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BACKGROUND: The PI3K pathway is activated in most GBMs and represents a potential therapeutic target. Buparlisib is an oral, pan-Class I PI3K inhibitor that enters the brain at therapeutic concentrations and inhibits the growth of U87 and human glioma tumor sphere models. METHODS: The Ivy Consortium conducted a phase II study of buparlisib in recurrent GBM patients with activation of the PI3K pathway (mutation, homozygous deletion or loss of IHC of PTEN, PIK3CA or PIK3RI mutations, or detectable pAKT). Additional eligibility criteria included radiologic progression, 1st or 2nd relapse, >18 yrs, KPS >60, adequate bone marrow and organ function, no prior bevacizumab or enzyme-inducing antiepileptic drugs. Patients received buparlisib 100mg daily. The study consisted of 2 concurrent cohorts. In Cohort 1 (up to 15 patients) buparlisib was given for 8-12 days prior to surgery for recurrent disease. Patients underwent FDG PET, pharmacokinetic studies, and tumor was obtained for drug concentrations and pharmacodynamic effects. In Cohort 2, 50 patients with unresectable GBM received buparlisib with a primary endpoint of PFS6. RESULTS: 13 patients were enrolled into cohort 1, 50 into cohort 2. Treatment was fairly well-tolerated with no grade 4 toxicities. Grade 3 toxicities were asymptomatic lipase elevation (6), rash (4), hyperglycemia (3), fatigue (4), elevated ALT/AST (2), and 1 each with depression, anxiety, hypophosphatemia, thrombocytopenia and lymphopenia. Analysis of tumor specimens from Cohort 1 showed reduction of pAKT by IHC in 4/6 (67%) of evaluable patients. The combined cohorts showed minimal efficacy with median PFS of 1.8 months and median OS of 10.9 months. Best response was stable disease. Only 1 patient in each cohort achieved PFS6. Of the first 40 patients who underwent exome sequencing, there were 4 PIK3CA (10%), 2 PIK3R1 (5%) and 13 PTEN (33%) mutations. Patients with PTEN loss and or PI3K mutations paradoxically had a worse outcome. CONCLUSIONS: Buparlisib is well-tolerated in patients with recurrent GBM and achieves adequate tumor concentration to inhibit pAKTS473. However, single agent efficacy was minimal. Final correlation of tumor genotype with outcome will be presented. SECONDARY CATEGORY: n/a.

As many as 100 ,000 new cases of brain tumor are diagnosed each year in the United States. About half of these are primary gliomas and the remaining half are metastatic tumors and non-glial primary tumors. Currently, gliomas are classified based on phenotypic characteristics. Recent progress in the elucidation of genetic alterations found in gliomas have raised the exciting possibility of using genetic and molecular analyses to resolve some of the problematic issues currently associated with the histological approach to glioma classification. Recently , immunohistochemical studies using novel proliferation markers have significantly advanced the assessment of tumor growth potential and the grading criteria of some tumor subtypes. Preliminary studies using cDNA array technologies suggest that the profiling of gene expression patterns may provide a novel and meaningful approach to glioma classification and subclassification. Furthermore, cDNA array technologies may also be used to identify candidate genes involved in glioma tumor development, invasion, and progression. This review summarizes current glioma classification schemes that are based on histopathological characteristics and discusses the potential for using cDNA array technology in the molecular classification of gliomas.

There is considerable evidence that lack of p16 protein expression is a frequent event in human gliomas. Nevertheless, the molecular mechanisms underlying this absence of p16 protein expression are not completely understood. In some gliomas, homozygous deletions are the main cause of p16/CDKN2 gene inactivation. However, other gliomas lacking p16 expression exhibit intact p16/CDKN2 gene, suggesting that p16/CDKN2 is down-regulated at the transcriptional level. In this study we investigated whether aberrant p16/CDKN2 gene methylation correlated with absence of p16 expression in the latter group of gliomas. In a series of 27 gliomas, 12 malignant tumors exhibited loss of p16/CDKN2 expression but not gene deletion. Methylation analysis of the CpG island in the 5' region of the p16/CDKN2 gene showed that exon 1 was extensively methylated in six and partially methylated in the other six of the 12 malignant gliomas. In contrast, no methylation was observed in four other malignant gliomas and two low-grade gliomas that expressed p16 protein. These results indicate that abnormal hypermethylation of the CpG island encompassing the 5' end of the p16/CDKN2 gene may be a mechanism of transcriptional silencing in gliomas without homozygous deletions. Oncogene

PURPOSE: Little progress has been made in the treatment of adult high-grade gliomas over the last two decades, thus necessitating a search for novel therapeutic strategies. Malignant gliomas are vascular or angiogenic tumors, which leads to the supposition that angiogenesis inhibition may represent a potentially promising strategy in the treatment of these tumors. We present the results of a phase II trial of thalidomide, a putative inhibitor of angiogenesis, in the treatment of adults with previously irradiated, recurrent high-grade gliomas. PATIENTS AND METHODS: Patients with a histologic diagnosis of anaplastic mixed glioma, anaplastic astrocytoma, or glioblastoma multiforme who had radiographic demonstration of tumor progression after standard external-beam radiotherapy with or without chemotherapy were eligible. Patients were initially treated with thalidomide 800 mg/d with increases in dose by 200 mg/d every 2 weeks until a final daily dose of 1,200 mg was achieved. Patients were evaluated every 8 weeks for response by both clinical and radiographic criteria. RESULTS: A total of 39 patients were accrued, with 36 patients being assessable for both toxicity and response. Thalidomide was well tolerated, with constipation and sedation being the major toxicities. One patient developed a grade 2 peripheral neuropathy after treatment with thalidomide for nearly a year. There were two objective radiographic partial responses (6%), two minor responses (6%), and 12 patients with stable disease (33%). Eight patients were alive more than 1 year after starting thalidomide, although almost all with tumor progression. Changes in serum levels of basic fibroblastic growth factor (bFGF) were correlated with time to tumor progression and overall survival. CONCLUSION: Thalidomide is a generally well-tolerated drug that may have antitumor activity in a minority of patients with recurrent high-grade gliomas. Future studies will better define the usefulness of thalidomide in newly diagnosed patients with malignant gliomas and in combination with radiotherapy and chemotherapy. Additionally, studies will be needed to confirm the potential utility of changes in serum bFGF as a marker of antiangiogenic activity and/or glioma growth. J Clin Oncol

The diffuse and extensive infiltration of malignant gliomas into the surrounding normal brain is believed to rely on modifications of the proteolysis of extracellular matrix components. A key molecule in regulating plasminogen-mediated extracellular proteolysis is the urokinase-type plasminogen activator (uPA). To investigate the role of uPA in the invasive process of brain tumors, we stably transfected a human glioblastoma cell line SNB19 with a vector capable of expressing an antisense transcript complementary to the 1020 bases at the 3' end of the uPA cDNA. Parental, vector-, and antisense construct-stably transfected cell lines were analyzed for uPA mRNA transcript by Northern blot analysis, for uPA enzyme activity by zymography, and for uPA protein levels by Western blotting. The levels of uPA mRNA, protein, and enzyme activities were significantly lower in antisense clones than in parental and vector controls. Radioreceptor binding studies demonstrated that uPA receptor levels remained the same in parental, vector-, and antisense-transfected cells. The antisense-transfected cells showed a markedly lower level of invasion in the Matrigel invasion assays, and their spheroids failed to invade the fetal rat brain aggregates in the coculture system. Green fluorescent protein (GFP) expressing parental and antisense transfectants was generated for detection in mouse brain tissue without any posttreatment. Intracerebral injection of antisense stable transfectants significantly reduced tumor formation compared with that in controls. Our results suggested that down-regulation of uPA expression may be a feasible approach to reducing the malignancy and invasiveness of glial tumors. Clin Cancer Res

Presently, there is no effective treatment for glioblastoma, the most malignant and common brain tumor. Angiogenic factors are potentially optimal targets for therapeutic strategies because they are essential for tumor growth and progression. In this study, we sought a strategy for efficiently delivering an antisense cDNA molecule of the vascular endothelial growth factor (VEGF) to glioma cells. The recombinant adenoviral vector Ad5CMV-alphaVEGF carried the coding sequence of wild-type VEGF165 cDNA in an antisense orientation. Infection of U-87 MG malignant glioma cells with the Ad5CMV-alphaVEGF resulted in reduction of the level of the endogenous VEGF mRNA and drastically decreased the production of the targeted secretory form of the VEGF protein. Treatment of s.c. human glioma tumors established in nude mice with intralesional injection of Ad5CMV-alphaVEGF inhibited tumor growth. Taken together, these findings indicate that the efficient down-regulation of the VEGF produced by tumoral cells using antisense strategies has an antitumor effect in vivo. This is the first time that an adenoviral vector is used to transfer antisense VEGF sequence into glioma cells in an animal model, and our results suggest that this system may have clinical and therapeutic utility. Cancer Res

The p16 (MTS1/CDKN2) gene localized at the 9p21 chromosomal region encodes for a cell cycle inhibitor protein and is altered in many human cancers. The frequency of p16 alterations in gliomas exceeds 50%. To restore the missing wild-type p16 gene efficiently in glioma cells an adenovirus vector carrying the full length coding sequence of the wild-type p16 cDNA, Ad5RSV-p16, was constructed. Three human glioma cell lines, U251 MG, U-87 MG and D54 MG, that did not express endogenous p16/CDKN2 gene and were easily infected with adenovirus vectors were selected for these experiments. Introduction of the Ad5RSV-p16 in these malignant glioma cell lines directed the biosynthesis of functional p16 protein in the majority of the exposed cells, significantly inhibited cell growth, influenced cell morphology and modified the transformed phenotype of cells including the ability to form colonies in soft agar. Flow cytometric studies revealed that the majority of the Ad5RSV-p16 infected glioma cells were arrested in the G0-G1 phases of the cell cycle. These results suggest that p16/CDKN2 inactivation is a significant factor in the genesis and progression of gliomas and that the restoration of the wild-type p16 protein could have clinical and therapeutic utility. Oncogene