Surgical management of lateral-ventricle metastases: report of 29 cases in a single-institution experience

OBJECT

The aim of this study was to review the outcome of patients undergoing surgery for treatment of lateral-ventricle metastases.

METHODS

Imaging information and chart reviews of operative reports were used to conduct a retrospective analysis in 29 patients who underwent resection of lateral-ventricle metastases at the authors' institution between 1993 and 2007. Clinical and neurosurgical outcomes and recurrence rates were studied.

RESULTS

The mean patient age was 56 years (range 20-69 years); 66% of patients were male. Single intraventricular metastases occurred in 69% of patients, and 55% of them had systemic metastases. The 30-day postoperative mortality rate was 7%. There was intracerebral tumor recurrence in 41% of patients, with 1 patient undergoing a second operation for this. The median postoperative survival duration for 28 patients (excluding 1 patient with preoperative leptomeningeal disease) was 11.7 months; the 3- and 5-year survival rates were 17 and 11%, respectively. Univariate analysis identified factors significantly influencing survival, including the preoperative Karnofsky Performance Scale (KPS) score (p = 0.02), the number of cerebral metastases (p = 0.02), the presence of primary renal cell carcinoma (RCC) (p = 0.02), and the resection method (en bloc vs piecemeal; p = 0.05). The presence of extracranial metastases did not significantly influence survival. Multivariate analysis showed that the preoperative KPS score (p = 0.002), the presence of primary RCC (p = 0.039), and the resection method (en bloc vs piecemeal; p = 0.008) correlated significantly with survival time.

CONCLUSIONS

Surgery is an important component in the management of intraventricular metastases. To the authors' knowledge, this is the first study focusing totally on resection of lateral-ventricle metastases. The authors found that patients with primary RCC, those with a favorable preoperative KPS score, and those who underwent en bloc resection had a better outcome than others.

Abstract 5322: Glioma cancer stem cells induce immune suppressive macrophages

Introduction: The tumor microenvironment can induce monocytes to become immune suppressive macrophages (M2) via the phosphorylation of the signal transducer activator of transcription 3 (STAT3). The M2 cells assume a phenotype with impaired anti-tumor activity, support tumor progression, angiogenesis, and invasion and portend a poor prognosis. Gliomas contain cancer stem cells (gCSCs) that are self-renewing, multipotent, recapitulate the phenotype of the original tumor, and mediate resistance to radiation and chemotherapy. The gCSCs inhibit adaptive immune responses by inhibiting T cell proliferation and effector responses, inducing T cell apoptosis and inducing Tregs secondary to phosphorylated STAT3 (p-STAT3) regulated processes such as secreted TGF-β1 and Galectin-3 and the expression of cell surface molecules such as B7-H1. We therefore hypothesized that gCSCs also exert immune suppression of the innate immune system by inducing M2 cells.

Methods: The gCSCs (n=4) were isolated from surgical glioblastoma specimens. Normal microglia were isolated from brain specimens obtained during resections of extra-axial lesions. Peripheral blood monocytes were isolated from healthy donors and differentiated into macrophages (MDMs), which were then treated with gCSC supernatants and recombinant cytokines. Cell surface markers were assessed by flow cytometry, secreted cytokines measured using ELISA, T cell proliferation by CFSE, Treg induction by flow cytometry and phagocytosis by fluorescent bead uptake. Western blot assays were used to assess activation of the p-STAT1 and p-STAT3 pathways. The p-STAT3 pathway was inhibited with the small molecule WP1066 and siRNA.

Results: The gCSCs produce macrophage inhibitory cytokine (MIC-1) (22.3 - 1056.2 pg/106 cells/24 hours), macrophage inhibitory factor (MIF) (69.1 - 1463.3 pg/106 cells/24 hours), and TGF-β1 (24 - 73.8 pg/106 cells/24 hours) but not IL-23. The MDMs exposed to the gCSC supernatants increased expression of CD80 and B7-H1, and had significantly potentiated secretion of TGF-β1 (106.3 - 3001.8 pg/106 cells/24 hours) and IL-23 (176.8 - 5650.6 pg/106 cells/24 hours). The induced TGF-β1 and IL-23 correlated with inhibition of T cell proliferation and the induction of Tregs. MDM phagocytosis was markedly inhibited by the gCSC supernatants, and physiological amounts of recombinant MIC-1 and MIF. Similar findings were obtained with the human microglia. The gCSC supernatants up-regulated p-STAT3 in the MDMs; however the M2 phenotype could be reversed when p-STAT3 was blocked in either the gCSCs or the MDMs.

Conclusions: The gCSCs secrete factors such as MIC-1 and MIF that can induce immune suppression in macrophages characterized by altered expression of cell surface markers, increased secretion of TGF-β1 and IL-23 with the associated ability to inhibit T cell proliferation and induce Tregs, and impaired phagocytosis. The M2 phenotype is reversed with p-STAT3 blockade.

Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5322.

Abstract 4305: Refinement of the glioma cancer stem cell marker profile

Infiltrating gliomas are the most frequently occurring adult brain tumor and, among high-grade forms, typically result in poor patient survival. These tumors tend to be refractory to most treatments, including aggressive surgical resection and chemoradiation. This treatment resistance is hypothesized to be the result of a small population of cells within the tumor which are responsible for tumor initiation, called glioma cancer stem cells (GCSCs). As is true in other stem cell systems, such as hematopoiesis, multiple cell-surface protein markers are needed to accurately define the true stem cell population. We and others have previously identified the glycoprotein podoplanin (pdpn) as a marker of GCSC, which improves upon the established marker, CD133. To refine the GCSC marker profile beyond these two proteins, we examined a number of candidate markers in combination with pdpn that have been proposed as stem cell markers in gliomas or other tumors or tissues. Candidate markers were analyzed by flow cytometry using primary glioma cell lines maintained as neurosphere cultures and fresh tumor specimens. Markers identifying a unique cell population either alone or in combination with pdpn were further analyzed by in vitro neurosphere formation assay and clonogenic survival assay following 2 Gy ionizing radiation. Candidates showing enrichment for stem cells based on these assays were examine for in vivo tumor initiation using flow sorted subpopulations of cells with and without the expression of the candidate protein. As expression of putative stem cell markers will likely predict for poor patient survival, candidate markers were also examined in human tumors by immunohistochemsitry. Among the most promosing candidates were CD97, CXCR4, CD58 and CD44. Flow cytometry revealed CD97 expression in 75%, CD58 in 80%, CXCR4 in 100%, and CD44 in 100% of tumors examined to date. Examination of primary neurosphere cultures, found CD97 in 80%, CXCR4 in 83%, CD58 in 100%, and CD44 in 100% of lines examined. Both CD44+ and CD58+ cells exhibited increased neurophere formation rates and in vivo tumor initiation. These stem-like characteristics were enhanced in those subpopulations also expressing pdpn. RNAs collected from these subpopulations were used for expression profiling to determine if these subpopulation express a unique gene expression. Results thus far indicate that pdpn expression is needed for the stem-like phenotype and that this is enhanced in populations co-expressing CD44, CD15, and/or CD58. Further refinement of this profile will aide in the isolation of the “true” GCSC and allow for improved therapeutic targeting of these resistant cells.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4305.

Quantitative phosphoproteomic analysis of the STAT3/IL-6/HIF1alpha signaling network: an initial study in GSC11 glioblastoma stem cells

Initiation and maintenance of several cancers including glioblastoma (GBM) may be driven by a small subset of cells called cancer stem cells (CSCs). CSCs may provide a repository of cells in tumor cell populations that are refractory to chemotherapeutic agents developed for the treatment of tumors. STAT3 is a key transcription factor associated with regulation of multiple stem cell types. Recently, a novel autocrine loop (IL-6/STAT3/HIF1alpha) has been observed in multiple tumor types (pancreatic, prostate, lung, and colon). The objective of this study was to probe perturbations of this loop in a glioblastoma cancer stem cell line (GSC11) derived from a human tumor by use of a JAK2/STAT3 phosphorylation inhibitor (WP1193), IL-6 stimulation, and hypoxia. A quantitative phosphoproteomic approach that employed phosphoprotein enrichment, chemical tagging with isobaric tags, phosphopeptide enrichment, and tandem mass spectrometry in a high-resolution instrument was applied. A total of 3414 proteins were identified in this study. A rapid Western blotting technique (<1 h) was used to confirm alterations in key protein expression and phosphorylation levels observed in the mass spectrometric experiments. About 10% of the phosphoproteins were linked to the IL-6 pathway, and the majority of remaining proteins could be assigned to other interlinked networks. By multiple comparisons between the sample conditions, we observed expected changes and gained novel insights into the contribution of each factor to the IL6/STAT3/HIF1alpha autocrine loop and the CSC response to perturbations by hypoxia, inhibition of STAT3 phosphorylation, and IL-6 stimulation.

Platelet-derived growth factor BB mediates the tropism of human mesenchymal stem cells for malignant gliomas

OBJECTIVE

Bone marrow-derived human mesenchymal stem cells (hMSCs) are capable of localizing to gliomas after systemic delivery and can be used in glioma therapy. However, the mechanism underlying the tropism of hMSCs for gliomas remains unclear. In vitro studies suggest that platelet-derived growth factor BB (PDGF-BB) may mediate this tropism. However, a causal role of PDGF-BB has not been demonstrated in vivo. Therefore, we tested the hypothesis that PDGF-BB mediates the attraction of hMSCs to gliomas in vitro and in vivo.

METHODS

U87 or LN229 glioma cells were transfected with plasmids encoding human PDGF-B. Stable transfected clones that secreted large amounts of PDFG-BB and clones that produced low levels of PDGF were chosen. In vitro migration of hMSCs toward PDGF-B or conditioned media from high- and low-secreting PDGF-B tumor cells was assessed using Matrigel invasion assays. For in vivo localization studies, hMSCs were tracked by bioluminescence imaging (BLI) after transduction with an adenovirus containing luciferase cDNA. In other studies, hMSCs were labeled with green fluorescent protein (gfp) and analyzed for intratumoral localization by immunohistochemistry.

RESULTS

In vitro invasion assays showed that significantly more hMSCs migrated toward glioma cells engineered to secrete high levels of PDGF-BB compared with low-secreting gliomas. Anti-PDGF-BB-neutralizing antibody abrogated this increase in migration. Pretreatment of hMSCs with inhibitory antibodies against PDGF receptor-beta also reduced hMSC migration. To demonstrate that PDGF-BB mediates the localization of hMSCs in vivo, hMSCs-Ad-Luc were injected into the carotid artery of mice harboring orthotopic 7-day-old U87-PDGF-BB-high secreting or U87-PDGF-BB-low secreting xenografts and analyzed by BLI. Statistically significant increases in hMSCs were seen within PDGF-BB-high xenografts compared with PDGF-BB-low xenografts. To control for PDGF-BB-induced differences in tumor size and vascularity, gfp-labeled hMSCs were injected into the carotid arteries of animals harboring 4-day old PDGF-BB-high secreting xenografts or 7-day old PDGF-BB-low secreting xenografts. At these times tumors had similar size and vessel density. Statistically significant more hMSCs localized to PDGF-BB-high secreting xenografts compared with PDGF-BB-low secreting xenografts. Pretreatment of hMSCs with anti-PDGFR-beta-inhibitory antibodies decreased the localization of hMSCs in this intracranial model.

CONCLUSION

PDGF-BB increases the attraction of hMSCs for gliomas in vitro and in vivo, and this tropism is mediated via PDGF-beta receptors on hMSCs. These findings can be exploited for advancing hMSC treatment.

Adjuvant whole-brain radiation therapy after surgical resection of single brain metastases

Adjuvant whole-brain radiation therapy (WBRT) after resection of single brain metastases remains controversial. Despite a phase III trial to the contrary, clinicians often withhold WBRT after resection of single brain metastases based on the argument that available evidence does not inform regarding treatment of all patients, such as those with radioresistant tumors. However, there is limited information about whether subpopulations benefit equally from WBRT after resection. Therefore, we undertook a retrospective study to determine the clinical, radiographic, and histologic features that influenced the effectiveness of adjuvant WBRT. We reviewed 358 patients with newly diagnosed, single brain metastases, who underwent resection, of which 142 (40%) received adjuvant WBRT and 216 (60%) did not. Median follow-up was 60.1 months. There were multiple tumor histologies, including 197 (55%) "radiosensitive" and 161 (45%) "radioresistant" tumors. Compared with observation, WBRT significantly reduced recurrence both locally (HR = 0.58; 95% CI 0.35-0.98, P = .04) and at distant brain sites (HR = 0.43, 95% CI 0.30-0.61, P < .001). Multivariate analyses demonstrated that withholding WBRT was an independent predictor of local and distant recurrence. For local recurrence, tumors with a maximum diameter of ≥3 cm that did not receive adjuvant WBRT had an increased risk of recurring locally (HR = 3.14, 95% CI 1.02-9.69, P = .05). For distant recurrence, patients whose primary disease was progressing and who did not receive WBRT had an increased risk of distant recurrence (HR = 2.16, 95% CI 1.01-4.66, P = .05). There was no effect of WBRT based on tumor type. Adjuvant WBRT significantly reduces local and distant recurrences in subsets of patients, particularly those with metastases >3 cm or with active systemic disease.

Oncolytic adenovirus: preclinical and clinical studies in patients with human malignant gliomas

Oncolytic adenoviruses are emerging as a promising alternative therapy for glioma patients and are currently being tested in clinic. In this review, we summarize our experience with gene-based therapy targeting RB pathway in gliomas. Our study has evolved from the development of RB-expressing adenoviral vectors to the characterization of the oncolytic effects on gliomas of the replication competent adenoviruses Delta-24, Delta-24-RGD and ICOVIR. We also review the successful combination of the viruses with chemotherapies that are routinely used in glioma patients, the efficacy of Delta-24-RGD against brain tumor stem cells, the newly described adenovirus-induced autophagy and the potential for the systemic delivery of the oncolytic viruses with human mesenchymal stem cells. Finally, we comment on the preclinical and clinical studies of p53 expressing adenoviral vector and the lessons learned from the experience of Onyx-015, the first oncolytic adenovirus tested in clinical setting.

Glioma-associated cancer-initiating cells induce immunosuppression

PURPOSE

Glioblastoma multiforme is a lethal cancer that responds poorly to therapy. Glioblastoma multiforme cancer-initiating cells have been shown to mediate resistance to both chemotherapy and radiation; however, it is unknown to what extent these cells contribute to the profound immunosuppression in glioblastoma multiforme patients and if strategies that alter their differentiation state can reduce this immunosuppression.

EXPERIMENTAL DESIGN

We isolated a subpopulation of cells from glioblastoma multiforme that possessed the capacity for self-renewal, formed neurospheres in vitro, were capable of pluripotent differentiation, and could initiate tumors in vivo. The immune phenotype of these cells was characterized including the elaboration of immunosuppressive cytokines and chemokines by ELISA. Functional immunosuppressive properties were characterized based on the inhibition of T-cell proliferation and effector responses, triggering of T-cell apoptosis, and induction of FoxP3(+) regulatory T cells. On altering their differentiation state, the immunosuppressive phenotype and functional assays were reevaluated.

RESULTS

We found that the cancer-initiating cells markedly inhibited T-cell proliferation and activation, induced regulatory T cells, and triggered T-cell apoptosis that was mediated by B7-H1 and soluble Galectin-3. These immunosuppressive properties were diminished on altering the differentiation of the cancer-initiating cells.

CONCLUSION

Cancer-initiating cells contribute to tumor evasion of the immunosurveillance and approaches that alter the differentiation state may have immunotherapeutic potential.

Glioblastoma cancer-initiating cells inhibit T-cell proliferation and effector responses by the signal transducers and activators of transcription 3 pathway

Glioblastoma multiforme (GBM) is a lethal cancer that responds poorly to radiotherapy and chemotherapy. Glioma cancer-initiating cells have been shown to recapitulate the characteristic features of GBM and mediate chemotherapy and radiation resistance. However, it is unknown whether the cancer-initiating cells contribute to the profound immune suppression in GBM patients. Recent studies have found that the activated form of signal transducer and activator of transcription 3 (STAT3) is a key mediator in GBM immunosuppression. We isolated and generated CD133+ cancer-initiating single colonies from GBM patients and investigated their immune-suppressive properties. We found that the cancer-initiating cells inhibited T-cell proliferation and activation, induced regulatory T cells, and triggered T-cell apoptosis. The STAT3 pathway is constitutively active in these clones and the immunosuppressive properties were markedly diminished when the STAT3 pathway was blocked in the cancer-initiating cells. These findings indicate that cancer-initiating cells contribute to the immune evasion of GBM and that blockade of the STAT3 pathway has therapeutic potential.

High rate of deletion of chromosomes 1p and 19q in insular oligodendroglial tumors

It has been reported recently that oligodendroglial tumors arising in the insula rarely harbor co-deletions of chromosomes 1p and 19q, a molecular signature which is associated with a good prognosis and increased responsiveness to radiation and chemotherapy compared with tumors in which 1p and/or 19q is intact. In the context of this claim, we analyzed a series of insular oligodendroglial tumors in order to determine the frequency of 1p/19q co-deletion in tumors arising in this region. We identified 14 insular cases operated on after 2003 in which testing for losses of 1p and 19q was performed. Of these cases, co-deletion of 1p and 19q occurred in eight (57%). Four (50%) of eight oligodendrogliomas and four (67%) of six oligoastrocytomas demonstrated 1p/19q co-deletions. Seven of the eight tumors with co-deletion of 1p/19q were WHO grade II gliomas. There were no statistical differences between tumors with 1p/19q co-deletion compared to those with 1p and/or 19q intact in terms of age, preoperative KPS, presenting symptoms, left versus right lateralization, tumor location (purely insular versus extension into frontal or temporal lobe), preoperative tumor size. There was a preponderance of females in the co-deletion group, and a greater average extent of resection. In contradistinction to previous reports, loss of 1p/19q occurs commonly in insular oligodendroglial tumors. With respect to 1p/19q, insular gliomas do not appear to be distinct from gliomas arising elsewhere in the brain.

Bilateral gonadoblastoma with dysgerminoma and pilocytic astrocytoma with WT1 GT-IVS9 mutation: A 46 XY phenotypic female with Frasier syndrome

Frasier syndrome is characterized by a 46 XY disorder of sex development, nephropathy, and increased risk for gonadoblastoma due to Wilms tumor 1(WT1) mutation in the donor splice site of intron-9, resulting in the splice form +KTS. Germ cell tumors and gonadoblastomas have been reported previously in Frasier syndrome. We present the clinical, radiological, and genetic (WT1 mutation analysis) of a 46 XY phenotypic female with Frasier syndrome with bilateral gonadoblastoma with dysgerminoma who developed pilocytic astrocytoma.

Human bone marrow-derived mesenchymal stem cells for intravascular delivery of oncolytic adenovirus Delta24-RGD to human gliomas

Delta24-RGD is an infectivity-augmented, conditionally replicative oncolytic adenovirus with significant antiglioma effects. Although intratumoral delivery of Delta24-RGD may be effective, intravascular delivery would improve successful application in humans. Due to their tumor tropic properties, we hypothesized that human mesenchymal stem cells (hMSC) could be harnessed as intravascular delivery vehicles of Delta24-RGD to human gliomas. To assess cellular events, green fluorescent protein-labeled hMSCs carrying Delta24-RGD (hMSC-Delta24) were injected into the carotid artery of mice harboring orthotopic U87MG or U251-V121 xenografts and brain sections were analyzed by immunofluorescence for green fluorescent protein and viral proteins (E1A and hexon) at increasing times. hMSC-Delta24 selectively localized to glioma xenografts and released Delta24-RGD, which subsequently infected glioma cells. To determine efficacy, mice were implanted with luciferase- labeled glioma xenografts, treated with hMSC-Delta24 or controls, and imaged weekly by bioluminescence imaging. Analysis of tumor size by bioluminescence imaging showed inhibition of glioma growth and eradication of tumors in hMSC-Delta24-treated animals compared with controls (P < 0.0001). There was an increase in median survival from 42 days in controls to 75.5 days in hMSC-Delta24-treated animals (P < 0.0001) and an increase in survival beyond 80 days from 0% to 37.5%, respectively. We conclude that intra-arterially delivered hMSC-Delta24 selectively localize to human gliomas and are capable of delivering and releasing Delta24-RGD into the tumor, resulting in improved survival and tumor eradication in subsets of mice.

Stereotactic radiosurgery for metastatic brain tumors: a comprehensive review of complications

Object

Stereotactic radiosurgery (SRS) is commonly used to treat brain metastases. Complications associated with this treatment are underreported. The authors reviewed a large series of patients who underwent SRS for brain metastases to identify complications and factors predicting their occurrence.

Methods

Prospectively collected clinical data from 273 patients undergoing SRS for 1 or 2 brain metastases at The University of Texas M. D. Anderson Cancer Center between June 1993 and December 2004 were reviewed. Patients who had received prior treatment for their tumor, including whole-brain radiation, SRS, or surgery, were excluded from the study. Data on adverse neurological and nonneurological outcomes following treatment were collected.

Results

Three hundred sixteen lesions were treated. Complications were associated with 127 (40%) of 316 treated lesions. New neurological complications were associated with 101 (32%) of 316 lesions. The onset of seizure was the most common complication, occurring in 41 (13%) of 316 SRS cases. On multivariate analysis, progressing primary cancer (hazard ratio [HR] = 2.4, 95% CI 1.6–3.6, p < 0.001), tumor location in eloquent cortex (HR = 2.3, 95% CI 1.6–3.4, p < 0.001), and lower (< 15 Gy) SRS dose (HR = 2.1, 95% CI 1.1–4.2, p = 0.04) were significantly associated with new complications. On multivariate analysis, a tumor location in the eloquent cortex (HR = 2.5, 95% CI 1.6–3.8, p < 0.001) and progressing primary cancer (HR = 1.6, 95% CI 1.1–2.5, p = 0.03) were significantly associated with new neurological complications.

Conclusions

The authors showed that new neurological and nonneurological complications were associated with 40% of SRS treatments for brain metastases. Patients with lesions in functional brain regions have a significantly increased risk of treatment-related complications.

An orthotopic murine model of human spinal metastasis: histological and functional correlations

OBJECT

There is currently no reproducible animal model of human spinal metastasis that allows for laboratory study of the human disease. Consequently, the authors sought to develop an orthotopic model of spinal metastasis by using a human lung cancer cell line, and to correlate neurological decline with tumor growth.

METHODS

To establish a model of spinal metastasis, the authors used a transperitoneal surgical approach to implant PC-14 lung tumors into the L-3 vertebral body of nude mice via a drill hole. In 24 animals, motor function was scored daily by using the validated semiquantitative Basso-Beattie-Bresnahan (BBB) scale. A second group of 26 animals (6 or 7 per time point) were sacrificed at specific times, and the spines were removed, sectioned, and stained. Canal compromise was analyzed quantitatively by determining the ratio of the area of the neural elements to the area of the spinal canal on histological sections (neural/canal ratio). Correlations between BBB score and histological evaluation of tumor growth were assessed.

RESULTS

Lung cancer xenografts grew in all animals undergoing functional evaluation (24 mice) according to a reliable and reproducible time course, with paraplegia occurring at a median interval of 30 days following tumor implantation (95% CI 28.1-31.9 days). Importantly, the analysis defined 4 key milestones based on components of the BBB score; these were observed in all animals, were consistent, and correlated with histological progression of tumor. From Days 1 to 14, the mean BBB score declined from 21 to 19. The animals progressed from normal walking with the tail up to walking with the tail constantly touching the ground (milestone 1). The median time to tail dragging was 12 days (95% CI 10.8-13.2). Histological studies on Day 14 demonstrated that tumor had progressed from partial to complete VB infiltration, with initial compression of the neural elements and epidural tumor extension to adjacent levels (mean neural/canal ratio 0.32 +/- 0.05, 7 mice). From Days 15 to 20/21 (left/right leg), the mean BBB score declined from 19 to 14. Animals showed gait deterioration, with the development of dorsal stepping (milestone 2). The median time to dorsal stepping was 21 days (95% CI 19.4-22.6) in the left hindlimb and 23 days (95% CI 20.6-25.4) in the right hindlimb. Histological studies on Day 21 demonstrated an increase in the severity of the neural element compression, with tumor extending to adjacent epidural and osseous levels (mean neural/canal ratio 0.19 +/- 0.05, 6 mice). From Days 22 to 26/27 (left/right leg), the mean BBB score declined from 14 to 8. Animals had progressive difficulty ambulating, to the point where they showed only sweeping movements of the hindlimb (milestone 3). The median time to hindlimb sweeping was 26 days (95% CI 23.6-28.4) and 28 days (95% CI 27.1-28.9) in the left and right hindlimbs, respectively. Histological studies on Day 28 revealed progressive obliteration of the spinal canal (mean neural/canal ratio 0.09 +/- 0.01, 7 mice). From Days 29 to 36, the animals progressed to paralysis (milestone 4). The median time to paralysis was 29 days (95% CI 27.6-30.4) and 30 days (95% CI 28.1-31.9) in the left and right hindlimbs, respectively.

CONCLUSIONS

The authors have developed an orthotopic murine model of human spinal metastasis in which neurological decline reproducibly correlates with severity of tumor progression. Although developed for lung cancer, this model can be expanded to study other types of metastatic or primary spinal tumors. Ultimately, this will allow testing of targeted therapies against specific tumor types.

Awake craniotomy for brain tumors near eloquent cortex: correlation of intraoperative cortical mapping with neurological outcomes in 309 consecutive patients

OBJECTIVE

Intraoperative localization of cortical areas for motor and language function has been advocated to minimize postoperative neurological deficits. We report herein the results of a retrospective study of cortical mapping and subsequent clinical outcomes in a large series of patients.

METHODS

Patients with intracerebral tumors near and/or within eloquent cortices (n = 309) were clinically evaluated before surgery, immediately after, and 1 month and 3 months after surgery. Craniotomy was tailored to encompass tumor plus adjacent areas presumed to contain eloquent cortex. Intraoperative cortical stimulation for language, motor, and/or sensory function was performed in all patients to safely maximize surgical resection.

RESULTS

A gross total resection (> or =95%) was obtained in 64%, and a resection of 85% or more was obtained in 77% of the procedures. Eloquent areas were identified in 65% of cases, and in that group, worsened neurological deficits were observed in 21% of patients, whereas only 9% with negative mapping sustained such deficits (P < 0.01). Intraoperative neurological deficits occurred in 64 patients (21%); of these, 25 (39%) experienced worsened neurological outcome at 1 month, whereas only 27 of 245 patients (11%) without intraoperative changes had such outcomes (P < 0.001). At 1 month, 83% overall showed improved or stable neurological status, whereas 17% had new or worse deficits; however, at 3 months, 7% of patients had a persistent neurological deficit. Extent of resection less than 95% also predicted worsening of neurological status (P < 0.025).

CONCLUSION

Negative mapping of eloquent areas provides a safe margin for surgical resection with a low incidence of neurological deficits. However, identification of eloquent areas not only failed to eliminate but rather increased the risk of postoperative deficits, likely indicating close proximity of functional cortex to tumor.

Physiologic oxygen concentration enhances the stem-like properties of CD133+ human glioblastoma cells in vitro

In vitro investigations of tumor stem-like cells (TSC) isolated from human glioblastoma (GB) surgical specimens have been done primarily at an atmospheric oxygen level of 20%. To determine whether an oxygen level more consistent with in situ conditions affects their stem cell-like characteristics, we compared GB TSCs grown under conditions of 20% and 7% oxygen. Growing CD133(+) cells sorted from three GB neurosphere cultures at 7% O(2) reduced their doubling time and increased the self-renewal potential as reflected by clonogenicity. Furthermore, at 7% oxygen, the cultures exhibited an enhanced capacity to differentiate along both the glial and neuronal pathways. As compared with 20%, growth at 7% oxygen resulted in an increase in the expression levels of the neural stem cell markers CD133 and nestin as well as the stem cell markers Oct4 and Sox2. In addition, whereas hypoxia inducible factor 1alpha was not affected in CD133(+) TSCs grown at 7% O(2), hypoxia-inducible factor 2alpha was expressed at higher levels as compared with 20% oxygen. Gene expression profiles generated by microarray analysis revealed that reducing oxygen level to 7% resulted in the up-regulation and down-regulation of a significant number of genes, with more than 140 being commonly affected among the three CD133(+) cultures. Furthermore, Gene Ontology categories up-regulated at 7% oxygen included those associated with stem cells or GB TSCs. Thus, the data presented indicate that growth at the more physiologically relevant oxygen level of 7% enhances the stem cell-like phenotype of CD133(+) GB cells.

Phosphorylation of Thr18 and Ser20 of p53 in Ad-p53-induced apoptosis

The p53 protein plays a critical role in inducing cell cycle arrest or apoptosis. Because p53 is inactivated in human gliomas, restoring p53 function is a major focus of glioma therapy. The most clinically tested strategy for replacing p53 has been adenoviral-mediated p53 gene therapy (Ad-p53). In addition to their therapeutic implications, investigations into Ad-p53 provide model systems for understanding p53's ability to induce cell cycle arrest versus apoptosis, particularly because wild-type p53 cells are resistant to Ad-p53-induced apoptosis. Here we use Ad-p53 constructs to test the hypothesis that simultaneous phosphorylation of p53 at threonine 18 (Thr18) and serine 20 (Ser20) is causally associated with p53-mediated apoptosis. Studies using phosphorylation-specific antibodies demonstrated that p53-induced apoptosis correlates with phosphorylation of p53 at Thr18 and Ser20 but not with carboxy-terminal phosphorylation (Ser392). To prove a causal relationship between apoptosis and Thr18 and Ser20 phosphorylation of p53, the effects of an adenoviral p53 construct that was not phosphorylated (Ad-p53) was compared with a Thr18/Ser20 phosphomimetic construct (Ad-p53-18D20D) in wild-type p53 gliomas. Whereas treatment with Ad-p53 resulted only in cell cycle arrest, treatment with Ad-p53-18D20D induced dramatic apoptosis. Microarray and Western blot analyses showed that only Ad-p53-18D20D was capable of inducing expression of apoptosis-inducing proteins. Chromatin immunoprecipitation assays indicated that the protein product of Ad-p53-18D20D, but not Ad-p53, was capable of binding to apoptosis-related genes. We thus conclude that phosphorylation of Thr18 and Ser20 is sufficient for inducing p53-mediated apoptosis in glioma cells. These results have implications for p53 gene therapy and inform other strategies that aim to restore p53 function.

CONVECTION-ENHANCED DELIVERY OF CINTREDEKIN BESUDOTOX (INTERLEUKIN-13-PE38QQR) FOLLOWED BY RADIATION THERAPY WITH AND WITHOUT TEMOZOLOMIDE IN NEWLY DIAGNOSED MALIGNANT GLIOMAS

OBJECTIVE

Cintredekin besudotox (CB), a recombinant cytotoxin consisting of interleukin-13 and truncated Pseudomonas exotoxin, binds selectively to interleukin-13Rα2 receptors overexpressed by malignant gliomas. This study assessed the safety of CB administered by convection-enhanced delivery followed by standard external beam radiation therapy (EBRT) with or without temozolomide (Temodar; Schering-Plough, Kenilworth, NJ) in patients with newly diagnosed malignant gliomas.

METHODS

After gross total resection of the tumor, two to four intraparenchymal catheters were stereotactically placed and CB (0.25 or 0.5 μg/mL) was infused for 96 hours. This was followed, 10 to 14 days later, by EBRT (5940–6100 cGy, 5 d/wk for 6–7 wk) with or without temozolomide (75 mg/m2/d, 7 d/wk during EBRT). Safety was assessed during an 11-week observation period after catheter placement

RESULTS

Twenty-two patients (12 men, 10 women; median age, 55 yr; 21 with glioblastoma multiforme and one with an anaplastic mixed oligoastrocytoma) were enrolled. None of the patients experienced dose-limiting toxicities in the first two cohorts (0.25 μg/mL CB + EBRT [n = 3] and 0.25 μg/mL CB + EBRT + temozolomide [n = 3]). One patient experienced a dose-limiting toxicity (Grade 4 seizure) in the third cohort (0.5 μg/mL CB + EBRT [n = 6]). Six patients in the final cohort (0.5 μg/mL CB + EBRT + temozolomide [n = 10]) completed treatment, and one patient experienced a dose-limiting toxicity (Grade 3 aphasia and confusion). Four patients were not considered evaluable for a dose decision and were replaced. CB related adverse events occurring in more than one patient were fatigue, gait disturbance, nystagmus, and confusion. No Grade 3 to 4 hematological toxicities were observed.

CONCLUSION

CB (0.5 μg/mL) administered via convection-enhanced delivery before standard radiochemotherapy seems to be well tolerated in adults with newly diagnosed malignant gliomas. Further clinical study assessment is warranted.

ICOVIR-5 shows E2F1 addiction and potent antiglioma effect in vivo

During 2007, approximately 200,000 people in the United States will be diagnosed with brain tumors. Gliomas account for 77% of primary malignant brain tumors, and the prognosis has hardly changed in the past 20 years, with only 30% of patients with malignant glioma surviving 5 years after diagnosis. Oncolytic adenoviruses are promising therapies for the treatment of gliomas. Here, report the antiglioma activity of the tumor-selective ICOVIR-5 adenovirus, which encompasses an early 1A adenoviral (E1A) deletion in the retinoblastoma (Rb) protein-binding region, substitution of the E1A promoter for E2F-responsive elements, and an RGD-4C peptide motif inserted into the adenoviral fiber to enhance adenoviral tropism. Mechanistic studies showed a dramatic addiction of ICOVIR-5 to the E2F1 oncogene in vitro and in vivo. This addiction was mediated by the occupancy of the ectopic adenoviral E2F1-responsive elements by the endogenous E2F1 protein resulting in high level of E1A expression in cancer cells and potent antiglioma effect. Importantly, we showed for the first time the ability of oncolytic adenoviruses to enhance E2F transcriptional activity in vivo, and we provided direct evidence of the interaction of the E2F1 protein with native and ectopic adenovirus promoters. Restoration of Rb function led to the association of Rb/E2F1 repressor complexes with ICOVIR-5 ectopic E2F1 promoter and subsequent down-modulation of E1A, dramatically impairing adenoviral replication. In xenografted mice, intratumoral injection of ICOVIR-5 resulted in a significant improvement of the median survival (P < 0.0001), and furthermore, led to 37% of long-term survivors free of disease. The antitumor activity of ICOVIR-5 suggests that it has the potential to be an effective agent in the treatment of gliomas.

Examination of the therapeutic potential of Delta-24-RGD in brain tumor stem cells: role of autophagic cell death

The eradication of brain tumor stem cells is essential for long-term brain tumor remission after treatment. In this study, we examined the therapeutic potential of an oncolytic adenovirus, Delta-24-RGD, targeted to the abnormal p16INK4/Rb pathway in brain tumor stem cells. Four brain tumor stem cell lines from surgical glioblastoma specimens expressed high levels of adenoviral receptors and allowed for efficient viral infection, replication, and oncolysis in an Rb-dependent manner. Delta-24-RGD induced autophagic cell death, as indicated by accumulation of Atg5 and LC3-II protein and autophagic vacuoles. Treatment of xenografts derived from brain tumor stem cells with Delta-24-RGD statistically significantly improved the survival of glioma-bearing mice (means: 38.5 versus 66.3 days, difference = 27.8 days, 95% confidence interval = 19.5 to 35.9 days, P <.001). Analyses of treated tumors showed that Atg5 expression colocalized with viral fiber protein and delineated a wave front of autophagic cells that circumscribed areas of virally induced necrosis. Our results show for the first time that brain tumor stem cells are susceptible to adenovirus-mediated cell death via autophagy in vitro and in vivo.

Papillary Tumors of the Pineal Region: Case Report

OBJECTIVE

The pineal region is a rare intracranial site for metastasis. We report three patients initially considered to have metastatic papillary adenocarcinoma to the pineal region. On review, these papillary, keratin-positive neoplasms meet the criteria for papillary tumor of the pineal region (PTPR).

CLINICAL PRESENTATION

These neoplasms occurred in three women (age range, 37–55 yr). Imaging studies demonstrated well-circumscribed lesions in the pineal region. All patients presented with obstructive hydrocephalus and symptoms attributable to hydrocephalus and tectal compression.

INTERVENTION

All three patients underwent near total microsurgical resection of the pineal region neoplasm, followed by adjuvant radiotherapy. The two patients with long-term follow-up (56–60 mo) have remained clinically stable without evidence of local or distant recurrence. The first two patients were initially diagnosed as having papillary metastatic carcinoma of unknown origin. The third patient was treated after the recent description of PTPR and met the histopathological diagnostic criteria. Retrospective pathological review of the previous two patients resulted in designation as PTPR.

CONCLUSION

The morphological features of the tumors in our series, along with the clinical presentations, are similar to those in the original description of the PTPR. Our findings agree with the original hypothesis that the cells composing the PTPR are similar to ependymal cells of the subcommissural organ, thus furthering the hypothesis that the PTPR derives from a specialized ependymocyte associated with the subcommissural organ. The two patients with long-term follow-up (56–60 mo) have remained clinically stable without evidence of local or distant recurrence.