PTEN mutation, EGFR amplification, and outcome in patients with anaplastic astrocytoma and glioblastoma multiforme

The prognostic relevance of molecular alterations in glioblastomas for patients age < 50 years

BACKGROUND

In patients with glioblastoma, age < 50 years was identified as a consistent prognostic variable. In addition, the prognosis for these patients may be determined by a complex interaction between age and genetic alterations. The objective of the current study was the molecular analysis of glioblastomas from adult patients age < 50 years ("young adults").

METHODS

The authors analyzed a set of 189 glioblastoma specimens. Fluorescence in situ hybridization was performed with a set of 10 chromosome probes (1p36, 1q25, centomere probe 7 [CEP7], 7p12/epidermal growth factor receptor gene (EGFR), CEP9, 9p21/p16, CEP10, 10q23/phosphatase and tesnin homolog gene (PTEN), 19p13, and 19q13).

RESULTS

Patient age < 40 years was associated strongly with a favorable prognosis. Patients age > or = 40 years frequently showed EGFR amplification, loss of 9p, loss of 10q, and gain of chromosome 19. The patients with - 19q were age < 40 years. The survival was shorter for patients with EGFR amplification, gain of chromosome 7, loss of 9p, loss of 10q, and gain of chromosome 19. In contrast, the patients who had tumors with gain of chromosome 9 or loss of 19q had more favorable outcomes. In a multivariate analysis, gain of chromosome 9 (P = 0.026) and loss of 10q23 (P = 0.007) reached the level of independent prognostic value. In addition, the prognostic value of molecular alterations in patients age < 40 years and patients age > 40 years were examined separately. Consequently, EGFR amplification, - 9p, and + 9 were significant for both age groups, whereas gain of chromosome 7 and loss of 10q showed clinical importance only among patients age > 40 years.

CONCLUSIONS

Adult patients age < 50 years with glioblastoma had molecularly distinct disease, and the age-dependent heterogeneity seen on the chromosomal level also applied at the clinical level.

Mutations in Rb1 pathway-related genes are associated with poor prognosis in anaplastic astrocytomas

Anaplastic astrocytoma (AA, WHO grade III) is, second to Glioblastoma, the most common and most malignant type of adult CNS tumour. Since survival for patients with AA varies markedly and there are no known useful prognostic or therapy response indicators, the primary purpose of this study was to examine whether knowledge of the known genetic abnormalities found in AA had any clinical value. The survival data on 37 carefully sampled AA was correlated with the results of a detailed analysis of the status of nine genes known to be involved in the development of astrocytic tumours. These included three genes coding for proteins in the p53 pathway (TP53, p14(ARF)and MDM2), four in the Rb1 pathway (CDKN2A, CDKN2B, RB1 and CDK4) and PTEN and EGFR. We found that loss of both wild-type copies of any of the three tumour suppressor genes CDKN2A, CDKN2B and RB1 or gene amplification of CDK4, disrupting the Rb1 pathway, were associated with shorter survival (P=0.009). This association was consistent in multivariate analysis, including adjustment for age (P=0.013). The findings suggest that analysis of the genes coding for Rb1 pathway components provides additional prognostic information in AA patients receiving conventional therapy.

Chromosome 22 tiling-path array-CGH analysis identifies germ-line- and tumor-specific aberrations in patients with glioblastoma multiforme

Gliomas are common and frequently malignant tumors of the central nervous system. Recurrent allelic losses of chromosome 22 have been reported in gliomas, indicating tumor-suppressor genes at this location. However, the target genes are still unknown. We applied a high resolution tiling-path chromosome 22 array to a series of 50 glioblastoma samples, with the aim of investigating the underlying abnormalities in both constitutional and tumor-derived DNA. We detected hemizygous deletions in 28% of the tumors (14 of 50), with monosomy 22 (10 of 50) being the predominant pattern. The distribution of overlapping hemizygous deletions delineated two putative tumor-suppressor loci (11.1 and 3.08 Mb in size) across 22q. Most strikingly, we identified two distinct loci affected by regional gains. Both alterations were of germ-line origin and were unique to samples from patients affected with tumors. Analysis of these two amplified regions revealed the presence of two interesting candidate genes: TOP3B and TAFA5. The TOP3B gene encodes a protein that seems to function in the unlinking of parental strands at the final stage of DNA replication and/or in the dissociation of structures in mitotic cells that could lead to recombination. The TAFA5 gene belongs to a novel family of proteins with similarity to chemokines and brain-specific expression. The role of the identified candidate loci should be studied further. Our results demonstrated the power of array-CGH to determine DNA copy number alterations in the context of germ-line- and tumor-specific aberrations.

Phase I/pharmacokinetic study of CCI-779 in patients with recurrent malignant glioma on enzyme-inducing antiepileptic drugs

OBJECTIVES

CCI-779 is an ester of the immunosuppressive agent sirolimus (rapamycin) that causes cell-cycle arrest at G1 via inhibition of key signaling pathways resulting in inhibition of RNA translation. Antitumor activity has been demonstrated using cell lines and animal models of malignant glioma. Patients receiving enzyme-inducing anti-epileptic drugs (EIAEDs) can have altered metabolism of drugs like CCI-779 that are metabolized through the hepatic cytochrome P450 enzyme system. The objectives of this study were to determine the pharmacokinetic profile and the maximum tolerated dose of CCI-779 in patients with recurrent malignant gliioma taking EIAEDs.

STUDY DESIGN

The starting dose of CCI-779 was 250 mg intravenously (IV) administered weekly on a continuous basis. Standard dose escalation was performed until the maximum tolerated dose was established. Toxicity was assessed using the National Cancer Institute common toxicity criteria.

RESULTS

Two of 6 patients treated at the second dose level of 330 mg sustained a dose-limiting toxicity: grade III stomatitis, grade 3 hypercholesterolemia, or grade 4 hypertriglyceridemia. The maximum tolerated dose was reached at 250 mg IV. Pharmacokinetic profiles were similar to those previously described, but the area under the whole blood concentration-time curve of rapamycin was 1.6 fold lower for patients on EIAEDs.

CONCLUSIONS

The recommended phase II dose of CCI 779 for patients on enzyme-inducing antiepileptic drugs is 250 mg IV weekly. A phase II study is ongoing to determine the efficacy of this agent.

Proteomic-based prognosis of brain tumor patients using direct-tissue matrix-assisted laser desorption ionization mass spectrometry

Clinical diagnosis and treatment decisions for a subset of primary human brain tumors, gliomas, are based almost exclusively on tissue histology. Approaches for glioma diagnosis can be highly subjective due to the heterogeneity and infiltrative nature of these tumors and depend on the skill of the neuropathologist. There is therefore a critical need to develop more precise, non-subjective, and systematic methods to classify human gliomas. To this end, mass spectrometric analysis has been applied to these tumors to determine glioma-specific protein patterns. Protein profiles have been obtained from human gliomas of various grades through direct analysis of tissue samples using matrix-assisted laser desorption ionization mass spectrometry (MS). Statistical algorithms applied to the MS profiles from tissue sections identified protein patterns that correlated with tumor histology and patient survival. Using a data set of 108 glioma patients, two patient populations, a short-term and a long-term survival group, were identified based on the tissue protein profiles. In addition, a subset of 57 patients diagnosed with high-grade, grade IV, malignant gliomas were analyzed and a novel classification scheme that segregated short-term and long-term survival patients based on the proteomic profiles was developed. The protein patterns described served as an independent indicator of patient survival. These results show that this new molecular approach to monitoring gliomas can provide clinically relevant information on tumor malignancy and is suitable for high-throughput clinical screening.

Clinical significance of EGFR amplification and the aberrant EGFRvIII transcript in conventionally treated astrocytic gliomas

The aim of this study was to evaluate the clinical value of assessing epidermal growth factor receptor (EGFR) amplification and the common 5' rearrangement of EGFR resulting in the EGFRvIII transcript in astrocytic gliomas. Data from 221 tumours were correlated with patient survival. The majority of previous studies evaluated amplification alone and provided contradictory results. Amplification was analysed by a densitometry of Southern blot analysis or quantitative polymerase chain reaction (PCR). EGFR transcripts were examined by reverse transcription PCR and subsequent sequencing. A ribonuclease (RNase) protection assay was carried out on a subgroup to confirm PCR results. Amplification of EGFR was found in 41% (65/160) of glioblastomas (GBs) and 10% (4/41) of anaplastic astrocytomas (AAs). The EGFRvIII rearrangement was identified in 54% (35/65) of GBs and 75% (3/4) of AAs with amplification, as well as in 8% (8/95) of GBs and 5% (2/37) of AAs without amplification (confirmed by RNase protection assay). There were no abnormalities of the EFGR or its transcript in grade II astrocytoma (AII). We found no significant association between EGFR amplification or rearrangement, and age or survival in the 160 GB patients. We noted a tendency towards decreased survival with any EGFR abnormality in the 41 patients with AAs. This was most marked in the five cases with the EGFRvIII transcript (p=0.069), but these were significantly older than those without (p=0.023). No abnormalities of EGFR were identified in AII patients. We conclude that neither EGFR amplification nor the presence of the EGFRvIII transcript predicts patient outcome in conventionally treated GBs. However, in AAs, although uncommon, EGFR aberrations appear to be associated with shorter survival.

Reduced Expression of PTEN Protein and Its Prognostic Implications in Invasive Ductal Carcinoma of the Breast

OBJECTIVE

The PTEN tumor suppressor gene has been demonstrated to be inactivated in a variety of human tumors. In breast cancer, the PTEN gene mutation is not commonly found whereas loss of heterozygosity affecting the PTEN locus is frequently found. The aim of this study was to analyze PTEN protein expression in breast cancer and to evaluate the prognostic significance of PTEN protein expression.

METHODS

Paraffin-embedded sections ofinvasive ductal carcinoma of the breast were immunohistochemically stained for PTEN protein expression in 236 breast cancers. The immunohistochemical expression of breast cancer cells was judged to be either normal or reduced compared with the PTEN protein expression of the normal mammary gland.

RESULTS

The expression of PTEN protein was found to have decreased in 67 (28%) of 236 breast cancers. The reduced expression correlated with lymph node metastasis (p = 0.0371), but not with tumor size, nuclear grade, MIB-1 counts or p53 protein expression. Univariate analysis indicated that patients with a reduced PTEN expression had a shorter disease-free survival (DFS) than those with a normal PTEN expression (p = 0.0174). Univariate analyses also determined tumor size, lymph node metastases, nuclear grade, MIB-1 counts, p53 protein as well as PTEN protein expression to be significant factors for DFS, while multivariate analysis determined lymph node metastases and the MIB-1 counts to be independent significant factors for DFS.

CONCLUSIONS

The inactivation of PTEN, demonstrated by a reduced expression of PTEN protein by immunohistochemistry, was found in about one third of all breast cancers. The reduced expression of PTEN protein correlated with lymph node metastases and a worse prognosis in the patients with breast cancer.

YKL-40 expression is associated with poorer response to radiation and shorter overall survival in glioblastoma

PURPOSE

YKL-40 is a secreted protein that has been reported to be overexpressed in epithelial cancers and gliomas, although its function is unknown. Previous data in a smaller sample set suggested that YKL-40 was a marker associated with a poorer clinical outcome and a genetically defined subgroup of glioblastoma. Here we test these findings in a larger series of patients with glioblastoma, and in particular, determine if tumor YKL-40 expression is associated with radiation response.

EXPERIMENTAL DESIGN

Patients (n=147) with subtotal resections were studied for imaging-assessed changes in tumor size in serial studies following radiation therapy. An additional set (n=140) of glioblastoma patients who underwent a gross-total resection was tested to validate the survival association and extend them to patients with minimal residual disease.

RESULTS

In the subtotal resection group, higher YKL-40 expression was significantly associated with poorer radiation response, shorter time to progression and shorter overall survival. The association of higher YKL-40 expression with poorer survival was validated in the gross-total resection group. In multivariate analysis with both groups combined (n = 287), YKL-40 was an independent predictor of survival after adjusting for patient age, performance status, and extent of resection. YKL-40 expression was also compared with genetically defined subsets of glioblastoma by assessing epidermal growth factor receptor amplification and loss at chromosome 10q, two of the common recurring aberrations in these tumors, using fluorescent in situ hybridization. YKL-40 was significantly associated with 10q loss.

CONCLUSIONS

The findings implicate YKL-40 as an important marker of therapeutic response and genetic subtype in glioblastomas and suggest that it may play an oncogenic role in these tumors.

Study of a novel brain relatively specific gene LRRC4 involved in glioma tumorigenesis suppression using the Tet-on system

LRRC4 is a novel relatively specific gene, which displays significant down-regulation in primary brain tumor biopsies and has the potential to suppress brain tumor growth. In this study, we investigated the growth inhibitory effect of LRRC4 on tumorigencity in vivo and on cell proliferation in vitro by a tetracycline-inducible expression system. Results showed that LRRC4 significantly reduced the growth and malignant grade of xenografts arising from glioblastoma U251MG cells. Cell proliferation was markedly inhibited after U251MG Tet-on-LRRC4 cell induction with doxycycline. Flow cytometry and Western blot analysis demonstrated that LRRC4 mediated a delay of the cell cycle in late G1, possibly through up-regulating the expressions of p21Waf1/cip1 and p27Kip1 and down-regulating the expressions of cyclin-dependent kinase 2, retinoblastoma protein and epidermal growth factor receptors. Together, these findings provide clues to the function of LRRC4 as a negative regulator of cell growth and underscore a link between the above-mentioned cyclins, cyclin-associated molecules and tumorigenicity.

Prognostic effect of epidermal growth factor receptor and EGFRvIII in glioblastoma multiforme patients

PURPOSE

The epidermal growth factor receptor (EGFR) is overexpressed in approximately 50% to 60% of glioblastoma multiforme tumors, and the most common EGFR mutant, EGFRvIII, is expressed in 24% to 67% of cases. We sought to determine whether glioblastoma multiforme expression of either overexpressed wild-type EGFR or the mutant EGFRvIII is an independent predictor of overall patient survival.

EXPERIMENTAL DESIGN

Glioblastoma multiforme patients (n = 196) underwent a > or =95% volumetric tumor resection followed by conformal radiation. Their EGFR and EGFRvIII status was determined by immunohistochemistry and survival analyses were done.

RESULTS

In our study of glioblastoma multiforme patients, 46% (n = 91) failed to express EGFR, 54% (n = 105) had overexpression of the wild-type EGFR, and 31% (n = 61) also expressed the EGFRvIII. Patients within groups expressing the EGFR, EGFRvIII, or lacking EGFR expression did not differ in age, sex, Karnofsky performance scale score, extent of tumor resection, or radiation. The median overall survival times for patients with tumors having EGFR expression absent, overexpressed only, or mutant (EGFRvIII) were 0.96, 0.98, and 1.07 years, respectively. However, for patients surviving > or =1 year, these values were 2.03, 2.02, and 1.21 years (P < 0.0001; log-rank test comparing EGFRvIII with all others). This effect remained significant in the multivariate analysis after adjustment for all other cofactors including age and Karnofsky performance scale score (rate ratio 4.34; 95% confidence interval, 2.21-8.51).

CONCLUSIONS

Neither the overexpressed wild-type EGFR nor EGFRvIII was an independent predictor of median overall survival in this selected cohort of patients who underwent extensive tumor resection. However, in patients surviving > or =1 year, the expression of EGFRvIII was an independent negative prognostic indicator.

Novel therapeutics in adult malignant brain gliomas

Malignant gliomas are the most frequent and most malignant intracranial neoplasms. In spite of extensive clinical trials and irrespective of aggressive surgery, radiotherapy and chemotherapy, the outcome is very poor and limited progress has been made in the last three decades. Several innovative targeted molecular therapies that are tailored to deregulate the signalling pathways involved in malignant progression have opened new and challenging treatment opportunities and offer hope for an improved outcome in the future. Furthermore, in the field of conventional cytotoxic agents, new drugs or combinations are continuously investigated, widening the therapeutic armamentarium. This paper reviews this rapidly evolving field, focuses on the results of the use of these agents in clinical trials and discusses the main methodological challenges that need to be dealt with before relevant progress in the outcome of malignant gliomas can be yielded.

Phase II trial of temsirolimus (CCI-779) in recurrent glioblastoma multiforme: a North Central Cancer Treatment Group Study

BACKGROUND

Temsirolimus (CCI-779) is a small-molecule inhibitor of the mammalian target of rapamycin (mTOR) and represents a rational therapeutic target against glioblastoma multiforme (GBM).

METHODS

Recurrent GBM patients with < or = 1 chemotherapy regimen for progressive disease were eligible. Temsirolimus was administered in a 250-mg intravenous dose weekly.

RESULTS

Sixty-five patients were treated. The incidence of grade 3 or higher nonhematologic toxicity was 51%, and consisted mostly of hypercholesterolemia (11%), hypertriglyceridemia (8%), and hyperglycemia (8%). Grade 3 hematologic toxicity was observed in 11% of patients. Temsirolimus peak concentration (Cmax), and sirolimus Cmax and area under the concentration-time curve were decreased in patients receiving p450 enzyme-inducing anticonvulsants (EIACs) by 73%, 47%, and 50%, respectively, but were still within the therapeutic range of preclinical models. Twenty patients (36%) had evidence of improvement in neuroimaging, consisting of decrease in T2 signal abnormality +/- decrease in T1 gadolinium enhancement, on stable or reduced steroid doses. Progression-free survival at 6 months was 7.8% and median overall survival was 4.4 months. Median time to progression (TTP) for all patients was 2.3 months and was significantly longer for responders (5.4 months) versus nonresponders (1.9 months). Development of grade 2 or higher hyperlipidemia in the first two treatment cycles was associated with a higher percentage of radiographic response (71% v 31%; P = .04). Significant correlation was observed between radiographic improvement and high levels of phosphorylated p70s6 kinase in baseline tumor samples (P = .04).

CONCLUSION

Temsirolimus is well tolerated in recurrent GBM patients. Despite the effect of EIACs on temsirolimus metabolism, therapeutic levels were achieved. Radiographic improvement was observed in 36% of temsirolimus-treated patients, and was associated with significantly longer TTP. High levels of phosphorylated p70s6 kinase in baseline tumor samples appear to predict a patient population more likely to derive benefit from treatment. These findings should be validated in other studies of mTOR inhibitors.

Molecular diagnostics in central nervous system tumors

Central nervous system (CNS) neoplasms can be diagnostically challenging, due to remarkably wide ranges in histologic appearance, biologic behavior, and therapeutic approach. Nevertheless, accurate diagnosis is the critical first step in providing optimal patient care. As with other oncology-based specialties, there is a rapidly expanding interest and enthusiasm for identifying and utilizing new biomarkers to enhance the day-to-day practice of surgical neuropathology. In this regard, the field is primed by recent advances in basic research, elucidating the molecular mechanisms of tumorigenesis and progression in the most common adult and pediatric brain tumors. Thus far, few have made the transition into routine clinical practice, the most notable example being 1p and 19q testing in oligodendroglial tumors. However, the field is rapidly evolving and many other biomarkers are likely to emerge as useful ancillary diagnostic, prognostic, or therapeutic aids. The goal of this article is to highlight the most common genetic alterations currently implicated in CNS tumors, focusing most on those that are either already in common use in ancillary molecular diagnostics testing or are likely to become so in the near future.

The treatment of malignant gliomas

The optimal management of patients with malignant gliomas begins with the accurate determination of the pathologic diagnosis based on adequate sampling of the tumor. Clear differences in prognosis and therapeutic options have been established for the various tumor grades and cellular classification. Current recommendations, on the basis of the results of a recent phase III randomized trial, are that patients with glioblastoma should have maximal surgical resection followed by concurrent radiation and chemotherapy with temozolomide. It is further recommended that patients then be treated with 6 to 12 months of adjuvant temozolomide. However, despite the shown improvement in survival with this chemoradiation regimen, the impact on outcome is modest. It is increasingly evident that a greater understanding of the molecular mechanisms of gliomagenesis is needed to improve treatments for these patients. Recent and ongoing investigations strongly indicate that specific molecular markers tremendously impact prognosis and often can predict response to treatment. For example, allelic loss of the 1p and 19q chromosome arms predicts a dramatic improvement in response to treatment and survival for tumors histologically classified as anaplastic oligodendroglioma. Future advances for treating primary brain tumors likely will be directly related to our ability to molecularly subcategorize tumors and customize therapy based on the molecular profile within each histologic type and grade of tumor. This is evident in preliminary data indicating that inactivation of the methyl guanine methyltransferase gene by hypermethylation of the promoter region specifically predicts a better tumor response rate to chemotherapies that alkylate DNA as their mechanism of action. Similarly, elucidation of overly active signal transduction pathways within tumor cells may provide an opportunity to select the optimal therapeutic regimen composed of modulators of these pathways, analogous to restricting the use of trastuzumab to breast cancers expressing the Her-2 receptor. Advances in treating primary malignant brain tumors will likely depend on collaborative clinical trials that are designed to select patients on the basis of histologic and molecular characteristics and to determine the optimal biologic dose of the best agent that can treat each specific tumor type.

The expression of epidermal growth factor receptor results in a worse prognosis for patients with rectal cancer treated with preoperative radiotherapy: a multicenter, retrospective analysis

BACKGROUND AND PURPOSE

Expression of epidermal growth factor receptor (EGFR) is observed in 50-70% of colorectal carcinoma and is associated with poor prognosis. The aim of this study was to determine the prognostic value of EGFR status before radiotherapy in a group of patients with locally advanced rectal cancer treated with preoperative radiotherapy.

PATIENTS AND METHODS

Eighty-seven patients were studied retrospectively. Treatment consisted of pelvic radiotherapy, in 50 patients with concomitant chemotherapy and surgical resection. Immunohistochemistry for EGFR was determined at the preradiation biopsy and in the resected specimens. Immunohistochemical analysis for EGFR expression was evaluated according to extension and staining intensity. We defined positive staining (EGFR positive), when extension was 5% or more.

RESULTS

A total of 52 of 87 tumors showed EGFR positive status at biopsy (60%) and EGFR expression was associated neither with clinical tumor stage nor with clinical nodal stage. EGFR positive expression was linked to a lack of pathologic complete response to preoperative radiotherapy (P=0.006). Disease-free survival was lower among patients with EGFR positive status before radiotherapy (P=0.003). In a multivariate analysis EGFR expression at biopsy was a statistically significant predictor of disease-free survival, RR=2.88(1.1-7.8), P=0.036.

CONCLUSIONS

EGFR is expressed in a significant number of rectal tumors. EGFR-positive expression before radiotherapy is an indicator for poor response and low disease-free survival.

Genetic analyses for predictors of radiation response in glioblastoma

PURPOSE

Radiotherapy (RT) for patients with glioblastoma improves survival and is recommended for nearly all patients with this diagnosis. However, the response to RT is variable in this patient population. Prior studies have suggested that underlying genetic alterations in the tumor may account for some of this treatment-related heterogeneity. It has been previously reported that epidermal growth factor receptor (EGFR) gene amplification and TP53 mutation correlate with the response to RT in patients with glioblastoma.

METHODS AND MATERIALS

We sought to identify molecular markers that could predict the response to RT, progression-free survival after RT, and overall survival among 75 glioblastoma patients treated with RT at a single institution. Genetic analyses assessed EGFR amplification, TP53 mutations, CDKN2A/p16 deletion, and losses of chromosomes 1p, 10q, and 19q.

RESULTS

Unlike previous reports, no association of EGFR amplification with response to RT, progression-free survival, or overall survival was found. Moreover, no association was found between these endpoints and the other genetic alterations assayed (TP53 mutation, CDKN2A/p16 deletion, loss of heterozygosity 1p, loss of heterozygosity 10q, and loss of heterozygosity 19q). However, in accordance with recent observations that the prognostic effects of genetic alterations in glioblastoma may depend on patient age, we observed age-dependent prognostic effects of TP53 and CDKN2A/p16 alterations in our patient population. For patients > or = 57 years old, those harboring TP53 mutations had a decreased overall survival compared with patients without TP53 mutations. Similarly, deletion of CDKN2A/p16 in patients > or = 57 years was associated with decreased progression-free survival after RT and a trend toward a shorter time to progression after RT compared with similar patients without the deletion.

CONCLUSION

These data contrast with previous studies regarding the significant prognostic effect of EGFR with respect to RT response. Although our observations regarding the age-dependent prognostic effects of TP53 and CDKN2A/p16 are consistent with a prior report regarding these alterations, the present results should be considered preliminary, given the small sample size.

Epidermal growth factor receptor amplification does not have prognostic significance in patients with glioblastoma multiforme

PURPOSE

There have been conflicting reports in the literature regarding the prognostic significance of epidermal growth factor receptor (EGFR) amplification in patients with glioblastoma multiforme (GBM). The purpose of this study is to determine the prognostic significance of EGFR amplification in patients with GBM treated at the Cleveland Clinic Foundation.

METHODS AND MATERIALS

A retrospective review of GBM patients treated with surgery at the Cleveland Clinic Foundation was performed. Amplification of EGFR was evaluated with fluorescence in situ hybridization in a total of 107 patients diagnosed between December 1995 and May 2003. In addition to EGFR status, various prognostic factors were evaluated to determine the factors that influenced survival and radiographic response rate. The median follow-up was 9 months.

RESULTS

The overall median survival was 9.8 months, with a 1-year survival of 40%. Of the 107 patients in whom EGFR status was evaluated, 36 (33.6%) were found to have EGFR amplification. On multivariate analysis, median survival was found to be significantly improved for patients with age < 60 (12.6 months vs. 8 months, p = 0.0061), patients with Karnofsky Performance Status > or = 70 (12.1 months vs. 4.4 months, p < 0.0001), patients who had undergone subtotal resection or gross total resection (11.1 months vs. 4.1 months, p = 0.002), and patients who received a radiation dose > or = 60 Gy compared with no radiation (12.7 months vs. 3 months, p < 0.0001). There was no association of EGFR amplification with survival. When stratified by age (< 60 vs. > or = 60), EGFR status still did not reach statistical significance in predicting for survival. For the 81 patients who had radiographic follow-up, the 1-year overall local control was 14%. On univariate analysis, only treatment with radiation (< 60 Gy vs. > or = 60 Gy vs. no radiation, p = 0.03) was found to predict for improved local control. Treatment with radiation did not remain statistically significant on multivariate analysis.

CONCLUSION

Epidermal growth factor receptor amplification was not found to be a significant prognostic indicator of overall survival or radiographic local control in patients with GBM treated with surgery at the Cleveland Clinic Foundation. Further studies are needed to fully delineate the significance of this molecular marker in patients with GBM.

Population-Based Studies on Incidence, Survival Rates, and Genetic Alterations in Astrocytic and Oligodendroglial Gliomas

Published data on prognostic and predictive factors in patients with gliomas are largely based on clinical trials and hospital-based studies. This review summarizes data on incidence rates, survival, and genetic alterations from population-based studies of astrocytic and oligodendrogliomas that were carried out in the Canton of Zurich, Switzerland (approximately 1.16 million inhabitants). A total of 987 cases were diagnosed between 1980 and 1994 and patients were followed up at least until 1999. While survival rates for pilocytic astrocytomas were excellent (96% at 10 years), the prognosis of diffusely infiltrating gliomas was poorer, with median survival times (MST) of 5.6 years for low-grade astrocytoma WHO grade II, 1.6 years for anaplastic astrocytoma grade III, and 0.4 years for glioblastoma. For oligodendrogliomas the MSTwas 11.6 years for grade II and 3.5 years for grade III. TP53 mutations were most frequent in gemistocytic astrocytomas (88%), followed by fibrillary astrocytomas (53%) and oligoastrocytomas (44%), but infrequent (13%) in oligodendrogliomas. LOH 1p/19q typically occurred in tumors without TP53 mutations and were most frequent in oligodendrogliomas (69%), followed by oligoastrocytomas (45%), but were rare in fibrillary astrocytomas (7%) and absent in gemistocytic astrocytomas. Glioblastomas were most frequent (3.55 cases per 100,000 persons per year) adjusted to the European Standard Population, amounting to 69% of total incident cases. Observed survival rates were 42.4% at 6 months, 17.7% at one year, and 3.3% at 2 years. For all age groups, survival was inversely correlated with age, ranging from an MST of 8.8 months (<50 years) to 1.6 months (>80 years). In glioblastomas, LOH 10q was the most frequent genetic alteration (69%), followed by EGFR amplification (34%), TP53 mutations (31%), p16INK4a deletion (31%), and PTEN mutations (24%). LOH 10q occurred in association with any of the other genetic alterations, and was the only alteration associated with shorter survival of glioblastoma patients. Primary (de novo) glioblastomas prevailed (95%), while secondary glioblastomas that progressed from low-grade or anaplastic gliomas were rare (5%). Secondary glioblastomas were characterized by frequent LOH 10q (63%) and TP53 mutations (65%). Of the TP53 mutations in secondary glioblastomas, 57% were in hot-spot codons 248 and 273, while in primary glioblastomas, mutations were more evenly distributed. G:C-->A:T mutations at CpG sites were more frequent in secondary than primary glioblastomas, suggesting that the acquisition of TP53 mutations in these glioblastoma subtypes may occur through different mechanisms.

Immunohistochemically determined total epidermal growth factor receptor levels not of prognostic value in newly diagnosed glioblastoma multiforme: Report from the Radiation Therapy Oncology Group

PURPOSE

The Radiation Therapy Oncology Group (RTOG) performed an analysis of patterns of immunohistochemically detected total epidermal growth factor receptor (EGFR) protein expression levels and their prognostic significance on archival tissue in newly diagnosed glioblastoma multiforme (GBM) patients from prior prospective RTOG clinical trials.

METHODS AND MATERIALS

Patients in this study had been treated on previous RTOG GBM trials (RTOG 7401, 7918, 8302, 8409, 9006, 9305, 9602, and 9806). Tissue microarrays were prepared from 155 patients enrolled in these trials. These specimens were stained using a mouse monoclonal antibody specific for the extracellular binding domain of EGFR to detect total EGFR (including both wild-type phosphorylated and wild-type unphosphorylated isoforms with some cross-reactivity with EGFRvIII). The intensity of total EGFR protein expression was measured by computerized quantitative image analysis using the SAMBA 4000 Cell Image Analysis System. The parameters measured were the mean optical densities over the labeled areas and the staining index, which represents the proportion of stained area relative to the mean stain concentration. Both parameters were correlated with the clinical outcome.

RESULTS

No differences in either overall or progression-free survival could be demonstrated by the mean optical density class or mean optical density quartile or the staining index of total EGFR immunostaining among the representative RTOG GBM cases.

CONCLUSION

Total EGFR protein expression levels, as measured immunohistochemically, do not appear to be of prognostic value in newly diagnosed GBM patients. Given the accumulating clinical evidence of the activity of anti-EGFR agents in GBM and the preclinical data suggesting the important role of downstream mediators as effectors of EGFR signaling, the RTOG is conducting additional investigations into the prognostic value of activation patterns of EGFR signaling, both at the level of the receptor (e.g., EGFRvIII, phospho-EGFR) and at the level of downstream signal transduction pathways (e.g., PI3K, Ras/MAPK pathways).

Gene Expression Profiling and Genetic Markers in Glioblastoma Survival

Despite the strikingly grave prognosis for older patients with glioblastomas, significant variability in patient outcome is experienced. To explore the potential for developing improved prognostic capabilities based on the elucidation of potential biological relationships, we did analyses of genes commonly mutated, amplified, or deleted in glioblastomas and DNA microarray gene expression data from tumors of glioblastoma patients of age >50 for whom survival is known. No prognostic significance was associated with genetic changes in epidermal growth factor receptor (amplified in 17 of 41 patients), TP53 (mutated in 11 of 41 patients), p16INK4A (deleted in 15 of 33 patients), or phosphatase and tensin homologue (mutated in 15 of 41 patients). Statistical analysis of the gene expression data in connection with survival involved exploration of regression models on small subsets of genes, based on computational search over multiple regression models with cross-validation to assess predictive validity. The analysis generated a set of regression models that, when weighted and combined according to posterior probabilities implied by the statistical analysis, identify patterns in expression of a small subset of genes that are associated with survival and have value in assessing survival risks. The dominant genes across such multiple regression models involve three key genes-SPARC (Osteonectin), Doublecortex, and Semaphorin3B-which play key roles in cellular migration processes. Additional analysis, based on statistical graphical association models constructed using similar computational analysis methods, reveals other genes which support the view that multiple mediators of tumor invasion may be important prognostic factor in glioblastomas in older patients.

Pathology and molecular genetics of astrocytic gliomas

Astrocytic gliomas are the most common primary brain tumours. Here we summarize the characteristic neuropathological features of the different types of astrocytic neoplasms according to the World Health Organization classification of tumours of the nervous system. In addition, we report on the present state of the art concerning the molecular genetics of these tumours. Over the past 20 years a number of recurrent chromosomal,genetic and epigenetic alterations have been found to be associated with the different histological types and malignancy grades of astrocytic tumours. However, we are still far from understanding the complex mechanisms that underly tumour initiation and progression in the individual case. Furthermore, the clinical significance of molecular parameters for the diagnostic and prognostic assessment of astrocytic gliomas is still limited. Therefore further investigation of the molecular mechanisms underlying oncogenesis and progression of these most common brain tumours is necessary to improve their diagnostic assessment and to devise novel, individually tailored treatment strategies.

Molecular stratification of diagnostically challenging high-grade gliomas composed of small cells: the utility of fluorescence in situ hybridization

PURPOSE

There is considerable morphologic overlap between various entities of high-grade gliomas, and, therefore, a further planning of their optimal treatment is a controversial issue. The aim of this study was molecular stratification of morphologically ambiguous high-grade gliomas composed from small cells. Fluorescence in situ hybridization (FISH) with commercially available probes was used for this purpose.

EXPERIMENTAL DESIGN

We analyzed a set of 114 high-grade small-cell gliomas that were difficult to interpret diagnostically because of their distinct cytological origin. FISH assay with locus probes for EGFR, p16, PTEN, and 1p and 19q was done.

RESULTS

Morphologically uniform high-grade gliomas composed of small cells varied greatly in terms of molecular features and clinical outcome. Four clinically relevant subsets of patients whose tumors showed distinctly different molecular profiles were identified as follows: (a) 13 patients whose tumors exhibited no discernable molecular alterations (5-year survival rate, 83%); (b) 20 patients whose tumors harbored either 1p/19q codeletion or isolated deletion of 19q unaccompanied by other molecular abnormalities (5-year survival rate, 59%); (c) 35 patients whose tumors showed p16 and/or PTEN deletions unaccompanied by EGFR amplification (5-year survival rate, 8%); and (d) 46 patients whose tumors harbored EGFR amplification (5-year survival rate, 0).

CONCLUSIONS

The FISH method provides clinically useful information in the molecular analysis of morphologically ambiguous malignant small-cell gliomas that could potentially enhance the quality of patient care.

Rottlerin sensitizes glioma cells to TRAIL-induced apoptosis by inhibition of Cdc2 and the subsequent downregulation of survivin and XIAP

In the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-resistant glioma cells, treatment with TRAIL in combination with subtoxic doses of rottlerin induced rapid apoptosis. While the proteolytic processing of procaspase-3 by TRAIL was partially blocked in these cells, treatment with rottlerin efficiently recovered TRAIL-induced activation of caspases. Treatment with rottlerin significantly decreased Cdc2 activity through the downregulation of cyclin A, cyclin B, and Cdc2 proteins, whereas the sensitizing effect of rottlerin on TRAIL-induced apoptosis was independent of PKCdelta activity. Furthermore, treatment with rottlerin downregulated the protein levels of survivin and X-chromosome-linked IAP (XIAP), two major caspase inhibitors. Forced expression of Cdc2 together with cyclin B attenuated rottlerin-potentiated TRAIL-induced apoptosis by over-riding the rottlerin-mediated downregulation of survivin and XIAP protein levels. Taken together, inhibition of Cdc2 activity and the subsequent downregulation of survivin and XIAP by subtoxic doses of rottlerin contribute to amplification of caspase cascades, thereby overcoming resistance of glioma cells to TRAIL-mediated apoptosis. Since rottlerin can sensitize Bcl-2- or Bcl-xL-overexpressing glioma cells but not human astrocytes to TRAIL-induced apoptosis, this combined treatment may offer an attractive strategy for safely treating resistant gliomas.

Integrated Array-Comparative Genomic Hybridization and Expression Array Profiles Identify Clinically Relevant Molecular Subtypes of Glioblastoma

Glioblastoma, the most aggressive primary brain tumor in humans, exhibits a large degree of molecular heterogeneity. Understanding the molecular pathology of a tumor and its linkage to behavior is an important foundation for developing and evaluating approaches to clinical management. Here we integrate array-comparative genomic hybridization and array-based gene expression profiles to identify relationships between DNA copy number aberrations, gene expression alterations, and survival in 34 patients with glioblastoma. Unsupervised clustering on either profile resulted in similar groups of patients, and groups defined by either method were associated with survival. The high concordance between these separate molecular classifications suggested a strong association between alterations on the DNA and RNA levels. We therefore investigated relationships between DNA copy number and gene expression changes. Loss of chromosome 10, a predominant genetic change, was associated not only with changes in the expression of genes located on chromosome 10 but also with genome-wide differences in gene expression. We found that CHI3L1/YKL-40 was significantly associated with both chromosome 10 copy number loss and poorer survival. Immortalized human astrocytes stably transfected with CHI3L1/YKL-40 exhibited changes in gene expression similar to patterns observed in human tumors and conferred radioresistance and increased invasion in vitro. Taken together, the results indicate that integrating DNA and mRNA-based tumor profiles offers the potential for a clinically relevant classification more robust than either method alone and provides a basis for identifying genes important in glioma pathogenesis.

Genetic pathways to glioblastomas

Glioblastomas, the most frequent and malignant human brain tumors, may develop de novo (primary glioblastoma) or by progression from low-grade or anaplastic astrocytoma (secondary glioblastoma). These glioblastoma subtypes constitute distinct disease entities that affect patients of different ages and develop through different genetic pathways. Our recent population-based study in the Canton of Zürich, Switzerland, shows that primary glioblastomas develop in older patients (mean age, 62 years) and typically show LOH on chromosome 10q (69%) and other genetic alterations (EGFR amplification, TP53 mutations, p16INK4a deletion, and PTEN mutations) at frequencies of 24-34%. Secondary glioblastomas develop in younger patients (mean, 45 years) and frequently show TP53 mutations (65%) and LOH 10q (63%). Common to both primary and secondary glioblastoma is LOH on 10q, distal to the PTEN locus; a putative suppressor gene at 10q25-qter may be responsible for the glioblastoma phenotype. Of the TP53 point mutations in secondary glioblastomas, 57% were located in hotspot codons 248 and 273, while in primary glioblastomas, mutations were more widely distributed. Furthermore, G:C-->A:T mutations at CpG sites were more frequent in secondary than in primary glioblastomas (56% vs 30%). These data suggest that the TP53 mutations in these glioblastoma subtypes arise through different mechanisms. There is evidence that G:C-->A:T transition mutations at CpG sites in the TP53 gene are significantly more frequent in low-grade astrocytomas with promoter methylation of the O6-methylguanine-DNA methyltransferase (MGMT) gene than in those without methylation. This suggests that, in addition to deamination of 5-methylcytosine (the best known mechanism of formation of G:C-->A:T transitions at CpG sites), involvement of alkylating agents that produce O6-methylguanine or related adducts recognized by MGMT cannot be excluded in the pathway leading to secondary glioblastomas.

Comparative genomic hybridization analysis of astrocytomas: prognostic and diagnostic implications

Astrocytoma is comprised of a group of common intracranial neoplasms that are classified into four grades based on the World Health Organization histological criteria and patient survival. To date, histological grade, patient age, and clinical performance, as reflected in the Karnofsky score, are the most reliable prognostic predictors. Recently, there has been a significant effort to identify additional prognostic markers using objective molecular genetic techniques. We believe that the identification of such markers will characterize new chromosomal loci important in astrocytoma progression and aid clinical diagnosis and prognosis. To this end, our laboratory used comparative genomic hybridization to identify DNA sequence copy number changes in 102 astrocytomas. Novel losses of 19p loci were detected in low-grade pilocytic astrocytomas and losses of loci on 9p, 10, and 22 along with gains on 7, 19, and 20 were detected in a significant proportion of high-grade astrocytomas. The Cox proportional hazards statistical modeling showed that the presence of +7q and -10q comparative genomic hybridization alterations significantly increased a patient's risk of dying, independent of histological grade. This investigation demonstrates the efficacy of comparative genomic hybridization for identifying tumor suppressor and oncogene loci in different astrocytic grades. The cumulative effect of these loci is an important consideration in their diagnostic and prognostic implications.

Loss of the AP-2α Transcription Factor Is Associated with the Grade of Human Gliomas

Purpose: The activator protein (AP)-2α transcription factor plays a crucial role in the progression of several human tumors, including malignant melanoma, prostate, and breast cancer. Loss of AP-2α results in deregulation of several genes with AP-2α binding motifs such as E-cadherin, p21WAF1, MMP-2, MCAM/MUC18, VEGF, and c-KIT. The purpose of our study was to determine AP-2α expression distribution among grades of gliomas and any possible effect on prognosis.

Experimental Design: A tissue microarray was assembled from all surgical glioma cases with available tissue samples at M.D. Anderson Cancer Center since 1986 to include 72 glioblastomas, 49 anaplastic astrocytomas, 9 low-grade astrocytoma, 37 oligodendrogliomas, 37 anaplastic oligodendrogliomas, 15 mixed oligoastrocytomas, 20 anaplastic mixed oligoastrocytomas, and 7 gliosarcomas. The microarray included normal brain tissue, and AP-2α expression was determined by immunohistochemistry.

Results: AP-2α expression was lost on 99% (P &lt; 0.001) and 98% (P &lt; 0.001) of glioblastomas and anaplastic astrocytomas, respectively, compared with grade 2 astrocytomas and normal brain, all of which (100%) maintained expression of AP-2α. The loss of AP-2α was a negative prognostic indicator within the overall category of gliomas by univariate analysis (rate ratio, 4.30; 95% confidence interval, 2.60-7.10; P &lt; 0.001). However, there was no significant effect of loss of AP-2α expression on survival observed after adjustment for patient age, Karnofsky Performance Scale score, tumor grade, and extent of resection (rate ratio, 1.2; 95% confidence interval, 0.6-2.2; P = 0.6).

Conclusions: AP-2α expression correlates inversely with glioma grade, suggesting a direct role in glioma tumorigenicity, possibly through subsequent deregulation of target genes. Of all the previously characterized markers of progression, the loss of AP-2α would be the most common (96.2%) molecular marker as an astrocytic tumor evolves from grade 2 to 3.

Molecular classification of human gliomas using matrix-based comparative genomic hybridization

Gliomas are the most frequent primary brain tumors and comprise a group of morphologically, biologically and clinically heterogeneous neoplasms. The different glioma types are associated with distinct genetic aberrations, which may provide useful information for tumor classification as well as prediction of prognosis and response to therapy. To facilitate the molecular classification of gliomas, we established a genomic microarray that consists of bacterial artificial chromosome (BAC) and P1-derived artificial chromosome (PAC) clones representing tumor suppressor genes, proto-oncogenes and chromosomal regions frequently gained or lost in gliomas. In addition, reference clones distributed evenly throughout the genome in approximately 15 Mbp intervals were spotted on the microarray. These customized microarrays were used for matrix-based comparative genomic hybridization (matrix CGH) analysis of 70 gliomas. Matrix CGH findings were validated by molecular genetic analyses of candidate genes, loss of heterozygosity studies and chromosomal CGH. Our results indicate that matrix CGH allows for the sensitive and specific detection of gene amplifications as well as low-level copy number gains and losses in clinical glioma samples. Furthermore, molecular classification based on matrix CGH data closely paralleled histological classification and was able to distinguish with few exceptions between diffuse astrocytomas and oligodendrogliomas, anaplastic astrocytomas and anaplastic oligodendrogliomas, anaplastic oligodendrogliomas and glioblastomas, as well as primary and secondary glioblastomas. Thus, matrix CGH is a powerful technique that allows for an automated genomic profiling of gliomas and represents a promising new tool for their molecular classification.

Detrended fluctuation analysis of genome-wide copy number profiles of glioblastomas using array-based comparative genomic hybridization

We examined whole genomic aberrations of biopsied samples from 19 independent glioblastomas by array-based comparative genomic hybridization analysis. The highest frequencies of copy number gains were observed on RFC2 (73.3%), EGFR (63.2%), and FGR, ELN, CDKN1C , FES, TOP2A, and ARSA (57.9% each). The highest frequencies of copy number losses were detected on TBR1 (52.6%), BMI1 (52.6%), EGR2 (47.4%), DMBT1 (47.4%), MTAP (42.1%), and FGFR2 (42.1%). The copy number gains of CDKN1C and INS and the copy number losses of TBR1 were significantly correlated with longer survival of patients. High-level amplifications were identified on EGFR, SAS/CDK4, PDGFRA, MDM2, and ARSA. These genes are assumed to be involved in tumorigenesis or progression of glioblastomas. The first attempts to apply detrended fluctuation analysis to copy number profiles by considering the reading direction as the time axis demonstrated that higher long-term fractal scaling exponents (alpha2) correlated well with longer survival of glioblastoma patients. The present study indicates that array-based comparative genomic hybridization analysis has great potential for assessment of copy number changes and altered chromosomal regions of brain tumors. Furthermore, we show that nonlinear analysis methods of whole genome copy number profiles may provide prognostic information about glioblastoma patients.

Detrended fluctuation analysis of genome-wide copy number profiles of glioblastomas using array-based comparative genomic hybridization

We examined whole genomic aberrations of biopsied samples from 19 independent glioblastomas by array-based comparative genomic hybridization analysis. The highest frequencies of copy number gains were observed on RFC2 (73.3%), EGFR (63.2%), and FGR, ELN, CDKN1C , FES, TOP2A, and ARSA (57.9% each). The highest frequencies of copy number losses were detected on TBR1 (52.6%), BMI1 (52.6%), EGR2 (47.4%), DMBT1 (47.4%), MTAP (42.1%), and FGFR2 (42.1%). The copy number gains of CDKN1C and INS and the copy number losses of TBR1 were significantly correlated with longer survival of patients. High-level amplifications were identified on EGFR, SAS/CDK4, PDGFRA, MDM2, and ARSA. These genes are assumed to be involved in tumorigenesis or progression of glioblastomas. The first attempts to apply detrended fluctuation analysis to copy number profiles by considering the reading direction as the time axis demonstrated that higher long-term fractal scaling exponents (alpha2) correlated well with longer survival of glioblastoma patients. The present study indicates that array-based comparative genomic hybridization analysis has great potential for assessment of copy number changes and altered chromosomal regions of brain tumors. Furthermore, we show that nonlinear analysis methods of whole genome copy number profiles may provide prognostic information about glioblastoma patients.

Anaplastic astrocytoma: diagnosis, prognosis, and management

The designation of a tumor as anaplastic astrocytoma (AA) reflects a distinct histologic classification of malignant glioma characterized by an abundance of pleomorphic astrocytes with evidence of mitosis. Although these tumors are malignant, they have a better prognosis and a higher likelihood of response to treatment than glioblastoma. Despite advances in brain tumor imaging, making an accurate diagnosis requires the evaluation of tumor tissue and is essential for treatment planning. Currently, most patients undergo maximal surgical debulking of tumor followed by external beam radiation, often with subsequent adjuvant chemotherapy. However, despite the use of these treatment modalities, most tumors recur within a few years and these recurrent tumors are more refractory to subsequent therapies. This review examines the diagnosis, prognosis, and treatment of AAs. Ongoing clinical research investigations are also summarized, reflecting advances in our knowledge of the molecular pathogenesis of these tumors and providing hope for significant improvements in patient outcomes.

A four-dimensional simulation model of tumour response to radiotherapy in vivo: parametric validation considering radiosensitivity, genetic profile and fractionation

The aim of this paper is to present the current state of a four-dimensional simulation model of solid tumour growth and response to radiotherapy developed by our group. The most prominent points of the algorithms describing the fundamental biological phenomena involved are outlined. A specific application of the model to a selected clinical case of glioblastoma multiforme is described and comparative studies are performed, using various exploratory values of the model parameters. Qualitative agreement with clinical observations has been achieved. Special emphasis is laid on the variability of radiosensitivity parameters throughout the cell cycle and on the influence of the genetic profile of the tumour on its radiosensitivity. The results of the simulation are three-dimensionally reconstructed. A valuable tool for getting insight into the biology of tumour growth and response to radiotherapy and at the same time an advanced patient specific decision support system is expected to emerge after the completion of the necessary extensive clinical evaluation.

Suppression of invasion in human U87 glioma cells by adenovirus-mediated co-transfer of TIMP-2 and PTEN gene

TIMPs and PTEN are known to be inhibitors of the invasive activities of malignant glioma. But there has been no literature reported concerning the effect of combined gene transfer of these two genes on invasiveness of glioma. This study was designed to evaluate the effect of adenovirus-mediated in vitro gene transfer of tissue inhibitor of metalloproteinases-2 (TIMP-2) and phosphatase and tensin homology deleted on chromosome ten (PTEN) on invasion of human U87 glioma cells. The mRNA and protein expressions of TIMP-2 and PTEN in U87 cells infected with AdTIMP-2 and AdPTEN were determined by RT-PCR and Western blot, respectively. The relative activity of MMP-2 and MMP-9 were measured by Gelatin zymogram and invasion of U87 in vitro were detected using Boyden chamber. The number of invasion cell of U87, U87 infected with Ad-gal, AdPTEN, AdTIMP-2 and AdPTEN/TIMP-2 was 55.63+/-13.27, 48.27+/-14.75, 35.27+/-10.94, 27.37+/-12.81, and 19.17+/-5.45, respectively. In vitro invasiveness of glioma cells was significantly inhibited by infection with AdTIMP-2 and/or AdPTEN, which was not consistent with the change of MMPs activity. And in the combinated group, the inhibition effect was more remarkable than in single group. Our studies suggest that adenovirus-mediated combined TIMP-2 and PTEN gene therapy is possibly useful for anti-invasion therapy of malignant glioma.

Putting the rap on Akt

The protein kinase Akt is activated in a wide variety of cancers, and this activation results in enhanced resistance to apoptosis through multiple mechanisms. This article reviews the control of Akt activation by the opposing actions of the oncogene phosphoinositide 3-kinase (PI3-K) and the tumor suppressor phosphatase and tensin homolog deleted on chromosome 10. The activation of Akt by transforming mutations, such as the amplification of HER-2/neu in breast cancer and the formation of the BCR/ABL fusion gene in chronic myelogenous leukemia, seems to be essential for the transforming activity of these oncogenes. We discuss several of the proposed mechanisms for the antiapoptotic effect of activated Akt, including the inhibition of the proapoptotic protein Bad, downregulation of death receptors, and enhancement of the glycolytic rate. Increased glycolysis is seen in many malignancies and forms the basis for the increasing use of positron emission tomography imaging for diagnosis and staging. Finally, we discuss rapamycin and its analogs, which are now in trials as antineoplastic therapy; these agents show particular promise in tumors in which Akt has been activated.

Protein patterns and proteins that identify subtypes of glioblastoma multiforme

Glioblastoma multiforme (GBM) has been subdivided into two types based on clinical and genetic findings: primary tumors, which arise de novo, and secondary tumors, which progress from lower grade gliomas to GBMs. To analyse this dichotomy at the protein level, we employed selective tissue microdissection to obtain pure populations of tumor cells, which we studied using two-dimensional protein gel electrophoresis (2-DGE) and protein sequencing of select target proteins. Protein patterns were analysed in a blinded manner from the clinical and genetic data. 2-DGE clearly identified two distinct populations of tumors. 2-DGE was reproducible and reliable, as multiple samples analysed from the same patient gave identical results. In addition, we isolated and sequenced 11 proteins that were uniquely expressed in either the primary or the secondary GBMs, but not both. We demonstrate that specific proteomic patterns can be reproducibly identified by two-dimensional gel electrophoresis from limited numbers of selectively procured, microdissected tumor cells and that two patterns of GBMs, primary versus secondary, previously distinguished by clinical and genetic differences, can be recognized at the protein level. Proteins that are expressed distinctively may have important implications for the diagnosis, prognosis, and treatment of patients with GBM.

Altered molecular pathways in gliomas: An overview of clinically relevant issues

Primary central nervous system (CNS) tumors constitute a small fraction of the overall incidence of human cancer, but they represent a major source of cancer-related morbidity and mortality. The most common CNS tumor subtype in adults, high-grade astrocytoma, confers a dismal prognosis with a median survival of only 1 to 2 years. Other common adult CNS tumors, ie, low-grade astrocytomas and oligodendrogliomas, carry a less ominous, yet still poor prognosis. Unfortunately, there has been little progress in extending the survival or quality of life for glioma patients, despite nearly four decades of extensive research. This research has, however, greatly increased our understanding of the underlying molecular biology of these tumors, examples of which include the determination of elevated epidermal growth factor receptor (EGFR) as well as platelet-derived growth factor receptor (PDGF) signaling, and the inactivation of p53 , p16 , and PTEN tumor-suppressor genes (TSGs) that negatively regulate specific enzymatic activities in normal glial cells. Such observations have greatly improved our understanding of the pathogenesis of these tumors and have potential diagnostic as well as therapeutic relevance. With respect to the latter of these two issues, the identification of aberrant enzymatic activities in gliomas has promoted the development of novel therapeutic agents that target specific signaling effectors, and whose inhibition should, in theory, prove to be cytostatic, if not cytotoxic, to tumor cells. Several clinical trials are currently underway for testing these therapeutic agents in patients with primary brain tumors, and it is hoped that the targeting of pro-tumorigenic enzymatic activities will lead to better patient outcomes. In this review, we will describe the most pertinent genetic and signaling pathway alterations that are clinically relevant to the management of glial tumors.

Genetic Pathways to Glioblastoma

We conducted a population-based study on glioblastomas in the Canton of Zurich, Switzerland (population, 1.16 million) to determine the frequency of major genetic alterations and their effect on patient survival. Between 1980 and 1994, 715 glioblastomas were diagnosed. The incidence rate per 100,000 population/year, adjusted to the World Standard Population, was 3.32 in males and 2.24 in females. Observed survival rates were 42.4% at 6 months, 17.7% at 1 year, and 3.3% at 2 years. For all of the age groups, younger patients survived significantly longer, ranging from a median of 8.8 months (<50 years) to 1.6 months (>80 years). Loss of heterozygosity (LOH) 10q was the most frequent genetic alteration (69%), followed by EGFR amplification (34%), TP53 mutations (31%), p16(INK4a) deletion (31%), and PTEN mutations (24%). LOH 10q occurred in association with any of the other genetic alterations and was predictive of shorter survival. Primary (de novo) glioblastomas prevailed (95%), whereas secondary glioblastomas that progressed from low-grade or anaplastic gliomas were rare (5%). Secondary glioblastomas were characterized by frequent LOH 10q (63%) and TP53 mutations (65%). Of the TP53 mutations in secondary glioblastomas, 57% were in hotspot codons 248 and 273, whereas in primary glioblastomas, mutations were more equally distributed. G:C-->A:T mutations at CpG sites were more frequent in secondary than primary glioblastomas (56% versus 30%; P = 0.0208). This suggests that the acquisition of TP53 mutations in these glioblastoma subtypes occurs through different mechanisms.

Immunohistochemical detection of EGFRvIII in high malignancy grade astrocytomas and evaluation of prognostic significance

The purpose of this study was to establish an accurate and accessible immunohistochemical (IHC) method for detecting vIII Egf receptor and to assess the prognostic significance of the method as applied to the detection of vIII in malignant astrocytomas. The accuracy of the method was determined by comparing vIII immunoreactivity in formalin-fixed and paraffin-embedded tumor sections versus RT-PCR results from the analysis of RNA extracted from corresponding frozen specimens. RT-PCR revealed vIII transcript in 18 of 44 cases in this series, and IHC analysis of matched formalin-fixed and paraffin-embedded sections showed EGFRvIII reactivity in each of these 18 tumors, as well as 1 additional tumor that was negative for vIII transcript. EGFR amplification was evident in all tumors expressing vIII; none of the 15 tumors lacking amplified EGFR were positive for vIII transcript or vIII protein. IHC analysis for vill expression was next applied to a large series of anaplastic astrocytomas (AAs) and glioblastoma multiforme (GBMs) from clinical trial patients with complete follow-up and that had been previously examined by FISH for amplified EGFR. Among the GBMs, vIII detection by IHC was determined in 19 of 46 cases (41.3%) with EGFR amplification, and in only 3 of 59 tumors lacking amplified EGFR (5.1%). Among the AAs, vIII expression was observed in 3 of 14 cases with amplified EGFR (21.4%) and in 6 of 49 cases without EGFR amplification (12.2%). GBM and AA patient survival analysis as a function of vIII expression showed contrasting results, with vIII positivity having no association with survival among GBM patients (p = 0.84), but being highly associated with reduced survival among AA patients (p = 0.0016). This latter finding, though quite possibly a result of vIII's association with increasing AA patient age, suggests that vIII IHC will be useful for identifying and/or confirming the identity of malignant astrocytomas whose clinical behavior is consistent with that of GBM.

The Biology and Clinical Relevance of the PTEN Tumor Suppressor Pathway

Genetic alterations targeting the PTEN tumor suppressor gene are among the most frequently noted somatic mutations in human cancers. Such lesions have been noted in cancers of the prostate and endometrium and in glioblastoma multiforme, among many others. Moreover, germline mutation of PTEN leads to the development of the related hereditary cancer predisposition syndromes, Cowden disease, and Bannayan-Zonana syndrome, wherein breast and thyroid cancer incidence is elevated. The protein product, PTEN, is a lipid phosphatase, the enzymatic activity of which primarily serves to remove phosphate groups from key intracellular phosphoinositide signaling molecules. This activity normally serves to restrict growth and survival signals by limiting activity of the phosphoinositide-3 kinase (PI3K) pathway. Multiple lines of evidence support the notion that this function is critical to the ability of PTEN to maintain cell homeostasis. Indeed, the absence of functional PTEN in cancer cells leads to constitutive activation of downstream components of the PI3K pathway including the Akt and mTOR kinases. In model organisms, inactivation of these kinases can reverse the effects of PTEN loss. These data raise the possibility that drugs targeting these kinases, or PI3K itself, might have significant therapeutic activity in PTEN-null cancers. Akt kinase inhibitors are still in development; however, as a first test of this hypothesis, phase I and phase II trials of inhibitors of mTOR, namely, rapamycin and rapamycin analogs are underway.

Analysis of 1p, 19q, 9p, and 10q as prognostic markers for high-grade astrocytomas using fluorescence in situ hybridization on tissue microarrays from Radiation Therapy Oncology Group trials

Survival periods vary considerably for patients with high-grade astrocytomas, and reliable prognostic markers are not currently available. We therefore investigated whether genetic losses from chromosomes 1p, 19q, 9p, or 10q were associated with survival in 89 high-grade astrocytomas using tissue microarrays (TMAs) derived from Radiation Therapy Oncology Group clinical trials. Cases included 15 anaplastic astrocytomas (AAs) and 74 glioblastomas (GBMs) selected on the basis of survival times significantly shorter or longer than the expected median. Genetic analysis was performed by TMA-fluorescence in situ hybridization (FISH) on array sections using 8 DNA probes, including those directed at 1p32, 19q13.4, 9p21 (p16/CDKN2A), and 10q (PTEN and DMBT1). Genetic status for each locus was correlated with patient survival group, and data were analyzed by using Fisher's exact test of association (adjusted P = 0.025). Losses of chromosome 1p, either alone or in combination with 19q, were encountered in only 2 cases, both AAs. This contrasts with oligodendrogliomas, in which combined 1p and 19q losses are frequent and predictive of prolonged survival. Solitary 19q loss was noted in 3/15 AAs and in 7/70 GBMs and was more frequent in the long-term survival group (P = 0.041, AA and GBM combined). Chromosome 9p loss was seen in 5/8 AAs and 39/57 GBMs, whereas chromosome 10q loss was detected in 4/15 AAs and 48/68 GBMs. The 9p and 10q deletions were slightly more frequent in short-term survivors, though none of the comparisons achieved statistical significance. Long-term and short-term survival groups of high-grade astrocytomas appear to have dissimilar frequencies of 19q, 9p, and 10q deletions. TMA-FISH is a rapid and efficient way of evaluating genetic alterations in such tumors.

A functional polymorphism in the EGF gene is found with increased frequency in glioblastoma multiforme patients and is associated with more aggressive disease

Glioblastoma multiforme, the most aggressive form of primary brain tumor in adults, is nearly universally fatal, with 5-year survivals of <5% (P. Kleihues and W. K. Cavenee, eds., pp. 1-314, Lyon: IARC, 2000). Alterations in the epidermal growth factor receptor (EGFR) are common events in many glioblastoma. We hypothesized that a polymorphism in the 5'-untranslated region of the epidermal growth factor (EGF) gene, a natural ligand of the EGFR, may play a role in the genesis of these malignant gliomas. We find that patients with the GA or GG genotype have higher tumoral levels of EGF, irrespective of EGFR status, that they are more likely to recur after surgery, and that they have a statistically significant shorter overall progression-free survival than patients with the AA genotype. These findings suggest that a single nucleotide polymorphism in EGF may play a role in the formation of glioblastomas, is a useful and powerful prognostic marker for these patients, and may be a target for tumor therapy.

A spatio-temporal simulation model of the response of solid tumours to radiotherapyin vivo: parametric validation concerning oxygen enhancement ratio and cell cycle duration

Advanced bio-simulation methods are expected to substantially improve radiotherapy treatment planning. To this end a novel spatio-temporal patient-specific simulation model of the in vivo response of malignant tumours to radiotherapy schemes has been recently developed by our group. This paper discusses recent improvements to the model: an optimized algorithm leading to conformal shrinkage of the tumour as a response to radiotherapy, the introduction of the oxygen enhancement ratio (OER), a realistic initial cell phase distribution and finally an advanced imaging-based algorithm simulating the neovascularization field. A parametric study of the influence of the cell cycle duration Tc, OER, OERbeta for the beta LQ parameter on tumour growth. shrinkage and response to irradiation under two different fractionation schemes has been made. The model has been applied to two glioblastoma multiforme (GBM) cases, one with wild type (wt) and another one with mutated (mt) p53 gene. Furthermore, the model has been applied to a hypothetical GBM tumour with alpha and beta values corresponding to those of generic radiosensitive tumours. According to the model predictions, a whole tumour with shorter Tc tends to repopulate faster, as is to be expected. Furthermore, a higher OER value for the dormant cells leads to a more radioresistant whole tumour. A small variation of the OERbeta value does not seem to play a major role in the tumour response. Accelerated fractionation proved to be superior to the standard scheme for the whole range of the OER values considered. Finally, the tumour with mt p53 was shown to be more radioresistant compared to the tumour with wt p53. Although all simulation predictions agree at least qualitatively with the clinical experience and literature, a long-term clinical adaptation and quantitative validation procedure is in progress.

EGF-R and PDGF-R, but not bcl-2, overexpression predict overall survival in patients with low-grade astrocytomas

BACKGROUND AND OBJECTIVES

Therapy of malignant glioma tumors is based on histology and clinical factors. However, comparable lesions may correspond with important prognostic differences. Our purpose was to analyze retrospectively the prognostic input of platelet-derived growth factor receptor (PDGF-R), epidermal growth factor (EGF-R), and bcl-2 expression in 103 malignant gliomas from uniformly treated patients.

METHODS

The expression of the antigens was analyzed by immunohistochemistry (IHC). Prognostic evaluation was performed with the multivariate proportional hazards model. The follow-up period lasted 19 (5-122) months for survivors.

RESULTS

We observed that almost 50% of gliomas showed high expression of PDGF-R, while a lower expression of EGF-R and bcl-2 was found. No association between the main prognostic factors in malignant glioma (sex, age, histological grade, and Karnofsky score) and the labeling index (LI) of these antigens was observed. We found that only PDGF-R and EGF-R overexpression were associated with a shorter survival in patients with World Health Organization (WHO) II astrocytomas, being both associations independent of known prognostic factors, as shown by Cox model. Besides, we confirmed other authors' results that high histological grade and low performance score were associated with worse prognosis.

CONCLUSIONS

PDGF-R and EGF-R expression could be relevant in determining the prognosis of low-grade astrocytomas (LGAs) and in providing a more objective mechanism for their classification.

The contribution of epidermal growth factor receptor (EGFR) signaling pathway to radioresistance in human gliomas: a review of preclinical and correlative clinical data

PURPOSE

The epidermal growth factor receptor (EGFR) pathway is frequently upregulated in high-grade gliomas via gene amplification and by specific mutations that render EGFR constitutively active (EGFRvIII).

METHODS AND MATERIALS

This review highlights EGFR's role in mediating radiation resistance in gliomas: underlying molecular mechanisms, with discussion of relevant preclinical and clinical correlative data.

RESULTS

Preclinical and emerging clinical data suggest that EGFR signaling plays a potentially important role in mediating radiation resistance in human gliomas.

CONCLUSIONS

Targeting EGFR alone, or in combination with its downstream mediators, represents a promising new approach for the management of glioma patients.

Acquired resistance to EGFR inhibitors: mechanisms and prevention strategies

Potent and specific, or relatively specific, inhibitors of epidermal growth factor receptor (EGFR) signaling, including monoclonal antibodies and small molecular weight compounds, have been successfully developed. Both types of agent have been found to have significant antitumor activity, especially when used in combination with radio- hormone- and chemotherapy in preclinical studies. Because of the potentiation of the conventional drug activity in these combination settings, inhibitors of EGFR signaling have often been referred to as sensitizers for chemotherapy or radiation, as well as drug resistance reversal agents. Phase II clinical trials in head-and-neck as well as lung cancer suggested this concept of chemosensitization might translate into the clinic, but this remains to be definitively proven in randomized, double-blind Phase III trials. Given the extensive preclinical literature on EGFR blocking drugs and the advanced clinical development of such agents, it is surprising that the possibility of development of acquired resistance to the EGFR inhibitors themselves, a common clinical problem with virtually all other currently used anticancer drugs, remains a largely unexplored subject of investigation. Here we summarize some of the possible mechanisms that can result in acquired resistance to EGFR-targeting drugs. Alternative combination therapies to circumvent and delay this problem are suggested.

Evaluation of Epidermal Growth Factor Receptor (EGFR) by Chromogenic In Situ

Overexpression of EGFR secondary to EGFR gene amplification is a common feature in primary malignant gliomas. To correctly assess EGFR protein and gene level as possible prognostic and predictive markers in gliomas, straightforward assays, which can be used routinely in the pathology laboratory to evaluate EGFR status, becomes critical. EGFR gene amplification and chromosome 7 aneuploidy was detected in 34 formalin-fixed, paraffin-embedded benign and malignant gliomas by chromogenic in situ hybridization (CISH) using digoxigenin-labeled EGFR and biotin-labeled chromosome 7 centromeric probes. The results were evaluated by bright-field microscopy under a 40x objective lens. EGFR protein level was detected by immunohistochemistry (IHC) using monoclonal antibody 31G7. Five cases, 3 astrocytoma grade III (33%) and 2 glioblastoma multiforme (GBM) (33%), had EGFR amplification displayed as diaminobenzidine-stained multiple dots suggesting the pattern of double-minute chromosomes. Chromosome 7 polysomy was found in 68% gliomas, 100% GBM, 67% astrocytoma grade III, 42% astrocytoma grade II, 50% astrocytoma grade I, 100% ependymoma, and the 1 case of mixed glioma III. High expression of EGFR protein was present in 62% gliomas and displayed membrane and cytoplasmic staining. All tumors with EGFR gene amplification showed EGFR high expression. High expression of EGFR without gene amplification was observed in all grades of gliomas. Simultaneous detection of EGFR gene copies or chromosome 7 centromere signals along with tissue morphology allows us to compare CISH results easily with IHC results. Our results show that CISH is an objective, practical, and accurate assay to screen for EGFR gene status in gliomas.

Factors influencing survival in high-grade gliomas

Multivariate analyses have consistently identified a number of patient, tumor, and treatment variables that are significant prognostic factors for overall survival in patients with high-grade glioma. Age, performance status, mental status, tumor grade and histology, and extent of surgical resection are among the most significant prognostic factors influencing survival. Recently, we showed that normal versus abnormal baseline Folstein mini-mental status examination score is a significant prognostic factor in younger patients (age </=42), suggesting that mental status may be a more important determinant of clinical outcome than physical functioning in patients with high-grade glioma. Among tumor variables, tumor grade and histology appear to have the greatest effect on survival. A recursive partitioning analysis of three Radiation Therapy Oncology Group trials showed that among patients under 50 years of age, astrocytoma with anaplastic or atypical foci was associated with significantly improved survival compared with glioblastoma. An oligodendroglial component was also associated with improved survival in patients with grade 3 astrocytoma. In addition, combined loss of chromosome arms 1p and 19q is associated with improved chemosensitivity and overall survival in patients with pure oligodendroglioma. Among the treatment variables tested, extent of resection appears to be the most consistent prognostic factor. Gross total resection is associated with significantly improved survival compared with biopsy only. These models are capable of grouping patients into distinct prognostic subgroups with median survivals ranging from less than 5 to more than 50 months and thus provide useful information for future clinical trial design.

Clinical Utility of Fluorescence In Situ Hybridization (FISH) in Morphologically Ambiguous Gliomas with Hybrid Oligodendroglial/Astrocytic Features

Gliomas with hybrid oligodendroglial/astrocytic features are diagnostically problematic, and our ability to predict tumor behavior is limited. Some likely represent intermingled mixed oligoastrocytomas (MOAs), though precise diagnostic criteria and specific markers for this lesion are lacking. From the files at Washington University (1987-2000), 155 "ambiguous" glioma/intermingled MOA candidates were independently classified and graded by 5 neuropathologists, with consensus-derived pure oligodendrogliomas and astrocytomas excluded from further study. The 90 remaining cases (grades II = 29, III = 44, IV = 17) were analyzed by FISH on formalin-fixed, paraffin-embedded sections. Detectable deletions included combined 1p/19q (9%), solitary 19q (22%), PTEN/DMBT1 (26%), and p16 (32%). EGFR amplification was found in 11%. Patients were followed until death (47%) or a median of 3.3 years. Similar to prior glioma series, patient age (p < 0.0001) and tumor grade (p < 0.0001) were strongly associated with survival times. EGFR amplification (p = 0.0007) and deletions of PTEN/ DMBT1 (p = 0.016) or p16 (p = 0.014), either individually or as a group (p = 0.04), portended a shorter median survival compared with tumors lacking these alterations. We conclude that 1) distinct genetic subsets are identifiable by FISH in morphologically ambiguous gliomas, and 2) both histological grading and molecular analysis yield prognostically useful information.

PTEN protein expression correlates with PTEN gene molecular changes but not with VEGF expression in astrocytomas

PTEN gene (10q23) is a relevant tumor suppressor gene whose protein is a phosphatase involved in the control of angiogenesis of some tumors including astrocytomas. There are no studies correlating molecular changes of PTEN and the immunohistochemical expression of its protein (pPTEN) with the expression of vascular endothelial growth factor (VEGF) in astrocytomas. Fifty-six surgically resected brain gliomas, 10 grade 2, 16 grade 3, and 30 grade 4, were studied by a combined approach, consisting of (1) PCR analysis using four microsatellite markers against the PTEN gene region (10q23), (2) the FISH technique to test chromosome 10 using a pericentromeric probe, and (3) immunohistochemical evaluation of pPTEN and VEGF. Loss of heterozygosity (LOH) of PTEN was observed in 10% of fibrillary grade 2 astrocytomas and all gemistocytic ones. In high-grade tumors, LOH was more frequent in grade 4 than in grade 3 (> or =2 loci deleted, 83% and 56%, respectively). Monosomy for chromosome 10 was observed especially in high-grade tumors (6% of grade 3 and 50% of grade 4) and in 20% of grade 2 tumors, corresponding to gemistocytic astrocytomas. Results with both antibodies against PTEN were concordant: loss of cytoplasmic immunoreactivity was frequently observed according to homogeneous or heterogeneous patterns in 70% and 50% of grades 4 and 3, respectively, but not in grade 2. Immunonegativity of pPTEN was associated with PTEN gene deletion (> or =2 loci deleted) (P = 0.04) but not with monosomy. Cytoplasmic immunoreactivity against VEGF was observed in high-grade and in gemistocytic astrocytomas, but not in conventional grade 2 tumors. Tumor expression of pPTEN was not associated with immunoreactivity against VEGF when the same areas were considered. In conclusion, loss of PTEN expression is frequent in high-grade astrocytomas, but not in grade 2 tumors, and correlates with PTEN deletion and loss of chromosome 10. PTEN immunoreactivity does not correlate with VEGF expression in astrocytomas when similar areas are considered.