treated with intensive chemotherapy. Univariate analysis revealed the NPM1 mutation was a favorable factor (p = 0.019) for overall survival (OS), whereas the DNMT3A mutation was consistently associated with a poor outcome (3-year OS, 52.0%; 3-year relapse-free survival [RFS], 44.8%; and 3-year cumulative incidence of relapse [CIR], 42.6%). Interestingly, the DNMT3A mutation still identified patients with a poorer prognosis, even when measurable residual disease (MRD) was negative after 2 courses of chemotherapy. In a multivariate regression model, age, DNMT3A mutation and MRD positivity were retained as independent adverse markers for OS, RFS, and CIR. In the absence of the DNMT3A or FLT3-ITD mutations, the NPM1 mutation identified patients with a very favorable OS (3-year OS, 96.3% and 86.3%, respectively). Finally, hematopoietic stem cell transplantation in first complete remission significantly improved RFS (p = 0.015) and there was a trend toward improvement in OS (p = 0.282) for patients with the DNMT3A mutation but it did not benefit 2 subgroups with the IDH1/2+/NPM1+/DNMT3A- and IDH1/2+/NPM1+/FLT3-ITD- genotypes. In summary, this study provides a reference for risk stratification and treatment implications for patients with IDH1/2-mutated AML as well as for comparison with results of IDH inhibitor- or venetoclax-based combination therapy.

Flow cytometry evaluation of acute myeloid leukemia minimal residual disease based on an understanding of the normal maturation patterns in the blast compartments

OBJECTIVE

Detection of minimal/measurable disease (MRD) in acute myeloid leukemia (AML) is critical for both clinical decision-making and prognostication, yet remains a challenge. Flow cytometry is a well-established method for MRD detection. Flow cytometric (FC) evaluation of MRD must consider a complex maturational pattern of normal hematopoietic development to separate normal from abnormal progenitors. Here, we offer an example of an interpretive approach based on a thorough understanding of stage- and lineage-specific hematopoietic maturation.

METHODS

We provide a comprehensive overview of blast maturation from early precursors (hematopoietic stem cells) to committed late-stage unilineage progenitors and commonly observed stage-specific abnormalities based on cases we have encountered in practice. We emphasize the importance of stage-specific comparisons for accurate MRD detection by flow cytometry.

RESULTS

The AML blasts almost invariably show abnormal phenotypes, and the phenotypes may evolve upon therapy. The detected phenotypes are necessarily confined to the target antigens included in the panel. It is therefore critical to evaluate a range of antigens to establish a specific stage/state of lineage commitment and detect potential common abnormalities. Moreover, enough cells must be acquired to allow for the detection of MRD at desired levels. Significant technical and analytical validation is critical.

CONCLUSIONS

Flow cytometry offers a powerful single-cell-based platform for MRD detection in AML, and the results have been proven critical for disease management. Leukemia-associated phenotype-informed difference from the normal approach presented in this review presents an analytical framework for sensitive and accurate MRD detection.

A clinical solution for tracking clonal evolution of acute myeloid leukemia after allogeneic transplantation using bulk next generation sequencing

Clinical next generation sequencing (NGS) typically relies on limited gene panels run on bulk marrow or blood. Current computational tools for inferring clonal relationships is generally limited by the use of a small panel of pathogenic mutations to define clones. We developed an online software (CloneTracker) that uses 'incidentally-sequenced' single nucleotide polymorphisms (SNPs) in the regions of recurrent somatic mutations in addition to conventional mutation data from bulk NGS gene panels to provide detailed visualizations of clonal evolution during cancer treatment, alongside clinical data. Tested on 29 patients who underwent non-myeloablative transplantation for AML, CloneTracker successfully reconstructed the evolutionary dynamics of donor engraftment from bulk NGS and rendered intuitive visualizations of residual patient-derived hematopoiesis and relapsing malignant clones. The software does not require sequencing donor samples, as donor-derived clones are identifiable from post-HCT SNP data. This manuscript aims to introduce CloneTracker to the BMT community and make it available for those who would ascertain its clinical utility, e.g, in BMT trials leveraging molecular minimal residual disease (MRD) monitoring and targeted interventions to pre-empt relapse.

Haploidentical Hematopoietic Stem Cell Transplantation for AML Patients with Persistent Molecular MRD

OBJECTIVE

The combined use of quantitative real-time polymerase chain reaction (qPCR) and next-generation sequencing (NGS) to detect molecular measurable residual disease (mMRD) has been shown to have prognostic value for patients undergoing matched-hematopoietic stem cell transplantation (HSCT). However, there have been no related studies in the context of haploidentical HSCT (haplo-HSCT).

METHODS

We included 148 acute myeloid leukemia (AML) patients who were in first complete remission (CR1) and underwent HSCT at Union Hospital (Wuhan, China) between 2019 and 2023. Among them, 28 patients were mMRD (+) before transplantation according to PCR/NGS. Then, on the basis of the 2017 European Leukemia Net (ELN) risk stratification, we randomly enrolled 56 mMRD (-) patients at a 1:2 ratio. Finally, we compared the outcomes, including overall survival (OS), cumulative incidence of relapse (CIR), leukemia-free survival (LFS), and nonrelapse mortality (NRM), between the two groups.

RESULTS

Persisting mMRD predicts worse long-term clinical outcomes in AML patients who received haplo-HSCT. The 2-year OS and LFS between the mMRD (+) and mMRD (-) groups were 77.1% (95%CI 62.5-95.2) versus 92.3% (95%CI 85.3-99.9) (P = 0.044) and 72.7% (95%CI 56.9-92.8) versus 90.7% (95%CI 83.2-98.8) (P = 0.003), respectively. The results of multivariate analysis revealed that mMRD (+) patients had worse OS and LFS than control patients did and that the mMRD (+) score was an independent prognostic factor for OS and LFS.

CONCLUSION

Pre-HSCT mMRD has predictive value for haplo-HSCT outcomes in AML patients. Patients who are mMRD (+) before transplantation have poorer OS and LFS. For these patients, intensified myeloablative conditioning (MAC), rapid reduction in immunosuppressive agents after 30 days, and pro-donor lymphocyte infusion (DLI) can improve post-transplant outcomes.

Acute Myeloid Leukemia: 2025 Update on Diagnosis, Risk-Stratification, and Management

DISEASE OVERVIEW

Acute myeloid leukemia (AML) is a bone marrow stem cell cancer that is often fatal despite available treatments. Diagnosis, risk assessment, monitoring, and therapeutic management of AML have changed dramatically in the last decade due to increased pathophysiologic understanding, improved assessment technology, and the addition of at least 12 approved therapies.

DIAGNOSIS

The diagnosis is based on the presence of immature leukemia cells in the blood, and/or bone marrow or less often in extra-medullary tissues. New biological insights have been integrated into recent classification systems.

RISK ASSESSMENT

The European Leukemia Network has published risk classification algorithms for both intensively and non-intensively treated patients based on cytogenetic and on molecular findings. Prognostic factors may differ based on the therapeutic approach.

MONITORING

Our increasing ability to quantify lower levels of measurable residual disease (MRD) potentially allows better response assessment, as well as dynamic monitoring of disease status. The incorporation of MRD findings into therapeutic decision-making is rapidly evolving.

RISK ADAPTED THERAPY

The availability of 12 newly approved agents has been welcomed; however, optimal strategies incorporating newer agents into therapeutic algorithms are debated. The overarching approach integrates patient and caregiver goals of care, comorbidities, and disease characteristics.

Combination of pre-transplant flow cytometry, WT1 expression, and NGS for MRD monitoring is potent in predicting the prognosis of AML receiving allogeneic transplantation

Minimal residual disease (MRD) monitoring has been demonstrated to important in predicting prognosis in acute myeloid leukemia (AML) receiving allogeneic hematopoietic stem cell transplantation (allo-HSCT), but the ideal time point and method remain unclear. Our study compared the prognostic value of multiparameter flow cytometry (MFC)-based and WT1 expression-based MRD a month before allo-HSCT [HSCT(-1 m)] and after allo-HSCT [HSCT(+ 1 m)], as well as next generation sequencing (NGS)-based MRD at HSCT(-1 m), HSCT(+ 1 m), 3 and 6 months after allo-HSCT [HSCT(+ 3 m) and HSCT(+ 6 m)] among 47 AML patients undergoing allo-HSCT. The MRD status by all the methods at HSCT(-1 m) was proved as a superior indicator with prognostic significance for disease progression, compared to that at HSCT(+ 1 m). For the NGS-based MRD, HSCT(+ 6 m) seemed to be the optimal detection time point, as supported by the optimal prognostic discrimination capability and the relatively high sensitivity for disease progression prediction. Moreover, our data showed that each individual method had some limitations in predicting prognosis; however, pre-transplant MRD monitoring by the combination of MFC, WT1 and NGS could greatly increase the sensitivity (100%) of identifying disease progression and greatly improve prognostic stratification. Our study may provide insights into the optimal time point and methodology for MRD monitoring in AML following allo-HSCT.

Persistent postremission clonal hematopoiesis shapes the relapse trajectories of acute myeloid leukemia

ABSTRACT

Mutations found in acute myeloid leukemia (AML) such as DNMT3A, TET2, and ASXL1 can be found in the peripheral blood of healthy adults, a phenomenon termed clonal hematopoiesis (CH). These mutations are thought to represent the earliest genetic events in the evolution of AML. Genomic studies on samples acquired at diagnosis, remission, and at relapse have demonstrated significant stability of CH mutations after induction chemotherapy. Meanwhile, later mutations in genes such as NPM1 and FLT3 have been shown to contract at remission, and in the case of FLT3 often are absent at relapse. We sought to understand how early CH mutations influence subsequent evolutionary trajectories throughout remission and relapse in response to induction chemotherapy. We assembled a retrospective cohort of patients diagnosed with de novo AML at our institution that underwent genomic sequencing at diagnosis, remission, and/or relapse (total N = 182 patients). FLT3 and NPM1 mutations were generally eliminated at complete remission but subsequently reemerged upon relapse, whereas DNMT3A, TET2, and ASXL1 mutations often persisted through remission. CH-related mutations exhibited distinct constellations of co-occurring genetic alterations, with NPM1 and FLT3 mutations enriched in DNMT3Amut AML, whereas CBL and SRSF2 mutations were enriched in TET2mut and ASXL1mut AML, respectively. In the case of NPM1 and FLT3 mutations, these differences vanished at the time of complete remission yet readily reemerged upon relapse, indicating the reproducible nature of these genetic interactions. Thus, CH-associated mutations that likely precede malignant transformation subsequently shape the evolutionary trajectories of AML through diagnosis, therapy, and relapse.

Fifth edition WHO classification: myeloid neoplasms

The fifth edition of the WHO classification of haematolymphoid tumours (WHO-HEM5) introduces significant advancements in the understanding and diagnosis of myeloid neoplasms, emphasising molecular and genetic insights. This review highlights key updates from the revised fourth edition (WHO-HEM4R), particularly the integration of genetic criteria for disease classification. Many entities are now defined by specific genetic abnormalities, enhancing diagnostic precision and prognostic assessment. Notably, the elimination of the 20% blast threshold for acute myeloid leukaemia (AML) with specific defining genetic alterations reflects a shift towards genomic-driven diagnostics. Additional updates include the refined subclassification of myelodysplastic neoplasms (MDS) and MDS/myeloproliferative neoplasms, as well as the recognition of novel entities such as clonal haematopoiesis and MDS with biallelic TP53 inactivation, further expanding the spectrum of myeloid neoplasms. WHO-HEM5 illustrates the diagnostic utility of morphology, flow cytometry, immunohistochemistry and next-generation sequencing in resource-rich settings. However, its implementation in low-income and middle-income countries (LMICs) remains challenging due to limited access to advanced diagnostic tools. This review explores strategies to optimise diagnosis in resource-constrained environments, where morphology and immunophenotyping remain fundamental. By integrating molecular diagnostics with traditional methods, WHO-HEM5 aims to refine classification and facilitate risk stratification in the era of personalised medicine, providing haematopathologists and clinicians with an essential framework to navigate the complexities of myeloid neoplasms. The emphasis on advancing haematopathology practices worldwide, including in LMICs, demonstrates the ongoing commitment to improving global outcomes in haematological malignancies.

Evolution of Allogeneic Stem Cell Transplantation: Main Focus on AML

In recent years, treatments in the field of hematologic malignancies have undergone significant evolution; allogeneic hematopoietic stem cell transplantation (allo-HSCT) has shifted from an "ultimate" therapy to becoming a component of a comprehensive therapeutic strategy for acute myeloid leukemia (AML). Advances in risk stratification (including molecular profiling and measurable residual disease assessment), conditioning regimens, and graft-versus-host disease (GVHD) prophylaxis-such as post-transplant cyclophosphamide-have improved outcomes and expanded donor selection and transplant eligibility. We should not only focus on the transplantation procedure but also consider various therapeutic components, including chemotherapy, targeted therapy (possibly including chimeric antigen receptor T-cell therapy), and post-transplant maintenance therapy, which need to be orchestrated within the broader context of leukemia treatment. In this review, we summarized key developments in allo-HSCT for AML and aim to "decipher" each component of transplantation.

Transplanting Hope: Managing Relapsed/Refractory AML

Acute myeloid leukemia (AML) is a heterogeneous malignant disorder of myeloid precursor cells, with high relapse rates, particularly in patients who fail to achieve morphological remission after induction therapy. Allogeneic hematopoietic cell transplantation (allo-HCT) can induce durable remissions through the graft-versus-leukemia (GVL) effect, yet current approaches of allo-HSCT often fail, with relapse rates of ∼40% within 6 months post-transplant. Outcomes following allo-HCT are inversely proportional to leukemia burden at the time of transplant. Both morphological relapse (≥5% blasts in the marrow) or minimal residual disease (MRD) positivity predict significantly reduced overall survival rates. Emerging strategies to improve outcomes in patients with high leukemic burden include aggressive bridging therapies (encompassing intensive salvage chemotherapy, hypomethylating agents, targeted inhibitors, and sequential induction-conditioning approaches such as FLAMSA), tailored conditioning regimens, post-transplant maintenance therapy, and innovative graft engineering methods. Graft engineering strategies, such as ORCA-T, which engineers stem cell grafts with a defined ratio of T-regulatory cells to effector T cells, are particularly promising and under evaluation in phase III clinical trials. These approaches aim to improve upon the poor outcomes for patients with persistent/relapsed AML undergoing allo-HCT.

Precision epitope editing: A path to advanced immunotherapies

The ability to recognize antigen epitope is crucial for generating an effective immune response. By engineering these epitopes, researchers can reduce on-target/off-tumor toxicity associated with targeted immunotherapy. Recent studies indicate that employing various gene editing tools to modify the epitopes of healthy hematopoietic stem and progenitor cells (HSPCs) can protect these cells from toxicity during tumor eradication, all while preserving their differentiation and function. This advancement greatly enhances the safety and efficacy of tumor immunotherapy.

Double mutant DNMT3A AML: a unique subtype experiencing increased DNA damage and poor prognosis

ABSTRACT

Mutation of DNMT3A, encoding a de novo methyltransferase essential for cytosine methylation, is a common early event in clonal hematopoiesis (CH) and adult acute myeloid leukemia (AML). Spontaneous deamination of methylated cytosines damages DNA, which is repaired by the base excision repair (BER) enzymes methyl-CpG binding domain 4 (MBD4) and thymine DNA glycosylase (TDG). Congenital MBD4 deficiency has been linked to early-onset CH and AML and is marked by exceedingly high levels of DNA damage and mutation of DNMT3A. Strikingly, wild-type (WT) DNMT3A binds TDG, thereby potentiating its repair activity. Because TDG is the only remaining BER enzyme in MBD4-deficient patients with AML capable of repairing methylation damage, we investigated whether mutant DNMT3A negatively affects the repair function of TDG. We found that, although WT DNMT3A stimulates TDG function, mutant DNMT3A impairs TDG-mediated repair of DNA damage in vitro. In light of this finding and to extrapolate our observations to the broader AML patient population, we investigate here the genetic profiles and survival outcomes of patients with AML with single mutant (SM) vs double mutant (DM) DNMT3A. Patients with DM DNMT3A AML show a characteristic driver mutation landscape and reduced overall survival compared with patients with SM DNMT3A AML. Importantly, whole-genome sequencing showed a trend for increased DNA damage in primary DM DNMT3A AML samples, especially when DNMT3A mutations are located at the DNMT3A-TDG interaction interface.

Maintenance Therapy in AML: What Is the Future Potential?

Over the last decade, there have been significant advancements in the treatment for patients with acute myeloid leukemia (AML) including the addition of novel, targeted agents to intensive or nonintensive chemotherapy regimens. However, despite this, the majority of patients will still ultimately relapse and long-term survival remains poor. While the use of maintenance therapy has emerged as a potential strategy to maintain more durable remissions and improve overall survival, the optimal use of these therapies has not yet been clearly defined. In this review, we provide a comprehensive overview of the evolution of maintenance strategies in AML and present a commentary on the future of maintenance therapy, including the pressing, unmet needs in this field.

A practice-oriented genome-profiling study for acute myeloid leukemia using the novel HANDLE system: HM-screen-JAPAN02

HM-SCREEN-Japan is a multicenter collaborative project in Japan to evaluate the clinical utility of a cancer genome panel in the treatment of acute myeloid leukemia (AML). The HM-SCREEN-JAPAN02 study used the Amoy Myeloid Panel® with the HANDLE system, which enables efficient and rapid sequencing, as the genomic testing kit. The Amoy Myeloid Panel® targets 53 genes with established clinical significance or high prevalence. The study analyzed bone marrow fluid or peripheral blood. Multiple time points for submission were allowed to evaluate clonal changes over time. A total of 179 tests/145 patients with one or more pathogenic mutations (23 patients submitted specimens at multiple time points) were included in the analysis. A variety of patterns were detected, including acquisition of new resistance-associated genetic mutations and pathogenic mutations remaining after clinical remission. The median time required for sequencing and annotation was 8 days. TP53 and NRAS mutations were associated with increased risk of death (hazard ratio = 3.98 and 5.50, respectively). In a survey of physicians at the participating centers, 63% reported that the genomic panel was clinically useful, particularly for assessing clinical risk and evaluating indications for hematopoietic stem cell transplantation.

Frontline Therapy of AML in the Fit and Younger Population-Incorporating Molecularly Targeted Agents

Backbone therapy for acute myeloid leukemia for younger adults has for 50 years been based on a combination of cytarabine and anthracycline. Over the past 10 years the addition of several targeted agents has been found to improve the outcomes of subsets of AML with particular molecular changes. In this review we will examine the data generated to date on the addition of agents targeting CD33, FLT3, IDH, and BCL2 to standard high intensity therapies. We will also review the potential for future studies evaluating the application of highly active lower intensity therapies developed in older adults to patients considered "fit for high intensity induction." Lastly, we review the data around the role of stem cell transplant in the modern targeted era.

Measurable residual disease monitoring in AML: Prospects for therapeutic decision-making and new drug development

Measurable residual disease (MRD) is strongly associated with risk of relapse and long-term survival outcomes in patients with acute myeloid leukemia (AML). Apart from its clear prognostic impact, MRD information is also increasingly used to guide therapeutic decision-making, including selection of appropriate patients for stem cell transplant, use of post-transplant maintenance, and candidacy for non-transplant maintenance therapies or MRD-directed clinical trials. While much progress has been made in accurately assessing MRD and understanding its clinical importance, many questions remain about how to optimize MRD testing and guide treatment decisions for individual patients. In this review, we discuss the common methods to assess MRD in AML and the prognostic impact of MRD across common clinical scenarios. We also review emerging and investigational strategies to target MRD and discuss some of the important unanswered questions and challenges in the field.

Significance of targeting DNMT3A mutations in AML

Acute myeloid leukemia (AML) is the most prevalent form of leukemia among adults, characterized by aggressive behavior and significant genetic diversity. Despite decades of reliance on conventional chemotherapy as the mainstay treatment, patients often struggle with achieving remission, experience rapid relapses, and have limited survival prospects. While intensified induction chemotherapy and allogeneic stem cell transplantation have enhanced patient outcomes, these benefits are largely confined to younger AML patients capable of tolerating intensive treatments. DNMT3A, a crucial enzyme responsible for establishing de novo DNA methylation, plays a pivotal role in maintaining the delicate balance between hematopoietic stem cell differentiation and self-renewal, thereby influencing gene expression programs through epigenetic regulation. DNMT3A mutations are the most frequently observed genetic abnormalities in AML, predominantly in older patients, occurring in approximately 20-30% of adult AML cases and over 30% of AML with a normal karyotype. Consequently, the molecular underpinnings and potential therapeutic targets of DNMT3A mutations in AML are currently being thoroughly investigated. This article provides a comprehensive summary and the latest insights into the structure and function of DNMT3A, examines the impact of DNMT3A mutations on the progression and prognosis of AML, and explores potential therapeutic approaches for AML patients harboring DNMT3A mutations.

Effective eradication of acute myeloid leukemia stem cells with FLT3-directed antibody-drug conjugates

Refractory disease and relapse are major challenges in acute myeloid leukemia (AML) therapy attributed to survival of leukemic stem cells (LSC). To target LSCs, antibody-drug conjugates (ADCs) provide an elegant solution, combining the specificity of antibodies with highly potent payloads. We aimed to investigate if FLT3-20D9h3-ADCs delivering either the DNA-alkylator duocarmycin (DUBA) or the microtubule-toxin monomethyl auristatin F (MMAF) can eradicate quiescent LSCs. We show here that DUBA more potently kills cell-cycle arrested AML cells compared to microtubule-targeting auristatins. Due to limited stability of 20D9h3-DUBA ADC in vivo, we analyzed both ADCs in advanced in vitro stem cell assays. 20D9h3-DUBA successfully eliminated leukemic progenitors in vitro in colony-forming unit and long-term culture initiating cell assays, both in patient cells and in patient-derived xenograft (PDX) cells. Further, it completely prevented engraftment of AML PDX leukemia-initiating cells in NSG mice. 20D9h3-MMAF had a similar effect in engraftment assays, but a less prominent effect in colony assays. Both ADCs did not affect healthy stem and progenitor cells at comparable doses providing the rationale for FLT3 as therapeutic LSC target. Collectively, we show that FLT3-directed ADCs with DUBA or MMAF have potent activity against AML LSCs and represent promising candidates for further clinical development.

Impact of high-sensitivity flow cytometry on peri-transplant minimal residual disease kinetics in acute leukemia

Minimal residual disease (MRD) detected before hematopoietic cell transplantation (HCT) is associated with adverse outcomes in patients with high-risk acute leukemia. However, the ideal time points for post-transplant MRD assessment and the clinical significance of low levels of residual disease in this context are unclear. We conducted a prospective real-world analysis of high-sensitivity flow cytometry MRD performed before and after transplant (at days 30, 60 and 100) in 77 acute leukemia patients. The aim was to evaluate the kinetics of disease elimination and correlate it with transplant outcomes. Pre-transplant MRD was negative in 42 (MRD-) and positive in 35 patients (MRD+). Post-transplant MRD assessment was feasible at day 30 (n = 30, 38.9%), day 60 (n = 27, 35.0%) and day 100 (n = 60, 77.9%). Relapses occurred in 8 patients in the MRD + group (22.9%) and three in the MRD-negative group (7.1%), p = 0.02. Pre-transplant MRD correlated with a decrease in overall survival (OS; 87.9% MRD- vs. 54.0% MRD+) and event-free survival (EFS; 85.3% MRD- vs. 51.1% MRD+), p = 0.001. Cumulative incidence of relapse (CIR) was 17.5% in MRD + vs. 2.6% in MRD- (p = 0.049). Non-relapse mortality (NRM) was 31.4% in MRD + vs. 12.1% in MRD- (p = 0.019). One-year OS was higher in patients with negative MRD at d100 (92.4%, 95% CI: 0.81-0.971) than positive d100 MRD (53.3%, 95% CI: 0.177-0.796), p < 0.0001. Disease status and d100 MRD were associated with OS, EFS and CIR. Differences in NRM between leukemia types (ALL: 18.9% MRD- vs. 50% MRD+, and AML 0% MRD- vs. 21.7% MRD+, p = 0.0158) were also observed. In conclusion, pre-transplant MRD assessed by highly sensitive flow cytometry accurately identified patients with adverse prognoses. Persistent MRD after HCT could predict relapse with high specificity and clinical sensitivity. These results highlight the importance of incorporating peri-transplant MRD kinetics into the routine treatment of acute leukemia, particularly in low/middle-income countries.

Impact of measurable residual disease clearance kinetics in patients with AML undergoing intensive chemotherapy

ABSTRACT

The prognostic impact of measurable residual disease (MRD) in acute myeloid leukemia (AML) is unequivocal; however, the optimal time point for achieving undetectable MRD is unclear. We retrospectively studied patients with newly diagnosed (ND) AML who achieved remission with frontline intensive chemotherapy and had MRD assessed by flow cytometry after induction (time point 1 [TP1]) and after cycles 2 or 3 (TP2). Cases were grouped into MRD negative (Neg)/Neg, positive (Pos)/Neg, or Pos/Pos at TP1 and TP2, respectively. Of 1980 patients with ND AML, 277 met the inclusion criteria and were included in this analysis. The median relapse-free survival (RFS) was 73 months, 22 months, and 5 months for the MRD Neg/Neg, Pos/Neg, and Pos/Pos groups, respectively (P < .01). There was a significant difference between the Neg/Neg and Pos/Neg groups (P = .05), suggesting benefit to early MRD negativity. The median overall survival (OS) was 81 months, 40 months, and 9 months, respectively (P < .01), but the difference between Neg/Neg and Pos/Neg was not statistically significant (P = .19). Landmark analysis demonstrated the benefit of stem cell transplant (SCT), particularly in Neg/Neg intermediate-risk AML (median RFS, not reached vs 15 months; P < .01). On multivariable analysis, MRD Pos/Neg was independently associated with a worse RFS than Neg/Neg (hazard ratio, 1.73; 95% confidence interval, 1.09-2.75; P = .02) but not for OS (P = .15). In conclusion, undetectable flow MRD after induction is associated with better RFS than undetectable MRD achieved later during consolidation. SCT benefited patients with intermediate-risk AML, regardless of MRD kinetics.

Significance of Measurable Residual Disease in Patients Undergoing Allogeneic Hematopoietic Cell Transplantation for Acute Myeloid Leukemia

Allogeneic hematopoietic cell transplantation (HCT) remains an important curative-intent treatment for many patients with acute myeloid leukemia (AML), but AML recurrence after allografting is common. Many factors associated with relapse after allogeneic HCT have been identified over the years. Central among these is measurable ("minimal") residual disease (MRD) as detected by multiparameter flow cytometry, quantitative polymerase chain reaction, and/or next-generation sequencing. Demonstration of a strong, independent prognostic role of pre- and early post-HCT MRD has raised hopes MRD could also serve as a predictive biomarker to inform treatment decision-making, with emerging data indicating the potential value to guide candidacy assessment for allografting as a post-remission treatment strategy, the selection of conditioning intensity, use of small molecule inhibitors as post-HCT maintenance therapy, and preemptive infusion of donor lymphocytes. Monitoring for leukemia recurrence after HCT and surrogacy for treatment response are other considerations for the clinical use of MRD data. In this review, we will outline the current landscape of MRD as a biomarker for patients with AML undergoing HCT and discuss areas of uncertainty and ongoing research.

Single-cell DNA sequencing reveals pervasive positive selection throughout preleukemic evolution

The representation of driver mutations in preleukemic hematopoietic stem cells (pHSCs) provides a window into the somatic evolution that precedes acute myeloid leukemia (AML). Here, we isolate pHSCs from the bone marrow of 16 patients diagnosed with AML and perform single-cell DNA sequencing on thousands of cells to reconstruct phylogenetic trees of the major driver clones in each patient. We develop a computational framework that can infer levels of positive selection operating during preleukemic evolution from the statistical properties of these phylogenetic trees. Combining these data with 67 previously published phylogenetic trees, we find that the highly variable structures of preleukemic trees emerge naturally from a simple model of somatic evolution with pervasive positive selection typically in the range of 9%-24% per year. At these levels of positive selection, we show that the identification of early multiple-mutant clones could be used to identify individuals at risk of future AML.

Measurable residual disease as predictor of post-day +100 relapses after allografting in adult AML

ABSTRACT

Measurable residual disease (MRD) by multiparametric flow cytometry (MFC) before allogeneic hematopoietic cell transplantation (HCT) identifies patients at high risk of acute myeloid leukemia (AML) relapse, often occurring early after allografting. To examine the role of MFC MRD testing to predict later relapses, we examined 935 adults with AML or myelodysplastic neoplasm/AML transplanted in first or second morphologic remission who underwent bone marrow restaging studies between day 70 and 100 after HCT and were alive and without relapse by day +100. Of 935 adults, 136 (15%) had MRD before HCT, whereas only 11 (1%) had MRD at day +70 to +100. In day +100 landmark analyses, pre-HCT and day +70 to +100 MFC MRD were both associated with relapse (both P < .001), relapse-free survival (RFS; both P < .001) overall survival (OS; both P < .001), and, for post-HCT MRD, nonrelapse mortality (P = .001) after multivariable adjustment. Importantly, although 126/136 patients (92%) with MRD before HCT tested negative for MRD at day +70 to +100, their outcomes were inferior to those without MRD before HCT and at day +70 to +100, with 3-year relapse risk of 40% vs 15% (P < .001), 3-year RFS of 50% vs 72% (P < .001), and 3-year OS of 56% vs 76% (P < .001), whereas 3-year nonrelapse mortality estimates were similar (P = .53). Thus, despite high MRD conversion rates, outcomes MRD positive/MRD negative (MRDneg) patients are inferior to those of MRDneg/MRDneg patients, suggesting all patients with pre-HCT MRD should be considered for preemptive therapies after allografting.

Cell Marker Accordion: interpretable single-cell and spatial omics annotation in health and disease

Single-cell technologies offer a unique opportunity to explore cellular heterogeneity in health and disease. However, reliable identification of cell types and states represents a bottleneck. Available databases and analysis tools employ dissimilar markers, leading to inconsistent annotations and poor interpretability. Furthermore, current tools focus mostly on physiological cell types, limiting their applicability to disease. We developed the Cell Marker Accordion, a user-friendly platform providing automatic annotation and unmatched biological interpretation of single-cell populations, based on consistency weighted markers. We validated our approach on multiple single-cell and spatial datasets from different human and murine tissues, improving annotation accuracy in all cases. Moreover, we show that the Cell Marker Accordion can identify disease-critical cells and pathological processes, extracting potential biomarkers in a wide variety of disease contexts. The breadth of these applications elevates the Cell Marker Accordion as a fast, flexible, faithful and standardized tool to annotate and interpret single-cell and spatial populations in studying physiology and disease.

Allogeneic Hemopoietic Cell Transplantation as a Paradigm for Cellular Immunotherapy

BACKGROUND

Allogeneic hematopoietic cell transplantation (alloHCT) is an established curative treatment for hematological malignancies and other severe blood disorders. However, alloHCT is also known for its significant side effects.

SUMMARY

Here we review recent advances in targeted molecular therapy, immunotherapy, infectiology, and diagnostics that have enhanced the tolerability and efficacy of alloHCT, expanding its use to less fit and elderly patients. We analyze developments in conditioning regimens, donor selection, and the management of graft versus host disease (GVHD) and infections and discuss posttransplantation strategies to prevent relapse.

KEY MESSAGE

In a fresh perspective, alloHCT can serve as a platform to enhance the potential of emerging targeted and immune therapies.

Molecular measurable residual disease monitoring and transplant indications in NPM1 mutated acute myeloid leukemia

NPM1 mutated acute myeloid leukemia (AML) comprises roughly 30% of all AML cases and is mainly classified as favorable or intermediate-risk according to the European Leukemia Net stratification. Some patients, however, either have a poor response to initial intensive chemotherapy or ultimately relapse. NPM1 mutations are common, generally stable at early relapse and AML specific, features which make them ideal targets for measurable residual disease (MRD) monitoring. MRD monitoring via molecular analysis during the course of treatment can inform the role of allogeneic stem cell transplantation (HCT) in first remission in patients with NPM1 mutated AML with high-risk co-occurring mutations, particularly FLT3-ITD, and in favorable risk patients who do not achieve defined molecular milestones. In this review, we evaluate the prognostic role of MRD monitoring in NPM1 mutated AML and its use as a predictive biomarker to refine risk stratification and inform decision making regarding treatment. We explore the impact of pre-HCT MRD positivity on post-HCT outcomes in this AML subset, and how HCT-related factors such as conditioning intensity may influence this risk.

Molecular measurable residual disease before transplantation independently predicts survival and relapse risk in adult lysine methyltransferase 2a-rearranged acute myeloid leukemia

BACKGROUND

Patients with lysine methyltransferase 2a (KMT2A)-rearranged (KMT2A-r) acute myeloid leukemia (AML) are assigned to intermediate-risk and adverse-risk categories at diagnosis. However, the value of molecular measurable residual disease (MRD) status in patients who have KMT2A-r AML before allogeneic hematopoietic stem cell transplantation (allo-HSCT) in adult cohorts has rarely been evaluated.

METHODS

Patients with KMT2A-r AML who achieved complete remission and subsequently underwent allo-HSCT between January 2015 and January 2023 were included in this analysis. Real-time quantitative polymerase chain reaction was used to detect molecular MRD in bone marrow samples. The end points were overall survival (OS), leukemia-free survival (LFS), the cumulative incidence of relapse (CIR), and nonrelapse mortality (NRM).

RESULTS

Pretransplantation molecular MRD was identified in 52 of 125 patients (42%) with KMT2A-r AML. The presence of KMT2A-r MRD was associated with inferior 3-year OS (51% vs. 82%; p < .001), LFS (42% vs. 81%; p < .001), CIR (33% vs. 12%; p < .001), and NRM (11% vs. 5%; p = .12). In multivariate models, molecular MRD status before transplantation independently predicted OS, LFS, and CIR. The survival of adult patients with KMT2A-r AML was heterogeneous, depending on the KMT2A translocation partners, and was more favorable in patients who had t(9;11) and t(10;11) than in those who had t(11;19) and t(6;11). In addition, flow cytometry-based MRD analysis conferred no additional prognostic value to the results of molecular MRD status.

CONCLUSIONS

Residual KMT2A-r before allo-HSCT independently predicts the risk of survival and relapse, and donor lymphocyte infusion or posttransplantation maintenance therapies should be considered for patients who have AML with detectable molecular MRD.

New practice of BCR::ABL1 standardization system based on p210 and p190 BCR::ABL1 reference materials

Quantification of BCR::ABL1 monitors minimal residual disease, thus critical for patient stratification. While significant progress has been made in enhancing the accuracy of p210 BCR::ABL1 quantification, no equivalent standardization has been conducted for p190 BCR::ABL1. Therefore, we developed p190 BCR::ABL1 reference materials to calibrate the quantitative process through an innovative plasmid-based calibration strategy. Then, we further explored the use of p190 and p210 reference materials to standardize tests in 159 laboratories across China and assessed their detection capability utilizing quality assessment samples. Results suggested that after calibration, the coefficient of variation of detection results decreased from 50.8 %-57.4 % to 24.9 %-36.4 % for p190, and from 37.6 %-49.0 % to 19.1 %-28.5 % for p210. The percentage of laboratories within ± 2-fold of the target values increased from 77.1 %, 76.4 %, 73.2 %, and 74.5 % to 94.3 %, 95.5 %, 92.4 %, and 91.1 % for p190 samples 2023S21-2023S24, and from 72.3 %, 86.2 %, 79.2 %, and 81.1 % to 98.1 %, 99.4 %, 98.1 %, and 96.2 % for p210 samples 2023S11-2023S14. Overall, our study successfully developed and employed p190 and p210 reference materials to promote accuracy and comparability of BCR::ABL1 quantification among laboratories.

Midostaurin added to 10-day decitabine, for patients unfit for intensive chemotherapy with AML and higher risk MDS, irrespective of FLT3 mutational status, does not improve outcome

The treatment of older patients with acute myeloid leukemia (AML) considered unfit for receiving intensive chemotherapy is challenging. Based on the hypothesis that addition of the broad tyrosine kinase inhibitor (TKI) midostaurin could improve the response to hypomethylating agents, irrespective of FLT3 gene mutational status, we conducted a randomized phase II multicenter study to assess the tolerability and efficacy of the addition of midostaurin to a 10-day schedule of decitabine in unfit (i.e. Hematopoietic Cell Transplantation Comorbidity Index (HCT-CI) ≥ 3) AML and higher risk myelodysplasia (MDS) patients (HOVON155 trial). In total, 140 eligible patients were randomly (1:1) assigned to treatment with 10-days of decitabine alone (N = 70) or combined with midostaurin (50 mg bid;starting the day following the last dose of decitabine), (N = 70). Addition of midostaurin was well tolerated and the number of AEs was comparable for both treatment arms. Early death rates (< 30 days) were similar as well (10%). In the decitabine plus midostaurin arm 24% reached CR/CRi, the median OS was 4.8 months and 1-yrs OS was 31% which compared with 34% CR/CRi, median OS of 7.4 months and 1-yrs OS of 37% for the decitabine alone group (NS). Thus, while the addition of midostaurin appears safe, it does not enhance therapeutic efficacy of decitabine in unfit AML patients.

Molecular techniques in haematopathology: what and how?

Here we review the 'what and how' of molecular techniques used in the context of haematopathological diagnostics of both lymphoid and myeloid neoplasms. Keeping in mind that the required resources for molecular testing are not universally available, we will not only discuss novel and emerging techniques that allow more high-throughput and sophisticated analyses of lymphoid and myeloid neoplasms, but also the more classical, low-cost alternatives and even some workarounds for molecular testing approaches. In this review we also address other key aspects around molecular techniques for haematopatholgy diagnostics, including preanalytics, data interpretation, and data management, bioinformatics, and interlaboratory precision and performance evaluation.

Pre-emptive therapeutic decisions based on measurable residual disease status in acute myeloid leukemia: ready for prime time?

The use of measurable residual disease (MRD) as a biomarker for prognostication, risk stratification, and therapeutic decision-making in acute myeloid leukemia (AML) is gaining prominence. MRD monitoring for NPM1-mutated and core-binding factor AML using PCR techniques is well-established for assessing disease after intensive chemotherapy. AML with persistent FLT3-ITD MRD post-intensive chemotherapy and pre-allogeneic hematopoietic cell transplantation (pre-allo-HCT) is associated with an increased risk of relapse and lower survival. Pre-allo-HCT MRD is an independent risk factor for post-allo-HCT outcomes, including relapse and death. Therefore, preemptive interventions on the natural history of MRD positivity are an active area of research beyond its initial prognostic function. Targeting MRD in AML with innovative treatment strategies can improve patient outcomes.

Acute myeloid leukemia management and research in 2025

The first 5 decades of research in acute myeloid leukemia (AML) were dominated by the cytarabine plus anthracyclines backbone, with advances in strategies including allogeneic hematopoietic stem cell transplantation, high-dose cytarabine, supportive care measures, and targeted therapies for the subset of patients with acute promyelocytic leukemia. Since 2017, a turning point in AML research, 12 agents have received regulatory approval for AML in the United States: venetoclax (BCL2 inhibitor); gemtuzumab ozogamicin (CD33 antibody-drug conjugate); midostaurin, gilteritinib, and quizartinib (fms-like tyrosine kinase 3 inhibitors); ivosidenib, olutasidenib, and enasidenib (isocitrate dehydrogenase 1 and 2 inhibitors); oral azacitidine (a partially absorbable formulation); CPX351 (liposomal encapsulation of cytarabine:daunorubicin at a molar ratio of 5:1); glasdegib (hedgehog inhibitor); and recently revumenib (menin inhibitor; approved November 2024). Oral decitabine-cedazuridine, which is approved as a bioequivalent alternative to parenteral hypomethylating agents in myelodysplastic syndrome, can be used for the same purpose in AML. Menin inhibitors, CD123 antibody-drug conjugates, and other antibodies targeting CD123, CD33, and other surface markers are showing promising results. Herein, the authors review the frontline and later line therapies in AML and discuss important research directions.

A phase 2, multicenter, clinical trial of CPX-351 in older patients with secondary or high-risk acute myeloid leukemia: PETHEMA-LAMVYX

BACKGROUND

LAMVYX was a multicenter, single-arm, phase 2 trial designed to validate the safety and efficacy of CPX-351 in patients aged 60-75 years with newly diagnosed, secondary acute myeloid leukemia and to generate evidence on key issues not addressed in the preceding regulatory pivotal trial.

METHODS

The primary end point of the study was the complete remission (CR)/CR with incomplete hematologic recovery (CRi) rate after induction. Eligible patients were recommended to undergo allogeneic hematopoietic stem cell transplantation after the first consolidation cycle. Alternatively, patients could undergo up to six maintenance cycles with CPX-351.

RESULTS

Twenty-nine patients (49%; 95% exact confidence interval [CI], 37%-62%) patients achieved a CR/CRi after one or two cycles of induction, with a measurable residual disease negativity rate of 67% as assessed by centralized, multiparameter flow cytometry. Among patients who had serial next-generation sequencing analyses available, clearance of somatic mutations that were present at diagnosis was achieved in 7 (35%). The median follow-up among survivors was 16.8 months (range, 8.7-24.3 months). The median event-free survival was 3.0 months (95% CI, 1.4-7.3 months), and the median overall survival was 7.4 months (95% CI, 3.7-12.7 months). In landmark analyses at day +100 from diagnosis, the 1-year overall and event-free survival rate among patients who underwent allogeneic hematopoietic stem cell transplantation was 70% (95% CI, 47%-100%) and 70% (95% CI, 47%-100%), respectively. The corresponding values were 89% (95% CI, 71%-100%) and 44% (95% CI, 21%-92%), respectively, for patients who entered the maintenance phase. No significant longitudinal changes were observed in severity index or quality-of-life visual analog scale scores.

CONCLUSIONS

The current data provide novel insights that might inform the clinical positioning and optimal use of CPX-351, complementing previous results (ClinicalTrials.gov identifier NCT04230239).

Prognostic impact of TET2 mutations in patients with acute myeloid leukemia: HM-SCREEN-Japan 01 and 02 study

Ten-eleven translocation-2 (TET2) gene mutations are observed in 12-20% of adult patients with acute myeloid leukemia (AML). The prognostic impact of TET2 mutations in patients with AML and myelodysplastic syndromes has been reported in several studies; however, their results remain controversial. Therefore, we aimed to analyze the prevalence and significance of TET2 mutations in patients with AML. Data were obtained from 331 patients with AML according to the Hematologic Malignancies-SCREEN-Japan 01 and 02 studies, which were prospective multicenter genomic profiling analyses. We found a distinct type of TET2 mutations, with a particularly detrimental prognosis in the patients. Thirty-five patients with TET2 'significant' mutations were identified (26 with frameshift mutations and nine with nonsense mutations). The proportion of patients with TET2 mutations was 31.7% (10.6% and 21.1% in the TET2 significant and non-significant mutation groups). The TET2 significant mutation group had a shorter OS than the TET2 non-significant mutation or wild-type TET2 group (median: 15.9 vs. 35.0 vs. 25.9 months). Regarding the response to chemotherapy according to TET2 status, the complete response (CR) or CR with incomplete count recovery rate was 37.1% in the TET2 significant mutation group and 46.6% in the non-significant mutation or wild-type group. Allogeneic hematopoietic stem cell transplantation (allo-HSCT) improved patient prognosis in the TET2 non-significant mutation or wild-type TET2 group; however, allo-HSCT did not affect prognosis in the TET2 significant mutation group. This study indicates that certain TET2 mutations in patients with AML may have detrimental effects.

The importance of targeted next-generation sequencing based genomic profiling in the diagnosis of childhood acute myeloid leukemia: a single center experience

BACKGROUND

The management of pediatric acute myeloid leukemia (AML) is based on the prognostic risk classification of initial leukemia. Targeted next-generation sequencing (NGS) is a reliable method used to identify recurrently mutated genes of pediatric AML and associated prognosis.

METHODS

In this study, we retrospectively evaluated the prognostic, and therapeutic utility of a targeted NGS panel covering twenty-five genes, in 21 children with de novo and 8 with relapsed or secondary AML.   Results. Variants were detected in 44.8% of patients, and 63.2% of them were in the signaling pathway genes. The number of variants per patient and diversity increased with age. The panel results affected hematopoietic stem cell transplantation decisions, especially in core binding factor AML, and allowed the categorization of diseases according to current classifications. Panel results also pointed out predisposition to germline leukemia to the extent of the panel coverage. No targeted therapy was used based on the variants, and none of the variants were used to monitor minimal residual disease.

CONCLUSIONS

Targeted NGS results, along with well-known genetic aberrations and treatment responses, can guide treatment modalities. The coverage of the routine panels should include proven mutations of childhood AML and germline leukemia predisposition genes.

Mutations and MRD: clinical implications of clonal ontogeny

Measurable residual disease (MRD) is a strong but imprecise predictor of relapse in acute myeloid leukemia. Many patients fall into the outlier categories of MRD positivity without relapse or MRD negativity with relapse. Why? We will discuss these states in the context of "clonal ontogeny" examining how mutations, clonal structure, and Darwinian rules impact response, resistance, and relapse.

Advancements in leukemia management: Bridging diagnosis, prognosis and nanotechnology (Review)

Leukemia is a cancer that starts in blood stem cells in the bone marrow. Today, the proper diagnosis and prognosis of leukemia are essential in mitigating the morbidity and mortality associated with this malignancy. The advent of novel biomarkers, particularly those related to minimal residual disease, has paved the way for personalized therapeutic strategies and enables the quantitative assessment of patient responses to treatment regimens. Novel diagnostic and targeted drug delivery may be helpful for the improved management of leukemia. Genetic clinical parameters, such as chromosomal abnormalities, are crucial in diagnosing and guiding treatment decisions. These genetic markers also provide valuable prognostic information, helping to predict patient outcomes and tailor personalized treatment plans. In the present review, the studies on the diagnostic and prognostic parameters of leukemia were analyzed. The prognosis of leukemia was investigated in most of the studies, and the remaining were performed on diagnosis. The clinical and laboratory prognostic parameters were the most common, followed by diagnostic hematological parameters, diagnostic blood parameter studies, and diagnostic immunological parameters. Clinical and laboratory prognostic and hematologic parameters were the most extensively studied. The methods used to diagnose and prognose the leukemia cases in these studies were predominantly clinical hematology. Numerous surface proteins and receptors, including CD45, CD27, CD29, CD38, CD27, CD123, CD56 and CD25, react similarly in various kinds of leukemia, which are ideal for targeted drug delivery. Drug delivery to leukemia cells encounters several significant obstacles, including heterogeneity, that hinder the effectiveness of treatment. Nanocarriers play a critical role in targeted drug delivery for leukemia by enhancing the precision of treatments directed at surface proteins and receptors. Additionally, they can be functionalized with targeting drugs and antibodies to target specific tissues and cells.

Detection methods and prognosis implications of measurable residual disease in acute myeloid leukemia

Measurable residual disease (MRD) in acute myeloid leukemia (AML) refers to the quantity of residual leukemic cells in a patient after treatment.According to the latest agreements, MRD in AML offering essential prognostic insights. However, there is ongoing debate regarding MRD-based monitoring and treatment strategies. There are multiple platforms for detecting MRD, each varying in sensitivity and suitability for different patients. MRD not only predicts treatment outcomes but also serves as an indicator of treatment effectiveness and a prognostic biomarker. In AML, most retrospective studies indicate that patients who are MRD-positive or show increasing MRD levels at specific time points during remission have significantly higher risks of relapse and mortality compared to MRD-negative patients. Although achieving MRD-negative status can improve patient prognosis, the possibility of relapse remains. Despite the correlation between MRD and clinical outcomes, MRD assessment methods are not yet standardized, leading to discrepancies in results across different techniques. To provide reliable MRD results, it is essential to optimize and standardize MRD detection methods. Methods for assessing MRD include multiparameter flow cytometry (MFC) and molecular assays, chosen based on disease characteristics. This review focuses on currently available MRD detection methods and discusses how the prognostic value of MRD test results informs personalized treatment strategies for AML patients.

Optimization criteria for ordering myeloid neoplasm next-generation sequencing

Introduction

Myeloid neoplasms (MNs) frequently harbor pathogenic mutations not detected by karyotyping and fluorescence in situ hybridization; hence, next-generation sequencing (NGS) is necessary for diagnosis, risk stratification, and therapy. If, however, NGS is not clinically indicated but still performed, the results may promote futile avenues of investigation, heighten patient distress, and increase cost.

Methods

We created criteria to approve NGS testing for MN (MN-NGS) with the goal of maximizing actionable results. These actionable results include making a new MN diagnosis, characterizing a MN with baseline mutational status, and altering treatment plans. Approval criteria included clinical suspicion of new, relapsed, or worsening disease and end-of-induction chemotherapy. Cancellation criteria included the suspicion of non-myeloid disease only, no suspicion of progression of a known MN, no evidence for recurrence post-transplant, a diagnosis of chronic myeloid leukemia, and cases using blood when a concurrent bone marrow NGS is being performed. We applied these criteria to NGS tests ordered at our institution between August and December 2018 and determined whether any tests meeting our cancelation criteria yielded actionable results.

Results

Consecutive MN-NGS orders (n = 174) were retrospectively categorized as appropriate (Group A, n = 115), inappropriate (Group B, n = 29), and appropriately canceled (group C, n = 30). Seventy-five of the 115 (65%) Group A tests and none of the 29 (0%) Group B tests yielded actionable results (p < 0.0001).

Conclusion

Approximately one third (59/174) of MN-NGS test orders can be safely canceled using these criteria, which would result in $150,370 of Centers for Medicare and Medicaid Services-reimbursed savings annually.

Risk Stratification in Older Intensively Treated Patients With AML

PURPOSE

AML is a genetically heterogeneous disease, particularly in older patients. In patients older than 60 years, survival rates are variable after the most important curative approach, intensive chemotherapy followed by allogeneic hematopoietic cell transplantation (allo-HCT). Thus, there is an urgent need in clinical practice for a prognostic model to identify older patients with AML who benefit from curative treatment.

METHODS

We studied 1,910 intensively treated patients older than 60 years with AML and high-risk myelodysplastic syndrome (HR-MDS) from two cohorts (NCRI-AML18 and HOVON-SAKK). The median patient age was 67 years. Using a random survival forest, clinical, molecular, and cytogenetic variables were evaluated in an AML development cohort (n = 1,204) for association with overall survival (OS). Relative weights of selected variables determined the prognostic model, which was validated in AML (n = 491) and HR-MDS cohorts (n = 215).

RESULTS

The complete cohort had a high frequency of poor-risk features, including 2022 European LeukemiaNet adverse-risk (57.3%), mutated TP53 (14.4%), and myelodysplasia-related genetic features (65.1%). Nine variables were used to construct four groups with highly distinct 4-year OS in the (1) AML development, (2) AML validation, and (3) HR-MDS test cohorts ([1] favorable: 54% ± 4%, intermediate: 38% ± 2%, poor: 21% ± 2%, very poor: 4% ± 1%; [2] 54% ± 9%, 43% ± 4%, 27% ± 4%, 4% ± 3%; and [3] 54% ± 10%, 33% ± 6%, 14% ± 5%, 0% ± 3%, respectively). This new AML60+ classification improves current prognostic classifications. Importantly, patients within the AML60+ intermediate- and very poor-risk group significantly benefited from allo-HCT, whereas the poor-risk patients showed an indication, albeit nonsignificant, for improved outcome after allo-HCT.

CONCLUSION

The new AML60+ classification provides prognostic information for intensively treated patients 60 years and older with AML and HR-MDS and identifies patients who benefit from intensive chemotherapy and allo-HCT.

Inhibition of TGF-β signaling in bone marrow endothelial cells promotes hematopoietic recovery in acute myeloid leukemia patients

Although it is an effective treatment for acute myeloid leukemia (AML), chemotherapy leads to myelosuppression and poor hematopoietic reconstruction. Hematopoiesis is regulated by bone marrow (BM) endothelial cells (ECs), and BM ECs are dysfunctional in acute leukemia patients with poor hematopoietic reconstitution after allogenic hematopoietic stem cell transplantation. Thus, it is crucial to explore the underlying mechanism of EC impairment and establish strategies for targeted therapy. TGF-β signaling was found to be upregulated in ECs from AML patients in complete remission (CR ECs) and led to CR EC damage. Administration of a TGF-β inhibitor rescued the dysfunction of ECs caused by TGF-β1 expression in vitro, especially their hematopoiesis-supporting ability. Moreover, inhibition of TGF-β expression repaired the BM EC damage triggered by chemotherapy in both AML patients in vitro and in an AML-CR murine model, and restored normal hematopoiesis without promoting AML progression. Mechanistically, our data reveal alterations in the transcriptomic pattern of damaged BM ECs, accompanied by the overexpression of downstream molecules TGF-βR1, pSmad2/3, and functional genes related to adhesion, angiogenesis suppression and pro-apoptosis. Collectively, our findings reveal for the first time that the activation of TGF-β signaling leads to BM EC dysfunction and poor hematopoietic reconstitution. Targeting TGF-β represents a potential therapeutic strategy to promote multilineage hematopoiesis, thereby benefiting more cancer patients who suffer from myelosuppression after chemotherapy.

Tracing Quiescent Cancer Cells In Vivo

QCCs have long gained significant interest as potential "seeds" for recurrent cancers. Clinical evidence suggests that a subset of cancer cells exits the cell cycle and enters a quiescent state following anti-cancer treatment. These microscopic-residual QCCs are extremely challenging to trace and detect within patients. Additionally, QCCs resist conventional anti-cancer therapies due to the lack of cell activity. Notably, upon the unknown environmental cues in unknown time points, sometimes decades later, QCCs can reactivate, triggering cancer relapse at primary or secondary sites. Currently, no targeted therapies or diagnostic tools exist for QCCs, and their molecular regulatory mechanisms remain largely unknown. The major challenge in understanding QCCs lies in the limited availability of human-relevant pre-clinical models that trace and collect QCCs in vivo. This review provides an overview of existing QCC tracing systems and analyzes their limitations. It also cautiously proposes potential improvements for tracing QCCs in vivo based on recent advancements in QCC studies and lineage-tracing techniques. Developing human-relevant and easily accessible in vivo tracing systems will be a crucial step in advancing QCC diagnostics and therapeutic strategies.

Longitudinal ultra-sensitive mutation burden sequencing for precise minimal residual disease assessment in AML

Relapse is one of the major challenges in clinical treatment of acute myeloid leukemia (AML). Though minimal residual disease (MRD) monitoring plays a crucial role in quantitative assessment of the disease, molecular MRD analysis has been mainly limited to patients diagnosed with gene fusions and NPM1 mutations. Here, we report a longitudinal ultra-sensitive mutation burden (UMB) monitoring strategy for accurate MRD analysis in AML patients regardless of genetic abnormality types. Using a Quantitative Blocker Displacement Amplification (QBDA) sequencing panel with limit of detection below 0.01% variant allele frequency (VAF), a hazard ratio of 14.8 (p < 0.001) is observed in cumulative incidence of relapse analysis of 20 patients with ≥ 2 samples during complete remission (CR). The ROC area under curve (AUC) is 0.98 when predicting relapse within 30 weeks of CR timepoint 2 (N = 20). Furthermore, we demonstrate quantitating VAF below 0.01% is essential for accurate relapse prediction.

TET2 mutation in acute myeloid leukemia: biology, clinical significance, and therapeutic insights

TET2 is a critical gene that regulates DNA methylation, encoding a dioxygenase protein that plays a vital role in the regulation of genomic methylation and other epigenetic modifications, as well as in hematopoiesis. Mutations in TET2 are present in 7%-28% of adult acute myeloid leukemia (AML) patients. Despite this, the precise mechanisms by which TET2 mutations contribute to malignant transformation and how these insights can be leveraged to enhance treatment strategies for AML patients with TET2 mutations remain unclear. In this review, we provide an overview of the functions of TET2, the effects of its mutations, its role in clonal hematopoiesis, and the possible mechanisms of leukemogenesis. Additionally, we explore the mutational landscape across different AML subtypes and present recent promising preclinical research findings.

Epitope prime editing shields hematopoietic cells from CD123 immunotherapy for acute myeloid leukemia

Acute myeloid leukemia (AML) is a malignant cancer characterized by abnormal differentiation of hematopoietic stem and progenitor cells (HSPCs). While chimeric antigen receptor T (CAR-T) cell immunotherapies target AML cells, they often induce severe on-target/off-tumor toxicity by attacking normal cells expressing the same antigen. Here, we used base editors (BEs) and a prime editor (PE) to modify the epitope of CD123 on HSPCs, protecting healthy cells from CAR-T-induced cytotoxicity while maintaining their normal function. Although BE effectively edits epitopes, complex bystander products are a concern. To enhance precision, we optimized prime editing, increasing the editing efficiency from 5.9% to 78.9% in HSPCs. Epitope-modified cells were resistant to CAR-T lysis while retaining normal differentiation and function. Furthermore, BE- or PE-edited HSPCs infused into humanized mice endowed myeloid lineages with selective resistance to CAR-T immunotherapy, demonstrating a proof-of-concept strategy for treating relapsed AML.

Measurable residual disease (MRD)-testing in haematological cancers: A giant leap forward or sideways?

Measurable residual disease (MRD)-testing is used in many haematological cancers to estimate relapse risk and to direct therapy. Sometimes MRD-test results are used for regulatory approval. However, some people including regulators wrongfully believe results of MRD-testing are highly accurate and of proven efficacy in directing therapy. We review MRD-testing technologies and evaluate the accuracy of MRD-testing for predicting relapse and the strength of evidence supporting efficacy of MRD-guided therapy. We show that at the individual level MRD-test results are often an inaccurate relapse predictor. Also, no convincing data indicate that increasing therapy-intensity based on a positive MRD-test reduces relapse risk or improves survival. We caution against adjusting therapy-intensity based solely on results of MRD-testing.

Indeterminate measurable residual disease by multiparameter flow cytometry is associated with an intermediate risk of clinical relapse in adult patients with acute leukaemia

Measurable residual disease (MRD) is useful for prognostication and for monitoring response to treatment in patients with acute leukaemia. MRD by multiparametric flow cytometry (MFC-MRD) utilises the leukaemia-associated immunophenotype (LAIP) and difference from normal (DfN) strategies to identify the leukaemic clone. Difficulties arise when the LAIP overlaps with normal regeneration, there is clonal evolution, or when the abnormal clone population is exceptionally small e.g., <0.01% of CD45+ cells. Such cases are reported as 'indeterminate'; however, there is little international consensus on this reporting. The relationship between clinical outcomes and indeterminate MFC-MRD is unknown. Here we determine the rate of indeterminate MFC-MRD reporting, its relationship to concurrent molecular MRD results when available, and to clinical outcomes to 12 months. We performed an internal audit of all adult testing for MFC-MRD between January and December 2021. A total of 153 consecutive patients with a diagnosis of acute leukaemia were included. Successive MFC-MRD results and clinical outcomes were recorded over a 12-month period from time of inclusion into the study. In total, 460 MFC-MRD tests from 153 patients were reviewed and 73 (16%) MFC-MRD tests from 54 (35%) patients were reported as indeterminate. The majority (70%) were at low levels between 0.01-0.1% of CD45+ cells. Compared to patients with a negative result, acute myeloid leukaemia (AML) was more frequent in patients who had an indeterminate MFC-MRD (70% vs 36%), and B-cell acute lymphoblastic leukaemia was less common (20% vs 55%). In patients with indeterminate MFC-MRD results, one-third had received either chemotherapy or allogeneic haemopoietic stem cell transplant (aHSCT) within the preceding 3 months. Agreement between MFC and molecular MRD testing was low. Patients with indeterminate MFC-MRD had leukaemia relapse rates below patients with a positive MFC-MRD, but greater than those with negative MFC-MRD (positive 33% vs indeterminate 21% vs negative 8%, p = 0.038). Overall, these findings indicate that indeterminate MFC-MRD results are more common in adults with AML and also in those who have received chemotherapy or aHSCT within the previous 3 months. We report for the first time that indeterminate MFC-MRD is a finding of potential clinical significance, which associates with a numerically higher median relapse rate within 12 months when compared to a negative MFC-MRD result.

Current status and research directions in acute myeloid leukemia

The understanding of the molecular pathobiology of acute myeloid leukemia (AML) has spurred the identification of therapeutic targets and the development of corresponding novel targeted therapies. Since 2017, twelve agents have been approved for the treatment of AML subsets: the BCL2 inhibitor venetoclax; the CD33 antibody drug conjugate gemtuzumab ozogamicin; three FLT3 inhibitors (midostaurin, gilteritinib, quizartinib); three IDH inhibitors (ivosidenib and olutasidenib targeting IDH1 mutations; enasidenib targeting IDH2 mutations); two oral hypomethylating agents (oral poorly absorbable azacitidine; fully absorbable decitabine-cedazuridine [latter approved as an alternative to parenteral hypomethylating agents in myelodysplastic syndrome and chronic myelomonocytic leukemia but commonly used in AML]); and CPX-351 (encapsulated liposomal 5:1 molar ratio of cytarabine and daunorubicin), and glasdegib (hedgehog inhibitor). Other targeted therapies (menin inhibitors, CD123 antibody-drug conjugates) are showing promising results. To achieve optimal results in such a rare and heterogeneous entity as AML requires expertise, familiarity with this rare cancer, and the access to, and delivery of disparate therapies under rigorous supportive care conditions. In this review, we update the standard-of-care and investigational therapies and outline promising current and future research directions.

Prognostic impact of DTA mutation and co-occurring mutations in patients with myelodysplastic syndrome

OBJECTIVE

To evaluate the frequency and prognostic significance of DTA (DNMT3A、TET2、ASXL1) gene mutation and co-occurring mutations in patients with myelodysplastic syndrome (MDS).

METHODS

The clinical data of 102 newly diagnosed MDS patients who accepted Next Generation Sequencing (NGS) was retrospectively analyzed. According to whether the patients had DTA gene mutation, the patients were divided into DTA mutated (DTA-mut) group and wild type (DTA-wt) group, and the relationship between gene mutation and clinical characteristics and prognosis was analyzed.

RESULTS

Among the 102 MDS patients, 96% (98/102) presented with mutation, while the mean number of mutations was 3.04 mutations/patient. DTA-mut was detected in 56.9% (58/102) patients. The most frequent co-mutated genes in DTA-mut group were SF3B1 (25.8%), RUNX1 (24.1%), U2AF1 (18.9%), SRSF2, EZH2, SETBP1 (17.2%), STAG2 (15.5%), IDH2 (12.1%) and BCOR, CBL (10.3%). The two groups showed no significant differences in ages, blood parameters, bone marrow blasts, WHO 2022 classification, IPSS-R risk category and rate of conversion to leukemia. Compared with the DTA-wt group, the mutation frequency of RUNX1 was higher (P = 0.02), while mutation frequency of TP53 was lower (P = 0.001) and the mutation frequency of ≥ 3 co-mutated genes was higher in DTA-mut group (P = 0.00). Survival analysis showed that the overall survivals (OS) of DTA-mut patients was significantly inferior to that of DTA-wt patients (P = 0.0332). According to IPSS-R classification, a statistically significant difference in OS was only observed in higher risk (IPSS-R > 3.5) group (P = 0.0058). In the context of DTA mutation, the OS of patients with RUNX1 mutation was shorter than that of patients without RUNX1 mutation significantly (P = 0.0074). The OS of patients with SF3B1 mutation was longer than that of patients without SF3B1 mutation, but there was no statistical difference (P = 0.0827). DTA mutations were not independent prognostic factors when DTA and co-mutated genes with frequency > 10% were considered in Cox regression model (P = 0.329). However, multivariate analysis confirmed an independently adverse prognosis of RUNX1 co-mutation (P = 0.042, HR = 2.426, 95% CI:1.031-5.711) in DTA-mut cohort. Moreover, our multivariable analysis suggests that SRSF2-mut was an independent poor prognostic factor for all MDS patients (P = 0.047), but lost significance (P = 0.103) for DTA-mut patients.

CONCLUSIONS

DTA mutations are frequently observed in patients with MDS, often accompanied by genes involved in RNA splicing and transcription factors like SF3B1 and RUNX1. DTA and concomitant mutations affect prognosis in MDS patients and RUNX1 was identified as an independent poor prognostic factor in patients with DTA mutations.

Flow Cytometric Assessment of Malignant Hematologic Disorders

Multiparameter flow cytometry (MPF) is an essential component of the diagnostic workup of hematologic malignancies. Recently developed tools have expanded the utility of MPF in detecting T-cell clonality and myelomonocytic dysplasia. Minimal/measurable residual disease analysis has long been established as critical in the management of B-lymphoblastic leukemia and is emerging as a useful tool in myeloid malignancies. With the continued increased complexity of MPF assays, emerging tools for data collection and analysis will allow users to take full advantage of MPF in the diagnosis of hematologic disease.