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PURPOSE Arsenic combined with all-trans retinoic acid (ATRA) is the standard of care for adult acute promyelocytic leukemia (APL). However, the safety and effectiveness of this treatment in pediatric patients with APL have not been reported on the basis of larger sample sizes. METHODS We conducted a multicenter trial at 38 hospitals in China. Patients with newly diagnosed APL were stratified into two risk groups according to baseline WBC count and FLT3-ITD mutation. ATRA plus arsenic trioxide or oral arsenic without chemotherapy were administered to the standard-risk group, whereas ATRA, arsenic trioxide, or oral arsenic plus reduced-dose anthracycline were administered to the high-risk group. Primary end points were event-free survival and overall survival at 2 years. RESULTS We enrolled 193 patients with APL. After a median follow-up of 28.9 months, the 2-year overall survival rate was 99% (95% CI, 97 to 100) in the standard-risk group and 95% (95% CI, 90 to 100) in the high-risk group ( P = .088). The 2-year event-free survival was 97% (95% CI, 93 to 100) in the standard-risk group and 90% (95% CI, 83 to 96) in the high-risk group ( P = .252). The plasma levels of arsenic were significantly elevated after treatment, with a stable effective level ranging from 42.9 to 63.2 ng/mL during treatment. In addition, plasma, urine, hair, and nail arsenic levels rapidly decreased to normal 6 months after the end of treatment. CONCLUSION Arsenic combined with ATRA is effective and safe in pediatric patients with APL, although long-term follow-up is still needed.

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: KIT mutations are common in children with core-binding factor (CBF) acute myeloid leukemia (AML). The relationship between KIT mutations and their prognostic value has generated intense attention during the past years. Although studies have evaluated the role of KIT mutations, their prognostic implications remain unclear. To clarify this issue, we conducted this meta-analysis. METHODS: We electronically searched the PubMed, Embase and Cochrane Library databases. Twelve studies met our selection criteria. These studies involved 1,123 children with CBF-AML including 256 children with KIT mutations. We investigated the effects of KIT mutations on the complete remission (CR), relapse, event-free survival (EFS), disease-free survival (DFS), and overall survival (OS) rates of pediatric CBF-AML patients. RESULTS: KIT mutations were not associated with CR [relative risk: 1.01, 95% confidence interval (CI): 0.94–1.09, P=0.761], but were associated with higher relapse risk [hazard ratio (HR): 1.69, 95% CI: 1.32–2.16, P=0.000], lower OS (HR: 3.05, 95% CI: 1.23–7.60, P=0.016), lower DFS (HR: 1.65, 95% CI: 1.07–2.54, P=0.024), and lower EFS (HR: 3.08, 95% CI: 1.02–9.32, P=0.046). CONCLUSIONS: Our analysis suggested that KIT mutations had an adverse prognostic effect in pediatric CBF-AML patients. The initial diagnostic workup for these patients should include tests for the detection of KIT mutations, and the treatment may need to be adjusted when these mutations are found to be present.

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.

Summary Background Vincristine plus dexamethasone pulses are generally used throughout maintenance treatment for childhood acute lymphoblastic leukaemia. However, previous studies remain inconclusive about the benefit of this maintenance therapy and the absence of randomised, controlled trials in patients with low-risk or high-risk acute lymphoblastic leukaemia provides uncertainty. We therefore aimed to determine if this therapy could be safely omitted beyond 1 year of treatment without leading to an inferior outcome in any risk subgroup of childhood acute lymphoblastic leukaemia. Methods This open-label, multicentre, randomised, phase 3, non-inferiority trial involved 20 major medical centres across China. We enrolled patients who were aged 0–18 years with newly diagnosed acute lymphoblastic leukaemia that was subsequently in continuous remission for 1 year after initial treatment. Patients with secondary malignancy or primary immunodeficiency were excluded. Eligible patients were classified as having low-risk, intermediate-risk, or high-risk acute lymphoblastic leukaemia based on minimal residual disease and immunophenotypic and genetic features of leukaemic cells. Randomisation and analyses were done separately for the low-risk and intermediate-to-high-risk cohorts. Randomisation was generated by the study biostatistician with a block size of six. Stratification factors included participating centre, sex, and age at diagnosis; the low-risk cohort was additionally stratified for ETV6–RUNX1 status, and the intermediate-to-high-risk cohort for cell lineage. Patients in each risk cohort were randomly assigned (1:1) to either receive (ie, the control group) or not receive (ie, the experimental group) seven pulses of intravenous vincristine (1·5 mg/m2) plus oral dexamethasone (6 mg/m2 per day for 7 days) during the second year of treatment. The primary endpoint was difference in 5-year event-free survival between the experimental group and the control group for both the low-risk and intermediate-to-high-risk cohorts, with a non-inferiority margin of 0·05 (5%). The analysis was by intention to treat. This trial is registered with the Chinese Clinical Trial Registry, ChiCTR-IPR-14005706. Findings Between Jan 1, 2015, and Feb 20, 2020, 6141 paediatric patients with newly diagnosed acute lymphoblastic leukaemia were registered to this study. Approximately 1 year after diagnosis and treatment, 5054 patients in continuous remission were randomly assigned, including 2923 (1442 in the control group and 1481 in the experimental group) with low-risk acute lymphoblastic leukaemia and 2131 (1071 control, 1060 experimental) with intermediate-to-high risk acute lymphoblastic leukaemia. Median follow-up for patients who were alive at the time of analysis was 3·7 years (IQR 2·8–4·7). Among patients with low-risk acute lymphoblastic leukaemia, no difference was observed in 5-year event-free survival between the control group and the experimental group (90·3% [95% CI 88·4–92·2] vs 90·2% [88·2–92·2]; p=0·90). The one-sided 95% upper confidence bound for the difference in 5-year event-free survival probability was 0·024, establishing non-inferiority. Among patients with intermediate-to-high-risk acute lymphoblastic leukaemia, no difference was observed in 5-year event-free survival between the control group and the experimental group (82·8% [95% CI 80·0–85·7] vs 80·8% [77·7–84·0]; p=0·90), but the one-sided 95% upper confidence bound for the difference in 5-year event-free survival probability was 0·055, giving a borderline inferior result for those in the experimental group. In the low-risk cohort, we found no differences in the rates of infections, symptomatic osteonecrosis, or other complications during the second year of maintenance treatment between patients in the control and experimental groups. Patients with intermediate-to-high-risk acute lymphoblastic leukaemia in the control group were more likely to develop grade 3–4 pneumonia (26 [2·4%] of 1071 vs ten [0·9%] of 1060) and vincristine-related peripheral neuropathy (17 [1·6%] vs six [0·6%]) compared with the experimental group. Incidence of grade 5 fatal infection was similar between the control group and the experimental group in both the low-risk cohort (two [0·1%] of 1442 vs five [0·3%] of 1481) and intermediate-to-high risk cohort (six [0·6%] of 1071 vs five [0·5%] of 1060). Interpretation Vincristine plus dexamethasone pulses might be omitted beyond 1 year of treatment for children with low-risk acute lymphoblastic leukaemia. Additional studies are needed for intermediate-to-high-risk acute lymphoblastic leukaemia. Funding VIVA China Children's Cancer Foundation, the National Natural Science Foundation of China, the China fourth round of Three-Year Public Health Action Plan (2015–2017), Chinese Academy of Medical Sciences Innovation Fund for Medical Sciences, US National Cancer Institute, St Baldrick's Foundation, and the American Lebanese Syrian Associated Charities. Translation For the Chinese translation of the abstract see Supplementary Materials section.

Background In the past decade, miR‐100, miR‐146a, and miR‐210 were reported to be dysregulated in childhood acute lymphoblastic leukemia (ALL). However, effects of genetic variants in these three microRNAs have not been investigated in Chinese population. Methods In this study, we conducted a case‐control study to evaluate the relationship between genetic variants in miR‐100, miR‐146a, and miR‐210 and the risk of childhood ALL in Chinese population. Subsequently, plasma expression level of miR‐100 was also detected. Result We found that subjects carrying mutant homozygous TT genotype of miR‐100 rs543412 had a statistically significantly decreased risk of childhood ALL (adjusted odds ratio [OR] = 0.73, 95% confidence interval [CI] = 0.55‐0.97, P = 0.029). This protective effect was also observed among subjects whose parents were ever drinkers (adjusted OR = 0.53, 95% CI = 0.29‐0.94), or whose living house were ever painted (adjusted OR = 0.57, 95% CI = 0.34‐0.94). Besides, rs543412 variant homozygous TT had a significantly protective role in patients with childhood B‐ALL. Finally, we found that expression level of miR‐100 in plasma of childhood ALL cases was significantly higher than that of noncancer controls. Conclusion Our study suggested that there was significant association between the polymorphisms in miR‐100 (rs543412) and decreased susceptibility to childhood ALL.

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.

Standard chemotherapy regimens for remission induction of pediatric acute myeloid leukemia (AML) are associated with significant morbidity and mortality. We performed a cohort study to determine the impact of reducing the intensity of remission induction chemotherapy on the outcomes of selected children with AML treated with a low-dose induction regimen plus granulocyte colony stimulating factor (G-CSF) (low-dose chemotherapy (LDC)/G-CSF). Complete response (CR) after two induction courses was attained in 87.0% (40/46) of patients receiving LDC/G-CSF. Post-remission therapy was offered to all patients, and included standard consolidation and/or stem cell transplantation. During the study period, an additional 94 consecutive children with AML treated with standard chemotherapy (SDC) for induction (80/94 (85.1%) of the patients attained CR after induction II, P = 0.953) and post-remission. In this non-randomized study, there were no significant differences in 4-year event-free (67.4 vs. 70.7%; P = 0.99) and overall (70.3 vs. 74.6%, P = 0.69) survival in the LDC/G-CSF and SDC cohorts, respectively. After the first course of induction, recovery of white blood cell (WBC) and platelet counts were significantly faster in patients receiving LDC/G-CSF than in those receiving SDC (11.5 vs. 18.5 d for WBCs (P < 0.001); 15.5 vs. 22.0 d for platelets (P < 0.001)). To examine the quality of molecular response, targeted deep sequencing was performed. Of 137 mutations detected at diagnosis in 20 children who attained hematological CR after two courses of LDC/G-CSF (n = 9) or SDC (n = 11), all of the mutations were below the reference value (variant allelic frequency

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.

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

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.

Genomic alterations underlying chemotherapy resistance remains poorly characterized in pediatric acute myeloid leukemia (AML). In this study, we used whole exome sequencing to identify gene mutations associated with chemo-resistance in 44 pediatric AML patients. We identified previously unreported mutations involving epigenetic regulators such as KDM5C, SRIT6, CHD4, and PRPF6 in pediatric AML patients. Despite low prevalence in general pediatric AML, mutations involving epigenetic regulators including splicing factors, were collectively enriched as a group in primary chemo-resistance AML patients. In addition, clonal evolution analysis of secondary chemo-resistance AML patients reveals dominant clone at diagnosis could survive several course of intensified chemotherapy. And gain of new mutations in genes such as MVP, TCF3, SS18, and BCL10, may contribute to chemo-resistance at relapse. These results provide novel insights into the genetic basis of treatment failure in pediatric AML.

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.

Cases of pediatric acute myeloid leukemia (AML) with complex karyotypes including chromosome 5 abnormalities are rare and have a dismal prognosis. Management of AML with monosomy 5/del(5q) has not been uniform. We treated three adolescents with this AML subtype with combined low-dose cytarabine and mitoxantrone, concurrent with decitabine and G-CSF, for remission induction. Decitabine was also included in the conditioning regimen before hematopoietic cell transplantation (HCT). All three patients attained complete remission after treatment with this combination. The treatment was well tolerated, and the patients are alive and free of disease at 3.6, 3.2, and 3.0 years after HCT, respectively. Our experience suggests that HCT is required for the eradication of pediatric AML, and possibly MDS, with complex karyotypes including del(5q). Decitabine combined with regimens of low myelotoxicity for remission induction represents an alternative approach to decrease the risk of complications associated with post-remission chemotherapy before HCT. 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.

This study aimed to investigate clinical characteristics and prognostic significance of activation-induced cytidine deaminase (AID) gene, miR-181b and miR-155 expression in de novo adult B-cell acute lymphoblastic leukemia (B-ALL) patients. Results showed that AID and miR-155 expression were higher in B-ALL patients than healthy controls, while miR-181b expression was lower in B-ALL patients. In addition, Ph+ B-ALLs had higher AID expression than Ph- B-ALLs, and its high expression was associated with BCR-ABL. Moreover, B-ALL patients with AIDhigh or miR-181blow expression had a shorter overall survival (OS). AIDhigh with miR-181blow, AIDhigh with miR-155low, miR-181blow, miR-155low, AIDhigh with miR-181blow and miR-155low expression were associated with shorter OS. Combination of the three molecules are more accurate predictors for unfavorable OS compared with univariate group. Therefore, AID, miR-181b and miR-155 provide clinical prognosis of adult de novo B-ALL patients and may refine their molecular risk classification.

Background Children with hematological malignancies are at high risk of infection. Various kinds of pathogens may cause infection in these patients. The effect of traditional methods on these patients is not ideal. Methods This was a case series study. The cases of five patients with clinical symptoms of pulmonary infection. Next-generation sequencing (NGS) was used to identify pathogens in these 5 patients. Results Uncommon pathogens were detected in five patients. Case information are shown in Table 1. Conclusion NGS may serve as a promising tool for rapid and accurate etiological diagnosis, which could greatly improve the diagnosis of uncommon infection in children with hematologic malignancies.

A survey of the clinical data on acute myeloid leukemia (AML) over the past 10 years in the treatment center of Children's Hospital was presented. The aim of the study was to identify the factors influencing the treatment abandonment rate (AR) of AML. Of the 474 AML cases examined, 264 were abandoned (55.7%). The most important factor affecting AR appeared to be the AML subtype-that is, the M3 versus non-M3 (42% vs. 60%). Patient age was observed to be closely related to AR-the older the patients, the lower the AR-and infants had the highest prevalence of abandonment (84.2%). The patient's residential location was markedly correlated to AR, which was almost inversely proportional to the size of the township where the patient came from. From large cities, intermediate and small towns to countryside villages, the AR increased linearly. So was the correlation with health insurance coverage, which decreased in the same way. Sex and karyotypes did not affect AR. In conclusion, the patients' financial burden and the perceived incurability of AML were the 2 leading factors dominating the decision for abandonment in parents and caregivers.

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.

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.

The role and potential efficacy of antithymocyte globulin (ATG) in patients receiving cord blood transplantation (CBT) remain controversial. We retrospectively evaluated the effect of ATG on patient outcomes in 207 children with high-risk or advanced hematological malignancies at 8 child blood disease centers in China. The cumulative incidence of platelet recovery on day 100 was significantly lower in the ATG cohort compared with the non-ATG cohort (77.3% versus 89.8%) (P = .046). There was no significant difference in the incidence of grade II to IV acute and chronic graft-versus-host disease (GVHD), and transplantation-related mortality (TRM) between the 2 groups (P = .76, P = .57, and P = .46, respectively). The incidence of CMV infection was significantly higher among the ATG group compared with that among the non-ATG group (P = .003). The 5-year cumulative incidence of relapse was significantly higher in the ATG cohort (30.7% versus 15.4%) (P = .009). Overall survival in the non-ATG group was slightly higher than that of the ATG cohort (64.1% versus 52.1%, P = .093) and leukemia-free survival in the non-ATG cohort was significantly higher than in the ATG cohort (56.6% versus 37.7%, P = .015). Our study demonstrated that, for high-risk or advanced childhood hematological malignancies receiving unrelated CBT, patients who received conditioning that omitted ATG had a faster platelet recovery, a comparable GVHD and TRM, a significantly lower relapse risk, and an improved long-term survival compared with those patients who received ATG in the conditioning.

In this study, we have analyzed both administrative and clinical data from our hospital during 2002 to 2012 to evaluate the influence of government medical policies on reducing abandonment treatment in pediatric patients with acute lymphoblastic leukemia. Two policies funding for the catastrophic diseases and the new rural cooperative medical care system (NRCMS) were initiated in 2005 and 2011, respectively. About 1151 children diagnosed with acute lymphoblastic leukemia were enrolled in our study during this period and 316 cases abandoned treatment. Statistical differences in sex, age, number of children in the family, and family financial status were observed. Of most importance, the medical insurance coverage was critical for reducing abandonment treatment. However, 92 cases abandoning treatment after relapse did not show significant difference either in medical insurance coverage or in duration from first complete remission. In conclusion, financial crisis was the main reason for abandoning treatment. Government-funded health care expenditure programs reduced families’ economic burden and thereby reduced the abandonment rate with resultant increased overall survival.

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.

Mixed phenotype acute leukemia (MPAL) is a rare type of acute leukemia with a poor clinical outcome which lacks specific therapy. To evaluate the therapeutic efficiency of CCLG-2008 protocol used for acute lymphoblastic leukemia (ALL) in China on MPAL children who were initially diagnosed as ALL by morphology, we reviewed patients’ database diagnosed as ALL and MPAL according to WHO classification and compared their outcomes from July 2008 to June 2012. Total newly enrolled ALL in this study were 309 cases by morphology, in which ten cases were identified as MPAL mainly by immunophenotyping: B+ myeloid (3/10), T+ myeloid (2/10), B + T (4/10), trilineage (1/10). Two cases were classified as intermediate risk (IR) and 8 cases were high risk (HR) according to the CCLG-2008 criteria. Only one case of IR survived and others died due to primary resistance of chemotherapy and relapse. Compared with MPAL, ALL children in IR and HR had a longer survival (28.1 vs 9.5 months, p

Yixin Hu, Hailong He, Jun Lu, Yi Wang, Peifang Xiao, Jianqin Li, Jie Li, Yina Sun, Hui Lv, Junjie Fan, Yanhua Yao, Yihuan Chai, Shaoyan Hu Department of Hematology and Oncology, The Children’s Hospital of Soochow University, Suzhou, People’s Republic of China Objective: The objective of this study was to observe the prognosis of pediatric patients with E2A-PBX1-positive acute lymphoblastic leukemia (ALL) from the treatment with the CCLG-ALL2008 protocol.Design and methods: Three hundred and forty-nine Chinese pediatric patients with pre-B-cell ALL were enrolled in this study from December 2008 to September 2013. Of these, 20 patients with E2A-PBX1 expression and 223 without the gene expression were stratified into two cohorts. Clinical and biological characteristics and 5-year event-free survival (EFS), relapse-free survival (RFS), and overall survival (OS) were analyzed and compared between these two groups. Results: The E2A-PBX1 fusion transcript was detected in 20 of 349 (5.7%) patients. Compared with the gene-negative subgroup, patients with E2A-PBX1 were younger in age but did not show significant differences in white blood cell (WBC) count or gender distribution at primary diagnosis. Moreover, there were more inferior karyotypes detected in the E2A-PBX1 subgroup (P=0.035). With the CCLG-ALL2008 treatment protocol, patients with E2A-PBX1 showed a favorable treatment response with lower minimal residual disease (MRD) levels (

Pediatric acute myeloid leukemia (pAML) is a heterogeneous disease. The clinical outcome of pAML has improved significantly over the past four decades with current long-term survival rates of ~70%. This improvement is due to intensification of chemotherapeutic regimens, better risk-group stratifications, better salvage at relapse, and improved supportive care. Nevertheless, novel therapies are still needed as the cure rates for some subtypes of pAML remain unacceptably low. In addition, the profound marrow suppression caused by near-myeloablative induction therapy may lead to life-threatening complications, such as severe infections, which not only prolong the hospitalization but also cause significant morbidity and mortality during or after treatment. Moreover, intensive chemotherapy usually affects the patient's quality of life and they can experience low physical, emotional, or social function. To determine the impact of reducing the intensity of induction chemotherapy on the outcome of pAML, we recently performed a study using G-CSF priming plus low-dose chemotherapy (GLDC) to treat pAML, compared with standard chemotherapy (SDC) during induction. Our study showed that complete remission (CR), 4-year event free survival (EFS), overall survival (OS), and cumulative incidence of relapse (CIR) rates of 46 pAML patients, initially given a GLDC for the first induction remission, were comparable to those of 94 children admitted to the same hospital and given SDC. However, GLDC showed a much lower toxicity than SDC. After the first course of induction, the recovery of white blood cell (WBC) and platelet counts were significantly faster in patients receiving GLDC than SDC. Grade III or IV infectious complications occurred in 4 (8.7%) patients receiving GLDC and 23 (24.4%) patients receiving SDC, and 2 patients receiving SDC died of complications (Hu Y. et al, 2019). Even though the clinical efficacy of GLDC has been seen in multiple clinical trials, the detailed mechanisms remain unclear. Some clinical and pre-clinical studies showed that G-CSF could push AML cells into cell-cycle, accelerate WBC and platelet recovery even when used after induction chemotherapy, and reduce the viability of AML cells when co-cultured with BM stroma, but not cultured alone. However, all of these studies were not established with LDC. To determine the potential mechanism(s) of GLDC in pAML, we established Mll-Af9 transplanted chimeric mice to develop AML, and we assessed the clearance of leukemic cells and the impact on normal cells by GLDC or SDC. Based on previous studies, we used combined cytarabine (100mg/kg) and doxorubicin (3mg/kg) (DA) in mice as SDC, half dose of SDC as LDC, and G-CSF (300ug/kg) plus half dose of SDC as GLDC in our study design. The G-CSF priming times were inconsistent in previous studies. To establish the best priming effect, especially for the stem cells, we first analyzed the cell cycle stimulation by G-CSF to the SLAM hematopoietic stem cells (SLAM-HSCs) and the more quiescent stem-like HSC population (endothelial protein C receptor expressing, EPCR+ HSCs) in WT mice. We found that G-CSF can stimulate SLAM-HSCs and EPCR+ HSCs into cell-cycle as early as 12hrs and 24hrs post G-CSF injection, so we used G-CSF one day priming before the chemotherapy estimating that even the deeper quiescent stem cells have been stimulated into the cell-cycle at that time point. We then arranged the Mll-Af9 transplanted mice with similar disease burden into 5 groups to receive different treatments for 6 days: LDC, GLDC, SDC, and also the G-CSF or the PBS groups as control (G-CSF was given on D1-D6, DA was given on D2-D6). We found that GLDC and SDC had similar clearance to the leukemic cells (CD45.2+), which were better than LDC, as observed 2 days after the treatment. However, the recovery of normal cells (CD45.1+) was significantly faster in the GLDC group compared with LDC and SDC groups. We also found that G-CSF could simulate the differentiation of both leukemic cells and normal cells, shown by the increase of the CD11b+Ly6G+ population of both CD45.2+ and CD45.1+ cells in the G-CSF group compared to the PBS group. Studies to further elucidate the additional mechanisms of GLDC are still ongoing. In conclusion, our clinical and mouse modeling studies consistently suggest that GLDC promotes leukemia cells clearance and normal hematopoietic regeneration simultaneously, which may be a better regimen for pAML. Disclosures No relevant conflicts of interest to declare.

OBJECTIVE To determine whether dasatinib given at 80 mg/m2 is more effective than imatinib at 300 mg/m2 to 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 III randomized study was conducted at 20 hospitals in China. Enrollment began in January 2015 and randomization was stopped in October 2018 when the early stopping criterion of the trial was met. Patients aged between 0 and 18 years were recruited. Of the 225 patients with the diagnosis, 35 declined and 1 died before treatment. 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 by intent-to-treat. The secondary outcomes were relapse, toxic death, and overall survival. RESULTS With a median follow-up of 26.1 months (IQR 16.3-34.1), the 4-year event-free survival rate was 71.0% (95% CI 56.2-89.6) in the dasatinib group and 48.9% (95% CI 32.0-74.5, p=0.005) in the imatinib group (hazard ratio 2.36, 95% CI 1.27-4.40, p=0.007). 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=0.01), while 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=0.06). There were no significant differences in the frequency of severe toxicities between the two treatment groups. CONCLUSION AND RELEVANCE Intensive chemotherapy including dasatinib at 80 mg/m2 per day yielded superior results in the treatment of Philadelphia chromosome-positive ALL compared to imatinib at 300 mg/m2 per day and provided excellent control of central-nervous-system leukemia without the use of prophylactic cranial irradiation. Disclosures No relevant conflicts of interest to declare.

Introduction: The efficacy of extended duration of vincristine (VCR) and dexamethasone (DEX) pulses in the treatment of childhood acute lymphoblastic leukemia (ALL) is uncertain in the context of contemporary chemotherapy. By contrast, the long-term sequelae of vincristine-induced peripheral neuropathy and dexamethasone-related metabolic syndrome, osteonecrosis, and neurocognitive impairment are well recognized. We therefore conducted a randomized study in the CCCG-ALL-2015 protocol participated by 20 hospitals in China to compare the event-free survival (EFS) and overall survival (OS) between children with newly diagnosed ALL who did or did not receive extended duration of VCR+DEX pulses during maintenance treatment. Methods: After remission induction and consolidation treatment with high-dose methotrexate and mercaptopurine, all patients received antimetabolite-based maintenance treatment. During the initial 20-week of maintenance treatment, low-risk (LR) patients received two reinduction cycles and three pulses of VCR+DEX pulses, while intermediate-/high-risk (I/HR) patients received daily mercaptopurine interrupted every three weeks with PEG-asparaginase, mercaptopurine, daunorubicin, and VCR+DEX pulses for 5 courses followed by a reinduction treatment. During the subsequent maintenance treatment, all patients received VCR+DEX pulses every 4 weeks for 5 cycles. All Philadelphia chromosome (Ph)-negative patients were then stratified and randomized during the fifth cycle of maintenance course (between weeks 51 and 53) to or not to receive the VCR+DEX pulse every 8 weeks for 7 cycles between weeks 54 and 109; the remaining maintenance treatment between weeks 110 and 125 consisted of only mercaptopurine and methotrexate. Results: Between January 2015 and December 2018, 3985 eligible Ph-negative patients, including 2318 (58.2%) LR patients and 1667 (41.8%) I/HR patients, were enrolled in the study. With a median follow-up of 2.53 years (IQR 1.82-3.26), the 4-year event-free survival (EFS) and overall survival (OS) rates were 91.6% (95% CI 89.4-93.9) and 98.8% (95% CI 98.2-99.4) in the LR patients, and 85.9% (95% CI 83.2-88.7) and 95.4% (95% CI 93.8-96.9) in the I/HR patients, respectively. The 4-year OS were 99.0% (95%CI, 98.3%-99.8%) in the 1145 LR patients randomized to receive VCR+DEX pulse (LR-A) and 98.6% (95% CI, 97.7%-99.5%) in the 1173 LR patients not to receive the pulse (LR-B, hazard ratio 1.5, 95% CI 0.6-4.0; p=0.374, Fig 1A). The 4-year EFS were 91.1% (95% CI, 87.4%-95.1%) in LR-A group and 92.0% (95% CI, 89.6%-94.5%) in LR-B group (hazard ratio 1.3, 95% CI 0.8-1.9; P=0.27; Figure 1B). There were no significant differences between LR-A and LR-B group among patients with or without the t (12;21) (ETV6-RUNX1) in univariate analysis (Table1). Likewise, there was no significant difference in the 4-year OS between the 834 I/HR patients who did (I/HR-A) and the 833 I/HR patients who did not (I/HR-B) receive the pulse: 94.3% (95% CI, 91.7%-97.0%) versus 96.3% (95%CI 94.6%-98.0%, hazard ratio 0.8, 95% CI 0.4-1.4; P=0.421) (Fig 1C). The 4-year EFS were 83.6% (95%CI 79.2%-88.3%) for I/HR-A group and 88.1% (95%CI 85.1%-91.2%, P=0.372) for I/HR-B group (hazard ratio 0.9, 95% CI 0.6-1.2; P=0.37) (Figure 1D). There were no significant differences between I/HR-A and I/HR-B group among patients with B-ALL, T-ALL or t (1;19) (TCF3-PBX1) in the univariate analysis (Table1). Conclusion: The additional pulses of VCR+DEX pulse beyond one year of maintenance treatment had no impact on 4-year EFS or OS among LR or I/HR patients. If this finding remains unchanged with additional follow-up, the VCR+DEX pulses can be omitted after one year of maintenance therapy in childhood ALL. Disclosures No relevant conflicts of interest to declare.

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.

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.

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: It is difficult for pediatric refractory and relapse acute myeloid leukemia (RR-AML) and MDS-RAEB/RAEBT patients to achieve complete remission (CR) and these patients develop recurrence and die of either disease progression or associated complications. The CAG regimen (cytarabine, aclarubicin and G-CSF) has been widely used in treating patients with MDS-EB and AML-MRC in Asia. Likely, Short term CAG derived regimens called low dose induction therapy, MAG regimen (Mitoxantrone for 3 doses, cytarabine and G-CSF for 10 days) also showed efficacy in De Novo AML. However, MAG regimen showed less efficacy in RR-AML and MDS-5(5q-). Purpose: To evaluate the clinical efficacy and safety of low-dose decitabine in combination with low-dose MAG regimen (D-MAG regimen) in the treatment of RR-AML and MDS-RAEB/RAEBT. Method A total of 17 patients with MDS-RAEB/RAEBT and RR-AML((2 cases of MDS-RAEB, 3 cases of MDS-RAEBT, 10 cases for refractory AML, and 2 cases for relapse AML) from June 2017 to April 2018 in our center were included in the retrospective study. All the patients were treated with decitabine of 20 mg/m2 for 5 days and followed by 10 days of MAG regimen (cytarabine of 10mg/m2 q12h for 10 days, mitoxantrone of 5 mg/ m2.d for 3 days, and G-CSF of 5μg/kg.d for 10 days),called D-CAG regimen. After two cycles of induction chemotherapy, the patients who obtained CR received consolidation chemotherapy or hematopoietic stem cell transplantation (HSCT). Results Among a total of 17 patients, the median age was the median age was 102 months (32-200 months) and 64.71 % of them were male. Characteristic features of these patients were illustrated in Table 1. Only 2 cases died of severe lung infection due to continuous agranulocytosis who had been received high dose induction therapy (Daunorubicin of 50mg/M2.d for 3 days, cytarabine of 100mg/m2 q12h for 10 days, and Etoposide of 150mg/m2.d for 5 days) for 2 cycles with poor physical condition before D-MAG. In the other 15 cases, 10 of them had complete remission (CR) after the first course of treatment, 4 cases were partial remission (PR), 1 case with a high blast cells at 25% indicated a poor response to D-MAG, and the effective rate was 93.3%. Among 4 children with PR, one case reached CR after the second courses of treatment. The most common adverse reactions in all children were hematological toxicity, grade III-IV. Liver damage was found in 2 cases, grade I and grade II respectively. There were 3 cases of oral side reactions, 1 case in grade I and 2 cases in grade II. The gastrointestinal reactions in all children were grade I - II. By July 2018, the median follow-up was 11 months (7-16months). Among 15 patients after D-MAG, 11 patients received HSCT. The twelve-month survival rate was 88.24% and the median leukemia-free survival (LFS) was 11 months. Conclusion The low-dose decitabine in combination with Low-dose MAG regimen improved CR rate for pediatric patients with MDS-RAEB and RR- AML, and is a promising treatment for pediatric patients with MDS/RR-AML. Disclosures No relevant conflicts of interest to declare.

Insulin-like growth factor binding proteins (IGFBPs) are secretory factors that play essential roles in regulation of insulin-like growth factors (IGFs) in tissue as well as in modulating IGF binding to its receptors. IGFBP7, known as IGFBP-related protein 1 (IGFBP-rP1), mac25/angiomodulin, function as a potential tumor suppressor in various human solid cancers, including breast, prostate, gastric and liver cancer. We have reported the overexpression of IGFBP7 in the context of acute myeloid leukemia (AML), showing that IGFBP7 expression level in AML patients is significantly increased compared with controls (P In order to study the role of IGFBP7 in AML, stable cell lines expressing IGFBP7 and control in AML cells were constructed using lentiviral packaging system. Expression microarray assay was carried out to analyze the global gene level changes driven by IGFBP7. MTT and transwell assays were performed to evaluate the effect of IGFBP7 on cell proliferation and migration. Bioinformatics results found that IGFBP7 appeared to utilize multiple cellular processes for its oncogenic roles, including adhesion, migration, and proliferation. Experimental data showed overexpression of IGFBP7 in K562 cells resulted in a 2-3 fold increase in migration in contrast to control cells. Moreover, enforced expression of IGFBP7 also led to phosphorylation of Akt and Erk, whose activities inactivation by pharmacologically inhibitors resulted in the loss of ability to migrating. Finally, knockdown of IGFBP7 in cells with high IGFBP7 level, their migration abilities were significantly decreased. To assess the role of IGFBP7 in leukemogenesis in vivo, the same numbers of K562/IGFBP7 and K562-Vector cells, U937-shIGFBP7 and U937-shNEG cells were injected into NOD-SCID mice by tail vein injection, respectively. About two weeks later, it was showed that mice of K562/IGFBP7 and U937 groups displayed higher white blood cell counts compared with mice of K562-Vector and U937-shIGFBP7 groups, respectively. Mice of K562/IGFBP7 and U937 groups had more severe splenomegaly and hepatomagaly compared with its corresponding control groups. We further characterized the molecular mechanism underlying leukemogenesis driven by IGFBP7 in AML cell lines. The global expression profiling and molecular biological experiments showed PI3K/AKT signaling was activated by overexpression of IGFBP7, and knockdown of IGFBP7 in AML cells led to a decrease of PI3K/AKT activity in PTEN-dependent manner. IGFBP7 promotes proliferation and migration of AML cells, the promotion could be suppressed by both RNA interference and pharmacological inhibition of PI3K/AKT pathway. Immuno-precipitation assay showed that IGFBP7 associated with AXAN2 and induced PTEN degradation. The expression of ANXA2 was significantly positive correlated with the expression ANXA2 in AML patients. The expression of IGFBP7 in AML, overexpression as well as knockdown of IGFBP7 in leukemia cells and in mice model, all suggest that IGFBP7 is a potential proto-oncogene. Collectively this work suggests that targeting IGFBP7 activity may be an effective therapeutic strategy for AML. 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.

This multicenter retrospective study included 184 children with malignant and non-malignant diseases who underwent UCBT between January 1998 and August 2012. The malignant disease group included 101 children with ALL, AML, CML, JMML, and MDS, and the non-malignant disease group included 83 children with PID, β-thalassemia, IMD BMF, and HLH. The median duration to neutrophil and platelet engraftment was 16 and 35 days in the malignant disease group vs 15 and 38 days in the non-malignant disease group. The cumulative incidence of grade II-IV aGVHD and cGVHD was 25.6% and 13.5% in the malignant disease group vs 19.7% and 11.1% in the non-malignant disease group, respectively. The median duration and cumulative incidence of neutrophil and platelet engraftment, and the cumulative incidence of grade II-IV aGVHD and cGVHD were similar between the two groups. Of the 184 pediatric patients, 114 patients survived during a median follow-up period of 14 months (range 4-138). The 5-year OS and DFS were not statistically different between the two groups (56.3% and 46.1% in malignant disease group vs 68.5% and 52.8% in non-malignant disease group). The above results indicate that UCB is a viable source for HSCT for children with malignant or non-malignant diseases, especially in urgent cases.

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.

The t(12;21)(p13;q22) ETV6‐RUNX1 gene fusion is one of the most common chromosomal translocation in childhood acute lymphoblastic leukemia (ALL). It is associated with favorable prognosis. The identification of the genomic sequence of the breakpoint flanking regions of the ETV6‐RUNX1 translocation should be the best strategy to monitor minimal residual disease (MRD) in patients with ETV6‐RUNX1‐positive ALL. In this study, the ETV6‐RUNX1 translocation was sequenced by next‐generation sequencing (NGS) in 26 patients with ETV6‐RUNX1‐positive ALL and re‐sequenced by using the Sanger method. Interestingly, the three‐way translocation, including ETV6‐RUNX1, was detected in five patients. Four of them relapsed during or after therapy, while 21 patients without the three‐way translocation were still in remission (P