Enhanced immunosuppression by therapy-exposed glioblastoma multiforme tumor cells.

Glioblastoma multiforme (GBM) is a highly malignant brain tumor with an extremely short time to relapse following standard treatment. Since recurrent GBM is often resistant to subsequent radiotherapy and chemotherapy, immunotherapy has been proposed as an alternative treatment option. Although it is well established that GBM induces immune suppression, it is currently unclear what impact prior conventional therapy has on the ability of GBM cells to modulate the immune environment. In this study, we investigated the interaction between immune cells and glioma cells that had been exposed to chemotherapy or irradiation in vitro. We demonstrate that treated glioma cells are more immunosuppressive than untreated cells and form tumors at a faster rate in vivo in an animal model. Cultured supernatant from in vitro-treated primary human GBM cells were also shown to increase suppression, which was independent of accessory suppressor cells or T regulatory cell generation, and could act directly on CD4(+) and CD8(+) T cell proliferation. While a number of key immunosuppressive cytokines were overexpressed in the treated cells, including IL-10, IL-6 and GM-CSF, suppression could be alleviated in a number of treated GBM lines by inhibition of prostaglandin E2. These results reveal for the first time that conventional therapies can alter immunosuppressive pathways in GBM tumor cells, a finding with important implications for the combination of immunotherapy with standard treatment.

Dendritic cell vaccination combined with temozolomide retreatment: results of a phase I trial in patients with recurrent glioblastoma multiforme.

There is no standard treatment for recurrent glioblastoma multiforme (GBM). Retreatment with temozolomide (TMZ) is one treatment option. We reasoned this could be more effective if combined with a vaccine that preferentially targeted TMZ-resistant cells. To test the feasibility and safety of such an approach, a phase 1 trial was conducted in which patients with GBM tumors relapsing after standard chemoradiotherapy were retreated with TMZ in combination with a vaccine consisting of monocyte-derived dendritic cells (DC) pulsed with autologous tumor cells that had previously been exposed to TMZ in vivo in the course of primary treatment. Of 14 participants, nine patients completed the initial phase of priming vaccinations and two cycles of TMZ, one proved to have radionecrosis, one rapidly progressed, and in three the yield of DC vaccine was insufficient to proceed with treatment. Other than expected toxicities related to TMZ, there were no adverse events attributable to the combined treatment. Two patients had objective radiological responses. Six month progression-free survival was 22 %, similar to retreatment with TMZ alone. Anti-tumor immune responses were assessed in peripheral blood mononuclear cells using interferon-γ ELISpot, with two patients meeting criteria for a vaccine-induced immune response, one of whom remained disease-free for nearly three years. Another patient with an anti-tumor immune response at baseline that was sustained post-vaccination experienced a 12-month period of progression-free survival. In summary, the combined treatment was safe and well-tolerated but feasibility in the recurrent setting was marginal. Evidence of immune responses in a few patients broadly correlated with better clinical outcome.

Side population is not necessary or sufficient for a cancer stem cell phenotype in glioblastoma multiforme.

There is strong evidence for the existence of cancer stem cells (CSCs) in the aggressive brain tumor glioblastoma multiforme (GBM). These cells have stem-like self-renewal activity and increased tumor initiation capacity and are believed to be responsible for recurrence due to their resistance to therapy. Several techniques have been used to enrich for CSC, including growth in serum-free defined media to induce sphere formation, and isolation of a stem-like cell using exclusion of the fluorescent dye Hoechst 33342, the side population (SP). We show that sphere formation in GBM cell lines and primary GBM cells enriches for a CSC-like phenotype of increased self-renewal gene expression in vitro and increased tumor initiation in vivo. However, the SP was absent from all sphere cultures. Direct isolation of the SP from the GBM lines did not enrich for stem-like activity in vitro, and tumor-initiating activity was lower in sorted SP compared with non-SP and parental cells. Transient exposure to doxorubicin enhanced both CSC and SP frequency. However, doxorubicin treatment altered the cytometric profile and obscured the SP demonstrating the difficulty of identifying SP in cells under stress. Doxorubicin-exposed cells showed a transient increase in SP, but the doxorubicin-SP cells were still not enriched for a stem-like self-renewal phenotype. These data demonstrate that the GBM SP does not necessarily contribute to self-renewal or tumor initiation, key properties of a CSC, and we advise against using SP to enumerate or isolate CSC.

Rate and Predictors of Failure in the Conservative Management of Stable Thoracolumbar Burst Fractures: A Systematic Review and Meta-Analysis.

STUDY DESIGN: Systematic review. OBJECTIVES: Management of stable traumatic thoracolumbar burst fractures in neurologically-intact patients remains controversial. Conservative management fails in a subset of patients who require subsequent surgical fixation. The aim of this review is to (1) determine the rate of conservative management failure, and (2) analyze predictive factors at admission influencing conservative management failure. METHODS: A systematic review adhering to PRISMA guidelines was performed. Studies with data pertaining to traumatic thoracolumbar burst fractures without posterior osteoligamentous injury (e.g. AO Type A3/A4) and/or the rate and predictive factors of conservative management failure were included. Risk of bias appraisal was performed. Pooled analysis of rates of failure was performed with qualitative analysis of predictors of conservative management failure. RESULTS: 16 articles were included in this review (11 pertaining to rate of conservative management failure, 5 pertaining to predictive risk factors). Rate of failure of conservative management from a pooled analysis of 601 patients is 9.2% (95% CI: 4.5%-13.9%). Admission factors predictive of conservative management failure include age, greater initial kyphotic angle, greater initial interpedicular distance, smaller initial residual canal size, greater Load Sharing Classification (LSC) score and greater admission Visual Analog Scale (VAS) pain scores. CONCLUSION: A proportion (9.2%) of conservatively managed, neurologically-intact thoracolumbar burst fractures fail conservative management. Among other factors, age, kyphotic angle, residual canal area and interpedicular distance should be investigated in prospective studies to identify the subset of patients prone to failure of conservative management. Surgical management should be carefully considered in patients with the above risk factors.

Somatic Mosaic Mutation Gradient Detected in Trace Brain Tissue From Stereo-EEG Depth Electrodes.

BACKGROUND AND OBJECTIVES: Mosaic pathogenic variants restricted to brain are increasingly recognized as a cause of focal epilepsies. We aimed to identify a mosaic pathogenic variant and its anatomical gradient in brain DNA derived from trace tissue on explanted stereo-electroencephalography (SEEG) electrodes. MATERIAL AND METHODS: We studied a patient with non-lesional multifocal epilepsy undergoing pre-surgical evaluation with SEEG. Following explantation, electrodes were divided into 3 pools based on their brain location (right posterior quadrant, left posterior quadrant, hippocampus/temporal neocortex). Tissue from each pool was processed and DNA whole genome amplified prior to high-depth exome sequencing. Droplet digital PCR was performed to quantify mosaicism. Brain-specific GFAP protein assay enabled cell-of-origin analysis. RESULTS: We demonstrated a mosaic gradient for a novel pathogenic KCNT1 loss-of-function variant, c.530G>A, p.W177X, predicted to lead to nonsense-mediated decay. Strikingly, the mosaic gradient correlated strongly with the SEEG findings as the highest mutant allele fraction was in the right posterior quadrant, reflecting the most epileptogenic region on EEG studies. Elevated GFAP level indicated enrichment of brain-derived cells in SEEG cell suspension. CONCLUSIONS: This study demonstrates proof-of-concept that mosaic gradients of pathogenic variants can be established using trace tissue from explanted SEEG electrodes.

Effects of brain tissue oxygen (PbtO2) guided management on patient outcomes following severe traumatic brain injury: A systematic review and meta-analysis.

Monitoring and optimisation of brain tissue oxygen tension (PbtO2) has been associated with improved neurological outcome and survival in observational studies of severe traumatic brain injury (TBI). We carried out a systematic review of randomized controlled trials to determine if PbtO2-guided management is associated with differential neurological outcomes, survival, and adverse events. Searches were carried out to 10 February 2022 in Medline (OvidSP), 11 February in EMBASE (OvidSP) and 8 February in Cochrane library. Randomized controlled trials comparing PbtO2 and ICP-guided management to ICP-guided management alone were included. The primary outcome was survival with favourable neurological outcome at 6-months post injury. Data were extracted by two independent authors and GRADE certainty of evidence assessed. There was no difference in the proportion of patients with favourable neurological outcomes with PbtO2-guided management (relative risk [RR] 1.42, 95% CI 0.97 to 2.08; p = 0.07; I2 = 0%, very low certainty evidence) but PbtO2-guided management was associated with reduced mortality (RR 0.54, 95% CI 0.31 to 0.93; p = 0.03; I2 = 42%; very low certainty evidence) and ICP (mean difference (MD) - 4.62, 95% CI - 8.27 to - 0.98; p = 0.01; I2 = 63%; very low certainty evidence). There was no significant difference in the risk of adverse respiratory or cardiovascular events. PbtO2-guided management in addition to ICP-based care was not significantly associated with increased favourable neurological outcomes, but was associated with increased survival and reduced ICP, with no difference in respiratory or cardiovascular adverse events. However, based on GRADE criteria, the certainty of evidence provided by this meta-analysis was consistently very low. MESH: Brain Ischemia; Intensive Care; Glasgow Outcome Scale; Randomized Controlled Trial; Craniocerebral Trauma.

Blood Biomarkers of Glioma in Response Assessment Including Pseudoprogression and Other Treatment Effects: A Systematic Review.

Imaging-based monitoring of disease burden in glioma patients is frequently confounded by treatment effects. Circulating biomarkers could theoretically augment imaging-based response monitoring. This systematic review aimed to present and evaluate evidence for differential expression and diagnostic accuracy of circulating biomarkers with respect to outcomes of tumor response, progression, stable disease, and treatment effects (pseudoprogression, radionecrosis, pseudoresponse, and pseudolesions) in patients undergoing treatment for World Health Organization grades II-IV diffuse astrocytic and oligodendroglial tumors. MEDLINE, EMBASE, Web Of Science, and SCOPUS databases were searched until August 18, 2019, for observational or diagnostic studies on multiple circulating biomarker types: extracellular vesicles, circulating nucleic acids, circulating tumor cells, circulating proteins, and metabolites, angiogenesis related cells, immune cells, and other cell lines. Methodological quality of included studies was assessed using an adapted Quality Assessment of Diagnostic Accuracy Studies-2 tool, and level of evidence (IA-IVD) for individual biomarkers was evaluated using an adapted framework from the National Comprehensive Cancer Network guidelines on evaluating tumor marker utility. Of 13,202 unique records, 58 studies met the inclusion criteria. One hundred thirty-three distinct biomarkers were identified in a total of 1,853 patients across various treatment modalities. Fifteen markers for response, progression, or stable disease and five markers for pseudoprogression or radionecrosis reached level IB. No biomarkers reached level IA. Only five studies contained data for diagnostic accuracy measures. Overall methodological quality of included studies was low. While extensive data on biomarker dysregulation in varying response categories were reported, no biomarkers ready for clinical application were identified. Further assay refinement and evaluation in larger cohorts with diagnostic accuracy study designs are required. PROSPERO Registration: CRD42018110658.

Anterior versus posterior approach in the management of AO Type B1 & B2 traumatic thoracolumbar fractures: A level 1 trauma centre study.

The authors perform a retrospective trauma registry study to compare clinical, surgical and radiographical variables between anterior and posterior approaches in the management of AO Type B1 and B2 traumatic thoracolumbar fractures. Consecutive patients with surgically-managed AO Type B1 and B2 thoracolumbar fractures were included. Baseline demographics, surgical outcomes (including duration of surgery, postoperative morbidity etc.), neurological outcomes and radiographical outcomes (Cobb angle, Gardner angle) were compared between the anterior and posterior approaches. A total of 108 patients (anterior: n = 25, posterior: n = 83) were included. There were no significant between-group differences in baseline demographics and co-morbidities. Duration of surgery was longer in the anterior compared to posterior group (251 ± 91 min vs. 175 ± 69 min respectively, p < 0.00003). At six-months post-surgery, there was a trend towards improvement of at least one AIS grade in the posterior compared to the anterior group (85.7% vs. 33.3% respectively, p = 0.08). Postoperative complication profile showed no difference between approaches. The posterior approach resulted in better sagittal correction (Cobb angle; anterior: +1.05 ± 8.61 deg, posterior: -3.87 ± 9.88 deg, p = 0.03) and smaller loss of correction at 6-months post-surgery (Cobb angle; anterior: 8.36 ± 9.47 deg, posterior: 4.88 ± 6.62 deg, p = 0.048). This is the first study investigating surgical approach in flexion-distraction thoracolumbar fractures. Besides a shorter operative duration, the posterior approach seems to portend more favourable radiological correction at 6 months when compared to the anterior approach. Given the inherent selection bias of this study, definitive recommendations regarding the anterior versus posterior approach cannot be made. Further well-defined, prospective studies are necessary.

Prophylactic postoperative measures to minimize surgical site infections in spine surgery: systematic review and evidence summary.

BACKGROUND CONTEXT: There are three phases in prophylaxis of surgical site infections (SSI): preoperative, intraoperative and postoperative. There is lack of consensus and paucity of evidence with SSI prophylaxis in the postoperative period. PURPOSE: To systematically evaluate the literature, and provide evidence-based summaries on postoperative measures for SSI prophylaxis in spine surgery. STUDY DESIGN: Systematic review, meta-analysis, evidence synthesis. METHODS: A systematic review conforming to PRIMSA guidelines was performed utilizing PubMed (MEDLINE), EMBASE, and the Cochrane Database from inception to January 2019. The GRADE approach was used for quality appraisal and synthesis of evidence. Six postoperative care domains with associated key questions were identified. Included studies were extracted into evidence tables, data synthesized quantitatively and qualitatively, and evidence appraised per GRADE approach. RESULTS: Forty-one studies (nine RCT, 32 cohort studies) were included. In the setting of preincisional antimicrobial prophylaxis (AMP) administration, use of postoperative AMP for SSI reduction has not been found to reduce rate of SSI in lumbosacral spine surgery. Prolonged administration of AMP for more than 48 hours postoperatively does not seem to reduce the rate of SSI in decompression-only or lumbar spine fusion surgery. Utilization of wound drainage systems in lumbosacral spine and adolescent idiopathic scoliosis corrective surgery does not seem to alter the overall rate of SSI in spine surgery. Concomitant administration of AMP in the presence of a wound drain does not seem to reduce the overall rate of SSI, deep SSI, or superficial SSI in thoracolumbar fusion performed for degenerative and deformity spine pathologies, and in adolescent idiopathic scoliosis corrective surgery. Enhanced-recovery after surgery clinical pathways and infection-specific protocols do not seem to reduce rate of SSI in spine surgery. Insufficient evidence exists for other types of spine surgery not mentioned above, and also for non-AMP pharmacological measures, dressing type and duration, suture and staple management, and postoperative nutrition for SSI prophylaxis in spine surgery. CONCLUSIONS: Despite the postoperative period being key in SSI prophylaxis, the literature is sparse and without consensus on optimum postoperative care for SSI prevention in spine surgery. The current best evidence is presented with its limitations. High quality studies addressing high risk cohorts such as the elderly, obese, and diabetic populations, and for traumatic and oncological indications are urgently required.

Patients with ankylosing spondylitis suffering from AO Type B3 traumatic thoracolumbar fractures are associated with increased frailty and morbidity when compared with patients with diffuse idiopathic skeletal hyperostosis.

BACKGROUND: AO Type B3 hyperextension thoracolumbar fractures are the commonest fracture subtype in ankylosing spinal disorders. Although often considered together in spinal fractures, ankylosing spondylitis (AS) and diffuse idiopathic skeletal hyperostosis (DISH) are distinct spondyloarthropathies with different pathophysiology. Few studies have compared the two entities in the setting of traumatic thoracolumbar fractures. The authors compare demographic metrics, injury profile, clinical and radiographical outcomes between patients with AS and DISH in patients suffering from AO Type B3 traumatic thoracolumbar fractures. METHODS: From January 2008 to December 2018, a retrospective analysis of consecutive surgically-managed patients with AO Type B3 fractures was performed. Demographic metrics, co-morbidity [Charlson-comorbidity index, modified frailty index (mFI), etc.], injury profile (level of injury, mechanism of injury, etc.), clinical (postoperative complication, etc.) and radiographical variables were collected. Differences between patients with AS and DISH were compared. RESULTS: Fourteen patients were identified. All patients had AS (n=6) or DISH (n=8). The mean age was 72.8±10.2 years and 78.6% of patients were neurologically intact at presentation. Medical and/or surgical complications occurred in 10 of 14 (71.4%) patients. As compared to patients with DISH, patients with AS were more likely to have low falls as the injury mechanism [odds ratio (OR): 35.0, P=0.026], have higher mFI (OR: 30.6, P=0.015), and experience a higher number of postoperative complications per patient (AS: 1.8/patient vs. DISH: 0.5/patient, P=0.024). CONCLUSIONS: In the setting of AO Type B3 fractures, patients with AS are more frail and have higher in-hospital morbidity compared to patients with DISH. Despite both pathologies being ankylosing in nature, further studies are required to fully understand the clinical differences between the two entities to enable clinicians to apply a more targeted and nuanced approach in managing fractures in ankylosing spinal disorders.

Prognosis of Acute Subdural Hematoma in the Elderly: A Systematic Review.

Acute subdural hematoma (aSDH) is among the most common injury types encountered by neurosurgeons, and carries a poor prognosis, particularly in the elderly. As the incidence of aSDH in the elderly population rises, identifying those patients who may benefit from operative intervention is crucial. This systematic review aimed to identify data on prognostic factors or indices, such as the modified frailty index, that may help predict outcome, and hence guide management. A comprehensive search of online databases was conducted by two independent authors, and data on prognostic factors and outcomes were extracted. The quality of the evidence was evaluated using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) criteria. Of 769 studies identified in the initial search, 7 satisfied inclusion and exclusion criteria. Mortality and morbidity varied considerably among studies. Initial Glasgow Coma Scale (GCS) of 3-8 was the most consistently reported negative prognostic feature. Several studies evaluated the impact of medical comorbidities and premorbid frailty, but were limited by small sample size. A previous history of pneumonia was shown to increase the risk of Glasgow Outcome Score (GOS) 1-3 (odds ratio [OR] 6.4 [95% CI 1.6-25.2], p = 0.04) in a single study, which also reported a greater increase in GOS at 3 months in those with fewer than five comorbidities (56% vs. 19%, p < 0.01). There are limited data describing prognostic factors or the use of frailty indices within the specific group of elderly patients with aSDH. Prospective research is needed to evaluate the utility of accurate and validated assessments of frailty to enhance the neurosurgeon's ability to appropriately manage this complex and expanding patient group.

Bing-Neel syndrome - Bilateral cavernous sinus lymphoma causing visual failure.

We report the case of a 68-year-old male with right eye vision loss secondary to a compressive optic neuropathy from Waldenstrom macroglobulinaemia relapse in both cavernous sinuses. Central nervous system involvement is extremely uncommon in lymphoplasmacytic lymphoma. Known as Bing-Neel syndrome, this has not been previously reported to present simultaneously in bilateral cavernous sinuses. We discuss the pathophysiology, diagnostic and neuroradiological features of Bing-Neel syndrome. In this case, there was marked clinical and radiological response to chemotherapy. As outcomes following treatment for Waldenstrom macroglobulinaemia improve, greater awareness of its less common manifestations becomes important. Neurosurgical intervention may be indicated to obtain histological diagnosis or decompress critical structures.

Obesity in Neurosurgery: A Narrative Review of the Literature.

Obesity is an important consideration in neurosurgical practice. Of Australian adults, 28.3% are obese and it is estimated that more than two thirds of Australia's population will be overweight or obese by 2025. This review of the effects of obesity on neurosurgical procedures shows that, in patients undergoing spinal surgery, an increased body mass index is a significant risk factor for surgical site infection, venous thromboembolism, major medical complications, prolonged length of surgery, and increased financial cost. Although outcome scores and levels of patient satisfaction are generally lower after spinal surgery in obese patients, obesity is not a barrier to deriving benefit from surgery and, when the natural history of conservative management is taken into account, the long-term benefits of surgery may be equivalent or even greater in obese patients than in nonobese patients. In cranial surgery, the impact of obesity on outcome and complication rates is generally lower. Specific exceptions are higher rates of distal catheter migration after shunt surgery and cerebrospinal fluid leak after posterior fossa surgery. Minimally invasive approaches show promise in mitigating some of the adverse effects of obesity in patients undergoing spine surgery but further studies are needed to develop strategies to reduce obesity-related surgical complications.

Blocking CTLA-4 while priming with a whole cell vaccine reshapes the oligoclonal T cell infiltrate and eradicates tumors in an orthotopic glioma model.

Vaccine-mediated cancer treatment is unlikely to induce long-term survival unless suppressive mechanisms are overcome. Given the success of antibody-mediated immune checkpoint blockade in relieving regulation of endogenous anti-tumor T cell responses in tumor-burdened hosts, we investigated whether checkpoint blockade could improve the efficacy of responses induced with a whole tumor-cell vaccine. We show that administration of a single dose of blocking antibody was sufficient to significantly enhance antitumor activity of the vaccine, inducing complete radiological regression of established intracranial tumors. The antibody or vaccine alone were ineffective in this setting. The antibody had to be administered before, or close to, vaccine administration, suggesting CTLA-4 blockade had an impact on early priming events. The combined treatment resulted in enhanced trapping of leukocytes in the lymphoid tissues, including T cells that had undergone significant proliferation. There were no obvious changes in the stimulatory function of antigen-presenting cells or the number and function of regulatory T cells, suggesting T cells were the targets of the checkpoint blockade. While tumors regressing under combined treatment were highly infiltrated with a variety of leukocytes, tumor eradication was dependent on CD4+ T cells. Analysis of the TCR repertoire showed that the addition of anti-CTLA-4 at priming reshaped the repertoire of tumor infiltrating T cells. In particular, the oligoclonal populations became greater in magnitude and more diverse in specificity. Using anti-CTLA-4 in a restricted way to promote the priming phase of an anti-cancer vaccine may offer a useful way of harnessing clinical benefit from this powerful agent.

Exploiting invariant NKT cells to promote T-cell responses to cancer vaccines.

Invariant natural killer T (iNKT) cells have the capacity to amplify adaptive immune responses by licensing antigen-presenting cells. A simple vaccine consisting of whole tumor cells pulsed with an iNKT-cell agonist efficiently delivers antigens plus adjuvants to endogenous dendritic cells and has potential for clinical applications.

Vaccination with irradiated tumor cells pulsed with an adjuvant that stimulates NKT cells is an effective treatment for glioma.

PURPOSE: The prognosis for patients with glioblastoma multiforme (GBM) remains extremely poor despite recent treatment advances. There is an urgent need to develop novel therapies for this disease. EXPERIMENTAL DESIGN: We used the implantable GL261 murine glioma model to investigate the therapeutic potential of a vaccine consisting of intravenous injection of irradiated whole tumor cells pulsed with the immuno-adjuvant α-galactosylceramide (α-GalCer). RESULTS: Vaccine treatment alone was highly effective in a prophylactic setting. In a more stringent therapeutic setting, administration of one dose of vaccine combined with depletion of regulatory T cells (Treg) resulted in 43% long-term survival and the disappearance of mass lesions detected by MRI. Mechanistically, the α-GalCer component was shown to act by stimulating "invariant" natural killer-like T cells (iNKT cells) in a CD1d-restricted manner, which in turn supported the development of a CD4(+) T-cell-mediated adaptive immune response. Pulsing α-GalCer onto tumor cells avoided the profound iNKT cell anergy induced by free α-GalCer. To investigate the potential for clinical application of this vaccine, the number and function of iNKT cells was assessed in patients with GBM and shown to be similar to age-matched healthy volunteers. Furthermore, irradiated GBM tumor cells pulsed with α-GalCer were able to stimulate iNKT cells and augment a T-cell response in vitro. CONCLUSIONS: Injection of irradiated tumor cells loaded with α-GalCer is a simple procedure that could provide effective immunotherapy for patients with high-grade glioma.