Kathleen Dorris

Prognostic significance of telomere maintenance mechanisms in pediatric high-grade gliomas

Children with high-grade glioma, including diffuse intrinsic pontine glioma (DIPG), have a poor prognosis despite multimodal therapy. Identifying novel therapeutic targets is critical to improve their outcome. We evaluated prognostic roles of telomere maintenance mechanisms in children with HGG, including DIPG. A multi-institutional retrospective study was conducted involving 50 flash-frozen HGG (35 non-brainstem; 15 DIPG) tumors from 45 children (30 non-brainstem; 15 DIPG). Telomerase activity, expression of hTERT mRNA (encoding telomerase catalytic component) and TERC (telomerase RNA template) and alternative lengthening of telomeres (ALT) mechanism were assayed. Cox Proportional Hazard regression analyses assessed association of clinical and pathological variables, TERC and hTERT levels, telomerase activity, and ALT use with progression-free or overall survival (OS). High TERC and hTERT expression was detected in 13/28 non-brainstem HGG samples as compared to non-neoplastic controls. High TERC and hTERT expression was identified in 13/15 and 11/15 DIPG samples, respectively, compared to controls. Evidence of ALT was noted in 3/11 DIPG and 10/19 non-brainstem HGG specimens. ALT and telomerase use were identified in 4/19 non-brainstem HGG and 2/11 DIPG specimens. In multivariable analyses, increased TERC and hTERT levels were associated with worse OS in patients with non-brainstem HGG, after controlling for tumor grade or resection extent. Children with HGG and DIPG, have increased hTERT and TERC expression. In children with non-brainstem HGG, increased TERC and hTERT expression levels are associated with a worse OS, making telomerase a promising potential therapeutic target in pediatric HGG.

Short-term mortality following surgical procedures for the diagnosis of pediatric brain tumors: outcome analysis in 5533 children from SEER, 2004–2011

OBJECT Thirty-day mortality is increasingly a reference metric regarding surgical outcomes. Recent data estimate a 30-day mortality rate of 1.4-2.7% after craniotomy for tumors in children. No detailed analysis of short-term mortality following a diagnostic neurosurgical procedure (e.g., resection or tissue biopsy) for tumor in the US pediatric population has been conducted. METHODS The Surveillance, Epidemiology and End Results (SEER) data sets identified patients ≤ 21 years who underwent a diagnostic neurosurgical procedure for primary intracranial tumor from 2004 to 2011. One- and two-month mortality was estimated. Standard statistical methods estimated associations between independent variables and mortality. RESULTS A total of 5533 patients met criteria for inclusion. Death occurred within the calendar month of surgery in 64 patients (1.16%) and by the conclusion of the calendar month following surgery in 95 patients (1.72%). Within the first calendar month, patients < 1 year of age (n = 318) had a risk of death of 5.66%, while those from 1 to 21 years (n = 5215) had a risk of 0.88% (p < 0.0001). By the end of the calendar month following surgery, patients < 1 year (n = 318) had a risk of death of 7.23%, while those from 1 to 21 years (n = 5215) had a risk of 1.38% (p < 0.0001). Children < 1 year at diagnosis were more likely to harbor a high-grade lesion than older children (OR 1.9, 95% CI 1.5-2.4). CONCLUSIONS In the SEER data sets, the risk of death within 30 days of a diagnostic neurosurgical procedure for a primary pediatric brain tumor is between 1.16% and 1.72%, consistent with contemporary data from European populations. The risk of mortality in infants is considerably higher, between 5.66% and 7.23%, and they harbor more aggressive lesions.

Severe allergic reactions to thiol-based cytoprotective agents mesna and amifostine in a child with a supratentorial primitive neuroectodermal tumor.

Both 2-mercaptoethane sulfonate sodium (mesna) and amifostines active metabolite WR-1065 are thiol-based cytoprotective agents that are critical components of high-dose chemotherapy regimens used to treat various cancers in both adults and children. This case report describes a patient with a supratentorial primitive neuroectodermal tumor who developed severe drug reactions to both mesna and amifostine/WR-1065, suggesting that the thiol component of these agents triggered the adverse reactions. This report highlights the clinical presentation of drug-induced hypersensitivity syndrome in the context of pediatric oncology and the supportive care measures that, if implemented rapidly, may diminish the reaction severity and allow successful completion of chemotherapy.

Atypical pediatric ganglioglioma is common and associated with a less favorable clinical course

OBJECT Ganglioglioma (GG) is commonly recognized as a low-grade tumor located in the temporal lobe, often presenting with seizures. Most are amenable to complete resection and are associated with excellent oncological outcome. The authors encountered several GGs in various locations, which seem to have a less favorable clinical course than GGs in the temporal lobe. METHODS The authors performed a single-center retrospective review of all children with a histological diagnosis of GG who were treated at Childrens Hospital Colorado between 1997 and 2013. Each tumor was categorized by 2 pediatric neuroradiologists as typical or atypical based on preoperative MRI appearance. Typical lesions were cortically based, within a single cerebral lobe, well-circumscribed, and solid or mixed solid/cystic. The treatment and clinical course of each patient was analyzed. RESULTS Thirty-seven children were identified, with a median age at presentation of 8.2 years and median follow-up of 38.0 months. Eighteen tumors (48.6%) were typical and 19 (51.4%) were atypical. All typical lesions presented with seizures, whereas no atypical lesions did so. Sixteen (88.9%) typical lesions were located in the temporal lobe. In the atypical group, tumor location was variable, including 11 (57.9%) in the brainstem. Death during follow-up was statistically more common in the atypical group (31.6% vs 0%, p = 0.02). Gross-total resection (GTR) was achieved for 15 of 16 typical tumors (93.8%), compared with 3 atypical tumors (15.8%, p < 0.0001). Presentation with seizure or non-brainstem location were each associated with survival (p = 0.02 and 0.004, respectively). The presence of mutation in BRAF exon 15 did not differ between the 2 groups. CONCLUSIONS Pediatric GG with typical imaging features is associated with excellent rates of GTR and overall survival. Atypical GG is commonly encountered, less amenable to GTR, and associated with a worse outcome. This may relate to anatomical or biological characteristics and merits further investigation.

Random‐effects meta‐analysis for systematic reviews of phase I clinical trials: Rare events and missing data

Phase I trials aim to establish appropriate clinical and statistical parameters to guide future clinical trials. With individual trials typically underpowered, systematic reviews and meta‐analysis are desired to assess the totality of evidence. A high percentage of zero or missing outcomes often complicate such efforts. We use a systematic review of pediatric phase I oncology trials as an example and illustrate the utility of advanced Bayesian analysis. Standard random‐effects methods rely on the exchangeability of individual trial effects, typically assuming that a common normal distribution sufficiently describes random variation among the trial level effects. Summary statistics of individual trial data may become undefined with zero counts, and this assumption may not be readily examined. We conduct Bayesian semi‐parametric analysis with a Dirichlet process prior and examine the assumption. The Bayesian semi‐parametric analysis is also useful for visually summarizing individual trial data. It provides alternative statistics that are computed free of distributional assumptions about the shape of the population of trial level effects. Outcomes are rarely entirely missing in clinical trials. We utilize available information and conduct Bayesian incomplete data analysis. The advanced Bayesian analyses, although illustrated with the specific example, are generally applicable.

A comparison of safety and efficacy of cytotoxic versus molecularly targeted drugs in pediatric phase I solid tumor oncology trials

Prior reviews of phase I pediatric oncology trials involving primarily cytotoxic agents have reported objective response rates (ORRs) and toxic death rates of 7.9–9.6% and 0.5%, respectively. These data may not reflect safety and efficacy in phase I trials of molecularly targeted (targeted) drugs.

Characterization of 2 Novel Ependymoma Cell Lines With Chromosome 1q Gain Derived From Posterior Fossa Tumors of Childhood

Ependymoma (EPN) is a common brain tumor of childhood that, despite standard surgery and radiation therapy, has a relapse rate of 50%. Clinical trials have been unsuccessful in improving outcome by addition of chemotherapy, and identification of novel therapeutics has been hampered by a lack of in vitro and in vivo models. We describe 2 unique EPN cell lines (811 and 928) derived from recurrent intracranial metastases. Both cell lines harbor the high-risk chromosome 1q gain (1q+) and a derivative chromosome 6, and both are classified as molecular group A according to transcriptomic analysis. Transcriptional enrichment of extracellular matrix-related genes was a common signature of corresponding primary tumors and cell lines in both monolayer and 3D formats. EPN cell lines, when cultured in 3D format, clustered closer to the primary tumors with better fidelity of EPN-specific transcripts than when grown as a monolayer. Additionally, 3D culture revealed ependymal rosette formation and cilia-related ontologies, similar to in situ tumors. Our data confirm the validity of the 811 and 928 cell lines as representative models of intracranial, posterior fossa 1q+ EPN, which holds potential to advance translational science for patients affected by this tumor.

Abstract B69: Activation of the IL6/STAT3 pathway in childhood ependymoma is associated with a pro-inflammatory tumor microenvironment and a poor prognosis

To aid development of immunotherapy for poor outcome Group A ependymoma (EPN) in children we sought to identify the molecular pathway underlying the adverse pro-inflammatory phenotype associated with this molecular subgroup. We have previously shown the importance of immunological factors in EPN outcome and that an anti-tumor immunophenotype was critical in survival whereas a pro-inflammatory phenotype was associated with a poor outcome. Moreover we showed a strong correlation between these immunophenotypes and the newly recognized molecular subgroups of posterior fossa EPN. We showed that Group A EPN have an adverse pro-inflammatory immunophenotype at presentation which adversely affects outcome even at relapse. We contrasted the gene expression profiles of patient tumor samples from Group A EPN to the more clinically favorable Group B EPN, as well as a broader panel of pediatric and adult brain tumors and normal brain, to identify potential molecular pathways that might be associated with the Group A immunophenotype. The results of these studies were validated using functional assays in short-term cultures of patient tumor samples and novel EPN cell lines. Strikingly we found a robust expression signature implicating the interleukin-6/signal transduced and activator of transcription 3 (IL6/STAT3) pathway in the Group A tumors. Comparison of transcriptomic profiles of EPN Group A (n=17) and Group B (n=20) demonstrated significant overexpression both IL6 (19.7-fold) and STAT3 (1.6 fold) in Group A. High overexpression of STAT3 driven genes IL8 (30-fold), SOCS3 (14-fold) and BIRC3 (8.5-fold) provided additional proof of IL6/STAT3 pathway activation in Group A. Furthermore, IL6 and IL8 gene expression was shown to be significantly higher (FDR To conclude: The IL6/STAT3 pathway is active in Group A EPN and is important in maintaining tumor growth in a pro-inflammatory microenvironment. Effective design of Group A-targeted immunotherapy for children with EPN may require alleviation of this potentially immunosuppressive pathway. Citation Format: Andrea Griesinger, Andrew M. Donson, Diane Birks, Vladimir Amani, Rebecca Josephson, Kathleen Dorris, Philip Reigan, Michael Handler, Nicholas Foreman. Activation of the IL6/STAT3 pathway in childhood ependymoma is associated with a pro-inflammatory tumor microenvironment and a poor prognosis. [abstract]. In: Proceedings of the AACR Special Conference: Tumor Immunology and Immunotherapy: A New Chapter; December 1-4, 2014; Orlando, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2015;3(10 Suppl):Abstract nr B69.

Abstract B18: Presence of tumor-associated macrophages in SHH medulloblastoma

The concept of tumor-promoting inflammation is a recognized enabling characteristic of cancer. Tumor associated macrophages (TAMs), one of the main contributors to the tumor microenvironment, have been identified in many adult malignancies and in the MYCN non-amplified high risk neuroblastomas. TAMs have been shown to promote cancer via multiple mechanisms including tumor cell growth and survival, invasion, metastasis, angiogenesis, inflammation, and immune regulation. Recent studies in adult gliomas have demonstrated increased expression of macrophage/microglia associated genes in subtypes of gliomas, however little is known about the role of inflammation in medulloblastomas, the most common malignant childhood brain tumor. In this study we examined the expression of inflammation-related genes and presence of TAMs in molecular subgroups of pediatric medulloblastoma. The molecular subgroups of medulloblastomas were initially identified using Human Exon Array (HuEx) microarray data from 168 samples (65 patients profiled at Children9s Hospital Los Angeles and 103 from previously published cohort) using a modified algorithm based on non-negative matrix factorization. We then examined the inflammation and immunology related genes that were differentially expressed among the molecular subgroups and discovered greater expression of inflammation-related genes in tumors of the SHH molecular subgroup compared with those of the Group 3 and Group 4 subgroups. Gene expression analysis was then performed on 83 medulloblastoma samples using a custom-built TaqMan Low Density Array (TLDA) card containing 41 tumor-related and 4 inflammation-related genes that were significantly deregulated among medulloblastoma subgroups in the HuEx microarray analyses. Thirty-one of these genes were used to develop a signature predictive of molecular subgroup. The internal cross-validted error rate of the TLDA 31-gene signature was 8%, with predominant misclassifications occurring between Groups 3 and 4. The expression levels of CD163 and CSF1R, two markers associated with TAMs, were higher in tumors of the SHH subgroup compared to those in the WNT, Group 3, and Group 4 subgroups (CD163, t-test p=.02 for WNT and p Our study reports the first evidence of the presence of TAMs in medulloblastomas and provides a novel 31-gene TLDA signature that accurately determines molecular subgroups of medulloblastomas. The increase in expression of macrophage related genes and intratumoral macrophages was strongly associated with the SHH subgroup of patients. The identification of TAMs in medulloblastomas provides opportunity for testing new therapies directed against TAMs such as CSF1R inhibitors, and the recognition of the importance of tumor microenvironment in childhood brain tumors. Citation Format: Ashley Margol, Janahan Gnanachandran, Nathan Robison, Long Hung, Rebekah Kennedy, Marzieh Vali, Girish Dhall, Jonathan Finlay, Anat Epstein, Mark Krieger, Kathleen Dorris, Maryam Fouladi, Floyd Gilles, Alexander Judkins, Richard Sposto, Shahab Asgharzadeh. Presence of tumor-associated macrophages in SHH medulloblastoma. [abstract]. In: Proceedings of the AACR Special Conference on Pediatric Cancer at the Crossroads: Translating Discovery into Improved Outcomes; Nov 3-6, 2013; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2013;74(20 Suppl):Abstract nr B18.