H3K27-Altered Diffuse Glioma of the Spinal Cord in Adult Patients: A Qualitative Systematic Review and Peculiarity of Radiological Findings

Background: Primary spinal cord diffuse gliomas (SpDG) are rare tumors that may harbor, like diffuse intrinsic pontine gliomas (DIPG), H3K27M mutations. According to the WHO (2021), SpDGs are included in diffuse midline H3K27-altered gliomas, which occur more frequently in adults and show unusual clinical presentation, neuroradiological features, and clinical behavior, which differ from H3 G34-mutant diffuse hemispheric glioma. Currently, homogeneous adult-only case series of SpDG, with complete data and adequate follow-up, are still lacking. Methods: We conducted a qualitative systematic review, focusing exclusively on adult and young adult patients, encompassing all studies reporting cases of primitive, non-metastatic SpDG with H3K27 mutation. We analyzed the type of treatment administered, survival, follow-up duration, and outcomes. Results: We identified 30 eligible articles published between 1990 and 2023, which collectively reported on 62 adult and young adult patients with primitive SpDG. Postoperative outcomes were assessed based on the duration of follow-up, with outcomes categorized as either survival or mortality. Patients who underwent surgery were followed up for a mean duration of 17.37 months, while those who underwent biopsy had a mean follow-up period of 14.65 months. Among patients who were still alive, the mean follow-up duration was 18.77 months. The radiological presentation of SpDG varies widely, indicating its lack of uniformity. Conclusion: Therefore, we presented a descriptive scenario where SpDG was initially suspected to be a meningioma, but was later revealed to be a malignant SpDG with H3K27M mutation.

Synchronous versus metachronous spinal metastasis: a comparative study of survival outcomes following neurosurgical treatment

PURPOSE

Patients with spinal metastases (SM) from solid neoplasms typically exhibit progression to an advanced cancer stage. Such metastases can either develop concurrently with an existing cancer diagnosis (termed metachronous SM) or emerge as the initial indication of an undiagnosed malignancy (referred to as synchronous SM). The present study investigates the prognostic implications of synchronous compared to metachronous SM following surgical resection.

METHODS

From 2015 to 2020, a total of 211 individuals underwent surgical intervention for SM at our neuro-oncology facility. We conducted a survival analysis starting from the date of the neurosurgical procedure, comparing those diagnosed with synchronous SM against those with metachronous SM.

RESULTS

The predominant primary tumor types included lung cancer (23%), prostate cancer (21%), and breast cancer (11.3%). Of the participants, 97 (46%) had synchronous SM, while 114 (54%) had metachronous SM. The median overall survival post-surgery for those with synchronous SM was 13.5 months (95% confidence interval (CI) 6.1-15.8) compared to 13 months (95% CI 7.7-14.2) for those with metachronous SM (p = 0.74).

CONCLUSIONS

Our findings suggest that the timing of SM diagnosis (synchronous versus metachronous) does not significantly affect survival outcomes following neurosurgical treatment for SM. These results support the consideration of neurosurgical procedures regardless of the temporal pattern of SM manifestation.

Boswellic acid formulations are not suitable for treatment of pediatric high-grade glioma due to tumor promoting potential

Background and aim

Pediatric high-grade gliomas (pedHGG) comprise a very poor prognosis. Thus, parents of affected children are increasingly resorting to complementary and alternative medicine (CAM), among those Boswellia extracts. However, nothing is known about the therapeutic effectiveness of their active substances, Boswellic acids (BA) in pedHGG. Thus, we aimed to investigate if the three main Boswellic acids (BA) present in Boswellia plants, alpha-boswellic acid (α-BA), beta-boswellic acid (β-BA) and 3-acetyl-11-keto-beta-boswellic acid (AKBA) hold any promising potential for treatment of affected pedHGG patients.

Experimental procedure

Histone 3 (H3)-wildtype and H3.3K27M-mutant pedHGG cell lines were treated with BA, either alone or in combination with radio-chemotherapy with temozolomide. Cell viability, stemness properties, apoptosis, in ovo tumor growth and the transcriptome was investigated upon BA treatment.

Results and conclusion

Interestingly, α-BA and β-BA treatment promoted certain tumor properties in both pedHGG cells. AKBA treatment reduced cell viability and colony growth accompanied by induction of slight anti-inflammatory effects especially in H3.3K27M-mutant pedHGG cells. However, no effects on apoptosis and in ovo tumor growth were found. In conclusion, besides positive anti-tumor effects of AKBA, tumor promoting effects were observed upon treatment with α-BA and β-BA. Thus, only pure AKBA formulations may be used to exploit any potential positive effects in pedHGG patients. In conclusion, the use of commercially available supplements with a mixture of different BA cannot be recommended due to detrimental effects of certain BA whereas pure AKBA formulations might hold some potential as therapeutic supplement for treatment of pedHGG patients.

Intraoperative or postoperative stereotactic radiotherapy for brain metastases: time to systemic treatment onset and other patient-relevant outcomes

PURPOSE

Intraoperative radiotherapy (IORT) has become a viable treatment option for resectable brain metastases (BMs). As data on local control and radiation necrosis rates are maturing, we focus on meaningful secondary endpoints such as time to next treatment (TTNT), duration of postoperative corticosteroid treatment, and in-hospital time.

METHODS

Patients prospectively recruited within an IORT study registry between November 2020 and June 2023 were compared with consecutive patients receiving adjuvant stereotactic radiotherapy (SRT) of the resection cavity within the same time frame. TTNT was defined as the number of days between BM resection and start of the next extracranial oncological therapy (systemic treatment, surgery, or radiotherapy) for each of the groups.

RESULTS

Of 95 BM patients screened, IORT was feasible in 84 cases (88%) and ultimately performed in 64 (67%). The control collective consisted of 53 SRT patients. There were no relevant differences in clinical baseline features. Mean TTNT (range) was 36 (9 - 94) days for IORT patients versus 52 (11 - 126) days for SRT patients (p = 0.01). Mean duration of postoperative corticosteroid treatment was similar (8 days; p = 0.83), as was mean postoperative in-hospital time (11 versus 12 days; p = 0.97). Mean total in-hospital time for BM treatment (in- and out-patient days) was 11 days for IORT versus 19 days for SRT patients (p < 0.001).

CONCLUSION

IORT for BMs results in faster completion of interdisciplinary treatment when compared to adjuvant SRT, without increasing corticosteroid intake or prolonging in-hospital times. A randomised phase III trial will determine the clinical effects of shorter TTNT.

ICOS DNA methylation regulates melanoma cell-intrinsic ICOS expression, is associated with melanoma differentiation, prognosis, and predicts response to immune checkpoint blockade

BACKGROUND

Inducible T cell costimulator ICOS is an emerging target in immuno-oncology. The aim of this study was to investigate the epigenetic regulation of ICOS in melanoma by DNA methylation.

METHODS

We comprehensively investigate ICOS DNA methylation of specific CpG sites and expression pattern within the melanoma microenvironment with regard to immune correlates, differentiation, clinical outcomes, and immune checkpoint blockade (ICB) response.

RESULTS

Our study revealed a sequence-contextual CpG methylation pattern consistent with an epigenetically regulated gene. We found a cell type-specific methylation pattern and locus-specific correlations and associations of CpG methylation with ICOS mRNA expression, immune infiltration, melanoma differentiation, prognosis, and response to ICB. High ICOS mRNA expression was identified as a surrogate for enriched immune cell infiltration and was associated with favorable overall survival (OS) in non-ICB-treated patients and predicted response and a prolonged progression-free survival (PFS) following ICB therapy initiation. ICOS hypomethylation, however, significantly correlated with poor OS in non-ICB patients but predicted higher response and prolonged PFS and OS in ICB-treated patients. Moreover, we observed cytoplasmic and sporadically nuclear tumor cell-intrinsic ICOS protein expression. Tumor cell-intrinsic ICOS protein and mRNA expression was inducible by pharmacological demethylation with decitabine.

CONCLUSION

Our study identified ICOS DNA methylation and mRNA expression as promising prognostic and predictive biomarkers for immunotherapy in melanoma and points towards a hitherto undescribed role of ICOS in tumor cells.

Multiomic neuropathology improves diagnostic accuracy in pediatric neuro-oncology

The large diversity of central nervous system (CNS) tumor types in children and adolescents results in disparate patient outcomes and renders accurate diagnosis challenging. In this study, we prospectively integrated DNA methylation profiling and targeted gene panel sequencing with blinded neuropathological reference diagnostics for a population-based cohort of more than 1,200 newly diagnosed pediatric patients with CNS tumors, to assess their utility in routine neuropathology. We show that the multi-omic integration increased diagnostic accuracy in a substantial proportion of patients through annotation to a refining DNA methylation class (50%), detection of diagnostic or therapeutically relevant genetic alterations (47%) or identification of cancer predisposition syndromes (10%). Discrepant results by neuropathological WHO-based and DNA methylation-based classification (30%) were enriched in histological high-grade gliomas, implicating relevance for current clinical patient management in 5% of all patients. Follow-up (median 2.5 years) suggests improved survival for patients with histological high-grade gliomas displaying lower-grade molecular profiles. These results provide preliminary evidence of the utility of integrating multi-omics in neuropathology for pediatric neuro-oncology.

Molecular pathological insights reveal a high number of unfavorable risk patients among children treated for medulloblastoma and CNS-PNET in Oslo 2005-2017

BACKGROUND

An unexplained regional difference in survival was observed in previous publications on outcome for children treated for medulloblastoma and supratentorial primitive neuroectodermal tumor (CNS-PNET) in Norway. We aimed now to reevaluate and perform a retrospective molecular-based risk stratification of all embryonal brain tumors (excluding atypical teratoid rhabdoid tumors [ATRT]) in pediatric patients, who underwent surgery and treatment at Oslo University Hospital between 2005 and 2017.

PROCEDURE

Specimens from all patients <20 years of age with initial diagnosis of medulloblastoma or CNS-PNET were reviewed. Molecular analyses comprised NanoString gene expression, molecular inversion probe profiling, Sanger sequencing, and 850K-methylation analysis. Whole chromosomal aberration signatures were assessed in standard-risk non-WNT/non-SHH medullobastomas for molecular risk stratification.

RESULTS

We identified 53 non-ATRT embryonal tumors among which 33 were medulloblastomas. Molecular genetic parameters including whole chromosomal aberration signatures allowed classification of 17 medulloblastomas as molecular high risk. These patients had a significantly worse 5-year overall survival than the remaining 16 medulloblastoma patients (52.9% vs. 87.1% p = 0.036). Five patients in our cohort had tumors that are considered as new entities in the 2021 classification of tumors of the central nervous system. Five tumors were re-classified as nonembryonal tumors after review.

CONCLUSION

Molecular-based risk stratification of standard-risk non-WNT/non-SHH medulloblastoma enabled superior identification of medulloblastomas with dismal prognosis. Our cohort demonstrated a significantly increased fraction of standard-risk non-WNT/non-SHH medulloblastoma with molecular high-risk profile compared to other studies, which might have contributed to previously reported unfavorable outcome data.

HGG-16. Final analysis of the HIT-HGG-2007 trial (ISRCTN19852453): Significant survival benefit for pontine and non-pontine pediatric high-grade gliomas in comparison to previous HIT-GBM-C/-D trials

The aim of the HIT-HGG-2007 trial (ISRCTN19852453) was to demonstrate therapeutic non-inferiority of temozolomide radiochemotherapy for pediatric patients (3-18 years) with high-grade gliomas (pedHGG) in comparison to the cisplatinum-based radiochemotherapy of the two previous clinical trials HIT-GBM-C/-D. Between 06/2009 and 12/2016, 456 patients were enrolled at 79 centers in Germany, Austria, and Switzerland (n=18 dropouts, remaining patients for confirmatory analysis: n=438). 438 patients from HIT-GBM-C/-D served as historical control. All pedHGG diagnoses had been confirmed by central neuroradiological and neuropathological review. Primary objective was achieved since non-inferiority of HIT-HGG-2007 in comparison to HIT-GBM-C/-D as indicated by 6 months event-free survival (EFS) was statistically confirmed (p=0.0125). Statistical survival analyses even revealed a better overall survival (OS) and EFS for HIT-HGG-2007 patients in comparison to their HIT-GBM-C/-D counterparts (EFS: p<0.0001; OS: p=0.0328). While EFS subgroup analyses for pontine and non-pontine pedHGG also showed a better survival of HIT-HGG-2007 patients (median EFS pontine pedHGG: 8.2 (n=152; confidence interval (CI): 7.6-9.4) versus 6.2 (n=170; CI: 5.5-6.9) months, p=0.0079; median EFS non-pontine pedHGG: 10.7 (n=276; CI: 9.6-12.4) versus 7.4 (n=267; CI: 6.4-9.2) months, p<0.0001), OS was only improved in HIT-HGG-2007 patients with non-pontine pedHGG (median OS non-pontine pedHGG: 19.3 (CI: 16.8-23.3) versus 16.2 (CI: 14.2-19.1) months; p=0.0181) but not with pontine pedHGG (median OS pontine pedHGG: 11.4 months versus 11.3 months, p=0.4021) Toxicity profile of HIT-HGG-2007 seemed very favorable with most CTCAE (common toxicity criteria adverse event) ≥ grade 3 as hematological toxicity, hepatotoxicity, and neurotoxicity. Less toxicity was observed during concomitant radiochemotherapy in comparison to HIT-GBM-C/-D. Further subgroup survival analyses as well as the assessment of the impact of MGMT promoter methylation are ongoing. In conclusion, our data show non-inferiority of the HIT-HGG-2007 trial with increased survival and less toxicity when compared with previous trials HIT-GBM-C/-D.

ETMR-04. Embryonal tumor with multi-layered rosettes (ETMR) located in the brainstem: a case report on clinical decision-making and a multimodal, interdisciplinary treatment approach including interstitial brachytherapy

OBJECTIVE: Embryonal tumors with multi-layered rosettes (ETMR) (CNS WHO grade 4) comprise a rare and malignant tumor type affecting predominantly infants below 3 years of age. The treatment consists of maximal safe surgical resection, irradiation, and intensive medulloblastoma type chemotherapy. Despite aggressive treatment, the prognosis of these patients remains poor, especially for brainstem tumors. We present the case of a male infant diagnosed with a brainstem ETMR, successfully treated with an interdisciplinary multimodal approach, including stereotactic interstitial brachytherapy. RESULTS: A 19 month old boy first presented with hemiparesis, intermittent bradycardia and reduced consciousness. Initial imaging showed a brainstem lesion with characteristic features of a diffuse intrinsic pontine glioma (DIPG). We performed stereotactic biopsy to confirm the diagnosis and initiated temozolomide treatment. While the pathology result was still pending, the boy’s clinical condition deteriorated to a soporic state with stretch synergisms. By emergency open surgery, partial resection was achieved. Eventually, the patient recovered rapidly. After the diagnosis of ETMR was established, medulloblastoma type chemotherapy (systemic carboplatin/etoposide; intrathecal methotrexate) was administered. After two cycles, the patient showed only residual right-sided hemiparesis. However, imaging demonstrated only a minimal reduction of the tumor size. Therefore, stereotactic interstitial brachytherapy using 125iodine seeds and subsequent high-dose chemotherapy (HDCT) with autologous stem cell transplantation (ASCT) was performed and overall tolerated well. After two months of brachytherapy and two additional cycles of chemotherapy, the MRI showed ≥ 50% reduction in tumor volume and no neurological deficit can be clinically detected. CONCLUSION: This case indicates that stereotactic interstitial brachytherapy during intensive systemic chemotherapy is feasible. It may provide a suitable treatment for malignant infant brain tumors. Furthermore, it shows that paediatric patients are capable of recovery even after devastating neurological symptoms. Lastly, it emphasizes the importance of multidisciplinary and multimodal treatment for rare diseases.

HGG-49. Gliomatosis cerebri in children: A collaborative report from the European Society for Pediatric Oncology (SIOPE)

BACKGROUND: Gliomatosis cerebri (GC), a radiologically defined diffusely infiltrating glioma, is no longer considered a distinct entity since the 2016 WHO classification for tumors of the CNS. Due to its rarity and dismal prognosis treatment recommendations in children remain ambiguous. Using central neuroradiological review, we performed a multi-institutional, retrospective study of GC providing comprehensive radiological, clinical, and (epi)genetic characterization. RESULTS: We included 104 patients between 1-19 years. Within a median follow-up of 15.5 months (range, 2.3-138.8), 93 patients (89.4 %) had died, 4 (3.8 %) were lost to follow-up and 7 (6.8 %) were alive with stable/progressive disease. Median progression-free- (PFS) and overall survival (OS) were 8.6 months (interquartile range, 4.3-14.0) and 15.5 months (10.9-27.7), respectively. Former WHO grading correlated significantly with median OS: WHO °II: 47.8 months (25.2-55.7); WHO °III: 15.9 months (11.4-26.3); WHO °IV: 10.4 months (8.8-14.4) (p&lt;0.001). In high-grade gliomas (HGG), radiochemotherapy showed best PFS (p=0.002). Compared to hemispheric pediatric non-GC HGG, GC phenotype was associated with decreased OS (p=0.001). Methylation-based classification and exome sequencing were possible for 49 and 45 patients, respectively. According to the 2021 WHO classification, most cases were considered as IDH-/H3-wildtype gliomas (n=37/49, 75.5 %), mostly with a pedRTK2 subtype (n=15, 30.6%), followed by pedMYCN (n=5, 10.2 %). Within the IDH-/H3-wildtype gliomas, EGFR-altered tumors (n=10) seemed overrepresented. Survival analyses revealed a better OS for IDH1-mutant tumors (n=6; 54.6 vs. 15.2 months in IDH-wildtype; p=0.015) and a worse OS for TP53-mutant tumors (n=6; p=0.001). Despite the potential overrepresentation of EGFR-altered tumors, no other specific molecular markers for GC could be identified so far. Further analyses are ongoing. CONCLUSIONS: GC in children is confirmed as a poor prognostic phenotype include various epigenetic pediatric glioma subtypes, without a proven (epi)genetic mark of its own. The relevance of overrepresented EGFR alterations has to be determined yet.

Pediatric high-grade gliomas and the WHO CNS Tumor Classification—Perspectives of pediatric neuro-oncologists and neuropathologists in light of recent updates

Background

The WHO Classification of Tumors of the Central Nervous System has undergone major restructuring. Molecularly defined diagnostic criteria were introduced in 2016 (revised 4th edition) and expanded in 2021 (5th edition) to incorporate further essential diagnostic molecular parameters. We investigated potential differences between specialists in perception of these molecularly defined subtypes for pediatric high-grade gliomas (pedHGG).

Methods

We designed a 22-question survey studying the impact of the revised 4th edition of the WHO classification on pedHGG. Data were collected and statistically analyzed to examine the spectrum of viewpoints and possible differences between neuro-oncologists and neuropathologists.

Results

465 participants from 53 countries were included; 187 pediatric neuro-oncologists (40%), 160 neuropathologists (34%), and 118 additional experts (26%). Neuro-oncologists reported issues with the introduction of molecularly defined tumor types, as well as the abolishment or renaming of established tumor entities, while neuropathologists did not to the same extent. Both groups indicated less relevant or insufficient diagnostic definitions were available in 2016. Reported issues were classified and assessed in the 2021 WHO classification and a substantial improvement was perceived. However, issues of high clinical relevance remain to be addressed, including the definition of clinical phenotypes for diffuse intrinsic pontine glioma and gliomatosis cerebri.

Conclusions

Within the WHO classification of pediatric brain tumors, such as pedHGG, rapid changes in molecular characterization have been introduced. This study highlights the ongoing need for cross talk between pathologist and oncologist to advance the classification of pedHGG subtypes and ensure biological relevance and clinical impact.

Magnetic Resonance Imaging Characteristics of Molecular Subgroups in Pediatric H3 K27M Mutant Diffuse Midline Glioma

Purpose

Recent research identified histone H3 K27M mutations to be associated with a dismal prognosis in pediatric diffuse midline glioma (pDMG); however, data on detailed MRI characteristics with respect to H3 K27 mutation status and molecular subgroups (H3.1 and H3.3 K27M mutations) are limited.

Methods

Standardized magnetic resonance imaging (MRI) parameters and epidemiologic data of 68 pDMG patients (age <18 years) were retrospectively reviewed and compared in a) H3 K27M mutant versus H3 K27 wildtype (WT) tumors and b) H3.1 versus H3.3 K27M mutant tumors.

Results

Intracranial gliomas (n = 58) showed heterogeneous phenotypes with isointense to hyperintense signal in T2-weighted images and frequent contrast enhancement. Hemorrhage and necrosis may be present. Comparing H3 K27M mutant to WT tumors, there were significant differences in the following parameters: i) tumor localization (p = 0.001), ii) T2 signal intensity (p = 0.021), and iii) T1 signal homogeneity (p = 0.02). No significant imaging differences were found in any parameter between H3.1 and H3.3 K27M mutant tumors; however, H3.1 mutant tumors occurred at a younger age (p = 0.004). Considering spinal gliomas (n = 10) there were no significant imaging differences between the analyzed molecular groups.

Conclusion

With this study, we are the first to provide detailed MR imaging data on H3 K27M mutant pDMG with respect to molecular subgroup status in a large patient cohort. Our findings may support diagnosis and future targeted therapeutic trials of pDMG within the framework of the radiogenomics concept.

Supplementary Information

The online version of this article (10.1007/s00062-021-01120-3) contains supplementary material, which is available to authorized users.

Transitioning to molecular diagnostics in pediatric high-grade glioma: experiences with the 2016 WHO classification of CNS tumors

Background

Pediatric neuro-oncology was profoundly changed in the wake of the 2016 revision of the WHO Classification of Tumors of the Central Nervous System. Practitioners were challenged to quickly adapt to a system of tumor classification redefined by molecular diagnostics.

Methods

We designed a 22-question survey studying the impact of the revised WHO classification on pediatric high-grade glioma. The survey collected basic demographics, general attitudes, issues encountered, and opinions on pediatric subtypes. Participant answers were analyzed along socioeconomic lines utilizing the human development index (HDI) of the United Nations and membership in the group of seven (G7) world economic forum.

Results

Four hundred and sixty-five participants from 53 countries were included, 187 pediatric neurooncologists (40%), 160 neuropathologists (34%), and 118 other experts (26%). When asked about pediatric high-grade glioma entities, participants from very high development countries preferred treating a patient based on genetic findings. Participants from high and medium development countries indicated using traditional histology and tumor location as mainstays for therapeutic decisions. Non-G7 countries tended to regard the introduction of molecularly characterized tumor entities as a problem for daily routine due to lack of resources.

Conclusions

Our findings demonstrate an overall greater reliance and favorability to molecular diagnostics among very high development countries. A disparity in resources and access to molecular diagnostics has left some centers unable to classify pediatric high-grade glioma per the WHO classification. The forthcoming edition should strain to abate disparities in molecular diagnostic availability and work toward universal adaptation.

Diagnosis of Pseudoprogression Following Lomustine-Temozolomide Chemoradiation in Newly Diagnosed Glioblastoma Patients Using FET-PET

PURPOSE

The CeTeG/NOA-09 phase III trial demonstrated a significant survival benefit of lomustine-temozolomide chemoradiation in patients with newly diagnosed glioblastoma with methylated O⁶-methylguanine-DNA methyltransferase (MGMT) promoter. Following lomustine-temozolomide chemoradiation, late and prolonged pseudoprogression may occur. We here evaluated the value of amino acid PET using O-(2-[¹⁸F]fluoroethyl)-l-tyrosine (FET) for differentiating pseudoprogression from tumor progression.

EXPERIMENTAL DESIGN

We retrospectively identified patients (i) who were treated off-study according to the CeTeG/NOA-09 protocol, (ii) had equivocal MRI findings after radiotherapy, and (iii) underwent additional FET-PET imaging for diagnostic evaluation (number of scans, 1-3). Maximum and mean tumor-to-brain ratios (TBR_max, TBR_mean) and dynamic FET uptake parameters (e.g., time-to-peak) were calculated. In patients with more than one FET-PET scan, relative changes of TBR values were evaluated, that is, an increase or decrease of >10% compared with the reference scan was considered as tumor progression or pseudoprogression. Diagnostic performances were evaluated using ROC curve analyses and Fisher exact test. Diagnoses were confirmed histologically or clinicoradiologically.

RESULTS

We identified 23 patients with 32 FET-PET scans. Within 5-25 weeks after radiotherapy (median time, 9 weeks), pseudoprogression occurred in 11 patients (48%). The parameter TBR_mean calculated from the FET-PET performed 10 ± 7 days after the equivocal MRI showed the highest accuracy (87%) to identify pseudoprogression (threshold, <1.95; P = 0.029). The integration of relative changes of TBR_mean further improved the accuracy (91%; P < 0.001). Moreover, the combination of static and dynamic parameters increased the specificity to 100% (P = 0.005).

CONCLUSIONS

The data suggest that FET-PET parameters are of significant clinical value to diagnose pseudoprogression related to lomustine-temozolomide chemoradiation.

DCE-MRI in Glioma, Infiltration Zone and Healthy Brain to Assess Angiogenesis: A Biopsy Study

Purpose

To explore the focal predictability of vascular growth factor expression and neovascularization using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in glioma.

Methods

120 brain biopsies were taken in vital tumor, infiltration zone and normal brain tissue of 30 glioma patients: 17 IDH(isocitrate dehydrogenase)-wildtype glioblastoma (GBM), 1 IDH-wildtype astrocytoma °III (together prognostic group 1), 3 IDH-mutated GBM (group 2), 3 anaplastic astrocytomas IDH-mutated (group 3), 4 anaplastic oligodendrogliomas and 2 low-grade oligodendrogliomas (together prognostic group 4). A mixed linear model evaluated the predictabilities of microvessel density (MVD), vascular area ratio (VAR), mean vessel size (MVS), vascular endothelial growth factor and receptors (VEGF-A, VEGFR‑2) and vascular endothelial-protein tyrosine phosphatase (VE-PTP) expression from Tofts model kinetic and model-free curve parameters.

Results

All kinetic parameters were associated with VEGF‑A (all p < 0.001) expression. K^trans, k_ep and v_e were associated with VAR (p = 0.006, 0.004 and 0.01, respectively) and MVS (p = 0.0001, 0.02 and 0.003, respectively) but not MVD (p = 0.84, 0.74 and 0.73, respectively). Prognostic groups differed in K^trans (p = 0.007) and v_e (p = 0.004) values measured in the infiltration zone. Despite significant differences of VAR, MVS, VEGF‑A, VEGFR‑2, and VE-PTP in vital tumor tissue and the infiltration zone (p = 0.0001 for all), there was no significant difference between kinetic parameters measured in these zones.

Conclusion

The DCE-MRI kinetic parameters show correlations with microvascular parameters in vital tissue and also reveal blood-brain barrier abnormalities in the infiltration zones adequate to differentiate glioma prognostic groups.

Supplementary Information

The online version of this article (10.1007/s00062-021-01015-3) contains supplementary material, which is available to authorized users.

CTLA4 promoter methylation predicts response and progression-free survival in stage IV melanoma treated with anti-CTLA-4 immunotherapy (ipilimumab)

Anti-CTLA-4-antibodies can induce long-lasting tumor remissions. However, only a few patients respond, necessitating the development of predictive companion biomarkers. Increasing evidence suggests a major role of epigenetics, including DNA methylation, in immunology and resistance to immune checkpoint blockade. Here, we tested CTLA4 promoter methylation and CTLA-4 protein expression as predictive biomarkers for response to anti-CTLA-4 immunotherapy. We identified retrospectively N = 30 stage IV melanoma patients treated with single-agent anti-CTLA-4 immunotherapy (ipilimumab). We used quantitative methylation-specific PCR and immunohistochemistry to quantify CTLA4 methylation and protein expression in pre-treatment samples. CTLA4 methylation was significantly higher in progressive as compared to responding tumors and significantly associated with progression-free survival. A subset of infiltrating lymphocytes and tumor cells highly expressed CTLA-4. However, CTLA-4 protein expression did not predict response to treatment. We conclude that CTLA4 methylation is a predictive biomarker for response to anti-CTLA-4 immunotherapy.

HGG-34. DETECTION OF ONCOGENIC FUSION EVENTS IN SUPRATENTORIAL GLIOBLASTOMAS OF YOUNG CHILDREN

INTRODUCTION

Glioblastoma in infancy and early childhood is characterized by a more favorable outcome compared to older children, a stable genome, and the occurrence of tyrosine kinase gene fusions that may represent therapeutic targets.

METHODS

50 glioblastomas (GBM) with supratentorial location occurring in children younger than four years were retrieved from the archives of the Brain Tumor Reference Center, Institute of Neuropathology, University of Bonn. DNA and RNA were extracted from FFPE tumor samples. Gene fusions were identified by FISH using break-apart probes for ALK, NTRK1, -2, -3, ROS1 and MET, Molecular Inversion Probe (MIP) methodology, and targeted RNA sequencing.

RESULTS

37 supratentorial GBM occurred in the first year of life, 13 GBM between one and four years. 18 cases showed fusions of ALK to different fusion partners; all occurred in the first year of life (18/37 cases, 48.6%). Fusions of ROS1 were found in 5, MET in 3, NTRK1, -2, -3 in 10 cases. 12 cases showed no and two novel fusions. The different methods led to comparable results; targeted RNA sequencing was not successful in a fraction of cases. Break-apart FISH led to reliable results on the next day, MIP technology represented the most sensitive method for analysis of FFPE samples.

CONCLUSIONS

Gene fusions involving the tyrosine kinase genes ALK, MET, ROS1 and NTRK1, -2, -3 occurred in 72% of glioblastomas of children younger than four years; the most frequent were ALK fusions occurring in infant GBM. DNA based MIP technology represented the most robust and sensitive assay.

Molecular, clinicopathological, and immune correlates of LAG3 promoter DNA methylation in melanoma

Background

The co-receptor lymphocyte-activation gene-3 (LAG3, LAG-3, CD223) is a potential target for immune checkpoint inhibition immunotherapies. However, little is known about the biological and clinical significance of LAG3 DNA methylation in melanoma and its microenvironment.

Methods

We evaluated LAG3 promoter and gene body methylation in a cohort of N = 470 melanoma patients obtained from The Cancer Genome Atlas (TCGA cohort), an independent cohort of N = 120 patients from the University Hospital Bonn, and in subsets of peripheral blood leukocytes, melanocytes, and melanoma cell lines. We validated the association of LAG3 methylation with mRNA expression in vitro in the melanoma cell line A375 treated with the hypomethylating agent 5-azacytidine and stimulated with interferon-γ. Finally, we investigated correlations between LAG3 methylation and progression-free survival in patients treated with immune checkpoint blockade (ICB cohort, N = 118).

Findings

Depending on the analysed locus (promoter, gene body) we found region-dependent significant LAG3 methylation differences between monocytes, B cells, CD8⁺ and CD4⁺ T cells, regulatory T cells, melanocytes, and melanoma cell lines. In tumor tissues, methylation correlated significantly with LAG3 mRNA expression, immune cell infiltrates (histopathologic lymphocyte score and RNA-Seq signatures of distinct immune infiltrates), and an interferon-γ signature. Finally, LAG3 methylation was associated with overall survival in the TCGA cohort and progression-free survival in the ICB cohort. We detected basal LAG3 mRNA expression in the melanoma cell A375 and an interferon-γ inducible expression after demethylation with 5-azacytidine.

Interpretation

Our study points towards an epigenetic regulation of LAG3 via promoter methylation and suggests a prognostic and predictive significance of LAG3 methylation in melanoma. Our results give insight in the tumor cell-intrinsic transcriptional regulation of LAG3 in melanoma. In perspective, our results might pave the way for investigating LAG3 methylation as a predictive biomarker for response to anti-LAG3 immune checkpoint blockage.

Funding

A full list of funding bodies that contributed to this study can be found in the Acknowledgements section.

Abstract LB-216: Frequent oncogenic tyrosine kinase gene fusions in supratentorial glioblastomas of young children

Glioblastoma in infancy and early childhood is characterized by a more favorable outcome compared to older children. We have shown in previous studies that these tumors are characterized by a stable genome. The occurrence of tyrosine kinase gene fusions in glioblastomas of infancy may represent therapeutic targets. 50 glioblastomas (GBM) with supratentorial location occurring in children younger than four years were retrieved from the archives of the Brain Tumor Reference Center, Institute of Neuropathology, University of Bonn, Germany. DNA and RNA were extracted from FFPE tumor samples. Gene fusions were identified on the DNA level by FISH using break-apart probes for ALK, NTRK1, -2, -3, ROS1 and MET and Molecular Inversion Probe (MIP) methodology. For the detection of fusions on the RNA level, targeted RNA sequencing was performed as well as Nanostring-based detection with probes specific for recurrent fusions. 37 supratentorial GBM occurred in the first year of life, 13 GBM between one and four years. 18 cases showed fusions of ALK to different fusion partners; all occurred in the first year of life (18/37 cases, 48.6%). Fusions of ROS1 were found in 5, MET in 3, NTRK1, -2, -3 in 10 cases. 12 cases showed no and two novel fusions. The different methods led to comparable results. Only recurrent fusions with known fusion partners were detectable with probes designed for the fusion sequence, and library construction for targeted RNA sequencing was not successful in a fraction of cases. Break-apart FISH led to reliable results on the next day, and MIP technology represented the most sensitive method for analysis of FFPE samples. Gene fusions involving the tyrosine kinase genes ALK, MET, ROS1 and NTRK1, -2, -3 occurred in 72% of glioblastomas of children younger than four years; the most frequent were ALK fusions occurring in infant GBM. DNA based MIP technology represented the most robust and sensitive assay.

Citation Format: Torsten Pietsch, Christian Vokuhl, Gerrit H. Gielen, Andre O. von Bueren, Evelyn Dörner, Glen Kristiansen, Andreas Waha, Christof Kramm. Frequent oncogenic tyrosine kinase gene fusions in supratentorial glioblastomas of young children [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr LB-216.

Challenging Implications of Chronic Lymphocytic Inflammation with Pontine Perivascular Enhancement Responsive to Steroids Syndrome with an Atypical Presentation: Report of Two Cases

BACKGROUND

Chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids (CLIPPERS) is an increasingly recognized neuroinflammatory syndrome that predominantly affects the pontine and cerebellar brain structures. Characteristically, patients will develop glucocorticoid-responsive brainstem disorders, demonstrate pontocerebellar contrast enhancement on magnetic resonance imaging (MRI), and exhibit an angiocentric, lymphocytic infiltrate in brain biopsies. We have presented and discussed 2 novel and challenging cases of CLIPPERS syndrome to highlight the clinical and radiological diversity of the syndrome.

CASE DESCRIPTION

The first case was of a 66-year-old male patient who had presented with dizziness, headaches, gait disturbances, mild cognitive impairment, and visual field loss to the left side. MRI revealed 1 cerebellar and 2 occipital contrast-enhancing lesions that were suspicious for intracerebral metastases. The second case was of a 53-year-old male patient who had presented with temporal lobe epilepsy, anomic aphasia, and mild cognitive impairment. MRI demonstrated 4 contrast-enhancing lesions in the pons, temporal lobe, and thalamus that were suspicious for intracerebral lymphoma. Because of the radiological presentation, neoplastic disease was the most plausible diagnosis for both patients. However, repeated biopsies ruled out tumor manifestation, and the findings were finally consistent with CLIPPERS syndrome. The significant and long-lasting response to immunosuppressive treatment confirmed the diagnosis.

CONCLUSIONS

In both cases, the characteristics of CLIPPERS syndrome imitated malignant tumor growth. This scenario can be challenging to clinicians and necessitates inclusion of this neuroinflammatory syndrome in the differential diagnosis of neuro-oncological disease.

Prognostic and predictive value of PD-L2 DNA methylation and mRNA expression in melanoma

BACKGROUND

PD-L1 (programmed cell death 1 ligand 1) expression in melanoma has been associated with a better response to anti-PD-1 (programmed cell death 1) therapy. However, patients with PD-L1-negative melanomas can respond to anti-PD-1 blockade, suggesting that the other PD-1 ligand, PD-L2 (programmed cell death 1 ligand 2), might also be relevant for efficacy of PD-1 inhibition. We investigated PD-L2 expression and methylation as a prognostic and predictive biomarker in melanoma.

METHODS

DNA methylation at five CpG loci and gene expression of PD-L2 were evaluated with regard to survival in 470 melanomas from The Cancer Genome Atlas. PD-L2 promoter methylation in correlation with PD-L2 mRNA and protein expression was analyzed in human melanoma cell lines. Prognostic and predictive value of PD-L2 methylation was validated using quantitative methylation-specific PCR in a multicenter cohort of 129 melanoma patients receiving anti-PD-1 therapy. mRNA sequencing data of 121 melanoma patients receiving anti-PD-1 therapy provided by Liu et al. were analyzed for PD-L2 mRNA expression.

RESULTS

We found significant correlations between PD-L2 methylation and mRNA expression levels in melanoma tissues and cell lines. Interferon-γ inducible PD-L2 protein expression correlated with PD-L2 promoter methylation in melanoma cells. PD-L2 DNA promoter hypomethylation and high mRNA expression were found to be strong predictors of prolonged overall survival. In pre-treatment melanoma samples from patients receiving anti-PD-1 therapy, low PD-L2 DNA methylation and high PD-L2 mRNA expression predicted longer progression-free survival.

CONCLUSION

PD-L2 expression seems to be regulated via DNA promoter methylation. PD-L2 DNA methylation and mRNA expression may predict progression-free survival in melanoma patients receiving anti-PD-1 immunotherapy. Assessment of PD-L2 should be included in further clinical trials with anti-PD-1 antibodies.

PDGRFB mutation-associated myofibromatosis: Response to targeted therapy with imatinib

Heterozygous activating mutations in platelet-derived growth factor receptor B (PDGFRB) have been recently identified as a cause of autosomal-dominant infantile myofibromatosis. We describe a 36-year-old man with PDGFRB c.1681C>T (p.R561C) mutation. Upon progressive disease, the patient received treatment with imatinib and showed a remarkable response with remission of multiple lesions after 12 months. This is the first report of an adult patient with PDGFRB c.1681C>T mutation treated with imatinib.

Longitudinal heterogeneity in glioblastoma: moving targets in recurrent versus primary tumors

Background

Molecularly targeted therapies using receptor inhibitors, small molecules or monoclonal antibodies are routinely applied in oncology. Verification of target expression should be mandatory prior to initiation of therapy, yet, determining the expression status is most challenging in recurrent glioblastoma (GBM) where most patients are not eligible for second-line surgery. Because very little is known on the consistency of expression along the clinical course we here explored common drug targets in paired primary vs. recurrent GBM tissue samples.

Methods

Paired surgical tissue samples were derived from a homogeneously treated cohort of 34 GBM patients. All patients received radiotherapy and temozolomide chemotherapy. Verification of common drug targets included immunohistological analysis of PDGFR-β, FGFR-2, FGFR-3, and mTOR-pathway component (phospho-mTOR^Ser2448) as well as molecular, MLPA-based analysis of specific copy number aberrations at the gene loci of ALK, PDGFRA, VEGFR2/KDR, EGFR, MET, and FGFR1.

Results

Paired tumor tissue exhibited significant changes of expression in 9 of the 10 investigated druggable targets (90%). Only one target (FGFR1) was found “unchanged”, since dissimilar expression was observed in only one of the 34 paired tumor tissue samples. All other targets were variably expressed with an 18–56% discordance rate between primary and recurrent tissue.

Conclusions

The high incidence of dissimilar target expression status in clinical samples from primary vs. recurrent GBM suggests clinically relevant heterogeneity along the course of disease. Molecular target expression, as determined at primary diagnosis, may not necessarily present rational treatment clues for the clinical care of recurrent GBM. Further studies need to analyze the therapeutic impact of longitudinal heterogeneity in GBM.

Electronic supplementary material

The online version of this article (10.1186/s12967-019-1846-y) contains supplementary material, which is available to authorized users.

Diffuse high-grade gliomas with H3 K27M mutations carry a dismal prognosis independent of tumor location

Background

The novel entity of "diffuse midline glioma, H3 K27M-mutant" has been defined in the 2016 revision of the World Health Organization (WHO) classification of tumors of the central nervous system (CNS). Tumors of this entity arise in CNS midline structures of predominantly pediatric patients and are associated with an overall dismal prognosis. They are defined by K27M mutations in H3F3A or HIST1H3B/C, encoding for histone 3 variants H3.3 and H3.1, respectively, which are considered hallmark events driving gliomagenesis.

Methods

Here, we characterized 85 centrally reviewed diffuse gliomas on midline locations enrolled in the nationwide pediatric German HIT-HGG registry regarding tumor site, histone 3 mutational status, WHO grade, age, sex, and extent of tumor resection.

Results

We found 56 H3.3 K27M-mutant tumors (66%), 6 H3.1 K27M-mutant tumors (7%), and 23 H3-wildtype tumors (27%). H3 K27M-mutant gliomas shared an aggressive clinical course independent of their anatomic location. Multivariate regression analysis confirmed the significant impact of the H3 K27M mutation as the only independent parameter predictive of overall survival (P = 0.009). In H3 K27M-mutant tumors, neither anatomic midline location nor histopathological grading nor extent of tumor resection had an influence on survival.

Conclusion

These results substantiate the clinical significance of considering diffuse midline glioma, H3 K27M-mutant, as a distinct entity corresponding to WHO grade IV, carrying a universally fatal prognosis.

Correction to: A suggestion to introduce the diagnosis of "diffuse midline glioma of the pons, H3 K27 wildtype (WHO grade IV)"

The citation of the original publication in PubMed contains an error. The seventh author name is wrongly cited.

Recurrent pseudoprogression in isocitrate dehydrogenase 1 mutant glioblastoma

In a subset of glioblastoma (GBM) patients, the differentiation between tumor progression and tumor pseudoprogression (PsP) is challenging. This case describes a male patient suffering from isocitrate dehydrogenase 1 (IDH1) mutant GBM who demonstrated an increasing contrast-enhancing (CE) lesion on a cranial magnetic resonance imaging (cMRI) scan 8 months after radiochemotherapy. In accordance with the response assessment in neuro-oncology (RANO) criteria, the cMRI lesion was classified as recurrent tumor, although ¹⁸F-fluoroethyl-L-tyrosine positron emission tomography (¹⁸F-FET-PET) did not indicate vital tumor tissue. The patient underwent re-surgery but histopathology only revealed reactive and necrotic tissue, consistent with PsP. Nine weeks after complete resection of the CE lesion, a new lesion emerged that later regressed in the follow-up cMRI scans, thereby retrospectively establishing the diagnosis of recurrent PsP.

Clinical, Radiologic, Pathologic, and Molecular Characteristics of Long-Term Survivors of Diffuse Intrinsic Pontine Glioma (DIPG): A Collaborative Report From the International and European Society for Pediatric Oncology DIPG Registries

Purpose Diffuse intrinsic pontine glioma (DIPG) is a brainstem malignancy with a median survival of < 1 year. The International and European Society for Pediatric Oncology DIPG Registries collaborated to compare clinical, radiologic, and histomolecular characteristics between short-term survivors (STSs) and long-term survivors (LTSs). Materials and Methods Data abstracted from registry databases included patients from North America, Australia, Germany, Austria, Switzerland, the Netherlands, Italy, France, the United Kingdom, and Croatia. Results Among 1,130 pediatric and young adults with radiographically confirmed DIPG, 122 (11%) were excluded. Of the 1,008 remaining patients, 101 (10%) were LTSs (survival ≥ 2 years). Median survival time was 11 months (interquartile range, 7.5 to 16 months), and 1-, 2-, 3-, 4-, and 5-year survival rates were 42.3% (95% CI, 38.1% to 44.1%), 9.6% (95% CI, 7.8% to 11.3%), 4.3% (95% CI, 3.2% to 5.8%), 3.2% (95% CI, 2.4% to 4.6%), and 2.2% (95% CI, 1.4% to 3.4%), respectively. LTSs, compared with STSs, more commonly presented at age < 3 or > 10 years (11% v 3% and 33% v 23%, respectively; P < .001) and with longer symptom duration ( P < .001). STSs, compared with LTSs, more commonly presented with cranial nerve palsy (83% v 73%, respectively; P = .008), ring enhancement (38% v 23%, respectively; P = .007), necrosis (42% v 26%, respectively; P = .009), and extrapontine extension (92% v 86%, respectively; P = .04). LTSs more commonly received systemic therapy at diagnosis (88% v 75% for STSs; P = .005). Biopsies and autopsies were performed in 299 patients (30%) and 77 patients (10%), respectively; 181 tumors (48%) were molecularly characterized. LTSs were more likely to harbor a HIST1H3B mutation (odds ratio, 1.28; 95% CI, 1.1 to 1.5; P = .002). Conclusion We report clinical, radiologic, and molecular factors that correlate with survival in children and young adults with DIPG, which are important for risk stratification in future clinical trials.

The ERICA Score: An MR Imaging-based Visual Scoring System for the Assessment of Entorhinal Cortex Atrophy in Alzheimer Disease

Purpose To establish and evaluate a visual score focused on entorhinal cortex atrophy (ERICA), as the entorhinal cortex is one of the first brain structures affected in Alzheimer disease (AD). Materials and Methods In this retrospective study, ERICA was visually evaluated with magnetic resonance imaging (2009-2016). First, a four-point ERICA score was developed by using data in 48 consecutive subjects (20 patients with AD and 28 control subjects). Then, in the main analysis, ERICA and the standard medial temporal lobe atrophy (MTA) scores were determined in an independent cohort of 60 patients suspected of having AD (mean age, 69.4 years; range, 46-86 years) and in 60 age-matched patients with subjective cognitive decline (SCD) (mean age, 72.4 years; range 50-87 years). Score performances were evaluated with κ statistics, receiver operating characteristic analysis, t tests, and analysis of variance according to the Standards for Reporting of Diagnostic Accuracy Studies. Results Patients with AD had higher MTA scores (mean, 2.13) and ERICA scores (mean, 2.05) than patients with SCD (P < .001). An ERICA score of 2 or greater achieved a higher diagnostic accuracy (91%) than the MTA score (74%), with a sensitivity of 83% versus 57% and a specificity of 98% versus 92% in discriminating dementia caused by AD from SCD (P < .001). The ERICA score was correlated with amyloid β 42/40 ratio (ρ = -0.54, P < .001) and with cerebrospinal fluid tau (ρ = 0.35, P = .001) and p-tau (ρ = 0.31, P = .004). In multivariable linear regression analysis, ERICA was associated with verbal learning and recall (β = -.40 and -.41), nonverbal recall (β = -.28), and cued recall (β = -.41, P ≤ .002 for all). Conclusion An ERICA score of 2 or greater indicates probable AD with high diagnostic accuracy. ^© RSNA, 2018 Online supplemental material is available for this article.

The immediate and short-term effects of bilateral intrahippocampal depth electrodes on verbal memory

In contrast to previous studies, Ljung et al. provide evidence of permanent cognitive consequences of bilateral intrahippocampal depth electrodes for verbal memory in patients who were not operated or operated in the right temporal lobe. Stimulated by this, we provide historical confirmatory and supplementary evidence of the detrimental effect of bilateral depth electrodes implanted along the longitudinal axis of the hippocampus on verbal learning and especially on delayed verbal memory and recognition performance. This is demonstrated in 31 patients with memory assessments before implantation, after explantation, and 3 months later after left/right temporal lobe surgery. After surgery, significant recovery from postimplantation impairment is found in right temporal patients. Left temporal resection patients stay on the level seen after implantation and do not recover. Surgery, however, has its own effects in addition to the implantation. Intracranial electrodes for electroencephalographic monitoring or electrical stimulation are commonly and increasingly used for diagnosis or treatment in pharmacoresistant epilepsies. Thus, the monitoring of invasive stereotactic approaches is recommended to find safe procedures for the patients. In response to the findings, we restricted indications and used different implantation schemes, different trajectories, and targets to minimize the risk of additional damage.

Meningioma assessment: Kinetic parameters in dynamic contrast-enhanced MRI appear independent from microvascular anatomy and VEGF expression

BACKGROUND AND PURPOSE

Kinetic parameters of T1-weighted dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) are considered to be influenced by microvessel environment. This study was performed to explore the extent of this association for meningiomas.

MATERIALS AND METHODS

DCE-MRI kinetic parameters (contrast agent transfer constants K^trans and k_ep, volume fractions v_p and v_e) were determined in pre-operative 3T MRI of meningioma patients for later biopsy sites (19 patients; 15 WHO I^o, no previous radiation, and 4 WHO III^o pre-radiated recurrent tumors). Sixty-three navigated biopsies were consecutively retrieved. Biopsies were immunohistochemically investigated with endothelial marker CD34 and VEGF antibodies, stratified in a total of 4383 analysis units and computationally assessed for VEGF expression and vascular parameters (vessel density, vessel quantity, vascular fraction within tissue [vascular area ratio], vessel wall thickness). Derivability of kinetic parameters from VEGF expression or microvascularization was determined by mixed linear regression analysis. Tissue kinetic and microvascular parameters were tested for their capacity to identify the radiation status in a subanalysis.

RESULTS

Kinetic parameters were neither significantly related to the corresponding microvascular parameters nor to tissue VEGF expression. There was no significant association between microvessel density and its presumed correlate v_p (P=0.07). The subgroup analysis of high-grade radiated meningiomas showed a significantly reduced microvascular density (AUC 0.91; P<0.0001) and smaller total vascular fraction (AUC 0.73; P=0.01).

CONCLUSIONS

In meningioma, DCE-MRI kinetic parameters neither allow for a reliable prediction of tumor microvascularization, nor for a prediction of VEGF expression. Kinetic parameters seem to be determined from different independent factors.

Haematological malignancies following temozolomide treatment for paediatric high-grade glioma

BACKGROUND

Temozolomide (TMZ) is widely used in high-grade glioma (HGG). There is a major concern of treatment-induced secondary haematological malignancies (SHMs). Due to the poor overall survival of HGG patients, the true incidence is yet elusive. Thus, the aim of this study was to determine the risk of SHMs following TMZ in paediatric HGG.

METHODS

We analysed 487 patients from the HIT-HGG database of the German-speaking Society of Pediatric Oncology and Hematology with follow up beyond 1 year.

RESULTS

The incidence of SHM was 7.7 ± 3.2% at 10 years. No SHM occurred in 194 patients after first-line TMZ therapy, but four out of 131 patients treated with TMZ for relapse following first-line multiagent chemotherapy experienced SHM (20% at 10 years; p = 0.041). SHMs occurred in two out of 162 patients who underwent multiagent chemotherapy without TMZ (4.1% at 10 years). Gender, patient age and acute haematological toxicity during treatment did not affect the incidence of SHMs.

CONCLUSION

Data of our cohort do not indicate an increased risk of SHM following TMZ treatment when compared to previous chemotherapy regimen. However, if TMZ is administered as a second-line treatment following conventional chemotherapy regimen, the risk might be disproportionately increasing.

Biopsy targeting with dynamic contrast-enhanced versus standard neuronavigation MRI in glioma: a prospective double-blinded evaluation of selection benefits

Current biopsy planning based on contrast-enhanced T1W (CET1W) or FLAIR sequences frequently delivers biopsy samples that are not in concordance with the gross tumor diagnosis. This study investigates whether the quantitative information of transfer constant K^trans maps derived from T1W dynamic contrast-enhanced MRI (DCE-MRI) can help enhance the quality of biopsy target selection in glioma. 28 patients with suspected glioma received MRI including DCE-MRI and a standard neuronavigation protocol of 3D FLAIR- and CET1W data sets (0.1 mmol/kg gadobutrol) at 3.0 T. After exclusion of five cases with no K^trans-elevation, 2-6 biopsy targets were independently selected by a neurosurgeon (samples based on standard imaging) and a neuroradiologist (samples based on kinetic parameter K^trans) per case and tissue samples corresponding to these targets were collected by a separate independent neurosurgeon. Standard technique and K^trans-based samples were rated for diagnostic concordance with the gross tumor resection reference diagnosis (67 WHO IV; 24 WHO III and II) by a neuropathologist blinded for selection mode. K^trans-based sample targets differed from standard technique sample targets in 90/91 cases. More K^trans-based than standard imaging-based samples could be extracted. Diagnoses from K^trans-based samples were more frequently concordant with the reference gross tumor diagnoses than those from standard imaging-based samples (WHO IV: 30/39 vs. 11/20; p = 0.08; WHO III/II: 12/13 vs. 6/11; p = 0.06). In 4/5 non-contrast-enhancing gliomas, K^trans-based selection revealed significantly more accurate samples than standard technique sample-selection (10/12 vs. 2/8 samples; p = 0.02). If K^trans elevation is present, K^trans-based biopsy targeting provides significantly more diagnostic tissue samples in non-contrast-enhancing glioma than selection based on CET1W and FLAIR-weighted images alone.

Intravoxel incoherent motion MRI in the brain: Impact of the fitting model on perfusion fraction and lesion differentiability

PURPOSE

To investigate the effect of the choice of the curve-fitting model on the perfusion fraction (f_IVIM ) with regard to tissue type characterization, correlation with microvascular anatomy, and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) parameters. Several curve-fitting models coexist in intravoxel incoherent motion (IVIM) MRI to derive the (f_IVIM ).

MATERIALS AND METHODS

In all, 29 patients with brain lesions (12 gliomas, 11 meningiomas, three metastases, two gliotic scars, one multiple sclerosis) underwent IVIM-MRI (32 b-values, 0 to 2000 s/mm² ) at 3T. f_IVIM was determined by classic monoexponential, biexponential, and a novel nonnegative least squares (NNLS) fitting in 352 regions of interest (lesion-containing and normal-appearing tissue) and tested their correlation with DCE-MRI kinetic parameters and microvascular anatomy derived from 57 region of interest (ROI)-based biopsies and their capacities to differentiate histologically different lesions.

RESULTS

f_IVIM differed significantly between all three models and all tissue types (monoexponential confidence interval in percent [CI 3.4-3.8]; biexponential [CI 11.21-12.45]; NNLS [CI 2.06-2.60]; all P < 0.001). For all models an increase in f_IVIM was associated with a shift to larger vessels and higher vessel area / tissue area ratio (regression coefficient 0.07-0.52; P = 0.04-0.001). Correlation with kinetic parameters derived from DCE-MRI was usually not significant. Only biexponential fitting allowed differentiation of both gliosis from edema and high- from low-grade glioma (both P < 0.001).

CONCLUSION

The curve-fitting model has an important impact on f_IVIM and its capacity to differentiate tissues. f_IVIM may possibly be used to assess microvascular anatomy and is weakly correlated with DCE-MRI kinetic parameters.

LEVEL OF EVIDENCE

2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2017;46:1187-1199.

MTSS1 is epigenetically regulated in glioma cells and inhibits glioma cell motility

Epigenetic silencing by DNA methylation in brain tumors has been reported for many genes, however, their function on pathogenesis needs to be evaluated. We investigated the MTSS1 gene, identified as hypermethylated by differential methylation hybridization (DMH). Fifty-nine glioma tissue samples and seven glioma cell lines were examined for hypermethylation of the MTSS1 promotor, MTSS1 expression levels and gene dosage. GBM cell lines were treated with demethylating agents and interrogated for functional consequences of MTSS1 expression after transient transfection. Hypermethylation was significantly associated with IDH1/2 mutation. Comparative SNP analysis indicates higher incidence of loss of heterozygosity of MTSS1 in anaplastic astrocytomas and secondary glioblastomas as well as hypermethylation of the remaining allele. Reversal of promoter hypermethylation results in an increased MTSS1 expression. Cell motility was significantly inhibited by MTSS1 overexpression without influencing cell growth or apoptosis. Immunofluorescence analysis of MTSS1 in human astrocytes indicates co-localization with actin filaments. MTSS1 is down-regulated by DNA methylation in glioblastoma cell lines and is part of the G-CIMP phenotype in primary glioma tissues. Our data on normal astrocytes suggest a function of MTSS1 at focal contact structures with an impact on migratory capacity but no influence on apoptosis or cellular proliferation.

Altered splicing leads to reduced activation of CPEB3 in high-grade gliomas

Cytoplasmic polyadenylation element binding proteins (CPEBs) are auxiliary translational factors that associate with consensus sequences present in 3'UTRs of mRNAs, thereby activating or repressing their translation. Knowing that CPEBs are players in cell cycle regulation and cellular senescence prompted us to investigate their contribution to the molecular pathology of gliomas-most frequent of intracranial tumors found in humans. To this end, we performed methylation analyses in the promoter regions of CPEB1-4 and identified the CPEB1 gene to be hypermethylated in tumor samples. Decreased expression of CPEB1 protein in gliomas correlated with the rising grade of tumor malignancy. Abundant expression of CPEBs2-4 was observed in several glioma specimens. Interestingly, expression of CPEB3 positively correlated with tumor progression and malignancy but negatively correlated with protein phosphorylation in the alternatively spliced region. Our data suggest that loss of CPEB3 activity in high-grade gliomas is caused by expression of alternatively spliced variants lacking the B-region that overlaps with the kinase recognition site. We conclude that deregulation of CPEB proteins may be a frequent phenomenon in gliomas and occurs on the level of transcription involving epigenetic mechanism as well as on the level of mRNA splicing, which generates isoforms with compromised biological properties.

Phase I trial of dovitinib (TKI258) in recurrent glioblastoma

PURPOSE

Dovitinib (TKI258) is an oral multi-tyrosine kinase inhibitor of FGFR, VEGFR, PDGFR β, and c-Kit. Since dovitinib is able to cross the blood-brain barrier and targets brain tumor-relevant pathways, we conducted a phase I trial to demonstrate its safety in recurrent glioblastoma (GBM).

PATIENTS AND METHODS

Patients with first or second GBM recurrence started treatment with the maximal tolerated dose (MTD) previously established in systemic cancer patients (500 mg/d, 5 days on/2 days off). A modified 3 + 3 design in three cohorts (500, 400, 300 mg) was used.

RESULTS

Twelve patients were enrolled. Seventy-two adverse events (AEs) occurred and 16.7 % of AEs were classified as ≥CTC grade 3 toxicity, mainly including hepatotoxicity and hematotoxicity. Only one out of six patients of the 300-mg cohort showed grade 3 toxicity. The PFS-6 rate was 16.7 %, and it was not associated with detection of the FGFR-TACC gene fusion in the tumor.

CONCLUSION

Dovitinib is safe in patients with recurrent GBM and showed efficacy in only some patients unselected for target expression. The recommended phase II dose of 300 mg would be substantially lower than the recently established MTD in systemic cancer patients. Further personalized trials are recommended.

Genetic Analysis of Diffuse High-Grade Astrocytomas in Infancy Defines a Novel Molecular Entity

Pediatric high-grade gliomas are considered to be different when compared to adult high-grade gliomas in their pathogenesis and biological behavior. Recently, common genetic alterations, including mutations in the H3F3A/ATRX/DAXX pathway, have been described in approximately 30% of the pediatric cases. However, only few cases of infant high-grade gliomas have been analyzed so far. We investigated the molecular features of 35 infants with diffuse high-grade astrocytomas, including 8 anaplastic astrocytomas [World Health Organization (WHO) grade III] and 27 glioblastomas (WHO grade IV) by immunohistochemistry, multiplex ligation probe-dependent amplification (MLPA), pyrosequencing of glioma-associated genes and molecular inversion probe (MIP) assay. MIP and MLPA analyses showed that chromosomal alterations are significantly less frequent in infants compared with high-grade gliomas in older children and adults. We only identified H3F3A K27M in 2 of 34 cases (5.9%), with both tumors located in the posterior fossa. PDGFRA amplifications were absent, and CDKN2A loss could be observed only in two cases. Conversely, 1q gain (22.7%) and 6q loss (18.2%) were identified in a subgroup of tumors. Loss of SNORD located on chromosome 14q32 was observed in 27.3% of the infant tumors, a focal copy number change not previously described in gliomas. Our findings indicate that infant high-grade gliomas appear to represent a distinct genetic entity suggesting a different pathogenesis and biological behavior.

Karyopherin a2 and chromosome region maintenance protein 1 expression in meningiomas: novel biomarkers for recurrence and malignant progression

The karyopherin protein family comprises importins and exportins which are nucleocytoplasmic shuttling receptors. Increased levels of karyopherin a2 and chromosome region maintenance protein 1 correlate with a higher WHO grade and a poorer prognosis in patients with infiltrative astrocytomas. The aim of this study was to evaluate representative members of importins and exportins (i.e. karyopherin a2 and chromosome region maintenance protein 1) as novel biomarkers for meningiomas of WHO grades I-III. We semiquantitatively analyzed nuclear expression of karyopherin a2, chromosome region maintenance protein 1 and the MIB1 labeling index using immunohistochemistry in 108 primary (44 meningiomas WHO grade I, 48 meningiomas WHO grade II, 16 meningiomas WHO grade III) and 13 recurrent meningiomas. Statistical analysis was performed using standard techniques. Karyopherin a2 (p < 0.001) and chromosome region maintenance protein 1 (p = 0.002) expression correlated significantly with the histological grade. Karyopherin a2 expression correlated with proliferative activity as assessed by the MIB1 index (p < 0.001). Recurrent tumors expressed significantly higher levels of karyopherin a2 (p = 0.045) when compared to primary growths. Multivariate analysis of the overall series as well as of patients with atypical meningiomas identified higher karyopherin a2 (≥ 5 vs. <5%) and chromosome region maintenance protein 1 (≥ 60 vs. 60%) expression as independent predictors of tumor recurrence. Karyopherin a2 and chromosome region maintenance protein 1 expression may have potential as novel biomarkers for meningiomas.

Recent aspects of classification and epidemiology of epilepsy-associated tumors

Epileptic seizures are frequent manifestations of brain tumors. However, biopsy specimens of patients who undergo neurosurgical removal of circumscribed foci to control chronic recurrent pharmacoresistant seizures often reveal tumor entities that are rare in general brain tumor series. The spectrum of these "long-term epilepsy-associated neoplasms" comprises highly differentiated glial and glioneuronal tumors that show a benign biologic behavior and clinical course, and that rarely relapse. Several entities are well recognizable on the basis of histopathologic and immunohistochemical characteristics. An intriguing functional aspect of these tumors, sometimes collectively referred to as "epileptomas," is their prominent epileptogenicity, which may represent a clinical feature indicating rather than causing the generally benign biologic behavior of these tumors. A frequent feature of respective neoplasms is their coincidence with dysplastic lesions in the vicinity of the tumor itself. The recent advent of new molecular markers, including genomic alterations leading to activation of the protooncogene BRAF and impaired function of isocitrate dehydrogenase (IDH1), provides excellent new tools in the differential diagnosis of low grade brain tumors, and provides intriguing implications to further develop the pathogenetic concepts of these neoplasms. Despite this progress, a number of tumors from patients with chronic epilepsy show combinations of cytologic, histologic, and immunohistochemical characteristics that challenge the current neuropathologic classification schemes. Attempts are currently ongoing to develop further classification schemes.

Cerebellar location may predict an unfavourable prognosis in paediatric high-grade glioma

Background:

High-grade glioma (HGG) of the cerebellum accounts for only 5% of paediatric HGG. Since little is known about these tumours, the present study aimed at their further characterisation.

Methods:

Twenty-nine paediatric patients with centrally reviewed cerebellar HGG were identified from the HIT-GBM/HIT-HGG database. Clinical and epidemiological data were compared with those of 180 paediatric patients with cortical HGG.

Results:

Patients with cerebellar tumours were younger (median age of 7.6 vs 11.7 years, P=0.028), but both groups did not differ significantly with regard to gender, tumour predisposing syndromes, secondary HGG, primary metastasis, tumour grading, extent of tumour resection, chemotherapy regimen, or radiotherapy. Except for an increased incidence of anaplastic pilocytic astrocytoma (APA) in the cerebellar subset (20.7% vs 3.3% P<0.001), histological entities were similarly distributed in both groups. As expected, tumour grading had a prognostic relevance on survival. Compared with cortical HGG, overall survival in the cerebellar location was significantly worse (median overall survival: 0.92±0.02 vs 2.03±0.32 years; P=0.0064), and tumour location in the cerebellum had an independent poor prognostic significance as shown by Cox-regression analysis (P=0.019).

Conclusion:

High-grade glioma represents a group of tumours with an obviously site-specific heterogeneity associated with a worse survival in cerebellar location.

H3F3A K27M mutation in pediatric CNS tumors: a marker for diffuse high-grade astrocytomas

Brain tumors are one of the most common childhood malignancies. Diffuse high-grade gliomas represent approximately 10% of pediatric brain tumors. Exon sequencing has identified a mutation in K27M of the histone H3.3 gene (H3F3A K27M and G34R/V) in about 20% of pediatric glioblastomas, but it remains to be seen whether these mutations can be considered specific for pediatric diffuse high-grade astrocytomas or also occur in other pediatric brain tumors. We performed a pyrosequencing-based analysis for the identification of H3F3A codon 27 and codon 34 mutations in 338 pediatric brain tumors. The K27M mutation occurred in 35 of 129 glioblastomas (27.1%) and in 5 of 28 (17.9%) anaplastic astrocytomas. None of the other tumor entities showed H3F3A K27M mutation. Because H3F3A K27M mutations occur exclusively in pediatric diffuse high-grade astrocytomas, analysis of codon 27 mutational status could be useful in the differential diagnosis of these neoplasms.

H3.3 G34R mutations in pediatric primitive neuroectodermal tumors of central nervous system (CNS-PNET) and pediatric glioblastomas: possible diagnostic and therapeutic implications?

Pediatric glioblastomas recently have been exon sequenced with evidence that approximately 30 % of cases harbour mutations of the histone H3.3 gene. Although studies to determinate their role in risk stratification are on-going, it remains to be determined whether H3.3 mutations could be found in other tumors such as pediatric primitive neuroectodermal tumors of the central nervous system (CNS-PNETs) and whether the presence of H3.3 mutations in glioblastomas could be used as diagnostic tool in their differential diagnosis with CNS-PNETs. We performed a large mutational pyrosequencing-based screening on 123 pediatric glioblastomas and 33 CNS-PNET. The analysis revealed that 39/123 (31.7 %) glioblastomas carry H3.3 mutations. The K27M (AAG → ATG, lysine → methionine) mutation was found in 33 glioblastomas (26 %); the G34R (GGG → AGG, glycine → arginine) was observed in 6 glioblastomas (5.5 %). However, we also identified 4 of 33 cases (11 %) of CNS-PNETs harbouring a H3.3 G34R mutation. Multiplex ligation-dependent probe amplification analysis revealed PDGFR-alpha amplification and EGFR gain in two cases and N-Myc amplification in one case of H3.3 G34R mutated CNS-PNET. None of H3.3 mutated tumors presented a CDKN2A loss. In conclusion, because pediatric patients with glioblastoma and CNS-PNET are treated according to different therapeutic protocols, these findings may raise further concerns about the reliability of the histological diagnosis in the case of an undifferentiated brain tumor harbouring G34R H3.3 mutation. In this view, additional studies are needed to determine whether H3.3 G34 mutated CNS-PNET/glioblastomas may represent a defined tumor subtype.