The cytosine analog 5-aza-2-deoxycytidine has been used clinically to reactivate genes silenced by DNA methylation. In particular, patients with ␤-thalassemia show fetal globin expression after administration of this hypomethylating drug. In addition, silencing of tumor suppressor gene expression by aberrant DNA methylation in tumor cells may potentially be reversed by a similar regimen. Consistent with its function in maintaining tumor suppressor gene expression, 5-aza-2-deoxycytidine significantly reduces intestinal tumor multiplicity in the predisposed Min mouse strain. Despite its utility as an anti-cancer agent, the drug is highly mutagenic by an unknown mechanism. To gain insight into how 5-aza-2-deoxycytidine induces mutations in vivo, we examined the mutational spectrum in an Escherichia coli lac I transgene in colonic DNA from 5-aza-2-deoxycytidinetreated mice. Mutations induced by 5-aza-2-deoxycytidine were predominantly at CpG dinucleotides, which implicates DNA methyltransferase in the mutagenic mechanism. C:G3G:C transversions were the predominant class of mutations observed. We suggest a model for how the mammalian DNA methyltransferase may be involved in facilitating these mutations. The observation that 5-aza-2-deoxycytidineinduced mutations are mediated by the enzyme suggests that novel inhibitors of DNA methyltransferase, which can inactivate the enzyme before its interaction with DNA, are needed for chemoprevention or long term therapy.

Purpose: Pediatric DMGs are highly malignant tumors with poor clinical outcomes. Over 70% of DMG patients harbor the histone 3 p.K27M (H3K27M) mutation, which correlates with a poorer clinical outcome, and is also used as a criterion for enrollment in clinical trials. Because complete surgical resection of DMG is not an option, biopsy at presentation is feasible, but re-biopsy at time of progression is rare. While imaging and clinical-based disease monitoring is the standard of care, molecular-based longitudinal characterization of these tumors is almost non-existent. To overcome these hurdles we examined if liquid biopsy allows measurement of disease response to precision therapy. Experimental Design: We established a sensitive and specific methodology which detects major driver mutations associated with pediatric DMGs using droplet digital PCR (n=48 subjects, n=110 specimens). Quantification of ctDNA for H3K27M was used for longitudinal assessment of disease response compared to centrally reviewed MRI data. Results: H3K27M was identified in cerebrospinal fluid (CSF) and plasma in 88% of patients with DMG, with CSF being the most enriched for ctDNA. We demonstrated the feasibility of multiplexing for detection of H3K27M, and additional driver mutations in patient’s tumor and matched CSF, maximizing the utility of a single source of liquid biome. A significant decrease in H3K27M plasma ctDNA agreed with MRI assessment of tumor response to radiotherapy in 83% (10/12) of patients. Conclusions: Our liquid biopsy approach provides a molecularly-based tool for tumor characterization, and is the first to indicate clinical utility of ctDNA for longitudinal surveillance of DMGs.

RBCT is associated with an increase in Pbto2 in most patients with subarachnoid hemorrhage or traumatic brain injury. This mean increase appears to be independent of cerebral perfusion pressure, Sao2, and Fio2. Further study is required to determine why Pbto2 decreases in some patients after RBCT.

Diffuse Intrinsic Pontine Glioma (DIPG) is a highly morbid form of pediatric brainstem glioma. Here, we present the first comprehensive protein, mRNA, and methylation profiles of fresh frozen DIPG specimens (n=14), normal brain tissue (n=10), and other pediatric brain tumors (n=17). Protein profiling identified 2,305 unique proteins indicating distinct DIPG protein expression patterns compared to other pediatric brain tumors. Western blot and immunohistochemistry validated upregulation of Clusterin (CLU), Elongation Factor 2 (EF2), and Talin-1 (TLN1) in DIPGs studied. Comparisons to mRNA expression profiles generated from tumor and adjacent normal brain tissue indicated two DIPG subgroups, characterized by upregulation of Myc (N-Myc) or Hedgehog (Hh) signaling. We validated upregulation of PTCH, a membrane receptor in the Hh signaling pathway, in a subgroup of DIPG specimens. DNA methylation analysis indicated global hypomethylation of DIPG compared to adjacent normal tissue specimens, with differential methylation of 24 genes involved in Hh and Myc pathways, correlating with protein and mRNA expression patterns. Sequencing analysis showed c.83A>T mutations in the H3F3A or HIST1H3B gene in 77% of our DIPG cohort. Supervised analysis revealed a unique methylation pattern in mutated specimens compared to the wild type DIPG samples. This study presents the first comprehensive multidimensional protein, mRNA, and methylation profiling of pediatric brain tumor specimens, detecting the presence of two subgroups within our DIPG cohort. This multidimensional analysis of DIPG provides increased analytical power to more fully explore molecular signatures of DIPGs, with implications for evaluating potential molecular subtypes and biomarker discovery for assessing response to therapy.

This clinical trial evaluated whether whole exome sequencing (WES) and RNA sequencing (RNAseq) of paired normal and tumor tissues could be incorporated into a personalized treatment plan for newly diagnosed patients (<25 years of age) with diffuse intrinsic pontine glioma (DIPG). Additionally, whole genome sequencing (WGS) was compared to WES to determine if WGS would further inform treatment decisions, and whether circulating tumor DNA (ctDNA) could detect the H3K27M mutation to allow assessment of therapy response. Patients were selected across three Pacific Pediatric Neuro‐Oncology Consortium member institutions between September 2014 and January 2016. WES and RNAseq were performed at diagnosis and recurrence when possible in a CLIA‐certified laboratory. Patient‐derived cell line development was attempted for each subject. Collection of blood for ctDNA was done prior to treatment and with each MRI. A specialized tumor board generated a treatment recommendation including up to four FDA‐approved agents based upon the genomic alterations detected. A treatment plan was successfully issued within 21 business days from tissue collection for all 15 subjects, with 14 of the 15 subjects fulfilling the feasibility criteria. WGS results did not significantly deviate from WES‐based therapy recommendations; however, WGS data provided further insight into tumor evolution and fidelity of patient‐derived cell models. Detection of the H3F3A or HIST1H3B K27M (H3K27M) mutation using ctDNA was successful in 92% of H3K27M mutant cases. A personalized treatment recommendation for DIPG can be rendered within a multicenter setting using comprehensive next‐generation sequencing technology in a clinically relevant timeframe.

SUMMARY Because molecular mechanisms underlying refractory focal epilepsy are poorly defined, we performed transcriptome analysis on human epileptogenic tissue. Compared with controls, expression of Circadian Locomotor Output Cycles Kaput (CLOCK) is decreased in epileptogenic tissue. To define the function of CLOCK, we generated and tested the Emx-Cre; Clockflox/flox and PV-Cre; Clockflox/flox mouse lines with targeted deletions of the Clock gene in excitatory and parvalbumin (PV)-expressing inhibitory neurons, respectively. The Emx-Cre; Clockflox/flox mouse line alone has decreased seizure thresholds, but no laminar or dendritic defects in the cortex. However, excitatory neurons from the Emx-Cre; Clockflox/flox mouse have spontaneous epileptiform discharges. Both neurons from Emx-Cre; Clockflox/flox mouse and human epileptogenic tissue exhibit decreased spontaneous inhibitory post-synaptic currents. Finally, video-EEG of Emx-Cre; Clockflox/flox mice reveals epileptiform discharges during sleep and also seizures arising from sleep. Altogether, these data show that disruption of CLOCK alters cortical circuits and may lead to generation of focal epilepsy.

Diffuse intrinsic pontine glioma (DIPG) is a leading cause of brain tumor -related death in children. DIPG is not surgically resectable, resulting in a paucity of tissue available for molecular studies. As such, tumor biology is poorly understood, and, currently, there are no effective treatments. In the absence of frozen tumor specimens, body fluids-such as cerebrospinal fluid (CSF), serum, and urine-can serve as more readily accessible vehicles for detecting tumor-secreted proteins. We analyzed a total of 76 specimens, including CSF, serum, urine, and normal and tumor brainstem tissue. Protein profiling of CSF from patients with DIPG was generated by mass spectrometry using an LTQ-Orbitrap-XL and database search using the Sequest algorithm. Quantitative and statistical analyses were performed with ProteoIQ and Partek Genomics Suite. A total of 528 unique proteins were identified, 71% of which are known secreted proteins. CSF proteomic analysis revealed selective upregulation of Cyclophillin A (CypA) and dimethylarginase 1 (DDAH1) in DIPG (n 5 10), compared with controls (n 5 4). Protein expression was further validated with Western blot analysis and immunohistochemical assays using CSF, brain tissue, serum, and urine from DIPG and control specimens. Immunohistochemical staining showed selective upregulation of secreted but not cytosolic CypA and DDAH1 in patients with DIPG. In this study, we present the first comprehensive protein profile of CSF specimens from patients with DIPG to demonstrate selective expression of tumor proteins potentially involved in brainstem gliomagenesis. Detection of secreted CypA and DDAH1 in serum and urine has potential clinical application, with implications for assessing treatment response and detecting tumor recurrence in patients with DIPG.

BACKGROUND Although ventriculoperitoneal shunts (VPS) remain the first-line option in most instances of pediatric hydrocephalus, the long-term efficacy of ventriculoatrial shunts (VAS) remains unknown. OBJECTIVE To characterize the long-term outcomes and adverse occurrences associated with both VPS and VAS at our institution. METHODS The authors retrospectively analyzed all cerebrospinal fluid (CSF) shunting procedures performed over a 13-yr period at a single institution. A total of 544 pediatric shunt patients were followed for at least 90 d (VPS: 5.9 yr; VAS: 5.3 yr). RESULTS A total of 54% of VPS and 60% of VAS required at least 1 revision. VPS demonstrated superior survival overall; however, if electively scheduled VAS lengthening procedures are not considered true “failures,” no statistical difference is noted in overall survival (P = .08). VPS demonstrated significantly greater survival in patients less than 7 yr of age (P = .001), but showed no difference in older children (P = .4). VAS had a significantly lower rate of infection (P &lt; .05) and proximal failure (P &lt; .001). CONCLUSION VAS can be a useful alternative to VPS when the abdomen is unsuitable, particularly in older children. Although VPS demonstrates superior overall survival, it should be understood that elective VAS lengthening procedures are often necessary, especially in younger patients. If elective lengthening procedures are not considered true failures, then the devices show similar survival.