Defining Glioblastoma Resectability Through the Wisdom of the Crowd: A Proof-of-Principle Study.

BACKGROUND: Extent of resection (EOR) correlates with glioblastoma outcomes. Resectability and EOR depend on anatomical, clinical, and surgeon factors. Resectability likely influences outcome in and of itself, but an accurate measurement of resectability remains elusive. An understanding of resectability and the factors that influence it may provide a means to control a confounder in clinical trials and provide reference for decision making. OBJECTIVE: To provide proof of concept of the use of the collective wisdom of experienced brain tumor surgeons in assessing glioblastoma resectability. METHODS: We surveyed 13 academic tumor neurosurgeons nationwide to assess the resectability of newly diagnosed glioblastoma. Participants reviewed 20 cases, including digital imaging and communications in medicine-formatted pre- and postoperative magnetic resonance images and clinical vignettes. The selected cases involved a variety of anatomical locations and a range of EOR. Participants were asked about surgical goal, eg, gross total resection, subtotal resection (STR), or biopsy, and rationale for their decision. We calculated a "resectability index" for each lesion by pooling responses from all 13 surgeons. RESULTS: Neurosurgeons' individual surgical goals varied significantly ( P = .015), but the resectability index calculated from the surgeons' pooled responses was strongly correlated with the percentage of contrast-enhancing residual tumor ( R = 0.817, P < .001). The collective STR goal predicted intraoperative decision of intentional STR documented on operative notes ( P < .01) and nonresectable residual ( P < .01), but not resectable residual. CONCLUSION: In this pilot study, we demonstrate the feasibility of measuring the resectability of glioblastoma through crowdsourcing. This tool could be used to quantify resectability, a potential confounder in neuro-oncology clinical trials.

Development of a Single-Cell Migration and Extravasation Platform through Selective Surface Modification.

Cell migration through three-dimensional (3D) tissue spaces is integral to many biological and pathological processes, including metastasis. Circulating tumor cells (CTCs) are phenotypically heterogeneous, and in vitro analysis of their extravasation behavior is often impeded by the inability to establish complex tissue-like extracellular matrix (ECM) environments and chemotactic gradients within microfluidic devices. We have developed a novel microfluidic strategy to manipulate surface properties of enclosed microchannels and create 3D ECM structures for real-time observation of individual migrating cells. The wettability of selective interconnected channels is controlled by a plasma pulse, enabling the incorporation of ECM exclusively within the transmigration regions. We applied this approach to collectively analyze CTC-endothelial adhesion, trans-endothelial migration, and subsequent motility of breast cancer cells (MDA-MB-231) through a 3D ECM under artificial gradients of SDF-1α. We observed migration velocities ranging from 5.12 to 12.8 µm/h, which closely correspond to single-cell migration in collagen blocks, but are significantly faster than the migration of cell aggregates. The compartmentalized microchannels separated by the porous ECM makes this in vitro assay versatile and suitable for a variety of applications such as inflammation studies, drug screening, and coculture interactions.

Phase II trial of hypofractionated intensity-modulated radiation therapy combined with temozolomide and bevacizumab for patients with newly diagnosed glioblastoma.

Bevacizumab blocks the effects of VEGF and may allow for more aggressive radiotherapy schedules. We evaluated the efficacy and toxicity of hypofractionated intensity-modulated radiation therapy with concurrent and adjuvant temozolomide and bevacizumab in patients with newly diagnosed glioblastoma. Patients with newly diagnosed glioblastoma were treated with hypofractionated intensity modulated radiation therapy to the surgical cavity and residual tumor with a 1 cm margin (PTV1) to 60 Gy and to the T2 abnormality with a 1 cm margin (PTV2) to 30 Gy in 10 daily fractions over 2 weeks. Concurrent temozolomide (75 mg/m(2) daily) and bevacizumab (10 mg/kg) was administered followed by adjuvant temozolomide (200 mg/m(2)) on a standard 5/28 day cycle and bevacizumab (10 mg/kg) every 2 weeks for 6 months. Thirty newly diagnosed patients were treated on study. Median PTV1 volume was 131.1 cm(3) and the median PTV2 volume was 342.6 cm(3). Six-month progression-free survival (PFS) was 90 %, with median follow-up of 15.9 months. The median PFS was 14.3 months, with a median overall survival (OS) of 16.3 months. Grade 4 hematologic toxicity included neutropenia (10 %) and thrombocytopenia (17 %). Grades 3/4 non-hematologic toxicity included fatigue (13 %), wound dehiscence (7 %) and stroke, pulmonary embolism and nausea each in 1 patient. Presumed radiation necrosis with clinical decline was seen in 50 % of patients, two with autopsy documentation. The study was closed early to accrual due to this finding. This study demonstrated 90 % 6-month PFS and OS comparable to historic data in patients receiving standard treatment. Bevacizumab did not prevent radiation necrosis associated with this hypofractionated radiation regimen and large PTV volumes may have contributed to high rates of presumed radiation necrosis.

Preoperative ethmoid artery ligation facilitates resection of large sub-frontal meningiomas.

Optimal vascular control during neurosurgical resection of large sub-frontal meningioma is hindered by limited early access to the ethmoidal arteries. Pre-operative ligation of the ethmoidal arteries 1) induces tumor necrosis simplifying resection and 2) minimizes blood loss and operative time. Early arterial ligation is an advantage of endoscopic approaches to transnasal resection of anterior skull base meningiomas that is not appreciated in open approaches with larger meningioma. Here we present a case of a colossal meningioma where minimally invasive pre-operative ligation of ethmoidal arteries prior to a traditional open surgical approach allowed for improved vascular control and decreased surgical time.

Increased immune gene expression and immune cell infiltration in high-grade astrocytoma distinguish long-term from short-term survivors.

Survival in the majority of high-grade astrocytoma (HGA) patients is very poor, with only a rare population of long-term survivors. A better understanding of the biological factors associated with long-term survival in HGA would aid development of more effective therapy and survival prediction. Factors associated with long-term survival have not been extensively studied using unbiased genome-wide expression analyses. In the current study, gene expression microarray profiles of HGA from long-term survivors were interrogated for discovery of survival-associated biological factors. Ontology analyses revealed that increased expression of immune function-related genes was the predominant biological factor that positively correlated with longer survival. A notable T cell signature was present within this prognostic immune gene set. Using immune cell-specific gene classifiers, both T cell-associated and myeloid linage-associated genes were shown to be enriched in HGA from long-term versus short-term survivors. Association of immune function and cell-specific genes with survival was confirmed independently in a larger publicly available glioblastoma gene expression microarray data set. Histology was used to validate the results of microarray analyses in a larger cohort of long-term survivors of HGA. Multivariate analyses demonstrated that increased immune cell infiltration was a significant independent variable contributing to longer survival, as was Karnofsky/Lansky performance score. These data provide evidence of a prognostic anti-tumor adaptive immune response and rationale for future development of immunotherapy in HGA.

Immune gene and cell enrichment is associated with a good prognosis in ependymoma.

Approximately 50% of children with ependymoma will suffer from tumor recurrences that will ultimately lead to death. Development of more effective therapies and patient stratification in ependymoma mandates better prognostication. In this study, tumor gene expression microarray profiles from pediatric ependymoma clinical samples were subject to ontological analyses to identify outcome-associated biological factors. Histology was subsequently used to evaluate the results of ontological analyses. Ontology analyses revealed that genes associated with nonrecurrent ependymoma were predominantly immune function-related. Additionally, increased expression of immune-related genes was correlated with longer time to progression in recurrent ependymoma. Of those genes associated with both the nonrecurrent phenotype and that positively correlated with time to progression, 95% were associated with immune function. Histological analysis of a subset of these immune function genes revealed that their expression was restricted to a subpopulation of tumor-infiltrating cells. Analysis of tumor-infiltrating immune cells showed increased infiltration of CD4(+) T cells in the nonrecurrent ependymomas. No genomic sequences for SV40, BK, JC, or Merkel polyomaviruses were found in nonrecurrent ependymoma. This study reveals that up-regulation of immune function genes is the predominant ontology associated with a good prognosis in ependymoma and it provides preliminary evidence of a beneficial host proinflammatory and/or Ag-specific immune response.

The survival impact of postoperative infection in patients with glioblastoma multiforme.

OBJECTIVE: The capacity for local infection to prolong survival in patients with cancer is a widely accepted but unsubstantiated principle. The neurosurgical literature contains anecdotal reports of patients with malignant gliomas who experienced prolonged remission of their tumors after a bacterial infection. This association has not been explored in a larger series of patients with malignant glioma with postoperative infections. METHODS: A single-center operative experience accumulated over 10 years was examined to evaluate whether postoperative infections conferred a survival advantage in patients with glioblastoma multiforme. A total of 382 patients were examined, and 18 bacterial infections were identified. The vast majority (17 cases, 94%) of these were gram-positive infections. Cases were compared with age-matched controls. Survival differences were evaluated using Kaplan-Meier curves, and other differences were tested using the Mann-Whitney U test. RESULTS: Cases and controls were younger and survived longer than the overall study sample, but cases and controls were similar at baseline. A moderate, statistically insignificant survival advantage was seen in the case group (Kaplan-Meier P = 0.27). However, when patients with infections in the first quarter and first half of their postoperative survival were examined, this survival advantage disappeared. There was no significant survival difference in any subgroup analyzed, including deep infections, bone flap infections, or infections caused by any specific organism. CONCLUSION: In this single-center study, postoperative infection did not confer any survival advantage in patients with glioblastoma multiforme.

Identification of A2B5+CD133- tumor-initiating cells in adult human gliomas.

OBJECTIVE: Several studies have shown that human gliomas contain a small population of cells with stem cell-like features. It has been proposed that these "cancer stem cells" may be uniquely responsible for glioma formation and recurrence. However, human gliomas also contain an abundance of cells that closely resemble more differentiated glial progenitors. Animal model studies have shown that these cells also possess the capacity to form malignant gliomas. METHODS: To investigate the contributions of stem-like and progenitor-like cells in human gliomas, we used flow cytometry to characterize the expression of a cancer stem cell marker (CD133) and a glial progenitor marker (A2B5) in 25 tumors. We found that human gliomas consistently express A2B5 in a large percentage of cells (61.7 +/- 3.8%, standard error of the mean). In contrast, CD133 expression was less abundant and less consistent (14.8 +/- 3.6%, standard error of the mean), with several glioblastomas containing very few or no detectable CD133+ cells. When present, the CD133+ population was almost entirely contained within the A2B5+ population. Thus, most gliomas could be divided into three distinct populations on the basis of these markers (A2B5+CD133+, A2B5+CD133-, and A2B5-CD133-). To test the tumorigenic potential of these populations, we separated cells from six tumors by fluorescence-activated cell sorting and reinjected them into nude rats. RESULTS: We found that the capacity for these different populations to form tumors varied depending on the human tumor specimen from which they were isolated. Of the six human gliomas tested, four contained A2B5+/CD133- cells that formed tumors when transplanted into nude rats, three contained A2B5+/CD133+ cells that formed tumors, and only one glioma contained A2B5-/CD133- cells with the capacity to form tumors. CONCLUSION: Together, these results demonstrate that human gliomas contain multiple populations of cells with the capacity to form tumors and specifically identify a population of tumorigenic A2B5+ cells that are phenotypically distinct from CD133+ cells.

Clinical usefulness and safety of routine intraoperative angiography for patients and personnel.

OBJECTIVE: The routine use of intraoperative angiography (IA) is still surrounded by controversy. We prospectively performed IAs in consecutive patients undergoing surgery for aneurysms, arteriovenous malformations, and dural arteriovenous fistulae. We calculated the percentage of identified residual pathologies, the cases requiring further surgical intervention, and the complication rates associated with the procedure. We also recorded radiation dose received by personnel during IA for comparison with elective procedures. If our review supported the routine use of IA, recommendations should be tempered by radiation dose to personnel regarding whether or not annual exposure would go beyond recommended limits and whether or not radiation doses indicate a need for specialized operating rooms. METHODS: Two hundred and four consecutive IAs were performed on 191 patients over a 2-year period. Angiographic findings were reviewed retrospectively and noted for additional interventions. Complications related to IA were recorded. Radiation doses received by personnel and fluoroscopy times were compiled from 18 IAs. Mean dose/minutes in intraoperative procedures was compared with mean dose/minutes of a separate cohort of 15 elective angiograms (Student's t test). RESULTS: Twenty-three percent of IAs revealed relevant findings. Clip repositioning or additional clip placement was performed in 8% of the patients. Resection of residual arteriovenous malformations or additional surgery for residual arteriovenous shunting in dural arteriovenous fistulae was performed in 2% of the patients. Fewer than 1% of the patients received intra-arterial verapamil or topical papaverine. The complication rate was less than 1%. The mean dose per procedure for physicians was 1.018 microsieverts (uSv) versus 0.988 uSv for technicians (P = 0.94). The mean effective dose/minutes in the angiogram suite was 0.9209 uSv/minute versus 1.213 uSv/minute in the operating room (P = 0.33). CONCLUSION: IA identifies a significant number of pertinent findings during open neurovascular surgery, half of which require additional intervention. It is associated with a low complication rate. Radiation dose received by personnel per procedure is negligible. IA radiation dose is not different from dose in the angiogram suite; thus, specialized operating rooms may not be necessary. These data support routine intraoperative angiography in open surgeries for neurovascular disorders.

Convection-enhanced delivery in the treatment of malignant glioma.

Despite advancements in glioma therapy, median survival remains low because of rapid post-resection recurrence. A regional method of drug delivery to address local invasion may improve clinical outcomes. Convection-enhanced delivery (CED) is a novel therapy that allows distribution of substances throughout the interstitium via positive-pressure infusion. Studies using various agents have investigated the parameters that affect CED including infusion rate, cannula size, infusion volume, extracellular space, particle characteristics and tumor tissue structure. We review models of small animal glioma that have been successfully treated using different substances administered through CED, particularly our favorable results using topotecan in a C6 rat glioma model. We also review Phase I/II trials utilizing CED which have shown promising response rates and acceptable safety profiles. Future studies should include prospective clinical trials and investigation of novel antitumor agents that are ineffective with systemic delivery. Development of a large animal glioma model would enhance pre-clinical investigation of CED. Clinically, methods to monitor distribution of therapeutic agents and real-time patient response should likewise be explored.