Long-Term Follow-up of Multinodular and Vacuolating Neuronal Tumors and Implications for Surveillance Imaging

BACKGROUND AND PURPOSE

Most multinodular and vacuolating neuronal tumors (MVNTs) are diagnosed and followed radiologically without any change across time. There are no surveillance guidelines or quantitative volumetric assessments of these tumors. We evaluated MVNT volumes during long follow-up periods using segmentation tools with the aim of quantitative assessment.

MATERIALS AND METHODS

All patients with MVNTs in a brain MR imaging report in our system were reviewed. Patients with only 1 brain MR imaging or in whom MVNT was not clearly the most likely diagnosis were excluded. All MVNTs were manually segmented. For all follow-up examinations, absolute and percentage volume change from immediately prior and initial examinations were calculated.

RESULTS

Forty-eight patients (32 women; median age, 50.5 years at first scanning) underwent 158 brain MRIs. The median duration between the first and last scan was 15.6 months (interquartile range, 5.7-29.6 months; maximum, 6.4 years) and between consecutive scans, it was 6.7 months (interquartile range, 3.3-12.4 months; maximum, 4.9 years). Pearson correlation coefficients between days since immediately prior scan versus absolute and percentage volume change from immediately prior scan were r = 0.05 (P = .60) and r = 0.07 (P = .45), respectively. For the relationship between days since the first scan versus absolute and percentage volume change from the first scan, values were r = -0.06 (P = .53) and r = -0.04 (P = .67), respectively.

CONCLUSIONS

MVNT segmentation across follow-up brain MR imaging examinations did not demonstrate significant volume differences, suggesting that these tumors do not enlarge with time. Hence, frequent surveillance imaging of newly diagnosed MVNTs may not be necessary.

Artificial-intelligence-based molecular classification of diffuse gliomas using rapid, label-free optical imaging

Molecular classification has transformed the management of brain tumors by enabling more accurate prognostication and personalized treatment. However, timely molecular diagnostic testing for patients with brain tumors is limited, complicating surgical and adjuvant treatment and obstructing clinical trial enrollment. In this study, we developed DeepGlioma, a rapid (<90 seconds), artificial-intelligence-based diagnostic screening system to streamline the molecular diagnosis of diffuse gliomas. DeepGlioma is trained using a multimodal dataset that includes stimulated Raman histology (SRH); a rapid, label-free, non-consumptive, optical imaging method; and large-scale, public genomic data. In a prospective, multicenter, international testing cohort of patients with diffuse glioma (n = 153) who underwent real-time SRH imaging, we demonstrate that DeepGlioma can predict the molecular alterations used by the World Health Organization to define the adult-type diffuse glioma taxonomy (IDH mutation, 1p19q co-deletion and ATRX mutation), achieving a mean molecular classification accuracy of 93.3 ± 1.6%. Our results represent how artificial intelligence and optical histology can be used to provide a rapid and scalable adjunct to wet lab methods for the molecular screening of patients with diffuse glioma.

SURG-24. QUANTITATIVE ANALYSIS OF TUMOR CELL DENSITY AND PROTOPORPHYRIN IX FLOURESCENCE IN GLIOMA PATIENTS USING PAIRED STIMULATED RAMAN HISTOLOGY AND TWO-PHOTON EXCITATION FLUORESCENCE MICROSCOPY

Fluorescence guidance is widely utilized to improve the precision of cancer surgery. 5-aminolevulinic acid, the most widely used fluorophore in glioma surgery, is thought to cause selective accumulation of fluorescent protoporphyrin IX (PpIX) in tumor cells by exploiting pathologic alterations in heme biosynthetic pathways. PpIX-induced fluorescence is highly specific for densely tumor-infiltrated tissue but less effective for visualizing the tumor periphery. To improve clinical detection of PpIX, we developed a microscope to perform paired stimulated Raman histology and two-photon excitation fluorescence microscopy (TPEF) and validated it in 175 fresh, unprocessed core tumor specimens from 75 high-grade glioma patients and three central nervous system lymphoma patients across three institutions. Surprisingly, intracellular PpIX accumulation was observed primarily in cells with histiocytic, rather than neoplastic morphology, and the number of cells concentrating PpIX within the cytoplasm was associated with the abundance of CD163 positive cells (p&lt; 0.02). There was no correlation between the degree of tumor cellularity and the concentration of PpIX across all imaged specimens (R=-0.21). Our findings encourage reconsideration of the existing theory of 5-ALA-induced tumor cell fluorescence in gliomas and demonstrate how 5-ALA and TPEF imaging can provide a window into the immune microenvironment of human gliomas.

CTNI-57. RADIONUCLIDE THERAPY WITH 177LU-DOTATATE (LUTATHERA) IN ADULTS WITH ADVANCED INTRACRANIAL MENINGIOMA - INTERIM ANALYSIS RESULTS OF A SINGLE-ARM, OPEN-LABEL, MULTICENTER PHASE II STUDY

BACKGROUND

While most meningiomas are considered benign tumors, a subset of these tumors are characterized by a more aggressive clinical course and require multimodal treatment. Beyond surgical and radiotherapeutic options, there are no effective medical treatments available. Somatostatin receptor 2 (SSTR2) is expressed by the majority of meningiomas. 177Lu-DOTATATE is a SSTR2-targeting radionuclide that has been successful in neuroendocrine tumors. Here we report the results of the interim analysis of an ongoing clinical trial (NCT03971461) that is evaluating the effect of 177Lu-DOTATATE in treating progressive intracranial meningiomas.

METHODS

In this Simon two-stage design phase II study, adults with advanced intracranial meningiomas received 177Lu-DOTATATE 7.4 GBq (200 mCi) every eight weeks for four doses. 68Ga-DOTATATE PET-MRI was performed before and at the end of treatment. The primary endpoint was progression-free survival at 6 months (PFS-6). Correlative studies evaluated the association of PFS-6, objective response rate, progression-free survival, overall survival with radiographic tumor measurements, 68Ga-DOTATATE uptake on PET-MRI, SSTR2 expression in tumor, and meningioma methylation subclass.

RESULTS

Fourteen patients (F = 11, M = 3) with progressive meningiomas (WHO I = 3, II = 10, III = 1) have been enrolled. Median age was 63.1 (range 49-78) years. All patients previously underwent tumor resection and at least one course of radiation. Treatment with 177Lu-DOTATATE was well tolerated, no treatment-limiting toxicities were observed. Six of 14 patients (42%) achieved PFS-6. Radiographically, all six patients had achieved Stable Disease. A functional alteration of tumoral SSTR2 expression by 68Ga-DOTATATE PET-MR imaging was observed in three patients.

CONCLUSIONS

Treatment with SSTR2-targeting 177Lu-DOTATATE is well tolerated. In this interim analysis, six of 14 patients achieved PFS-6. This exceeds the predefined threshold to continue to stage two of this study. This clinical trial is now open to patient enrollment at two study sites in the US.

NIMG-30. AI-BASED MOLECULAR CLASSIFICATION OF DIFFUSE GLIOMAS USING RAPID, LABEL-FREE OPTICAL HISTOLOGY

INTRODUCTION

Molecular classification has transformed the management of brain tumors by enabling more accurate prognostication and personalized treatment. Access to timely molecular diagnostic testing for brain tumor patients is limited, complicating surgical and adjuvant treatment and obstructing clinical trial enrollment.

OBJECTIVE

We aim to develop a rapid (&lt; 90 seconds), AI-based diagnostic screening system that can provide molecular classification of diffuse gliomas and report its use in a prospective, multicenter, international clinical trial of diffuse glioma patients (n = 153).

METHODS

By combining stimulated Raman histology (SRH), a rapid, label-free, non-consumptive, optical imaging method, and deep learning-based image classification, we are able to predict the molecular genetic features used by the World Health Organization (WHO) to define the adult-type diffuse glioma taxonomy, including IDH-1/2, 1p19q-codeletion, and ATRX loss. We developed a multimodal deep neural network training strategy that uses both SRH images and large-scale, public diffuse glioma genomic data in order to achieve optimal molecular classification performance.

RESULTS

One institution was used for model training (University of Michigan) and four institutions (NYU, UCSF, Medical University of Vienna, and University Hospital Cologne) were included for prospective patient enrollment and model testing. Using our system, called DeepGlioma, we achieved an average molecular genetic classification accuracy of 93.2% and identified the correct diffuse glioma molecular subgroup with 91.5% accuracy. DeepGlioma outperformed conventional IDH1-R132H immunohistochemistry (94.2% versus 91.4% accuracy, respectively) as a first-line molecular diagnostic screening method for diffuse gliomas, detecting canonical and non-canonical IDH mutations with high accuracy.

CONCLUSION

Our results demonstrate how artificial intelligence and optical histology can be used to provide a rapid and scalable alternative to wet lab methods for the molecular diagnosis of brain tumor patients during surgery.

Integrated Molecular-Morphologic Meningioma Classification: A Multicenter Retrospective Analysis, Retrospectively and Prospectively Validated

PURPOSE

Meningiomas are the most frequent primary intracranial tumors. Patient outcome varies widely from benign to highly aggressive, ultimately fatal courses. Reliable identification of risk of progression for individual patients is of pivotal importance. However, only biomarkers for highly aggressive tumors are established (CDKN2A/B and TERT), whereas no molecularly based stratification exists for the broad spectrum of patients with low- and intermediate-risk meningioma.

METHODS

DNA methylation data and copy-number information were generated for 3,031 meningiomas (2,868 patients), and mutation data for 858 samples. DNA methylation subgroups, copy-number variations (CNVs), mutations, and WHO grading were analyzed. Prediction power for outcome was assessed in a retrospective cohort of 514 patients, validated on a retrospective cohort of 184, and on a prospective cohort of 287 multicenter cases.

RESULTS

Both CNV- and methylation family-based subgrouping independently resulted in increased prediction accuracy of risk of recurrence compared with the WHO classification (c-indexes WHO 2016, CNV, and methylation family 0.699, 0.706, and 0.721, respectively). Merging all risk stratification approaches into an integrated molecular-morphologic score resulted in further substantial increase in accuracy (c-index 0.744). This integrated score consistently provided superior accuracy in all three cohorts, significantly outperforming WHO grading (c-index difference P = .005). Besides the overall stratification advantage, the integrated score separates more precisely for risk of progression at the diagnostically challenging interface of WHO grade 1 and grade 2 tumors (hazard ratio 4.34 [2.48-7.57] and 3.34 [1.28-8.72] retrospective and prospective validation cohorts, respectively).

CONCLUSION

Merging these layers of histologic and molecular data into an integrated, three-tiered score significantly improves the precision in meningioma stratification. Implementation into diagnostic routine informs clinical decision making for patients with meningioma on the basis of robust outcome prediction.

NCOG-11. ASSOCIATION OF HYPERGLYCEMIA AND TUMOR SUBCLASS ON SURVIVAL IN IDH-WILDTYPE GLIOBLASTOMA

BACKGROUND

RNA expression and DNA methylation studies have identified different subclasses of isocitrate dehydrogenase (IDH)-wildtype (wt) glioblastoma (GBM). However, the prognostic significance of molecular subclasses is unclear. Although hyperglycemia has been previously associated with worse survival, attempts to lower glucose have yielded mixed responses. The role of hyperglycemia may be confounded by molecular heterogeneity and have different impact in molecularly distinct GBM subclasses.

METHODS

Clinical, laboratory, and molecular data on 89 IDH-wt GBMs profiled by clinical next-generation sequencing and treated with Stupp protocol were reviewed. IDH-wt GBMs were subclassified into RTKI (Proneural), RTKII (Classical) and Mesenchymal subtypes using DNA methylation. Average glucose was calculated by time-weighting plasma glucose measurements between diagnosis and last follow-up.

RESULTS

Patients were stratified into three groups using average glucose: tertile one (&lt; 100mg/dL), tertile two (100-115mg/dL), and tertile three ( &gt; 115mg/dL). Comparison across glucose tertiles revealed no significant differences in Karfnosky Performance Status (KPS), dexamethasone dose, MGMT methylation, or methylation subclass. Overall survival (OS) was not affected by methylation subclass (log-rank p=0.9) but decreased with higher glucose (log-rank p=0.015). Higher glucose tertiles were associated with poorer OS among RTK I (log-rank p=0.08) and mesenchymal tumors (log-rank p=0.05), but not RTK II (log-rank p=0.99). After controlling for age, KPS, dexamethasone dose, and MGMT status, glucose remained significantly associated with survival (adjusted hazard ratio=5.2, p=0.02). DNA methylation clustering did not identify a unique signature associated with high or low glucose levels. Metabolomic analysis of 23 tumors showed minimal variation across metabolites within the cohort with no differences across molecular subclasses.

CONCLUSION

Higher average glucose values were associated with poorer OS in RTKI and Mesenchymal IDH-wt GBM, but not RTKII. There were no discernible epigenetic or metabolomic differences between tumors in different glucose environments, suggesting a potential survival benefit with systemic glucose lowering in selected molecular subtype.

PATH-39. INTEGRATED MOLECULAR-MORPHOLOGICAL MENINGIOMA CLASSIFICATION: A MULTICENTER RETROSPECTIVE ANALYSIS, RETRO- AND PROSPECTIVELY VALIDATED

PURPOSE

Meningiomas are the most frequent primary intracranial tumors. Patient outcome varies widely from cases with benign to highly aggressive, ultimately fatal courses. Reliable identification of risk of progression for the individual patient is of pivotal importance in clinical management. However, only biomarkers for highly aggressive tumors are established at present (CDKN2A/B and TERT), while no molecularly-based stratification exists for the broad spectrum of low- and intermediate-risk meningioma patients.

PATIENTS AND METHODS

DNA methylation data and copy-number information were generated for 3,031 meningiomas of 2,868 individual patients, with mutation data for 858 samples. DNA methylation subgroups, copy-number variations (CNV), mutations and WHO grading were comparatively analyzed. Prediction power for outcome of these parameters was assessed in an initial retrospective cohort of 514 patients, and validated on a retrospective cohort of 184, and on a prospective cohort of 287 multi-center cases, respectively.

RESULTS

Both CNV and methylation family- (MF)-based subgrouping independently resulted in an increase in prediction accuracy of risk of recurrence compared to the WHO classification (c-indexes WHO 2016, CNV, and MF 0.699, 0.706 and 0.721, respectively). Merging all independently powerful risk stratification approaches into an integrated molecular-morphological score resulted in a further, substantial increase in accuracy (c-index 0.744). This integrated score consistently provided superior accuracy in all three cohorts, significantly outperforming WHO grading (c-index difference p=0.005). Besides the overall stratification advantage, the integrated score separates more precisely for risk of progression at the diagnostically challenging interface of WHO grade 1 and grade 2 tumors (HR 4.56 [2.97;7.00], 4.34 [2.48;7.57] and 3.34 [1.28; 8.72] for discovery, retrospective, and prospective validation cohort, respectively).

CONCLUSIONS

Merging these layers of histological and molecular data into an integrated, three-tiered score significantly improves the precision in meningioma stratification. Implementation into diagnostic routine informs clinical decision-making for meningioma patients on the basis of robust outcome prediction.

RADI-19. The Incidence of New Brain Metastases in Patients with Non-Small Cell Lung Cancer Following Discontinuation of Systemic Therapy

Purpose

Patients with non-small cell lung cancer (NSCLC) metastatic to the brain increasingly are living longer due to improvements in systemic therapy and local modalities. The risk of new brain metastases when these patients stop systemic therapy is unknown. Recognizing patterns of new tumor occurrence is necessary to determine the frequency of follow-up and the need for further treatment.

Methods

We included patients in a prospective registry who had non-small cell lung cancer (NSCLC) brain metastases, discontinued systemic therapy for at least 90 days, and underwent active surveillance. 63 patients with 73 off-periods were studied. The risk factors for the development of new tumors were determined using Cox regression and multi-state Markov modeling.

Results

The median time to new brain metastases off systemic therapy was 16.0 months. The probability of developing an additional new tumor at 6, 12, and 18 months was 26%, 40%, and 53%, respectively. There were no additional new tumors 22 months after stopping therapy. Patients who discontinued therapy due to intolerance or progression of the disease and those with mutations in RAS or receptor tyrosine kinase pathways (e.g. KRAS, EGFR) were more likely to develop new tumors (HR: 2.21, 95% CI: 1.25–3.91, p=6.3 x 10^–3; HR: 2.03, 95% CI: 1.09–3.77, p=0.026, respectively).

Conclusion

The rate of new brain metastases from NSCLC in patients off systemic therapy decreases over time and is uncommon 2 years after cessation of cancer therapy. Patients who stop therapy due to toxicity or who have RAS or receptor tyrosine kinase pathway mutations have a higher rate of new metastases and should be followed more closely.

Functional connectivity of the default mode, dorsal attention and fronto-parietal executive control networks in glial tumor patients

PURPOSE

Resting state functional magnetic resonance imaging (rsfMRI) is an emerging tool to explore the functional connectivity of different brain regions. We aimed to assess the disruption of functional connectivity of the Default Mode Network (DMN), Dorsal Attention Network(DAN) and Fronto-Parietal Network (FPN) in patients with glial tumors.

METHODS

rsfMRI data acquired on 3T-MR of treatment-naive glioma patients prospectively recruited (2015-2019) and matched controls from the 1000 functional-connectomes-project were analyzed using the CONN functional toolbox. Seed-Based Connectivity Analysis (SBCA) and Independent Component Analysis (ICA, with 10 to 100 components) were performed to study reliably the three networks of interest.

RESULTS

35 patients with gliomas (17 WHO grade I-II, 18 grade III-IV) and 70 controls were included. Global increased DMN connectivity was consistently found with SBCA and ICA in patients compared to controls (Cluster1: Precuneus, height: p < 10^-6; Cluster2: subcallosum; height: p < 10^-5). However, an area of decreased connectivity was found in the posterior corpus callosum, particularly in high-grade gliomas (height: p < 10^-5). The DAN demonstrated small areas of increased connectivity in frontal and occipital regions (height: p < 10^-6). For the FPN, increased connectivity was noted in the precuneus, posterior cingulate gyrus, and frontal cortex. No difference in the connectivity of the networks of interest was demonstrated between low- and high-grade gliomas, as well as when stratified by their IDH1-R132H (isocitrate dehydrogenase) mutation status.

CONCLUSION

Altered functional connectivity is reliably found with SBCA and ICA in the DMN, DAN, and FPN in glioma patients, possibly explained by decreased connectivity between the cerebral hemispheres across the corpus callosum due to disruption of the connections.

Improved Task-based Functional MRI Language Mapping in Patients with Brain Tumors through Marchenko-Pastur Principal Component Analysis Denoising

Background Functional MRI improves preoperative planning in patients with brain tumors, but task-correlated signal intensity changes are only 2%-3% above baseline. This makes accurate functional mapping challenging. Marchenko-Pastur principal component analysis (MP-PCA) provides a novel strategy to separate functional MRI signal from noise without requiring user input or prior data representation. Purpose To determine whether MP-PCA denoising improves activation magnitude for task-based functional MRI language mapping in patients with brain tumors. Materials and Methods In this Health Insurance Portability and Accountability Act-compliant study, MP-PCA performance was first evaluated by using simulated functional MRI data with a known ground truth. Right-handed, left-language-dominant patients with brain tumors who successfully performed verb generation, sentence completion, and finger tapping functional MRI tasks were retrospectively identified between January 2017 and August 2018. On the group level, for each task, histograms of z scores for original and MP-PCA denoised data were extracted from relevant regions and contralateral homologs were seeded by a neuroradiologist blinded to functional MRI findings. Z scores were compared with paired two-sided t tests, and distributions were compared with effect size measurements and the Kolmogorov-Smirnov test. The number of voxels with a z score greater than 3 was used to measure task sensitivity relative to task duration. Results Twenty-three patients (mean age ± standard deviation, 43 years ± 18; 13 women) were evaluated. MP-PCA denoising led to a higher median z score of task-based functional MRI voxel activation in left hemisphere cortical regions for verb generation (from 3.8 ± 1.0 to 4.5 ± 1.4; P < .001), sentence completion (from 3.7 ± 1.0 to 4.3 ± 1.4; P < .001), and finger tapping (from 6.9 ± 2.4 to 7.9 ± 2.9; P < .001). Median z scores did not improve in contralateral homolog regions for verb generation (from -2.7 ± 0.54 to -2.5 ± 0.40; P = .90), sentence completion (from -2.3 ± 0.21 to -2.4 ± 0.37; P = .39), or finger tapping (from -2.3 ± 1.20 to -2.7 ± 1.40; P = .07). Individual functional MRI task durations could be truncated by at least 40% after MP-PCA without degradation of clinically relevant correlations between functional cortex and functional MRI tasks. Conclusion Denoising with Marchenko-Pastur principal component analysis led to higher task correlations in relevant cortical regions during functional MRI language mapping in patients with brain tumors. © RSNA, 2020 Online supplemental material is available for this article.

Abstract A65: Longitudinal detection of TERT-mutant plasma cell-free circulating tumor DNA in newly diagnosed glioblastoma patients

Introduction: Liquid biopsies, especially plasma cell-free circulating tumor DNA (ctDNA), provide a potential opportunity to be a noninvasive biomarker for the diagnosis and monitoring of glioblastoma (GBM) patients. Previously, we detected TERT promoter hotspot mutations (C228T and C250T) in ctDNA of IDH wild-type (IDHwt) TERT promoter mutant GBM patients with 100% specificity using mutation-specific droplet digital PCR (ddPCR) assays. Here, we examine the association between mutant TERT ctDNA levels and clinical outcomes in newly diagnosed GBM patients undergoing chemoradiation.

Methods: We analyzed 76 serially collected plasma samples from 17 patients with suspected IDHwt GBM based on MRI before surgery. Twenty mL of whole blood was collected in EDTA tubes at predetermined times: pre- and postoperatively, at the end of chemoradiation, and 1, 3, and 6 months from the end of chemoradiation. TERT promoter mutations C228T or C250T were identified in FFPE tumor samples using ddPCR assays specific for these mutations. Plasma samples were analyzed for the patient’s tumor TERT mutation using the ddPCR assays. The analytically validated thresholds for positive ctDNA detection were 1.5 and 1.7 copies/mL for C228T and C250T, respectively.

Results: Sixteen of 17 (94%) IDHwt tumors had TERT mutations (10 C228T, 6 C250T) with MGMT methylated, unmethylated, or unknown status in 10, 5, and 1, respectively. Fourteen of the 16 patients (87.5%) had detectable mutant ctDNA at one or more time points (range 1.66 to 22.13 copies/mL). Of the 2 patients with undetectable ctDNA, one had diffuse and non-avidly enhancing disease and the other only had pre/postop plasma samples collected. Six patients had detectable ctDNA preop, and most had a dominant rim-enhancing mass with additional nonenhancing or enhancing lesion(s). Ten patients had detectable ctDNA up to 4 days postop, half of whom had undergone gross total resection. For 3 of 5 patients for whom there was a question of pseudoprogression versus true progression, ctDNA kinetics matched the clinical outcome. One patient with MGMT unmethylated multifocal GBM achieved ctDNA zeroconversion at 6 months post radiation (RT), and did not progress for another five months. Another patient was negative at all time points until their 3-month post RT follow-up, at which time they developed a recurrence. Another patient achieved zeroconversion at the end of RT but developed a borderline positive ctDNA at 6 months after RT, 2 months before documented radiographic progression.

Conclusions: In this pilot, prospective ctDNA monitoring study of IDHwt GBM, TERT mutant ctDNA was detected at one or more time points in the majority of patients. ctDNA kinetics were associated with clinical outcomes for some patients. These data suggest that additional, larger studies could refine how ctDNA monitoring may be used to enhance the clinical management of IDHwt GBM patients.

Citation Format: Christine Cordova, Mahrukh M. Syeda, Broderick Corless, Jennifer M. Wiggins, Amie Patel, Sylvia C. Kurz, Malcolm Delara, Zacharia Sawaged, Minerva Utate, Dimitris Placantonakis, John Golfinos, Jessica Schafrick, Joshua S. Silverman, Rajan Jain, Matija Snuderl, David Zagzag, George Karlin-Neumann, David Polsky, Andrew S. Chi. Longitudinal detection of TERT-mutant plasma cell-free circulating tumor DNA in newly diagnosed glioblastoma patients [abstract]. In: Proceedings of the AACR Special Conference on Advances in Liquid Biopsies; Jan 13-16, 2020; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(11_Suppl):Abstract nr A65.

ACTR-09. A PHASE 0 PHARMACODYNAMIC AND PHARMACOKINETIC STUDY OF EVEROLIMUS IN VESTIBULAR SCHWANNOMA (VS) AND MENINGIOMA PATIENTS

BACKGROUND

Inhibition of mTORC1 signaling has been shown to diminish growth of NF2 deficient tumors in preclinical studies, and clinical data suggest that everolimus, an orally administered mTORC1 inhibitor, may slow tumor progression in a subset of adult and pediatric NF2 patients with VS. To assess the pharmacokinetics, pharmacodynamics and potential mechanisms of treatment resistance, we performed a pre-surgical (“phase 0”) clinical trial of everolimus in patients undergoing surgery for VS or meningiomas.

METHODS

Eligible patients with meningioma or VS requiring tumor resection received everolimus 10 mg daily for 10 days immediately prior to surgery. Everolimus blood levels were determined immediately prior to and after surgery. Tumor samples were collected intraoperatively.

RESULTS

Ten patients completed protocol therapy, including 5 patients with NF2-related meningioma, 3 patients with sporadic meningioma, and 2 patients with NF2-related VS. Median pre- and post-operative plasma levels of everolimus were found to be in a high therapeutic range (17.4 ng/ml and 9.4 ng/ml, respectively). Median tumor tissue drug concentration determined by mass spectrometry was 24.3 ng/g (range 9.2–169.2), and median tumor tissue to post-operative plasma drug concentration ratio was 0.39. We observed only partial inhibition of phospho-S6 in the treated tumors, indicating incomplete target inhibition compared to matched control tissues from untreated patients (p = 0.005). Consistent with prior observations that inhibition of mTORC1 may lead to MAPK pathway activation through a PI3K-dependent feedback loop, we observed a statistically significant increase of phospho-ERK (p < 0.03) versus untreated controls.

CONCLUSIONS

In patients with meningioma or VS, treatment with everolimus leads to incomplete inhibition of mTORC1 signaling and upregulation phospho-ERK. These data may explain the limited anti-tumor effect of everolimus observed in clinical studies for NF2 patients and identify upregulation of phospho-ERK as a likely resistance mechanism that could be addressed with combination therapies.

NIMG-09. NONINVASIVE PERFUSION IMAGING BIOMARKER OF MALIGNANT GENOTYPE IN ISOCITRATE DEHYDROGENASE MUTANT GLIOMAS

OBJECTIVE

A small subset of IDHmut astrocytomas behave aggressively, similarly to IDHwt glioblastoma. Genomic correlates of poor prognosis IDHmut astrocytomas include global relative DNA hypomethylation, MYCN amplification copy number variation (CNV) abundance, and CDKN2A/B homozygous deletion. We sought to identify a non-invasive imaging correlate of poor prognosis IDHmut astrocytomas.

METHODS

30 IDHmut astrocytomas (NYU=18, TCGA=12) were included. Relative cerebral blood volume was obtained from 4 regions of interest within the highest perfusion areas. Genomic CNV analysis and CDKN2A/B copy number status was obtained using Illumina Infinium 450k or Illumina EPIC methylation array data. Associations between rCBV, survival, and genomic alterations were evaluated. An additional 22 IDHmut astrocytomas were obtained from another institution for validation.

RESULTS

CNV stable (CNV-S, n=14) astrocytomas demonstrated significantly lower mean rCBV than and CNV unstable (CNV-U, n=16) (P=0.0.0155) ones. IDHmut astrocytomas with CDKN2A/B homozygous deletion (n=7) had higher rCBV (3.9 ± 2.3, mean ± SD) compared to those without this alteration (n=22; 1.8 ± 1.9, mean ± SD; P=0.0489). In the validation set, there was no significant evidence in rCBV between CNV-S and CNV-U tumors (P=0.3976). These results were sensitive to a single outlier in the CNV-S group. Excluding this case with rCBV=7.15, the CNV-S tumors demonstrated significantly lower mean rCBV (P=0.0279). IDHmut astrocytomas with CDKN2A/B homozygous deletion (n=9) tended to have higher rCBV (4.2 ± 1.8, mean ± SD) compared to those without this alteration (n=16; 2.5 ± 1.5, mean ± SD; P=0.0757, t-test). This led to significant discrimination (P=0.0328, Wilcoxon).

CONCLUSION

Our study is the first to identify a non-invasive imaging biomarker for prognostic genomic alterations in IDHmut astrocytomas. Greater CNV abundance and/or CDKN2A/B homozygous deletion have higher rCBV and worse prognosis. Our methods can be applied to standard clinical practice and may enhance informed treatment decisions in the preoperative and immediate postoperative settings.

Plasma cell-free circulating tumor DNA (ctDNA) detection in longitudinally followed glioblastoma patients using TERT promoter mutation-specific droplet digital PCR assays

2026

Background: There is a critical need for more specific and less invasive diagnostic and pharmacodynamic biomarkers in glioblastoma (GBM) patients (pts). Previously, we detected TERT promoter hotspot mutations (C228T and C250T) in the ctDNA of IDH wildtype ( IDHwt) TERT promoter mutant GBM pts with 100% specificity using mutation-specific droplet digital PCR (ddPCR) assays. Here, we explored the dynamics and clinical associations of mutant TERT ctDNA levels in GBM pts undergoing therapy. Methods: We examined 14 pts with suspected IDHwt GBM based on preoperative MRI. Plasma was isolated and frozen from ~15 mL whole blood samples collected pre- and post-op, at end of radiation (RT), and 1, 3, and 6 m after end of RT. TERT promoter mutations were identified in FFPE tumor samples using ddPCR assays for C228T/C250T. Plasma samples were analyzed using ddPCR assays specific for the corresponding tumor mutation. The validated thresholds for positive detection were 1.5 (C228T) and 1.7 copies/mL (C250T). Results: 13/14 (92.9%) IDHwt tumors had TERT mutations (7 C228T and 6 C250T). Six of these 13 (46%) pts had positive plasma TERT ctDNA preop (4 C228T, 2 C250T). The mean cross sectional area of enhancing disease at presentation for positive or negative preop mutant ctDNA was similar. All 4 pts with multiple contrast enhancing lesions had positive preop mutant ctDNA. 2 pts who were negative initially developed detectable mutant ctDNA preceding progression. 3/4 pts with equivocal radiographic pseudoprogression had ctDNA dynamics that correlated with eventual clinical outcome. One patient with unresectable GBM had declining mutant ctDNA in later collections during clinical stability. Conclusions: We detected plasma TERT ctDNA in 46% of TERT mutant GBM pts before surgery, and in 100% of pts with multiple contrast enhancing lesions. TERT mutant ctDNA levels correlated with pseudoprogression or true disease progression and predicted progression before MRI. These data suggest that larger studies to test circulating cell-free TERT mutation as a diagnostic and pharmacodynamic biomarker in GBM are warranted.

Predicting Genotype and Survival in Glioma Using Standard Clinical MR Imaging Apparent Diffusion Coefficient Images: A Pilot Study from The Cancer Genome Atlas

BACKGROUND AND PURPOSE

Few studies have shown MR imaging features and ADC correlating with molecular markers and survival in patients with glioma. Our purpose was to correlate MR imaging features and ADC with molecular subtyping and survival in adult diffuse gliomas.

MATERIALS AND METHODS

Presurgical MRIs and ADC maps of 131 patients with diffuse gliomas and available molecular and survival data from The Cancer Genome Atlas were reviewed. MR imaging features, ADC (obtained by ROIs within the lowest ADC area), and mean relative ADC values were evaluated to predict isocitrate dehydrogenase (IDH) mutation, 1p/19q codeletion status, MGMT promoter methylation, and overall survival.

RESULTS

IDH wild-type gliomas tended to exhibit enhancement, necrosis, and edema; >50% enhancing area (P < .001); absence of a cystic area (P = .013); and lower mean relative ADC (median, 1.1 versus 1.6; P < .001) than IDH-mutant gliomas. By means of a cutoff value of 1.08 for mean relative ADC, IDH-mutant and IDH wild-type gliomas with lower mean relative ADC (<1.08) had poorer survival than those with higher mean relative ADC (median survival time, 24.2 months; 95% CI, 0.0-54.9 months versus 62.0 months; P = .003; and median survival time, 10.4 months; 95% CI, 4.4-16.4 months versus 17.7 months; 95% CI, 11.6-23.7 months; P = .041, respectively), regardless of World Health Organization grade. Median survival of those with IDH-mutant glioma with low mean relative ADC was not significantly different from that in those with IDH wild-type glioma. Other MR imaging features were not statistically significant predictors of survival.

CONCLUSIONS

IDH wild-type glioma showed lower ADC values, which also correlated with poor survival in both IDH-mutant and IDH wild-type gliomas, irrespective of histologic grade. A subgroup with IDH-mutant gliomas with lower ADC had dismal survival similar to that of those with IDH wild-type gliomas.

A Superior Cerebellar Convexity Two-Part Craniotomy to Access the Paramedian Supra and Infratentorial Space: Technical Note

A craniotomy over the superior cerebellar convexity for approaches to this region typically involves a small infratentorial craniotomy and then drilling down of the bone to expose some portion of the transverse/sigmoid sinuses. The authors describe the anatomy of the region and the method for a two-part paramedian occipital and suboccipital craniotomy (supra and infratentorial) that may have time-saving, safety, and cosmetic advantages. For this technique, a supratentorial craniotomy is used to expose the transverse sinus from above, and subsequently, dissection across the sinus over the cerebellar convexity can be done under direct vision. The two bone pieces are joined on the inner table side while plates for fixation above the superior nuchal line can be counter-sunk to avoid post-operative pain from the prominence of screws. There is no need for cranioplasty materials since there is no burring down of bone for adequate exposure of the transverse sinus. The technique has been used by two senior surgeons over the years convincing them of the speed, safety, and utility of the technique. Here, the authors present a single example of the technique. 

Somatic and germline analyses of a long term melanoma survivor with a recurrent brain metastasis

Background

Median overall survival (OS) of patients with melanoma brain metastases (MBM) is usually 6 months or less. There are rare reports of patients with treated MBM who survived for years. These outlier cases represent valuable opportunities to study the somatic and germline factors that may have influenced patient outcome and led to extended survival.

Case presentation

Here we report the clinical scenario of a 67 year old man with a recurrent brain metastasis from melanoma who has survived over 12 years post-resection. We review the literature relating to clinical and molecular variables associated with long term survival post-brain metastasis. We present the somatic characteristics of this individual patient’s tumor as well as an analysis of inherited genetic variants related to immune function.

The patient’s resected brain tumor is BRAF V600E mutated, NRAS wild type (WT), and TERT C250T mutated. The patient is a carrier of germline variants in immunomodulatory loci associated with prolonged survival.

Conclusions

Our data suggest that genetic variants in immunomodulatory loci may partially contribute to this patient’s unusually favorable outcome and should not be overlooked. With further and future investigation, knowledge of inherited single nucleotide polymorphisms (SNPs) may provide clinicians with more individualized prognostic information for melanoma patients, with potential implications for surveillance strategies and therapeutic interventions.

Glioma Angiogenesis and Perfusion Imaging: Understanding the Relationship between Tumor Blood Volume and Leakiness with Increasing Glioma Grade

BACKGROUND AND PURPOSE

The purpose of this study was to investigate imaging correlates to the changes occurring during angiogenesis in gliomas. This was accomplished through in vivo assessment of vascular parameters (relative CBV and permeability surface-area product) and their changing relationship with increasing glioma grade.

MATERIALS AND METHODS

Seventy-six patients with gliomas underwent preoperative perfusion CT and assessment of relative CBV and permeability surface-area product. Regression analyses were performed to assess the rate of change between relative CBV and permeability surface-area product and to test whether these differed for distinct glioma grades. The ratio of relative CBV to permeability surface-area product was also computed and compared among glioma grades by using analysis of variance methods.

RESULTS

The rate of change in relative CBV with respect to permeability surface-area product was highest for grade II gliomas followed by grade III and then grade IV (1.64 versus 0.91 versus 0.27, respectively). The difference in the rate of change was significant between grade III and IV (P = .003) and showed a trend for grades II and IV (P = .098). Relative CBV/permeability surface-area product ratios were the highest for grade II and lowest for grade IV. The pair-wise difference among all 3 groups was significant (P < .001).

CONCLUSIONS

There is an increase in relative CBV more than permeability surface-area product in lower grade gliomas, whereas in grade III and especially grade IV gliomas, permeability surface-area product increases much more than relative CBV. The rate of change of relative CBV with respect to permeability surface-area product and relative CBV/permeability surface-area product ratio can serve as an imaging correlate to changes occurring at the tumor microvasculature level.

Quality of Life Assessment in Patients with Neurofibromatosis Type II

Objectives:

(1) Develop a multidimensional metric for assessing quality of life (QoL) in patients with NF2. (2) Compare NF2 results with reference values for the general population and patients with head and neck or brain cancer.

Methods:

Structured interviews with NF2 providers and patients identified relevant domains. Items in these domains were extracted from validated EORTC modules, combined with items unique to NF2 and pre-tested on NF2 providers and patients (N = 118). The questionnaire included 61 items assessing overall QoL and 10 additional domains including hearing, balance, facial function, vision, oral intake, future uncertainty, psychosocial, cognition, sexual activity, pain and vocal communication. Responses were compared to reference values for the general population and head and neck cancer and brain cancer patients.

Results:

QoL in NF2 patients was lower than that of the general population ( P < .01) and similar to that of patients with cancer. NF2 patients whose treatment included radiation therapy had worse overall QoL than patients who did not undergo radiation. Patients with more facial weakness, hearing loss and imbalance reported significantly lower QoL. However, domains most predictive of overall QoL were psychosocial, future uncertainty and pain. When compared to patients with head and neck and brain cancer, NF2 patients demonstrated significantly higher levels of psychosocial stressors, including disease-related anxiety, personal and financial stress, and lack of social support ( P < .01).

Conclusions:

Psychosocial stress and pain significantly impact QoL in NF2 indicating that mental health, pain management, and financial counseling could have an important impact on QoL in this population.

A phase II trial of lithium, bevacizumab, temozolomide, and radiation for newly diagnosed glioblastomas (GBM)

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Background: Invasion is a dominant escape mechanism following angiogenic blockade in glioblastomas (GBM). Lithium has shown anti-invasive activity in glioma cells by inhibiting Glycogen Synthetase Kinase -3. This phase II study evaluated the safety and efficacy of using lithium and bevacizumab (BEV) in newly diagnosed GBM. Methods: From 2010 through 2012, 20 GBM patients with residual disease after surgery were treated with involved-field radiation therapy to 5940 cGy and concomitant temozolomide (TMZ) (75 mg/m2 daily for 42 days) along with BEV (10 mg/kg every 2 weeks), starting 29 days after surgery. This was followed by six 28-day cycles of TMZ (150 mg/m2 on days 1-7, BEV (10 mg/kg) on days 8 and 22, and lithium 300 mg BID. Lithium was increased every 7 days up to 600 mg BID with a serum lithium goal level of 0.8 to 1.2 mEq/L. Results: The median follow-up was 9.9 months (range 1.9-24.5). Fourteen patients (70.0%) received at least one dose of lithium and three patients completed the entire course of therapy. The median number of BEV infusion was 9 (range 2-19). Five patients discontinued trial due to skin sensitivity (n = 2), pulmonary embolism (n = 1), infection (n = 1), and hematological toxicity (n=1). Two patients experienced dose limiting lithium toxicity which included drowsiness (n = 1) and tremor (n = 1). No patients experienced grade 3/4 intra-cranial hemorrhage. The median progression free survival (PFS) was 9.3 months. The 12-month PFS and OS were 31.9% and 59.3% respectively. For the 14 patients who received lithium, the 12-month PFS and OS were 42.9% and 69.2% respectively. Conclusions: The strategy of targeting angiogenesis and invasion simultaneously in newly diagnosed GBM is effective and feasible. Clinical trial information: NCT01105702.