IL-13 receptors as possible therapeutic targets in diffuse intrinsic pontine glioma.

Diffuse intrinsic pontine glioma (DIPG) is a universally fatal childhood cancer of the brain. Despite the introduction of conventional chemotherapy and radiotherapy, improvements in survival have been marginal and long-term survivorship is uncommon. Thus, new targets for therapeutics are critically needed. Early phase clinical trials exploring molecularly-targeted therapies against the epidermal growth factor receptor (EGFR) and novel immunotherapies targeting interleukin receptor-13α2 (IL-13Rα2) have demonstrated activity in this disease. To identify additional therapeutic markers for cell surface receptors, we performed exome sequencing (16 new samples, 22 previously published samples, total 38 with 26 matched normal DNA samples), RNA deep sequencing (17 new samples, 11 previously published samples, total 28 with 18 matched normal RNA samples), and immunohistochemistry (17 DIPG tissue samples) to examine the expression of the interleukin-4 (IL-4) signaling axis components (IL-4, interleukin 13 (IL-13), and their respective receptors IL-4Rα, IL-13Rα1, and IL-13Rα2). In addition, we correlated cytokine and receptor expression with expression of the oncogenes EGFR and c-MET. In DIPG tissues, transcript-level analysis found significant expression of IL-4, IL-13, and IL-13Rα1/2, with strong differential expression of IL-13Rα1/2 in tumor versus normal brain. At the protein level, immunohistochemical studies revealed high content of IL-4 and IL-13Rα1/2 but notably low expression of IL-13. Additionally, a strong positive correlation was observed between c-Met and IL-4Rα. The genomic and transcriptional landscape across all samples was also summarized. These data create a foundation for the design of potential new immunotherapies targeting IL-13 cell surface receptors in DIPG

EGFR correlation with IL-4 signaling axis genes and correlation between IL-4 tumor and normal.

<p>EGFR correlation with IL-4 signaling axis genes and correlation between IL-4 tumor and normal.</p

Immunohistochemical studies of the IL-4R signaling axis, <i>EGFR</i> and <i>c-Met</i> protein expression.

<p>Representative immunohistochemical staining of DIPG archival cases for (A) <i>IL-4</i> (B) <i>IL-4Rα</i> (C) <i>IL-13</i> (D) <i>IL-13Rα1</i> (E) <i>IL-13Rα2</i> (F) <i>EGFR</i> (G) <i>c-Met</i>.</p

Landscape of exome mutations and differential gene expression of frequently-mutated DIPG genes and IL-4 pathway targets in DIPG samples.

<p>(A) Mutational landscape of frequently-mutated DIPG genes and IL-family genes. Exome sequencing was performed on 38 DIPG samples to identify somatic mutations and copy number variations. When possible, tumor samples were compared against matched normal samples. (B) Gene expression of frequently-mutated DIPG genes and IL-family genes. The set of genes is identical to those in Fig A. RNA sequencing was performed on 28 DIPG samples: 18 tumor samples with matched normal samples, 10 unmatched tumor samples. Average fold change and tumor vs. normal p-values were calculated across the set of expressed genes. Note that <i>IL-13Rα1</i> and <i>IL-13Rα2</i> are significantly overexpressed in tumor compared to normal, but are mutationally silent.</p

Summary of immunohistochemical staining.

<p>Summary of immunohistochemical staining.</p

The immunohistochemical, DNA methylation, and chromosomal copy number profile of cauda equina paraganglioma is distinct from extra-spinal paraganglioma.

Paragangliomas are neuroendocrine tumors of the autonomic nervous system that are variably clinically functional and have a potential for metastasis. Up to 40% occur in the setting of a hereditary syndrome, most commonly due to germline mutations in succinate dehydrogenase (SDHx) genes. Immunohistochemically, paragangliomas are characteristically GATA3-positive and cytokeratin-negative, with loss of SDHB expression in most hereditary cases. In contrast, the rare paragangliomas arising in the cauda equina (CEP) or filum terminale region have been shown to be hormonally silent, clinically indolent, and have variable keratin expression, suggesting these tumors may represent a separate pathologic entity. We retrospectively evaluated 17 CEPs from 11 male and 6 female patients with a median age of 38&nbsp;years (range 21-82), none with a family history of neuroendocrine neoplasia. Six of the 17 tumors demonstrated prominent gangliocytic or ganglioneuromatous differentiation. By immunohistochemistry, none of the CEPs showed GATA3 positivity or loss of SDHB staining; all 17 CEPs were cytokeratin positive. Genome-wide DNA methylation profiling was performed on 12 of the tumors and compared with publicly available genome-wide DNA methylation data. Clustering analysis showed that CEPs form a distinct epigenetic group, separate from paragangliomas of extraspinal sites, pheochromocytomas, and other neuroendocrine neoplasms. Copy number analysis revealed diploid genomes in the vast majority of CEPs, whereas extraspinal paragangliomas were mostly aneuploid with recurrent trisomy 1q and monosomies of 1p, 3, and 11, none of which were present in the cohort of CEP. Together, these findings indicate that CEPs likely represent a distinct entity. Future genomic studies are needed to further elucidate the molecular pathogenesis of these tumors

External validation and recalibration of an incidental meningioma prognostic model - IMPACT: protocol for an international multicentre retrospective cohort study

Introduction: Due to the increased use of CT and MRI, the prevalence of incidental findings on brain scans is increasing. Meningioma, the most common primary brain tumour, is a frequently encountered incidental finding, with an estimated prevalence of 3/1000. The management of incidental meningioma varies widely with active clinical-radiological monitoring being the most accepted method by clinicians. Duration of monitoring and time intervals for assessment, however, are not well defined. To this end, we have recently developed a statistical model of progression risk based on single-centre retrospective data. The model Incidental Meningioma: Prognostic Analysis Using Patient Comorbidity and MRI Tests (IMPACT) employs baseline clinical and imaging features to categorise the patient with an incidental meningioma into one of three risk groups: low, medium and high risk with a proposed active monitoring strategy based on the risk and temporal trajectory of progression, accounting for actuarial life expectancy. The primary aim of this study is to assess the external validity of this model. Methods and analysis: IMPACT is a retrospective multicentre study which will aim to include 1500 patients with an incidental intracranial meningioma, powered to detect a 10% progression risk. Adult patients ≥16 years diagnosed with an incidental meningioma between 1 January 2009 and 31 December 2010 will be included. Clinical and radiological data will be collected longitudinally until the patient reaches one of the study endpoints: intervention (surgery, stereotactic radiosurgery or fractionated radiotherapy), mortality or last date of follow-up. Data will be uploaded to an online Research Electronic Data Capture database with no unique identifiers. External validity of IMPACT will be tested using established statistical methods. Ethics and dissemination: Local institutional approval at each participating centre will be required. Results of the study will be reported through peer-reviewed articles and conferences and disseminated to participating centres, patients and the public using social media