High DOCK1 expression identifies a distinct prognostic subgroup of pediatric acute myeloid leukemia: Results of the Japanese Pediatric Leukemia/Lymphoma Study Group AML-05 trial.

BACKGROUND: The molecular pathogenesis of acute myeloid leukemia (AML) was dramatically clarified over the latest two decades. Several important molecular markers were discovered in patients with AML that have helped to improve the risk stratification. However, developing new treatment strategies for relapsed/refractory acute myeloid leukemia (AML) is crucial due to its poor prognosis. PROCEDURE: To overcome this difficulty, we performed an assay for transposase-accessible chromatin with sequencing (ATAC-seq) in 10 AML patients with various gene alterations. ATAC-seq is based on direct in vitro sequencing adaptor transposition into native chromatin, and is a rapid and sensitive method for integrative epigenomic analysis. ATAC-seq analysis revealed increased accessibility of the DOCK1 gene in patients with AML harboring poor prognostic factors. Following the ATAC-seq results, quantitative reverse transcription polymerase chain reaction was used to measure DOCK1 gene expression levels in 369 pediatric patients with de novo AML. RESULTS: High DOCK1 expression was detected in 132 (37%) patients. The overall survival (OS) and event-free survival (EFS) among patients with high DOCK1 expression were significantly worse than those patients with low DOCK1 expression (3-year EFS: 34% vs. 60%, p < .001 and 3-year OS: 60% vs. 80%, p < .001). To investigate the significance of high DOCK1 gene expression, we transduced DOCK1 into MOLM14 cells, and revealed that cytarabine in combination with DOCK1 inhibitor reduced the viability of these leukemic cells. CONCLUSIONS: Our results indicate that a DOCK1 inhibitor might reinforce the effects of cytarabine and other anti-cancer agents in patients with AML with high DOCK1 expression.

High IL2RA/CD25 expression is a prognostic stem cell biomarker for pediatric acute myeloid leukemia without a core-binding factor.

CD25 is an aberrant marker expressed on the leukemic stem cell (LSC) surface and an immunotherapy target in acute myeloid leukemia (AML). However, the clinical prevalence and significance of CD25 expression in pediatric AML are unknown. High IL2RA/CD25 expression in pediatric AML showed a stem cell-like phenotype, and elevated CD25 expression was associated with lower overall survival (p < .001) and event-free survival (p < .001) in the Japanese Pediatric Leukemia/Lymphoma Study Group AML-05 study. This finding was reproduced in AML without a core-binding factor in the Children's Oncology Group study cohort. High CD25 expression has prognostic significance in pediatric AML.

Severe RAS-Associated Lymphoproliferative Disease Case with Increasing αß Double-Negative T Cells with Atypical Features.

Autoimmune lymphoproliferative syndrome (ALPS) is a disease of lymphocyte homeostasis caused by FAS-mediated apoptotic pathway dysfunction and is characterized by non-malignant lymphoproliferation with an increased number of TCRαß+CD4-CD8- double-negative T cells (αßDNTs). Conversely, RAS-associated leukoproliferative disease (RALD), which is caused by gain-of-functional somatic variants in KRAS or NRAS, is considered a group of diseases with a similar course. Herein, we present a 7-year-old Japanese female of RALD harboring NRAS variant that aggressively progressed to juvenile myelomonocytic leukemia (JMML) with increased αßDNTs. She eventually underwent hematopoietic cell transplantation due to acute respiratory distress which was caused by pulmonary infiltration of JMML blasts. In general, αßDNTs have been remarkably increased in ALPS; however, FAS pathway gene abnormalities were not observed in this case. This case with RALD had repeated shock/pre-shock episodes as the condition progressed. This shock was thought to be caused by the presence of a high number of αßDNTs. The αßDNTs observed in this case revealed high CCR4, CCR6, and CD45RO expressions, which were similar to Th17. These increased Th17-like αßDNTs have triggered the inflammation, resulting in the pathogenesis of shock, because Th17 secretes pro-inflammatory cytokines such as interleukin (IL)-17A and granulocyte-macrophage colony-stimulating factor. The presence of IL-17A-secreting αßDNTs has been reported in systemic lupus erythematosus (SLE) and Sjögren's syndrome. The present case is complicated with SLE, suggesting the involvement of Th17-like αßDNTs in the disease pathogenesis. Examining the characteristics of αßDNTs in RALD, JMML, and ALPS may reveal the pathologies in these cases.

Low NUDT15 expression levels due to biallelic NUDT15 variants and 6-mercaptopurine intolerance.

6-Mercaptopurine (6-MP) is widely used for the treatment of paediatric leukaemia and lymphoma. Recently, germline variants in the NUDT15 gene have been identified as one of the major genetic causes for 6-MP-associated adverse effects such as myelosuppression. Patients with hypomorphic NUDT15 variants accumulate excessive levels of DNA-incorporated thioguanine in white blood cells, resulting in severe myelosuppression. Although preclinical studies suggest that these variants may influence the protein stability of NUDT15, this has not been directly characterised in patients. In this study, we report the development of a series of novel monoclonal antibodies against NUDT15, using which we quantitatively assessed NUDT15 protein levels in 37 patients with acute lymphoblastic leukaemia treated with 6-MP, using sandwich enzyme-linked immunosorbent assay (ELISA). The NUDT15 genotype was highly correlated with its protein levels (p < 0.0001), with homozygous and compound heterozygous patients showing exceedingly low NUDT15 expression. There was a positive correlation between NUDT15 protein level and 6-MP tolerance (r = 0.631, p < 0.0001). In conclusion, our results point to low NUDT15 protein abundance as the biochemical basis for NUDT15-mediated 6-MP intolerance, thus providing a phenotypic readout of inherited NUDT15 deficiency.

A phase III clinical trial evaluating efficacy and safety of minimal residual disease-based risk stratification for children with acute myeloid leukemia, incorporating a randomized study of gemtuzumab ozogamicin in combination with post-induction chemotherapy for non-low-risk patients (JPLSG-AML-20).

The purpose of this study is to establish a treatment with appropriate intensity for children (<16 years old at diagnosis) with de novo acute myeloid leukemia (excluding acute promyelocytic leukemia and myeloid leukemia associated with Down syndrome) according to a risk stratification based on recurrent leukemic cytogenetic abnormalities and flow-cytometric minimal residual disease at end of initial induction chemotherapy and to validate the safety and efficacy of gemtuzumab ozogamicin (GO)-combined post-induction chemotherapy for the non-low-risk (non-LR) patients. The primary endpoint of this phase III study is three-year disease-free survival rate, which will be compared between the GO and non-GO arms of the non-LR (intermediate-risk and high-risk [HR]) patients. All HR patients will be allocated to allogeneic hematopoietic stem cell transplantation in first remission. This trial has been registered at the Japan Registry of Clinical Trials (jRCTs041210015).

Droplet digital polymerase chain reaction assay for the detection of the minor clone of KIT D816V in paediatric acute myeloid leukaemia especially showing RUNX1-RUNX1T1 transcripts.

KIT D816V mutation within exon 17 has been particularly reported as one of the poor prognostic factors in pediatric acute myeloid leukemia (AML) with RUNX1-RUNX1T1. The exact frequency and the prognostic impact of KIT D816V minor clones at diagnosis were not examined. In this study, the minor clones were examined and the prognostic significance of KIT D816V mutation in pediatric patients was investigated. Consequently, 24 KIT D816V mutations (7.2%) in 335 pediatric patients were identified, and 12 of 24 were only detected via the digital droplet polymerase chain reaction method. All 12 patients were confined in core binding factor (CBF)-AML patients. The 5 year event-free survival of the patients with KIT D816V mutation was significantly inferior to those without KIT D816V mutation (44.1% [95% confidence interval (CI), 16.0%-69.4%] vs. 74.7% [95% CI, 63.0%-83.2%] P-value = 0.02, respectively). The 5 year overall survival was not different between the two groups (92.9% [95% CI, 59.0%-NA vs. 89.7% [95% CI, 69.6%-96.8%] P-value = 0.607, respectively). In this study, KIT D816V minor clones in patients with CBF-AML were confirmed and KIT D816V was considered as a risk factor for relapse in patients with RUNX1-RUNX1T1-positive AML.

Allogeneic Bone Marrow Transplantation versus Peripheral Blood Stem Cell Transplantation for Hematologic Malignancies in Children: A Systematic Review and Meta-Analysis.

Peripheral blood stem cell transplantation (PBSCT) is being increasingly performed as an alternative to bone marrow transplantation (BMT); however, PBSCT has not been proven to have equivalent outcome to BMT. We conducted a meta-analysis to compare survival rates and treatment-related complications between PBSCT and BMT for pediatric hematologic malignancies. We searched Medline, Embase plus Embase classics, and the Cochrane Central Register of Controlled Trials for the terms "hematopoietic stem cell transplantation" AND "allogeneic transplantation" AND "children", including randomized controlled studies and cohort studies without language limitations. We identified 7 of 5368 studies for inclusion in our meta-analysis. The cohorts of these studies included a total of 4328 patients, 3185 who underwent BMT and 1143 who underwent PBSCT. Five-year overall survival was similar in the 2 groups (PBSCT, 56.2%; BMT, 63.5%; relative risk [RR], 1.17; 95% confidence interval [CI], .91 to 1.52), as was the 5-year event-free survival (PBSCT, 49.9%; BMT, 57.2%; RR, 1.14; 95% CI, .93 to 1.39). The incidences of nonrelapse mortality and chronic graft-versus-host disease were higher in the PBSCT group compared with the BMT group (RR, 1.73; 95% CI, 1.50 to 1.99 versus RR, 1.55; 95% CI, 1.18 to 2.03). This meta-analysis found insufficient evidence to conclude that peripheral blood stem cells are equivalent to bone marrow. The results indicate that bone marrow can still be a preferred donor source for pediatric hematologic malignancies.

Relationship between Sedative Antihistamines and the Duration of Febrile Seizures.

Some studies have shown that sedative antihistamines prolong febrile seizure duration. Although the collective evidence is still mixed, the Japanese Society of Child Neurology released guidelines in 2015 that contraindicated the use of sedative antihistamines in patients with febrile seizure. Focused on addressing limitations of previous studies, we conducted a cross-sectional study to evaluate the relationship between febrile seizure duration and the use of sedative antihistamines. Data were collected from patients who visited St. Luke's International Hospital due to febrile seizure between August 2013 and February 2016. Patients were divided into groups based on their prescribed medications: sedative antihistamine, nonsedative antihistamine, and no antihistamine. Seizure duration was the primary outcome and was examined using multivariate analyses. Of the 426 patients included, sedative antihistamines were administered to 24 patients. The median seizure duration was approximately 3 minutes in all three groups. There was no statistical difference in the bivariate (p = 0.422) or multivariate analyses (p = 0.544). Our results do not support the relationship between sedative antihistamine use and prolonged duration of febrile seizure. These results suggest that the use of antihistamines may be considered for patients with past history of febrile seizure, when appropriate.

Acute promyelocytic leukemia with a cryptic insertion of RARA into TBL1XR1.

Acute promyelocytic leukemia (APL) is cytogenetically characterized by the t(15;17) (q24;q21), although cases without this translocation exist. These cases are referred to as "cryptic" or "masked" translocations. Additionally, fewer than 5% of APL cases have another partner gene fused to the RARA gene. The TBL1XR1-RARA fusion gene has recently been reported as a novel RARA-associated fusion gene. We report a case with TBL1XR1-RARA and a masked translocation that was not detected by conventional tests for RARA-associated translocations. Three-year-old girl was diagnosed with APL based morphological findings, although conventional tests for RARA-associated chimeric genes were negative. She received all-trans retinoic acid treatment, but that was not effective. She achieved a complete remission (CR) by conventional multidrug chemotherapy, but had extramedullary relapse 2 years after onset. She underwent cord blood transplantation (CBT) in her second CR and is currently alive. To investigate the underlying pathogenesis of this unique case, we performed whole-genome sequencing and found a cryptic insertion of RARA gene into the TBL1XR1 gene. The transcript of the chimeric gene, TBL1XR1-RARA, was confirmed as an in-frame fusion by RT-PCR. In conclusion, we found using next-generation sequencing (NGS) a TBL1XR1-RARA fusion in a child with variant APL without the classic karyotype. Cryptic insertion could also occur in cases other than APL with PML-RARA. Variant APL has many variants and NGS analysis should therefore be considered for APL variant cases, even for those without RARA translocation detected by conventional analysis.

Whole transcriptome sequencing reveals a KMT2A-USP2 fusion in infant acute myeloid leukemia.

Infant acute lymphoblastic leukemia with lysine (K)-specific methyltransferase 2A (KMT2A) rearrangements usually has a poor prognosis regardless of the fusion partners of KMT2A. However, the prognosis of pediatric acute myeloid leukemia (AML) with KMT2A rearrangements depends on its translocation partners. We herein report the case of a 9-month-old boy with a KMT2A-USP2 fusion, which required diagnosis by whole transcriptome sequencing after the failure of detection of known translocation partners by conventional screening approaches. As this first report of a patient with AML with a KMT2A-USP2 fusion illustrates, identification of the partners in all patients with KMT2A-rearranged AML is critical to elucidate the outcomes associated with specific rearrangements and to develop appropriate treatment strategies. Moreover, development of additional methods to detect specific translocation partners of KMT2A and leukemia-specific targeting drugs is important to improve further the outcomes of KMT2A-rearranged AML.

Effectiveness of acyclovir prophylaxis against varicella zoster virus disease after allogeneic hematopoietic cell transplantation: A systematic review and meta-analysis.

BACKGROUND: Varicella zoster virus (VZV) disease is a common complication after hematopoietic cell transplantation (HCT). The mortality rate for disseminated VZV infection is 34%. Acyclovir has been used for the prophylaxis of VZV disease after HCT, but the effectiveness of prophylaxis is controversial. We conducted a meta-analysis of the incidence of VZV disease within the first 1 year after acyclovir prophylaxis had been discontinued and assessed the risk of VZV disease during acyclovir prophylaxis. METHODS: Medline, EMBASE plus EMBASE classics, and the Cochrane Central Register of Controlled Trials were used for a systematic search. The inclusion criteria were both randomized controlled trials and cohort studies that described the effectiveness of acyclovir as prophylaxis against VZV disease after allogeneic HCT. RESULTS: We included seven studies involving a total of 2265 patients. No mortality by VZV was identified. Acyclovir prophylaxis significantly reduced the rate of VZV infection within the first 1 year after discontinuation (risk ratio: 0.38, 95% confidence interval (CI): 0.29-0.51). The risk of VZV disease during acyclovir prophylaxis was also reduced (risk ratio: 0.17, 95% CI: 0.12-0.24). Both short-term and long-term prophylaxis reduced the incidence of VZV infection (RR: 0.51, 95% CI: 0.30-0.86 vs RR: 0.34, 95% CI: 0.22-0.54). Low-dose acyclovir (<400 mg/d) is sufficient to reduce the risk of VZV disease. CONCLUSION: This study showed that acyclovir prophylaxis reduced VZV infection after HCT with no fatal cases and acyclovir prophylaxis is beneficial. No significant adverse effects occurred and no delayed VZV disease was identified.

Intraventricular Rituximab in Pediatric CD20-positive Refractory Primary Central Nervous System Lymphoma.

Primary central nervous system lymphoma (PCNSL) is a rare and aggressive type of extranodal non-Hodgkin lymphoma that carries an unsatisfactory prognosis. Treating refractory PCNSL is challenging because of resistance to conventional cytotoxic and intrathecal chemotherapies. Therefore, novel therapeutic approaches are needed. Here, we report a 12-year-old boy with CD20-positive PCNSL, which was refractory to combination chemotherapy and intravenous rituximab. However, the patient achieved complete remission after repeated intraventricular rituximab administration. The results of this case indicate that intraventricular rituximab is an effective option to treat refractory PCNSL in children.

Preoperative diagnosis of clear cell sarcoma of the kidney by detection of BCOR internal tandem duplication in circulating tumor DNA.

Clear cell sarcoma of the kidney (CCSK) is the second most common renal malignancy in children. The prognosis is poorer in CCSK than in Wilms' tumor, and multimodal treatment including surgery, intensive chemotherapy, and radiation is required to improve the outcome for children with CCSK. Histological evaluation is required for the diagnosis. However, biopsies of tumors to obtain diagnostic specimens are not routinely performed because of the risk of spreading tumor cells during the procedure. Recently, internal tandem duplication (ITD) of BCOR has been recognized as a genetic hallmark of CCSK. We herein established a novel BCOR-ITD-specific polymerase chain reaction method with well-designed primers, and then performed a liquid biopsy for cell-free DNA (cfDNA) obtained from plasma of three children with nonmetastatic renal tumors (stage II) and from one control. BCOR-ITD was positively detected in the cfDNA of two cases, both of which were later diagnosed as CCSK based on histological feature of the resected tumor specimen, while it was not detected for a normal control and a patient diagnosed with Wilms' tumor. Our study is the first one of preoperative circulating tumor DNA assay in pediatric renal tumors. The liquid biopsy method enables less invasive, preoperative diagnosis of CCSK with no risk of tumor spillage, which can avoid iatrogenic upstaging.

A Cryptic NUP214-ABL1 Fusion in B-cell Precursor Acute Lymphoblastic Leukemia.

Fluorescent in situ hybridization (FISH) analysis is the standard methods for screening ABL1 fusions, which is recurrently translocated in pediatric acute lymphoblastic leukemia (ALL), and potentially targetable by kinase inhibitors. Here we demonstrated a case of B-cell precursor ALL with NUP214-ABL1 fusion, which break-apart FISH assay for ABL1 failed to detect. The cryptic fusion was generated by small duplication from ABL1 to NUP214, which was detected by copy number analysis using genomic microarray and confirmed by PCR. In the context of precision medicine, we should establish how to screen targetable abnormalities for minimizing risk of false-negative.

Risk factors for psychological and psychosomatic symptoms among children with malignancies.

AIM: With increasing survival rates in paediatric malignancies, the quality-of-life of children during hospitalisation should be given more attention. We aimed to identify factors associated with psychological and psychosomatic symptoms (PPS) that required medication among children hospitalised for treatment of malignancies. METHODS: We retrospectively analysed data of 190 patients aged 2-18 years old. They were diagnosed with malignant diseases and admitted for treatment at St. Luke's International Hospital between 2003 and 2013. Patients were considered as having PPS if they were prescribed psychotropic agents during hospitalisation. RESULTS: Of the 190 patients, 56 (30%) were prescribed psychotropic agents for PPS. Types of PPS included insomnia in 21 (38%), anxiety in 11 (20%), and others conditions (psychogenetic nausea, agitation, delirium, depression). The most prescribed psychotropic agents were etizolam for 34 cases (61%), followed by diazepam and risperidone. The multivariable analyses confirmed statistically significant independent associations for haematopoietic stem cell transplantation (HSCT) (odds ratio (OR), 5.21; 95% confidence interval (CI), 1.77-15.35), older age (12-18 years vs. 2-5 years, OR, 3.74; 95% CI, 1.04-10.00), and opioid use (OR, 7.15; 95% CI, 2.36-21.69). CONCLUSIONS: Older age at admission, undergoing HSCT, and those given opioids were found to be risk factors for PPS among children with malignancies. Appropriate preventive measures against PPS may be warranted for patients with these risk factors.

Influence of ADORA2A gene polymorphism on leukoencephalopathy risk in MTX-treated pediatric patients affected by hematological malignancies.

BACKGROUND: Methotrexate (MTX) can lead to neurotoxicity and asymptomatic leukoencephalopathy. However, the mechanism of MTX-related leukoencephalopathy is obscure. MTX and its metabolites inhibit 5-aminoimidazole-4-carboxamide ribonucleotide formiltransferase (ATIC) and promote adenosine release. Recently, it has been reported that adenosine and its receptor are related to certain central nervous system diseases. We investigated whether adenosine pathway gene polymorphisms and clinical factors were related to MTX-related leukoencephalopathy in pediatric patients affected by hematological malignancies. PROCEDURE: Fifty-six Japanese childhood acute lymphoblastic leukemia or lymphoma patients were investigated. Patients were evaluated by magnetic resonance imaging of the brain before maintenance therapy or stem cell transplantation. Gene polymorphisms within the adenosine pathway (ATIC, adenosine A2A receptor [ADORA2A]) and the MTX pathway (methylenetetrahydrofolate reductase [MTHFR] and ABCB1) were genotyped using TaqMan assays. Clinical data were collected by accessing the medical records. MTX-related leukoencephalopathy was evaluated by a pediatric neurologist. RESULTS: Twenty-one (37%) of 56 patients developed MTX-related leukoencephalopathy. Four of 21 patients developed clinical neurotoxicity. The minor allele CC genotype of rs2298383 (ADORA2A) was associated with MTX-related leukoencephalopathy (P = 0.010, odds ratio = 5.81, 95% confidence interval 1.50-22.50). High cumulative dose of systemic MTX was associated with MTX-related leukoencephalopathy after adjusting for sex, ADORA2A polymorphism, and prolonged high MTX concentration (P = 0.042, odds ratio = 1.18, 95% confidence interval 1.01-1.37). CONCLUSIONS: ADORA2A rs2298383 and high cumulative dose of systemic MTX administration were significantly associated with MTX-related leukoencephalopathy. Our results indicate that pharmacological intervention within the adenosine pathway may be both a treatment and preventative option for MTX-related leukoencephalopathy.

A Case of Myxoid Pleomorphic Liposarcoma with Rhabdoid Cells: A Diagnostic Pitfall.

Myxoid pleomorphic liposarcoma (MPLS) is an extremely rare tumor listed in the fifth edition of the WHO classification (2020). Histologically, it mainly comprises a mixture of myxoid and pleomorphic liposarcoma-like components. Genetically, it lacks FUS/EWSR1::DDIT3 fusion and MDM2 amplification. Herein, we describe an example of MPLS with rhabdoid cells in a 10-year-old girl who presented with a growing mass in the right inguinal region. The specimen from the wide excision measured 68 mm × 55 mm × 43 mm, and a circumscribed and lobulated mass was observed in the subcutaneous tissue. Histologically, oval-to-short, spindle-shaped, proliferating tumor cells with moderate nuclear atypia and mesh-like capillaries against a myxoid background were noted. Adipocytes were observed focally, while rhabdoid cells were observed multifocally. Immunohistochemically, the tumor showed inconsistent reactivity for desmin but was negative for MYOD1, myogenin, MDM2, and CDK4. Fluorescence in situ hybridization revealed no DDIT3 rearrangement. Despite adjuvant chemotherapy, the tumor metastasized to the thoracic cavity 24 months after excision. The metastatic lesions contained abundant lipoblasts rather than rhabdoid cells, and we concluded this tumor was a MPLS. The presence of rhabdoid cells could be a diagnostic pitfall, and recognizing such a variation in histology would help improve diagnostic accuracy.