Incidence and outcome of pseudoprogression after radiation therapy in glioblastoma patients: A cohort study.

Background: Differentiating post-radiation MRI changes from progressive disease (PD) in glioblastoma (GBM) patients represents a major challenge. The clinical problem is two-sided; avoid termination of effective therapy in case of pseudoprogression (PsP) and continuation of ineffective therapy in case of PD. We retrospectively assessed the incidence, management, and prognostic impact of PsP and analyzed factors associated with PsP in a GBM patient cohort. Methods: Consecutive GBM patients diagnosed in the South-Eastern Norway Health Region from 2015 to 2018 who had received RT and follow-up MRI were included. Tumor, patient, and treatment characteristics were analyzed in relationship to re-evaluated MRI examinations at 3 and 6 months post-radiation using Response Assessment in Neuro-Oncology criteria. Results: A total of 284 patients were included in the study. PsP incidence 3 and 6 months post-radiation was 19.4% and 7.0%, respectively. In adjusted analyses, methylated O6-methylguanine-DNA methyltransferase (MGMT) promoter and the absence of neurological deterioration were associated with PsP at both 3 (p < .001 and p = .029, respectively) and 6 months (p = .045 and p = .034, respectively) post-radiation. For patients retrospectively assessed as PD 3 months post-radiation, there was no survival benefit of treatment change (p = .838). Conclusions: PsP incidence was similar to previous reports. In addition to the previously described correlation of methylated MGMT promoter with PsP, we also found that absence of neurological deterioration significantly correlated with PsP. Continuation of temozolomide courses did not seem to compromise survival for patients with PD at 3 months post-radiation; therefore, we recommend continuing adjuvant temozolomide courses in case of inconclusive MRI findings.

Preoperative Prognostic Index for Patients with Brain Metastases-A Population-Based Multi-Centre Study.

BACKGROUND: Brain metastases (BM) are common in cancer patients and are associated with high morbidity and mortality. Surgery is an option, but the optimal selection of patients for surgery is challenging and controversial. Current prognostication tools are not ideal for preoperative prognostication. By using a reference population (derivation data set) and two external populations (validation data set) of patients who underwent surgery for BM, we aimed to create and validate a preoperative prognostic index. METHODS: The derivation data set consists of 590 patients who underwent surgery for BM (2011-2018) at Oslo University Hospital. We identified variables associated with survival and created a preoperative prognostic index with four prognostic groups, which was validated on patients who underwent surgery for BM at Karolinska University Hospital and St. Olavs University Hospital during the same time period. To reduce over-fitting, we adjusted the index in accordance with our findings. RESULTS: 438 patients were included in the validation data set. The preoperative prognostic index correctly divided patients into four true prognostic groups. The two prognostic groups with the poorest survival outcomes overlapped, and these were merged to create the adjusted preoperative prognostic index. CONCLUSION: We created a prognostic index for patients with BM that predicts overall survival preoperatively. This index might be valuable in supporting informed choice when considering surgery for BM.

MR elastography identifies regions of extracellular matrix reorganization associated with shorter survival in glioblastoma patients.

Background: Biomechanical tissue properties of glioblastoma tumors are heterogeneous, but the molecular mechanisms involved and the biological implications are poorly understood. Here, we combine magnetic resonance elastography (MRE) measurement of tissue stiffness with RNA sequencing of tissue biopsies to explore the molecular characteristics of the stiffness signal. Methods: MRE was performed preoperatively in 13 patients with glioblastoma. Navigated biopsies were harvested during surgery and classified as "stiff" or "soft" according to MRE stiffness measurements (|G*|norm). Twenty-two biopsies from eight patients were analyzed by RNA sequencing. Results: The mean whole-tumor stiffness was lower than normal-appearing white matter. The surgeon's stiffness evaluation did not correlate with the MRE measurements, which suggests that these measures assess different physiological properties. Pathway analysis of the differentially expressed genes between "stiff" and "soft" biopsies showed that genes involved in extracellular matrix reorganization and cellular adhesion were overexpressed in "stiff" biopsies. Supervised dimensionality reduction identified a gene expression signal separating "stiff" and "soft" biopsies. Using the NIH Genomic Data Portal, 265 glioblastoma patients were divided into those with (n = 63) and without (n = 202) this gene expression signal. The median survival time of patients with tumors expressing the gene signal associated with "stiff" biopsies was 100 days shorter than that of patients not expressing it (360 versus 460 days, hazard ratio: 1.45, P < .05). Conclusion: MRE imaging of glioblastoma can provide noninvasive information on intratumoral heterogeneity. Regions of increased stiffness were associated with extracellular matrix reorganization. An expression signal associated with "stiff" biopsies correlated with shorter survival of glioblastoma patients.

Surgery for brain metastases-impact of the extent of resection.

BACKGROUND: Surgical resection of brain metastases improves symptoms and survival in selected patients. The benefit of gross total resection is disputed, as most patients are believed to succumb from their non-CNS tumor burden. We investigated the association between overall survival and residual tumor after surgery for single brain metastases. METHODS: We reviewed adults who underwent surgery for a single brain metastasis at a regional referral center (2011-2018). Gross total resection was defined as no visible residual tumor on cerebral MRI 12-48 h postoperatively. RESULTS: We included 373 patients. The most common primary tumors were lung cancer (36%) and melanoma (24%). We identified gross total resection in 238 patients (64%). Median overall survival was 11.0 months, 8.0 (6.2-9.8) months for patients with subtotal resection and 13.0 (9.7-16.3) months for patients with gross total resection. In a multivariate regression analysis including preoperative prognostic factors, gross total resection was associated with longer overall survival (HR: 0.66, p = 0.003). Postoperative radiotherapy administered within 6 weeks did not significantly alter the hazard ratio estimates for grade of resection. CONCLUSIONS: Our study suggests improved survival with gross total resection compared to subtotal resection. The importance of extent of resection in surgery for brain metastases should not be discarded.

Surgery for brain metastases - real-world prognostic factors' association with survival.

BACKGROUND: Surgical resection of brain metastases (BM) improves overall survival (OS) in selected patients. Selecting those patients likely to benefit from surgery is challenging. The Graded Prognostic Assessment (GPA) and the diagnosis-specific Graded Prognostic Assessment (ds-GPA) were developed to predict survival in patients with BM, but not specifically to guide patient selection for surgery. Our aim was to evaluate the feasibility of preoperative GPA/ds-GPA scores and assess variables associated with OS. METHODS: We retrospectively reviewed first-time surgical resection of BM from solid tumors at a Norwegian regional referral center from 2011 to 2018. RESULTS: Of 590 patients, 51% were female and median age was 63 years. Median OS was 10.3 months and 74 patients (13%) died within three months after surgery. Preoperatively tumor origin was unknown in 20% of patients. A GPA score could be calculated for 92% of the patients preoperatively, but could not correctly predict survival. A ds-GPA score could be calculated for 46% of patients. Multivariable regression analysis revealed shorter OS in patients with higher age, worse functioning status, colorectal primary cancer compared to lung cancer, presence of extracranial metastases, and more than four BM. Patients with preoperative progressive extracranial disease or synchronous BM had shorter OS compared to patients with stable extracranial disease. CONCLUSION: Ds-GPA could be calculated in less than half of patients preoperatively and GPA poorly identified patients which had minimal benefit of surgery. Including status of extracranial disease improve prognostication and therefore selection to surgery for brain metastases.

Diagnostic utility of Restriction Spectrum Imaging in the characterization of the peritumoral brain zone in glioblastoma: Analysis of overall and progression-free survival.

PURPOSE: We studied the ability of Restriction Spectrum Imaging (RSI), a novel advanced diffusion imaging technique, to estimate levels of cellularity in different glioblastoma regions, evaluated their prognostic value compared with established clinical diffusion metrics such as fractional anisotropy (FA) and mean diffusivity (MD). METHODS: Forty-two patients with untreated glioblastoma, IDH-wildtype, were examined with an advanced MRI tumor protocol. The region of interest (ROI) was obtained from the contrast-enhancing part of tumor and the peritumoral brain zones and then co-registered with RSI-cellularity index, FA and MD maps. Histogram parameters of diffusion metrics were assessed for all ROI locations and compared to MGMT promoter methylation status and survival. The ability of RSI-cellularity index, FA, and MD to stratify survival and were assessed by Cox proportional hazard regression, adjusted for significant clinical predictors. RESULTS: The highest RSI-cellularity index was measured in contrast-enhancing tumor core with a negative gradient from tumor core to the periphery of peritumoral zone with predictive accuracy 81 % (P < 0.001). Shorter overall survival was significant associated with higher RSI-cellularity index (hazard ratio (HR) 3.6, 95 % confidence interval (CI) 1.3-9.5, P = 0.002) with synchronal decrease in MD (HR 0.31, 95 %CI 0.1-0.8, P = 0.008) in the contrast-enhanced tumor core. This association was also consistent for RSI-cellularity index value measured in the peri-enhancing zone (HR 3.6, 95 % CI 1.0-12.3, P = 0.041). No statistically significant differences were noted between RSI-cellularity index, FA, nor MD and MGMT promoter methylation. CONCLUSION: RSI-cellularity index may be used as prognostic biomarker to improve risk stratification in patients with glioblastoma.

A Small-Molecule Tankyrase Inhibitor Reduces Glioma Stem Cell Proliferation and Sphere Formation.

Evidence suggests that the growth and therapeutic resistance of glioblastoma (GBM) may be enabled by a population of glioma stem cells (GSCs) that are regulated by typical stem cell pathways, including the WNT/ß-catenin signaling pathway. We wanted to explore the effect of treating GSCs with a small-molecule inhibitor of tankyrase, G007-LK, which has been shown to be a potent modulator of the WNT/ß-catenin and Hippo pathways in colon cancer. Four primary GSC cultures and two primary adult neural stem cell cultures were treated with G007-LK and subsequently evaluated through the measurement of growth characteristics, as well as the expression of WNT/ß-catenin and Hippo signaling pathway-related proteins and genes. Treatment with G007-LK decreased in vitro proliferation and sphere formation in all four primary GSC cultures in a dose-dependent manner. G007-LK treatment altered the expression of key downstream WNT/ß-catenin and Hippo signaling pathway-related proteins and genes. Finally, cotreatment with the established GBM chemotherapeutic compound temozolomide (TMZ) led to an additive reduction in sphere formation, suggesting that WNT/ß-catenin signaling may contribute to TMZ resistance. These observations suggest that tankyrase inhibition may serve as a supplement to current GBM therapy, although more work is needed to determine the exact downstream mechanisms involved.

Dynamic susceptibility contrast and diffusion MR imaging identify oligodendroglioma as defined by the 2016 WHO classification for brain tumors: histogram analysis approach.

PURPOSE: According to the revised World Health Organization (WHO) Classification of Tumors of the Central Nervous System (CNS) of 2016, oligodendrogliomas are now defined primarily by a specific molecular signature (presence of IDH mutation and 1p19q codeletion). The purpose of our study was to assess the value of dynamic susceptibility contrast MR imaging (DSC-MRI) and diffusion-weighted imaging (DWI) to characterize oligodendrogliomas and to distinguish them from astrocytomas. METHODS: Seventy-one adult patients with untreated WHO grade II and grade III diffuse infiltrating gliomas and known 1p/19q codeletion status were retrospectively identified and analyzed using relative cerebral blood volume (rCBV) and apparent diffusion coefficient (ADC) maps based on whole-tumor volume histograms. The Mann-Whitney U test and logistic regression were used to assess the ability of rCBV and ADC to differentiate between oligodendrogliomas and astrocytomas both independently, but also related to the WHO grade. Prediction performance was evaluated in leave-one-out cross-validation (LOOCV). RESULTS: Oligodendrogliomas showed significantly higher microvascularity (higher rCBVMean ≥ 0.80, p = 0.013) and higher vascular heterogeneity (lower rCBVPeak ≤ 0.044, p = 0.015) than astrocytomas. Diffuse gliomas with higher cellular density (lower ADCMean ≤ 1094 × 10-6 mm2/s, p = 0.009) were more likely to be oligodendrogliomas than astrocytomas. Histogram analysis of rCBV and ADC was able to differentiate between diffuse astrocytomas (WHO grade II) and anaplastic astrocytomas (WHO grade III). CONCLUSION: Histogram-derived rCBV and ADC parameter may be used as biomarkers for identification of oligodendrogliomas and may help characterize diffuse gliomas based upon their genetic characteristics.

Ultracentrifugation versus kit exosome isolation: nanoLC-MS and other tools reveal similar performance biomarkers, but also contaminations.

AIM: For isolation of exosomes, differential ultracentrifugation and an isolation kit from a major vendor were compared. MATERIALS & METHODS: 'Case study' exosomes isolated from patient-derived cells from glioblastoma multiforme and a breast cancer cell line were analyzed. RESULTS: Transmission electron microscopy, dynamic light scattering, western blotting, and so forth, revealed comparable performance. Potential protein biomarkers for both diseases were also identified in the isolates using nanoLC-MS. Western blotting and nanoLC-MS also revealed negative exosome markers regarding both isolation approaches. CONCLUSION: The two isolation methods had an overall similar performance, but we hesitate to use the term 'exosome isolation' as impurities may be present with both isolation methods. NanoLC-MS can detect disease biomarkers in exosomes and is useful for critical assessment of exosome enrichment procedures.

Therapeutic vaccination against autologous cancer stem cells with mRNA-transfected dendritic cells in patients with glioblastoma.

BACKGROUND: The growth and recurrence of several cancers appear to be driven by a population of cancer stem cells (CSCs). Glioblastoma, the most common primary brain tumor, is invariably fatal, with a median survival of approximately 1 year. Although experimental data have suggested the importance of CSCs, few data exist regarding the potential relevance and importance of these cells in a clinical setting. METHODS: We here present the first seven patients treated with a dendritic cell (DC)-based vaccine targeting CSCs in a solid tumor. Brain tumor biopsies were dissociated into single-cell suspensions, and autologous CSCs were expanded in vitro as tumorspheres. From these, CSC-mRNA was amplified and transfected into monocyte-derived autologous DCs. The DCs were aliquoted to 9-18 vaccines containing 10(7) cells each. These vaccines were injected intradermally at specified intervals after the patients had received a standard 6-week course of post-operative radio-chemotherapy. The study was registered with the ClinicalTrials.gov identifier NCT00846456. RESULTS: Autologous CSC cultures were established from ten out of eleven tumors. High-quality RNA was isolated, and mRNA was amplified in all cases. Seven patients were able to be weaned from corticosteroids to receive DC immunotherapy. An immune response induced by vaccination was identified in all seven patients. No patients developed adverse autoimmune events or other side effects. Compared to matched controls, progression-free survival was 2.9 times longer in vaccinated patients (median 694 vs. 236 days, p = 0.0018, log-rank test). CONCLUSION: These findings suggest that vaccination against glioblastoma stem cells is safe, well-tolerated, and may prolong progression-free survival.

Comparison of glioma stem cells to neural stem cells from the adult human brain identifies dysregulated Wnt- signaling and a fingerprint associated with clinical outcome.

Glioblastoma is the most common brain tumor. Median survival in unselected patients is <10 months. The tumor harbors stem-like cells that self-renew and propagate upon serial transplantation in mice, although the clinical relevance of these cells has not been well documented. We have performed the first genome-wide analysis that directly relates the gene expression profile of nine enriched populations of glioblastoma stem cells (GSCs) to five identically isolated and cultivated populations of stem cells from the normal adult human brain. Although the two cell types share common stem- and lineage-related markers, GSCs show a more heterogeneous gene expression. We identified a number of pathways that are dysregulated in GSCs. A subset of these pathways has previously been identified in leukemic stem cells, suggesting that cancer stem cells of different origin may have common features. Genes upregulated in GSCs were also highly expressed in embryonic and induced pluripotent stem cells. We found that canonical Wnt-signaling plays an important role in GSCs, but not in adult human neural stem cells. As well we identified a 30-gene signature highly overexpressed in GSCs. The expression of these signature genes correlates with clinical outcome and demonstrates the clinical relevance of GSCs.

A comparative study of the structural organization of spheres derived from the adult human subventricular zone and glioblastoma biopsies.

Sphere forming assays have been useful to enrich for stem like cells in a range of tumors. The robustness of this system contrasts the difficulties in defining a stem cell population based on cell surface markers. We have undertaken a study to describe the cellular and organizational composition of tumorspheres, directly comparing these to neurospheres derived from the adult human subventricular zone (SVZ). Primary cell cultures from brain tumors were found to contain variable fractions of cells positive for tumor stem cell markers (CD133 (2-93%)/SSEA1 (3-15%)/CXCR4 (1-72%)). All cultures produced tumors upon xenografting. Tumorspheres contained a heterogeneous population of cells, but were structurally organized with stem cell markers present at the core of spheres, with markers of more mature glial progenitors and astrocytes at more peripheral location. Ultrastructural studies showed that tumorspheres contained a higher fraction of electron dense cells in the core than the periphery (36% and 19%, respectively). Neurospheres also contained a heterogeneous cell population, but did not have an organization similar to tumorspheres. Although tumorspheres clearly display irregular and neoplastic cells, they establish an organized structure with an outward gradient of differentiation. We suggest that this organization is central in maintaining the tumor stem cell pool.

Brain tumor stem cells maintain overall phenotype and tumorigenicity after in vitro culturing in serum-free conditions.

Traditional in vitro culturing of tumor cells has been shown to induce changes so that cultures no longer represent the tumor of origin. Serum-free culturing conditions are used in a variety of cancers to propagate stem-like cells in vitro. Limited reports, however, exist on the effects of such propagation. We have compared cells from brain tumor biopsies cultivated under serum-free conditions at passages 2 and 10 to describe the effects of in vitro culturing. We were able to establish cell lines from 7 of 10 biopsies from patients with glioblastoma. The cell lines adapted to conditions and had 2.2 times increased population doubling rate at later passages. Karyotyping and comparative genomic hybridization analysis revealed that all examined cell lines had cytogenetic aberrations commonly found in glioblastomas, and there were only minor differences between tumor and early and late passages in the same culture. Whole-transcriptome analysis shows that tumors had interindividual differences. Changes in the overall expression patterns through passaging were modest, with a significant change in only 14 genes; the variation among cultures was, however, reduced through passages. The ability to differentiate differed among tumors but was maintained throughout passaging. The cells initiated tumors upon transplantation to immunodeficient mice with differing phenotypes, but a given cell culture maintained tumor phenotype after serial cultivation. The cultures established maintained individual characteristics specific to culture identity. Thus, each cell culture reflects an image of the tumor--or a personalized model--from which it was derived and remains representative after moderate expansion.

Neurosurgery in Oslo.

Neurosurgery in Oslo, Norway, was founded by the pioneer Vilhelm Magnus in the beginning of the 20th century. Through the contributions of important surgeons such as Arne Torkildsen, Kristian Kristiansen, and Helge Nornes, Norwegian neurosurgery has developed into an active clinical and technologically oriented surgical specialty. Since the unification of neurosurgical procedures in Oslo in January 2010 into one department, it is one of the largest neurosurgical departments in Europe with more than 4500 surgeries performed per year covering all aspects of neurosurgery. The department's scientific focus is on clinical studies, in close collaboration with supportive clinical departments; through interaction with basic science stem cell groups, an increasing effort is being made in translational cellular and molecular medicine.

Gamma knife stereotactic radiosurgery of Nelson syndrome.

OBJECTIVE: Gamma knife radiosurgery (GKR) can be used as primary or adjuvant therapy for the treatment of an ACTH-producing pituitary tumor after bilateral adrenalectomy, called Nelson syndrome (NS). We have examined the effect of GKR on tumor growth and ACTH-hypersecretion, and characterized the adverse events of this treatment in patients with NS. DESIGN: Cross-sectional follow-up study. First, retrospective data pre- and post-GKR were collected. Patients then underwent a predefined survey including radiological, endocrinological, ophthalmological, and neurosurgical evaluation. SUBJECTS: Ten patients treated with GKR for NS after previous bilateral adrenalectomy. The mean follow-up was 7 years. No patient was lost to follow-up. RESULTS: Tumor growth was stopped in all patients. The ACTH levels declined in eight patients, and normalized in one patient. There was a significant drop in ACTH levels, with a half-time of 2.8 years. No patient developed visual field defects or any other cranial nerve dysfunction as a result of treatment. Four patients started hormone substitution therapy during the follow-up period. The substitution therapy of three pituitary axes present at GKR treatment could be stopped during the same period. One patient developed a glioblastoma in the left parieto-occipital region 14 years after GKR, far from the field of treatment. As the radiation level was below 1Gy to this area, it is unlikely that the GKR treatment itself induced the malignant tumor. CONCLUSION: In patients with NS, GKR is an effective adjuvant treatment, carrying relatively few adverse effects. Although the risk of developing a secondary neoplasia after GKR is present, it is probably extremely low.

Gamma knife stereotactic radiosurgery for acromegaly.

BACKGROUND: Gamma knife radiosurgery (GKR) is an adjuvant treatment for acromegaly if surgery fails to normalize GH hypersecretion. OBJECTIVE: To examine the effect of GKR on tumor growth and hypersecretion, and to characterize the adverse effect of this treatment. DESIGN: Cross-sectional follow-up study. First, retrospective data pre- and post-GKR were collected. PATIENTS then underwent a predefined survey including radiological, endocrinological, ophthalmological, and neurosurgical evaluation. SETTING: Norwegian National Center for gamma knife treatment. PATIENTS: Sixty-one patients treated with GKR for acromegaly. Out of 55, 53 living patients underwent a detailed survey. The mean follow-up was 5.5 years. No patient was lost to follow-up. RESULTS: Tumor growth was stopped in all patients. At 3, 5, and 10 years after GKR, 45, 58, and 86% of patients had normal IGF-I levels. Consecutive hormone value analysis showed that patients receiving GH-suppressive medication had a more rapid decline in hypersecretion than those who did not receive such medication. Evaluated by survey baseline values alone, non-elevated IGF-I and GH levels below 5 mIU/l were found in 38%. GH-suppressive medication was terminated in 16 out of 40 patients following GKR. Nine out of 53 surveyed patients (17%) had normal IGF-I and GH nadir below 2.6 mIU/l at glucose tolerance tests, while not on hormone-suppressive medication. Two patients developed minor visual field defects. Eight patients started hormone substitution therapy during the follow-up period. CONCLUSION: GKR is an effective adjuvant treatment for residual acromegaly, carrying few side effects.

Mammalian ykt6 is a neuronal SNARE targeted to a specialized compartment by its profilin-like amino terminal domain.

SNAREs are required for specific membrane fusion throughout the endomembrane system. Here we report the characterization of rat ykt6, a prenylated SNARE selectively expressed in brain neurons. Immunofluorescence microscopy in neuronal and neuroendocrine cell lines revealed that membrane-associated ykt6 did not colocalize significantly with any conventional markers of endosomes, lysosomes, or the secretory pathway. However, ykt6-containing membranes displayed very minor overlaps with lysosomes and dense-core secretory granules and were similar to lysosomes in buoyant density. Thus, ykt6 appears to be specialized for the trafficking of a unique membrane compartment, perhaps related to lysosomes, involved in aspects of neuronal function. Targeting of this SNARE to the ykt6 compartment was mediated by its profilin-like amino-terminal domain, even in the absence of protein prenylation. Although several other R-SNAREs contain related amino-terminal domains, only the ykt6 version was able to confer the specialized localization. Rat ykt6, which contains an arginine in its SNARE motif zero-layer, was found to behave like other R-SNAREs in its SNARE assembly properties. Interestingly, cytosolic ykt6, constituting more than half of the total cellular pool, appeared to be conformationally inactive for SNARE complex assembly, perhaps indicative of a regulatory mechanism that prevents promiscuous and potentially deleterious SNARE interactions.