Childhood Myelodysplastic Syndrome Research Articles

Clinical features and prognostic factors of advanced myelodysplastic syndromes in children

Objective: To investigate the clinical features and prognostic factors of advanced myelodysplastic syndromes (MDS) in children. Methods: Clinical data of children diagnosed with advanced MDS in the Hematology & Blood Diseases Hospital, Chinese Academy of Medical Sciences, between September 2009 and April 2022 were retrospectively collected. Follow-up assessments were performed through telephone interviews and the review of medical records until May 1, 2023. The clinical features of children with advanced MDS were summarized by analyzing chromosomal karyotype tests, second-generation gene sequencing results. Multivariate Cox regression analysis was used to investigate the prognostic factors of advanced MDS in children. Results: A total of 69 children, comprising 49 males and 20 females, aged [M (Q1, Q3)] 8 (5, 10) years, were enrolled in the study. Sixty-seven cases underwent chromosomal karyotype testing, of which 42 cases (62.7%) had abnormal karyotypes, with monosomy 7 the most common in 17 cases (25.4%). Forty-three cases underwent next-generation sequencing, with mutations in the SETBP1, NRAS, PTPN11 and RUNX1 genes more common, identified in 12 cases (27.9%), 9 cases (20.9%), 8 cases(18.6%), and 8 cases(18.6%), respectively. The follow-up time [M (Q1, Q3)] was 26 (13, 56) months and the 5-year overall survival rate was 56%(95%CI: 44.4%-70.5%). The 5-year overall survival rate for children who underwent hematopoietic stem cell transplantation (HSCT) was higher than that of children who did not undergo HSCT (73.9% vs 29.1%, P<0.001). HSCT (HR=0.118, 95%CI: 0.037-0.372, P<0.001) was a protective factor for the overall survival rate of children with advanced MDS. Serum ferritin level>356.3 μg/L (HR=6.497, 95%CI: 2.068-20.415, P=0.001) and moderate to severe splenomegaly (HR=4.075, 95%CI: 1.174-14.141, P=0.027) were risk factors for the overall survival rate of children with advanced MDS. Conclusions: Monosomy 7 was the most common abnormal karyotype and SETBP1 was the gene that had the highest mutation frequency in children with advanced MDS. HSCT, increased ferritin and moderate to severe splenomegaly are prognostic factors influencing the overall survival rate of children with advanced MDS.

Childhood myelodysplastic syndromes: Is cytoreductive therapy useful before allogeneic hematopoietic stem cell transplantation?

For most patients with childhood myelodysplastic syndrome (cMDS), allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains the only curative option. In the case of increased blasts (cMDS-IB), the benefit of pretransplant cytoreductive therapy remains controversial. In this multicenter retrospective study, the outcomes of all French children who underwent allo-HSCT for cMDS reported in the SFGM-TC registrybetween 2000 and 2020 were analyzed (n = 84). The median age at transplantation was 10.2 years. HSCT was performed from matched sibling donors (MSD) in 29% of the cases, matched unrelated donors (MUD) in 44%, haploidentical in 6%, and cord blood in 21%. Myeloablative conditioning was used in 91% of cases. Forty-eight percent of patients presented with cMDS-IB at diagnosis (median BM blasts: 8%). Among them, 50% received pretransplant cytoreductive therapy. Five-year overall survival (OS), cumulative incidence of nonrelapse mortality (NRM), and relapse were 67%, 26%, and 12%, respectively. Six-month cumulative incidence of grade II-IV acute graft-versus-host disease was 46%. Considering the whole cohort, age under 12, busulfan/cyclophosphamide/melphalan conditioning or MUD were associated with poorer 5-year OS. In the cMDS-IB subgroup, pretransplant cytoreductive therapy was associated with a better OS in univariate analysis. This seems to be mainly due to a decreased NRMsince no impact on the incidence of relapse was observed. Overall, those data may argue in favor of cytoreduction for cMDS-IB. They need to be confirmed on a larger scale and prospectively.

Childhood myelodysplastic syndrome with increased fibrosis in association with neurofibromatosis 1: A case report

Childhood myelodysplastic syndrome with increased fibrosis in association with neurofibromatosis 1: A case report

Persistent or New Cytopenias Predict Relapse Better than Routine Bone Marrow Aspirate Evaluations After Hematopoietic Cell Transplantation for Acute Leukemia or Myelodysplastic Syndrome in Children and Young Adult Patients

The clinical value of serial routine bone marrow aspirates (rBMAs) in the first year after allogeneic hematopoietic cell transplantation (alloHCT) to detect or predict relapse of acute leukemia (AL) and myelodysplastic syndrome (MDS) in pediatric and young adult patients is unclear. The purpose of this analysis was to determine if assessment of minimal residual disease (MRD) by multiparameter flow cytometry (MFC, MFC-MRD) or donor chimerism (DC) in rBMAs or serial complete blood counts (CBCs) done in the year after alloHCT predicted relapse of AL or MDS in pediatric and young adult patients. We completed a retrospective analysis of patients with AL or MDS who had rBMAs performed after alloHCT between January 2012 and June 2018. Bone marrow (BM) was evaluated at approximately 3, 6, and 12 months for disease recurrence by morphology, MFC-MRD, and percent DC by short tandem repeat molecular testing. CBCs were performed at every clinic visit. The main outcome of interest was an assessment of whether MFC-MRD or DC in rBMAs or serial CBCs done in the year after alloHCT predicted relapse in AL or MDS pediatric and young adult patients. A total of 121 recipients with a median age of 13 years (range 1 to 32) were included: 108 with AL and, 13 with MDS. A total of 423 rBMAs (median 3; 0 to 13) were performed. Relapse at 2 years was 23% (95% CI: 16% to 31%) and at 5 years 25% (95% CI: 18% to 33%). One hundred fifty-four of 157 (98%) rBMAs evaluated for MRD by MFC were negative and did not preclude subsequent relapse. Additionally, low DC (<95%) did not predict relapse and high DC (≥95%) did not preclude relapse. For patients alive without relapse at 1 year, BM DC (P = .74) and peripheral T-cell DC (P = .93) did not predict relapse. Six patients with low-level T-cell and/or BM DC had a total of 8 to 20 BM evaluations, none of these patients relapsed. However, CBC results were informative for relapse; 28 of 31 (90%) relapse patients presented with an abnormal CBC with peripheral blood (PB) blasts (16 patients), cytopenias (9 patients), or extramedullary disease (EMD, 3 patients). Two patients with BM blasts >5% on rBMA had circulating blasts within 5 weeks of rBMA. Neutropenia (ANC <1.5 K/mcl) at 1 year was predictive of relapse (P = .01). Neutropenia and thrombocytopenia (<160 K/mcl) were predictive of disease-free survival (DFS) with inferior DFS for ANC <1.5 K/mcl, P = .001, or platelet count <160 K/mcl (P = .04). These results demonstrate rBMAs after alloHCT assessed for MRD by MFC and/or for level of DC are poor predictors for relapse in pediatric and young adult patients with AL or MDS. Relapse in these patients presents with PB blasts, cytopenias, or EMD. ANC and platelet count at 1-year were highly predictive for DFS.

Decitabine-containing conditioning improved outcomes for children with higher-risk myelodysplastic syndrome undergoing allogeneic hematopoietic stem cell transplantation.

Myelodysplastic syndrome (MDS) is a rare clonal hematopoietic disorder in children. The risk stratification system and treatment strategy for adults are unfit for children. The role of hypomethylating agents (HMAs) in higher-risk childhood MDS has not been identified. This study aimed to investigate the outcomes of hematopoietic stem cell transplantation (HSCT) in children with higher-risk MDS at one single center. A retrospective study was conducted in children with higher-risk MDS undergoing HSCT between September 2019 and March 2023 at Blood Diseases Hospital CAMS. The clinical characteristics and transplantation information were reviewed and analyzed. A total of 27 patients were analyzed, including 11 with MDS with excess blasts (MDS-EB), 14 with MDS-EB in transformation (MDS-EBt) or acute myeloid leukemia with myelodysplasia-related changes (AML-MRC), and 2 with therapy-related MDS/AML (t-MDS/AML). Eight patients harbored monosomy 7. Before transplantation, induction therapy was administered to 25 patients, and 19 of them achieved bone marrow blasts <5% before HSCT. The stem cell source was unmanipulated-related bone marrow or peripheral blood stem cells for nineteen patients and unrelated cord blood for eight. All patients received decitabine-containing and Bu/Cy-based myeloablative conditioning; 26 patients achieved initial engraftment. The cumulative incidences of grade II-IV and grade III-IV acute graft-versus-host disease (GvHD) at 100 days were 65.4% and 42.3%, respectively. The incidence of cGvHD was 38.5%. The median follow-up was 26 (range 4-49) months after transplantation. By the end of follow-up, two patients died of complications and two died of disease progression. The probability of 3-year overall survival (OS) was 84.8% (95%CI, 71.1 to 98.5%). In summary, decitabine-containing myeloablative conditioning resulted in excellent outcomes for children with higher-risk MDS undergoing allogeneic HSCT.

The role of genetic factors in pediatric myelodysplastic syndromes with different outcomes

BackgroundPediatric myelodysplastic syndromes (MDS) are rare disorders with an unrevealed pathogenesis. Our aim is to explore the role of genetic factors in the pathogenesis of MDS in children with different outcomes and to discover the correlation between genetic features and clinical outcomes as well as disease characteristics.MethodsWe conducted an analysis of archived genetic data from 26 patients diagnosed with pediatric MDS at our institution between 2015 and 2021, examining the association between different genetic characteristics and clinical manifestations as well as prognosis. Additionally, We presented three cases with distinct genetic background and outcomes as examples to elaborate the role of genetic factors in pediatric MDS with different prognoses.ResultsGenetic variations were detected in 13 out of the 26 patients, including 8 patients with co-occurrence of somatic and germline mutations (CSGMs) and 5 patients with somatic mutations alone. Our analysis revealed that advanced MDS (4/8, 50% vs. 1/5, 20% and 4/11, 36.4%), PD (3/8, 37.5% vs. 1/5, 20% and 1/11 9.1%), and TD (6/8, 75% vs. 2/5, 40% and 2/11, 18.2%) were more common in patients with CSGMs than those with somatic mutations alone or without any mutations. We also found out in our study that 8 patients with CSGMs had evidently different clinical outcomes, and we presented 3 of them as examples for elaboration. Case 1 with germline and somatic mutations of unknown significance had a relatively slow disease course and a good prognosis. Case 2 with compound heterozygous germline SBDS variants and somatic mutations like del20q had a stable disease course and a reversed outcome. Case 3 with a germline GATA2 variant and somatic mutations including − 7 had a rapidly progressive disease course and a worst prognosis.ConclusionOur findings indicate that genetic background of pediatric MDS is closely linked with disease characteristics as well as outcomes and that CSGMs may lead to disease progression. It should be emphasized that the interaction between certain germline variants and somatic mutations, such as SBDS and del20q, may result in hematopoietic stem cell adaptation (improved hematopoiesis) and reversed clinical outcomes, which can facilitate the development of targeted therapy.

The Efficacy and Prognosis of Advanced Myelodysplastic Syndrome in Children

Pediatric myelodysplastic syndrome (MDS) is a clonal hematopoietic stem cell neoplasm with an annual incidence of 1-4 cases/million. The low incidence of advanced MDS in children and poor prognosis attract our attention. However, there are limited reports on the scheme and efficacy of pediatric advanced MDS. In this study, we retrospectively analyzed the efficacy of chemotherapy in pediatric advanced MDS and assessed the prognosis of patients. According to 2016 World Health Organization (WHO) classification of haematolymphoid tumours, 30 newly diagnosed pediatric advanced MDS patients during Dec 2007 to Apr 2022 from our single center were selected as the research object. The clinical data and prognosis were analyzed. The median age of patients is 8 years (range: 1-15years). The median bone marrow blast is 15.75% (range: 5-29.5%), while the median peripheral blood blast is 4% (range: 0-29%). Cytogenetic analysis was available for 29 patients, 69% (20/29) cases had abnormal karyotype. Monosomy 7 (37.9%) was the most common cytogenetic abnormality. Out of the total, 7 patients were treated with CAG/HAG regimen (C: aclarubicin 6mg d1-14, H: homoharringtonine 1mg/m 2d1-14, A: cytarabine 10mg/m 2 q12h d1-14, and G: Granulocyte Colony-stimulating Factor 200mg/m 2 d1-14 ), 8 patients with decitabine (20mg/m 2 d1-5), 11 patients with decitabine and CAG/HAG, 4 patients with AML-like chemotherapy (Daunorubicin+cytarabine+etoposide ) or other. The evaluation of response of therapy was available in 25 patients, 5 cases (20%) in partial remission (PR), 11 cases (44%) in complete remission (CR), 9 cases in(36%)non-remission (NR). The total response rate of chemotherapy is 60%, with CAG/HAG therapy 33%, decitabine therapy 43%, combined CAG/HAG and decitabine therapy 78%, AML-like chemotherapy 100%. The total complete remission rate of chemotherapy is 44%, with CAG/HAG therapy 17%, decitabine therapy 43%, combined CAG/HAG and decitabine therapy 56%, AML-like chemotherapy 67%. Patients receiving CAG/HAG in combination with decitabine had higher response rates compared to CAG/HAG or decitabine alone (OR=17.5, 95% CI 1.2-250.3, P=0.035). With a median follow-up of 20 months (range: 1-158months), 23 patients received HSCT after chemotherapy, and they had a higher 2-year overall survival rate compared to those who did not undergo transplantation (86% vs 0%, p&amp;lt;0.001). Decitabine combined with CAG/HAG improve the response rate of advanced pediatric MDS. Chemotherapy bridged hematopoietic stem cell transplantation significantly improves the prognosis of advanced pediatric MDS.

Impaired Efficacy and Durability of Hematopoietic Stem Cell Engraftment Caused By Samd9l-Deficiency within Bone Marrow Niches

Germline mutations in the SAMD9 and SAMD9L (SAMD9/L) genes on chromosome 7q drive both childhood myelodysplastic syndrome (MDS)/secondary acute myeloid leukemia (sAML) associated with monosomy 7, and adult-onset MDS/sAML associated with distinct somatic genetic alterations. The ortholog for SAMD9/L in mice is Samd9l. Gain of Function (GoF) and Loss of Function (LoF) Samd9l alleles predispose to MDS at distinct ages. LoF models show that Samd9l-deficient mice, like humans, are more likely to develop MDS during adulthood, while GoF models result in early onset bone marrow (BM) dysfunction and MDS/sAML. Hematopoietic stem cell transplantation (HSCT) is the only curative treatment for bone marrow failure (BMF), MDS, and AML arising from germline genetic syndromes. Our previous research demonstrated that deficits in host BM microenvironment (ME) niches contribute to hematopoietic failure and poor HSC engraftment in murine models of many MDS predisposition syndromes associated with BMF. As we have observed clinical cases where poor engraftment impaired outcomes in patients with SAMD9/L mutations, we recently hypothesized, BM niche functions critical to facilitating HSC engraftment may be impaired due to niche-intrinsic deficits caused by SAMD9/L mutations. Herein, we present data testing this hypothesis, demonstrating Samd9l deficiency alters BM ME composition, extracellular matrix (ECM) regulation, and proinflammatory cytokine signaling resulting in impaired donor HSC engraftment after HSCT. We performed primary (1 ry) and secondary (2 ry) HSCT to model impacts of SAMD9/L deficiency on BM niche function during HSCT using WT ( Samd9l+/+), Samd9l+/-, and Samd9l-/- mice as HSCT recipients of healthy WT GFP + donor BM to measure the capacity of Samd9l LoF niches to engraft donor HSCs. To assess changes in niche composition and gene expression during HSCT, flow cytometry, multiplex ELISA, and RNASeq analysis were performed on WT, Samd9+/- and Samd9-/- mice. Compared to WT control niches, Samd9+/- and Samd9-/- niches exhibited impaired efficiency of donor HSC engraftment at 3 weeks post-1 ry HSCT, as measured by competitive 2 ry-HSCT performed with 1 ry recipient BM harvested at this timepoint. Beyond 30 weeks post-2 ry-HSCT in this model, GFP + reconstitution of GR1 + myeloid, RBC's, and platelets was reduced by 25%, 18%, and 35% in 2 ry recipients of Samd9+/-1 ry recipient BM and by 26%, 28%, and 32% in 2 ry recipients of Samd9-/- 1 ry recipient BM. Durability of HSC engraftment by 8 months was even more significantly impaired in Samd9+/- and Samd9-/- niches, with Samd9-/- mice exhibiting low survival by this timepoint. Competitive 2 ry HSCT performed 8 months post-1 ry HSCT showed reduction in trilineage GFP + blood cells out to 24 weeks post 2 ry-HSCT, including reductions in GFP + Gr1 + myeloid cells by 50% and 83% in 2 ry recipients of Samd9l+/-and Samd9l-/-1 ry recipient BM, respectively, compared to control 1 ry recipient BM. Similar reductions in BM long-term HSC and Lin -Sca-1 +cKit + HSC/progenitor cells in 2 ry recipients of Samd9l-/-compared to Samd9l+/+ 1 ryrecipient BM 8 months post 1 ry-HSCT. Following TBI, Samd9l+/-and Samd9l-/- BM niches contained similar percentages of osteoprogenitors, mesenchymal stem cells, and endothelial cells compared to WT controls. Multiplex ELISA on BM plasma collected 48hrs post-TBI revealed that Samd9l+/-and Samd9l-/-deletion in the BM ME led to markedly reduced expression of IFN-γ (43% and 55% reduction in Samd9l+/-and Samd9l-/-), Eotaxin (33%/36%), GM-CSF (47%/47%), and IL-1a (48%/65%). In contrast, expression of niche cell extracts showed markedly increased levels of IL-17 (4 fold) and CXCL11 (1.4 fold) in Samd9l+/-and of IL-17 (5.3 fold) IL-12p70 (1.3 fold), and CXCL11 (1.5 fold) in Samd9l-/-, suggesting that aberrantly active Th17 responses caused by niche Samd9l deficiency may be responsible for impairing HSC function and maintenance post-HSCT. RNASeq analysis showed downregulation of ECM genes in both Samd9l-/-and Samd9l+/-models. Our data demonstrates BM niche function is impaired by Samd9l deficiency in a gene dosage-dependent manner. These deficits are associated with increased expression of a specific inflammatory cytokine pathway, suggesting that aberrant growth factor receptor recycling due to Samd9l deficiency may drive stress hematopoiesis and alter HSC cell fate decisions leading to failure of durable donor HSC maintenance post-HSCT.

Outcomes of Hematopoietic Cell Transplantation for Patients with Refractory Cytopenia with Multilineage Dysplasia: A Comparison Children with Adolescents and Young Adults

Background: The 2008 World Health Organization (WHO) classification proposed a new entity in childhood myelodysplastic syndrome (MDS), refractory cytopenia of childhood (RCC). The spectrum of patients with RCC is wide, ranging from patients with severe hypocellular bone marrow (BM) and mild dysplasia (hypocellular RCC) to those with normocellular BM and distinct dysplasia meeting the criteria for refractory cytopenia with multilineage dysplasia (RCMD) defined for adults with MDS. The term of RCMD was revised to MDS with multilineage dysplasia in the 2017 WHO classification. In Japan, children who meet the criteria for RCMD have been diagnosed as RCMD distinguished from hypocellular RCC. Although hematopoietic cell transplantation (HCT) is a curative treatment for RCMD in children, there have been few reports of the outcomes of HCT for children with RCMD. Patients and Methods: To clarify the outcomes of HCT for children with RCMD, we retrospectively analyzed the clinical data in children (&amp;lt;16 years) with RCMD who underwent the first HCT from 2010 to 2021 and registered in the Japan Society for Hematopoietic Cell Transplantation Registry, and compared with those in adolescents and young adults (AYA; ≥16, &amp;lt;40 years) with RCMD who underwent the first HCT during the same study period. During the study period, 195 patients with RCMD (children, 69; AYA, 126) underwent HCT. The stem cell source was BM in 138 (children, 58; AYA, 80), peripheral blood (PB) in 27 (children, 2; AYA, 25), and cord blood (CB) in 30 patients (children, 9; AYA, 21). Myeloablative conditioning (MAC) regimen was defined as the use of total body irradiation (TBI) ≥8 Gy (MAC-TBI) and the administration of busulfan (BU) &amp;gt;8 mg/kg (MAC-BU). All other regimens were included in reduced intensity conditioning (RIC) regimen. Results: We retrospectively analyzed 195 patients with RCMD (male, 105; female, 90). The median age at HCT was 8 years (range, 0-15) in children and 29 years (range, 16-39) in AYA. Of the 195 patients, 20 (29%) and 52 (41%) had abnormal karyotypes in children and AYA, respectively. Of the patients who underwent HCT, 68 were from related (children, 22; AYA, 46), and 127 from unrelated (children, 47; AYA, 80) donors. MAC-BU was used for 46 (children, 9; AYA, 37), MAC-TBI for 51 (children, 1; AYA, 50), and RIC for 98 (children, 59; AYA, 39) patients. Of the 195 patients, 8 (children, 3; AYA, 5) developed primary graft failure, 16 (children, 5; AYA, 11) secondary graft failure, 10 (children, 3; AYA, 7) disease relapse, and 11 (children, 2; AYA, 9) secondary tumor. Twenty-four (children, 5; AYA, 19) patients died of HCT-related complications and four AYA of disease relapse. The 5-year overall survival (OS) rate was significantly higher in children (93%) than in AYA (82%) (p = 0.04). The 5-year event-free survival (EFS) rate was 76% in children and 64% in AYA. The 1-month cumulative incidence (CI) of neutrophil engraftment was 93% in children and 94% in AYA. The 5-year CI of relapse was 6% in AYA and 2% in children. The 5-year CI of treatment-related mortality (TRM) was 16% in AYA and 7% in children. The 5-year CI of graft failure was 12% in children and 12% in AYA. The 3-year CI of chronic graft-versus-host disease (GVHD) was significantly higher in AYA (37%) than in children (21%) (p = 0.04), while there was no difference in the 3-month CI of acute GVHD (gradeⅡ-Ⅳ) between children (35%) and AYA (39%). In children, the 5-year OS and EFS rates were significantly lower in CB (67% and 42%) than in BM/PB (97% and 81%) (p &amp;lt; 0.01 and p &amp;lt; 0.01), respectively, while the 5-year OS and EFS rates were not different between CB (91% and 76%) and BM/PB (80% and 62%) in AYA, respectively. Of the 59 children who underwent HCT using RIC, 43 without abnormal karyotypes showed 95% and 16 with abnormal karyotypes showed 88% in the 5-year OS rate. Even in AYA, there was no difference in the 5-year OS rate between RIC and MAC in both groups with (RIC, n = 14, 76%; MAC, n =38, 72%) and without (RIC, n = 25, 81%; MAC, n = 49, 90%) abnormal karyotypes. Conclusions: HCT for children with RCMD showed better OS rate than that for AYA with RCMD. HCT using RIC regimen provided good outcomes for RCMD in children with or without abnormal karyotypes. Even in AYA, HCT using RIC regimen showed OS rate comparable to MAC regimen in both groups with and without abnormal karyotypes.

Development of MDS in Pediatric Patients with GATA2 Deficiency: Increased Histone Trimethylation and Deregulated Apoptosis as Potential Drivers of Transformation

GATA2 deficiency is a heterogeneous, multisystem disorder associated with a high risk of developing myelodysplastic syndrome (MDS) and the progression to acute myeloid leukemia. The mechanisms underlying malignant transformation in GATA2 deficiency remain poorly understood, necessitating predictive markers to assess an individual’s risk of progression and guide therapeutic decisions. In this study, we performed a systematic analysis of bone marrow biopsies from 57 pediatric MDS patients. Focusing on hematopoiesis and the hematopoietic niche, including its microenvironment, we used multiplex immunofluorescence combined with multispectral imaging, gene expression profiling, and multiplex RNA in situ hybridization. Patients with a GATA2 deficiency exhibited a dysregulated GATA2 transcriptional network. Disease progression (GATA2-EB, n = 6) was associated with increased GATA2 mRNA levels, restored expression of the GATA2 target EZH2, and increased H3K27me3. GATA2-EB was further characterized by the high expression of the anti-apoptotic protein BCL2, a feature absent in children with a GATA2 deficiency and refractory cytopenia of childhood (GATA2-RCC, n = 24) or other pediatric MDS subgroups (RCC, n = 17; MDS-EB, n = 10). The multispectral imaging analysis of additional BCL2 family members revealed significantly elevated Mediators of Apoptosis Combinatorial (MAC) scores in GATA2-EB patients. Taken together, our findings highlight the potential drivers of disease progression in GATA2 deficiency, particularly increased histone trimethylation and dysregulated apoptosis. Furthermore, upregulated BCL2 and EZH2 and increased MAC scores provide a strong rationale for the use of venetoclax and azacitidine in therapeutic regimens for GATA2-EB.

Abstract A51: Divergent effects of MDS predisposing SAMD9L point mutations, in humans, mice, and cellular models

Abstract We previously showed that germline SAMD9 and SAMD9L (SAMD9/9L) disorders are the most common predisposition to childhood myelodysplastic syndromes with bone marrow failure (BMF). Heterozygous mutations in both genes are growth inhibitory and undergo negative selection by acquiring compensatory rescue events in blood. Here, we describe the first report of SAMD9L genetic rescue occurring during embryonal development and resulting in germline triple-allelic mosaicism (1 wildtype (WT) and 2 mutant alleles), where only one mutant allele was transmitted to each of the two diseased children. In a family of 2 affected siblings with hypocellular BMF, the Index case carried germline heterozygous SAMD9L V1512M mutation and her brother was heterozygous for V1512L mutation. The clinical presentation for Index with V1512M was more severe compared to her brother with V1512L mutation. Genetic assessment of the parents showed the asymptomatic mother to be a triple-allelic mosaic, carrying WT SAMD9L allele at ~50% frequency in all tissues, while both V1512M and V1512L mutant alleles “competed” in their allelic distribution depending on the tissue origin. Single-cell DNA sequencing on her peripheral blood (PB) revealed 3 independent diploid clones: V1512M in 14%, V1512L in 68%, and WT (due to revertant UPD7q) in 18% of cells. Because her parents were SAMD9L WT, one of the mutations likely arose de novo and underwent failed embryonic rescue attempt leading to a second mutation. Towards studying the effect on hematopoiesis in vitro, we knocked in V1512M and V1512L mutations in inducible pluripotent stem cells (iPSC). For in vivo functional validation, we created constitutive mouse models with ortholog mutations (V1507M and V1507L). Mutant hematopoietic progenitor cells from iPSC had severely compromised proliferative capacity and yielded fewer erythroid and myeloid cells. This effect was more severe in V1512M vs. V1512L mutants. The divergent mutational phenotypes were also replicated in our mouse models: two-thirds (13/19) of the heterozygous V1507M (V1507Mhet) pups died before 4 weeks of age. In contrast, V1507Lhet mice had overall survival equal to WT mice, while one-third of homozygous V1507L (V1507Lhom) mice showed decreased survival post 19 weeks of age. At baseline, V1507Mhet mice showed severe growth retardation with multisystemic issues, which were absent in the V1507L mutant models. PB cytopenia (anemia, B-cell lymphopenia) though observed in both V1507Mhet and V1507Lhom mice, the degree of severity was high in the V1507Mhet than in the V1507Lhom model. Meanwhile, V1507Lhet mice had blood counts similar to WT. In summary, V1512M compared to V1512L mutation resulted in a more severe phenotype in all analyzed model systems. This observation showed how different mutational permutations of the same amino acid can exert divergent phenotypic effects in SAMD9L BMF disorder. Therefore, together with our genetic analysis, we could postulate that the V1512L mutation arose as a failed rescue attempt of V1512M during embryogenesis. Citation Format: Sushree S Sahoo, Charnise Goodings, Shondra M. Pruett-Miller, Maria A Lillo, Lei Han, Baranda Hansen, Ti-Cheng Chang, Tim Lammens, Mattias Hofmans, Marta Derecka, Barbara De Moerloose, Marcin W Wlodarski. Divergent effects of MDS predisposing SAMD9L point mutations, in humans, mice, and cellular models [abstract]. In: Proceedings of the AACR Special Conference: Acute Myeloid Leukemia and Myelodysplastic Syndrome; 2023 Jan 23-25; Austin, TX. Philadelphia (PA): AACR; Blood Cancer Discov 2023;4(3_Suppl):Abstract nr A51.

The Clinical Spectrum, Diagnosis, and Management of GATA2 Deficiency.

Hereditary myeloid malignancy syndromes (HMMSs) are rare but are becoming increasingly significant in clinical practice. One of the most well-known syndromes within this group is GATA2 deficiency. The GATA2 gene encodes a zinc finger transcription factor essential for normal hematopoiesis. Insufficient expression and function of this gene as a result of germinal mutations underlie distinct clinical presentations, including childhood myelodysplastic syndrome and acute myeloid leukemia, in which the acquisition of additional molecular somatic abnormalities can lead to variable outcomes. The only curative treatment for this syndrome is allogeneic hematopoietic stem cell transplantation, which should be performed before irreversible organ damage happens. In this review, we will examine the structural characteristics of the GATA2 gene, its physiological and pathological functions, how GATA2 genetic mutations contribute to myeloid neoplasms, and other potential clinical manifestations. Finally, we will provide an overview of current therapeutic options, including recent transplantation strategies.

Analysis of Clinical Characteristics of Childhood Myelodysplastic Syndrome with Increased Blasts (cMDS-IB)

Analysis of Clinical Characteristics of Childhood Myelodysplastic Syndrome with Increased Blasts (cMDS-IB)

DNA ligase IV dificiency with elevated serum IgG levels suspected to have myelodysplastic syndrome: a case report

BackgroundLigase IV (LIG4) dificiency is a very rare clinical syndrome with around 50 cases reported to date. This syndrome is caused by biallelic pathogenic variants in the LIG4 gene, which cause DNA damage repair disorders, mainly manifesting as severe immunodeficiency.Case presentationWe report the case of a 15-month-old male child with pancytopenia, growth retardation, microcephaly, history of vaccine-related rubella, elevated immunoglobulin G, and decreased T- and B lymphocytes. Next-generation sequencing revealed LIG4 pathogenic genes and compound heterozygous mutations, namely the missense mutation c.833G > T (p.Arg278Leu) and deletion mutation c.1271_1275del (p.Lys424Argfs*20).ConclusionThis case suggests that LIG4 dificiency can manifest not only as immunodeficiency but also with increased serum IgG levels and pancytopenia, which constitutes an additional clinical phenotype. Furthermore, this case suggests that LIG4 deficiency should be considered upon differential diagnosis of myelodysplastic syndrome in children.

Clinical Efficacy of Haplo-HSCT of ATG Combined with PTCy for Children with Myelodysplastic Syndrome

To investigate the efficacy and safety of haploidentical hematopoietic stem cell transplantation (haplo-HSCT) in combination of ATG and post-transplant cyclophosphamide (PTCy) -induced immune tolerance after transplantation in treatment of childhood myelodysplastic syndromes(MDS）. From July 2016 to November 2020, a total of 8 children with MDS receiving the haploidentical allo-HSCT combined with ATG and PTCy-induced immune tolerance after transplantation in our hospital were enrolled, whose clinical data were retrospected and analyzed. Median age at diagnosis of the 8 children (1 male and 7 females) was 6.4 (range, 10 months to 15 years) years old. The median medical history of MDS was 2.7 years (range, 3 months to 8 years). Among the 8 patients, 7 cases were diagnosed with refractory cytopenia of childhood and one with refractory anemia with excess of blasts. The HSC donors were father, mother or brother of patients and HLA matching in 6-9/12 loci were identical. All the donors were healthy and didn't carry the same pathogenic genes as the recipients. The median age of donors was 36.4 (range, 25 to 49) years old. The median mononuclear cell (MNC) number of the graft was 19.8, ranging in (13.2-47.3)×108/kg, and the median CD34+ cell number was 11.8×106/kg, ranging in (5.0-18.3)×106/kg. Graft-versus-host disease prophylactic regimen was started on day 3 and 4 after transplantation, in which cyclophosphamide (50 mg/kg·d) was administered by intravenous infusion. From day 5 after transplantation, low-dose tacrolimus was administered by intravenous infusion and mycophenolate mofetil was administered orally. The median time of neutrophil and platelet engraftment was 12.6 (rang, 11 to 15) days and 13.3 (rang, 11 to 18) days, respectively. All the patients achieved full donor chimerism on neutrophil engraftment after transplantation. The median follow-up time was 1 032 (rang, 747 to 1 536) days. Both overall survival rate and disease-free survival rate were 100%. Haplo-HSCT combined with ATG and PTCy-induced immune tolerance after transplantation is a safe and effective treatment for children with MDS.

Clinical Characteristics and Prognosis of Children with Myelodysplastic Syndrome

To analyze the clinical characteristics and prognosis of 40 children with myelodysplastic syndrome (MDS), and provide ideas for clinical diagnosis and treatment. The clinical characteristics, risk stratification, and different treatment regimens of 40 cases with MDS admitted in Department of Hematology of Children's Hospital of Soochow University from January 1, 2011 to December 31, 2017 was retrospectively analyzed. Kaplan-Meier survival curve were used to estimate 3-year overall survival (OS) rate and event-free survival (EFS) rate. In 40 cases, the ratio of male to female was 1.4∶1.0, male was more than female, and median age was 6.0 years old. Among them, refractory cytopenia (MDS-RCC) was the most common type, and 11 cases were chromosomal abnormalities, 21 cases genetic abnormalities. Fifteen cases accepted hematopoietic stem cell transplantation (HSCT) treatment, while 25 cases did not but drug therapy alone. The 3-year OS rate of the cases who accepted HSCT or not was (72.2±12.2)% and (35.3±10.2)% (P=0.039), 3-year EFS rate was (65.0±12.9)% and (19.2±8.4)% (P=0.012), respectively. Cox regression analysis showed that age < 7 years old (P=0.0333), initial diagnosed platelet < 50×109/L (P=0.007), presence of complex karyotypes and/or gene mutations (P=0.0002), and treatment without HSCT (P=0.016) were the high-risk factors of prognosis. All the children were classified according to IPSS, WPSS and IPSS-R, while analysis result showed that the above three risk assessment had limitations for risk assessment of MDS in children, they could not comprehensively assess the prognosis of children with MDS. MDS-RCC in children is more common. Cox multivariate analysis shows that age < 7 years old, initial diagnosed platelet < 50×109/L, presence of complex karyotypes and/or gene mutation, and treatment without HSCT are the high-risk factors of prognosis in children with MDS. HSCT is the most effective treatment to cure children with MDS at present. The current methods such as IPSS-R commonly used in assessment of prognosis in children with MDS show obvious limitation.

Morphological diagnosis of childhood bone marrow failure syndromes

In 2008, the World Health Organization proposed a provisional entity of childhood myelodysplastic syndrome (MDS) without a blasts increase, which was referred to as the refractory cytopenia of childhood (RCC). We performed a central review of bone marrow morphology in 252 children with acquired bone marrow failure syndromes to clarify the clinical relevance of the RCC. The RCC was divided two categories, namely, RCC without multilineage dysplasia (MLD) and RCC with MLD, which is similar to MDS with MLD in adult MDS. Furthermore, the clinical outcomes were investigated for cases diagnosed with aplastic anemia, RCC without MLD, and RCC with MLD. The response rates to immunosuppressive therapy and the incidence of the development of the new chromosomal aberration did not significantly differ among the three groups. The RCC with MLD can be adopted in childhood MDS since children with this condition exhibited a frequent chromosomal aberration at the time of diagnosis and a high frequency of secondary graft failure after a hematopoietic cell transplantation.

Myelodysplastic syndromes (MDS)

MDS in children is a rare group of hematopoietic stem cell clonal disorder. Allogeneic HSCT is the only curative treatment. HLA typing and the search for a compatible donor must be carried out upon diagnosis, for all patients. However, patients with refractory cytopenia of childhood without an unfavorable karyotype can keep the disease stable for a long time. Thus, in the absence of transfusion dependence or severe neutropenia, a careful observation strategy without treatment is recommended. The treatment of children diagnosed with MDS with excess blasts remains a major challenge. Allogeneic HSCT is the only curative treatment, although the data published in the literature generally include a small number of patients, heterogeneously transplanted. For children with MDS secondary to therapy, despite HSCT, the evolution is generally unfavorable.

Germline and Somatic Variants Co-Ocurrence Profile in Early Onset Adult Myelodysplastic Syndromes without a Preexisting Disorder

Germline and Somatic Variants Co-Ocurrence Profile in Early Onset Adult Myelodysplastic Syndromes without a Preexisting Disorder

Prospective validation of the provisional entity of refractory cytopenia of childhood, proposed by the World Health Organization.

In 2008, the World Health Organization proposed a new entity of childhood myelodysplastic syndrome (MDS), which was referred to as refractory cytopenia of childhood (RCC). However, whether this morphological classification reflects clinical outcomes remains unclear. We performed a prospective evaluation of bone marrow morphology in 252 children with acquired bone marrow failure between 2009 and 2013. Of 252 patients, 63 were diagnosed with aplastic anaemia (AA), 131 with RCC without multilineage dysplasia (RCC-w/o-MLD) and 58 with RCC with MLD (RCC-MLD). One patient with AA, three with RCC-w/o-MLD and nine with RCC-MLD presented with chromosomal abnormalities at diagnosis (P=0·001). The response rates to immunosuppressive therapy (IST) at 6months and the cumulative incidence of clonal evolution at 5years did not significantly differ among the three groups. A multivariate analysis revealed that the morphological classification of RCC-MLD was a significant risk factor for secondary graft failure after haematopoietic cell transplantation (HCT) (P=0·003). In view of these findings, RCC could be divided into two categories, RCC-w/o-MLD and RCC-MLD, because children with this condition exhibited a distinct morphology, frequent chromosomal abnormalities at diagnosis and a high frequency of secondary graft failure after HCT.