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Cytomegalovirus (CMV) infection remains an important cause of morbidity and mortality post cord blood transplantation (CBT). It has been suggested that the graft-versus-host disease (GVHD) and immunosuppressants have an impact on CMV infection. This study evaluated the incidence, outcomes, and risk factors of CMV infection, while focusing on GVHD and the use of immunosuppressants, in 103 children who had received CBT. Among the patients, 92.2% were positive for CMV serology, while CMV antigenemia was observed in 68.9% and CMV disease developed in 26.2%. CMV enterocolitis was the most common, followed by retinitis and pneumonia. Patients with positive CMV serology and grade II to IV GVHD were independently associated with CMV antigenemia. Recurrent CMV antigenemia was observed significantly more frequently in patients with extensive chronic GVHD. Patients with CMV disease showed significantly worse overall survival, relapse-free survival, and non-relapse mortality than those without CMV disease. In conclusion, CMV infection is common post-CBT in countries with a high rate of CMV seropositivity in the general population and is related to worse outcomes. GVHD severity is associated with the development and recurrence of CMV infection. Thus, efforts need to be made to prevent CMV infection in children post-CBT. [ABSTRACT FROM AUTHOR]

Purpose: We aimed to report our single-center experience of allogeneic hematopoietic cell transplantation (HCT), which has been the only curative option for certain patients with lethal primary immunodeficiencies (PIDs).Methods: We summarized the results of HCT performed for patients with PIDs for 11 consecutive years from 2006 to 2016 at Samsung Medical Center, Seoul, Korea. Twenty-six patients with PIDs received HCT. Most had chronic granulomatous disease (42.3%), Wiskott Aldrich syndrome (15.4%), or severe combined immunodeficiency (11.5%).Results: Nine patients (34.6%) received HCT during the former half period and 17 patients (65.4%) during the latter half period. Donor types were categorized as: matched sibling donor (n = 5), unrelated donor (n = 17), and familial mismatched donor (FMMD) (n = 4). Unrelated HCT and FMMD transplantation were increasingly performed in the latter half period compared to the first (5 vs. 16, P = 0.034). Five patients experienced initial engraftment failure, but all of them were eventually engrafted after additional HCTs. The 3-year probability of overall survival was 72.0%. Seven patients (26.9%) died, and the causes of death were bacterial sepsis (n = 4), pneumonia (n = 1), chronic graft-versus-host disease (GVHD) (n = 1), and diffuse alveolar hemorrhage (n = 1). Two patients with bacterial sepsis and a patient with pneumonia also had chronic GVHD. Unrelated HCT and use of methotrexate were associated with poor outcome. Complete chimerism was attained in 85.0% at 1 year after HCT.Conclusion: PID candidates have been increasingly identified for allogeneic HCT in Korea, and the majority of them could be cured by HCT. Establishment of a systematic registry of PID patients for HCT is needed. [ABSTRACT FROM AUTHOR]

Juvenile myelomonocytic leukemia (JMML) is a life-threatening myeloproliferative neoplasm. The chemotherapeutic effect on survival remains unclear, and feasible standardized response criteria are yet to be established. We aimed to evaluate the chemotherapeutic response and its effect on survival in patients with JMML. A retrospective registry was reviewed for children diagnosed with JMML between 2000 and 2019. Response was assessed according to the criteria proposed by the International JMML Symposium in 2007 (criteria I) and the updated version in 2013 with its modifications (criteria II). A total of 73 patients were included in this study. Complete response (CR) rates were 46.6% and 28.8% using the criteria I and criteria II, respectively. A platelet count ≥ 40 × 109/L at diagnosis was associated with higher CR rates using the criteria II. Patients with criteria I-based CR had a better overall survival (OS) than those without CR (81.1% vs. 49.1% at 5 years). Patients with criteria II-based CR showed better OS (85.7% vs. 55.5% at 5 years) and event-free survival (EFS) (71.1% vs. 44.7% at 5 years) than those without CR. Additionally, a trend toward better EFS was observed in patients with criteria II-based CR than in those with criteria I-based CR but without criteria II-based CR (71.1% vs. 53.8% at 5 years). Chemotherapeutic response is associated with better survival outcomes. Along with splenomegaly, the addition of platelet count recovery, existence of extramedullary leukemic infiltration, and more stringent leukocyte counts to the response criteria allows for a more sensitive prediction of survival outcomes. • Standardized response criteria are yet to be established in treatment of JMML. • Complete response was assessed by the two criteria (criteria I and II). • A platelet count ≥40×109/L at diagnosis was associated with higher CR rates. • Patients with criteria II-based CR showed better OS and EFS than those without. • More stringent response criteria might be helpful in predicting survival outcomes. [ABSTRACT FROM AUTHOR]

We reviewed the medical records of five patients with T-B+NK- severe combined immunodeficiency (SCID) who received minimal dose allogeneic hematopoietic cell transplantation (HCT) (total nucleated cell count (TNC) lower than 1.0 × 108/kg). Patients were administered a median of 5.0 mL of bone marrow or peripheral blood without conditioning (in four) or with anti-thymocyte globulin alone (in one). Three patients received HCT from a matched sibling donor, one from unrelated donor, and one from familial mismatched donor. The median TNC and CD34+ cells were 0.54 (0.29–0.84) × 108/kg and 0.61 (0.35–0.84) × 106/kg, respectively. Engraftment was achieved in all. Total T cell, CD4+ cell, and CD8+ cell recovery was obtained within a year in four, and immunoglobulin replacement was discontinued in all. All patients survived, exhibiting stable donor chimerism. We obtained sufficient therapeutic effects with minimal dose transplantation without intensive conditioning in patients with T-B+NK- SCID. • Patients with SCID were administered a median of 5.0 mL of BM or PB grafts. • The median TNC and CD34+ cells were 0.54 × 108/kg and 0.61 × 106/kg, respectively. • Except for one patient, T cell recovery was obtained within a year. • IVIg replacement was discontinued in all patients at a median of 4 months. • All survived without disease recurrence, exhibiting stable donor chimerism. [ABSTRACT FROM AUTHOR]

We retrospectively analyzed infectious complications during tandem high-dose chemotherapy and autologous stem cell transplantation (HDCT/auto-SCT) in children and adolescents with high-risk or recurrent solid tumors. A total of 324 patients underwent their first HDCT/auto-SCT between October 2004 and September 2014, and 283 of them proceeded to their second HDCT/auto-SCT (a total of 607 HDCT/auto-SCTs). During the early transplant period of 607 HDCT/auto-SCTs (from the beginning of HDCT to day 30 post-transplant), bacteremia, urinary tract infection (UTI), respiratory virus infection, and varicella zoster virus (VZV) reactivation occurred in 7.1%, 2.3%, 13.0%, and 2.5% of HDCT/auto-SCTs, respectively. The early transplant period of the second HDCT/auto-SCT had infectious complications similar to the first HDCT/auto-SCT. During the late transplant period of HDCT/auto-SCT (from day 31 to 1 year post-transplant), bacteremia, UTI, and VZV reactivation occurred in 7.5%, 2.5%, and 3.9% of patients, respectively. Most infectious complications in the late transplant period occurred during the first 6 months post-transplant. There were no invasive fungal infections during the study period. Six patients died from infectious complications (4 from bacterial sepsis and 2 from respiratory virus infection). Our study suggests that infectious complications are similar following second and first HDCT/auto-SCT in children. [ABSTRACT FROM AUTHOR]

The original version of this article unfortunately contained a mistake in the 7th author’s given name. The correct version is presented above. [ABSTRACT FROM AUTHOR]

Monosomal karyotype (MK) is known as a far end of the unfavorable cytogenetics in adult acute myeloid leukemia (AML), while available data in childhood AML is scarce. In this study, we investigated the prevalence and prognostic value of MK with retrospectively analyzed 119 patients newly diagnosed with childhood de novo AML. Ten patients (8.4%) revealed to have MK. All MK-positive (MK(+)) AML were associated with complex cytogenetic abnormalities and belonged to the cytogenetic adverse-risk group. Nine of MK(+) patients (90%) achieved complete remission. The event-free survival (EFS) and overall survival (OS) of MK(+) adverse group were comparable to the ESF and OS of MK-negative non-adverse group (EFS 60.0 ± 15.5% vs 59.0 ± 5.1%, P = 0.925; OS 70.0 ± 14.5% vs 58.1 ± 5.3%, P = 0.696). In multivariate analysis, MK was not an independent adverse prognostic factor for EFS (hazard ratio 0.45, 95% C.I. 0.13–1.50, P = 0.194). In addition, 7 of 9 MK(+) patients who received allogeneic hematopoietic stem cell transplantation (HSCT) survived event-free, with a median follow-up of 64 months. In conclusion, MK did not act as an adverse prognostic factor in childhood de novo AML. Allogeneic HSCT might have contributed to the excellent outcome of MK(+) childhood de novo AML. [ABSTRACT FROM AUTHOR]

Background: Large inter-individual variations in drug metabolism pose a challenge in determining 6-mercaptopurine (6MP) doses. As the last product of 6MP metabolism, DNA-thioguanine nucleotide (DNA-TGN) could reflect the efficacy of 6MP, especially in patients harboring variants in the 6MP metabolism pathway. The aim of this study was to investigate the clinical significance of DNA-TGN monitoring in Korean pediatric acute lymphoblastic leukemia (ALL) patients, focusing on the NUDT15 genotype. Methods: The subjects of this study were patients who underwent ALL treatment with 6MP. Tests for the NUDT15 and TPMT genotypes were performed, and prospective DNA-TGN and erythrocyte TGN samples were collected after two weeks or more of 6MP treatment. DNA-TGN was quantified using the liquid chromatography-tandem mass spectrometry method. Results: A total of 471 DNA-TGN measurements in 71 patients were analyzed, which ranged from 1.0 to 903.1 fmol thioguanine/μg DNA. The 6MP intensity demonstrated a significant relationship with DNA-TGN concentration (P<0.001). Patients harboring NUDT15 variants were treated with a lower dose of 6MP (P<0.001); however, there was no significant difference in DNA-TGN concentration when compared to patients carrying wild-type NUDT15 (P = 0.261). These patients also presented higher variation in DNA-TGN levels (P = 0.002) and DNA-TGN/6MP intensity (P = 0.019) compared to patients carrying wild-type NUDT15. DNA-TGN concentration did not show a significant correlation with WBC count (P = 0.093). Conclusions: Patients harboring NUDT15 variants demonstrated similar DNA-TGN concentrations even at low doses of 6MP and showed high variability in DNA-TGN. Particularly in patients with NUDT15 variants who need a reduced 6MP dose, DNA-TGN could be applied as a useful marker to monitor the therapeutic effect of 6MP. [ABSTRACT FROM AUTHOR]

Aims: We aimed to investigate the impact of various genetic polymorphisms affecting thiopurine metabolism pathways and toxicity in paediatric acute lymphoblastic leukaemia patients for the first time in Korea. Methods: From May 2006 to September 2016, 139 paediatric acute lymphoblastic leukaemia patients treated with combination chemotherapy including 6‐mercaptopurine were included in the study. One hundred and twenty‐three variants in 43 genes, including TMPT and NUDT15, were screened using targeted genotyping, such as a MassARRAY system, direct sequencing and polymerase chain reaction‐restriction fragment length polymorphism methods. Among the polymorphisms screened, 103 polymorphisms of 43 genes were included for further analyses. Results: The genetic polymorphisms in the ABCC4, AHCY, ATIC, FAM8A6P, GART, GNG2, GSTA1, MTHFD1, MTHFR, NUDT15, PACSIN2, TYMS and XDH genes, and an intronic polymorphism between HIVEP2 and AIG1, and TPMT genotype were associated with thiopurine metabolism (P < 0.05). Genetic polymorphisms in the ABCC4, ADK, ATIC, GART, GMPS, GSTP1, IMPDH1, ITPA, KCNMA1, MOCOS, MTRR, NUDT15, SLC19A1, SLC28A3, SLC29A1, SLCO1B1, TYMP and XDH genes were associated with thiopurine‐related toxicities; neutropenia, hepatotoxicity and treatment interruption (P < 0.05). Conclusions: Findings of this study may provide basic knowledge for personalized medicine for thiopurinxe treatment in paediatric acute lymphoblastic leukaemia patients. [ABSTRACT FROM AUTHOR]

Aim: The Lao-Korea National Children's Hospital initiated and developed a pediatric cancer treatment program for the first time in September 2012, through education by the Lee Jong-Wook project, establishment of infrastructure by the Korea International Cooperation Agency, and cooperation of medical staff. Material and Methods: we describe the experience of initiating and building this program by retrospectively reviewing the data from pediatric patients with cancer diagnosed at the Lao-Korea National Children's Hospital between September 2012 and December 2016. Results: A total of 78 patients diagnosed with acute lymphoblastic leukemia (ALL) (n = 44), acute myeloid leukemia (AML) (n = 12), chronic myeloid leukemia (n = 7), lymphoma (n = 6), retinoblastoma (n = 5), Wilms tumor (n = 3), and germ cell tumor (n = 1) were included. Of the 44 patients with ALL, 40 received induction chemotherapy, and 4 refused chemotherapy. Of these 40 patients, 29 (73.6%) achieved complete remission (CR) and 9 (22.5%) died during chemotherapy. Of the 29 patients with CR, 4 completed the chemotherapy, 19 were still on chemotherapy, 4 relapsed, and 2 were deceased. Treatment was unsuccessful for all 12 patients with AML. Conclusion: We successfully initiated the pediatric cancer care program but faced challenges associated with high mortality because of insufficient resources. We should continue our efforts to find more abandoned patients, detect cancer earlier, and reduce the overall associated mortality. [ABSTRACT FROM AUTHOR]

Abstract: In this study, we evaluated the results of multimodal treatment that included tandem HDCT/auto‐SCT in children with anaplastic ependymomas. Fourteen patients with anaplastic ependymomas were enrolled from 2006 to 2014. Six cycles of induction chemotherapy were administered to all patients before they underwent tandem HDCT/auto‐SCT. Patients who were older than 3 years of age were administered RT after two cycles of induction chemotherapy. In patients under 3 years of age, RT was either omitted or delayed until they reached 3 years of age, if the patients experienced CR after tandem HDCT/auto‐SCT. All patients, including two who experienced disease progression during induction treatment, underwent the first HDCT/auto‐SCT, and 13 subsequently underwent the second HDCT/auto‐SCT. One patient died from hepatic VOD during the second HDCT/auto‐SCT; other toxicities occurring during tandem HDCT/auto‐SCT were manageable. Relapses or progression occurred in seven patients, and five of seven of them remain alive till date after salvage treatment, including surgery and RT. The 5‐year overall and event‐free survival rates were 85.1% ± 9.7% and 50.0% ± 13.4%, respectively. These findings suggest that multimodal treatment including tandem HDCT/auto‐SCT could be a feasible option for improving survival in children with anaplastic ependymomas. [ABSTRACT FROM AUTHOR]

• We investigated MTX-PG levels using LC–MS/MS with TPMT , NUDT15 , and MTHFR genotypes. • MTX-PG3 was the predominant form among five MTX-PGs. • MTX-PG3 level was higher in patients with TPMT *1/*3C than in patients with wild type. • MTX-PG3% was higher in NUDT15 intermediate metabolizers than the other metabolizers. • MTX-PG5% was lower in NUDT15 intermediate metabolizers than the other metabolizers. We developed and validated a quantification method for methotrexate (MTX) polyglutamates (MTX-PGs, MTX-PG1 to MTX-PG5) by liquid chromatography-tandem mass spectrometry using stable isotope-labeled internal standards and applied to 196 clinical samples collected from pediatric acute lymphoblastic leukemia patients treated with MTX. MTX-PGs levels and their proportions (%) in sum of all MTX-PGs (MTXSum) were evaluated in relation to TPMT , NUDT15 , and MTHFR genotypes. For the developed method, linearity ranges 1−500 nmol/L, bias for accuracy 0.3–13.5 %, coefficient of variation for within- and between-run imprecision of 3.2−9.5% and 1.5−12.0%, respectively. Recoveries achieved were 74.2–105.8 %. There was no significant carryover. The median level of the MTXSum for 196 clinical samples was 129.4 nmol/L (interquartile range 28.1−241.2). MTX dose and MTX-PGs were associated (P < 0.05) and among five MTX-PGs, MTX-PG3 was the predominant form (median 41.7 %). The MTX-PG3 level was significantly higher in patients with TPMT *1/*3C than in patients with wild type and MTX-PG3% was significantly higher and MTX-PG5% was significantly lower in NUDT15 intermediate metabolizers than normal or indeterminate phenotypes (P < 0.05). This validated MTX-PGs quantification method can facilitate a better understanding of MTX metabolism and therapeutic drug monitoring for MTX treatment. [ABSTRACT FROM AUTHOR]

The role of unrelated donor HSCT for children with de novo AML in CR1 is controversial. We performed this study to investigate the feasibility of unrelated donor HSCT who initially had intermediate‐ or high‐risk cytogenetics. We retrospectively reviewed medical records of patients with AML who received unrelated HSCT in CR1 at Samsung Medical Center between November 2001 and January 2012. Patients were allocated based on karyotype at diagnosis as follows: (a) low‐risk: inv(16), t(16;16), t(8;21), and t(15;17); (b) high‐risk: ‐5, 5q‐, ‐7, 3q abnormalities, t(8;16), t(6;9), t(6;11), t(6;21), t(10;11), complex karyotype (≥3 abnormalities), and acute megakaryocytic leukemia without t(1;22); and (c) IR: all the other karyotypes including normal. Patients in intermediate‐ or high‐risk group who were transplanted with either unrelated CB or matched unrelated BM/mobilized PB in their CR1 were included in this study. The projected OS and EFS rates were 74.9% and 71.1%, respectively, with a median follow‐up of 87.3 months after transplantation. The EFS was 70.1%, 80.7%, and 73.9% for CB, BM, and mobilized PB groups, respectively (P = 0.89), and 73.9% and 70.6% for IR and high‐risk groups (P = 0.76). The leading cause of death was relapse (n = 8), and only one patient died from non‐relapse cause. Unrelated donor HSCT seems a feasible approach for children with intermediate‐ or high‐risk AML in CR1. Relapse remains the leading cause of treatment failure among these patients. [ABSTRACT FROM AUTHOR]