Clinical Analysis of Pediatric Acute Megakaryocytic Leukemia With CBFA2T3-GLIS2 Fusion Gene.

CBFA2T3-GLIS2 is the most frequent chimeric oncogene identified to date in non-Down syndrome acute megakaryocytic leukemia (AMKL), which is associated with extremely poor clinical outcome. The presence of this fusion gene is associated with resistance to high-intensity chemotherapy, including hematopoietic stem cell transplantation (HSCT), and a high cumulative incidence of relapse frequency. The clinical features and clinical effects of China Children's Leukemia Group-acute myeloid leukemia (AML) 2015/2019 regimens and haploidentical HSCT (haplo-HSCT) for treatment of 6 children harboring the CBFA2T3-GLIS2 fusion gene between January 2019 and December 2021 were retrospectively analyzed. The 6 patients included 4 boys and 2 girls with a median disease-onset age of 19.5 months (range: 6-67 mo) who were diagnosed with AMKL. Flow cytometry demonstrated CD41a, CD42b, and CD56 expression and lack of HLA-DR expression in all 6 patients. All the children were negative for common leukemia fusion genes by reverse transcription polymerase chain reaction, but positive for the CBFA2T3-GLIS2 fusion gene by next-generation sequencing and RNA sequencing. All patients received chemotherapy according to China Children's Leukemia Group-AML 2015/2019 regimens, and 4 achieved complete remission. Four children underwent haplo-HSCT with posttransplant cyclophosphamide-based conditioning; 3 had minimal residual disease negative (minimal residual disease <0.1%) confirmed by flow cytometry at the end of the follow-up, with the remaining patient experiencing relapse at 12 months after transplantation. Transcriptome RNA sequencing is required for the detection of the CBFA2T3-GLIS2 fusion gene and for proper risk-based allocation of pediatric patients with AML in future clinical strategies. Haplo-HSCT with posttransplant cyclophosphamide-based conditioning may improve survival in children with AMKL harboring the fusion gene.

Acute megakaryoblastic leukaemia shows high frequency of chromosome 1q aberrations and dismal outcome.

Acute megakaryoblastic leukaemia (AMKL) is associated with poor prognosis. Limited information is available on its cytogenetics, molecular genetics and clinical outcome. We performed genetic analyses, evaluated prognostic factors and the value of allogeneic haematopoietic stem cell transplantation (allo-HSCT) in a homogenous adult AMKL patient cohort. We retrospectively analysed 38 adult patients with AMKL (median age: 58 years, range: 21-80). Most received intensive treatment in AML Cooperative Group (AMLCG) trials between 2001 and 2016. Cytogenetic data showed an accumulation of adverse risk markers according to ELN 2017 and an unexpected high frequency of structural aberrations on chromosome arm 1q (33%). Most frequently, mutations occurred in TET2 (23%), TP53 (23%), JAK2 (19%), PTPN11 (19%) and RUNX1 (15%). Complete remission rate in 33 patients receiving intensive chemotherapy was 33% and median overall survival (OS) was 33 weeks (95% CI: 21-45). Patients undergoing allo-HSCT (n = 14) had a superior median OS (68 weeks; 95% CI: 11-126) and relapse-free survival (RFS) of 27 weeks (95% CI: 4-50), although cumulative incidence of relapse after allo-HSCT was high (62%). The prognosis of AMKL is determined by adverse genetic risk factors and therapy resistance. So far allo-HSCT is the only potentially curative treatment option in this dismal AML subgroup.

Acute monocytic leukemia with KMT2A::LASP1 developed 9 months after diagnosis of acute megakaryoblastic leukemia in a 2-year-old boy.

Acute myeloid leukemia (AML) is known as one of the subsequent malignant neoplasms that can develop after cancer treatment, but it is difficult to distinguish from relapse when the preceding cancer is leukemia. We report a 2-year-old boy who developed acute megakaryoblastic leukemia (AMKL, French-American-British classification [FAB]: M7) at 18 months of age and achieved complete remission with multi-agent chemotherapy without hematopoietic stem cell transplantation. Nine months after diagnosis and 4 months after completing treatment for AMKL, he developed acute monocytic leukemia (AMoL) with the KMT2A::LASP1 chimeric gene (FAB: M5b). The second complete remission was achieved using multi-agent chemotherapy and he underwent cord blood transplantation 4 months after AMoL was diagnosed. He is currently alive and disease free at 39 and 48 months since his AMoL and AMKL diagnoses, respectively. Retrospective analysis revealed that the KMT2A::LASP1 chimeric gene was detected 4 months after diagnosis of AMKL. Common somatic mutations were not detected in AMKL or AMoL and no germline pathogenic variants were detected. Since the patient's AMoL was different from his primary leukemia of AMKL in terms of morphological, genomic, and molecular analysis, we concluded that he developed a subsequent leukemia rather than a relapse of his primary leukemia.

Haematopoietic cell transplantation for children with acute megakaryoblastic leukaemia without Down syndrome.

Patients with acute megakaryoblastic leukaemia of Down syndrome (DS-AMKL) have an excellent survival rate; however, patients with non-DS-AMKL experience poor outcomes. Therefore, this study retrospectively analysed 203 children with non-DS-AMKL who underwent their first haematopoietic cell transplantation (HCT) from 1986 to 2015 using a nationwide Japanese HCT registry data to assess HCT outcomes for non-DS-AMKL. The 5-year overall survival (OS) and event-free survival (EFS) rates were 43% and 38% respectively. The 5-year OS rate was significantly higher for patients who underwent HCT in the first complete remission (CR1, 72%) than for those in the second CR (CR2, 23%) and non-CR (16%) (p < 0.001), and for those from a human leukocyte antigen (HLA)-matched (52%) than for those from an HLA-mismatched donor (27%) (p < 0.001). Multivariate analysis for OS revealed that HCT in CR2 and non-CR was a significant risk factor (hazard ratio, 5.86; 95% confidence interval, 3.56-9.53; p < 0.001). The 3-year EFS in patients who received HCT in CR1 using reduced-intensity conditioning (RIC, 35%) was significantly lower than in those using myeloablative conditioning (busulfan-based, 71%; total body irradiation-based, 58%) (p < 0.001). Risk stratification in patients with non-DS-AMKL should be established to determine HCT indication in CR1.

Lineage switch in a pediatric patient with KMT2A-MLLT3 from acute megakaryoblastic leukemia to T cell acute lymphoblastic leukemia at the fourth relapse after allo-HSCT: with literature review.

We present a patient with acute megakaryoblastic leukemia (AMKL) harboring KMT2A-MLLT3 that converted to T cell acute lymphoblastic leukemia (T-ALL) at her fourth relapse. A 4-year-old girl developed AMKL with multiple swollen lymph nodes. She exhibited several recurrences in the bone marrow and died of septic shock after her fourth relapse. Bone marrow cells at the initial diagnosis and at all four relapses had the same KMT2A-MLLT3 fusion transcript. She also developed a somatic mutation (c.7177C > T p.Q2393X) of NOTCH1 at the fourth relapse. This sequential phenotypic and cytogenetic study may yield valuable insights into the mechanism of AMKL to T-ALL lineage switch and possible implications for treatment selection.

[Clinical features and prognosis of pediatric acute megakaryocytic leukemia].

OBJECTIVE: To study the clinical features and prognosis of children with acute megakaryocytic leukemia (AMKL) and the clinical effect of acute myeloid leukemia 03 (AML03) regimen for the treatment of pediatric AMKL. METHODS: The clinical data were collected from 47 children with AMKL who were diagnosed from May 2011 to December 2019. The treatment outcomes and prognostic factors were analyzed. The Kaplan-Meier method and the log-rank test were used for survival analysis. RESULTS: Among the 47 children with AMKL, 22 with non-Down syndrome-AMKL were treated by the AML03 regimen, with a median follow-up time of 11.4 months. For the 22 non-Down syndrome-AMKL patients, the remission rate of bone marrow cytology was 85% and the negative rate of minimal residual disease (MRD) was 79% after induction Ⅱ, with a 2-year overall survival (OS) rate of (50±13)% and a 2-year event-free survival (EFS) rate of (40±12)%. The group with positive immunophenotypic marker CD56 had significantly lower 2-year EFS and OS rates than the group with negative CD56 (P < 0.05). The group without remission of bone marrow cytology after induction Ⅱ had significantly lower 2-year EFS and OS rates than the group with remission (P < 0.05). The group with positive MRD after induction Ⅱ had a significantly lower 2-year EFS rate than the group with negative MRD (P < 0.05). There was no significant difference in 2-year OS and EFS rates between the patients with transplantation and those without transplantation (P > 0.05). CONCLUSIONS: Children with AMKL tend to have a low remission rate and a poor prognosis. Positive immunophenotypic marker CD56, bone marrow cytology during early treatment response, and MRD results are important factors influencing the prognosis. Allogeneic hematopoietic stem cell transplantation has no significant effect on the prognosis of AMKL.

Salvage Cord Blood Transplantation for Sustained Remission of Acute Megakaryoblastic Leukemia That Relapsed Early after Myeloablative Transplantation.

Acute megakaryoblastic leukemia (AMKL) is a rare subtype of acute myeloid leukemia accompanied by an aggressive clinical course and dismal prognosis. We herein report a case of AMKL preceded by mediastinal germ cell tumor that relapsed early after allogeneic hematopoietic stem cell transplantation with myeloablative conditioning but was successfully treated using salvage cord blood transplantation (CBT) with reduced-intensity conditioning. Although several serious complications developed, sustained remission with a favorable general condition was ultimately achieved. Although an optimal therapeutic strategy remains to be established, the graft-versus-leukemia effect of CBT may be promising, even for the treatment of refractory AMKL.

Outcome and Prognostic Features in Pediatric Acute Megakaryoblastic Leukemia Without Down Syndrome: A Retrospective Study in China.

BACKGROUND: Acute megakaryoblastic leukemia (AMKL) is a biologically heterogeneous subtype of acute myeloid leukemia that originates from megakaryocytes. Patients with AMKL with non-Down syndrome (DS) had a poorer prognosis. However, clear prognostic indicators and treatment recommendations for this subgroup remain controversial. PATIENTS AND METHODS: Herein, we performed a retrospective study on 40 patients (age ≤ 18 years) with non-Down syndrome AMKL at our institution. We assessed the effect of different prognostic factors, such as their cytogenetic abnormalities, early treatment response, and the role of hematopoietic stem cell transplantation (HSCT) as post-remission treatment on the outcomes. RESULTS: The complete remission (CR) rate of the patients was 57.9% and 81.1%, respectively, at the end of induction therapy 1 and 2. The overall survival (OS) and event-free survival rates at 2 years were 41% ± 13% and 41% ± 10%, respectively. An analysis of the cytogenetic features showed that patients with +21 or hyperdiploid (> 50 chromosomes) had significantly better OS than those in other cytogenetic subgroups (Plog-rank = .048 and Plog-rank = .040, respectively). Besides cytogenetics, an excellent early treatment response (CR and minimal residual disease < 1% after induction therapy 1) also provided a significant survival benefit in univariate analysis in our study. However, multivariate analysis indicated that allogeneic HSCT was the only independent prognostic marker (relative risk, 11.192; 95% confidence interval, 2.045-61.241; P = .005 for OS and relative risk, 5.400; 95% confidence interval, 1.635-17.832; P = .006 for event-free survival, respectively). CONCLUSION: AMKL in patients with non-Down syndrome has a poor outcome. With poor OS but CR rates comparable with other acute myeloid leukemia subtypes, allogenic HSCT may be a better option for post-remission therapy than conventional chemotherapy, especially for those having a poor response to induction therapy.

Clinical Characteristics and Prognosis of 27 Patients with Childhood Acute Megakaryoblastic Leukemia.

BACKGROUND The aim of this study was to investigate the clinical features and prognostic factors of childhood acute megakaryoblastic leukemia (AMKL). MATERIAL AND METHODS The data of 27 cases of childhood AMKL admitted from November 2009 to July 2018 were retrospectively analyzed. The survival analysis and prognostic factors were analyzed by Kaplan-Meier method. RESULTS The median follow-up time was 26.4 months in 27 cases, and the complete response rate was 92.31% after 2 chemotherapy courses. Eight patients underwent bone marrow transplantation after 3-6 courses. Five patients died after transplantation, 4 of whom died due to recurrence after transplantation. Of the 27 patients, 10 developed recurrence (37.04%), and 8/10 had recurrence within 1 year. The 3-year overall survival rate and disease-free survival rates were (47±12)% and (36±14)%, respectively. Of the 27 AMKL cases, the 3 with Down syndrome (DS-AMKL) all survived after treatment, and the 3-year overall survival rate was 100%. However, of the other 24 AMKL patients without Down syndrome (non-DS-AMKL), 6 died and 6 abandoned treatment, and the 3-year overall survival rate was only 50%. Univariate analysis showed that 3-year overall survival rate was not correlated to gender, age, number of newly diagnosed white blood cells, karyotype, remission after 2 courses of treatment, and transplant after 3 courses of treatment of childhood AMKL cases. Nevertheless, recurrence and remission after 2 courses of treatment were significantly correlated with 3-year overall survival rate. CONCLUSIONS Children with non-DS-AMKL have a high degree of malignancy and are prone to early recurrence with a poor prognosis, whereas the prognosis of DS-AMKL is relatively good. Recurrence after treatment and remission after 2 courses of treatment are important factors influencing the prognosis of childhood AMKL. Recurrence after transplantation is the leading cause of death in transplantation patients.

Human models of NUP98-KDM5A megakaryocytic leukemia in mice contribute to uncovering new biomarkers and therapeutic vulnerabilities.

Acute megakaryoblastic leukemia (AMKL) represents ∼10% of pediatric acute myeloid leukemia cases and typically affects young children (<3 years of age). It remains plagued with extremely poor treatment outcomes (<40% cure rates), mostly due to primary chemotherapy refractory disease and/or early relapse. Recurrent and mutually exclusive chimeric fusion oncogenes have been detected in 60% to 70% of cases and include nucleoporin 98 (NUP98) gene rearrangements, most commonly NUP98-KDM5A. Human models of NUP98-KDM5A-driven AMKL capable of faithfully recapitulating the disease have been lacking, and patient samples are rare, further limiting biomarkers and drug discovery. To overcome these impediments, we overexpressed NUP98-KDM5A in human cord blood hematopoietic stem and progenitor cells using a lentiviral-based approach to create physiopathologically relevant disease models. The NUP98-KDM5A fusion oncogene was a potent inducer of maturation arrest, sustaining long-term proliferative and progenitor capacities of engineered cells in optimized culture conditions. Adoptive transfer of NUP98-KDM5A-transformed cells into immunodeficient mice led to multiple subtypes of leukemia, including AMKL, that phenocopy human disease phenotypically and molecularly. The integrative molecular characterization of synthetic and patient NUP98-KDM5A AMKL samples revealed SELP, MPIG6B, and NEO1 as distinctive and novel disease biomarkers. Transcriptomic and proteomic analyses pointed to upregulation of the JAK-STAT signaling pathway in the model AMKL. Both synthetic models and patient-derived xenografts of NUP98-rearranged AMKL showed in vitro therapeutic vulnerability to ruxolitinib, a clinically approved JAK2 inhibitor. Overall, synthetic human AMKL models contribute to defining functional dependencies of rare genotypes of high-fatality pediatric leukemia, which lack effective and rationally designed treatments.

Establishment of a Parvovirus B19 NS1-Expressing Recombinant Adenoviral Vector for Killing Megakaryocytic Leukemia Cells.

Adenoviral viral vectors have been widely used for gene-based therapeutics, but commonly used serotype 5 shows poor transduction efficiency into hematopoietic cells. In this study, we aimed to generate a recombinant adenovirus serotype 5 (rAd5) vector that has a high efficiency in gene transfer to megakaryocytic leukemic cells with anticancer potential. We first modified the rAd5 backbone vector with a chimeric fiber gene of Ad5 and Ad11p (rAd5F11p) to increase the gene delivery efficiency. Then, the nonstructural protein NS1 of human parvovirus B19 (B19V), which induces cell cycle arrest at the G2/M phase and apoptosis, was cloned into the adenoviral shuttle vector. As the expression of parvoviral NS1 protein inhibited Ad replication and production, we engineered the cytomegalovirus (CMV) promoter, which governs NS1 expression, with two tetracycline operator elements (TetO2). Transfection of the rAd5F11p proviral vectors in Tet repressor-expressing T-REx-293 cells produced rAd in a large quantity. We further evaluated this chimeric rAd5F11p vector in gene delivery in human leukemic cells, UT7/Epo-S1. Strikingly, the novel rAd5F11p-B19NS1-GFP vector, exhibited a transduction efficiency much higher than the original vector, rAd5-B19NS1-GFP, in UT7/Epo-S1 cells, in particular, when they were transduced at a relatively low multiplicity of infection (100 viral genome copies/cell). After the transduction of rAd5F11p-B19NS1-GFP, over 90% of the UT7/Epo-S1 cells were arrested at the G2/M phase, and approximately 40%-50% of the cells were undergoing apoptosis, suggesting the novel rAd5F11P-B19NS1-GFP vector holds a promise in therapeutic potentials of megakaryocytic leukemia.

The changing scenario of non-Down syndrome acute megakaryoblastic leukemia in children.

Pediatric non-Down-syndrome acute megakaryoblastic leukemia (non-DS-AMKL) is a heterogeneous subtype of leukemia that has historically been associated with poor prognosis. Until the advent of large-scale genomic sequencing, the management of patients with non-DS-AMKL was very difficult due to the absence of reliable biological prognostic markers. The sequencing of large cohort of pediatric non-DS-AMKL samples led to the discovery of novel genetic aberrations, including high-frequency fusions, such as CBFA2T3-GLIS2 and NUP98-KDM5 A, as well as less frequent aberrations, such as HOX rearrangements. These new insights into the genetic landscape of pediatric non-DS-AMKL has allowed refining the risk-group stratification, leading to important changes in the prognostic scenario of these patients. This review summarizes the most important molecular pathogenic mechanisms of pediatric non-DS-AMKL. A critical discussion on how novel genetic abnormalities have refined the risk profile assessment and changed the management of these patients in clinical practice is also provided.

Molecular features, prognosis, and novel treatment options for pediatric acute megakaryoblastic leukemia.

INTRODUCTION: Acute megakaryoblastic leukemia (AMegL) is a rare hematological neoplasm most often diagnosed in children and is commonly associated with Down's syndrome (DS). Although AMegLs are specifically characterized and typically diagnosed by megakaryoblastic expansion, recent advancements in molecular analysis have highlighted the heterogeneity of this disease, with specific cytogenic and genetic alterations characterizing different disease subtypes. Areas covered: This review will focus on describing recurrent molecular variations in both DS and non-DS pediatric AMegL, their role in promoting leukemogenesis, their association with different clinical aspects and prognosis, and finally, their influence on future treatment strategies with a number of specific drugs beyond conventional chemotherapy already under development. Expert opinion: Deep understanding of the genetic and molecular landscape of AMegL will lead to better and more precise disease classification in terms of diagnosis, prognosis, and possible targeted therapies. Development of new therapeutic approaches based on these molecular characteristics will hopefully improve AMegL patient outcomes.

Late mortality and morbidity among long-term leukemia survivors with Down syndrome: A nationwide population-based cohort study.

BACKGROUND: Late health consequences of treatment for childhood leukemia are well documented. Although individuals with Down syndrome (DS) have a substantially increased risk of leukemia, information on late effects in this group is almost nonexistent. The aim of this study was to evaluate the mortality and morbidity among 5-year leukemia survivors with DS. PROCEDURE: We compared 5-year leukemia survivors with leukemia-free individuals with DS. All individuals born with DS in Denmark between 1960 and 2007 and in Sweden between 1973 and 2009 were included. Long-term morbidity was estimated by comparing hospitalization rates between survivors and leukemia-free individuals. RESULTS: In total, we found 6,705 individuals with DS, 84 of whom were 5-year survivors of leukemia. Survivors had a higher risk of death (hazard ratio [HR] 5.9; 95% confidence interval [CI]: 2.7-13) compared with leukemia-free individuals. All deaths (n = 7) among 5-year leukemia survivors were due to relapse. Survivors had a higher hospitalization rate (HR 4.4; 95% CI: 3.1-6.2). However, most of these hospitalizations were due to relapse. Censoring individuals who either had a relapse or were being treated for a relapse more than 5 years from the initial diagnosis (n = 9) attenuated the association (HR 1.4; 95% CI: 1.0-2.1). CONCLUSION: In this study, we found that relapse was the main reason for death and hospitalization among leukemia survivors with DS, and not late effects. These results are reassuring for individuals treated for DS associated with leukemia and their parents.

HLA analysis of Mexican candidates for bone marrow transplantation and probability of finding compatible related donors.

INTRODUCTION: Oncohematological disorders are the main cause of morbidity in the Mexican population from 1 to 19 years old, where megakaryoblastic and promyelocitic leukemias are more frequent. Considering that the success of a transplant is multifactorial, the criterion of compatibility in the HLA system is crucial and even more so when the source of HSC is bone marrow. OBJECTIVE: To determine the frequency of the HLA genotype in Mexican candidates who require a bone marrow transplant from related donors and the probability to find donors. MATERIALS AND METHODS: One hundred twenty-six candidates for bone marrow transplant and related donors were tested for HLA class I (-A*, -B* alleles) and class II (-DRB1* allele) in intermediate-resolution, as the first phase in the choice of the possible donor. The criteria to identify donors were determined by antigen-matched in each HLA haplotype as follows: 4/6, 5/6 and 6/6 at the HLA-A*, HLA-B*, and HLA-DRB1* alleles. RESULTS: Of all the candidates analyzed, 57.93%, at least one bone marrow donor was identified; in 53 cases, no donor was found. The average size of the families was 4.79 ±â€¯1.06 members. A higher percentage of compatibility with grade 6/6 (31.6%) was identified with brothers, followed by sisters in 25.3%. The probability to find at least one compatible potential donor was 1.51 ±â€¯0.92 donors. CONCLUSION: In the first phase to select donors, Mexican patients studied in this work, have a compatible donor, however the grade of resolution test influenced in the probability identified.

Acute megakaryoblastic leukemia (excluding Down syndrome) remains an acute myeloid subgroup with inferior outcome in the French ELAM02 trial.

We report the outcome of 27 children with de novo acute megakaryoblastic leukemia (AMKL) (excluding Down syndrome) enrolled in the French multicenter prospective study ELAM02 (2005-2011). There was no difference in gender, initial leukocyte count, CNS involvement, and complete remission rate (88.9%), as compared to other acute myeloid leukemia (AML) subtypes. AMKL patients had a significantly poorer outcome (5-year overall survival 54% [CI 95% 33%-71%] than children with other AML subtypes (5-year overall survival 73% [CI 95% 68%-77%] p = 0.02). Gender, age, CNS leukemia, hyperleukocytosis, complete remission or cytogenetic subgroups were not significant prognostic factors of disease-free survival. AMKL (excluding Down syndrom) remains an AML subgroup with inferior outcome.

Post-allogeneic stem cell transplant extramedullary relapse of acute megakaryoblastic leukemia initially detected by elevated WT1 mRNA levels in peripheral blood.

An 18-year-old male was admitted to our hospital for fever, and was diagnosed with acute megakaryoblastic leukemia (AML M7) based on the presence of CD42a and CD61 positive myeloblasts in peripheral blood (PB). Induction chemotherapy at our hospital resulted in complete remission (CR). Subsequently, he underwent unrelated HLA-DR one locus-mismatched allogeneic bone marrow (BM) transplantation. Although CR was maintained without development of graft-versus-host disease (GvHD), the WT1 mRNA level in PB was elevated on post-transplant day 134. As BM aspiration performed 1 week later confirmed maintenance of CR, and because the WT1 mRNA level in BM was not high in comparison with PB, we suspected extramedullary relapse. PET-CT demonstrated a thymic tumor and a gastric tumor with abnormal accumulation of FDG, and biopsy confirmed both to be extramedullary relapse of AML M7. Induction chemotherapy following local radiation therapy achieved a second CR, following which he received HLA haploidentical peripheral blood stem cell transplantation on day 256 after the first transplant. The patient is currently surviving free from both relapse and GvHD. High WT1 mRNA levels in PB as compared with BM should raise suspicion of extramedullary relapse, and PET-CT is very useful for whole body evaluation in such cases.