Sherise D. Ferguson

MiR-124 inhibits STAT3 signaling to enhance T cell-mediated immune clearance of glioma

miRNAs (miR) have been shown to modulate critical gene transcripts involved in tumorigenesis, but their role in tumor-mediated immunosuppression is largely unknown. On the basis of miRNA gene expression in gliomas using tissue microarrays, in situ hybridization, and molecular modeling, miR-124 was identified as a lead candidate for modulating STAT3 signaling, a key pathway mediating immunosuppression in the tumor microenvironment. miR-124 is absent in all grades and pathologic types of gliomas. Upon upregulating miR-124 in glioma cancer stem cells (gCSC), the STAT3 pathway was inhibited, and miR-124 reversed gCSC-mediated immunosuppression of T-cell proliferation and induction of forkhead box P3 (Foxp3)(+) regulatory T cells (Treg). Treatment of T cells from immunosuppressed glioblastoma patients with miR-124 induced marked effector response including upregulation of interleukin (IL)-2, IFN-γ, and TNF-α. Both systemic administration of miR-124 or adoptive miR-124-transfected T-cell transfers exerted potent anti-glioma therapeutic effects in clonotypic and genetically engineered murine models of glioblastoma and enhanced effector responses in the local tumor microenvironment. These therapeutic effects were ablated in both CD4(+)- and CD8(+)-depleted mice and nude mouse systems, indicating that the therapeutic effect of miR-124 depends on the presence of a T-cell-mediated antitumor immune response. Our findings highlight the potential application of miR-124 as a novel immunotherapeutic agent for neoplasms and serve as a model for identifying miRNAs that can be exploited as immunotherapeutics.

OBESITY AND SELF-REPORTED OUTCOME AFTER MINIMALLY INVASIVE LUMBAR SPINAL FUSION SURGERY

OBJECTIVEMany patients undergoing lumbar spine fusion are overweight or obese. The relationship between body habitus and outcome after lumbar spine fusion surgery is not well defined. METHODSWe analyzed a prospectively maintained database of self-reported pain and quality of life measures, including Visual Analog Scale pain score, Short Form 36, and Oswestry Disability Index. We selected patients undergoing minimally invasive transforaminal lumbar interbody fusion between September 2002 and June 2006 at a single institution. We used linear regression models and mixed-effects linear models to examine the relationships between body habitus and self-reported outcomes. RESULTSThe analysis identified 110 patients meeting the study criteria, with a median follow-up period of 14.8 months. The mean age was 56 years, mean height was 169 cm, and mean weight was 82.2 kg. The mean body mass index (BMI) was 28.7 kg/m2; 31% of patients were overweight (BMI, 25–29.9), and 32% of patients were obese (BMI, >30). Linear regression analysis did not identify a correlation between weight or BMI and pre- and postsurgery changes in any of the outcome measures. The significant findings observed in the mixed-effects linear models were that the changing patterns of Short Form 36 Body Pain subscale and Short Form 36 Vitality subscale varied significantly by category of BMI (P = 0.01 and P = 0.002, respectively), but not significantly if continuous BMI was used (P = 0.53 and P = 0.46, respectively). BMI correlated marginally with estimated blood loss (P = 0.08), but not operative time, length of hospital stay, or complications. CONCLUSIONAmong this cohort of minimally invasive lumbar fusion patients, body habitus measured by BMI, weight, or height did not have a significant relationship with most self-reported outcome measures, operative time, length of hospital stay, or complications. Obesity should not be considered a contraindication to minimally invasive lumbar spinal fusion surgery.

Mesenchymal Stem Cells Modified with a Single-Chain Antibody against EGFRvIII Successfully Inhibit the Growth of Human Xenograft Malignant Glioma

Background Glioblastoma multiforme is the most lethal brain tumor with limited therapeutic options. Antigens expressed on the surface of malignant cells are potential targets for antibody-mediated gene/drug delivery. Principal Findings In this study, we investigated the ability of genetically modified human mesenchymal stem cells (hMSCs) expressing a single-chain antibody (scFv) on their surface against a tumor specific antigen, EGFRvIII, to enhance the therapy of EGFRvIII expressing glioma cells in vivo. The growth of U87-EGFRvIII was specifically delayed in co-culture with hMSC-scFvEGFRvIII. A significant down-regulation was observed in the expression of pAkt in EGFRvIII expressing glioma cells upon culture with hMSC-scFvEGFRvIII vs. controls as well as in EGFRvIII expressing glioma cells from brain tumors co-injected with hMSC-scFvEGFRvIII in vivo. hMSC expressing scFvEGFRvIII also demonstrated several fold enhanced retention in EGFRvIII expressing flank and intracranial glioma xenografts vs. control hMSCs. The growth of U87-EGFRvIII flank xenografts was inhibited by 50% in the presence of hMSC-scFvEGFRvIII (p<0.05). Moreover, animals co-injected with U87-EGFRvIII and hMSC-scFvEGFRvIII intracranially showed significantly improved survival compared to animals injected with U87-EGFRvIII glioma cells alone or with control hMSCs. This survival was further improved when the same animals received an additional dosage of hMSC-scFvEGFRvIII two weeks after initial tumor implantation. Of note, EGFRvIII expressing brain tumors co-injected with hMSCs had a lower density of CD31 expressing blood vessels in comparison with control tumors, suggesting a possible role in tumor angiogenesis. Conclusions/Significance The results presented in this study illustrate that genetically modified MSCs may function as a novel therapeutic vehicle for malignant brain tumors.

Convection Enhanced Drug Delivery of Novel Therapeutic Agents to Malignant Brain Tumors

In spite of conventional treatment modalities which include surgery, chemotherapy, and radiotherapy, the survival rates for patients with malignant gliomas remain disappointing. Successful treatment has been limited by difficulties in delivering therapeutic agents to the central nervous system (CNS). Specifically, drug penetration of the blood brain barrier (BBB) poses a unique and challenging problem in glioma therapy. Recently, however, promising techniques have emerged to circumvent this problem. One such advancement is convection-enhanced delivery (CED). This method was originally introduced and refined in the early 1990s by researchers at the National Institute of Health (NIH) and involves drug infusion under high pressure using intracranial catheters. CED allows for delivery of high concentrations of therapeutic agents directly into brain tumors and surrounding parenchyma. This method eludes the BBB and allows the use of regional drug therapy, while at the same time limiting systemic toxicity. In the present article, we review both the pre-clinical and clinical studies concerning CED. We also discuss future directions and the potential impact of this modality on the treatment of malignant gliomas.

Intranasal Delivery of Mesenchymal Stem Cells Significantly Extends Survival of Irradiated Mice with Experimental Brain Tumors

Treatment options of glioblastoma multiforme are limited due to the blood-brain barrier (BBB). In this study, we investigated the utility of intranasal (IN) delivery as a means of transporting stem cell-based antiglioma therapeutics. We hypothesized that mesenchymal stem cells (MSCs) delivered via nasal application could impart therapeutic efficacy when expressing TNF-related apoptosis-inducing ligand (TRAIL) in a model of human glioma. ¹¹¹In-oxine, histology and magnetic resonance imaging (MRI) were utilized to track MSCs within the brain and associated tumor. We demonstrate that MSCs can penetrate the brain from nasal cavity and infiltrate intracranial glioma xenografts in a mouse model. Furthermore, irradiation of tumor-bearing mice tripled the penetration of (¹¹¹In)-oxine-labeled MSCs in the brain with a fivefold increase in cerebellum. Significant increase in CXCL12 expression was observed in irradiated xenograft tissue, implicating a CXCL12-dependent mechanism of MSCs migration towards irradiated glioma xenografts. Finally, MSCs expressing TRAIL improved the median survival of irradiated mice bearing intracranial U87 glioma xenografts in comparison with nonirradiated and irradiated control mice. Cumulatively, our data suggest that IN delivery of stem cell-based therapeutics is a feasible and highly efficacious treatment modality, allowing for repeated application of modified stem cells to target malignant glioma.

Therapeutic effect of neural stem cells expressing TRAIL and bortezomib in mice with glioma xenografts.

Treatment of glioblastoma remains a challenge in neuro-oncology. We investigated if treatment with neural stem cells engineered to express membrane-bound TRAIL (NSCs-mTRAIL) alone or in combination with proteasome inhibitors is a feasible therapeutic approach for experimental glioma. Glioma cells showed resistance to soluble TRAIL and proteasome inhibitors alone, but responded well to their combined treatment. In co-culture with NSCs-mTRAIL, glioma cells appeared to be more prone to apoptosis than to treatment with soluble TRAIL, which was enhanced by proteasome inhibitor bortezomib. In vivo, the survival of animals bearing intracranial glial xenografts was significantly improved by NSCs-mTRAIL. The addition of bortezomib further enhanced the efficacy of NSCs-TRAIL treated group in one of examined tumor models. These data demonstrate that therapy with NSCs-mTRAIL is a potent cell based approach for treatment of glioma. Such an approach warrants further search for therapeutics capable of increasing sensitivity of glioma cells to mTRAIL in vivo.

Anti-angiogenic therapy increases intratumoral adenovirus distribution by inducing collagen degradation

Conditionally replicating adenoviruses (CRAd) are a promising class of gene therapy agents that can overcome already known glioblastoma (GBM) resistance mechanisms but have limited distribution upon direct intratumoral (i.t.) injection. Collagen bundles in the extracellular matrix (ECM) have an important role in inhibiting virus distribution. In fact, ECM pre-treatment with collagenases improves virus distributions to tumor cells. Matrix metalloproteinases (MMPs) are an endogenous class of collagenases secreted by tumor cells whose function can be altered by different drugs including anti-angiogenic agents, such as bevacizumab. In this study we hypothesized that upregulation of MMP activity during anti-angiogenic therapy can improve CRAd-S-pk7 distribution in GBM. We find that MMP-2 activity in human U251 GBM xenografts increases (*P=0.03) and collagen IV content decreases (*P=0.01) during vascular endothelial growth factor (VEGF-A) antibody neutralization. After proving that collagen IV inhibits CRAd-S-pk7 distribution in U251 xenografts (Spearman rho=−0.38; **P=0.003), we show that VEGF-blocking antibody treatment followed by CRAd-S-pk7 i.t. injection reduces U251 tumor growth more than each individual agent alone (***P<0.0001). Our data propose a novel approach to improve virus distribution in tumors by relying on the early effects of anti-angiogenic therapy.

Arterial diameters on catheter and computed tomographic angiography

BACKGROUND The diagnosis of cerebral vasospasm is hampered by lack of an accurate, noninvasive test. Computed tomographic angiography (CTA) may be useful but the correlation between arterial diameters determined from catheter digital subtraction angiography (DSA) and CTA over a range of artery sizes would need to be determined to show this. The purpose of this study was to determine the correlation between artery diameters measured on DSA and multidetector CTA. METHODS Two hundred forty artery diameters were measured in DSA and CTA from 46 patients who underwent both studies within 12 hours of each other. Axial cross section, maximum intensity projection, and volume-rendered images were measured and compared by linear correlation. Two independent readers measured CTA diameters to determine interobserver variability by linear correlation. Values also were categorized and compared by χ(2) and κ statistics. Analysis was repeated with unmeasurable arteries assigned a value of 0. RESULTS There were significant correlations between arterial diameters measured on DSA and those from CTA measured by any method (R(2) ranging from 0.45 to 0.76, P < .0001), although there was a tendency for the slope of this relationship to be less than 1, indicating underestimation of diameter of large and overestimation of diameter of small arteries with CTA. Computed tomographic angiography diameters also correlated significantly between the 2 reviewers with higher values often when unmeasureable arteries were assigned a value of 0 (κ = 0.23-0.55, P < .0001). CONCLUSION Arterial diameters measured on multidetector CTA correlate well with those determined from DSA and should permit use of CTA for quantitative study of cerebral vasospasm and other conditions requiring accurate measurement of arterial diameters. The limitation of CTA remains the inability to measure some arteries due to artifact.

Intracranial mucosa-associated lymphoid tissue (MALT) lymphoma.

Primary central nervous system lymphomas are a rare lymphoid tumor. A small proportion of these lymphomas are low-grade B-cell lymphoma of the mucosa-associated lymphoid tissue (MALT) subgroup. A primary MALT-lymphoma of the dura is very rare, with only a few reports. These low-grade tumors respond favorably to a combination of surgery and post-operative regional external beam radiotherapy. Differentiating these lesions from primary lymphomas or other dural-based lesions is therefore critical to determine clinical management and future prognosis. We report a 29-year-old patient with visual loss and dural-based MALT lymphoma and discuss the pertinent findings as well as the clinical management of patients with this unusual lesion.

Tumor Vaccines for Malignant Gliomas

Despite continued research efforts, glioblastoma multiforme (GBM) remains the deadliest brain tumor. Immunotherapy offers a novel way to treat this disease, the genetic signature of which is not completely elucidated. Additionally, these tumors are known to induce immunosuppression in the surrounding tumor microenvironment via an array of mechanisms, making effective treatment all the more difficult. The immunotherapeutic strategy of using tumor vaccines offers a way to harness the activity of the host immune system to potentially control tumor progression. GBM vaccines can react to a variety of tumor-specific antigens, which can be harvested from the patient’s unique pathological condition using selected immunotherapy techniques. This article reviews the rationale behind and development of GBM vaccines, the relevant clinical trials, and the challenges involved in this treatment strategy.