Andrej Pala

Epidermal to Mesenchymal Transition and Failure of EGFR-Targeted Therapy in Glioblastoma

Glioblastoma multiforme (GBM), the most common primary brain tumor in adults, is almost never curable with the current standard treatment consisting of surgical resection, irradiation and temozolomide. The prognosis remains poor despite undisputable advances in the understanding of this tumor’s molecular biology and pathophysiology, which unfortunately has so far failed to translate into a meaningful clinical benefit. Dysregulation and a resulting prominent pathophysiological role of the epidermal growth factor receptor (EGFR) have been identified in several different malignant tumor entities, GBM among them. The EGFR is overexpressed in about 40% of GBM cases, and half of these coexpress a mutant, constitutively activated subtype, EGFRvIII. Unfortunately, recent trials studying with therapeutic approaches targeted against the EGFR and EGFRvIII have failed to meet expectations, with only a minority of patients responding despite evidence of good in vitro and rodent model activity. Having potentially high relevance within this context, epithelial to mesenchymal transition (EMT) is a phenomenon associated with early stages of carcinogenesis, cancer invasion and recurrence. During EMT, epithelial cells lose many of their epithelial characteristics, prominently E-cadherin expression, and acquire properties that are typical for mesenchymal cells such as the expression of vimentin. Epithelial to mesenchymal transition has been specifically demonstrated in GBM. In this review, we summarize the evidence that EMT may precipitate GBM resistance to EGFR-targeted therapy, and may thus be among the principal factors contributing to the clinical failure of targeted therapy against EGFR and EGFRvIII.

Immune phenotypes predict survival in patients with glioblastoma multiforme

BackgroundGlioblastoma multiforme (GBM), a common primary malignant brain tumor, rarely disseminates beyond the central nervous system and has a very bad prognosis. The current study aimed at the analysis of immunological control in individual patients with GBM.MethodsImmune phenotypes and plasma biomarkers of GBM patients were determined at the time of diagnosis using flow cytometry and ELISA, respectively.ResultsUsing descriptive statistics, we found that immune anomalies were distinct in individual patients. Defined marker profiles proved highly relevant for survival. A remarkable relation between activated NK cells and improved survival in GBM patients was in contrast to increased CD39 and IL-10 in patients with a detrimental course and very short survival. Recursive partitioning analysis (RPA) and Cox proportional hazards models substantiated the relevance of absolute numbers of CD8 cells and low numbers of CD39 cells for better survival.ConclusionsDefined alterations of the immune system may guide the course of disease in patients with GBM and may be prognostically valuable for longitudinal studies or can be applied for immune intervention.

Head injury in children: has a change in circumstances caused an increase in treatment numbers?

The number of hospitalizations for head injuries in children is rising. The exact causes remain unclear. We analyzed data of children aged between 0 and 18 years who sustained a head injury between 2010 and 2011. The analysis focused on data related to demographics, trauma mechanism, clinical course, results of imaging scans, concomitant injuries, and outcome. A total of 794 inpatient cases of head injury were treated. The leading mechanism of injury was a fall (at home) primarily at the age of 1 to 4 years (46.5%), with the majority of the children sustaining a mild brain injury (764, 96.2%). Neurosurgery was performed in 21 (2.64%) cases; average hospital stay was 2.9 days (range: 0-68 days). This study is not able to confirm that children are increasingly being brought to the hospital by their parents because of new trauma mechanisms or parents’ uncertainty, nor can we confirm that the number of nonaccidental injuries is rising.

Histopathological Insights on Imaging Results of Intraoperative Magnetic Resonance Imaging, 5-Aminolevulinic Acid, and Intraoperative Ultrasound in Glioblastoma Surgery

BACKGROUND For appropriate use of available intraoperative imaging techniques in glioblastoma (GB) surgery, it is crucial to know the potential of the respective techniques in tumor detection. OBJECTIVE To assess histopathological basis of imaging results of intraoperative magnetic resonance imaging (iMRI), 5-aminolevulinic acid (5-ALA), and linear array intraoperative ultrasound (lioUS). METHODS We prospectively compared the imaging findings of iMRI, 5-ALA, and lioUS at 99 intraoperative biopsy sites in 33 GB patients during resection control. Histological classification of specimens, tumor load, presence of necrosis, presence of vascular malformations, and O6-methylguanin-DNA methyltransferase (MGMT) promoter state was correlated with imaging findings. RESULTS Solid tumor was found in 57%, infiltration zone in 42%, and no tumor in 1% of specimens. However, imaging was negative in iMRI in 49%, using 5-ALA in 17%, and in lioUS in 21%. In positive imaging results, share of solid tumor was highest in 5-ALA (65%) followed by lioUS (60%) and lowest in iMRI (55%). In comparison to 5-ALA, iMRI had a high share of solid tumor in specimens when showing intermediate results. Sensitivity for invasive tumor was higher in 5-ALA (84%) and lioUS (80%) than in iMRI (50%). We found a significant correlation of 5-ALA with classification of specimen, presence of necrosis, and microproliferations. Methylated MGMT promoter correlated with positive findings in 5-ALA. lioUS and iMRI showed no correlations with histopathological findings. CONCLUSION All of the assessed established imaging techniques detect infiltrating tumor only to a certain extent. Only 5-ALA showed a significant correlation with histopathological findings. Interestingly, tumor remnants in an MGMT-methylated tumor are more likely to be visible using 5-ALA as in unmethylated tumors.

Epithelial to Mesenchymal Transition and Progression of Glioblastoma

Glioblastoma multiforme (GBM) is the most common primary brain tumor among adults. Rapid tumor progression and diffuse invasion of brain tissue restrict the therapeutic options and result in poor prognosis despite advances in the understanding of this tumor’s molecular biology and pathophysiology [1-4]. Current standard therapy consists of a combination of tumor resection, irradiation and temozolomide. Advances in the field of molecular biology have led to the development of targeted therapy, and the epidermal growth factor receptor (EGFR) has been introduced as one potential therapeutic target [5]. Although pre-clinical studies have shown promising effects, clinical applications yielded no significant benefit in comparison with standard therapy. This fact encouraged extensive investigations studying the molecular mechanisms underlying GBM resistance to EGFR-targeted therapy. Epithelial to mesenchymal transition (EMT) is considered an important factor contributing to resistance towards this therapy by diminishing the molecular target [1-6].

Contemporary use of intraoperative imaging in glioma surgery: A survey among EANS members

OBJECTIVES In glioma surgery, intraoperative imaging is regarded highly valuable to improve extent of resection. Current distribution of intraoperative imaging techniques is largely unknown. Further, controversy exists which method might be most beneficial. PATIENTS AND METHODS We performed a web-based survey among members of the European Association of Neurological Surgeons(EANS) from April to May 2017. Our questionnaire included intraoperative MRI(iMRI), 5-aminolevulinic acid(5-ALA), intraoperative ultrasound(iUS),Na-Fluorescein and intraoperative CT(iCT). The value of each method in resection of glioblastoma(GB) and low-grade-glioma(LGG) and their role for intraoperative orientation and usability were rated based on Likert-scales from 1(not valuable/important) to 5(very valuable/important). A total score was calculated based on each sub-score. Mann-Whitney-U-test was used to compare ratings of imaging methods. RESULTS Among the 310 participants, iMRI and 5-ALA were regarded as the most valuable intraoperative imaging methods in GB-surgery (iMRIvs.5-ALA,p=0.573;mean 4.05(SE0.149)vs.4.22(SE0.216)). Both were considered significantly more valuable than iUS, Na-Fluorescein and iCT(p≤0.001).Compared to all other methods, iMRI received significantly higher ratings for the resection of LGGs (p<0.01,mean 4.21(SE 0.143)) as well as for intraoperative orientation (mean 4.00(SE0.166)).5-ALA was rated highest regarding intraoperative usability (mean 4.07(SE0.082)). iMRI showed the highest total score compared to all other imaging modalities(p<0.001,mean 15.95(SE 0.484)). CONCLUSION iMRI and 5-ALA were rated most valuable for GB-surgery, while only iMRI reached higher ratings in LGG cases. iMRI was the best imaging method for intraoperative orientation as well as the most valuable method in overall rating. Considering the total score, 5-ALA and iUS received similar values and were rated second highest, followed by Na-Fluorescein and iCT.

Vacquinol-1 inducible cell death in glioblastoma multiforme is counter regulated by TRPM7 activity induced by exogenous ATP

Glioblastomas (GBM) are the most malignant brain tumors in humans and have a very poor prognosis. New therapeutic options are urgently needed. A novel drug, Vacquinol-1 (Vac), a quinolone derivative, displays promising properties by inducing rapid cell death in GBM but not in non-transformed tissues. Features of this type of cell death are compatible with a process termed methuosis. Here we tested Vac on a highly malignant glioma cell line observed by long-term video microscopy. Human dental-pulp stem cells (DPSCs) served as controls. A major finding was that an exogenous ATP concentration of as little as 1 μM counter regulated the Vac-induced cell death. Studies using carvacrol, an inhibitor of transient receptor potential cation channel, subfamily M, member 7 (TRPM7), demonstrated that the ATP-inducible inhibitory effect is likely to be via TRPM7. Exogenous ATP is of relevance in GBM with large necrotic areas. Our results support the use of GBM cultures with different grades of malignancy to address their sensitivity to methuosis. The video-microscopy approach presented here allows decoding of signaling pathways as well as mechanisms of chemotherapeutic resistance by long-term observation. Before implementing Vac as a novel therapeutic drug in GBM, cells from each individual patient need to be assessed for their ATP sensitivity. In summary, the current investigation supports the concept of methuosis, described as non-apoptotic cell death and a promising approach for GBM treatment. Tissue-resident ATP/necrosis may interfere with this cell-death pathway but can be overcome by a natural compound, carvacrol that even penetrates the blood-brain barrier.

Does the routine use of intraoperative MRI prolong progression free survival in low-grade glioma surgery? A retrospective study

Abstract Introduction: Available data imply that extent of resection (EOR) improves progression free survival (PFS) in patients harboring a low-grade glioma (LGG). Intraoperative high-field magnetic resonance imaging (iMRI) is an established diagnostic tool that can detect residual tumors in LGG surgery. We conducted a retrospective study to evaluate the extent of resection, clinical outcome and PFS in conventional and iMRI-based LGG resection. Patients and methods: A total of 69 patients was assessed. Only World Health Organization (WHO) grade II LGGs were evaluated. Thirty-three patients had surgery using iMRI (2008–2013). Thirty-six patients underwent surgery before introduction of iMRI at our center (2000–2008). Demographic data, extent of resection (EOR), complication rate, overall time of surgery and progression free survival were evaluated. Results: The majority of patients were treated for a diffuse astrocytoma in both cohorts (iMRI: 46.9%, historical (hist.): 61.1%). Extent of resection was a positive prognostic factor for longer PFS according to Cox regression multivariate analysis controlled by eloquent location, tumor recurrence and histological subtype [P<0.001, hazard ratio (HR) 0.247]. Additionally, the Cox regression showed the advantage and longer PFS of iMRI-assisted resections using the same settings (P=0.038, HR=0.378). Permanent neurological deficits (PND) after surgery were found in 12.5% (n=4) of the iMRI group and in 22.2% (n=8) of the historical group. Duration of surgery was significantly higher in the iMRI group (iMRI: 6.3 h, hist.: 4.3 h, P<0.036). However, there was no significant increase of postoperative surgical complications. Gross total resection (GTR) was achieved in 63.6% (n=21) of iMRI patients and 27.8% (n=10, P<0.0069) in the historical control, respectively. Binary logistic regression showed that iMRI has a significant impact on tumor remnants (P<0.001). Conclusion: In our study we have confirmed EOR to be an important positive prognostic factor for PFS. At our center, compared to a historical group, the routine use of iMRI increases EOR and was associated with a decrease in complications. Due to a selection bias no final conclusion can be drawn as to whether the use of iMRI increases PFS.

Diagnostic accuracy of intraoperative perfusion-weighted MRI and 5-aminolevulinic acid in relation to contrast-enhanced intraoperative MRI and 11C-methionine positron emission tomography in resection of glioblastoma: a prospective study

The aim of our study was to compare depicted pre-, intra-, and postoperative tumor volume of met-PET, perfusion-weighed MRI (PWI), and Gd-DTPA MRI. Further, to assess their sensitivity and specificity in correlation with histopathological specimen. Inclusion criteria of the prospective study were histological confirmed glioblastoma (GB), age > 18, and eligible for gross total resection (GTR). Met-PET was performed before and after surgery. Gd-DTPA MRI and PWI were performed before, during, and after surgery. A combined 5-aminolevulinic acid (5-ALA) and iMRI-guided surgery was performed. Volumetric analysis was evaluated for all imaging modalities except for 5-ALA. A total of 59 navigated biopsies were taken. Sensitivity and specificity were calculated for Gd-DTPA MRI, PWI, met-PET, and 5-ALA according to the histology of specimen. Met-PET depicted significantly larger tumor volume before surgery (p = 0.01) compared to PWI and Gd-DTPI MRI. We found no significant difference in tumor volume between met-PET and PWI after surgery (p = 0.059). Both PWI and met-PET showed significantly larger tumor volume after surgery when compared to Gd-DTPA (p = 0.018 and p = 0.003, respectively). Intraoperative PWI reading was impaired in 33.3% due to artifacts. Met-PET showed the highest sensitivity for detection of GB with 95%. The lowest sensitivity was found with Gd-DTPA MRI (50%), while 5-ALA and intraoperative PWI showed similar results (69 and 67%). Met-Pet is the imaging modality with the highest sensitivity to detect a residual tumor in GB. Intraoperative PWI seems to have a synergistic effect to Gd-DTPA and 5-ALA. However, its value may be limited by artifacts. Both pre- and intraoperative PWI cannot substitute met-PET in tumor detection.

Is MGMT promoter methylation to be considered in the decision making for recurrent surgery in glioblastoma patients

OBJECTIVES At present, there is no standard therapy approved for recurrent glioblastoma (rGB). In particular, the counselling of patients with an unmethylated O6-methylguanine-DNA methyltransferase (MGMT) promoter GB remains a challenge. Our aim was to compare the overall survival (OS) and progression free survival (PFS) in patients treated surgically and non-surgically at the time of GB recurrence. This was evaluated with particular reference to the impact of recurrent surgery for patients with unmethylated MGMT promoter rGB. PATIENTS AND METHODS The clinical and radiological data from 127 consecutive cases of rGB was retrospectively identified and evaluated. The PFS and OS from cohorts of surgically and non-surgically treated patients at time of GB recurrence were compared using Kaplan Meier estimations and Log-Rank tests. Multivariate Cox regression analysis included the major influencing variables (surgical resection, MGMT promoter methylation status, Karnofsky performance scale (KPS), age, eloquent tumor location) to analyze the survival benefit. Subgroup analysis of cases depending on the MGMT promoter methylation status was performed. RESULTS Multiple Cox regression analysis revealed inferior OS (p = 0.029, OR = 1.731, CI 95% 1.059-2.829) of patients treated non-surgically (14 vs. 31 months). MGMT promoter methylation and age were related to longer OS (p < 0.001, OR 2.683, CI 95% 1.631-4.414 and p = 0.009, OR = 1.029, CI95% 1.007-0.052 respectively). Gross total resection (GTR) in comparison to subtotal resection (STR) lead to a median OS of 39 months vs. 22 months and a PFS of seven vs. four months respectively. In the subgroup of cases with unmethylated MGMT promoter rGB, those who underwent GTR survived significantly longer (OS: 31 months) than patients who underwent STR (OS: 15 months, p = 0.024). PFS was six vs. four months after GTR and STR respectively. CONCLUSION Surgical management for recurrent glioblastoma appears to be a safe procedure which results in longer OS in comparison to non-surgical management. GTR may be of particular benefit to patients with unmethylated MGMT promoter rGB.