Pathogens and glioma: a history of unexpected discoveries ushering in novel therapy

In the late 19th century, Dr. William B. Coley introduced the theory that infections may aid in the treatment of malignancy. With the creation of Coley’s toxin, reports of remission during viral illnesses for systemic malignancies soon emerged. A few decades after this initial discovery, Austrian physicians performed intravascular injections of Clostridium to induce oncolysis in patients with glioblastoma. Since then, suggestions between improved survival and infectious processes have been reported in several patients with glioma, which ultimately marshaled the infamous use of intracerebral Enterobacter. These early observations of tumor regression and concomitant infection piloted a burgeoning field focusing on the use of pathogens in molecular oncology.

Contemporaneous biopsy and laser interstitial thermal therapy for two treatment-refractory brain metastases

Recurrent treatment-refractory brain metastases can be treated with modern adjuvant therapies such as laser interstitial thermal therapy (LITT). Since previously radiated lesions may be indolent (treatment effect) or recurrent tumor, histological confirmation may be helpful. The authors present the utility of contemporaneous biopsy and LITT using intraoperative O-arm navigation in a patient who presented with multiple refractory metastases. The authors demonstrate the utility of O-arm navigation to confirm intraoperative biopsy and LITT placement. Concurrent stereotactic biopsy and LITT may be a safe and efficacious method for both the diagnosis and treatment of deep lesions that are unamenable to standard adjuvant treatment modalities.

The video can be found here: https://youtu.be/SUY-qiahMyo.

Value of diffusion kurtosis imaging in assessing low-grade gliomas

BACKGROUND

Diffusion kurtosis imaging (DKI) measures have been shown to provide increased sensitivity relative to diffusion tensor imaging (DTI) in detecting pathologies.

PURPOSE

To compare the sensitivity of DKI-derived kurtosis and diffusion maps for assessment of low-grade gliomas (LGG).

STUDY TYPE

Prospective study.

POPULATION

In all, 19 LGG patients and 26 healthy control subjects were recruited.

FIELD STRENGTH/SEQUENCE

Echo-planar-imaging diffusion-weighted MR images (b-values = 0, 1000, and 2000 with 30 diffusion gradient directions) were acquired on a 3T scanner.

ASSESSMENT

Maps for mean, axial, and radial diffusivity (MD, AD, and RD) and kurtosis (MK, AK, and RK), and fractional anisotropy (FA) were evaluated in the tumor, perilesional white matter, and contralateral normal-appearing white matter regions.

STATISTICAL TESTING

General linear models (GLM), Cohen's d for effect size estimates, false discovery rate (FDR) for multiple corrections, Cochran Q-test.

RESULTS

Pairwise differences were observed for all diffusion and kurtosis measures between the studied regions (FDR P < 0.001), except an FA map that failed to show significant differences between the lesion and perilesional white matter (FDR P = 0.373). Effect size analysis showed that kurtosis metrics were found to be 18.8% (RK, P = 0.144) to 29.1% (AK, P < 0.05) more sensitive in discriminating perilesional regions from the lesion than corresponding diffusion metrics, whereas AK provided a 25.0% (P < 0.05) increase in sensitivity in discriminating perilesional and contralateral white matter. RK was found to be the most sensitive to contralateral white matter differences between low-grade gliomas and controls, with MK and RK providing a significantly greater sensitivity of 587.2% (P < 0.001) and 320.7% (P < 0.001) than MD and RD, respectively.

DATA CONCLUSION

Kurtosis maps showed increased sensitivity, as compared to counterpart diffusion maps, for evaluation of microstructural changes in gliomas with a 3-6-fold increment in assessing changes in contralateral white matter.

LEVEL OF EVIDENCE

2 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2018;48:1551-1558.

Serum long noncoding RNA HOTAIR as a novel diagnostic and prognostic biomarker in glioblastoma multiforme

Glioblastoma multiforme (GBM) is the most common and aggressive malignant adult primary brain tumor. Despite surgical resection followed by radiotherapy and chemotherapy, the median survival rate is approximately 14 months. Although experimental therapies are in clinical trials for GBM, there is an urgent need for a peripheral GBM biomarker for measuring treatment response. As we have previously demonstrated that the long noncoding RNA HOX Transcript Antisense Intergenic RNA, or HOTAIR, is dysregulated in GBM and required for GBM cell proliferation, we hypothesized that HOTAIR expression may be utilized as a peripheral biomarker for GBM. HOTAIR expression was measured in serum from 43 GBM and 40 controls using quantitative real-time PCR (qRT-PCR). The PCR products were subsequently subcloned into pCR™4-TOPO®TA vectors for DNA sequencing. A ROC curve was also generated to examine HOTAIR's prognostic value. The amount of HOTAIR in serum exosomes and exosome-depleted supernatant was calculated by qRT-PCR. The relative HOTAIR expression was also investigated in 15 pairs of GBM serum and tumors. We detected HOTAIR in serum from GBM patients. HOTAIR levels in serum samples from GBM patients was significantly higher than in the corresponding controls (P < 0.0001). The area under the ROC curve distinguishing GBM patients from controls was 0.913 (95% CI: 0.845-0.982, P < 0.0001), with 86.1% sensitivity and 87.5% specificity at the cut-off value of 10.8. HOTAIR expression was significantly correlated with high grade brain tumors. In addition, Pearson correlation analysis indicated a medium correlation of serum HOTAIR levels and the corresponding tumor HOTAIR levels (r = 0.734, P < 0.01). We confirmed via sequencing that the amplified HOTAIR from serum contained the HOTAIR sequence and maps to the known HOTAIR locus at 12q13. The serum-derived exosomes contain HOTAIR and the purified exosomes were validated by western blot and nanoparticle tracking analysis. Importantly, our results demonstrate that serum HOTAIR can be used as a novel prognostic and diagnostic biomarker for GBM.

Radiation-induced meningiomas: A case-control study at single center institution

BACKGROUND

Our understanding of radiation induced meningiomas (RIM) is limited. It has been suggested that RIM harbor more aggressive cellular pathology and must be observed vigilantly. However, the actual recurrence rates of RIM compared to the sporadic meningiomas has yet to be defined.

OBJECTIVE

We employ a single center case-control study to retrospectively assess recurrence rates between RIM (n = 12) and sporadic meningiomas (n = 118).

METHODS

The criteria for the RIM group included the following: 1) History of intracranial clinical-dose radiation 2) Initial pathology other than meningioma, 3) Radiation administered greater than 5 years prior to meningioma onset. Recurrence rates, extent of resection and outcomes were analyzed.

RESULTS

There was a significant difference in recurrence rates between the RIM group and sporadic meningioma: 50% vs. 5% respectively, p = 0.004. There was no significant difference in race, preoperative tumor volume, extent of resection, Ki67, or age between the two groups. Multivariate analysis demonstrated that size (OR 0.95 95%CI (0.92-0.99)), extent of resection (OR 1.08 95%CI (1.01-1.14)), WHO grade (OR 160.24 95% CI (6.32-74509)) and history of previous radiation (OR 1.28 95%CI (1.01-1.62)) were independent risk factors for recurrence. RIM patients had significantly higher proportion of atypical or malignant histology compared to sporadic patients (p < 0.0001).

CONCLUSION

RIM patients may have a higher predisposition for tumor recurrence than patients with sporadic RIM. The use of Ki67 indices may help identify patients with a higher risk of tumor recurrence. Prospective studies focusing on newly diagnosed patients with RIM may help identify an optimal surveillance and treatment plan.

Novel Immunotherapeutics for the Treatment of Glioblastoma: The Last Decade of Research

Despite surgical resection and adjuvant chemoradiation, survival for glioblastoma remains poor. Because of the dismal prognosis, attention has shifted to alternative adjuvant treatment modalities. Although traditionally limited to systemic malignancies (melanoma, lung and colon cancer), the field of immunotherapy has recently identified glioblastoma as a potential target for new treatments. Anti-tumor vaccines (dendritic cell/heat shock), checkpoint inhibitors, chimeric T-cell receptors, and virotherapy all have been preliminarily trialed in glioblastoma patients with reasonable success and safety. Although there are limitations due to autoimmune reactions and immune escape, immunotherapeutics hold much promise in the future treatment paradigms for malignant glioma.

Postoperative Seizure Rate After Transcortical Resection of Subcortical Brain Tumors and Colloid Cysts: A Single Surgeon's Experience

When deciding on a surgical route to reach subcortical brain tumors and colloid cysts, many surgeons advocate the use of transcallosal, transsulcal, or skull base approaches over transcortical approaches due to a high reported incidence of postoperative seizures. We have retrospectively analyzed all patients operated upon by a senior neurosurgeon (Ricardo J. Komotar) who undertook transcortical approaches for the resection of subcortical brain tumors and colloid cysts. We have also performed a comprehensive review of the literature to estimate postoperative seizure risk after transcortical approaches for the resection of deep tumors and colloid cysts. Of 27 patients who underwent transcortical approaches for the resection of subcortical brain tumors and colloid cysts, zero had postoperative seizures. A comprehensive review of the literature shows an 8.3% postoperative risk of seizures after the transcortical approach. Our institution has never experienced a postoperative seizure following the transcortical approach for the resection of deep tumors and colloid cysts. For this reason, we advocate selecting a surgical approach that obtains adequate lesion exposure and minimizes the violation and retraction of eloquent cortex, venous structures, and white matter tracts, rather than on presumed postoperative seizure risk.

Laser Ablation of Newly Diagnosed Malignant Gliomas: a Meta-Analysis

BACKGROUND

Magnetic resonance-guided laser-interstitial thermotherapy (MR-LITT) is a minimally invasive technique that shows promise in neuro-oncology because of its superiority in delivering precise minimally invasive thermal energy with minimal collateral damage.

OBJECTIVE

In this analysis, we investigate initial data on the use of MR-LITT in the treatment of newly diagnosed high-grade gliomas.

METHODS

With the use of the PubMed, OVID, and Google-scholar database systems, a comprehensive search of the English literature was performed. Eighty-five articles were identified plus 1 that is pending publication. Four articles were accounted for in this review, including 25 patients with newly diagnosed high-grade gliomas who underwent MR-LITT treatment. We evaluated safety, progression-free survival, and overall survival.

RESULTS

Twenty-five patients with a mean age of 53.8 years underwent LITT treatments. On average, 82.9% of the pretreatment lesion volume was ablated. The average tumor volume treated was 16.5 cm. The mean follow-up time was 7.6 months. Median overall survival was found to be 14.2 months (range 0.1-23 months). The median progression-free survival was 5.1 months (range 2.4-23 months); however, these data are limited by the relatively short follow-up of the patients reviewed and small sample size of only 25 patients. There was 1 (3.4%) major perioperative complication, which was a central nervous system infection.

CONCLUSION

MR-LITT is a promising technology for the treatment of small, yet difficult-to-treat newly diagnosed high-grade gliomas. This study demonstrates that MR-LITT is safe, and future randomized studies are needed to evaluate its role as a treatment adjunct for newly diagnosed high-grade gliomas.

ABBREVIATIONS

BBB, blood-brain barrierHGG, high-grade gliomaLITT, laser-interstitial thermal therapyWHO, World Health Organization.

Neurosarcoidosis presenting as an incidental solitary cranial ring-enhancing lesion

Isolated neurosarcoidosis without prior systemic symptoms is extremely rare, occurring in approximately 2% of patients with neurosarcoidosis. Due to its rarity, mistakes in diagnosis and treatment occur commonly. We present a case of a 47-year-old female who was found to have an incidentally discovered solitary intracranial lesion that mimicked a high-grade neoplasm, but was later confirmed to be neurosarcoidosis. Incidental solitary neurosarcoid granulomas are difficult to diagnose due to its nonspecific clinical and imaging presentations. Early diagnosis by biopsy in these rare incidental cases remains paramount for adequate treatment.

Autologous Heat Shock Protein Peptide Vaccination for Newly Diagnosed Glioblastoma: Impact of Peripheral PD-L1 Expression on Response to Therapy

Purpose: Standard therapy for newly diagnosed glioblastoma (GBM) is surgical resection, followed by concurrent radiotherapy and temozolomide chemotherapy. In this phase II clinical trial, the addition of an autologous heat-shock protein vaccine to standard therapy was evaluated. Tumor-induced immunosuppression, mediated by expression of PD-L1 on tumor and circulating immune cells, may impact the efficacy of vaccination. Expression of PD-L1 on peripheral myeloid cells was evaluated for the first time as a predictor of survival.Experimental Design: In this single arm, phase II study, adult patients with GBM underwent surgical resection followed by standard radiation and chemotherapy. Autologous vaccine (Prophage) was generated from resected tumors and delivered in weekly vaccinations after completion of radiotherapy. The primary endpoint was overall survival.Results: Forty-six patients received the vaccine with a median overall survival of 23.8 months [95% confidence interval (CI), 19.8-30.2]. Median overall survival for patients with high PD-L1 expression on myeloid cells was 18.0 months (95% CI, 10.0-23.3) as compared with 44.7 months (95% CI, incalculable) for patients with low PD-L1 expression (hazard ratio 3.3; 95% CI, 1.4-8.6; P = 0.007). A multivariate proportional hazards model revealed MGMT methylation, Karnofsky performance status, and PD-L1 expression as the primary independent predictors of survival.Conclusions: Vaccination with autologous tumor-derived heat shock proteins may improve survival for GBM patients when combined with standard therapy and warrants further study. Systemic immunosuppression mediated by peripheral myeloid expression of PD-L1 is a recently identified factor that may significantly impact vaccine efficacy. Clin Cancer Res; 23(14); 3575-84. ©2017 AACR.

Abstract 5864: Targeting brain cancer stem cells by potentiating radiation-induced ER stress

Background. Glioblastoma (GBM) is one of the most malignant brain tumors occurring in both children and adults. Despite an aggressive treatment regimen consisting of surgical resection, radiation therapy and chemotherapy the five-year survival rate is less than 5%. This poor outcome has been attributed to the existence of therapy-resistant GBM stem-like cells (GSCs), which are believed to be responsible for tumor recurrence and patient relapse. Understanding the resistance mechanisms employed by brain tumor stem cells and developing novel methods to target these cells is necessary for prolonged patient survival. Recent evidence suggests that the endoplasmic reticulum stress response pathway may mediate therapeutic resistance in cancer. Here we sought to examine the ER stress response pathway of GSCs in response to ionizing radiation and to increase the extent of ER stress in an effort to promote cell death using the glycolytic inhibitor, 2-deoxy glucose (2-DG).

Methods. GSC lines were derived from resected tumor sections. GSCs were irradiated using the Rad Source 2000 Series Biological Irradiator. Transmission Electron Microscopy (TEM) was used to investigate the ultra-structural alterations of GSCs following exposure to 8 Gy radiation. Viability was determined using trypan blue exclusion, MTS and LDH assays. Cell signaling pathways were investigated by western blot analysis.

Results. Consistent with previous findings, minimal cell death was observed in GSCs exposed to 2-20 Gy radiation. TEM analysis revealed that exposure to 8 Gy significantly increased ER lumen dilation, suggestive of ER stress. Western blot analysis indicated an increase in ER stress markers GRP78, GRP94 and CHOP, confirming that radiation induces ER stress in GSCs. Treatment with 2-DG induced an increase in ER lumen diameter and ER stress markers. Combined 2-DG (0.5mM and 2mM) and radiotherapy (8 Gy) significantly increased ER luminal diameter and ER stress marker expression over radiation or 2-DG alone. In addition, combined radiation and 2-DG (0.1-2mM) significantly reduced GSC viability compared to radiation or 2-DG alone.

Conclusion. The ER stress response pathway is an adaptive mechanism and thought to mediate therapeutic resistance. Here we demonstrate that radiation induces ER stress response pathway including ER lumen dilation and an increase in molecular chaperone expression in GSCs. Potentiating ER stress can switch the pathway from one of adaptation to cell death. 2-DG increased radiation-induced ER stress and promoted cell death. Our data suggests that targeting this adaptive response could increase the efficacy of radiotherapy and prolong patient survival

Note: This abstract was not presented at the meeting.

Citation Format: Regina M. Graham, Sumedh S. Shah, Alexis J. Musick, Winston Walters, Ricardo J. Komotar, Jeffery S. Prince, Steven Vanni. Targeting brain cancer stem cells by potentiating radiation-induced ER stress [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5864. doi:10.1158/1538-7445.AM2017-5864

Curcumin decreases malignant characteristics of glioblastoma stem cells via induction of reactive oxygen species

Background

Glioblastoma Multiforme (GBM) is the most common and lethal form of primary brain tumor in adults. Following standard treatment of surgery, radiation and chemotherapy, patients are expected to survive 12–14 months. Theorized cause of disease recurrence in these patients is tumor cell repopulation through the proliferation of treatment-resistant cancer stem cells. Current research has revealed curcumin, the principal ingredient in turmeric, can modulate multiple signaling pathways important for cancer stem cell self-renewal and survival.

Methods

Following resection, tumor specimens were dissociated and glioblastoma stem cells (GSCs) were propagated in neurosphere media and characterized via immunocytochemistry. Cell viability was determined with MTS assay. GSC proliferation, sphere forming and colony forming assays were conducted through standard counting methods. Reactive oxygen species (ROS) production was examined using the fluorescent molecular probe CM-H2DCFA. Effects on cell signaling pathways were elucidated by western blot.

Results

We evaluate the effects of curcumin on patient-derived GSC lines. We demonstrate a curcumin-induced dose-dependent decrease in GSC viability with an approximate IC₅₀ of 25 μM. Treatment with sub-toxic levels (2.5 μM) of curcumin significantly decreased GSC proliferation, sphere forming ability and colony forming potential. Curcumin induced ROS, promoted MAPK pathway activation, downregulated STAT3 activity and IAP family members. Inhibition of ROS with the antioxidant N-acetylcysteine reversed these effects indicating a ROS dependent mechanism.

Conclusions

Discoveries made in this investigation may lead to a non-toxic intervention designed to prevent recurrence in glioblastoma by targeting glioblastoma stem cells.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-017-3058-2) contains supplementary material, which is available to authorized users.