Project description:With the increasing use of immunotherapy in cancer, understanding the tumor immune microenvironment (TIME) has become increasingly important. There has been great success in treatment of some pediatric high-grade gliomas with immune checkpoint inhibition, however overall, the immune microenvironment in pediatric brain tumors remains poorly understood. Accordingly, we developed a clinical immune-oncology gene expression assay and used it to profile a diverse range of pediatric brain tumors with detailed clinical and molecular annotation, including a total of 1379 cases. Our findings demonstrate the critical importance of understanding the TIME to guide the prognosis and management of pediatric brain tumors. In pediatric low-grade gliomas we identified distinct patterns of immune activation with prognostic significance in BRAF V600E mutant tumors. In pediatric high-grade gliomas, we observed elevated inflammation and T cell infiltrates in tumors that have historically been considered immune cold, as well as genomic correlates of inflammation levels. In our cohort of mismatch repair deficient high-grade gliomas treated with immune checkpoint inhibition, we found that high tumor inflammation signature was a significant predictor of treatment response. Furthermore, we demonstrated the potential for multimodal biomarkers to improve the treatment stratification of these patients. Importantly, while overall patterns of immune activation were observed for histologically and genomically defined tumor types, there was nonetheless significant variability within each diagnostic entity, indicating that the immune response must be evaluated as an independent feature. In sum, in addition to the histology and molecular profile, this work establishes the importance of assessing and reporting on the tumor immune microenvironment as an essential axis of cancer diagnosis in the era of personalized medicine.
Project description:The characteristics of immune cells infiltrating pediatric brain tumors is largely unexplored. A better understanding of these characteristics will provide a foundation for development of immunotherapy for pediatric brain tumors. Gene expression profiles were used to identify immune marker gene that are differentially expressed between various brain tumor types. Gene expression profiles were generated from surgical tumor and normal brain samples (n=130) using Affymetrix HG-U133plus2 chips (Platform GPL570). Gene expression profiles of different types of brain tumors and normal brain were filtered to obtain gene expression of key immune cell markers. Comparative analyses between different brain tumors and normal brain was used to identifiy differential immune characteristics of these tumors.
Project description:The characteristics of immune cells infiltrating pediatric brain tumors is largely unexplored. A better understanding of these characteristics will provide a foundation for development of immunotherapy for pediatric brain tumors. Gene expression profiles were used to identify immune marker gene that are differentially expressed between various brain tumor types.
Project description:Comparison of immune-infiltrated bone marrow samples (n=6) with immune-depleted bone marrow samples (n=17) of pediatric acute myeloid leukemia patients using the Nanostring PanCancer IO 360 panel.
Project description:Background<br>Primitive brain tumors are the first cause of cancer-related death in children. Tumor cells with stem-like properties (TSCs), thought to account for tumorigenesis and therapeutic resistance, have been isolated from high-grade gliomas in adults. Whether TSCs are a common component of pediatric brain tumors and are of clinical relevance remains to be determined. <br>Methodology/Principal findings<br>Tumor cells with self-renewal properties were isolated with cell biology techniques from a majority of 55 pediatric brain tumors samples, regardless of their histopathologies and grades of malignancy (57% of embryonal tumors, 57% of low-grade gliomas and neuro-glial tumors, 70% of ependymomas, 91% of high-grade gliomas). The vast majority (10/12) of high-grade glioma-derived oncospheres sustained long-term self-renewal numbers akin to neural stem cells (>7 self-renewals), whereas cells with limited renewing abilities akin to neural progenitors dominated in all other tumor types. Regardless of tumor entities, the young age group was associated with self-renewal properties akin to neural stem cells (P=0.05, chi-square test). TSCs shared a complex molecular profile combining embryonic stem cell markers with elements controlling neural stem cell properties and epithelio-mesenchymal transitions. They were radio- and chemoresistant and formed aggressive tumors after intracerebral grafting. Survival analysis of the cohort showed an association between isolation of TSCs with long-term self-renewal abilities and a patientM-^Rs higher mortality rate (P = 0.022, log-rank test). Patients bearing cells with limited self-renewal properties constituted an intermediate group of survival but which did not reach statistical significance. <br>Conclusions/Significance<br>In brain tumors affecting adult patients, TSC have been isolated only from high-grade gliomas. In contrast, our data show that tumor cells with stem cell-like or progenitor-like properties can be isolated from a wide range of histological sub-types and grades of pediatric brain tumors. They suggest that cellular mechanisms fueling tumor development differ between adult and pediatric brain tumors.<br>
Project description:Background<br>Primitive brain tumors are the first cause of cancer-related death in children. Tumor cells with stem-like properties (TSCs), thought to account for tumorigenesis and therapeutic resistance, have been isolated from high-grade gliomas in adults. Whether TSCs are a common component of pediatric brain tumors and are of clinical relevance remains to be determined. <br>Methodology/Principal findings<br>Tumor cells with self-renewal properties were isolated with cell biology techniques from a majority of 55 pediatric brain tumors samples, regardless of their histopathologies and grades of malignancy (57% of embryonal tumors, 57% of low-grade gliomas and neuro-glial tumors, 70% of ependymomas, 91% of high-grade gliomas). The vast majority (10/12) of high-grade glioma-derived oncospheres sustained long-term self-renewal numbers akin to neural stem cells (>7 self-renewals), whereas cells with limited renewing abilities akin to neural progenitors dominated in all other tumor types. Regardless of tumor entities, the young age group was associated with self-renewal properties akin to neural stem cells (P=0.05, chi-square test). TSCs shared a complex molecular profile combining embryonic stem cell markers with elements controlling neural stem cell properties and epithelio-mesenchymal transitions. They were radio- and chemoresistant and formed aggressive tumors after intracerebral grafting. Survival analysis of the cohort showed an association between isolation of TSCs with long-term self-renewal abilities and a patients higher mortality rate (P = 0.022, log-rank test). Patients bearing cells with limited self-renewal properties constituted an intermediate group of survival but which did not reach statistical significance. <br>Conclusions/Significance<br>In brain tumors affecting adult patients, TSC have been isolated only from high-grade gliomas. In contrast, our data show that tumor cells with stem cell-like or progenitor-like properties can be isolated from a wide range of histological sub-types and grades of pediatric brain tumors. They suggest that cellular mechanisms fueling tumor development differ between adult and pediatric brain tumors.<br>
Project description:Brain tumors are the leading cause of cancer-related death in children. Experimental in vitro models that faithfully capture the hallmarks and tumor heterogeneity of pediatric brain cancer are limited and hard to establish. We present a protocol that enables efficient generation, expansion and biobanking of pediatric brain cancer organoids. Utilizing our protocol, we have established patient-derived organoids (PDOs) from ependymomas, medulloblastomas, low-grade glial tumors and patient-derived xenograft organoids (PDXOs) from medulloblastoma xenografts. PDOs and PDXOs recapitulate histological features, DNA methylation profiles and intratumor heterogeneity of the tumors from which they were derived. We also showed that PDOs can be xenografted. Most interestingly, when subjected to the same routinely applied therapeutic regimens, PDOs respond similarly to the patients. Taken together, our study highlights the potential of PDOs and PDXOs for research and translational applications for personalized medicine.
Project description:Neoantigen discovery in pediatric brain tumors is hampered by their low mutational burden and scant tissue availability. We developed a low-input proteogenomic approach combining tumor DNA/RNA sequencing and mass spectrometry proteomics to identify tumor-restricted (neoantigen) peptides arising from multiple genomic aberrations to generate a highly target-specific, autologous, personalized T cell immunotherapy. Our data indicate that novel splice junctions are the primary source of neoantigens in medulloblastoma, a common pediatric brain tumor. Proteogenomically identified tumor-specific peptides are immunogenic and generate MHC II-based T cell responses. Moreover, polyclonal and polyfunctional T cells specific for tumor-specific peptides effectively eliminated tumor cells in vitro. Targeting novel tumor-specific antigens obviates the issue of central immune tolerance while potentially providing a safety margin favoring combination with other immune-activating therapies. These findings demonstrate the proteogenomic discovery of immunogenic tumor-specific peptides and lay the groundwork for personalized targeted T cell therapies for children with brain tumors.
Project description:Epigenetics tightly regulates gene expression during brain development, which ensemble distinct cell types and form complicated functional brain organ. DNA methylation is an important mark which undergo dramatically changes during brain development. The disturb of this process will lead to various brain tumors. To study the concordant DNA methylation changes during normal brain development, we sequenced DNA methylome of pediatric brain tissues from autopsy with various ages. We systematically compared the DNA methylome of pediatric brain and adult brain and identified candidate DMRs that contribute to normal brain development. This comprehensive analysis will provide important epigenetic reference for human brain development which will be a valuable data to study the epigenetic mechanism of pediatric brain tumor.