Notch activation contributes to Ras-induced transformation of glial cells and to glioma growth, survival, or both and as such may represent a new target for GBM therapy.

A recent study reported on mutations in the active site of the isocitrate dehydrogenase 1 (IDH1) gene in several types of gliomas. All mutations detected resulted in an amino acid exchange at position 132. We analyzed the genomic region spanning wild-type R132 of IDH1 by direct sequencing in 125 glial tumors. A total of 39 IDH1 mutations were observed. Mutations of the IDH2 gene, homologous to IDH1, were often detected in gliomas without IDH1 mutations. In the present study, R172 mutation of the IDH2 gene was detected in one anaplastic astrocytoma. IDH1 or IDH2 mutations were frequently in oligodendrogliomas (67%), anaplastic astrocytomas (62%), anaplastic oligoastrocytomas (75%), anaplastic oligodendrogliomas (50%), secondary glioblastomas (67%), gangliogliomas (38%), and anaplastic gangliogliomas (60%). Primary glioblastomas were characterized by a low frequency of mutations (5%) at amino acid position 132 of IDH1. Mutations of the IDH1 or IDH2 genes were significantly associated with improved outcome in patients with anaplastic astrocytomas. Our data suggest that IDH1 or IDH2 mutation plays a role in early tumor progression of several types of glioma and might arise from a common glial precursor. The infrequency of IDH1 mutation in primary glioblastomas revealed that these subtypes are genetically distinct entities from other glial tumors. (Cancer Sci 2009; 100: 1996-1998) G liomas are the most common primary brain tumors and are grouped into four grades according to the World Health Organization (WHO) criteria.(1) This group of tumors includes specific histological subtypes; the most common are astrocytomas, oligodendrogliomas, and ependymomas. Glioblastomas (GBM; WHO grade IV), the most malignant glioma, may manifest rapidly de novo (primary GBM), or develop slowly from low-grade diffuse or anaplastic astrocytoma (secondary GBM). (2) Recent genomewide mutational analysis revealed somatic mutations of cytosolic NADP + -dependent isocitrate dehydrogenase (IDH1) in approximately 12% of GBM.(3) Isocitrate dehydrogenase catalyzes the oxidative decarboxylation of isocitrate to α-ketoglutarate thereby leading to NADPH production.(4) Mutations affected the amino acid arginine at position 132 of the amino acid sequence, which is evolutionarily highly conserved, and is located in the binding site of isocitrate.(5) In the vast majority of the cases, wild-type arginine at position 132 was replaced by histidine ( R132H).The IDH2 gene is homologous to IDH1, which uses NADP + as an electron receptor. Gliomas without IDH1 mutations were often found to have mutations at the analogous amino acid (R172) of the IDH2 gene.(6) Both IDH1 and IDH2 mutations reduced the enzymatic activity of the encoded protein. (6) In recent analyses from North American and European groups, IDH1 mutations were more frequent in secondary GBM than primary GBM.(6-8) Similarly, high frequencies of IDH1 mutations were found in diffuse (WHO grade II) or anaplastic astrocytomas ( WHO grade III), oligodendrogliomas ( WHO grade II), and anaplastic oligoden...

Germ cell tumors constitute a heterogeneous group that displays a broad spectrum of morphology. They often arise in testes; however, extragonadal occurrence, in particular brain, is not uncommon, and whether they share a common pathogenesis is unknown. We performed whole exome sequencing in 41 pairs of central nervous system germ cell tumors (CNS GCTs) of various histology and their matched normal tissues. We then performed targeted sequencing of 41 selected genes in a total of 124 CNS GCTs, 65 testicular germ cell tumors (tGCTs) and 8 metastatic GCTs to the CNS. The results showed that mutually exclusive mutations of genes involved in the MAPK pathway were most common (48.4 %), typically in KIT (27.4 %), followed by those in the PI3K pathway (12.9 %), particularly in MTOR (6.5 %), among the 124 CNS GCTs. Pure germinomas and non-germinomatous germ cell tumors (NGGCTs), as well as CNS and testicular GCTs, showed similar mutational profiles, suggesting that GCTs share a common molecular pathogenesis. Mutated MTOR identified in CNS GCTs upregulated phosphorylation of the AKT pathway proteins including AKT and 4EBP1 in nutrient-deprived conditions and enhanced soft-agar colony formation; both events were suppressed in a dose-dependent manner by addition of the MTOR inhibitor pp242. Our findings indicate that the dominant genetic drivers of GCTs regardless of the site of origin are activation of the MAPK and/or PI3K pathways by somatic point mutations. Mutated MTOR represents a potential target for novel targeted therapies for refractory GCTs.

Intracranial germ cell tumors (iGCTs) are the second most common brain tumors among children under 15 in Japan. The pathogenesis of iGCTs is largely unexplored. Although a subset of iGCTs is known to have KIT mutation, its impact on the biology and patients' survival has not been established. In this study, we investigated genes involved in the KIT signaling pathway. 65 iGCTs (30 pure germinomas, 14 teratomas, 18 mixed GCTs, 2 yolk sac tumors, 1 choriocarcinoma) were screened for mutation of KIT, KRAS, NRAS, HRAS, BRAF, PDGFRA, and IDH1 by direct sequencing. KIT expression was examined by immunohistochemistry and quantitative PCR. Chromosomal status was analyzed by array-comparative genomic hybridization (aCGH). Somatic mutations were detected only in KIT and RAS, which were frequently observed in pure germinomas (60.0 %), but rare in non-germinomatous GCTs (NGGCTs) (8.6 %). All KIT/RAS mutations were mutually exclusive. Regardless of the mutation status or mRNA expression, the KIT protein was expressed in all germinomas, while only in 54.3 % of NGGCTs. Amplification of KIT was found in one pure germinoma by aCGH. In pure germinomas, high expression of KIT mRNA was associated with the presence of KIT/RAS alterations and severe chromosomal instability. Our results indicate that alterations of the KIT signaling pathway play an important role in the development of germinomas. Pure germinomas may develop through two distinct pathogeneses: one with KIT/RAS alterations, elevated KIT mRNA expression and severe chromosomal instability, and the other through yet an unidentified mechanism without any of the above abnormalities.

Background. We conducted a phase III trial of personalized peptide vaccination (PPV) for human leukocyte antigen (HLA)-A24+ recurrent glioblastoma to develop a new treatment modality. Methods. We randomly assigned 88 recurrent glioblastoma patients to receive PPV (n = 58) or the placebo (n = 30) at a 2-to-1 ratio. Four of 12 warehouse peptides selected based on preexisting peptide-specific immunoglobulin G levels or the corresponding placebos were injected 1×/week for 12 weeks. Results. Our trial met neither the primary (overall survival [OS]) nor secondary endpoints. Unfavorable factors for OS of 58 PPV patients compared with 30 placebo patients were SART2-93 peptide selection (n = 13 vs 8, hazard ratio [HR]: 15.9), ≥70 years old (4 vs 4, 7.87), >70 kg body weight (10 vs 7, 4.11), and performance status (PS)3 (8 vs 2, 2.82), respectively. Consequently, the median OS for PPV patients without SART2-93 selection plus one of these 3 favorable factors (<70 y old, ≤70 kg, or PS0-2) was significantly longer than that for the corresponding placebo patients (HR: 0.49, 0.44, and 0.51), respectively. Preexisting immunity against both all 12 warehouse peptides besides SART2-93 and the other cytotoxic T lymphocyte epitope peptides was significantly depressed in the patients with SART2-93 selection (n = 21) compared with that of the patients without SART2-93 selection (n = 67). Biomarkers correlative for favorable OS of the PPV patients were a lower percentage of CD11b+CD14+HLA-DR low A randomized, double-blind, phase III trial of personalized peptide vaccination for recurrent glioblastoma 349 Narita et al. Recurrent GBM and peptide vaccination: phase III trial Neuro-Oncologyimmunosuppressive monocytes and a higher percentage of CD4+CD45RA− activated T cells, the intermediate levels of chemokine C-C ligand 2 (CCL2), vascular endothelial growth factor, interleukin (IL)-6, IL-17, or haptoglobin, respectively. Conclusion. This phase III trial met neither the primary nor secondary endpoints. Key Points1. This trial of personalized peptide vaccination did not meet the primary endpoint.2. Personalized peptide vaccination shortened the OS of certain patients.3. Intermediate CCL2 level was a biomarker correlative for favorable OS.The overall survival (OS) of recurrent glioblastoma (rGBM) patients is very poor, although bevacizumab has been reported to improve the progression-free survival (PFS) of rGBM patients. [1][2][3] Many clinical studies failed to provide clinical benefits for rGBM in the past decade. [4][5][6] This failure may be partly due to the unique and diverse immunological features of GBM. 4-10 GBM tumor cells produce many cytokines and chemokines as potential autocrine growth factors and subsequent immune regulators, which might in turn influence the self-proliferation in most patients. 4-10 Among the GBM-producing cytokines, granulocyte-monocyte stimulating factor (GM-CSF) and the chemokine (C-C motif) ligand 2 (CCL2) are the two major factors for immune regulation. [6][7][8][9] GM-CSF forms a cytokine network with in...