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Hereditary spherocytosis (HS) with hemolysis, splenomegaly, and jaundice as the main clinical symptoms varied in different population and SPTB mutated rate is common except for ANK1 in the Chinese population, whereas only a few studies have been reported. Here, 11 Chinese pediatric patients with newly SPTB mutations detected by targeted next generation sequencing technology were included and analyzed in our study. The characteristics of mutation separation were verified among family members by bidirectional Sanger sequencing. The detected 11 mutations were novel, all of which were heterozygotes, including five de novo mutations, five maternal mutations, and one paternal mutation. Meanwhile, the 11 different novel mutation sites distributed on and near the seven exons included four pathogenic sites and seven likely pathogenic sites. The detection of 11 novel mutation sites gene expanded the mutant spectrum of the SPTB gene, and provided corresponding clinical data, which laid a foundation for the subsequent studies on HS in Chinese population, especially in pediatric patients.

Objective. To explore the immune cell therapy for T cell lymphoma, we developed CD4-specific chimeric antigen receptor- (CAR-) engineered T cells (CD4CART), and the cytotoxic effects of CD4CART cells were determined in vitro and in vivo. Methods. CD4CART cells were obtained by transduction of lentiviral vector encoding a single-chain antibody fragment (scFv) specific for CD4 antigen, costimulatory factor CD28 fragment, and intracellular signal transduction domain of CD3 fragments. Control T cells were obtained by transduction of reporter lentiviral vector. The cytotoxicity, tumor growth, and survival rate of mice with T cell lymphoma were analyzed after adoptive T cell transfer in vivo. Results. CD4CART cells had potent cytotoxic activity against CD4+ T1301 tumor T cells in a concentration-dependent manner. In addition, adoptive CD4CART cell transfer significantly suppressed tumor growth and improved animal survival with T cell lymphoma, compared to the mice who received control T cells and PBS. Conclusion. CD4CART cells have potent cytotoxic effects on T cell lymphoma. The study provided an experimental basis for CD4CART-mediated therapy of T cell lymphoma.

The E2A-HLF fusion gene is a very poor biomarker in acute lymphoblastic leukemia (ALL) because of its high relapse risk, even with the most intensive chemotherapy and hematopoietic stem cell transplantation (HSCT). Here, we analyzed four cases diagnosed with E2A-HLF fusion gene-positive B-ALL and treated with the CCCG-ALL-2015 protocol based on high-risk stratification from Jun 2017 to May 2020 retrospectively. Three cases (Case 1, 2, 3) were insensitive to conventional therapy and inhibitors with high-level MRD on days 19 and 46, but they all achieved complete remission at the molecular level with Chimeric Antigen Receptor (CAR) T cell therapy regardless of primary resistance or recurrence. Although remission was initially achieved for Case 4, chemotherapeutics was not sensitive after recurrence. However, CAR-T cell therapy gave him the chance to obtain complement remission again. Cytokine release syndrome (CRS) with fever, chills, acute kidney injury, hypotension and capillary leak syndrome and CAR-T related encephalopathy syndrome (CRE) with seizures and encephaledema occurred after CAR-T cell therapy, but symptoms disappeared with effective intensive care. Overall, CAR-T cell therapy enabled the patients to achieve complement remission with controllable adverse events. Our results indicated that CAR-T cell therapy is a feasible and effective therapy for patients with E2A-HLF-positive B-ALL and prompted the authors to report these cases.

MYH9-related diseases (MYH9-RD) are a group of autosomal dominant diseases caused by mutations in the MYH9 gene, which are featured by thrombocytopenia, giant platelets and granulocyte cytoplasmic inclusion bodies. MYH9-RD patients generally suffer from bleeding syndromes, progressive kidney disease, deafness, or cataracts. Here, we reported on a case of MYH9-RD. A novel heterozygous mutation of MYH9 (c.2344-2345delGTinsTA, p.T782Y) was discovered by targeted sequencing technology. Immunofluorescence analysis of neutrophils confirmed abnormal aggregation of MYH9 protein. The results of this study should expand the MYH9 gene mutation spectrum and provide reference for subsequent researchers and genetic counseling.

Background Transcobalamin (TC) transports vitamin B12 from blood into cells. TC II deficiency is a rare autosomal recessive disorder. It is characterized by failure to thrive, diarrhoea, pallor, anaemia, pancytopenia or agammaglobulinemia. It is usually confirmed by molecular analysis of the TCN2 gene. We report a 2-month-old girl with two novel mutations, which were first reported in humans. Case presentation We present a 2-month-old Chinese girl with pancytopenia, severe combined immunodeficiency disease, and megaloblastic anaemia. Targeted next-generation sequencing (NGS) was performed, which detected compound heterozygous variants in exon 7 of the TCN2 gene (Mutation 1: c.1033 C > T; Mutation 2: c.1017-1031delinsGTAACAGAGATGGTT). These mutations result in stop codons in TCN2. The c.1033C > T mutation causes a stop at codon 345 (p.Gln345Ter), and the c.1017-1031delinsGTAACAGAGATGGTT mutation causes a stop at codon 340 (p.Leu340Ter). After being diagnosed, she was treated with intramuscular 1 mg hydroxycobalamin (OH-Cbl) every day for 2 months. The CBC value returned to normal after half a month. The peripheral blood lymphocyte subsets and immunoglobulin recovered after 2 months. Then, the dosage of OH-Cbl was gradually reduced. Conclusions TC II deficiency is a serious complication that requires lifelong treatment. Its diagnosis is difficult due to the lack of clearly identifiable symptoms. Genetic testing should be performed as early as possible if this disease is suspected. The specific observations of this case report make a considerable contribution to the literature and provide a reference for the diagnosis and treatment of future cases.

Neuroblastoma (NB) is the most common extra-cranial solid tumor in childhood with the overall 5 years' survival less than 40%. Polo-like kinase 1 (PLK1) is a serine/threonine-protein kinase expressed during mitosis and over expressed in multiple cancers, including neuroblastoma. We found that higher PLK1 expression related to poor outcome of NB patients. BI2536, a small molecule inhibitor against PLK1, significantly reduced cell viability in a panel of NB cell lines, with IC50 less than 100 nM. PLK1 inhibition by BI 2536 treatment induced cell cycle arrest at G2/M phase and cell apoptosis in NB cells. Realtime PCR array revealed the PLK1 inhibition related genes, such as BIRC7, TNFSF10, LGALS1 and DAD1 et al. Moreover, autophagy activity was investigated in the NB cells treated with BI 2536. BI 2536 treatment in NB cells increased LC3-II puncta formation and LC3-II expression. Formation of autophagosome induced by BI 2536 was observed by transmission electron microscopy. However, BI2536 abrogated the autophagic flux in NB cells by reducing SQSTM1/p62 expression and AMPKαT172 phosphorylation. These results provide new clues for the molecular mechanism of cell death induced by BI 2536 and suggest that BI 2536 may act as new candidate drug for neuroblastoma.

Background: Immune thrombocytopenic purpura (ITP) is an autoimmune bleeding disorder and the decreased number and immunosuppressive dysfunction of Treg cells are key promoters of ITP. However, their mechanisms in ITP development have not been fully clarified.Methods: HUWE1 mRNA and protein levels in CD4+ T cells in peripheral blood from ITP patients were assessed by quantitative real-time PCR and Western blot. HUWE1 function in ITP was estimated using flow cytometry, enzyme-linked immunosorbent assay and immunosuppression assay. Besides, the HUWE1 mechanism in reducing the number and function of Treg cells in ITP was investigated by immunoprecipitation, cycloheximide-chase assay, ubiquitin experiment and immunofluorescence assay.Results: HUWE1 expression was elevated in CD4+ T cells in peripheral blood from ITP patients and HUWE1 mRNA level was negatively correlated with platelet counts and Treg cell percentage. Moreover, the interference with HUWE1 increased the number of Treg cells and enhanced its immunosuppressive function, and the HUWE1 overexpression produced the opposite results. For the exploration of mechanism, HUWE1 interacted with E26 transformation-specific-1 (Ets-1) and this binding was dependent on the negative regulation of the phosphorylation level of Ets-1 (Thr38) and HUWE1 facilitated the ubiquitin degradation of Ets-1 protein to restrain Treg cell differentiation and weaken their immunosuppressive functions. The in vivo assay confirmed that the HUWE1 inhibitor alleviated ITP in mice.Conclusion: HUWE1 induced the immune imbalance in ITP by decreasing the number and weakening the function of Treg cells through the ubiquitination degradation of Ets-1.

Most tumors are sporadic and originated from somatic mutations. Some rare germline mutations cause familial tumors, often involving multiple tissues or organs. Tumors from somatic mosaicism during embryonic development are extremely rare. We describe here a pediatric patient who developed both an ovarian germ cell tumor and systemic mastocytosis. Targeted DNA NGS analysis revealed similar genomic changes including the same KIT D816V mutation in both tissues, suggesting a common progenitor cancer cell. The KIT mutated cells are likely from early embryonic development during germ cell migration. A literature search found additional 8 similar cases. These diseases are characterized by pediatric-onset, all-female, neoplastic proliferation in both gonad and bone marrow, and a common oncogenic cause, i.e., KIT mutation, constituting a clinically and genetically homogenous disease entity. Importantly, the association of germ cell tumors with hematopoietic neoplasms suggests that the primordial germ cells are the primitive hematopoietic stem cells, a much-debated and unsettled question. This article is protected by copyright. All rights reserved.

Aims: To conduct a lifetime cost-effectiveness analysis (CEA) of rasburicase compared with standard of care (SOC) for tumor lysis syndrome (TLS) in children with hematologic malignancies from the Chinese healthcare system perspective. Materials and methods: The CEA was performed using a decision tree model with a lifetime horizon. The model explores the cost-effectiveness of rasburicase vs SOC for both preventing TLS and treating established TLS among pediatric patients with acute myeloid leukemia (AML), acute lymphoid leukemia (ALL), and non-Hodgkin's lymphoma (NHL). Both the prophylaxis-use model and treatment-use model incorporate long-term health states of the diseases: survival without TLS and death. The efficacy data of rasburicase and SOC were obtained from published literature. Drug costs, healthcare resource utilization (HRU), and adverse event (AE) management costs were obtained via a published study with clinical experts. Costs in US dollar and quality-adjusted life year (QALY) are reported, and incremental cost-effectiveness ratios (ICERs) were also calculated. Uncertainties due to parameter fluctuations in the model were assessed through one-way sensitivity analysis and probabilistic sensitivity analysis (PSA). Results: During TLS prevention, compared with SOC, the ICER of rasburicase treatment in China are $17,580.04/QALY, $5,783.45/QALY, and $5,391.00/QALY for pediatric patients with AML, ALL, and NHL, respectively. For the established TLS treatment, compared with SOC, the ICERs of rasburicase treatment are $2,031.18/QALY, $1,142.93/QALY, and $990.37/QALY for pediatric patients with AML, ALL, and NHL, respectively. Limitations: The clinical data for SOC are based on the published study in China, and the rasburicase prevention or treatment failure rate was either calculated based on the risk ratio or directly from the clinical study among non-Chinese pediatric patients. Another study limitation was the lack of utility data for pediatric patients with TLS and without TLS. Thus, the utility scores of pediatric cancer survivors were used as an alternative. Conclusion: Rasburicase is estimated to be a cost-effective alternative to SOC in the prevention and treatment of TLS among Chinese pediatric patients with AML, ALL, and NHL.

Treatment refusal and death as a result of toxicity account for most treatment failures among children with acute myeloid leukemia (AML) in resource-constrained settings. We recently reported the results of treating children with AML with a combination of low-dose cytarabine and mitoxantrone or omacetaxine mepesuccinate with concurrent granulocyte colony-stimulating factor (G-CSF) (low-dose chemotherapy [LDC]) for remission induction followed by standard postremission strategies. We have now expanded the initial cohort and have provided long-term follow-up. Eighty-three patients with AML were treated with the LDC regimen. During the study period, another 100 children with AML received a standard-dose chemotherapy (SDC) regimen. Complete remission was attained in 88.8% and 86.4% of patients after induction in the LDC and SDC groups, respectively (P = .436). Twenty-two patients in the LDC group received SDC for the second induction course. Significantly more high-risk AML patients were treated with the SDC regimen (P = .035). There were no significant differences between the LDC and SDC groups in 5-year event-free survival (61.4% ± 8.7% vs 65.2% ± 7.4%, respectively; P = .462), overall survival (72.7% ± 6.9% vs 72.5% ± 6.2%, respectively; P = .933), and incidence of relapse (20.5% ± 4.5% vs 17.6% ± 3.9%, respectively; P = .484). Clearance of mutations based on the average variant allele frequency at complete remission in the LDC and SDC groups was 1.9% vs 0.6% (P < .001) after induction I and 0.17% vs 0.078% (P = .052) after induction II. In conclusion, our study corroborated the high remission rate reported for children with AML who received at least 1 course of LDC. The results, although preliminary, also suggest that long-term survival of these children is comparable to that of children who receive SDC regimens.

BackgroundAberrant expression of CD123 (IL-3Rα) was observed in various hematological malignancies including acute lymphoblastic leukemia (ALL), which is the most common malignancy in childhood. Although widely used for minimal residual disease (MRD) monitoring, the prognostic value of CD123 has not been fully characterized in pediatric B-ALL. This retrospective study aims to evaluate the association between the CD123 expression of leukemic blasts and the outcomes of the pediatric B-ALL patients.MethodsA total of 976 pediatric B-ALL, including 328 treated with CCLG-ALL-2008 protocol and 648 treated with CCCG-ALL-2015 protocol, were recruited in this retrospective study. CD123 expression was evaluated by flow cytometry. Patients with >50, 20–50, or high, CD123low, and CD123neg, respectively. The correlation between CD123 expression and the patients’ clinical characteristics, overall survival (OS), event-free survival (EFS), and relapse-free survival (RFS) were studied statistically.ResultsOf 976 pediatric B-ALL, 53.4% from the CCLG-ALL-2008 cohort and 49.2% from the CCCG-ALL-2015 cohort were CD123high. In the CCLG-ALL-2008 cohort, CD123high was significantly associated with chromosome hyperdiploidy (p < 0.0001), risk stratification (p = 0.004), and high survival rate (p = 0.005). By comparing clinical outcomes, patients with CD123high displayed favorable prognosis, with a significantly better OS (p = 0.005), EFS (p = 0.017), and RFS (p = 0.045), as compared to patients with CD123low and CD123neg. The prognostic value of CD123 expression was subsequently confirmed in the CCCG-ALL-2015 cohort. Univariate and multivariate cox regression model analysis showed that high CD123 expression was independently associated with favorable EFS (OR: 0.528; 95% CI: 0.327 to 0.853; p = 0.009) in this cohort. In patients without prognosis-defining genomic abnormalities, high CD123 expression strongly indicated superior survival rates and was identified as an independent prognosis factor for EFS and RFS in both cohorts.ConclusionsA group of B-ALL lacks prognosis-defining genomic aberrations, which proposes a challenge in risk stratification. Our findings revealed that high CD123 expression of leukemic blasts was associated with favorable clinical outcomes in pediatric B-ALL and CD123 could serve as a promising prognosis predictor, especially in patients without prognosis-defining genetic aberrations.

With the dramatic improvements in outcomes following alternative donor hematopoietic stem cell transplantation (HSCT), interest in the use of alternative donors in severe aplastic anemia (SAA) is increasing. We conducted a multicenter prospective study to explore the efficiency and safety of upfront HSCT from a 6-8/8 HLA-matched unrelated donor (MUD) or 6-7/8 HLA-matched related donor (MRD) in acquired SAA patients under 40 years. Between August 2014 and July 2017, 115 patients were enrolled, including 48 (41.7%) patients receiving grafts from an 8/8 MUD, 25 (21.7%) from a 6-7/8 MRD, and 42 (36.5%) from a 6-7/8 MUD. The incidence of grade II-IV acute graft-versus-host disease (GVHD) was higher in the 6-7/8 MUD group than in the 8/8 MUD group (42.9% vs. 12.8%, P=0.001). The corresponding incidence in the 6-7/8 MRD group was comparable to that in the 8/8 MUD group (21.7% vs. 12.8%, P=0.332). There was no significant difference in the incidence of chronic GVHD (24.3%, 13.6%, and 17.9%, P=0.676), graft failure (2.4%, 8.0%, and 6.3%, P=0.551), overall survival (85.7%, 96.0%, and 87.5%, P=0.424), and failure-free survival (83.3%, 88.0%, and 83.3%, P=0.885) among the three groups (6-7/8 MUD, 6-7/8 MRD, and 8/8 MUD). In multivariate analysis, conditioning regimen without low-dose irradiation or busulfan was associated with an inferior failure-free survival (HR=2.973, P=0.042). In conclusion, after an intensified conditioning regimen with additional low-dose irradiation or busulfan, the outcome of HSCT from a 6-7/8 MRD or 6-7/8 MUD is comparable to that from an 8/8 MUD.

Graft-versus-host disease (GVHD) causes failed reconstitution of donor plasmacytoid dendritic cells (pDCs) that are critical for immune protection and tolerance. We used both murine and human systems to uncover the mechanisms whereby GVHD induces donor pDC defects. GVHD depleted Flt3-expressing donor multipotent progenitors (MPPs) that sustained pDCs, leading to impaired generation of pDCs. MPP loss was associated with decreased amounts of MPP-producing hematopoietic stem cells (HSCs) and oxidative stress-induced death of proliferating MPPs. Additionally, alloreactive T cells produced GM-CSF to inhibit MPP expression of Tcf4, the transcription factor essential for pDC development, subverting MPP production of pDCs. GM-CSF did not affect the maturation of pDC precursors. Notably, enhanced recovery of donor pDCs upon adoptive transfer early after allogeneic HSC transplantation repressed GVHD and restored the de novo generation of donor pDCs in recipient mice. pDCs suppressed the proliferation and expansion of activated autologous T cells via a type I IFN signaling-dependent mechanism. They also produced PD-L1 and LILRB4 to inhibit T cell production of IFN-γ. We thus demonstrate that GVHD impairs the reconstitution of tolerogenic donor pDCs by depleting DC progenitors rather than by preventing pDC maturation. MPPs are an important target to effectively bolster pDC reconstitution for controlling GVHD.

To identify the prognostic factors that are useful to improve central nervous system (CNS) control in children with acute lymphoblastic leukemia (ALL), we analyzed the outcome of 7640 consecutive patients treated on Chinese Children’s Cancer Group ALL-2015 protocol between 2015 and 2019. This protocol featured prephase dexamethasone treatment before conventional remission induction and subsequent risk-directed therapy, including 16 to 22 triple intrathecal treatments, without prophylactic cranial irradiation. The 5-year event-free survival was 80.3% (95% confidence interval [CI], 78.9-81.7), and overall survival 91.1% (95% CI, 90.1-92.1). The cumulative risk of isolated CNS relapse was 1.9% (95% CI, 1.5-2.3), and any CNS relapse 2.7% (95% CI, 2.2-3.2). The isolated CNS relapse rate was significantly lower in patients with B-cell ALL (B-ALL) than in those with T-cell ALL (T-ALL) (1.6%; 95% CI, 1.2-2.0 vs 4.6%; 95% CI, 2.9-6.3; P < .001). Independent risk factors for isolated CNS relapse included male sex (hazard ratio [HR], 1.8; 95% CI, 1.1-3.0; P = .03), the presence of BCR-ABL1 fusion (HR, 3.8; 95% CI, 2.0-7.3; P < .001) in B-ALL, and presenting leukocyte count ≥50×109/L (HR, 4.3; 95% CI, 1.5-12.2; P = .007) in T-ALL. Significantly lower isolated CNS relapse was associated with the use of total intravenous anesthesia during intrathecal therapy (HR, 0.2; 95% CI, 0.04-0.7; P = .02) and flow cytometry examination of diagnostic cerebrospinal fluid (CSF) (HR, 0.2; 95% CI, 0.06-0.6; P = .006) among patients with B-ALL. Prephase dexamethasone treatment, delayed intrathecal therapy, use of total intravenous anesthesia during intrathecal therapy, and flow cytometry examination of diagnostic CSF may improve CNS control in childhood ALL. This trial was registered with the Chinese Clinical Trial Registry (ChiCTR-IPR-14005706).

Tumor lysis syndrome (TLS) is a common and fatal complication of childhood hematologic malignancies, especially acute lymphoblastic leukemia (ALL). The clinical features, therapeutic regimens, and outcomes of TLS have not been comprehensively analyzed in Chinese children with ALL. A total of 5537 children with ALL were recruited from the Chinese Children’s Cancer Group, including 79 diagnosed with TLS. The clinical characteristics, treatment regimens, and survival of TLS patients were analyzed. Age distribution of children with TLS was remarkably different from those without TLS. White blood cells (WBC) count ≥ 50 × 109/L was associated with a higher risk of TLS [odds ratio (OR) = 2.6, 95% CI = 1.6–4.5]. The incidence of T-ALL in TLS children was significantly higher than that in non-TLS controls (OR = 4.7, 95% CI = 2.6–8.8). Hyperphosphatemia and hypocalcemia were more common in TLS children with hyperleukocytosis (OR = 2.6, 95% CI = 1.0–6.9 and OR = 5.4, 95% CI = 2.0–14.2, respectively). Significant differences in levels of potassium (P = 0.004), calcium (P P P

Postzygotic mutations are acquired in all of the normal tissues throughout an individual’s lifetime and hold clues for identifying mutagenesis causing factors. The process and underlying mechanism of postzygotic mutations in normal tissues is still poorly understood. In this study, we investigated postzygotic mutation spectra in healthy individuals by optimized ultra-deep exome sequencing of time series samples from the same volunteer and samples from different individuals. In cells of blood, sperm, and muscle, we resolved three common types of mutational signature. Two of them are known to represent clock-like mutational processes, and their proportions in mutation profiles associated with polymorphisms of epigenetic regulation genes, suggesting the contribution of personal genetic backgrounds to underlying biological process. Notably, the third signature, characterized by C>T transitions at GpCpN sites, tends to be a feature of diverse normal tissues. Mutations of this type were likely to occur early in embryo development even before the tissue differentiation, as indicated by their relatively high allele frequencies, sharing variants between multiple tissues, and lacking of age-related accumulation. Almost all tumors shown in public datasets did not have this signature detected except for 19.6% of clear cell renal cell carcinoma samples, which featured by activation of the hypoxia-induced signaling pathway. Moreover, in vitro activation of HIF signaling pathway successfully introduced the corresponding mutation profile of this signature in a culture-expanded human embryonic stem cell line. Therefore, embryonic hypoxia may explain this novel signature across multiple normal tissues. Our study suggest hypoxic conditions in the early stage of embryo development may be a crucial factor for the C>T transitions at GpCpN sites and individual genetic background also related to shaping human postzygotic mutation profiles. Author Summary The process and related mechanism of post-zygotic mutations in normal tissues is still poorly understood. By analyzing post-zygotic mutations in blood, sperm and muscle from healthy individuals, we found a normal tissues specific mutation type characterized by C>T transitions at GpCpN sites. Almost none of tumors in The Cancer Genome Atlas project harbors this type of mutations, except for a subset of clear cell renal cell carcinoma samples with higher activity of hypoxia inducible signaling pathways. We further reproduce the enrichment of this type of mutations in human embryonic stem cells by specific activating hypoxia inducible factor 1α. Taken together, we propose that hypoxic conditions are one crucial factor responsible for the occurrence of post-zygotic mutations, especially the C>T transition in GpCpN sites, in the early stage of embryo development in healthy individuals.

Acute myeloid leukemia (AML) is the most common hematologic malignancy in adults. Although AML patients achieve a complete remission following chemotherapy, most patients relapse with residual disease. Only approximately 25% of AML patients are alive 5 years following their diagnosis. Immunotherapies, such as chimeric antigen receptor T cells, immune checkpoint inhibitors, and vaccination using dendritic cells (DCs) treated by AML cells and their-derived antigens, have emerged as promising therapeutic modalities in AML. However, for AML, in which leukemia cells disseminate in bone marrow (BM), peripheral blood and many other tissues, the mechanisms that regulate the generation and maintenance of leukemia-specific T cell responses are less clear. Growing evidence suggests that AML cells can not only directly repress antigen-specific T cell reactivity, but also induce tolerogenic DCs to reduce tumor-specific T cell responses. DC-mediated tolerogenic mechanisms include suppressing T cell proliferation, inducing T cell deletion and impairing the function of leukemia-specific T cells. Interestingly, this tolerogenic effect can be potentially reversed upon activation by Toll-like receptor agonists and ligation of CD40 in DCs. Clinical studies reveal that DC-based vaccination is potentially effective on preventing and delaying relapse of AML. In this chapter, we focus on discussing these effects of DCs on mediating immunogenicity and immune tolerance of T cells against AML cells.

Introduction Patients with E2A-PBX1 fusion are expected to have an aggressive disease course. Because of the rarity of this genotype (nearly 5% of pediatric and 3% of adult B-cell acute lymphoblastic leukemia (B-ALL) cases), a consensus on the clinical and prognostic characteristics of adult E2A-PBX1-positive B-ALL patients, especially in adult patients, has not yet been reached. Patients and Methods We retrospectively summarized our clinical findings from 137 B-ALL patients diagnosed with E2A-PBX at our centers from 2009 to 2019, including 56 adolescents/adults (≥15 years old) and 81 children ( Results The proportions of E2A-PBX1-positive B-ALL in our centers were 5.3% (81/1526) in children, 4.6% (43/925) in AYA and 2.1% (15/713) in older adults. The complete remission rate among all E2A-PBX1-positive B-ALL patients in this study was 94.9% (129/136) after one course of induction chemotherapy. The 5-year overall survival (OS) and disease-free survival (DFS) rates of the whole cohort were 68.6% and 61.0%, respectively. Allo-HSCT at CR1 in adolescents/adults could dramatically improve the 5-year prognoses (OS: 80.8% vs. 25.7%, P A total of 12 patients received CD19-targeted CAR-T cell therapy for disease progression (Figure 1C), and 91.7% (11/12) of patients achieved remission. Two patients died of relapse, and 3 patients died of complications (One died of grade 4 CRS, one died of cerebral hemorrhage after transfusion, and the other one died of infection after 14 months). Three patients received CAR-T bridging to allo-HSCT, and all of them remained in remission within the follow-up period. Univariate and multivariate analysis showed that t(1;19)(q23;p13) only (OS: P=0.020, HR=0.387, 95% CI: 0.174-0.862; DFS: P=0.004, HR= 0.375, 95% CI: 0.193-0.729; CIR: P=0.009, HR= 0.400, 95% CI: 0.200-0.799), Age (DFS: P=0.037, HR=1.009, 95% CI: 1.001-1.018; CIR: P=0.005, HR=1.025, 95% CI: 1.008-1.044) and the level of minimal residual disease (MRD) after induction chemotherapy (OS: P=0.020, HR=2.971, 95% CI: 1.185-7.452; DFS: P=0.002, HR= 3.218, 95% CI: 1.510-6.861; CIR: P=0.006, HR= 3.190, 95% CI: 1.406-7.246) were independent risk factors in E2A-PBX1-positive B-ALL (Figure 1D). In the diagnosis samples, mutations in PBX1, PAX5, CTCF and SETD2, amplification of AKT3, and deletion of CDKN2A/B were common in the total cohort, while transcriptome differences were found in the cell cycle, NGF signaling pathway and transcriptional regulation by TP53 between adolescents/adults and children (Figure 2A,B). More DNA repair gene mutations were detected in the relapse samples (7.9% vs. 57.1%, P Conclusions Our study indicated that age, the level of MRD and DNA repair gene mutations were associated with E2A-PBX1-positive B-ALL outcomes. Allo-HSCT, especially haploidentical-HSCT, could improve the prognosis of adolescent/adult patients. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

Early prediction and intervention are known to be critical for acute graft-versus-host disease (aGVHD) prevention and treatment. Significant progress has been made in the development of human plasma biomarkers for the risk stratification of aGVHD severity. Whether donor-derived immune cells may predict the occurrence of severe aGVHD early after allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains poorly understood. The objective of this retrospective study was to evaluate the results of allo-HSCT in pediatric patients with different counts and frequencies of dendritic cell (DC) subsets at engraftment in pediatric patients at the Children's Hospital of Soochow University. A total of 45 patients as a discovery cohort were enrolled from March 2018 to December 2018 at the hospital. The validation cohort (30 patients) was enrolled from December 2019 to May 2020. Plasma samples collected from 2016 to 2018 were used for testing ST2 and Reg3α in pediatric patients undergoing allo-HSCT. Patients with grade II-IV aGVHD (n = 18; termed severe aGVHD) showed 3- and 6-fold fewer frequency and numbers, respectively, of plasmacytoid dendritic cells (pDCs) in the peripheral blood (PB) at the engraftment time than patients with grade 0-I aGVHD (n = 27; termed no/mild aGVHD). Using a receiver operating characteristic curve analysis, we identified the threshold of pDC level at 0.3 cell/μL as a cutoff to evaluate the difference in patients with high (0.3 cell/μL) versus low (0.3 cell/μL) pDC counts. Of these 45 patients, 21 (46.7%) had a high number of pDCs and 24 (53.3%) had low pDCs. The patients with low pDCs at the time of engraftment had a significantly higher probability of developing severe aGVHD (P.05). The sensitivity of distinguishing severe aGVHD from no/mild aGVHD was 75%, and the specificity was 94%. In addition, the low pDC patients had higher transplantation-related mortality compared with the high pDC patients (12.5% versus 0%). Using an additional cohort of 30 allo-HSCT patients, we validated this observation. Our findings demonstrate that donor pDC count in PB at the time of engraftment is a valuable biomarker for predicting severe aGVHD in pediatric patients undergoing allo-HSCT.

Neuroblastoma is the most common extracranial solid childhood tumor. Despite the availability of advanced multimodal therapy, high-risk patients still have low survival rates. p21-activated kinase 4 (PAK4) has been shown to regulate many cellular processes in cancer cells, including migration, polarization and proliferation. However, the role of PAK4 in neuroblastoma remains unclear. In the present study, we demonstrated that PAK4 was overexpressed in neuroblastoma tissues and was correlated with tumor malignance and prognosis. To investigate the function of PAK4 in neuroblastoma, we used a small-molecule inhibitor that targets PAK4, that is, PF-3758309. Our results showed that PF-3758309 significantly induced cell cycle arrest at the G1 phase and apoptosis in neuroblastoma cell lines. Meanwhile, the inhibition of PAK4 by PF-3758309 increased the expression of CDKN1A, BAD and BAK1 and decreased the expression of Bcl-2 and Bax. In addition, we screened the target genes of PAK4 by PCR array and found that 23 genes were upregulated (including TP53I3, TBX3, EEF1A2, CDKN1A, IFNB1 and MAPK8IP2) and 20 genes were downregulated (including TNFSF8, Bcl2-A1, Bcl2L1, SOCS3, BIRC3 and NFKB1) after PAK4 inhibition by PF-3758309. Moreover, PAK4 was found to regulate the cell cycle and apoptosis via the ERK signaling pathway. In conclusion, the present study demonstrated, for the first time, the expression and function of PAK4 in neuroblastomas and the inhibitory effect of PF-3758309, which deserves further investigation as an alternative strategy for neuroblastoma treatment.

Modulating T-cell alloreactivity has been a main strategy to reduce graft-versus-host disease (GVHD), a life-threatening complication after allogeneic hematopoietic stem-cell transplantation (HSCT). Genetic deletion of T-cell Ezh2, which catalyzes trimethylation of histone H3 at lysine 27 (H3K27me3), inhibits GVHD. Therefore, reducing Ezh2-mediated H3K27me3 is thought to be essential for inhibiting GVHD. We tested this hypothesis in mouse GVHD models. Unexpectedly, administration of the Ezh2 inhibitor GSK126, which specifically decreases H3K27me3 without affecting Ezh2 protein, failed to prevent the disease. In contrast, destabilizing T-cell Ezh2 protein by inhibiting Hsp90 using its specific inhibitor AUY922 reduced GVHD in mice undergoing allogeneic HSCT. In vivo administration of AUY922 selectively induced apoptosis of activated T cells and decreased the production of effector cells producing interferon γ and tumor necrosis factor α, similar to genetic deletion of Ezh2. Introduction of Ezh2 into alloreactive T cells restored their expansion and production of effector cytokines upon AUY922 treatment, suggesting that impaired T-cell alloreactivity by inhibiting Hsp90 is achieved mainly through depleting Ezh2. Mechanistic analysis revealed that the enzymatic SET domain of Ezh2 directly interacted with Hsp90 to prevent Ezh2 from rapid degradation in activated T cells. Importantly, pharmacological inhibition of Hsp90 preserved antileukemia activity of donor T cells, leading to improved overall survival of recipient mice after allogeneic HSCT. Our findings identify the Ezh2-Hsp90 interaction as a previously unrecognized mechanism essential for T-cell responses and an effective target for controlling GVHD.

Although majority of pediatric acute myeloid leukemia (pAML) undergo complete remission (CR) after chemotherapy, more than 30% of which eventually relapse, leading to a dismal outcome. Chemo-resistant cells at CR, measured as minimal residual disease (MRD), are thought to be origin for relapse. Although more sensitive detection of MRD has been achieved through genetic mutations, the pathological and clinical significance for most of the detected mutations remain unknown, largely due to a lack of understanding for the biological context where the mutation resides. The idea of retention of leukemia stem cells (LSCs) as a mechanism of chemo-resistance has not been demonstrated post-therapy in patients. Here we applied single cell RNA sequencing (scRNA-seq) on 14 pAML who met the criteria for clinical CR (n=11) and partial remission (PR, n=3) to determine the cellular heterogeneity and cancerous feature of the residual cells that can survive chemotherapy at remission. These patients carried common genetic mutations such as AML1-ETO, CBFB-MYH11 and FLT3-ITD, which represents genetically diverse WHO subtypes. To maximize the power to detect tumor cells that can survive chemotherapy, we used 54 unsorted total bone marrow (BM) and/or peripheral blood (PB) nucleated cells collected at diagnosis and Day 26 (D26) of the first cycle of chemotherapy for 10X genomics' scRNA-seq. Cells from each pAML were compiled into one UMAP together with normal reference using unsupervised clustering to distinguish tumor clusters from normal. Clusters were defined to be tumor if patient's diagnosis contributed at least 80% of the cells, and were confirmed by the presence of somatic mutations and/or known AML mRNA expression signature associated with chromosome translocations. By projecting onto the closest normal hematopoietic cells based on transcription features, the tumor cells were classified as one of the 12 cell types (HSC/MPP, LMPP, GMP, MEP, E/B/M, CLP, classical/nonclassical Monocyte, cDC, pDC, and pre/inmature Neutrophil like cells). Consistently with findings in adult AML, cell populations were heterogeneous at diagnosis with 5-9 distinct clusters. Interestingly, majority (9/11) of the patients had 1-6 tumor clusters detected (mean 52 cells per cluster) at D26 post-chemotherapy. These D26 residual tumor cells possessed mutations originally detected by genomic sequencing and/or known AML signatures, and consistently clustered with tumor cells from diagnosis. These residual tumor cells accounted for average 1.4% of total BM cells at D26, while the morphological examination and flow cytometry analysis of MRD showed average 4.0% and 0.71% of tumor cells. To further evaluate the chemo-resistant potential of identified residual tumor cells, we focused on three distinct features known to be associated with chemo-resistance in mouse models, including LSC activity, active oxidative phosphorylation (OXPHOS) or leukemic-regenerating cell (LRC) state. Among the total 18 residual tumor clusters detected at D26, 33.3% (6/18) exhibited expression signatures associated with at least one chemo-resistant features. The remaining clusters consisted more differentiated progenitor/monocyte-like cells. Specifically, three patients (1 PR and 2 CR) had the HSC/MPP or LMPP-like clusters possessing strong LSC and OXPHOS-associated signatures. The remaining one patient had cDC-like cluster expressing reported LRC signature. Importantly, all these four patients had either unfavorable cytogenetics or persistence of driver mutations detected by PCR. Taken together, these data showed that pediatric AMLs represented heterogeneous populations at both diagnosis and remission. Among the residual tumor clusters that survived chemotherapy, a small fraction (6/18) were HSC/MPP-like, LMPP-like and cDC-like cells with known chemo-resistant expression features. These findings provide the first in vivo characterization of cellular heterogeneity in chemo-treated pAML with complete remission. Further studies are needed to determine the molecular characteristics of these residual cells that may convey chemo-resistance and to determine whether the presence of these cells are associated with increased risk of relapse. Disclosures No relevant conflicts of interest to declare.

Autoimmune hemolytic anemia (AIHA) is a rare disease in children, and its clinical severity varies. To better understand disease manifestation and treatment outcome, we analyzed 68 children diagnosed as AIHA for clinical characteristics, laboratory findings, and treatment outcomes. Data show that primary AIHA accounted for 39.7% of all patients, whereas secondary AIHA accounted for 60.3%. Among them, Evans syndrome (ES) accounted for 20 cases (29.4%). Average hemoglobin was lower in the 1-year or below age group than in the above 1-year age group, combined-antibody group than single-antibody group, and IgM-contained group than non-IgM-contained group (P

Importance A randomized clinical trial is needed to determine whether the second-generation Abl–tyrosine kinase inhibitor dasatinib is more effective than the first-generation inhibitor imatinib mesylate for childhood Philadelphia chromosome–positive acute lymphoblastic leukemia (ALL). Objective To determine whether dasatinib given at a daily dosage of 80 mg/m2is more effective than imatinib mesylate at a daily dosage of 300 mg/m2to improve event-free survival of children with Philadelphia chromosome–positive ALL in the context of intensive chemotherapy without prophylactic cranial irradiation. Design, Setting, and Participants This open-label, phase 3 randomized clinical trial was conducted at 20 hospitals in China. Enrollment occurred from January 1, 2015, through September 18, 2018, and randomization was stopped on October 4, 2018, when the early stopping criterion of the trial was met. Patients aged 0 to 18 years were recruited. Of the 225 patients with the diagnosis, 35 declined participation and 1 died before treatment, leaving 189 patients available for analysis. Data were analyzed from January 1 through August 4, 2019. Interventions Patients were randomized to receive daily dasatinib (n = 92) or imatinib (n = 97) continuously for the entire duration of ALL therapy from the time of diagnosis made during remission induction to the end of continuation therapy. Main Outcomes and Measures The primary outcome was event-free survival, analyzed based on intention to treat. The secondary outcomes were relapse, death due to toxic effects, and overall survival. Results Among the 189 participants (136 male [72.0%]; median age, 7.8 [interquartile range (IQR), 5.2-11.3] years) and a median follow-up of 26.4 (IQR, 16.3-34.1) months, the 4-year event-free survival and overall survival rates were 71.0% (95% CI, 56.2%-89.6%) and 88.4% (95% CI, 81.3%-96.1%), respectively, in the dasatinib group and 48.9% (95% CI, 32.0%-74.5%;P = .005, log-rank test) and 69.2% (95% CI, 55.6%-86.2%;P = .04, log-rank test), respectively, in the imatinib group. The 4-year cumulative risk of any relapse was 19.8% (95% CI, 4.2%-35.4%) in the dasatinib group and 34.4% (95% CI, 15.6%-53.2%) in the imatinib group (P = .01, Gray test), whereas the 4-year cumulative risk of an isolated central nervous system relapse was 2.7% (95% CI, 0.0%-8.1%) in the dasatinib group and 8.4% (95% CI, 1.2%-15.6%) in the imatinib group (P = .06, Gray test). There were no significant differences in the frequency of severe toxic effects between the 2 treatment groups. Conclusions and Relevance Intensive chemotherapy including dasatinib at a dosage of 80 mg/m2per day yielded superior results in the treatment of Philadelphia chromosome–positive ALL compared with imatinib mesylate at a dosage of 300 mg/m2per day and provided excellent control of central nervous system leukemia without the use of prophylactic cranial irradiation. Trial Registration Chinese Clinical Trial Registry:ChiCTR-IPR-14005706

ObjectivesBefore 2003, most children with acute lymphoblastic leukaemia (ALL) abandoned treatment, with only approximately 30% treated in China. With the development of national insurance for underprivileged patients, we assessed the current frequency and causes of treatment abandonment among patients with ALL who were enrolled in the Chinese Children’s Cancer Group ALL protocol between 2015 and 2016.MethodsDemographic, clinical and laboratory data on patients who abandoned treatment, as well as economic and sociocultural data of their families were collected and analysed. General health-related statistics were retrieved from publicly accessible databanks maintained by the Chinese government.ResultsAt a median follow-up of 119 weeks, 83 (3.1%, 95% CI 2.5% to 3.8%) of the 2641 patients abandoned treatment. Factors independently associated with abandonment included standard/high-risk ALL (OR 2.62, 95% CI 1.43 to 4.77), presence of minimal residual disease at the end of remission induction (OR 3.57, 95% CI 1.90 to 6.74) and low-income economic region (OR 3.7, 95% CI 1.89 to 7.05). According to the family members, economic constraints (50.6%, p=0.0001) were the main reason for treatment abandonment, followed by the belief of incurability, severe side effects and concern over late complications.ConclusionsThe rate of ALL treatment abandonment has been greatly reduced in China. Standard/high-risk ALL, residence in a low-income region and economic difficulties were associated with treatment abandonment.Clinical trial registration numberChiCTR-IPR-14005706, pre-results.

Background Small GTP binding protein Rac1 is a component of NADPH oxidases and is essential for superoxide-induced cell death. Rac1 is activated by guanine nucleotide exchange factors (GEFs), and this activation can be blocked by regulator of chromosome condensation 2 (RCC2), which binds the switch regions of Rac1 to prevent access from GEFs. Methods Three cancer cell lines with up- or down-regulation of RCC2 were used to evaluate cell proliferation, apoptosis, Rac1 signaling and sensitivity to a group of nine chemotherapeutic drugs. RCC2 expression in lung cancer and ovarian cancer were studied using immunochemistry stain of tumor tissue arrays. Results Forced RCC2 expression in tumor cells blocked spontaneous- or Staurosporine (STS)-induced apoptosis. In contrast, RCC2 knock down in these cells resulted in increased apoptosis to STS treatment. The protective activity of RCC2 on apoptosis was revoked by a constitutively activated Rac1, confirming a role of RCC2 in apoptosis by regulating Rac1. In an immunohistochemistry evaluation of tissue microarray, RCC2 was over-expressed in 88.3% of primary lung cancer and 65.2% of ovarian cancer as compared to non-neoplastic lung and ovarian tissues, respectively. Because chemotherapeutic drugs can kill tumor cells by activating Rac1/JNK pathway, we suspect that tumors with RCC2 overexpression would be more resistant to these drugs. Tumor cells with forced RCC2 expression indeed had significant difference in drug sensitivity compared to parental cells using a panel of common chemotherapeutic drugs. Conclusions RCC2 regulates apoptosis by blocking Rac1 signaling. RCC2 expression in tumor can be a useful marker for predicting chemotherapeutic response.

Acute myeloid leukemia (AML) in children is a complex and heterogeneous disease. The identification of reliable and stable molecular biomarkers for diagnosis, especially early diagnosis, remains a significant therapeutic challenge. Aberrant microRNA expression could be used for cancer diagnosis and treatment selection. Here, we describe a novel bioinformatics model for the prediction of microRNA biomarkers for the diagnosis of paediatric AML based on computational functional analysis of the microRNA regulatory network substructure. microRNA-196b, microRNA-155 and microRNA-25 were identified as putative diagnostic biomarkers for pediatric AML. Further systematic analysis confirmed the association of the predicted microRNAs with the leukemogenesis of AML. In vitro q-PCR experiments showed that microRNA-155 is significantly overexpressed in children with AML and microRNA-196b is significantly overexpressed in subgroups M4-M5 of the French-American-British classification system. These results suggest that microRNA-155 is a potential diagnostic biomarker for all subgroups of paediatric AML, whereas microRNA-196b is specific for subgroups M4-M5.

The success of treating a wide variety of pediatric diseases with HSCT, hematologic malignancies in particular, has resulted in an increased number of long-term survivors. This study is the first large-scale, multicentre report that describes the evolution of pediatric HSCTs in China during the period of 1998-2012. Of all 1052 patients, 266 cases were treated with autologous HSCs and 786 used allogeneic HSCs. The disease indications for HSCTs mainly included leukemias, lymphoma, solid tumors, and non-malignant disorders. The total number of HSCTs, especially unrelated donor transplants, appeared to be increasing year by year. For patients with neuroblastoma, the therapeutic efficacy seemed to be poor, with a five-yr OS and DFS rate of 34.5 ± 14.3% and 20.7 ± 9.6%, respectively. In contrast, the survival of patients with SAA was prominently improved, and their five-yr OS and DFS rates were 82.8 ± 4% and 80.7 ± 4.1%, respectively. Patients who received cord blood transplants had a lower incidence of acute GVHD than that of PB and/or BM transplants from unrelated donors. This report offers us a valuable resource for evaluating the changes in HSCTs in China over the past 14 yr.

Polo-like kinase 1 (PLK1) is highly expressed in many cancers and therefore a biomarker of transformation and potential target for the development of cancer-specific small molecule drugs. RO3280 was recently identified as a novel PLK1 inhibitor, however its therapeutic effects in leukemia treatment are still unknown. We found that the PLK1 protein was highly expressed in leukemia cell lines as well as 73.3% (11/15) of pediatric acute myeloid leukemia (AML) samples. PLK1 mRNA expression was significantly higher in AML samples compared with control samples (82.95 ± 110.28 vs. 6.36 ± 6.35, p &lt, 0.001). Kaplan-Meier survival analysis revealed that shorter survival time correlated with high tumor PLK1 expression (p = 0.002). The 50% inhibitory concentration (IC50) of RO3280 for acute leukemia cells was between 74 and 797 nM. The IC50 of RO3280 in primary acute lymphocytic leukemia (ALL) and AML cells was between 35.49 and 110.76 nM and 52.80 and 147.50 nM, respectively. RO3280 induced apoptosis and cell cycle disorder in leukemia cells. RO3280 treatment regulated several apoptosis-associated genes. The regulation of DCC, CDKN1A, BTK, and SOCS2 was verified by western blot. These results provide insights into the potential use of RO3280 for AML therapy, however, the underlying mechanisms remain to be determined.

B-cell acute lymphoblastic leukemia is the most common type of pediatric leukemia. Despite improved remission rates, current treatment regimens for pediatric B-cell acute lymphoblastic leukemia are often associated with adverse effects and central nervous system relapse, necessitating more effective and safer agents. Bafilomycin A1 is an inhibitor of vacuolar H(+)-ATPase that is frequently used at high concentration to block late-phase autophagy. Here, we show that bafilomycin A1 at a low concentration (1 nM) effectively and specifically inhibited and killed pediatric B-cell acute lymphoblastic leukemia cells. It targeted both early and late stages of the autophagy pathway by activating mammalian target of rapamycin signaling and by disassociating the Beclin 1-Vps34 complex, as well as by inhibiting the formation of autolysosomes, all of which attenuated functional autophagy. Bafilomycin A1 also targeted mitochondria and induced caspase-independent apoptosis by inducing the translocation of apoptosis-inducing factor from mitochondria to the nucleus. Moreover, bafilomycin A1 induced the binding of Beclin 1 to Bcl-2, which further inhibited autophagy and promoted apoptotic cell death. In primary cells from pediatric patients with B-cell acute lymphoblastic leukemia and a xenograft model, bafilomycin A1 specifically targeted leukemia cells while sparing normal cells. An in vivo mouse toxicity assay confirmed that bafilomycin A1 is safe. Our data thus suggest that bafilomycin A1 is a promising candidate drug for the treatment of pediatric B-cell acute lymphoblastic leukemia.

Acute lymphoblastic leukemia (ALL) is the most common malignancy among children. The trial Chinese Children Leukemia Group (CCLG)-ALL 2008 was a prospective clinical trial designed to improve treatment outcome of childhood ALL through the first nation-wide collaborative study in China. Totally 2231 patients were recruited from ten tertiary hospitals in eight cities. The patients were stratified according to clinical-biological characteristics and early treatment response. Standard risk (SR) and intermediate risk (IR) groups were treated with a modified BFM based protocol, and there was 25%-50% dose reduction during intensification phases in the SR group. Patients in high risk (HR) group received a more intensive maintenance treatment. Minimal residual disease (MRD) monitoring with treatment adjustment was performed in two hospitals (the MRD group). Complete remission (CR) was achieved in 2100 patients (94.1%). At five years, the estimate for overall survival (OS) and event-free survival (EFS) of the whole group was 85.3% and 79.9%, respectively. The cumulative incidence of relapse (CIR) was 15.3% at five years. The OS, EFS and CIR for the SR group were 91.5%, 87.9%, and 9.7%, respectively. The outcome of the MRD group is better than the non-MRD group (5y-EFS: 82.4% vs 78.3%, P = .038; 5y-CIR: 10.7% vs 18.0%, P < .001). Our results demonstrated that the large-scale multicenter trial for pediatric ALL was feasible in China. Dose reduction in the SR group could achieve high EFS. MRD-based risk stratification might improve the treatment outcome for childhood ALL.

The 8p11 myeloproliferative syndrome (EMS) is an aggressive neoplasm associated with chromosomal translocations involving the fibroblast growth factor receptor 1 (FGFR1) tyrosine kinase gene on chromosome 8p11-12. A new case of a 9-year-old boy with leukocytosis, eosinophilia, and general lymphadenopathy is reported in this study. Bone marrow examination showed eosinophilic hyperplasia, with blast cells amounting to 6-7%. Karyotyping revealed cytogenetic abnormalities, including t(8;9)(p11.2;q3?3). Fluorescence in situ hybridization for the FGFR1 gene rearrangement yielded positive results. Lymph node biopsy confirmed the diagnosis of precursor T-lymphoblastic lymphoma. The patient responded to chemotherapy, and unmatched related bone marrow transplantation was performed. A successful outcome was obtained with complete cytogenetic remission maintained for 14 months to date. In the future, FGFR1 inhibitors might be specific and effective therapeutic targets for EMS. Similar cases from the literature are reviewed.

Background Overexpression of cyclin D1 dependent kinases 4 and 6 (CDK4/6) is a common feature of many human cancers including leukemia. LEE011 is a novel inhibitor of both CDK4 and 6. To date, the molecular function of LEE011 in leukemia remains unclear. Methods Leukemia cell growth and apoptosis following LEE011 treatment was assessed through CCK-8 and annexin V/propidium iodide staining assays. Cell senescence was assessed by β-galactosidase staining and p16INK4a expression analysis. Gene expression profiles of LEE011 treated HL-60 cells were investigated using an Arraystar Human LncRNA array. Gene ontology and KEGG pathway analysis were then used to analyze the differentially expressed genes from the cluster analysis. Results Our studies demonstrated that LEE011 inhibited proliferation of leukemia cells and could induce apoptosis. Hoechst 33,342 staining analysis showed DNA fragmentation and distortion of nuclear structures following LEE011 treatment. Cell cycle analysis showed LEE011 significantly induced cell cycle G1 arrest in seven of eight acute leukemia cells lines, the exception being THP-1 cells. β-Galactosidase staining analysis and p16INK4a expression analysis showed that LEE011 treatment can induce cell senescence of leukemia cells. LncRNA microarray analysis showed 2083 differentially expressed mRNAs and 3224 differentially expressed lncRNAs in LEE011-treated HL-60 cells compared with controls. Molecular function analysis showed that LEE011 induced senescence in leukemia cells partially through downregulation of the transcriptional expression of MYBL2. Conclusions We demonstrate for the first time that LEE011 treatment results in inhibition of cell proliferation and induction of G1 arrest and cellular senescence in leukemia cells. LncRNA microarray analysis showed differentially expressed mRNAs and lncRNAs in LEE011-treated HL-60 cells and we demonstrated that LEE011 induces cellular senescence partially through downregulation of the expression of MYBL2. These results may open new lines of investigation regarding the molecular mechanism of LEE011 induced cellular senescence. Electronic supplementary material The online version of this article (doi:10.1186/s12935-017-0405-y) contains supplementary material, which is available to authorized users.

Introduction: Septicemia is one of the common complications after chemotherapy for acute lymphoblastic leukemia (ALL) and is also an important cause of treatment related mortality and treatment failure. A multicenter study CCCG-ALL-2015 was conducted in China and factors associated with septicemia and mortality were studied. Methods: Patients participated in CCCG-ALL-2015 study from January 2015 to December 2017 were included in this study. Patients with documented septicemia were identified from the Database of Central Data Center. Additional data were then collected from participation centers, including associated co-morbidity, blood counts before septicemia and infection preventive measures. Results: A total of 4080 patients were recruited from 18 centers. There were 527 patients with septicemia identified (12.9%). The Intermediate risk (IR)/ High risk (HR) group(n=1930) had significantly higher incidence of septicemia as compared with Low risk (LR) group (n=2150), 17.15% vs 9.12% (p Conclusion: Overall the incidence and pattern of septicemia in this multicenter study in China was similar to reports of western countries. The septicemia related mortality rate was low. However there was marked variation in the incidence of septicemia among the centers, further studies are required to validate factors such as infection preventive measures which might influence the septicemia incidence. Disclosures No relevant conflicts of interest to declare.

Background: Acute megakaryocytic leukemia (AMKL) is a rare subtype of acute myeloid leukemia (AML) with a dismal outcome in children without Down syndrome. Refractory or relapsed disease accounts for treatment failure in most cases. Hematopoietic stem cell transplantation (HSCT) is recommended as post-remission therapy, although some patients have been cured with intensive chemotherapy alone. Genetic and genomic abnormalities are common in AMKL, but their prognostic significance is not known. In this study, we analyzed AMKL using high-throughput sequencing in addition to conventional morphology, immunophenotype, cytogenetic, and molecular (MICM) approaches. Methods: From February 2015 to April 2019, 19 cases of AMKL in non-Down syndrome patients were diagnosed according to conventional methods in our center. All patients, except one, were treated using a low-dose chemotherapy (LDC) regimen (cytarabine 10 mg/m2, subcutaneously every 12 h, 20 doses; mitoxantrone 5 mg/m2 days 1, 3 and 5, and G-CSF 5µ/kg subcutaneous, daily, 10 doses) for induction remission followed by four courses of intensive chemotherapy or hematopoietic stem cell transplantation (HSCT) as post-remission consolidation[1]. Patients were treated with consolidation chemotherapy if parents refused HSCT. High-throughput mutational sequencing of leukemia cells obtained at diagnosis was performed. The average sequencing depth was 500-1000× and analyses were performed using mGATK, SAMTools, SIFT, PolyPhen2, LRT, and MutatioinTaster methods. Results: The average age at diagnosis of AMKL of the nine boys and 10 girls was 19.7 months (7-53 months). Eighty-four percent of the cases were younger than 2 years of age. The 19 patients with AMKL represent 10% of cases diagnosed with AML during the study period. The median initial white blood cell (WBC) count was 13×109/L(2.38-126×109/L)and the average blasts at initial bone marrow (BM) was 54.5% (13-85%). In all cases of AMKL, more than 25% of cells were positive for CD41. Sixty-three percent of patients had recurrent fusion genes, including NUP98-KDM5A, HOXA11-AS/ANGPT1, CBFA2T3-GLIS2, KMT2A-MLLT3, RBM15-MKL1. Also, we identified PICALM-MLL10, TNIP1-CSF1R, NUP98-TAF3, and CBFA2T3-GLIS1 fusion genes which had not been previously reported in AMKL. EVI-1 expression was evaluated in all cases and was overexpressed in two cases. Forty-seven percent of patients showed at least single-gene mutations, including JAK2, MPL, KRAS, NRAS, TP53, NTRK3, MYO16, PDGFB, FLT3, and others. The response rate after remission induction I (IND-I) were 84.2% with 63.1% (12/19) attaining complete remission (CR) and 21.1% (4/19) partial remission (PR). After IND-II, the CR, PR, and no response (NR) rates was 68.4%, 10.5%, and 21.1%, respectively. Four patients (21.1%) were refractory to induction chemotherapy. Seven patients (36.8%) relapsed, three during consolidation chemotherapy courses, and four after transplantation (Table 1). Currently, 75% (6/8) patients who received chemotherapy only for consolidation were alive (median follow-up time 27 months). Eleven patients underwent allo-HSCT, and 8 patients are alive, including 6 cases living without evidence of disease. Four patients relapsed after allo-HSCT, and two of them have died. One additional patient died of transplantation related mortality. The 4-year OS, RFS, and EFS in this cohort were 62.4%±13.9%, 54.1±13.0% and 40.5±11.5%, respectively (Figure 1).Conclusion: Non-Down syndrome AMKL is genetically heterogeneous with recurrent and new fusion genes. Patients treated with LDC for induction followed by intensive chemotherapy or HSCT for consolidation have outcome comparable to those treated with intensive induction regimens. New treatment strategies are needed to improve the outcome of pediatric AMKL. Figure 1 Disclosures No relevant conflicts of interest to declare.

Promoting donor T cell tolerance to host non-hematopoietic tissues remains the ultimate therapeutic goal in allogeneic hematopoietic stem cell transplantation (allo-HSCT). Dendritic cells (DCs) play dual functions in regulating alloimmunity. DCs can elicit alloreactive T cell responses to mediate graft-versus-host disease (GVHD), but are also implicated in reducing GVHD. In patients, the depletion of plasmacytoid DCs (pDCs) from donor BM grafts resulted in GVHD acceleration. On the other hand, acute GVHD causes complete failure of donor pDC reconstitution after allo-HSCT, and low levels of donor pDC correlate with significantly increased GVHD severity. Thus, the impairment of pDC reconstitution by GVHD may be responsible for the dysfunctional immune regulation. Delineation of the mechanism involved may allow therapeutic intervention to reduce GVHD and improve the efficacy of allo-HSCT. In this study, we demonstrate that alloreactive T cells produce GM-CSF to impair reconstitution of donor pDCs by inhibiting Flt3 expression and its-regulated transcription programs in DC progenitor cells. Using murine GVHD model, we confirmed GVHD severely impaired reconstitution of both donor pDCs and conventional DCs (cDCs). Adoptive transfer of donor-type pDCs rather than cDCs prevented the occurrence of severe GVHD in mice, suggesting donor pDC reconstitution is important to restore tolerance of donor T cells against host tissues. Flt3 is required to induce pDC production through a successive differentiation pathway: HSC → multiple potential progenitors (MPP) → common DC progenitors (CDP) → precursor DCs (pre-DCs). GVHD mice produced significantly less MPP, CDP and pre-DCs compared to normal donor mice and allogeneic mice receiving T cell-depleted BM. Ex vivo culture with Flt3 ligand (Flt3L) showed that those MPP and CDP derived from GVHD mice dramatically decreased the capacity to produce pDCs. Thus, GVHD not only causes decreased numbers of MPP and CDP but also their intrinsic defect in producing pDCs. While both MPP and CDP gave rise to similar numbers of pDCs within 3 days of culture with Flt3L, MPP produced 40-fold more pDCs than CDP by day 9 of culture. This indicates the impairment in GVHD MPP may have much more profound long-term impact on pDC reconstitution than that in CDP. Based on surface expression of Flt3, normal MPP contained two subsets: CD135high MPP and CD135mod MPP. CD135high MPP produced 4-fold more pDCs than CD135mod MPP. As compared to CD135mod MPP, CD135high MPP expressed lower levels of Ink4 family genes, which are cyclin-dependent inhibitors restraining cell proliferation and survival, suggesting that CD135high MPP represent earlier stage differentiated progenitors with greater proliferative capacity. Intriguingly, although GVHD mice generated similar amount of CD135mod MPP as did normal mice, they failed to reconstitute highly proliferative CD135high MPP. Thus, the failure of donor pDC reconstitution may largely result from GVHD-mediated inhibition of CD135high MPP. Alloreactive T cells are known to produce high levels of effector molecules, such as IFN-γ, TNF-α, GM-CSF and other cytolytic molecules. We observed that GVHD effector T cells significantly reduced the production of pDCs from Flt3L-induced normal MPP. Blocking GM-CSF using neutralizing antibody but not other effector molecules markedly inhibited this repressive effect of GVHD T cells on pDC production. GM-CSF dose-dependently decreased the expression of Flt3 and its-regulated transcription factors Irf8 and Tcf4, which are important for development of functional pDCs. However, GM-CSF failed to inhibit the conversion of SiglecH+ pre-pDCs into pDCs. These data suggest that alloreactive T cells produce GM-CSF to block pDC reconstitution by targeting DC progenitors (e.g., MPP and CDP). Building on these findings, we established a novel optimized culture system to produce adequate numbers of SiglecH+ pre-pDCs. Adoptive transfer of these pre-pDCs prevented GVHD, leading to significantly improved overall survival of mice undergoing allo-HSCT. Our findings identify for the first time that selective restoration of donor pDCs early after allo-HSCT may represent an effective cellular therapy to prevent GVHD. Further delineation of the molecular pathway(s) involved in GVHD inhibition of DC progenitors may allow the development of novel approaches to circumvent mortality and morbidity associated with GVHD. Disclosures Zheng: Pfizer: Research Funding.

Graft-versus-host-disease (GVHD) remains a leading cause of transplant-related mortality (TRM) in patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT). Patients who do not respond to GVHD therapy are at high risk for death without relapse. Strategies that can predict the development of severe GVHD in transplant patients may improve risk stratification for steroids treatment refractory GVHD and TRM. Dendritic cells (DCs) play nonredundant roles in regulating both immunity and tolerance. Clinical and pre-clinical studies suggest that GVHD causes dysregulated development of functional DCs and impaired reconstitution of donor DCs is associated with increased risk of severe GVHD. We demonstrate that donor plasmacytoid DC (pDC) reconstitution around the engraftment time is a useful predictor for the development of severe GVHD in children after allo-HSCT. We examined reconstitution of donor DCs, including total DCs (lineage-negative (LIN-)HLADR+), pDCs (LIN-HLADR+CD123+CD1c-) and CD1c+DCs (LIN-HLADR+CD123-CD1c+), in peripheral blood of patients undergoing allo-HSCT, using age-matched healthy children as controls. The median time for engraftment was 14 days (range, 13.0~17 days), whereas clinical signs of GVHD occurred approximately 10 days later (median time, 24 days;range, 18~35 days). Thus, measuring the number and frequency of circulating blood DCs early at the engraftment time allowed us to evaluate the subsequent occurrence of GVHD. Transplant patients were followed up for 6 months after allo-HSCT. Of evaluable 45 transplant patients, 27 patients had no GVHD (grade 0) or mild GVHD (grade I), and 18 patients developed severe GVHD (grade II-IV GVHD). Patients who developed grade II-IV GVHD had no significant difference in frequency ( median, 0.2%; range, 0.04~0.35%) and number (median, 1.6 cell/ml; range, 1~3.8 cell/ml) of total DCs than patients with grade 0-I GVHD (median frequency, 0.41%; range, 0.15~0.63%, P Disclosures No relevant conflicts of interest to declare.

Normal human hematopoietic stem and progenitor cells (HSPCs) express functional complement anaphylatoxin C3a receptor (C3aR), and the C3aR–C3a axis sensitizes the responses of these cells to stroma...

Histone modification enzymes regulate gene expression by altering the accessibility of promoters to transcription factors. We sought to determine whether the genes encoding histone modification enzymes are dysregulated in pediatric acute lymphoblastic leukemia (ALL). A real-time PCR array was designed, tested and used to profile the expression of 85 genes encoding histone modification enzymes in bone marrow mononuclear cells from 30 pediatric ALL patients and 20 normal controls. The expression profile of histone-modifying genes was significantly different between normal karyotype B cell pediatric ALL and normal controls. Eleven genes were upregulated in pediatric ALL, including the histone deacetylases HDAC2 and PAK1, and seven genes were downregulated, including PRMT2 and the putative tumor suppressor EP300. Future studies will seek to determine whether these genes serve as biomarkers of pediatric ALL. Ingenuity Pathway Analysis revealed that Gene Expression and Organ Morphology was the highest rated network, with 13 focus molecules (significance score = 35). Ingenuity Pathway Analysis also indicated that curcumin and miR-34 are upstream regulators of histone-modifying enzymes; future studies will seek to validate these results and examine the role of curcumin and miR-34 in leukemia. This study provides new clues into the molecular mechanisms of pediatric ALL.

Purpose: Prognosis and therapeutic treatment of Fanconi anemia (FA) and acquired aplastic anemia (AA) are different. However, delayed and incorrect treatments are frequently occurred in FA because its symptoms are very similar to those of AA. This study aimed to elucidate the differences between FA and AA at the molecular level and to identify biomarkers and pathways of FA through quantitative proteomics and bioinformatics analyses. Methods: Samples were obtained from the bone marrow of patients with FA and AA followed the institutional guideline. Proteins were extracted, digested with Lys-C and trypsin, and chemically labeled with tandem mass tag (TMT) duplex reagents (TMT126 and 127) for mass spectrometric analyses. Proteins with fold changes of > 1.5 or < 0.667 were considered as differentially expressed proteins (DEPs). Gene ontology analysis was performed using the Database for Annotation, Visualization and Integrated Discovery. Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses were conducted using the ClueGO plug-in in Cytoscape. A DEP-associated protein-protein interaction (PPI) network was constructed using STRING and visualized in Cytoscape. The degree and topological index of these DEPs were calculated using CentiScape. The PPI network was subjected to modular analysis using the Molecular Complex Detection plug-in in Cytoscape. Results: A total of 114 DEPs, including 71 upregulated and 43 downregulated proteins, were discovered in the FA sample compared with those in the AA sample. The upregulated proteins were enriched in nucleosome assembly, cell or subcellular component movement, glycolysis, and gluconeogenesis pathway. The downregulated proteins were enriched in immune response, negative regulation of apoptosis, proteolysis, phagosome, and pantothenate and CoA biosynthesis. Five important modules were detected from the PPI network of DEPs. Eight hub proteins, a-enolase (ENO1), phosphoglycerate kinase 1 (PGK1), HSP90AA1, HSP90AB1, ACTC1, ACTBL2, EEF1A1, and CFL1, with a high degree of connectivity were obtained. Conclusions: Quantitative proteomics coupled with bioinformatics analyses are useful for the identification of protein biomarkers and pathways associated with FA and AA. Some critical DEPs, such as ENO1, PGK1, ACTC1, ACTBL2, EEF1A1, and CFL1, likely play important roles in FA and could be used as serologic markers for its early diagnosis and to distinguish FA from AA. Disclosures No relevant conflicts of interest to declare.

Objective: To investigate the incidence, clinical characteristics and prognosis of nervous system (NS) complications after hematopoietic stem cell transplantation (HSCT) in children. Methods: Three hundred children who received HSCT from October 2010 to June 2018 were retrospectively analyzed to identify NS complications in our center. Factors which may be related to NS complications were figured out. Median follow-up time is 3.9 years (range, 0.2- 7.7 years). Results: Among 300 cases with transplantation, 290 cases were allogeneic transplantation, 9 Autologous transplantation and one case with Isogenic transplantation. The median age was 8 years old (0.7-16 years old), and median weight was 25kg (7-88kg).47.33% of them were male(142/300). Of 290 allogeneic transplantation, 79 cases received sibling matched transplantation, 90 cases received non-relative cord blood transplantation, and 121 cases were haploididentical transplantation. Diseases distribution was as following: 48 cases with aplastic anemia (AA), 174 cases with acute leukemia(AL), 4 cases with chronic myelocytic leukemia (CML), 1 case with juvenile Myelomonocytic Leukemia (JMML),12 cases with myelodysplastic/myeloproliferative neoplasm(MDS/MPN), 28 cases with Wiskott-Aldrich syndrome(WAS), 5 cases with Fanconi anemia (FA), 6 cases with thalassemia, 5 cases with neuroblastoma, one case with neuroblastoma and acute myeloid leukemia, 16 cases with other congenital disorders. Twenty six children developed NS complications after HSCT which accounted for 8.67% (26/300). The diseases which developed NS complications from high to low were as following: FA (33.3%), MDS/MPN (19.2%), AL (7.3%), AA (7.0%), 3.1% in genetic immunodeficiency disease. The average age of children who developed NS complications was 8.3±3.8years old which was older than non- NS complications (6.5±4.0 years old) (p=0.02). Different types of NS complications included 23.1% of demyelinating encephalopathia, 30.8% of cerebral acute graft versus host disease(GVHD), 15.4% of hypertension encephalopathia,11.5% of cerebrovascular lesion, one case of transplantation associated thrombotic microangiopathy (TA-TMA),7.7% of drug therapy-related toxic encephacopathy,3.8% of metabolic encephalopathy,7.7% of peripheral neuropathy. The mortality of NS complications was 34.6%. Of 8 cases with cerebral GVHD, 5 cases died which had the highest mortality (62.5%). No patients with drug therapy-related toxic encephacopathy, metabolic encephalopathy, and peripheral neuropathy died. The overall survival in children with NS complications is lower than the children without NS complications after HSCT (65.4% vs 84.2%, p=0.015). Conclusions: The incidence of NS complications after HSCT was correlated with primary diseases and children's age. Patients with drug therapy-related toxic encephacopathy, metabolic encephalopathy and peripheral neuropathy had better prognosis than cerebral GVHD and TA-TMA patients. Reduction of NS complications may improve long term survival of children after HSCT. Disclosures No relevant conflicts of interest to declare.

Background and Objectives: Wiskott-Aldrich syndrome (WAS) is a rare X-linked primary immunodeficiency with microthrombocytopenia. Hematopoietic stem cell transplantation is a curative treatment for WAS. Unrelated cord blood transplantation (UCBT) become a more successive alternative donor transplantation for WAS with the improvement of high resolution HLA-typing method. However, graft rejection is the primary cause for mortality of WAS after UCBT. We hypothesized that the addition of fludarabine to a myeloablative conditioning regimen with antithymocyte globulin (ATG) would support engraftment for these children. Methods: Seventeen Children with WAS underwent UBCT matched 6-10/10 at higher resolution (HLA-A, -B, -C, -DRB1and DQB1) in our center between 2013 and 2018. The conditioning regimen consisted of fludarabine 160 mg/m2 , busulfan (BU)12.8 mg/kg, cyclophosphamide (CY)120 mg/kg, ATG 7.5 mg/kg, and cyclosporine and mycophenolate for GVHD prophylaxis. Median follow-up time is 2.5 years (range, 0.2 to 3.5 years). Results: All children had sustained donor cell engraftment and are stable engraftment. Twelve (71%) patients had cytomegalovirus (CMV) antigenemia and no one developed into CMV disease. Six (35%) children underwent acute Graft-versus-host disease (GVHD) (grade II-IV) and four (24%) children developed into chronic GVHD (cGVHD). Among these cases, only one child with HLA matched 6/10 died of kidney failure because of cGVHD. He experienced aGVHD with skin bullosa. Sixteen (94%) children are survival. Conclusion: Conditioning regimen consisted of Fludarabine combined BUCY and ATG was able to reduce graft rejection in the WAS children after UCBT without increasing infection related mortality. Future efforts will focus on further reducing rates of acute GVHD and extensive cGVHD. Disclosures No relevant conflicts of interest to declare.

Plasmacytoid dendritic cells (pDCs) derived either from adoptive transfer from the donor graft or stem cell reconstitution can attenuate and prevent graft-versus-host disease (GVHD) in both pre-clinical and clinical settings. However, the reconstitution of donor pDCs is severely impaired during GVHD via an unknown mechanism. Here we demonstrate that the histone methyltransferase Dot1l, which specifically catalyzes methylation of histone H3 at lysine 79 (H3K79me), is critical for regulating the commitment and differentiation of pDCs from hematopoietic stem cells (HSCs) and we observed its function was severely impaired in GVHD mice. We have previously demonstrated that Flt3L-induced DCs can program allogeneic T cells to reduce their GVHD toxicity (Blood 2016). Using this platform, we explored candidate histone methyltransferase(s) that affected pDC development. We found the inhibitor specific to Dot1l dramatically decreased the frequency and number of pDCs in cultures compared to other chemical probes that inhibit Ezh2, MLL1, G9a and Jmjd3, respectively. Under steady-state condition, pDCs develop from HSCs through successive steps of lineage commitment and differentiation: multiple potent progenitors (MPP) → macrophage and DC progenitors (MDP) → common DC progenitors (CDP). Upon culturing in the presence of Flt3L+SCF, MPP produced 2-fold and 5-fold more pDCs than MDP and HSCs, respectively, over 6 days' incubation. For this reason, we focused on evaluating the effect of Dot1l deletion on pDC development from MPP and CDP, which represent the early and later stage of pDC progenitors, respectively. To examine the specific role of Dot1l in DC development, we crossed Dot1l conditional knock mice (Dot1lf/f) to ER-Cre B6 mice to generate ER-Cre.Dot1lf/f B6 mice. We administered tamoxifen to ER-Cre.Dot1lf/f B6 mice at day 0 and day +1 to delete Dot1l, highly purified MPP and CDP, and cultured them in the presence of Flt3L+SCF. Deletion of Dot1l led to significant decrease of (3- to 5-fold) pDCs from MPP but marginally decreased CDP production of pDCs. These results suggest that Dot1l is required for the initial commitment and differentiation of MPP into pDCs or the expansion of selected pDCs. To test it, we added Dot1l inhibitor SGC to the cultures containing wild-type (WT) mouse-derived MPP, CDP and pDCs. Inhibiting Dot1l with SGC decreased both the frequency (3-fold) and number (5-fold) of pDCs in the MPP culture compared to control, however, it did not affect the generation of pDCs from the cultures of either CDP or pDCs. Thus, Dot1l regulates the commitment and differentiation of pDCs during the MPP stage. To understand the molecular mechanism by which Dot1l regulates pDC commitment and differentiation, we examined the expression of transcription factor Tcf4, which promotes pDC development, and Id2, which antagonizes Tcf4 effects on pDCs. Dot1l inhibition led to 2-fold reduction of Tcf4 expression and 5-fold increase of Id2 in Flt3L-induced bone marrow cells. ChIP assays confirmed the presence of high amount of Dot1l-catalyzed H3K79me2 at the promoter regions of Id2 and Tcf4 loci. Retroviral introduction of Tcf4 into hematopoietic progenitors lacking Dot1l restored their capacity to produce pDCs in cultures. These findings clearly establish that Tcf4 is the down-stream effector of Dot1l to control pDC development. Building on these observations, we finally examined whether GVHD may impair the reconstitution of donor pDCs through a mechanism of reducing Dot1l expression and function. Using the C57BL/6 (B6) into Balb/c mouse GVHD model, we confirmed the loss of donor pDCs in GVHD recipients at day 14 and day 21 after transplantation and, observed that these GVHD mice had 3- to 12-fold fewer MPP and CDP compared to normal donor mice. Additionally, both HSCs and MPP derived from GVHD mice showed significant reduction of H3K79me2 compared to their normal counterparts. Finally, adoptive transfer of donor BM-derived pDCs attenuated the incidence and severity of GVHD in Balb/c mice receiving B6 T cells. Collectively, these data suggest that GVHD-mediated inflammation profoundly decreases Dot1l function in engrafted donor DC progenitors, leading to damaged reconstitution of donor pDCs. Novel strategies that target Dot1l and its-regulated transcriptional programs may improve the reconstitution of donor pDCs to inhibit GVHD while also promoting anti-leukemia activity in recipients undergoing allo-HSCT. Disclosures No relevant conflicts of interest to declare.

Background Acute myeloid leukemia (AML) is the second-most common form of leukemia in children. Aberrant DNA methylation patterns are a characteristic feature of AML. GATA4 has been suggested to be a tumor suppressor gene regulated by promoter hypermethylation in various types of human cancers although the expression and promoter methylation of GATA4 in pediatric AML is still unclear. Methods Transcriptional expression levels of GATA4 were evaluated by semi-quantitative and real-time PCR. Methylation status was investigated by methylation-specific PCR (MSP) and bisulfate genomic sequencing (BGS). The prognostic significance of GATA4 expression and promoter methylation was assessed in 105 cases of Chinese pediatric acute myeloid leukemia patients with clinical follow-up records. Results MSP and BGS analysis showed that the GATA4 gene promoter is hypermethylated in AML cells, such as the HL-60 and MV4-11 human myeloid leukemia cell lines. 5-Aza treatment significantly upregulated GATA4 expression in HL-60 and MV4-11 cells. Aberrant methylation of GATA4 was observed in 15.0 % (3/20) of the normal bone marrow control samples compared to 56.2 % (59/105) of the pediatric AML samples. GATA4 transcript levels were significantly decreased in AML patients (33.06 ± 70.94; P = 0.011) compared to normal bone marrow/idiopathic thrombocytopenic purpura controls (116.76 ± 105.39). GATA4 promoter methylation was correlated with patient leukocyte counts (WBC, white blood cells) (P = 0.035) and minimal residual disease MRD (P = 0.031). Kaplan-Meier survival analysis revealed significantly shorter overall survival time in patients with GATA4 promoter methylation (P = 0.014). Conclusions Epigenetic inactivation of GATA4 by promoter hypermethylation was observed in both AML cell lines and pediatric AML samples; our study implicates GATA4 as a putative tumor suppressor gene in pediatric AML. In addition, our findings imply that GATA4 promoter methylation is correlated with WBC and MRD. Kaplan-Meier survival analysis revealed significantly shorter overall survival in pediatric AML with GATA4 promoter methylation but multivariate analysis shows that it is not an independent factor. However, further research focusing on the mechanism of GATA4 in pediatric leukemia is required. Electronic supplementary material The online version of this article (doi:10.1186/s12885-015-1760-5) contains supplementary material, which is available to authorized users.

Chemotherapy employs chemical substances to interfere with the growth of cancer cells, and is a major treatment strategy in human cancer including acute myeloid leukemia (AML). Although they often effectively kill fast-dividing tumor cells, chemotherapeutic drugs also profoundly affect mutation spectrum of the tumor genome. Each chemotherapeutic drug has a working concentration within an appropriate range. Concentrations beyond this range will increase drug toxicity without adding clinical benefit, while concentrations below the range will result in an insufficient drug effect. The conventional strategy in oncology is to give a patient drugs at the maximum tolerated dose (MTD) in order to kill as many tumor cells as possible. However, this inevitably causes a high rate of toxicity to normal tissue, as well as resulting in new mutations and genome instability which can lead to drug resistance and relapse. The priming induction regimen of HAG (low dose of cytarabine (Ara-C) and Homoharringtonine (HHT) with granulocyte colony-stimulating factor (G-CSF) priming), has proven to be effective in subgroup of AML patients in small scale clinical studies. It is of great medical significance to explore whether low dose chemotherapy can reduce the side effect of chemotherapeutic drugs while maintaining the therapeutic benefits, and whether such alternative therapeutic strategy is advantageous compared to conventional intensive treatment regarding the development of drug resistance by affecting leukemic genome mutation load and clonal evolution in subgroup of AMLs.

Long non-coding RNA (lncRNA) plays a role in gene transcription, protein expression and epigenetic regulation; and altered expression results in cancer development. Acute myeloid leukemia (AML) is rare in children; and thus, this study profiled lncRNA expression in bone marrow samples from pediatric AML patients. Arraystar Human LncRNA Array V3.0 was used to profile differentially expressed lncRNAs in three bone marrow samples obtained from each pediatric AML patient and normal controls. Quantitative polymerase chain reaction (qRT-PCR) was performed to confirm dysregulated lncRNA expressions in 22 AML bone marrow samples. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed to construct the lncRNA-mRNA co-expression network. A total of 372 dysregulated lncRNAs (difference ≥10-fold) were found in pediatric AML patients compared to normal controls. Fifty-one mRNA levels were significantly upregulated, while 85 mRNA levels were significantly downregulated by >10-fold in pediatric AML, compared to normal controls. GO terms and KEGG pathway annotation data revealed that cell cycle pathway-related genes were significantly associated with pediatric AML. As confirmed by qRT-PCR, expression of 24 of 97 lncRNA was altered in pediatric AML compared to normal controls. In pediatric AML, ENST00000435695 was the most upregulated lncRNA, while ENST00000415964 was the most downregulated lncRNA. Data from this study revealed dysregulated lncRNAs and mRNAs in pediatric AML versus normal controls that could form gene pathways to regulate cell cycle progression and immunoresponse. Further studies are required to determine whether these lncRNAs could serve as novel therapeutic targets and bbdiagnostic biomarkers in pediatric AML.

Background Wilms’ tumor (WT) is one of the most common malignant neoplasms of the urinary tract in children. Anaplastic histology (unfavorable histology) accounts for about 10% of whole WTs, and it is the single most important histologic predictor of treatment response and survival in patients with WT; however, until now the molecular basis of this phenotype is not very clearly. Methods A real-time polymerase chain reaction (PCR) array was designed and tested. Next, the gene expression profile of pediatric anaplastic histology WT and normal adjacent tissues were analyzed. These expression data were anlyzed with Multi Experiment View (MEV) cluster software further. Datasets representing genes with altered expression profiles derived from cluster analyses were imported into the Ingenuity Pathway Analysis Tool (IPA). Results 88 real-time PCR primer pairs for quantitative gene expression analysis of key genes involved in pediatric anaplastic histology WT were designed and tested. The gene expression profile of pediatric anaplastic histology WT is significantly different from adjacent normal controls; we identified 15 genes that are up-regulated and 16 genes that are down-regulated in the former. To investigate biological interactions of these differently regulated genes, datasets representing genes with altered expression profiles were imported into the IPA for further analysis, which revealed three significant networks: Cancer, Hematological Disease, and Gene Expression, which included 27 focus molecules and a significance score of 43. The IPA analysis also grouped the differentially expressed genes into biological mechanisms related to Cell Death and Survival 1.15E−12, Cellular Development 2.84E−11, Cellular Growth and Proliferation 2.84E-11, Gene Expression 4.43E−10, and DNA Replication, Recombination, and Repair 1.39E−07. The important upstream regulators of pediatric anaplastic histology WT were TP53 and TGFβ1 signaling (P = 1.15E−14 and 3.79E−13, respectively). Conclusions Our study demonstrates that the gene expression profile of pediatric anaplastic histology WT is significantly different from adjacent normal tissues with real-time PCR array. We identified some genes that are dysregulated in pediatric anaplastic histology WT for the first time, such as HDAC7, and IPA analysis showed the most important pathways for pediatric anaplastic histology WT are TP53 and TGFβ1 signaling. This work may provide new clues into the molecular mechanisms behind pediatric anaplastic histology WT. Electronic supplementary material The online version of this article (doi:10.1186/s12935-015-0197-x) contains supplementary material, which is available to authorized users.

Acute myeloid leukemia (AML) is the second-most common form of leukemia in children. Aberrant DNA methylation patterns are characteristic of AML. Zinc finger protein 382 (ZNF382) has been suggested to be a tumor suppressor gene possibly regulated by promoter hypermethylation in various types of human cancer. However, ZNF382 expression and methylation status in pediatric AML is unknown. In the present study, ZNF382 transcription levels were evaluated by quantitative reverse-transcription PCR. Methylation status was investigated by methylation-specific (MSP) PCR and bisulfate genomic sequencing (BGS). The prognostic significance of ZNF382 expression and promoter methylation was assessed in 105 cases of pediatric AML. The array data suggested that the ZNF382 promoter was hypermethylated in the AML cases examined. MSP PCR and BGS analysis revealed that ZNF382 was hypermethylated in leukemia cell lines. Furthermore, treatment with 5-aza-2'-deoxycytidine (5-Aza) upregulated ZNF382 expression in the selected leukemia cell lines. The aberrant methylation of ZNF382 was observed in 10% (2/20) of the control samples compared with 26.7% (28/105) of the AML samples. ZNF382 expression was significantly decreased in the 105 AML patients compared with the controls. Patients with ZNF382 methylation showed lower ZNF382 transcript levels compared with patients exhibiting no methylation. There were no significant differences in clinical characteristics or cytogenetic analysis between the patients with or without ZNF382 methylation. ZNF382 methylation correlated with minimal residual disease (MRD). Kaplan-Meier survival analysis revealed similar survival times in the samples with ZNF382 methylation, and multivariate analysis revealed that ZNF382 methylation was not an independent prognostic factor in pediatric AML. The epigenetic inactivation of ZNF382 by promoter hypermethylation can be observed in AML cell lines and pediatric AML samples. Therefore, our study suggests that ZNF382 may be considered a putative tumor suppressor gene in pediatric AML. However, further studies focusing on the mechanisms responsible for ZNF382 downregulation in pediatric leukemia are required.