Neurology & Neurosurgery

Neurology and neurosurgery update: whole exome sequencing, Sesame Workshop

May 9, 2016 – WES yields clinical diagnoses for 42 percent, ending ‘diagnostic odyssey’.
Whole exome sequencing (WES), a method to look at all the genes in the genome at once, yielded clinical diagnoses for 42 percent of patients whose white matter abnormalities had been unresolved an average of eight years, ending families’ “prolonged diagnostic odyssey.”  White matter disorders, which affect 1 in 7,000 children born each year, are progressive and involve age-related weakness in the region of the nerves that connect various parts of the brain to each other and to the spinal cord. Nine of 28 named authors of the study, published online May 9, 2016 in Annals of Neurology, are affiliated with Children’s National Health System.

April 6, 2016 – Georgetown, Children’s National researchers to evaluate Sesame Workshop’s Autism Initiative.
Sesame Workshop, the nonprofit educational organization behind Sesame Street, has selected Georgetown University Medical Center and Children’s National Health System researchers to lead an evaluation of  “Sesame Street and Autism: See Amazing in All Children,” an initiative developed to reduce stigma and build understanding about autism spectrum disorder. Sesame Workshop launched a new phase of its autism initiative in early April. Last year, Sesame Street introduced Julia, an autistic preschool digital Muppet, and accompanying resources, such as an app, videos, storybooks, and daily routine cards as part of the Sesame Street and Autism: See Amazing in All Children initiative. Now ready for evaluation, Sesame Workshop awarded a grant for real-world testing of the materials to Bruno Anthony, PhD, deputy director of the Georgetown Center for Child and Human Development in collaboration with his wife and research collaborator Laura Anthony, PhD, at the Center for Autism Spectrum Disorder at Children’s National.

In Brief- Fetal Medicine

Cognitive training exercises at home help kids with sickle cell boost visuospatial working memory

A team led by Children’s National Health System clinicians and research scientists attempted to identify novel approaches to boost working memory in children who suffer from sickle cell disease.

A team led by Children’s National Health System clinicians and research scientists attempted to identify novel approaches to boost working memory in children who suffer from sickle cell disease.

Youths with sickle cell disease who used hand-held computers to play game-like exercises that get harder as a user’s skill level rises improved their visuospatial working memory (WM). Children with sickle cell disease, however, completed fewer training sessions during an initial study compared with children with other disease-related WM deficits.

A team led by Children’s National Health System clinicians and research scientists attempted to identify novel approaches to boost WM in children who suffer from sickle cell disease. Kids who have this red blood cell disorder inherit abnormal hemoglobin genes from each parent. Rather than slipping through large and small vessels to ferry oxygen throughout the body, their stiff, sickle-shaped red blood cells stick to vessel walls, impeding blood supply and triggering sudden pain. Children with sickle cell disease have more difficulty completing tasks that place demands on one’s WM, the brain function responsible for temporarily remembering information and manipulating that information to facilitate learning and reasoning. As a result, they’re more likely to repeat a grade, require special academic services, and to have difficulty maintaining employment as adults.

Because computerized cognitive training programs have been used with success to boost WM for children with other health conditions, such as childhood cancer, the research team sought to examine the feasibility of using the technique for kids with sickle cell disease. “This small study highlights the challenges and opportunities of implementing a home-based cognitive training intervention with youths who have sickle cell disease,” says Steven J. Hardy, PhD, a pediatric psychologist in the Divisions of Hematology, Oncology, and Blood and Marrow Transplantation at Children’s National. “While a larger, randomized controlled clinical trial is needed to better characterize efficacy, our initial work indicates that Cogmed is acceptable and moderately feasible in this population.”

Children’s National is home to the Sickle Cell Disease (SCD) Program, one of the nation’s largest, most comprehensive pediatric programs that cares for 1,350 patients younger than 21 annually. Over 15 months, the team recruited youths aged 7 to 16 participating in the program who had an intelligence quotient of at least 70 and an absolute or relative memory deficit. Those who lacked access to a tablet computer were loaned an iPad Mini 2 loaded with Cogmed RM, an interactive audiovisual cognitive training program that consists of exercises that get progressively more challenging. A clinical psychologist provided coaching and moral support through weekly telephone calls to review progress and challenges, and to offer tips on how to optimize the youths’ progress.

Six of 12 eligible participants – all girls – completed by finishing at least 20 sessions of the program. The mean number of sessions completed was 15.83, and the kids spent a median of 725 minutes working actively on Cogmed exercises. “Participants who completed Cogmed indicated that they perceived greater levels of social support from teachers,” Hardy and colleagues write in the study, published by Pediatric Blood & Cancer. “[T]here was not a statistical difference in perceived parent support.”

Among those children who completed Cogmed, standard scores increased an average of 5.05 on a measure of visuospatial short-term memory, 19.72 on a measure of verbal WM, 27.53 on a measure of visuospatial short-term memory, and 23.82 on a measure of visuospatial WM. The researchers also observed a normalizing of memory functioning for those who finished Cogmed, as a significant portion of participants scored below the average range before using Cogmed and most scored in the average range or higher on memory tests after finishing the program.

“In this initial feasibility trial, adherence to Cogmed was lower than expected (50 percent completion) compared to adherence rates of other samples of children with medical histories, including patients with symptomatic epilepsy and youth treated for cancer,” Hardy and co-authors write. “Thus, additional modifications may be needed to achieve consistent delivery of the intervention to youth with SCD.”

Related Resources: Research at a Glance

Analysis of a progressive diffuse intrinsic pontine glioma: a case report

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What’s Known
Despite multiple clinical trials testing an assortment of new treatments, the survival rate for diffuse intrinsic pontine glioma (DIPG) remains abysmal, with most children succumbing to the pediatric brainstem tumor within 12 months of diagnosis. Focal radiation therapy, the primary treatment approach, has not improved overall survival. While the majority of DIPG tumors grow within the brainstem, metastases can occur elsewhere in the brain. Due to recent availability of tissue, new data are emerging about the biologic behavior of tumors, details that could be instrumental in constructing optimal treatment strategies.

What’s New
An otherwise healthy 9-year-old girl developed weakness in the left side of her face; magnetic resonance imagining revealed T2/FLAIR hyperintensity centered within and expanding the pons. Despite various treatments, her pontine lesion increased in size and new metastases were noted. The team led by Children’s National Health System researchers is the first to report comprehensive phenotypic analyses comparing multiple sites in primary and distant tumors. All tumor sites displayed positive staining for the H3K27M mutation, a mutation described in more than two-thirds of DIPGs that may portend a worse overall survival. Persistence of mutational status across multiple metastatic sites is particularly important since the effectiveness of some therapeutic approaches relies on this occurring. mRNA analyses, by contrast, identified a small number of genes in the primary tumor that differed from one metastatic tumor. This divergence implies that a single biopsy analysis for mRNA expression has the potential to be misleading.

Questions for Future Research
Q: Because a small cohort of genes in the girl’s primary tumor were different from genes in portions of the metastatic tumor, would genomic and proteomic analyses provide additional details about this genetic evolution?
Q: How do site-specific differences in mRNA expression affect decisions about which therapies to provide and in which order?

Source: “Histological and Molecular Analysis of a Progressive Diffuse Intrinsic Pontine Glioma and Synchronous Metastatic Lesions: A Case Report.” J. Nazarian, G.E. Mason, C.Y. Ho, E. Panditharatna, M. Kambhampati, L.G. Vezina, R.J. Packer, and E.I. Hwang. Published by Oncotarget on June 14, 2016.
researcher using ice bucket in lab

Spatial and temporal homogeneity of driver mutations in diffuse intrinsic pontine glioma

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What’s Known
Needle biopsies help to guide diagnosis and targeted therapies for diffuse intrinsic pontine gliomas (DIPGs), which make up 10 percent to 15 percent of all pediatric brain tumors but carry a median survival of 9 to 12 months. This dismal survival rate compares with a 70 percent chance of children surviving other central nervous system tumors five years post diagnosis. In DIPG, tumors appear in the pons, an area of the brain that houses cranial nerve nuclei. Surgical options are limited. Spatial and temporal tumor heterogeneity is a major obstacle to accurate diagnosis and successful targeted therapy.

What’s New
The team sought to better define DIPG heterogeneity. They analyzed 134 specimens from nine patients and found that H3K27M mutations were ubiquitous in all 41 samples with oncogenic content, and always were associated with at least one partner driver mutation: TP53, PPM1D, ACVR1 or PIK3R1. These H3K27M mutations are the initial oncogenic event in DIPG, writes the research team led by Children’s National Health System. “Driver” mutations, such as H3K27M, are essential to begin and sustain tumor formation. This main driver partnership is maintained throughout the course of the disease, in all cells across the tumor, and as tumors spread throughout the brain. Because homogeneity for main driver mutations persists for the duration of illness, efforts to cure DIPG should be directed at the oncohistone partnership, the authors write. Based on early tumor spread, efforts to cure DIPG should aim for early systemic tumor control, rather focused exclusively on the pons.

Questions for Future Research
Q: If a larger sample size were analyzed, what would it reveal about the true heterogeneity/homogeneity status of DIPGs?
Q: “Accessory” driver mutations are not absolutely essential but do help to further promote and accelerate tumor growth. What is their precise role?

Source: “Spatial and Temporal Homogeneity of Driver Mutations in Diffuse Intrinsic Pontine Glioma.” H. Nikbakht, E. Panditharatna, L.G. Mikael, R. Li, T. Gayden, M. Osmond, C.Y. Ho, M. Kambhampati, E.I. Hwang, D. Faury, A. Siu, S. Papillon-Cavanagh, D. Bechet, K.L. Ligon, B. Ellezam, W.J. Ingram, C. Stinson, A.S. Moore, K.E. Warren, J. Karamchandani, R.J. Packer, N. Jabado, J. Majewski, and J. Nazarian. Published by Nature Communications on April 6, 2016.

The role of NG2 proteoglycan in glioma

A large number of staffers contribute to the Children's National team effort to unravel the mysteries of DIPG. We photograph a few essential players in Dr. Nazarian's lab.

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What’s Known
Neuron glia antigen-2 (NG2) is a protein expressed by many central nervous system cells during development and differentiation. NG2-expressing oligodendrocyte progenitor cells have been identified as the cells of origin in gliomas, tumors that arise from the brain’s gluey supportive tissue. What’s more, NG2 expression also has been associated with childhood diffuse intrinsic pontine glioma (DIPG) an aggressive tumor that accounts for 10 percent to 20 percent of pediatric central nervous system (CNS) tumors. Radiation can prolong survival by a few months, but children diagnosed with DIPG typically survive less than one year.

What’s New
Researchers are searching for appropriate targets and effective drugs that offer some chance of benefit. A team of Children’s National Health System researchers investigated whether NG2 – which plays a critical role in proliferation and development of new blood vessels and promotes tumor infiltration – could be a potential target for cancer treatment. Of the various options, antibody-mediated mechanisms of targeting NG2 are feasible, but the size of antibodies limits their ability to cross the blood-brain barrier. “Due to its role in maintaining a pluripotent pool of tumor cells, and its role in tumor migration and infiltration, NG2 provides multiple avenues for developing therapeutics,” the research team concludes. “Moreover, the large extracellular domain of NG2 provides an excellent antigen repertoire for immunotherapeutic interventions. As such, further research is warranted to define the role and expression regulation of NG2 in CNS cancers.”

Questions for Future Research

Q: Because healthy oligodendrocyte progenitor cells are important for the child’s developing brain, how could further characterization of NG2 isoforms help prevent drugs from damaging those beneficial cells?

Q: Could NG2-binding peptides cross the blood-brain barrier to deliver anti-cancer therapies precisely to tumor sites?

Source: “The Role of NG2 Proteoglycan in Glioma.” S. Yadavilli, E.I. Hwang, R. J. Packer, and J. Nazarian. Published by Translational Oncology on February 2016.

Clinicopathology of diffuse intrinsic pontine glioma and its redefined genomic and epigenomic landscape

Dr. Nazarian's lab

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What’s Known
Fewer than 150 U.S. children per year are diagnosed with diffuse intrinsic pontine glioma (DIPG), one of the most lethal pediatric central nervous system cancers. Despite an increasing number of experimental therapies tested via clinical trials, more than 95 percent of these children die within two years of diagnosis. Molecular studies have yielded additional insight about DIPG, including that mutations in histone-encoding genes are associated with 70 percent of cases. Understanding mutations that drive tumors and the genomic landscape can help to guide development of targeted therapies.

What’s New: Frequently found genetic alterations prevalent in DIPGs

dipg-gene-mutations-and-biological-consequences

Source: “Clinicopathology of Diffuse Intrinsic Pontine Glioma and Its Redefined Genomic and Epigenomic Landscape.” E. Panditharatna, K. Yaeger, L.B. Kilburn, R.J. Packer, and J. Nazarian. Published by Cancer Genetics on May 1, 2015.