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Although immunotherapy has become an attractive approach to cancer treatment in patients with broad types of aggressive tumors, phase III clinical trials of immunotherapy for glioblastoma (GBM) have not achieved extended survival of patients. Dendritic cells perform an essential role in the immune system as antigen-presenting cells and tumor fused dendritic cells (TFDCs) can induce tumor-specific cytotoxic T cells as a cancer vaccine. We have previously described the safety and mechanisms of TFDCs therapy, as well as immunological and clinical responses of patients with GBM, however, there were little known about predictive and prognostic biomarkers specific to TFDCs therapy. In the present study, we investigated the whole transcriptome sequencing of tumor cells, and novel prognostic factors were identified through molecular profiling GBM treated with TFDCs immunotherapy. Fifty-three patients were eligible in this study and 28 samples from patients with newly diagnosed GBM IDH wild-type were included. Of these 28 samples, 15 high-quality RNA samples successfully extracted from tumors were analysed. The samples were divided into two groups based on the median patient's overall survival. Differential expression analyses and enrichment analysis between the two groups were carried out using CLC Genomics Workbench (QIAGEN), and Gene Ontologies (GO) were assigned. A total of 473 differentially expressed genes were detected including 327 enriched GO terms. Fifteen GO terms out of 327 GO terms represented the highest enrichment scores, revealed that five GO terms were associated with the major histocompatibility complex (MHC). The relationship among the MHC, immune-related genes, and clinical outcomes was investigated using the Cox regression model and Kaplan–Meier log-rank test. Low expression of HLA-A in the tumors turned out to be a significantly favorable prognostic impact (p = 0.01). The decreased expression of HLA-A might be a novel prognostic factor in GBM patients treated with TFDCs immunotherapy.

Although bevacizumab was shown to improve progression-free survival and performance status of the patients with high-grade gliomas, clinical trials consistently showed lack of benefit in terms of patients’ overall survival. The recurrent tumors are inevitably more aggressive and invasive as compared with the original tumors, and the in-situ observation in actual human specimens is essential to elucidate the mechanism of resistance. In Japan, bevacizumab was approved not only for recurrent but also for newly diagnosed cases. The safety as well as efficacy of resection following neoadjuvant bevacizumab has been reported, and a phase II study is currently ongoing (UMIN-000025579). In the present study, the expression of angiogenic factors other than VEGF (basic fibroblast growth factor (bFGF), placenral growth factor (PlGF), angiopoietin1/2 and ephrinA2) was investigated by immunohistochemistry to be compared among tumors with no previous bevacizumab treatment, those resected following bevacizumab, and those refractory to bevacizumab. Fifty-nine samples from 42 patients were included; 24 of newly diagnosed glioblastomas with no previous bevacizumab (naïve group), 16 resected following neoadjuvant bevacizumab (effective group), and 6 resected after recurrence or autopsied (refractory/autopsied group). 12 were paired samples (8 naïve and refractory, 4 effective and refractory). The expression of PlGF significantly increased in the effective group as compared with the naïve group (p=0.003). In the paired specimens, there was a trend towards increased expression of PlGF in the second specimens (refractory/autopsied group) as compared with the specimens of initial surgery (p=0.083). Angiopoietin1, angiopoietin2 and ephrinA2 were characteristically expressed in the microvessels less than 15μm. The increased expression of PlGF might be associated with the recurrence after bevacizumab.

BACKGROUND/OBJECTIVES Relapsed or refractory brain tumors in childhood continue to have a dismal prognosis in spite of intensive multidisciplinary treatment. Cancer immunotherapy is newly developed to be expected as next promising treatment for highly aggressive pediatric cancer. This trial was designed to evaluate the safety and effectiveness of an immunotherapy with fusions of dendritic cells (DCs) and tumor cells in patients with malignant brain tumors. METHODS Patients with histopathologically confirmed malignant and recurrent/refractory brain tumor were eligible for this immunotherapy trial. Autologous cultured tumor cells obtained from surgical specimens were fused with autologous DCs using polyethylene glycol. The fusion cells (FC) were inoculated intradermally in the cervical region and repeated 3–10 times in each 28–84 days cycle. Treatment-related toxicity, progression-free survival (PFS), and overall survival (OS) were evaluated. RESULTS Six patients were enrolled, three with high grade glioma and three with ependymoma. Median age at first course of immunotherapy was 10 years (range 8–25 years) and median follow-up time from the first course of immunotherapy was 13.5 months (range 3–33 months). All patients with immunotherapy were well tolerated to this treatment with no adverse events except local erythema in injected site. Median progression free survival and overall survival were 18 months and 18.5 months, respectively. CONCLUSIONS FC immunotherapy with autologous DCs and tumor cells for brain tumor in children and young adults were extremely well tolerated and showed encouraging responses in this series. Further phase II study of FC immunotherapy is planned to improve survival and reduce treatment related morbidity.