Treatment options for glioblastoma

Kynurenine Monooxygenase Expression and Activity in Human Astrocytomas

Glioblastoma multiforme (GBM) is the most common and aggressive primary brain tumor. The enzyme indoleamine-2,3-dioxygenase (IDO), which participates in the rate-limiting step of tryptophan catabolism through the kynurenine pathway (KP), is associated with poor prognosis in patients with GBM. The metabolites produced after tryptophan oxidation have immunomodulatory properties that can support the immunosuppressor environment. In this study, mRNA expression, protein expression, and activity of the enzyme kynurenine monooxygenase (KMO) were analyzed in GBM cell lines (A172, LN-18, U87, U373) and patient-derived astrocytoma samples. KMO mRNA expression was assessed by real-time RT-qPCR, KMO protein expression was evaluated by flow cytometry and immunofluorescence, and KMO activity was determined by quantifying 3-hydroxykynurenine by HPLC. Heterogenous patterns of both KMO expression and activity were observed among the GBM cell lines, with the A172 cell line showing the highest KMO expression and activity. Higher KMO mRNA expression was observed in glioma samples than in patients diagnosed with only a neurological disease; high KMO mRNA expression was also observed when using samples from patients with GBM in the TCGA program. The KMO protein expression was localized in GFAP⁺ cells in tumor tissue. These results suggest that KMO is a relevant target to be explored in glioma since it might play a role in supporting tumor metabolism and immune suppression.

Effect of Vocimagene Amiretrorepvec in Combination With Flucytosine vs Standard of Care on Survival Following Tumor Resection in Patients With Recurrent High-Grade Glioma: A Randomized Clinical Trial

Importance

New treatments are needed to improve the prognosis of patients with recurrent high-grade glioma.

Objective

To compare overall survival for patients receiving tumor resection followed by vocimagene amiretrorepvec (Toca 511) with flucytosine (Toca FC) vs standard of care (SOC).

Design, Setting, and Participants

A randomized, open-label phase 2/3 trial (TOCA 5) in 58 centers in the US, Canada, Israel, and South Korea, comparing posttumor resection treatment with Toca 511 followed by Toca FC vs a defined single choice of approved (SOC) therapies was conducted from November 30, 2015, to December 20, 2019. Patients received tumor resection for first or second recurrence of glioblastoma or anaplastic astrocytoma.

Interventions

Patients were randomized 1:1 to receive Toca 511/FC (n = 201) or SOC control (n = 202). For the Toca 511/FC group, patients received Toca 511 injected into the resection cavity wall at the time of surgery, followed by cycles of oral Toca FC 6 weeks after surgery. For the SOC control group, patients received investigators' choice of single therapy: lomustine, temozolomide, or bevacizumab.

Main Outcomes and Measures

The primary outcome was overall survival (OS) in time from randomization date to death due to any cause. Secondary outcomes reported in this study included safety, durable response rate (DRR), duration of DRR, durable clinical benefit rate, OS and DRR by IDH1 variant status, and 12-month OS.

Results

All 403 randomized patients (median [SD] age: 56 [11.46] years; 62.5% [252] men) were included in the efficacy analysis, and 400 patients were included in the safety analysis (3 patients on the SOC group did not receive resection). Final analysis included 271 deaths (141 deaths in the Toca 511/FC group and 130 deaths in the SOC control group). The median follow-up was 22.8 months. The median OS was 11.10 months for the Toca 511/FC group and 12.22 months for the control group (hazard ratio, 1.06; 95% CI 0.83, 1.35; P = .62). The secondary end points did not demonstrate statistically significant differences. The rates of adverse events were similar in the Toca 511/FC group and the SOC control group.

Conclusions and Relevance

Among patients who underwent tumor resection for first or second recurrence of glioblastoma or anaplastic astrocytoma, administration of Toca 511 and Toca FC, compared with SOC, did not improve overall survival or other efficacy end points.

Trial Registration

ClinicalTrials.gov Identifier: NCT02414165.

Window of Opportunity Clinical Trials to Evaluate Novel Therapies for Brain Tumors

Despite significant improvement in understanding of molecular underpinnings driving glioblastoma, there is minimal improvement in overall survival of patients. This poor outcome is caused in part by traditional designs of early phase clinical trials, which focus on clinical assessments of drug toxicity and response. Window of opportunity trials overcome this shortcoming by assessing drug-induced on-target molecular alterations in post-treatment human tumor specimens. This article provides an overview of window of opportunity trials, including novel designs for incorporating biologic end points into early stage trials in context of brain tumors, and examples of successfully executed window of opportunity trials for glioblastoma.

Incorporating genomic signatures into surgical and medical decision-making for elderly glioblastoma patients

Glioblastoma (GBM) is the most common type of malignant primary brain tumor in adults. It is a uniformly fatal disease (median overall survival 16 months) even with aggressive resection and an adjuvant temozolomide-based chemoradiation regimen. Age remains an independent risk factor for a poor prognosis. Several factors contribute to the dismal outcomes in the elderly population with GBM, including poor baseline health status, differences in underlying genomic alterations, and variability in the surgical and medical management of this subpopulation. The latter arises from a lack of adequate representation of elderly patients in clinical trials, resulting in limited data on the response of this subpopulation to standard treatment. Results from retrospective and some prospective studies have indicated that resection of only contrast-enhancing lesions and administration of hypofractionated radiotherapy in combination with temozolomide are effective strategies for optimizing survival while maintaining baseline quality of life in elderly GBM patients; however, survival remains dismal relative to that in a younger cohort. Here, the authors present historical context for the current strategies used for the multimodal management (surgical and medical) of elderly patients with GBM. Furthermore, they provide insights into elderly GBM patient-specific genomic signatures such as isocitrate dehydrogenase 1/2 (IDH1/2) wildtype status, telomerase reverse transcriptase promoter (TERTp) mutations, and somatic copy number alterations including CDK4/MDM2 coamplification, which are becoming better understood and could be utilized in a clinical trial design and patient stratification to guide the development of more effective adjuvant therapies specifically for elderly GBM patients.

Allicin Inhibits Proliferation by Decreasing IL-6 and IFN-β in HCMV-Infected Glioma Cells

PURPOSE

Allicin, an extract of garlic, has antitumor effects in multiple tumor types. However, the efficacy of allicin for treating glioblastoma has not yet been examined. This study examined the antitumor effect of allicin on human cytomegalovirus (HCMV)-infected glioblastoma multiforme (GBM) and its role in cytokine signaling.

MATERIALS AND METHODS

HCMV-infected glioblastoma was modeled by transfection of U87MG glioblastoma cells with HMCV proteins. MTT assay was used to assess the effect of allicin on the proliferation of glioma cells. Western blot analysis was used to detect the effect of allicin on the expression of intermediate-early gene 2 (IE2) and p53. Reverse transcription-quantitative polymerase chain reaction was used to assess and the levels of interleukin (IL)-6 and interferon (IFN)-β. Single cell gel electrophoresis was used to analyze changes in radiotherapy-induced DNA damage.

RESULTS

Transfection of the IE2 protein led to decreased p53 expression and increased glioblastoma cell proliferation. Allicin inhibited this proliferation in a dose- and time-dependent manner. An inhibitory effect on cytokine release was observed in GBM cells treated with allicin. After treatment with allicin, p53 levels increased significantly, whereas expression of the inflammatory factors such as IL-6 and IFN-β decreased. U87MG cells treated with allicin and 10 Gy irradiation had increased intracellular DNA damage compared to either treatment alone.

CONCLUSION

Allicin inhibited proliferation of glioblastoma cells in vitro. Allicin also inhibited cytokine release, upregulated p53 activity, and increased the sensitivity of glioblastoma to radiotherapy. These results suggest that allicin is effective against HCMV-infected glioblastomas.

Phase 1 trial of vocimagene amiretrorepvec and 5-fluorocytosine for recurrent high-grade glioma

Toca 511 (vocimagene amiretrorepvec) is an investigational nonlytic, retroviral replicating vector (RRV) that delivers a yeast cytosine deaminase, which converts subsequently administered courses of the investigational prodrug Toca FC (extended-release 5-fluorocytosine) into the antimetabolite 5-fluorouracil. Forty-five subjects with recurrent or progressive high-grade glioma were treated. The end points of this phase 1, open-label, ascending dose, multicenter trial included safety, efficacy, and molecular profiling; survival was compared to a matching subgroup from an external control. Overall survival for recurrent high-grade glioma was 13.6 months (95% confidence interval, 10.8 to 20.0) and was statistically improved relative to an external control (hazard ratio, 0.45; P = 0.003). Tumor samples from subjects surviving more than 52 weeks after Toca 511 delivery disproportionately displayed a survival-related mRNA expression signature, identifying a potential molecular signature that may correlate with treatment-related survival rather than being prognostic. Toca 511 and Toca FC show excellent tolerability, with RRV persisting in the tumor and RRV control systemically. The favorable assessment of Toca 511 and Toca FC supports confirmation in a randomized phase 2/3 trial (NCT02414165).

Brain targeted delivery of carmustine using solid lipid nanoparticles modified with tamoxifen and lactoferrin for antitumor proliferation

Solid lipid nanoparticles (SLNs) conjugated with tamoxifen (TX) and lactoferrin (Lf) were applied to carry anticancer carmustine (BCNU) across the blood-brain barrier (BBB) for enhanced antiproliferation against glioblastoma multiforme (GBM). BCNU-loaded SLNs with modified TX and Lf (TX-Lf-BCNU-SLNs) were used to penetrate a monolayer of human brain-microvascular endothelial cells (HBMECs) and human astrocytes and to target malignant U87MG cells. The surface TX and Lf on TX-Lf-BCNU-SLNs improved the characteristics of sustained release for BCNU. When compared with BCNU-loaded SLNs, TX-Lf-BCNU-SLNs increased the BBB permeability coefficient for BCNU about ten times. In addition, TX-BCNU-SLNs considerably promoted the fluorescent intensity of intracellular acetomethoxy derivative of calcein (calcein-AM) in HBMECs via endocytosis. However, the conjugated Lf could only slightly increase the fluorescence of calcein-AM. Moreover, the order of formulation in the inhibition to U87MG cells was TX-Lf-BCNU-SLNs>TX-BCNU-SLNs>Lf-BCNU-SLNs>BCNU-SLNs. TX-Lf-BCNU-SLNs can be effective in infiltrating the BBB and delivering BCNU to GBM for future chemotherapy application.

Bcl-2 family member Mcl-1 expression is reduced under hypoxia by the E3 ligase FBW7 contributing to BNIP3 induced cell death in glioma cells

Mcl-1 is an anti-apoptotic Bcl-2 family member that is often over-expressed in the malignant brain tumor glioblastoma (GBM). It has been previously shown that epidermal growth factor receptors up-regulate Mcl-1 contributing to a cell survival response. Hypoxia is a poor prognostic marker in glioblastoma despite the fact that hypoxic regions have areas of necrosis. Hypoxic regions of GBM also highly express the pro-cell death Bcl-2 family member BNIP3, yet when BNIP3 is overexpressed in glioma cells, it induces cell death. The reasons for this discrepancy are unclear. Herein we have found that Mcl-1 expression is reduced under hypoxia due to degradation by the E3 ligase FBW7 leading to increased hypoxia induced cell death. This cell death is reduced by EGFR activation leading to increased Mcl-1 expression under hypoxia. Conversely, BNIP3 is over-expressed in hypoxia at times when Mcl-1 expression is decreased. Knocking down BNIP3 expression reduces hypoxia cell death and Mcl-1 expression effectively blocks BNIP3 induced cell death. Of significance, BNIP3 and Mcl-1 are co-localized under hypoxia in glioma cells. These results suggest that Mcl-1 can block the ability of BNIP3 to induce cell death under hypoxia in GBM tumors.

Intratumoral oncolytic adenoviral treatment modulates the glioma microenvironment and facilitates systemic tumor-antigen-specific T cell therapy

Glioblastoma multiforme (GBM) is the most aggressive form of primary brain tumor and is associated with poor survival. Virotherapy is a promising candidate for the development of effective, novel treatments for GBM. Recent studies have underscored the potential of virotherapy in enhancing antitumor immunity despite the fact that its mechanisms remain largely unknown. Here, using a syngeneic GBM mouse model, we report that intratumoral virotherapy significantly modulates the tumor microenvironment. We found that intratumoral administration of an oncolytic adenovirus, AdCMVdelta24, decreased tumor-infiltrating CD4⁺ Foxp3⁺ regulatory T cells (Tregs) and increased IFNγ-producing CD8⁺ T cells in treated tumors, even in late stage disease in which a highly immunosuppressive tumor microenvironment is considered to be a significant barrier to immunotherapy. Importantly, intratumoral AdCMVdelta24 treatment augmented systemically transferred tumor-antigen-specific T cell therapy. Furthermore, mechanistic studies showed (1) downregulation of Foxp3 in Tregs that were incubated with media conditioned by virus-infected tumor cells, (2) downregulation of indoleamine 2,3 dioxygenase 1 (IDO) in glioma cells upon infection by AdCMVdelta24, and (3) reprograming of Tregs from an immunosuppressive to a stimulatory state. Taken together, our findings demonstrate the potency of intratumoral oncolytic adenoviral treatment in enhancing antitumor immunity through the regulation of multiple aspects of immune suppression in the context of glioma, supporting further clinical development of oncolytic adenovirus-based immune therapies for malignant brain cancer.

Ginsenoside Rg3 induces apoptosis in the U87MG human glioblastoma cell line through the MEK signaling pathway and reactive oxygen species

Ginsenoside is known to have potential cancer-preventive activities. The major active components in red ginseng consist of a variety of ginsenosides including Rg3, Rg5 and Rk1, each of which has different pharmacological activities. Among these, Rg3 has been reported to exert anticancer activities through inhibition of angiogenesis and cell proliferation. However, the effects of Rg3 and its molecular mechanism on glioblastoma multiforme (GBM) remain unclear. Therefore, it is essential to develop a greater understanding of this novel compound. In the present study, we investigated the effects of Rg3 on a human glioblastoma cell line and its molecular signaling mechanism. The mechanisms of apoptosis by ginsenoside Rg3 were related with the MEK signaling pathway and reactive oxygen species. Our data suggest that ginsenoside Rg3 is a novel agent for the chemotherapy of GBM.

Current status of local therapy in malignant gliomas--a clinical review of three selected approaches

Malignant gliomas are the most frequently occurring, devastating primary brain tumors, and are coupled with a poor survival rate. Despite the fact that complete neurosurgical resection of these tumors is impossible in consideration of their infiltrating nature, surgical resection followed by adjuvant therapeutics, including radiation therapy and chemotherapy, is still the current standard therapy. Systemic chemotherapy is restricted by the blood-brain barrier, while methods of local delivery, such as with drug-impregnated wafers, convection-enhanced drug delivery, or direct perilesional injections, present attractive ways to circumvent these barriers. These methods are promising ways for direct delivery of either standard chemotherapeutic or new anti-cancer agents. Several clinical trials showed controversial results relating to the influence of a local delivery of chemotherapy on the survival of patients with both recurrent and newly diagnosed malignant gliomas. Our article will review the development of the drug-impregnated release, as well as convection-enhanced delivery and the direct injection into brain tissue, which has been used predominantly in gene-therapy trials. Further, it will focus on the use of convection-enhanced delivery in the treatment of patients with malignant gliomas, placing special emphasis on potential shortcomings in past clinical trials. Although there is a strong need for new or additional therapeutic strategies in the treatment of malignant gliomas, and although local delivery of chemotherapy in those tumors might be a powerful tool, local therapy is used only sporadically nowadays. Thus, we have to learn from our mistakes in the past and we strongly encourage future developments in this field.

BNIP3 acts as transcriptional repressor of death receptor-5 expression and prevents TRAIL-induced cell death in gliomas

Glioblastoma multiforme (GBM) is the most common and malignant brain tumor, and current treatment modalities such as surgical resection, adjuvant radiotherapy and temozolomide (TMZ) chemotherapy are ineffective. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a novel cancer therapeutic agent for GBM because of its capability of inducing apoptosis in glioma cells. Unfortunately, the majority of glioma cells are resistant to TRAIL-induced apoptosis. The Bcl-2 nineteen kilodalton interacting protein (BNIP3) is a pro-cell death BH3-only member of the Bcl-2 family that is one of the highest expressed genes in hypoxic regions of GBM tumors. We previously found that BNIP3 is localized to the nucleus in GBM tumors and suppresses cell death in glioma cells. Herein, we have discovered when BNIP3 nuclear expression is knockdown in glioma cell lines and in normal mouse astrocytes, TRAIL and its death receptor, death receptor-5 (DR5) expression is increased. In addition, when nuclear BNIP3 expression is increased, the amount of TRAIL-induced apoptosis is reduced. Using a streptavidin pull-down assay, we found that BNIP3 binds to the DR5 promoter and nuclear BNIP3 binds to the DR5 promoter. Furthermore, nuclear BNIP3 expression in GBM tumors correlates with decreased DR5 expression. Taken together, we have discovered a novel transcriptional repression function for BNIP3 conferring a TRAIL resistance in glioma cells.

Neural progenitor and hemopoietic stem cells inhibit the growth of low-differentiated glioma

The effects of neural progenitor and hemopoietic stem cells on C6 glioma cells were studied in in vivo and in vitro experiments. Considerable inhibition of proliferation during co-culturing of glioma cells with neural progenitor cells was revealed by quantitative MTT test and bromodeoxyuridine incorporation test. Labeled neural progenitor and hemopoietic stem cells implanted into the focus of experimental cerebral glioma C6 survive in the brain of experimental animals for at least 7 days, migrate with glioma cells, and accumulate in the peritumoral space. Under these conditions, neural progenitor cells differentiate with the formation of long processes. Morphometric analysis of glioma cells showed that implantation of neural progenitor and hemopoietic stem cells is accompanied by considerable inhibition of the growth of experimental glioma C6 in comparison with the control. The mechanisms of tumor-suppressive effects of neural and hemopoietic stem cells require further investigation.

Conditional survival of high-grade glioma in Los Angeles County during the year 1990-2000

Survival probabilities for high-grade glioma are estimated at the time of diagnosis and provide limited information following treatment. This study determined dynamic indices to predict post-diagnosis survival for high-grade glioma patients. Survival information for 2,743 patients with high-grade glioma, diagnosed in Los Angeles County during the years 1990-2000, were used to estimate conditional survival probabilities with 95 % confidence intervals, for patients still alive at 1, 2, 3, 4, or 5 years after diagnosis. The conditional probabilities of surviving one additional year increase as the post-diagnosis survival time increases (from 43 ± 2 % conditional on surviving 1 year after diagnosis to 91 ± 2 % conditional on surviving 5 years after diagnosis). Patients diagnosed with WHO grade III gliomas have higher conditional survival probabilities than those diagnosed WHO grade IV gliomas. However, as the years after diagnosis increase, the differences in the conditional probabilities between the two groups are attenuated. At the time of diagnosis, age and tumor histology (WHO grade), tumor site, primary treatment, time of treatment start after diagnosis, as well as whether the patient was treated at a teaching hospital were significantly associated with overall survival. By 4 years post-diagnosis however, with the exception of age, variables associated with survival at baseline were no longer significantly associated with survival. Conditional survival probabilities provide clinically relevant information for understanding the prognosis for patients with high-grade gliomas.

Convection-enhanced delivery catheter placements for high-grade gliomas: complications and pitfalls

Convection-enhanced delivery (CED) of compounds into brain tumors reportedly circumvents the blood brain barrier. CED intends to increase drug delivery to malignant cells, reaching high local therapeutic concentration and decreasing or eliminating systemic side effects. Clinical experience and published data on catheter placement (CP) surgery are scarce. We propose practical and technical guidelines for planning CED based on our experience. We retrospectively analyzed the medical charts and relevant neuroimages of 25 patients following the insertion of 64 CED catheters. The patients were enrolled in at least one of four clinical trials using CED for treating recurrent glioblastoma multiforme in our institution between 2003-2006. Intra- and postoperative complications related to CP surgery and the difficulties and pitfalls of planning were evaluated. There were 29 CP surgeries. Forty-four peritumoral brain tissue catheters were inserted in 16 CP surgeries following tumor resection in 16 patients, and 20 catheters were placed into the tumor in 13 procedures in 10 patients. The lesions were in or near eloquent brain tissue areas in 13 of all CP surgeries. Complications included increased edema (31%), infection (6.9%), bleeding (6.9%) and seizures (13.8%). Significant neurological deterioration occurred in 4 patients (13.8%). Difficulties in adhering to CP surgery guidelines included lesion site (superficial, mesial temporal lobe, proximity to CSF spaces), proximity to eloquent cortical areas, tissue density that interfered with the trajectory, and technical limitations of stereotactic instruments. CED procedures for high-grade gliomas may be associated with surgical morbidity. Adherence to guidelines might be difficult because of lesion site and complicated by brain and tumor tissue characteristics. This should be considered while planning clinical trials that use convection-based technology.

Treatment outcomes for patients with glioblastoma multiforme and a low Karnofsky Performance Scale score on presentation to a tertiary care institution. Clinical article

OBJECT

The object of this study was to determine the benefit of surgery, radiation, and chemotherapy for patients with glioblastoma multiforme (GBM) and a low Karnofsky Performance Scale (KPS) score.

METHODS

The authors retrospectively evaluated the records of patients who underwent primary treatment for pathologically confirmed GBM and with a KPS score ≤ 50 on initial evaluation for radiation therapy at a tertiary care institution between 1977 and 2006. Seventy-four patients with a median age of 69 years (range 19-88 years) and a median KPS score of 50 (range 20-50) were retrospectively grouped into the Radiation Therapy Oncology Group (RTOG) recursive partitioning analysis (RPA) Classes IV (11 patients), V (15 patients), and VI (48 patients). Patients underwent biopsy (38 patients) or tumor resection (36 patients). Forty-seven patients received radiation. Nineteen patients also received chemotherapy (53% temozolomide), initiated concurrently (47%) or after radiotherapy.

RESULTS

The median survival overall was 2.3 months (range 0.2-48 months). Median survival stratified by RPA Classes IV, V, and VI was 6.6, 6.6, and 1.8 months, respectively (p < 0.001, log-rank test). Median survival for patients receiving radiation (5.2 months) was greater than that for patients who declined radiation (1.6 months, p < 0.001). Patients in RPA Class VI appeared to benefit from radiotherapy only when tumor resection was also performed. The median survival from treatment initiation was greater for patients receiving chemotherapy concomitantly with radiotherapy (9.8 months) as compared with radiotherapy alone (1.7 months, p = 0.002). Of 20 patients seen for follow-up in the clinic at a median of 48 days (range 24-196 days) following radiotherapy, 70% were noted to have an improvement in the KPS score of between 10 and 30 points from the baseline score. On multivariate analysis, only RPA class (p = 0.01), resection (HR = 0.37, p = 0.001), and radiation therapy (HR = 0.39, p = 0.02) were significant predictors of a decreased mortality rate.

CONCLUSIONS

Patients with a KPS score ≤ 50 appear to have increased survival and functional status following tumor resection and radiation. The extent of benefit from concomitant chemotherapy is unclear. Future studies may benefit from reporting that utilizes a prognostic classification system such as the RTOG RPA class, which has been shown to be effective at separating outcomes even in patients with low performance status. Patients with GBMs and low KPS scores need to be evaluated in prospective studies to identify the extent to which different therapies improve outcomes.

Imatinib and docetaxel in combination can effectively inhibit glioma invasion in an in vitro 3D invasion assay

The main problem in the treatment of malignant astrocytomas is their invasive behaviour. Successful resection of the main tumour mass cannot prevent recurrence due to single cells invading the surrounding brain parenchyma at the time of diagnosis. The classical combination therapy, PCV (Procarbazine, CCNU and Vincristine) used for over 30 years; has shown its clinical effectiveness in the treatment of malignant astrocytomas and glioblastomas is still doubtful. Using an in vitro three dimensional invasion model, we tested the effect of the tyrosine kinase inhibitor imatinib and the microtubule inhibitor docetaxel on the invasion activity of a panel of astrocytic tumour cell lines, including two established glioma cell lines, IPSB-18 and SNB-19, and two primary cell lines, originating from glioblastomas, CLOM002 and UPHHJA, and in normal astrocytes. A dose response curve for each drug alone and in combination was determined. The half maximal inhibitory concentration (IC(50)) concentration of imatinib was between 15.7 and 18.7 μM, which did not affect invasion activity of the cell lines. The IC(50) concentration of docetaxel was between 0.7 and 19.8 nM, and at 14.9 nM docetaxel had a slight transient inhibitory effect on invasion activity of all tested cells. The combination of imatinib at 13.5 μM and docetaxel at 14.9 nM, however, synergistically inhibited cell growth and invasion activity and could not be reversed by drug removal. A combination treatment with tyrosine kinase inhibitors and cytotoxic drugs shows promise in tackling both glioma proliferation and invasion, and could present a new treatment regimen for malignant astrocytomas.

Novel antitumor effect of carboplatin delivered by intracerebral microinfusion in a rat malignant glioma model

Carboplatin loaded osmotic mini-pumps were implanted in 24 9L malignant glioma-bearing rats to investigate the implications of direct intracerebral microinfusion. Carboplatin using 0.1 mg/ml (low dose group) or 1.0 mg/ml (high dose group) with eight rats in each group, or 5% D-glucose (control group) in eight rats were infused at 1 microl/hr for 7 days. The tumor volume was serially measured by magnetic resonance (MR) imaging with gadolinium as the enhanced area, and the survival periods and histological findings were also examined. Separately, to examine the effects of intracerebral carboplatin infusion on vascular permeability, tumor-bearing rats received intravenous administration of 2% Evans blue at 21 days after infusion. The high dose group showed transient increase of enhanced volume at 21 days associated with mass effect, and significantly decreased tumor volume at 28 and 35 days compared with the control and low dose groups. The high dose group showed significant longer survival time than the control and low dose groups. Histological examination of the high dose group at 21 days showed the central tumor necrotic area around the infusion site and Evans blue leakage into the surrounding enhanced rim and the necrotic core. Therefore, leakage of plasma fluid into the necrotic area was considered to be the cause of apparent transient swelling. The present study demonstrated quantitatively using MR imaging that intracerebral carboplatin microinfusion significantly inhibited the rapid growth of experimental rat glioma but that the high dose required carries the risk of transient swelling of the target tumor.

Long-Term Survival of a Patient with Giant Cell Glioblastoma: Case Report and Review of the Literature

Glioblastoma multiforme (GBM) is the most common glial tumor of the central nervous system. Overall survival is less than a year in most of the cases in spite of multimodal treatment approaches. A 45-year-old female with histologically confirmed giant cell GBM was treated at our institution. Subtotal excision of the lesion situated in the right precentral area was performed during the initial stay in August 2005. The patient improved after the procedure with no hypertension and additional neurological deficit. Radiotherapy plus concomitant and adjuvant temozolomide was performed. The patient was symptom-free for 35 months after initial surgery. From July 2008 the patient developed partial motor seizures in the left side of the body and progressive hemiparesis. Local tumor progression was demonstrated on the neuroimaging studies. In December 2008, a second operative intervention was performed with subtotal excision of the tumor. Forty-five months after the initial diagnosis the patient is still alive with moderate neurological deficit. Microarray analysis of the tumor found the following numeric chromosomal aberrations: monosomy 8, 10, 13, 22, and trisomy 21, as well as amplifications in 4q34.1, 4q28.2, 6q16.3, 7q36.1, 7p21.3, and deletions in 1q42.12, 1q32.2, 1q25.2, 1p33, 2q37.2, 18q22.3, 19p13.2, Xq28, and Xq27.3. GBMs seem to be a heterogeneous group of glial tumors with different clinical course and therapeutic response. Microarray analysis is a useful method to establish a number of possible molecular predictors.

Interstitial continuous infusion therapy in a malignant glioma model in rats

PURPOSE

Local direct delivery of chemotherapeutic agents for the treatment of brain tumors is an area of focus in the development of new therapeutic paradigms. These techniques need improvement, especially in terms of drug retention in brain tissue.

MATERIALS AND METHODS

In this study, we used a rat glioma model to examine carboplatin distribution, as measured by platinum penetration, after delivery via interstitial continuous (i.c.) infusion. We also examined rat survival times in response to carboplatin and oxaliplatin. I.C. infusion, a modified version of convection-enhanced delivery (CED) for local drug delivery, uses low volume (1 microl per hour) continuous infusion directly into the tumor.

RESULTS

I.C. infusion produced a nearly 360-fold higher concentration of platinum in tumor tissue and significantly prolonged rodent survival time compared to intraperitoneal (i.p.) infusion.

CONCLUSIONS

We showed i.c. infusion allows for circumvention of the blood-brain barrier, focused drug distribution, and sustained drug delivery. This method could be a promising strategy for treating brain tumors.

BNIP3 (Bcl-2 19 kDa interacting protein) acts as transcriptional repressor of apoptosis-inducing factor expression preventing cell death in human malignant gliomas

The Bcl-2 19 kDa interacting protein (BNIP3) is a pro-cell-death BH3-only member of the Bcl-2 family. We previously found that BNIP3 is localized to the nucleus in the majority of glioblastoma multiforme (GBM) tumors and fails to induce cell death. Herein, we have discovered that nuclear BNIP3 binds to the promoter of the apoptosis-inducing factor (AIF) gene and represses its expression. BNIP3 associates with PTB-associating splicing factor (PSF) and HDAC1 (histone deacetylase 1) contributing to transcriptional repression of the AIF gene. This BNIP3-mediated reduction in AIF expression leads to decreased temozolomide-induced apoptosis in glioma cells. Furthermore, nuclear BNIP3 expression in GBMs correlates with decreased AIF expression. Together, we have discovered a novel transcriptional repression function for BNIP3 causing reduced AIF expression and increased resistance to apoptosis. Thus, nuclear BNIP3 may confer a survival advantage to glioma cells and explain, in part, why BNIP3 is expressed at high levels in solid tumors, especially GBM.

Early clinical and neuroradiological worsening after radiotherapy and concomitant temozolomide in patients with glioblastoma: tumour progression or radionecrosis?

OBJECTIVES

This study investigates the diagnosis and management of patients with resected brain glioblastomas who presented early clinical and neuroradiological worsening after the completion of the Stupp protocol. Its aim is to discuss the occurrence of early radionecrosis.

METHODS

Fifty patients with brain glioblastoma treated by surgical resection and Stupp protocol were reviewed; 15 among them (30%) had early clinical and neuroradiological worsening at the 6-month follow-up. The MR spectroscopy and surgical findings of these patients are reviewed.

RESULTS

MR spectroscopy was in favour of tumour recurrence in 14 among 15 patients and showed radionecrosis in one. Among 10 patients who were reoperated on, 7 had histologically verified tumour recurrence or regrowth, whereas in 3 histopathology showed necrosis without evidence of tumour. The 7 patients with tumour progression had prevalence of focal neuroradiological signs (6/7) and a survival of 7.5-12 months (median survival 10 months). The 4 patients with early radionecrosis (including one patient who was not reoperated on) had clinical worsening with mental deterioration, confusion and ataxia, and MR spectroscopy positive for tumour recurrence in 3. Three were alive 24-30 months after the end of the radiotherapy, whereas one died at 40 months.

CONCLUSION

Early radionecrosis after the Stupp protocol is not a rare event due to the radiosensitization effect of temozolomide. This phenomenon may predict a durable response to radiotherapy. MR spectroscopy may simulate tumour recurrence. A correct diagnosis is necessary to avoid useless reoperations and incorrect withdrawal of temozolomide.

Vector therapies for malignant glioma: shifting the clinical paradigm

BACKGROUND

Malignant glioma represents one of the most aggressive and devastating forms of human cancer. At present, there exists no successful treatment for this disease. Gene therapy, or vector therapy, has emerged as a viable experimental treatment method for intracranial malignancies.

OBJECTIVE

Vector therapy paradigms that have entered the clinical arena have shown adequate safety; however, the majority of the studies failed to observe significant clinical benefits. As such, researchers have refocused their efforts on developing novel vectors as well as new delivery methods to enhance the therapeutic effect of a particular vector. In this review, we discuss common vector therapy approaches used in clinical trials, their drawbacks and potential ways of overcoming these challenges.

METHODS

We focus on the experimental evaluation of cell-based vector therapies and adenoviral and herpes simplex virus type 1 vectors in the treatment of malignant glioma.

CONCLUSION

Vector therapy remains a promising treatment strategy for malignant glioma. Although significant questions remain to be answered, early clinical data suggest safety of this approach and future studies will likely address the efficacy of the proposed therapy.

Reduced expression of DNA topoisomerase I in SF295 human glioblastoma cells selected for resistance to homocamptothecin and diflomotecan

Homocamptothecins (hCPTs) are a novel class of topoisomerase I (Top1) inhibitors with enhanced chemical stability compared with the currently used camptothecin (CPT) analogs irinotecan and topotecan. The hCPT derivative diflomotecan (BN80915) is currently in clinical trials. We established two resistant human glioblastoma cell lines, SF295/hCPT50 and SF295/BN50, by stepwise exposure of the parental SF295 line to increasing concentrations of hCPT and BN80915, respectively. The two resistant cell lines were 15- to 22-fold resistant to hCPT and BN80915 as well as 7- to 27-fold cross-resistant to other Top1 inhibitors, including CPT, topotecan, and the indenoisoquinolines MJ-III-65 (NSC 706744) and NSC 724998, but sensitive to the topoisomerase II inhibitors mitoxantrone and etoposide. Neither of the resistant cell lines displayed any detectable expression of the three major drug transporters P-glycoprotien, multidrug resistance-associated protein 1, or ATP-binding cassette, subfamily G (WHITE), member 2, as assessed by immunoblot or flow cytometry. Reduced expression of Top1 protein occurred at the transcriptional level in both of the resistant cell lines, consistent with the reduction of Top1 enzyme level as the major contribution to the resistance phenotype in SF295/hCPT50 and SF295/BN50 cells. Treatment of the resistant cell lines with the histone deacetylase inhibitor depsipeptide or the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine alone or concomitantly did not result in re-expression of Top1. Our studies suggest that selection for resistance to hCPT or BN80915 is primarily related to reduced Top1 expression at the transcriptional level, resulting in reduced enzyme levels.

Alpha-v integrins as therapeutic targets in oncology

Integrins are heterodimeric cell adhesion receptors that mediate intercellular communication through cell-extracellular matrix interactions and cell-cell interactions. Integrins have been demonstrated to play a direct role in cancer progression, specifically in tumor cell survival, tumor angiogenesis, and metastasis. Therefore, agents targeted against integrin function have potential as effective anticancer therapies. Numerous anti-integrin agents, including monoclonal antibodies and small-molecule inhibitors, are in clinical development for the treatment of solid and hematologic tumors. This review focuses on the role of alpha(v) integrins in cancer progression, the current status of integrin-targeted agents in development, and strategies for the clinical development of anti-integrin therapies.

Cellular multiparametric MRI of neural stem cell therapy in a rat glioma model

Cellular multiparametric magnetic resonance imaging (MRI) provided an in vivo visualisation of neural stem cells' (NSCs) tropism for gliomas in the rat brain. NSCs were magnetically labelled in vitro with the bimodal gadolinium-based contrast agent, gadolinium rhodamine dextran (GRID), and injected into the contralateral hemisphere to the developing tumour. Contrast-to-noise measurements showed that GRID-labelled cells induced a signal attenuation on both T2-, T2(*)-weighted images, and a modest signal gain on T1-weighted images. Tumour development and progression were longitudinally monitored in vivo by serial MR scanning. Measurements of tumour volume and tumour progression over time in terms of tumour doubling time showed a tendency towards a reduced tumour growth in NSC-treated animals. MR findings of migration and infiltration of tumours by labelled NSCs were corroborated with immunohistopathology, where labelled cells were detected in the corpus callosum at the tumour border and dispersed in the solid tumour tissue. Immunohistopathology also revealed that macrophages invaded the tumour tissue and in some cases engulfed GRID-labelled stem cells. No significant difference in macrophage recruitment between NSC-treated and vehicle-treated animals were detected, indicating that magnetically labelled NSC do not increase macrophage invasion of tumour tissue. Our findings demonstrate that cellular multiparametric MRI provides a valuable tool for in vivo dynamic monitoring of tumour-directed neural stem cell migration as well as therapeutic efficacy.

Selective enhancement of cellular oxidative stress by chloroquine: implications for the treatment of glioblastoma multiforme

Chloroquine is used in the treatment of malaria, a disease caused by infection with the parasite Plasmodium. Although chloroquine appears to possess diverse pharmacological activity, its plasmodicidal activity results from augmentation of parasite oxidative stress. Chloroquine also appears to augment oxidative stress in metabolically active mammalian cells, including human astroglial cells. The authors propose that chloroquine may augment oxidative stress induced by radiotherapy in the treatment of glioblastoma multiforme, enhancing therapeutic efficacy. Such an effect would be consistent with the known pharmacological effects of chloroquine observed in Plasmodium. Other selective redox agents, such as tempol and artemisinin, should be investigated clinically for therapeutic benefit when coadministered with combined radio- and chemotherapy for cancer.