MLL-Rearranged Leukemia Is Dependent on Aberrant H3K79 Methylation by DOT1L

SummaryThe histone 3 lysine 79 (H3K79) methyltransferase Dot1l has been implicated in the development of leukemias bearing translocations of the Mixed Lineage Leukemia (MLL) gene. We identified the MLL-fusion targets in an MLL-AF9 leukemia model, and conducted epigenetic profiling for H3K79me2, H3K4me3, H3K27me3, and H3K36me3 in hematopoietic progenitor and leukemia stem cells (LSCs). We found abnormal profiles only for H3K79me2 on MLL-AF9 fusion target loci in LSCs. Inactivation of Dot1l led to downregulation of direct MLL-AF9 targets and an MLL translocation-associated gene expression signature, whereas global gene expression remained largely unaffected. Suppression of MLL translocation-a…

Tumor Lipids of Pediatric Papillary Renal Cell Carcinoma Stimulate Unconventional T Cells

Papillary renal cell carcinoma (PRCC) is a rare entity in children with no established therapy protocols for advanced diseases. Immunotherapy is emerging as an important therapeutic tool for childhood cancer. Tumor cells can be recognized and killed by conventional and unconventional T cells. Unconventional T cells are able to recognize lipid antigens presented via CD1 molecules independently from major histocompatibility complex, which offers new alternatives for cancer immunotherapies. The nature of those lipids is largely unknown and α-galactosylceramide is currently used as a synthetic model antigen. In this work, we analyzed infiltrating lymphocytes of two pediatric PRCCs using flow cy…

Clofarabine Significantly Increases Eradication of Minimal Residual Disease of B-Precursor ALL Compared to High-Dose Cytarabine in Randomized Trial Coall 08-09

Background Since the FDA approval of clofarabine for the treatment of relapsed or refractory acute lymphoblastic leukemia (ALL) at childhood, several studies have been launched which put clofarabine under scrutiny in combination with other cytostatic drugs as second or third line therapy. As a novel treatment-strategy we introduced the combination of clofarabine with pegylated asparaginase (PEG-ASP) in a randomized fashion in comparison to the standard consolidation course with high dose cytarabine (Hidac) combined with PEG-ASP into the frontline management of ALL within the CoALL 08-09 protocol. The primary objective of the study was to compare the MRD based assessment of the cytotoxic eff…

Multivariate analysis on complications of central venous access devices in children with cancer and severe disease influenced by catheter tip position and vessel insertion site (A STROBE-compliant study)

Abstract Context Reliable long-term central venous access device (CVAD) is essential for the management of pediatric patients with cancer or chronic diseases. However, there is no general consensus for optimal catheter tip location and vessel insertion site in children. Objective This single center study analyzes the risk of complications associated with long-term upper body CVAD and evaluates them with respect to catheter tip location as well as vessel insertion site. Design Pediatric patients who received long-term upper body CVAD from January 2008 through April 2017 and underwent radiographic documentation of the tip location were retrospectively included in the study. Data on demographi…

Radiation-induced vascular changes in the intracranial irradiation field in medulloblastoma survivors: An MRI study

While survival times after treatment of medulloblastoma are increasing, little is known about radiochemotherapy (RCT)-induced cerebrovascular changes. High resolution vessel wall imaging (VWI) sequences are an emerging tool for the evaluation of cerebrovascular diseases. We performed VWI in medulloblastoma long-term survivors to screen for late sequelae of RCT.Twenty-two pediatric medulloblastoma survivors (mean age 25.8 years (10-53 years); 16.3 years (mean) post primary RCT (range 1-45 years)) underwent 2D VWI-MRI. Vessel wall thickening, contrast enhancement and luminal narrowing were analyzed. The findings were correlated with the patients' radiation protocols.Vessel wall changes were o…

Susceptibility-weighted magnetic resonance imaging of cerebrovascular sequelae after radiotherapy for pediatric brain tumors

Due to sensitive neuroimaging techniques, cerebrovascular complications such as cerebral microbleeds (CMB) and cerebral cavernous malformations (CCM) are increasingly recognized as considerable late effects after treatment for pediatric brain tumor. The aim of this study was to analyze CMB in a cohort of patients after cranial irradiation therapy for medulloblastoma or other pediatric brain tumors using susceptibility-weighted magnetic resonance imaging (SWI).Forty former pediatric brain tumor patients were enrolled in this prospective cross-sectional study and examined by cranial MRI including SWI sequences. Cerebral microbleeds, clinical symptoms and disability were evaluated.Thirty-six (…

Identification of an Immunogenic Medulloblastoma-Specific Fusion Involving EPC2 and GULP1

Medulloblastoma is the most common malignant brain tumor in children. Immunotherapy is yet to demonstrate dramatic results in medulloblastoma, one reason being the low rate of mutations creating new antigens in this entity. In tumors with low mutational burden, gene fusions may represent a source of tumor-specific neoantigens. Here, we reviewed the landscape of fusions in medulloblastoma and analyzed their predicted immunogenicity. Furthermore, we described a new in-frame fusion protein identified by RNA-Seq. The fusion involved two genes on chromosome 2 coding for the enhancer of polycomb homolog 2 (EPC2) and GULP PTB domain containing engulfment adaptor 1 (GULP1) respectively. By qRT-PCR …

16P How to translate what we learned from Gaucher’s disease into new treatments for brain tumours

Human toll-like receptor 4 mutations are associated with susceptibility to invasive meningococcal disease in infancy.

Toll-like receptor 4 (TLR4) is required for efficient recognition of bacterial infections. We investigated an association between 2 TLR4 mutations (Asp 299 Gly and Thr 399 Ile) and meningococcal disease in 197 patients and 214 healthy controls by allele-specific real time polymerase chain reaction and direct sequencing. Although the allele frequency was not higher in the overall patient population, a significantly higher frequency in the 40 patients younger than 12 months of age (P = 0.007) was observed. We conclude that TLR4 mutations represent a risk factor for meningococcal disease in this age group.

Age-Dependent Association of Human Mannose-Binding Lectin Mutations With Susceptibility to Invasive Meningococcal Disease in Childhood

Mannose-binding lectin (MBL) is an important factor of the innate immune system, and MBL-initiated complement activation is an important early defense mechanism against various bacterial infections, including invasive meningococcal disease.In a pediatric cohort (ages 2-215 months) with invasive meningococcal disease, we investigated the overall and age-stratified frequency of 3 MBL exon 1 variations (C154T, G161A, G170A), previously shown to result in markedly decreased MBL plasma concentrations, by allele specific fluorescent hybridization probe real-time PCR assays and direct sequencing. Healthy age-matched volunteers with the same ethnic background and no history of meningococcal disease…

Demonstration of a Role for Dot1l In MLL-Rearranged Leukemia Using a Conditional Loss of Function Model

Abstract Abstract 62 Leukemias associated with translocations of the Mixed Lineage Leukemia (MLL) gene account for a significant percentage of both AML and ALL, and often carry a poor prognosis. The exact molecular mechanisms by which MLL-fusion proteins transform cells are incompletely understood. One proposed model involves the aberrant activation of transcriptional programs through epigenetic changes that ultimately lead to leukemogenesis. The histone 3 lysine 79 (H3K79) methyltransferase Dot1l has been shown to be recruited by the most common MLL fusion proteins, and MLL fusion protein target loci are associated with H3K79 methylation (H3K79me2/3) in mouse models and MLL-rearranged huma…

Exploiting Gangliosides for the Therapy of Ewing’s Sarcoma and H3K27M-Mutant Diffuse Midline Glioma

Simple Summary Osteosarcoma, Ewing’s sarcoma, and H3K27M-mutant diffuse midline glioma are rare but aggressive malignancies occurring mainly in children. Due to their rareness and often fatal course, drug development is challenging. Here, we repurposed the existing drugs dinutuximab and eliglustat and investigated their potential to directly target or indirectly modulate the tumor cell-specific ganglioside GD2. Our data suggest that targeting and/or modulating tumor cell-specific GD2 may offer a new therapeutic strategy for the above mentioned tumor entities. Abstract The ganglioside GD2 is an important target in childhood cancer. Nevertheless, the only therapy targeting GD2 that is approve…

16P Molecular analysis for precision oncology of children: Beyond genomics

A New Algorithm and Panel Construction for Pediatric Leukemia Immunophenotyping Using 10-Color Flow Cytometry

Abstract Abstract 4799 Background: Rapid identification and quantification of abnormal cell populations in minimal specimen are crucial for diagnosis and longitudinal minimal residual disease (MRD) testing of childhood leukemia. So far, most standard immunophenotypic analyses are performed using antibody panels with up to five-colors and require high cell numbers. For infant and pediatric specimen, high-level multicolor analyses is highly desirable to gather sufficient data for initial diagnostic and follow up monitoring of pathologic populations. Objective: In this study, we aimed to establish a newly defined pediatric multicolor flow cytometric panel algorithm with high reliability yet mi…

Hemophagocytic Lymphohistiocytosis in Early Infancy- Pitfall of Differentiation between Hereditary and Infectious Reasons

Abstract Hemophagocytic Lymphohistiocytosis (HLH) is characterized by pathologic immune activation which occurs either as a familial disorder or as an acquired condition. The diagnosis of HLH requires the presence of five out of nine criteria: fever, splenomegaly, pancytopenia, hypertriglyceridemia, hypofibrinogenemia, hemophagocytosis in bone marrow, hyperferritinemia, low or absent natural killer cell activity and high level of soluble interleukin-2 receptor. Here we present a 6-month-old girl with parents from Southern Italy. She suffered from hepatosplenomegaly and a recurrent high fever for 3 months' duration. On admission, she showed neurological symptoms including irritability and ne…