Novel prognostic subgroups in childhood 11q23/MLL-rearranged acute myeloid leukemia: results of an international retrospective study

Clinicopathologic features and outcomes of acute leukemia harboring PICALM::MLLT10 fusion

The PICALM::MLLT10 fusion is a rare but recurrent cytogenetic abnormality in acute leukemia, with limited clinicopathologic and outcome data available. Herein, we analyzed 156 acute leukemia patients with PICALM::MLLT10 fusion, including 12 patients from our institutions and 144 patients from the literature. The PICALM::MLLT10 fusion preferentially manifested in pediatric and young adult patients, with a median age of 24 years. T-lymphoblastic leukemia/lymphoma (T-ALL) constituted 65% of cases, acute myeloid leukemia (AML) 27%, and acute leukemia of ambiguous lineage (ALAL) 8%. About half of T-ALL were classified as an early T-precursor (ETP)-ALL. In our institutions' cohort, mediastinum was the most common extramedullary site of involvement. Eight of 12 patients were diagnosed with T-ALL exhibiting a pro-/pre-T stage phenotype (CD4/CD8-double negative, CD7-positive), and frequent CD79a expression. NGS revealed pathogenic mutations in 5 of 6 tested cases, including NOTCH1, and genes in RAS and JAK-STAT pathways and epigenetic modifiers. Of 138 cases with follow-up, pediatric patients (<18 years) had 5-year overall survival (OS) of 71%, significantly better than adults at 33%. The 5-year OS for AML patients was 25%, notably shorter than T-ALL patients at 54%; this distinction was observed in both pediatric and adult populations. Furthermore, adult but not pediatric ETP-ALL patients demonstrated inferior survival compared to non-ETP-ALL patients. Neither karyotype complexity nor transplant status had a discernible impact on OS. In conclusion, PICALM::MLLT10 fusion is most commonly seen in T-ALL patients, particularly those with an ETP phenotype. AML and adult ETP-ALL patients had adverse prognosis. PICALM::MLTT10 fusion testing should be considered in T-ALL, AML, and ALAL patients.

Rearrangements involving 11q23.3/KMT2A in adult AML: mutational landscape and prognostic implications - a HARMONY study

Balanced rearrangements involving the KMT2A gene (KMT2Ar) are recurrent genetic abnormalities in acute myeloid leukemia (AML), but there is lack of consensus regarding the prognostic impact of different fusion partners. Moreover, prognostic implications of gene mutations co-occurring with KMT2Ar are not established. From the HARMONY AML database 205 KMT2Ar adult patients were selected, 185 of whom had mutational information by a panel-based next-generation sequencing analysis. Overall survival (OS) was similar across the different translocations, including t(9;11)(p21.3;q23.3)/KMT2A::MLLT3 (p = 0.756). However, independent prognostic factors for OS in intensively treated patients were age >60 years (HR 2.1, p = 0.001), secondary AML (HR 2.2, p = 0.043), DNMT3A-mut (HR 2.1, p = 0.047) and KRAS-mut (HR 2.0, p = 0.005). In the subset of patients with de novo AML < 60 years, KRAS and TP53 were the prognostically most relevant mutated genes, as patients with a mutation of any of those two genes had a lower complete remission rate (50% vs 86%, p < 0.001) and inferior OS (median 7 vs 30 months, p < 0.001). Allogeneic hematopoietic stem cell transplantation in first complete remission was able to improve OS (p = 0.003). Our study highlights the importance of the mutational patterns in adult KMT2Ar AML and provides new insights into more accurate prognostic stratification of these patients.

Menin inhibitors in pediatric acute leukemia: a comprehensive review and recommendations to accelerate progress in collaboration with adult leukemia and the international community

Aberrant expression of HOX and MEIS1 family genes, as seen in KMT2A-rearranged, NUP98-rearranged, or NPM1-mutated leukemias leads to arrested differentiation and leukemia development. HOX family genes are essential gatekeepers of physiologic hematopoiesis, and their expression is regulated by the interaction between KMT2A and menin. Menin inhibitors block this interaction, downregulate the abnormal expression of MEIS1 and other transcription factors and thereby release the differentiation block. Menin inhibitors show significant clinical efficacy against KMT2A-rearranged and NPM1-mutated acute leukemias, with promising potential to address unmet needs in various pediatric leukemia subtypes. In this collaborative initiative, pediatric and adult hematologists/oncologists, and stem cell transplant physicians have united their expertise to explore the potential of menin inhibitors in pediatric leukemia treatment internationally. Our efforts aim to provide a comprehensive clinical overview of menin inhibitors, integrating preclinical evidence and insights from ongoing global clinical trials. Additionally, we propose future international, inclusive, and efficient clinical trial designs, integrating pediatric populations in adult trials, to ensure broad access to this promising therapy for all children and adolescents with menin-dependent leukemias.

Optimized cytogenetic risk-group stratification of KMT2A-rearranged pediatric acute myeloid leukemia

ABSTRACT

A comprehensive international consensus on the cytogenetic risk-group stratification of KMT2A-rearranged (KMT2A-r) pediatric acute myeloid leukemia (AML) is lacking. This retrospective (2005-2016) International Berlin-Frankfurt-Münster Study Group study on 1256 children with KMT2A-r AML aims to validate the prognostic value of established recurring KMT2A fusions and additional cytogenetic aberrations (ACAs) and to define additional, recurring KMT2A fusions and ACAs, evaluating their prognostic relevance. Compared with our previous study, 3 additional, recurring KMT2A-r groups were defined: Xq24/KMT2A::SEPT6, 1p32/KMT2A::EPS15, and 17q12/t(11;17)(q23;q12). Across 13 KMT2A-r groups, 5-year event-free survival probabilities varied significantly (21.8%-76.2%; P < .01). ACAs occurred in 46.8% of 1200 patients with complete karyotypes, correlating with inferior overall survival (56.8% vs 67.9%; P < .01). Multivariable analyses confirmed independent associations of 4q21/KMT2A::AFF1, 6q27/KMT2A::AFDN, 10p12/KMT2A::MLLT10, 10p11.2/KMT2A::ABI1, and 19p13.3/KMT2A::MLLT1 with adverse outcomes, but not those of 1q21/KMT2A::MLLT11 and trisomy 19 with favorable and adverse outcomes, respectively. Newly identified ACAs with independent adverse prognoses were monosomy 10, trisomies 1, 6, 16, and X, add(12p), and del(9q). Among patients with 9p22/KMT2A::MLLT3, the independent association of French-American-British-type M5 with favorable outcomes was confirmed, and those of trisomy 6 and measurable residual disease at end of induction with adverse outcomes were identified. We provide evidence to incorporate 5 adverse-risk KMT2A fusions into the cytogenetic risk-group stratification of KMT2A-r pediatric AML, to revise the favorable-risk classification of 1q21/KMT2A::MLLT11 to intermediate risk, and to refine the risk-stratification of 9p22/KMT2A::MLLT3 AML. Future studies should validate the associations between the newly identified ACAs and outcomes and unravel the underlying biological pathogenesis of KMT2A fusions and ACAs.

[SFCE harmonization workshops: Neonatal acute myeloid leukemia]

Neonatal acute myeloid leukemias (AML) occurred within the first 28 days of life and constitute only a small proportion of all AL. They are distinguished from leukemias of older children by their clinical presentation, which frequently includes cutaneous localizations ("blueberry muffin rash syndrome") and a leukocytosis above 50 ×109/L. This proliferation may be transient, causing a transient leukemoid reaction in a background of constitutional trisomy 21 ("Transient Abnormal Myelopoieseis" or TAM) or Infantile Myeloproliferative Disease in the absence of constitutional trisomy 21 ("Infantile Myeloproliferative Disease" or IMD). In cases of true neonatal AML, the prognosis of patients is poor. Overall survival is around 35 % in the largest historical series. This poor prognosis is mainly due to the period of onset of this pathology making the use of chemotherapy more limited and involving many considerations, both ethical and therapeutic. The objective of this work is to review this rare pathology by addressing the clinical, biological, therapeutic and ethical particularities of patients with true neonatal AML or transient leukemoid reactions occurring in a constitutional trisomy 21 (true TAM) or somatic background (IMD).

Structural variants involving MLLT10 fusion are associated with adverse outcomes in pediatric acute myeloid leukemia

ABSTRACT

MLLT10 gene rearrangements with KMT2A occur in pediatric acute myeloid leukemia (AML) and confer poor prognosis, but the prognostic impact of MLLT10 in partnership with other genes is unknown. We conducted a retrospective study with 2080 children and young adults with AML registered on the Children's Oncology Group AAML0531 (NCT00372593) and AAML1031 trials (NCT01371981). Transcriptome profiling and/or karyotyping were performed to identify leukemia-associated fusions associated with prognosis. Collectively, 127 patients (6.1%) were identified with MLLT10 fusions: 104 (81.9%) with KMT2A::MLLT10, 13 (10.2%) with PICALM::MLLT10, and 10 (7.9%) X::MLLT10: (2 each of DDX3X and TEC), with 6 partners (DDX3Y, CEP164, SCN2B, TREH, NAP1L1, and XPO1) observed in single patients. Patients with MLLT10 (n = 127) demonstrated adverse outcomes, with 5-year event-free survival (EFS) of 18.6% vs 49% in patients without MLLT10 (n = 1953, P < .001), inferior 5-year overall survival (OS) of 38.2% vs 65.7% (P ≤ .001), and a higher relapse risk of 76% vs 38.6% (P < .001). Patients with KMT2A::MLLT10 had an EFS from study entry of 19.5% vs 12.7% (P = .628), and an OS from study entry of 40.4% vs 27.6% (P = .361) in those with other MLLT10 fusion partners. Patients with PICALM::MLLT10 had an EFS of 9.2% vs 20% in other MLLT10- without PICALM (X::MLLT10; P = .788). Patients with PICALM::MLLT10 and X::MLLT10 fusions exhibit a DNA hypermethylation signature resembling NUP98::NSD1 fusions, whereas patients with KMT2A::MLLT10 bear aberrations primarily affecting distal regulatory elements. Regardless of the fusion partner, patients with AML harboring MLLT10 fusions exhibit very high-risk features and should be prioritized for alternative therapeutic interventions.

Cytogenetic abnormalities predict survival after allogeneic hematopoietic stem cell transplantation for pediatric acute myeloid leukemia: a PDWP/EBMT study

Poor-risk (PR) cytogenetic/molecular abnormalities generally direct pediatric patients with acute myeloid leukemia (AML) to allogeneic hematopoietic stem cell transplant (HSCT). We assessed the predictive value of cytogenetic risk classification at diagnosis with respect to post-HSCT outcomes in pediatric patients. Patients younger than 18 years at the time of their first allogeneic HSCT for AML in CR1 between 2005 and 2022 who were reported to the European Society for Blood and Marrow Transplantation registry were subgrouped into four categories. Of the 845 pediatric patients included in this study, 36% had an 11q23 abnormality, 24% had monosomy 7/del7q or monosomy 5/del5q, 24% had a complex or monosomal karyotype, and 16% had other PR cytogenetic abnormalities. In a multivariable model, 11q23 (hazard ratio [HR] = 0.66, P = 0.03) and other PR cytogenetic abnormalities (HR = 0.55, P = 0.02) were associated with significantly better overall survival when compared with monosomy 7/del7q or monosomy 5/del5q. Patients with other PR cytogenetic abnormalities had a lower risk of disease relapse after HSCT (HR = 0.49, P = 0.01) and, hence, better leukemia-free survival (HR = 0.55, P = 0.01). Therefore, we conclude that PR cytogenetic abnormalities at diagnosis predict overall survival after HSCT for AML in pediatric patients.

Panel-based RNA fusion sequencing improves diagnostics of pediatric acute myeloid leukemia

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.

Pediatric acute myeloid leukemia - novel approaches

PURPOSE OF REVIEW

Despite higher remission and survival rates than observed in adults, children with acute myeloid leukemia (AML) still suffer unacceptably high rates of treatment failure and late toxicities. Ongoing work aims to improve these long-term outcomes through improvements in the utilization of current therapies, the incorporation of novel chemotherapy agents, and improved use of current or novel cellular and immunotherapeutic approaches. In this review, we highlight recent advances and contextualize them within this evolving landscape.

RECENT FINDINGS

Novel agents such as the B-cell lymphoma 2 inhibitor venetoclax and the menin inhibitors have shown promising results with implications for large portions of the pediatric AML population. Older agents are being used in novel combinations (e.g. gemtuzumab ozogamicin) or are expanding into pediatrics after longer use in adults (e.g. Fms-like tyrosine kinase 3 inhibitors). Finally, immunotherapeutic approaches offer new options for patients with high-risk or relapsed disease.

SUMMARY

Recent findings have altered the landscape of pediatric AML therapy with exciting immediate and long-term implications. Ongoing studies may soon define this as standard as well. After many years in which few new therapies have become available for children with AML, recent and upcoming advances may soon dramatically alter the therapeutic landscape.

Outcomes of Allogeneic Hematopoietic Stem Cell Transplantation in Adult Patients With Acute Myeloid Leukemia Harboring KMT2A Rearrangement and Its Prognostic Factors

KMT2A rearrangement (KMT2A-r) in patients with acute myeloid leukemia (AML) is associated with poor outcomes; the prognostic factors after allogeneic hematopoietic stem cell transplantation (allo-HSCT) remain unclear. We investigated 364 adults with AML who underwent allo-HSCT between April 2016 and May 2022, and 45 had KMT2A-r among them. Propensity score analysis with 1:1 matching and the nearest neighbor matching method identified 42 patients in KMT2A-r and non-KMT2A-r cohorts, respectively. The 2-year overall survival (OS), relapse-free survival (RFS), cumulative incidence of relapse (CIR), and non-relapsed mortality rates of patients with KMT2A-r (n = 45) were 59.1%, 49.6%, 41.5%, and 8.9%, respectively. Using propensity score matching, the 2-year OS rate of patients with KMT2A-r (n = 42) was lower than that of those without KMT2A-r (n = 42; 56.1% vs 88.1%, P = 0.003). Among patients with KMT2A-r (n = 45), the prognostic advantage was exhibited from transplantation in first complete remission (CR1) and measurable residual disease (MRD) negative, which was reflected in OS, RFS, and CIR (P < 0.001, P < 0.001, and P = 0.002, respectively). Furthermore, patients with AF6 had poorer outcomes than those with AF9, ELL, and other KMT2A-r subtypes (P = 0.032, P = 0.001, and P = 0.001 for OS, RFS, and CIR, respectively). However, no differences were found in the OS, RFS, and CIR between patients with KMT2A-r with and without mutations (all P > 0.05). Univariate and multivariate analyses revealed that achieving CR1 MRD negative before HSCT was a protective factor for OS [hazard ratio (HR) = 0.242, P = 0.007], RFS (HR = 0.350, P = 0.036), and CIR (HR = 0.271, P = 0.021), while AF6 was a risk factor for RFS (HR = 2.985, P = 0.028) and CIR (HR = 4.675, P = 0.004). The prognosis of patients with KMT2A-r AML was poor, particularly those harboring AF6-related translocation; however, it is not associated with the presence of mutations. These patients can benefit from achieving CR1 MRD negative before HSCT.

KMT2A oncoproteins induce epigenetic resistance to targeted therapies

Chromosomal translocations involving the Lysine-Methyl-Tansferase-2A ( KMT2A ) locus generate potent oncogenes that cause highly aggressive acute leukemias 1 . KMT2A and the most frequent translocation partners encode proteins that interact with DNA to regulate developmental gene expression 2 . KMT2A-oncogenic fusion proteins (oncoproteins) contribute to the epigenetic mechanisms that allow KMT2A -rearranged leukemias to evade targeted therapies. By profiling the oncoprotein-target sites of 34 KMT2A -rearranged leukemia samples, we find that the genomic enrichment of oncoprotein binding is highly variable between samples. At high levels of expression, the oncoproteins preferentially activate either the lymphoid or myeloid lineage program depending on the fusion partner. These fusion-partner-dependent binding sites correspond to the frequencies of each mutation in acute lymphoid leukemia versus acute myeloid leukemia. By profiling a sample that underwent a lymphoid-to-myeloid lineage switching event in response to lymphoid-directed treatment, we find the global oncoprotein levels are reduced and the oncoprotein-target gene network changes. At lower levels of expression, the oncoprotein shifts to a non-canonical regulatory program that favors the myeloid lineage, and in a subset of resistant patients, the Menin inhibitor Revumenib induces a similar response. The dynamic shifts in KMT2A oncoproteins we describe likely contribute to epigenetic resistance of KMT2A -rearranged leukemias to targeted therapies.

The PedAL/EuPAL Project: A Global Initiative to Address the Unmet Medical Needs of Pediatric Patients with Relapsed or Refractory Acute Myeloid Leukemia

The prognosis of children with acute myeloid leukemia (AML) has improved incrementally over the last few decades. However, at relapse, overall survival (OS) is approximately 40-50% and is even lower for patients with chemo-refractory disease. Effective and less toxic therapies are urgently needed for these children. The Pediatric Acute Leukemia (PedAL) program is a strategic global initiative that aims to overcome the obstacles in treating children with relapsed/refractory acute leukemia and is supported by the Leukemia and Lymphoma Society in collaboration with the Children's Oncology Group, the Innovative Therapies for Children with Cancer consortium, and the European Pediatric Acute Leukemia (EuPAL) foundation, amongst others. In Europe, the study is set up as a complex clinical trial with a stratification approach to allocate patients to sub-trials of targeted inhibitors at relapse and employing harmonized response and safety definitions across sub-trials. The PedAL/EuPAL international collaboration aims to determine new standards of care for AML in a first and second relapse, using biology-based selection markers for treatment stratification, and deliver essential data to move drugs to front-line pediatric AML studies. An overview of potential treatment targets in pediatric AML, focused on drugs that are planned to be included in the PedAL/EuPAL project, is provided in this manuscript.

Transformation from acute promyelocytic leukemia in pregnancy to acute myeloid leukemia with MLL-AF9 fusion gene: A case report and literature review

RATIONALE

Because there are few evidence-based guidelines and an extremely low incidence rate, managing and treating patients who have transitioned from acute promyelocytic leukemia (APL), which was diagnosed during pregnancy, to acute myeloid leukemia (AML), can be difficult.

PATIENT CONCERNS

In this case, a 34-year-old pregnant patient was diagnosed with APL in medium-risk group in June 2017. After the all-trans retinoic acid and arsenic trioxide-based full-course treatment, the patients achieved complete remission (CR) and were well-tolerated. After 5 years, the patient complained of fatigue for 3 months.

DIAGNOSIS

Bone marrow examination revealed hypercellularity with approximately 50% immunophenotypic abnormal myeloblasts with MLL-AF9 fusion gene. Based on the AML diagnosis criteria of the World Health Organization, the patient was eventually diagnosed with a rare transformation from APL to AML.

INTERVENTIONS

The patient was treated with two cycles of induction chemotherapy and an allogeneic hematopoietic stem cell transplantation (allo-HSCT).

OUTCOMES

Until now, the patient is in continuous remission with no signs of APL and AML.

LESSIONS

Despite the rarity of APL to AML transformation, it is crucial to track the disease's progress and administer treatment on time. It remains uncertain whether the risk stratification and clinical outcomes of secondary AML with MLL-AF9 are equivalent to those of de novo AML with MLL-AF9. The management and treatment of these patients should be personalized and require further observation.

Therapeutic targeting in pediatric acute myeloid leukemia with aberrant HOX/MEIS1 expression

Despite advances in the clinical management of childhood acute myeloid leukemia (AML) during the last decades, outcome remains fatal in approximately one third of patients. Primary chemoresistance, relapse and acute and long-term toxicities to conventional myelosuppressive therapies still constitute significant challenges and emphasize the unmet need for effective targeted therapies. Years of scientific efforts have translated into extensive insights on the heterogeneous spectrum of genetics and oncogenic signaling pathways of AML and identified a subset of patients characterized by upregulation of HOXA and HOXB homeobox genes and myeloid ecotropic virus insertion site 1 (MEIS1). Aberrant HOXA/MEIS1 expression is associated with genotypes such as rearrangements in Histone-lysine N-methyltransferase 2A (KMT2A-r), nucleoporin 98 (NUP98-r) and mutated nucleophosmin (NPM1c) that are found in approximately one third of children with AML. AML with upregulated HOXA/MEIS1 shares a number of molecular vulnerabilities amenable to recently developed molecules targeting the assembly of protein complexes or transcriptional regulators. The interaction between the nuclear scaffold protein menin and KMT2A has gained particular interest and constitutes a molecular dependency for maintenance of the HOXA/MEIS1 transcription program. Menin inhibitors disrupt the menin-KMT2A complex in preclinical models of KMT2A-r, NUP98-r and NPM1c acute leukemias and its occupancy at target genes leading to leukemic cell differentiation and apoptosis. Early-phase clinical trials are either ongoing or in development and preliminary data suggests tolerable toxicities and encouraging efficacy of menin inhibitors in adults with relapsed or refractory KMT2A-r and NPM1c AML. The Pediatric Acute Leukemia/European Pediatric Acute Leukemia (PedAL/EUPAL) project is focused to advance and coordinate informative clinical trials with new agents and constitute an ideal framework for testing of menin inhibitors in pediatric study populations. Menin inhibitors in combination with standard chemotherapy or other targeting agents may enhance anti-leukemic effects and constitute rational treatment strategies for select genotypes of childhood AML, and provide enhanced safety to avoid differentiation syndrome. In this review, we discuss the pathophysiological mechanisms in KMT2A-r, NUP98-r and NPM1c AML, emerging molecules targeting the HOXA/MEIS1 transcription program with menin inhibitors as the most prominent examples and future therapeutic implications of these agents in childhood AML.

Integration of Transcriptomic Features to Improve Prognosis Prediction of Pediatric Acute Myeloid Leukemia With KMT2A Rearrangement

Lysine methyltransferase 2A-rearranged acute myeloid leukemia (KMT2A-r AML) is a special entity in the 2022 World Health Organization classification of myeloid neoplasms, characterized by high relapse rate and adverse outcomes. Current risk stratification was established on the treatment response and translocation partner of KMT2A. To study the transcriptomic feature and refine the current stratification of pediatric KMT2A-r AML, we analyzed clinical and RNA sequencing data of 351 patients. By implementing least absolute shrinkage and selection operator algorithm, we identified 7 genes (KIAA1522, SKAP2, EGFL7, GAB2, HEBP1, FAM174B, and STARD8) of which the expression levels were strongly associated with outcomes. We then developed a transcriptome-based score, dividing patients into 2 groups with distinct gene expression patterns and prognosis, which was further validated in an independent cohort and outperformed the LSC17 score. We also found cell cycle, oxidative phosphorylation, and metabolism pathways were upregulated in patients with inferior outcomes. By integrating clinical characteristics, we proposed a simple-to-use prognostic scoring system with excellent discriminability, which allowed us to distinguish allogeneic hematopoietic stem cell transplantation candidates more precisely. In conclusion, pediatric KMT2A-r AML is heterogenous on transcriptomic level and the newly proposed scoring system combining clinical characteristics and transcriptomic features can be instructive in clinical routines.

Cytogenetics in the management of acute myeloid leukemia and histiocytic/dendritic cell neoplasms: Guidelines from the Groupe Francophone de Cytogénétique Hématologique (GFCH)

Genetic data are becoming increasingly essential in the management of hematological neoplasms as shown by two classifications published in 2022: the 5th edition of the World Health Organization Classification of Hematolymphoid Tumours and the International Consensus Classification of Myeloid Neoplasms and Acute Leukemias. Genetic data are particularly important for acute myeloid leukemias (AMLs) because their boundaries with myelodysplastic neoplasms seem to be gradually blurring. The first objective of this review is to present the latest updates on the most common cytogenetic abnormalities in AMLs while highlighting the pitfalls and difficulties that can be encountered in the event of cryptic or difficult-to-detect karyotype abnormalities. The second objective is to enhance the role of cytogenetics among all the new technologies available in 2023 for the diagnosis and management of AML.

Risk-Stratified Therapy for Pediatric Acute Myeloid Leukemia

Acute Myeloid Leukemia (AML) is the second most common type of leukemia in children. Recent advances in high-resolution genomic profiling techniques have uncovered the mutational landscape of pediatric AML as distinct from adult AML. Overall survival rates of children with AML have dramatically improved in the past 40 years, currently reaching 70% to 80% in developed countries. This was accomplished by the intensification of conventional chemotherapy, improvement in risk stratification using leukemia-specific cytogenetics/molecular genetics and measurable residual disease, appropriate use of allogeneic hematopoietic stem cell transplantation, and improvement in supportive care. However, the principle therapeutic approach for pediatric AML has not changed substantially for decades and improvement in event-free survival is rather modest. Further refinements in risk stratification and the introduction of emerging novel therapies to contemporary therapy, through international collaboration, would be key solutions for further improvements in outcomes.

The MLL-Menin Interaction is a Therapeutic Vulnerability in NUP98-rearranged AML

Chromosomal translocations involving the NUP98 locus are among the most prevalent rearrangements in pediatric acute myeloid leukemia (AML). AML with NUP98 fusions is characterized by high expression of HOXA and MEIS1 genes and is associated with poor clinical outcome. NUP98 fusion proteins are recruited to their target genes by the mixed lineage leukemia (MLL) complex, which involves a direct interaction between MLL and Menin. Here, we show that therapeutic targeting of the Menin-MLL interaction inhibits the propagation of NUP98-rearrranged AML both ex vivo and in vivo. Treatment of primary AML cells with the Menin inhibitor revumenib (SNDX-5613) impairs proliferation and clonogenicity ex vivo in long-term coculture and drives myeloid differentiation. These phenotypic effects are associated with global gene expression changes in primary AML samples that involve the downregulation of many critical NUP98 fusion protein-target genes, such as MEIS1 and CDK6. In addition, Menin inhibition reduces the expression of both wild-type FLT3 and mutated FLT3-ITD, and in combination with FLT3 inhibitor, suppresses patient-derived NUP98-r AML cells in a synergistic manner. Revumenib treatment blocks leukemic engraftment and prevents leukemia-associated death of immunodeficient mice transplanted with NUP98::NSD1 FLT3-ITD-positive patient-derived AML cells. These results demonstrate that NUP98-rearranged AMLs are highly susceptible to inhibition of the MLL-Menin interaction and suggest the inclusion of AML patients harboring NUP98 fusions into the clinical evaluation of Menin inhibitors.

Mechanisms of Secondary Leukemia Development Caused by Treatment with DNA Topoisomerase Inhibitors

Leukemia is a blood cancer originating in the blood and bone marrow. Therapy-related leukemia is associated with prior chemotherapy. Although cancer therapy with DNA topoisomerase II inhibitors is one of the most effective cancer treatments, its side effects include development of secondary leukemia characterized by the chromosomal rearrangements affecting AML1 or MLL genes. Recurrent chromosomal translocations in the therapy-related leukemia differ from chromosomal rearrangements associated with other neoplasias. Here, we reviewed the factors that drive chromosomal translocations induced by cancer treatment with DNA topoisomerase II inhibitors, such as mobility of ends of double-strand DNA breaks formed before the translocation and gain of function of fusion proteins generated as a result of translocation.

Measurable Residual Disease and Fusion Partner Independently Predict Survival and Relapse Risk in Childhood KMT2A-Rearranged Acute Myeloid Leukemia: A Study by the International Berlin-Frankfurt-Münster Study Group

PURPOSE

A previous study by the International Berlin-Frankfurt-Münster Study Group (I-BFM-SG) on childhood KMT2A-rearranged (KMT2A-r) AML demonstrated the prognostic value of the fusion partner. This I-BFM-SG study investigated the value of flow cytometry-based measurable residual disease (flow-MRD) and evaluated the benefit of allogeneic stem-cell transplantation (allo-SCT) in first complete remission (CR1) in this disease.

METHODS

A total of 1,130 children with KMT2A-r AML, diagnosed between January 2005 and December 2016, were assigned to high-risk (n = 402; 35.6%) or non-high-risk (n = 728; 64.4%) fusion partner-based groups. Flow-MRD levels at both end of induction 1 (EOI1) and 2 (EOI2) were available for 456 patients and were considered negative (<0.1%) or positive (≥0.1%). End points were 5-year event-free survival (EFS), cumulative incidence of relapse (CIR), and overall survival (OS).

RESULTS

The high-risk group had inferior EFS (30.3% high risk v 54.0% non-high risk; P < .0001), CIR (59.7% v 35.2%; P < .0001), and OS (49.2% v 70.5%; P < .0001). EOI2 MRD negativity was associated with superior EFS (n = 413; 47.6% MRD negativity v n = 43; 16.3% MRD positivity; P < .0001) and OS (n = 413; 66.0% v n = 43; 27.9%; P < .0001), and showed a trend toward lower CIR (n = 392; 46.1% v n = 26; 65.4%; P = .016). Similar results were obtained for patients with EOI2 MRD negativity within both risk groups, except that within the non-high-risk group, CIR was comparable with that of patients with EOI2 MRD positivity. Allo-SCT in CR1 only reduced CIR (hazard ratio, 0.5 [95% CI, 0.4 to 0.8]; P = .00096) within the high-risk group but did not improve OS. In multivariable analyses, EOI2 MRD positivity and high-risk group were independently associated with inferior EFS, CIR, and OS.

CONCLUSION

EOI2 flow-MRD is an independent prognostic factor and should be included as risk stratification factor in childhood KMT2A-r AML. Treatment approaches other than allo-SCT in CR1 are needed to improve prognosis.

The KMT2A recombinome of acute leukemias in 2023

Chromosomal rearrangements of the human KMT2A/MLL gene are associated with de novo as well as therapy-induced infant, pediatric, and adult acute leukemias. Here, we present the data obtained from 3401 acute leukemia patients that have been analyzed between 2003 and 2022. Genomic breakpoints within the KMT2A gene and the involved translocation partner genes (TPGs) and KMT2A-partial tandem duplications (PTDs) were determined. Including the published data from the literature, a total of 107 in-frame KMT2A gene fusions have been identified so far. Further 16 rearrangements were out-of-frame fusions, 18 patients had no partner gene fused to 5'-KMT2A, two patients had a 5'-KMT2A deletion, and one ETV6::RUNX1 patient had an KMT2A insertion at the breakpoint. The seven most frequent TPGs and PTDs account for more than 90% of all recombinations of the KMT2A, 37 occur recurrently and 63 were identified so far only once. This study provides a comprehensive analysis of the KMT2A recombinome in acute leukemia patients. Besides the scientific gain of information, genomic breakpoint sequences of these patients were used to monitor minimal residual disease (MRD). Thus, this work may be directly translated from the bench to the bedside of patients and meet the clinical needs to improve patient survival.

SWI/SNF Blockade Disrupts PU.1-Directed Enhancer Programs in Normal Hematopoietic Cells and Acute Myeloid Leukemia

In acute myeloid leukemia (AML), SWI/SNF chromatin remodeling complexes sustain leukemic identity by driving high levels of MYC. Previous studies have implicated the hematopoietic transcription factor PU.1 (SPI1) as an important target of SWI/SNF inhibition, but PU.1 is widely regarded to have pioneer-like activity. As a result, many questions have remained regarding the interplay between PU.1 and SWI/SNF in AML as well as normal hematopoiesis. Here we found that PU.1 binds to most of its targets in a SWI/SNF-independent manner and recruits SWI/SNF to promote accessibility for other AML core regulatory factors, including RUNX1, LMO2, and MEIS1. SWI/SNF inhibition in AML cells reduced DNA accessibility and binding of these factors at PU.1 sites and redistributed PU.1 to promoters. Analysis of nontumor hematopoietic cells revealed that similar effects also impair PU.1-dependent B-cell and monocyte populations. Nevertheless, SWI/SNF inhibition induced profound therapeutic response in an immunocompetent AML mouse model as well as in primary human AML samples. In vivo, SWI/SNF inhibition promoted leukemic differentiation and reduced the leukemic stem cell burden in bone marrow but also induced leukopenia. These results reveal a variable therapeutic window for SWI/SNF blockade in AML and highlight important off-tumor effects of such therapies in immunocompetent settings.

SIGNIFICANCE

Disruption of PU.1-directed enhancer programs upon SWI/SNF inhibition causes differentiation of AML cells and induces leukopenia of PU.1-dependent B cells and monocytes, revealing the on- and off-tumor effects of SWI/SNF blockade.

Epigenomic machinery regulating pediatric AML: clonal expansion mechanisms, therapies, and future perspectives

Acute myeloid leukemia (AML) is a heterogeneous disease with a genetic, epigenetic, and transcriptional etiology mainly presenting somatic and germline abnormalities. AML incidence rises with age but can also occur during childhood. Pediatric AML (pAML) accounts for 15-20% of all pediatric leukemias and differs considerably from adult AML. Next-generation sequencing technologies have enabled the research community to "paint" the genomic and epigenomic landscape in order to identify pathology-associated mutations and other prognostic biomarkers in pAML. Although current treatments have improved the prognosis for pAML, chemoresistance, recurrence, and refractory disease remain major challenges. In particular, pAML relapse is commonly caused by leukemia stem cells that resist therapy. Marked patient-to-patient heterogeneity is likely the primary reason why the same treatment is successful for some patients but, at best, only partially effective for others. Accumulating evidence indicates that patient-specific clonal composition impinges significantly on cellular processes, such as gene regulation and metabolism. Although our understanding of metabolism in pAML is still in its infancy, greater insights into these processes and their (epigenetic) modulation may pave the way toward novel treatment options. In this review, we summarize current knowledge on the function of genetic and epigenetic (mis)regulation in pAML, including metabolic features observed in the disease. Specifically, we describe how (epi)genetic machinery can affect chromatin status during hematopoiesis, leading to an altered metabolic profile, and focus on the potential value of targeting epigenetic abnormalities in precision and combination therapy for pAML. We also discuss the possibility of using alternative epidrug-based therapeutic approaches that are already in clinical practice, either alone as adjuvant treatments and/or in combination with other drugs.

Stratification and therapeutic potential of ELL in cytogenetic normal acute myeloid leukemia

Optimizing prognostic stratification of patients with cytogenetic normal acute myeloid leukemia (CN-AML), a highly heterogeneous subgroup in AML, appears to be important to improve its treatment and clinical outcome. Here, we report a potential role of ELL, a gene associated with leukemogenesis in AML, in prognostic stratification of CN-AML patients. By analyzing public available databases, we found that ELL was highly expressed in AML patients compared with healthy donors. Kaplan-Meier analysis revealed that ELL expression markedly correlated with short overall survival (OS) of CN-AML patients. In COX multivariable regression analysis, higher ELL expression was an independent prognostic factor for OS in CN-AML. Knockdown of ELL by shRNAs sensitized KG-1α cells to anti-leukemic agents such as idarubicin (IDA) and chidamide (CS055), supporting its role in therapeutic response and outcome in AML. To understand its function in CN-AML, we further analyzed the ELL-driving gene signature. ELL-related genes were particularly enriched in cell adhesion molecules, cell differentiation, pathways in cancer, sequence-specific DNA binding, and extracellular matrix (ECM)-receptor interaction. Analysis of the PPI network identified 25 hub genes, including the stem cell gene BMP4. While BMP4 expression was significantly associated with ELL in CN-AML, knockdown of ELL markedly down-regulated BMP4 expression, suggesting that ELL might function via regulating BMP4 in AML. Together, these observations suggest a novel mechanism underlying pro-leukemogenic role of ELL via BMP4 up-regulation in AML and its potential value to serve as a predictive biomarker for therapeutic response and outcome of CN-AML patients.

Integrative phosphoproteomics defines two biologically distinct groups of KMT2A rearranged acute myeloid leukaemia with different drug response phenotypes

Acute myeloid leukaemia (AML) patients harbouring certain chromosome abnormalities have particularly adverse prognosis. For these patients, targeted therapies have not yet made a significant clinical impact. To understand the molecular landscape of poor prognosis AML we profiled 74 patients from two different centres (in UK and Finland) at the proteomic, phosphoproteomic and drug response phenotypic levels. These data were complemented with transcriptomics analysis for 39 cases. Data integration highlighted a phosphoproteomics signature that define two biologically distinct groups of KMT2A rearranged leukaemia, which we term MLLGA and MLLGB. MLLGA presented increased DOT1L phosphorylation, HOXA gene expression, CDK1 activity and phosphorylation of proteins involved in RNA metabolism, replication and DNA damage when compared to MLLGB and no KMT2A rearranged samples. MLLGA was particularly sensitive to 15 compounds including genotoxic drugs and inhibitors of mitotic kinases and inosine-5-monosphosphate dehydrogenase (IMPDH) relative to other cases. Intermediate-risk KMT2A-MLLT3 cases were mainly represented in a third group closer to MLLGA than to MLLGB. The expression of IMPDH2 and multiple nucleolar proteins was higher in MLLGA and correlated with the response to IMPDH inhibition in KMT2A rearranged leukaemia, suggesting a role of the nucleolar activity in sensitivity to treatment. In summary, our multilayer molecular profiling of AML with poor prognosis and KMT2A-MLLT3 karyotypes identified a phosphoproteomics signature that defines two biologically and phenotypically distinct groups of KMT2A rearranged leukaemia. These data provide a rationale for the potential development of specific therapies for AML patients characterised by the MLLGA phosphoproteomics signature identified in this study.

Evolution and optimization of therapies for acute lymphoblastic leukemia in infants

Acute lymphoblastic leukemia (ALL) in infants accounts for less than 5% of pediatric ALL and is biologically and clinically unique. Approximately 70% to 80% of cases present as an aggressive leukemia with KMT2A gene rearrangement (KMT2A-r), which is one of the most difficult-to-cure forms of pediatric leukemia. Owing to continuing global efforts through multicenter clinical trials since the mid-1990s, a standard of care for infant KMT2A-r ALL, including minimal residual disease-based risk stratifications, "hybrid chemotherapy" incorporating myeloid leukemia-like drugs (e.g., cytarabine) into the ALL chemotherapy backbone, and selective use of allogeneic hematopoietic stem cell transplantation, has now been established. However, there are still many concerns regarding treatment of infants with KMT2A-r ALL, including insufficient efficacy of the current standard therapies, limited pharmacokinetic/pharmacodynamic data on drugs in infants, and management of both acute and late toxicities. Refinements in risk stratification based on leukemia biology, as well as the introduction of emerging novel immunotherapies and molecular-targeted drugs to contemporary therapy, through international collaboration would provide key solutions for further improvement in outcomes.

Measurable residual disease study through three different methods can anticipate relapse and guide pre-emptive therapy in childhood acute myeloid leukemia

PURPOSE

Although outcomes of children with acute myeloid leukemia (AML) have improved over the last decades, around one-third of patients relapse. Measurable (or minimal) residual disease (MRD) monitoring may guide therapy adjustments or pre-emptive treatments before overt hematological relapse.

METHODS

In this study, we review 297 bone marrow samples from 20 real-life pediatric AML patients using three MRD monitoring methods: multiparametric flow cytometry (MFC), fluorescent in situ hybridization (FISH) and polymerase chain reaction (PCR).

RESULTS

Patients showed a 3-year overall survival of 73% and a 3-year event-free survival of 68%. Global relapse rate was of 25%. All relapses were preceded by the reappearance of MRD detection by: (1) MFC (p = 0.001), (2) PCR and/or FISH in patients with an identifiable chromosomal translocation (p = 0.03) and/or (3) one log increase of Wilms tumor gene 1 (WT1) expression in two consecutive samples (p = 0.02). The median times from MRD detection to relapse were 26, 111, and 140 days for MFC, specific PCR and FISH, and a one log increment of WT1, respectively.

CONCLUSIONS

MFC, FISH and PCR are complementary methods that can anticipate relapse of childhood AML by weeks to several months. However, in our series, pre-emptive therapies were not able to prevent disease progression. Therefore, more sensitive MRD monitoring methods that further anticipate relapse and more effective pre-emptive therapies are needed.

Successful combination treatment with azacitidine and venetoclax as a bridging therapy for third allogenic stem cell transplantation in a patient with 11q23/MLL-rearranged complex karyotype acute myeloid leukemia

Translocation t(6;11) occurs in approximately 5% of patients with acute myeloid leukemia (AML) corresponding to 11q23/mixed lineage leukemia (MLL) rearrangement. The AF6 gene on chromosome 6q27 is the fusion partner of the MLL gene on 11q23 in t(6;11), which results in a poor prognosis. The case of a patient with 11q23/MLL-rearranged AML who successfully underwent a third allogeneic stem cell transplantation after treatment with azacitidine (AZA) and venetoclax (VEN) is presented in this article. This report suggests that a combination of AZA and VEN is an effective therapeutic approach for relapsed and refractory MLL-rearranged AML.

Prognostic value and outcome for acute lymphocytic leukemia in children with MLL rearrangement: a case-control study

Purpose

To evaluate the prognostic factors and outcome for acute lymphoblastic leukemia (ALL) in children with MLL rearrangement (MLL-r).

Methods

A total of 124 pediatric patients who were diagnosed with ALL were classified into two groups based on the MLL-r status by using a retrospective case-control study method from June 2008 to June 2020.

Results

The prevalence of MLL-r positive in the whole cohort was 4.9%. The complete remission (CR) rate on Day 33 in the MLL-r positive group was not statistically different from the negative group (96.8% vs 97.8%, P = 0.736). Multivariate analysis showed that T-cell, white blood cell counts (WBC) ≥ 50 × 109/L, MLL-AF4, and D15 minimal residual disease (MRD) positive were independent risk factors affecting the prognosis of MLL-r positive children. Stem cell transplantation (SCT) was a favorable independent prognostic factor affecting event-free survival (EFS) in MLL-r positive patients (P = 0.027), and there was a trend toward an independent prognostic effect on overall survival (OS) (P = 0.065). The 10-year predicted EFS for patients with MLL-AF4, MLL-PTD, MLL-ENL, other MLL partner genes, and MLL-r negative cases were 46.67 ± 28.61%, 85.71 ± 22.37%, 75 ± 32.41%, 75 ± 32.41%, and 77.33 ± 10.81%, respectively (P = 0.048). The 10-year predicted OS were 46.67 ± 28.61%, 85.71 ± 22.37%, 75 ± 32.41%, 75 ± 32.41%, and 85.2 ± 9.77%, respectively (P = 0.049). The 124 patients with ALL were followed up and eventually 5 (4%) cases relapsed, with a median relapse time of 3.9 years.

Conclusion

Patients with MLL-r positive ALL have moderate remission rates, but are prone to relapse with low overall survival. The outcome of MLL-r positive ALL was closely related to the partner genes, and clinical attention should be paid to screening for MLL partner genes and combining them with other prognostic factors for accurate risk stratification.

Targeting Menin and CD47 to Address Unmet Needs in Acute Myeloid Leukemia

After forty years of essentially unchanged treatment in acute myeloid leukemia (AML), innovation over the past five years has been rapid, with nine drug approvals from 2016 to 2021. Increased understanding of the molecular changes and genetic ontology of disease have led to targeting mutations in isocitrate dehydrogenase, FMS-like tyrosine kinase 3 (FLT3), B-cell lymphoma 2 and hedgehog pathways. Yet outcomes remain variable; especially in defined molecular and genetic subgroups such as NPM1 (Nucleophosmin 1) mutations, 11q23/KMT2A rearranged and TP53 mutations. Emerging therapies seek to address these unmet needs, and all three of these subgroups have promising new therapeutic approaches. Here, we will discuss the normal biological roles of menin in acute leukemia, notably in KMT2A translocations and NPM1 mutation, as well as current drug development. We will also explore how CD47 inhibition may move immunotherapy into front-line settings and unlock new treatment strategies in TP53 mutated disease. We will then consider how these new therapeutic advances may change the management of AML overall.

t(4;11) translocation in hyperdiploid de novo adult acute myeloid leukemia: A case report

BACKGROUND

MLL gene rearrangement is a common genetic abnormality of acute myeloid leukemia (AML), which predicts poor prognosis and is important in clinical diagnosis. MLL rearrangement involves many chromosomes, among which, t(4;11) translocation is rare in AML. The present case was t(4;11) AML, accompanied by a hyperdiploid karyotype. Such cases have not been reported previously.

CASE SUMMARY

An adult male with self-reported symptoms of fatigue, febrility and hyperleukocytosis was diagnosed with AML by morphology and confirmed by immunophenotype analysis. Uncommonly, chromosomal and fluorescence in situ hybridization (FISH) analysis showed a hyperdiploid karyotype with t(4;11) translocation and MLL rearrangement, and a negative MLL–AF4 fusion gene result. The patient died of respiratory and circulatory failure 5 days after diagnosis.

CONCLUSION

t(4;11) AML with hyperdiploid karyotype has not been reported. In this case, t(4;11) was only detected by karyotype analysis and FISH, suggesting their importance in MLL rearrangement detection.

Clinical profile in KMT2A-SEPT6-positive acute myeloid leukemia: Does it often co-occur with NRAS mutations?

Background

The KMT2A-SEPT6 fusion gene is a relatively rare genetic event in leukemia. Its clinical characteristics and prognosis, especially the profile of co-occurring gene mutations remain unclear.

Methods

We retrospectively analyzed the characteristics of four cases carrying KMT2A-SEPT6 in our hospital, and provided a literature review.

Results

All the four patients were diagnosed with acute myeloid leukemia (AML) and harbored X chromosome and 11 chromosome rearrangements, they all manifested high levels of D-dimer. Three of four patients had NRAS mutations while one patient with congenital AML did not. Of the four cases, one developed drug resistance, one suffered relapse after bone marrow transplantation (BMT) and two died. Combined with other cases reported in the literature, we found that of all patients diagnosed with AML, 90.9% were children (≤9 years old). Patients with white blood cells ≥20.0 × 10⁹/L or diagnosed with M4 had a shorter overall survival (P < 0.05). Age, whether to receive BMT, and the chromosome rearrangement patterns had no significant effect on overall survival (P > 0.05).

Conclusions

KMT2A-SEPT6 was more commonly observed in pediatric AML patients, some of which may co-occur with NRAS mutations. The prognosis was related to the white blood cell levels and the leukemia subtype, but was not related to age or BMT. More cases need to be accumulated to better understand the profile in KMT2A-SEPT6-positive AML.

Integrated stem cell signature and cytomolecular risk determination in pediatric acute myeloid leukemia

Relapsed or refractory pediatric acute myeloid leukemia (AML) is associated with poor outcomes and relapse risk prediction approaches have not changed significantly in decades. To build a robust transcriptional risk prediction model for pediatric AML, we perform RNA-sequencing on 1503 primary diagnostic samples. While a 17 gene leukemia stem cell signature (LSC17) is predictive in our aggregated pediatric study population, LSC17 is no longer predictive within established cytogenetic and molecular (cytomolecular) risk groups. Therefore, we identify distinct LSC signatures on the basis of AML cytomolecular subtypes (LSC47) that were more predictive than LSC17. Based on these findings, we build a robust relapse prediction model within a training cohort and then validate it within independent cohorts. Here, we show that LSC47 increases the predictive power of conventional risk stratification and that applying biomarkers in a manner that is informed by cytomolecular profiling outperforms a uniform biomarker approach.

Relapsed pediatric acute myeloid leukemia is associated with poor prognosis. Here, the authors use RNA-seq data from 1503 primary samples to create a combined transcriptional and cytomolecular signature to improve relapse risk prediction.

Allogeneic hematopoietic stem cell transplantation for pediatric acute myeloid leukemia in first complete remission: a meta-analysis

Identification of pediatric patients with acute myeloid leukemia (AML) candidates to receive allogeneic hematopoietic stem cell transplantation (allo-HSCT) in first complete remission (CR1) is still a matter of debate. Currently, transplantation is reserved to patients considered at high risk of relapse based on cytogenetics, molecular biology, and minimal residual disease (MRD) assessment. However, no randomized clinical trial exists in the literature comparing transplantation with other types of consolidation therapy. Here, we provide an up-to-date meta-analysis of studies comparing allo-HSCT in CR1 with chemotherapy alone as a post-remission treatment in high-risk pediatric AML. The literature search strategy identified 10 cohorts from 9 studies performing as-treated analysis. The quantitative synthesis showed improved overall survival (OS) (relative risk, 1.15; 95% confidence interval [CI], 1.06-1.24; P = 0.0006) and disease-free survival (relative risk, 1.31; 95% CI, 1.17-1.47; P = 0.0001) in the allo-HSCT group, with increased relapse rate in the chemotherapy group (relative risk, 1.26; 95% CI, 1.07-1.49; P = 0.006). Sensitivity analysis including prospective studies alone and excluding studies that reported the comparison only on intermediate-risk patients confirmed the benefit of allo-HSCT on OS. Further research should focus on individualizing allo-HSCT indications based on molecular stratification and MRD monitoring.

Outcomes of allogeneic haematopoietic stem cell transplantation for paediatric patients with MLL-rearranged acute myeloid leukaemia

Background

The presence of mixed-lineage leukaemia rearrangement (MLL-r) in paediatric patients with acute myeloid leukaemia (AML) is a poor prognostic predictor. Whether allogeneic haematopoietic stem cell transplantation (allo-HSCT) is beneficial in such cases remains unclear.

Methods

We evaluated the outcomes and prognostic factors of allo-HSCT in 44 paediatric patients with MLL-r AML in the first complete remission (CR1) between 2014 and 2019 at our institution.

Results

For all the 44 patients, the 3-year overall survival (OS), event-free survival (EFS), and cumulative incidence of relapse (CIR) were 74.5%, 64.1%, and 29.1%, respectively. Among them, 37 (84.1%) patients received haploidentical (haplo)-HSCT, and the 3-year OS, EFS, and CIR were 73.0%, 65.6%, and 26.4%, respectively. The 100-day cumulative incidence of grade II–IV acute graft-versus-host disease (aGVHD) post-transplantation was 27.3%, and that of grade III–IV aGVHD was 15.9%. The overall 3-year cumulative incidence of chronic graft-versus-host disease (cGVHD) post-transplantation was 40.8%, and that of extensive cGVHD was 16.7%. Minimal residual disease (MRD)-positive (MRD +) status pre-HSCT was significantly associated with lower survival and higher risk of relapse. The 3-year OS, EFS, and CIR differed significantly between patients with MRD + pre-HSCT (n = 15; 48.5%, 34.3% and 59%) and those with MRD-pre-HSCT (n = 29; 89.7%, 81.4% and 11.7%). Pre-HSCT MRD + status was an independent risk factor in multivariate analysis.

Conclusions

Allo-HSCT (especially haplo-HSCT) can be a viable strategy in these patients, and pre-HSCT MRD status significantly affected the outcomes.

Mutational landscape and clinical outcome of pediatric acute myeloid leukemia with 11q23/KMT2A rearrangements

BACKGROUND

Alterations of 11q23/KMT2A are the most prevalent cytogenetic abnormalities in acute myeloid leukemia (AML) and the prognostic significance of 11q23/KMT2A-rearranged AML based on various translocation partners varies among different studies. However, few studies evaluated the molecular characteristics of 11q23/KMT2A-rearranged pediatric AML. We aim to analyze the mutational landscape of 11q23/KMT2A-rearranged AML and assess their prognostic value in outcomes.

METHODS

The mutational landscape and clinical prognosis of 105 children with 11q23/KMT2A-rearranged AML in comparison with 277 children with non-11q23/KMT2A-rearranged AML were analyzed using publicly accessible next-generation sequencing data from Therapeutically Applicable Research to Generate Effective Treatments (TARGET) dataset.

RESULTS

Pediatric AML patients with 11q23/KMT2A-rearrangements harbored a low number of mutations (Median, 1 mutation/patient, range, 1-22), 58% of which involved in RAS pathway mutations (KRAS, NRAS, and PTPN11) and 10.5% of which comprised of SETD2 mutations. Compared with non-11q23/KMT2A-rearranged AML, the incidence of KRAS (32.4% vs. 10.1%, P〈0.001) and SETD2 (10.5% vs. 1.4%, P=0.001) gene mutations in 11q23/KMT2A-rearranged AML was significantly higher. Both KRAS and SETD2 mutations occurred more often in t(10;11)(p12;q23). KRAS mutations were correlated with worse 5-year event-free survival [EFS] (Plog-rank = 0.001) and 5-year overall survival [OS] (Plog-rank = 0.009) and the presence of SETD2 mutations increases the 5-year relapse rate (PGray = 0.004). Multivariate analyses confirmed KRAS mutations in 11q23/KMT2A-rearranged AML as an independent predictor for poor EFS (hazard ratio [HR] = 2.10, P=0.05) and OS (HR = 2.39, P=0.054).

CONCLUSION

Our findings show that pediatric patients with 11q23/KMT2A rearrangements have characteristic mutation patterns and varying clinical outcomes depending on different translocation partners, which could be utilized to develop more accurate risk stratification and tailored therapies.

EAHP 2020 workshop proceedings, pediatric myeloid neoplasms

The first section of the bone marrow workshop of the European Association of Haematopathology (EAHP) 2020 Virtual Meeting was dedicated to pediatric myeloid neoplasms. The section covered the whole spectrum of myeloid neoplasms, including myelodysplastic syndromes (MDS), myeloproliferative neoplasms (MPN), myelodysplastic/myeloproliferative neoplasms (MDS/MPN), and acute myeloid leukemia (AML). The workshop cases are hereby presented, preceded by an introduction on these overall rare diseases in this age group. Very rare entities such as primary myelofibrosis, pediatric MDS with fibrosis, and MDS/MPN with JMML-like features and t(4;17)(q12;q21); FIP1L1::RARA fusion, are described in more detail.

A phase III clinical trial evaluating efficacy and safety of minimal residual disease-based risk stratification for children with acute myeloid leukemia, incorporating a randomized study of gemtuzumab ozogamicin in combination with post-induction chemotherapy for non-low-risk patients (JPLSG-AML-20)

The purpose of this study is to establish a treatment with appropriate intensity for children (<16 years old at diagnosis) with de novo acute myeloid leukemia (excluding acute promyelocytic leukemia and myeloid leukemia associated with Down syndrome) according to a risk stratification based on recurrent leukemic cytogenetic abnormalities and flow-cytometric minimal residual disease at end of initial induction chemotherapy and to validate the safety and efficacy of gemtuzumab ozogamicin (GO)-combined post-induction chemotherapy for the non-low-risk (non-LR) patients. The primary endpoint of this phase III study is three-year disease-free survival rate, which will be compared between the GO and non-GO arms of the non-LR (intermediate-risk and high-risk [HR]) patients. All HR patients will be allocated to allogeneic hematopoietic stem cell transplantation in first remission. This trial has been registered at the Japan Registry of Clinical Trials (jRCTs041210015).

Pediatric acute myeloid leukemia patients with KMT2A rearrangements: a single-center retrospective study

PURPOSE

Pediatric acute myeloid leukemia (AML) with KMT2A rearrangements has a very different prognosis. Poor outcomes cannot be avoided even after hematopoietic stem cell transplantation. In order to investigate the prognosis and efficacy, we conducted a retrospective analysis.

PATIENTS AND METHODS

We retrospectively analyzed a total of 32 children with KMT2A rearrangements AML treated in our hospital between January 2015 and February 2021.

RESULTS

The proportion of patients with KMT2A-rearranged in the medium-risk group of overall survival (OS) and event-free survival (EFS) was 100%. No differences in OS, EFS and cumulative incidence of relapse (CIR) were detected between the haploidentical hematopoietic stem cell transplantation (haplo-HSCT) and full matched HSCT (P = 0.289, P = 0.303, P = 0.303). Acute graft-versus-host disease (aGVHD) was often detected in the haplo-HSCT cohort, while full matched HSCT had no obvious aGVHD, assessed as≤1 grade (P < 0.05). Patients in the medium-risk pediatric group could acquire 100% OS and EFS only after chemotherapy. There was no significant difference in OS, EFS and CIR between full matched HSCT and haploidentical transplantation in pediatric AML with KMT2A rearrangements, but full matched HSCT seemed to have a lower death rate. The severity of aGVHD in the full matched HSCT was less than that in the haploidentical transplantation group.

CONCLUSION

The primary choice of donor can be HLA-matched sibling donors or matched unrelated donors for children with AML with KMT2A rearrangements, and the secondary choice can be haploid donors.

The Histone Deacetylase Inhibitor I1 Induces Differentiation of Acute Leukemia Cells With MLL Gene Rearrangements via Epigenetic Modification

Acute leukemia (AL) is characterized by excessive proliferation and impaired differentiation of leukemic cells. AL includes acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL). Previous studies have demonstrated that about 10% of AML and 22% of ALL are mixed lineage leukemia gene rearrangements (MLLr) leukemia. The prognosis of MLLr leukemia is poor and new therapeutics are urgently needed. Differentiation therapy with all-trans-retinoic acid (ATRA) has prolonged the 5-years disease-free survival rate in acute promyelocytic leukemia (APL), a subtype of AML. However, the differentiation therapy has not been effective in other acute leukemia. Here, we aim to explore the cell differentiation effect of the potent HDACs inhibitor, I1, and the possible mechanism on the MLLr-AML and MLLr-ALL cells (MOLM-13, THP-1, MV4-11 and SEM). It is shown that I1 can significantly inhibit the proliferation and the colony-forming ability of MOLM-13, THP-1, MV4-11 and SEM cells by promoting cell differentiation coupled with cell cycle block at G0/G1 phase. We show that the anti-proliferative effect of I1 attributed to cell differentiation is most likely associated with the HDAC inhibition activity, as assessed by the acetylation of histone H3 and H4, which may dictates the activation of hematopoietic cell lineage pathway in both MOLM-13 and THP-1 cell lines. Moreover, the activity of HDAC inhibition of I1 is stronger than that of SAHA in MOLM-13 and THP-1 cells. Our findings suggest that I1, as a chromatin-remodeling agent, could be a potent epigenetic drug to overcome differentiation block in MLLr-AL patients and would be promising for the treatment of AL.

The dual role of autophagy in acute myeloid leukemia

Acute myeloid leukemia (AML) is a severe hematologic malignancy prevalent in older patients, and the identification of potential therapeutic targets for AML is problematic. Autophagy is a lysosome-dependent catabolic pathway involved in the tumorigenesis and/or treatment of various cancers. Mounting evidence has suggested that autophagy plays a critical role in the initiation and progression of AML and anticancer responses. In this review, we describe recent updates on the multifaceted functions of autophagy linking to genetic alterations of AML. We also summarize the latest evidence for autophagy-related genes as potential prognostic predictors and drivers of AML tumorigenesis. We then discuss the crosstalk between autophagy and tumor cell metabolism into the impact on both AML progression and anti-leukemic treatment. Moreover, a series of autophagy regulators, i.e., the inhibitors and activators, are described as potential therapeutics for AML. Finally, we describe the translation of autophagy-modulating therapeutics into clinical practice. Autophagy in AML is a double-edged sword, necessitating a deeper understanding of how autophagy influences dual functions in AML tumorigenesis and anti-leukemic responses.

The tumor suppressor MIR139 is silenced by POLR2M to promote AML oncogenesis

MIR139 is a tumor suppressor and is commonly silenced in acute myeloid leukemia (AML). However, the tumor-suppressing activities of miR-139 and molecular mechanisms of MIR139-silencing remain largely unknown. Here, we studied the poorly prognostic MLL-AF9 fusion protein-expressing AML. We show that MLL-AF9 expression in hematopoietic precursors caused epigenetic silencing of MIR139, whereas overexpression of MIR139 inhibited in vitro and in vivo AML outgrowth. We identified novel miR-139 targets that mediate the tumor-suppressing activities of miR-139 in MLL-AF9 AML. We revealed that two enhancer regions control MIR139 expression and found that the polycomb repressive complex 2 (PRC2) downstream of MLL-AF9 epigenetically silenced MIR139 in AML. Finally, a genome-wide CRISPR-Cas9 knockout screen revealed RNA Polymerase 2 Subunit M (POLR2M) as a novel MIR139-regulatory factor. Our findings elucidate the molecular control of tumor suppressor MIR139 and reveal a role for POLR2M in the MIR139-silencing mechanism, downstream of MLL-AF9 and PRC2 in AML. In addition, we confirmed these findings in human AML cell lines with different oncogenic aberrations, suggesting that this is a more common oncogenic mechanism in AML. Our results may pave the way for new targeted therapy in AML.