Pediatric Brainstem Research Articles

Identification of new therapeutic targets and natural compounds against diffuse intrinsic pontine glioma (DIPG).

Diffuse Intrinsic Pontine Glioma (DIPG) is a highly aggressive pediatric brainstem tumor which accounts for about 10-20% of childhood brain tumors. The survival rate for DIPG remains very poor, with a median survival of less than 1year. The dismal prognosis associated with DIPG has been exacerbated by the failure of a large number of clinical trials to meaningfully improve survival compared with radiotherapy, the current standard of care for DIPG. In the current study, we screened a natural product library and for the first time identified 6 natural compounds displaying inhibitory effects on DIPG proliferation and anchorage-independent growth through inducing tumor cell apoptosis and cell cycle arrest. Subsequent RNA-Sequencing and functional validation revealed the molecular mechanisms of these compounds with anti-DIPG activities, and identified new cellular factors such as Fibronectin 1 (FN1) and Eukaryotic translation initiation factor 3 subunit C-like (EIF3CL), required for DIPG survival as potential therapeutic targets. Our study provides promising directions to fight against this deadly pediatric cancer.

Genomic and serologic characterization of enterovirus A71 brainstem encephalitis.

ObjectiveIn 2016, Catalonia experienced a pediatric brainstem encephalitis outbreak caused by enterovirus A71 (EV-A71). Conventional testing identified EV in the periphery but rarely in CSF. Metagenomic next-generation sequencing (mNGS) and CSF pan-viral serology (VirScan) were deployed to enhance viral detection and characterization.MethodsRNA was extracted from the CSF (n = 20), plasma (n = 9), stool (n = 15), and nasopharyngeal samples (n = 16) from 10 children with brainstem encephalitis and 10 children with meningitis or encephalitis. Pathogens were identified using mNGS. Available CSF from cases (n = 12) and pediatric other neurologic disease controls (n = 54) were analyzed with VirScan with a subset (n = 9 and n = 50) validated by ELISA.ResultsmNGS detected EV in all samples positive by quantitative reverse transcription polymerase chain reaction (qRT-PCR) (n = 25). In qRT-PCR-negative samples (n = 35), mNGS found virus in 23% (n = 8, 3 CSF samples). Overall, mNGS enhanced EV detection from 42% (25/60) to 57% (33/60) (p-value = 0.013). VirScan and ELISA increased detection to 92% (11/12) compared with 46% (4/12) for CSF mNGS and qRT-PCR (p-value = 0.023). Phylogenetic analysis confirmed the EV-A71 strain clustered with a neurovirulent German EV-A71. A single amino acid substitution (S241P) in the EVA71 VP1 protein was exclusive to the CNS in one subject.ConclusionmNGS with VirScan significantly increased the CNS detection of EVs relative to qRT-PCR, and the latter generated an antigenic profile of the acute EV-A71 immune response. Genomic analysis confirmed the close relation of the outbreak EV-A71 and neuroinvasive German EV-A71. A S241P substitution in VP1 was found exclusively in the CSF.

Combined Targeting of Mutant p53 and Jumonji Family Histone Demethylase Augments Therapeutic Efficacy of Radiation in H3K27M DIPG.

Diffuse intrinsic pontine glioma (DIPG) is an aggressive pediatric brainstem tumor with a 5-year survival of <1%. Up to 80% of the DIPG tumors contain a specific K27M mutation in one of the two genes encoding histone H3 (H3K27M). Furthermore, p53 mutations found in >70–80% of H3K27M DIPG, and mutant p53 status is associated with a decreased response to radiation treatment and worse overall prognosis. Recent evidence indicates that H3K27M mutation disrupts tri-methylation at H3K27 leading to aberrant gene expression. Jumonji family histone demethylases collaborates with H3K27 mutation in DIPG by erasing H3K27 trimethylation and thus contributing to derepression of genes involved in tumorigenesis. Since the first line of treatment for pediatric DIPG is fractionated radiation, we investigated the effects of Jumonji demethylase inhibition with GSK-J4, and mutant p53 targeting/oxidative stress induction with APR-246, on radio-sensitization of human H3K27M DIPG cells. Both APR-246 and GSK-J4 displayed growth inhibitory effects as single agents in H3K27M DIPG cells. Furthermore, both of these agents elicited mild radiosensitizing effects in human DIPG cells (sensitizer enhancement ratios (SERs) of 1.12 and 1.35, respectively; p < 0.05). Strikingly, a combination of APR-246 and GSK-J4 displayed a significant enhancement of radiosensitization, with SER of 1.50 (p < 0.05) at sub-micro-molar concentrations of the drugs (0.5 μM). The molecular mechanism of the observed radiosensitization appears to involve DNA damage repair deficiency triggered by APR-246/GSK-J4, leading to the induction of apoptotic cell death. Thus, a therapeutic approach of combined targeting of mutant p53, oxidative stress induction, and Jumonji demethylase inhibition with radiation in DIPG warrants further investigation.

Progress in diffuse intrinsic pontine glioma: advocating for stereotactic biopsy in the standard of care.

Diffuse intrinsic pontine glioma (DIPG) is a universally fatal pediatric brainstem tumor affecting approximately 300 children in the US annually. Median survival is less than 1 year, and radiation therapy has been the mainstay of treatment for decades. Recent advances in the biological understanding of the disease have identified the H3K27M mutation in nearly 80% of DIPGs, leading to the 2016 WHO classification of diffuse midline glioma H3K27M-mutant, a grade IV brainstem tumor. Developments in epigenetic targeting of transcriptional tendencies have yielded potential molecular targets for clinical trials. Chimeric antigen receptor T cell therapy has also shown preclinical promise. Recent clinical studies, including prospective trials, have demonstrated the safety and feasibility of pediatric brainstem biopsy in the setting of DIPG and other brainstem tumors. Given developments in the ability to analyze DIPG tumor tissue to deepen biological understanding of this disease and develop new therapies for treatment, together with the increased safety of stereotactic brainstem biopsy, the authors present a case for offering biopsy to all children with suspected DIPG. They also present their standard operative techniques for image-guided, frameless stereotactic biopsy.

Deformational changes after convection-enhanced delivery in the pediatric brainstem.

In the brainstem, there are concerns regarding volumetric alterations following convection-enhanced delivery (CED). The relationship between distribution volume and infusion volume is predictably greater than one. Whether this translates into deformational changes and influences clinical management is unknown. As part of a trial using CED for diffuse intrinsic pontine glioma (DIPG), the authors measured treatment-related volumetric alterations in the brainstem and ventricles. Enrolled patients underwent a single infusion of radioimmunotherapy. Between 2012 and 2019, 23 patients with volumetric pre- and postoperative day 1 (POD1) and day 30 (POD30) MRI scans were analyzed using iPlan® Flow software for semiautomated volumetric measurements of the ventricles and pontine segment of the brainstem. Children in the study had a mean age of 7.7 years (range 2-18 years). The mean infusion volume was 3.9 ± 1.7 ml (range 0.8-8.8 ml). Paired t-tests demonstrated a significant increase in pontine volume immediately following infusion (p < 0.0001), which trended back toward baseline by POD30 (p = 0.046; preoperative 27.6 ± 8.4 ml, POD1 30.2 ± 9.0 ml, POD30 29.5 ± 9.4 ml). Lateral ventricle volume increased (p = 0.02) and remained elevated on POD30 (p = 0.04; preoperative 23.5 ± 15.4 ml, POD1 26.3 ± 16.0, POD30 28.6 ± 21.2). Infusion volume had a weak, positive correlation with pontine and lateral ventricle volume change (r2 = 0.22 and 0.27, respectively). Four of the 23 patients had an increase in preoperative neurological deficits at POD30. No patients required shunt placement within 90 days. CED infusion into the brainstem correlates with immediate but self-limited deformation changes in the pons. The persistence of increased ventricular volume and no need for CSF diversion post-CED are inconsistent with obstructive hydrocephalus. Defining the degree and time course of these deformational changes can assist in the interpretation of neuroimaging along the DIPG disease continuum when CED is incorporated into the treatment algorithm.

Pediatric brain stem death: Perspectives for the future in India

Pediatric brain stem death needs to be recognized both for futility in resuscitative efforts and in scope for organ donation. Pediatric donation can be performed from 37 weeks gestational age to 18 years. The diagnosis of brain stem death is completed by two clinical examinations separated by an interval of 24 h in term newborns and neonates and 12-h interval infants and children. Apnea testing is the main diagnostic test supported by tests of cranial nerve functions. Ancillary tests have not been approved for the diagnosis of brain stem death in India. Donor management is critical and needs invasive lines and attention to the maintenance of hemodynamics, fluid management, temperature, and hormonal resuscitation.Shifting the goals of care to organ maintenance can be challenging for the medical team. Counseling for donation needs to be sympathetic and honest while letting the parents understand that return back to life is impossible. Religious, cultural, and social customs of the family need to be respected and supported and the medical social worker is the key person in the establishment of a rapport with the grieving family. Creation of awareness among public and health-care professionals beside the involvement of governmental organizations both to endorse the process and support costs toward the program at least in its developmental phase is needed for this program in India.

Targeting Sphingosine Kinase by ABC294640 against Diffuse Intrinsic Pontine Glioma (DIPG).

As a highly aggressive pediatric brainstem tumor, diffuse intrinsic pontine glioma (DIPG) accounts for 10% to 20% of childhood brain tumors. The survival rate for DIPG remains very low, with a median survival time as less than one year even under radiotherapy, the current standard treatment. Moreover, over than 250 clinical trials have failed when trying to improve the survival compared to radiotherapy. The sphingolipid metabolism and related signaling pathways have been found closely related to cancer cell survival; however, the sphingolipid metabolism targeted therapies have never been investigated in DIPG. In the current study, the anti-DIPG activity of ABC294640, the only first-in-class orally available Sphingosine kinase (SphK) inhibitor was explored. Treatment with ABC294640 significantly repressed DIPG cell growth by inducing intracellular pro-apoptotic ceramides production and cell apoptosis. We also profiled ABC294640-induced changes in gene expression within DIPG cells and identified many new genes tightly controlled by sphingolipid metabolism, such as IFITM1 and KAL1. These genes are required for DIPG cell survival and display clinical relevance in DIPG patients' samples. Together, our findings in this study indicate that targeting sphingolipid metabolism may represent a promising strategy to improve DIPG treatment.

Pediatric Auditory Brainstem Implants, Adult Single-Sided Deafness, and Teaching

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Pediatric intrinsic brainstem lesions: clinical, imaging, histological characterization, and predictors of survival.

Brainstem lesions comprise 10-20% of all pediatric brain tumors. Over the past years, the benefits of stereotactic biopsy versus the use alone of MRI features to guide treatment have been controversial. Retrospective study with pediatric patients submitted to stereotactic brainstem biopsies between 2008 and 2018. Demographic, clinical, imaging, and surgical characteristics were recorded, as well as the histological diagnosis, complications, and survival. Predictors of survival were evaluated through Cox regression models after multivariate adjustment. Twenty-six patients (mean age of 8.8 ± 4.3years and 14 female). Diagnosis was reached on 84.6% (95% CI 65.1-95.6%) of the patients. Glioma was diagnosed on 20 cases (11 high-grade and 9 low-grade lesions). There was no association between age and gender and the dichotomized histological diagnosis. Contrast enhancement, diffuse distribution, invasion of adjacent structures, and remote injury were present on 62.5%, 75.0%, 62.5%, and 25.0% of the cases. Hydrocephalus at admission was present on almost half of the patients (46.2%). Only radiological invasion of adjacent structures had a possible association with high-grade lesions (p = 0.057). Surgical trajectory was trans-cerebellar in most of the cases (79.9%). There were no major complications and only two minor/transitory complications. Poorer survival was independently associated with high-grade lesions (HR 32.14, 95% CI 1.40-735.98, p = 0.030) and contrast enhancement at MRI (HR 36.54, 95% CI 1.40-952.26, p = 0.031). Stereotactic biopsy was safe and allows successful tissue sampling for a definite diagnosis. Poorer survival was independently associated with high-grade and contrast-enhancing lesions.

Pediatric Brainstem Gliomas: An Institutional Experience.

Objective:The aim of this study was to analyze the clinical profiles and outcomes of pediatric brainstem gliomas treated at our institute.Methodology:We reviewed the files of 18 pediatric age group patients diagnosed with brainstem glioma at our institution. The following variables were recorded: age, sex, duration of symptoms, date of diagnosis, main clinical symptoms, Karnofsky performance status score, magnetic resonance imaging findings, histopathology findings, details of the treatment given, disease progression, and date of mortality/last follow-up. This data were then transferred to SPSS version 23 which was used for further analysis.Results:The mean age of our cohort was 8.6 years (range 3–15). There were 11 (61.1%) males and 7 (38.9%) females. There were 16 (88.9%) patients with diffuse intrinsic pontine gliomas (DIPGs), 1 (5.6%) patients with exophytic medullary gliomas, and 1 (5.6%) patient with midbrain/tectal glioma. Mean overall survival (OS) was 9.7 months. Mean progression-free survival (PFS) was 6.3 months. All patients with DIPG eventually passed away from their disease. Patients with DIPG who received radiotherapy had a longer OS and PFS than those who did not (9.8 and 6 months vs. 3.4 and 2.4 months). Diagnostic latency >1 month was found to have a statistically significant longer progression-free interval.Conclusion:DIPGs in the pediatric population have a poor prognosis. Radiotherapy serves to increase survival time but is not curative.

Favorable prognosis in pediatric brainstem low-grade glioma: Report from the German SIOP-LGG 2004 cohort.

Reports on pediatric low-grade glioma (LGG) of the caudal brainstem are retrospective with heterogeneous cohorts, variable treatments and inconsistent outcome data. We analyzed their natural history and asked whether brainstem location proved unfavorable for survival within the framework of the comprehensive SIOP-LGG 2004 management strategy. Within the prospectively registered, population-based German SIOP-LGG 2004 cohort 116 patients (age 0.2-16.5 years, 10% Neurofibromatosis NF1) were diagnosed with LGG of the pons (27%) and medulla oblongata (73%). After biopsy (23%), variable resection (63%) or radiologic diagnosis only (14%), 59 patients received no adjuvant treatment. Radiologic progression or severe neurologic symptoms prompted chemo- (n = 39) or radiotherapy (n = 18). After further progression (28/57), salvage treatments included multiple treatment lines for 12/28 patients. Five-years event-free survival dropped to 0.40, while 5-years overall survival was 0.95 (median observation time 6.8 years). Higher extent of resection yielded lower progression rate (p = 0.001), but at a cost of 21/100 patients suffering from new postsurgical complications including respiratory insufficiency. Central review confirmed pilocytic astrocytoma (56%), diffuse astrocytoma (8%) or glioneuronal histology (16%) (others 4%, no histology 17%). Malignant evolution was documented in five patients associated with Histone3 mutation in 2/5. Our treatment algorithm conveyed high overall survival for pediatric brainstem LGG. Extensive neurosurgical resection did increase additional postoperative neurologic deficits but not overall survival in this often-chronic disease. More than half of all patients can be safely followed by observation, while multimodal adjuvant treatment can control progressive tumors. Molecular assessment should confirm low-grade diagnosis and may detect patterns prognostic for malignant evolution.

Epigenetic reprogramming and chromatin accessibility in pediatric diffuse intrinsic pontine gliomas: a neural developmental disease.

Diffuse intrinsic pontine glioma (DIPG) is a rare but deadly pediatric brainstem tumor. To date, there is no effective therapy for DIPG. Transcriptomic analyses have revealed DIPGs have a distinct profile from other pediatric high-grade gliomas occurring in the cerebral hemispheres. These unique genomic characteristics coupled with the younger median age group suggest that DIPG has a developmental origin. The most frequent mutation in DIPG is a lysine to methionine (K27M) mutation that occurs on H3F3A and HIST1H3B/C, genes encoding histone variants. The K27M mutation disrupts methylation by polycomb repressive complex 2 on histone H3 at lysine 27, leading to global hypomethylation. Histone 3 lysine 27 trimethylation is an important developmental regulator controlling gene expression. This review discusses the developmental and epigenetic mechanisms driving disease progression in DIPG, as well as the profound therapeutic implications of epigenetic programming.

A comprehensive study on the mechanical properties of different regions of 8-week-old pediatric porcine brain under tension, shear, and compression at various strain rates

Young porcine brain is often used as a surrogate for studying the mechanical factors affecting traumatic brain injury in children. However, the mechanical properties of pediatric brain tissue derived from humans and piglets are very scarce, and this seriously detracts from the biofidelity of the developed finite element (FE) models of the pediatric head/brain. The present study addresses this issue by subjecting the cerebrum (white matter and gray matter), cerebellum, and brainstem specimens derived from 8-week-old piglets to tension and shear testing at strain rates of 0.01, 1, and 50/s. The experimental data are combined with the corresponding data derived from a previous study under compression to obtain comprehensive stress-strain curves of the pediatric porcine cerebrum, cerebellum, and brainstem tissue specimens. In general, the average stress level of the white matter is somewhat higher than that of the gray matter under the tension, shear and compression conditions, however, this difference does not reach a significant level. The stiffness of the cerebellum and the cerebrum does not differ significantly under tension and shear conditions, but the stiffness of the cerebellum is greater than that of the cerebrum under compression. The brainstem has significantly higher stiffness than the cerebrum and the cerebellum under all loading modes. In addition, the mechanical properties of brain tissue exhibit significant strain-rate dependences. With increasing strain rate from 0.01/s to 50/s, the average stress at a strain of 0.5 for all of the brain tissue increased by about 2.2 times under tension, about 2.4 times under shearing and about 2.2 times under compression. The variations in the stress as a function of the strain rate for brain tissue specimens were well characterized by exponential functions at strains of 0.25 and 0.5 under all three loading modes. The results of this study are useful for developing biofidelic FE models of the pediatric brain.

Clinical trials for diffuse intrinsic pontine glioma: the current state of affairs

Diffuse intrinsic pontine glioma (DIPG) is a lethal high-grade pediatric brainstem tumor without a cure. Despite numerous clinical trials over the last decades, the prognosis has remained poor. The aim of this update was to report on the status and outcomes of all clinical trials for DIPG performed to better understand the landscape of research efforts for this diagnosis to date. The ClinicalTrials.gov database was reviewed in May 2019 for all possible interventional clinical trials that included DIPG as a diagnosis of primary investigation. These were then screened against selection criteria to identify pertinent clinical trials. Ninety-five clinical trials satisfied all inclusion criteria, with 55 (58%) trials specific to the DIPG diagnosis only. In terms of the most prevalent design features, 42 (44%) were phase I trials, with median expected start and completion years in 2011 (range, 1994-2020) and 2018 (range, 2005-2047), respectively. Median target number of patients to enroll was 38 (range, 1-1500), and the most common primary outcome was safety and toxicity (56%). There were 69 (73%) trials originating from the USA, with 49 (52%) of them being single institutional. Only 10 (11%) trials have reported results to date. To date, 95 clinical trials investigating DIPG with specific emphasis have been registered on ClinicalTrials.gov. There were only a small number of trials that had study results available, and they uniformly reported non-significant improvement to prognosis. Given the rarity and lethality of DIPG, which limits the accumulation of large cohorts, our results mandate the need for more robust, systematic clinical trial design to minimize redundancies and maximize yield in the future.

Pediatric Auditory Brainstem Implant Users Compared With Cochlear Implant Users With Additional Disabilities.

To evaluate long-term language development in children with prelingual deafness who received auditory brainstem implants (ABIs) compared with children who received cochlear implants (CIs) at the same hospital. Additional non-auditory disabilities were taken into account. Retrospective cohort study. Tertiary referral center. Ten children with bilateral malformations of the cochlea and/or cochlear nerve who received ABIs, including seven with additional disabilities, and 147 children with CIs as a reference group, including 22 children with additional disabilities. ABIs were implanted at 1.3 to 6.2 years of age. Follow-up ranged from 1.1 to 7.7 years. Receptive and expressive language abilities were assessed using the Infant Toddler Meaningful Auditory Integration Scale (IT-MAIS), the Categories of Auditory Performance (CAP), the Meaningful Use of Speech Scale (MUSS), and the Speech Intelligibility Rate (SIR). Of the 10 children with ABIs, seven had long-term follow-up data. Within 1 year, six of the seven children with ABIs could identify sounds, respond to speech, and use their voice to attract attention. Language skills developed at a slower rate than in children with CIs and reached the same competence level when additional disabilities were absent. These language skills matched, on average, those of children with CIs with additional disabilities. For deaf children with bilateral inner ear malformations, ABIs provide satisfactory auditory input. Children with ABIs are able to develop receptive and expressive language skills comparable to those of children with CIs with additional disabilities. Using this knowledge, preoperative parent counselling can be refined.

Diverse immunotherapies can effectively treat syngeneic brainstem tumors in the absence of overt toxicity

BackgroundImmunotherapy has shown remarkable clinical promise in the treatment of various types of cancers. However, clinical benefits derive from a highly inflammatory mechanism of action. This presents unique challenges for use in pediatric brainstem tumors including diffuse intrinsic pontine glioma (DIPG), since treatment-related inflammation could cause catastrophic toxicity. Therefore, the goal of this study was to investigate whether inflammatory, immune-based therapies are likely to be too dangerous to pursue for the treatment of pediatric brainstem tumors.MethodsTo complement previous immunotherapy studies using patient-derived xenografts in immunodeficient mice, we developed fully immunocompetent models of immunotherapy using transplantable, syngeneic tumors. These four models – HSVtk/GCV suicide gene immunotherapy, oncolytic viroimmunotherapy, adoptive T cell transfer, and CAR T cell therapy – have been optimized to treat tumors outside of the CNS and induce a broad spectrum of inflammatory profiles, maximizing the chances of observing brainstem toxicity.ResultsAll four models achieved anti-tumor efficacy in the absence of toxicity, with the exception of recombinant vaccinia virus expressing GMCSF, which demonstrated inflammatory toxicity. Histology, imaging, and flow cytometry confirmed the presence of brainstem inflammation in all models. Where used, the addition of immune checkpoint blockade did not introduce toxicity.ConclusionsIt remains imperative to regard the brainstem with caution for immunotherapeutic intervention. Nonetheless, we show that further careful development of immunotherapies for pediatric brainstem tumors is warranted to harness the potential potency of anti-tumor immune responses, despite their possible toxicity within this anatomically sensitive location.

Abstract 3920: Differential effects of Jumonji family demethylase and EZH2 H3K27 methyltransferase inhibition on radiation sensitivity of H3K27M mutant DIPG

Abstract Diffuse intrinsic pontine glioma (DIPG) is an aggressive pediatric brainstem tumor with a 5-year survival of &amp;lt;1% (1). Up to 80% of DIPG tumors contain a specific K27M mutation in one of two genes encoding histone H3 (H3K27M). 60-75% of H3K27M mutations occur in gene encoding histone variant H3.3, which has been linked to reduced overall survival and poor response to first line radiation therapy (1). Recent evidence indicates that H3K27M inhibits the enzymatic activity of Polycomb Repressive Complex 2 through interaction with the EZH2 histone methyl transferase (2). A specific inhibitor of Jumonji family histone demethylase GSK-J4 was recently reported to restore H3K27 tri-methylation patterns in human DIPG cells and improve survival of H3K27M mutant orthotopic xenograft brainstem tumor models (3). Furthermore, a genetic deletion of EZH2 had also been shown to improve survival of H3K27M mouse model of DIPG, suggesting that EZH2 may be a potential therapeutic target (4). Given these data, we investigated the effects of Jumonji demethylase inhibitor GSK-J4 and EZH2 inhibitor tazemetostat on radiosensitization of human H3K27M DIPG cells. We found that GSK-J4 inhibitor had a growth inhibitory effect on H3K27M mutant DIPG cells as a single agent (96% growth inhibition at 1.5 micro-molar concentration, P&amp;lt;0.0001). Strikingly, GSK-J4 inhibitor also displayed radiosensitizing effects when combined with ionizing radiation at sub-micromolar concentrations of the drug (34.4% growth inhibition at 0.37 micro-molar concentration when combined with 4 Gy XRT vs 23.3% with XRT alone, P&amp;lt;0.0001 for both; no significant growth inhibition as single agent). Contrary to previously reported results with EZH2 inhibition in H3K27M neural stem cell model of DIPG, EZH2 inhibitor tazemetostat had no effect on human H3K27M DIPG cells as a single agent or when combined with ionizing radiation. This result is, however, not unexpected, given the proposed inhibitory effect of H3K27M mutation on EZH2 activity in DIPG disease pathogenesis. In conclusion, Jumonji family methyltransferase inhibitor GSK-4J sensitizes H3K27M DIPG cells to ionizing radiation, while EZH2 methyltransferase inhibitor has no effect. This result appears to be consistent with the recently proposed epigenetic mechanism of DIPG pathogenesis (1, 2). 1. Johung TB, et al. Diffuse intrinsic pontine glioma: new pathophysiological insights and emerging therapeutic targets. Curr Neuropharmacol. 2017;15:88-97. 2. Lewis PW, et al. Inhibition of PRC2 activity by a gain-of-function H3 mutation found in pediatric glioblastoma. Science. 2013;340:857-61. 3. Hashizume R, et al. Pharmacologic inhibition of histone demethylation as a therapy for pediatric brainstem glioma. Nat Med. 2014;20:1394-6. 4. Mohammad F, et al. EZH2 is a potential therapeutic target for H3K27M-mutant pediatric gliomas. Nat Med. 2017;23:483-492. Citation Format: Anatoly Y. Nikolaev, John B. Fiveash, Eddy S. Yang. Differential effects of Jumonji family demethylase and EZH2 H3K27 methyltransferase inhibition on radiation sensitivity of H3K27M mutant DIPG [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3920.

Effect of anesthesia on evoked auditory responses in pediatric auditory brainstem implant surgery.

Electrically evoked auditory brainstem responses (EABR) guide placement of the multichannel auditory brainstem implant (ABI) array during surgery. EABRs are also recorded under anesthesia in nontumor pediatric ABI recipients prior to device activation to confirm placement and guide device programming. We examine the influence of anesthesia on evoked response morphology in pediatric ABI users by comparing intraoperative with postoperative EABR recordings. Retrospective review. Seven children underwent ABI surgery by way of retrosigmoid craniotomy. General anesthesia included inhaled sevoflurane induction and propofol maintenance during which EABRs were recorded to confirm accurate positioning of the ABI. A mean of 7.7 ± 2.8 weeks following surgery, the ABI was activated under general anesthesia or sedation (dexmedetomidine) and EABR recordings were made. A qualitative analysis of intraoperative and postoperative waveform morphology was performed. Seven subjects (mean age 20.6 months) underwent nine ABI surgeries (seven primary, two revisions) and nine activations. EABRs were observed in eight of nine postoperative recordings. In three cases, intraoperative EABRs during general anesthesia were similar to postoperative EABRs with sedation. In one case, sevoflurane and propofol were used for intra- and postoperative recordings, and waveforms were also similar. In four cases, amplitude and latency changes were observed for intraoperative versus postoperative EABRs. Similarity of EABR morphology in the anesthetized versus sedated condition suggests that anesthesia does not have a large effect on far-field evoked potentials. Changes in EABR waveform morphology observed postoperatively may be influenced by other factors such as movements of the surface array. 4 Laryngoscope, 130:507-513, 2020.

Tenascin-C expression contributes to pediatric brainstem glioma tumor phenotype and represents a novel biomarker of disease

Diffuse intrinsic pontine glioma (DIPG), an infiltrative, high grade glioma (HGG) affecting young children, has the highest mortality rate of all pediatric cancers. Despite treatment, average survival is less than twelve months, and five-year survival under 5%. We previously detected increased expression of Tenascin-C (TNC) protein in DIPG cerebrospinal fluid and tumor tissue relative to normal specimens. TNC is an extracellular matrix (ECM) glycoprotein that mediates cell-matrix interactions, guides migrating neurons during normal brain development and is thought to maintain the periventricular stem cell niche in the developing brain. Tumor TNC expression is reported in adult glioma and other cancers. However, the pattern and effects of TNC expression in DIPG has not been previously explored. Here, we characterize TNC expression in patient derived pediatric supratentorial HGG (n = 3) and DIPG (n = 6) cell lines, as well as pediatric glioma tumor (n = 50) and normal brain tissue specimens (n = 3). We found tumor specific TNC gene and protein overexpression that directly correlated with higher tumor grade (WHO III and IV, p = 0.05), H3K27 M mutation (p = 0.012), shorter progression free survival (p = 0.034), and poorer overall survival (0.041) in association with these factors. TNC knockdown via lentiviral shRNA transfection of HGG (n = 1) and DIPG (n = 3) cell lines resulted in decreased cell proliferation, migration, and invasion in vitro (p < 0.01), while TNC cDNA transfection resulted in increased cell migration, invasion and proliferation (p < 0.01) as well as altered cell morphology in H3K27 M mutant DIPG lines. Whole transcriptome sequencing analysis (RNA-Seq) on DIPG (n = 3) and HGG (n = 2) cell lines after TNC cDNA, shRNA, and empty vector control transfection revealed the effects of TNC expression level on global gene expression profiles. Together, our findings reveal TNC expression in DIPG in association with H3K27 M mutation and VEGF signaling, and suggest that TNC may contribute to DIPG tumor phenotype, and serve as a clinically detectable biomarker for DIPG.

Expressive Vocabulary Growth After Pediatric Auditory Brainstem Implantation in Two Cases' Spontaneous Productions: A Comparison With Children With Cochlear Implants and Typical Hearing.

Auditory brainstem implants (ABI) are recently being used to restore hearing of children with a congenital hearing loss, due to for instance the absence of auditory nerves. Thus far, the literature has focused on perceptual outcomes. The present study is among the first ones to investigate the spoken language development after implantation. The lexical development of children with ABI is examined longitudinally in comparison to children with typical hearing and children with cochlear implants. Results show that children with ABI still have smaller spoken vocabularies as compared to (hearing) age-matched children with cochlear implants and children with typical hearing. Implications will be discussed.