Neoantigens, which are derived from tumour-specific protein-coding mutations, are exempt from central tolerance, can generate robust immune responses1,2 and can function as bona fide antigens that facilitate tumour rejection3. Here we demonstrate that a strategy that uses multi-epitope, personalized neoantigen vaccination, which has previously been tested in patients with high-risk melanoma4–6, is feasible for tumours such as glioblastoma, which typically have a relatively low mutation load1,7 and an immunologically ‘cold’ tumour microenvironment8. We used personalized neoantigen-targeting vaccines to immunize patients newly diagnosed with glioblastoma following surgical resection and conventional radiotherapy in a phase I/Ib study. Patients who did not receive dexamethasone—a highly potent corticosteroid that is frequently prescribed to treat cerebral oedema in patients with glioblastoma—generated circulating polyfunctional neoantigen-specific CD4+ and CD8+ T cell responses that were enriched in a memory phenotype and showed an increase in the number of tumour-infiltrating T cells. Using single-cell T cell receptor analysis, we provide evidence that neoantigen-specific T cells from the peripheral blood can migrate into an intracranial glioblastoma tumour. Neoantigen-targeting vaccines thus have the potential to favourably alter the immune milieu of glioblastoma.

microRNAs are noncoding RNAs inhibiting expression of numerous target genes, and a few have been shown to act as oncogenes or tumor suppressors. We show that microRNA-7 (miR-7) is a potential tumor suppressor in glioblastoma targeting critical cancer pathways. miR-7 potently suppressed epidermal growth factor receptor expression, and furthermore it independently inhibited the Akt pathway via targeting upstream regulators. miR-7 expression was down-regulated in glioblastoma versus surrounding brain, with a mechanism involving impaired processing. Importantly, transfection with miR-7 decreased viability and invasiveness of primary glioblastoma lines. This study establishes miR-7 as a regulator of major cancer pathways and suggests that it has therapeutic potential for glioblastoma. [Cancer Res 2008;68(10):3566-72]

MicroRNAs (miR) show characteristic expression signatures in various cancers and can profoundly affect cancer cell behavior. We carried out miR expression profiling of human glioblastoma specimens versus adjacent brain devoid of tumor. This revealed several significant alterations, including a pronounced reduction of miR-128 in tumor samples. miR-128 expression significantly reduced glioma cell proliferation in vitro and glioma xenograft growth in vivo. miR-128 caused a striking decrease in expression of the Bmi-1 oncogene, by direct regulation of the Bmi-1 mRNA 3 ¶-untranslated region, through a single miR-128 binding site. In a panel of patient glioblastoma specimens, Bmi-1 expression was significantly up-regulated and miR-128 was down-regulated compared with normal brain. Bmi-1 functions in epigenetic silencing of certain genes through epigenetic chromatin modification. We found that miR-128 expression caused a decrease in histone methylation (H3K27me 3 ) and Akt phosphorylation, and up-regulation of p21 CIP1 levels, consistent with Bmi-1 down-regulation. Bmi-1 has also been shown to promote stem cell self-renewal; therefore, we investigated the effects of miR-128 overexpression in human glioma neurosphere cultures, possessing features of glioma ''stem-like'' cells. This showed that miR-128 specifically blocked glioma self-renewal consistent with Bmi-1 downregulation. This is the first example of specific regulation by a miR of a neural stem cell self-renewal factor, implicating miRs that may normally regulate brain development as important biological and therapeutic targets against the ''stem cell-like'' characteristics of glioma. [Cancer Res 2008;68(22):9125-30]

Summary To sustain tumor growth, cancer cells must be able to adapt to fluctuations in energy availability. We have identified a single microRNA that controls glioma cell proliferation, migration, and responsiveness to glucose deprivation. Abundant glucose allows relatively high miR-451 expression, promoting cell growth. In low glucose, miR-451 levels decrease, slowing proliferation but enhancing migration and survival. This allows cells to survive metabolic stress and seek out favorable growth conditions. In glioblastoma patients, elevated miR-451 is associated with shorter survival. The effects of miR-451 are mediated by LKB1, which it represses through targeting its binding partner, CAB39 (MO25α). Overexpression of miR-451 sensitized cells to glucose deprivation, suggesting that its downregulation is necessary for robust activation of LKB1 in response to metabolic stress. Thus, miR-451 is a regulator of the LKB1/AMPK pathway, and this may represent a fundamental mechanism that contributes to cellular adaptation in response to altered energy availability.

Abstract Glioblastomas are the most common form of malignant primary brain tumor and an important cause of morbidity and mortality. In recent years there have been important advances in understanding the molecular pathogenesis and biology of these tumors, but this has not translated into significantly improved outcomes for patients. In this consensus review from the Society for Neuro-Oncology (SNO) and the European Association of Neuro-Oncology (EANO), the current management of isocitrate dehydrogenase wildtype (IDHwt) glioblastomas will be discussed. In addition, novel therapies such as targeted molecular therapies, agents targeting DNA damage response and metabolism, immunotherapies, and viral therapies will be reviewed, as well as the current challenges and future directions for research.

Glioblastoma can suppress immunity by using surface PD-L1 on extracellular vesicles to block T cell receptor–mediated T cell activation.

Oncolytic viruses are an active area of clinical research. The ability of these agents to harness antitumor immunity appears to be key for their success. Combinatorial studies with immune checkpoint blockade have started and the results are awaited with great interest.

Clinical trials are testing oncolytic viruses (OVs) as therapies for cancer. We have shown that animals that have brain tumors and are treated with a herpes simplex virus (HSV)-derived OV live significantly longer when cyclophosphamide (CPA) is preadministered. Here, we explore the mechanisms behind this finding. In a syngeneic rat glioma model, intratumoral HSV administration is associated with rapid increase of natural killer cells, microglia͞ macrophages (CD68 ؉ and CD163 ؉ ), and IFN-␥. Pretreatment with CPA enhances HSV replication and oncolysis and reduces an HSVmediated increase in CD68 ؉ and CD163 ؉ cells and intratumoral IFN-␥. Molecular imaging shows CPA pretreatment to inhibit HSVinduced infiltration of tumor-associated phagocytic cells. Our results reveal molecular and cellular mechanisms that inhibit intratumoral spread of HSV and suggest a therapeutic path for improving the efficacy of virotherapy as a treatment for cancer.gene therapy ͉ innate immunity ͉ oncolytic virus ͉ brain tumor ͉ herpes simplex virus A dvances in virology and tumor biology have enabled development of oncolytic viruses (OVs), which replicate selectively in tumor cells (1-6). OV progeny propagate throughout tumors, lysing tumor cells but not normal cells. Phase I clinical trials have shown OV therapy to be safe (7-13) but with limited efficacy. A brisk host response to OV therapy has been seen. It includes intratumoral immune cells (7) and acute-phase reaction to intravascular virus (13). Innate immune responses may be a common side effect of OV therapy, similar to the radionecrosis of radiotherapy or myelosuppression of chemotherapy.The role of host immune responses in the efficacy or toxicity of OV therapy is poorly defined. Such responses are thought beneficial because oncolysis stimulates adaptive immunity, setting up an anticancer vaccination effect (14-16). However, initial innate responses to OVs may reduce efficient anticancer effects (17-21). For example, we have shown a herpes simplex virus (HSV)-based OV therapy to be more efficient when cyclophosphamide (CPA) is present (22-25), and this increased efficiency is credited to CPA's immunosuppressive action. However, the specific immune pathways of the observed effects have not been analyzed. ResultsPreadministering CPA Inhibits Clearance of Viral Particles and Increases HSV Replication Within Injected Tumors. We have reported that CPA allows increased replication of HSV in injected tumors by suppressing immune activity (25). To determine intratumoral persistence of HSV, we compared intratumoral viral-mediated LacZ (Fig. 1) and ICP4 (infected-cell protein 4) (Fig. 6, which is published as supporting information on the PNAS web site) gene expression in immunocompetent rats 6 and 72 h after treatment with HSV, with and without CPA pretreatment. Six hours after intratumoral HSV delivery, Ϸ50% of tumor cells showed viral-mediated gene expression, regardless of CPA ( Fig. 1 A and C). However, by 72 h, without CPA, Ͻ10% of tumor cells showed viral-mediated gene expression,...