Search

Glioblastomas (GBMs) in patients harboring somatic or germinal mutations of mismatch-repair (MMR) genes exhibit a hypermutable phenotype. Here, we describe a GBM patient with increased tumor mutational burden and germline MMR mutations, treated using anti-PD1 therapy. A woman with newly diagnosed GBM (nGBM) was treated by surgery, radiotherapy, and temozolomide. The tumor recurred after 13 months leading to a second surgery and treatment with nivolumab. Whole-exome sequencing was performed on the nGBM, recurrent GBM (rGBM), and blood. Immune infiltration was investigated by immunohistochemistry and the immune response in the blood during treatment was analyzed by flow cytometry. High density of infiltrating CD163 + cells was found in both GBM specimens. Large numbers of CD3 + and CD8 + T cells were homogeneously distributed in the nGBM. The infiltration of CD4 + T cells and a different CD8 + T cell density were observed in the rGBM. Both GBM shared 12,431 somatic mutations, with 113 substitutions specific to the nGBM and 1,683 specific to the rGBM. Germline variants included pathogenic mutation in the MSH2 (R359S) gene, suggesting the diagnosis of Lynch syndrome. Systemic immunophenotyping revealed the generation of CD8 + T memory cells and persistent activation of CD4 + T cells. The patient is still receiving nivolumab 68 months after the second surgery. Our observations indicate that the hypermutator phenotype associated with germinal mutations of MMR genes and abundant T-cell infiltration contributes to a durable clinical benefit sustained by a persistent and robust immune response during anti-PD1 therapy.

Glioblastoma multiforme (GBM) is considered the most malignant form of primary brain tumor. Despite multimodal treatment, prognosis remains poor. Ketogenic diet (KD) has been suggested for the treatment of GBM. In this study, the syngenic, orthotopic GL261 mouse glioma model was used to evaluate the effects of KD on the metabolic responses of the tumor using 7T magnetic resonance imaging/spectroscopy. GL261 cells were injected into the caudate nucleus of mice. Following implantation, animals were fed with standard chow or underwent a KD. 18 days after initiating the diet, mice fed with KD displayed significantly higher plasmatic levels of ketone bodies and survived longer than those fed with the standard diet. Decreased concentrations of gamma-aminobutyric acid, N-Acetyl-Aspartate and N-acetylaspartylglutamate were found in tumor tissue after 9 days into the KD, while a huge increase in beta-hydroxybutyrate (bHB) was detected in tumor tissue as compared to normal brain. The accumulation of bHB in the tumor tissue in mice undergoing the KD, may suggest either elevated uptake/release of bHB by tumor cells, or the inability of tumor cells in this context to use it for mitochondrial metabolism.

The metabolism of glioblastoma (GBM), the most aggressive and lethal primary brain tumor, is flexible and adaptable to different adverse conditions, such as nutrient deprivation. Beyond glycolysis, altered lipid metabolism is implicated in GBM progression. Indeed, metabolic subtypes were recently identified based on divergent glucose and lipid metabolism. GBM is also characterized by an immunosuppressive microenvironment in which myeloid-derived suppressor cells (MDSCs) are a powerful ally of tumor cells. Increasing evidence supports the interconnection between GBM and MDSC metabolic pathways. GBM cells exert a crucial contribution to MDSC recruitment and maturation within the tumor microenvironment, where the needs of tumor-infiltrating lymphocytes (TILs) with antitumor function are completely neglected. In this review, we will discuss the unique or alternative source of energy exploited by GBM and MDSCs, exploring how deprivation of specific nutrients and accumulation of toxic byproducts can induce T-cell dysfunction. Understanding the metabolic programs of these cell components and how they impact fitness or dysfunction will be useful to improve treatment modalities, including immunotherapeutic strategies.

Background The efficacy of dendritic cell (DC) immunotherapy as a single therapeutic modality for the treatment of glioblastoma (GBM) patients remains limited. In this study, we evaluated in patients with GBM recurrence the immune-mediated effects of DC loaded with autologous tumor lysate combined with temozolomide (TMZ) or tetanus toxoid (TT). Methods In the phase I-II clinical study DENDR2, 12 patients were treated with 5 DC vaccinations combined with dose-dense TMZ. Subsequently, in eight patients, here defined as Variant (V)-DENDR2, the vaccine site was preconditioned with TT 24 hours before DC vaccination and TMZ was avoided. As a survival endpoint for these studies, we considered overall survival 9 months (OS9) after second surgery. Patients were analyzed for the generation of effector, memory, and T helper immune response. Results Four of 12 DENDR2 patients reached OS9, but all failed to show an immunological response. Five of eight V-DENDR2 patients (62%) reached OS9, and one patient is still alive (OS >30 months). A robust CD8+ T-cell activation and memory T-cell formation were observed in V-DENDR2 OS>9. Only in these patients, the vaccine-specific CD4+ T-cell activation (CD38+/HLA-DR+) was paralleled by an increase in TT-induced CD4+/CD38low/CD127high memory T cells. Only V-DENDR2 patients showed the formation of a nodule at the DC injection site infiltrated by CCL3-expressing CD4+ T cells. Conclusions TT preconditioning of the vaccine site and lack of TMZ could contribute to the efficacy of DC immunotherapy by inducing an effector response, memory, and helper T-cell generation.

Dendritic cells (DC) are the most potent antigen-presenting cells, strongly inducers of T cell-mediated immune responses and, as such, broadly used as vaccine adjuvant in experimental clinical settings. DC are widely generated from human monocytes following in vitro protocols which require 5&ndash, 7 days of differentiation with GM-CSF and IL-4 followed by 2&ndash, 3 days of activation/maturation. In attempts to shorten the vaccine&rsquo, s production, Fast-DC protocols have been developed. Here we reported a Fast-DC method in compliance with good manufacturing practices for the production of autologous mature dendritic cells loaded with antigens derived from whole tumor lysate, suitable for the immunotherapy in glioblastoma patients. The feasibility of generating Fast-DC pulsed with whole tumor lysate was assessed using a series of small-scale cultures performed in parallel with clinical grade large scale standard method preparations. Our results demonstrate that this Fast protocol is effective only in the presence of PGE2 in the maturation cocktail to guarantee that Fast-DC cells exhibit a mature phenotype and fulfill all requirements for in vivo use in immunotherapy approaches. Fast-DC generated following this protocol were equally potent to standard DC in inducing Ag-specific T cell proliferation in vitro. Generation of Fast-DC not only reduces labor, cost, and time required for in vitro clinical grade DC development, but can also minimizes inter-preparations variability and the risk of contamination.

Expression of neuron-glial antigen 2 (NG2) identifies an aggressive malignant phenotype in glioblastoma (GBM). Mouse models have implicated NG2 in the genesis, evolution, and maintenance of glial cancers and have highlighted potential interactions between NG2 and epidermal growth factor receptor (EGFR). However, it is unknown whether the lineage relationship of NG2+ and NG2- cells follows a hierarchical or stochastic mode of growth. Furthermore, the interaction between NG2 and EGFR signaling in human GBM is also unclear.Single GBM NG2+ and NG2- cells were studied longitudinally to assess lineage relationships. Short hairpin RNA knockdown of NG2 was used to assess the mechanistic role of NG2 in human GBM cells. NG2+ and NG2- cells and NG2 knockdown (NG2-KD) and wild type (NG2-WT) cells were analyzed for differential effects on EGFR signaling.Expression of NG2 endows an aggressive phenotype both at single cell and population levels. Progeny derived from single GBM NG2- or GBM NG2+ cells consistently establish phenotypic equilibrium, indicating the absence of a cellular hierarchy. NG2 knockdown reduces proliferation, and mice grafted with NG2-KD survive longer than controls. Finally, NG2 promotes EGFR signaling and is associated with EGFR expression.These data support a dynamic evolution in which a bidirectional relationship exists between GBM NG2+ and GBM NG2- cells. Such findings have implications for understanding phenotypic heterogeneity, the emergence of resistant disease, and developing novel therapeutics.

In glioma patients, high levels of glutamate can cause brain edema and seizures. GLAST, a glutamate-aspartate transporter expressed by astrocytes with a role in glutamate uptake, is highly expressed on the plasma membrane of glioblastoma (GBM) cells, and its expression significantly correlates with shortened patient survival. Here, it was demonstrated that inhibition of GLAST expression limited the progression and invasion of GBM xenografts. Magnetic resonance spectroscopy was used to measure glutamate in GLAST-expressing gliomas showing that these tumors exhibit increased glutamate concentration compared to GLAST-depleted glioma. Despite their GLAST expression, GBM stem-like cells (GSCs) released rather than taking up glutamate due to their lack of Na+/K+-ATPase. Overexpression of Na+/K+-ATPase in these cells restored glutamate uptake and induced apoptosis. The therapeutic relevance of targeting GLAST in gliomas was assessed using the inhibitor UCPH-101. In glioma-bearing mice, a single intratumoral injection of UCPH-101 significantly increased survival by decreasing GLAST expression and inducing apoptosis. Thus, GLAST has a novel role in GBM that appears to have crucial relevance in glutamate trafficking and may thus be a new therapeutic target.

Although some progress has been made in understanding GBM biology, treatment remains a challenge. There is increasing evidence that radiotherapy (RT) not only provides immunomodulatory effects on tumor microenvironment but also influences systemic immune response, supporting the advantage of combinatorial strategies with immunotherapy (IT). Using immune-competent mice in which syngeneic glioma cells are grown intracranially and treated with local fractionated radiation, we assessed the effects of RT on both local innate and adaptive immune cells. GL261-glioma bearing mice were locally irradiated with a total dose of 15 Gy in three consecutive fractions of 5 Gy on day 7, 8, and 9 after the tumor implantation. Irradiation was delivered both as exclusive (RT) and concomitant treatment in combination with dendritic cell (DC) immunotherapy (RT-IT). DCs were injected subcutaneously on day 16, 23, and 30 after tumor implantation. The potential role of RT in reprogramming the glioma-associated microglia is still poorly characterized. Microglia were isolated and enriched using CD11b microbeads from both the brain tumor hemisphere and contralateral hemisphere of RT, RT-IT, and control mice. A gene expression signature was analyzed on isolated microglia. Expression of mmp14 and trem2, involved in enhancing glioma proliferation, decreased in microglia isolated from RT mice (2.3 and 2.0-fold lower than in controls, day 16 P=0.01). The frequency of CD45dim/CD11b+/CD172A+ microglia showed an early increase at day 16 in the tumor mass and contralateral hemisphere in RT mice, but not in controls (p Citation Format: Serena Pellegatta, Natalia Di Ianni, Martina Maffezzini, Maria Luisa Fumagalli, Valentina Pinzi, Silvia Musio, Laura Fariselli, Gaetano Finocchiaro. Radiotherapy treatment in combination with Dendritic Cell Immunotherapy promotes a microglia activation and a disruption of the SIRPα-CD47 signaling axis in the GL261 glioma model [abstract]. In: Abstracts: AACR Virtual Special Conference: Tumor Immunology and Immunotherapy; 2020 Oct 19-20. Philadelphia (PA): AACR; Cancer Immunol Res 2021;9(2 Suppl):Abstract nr PO087.

Different approaches have been explored to raise effective antitumor responses against glioblastoma (GBM), the deadliest of primary brain tumors. In many clinical studies, cancer vaccines have been based on dendritic cells (DCs) loaded with peptides, representing one or more specific tumor antigens or whole lysates as a source of multiple antigens. Randomized clinical trials using DCs are ongoing, and results of efficacy are not yet available. Such strategies are feasible and safe; however, immune-suppressive microenvironment, absence of appropriate specific epitopes to target, and cancer immunoediting can limit their efficacy. The aim of this review is to describe how the definition of novel and more specific targets may increase considerably the possibility of successful DC immunotherapy. By proposing to target glioblastoma stem-like cells (GSCs), the immune response will be pointed to eradicating factors and pathways highly relevant to GBM biology. Preclinical observations on efficacy, and preliminary results of immunotherapy trials, encourage exploring the clinical efficacy of DC immunotherapy in GBM patients using high-purity, GSC-loaded DC vaccines.

Glioblastoma (GBM) is a lethal tumor that displays remarkable genetic heterogeneity. It is also known that GBM contains a cell hierarchy driven by GBM stem-like cells (GSCs), responsible for tumor generation, therapeutic resistance, and relapse. An important and still open issue is whether phylogenetically related GSCs can be found in matched primary and recurrent GBMs, and reflect tumor genetic evolution under therapeutic pressure. To address this, we analyzed the mutational profile of GSCs isolated from either human primary GBMs (primary GSCs) or their matched tumors recurring after surgery and chemoradiotherapy (recurrent GSCs). We found that recurrent GSCs can accumulate temozolomide-related mutations over primary GSCs, following both linear and branched patterns. In the latter case, primary and recurrent GSCs share a common set of lesions, but also harbor distinctive mutations indicating that primary and recurrent GSCs derive from a putative common ancestor GSC by divergent genetic evolution. Interestingly, TP53 mutations distinctive of recurrent GSCs were detectable at low frequency in the corresponding primary tumors and likely marked pre-existent subclones that evolved under therapeutic pressure and expanded in the relapsing tumor. Consistently, recurrent GSCs displayed in vitro greater therapeutic resistance than primary GSCs. Overall, these data indicate that (a) phylogenetically related GSCs are found in matched primary and recurrent GBMs and (b) recurrent GSCs likely pre-exist in the untreated primary tumor and are both mutagenized and positively selected by chemoradiotherapy.

Glioblastoma is a highly heterogeneous aggressive primary brain tumor, with the glioma stem‐like cells (GSC) being more sensitive to cytotoxic lymphocyte‐mediated killing than glioma differentiated cells (GDC). However, the mechanism behind this higher sensitivity is unclear. Here, we found that the mitochondrial morphology of GSCs modulates the ER–mitochondria contacts that regulate the surface expression of sialylated glycans and their recognition by cytotoxic T lymphocytes and natural killer cells. GSCs displayed diminished ER–mitochondria contacts compared to GDCs. Forced ER–mitochondria contacts in GSCs increased their cell surface expression of sialylated glycans and reduced their susceptibility to cytotoxic lymphocytes. Therefore, mitochondrial morphology and dynamism dictate the ER–mitochondria contacts in order to regulate the surface expression of certain glycans and thus play a role in GSC recognition and elimination by immune effector cells. Targeting the mitochondrial morphology, dynamism, and contacts with the ER could be an innovative strategy to deplete the cancer stem cell compartment to successfully treat glioblastoma.

Glioblastoma is one of the most challenging forms of cancer to treat. Here we describe a computational platform that integrates the analysis of copy number variations and somatic mutations and unravels the landscape of in-frame gene fusions in glioblastoma. We found mutations with loss of heterozygosity in LZTR1, encoding an adaptor of CUL3-containing E3 ligase complexes. Mutations and deletions disrupt LZTR1 function, which restrains the self renewal and growth of glioma spheres that retain stem cell features. Loss-of-function mutations in CTNND2 target a neural-specific gene and are associated with the transformation of glioma cells along the very aggressive mesenchymal phenotype. We also report recurrent translocations that fuse the coding sequence of EGFR to several partners, with EGFR-SEPT14 being the most frequent functional gene fusion in human glioblastoma. EGFR-SEPT14 fusions activate STAT3 signaling and confer mitogen independence and sensitivity to EGFR inhibition. These results provide insights into the pathogenesis of glioblastoma and highlight new targets for therapeutic intervention. © 2013 Nature America, Inc. All rights reserved.

MYC deregulation is common in human cancer and has a role in sustaining the aggressive cancer stem cell populations. MYC mediates a broad transcriptional response controlling normal biological programmes, but its activity is not clearly understood. We address MYC function in cancer stem cells through the inducible expression of Omomyc—a MYC‐derived polypeptide interfering with MYC activity—taking as model the most lethal brain tumour, glioblastoma. Omomyc bridles the key cancer stemlike cell features and affects the tumour microenvironment, inhibiting angiogenesis. This occurs because Omomyc interferes with proper MYC localization and itself associates with the genome, with a preference for sites occupied by MYC. This is accompanied by selective repression of master transcription factors for glioblastoma stemlike cell identity such as OLIG2, POU3F2, SOX2, upregulation of effectors of tumour suppression and differentiation such as ID4, MIAT, PTEN, and modulation of the expression of microRNAs that target molecules implicated in glioblastoma growth and invasion such as EGFR and ZEB1. Data support a novel view of MYC as a network stabilizer that strengthens the regulatory nodes of gene expression networks controlling cell phenotype and highlight Omomyc as model molecule for targeting cancer stem cells.

Malignant gliomas are aggressive brain tumours with very poor prognosis. The majority of glioma cells are differentiated (glioma-differentiated cells: GDCs), whereas the smaller population (glioma-initiating cells, GICs) is undifferentiated and resistant to conventional therapies. Therefore, to better target this pool of heterogeneous cells, a combination of diverse therapeutic approaches is envisaged. Here we investigated whether the immunosensitising properties of the hypomethylating agent decitabine can be extended to GICs. Using the murine GL261 cell line, we demonstrate that decitabine augments the expression of the death receptor FAS both on GDCs and GICs. Interestingly, it had a higher impact on GICs and correlated with an enhanced sensitivity to FASL-mediated cell death. Moreover, the expression of other critical molecules involved in cognate recognition by cytotoxic T lymphocytes, MHCI and ICAM-1, was upregulated by decitabine treatment. Consequently, T-cell mediated killing of both GDCs and GICs was enhanced, as was T cell proliferation after reactivation. Overall, although GICs are described to resist classical therapies, our study shows that hypomethylating agents have the potential to enhance glioma cell recognition and subsequent destruction by immune cells, regardless of their differentiation status. These results support the development of combinatorial treatment modalities including epigenetic modulation together with immunotherapy in order to treat heterogenous malignancies such as glioblastoma.

Oncogenic TACC-tics Human cancers exhibit many types of genomic rearrangements—including some that juxtapose sequences from two unrelated genes—thereby creating fusion proteins with oncogenic activity. Functional analysis of these fusion genes can provide mechanistic insights into tumorigenesis and potentially lead to effective drugs, as famously illustrated by the BCR-ABL gene in chronic myelogenous leukemia. Singh et al. (p. 1231 , published online 26 July) identify and characterize a fusion gene present in 3% of human glioblastomas, a deadly brain cancer. In the resultant fusion protein, the tyrosine kinase region of the fibroblast growth factor receptor (FGFR) is joined to a domain from a transforming acidic coiled-coil (TACC) protein. The TACC-FGFR protein is oncogenic, shows unregulated kinase activity, localizes to the mitotic spindle, and disrupts chromosome segregation. In mice, FGFR inhibitors slowed the growth of tumors driven by the TACC-FGFR gene, suggesting that a subset of glioblastoma patients may benefit from these types of drugs.

// Maria Carmela Speranza 1,3 , Veronique Frattini 1,3 , Federica Pisati 1,3 , Dimos Kapetis 2 , Paola Porrati 1 , Marica Eoli 1 , Serena Pellegatta 1,3 , and Gaetano Finocchiaro 1,3 1 Unit of Molecular Neuro-Oncology, Fondazione I.R.C.C.S. Istituto Neurologico C. Besta, Milan, Italy 2 Bioinformatics, Fondazione I.R.C.C.S. Istituto Neurologico C. Besta, Milan, Italy 3 Dept Experimental Oncology, Campus IFOM-IEO, Milan, Italy Correspondence: Gaetano Finocchiaro, email: // Keywords : miR-145, NEDD9, invasion, progression, glioma, glioblastoma Received : July 31, 2012, Accepted : August 04, 2012, Published : August 05, 2012 Abstract miR-145 is an important repressor of pluripotency in embryonic stem cells and a tumor suppressor in different cancers. Here, we found that miR-145 is strongly down-regulated in glioblastoma (GB) specimens and corresponding glioblastoma-neurospheres (GB-NS, containing GB stem-like cells) compared to normal brain (NB) and to low-grade gliomas (LGG). We observed a direct correlation between miR-145 expression and the progression-free survival (PFS) in LGG patients and overall survival (OS) in GB patients. Using microarray analysis, we identified relevant differences in gene expression profiles between GB-NS over-expressing miR-145 (miRover-NS) and GB-NS Empty (Empty-NS). We focused our attention on HEF1/Cas-L/NEDD9, a scaffold protein involved in invasion in several types of cancer. We confirmed a significant down-regulation of NEDD9 in miRover-NS and we found a higher expression in GB and GB-NS compared to NB. Approximately 50% of LGG patients expressed higher levels of NEDD9 than NB, and the PFS of such patients was shorter than in patients expressing lower levels of NEDD9. We observed that intracranial injection of GB-NS over-expressing miR-145 delays significantly tumor development :deriving tumors showed a significant down-regulation of NEDD9. In addition, we demonstrated a significant inhibition of invasion in silencing experiments with GB-NS shNEDD9 (shNEDD9), and an up-regulation of miR-145 in shNEDD9, suggesting a double-negative feedback loop between miR-145 and NEDD9. Our results demonstrate the critical role of miR-145 and NEDD9 in regulating glioblastoma invasion and suggest a potential role of NEDD9 as a biomarker for glioma progression.

A number of studies in murine models have suggested that the immune system may edit different tumors by forcing their expression profiles so that they escape immune reactions and proliferate. Glioblastoma (GB), the most frequent and aggressive primary brain tumor, provides a good example of this, thanks to the production of numerous immunosuppressive molecules (with TGF-β being of paramount importance), downregulation of the MHC complex and deregulation of the potential for antigen presentation by the surrounding microglia. Given that surgery, radiotherapy and chemotherapy with available protocols have limited effects on the survival of GB patients, different immunotherapy strategies have been developed, based on the use of dendritic cells, antibodies and peptide vaccination. Presently, bevacizumab, a humanized anti-VEGF antibody, provides the most successful example for immune-based treatment of GB, however, its action is limited in time, as the often tumor relapses due to still undefined immunoediting mechanisms. Altered function of EGF receptor-driven pathways is common in GB and is most frequently due to the presence of a deleted form named EGFRvIII, providing a unique cancer epitope that has been targeted by immunotherapy. A recent trial of GB immunotherapy based on vaccination with the EGFRvIII peptide has shown clinical benefit: interestingly most GBs at relapse were negative for EGFRvIII expression, a relevant, direct example of cancer immunoediting. Investigations on the mechanisms of GB immunoediting will lead to an increased understanding of the biology of this malignancy and hopefully provide novel therapeutic targets.

Meningiomas are the most frequent intracranial tumors. Surgery can be curative, but recurrences are possible. We performed gene expression analyses and loss of heterozygosity (LOH) studies looking for new markers predicting the recurrence risk. We analyzed expression profiles of 23 meningiomas (10 grade I, 10 grade II, and 3 grade III) and validated the data using quantitative polymerase chain reaction (qPCR). We performed LOH analysis on 40 meningiomas, investigating chromosomal regions on 1p, 9p, 10q, 14q, and 22q. We found 233 and 268 probe sets to be significantly down- and upregulated, respectively, in grade II or III meningiomas. Genes downregulated in high-grade meningiomas were overrepresented on chromosomes 1, 6, 9, 10, and 14. Based on functional enrichment analysis, we selected LIM domain and actin binding 1 (LIMA1), tissue inhibitor of metalloproteinases 3 (TIMP3), cyclin-dependent kinases regulatory subunit 2 (CKS2), leptin receptor (LEPR), and baculoviral inhibitor of apoptosis repeat-containing 5 (BIRC5) for validation using qPCR and confirmed their differential expression in the two groups of tumors. We calculated ΔCt values of CKS2 and LEPR and found that their differential expression (C-L index) was significantly higher in grade I than in grade II or III meningiomas (p < .0001). Interestingly, the C-L index of nine grade I meningiomas from patients who relapsed in

IL-17A, produced by Th17 cells, may play a dual role in antitumor immunity. Using the GL261-glioma model, we investigated the effects of Th17 cells on tumor growth and microenvironment. Th17 cells infiltrate mouse gliomas, increase significantly in a time-dependent manner similarly to Treg and do not express Foxp3. To characterize the direct effects of Th17 cells on GL261 murine gliomas and on tumor microenvironment, we isolated IL-17-producing cells enriched from splenocytes derived from naive (nTh17) or glioma-bearing mice (gTh17) and pre-stimulated in vitro with or without TGF-β. Spleen-derived Th17 cells co-expressing IL-17, IFN-γ and IL-10, but not Treg marker Foxp3, were co-injected intracranially with GL261 in immune-competent mice. Mice co-injected with GL261 and nTh17 survived significantly longer than gTh17 (P

F. Orzan, S. Pellegatta, P. L. Poliani, F. Pisati, V. Caldera, F. Menghi, D. Kapetis, C. Marras, D. Schiffer and G. Finocchiaro (2011) Neuropathology and Applied Neurobiology37, 381–394 Enhancer of Zeste 2 (EZH2) is up-regulated in malignant gliomas and in glioma stem-like cells Aims: Proteins of the Polycomb repressive complex 2 (PRC2) are epigenetic gene silencers and are involved in tumour development. Their oncogenic function might be associated with their role in stem cell maintenance. The histone methyltransferase Enhancer of Zeste 2 (EZH2) is a key member of PRC2 function: we have investigated its expression and function in gliomas. Methods:EZH2 expression was studied in grade II–IV gliomas and in glioma stem-like cells (GSC) by quantitative PCR and immunohistochemistry. Effects of EZH2 down-regulation were analysed by treating GSC with the histone deacetylase (HDAC) inhibitor suberoylanide hydroxamic acid (SAHA) and by shRNA. Results: DNA microarray analysis showed that EZH2 is highly expressed in murine and human GSC. Real-time PCR on gliomas of different grade (n = 66) indicated that EZH2 is more expressed in glioblastoma multiforme (GBM) than in low-grade gliomas (P = 0.0013). This was confirmed by immunohistochemistry on an independent set of 106 gliomas. Treatment with SAHA caused significant up-regulation of PRC2 predicted target genes, GSC disruption and decreased expression of EZH2 and of the stem cell marker CD133. Inhibition of EZH2 expression by shRNA was associated with a significant decrease of glioma proliferation. Conclusion: The data suggest that EZH2 plays a role in glioma progression and encourage the therapeutic targeting of these malignancies by HDAC inhibitors.

e14053Background: Recurrent glioblastoma (GBM) are highly aggressive tumors allowing 6-8 month survival. Recent data suggested that tetanus/ diphtheria toxoid (Td) preconditioning could increase de...

The R132H mutation of cytosolic isocitrate dehydrogenase (IDH1) is present in the majority of low grade gliomas. Immunotherapy in these tumors has an interesting, still unexploited, therapeutic potential, as they are less immunosuppressive than glioblastomas. Using site-directed mutagenesis we introduced the R132H mutation into the murine glioma cell line GL261, creating mIDH1-GL261. Presence of the mutation was confirmed by immunoblotting and production of the oncometabolite 2-hydroxyglutarate (2HG), demonstrated by mass spectrometry (LC-MS/MS) performed on cell supernatant. In vitro mIDH1-GL261 had different morphology but similar growth rate than parental GL261 (p-GL261). After intracranial injection, MRI suggested that the initial growth rate was slower in mIDH1-GL261 than p-GL261 gliomas but overall survival was similar. mIDH1-GL261 gliomas showed evidence of R132H expression and of intratumoral 2HG production (evaluated by MRS and LC-MS/MS). Immunizations were performed nine days after intracranial implantation of mIDH1- or p-GL261 cells by three subcutaneous injections of five different peptides encompassing the IDH1 mutation site, all emulsified with Montanide ISA-51, in association with GM-CSF. Control mice were injected with four ovalbumin peptides or vehicle. Mice with mIDH1-GL261 but not p-GL261 gliomas treated with mIDH1 peptides survived longer than controls; 25% of them were cured. Immunized mice showed higher amounts of peripheral CD8+ T cells, higher production of IFN-γ, and evidence of anti-mIDH1 antibodies. Immunizations led to intratumoral up-regulation of IFN-γ, granzyme-b and perforin-1 and down-regulation of TGF-β2 and IL-10. These results support the translational potential of immunotherapeutic targeting of gliomas carrying IDH1 mutations. Electronic supplementary material The online version of this article (doi:10.1186/s40478-014-0180-0) contains supplementary material, which is available to authorized users.

Stem cells of different origin are under careful scrutiny as potential new tools for the treatment of several neurological diseases. The major focus of these reaserches have been neurodegenerative disorders, such as Huntington Chorea or Parkinson Disease (Shihabuddin et al., 1999). More recently attention has been devoted to their use for brain repair after stroke (Savitz et al., 2002). In this review we will focus on the potential of stem cell treatments for glioblastoma multiforme (Holland, 2000), the most aggressive primary brain tumor, and globoid cell leukodystrophy (Krabbe disease), a metabolic disorder of the white matter (Berger et al., 2001). These two diseases may offer a paradigm of what the stem cell approach may offer in term of treatment, alone or in combination with other therapeutic approaches. Two kinds of stem cells will be consideredhere: neural stem cells and hematopoietic stem cells, both obtained after birth. The review will focus on experimental models, with an eye on clinical perspectives.

2065 Background: The MRI follow –up of patients affected by glioblastoma (GBM) and treated with immunotherapy may be difficult, as immune responses may mimic tumor progression. To explore the potential contribution of quantitative MRI to the identification of patients with clinical benefit benefit, we used advanced MRI to study GBM patients treated with dendritic cell (DC) immunotherapy added to standard treatment (surgery, radiotherapy with concomitant temozolomide (TMZ) followed by adjuvant TMZ; DENDR1 trial, EUDRACT N° 2008-005035-15). Methods: A retrospective analysis was performed on longitudinal MRIs obtained soon after radiotherapy, within two days before the first vaccination (basal MRI) and every two months, in 22 patients enrolled in DENDR1. The following parameters were collected: tumor volume of contrast–enhanced lesions, mean rCBV, maximal rCBV, mean ADC, minimal ADC, ADC skewness. Receiver Operating Characteristic (ROC) curves were used to determine optimal sensitivity and specificity in differentiating patients as responder or not responder. Association with PFS (as per RANO criteria) and OS was analyzed using log-rank test and Cox regression. Results: Ten patients with PFS > 12 months were defined as responders Their basal mean ADC was significantly higher than in non responders (1.34 ± 0.17 vs 1.14 ± 0.34, p = 0.03). After four DC vaccinations mean ADC significantly decreased in responders only from 1.34 ± 0.17 to 1.23 ±0.23 (p = 0.028); the decrease persisted during immunotherapy. A basal mean ADC value ≥ 1.07 and a decrease in mean ADC value ≥ 0.13 were significant predictors of longer PFS (15.4 vs 9 m p = 0.0006; 17.2 vs 10.2 p = 0.04) and OS (29 vs 12.5 mo p = 0.002; 33 vs 19.9 p = 0.04 No significant correlations between the other parameters and the outcome were observed. Conclusions: Association with prolonged survival may suggest that in DENDR1responders decreased ADC is partly contributed by immune cells infiltrating the tumor.

The stem cell–determining transcription factor Sox2 is required for the maintenance of normal neural stem cells. In this study, we investigated the requirement for Sox2 in neural cancer stem-like cells using a conditional genetic deletion mutant in a mouse model of platelet-derived growth factor–induced malignant oligodendroglioma. Transplanting wild-type oligodendroglioma cells into the brain generated lethal tumors, but mice transplanted with Sox2-deleted cells remained free of tumors. Loss of the tumor-initiating ability of Sox2-deleted cells was reversed by lentiviral-mediated expression of Sox2. In cell culture, Sox2-deleted tumor cells were highly sensitive to differentiation stimuli, displaying impaired proliferation, increased cell death, and aberrant differentiation. Gene expression analysis revealed an early transcriptional response to Sox2 loss. The observed requirement of oligodendroglioma stem cells for Sox2 suggested its relevance as a target for therapy. In support of this possibility, an immunotherapeutic approach based on immunization of mice with SOX2 peptides delayed tumor development and prolonged survival. Taken together, our results showed that Sox2 is essential for tumor initiation by mouse oligodendroglioma cells, and they illustrated a Sox2-directed strategy of immunotherapy to eradicate tumor-initiating cells. Cancer Res; 74(6); 1833–44. ©2014 AACR.

Chimeric Antigen Receptor-redirected T cells (CAR-Ts) remain challenging for the treatment of glioblastoma (GBM) due to the heterogeneous expression of targetable antigens, which leads to antigen-loss variants. In addition, the emerging role of the GBM-derived neurospheres (GBM-NS) as a critical cell subset in causing GBM recurrence highlights the needs for targeting these cells to achieve sustained responses. By exploiting a well-established culture system, we generated and expanded GBM-NS from 23 surgical samples, and tested using flow cytometry the expression of CSPG4, an antigen found to be overexpressed in GBM by mRNA profiling. We observed that 70% of GBM-NS displayed high expression of CSPG4 (71 to 99%), 17% moderate-high expression (51-70%), and 13% moderate-low expression (less than 50%). Based on these results, we hypothesized that CAR-Ts specific for the CSPG4 antigen would represent a broadly applicable strategy for the treatment of GBM. We generated CSPG4.CAR-Ts, encoding the 4-1BB endodomain, from six healthy donors. CSPG4.CAR-Ts efficiently eliminated 19 different GBM-NS, showing high to moderate-low expression of CSPG4, in co-culture experiments at the E:T ratios ranging from 2:5 to 1:5 (0.2±0.5% and 0.6±0.9% residual GBM-NS, respectively). By contrast, GBM-NS continued to grow in the presence of control T cells (60.7±17.6% residual GBM-NS). CSPG4.CAR-Ts, but not control T cells, also rapidly proliferated in response to GBM-NS as evaluated by the CFSE assay. CSPG4.CAR-Ts showed a Th1 cytokine profile in response to GBM-NS, releasing significantly more IFN-γ (3593.8±1718.1 pg/ml/2×10⁁5 cells) and IL-2 (258.8±153.3 pg/ml/2×10⁁5 cells) than control T cells (1.8±2.5 and 0.9±1.2 pg/ml/2×10⁁5 cells, respectively). For the in vivo experiments we compared CSPG4.CAR-Ts encoding three different co-stimulatory domains, specifically CD28, 4-1BB, and CD28-4-1BB and used CAR.CD19-Ts as negative control. Two different GBM-NS with moderate-low and high expression of CSPG4 were selected and transduced to express the FFluciferase gene to monitor the tumor growth by in vivo bioluminescence imaging. Both GBM-NS and CAR-Ts were intracranially injected in 5 wks old female nude mice. CSPG4.CAR-Ts were efficient in controlling tumor growth of both moderate and high CSPG4-expressing GBM-NS. In all CAR treated mice, we observed an early eradication of the tumor mass from high-CSPG4 expressing GBM-NS, and a significant improved survival in mice bearing moderate CSPG4-expressing GBM-NS. CAR-Ts encoding the 4-1BB were significantly more efficient than those encoding CD28 or CD28-4-1BB in prolonging survival (p = 0.04). Our data suggest that CSPG4 is a promising target for CAR-Ts in GBM and opens the path for pursuing this approach in the clinical setting. Citation Format: Serena Pellegatta, Barbara Savoldo, Chuang Su, Ferrone Soldano, Gaetano Finocchiaro, Dotti Gianpietro. Condroitin sulfate proteoglycan 4 (CSPG4)- redirected T cells eliminate glioblastoma-derived neurospheres. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr LB-249.

2039Background: In the two stage phase I-II study DENDR-I, 24 patients with first diagnosis of glioblastoma (GBM) were treated with DC immunotherapy associated to standard radio-chemotherapy. To go...

Glioblastoma multiforme (GBM) is among the most deadly cancers. A number of studies suggest that a fraction of tumor cells with stem cell features (Glioma Stem-like Cells, GSC) might be responsible for GBM recurrence and aggressiveness. GSC similarly to normal neural stem cells, can form neurospheres (NS) in vitro, and seem to mirror the genetic features of the original tumor better than glioma cells growing adherently in the presence of serum. Using cDNA microarray analysis we identified a number of relevant genes for glioma biology that are differentially expressed in adherent cells and neurospheres derived from the same tumor. Fatty acid-binding protein 7 (FABP7) was identified as one of the most highly expressed genes in NS compared to their adherent counterpart. We found that down-regulation of FABP7 expression in NS by small interfering RNAs significantly reduced cell proliferation and migration. We also evaluated the potential involvement of FABP7 in response to radiotherapy, as this treatment may cause increased tumor infiltration. Migration of irradiated NS was associated to increased expression of FABP7. In agreement with this, in vivo reduced tumorigenicity of GBM cells with down-regulated expression of FABP7 was associated to decreased expression of the migration marker doublecortin. Notably, we observed that PPAR antagonists affect FABP7 expression and decrease the migration capability of NS after irradiation. As a whole, the data emphasize the role of FABP7 expression in GBM migration and provide translational hints on the timing of treatment with anti-FABP7 agents like PPAR antagonists during GBM evolution.

During recent years different approaches have been explored to raise effective antitumor responses against brain tumors and particularly glioblastomas (GBMs). In most cases, cancer vaccines were based on autologous dendritic cells loaded with GBM peptides or whole tumor lysates. Many phase I-II studies showed that such strategy is feasible and nontoxic but failed to provide convincing evidence of its efficacy. This was due to study design and other biological issues: local immune suppression and insufficient characterization of appropriate epitopes appear as particularly relevant.In neuro-oncology intriguing data have been obtained by vaccinating patients with the epidermal growth factor receptor variant III (EGFRvIII) peptide, reproducing a specific epitope arising because of large deletion of the EGFR gene. In other cancers immunotherapy is obtaining clinically meaningful results: in prostate cancer vaccination with dendritic cells loaded with a cancer peptide, and in metastatic melanoma antibodies against an immune gate-keeper, CTL4, both led to increased survival and have been approved by FDA.On the basis of these and other clinical and preclinical findings it appears that several approaches may have chances of clinical success. They include combinatorial treatments of chemotherapy and immunotherapy, systemic and local immunotherapy, vaccination against specific targets, for example cytomegalovirus protein or stem cell markers re-expressed during brain cancer progression.

Pilot data showed that adding intratumoral (IT) injection of dendritic cells (DCs) prolongs survival of patients affected by glioblastoma multiforme (GBM) treated by subcutaneous (SC) delivery of DCs. Using a murine model resembling GBM, we investigated the immunological mechanisms underlying this effect. C57BL6/N mice received brain injections of GL261 glioma cells. Seven days later, mice were treated by 3 SC injections of DCs with or without 1 IT injection of DCs. DC maturation, induced by pulsing with GL261 lysates, was necessary to develop effective immune responses. IT injection of pulsed (pDC), but not unpulsed DCs (uDC), increased significantly the survival, either per se or in combination with SC-pDC (P.001 vs controls). Mice treated by IT-pDC plus SC-pDC survived longer than mice treated by SC-pDC only (P = .03). Injected pDC were detectable in tumor parenchyma, but not in cervical lymph nodes. In gliomas injected with IT-pDC, CD8+ cells were significantly more abundant and Foxp3+ cells were significantly less abundant than in other groups. Using real-time polymerase chain reaction, we also found enhanced expression of IFN-gamma and TNF-alpha and decreased expression of transforming growth factor-beta (TGF-beta) and Foxp3 in mice treated with SC-pDC and IT-pDC. In vitro, pDC produced more TNF-alpha than uDC: addition of TNF-alpha to the medium decreased the proliferation of glioma cells. Overall, the results suggest that IT-pDC potentiates the anti-tumor immune response elicited by SC-pDC by pro-immune modulation of cytokines in the tumor microenvironment, decrease of Treg cells, and direct inhibition of tumor proliferation by TNF-alpha.

Abcc3, a member of the ATP-binding cassette transporter superfamily, plays a role in multidrug resistance. Here, we found that Abcc3 is highly expressed in blood-derived NK cells but not in CD8+ T cells. In GL261 glioma-bearing mice treated with the alkylating agent temozolomide (TMZ) for 5 d, an early increased frequency of NK cells was observed. We also found that Abcc3 is strongly upregulated and functionally active in NK cells from mice treated with TMZ compared to controls. We demonstrate that Abcc3 is critical for NK cell survival during TMZ administration; more importantly, Akt, involved in lymphocyte survival, is phosphorylated only in NK cells expressing Abcc3. The resistance of NK cells to chemotherapy was accompanied by increased migration and homing in the brain at early time points. Cytotoxicity, evaluated by IFNγ production and specific lytic activity against GL261 cells, increased peripherally in the later phases, after conclusion of TMZ treatment. Intra-tumor increase of the NK effector subset as well as in IFNγ, granzymes and perforin-1 expression, were found early and persisted over time, correlating with a profound modulation on glioma microenvironment induced by TMZ. Our findings reveal an important involvement of Abcc3 in NK cell resistance to chemotherapy and have important clinical implications for patients treated with chemo-immunotherapy.

Growing evidence suggests that chemotherapy can influence the immune response by inducing lymphopenia or enhancing immunogenicity of dying tumor cells. In a clinical trial currently active in our Institution, patients with first diagnosis of glioblastoma are treated with dendritic cells (DC) loaded with autologous tumor lysate together with standard radio and chemotherapy with temozolomide. Peripheral blood lymphocytes from 22 patients were analyzed by flow cytometry to identify immune cell activation before and after DC vaccines. The ratio of vaccine/baseline frequencies (V/B ratio) was correlated with the survival of each patient. Increased V/B ratio for NK cells was significantly associated with prolonged PFS and OS (median 15.0 vs 8.0 mo, p = 0.003; 22.0 vs 12.0 mo, p = 0.02, respectively). Using the murine malignant glioma GL261, we investigated the molecular mechanisms induced by TMZ on NK and CD8 T cells. We treated mice 9 days after intracranial implantation of GL261 cells with intraperitoneal injections of TMZ (5 mg/kg) or vehicle (control mice) for 5 days. Mice were sacrificed at different time points and tumor and peripheral blood harvested and analyzed by flow cytometry. Gene expression profiling on peripheral blood lymphocytes revealed an up-regulation of multidrug resistance genes in NK cells, but not in CD8 T lymphocytes, in TMZ-treated mice compared to controls. The increased expression of the ATP transporter gene Abcc3 was confirmed by real time PCR (4.2-fold higher than controls, P = 0.006). Using eFluxx-ID multidrug resistance (MDR) assay based on specific inhibitors, we also demonstrated that Abcc3 was functionally active during TMZ treatment. NK cell resistance to chemotherapy was accompanied by an increase in migration and homing ability into the brain at early time point and in cytotoxicity at later phases (beyond the end of TMZ treatment). Our data show that murine NK cells are resistant to and activated by TMZ chemotherapy. Further investigations in patients treated by radio-chemotherapy with or without DC immunotherapy are warranted. Note: This abstract was not presented at the meeting. Citation Format: Serena Pellegatta, Sara Pessina, Gabriele Cantini, Emanuela Cazzato, Dimos Kapetis, Gaetano Finocchiaro. Abcc3 up-regulation confers protection from chemotherapy to NK cells in a murine model of malignant glioma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1343. doi:10.1158/1538-7445.AM2015-1343

Cancer stem–like cells (CSC) could be a novel target for cancer therapy, including dendritic cell (DC) immunotherapy. To address this, we developed experiments aimed at DC targeting of neurospheres (NS) from GL261 glioma cells because neurospheres can be enriched in CSC. We obtained murine neurospheres by growing GL261 cells in epidermal growth factor/basic fibroblast growth factor without serum. GL261-NS recapitulated important features of glioblastoma CSC and expressed higher levels of radial glia stem cell markers than GL261 cells growing under standard conditions (GL261 adherent cells, GL261-AC), as assessed by DNA microarray and real-time PCR. GL261-NS brain gliomas were highly infiltrating and more rapidly lethal than GL261-AC, as evidenced by survival analysis (P < 0.0001), magnetic resonance imaging and histology. DC from the bone marrow of syngeneic mice were then used for immunotherapy of GL261-NS and GL261-AC tumors. Strikingly, DC loaded with GL261-NS (DC-NS) cured 80% and 60% of GL261-AC and GL261-NS tumors, respectively (P < 0.0001), whereas DC-AC cured only 50% of GL261-AC tumors (P = 0.0022) and none of the GL261-NS tumors. GL261-NS expressed higher levels of MHC and costimulatory molecules (CD80 and CD86) than GL261-AC; the JAM assay indicated that DC-NS splenocytes had higher lytic activity than DC-AC splenocytes on both GL261-NS and GL261-AC, and immunohistochemistry showed that DC-NS vaccination was associated with robust tumor infiltration by CD8+ and CD4+ T lymphocytes. These findings suggest that DC targeting of CSC provides a higher level of protection against GL261 gliomas, a finding with potential implications for the design of clinical trials based on DC vaccination. (Cancer Res 2006; 66(21): 10247-52)

In recent years, the use of dendritic cells (DC), the most powerful antigen presenting cells, has been proposed for the creation of vaccines against gliomas. This approach has been demonstrated to be safe and non-toxic in phase I or I-II trials (2, 3). Immunotherapy plays a central role in the search for new treatments for glioblastoma multiforme (GBM). In particular, several phase I studies have been performed using DC pulsed by GBM proteins as a vaccine for patients with relapsing GBM. The studies demonstrated that DC vaccination is safe and may produce a significant increase in overall survival. As the first step in the preparation of appropriate conditions for a clinical evaluation in Italy, we have performed pre-clinical experiments on immune-competent mice injected intra-cerebrally with syngeneic GL261GBM cells and treated subcutaneously and intra-tumorally with DC loaded with a GL261 homogenate. These results show that vaccination with DC pulsed with a tumor lysate increases considerably survival in mice bearing intracranial glioblastomas and supports the development of DC-based clinical trials for patients with glioblastomas that do not respond to standard therapies.

During their growth, malignant gliomas interact with the immune system and are able to escape immune reactions. Attempts to instruct the immune system to develop anti-glioma reactions have been partly unsuccessful. Recent advances in the molecular and cellular biology of dendritic cells (DC), however, may increase the chances of preparing effective “vaccines” against these tumours. We show that vaccination with DC pulsed with a tumour lysate considerably increases survival in mice bearing intracranial glioblastomas. These results support the development of DC-based clinical trials for patients with glioblastomas that do not respond to standard therapies.

Twitcher (GALC(twi/twi)) is the murine model of globoid cell leukodystrophy (GLD or Krabbe disease), a disease caused by mutations of the lysosomal enzyme galactocerebrosidase (GALC). To verify the therapeutic potential on twitcher of neural stem/progenitor cells (NSPC), we transduced them with a GALC lentiviral vector. Brain injection of NSPC-GALC increased survival of GALC(twi/twi) from 36.1 +/- 4.1 to 52.2 +/- 5.6 days (P < 0.0001). Detection of GALC activity and flow cytometry showed that NSPC-GALC and NSPC expressing the green fluorescent protein were attracted to the posterior area of twitcher brain, where demyelination occurs first. GALC(twi/twi) microglia, also more abundant in posterior regions of the brain, released significant amounts of the cytotoxic cytokine TNF-alpha when matched with NSPC-GALC. Thus, in murine GLD, and possibly in other demyelinating diseases, NSPC are attracted to regions of active demyelination but have limited survival and therapeutic potential if attacked by activated macrophages/microglia.

2087 Background: DENDR1 is a phase I-II phase study aimed at evaluating dendritic cell (DC) immunotherapy in patients with first diagnosis of glioblastoma multiforme (GBM). Here we provide results ...

Background Recent data suggest that circulating endothelial and progenitor cells (CECs and CEPs, respectively) may have predictive potential in cancer patients treated with bevacizumab, the antibody recognizing vascular endothelial growth factor (VEGF). Here we report on CECs and CEPs investigated in 68 patients affected by recurrent glioblastoma (rGBM) treated with bevacizumab and irinotecan and two Independent Datasets of rGBM patients respectively treated with bevacizumab alone (n=32, independent dataset A: IDA) and classical antiblastic chemotherapy (n=14, independent dataset B: IDB). Methods rGBM patients with KPS ≥50 were treated until progression, as defined by MRI with RANO criteria. CECs expressing CD109, a marker of tumor endothelial cells, as well as other CEC and CEP subtypes, were investigated by six-color flow cytometry. Results A baseline count of CD109+ CEC higher than 41.1/ml (1st quartile) was associated with increased progression free survival (PFS; 20 versus 9 weeks, P=0.008) and overall survival (OS; 32 versus 23 weeks, P=0.03). Longer PFS (25 versus 8 weeks, P=0.02) and OS (27 versus 17 weeks, P=0.03) were also confirmed in IDA with CD109+ CECs higher than 41.1/ml but not in IDB. Patients treated with bevacizumab with or without irinotecan that were free from MRI progression after two months of treatment had significant decrease of CD109+ CECs: median PFS was 19 weeks; median OS 29 weeks. The presence of two non-contiguous lesions (distant disease) at baseline was an independent predictor of shorter PFS and OS (P

Recurrent glioblastoma (GB) are highly aggressive tumors allowing 6-8 month survival. Here we evaluated the possible benefits of immunotherapy with mature dendritic cells (DC) loaded with autologous tumor lysate in 15 patients with recurrent GB. After a median follow-up of 8 months median progression free survival (PFS) was 4.4 months and median overall survival (OS) 8.0 months. Patients with small tumors at first vaccination (< 20 cc; n = 8) had significantly longer PFS and OS than others: 6.0 vs 3.0 months (p = 0.01) and 16.5 vs 7.0 months (p = 0.003), respectively. Patients were analysed for CD8+ T cells, CD56+ NK cells and other relevant immunological parameters in peripheral blood before and after immunization, defining a vaccination/baseline ratio (V/B ratio). Increased V/B ratio of NK but not CD8+ T cells was significantly associated to longer PFS and OS. Patients showing NK cell responses had higher levels of IFN-γ and E4BP4, the NK cell transcription factor. Furthermore, NK V/B ratio was inversely correlated with TGF-β2 and VEGF V/B ratio. The results suggest that tumor-loaded DC may increase survival of recurrent GB after effective tumor debulking and emphasize the role of NK cell responses in this therapeutic setting. Citation Format: Serena Pellegatta, Marica Eoli, Simona Frigerio, Carlo Antozzi, Maria Grazia Bruzzone, Gabriele Cantini, Sara Nava, Elena Anghileri, Lucia Cuppini, Valeria Cuccarini, Emilio Ciusani, Marta Dossena, Bianca Pollo, Renato Mantegazza, Eugenio A. Parati, Gaetano Finocchiaro. NK cell response and tumor debulking are associated to prolonged survival in recurrent glioblastoma treated by dendritic cells loaded with autologous tumor lysate. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2839. doi:10.1158/1538-7445.AM2013-2839 Note: This abstract was not presented at the AACR Annual Meeting 2013 because the presenter was unable to attend.

2044 Background: Bevacizumab (Bev), a monoclonal antibody targeting the vascular endothelial growth factor (VEGF), has shown significant activity in a subset of patients with high grade gliomas (HGG): to date no biological marker can predict the treatment benefit. Circulating endothelial cells (CEC) and progenitors (CEP) have been observed in cancer patients, reflecting ongoing tumor angiogenesis. Methods: Forty-seven HGG patients (38 glioblastoma, GB; 9 anaplastic astrocytomas), relapsing after radiotherapy and temozolomide, were treated every 2 weeks with Bev (10 mg/kg) and irinotecan (125 or 340 mg/m2 depending on EIAEDs use). Adverse events were graded based on the CTC-AE v3.0. Before first treatment and every 8 weeks MRI and CEC and CEP assessment were performed. Radiological responses were assessed based on RANO criteria. CEC and CEP were enumerated in healthy controls (n=37) and patients by six color flow cytometry as Syto+CD45-CD31+/P1h12+ and Syto+CD45-CD31+/CD133+ cells, respectively. The Kaplan...

The identification of antigens preferentially expressed in glioblastoma (GBM) and involved in its malignant phenotype is critical for for developing therapeutic strategies. We observed by DNA microarray analysis and confirmed by western blot and immunocytochemistry that the neural stem cells marker GLAST (Glutamate Aspartate Transporter), highly expressed in cells of the radial glia, is also expressed in the plasma membrane of murine and human GBM stem-like cells (GSC). GLAST is a membrane protein expressed by astrocytes with a relevant role in glutamate uptake. When we evaluated the uptake in different GSC lines we found that their glutamate uptake is up to 100 fold lower than in normal astrocytes. GSC are able to release glutamate in culture medium just as hypoxic astrocytes, showing that in pathological conditions such as ischemia, transporters can reverse uptake and release glutamate. We have used GLAST as a marker to isolate a GSC subpopulation by immunomagnetic sorting and test the capacity of GLAST-enriched cells for tumor formation in mice. Using the murine glioma model GL261, GLAST+ cells injected intracranially were significantly more tumorigenic than GLAST- or unsorted cells (p=0.00057 and p=0.00028, respectively). We confirmed these observations in nude mice using GSC from one human recurrent GBM. Histological analysis provided evidence of the invasive nature of GLAST+ GSC asin the contralateral hemisphere many tumor cellsexpress GLAST and the migration marker Double-Cortin. To evaluate the functional role of GLAST in GSC we decided to target GLAST expression using lentiviral particles expressing GLAST shRNA. GLAST inhibition impacts on cell proliferation and especially on Matrigel invasion in vitro and interferes with tumor progression, improving survival in injected nude mice (p = 0.0034 shGLAST vs Scrambled). As a consequence of GLAST interference we also found in vitro a significant reduction of glutamate release in silenced cells compared to control cells(non specific shRNA). We investigated the expression of GLAST in 60 human primary GBM and 15 low grade gliomas (LGG) by immunohistochemistry. We found marked expression of GLAST in the large majority of GBM, in contrast LGG were negative or showed nuclear expression of GLAST. When we correlated GLAST expression to overall survival of 51 GBM patients we found that high percentage of GLAST pos cells and moderate or strong reactivity correlate with decreased overall survival (p=0.02). Our data suggest that GLAST is expressed in GBM and may be involved in proliferation and invasion. In addition GLAST could be investigated as clinical marker in association with prognosis of GBM patients and for development of novel therapeutic strategies. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3403. doi:10.1158/1538-7445.AM2011-3403

2067 Background: Bevacizumab, an anti-VEGF antibody, is active in a fraction of high-grade gliomas. Circulating endothelial and progenitor cells (CECs and CEPs, respectively), contribute to the formation of tumor vessels and their number may correlate with the degree of tumor angiogenesis. Methods: We tested this relationship in 24 patients with recurrent, high-grade gliomas (19 glioblastomas, GBM; 5 anaplastic astrocytomas, AA) treated with bevacizumab (10 mg/kg every two weeks) and Irinotecan (125 mg/m2 every two weeks for patients not on EIAEDs and 340 mg/mq for patients on EIAEDs) after approval of the Ethical Committee of the Neurological Institute C. Besta. The number and viability of CECs and CEPs were measured before treatment and every 2 months by six color cytometry. CECs were enumerated as Syto+CD45- CD31+/P1h12+ cells, CEPs as Syto+CD45- CD31+/CD133+ cells; CEC subpopulations expressing CD109 were also enumerated. Results: Median age was 53 years (range 15-66), median Karnofsky Performance Sta...

Malignant brain tumours are among the most deadly cancers. Current treatment strategies, such as surgery, chemotherapy and radiotherapy only modestly improve patient survival. The limited success of these strategies is largely due to a high incidence of tumor recurrence after the treatment. Recent evidences suggested that a rare population of stem-like cells (or tumour initiating cells) present in brain tumours might be responsible for the aggressiveness and recurrence of these tumours. These cells, named brain tumor stem-like cells (BTSC), share many properties of normal neural stem cells, including self renewal, extended proliferation, formation of neurospheres (when cultured in vitro in the presence of growth factors) and potential to differentiate into neurons and glial cells. Further investigations have suggested that studying this BTSC population in glioblastoma (GBM) is a more relevant system for exploring glioma biology than the adherently growing glioma cell lines. In the current study we identified target genes and proteins that are differently expressed between adherent glioma cell lines and sphere growing BTSC, using microarray and differential proteomics, respectively. Fatty acid-binding protein 7 (FABP7) was identified as overexpressed in BTSC compared to glioma adherent cell lines both at the gene as well as at the protein level. FABP proteins are a family of small, highly conserved, cytoplasmic proteins that bind long-chain fatty acids and other hydrophobic ligands. FABPs are thought to play important roles in fatty acid uptake, transport, and metabolism. Functionally, FABPS were described to play a role in gene regulation, cell signaling, cell growth and differentiation. The functional role of FABP7 in glioblastoma was investigated by assessing the effect of silencing FABP7 on migration and cell proliferation of glioblastoma cells. We observed that down-regulating FABP7 expression significantly reduced in vitro cell proliferation and even more the migration of BTSC. Since increased tumour infiltration was reported as a consequence of radiotherapy, the potential involvement of FABP7 in this process was evaluated. Irradiated BTSCs displayed significantly higher FABP7 protein levels and therefore we suggest that FABP7 may contribute to the radiotherapy-induced aggressive phenotype of BTSCs. Moreover, further mechanistic investigations indicated that directly or indirectly reducing the expression of FABP7 significantly impacts on the behaviour of glioblastoma derived BTSC. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5148.

IL-17, produced by Th17 cells, may play a dual role in antitumor immunity. Using the GL261 murine glioma model, we have investigated how Th17 cells can affect tumor growth and microenvironment. We first obtained TIL from fresh GL261-glioma 10 and 20 days after tumor implantation, and evaluated by flow cytometry infiltrating-Th17 as a percentage of total CD4+ cells. Th17 increased from 7.9±1.9 on day 10 to 13.1±5.2 on day 20 (p=0.03). To characterize the direct effects of Th17 cells on GL261-glioma and on tumor microenvironment, we isolated IL-17 producing cells enriched using Miltenyi technology from splenocytes derived from naïve or glioma-bearing mice (Gb) and pre-stimulated in vitro with or without TGF-ß. Th17 derived from naïve (nTh17) or Gb splenocytes (GbTh17) were co-injected subcutaneously with GL261 cells in immune-competent mice. Gliomas in mice co-injected with nTh17 were smaller than gliomas obtained from GL261 cells only (34±39.5mm3 vs 235.3±22.0mm3 respectively, p=0.003). In these gliomas, using RT-PCR we also found enhanced expression in IFN- and decreased expression of IL-10, TGF- and VEGF. Opposite results were obtained in gliomas of mice co-injected with Gb-Th17 (866±627 mm3, p=0.01 vs GL261, p By MTT assay and kinetic proliferation we found that IL-17 per se did not exert effects on GL261 proliferation. Because Th17 may differentiate under the influence of TGF-ß as well as regulatory T cells (Treg), we characterized both Treg and Th17. Treg were significantly higher in splenocytes from Gb than naïve mice (19.8±2.8% vs 3.5±0.05% respectively, p=0.01). nTh17 produced higher levels of IFN- than IL-10 (9.7±0.7% vs 2.2± 1.5, respectively, p=0.01) suggesting a suppressive function on tumor microenvironment. In contrast, GbTh17 produced more IL-10 than IFN- (9.3±1.4% vs 1.6±0.7%, respectively, p=0.02), suggesting a promoting function on tumor growth. To determine the potential influence of Treg in driving Th17 cytokine profile, using PC61 we depleted the Treg fraction in Gb splenocytes from 19.5±2.0% to 1.3±0.6% (p Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr LB-315.

The glutamate-aspartate transporter GLAST is a radial glia marker that is highly expressed in GL261 stem-like cells (GSCs). To target GLAST, we treated glioma-bearing mice with three subcutaneous injections of four GLAST peptides emulsified with Montanide ISA-51 in association with granulocyte macrophage colony-stimulating factor (GM-CSF) injections. Vaccination with GLAST peptides significantly prolonged survival, effectively enhanced systemic T-cell and NK-cell responses and promoted robust antitumor cytotoxicity. GLAST expression significantly decreased in gliomas from immunized mice, as evaluated by histological analysis and real-time PCR (RT-PCR). Moreover, the immunization protocol led to the upregulation of interferonγ (IFNγ) and tumor necrosis factorα (TNFα) as well as to the downregulation of transforming growth factor (TGF) β1 and β2 in the tumor. Beyond these changes, gliomas from immunized mice exhibited an increased recruitment of NK cells and antigen-specific CD8+ T cells expressing the tumor homing molecule VLA-4, as well as a local chemotactic gradient featuring expression of CXCL10 (which may be responsible for the recruitment of CTLs), CCL3, CCL4 and CCL5 (which are involved in NK-cell migration), and NKG2D ligand on glioma cells. Importantly, although GLAST is expressed in the central nervous system, autoimmune reactions were not observed in immunized mice. Altogether, these results support the contention that GLAST may constitute a glioma antigen against which immune responses can be efficiently induced without major safety concerns.

Absence of serum and presence of growth factors (mostly EGF and bFGF) has been used to culture cancer stem cells (CSC). In case of GB the term neurospheres (NS) has been considered as synonymous of glioma stem-like cells (GSCs). In our laboratories we isolate and culture GSC from fresh GB specimens growing in the absence of serum and in the presence of EGF and bFGF as neurospheres after mechanical and enzymatic dissociation. Previous data and our experience suggest that NS may mirror more closely than previous, serum-based glioma cell lines, the actual biology of GB. Tumor fragments were used to start the culture. The Cavitation Ultrasonics Surgical Aspirator (CUSA) is increasingly used for GB surgery, decreasing the availability of tumor fragments. CUSA delivers an irrigating solution that converts the fragmented tissue into an emulsion and then aspirates the particles directly into a sterile bag. The bag contains some larger pieces of tissue, debris and high amounts of erythrocytes, and occasionally necrotic or reactive tissue. Here we describe our experience with CUSA bags as the staring material for GSC preparation. Tissue fragments in CUSA bags after several rounds of spinning ad washing are dissociated using the GentleMacs Dissociator (Miltenyi Biotec) that provides a closed system and reproducible results. We have optimized a gentle and effective protocol starting from appropriate gentleMACS programs, allowing to obtain a high yield of viable tumor cells. After processing, cell suspensions are cultured as neurospheres in DMEM/F12, B27 supplement, human recombinant b-FGF and EGF. During the last year we obtained from the Department of Neurosurgery of Istituto Besta a total of 54 CUSA. Primary GB were the most represented brain tumors (87%). Using tumor fragments obtained from surgery and combining mechanical dissociation with enzymatic disaggregation on a series of primary GB we previously obtained GSC in 52% of the cases. This percentage is now increased to 71% with the use of surgical material from CUSA and the optimized protocol. Proliferation kinetics was studied by plating three primary cell lines obtained in parallel from GB specimen and from CUSA material at density of 15,000-30,000 cells/cm2. Cultures were collected every 5 days and the total number of viable cells assessed at each passage by Trypan Blue exclusion. A long term proliferation of cell lines at low sub-culturing stages (3 to 10 passages), showed that proliferation increased exponentially, but the proliferation index of NS from CUSA materials was higher that cells from specimens (1.32 vs 1.18 respectively, p = 0.03). These improvements and the use of a closed system providing a wider margin of safety support the incorporation of this process in a clinical trial protocol which plans to use GSC as a source of antigens for dendritic cell loading, replacing the whole lysate from GB specimens used in current immunotherapy protocols.