Publications by authors named "MacLean P Nasrallah"

36 Publications

TP53 Mutation and Extraneural Metastasis of Glioblastoma: Insights From an Institutional Experience and Comprehensive Literature Review.

Am J Surg Pathol 2021 11;45(11):1516-1526

Departments of Pathology and Laboratory Medicine.

Extraneural metastases of glioblastoma (GBM), although rare, are becoming an increasingly recognized occurrence. Currently, the biological mechanism underlying this rare occurrence is not understood. To explore the potential genomic drivers of extraneural metastasis in GBM, we present the molecular features of 4 extraneural metastatic GBMs, along with a comprehensive review and analysis of previously reported cases that had available molecular characterization. In addition to our 4 cases, 42 patients from 35 publications are reviewed. To compare the molecular profiles between GBM cases with extraneural metastasis and the general GBM population, genomic data from GBM samples in The Cancer Genome Atlas (TCGA) database were also analyzed. We found that 64.5% (20/31) of the cases with extraneural metastasis that were tested for TP53 changes had at least 1 TP53 pathogenic variant detected in either 1 or both primary and metastatic tumors. In contrast, TP53 mutation was significantly less frequent in the unselected GBM from TCGA (22.6%, 56/248) (P=0.000). In addition, O-6-methylguanine-DNA methyltransferase (MGMT) promoter methylation was more common in unselected TCGA GBM cases (48.6%, 170/350) than in cases with extraneural metastasis (31.8%, 7/22), although not statistically significant. Although isocitrate dehydrogenase (IDH) mutation is a rare occurrence in high-grade astrocytomas, IDH-mutant grade 4 astrocytomas are at least as likely to metastasize as IDH wild-type GBMs; 3 metastatic cases definitively harbored an IDH1 (p.R132H) mutation in our analysis. Our findings not only provide potential biomarkers for earlier screening of extraneural metastasis, but could also suggest clues to understanding biological mechanisms underlying GBM metastasis, and for the development of therapeutic modalities.
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http://dx.doi.org/10.1097/PAS.0000000000001762DOI Listing
November 2021

Accurate and Robust Alignment of Differently Stained Histologic Images Based on Greedy Diffeomorphic Registration.

Appl Sci (Basel) 2021 Feb 21;11(4). Epub 2021 Feb 21.

Center for Biomedical Image Computing & Analytics, University of Pennsylvania, Philadelphia, PA 19104, USA.

Histopathologic assessment routinely provides rich microscopic information about tissue structure and disease process. However, the sections used are very thin, and essentially capture only 2D representations of a certain tissue sample. Accurate and robust alignment of sequentially cut 2D slices should contribute to more comprehensive assessment accounting for surrounding 3D information. Towards this end, we here propose a two-step diffeomorphic registration approach that aligns differently stained histology slides to each other, starting with an initial affine step followed by estimating a deformation field. It was quantitatively evaluated on ample ( = 481) and diverse data from the automatic non-rigid histological image registration challenge, where it was awarded the second rank. The obtained results demonstrate the ability of the proposed approach to robustly (average robustness = 0.9898) and accurately (average relative target registration error = 0.2%) align differently stained histology slices of various anatomical sites while maintaining reasonable computational efficiency (<1 min per registration). The method was developed by adapting a general-purpose registration algorithm designed for 3D radiographic scans and achieved consistently accurate results for aligning high-resolution 2D histologic images. Accurate alignment of histologic images can contribute to a better understanding of the spatial arrangement and growth patterns of cells, vessels, matrix, nerves, and immune cell interactions.
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http://dx.doi.org/10.3390/app11041892DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8291745PMC
February 2021

Case Report: Prolonged Survival Following EGFRvIII CAR T Cell Treatment for Recurrent Glioblastoma.

Front Oncol 2021 7;11:669071. Epub 2021 May 7.

Glioblastoma Translational Center of Excellence, The Abramson Cancer Center, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, United States.

Autologous chimeric antigen receptor (CAR) T cells targeted to epidermal growth factor receptor variant III (CAR T-EGFRvIII) have been developed and administered experimentally to treat patients with IDH1 wildtype recurrent glioblastoma (rGBM) (NCT02209376). We report the case of a 59-year-old patient who received a single peripheral infusion of CAR T-EGFRvIII cells and survived 36 months after disease recurrence, exceeding expected survival for recurrent glioblastoma. Post-infusion histopathologic analysis of tissue obtained during a second stage surgical resection revealed immunosuppressive adaptive changes in the tumor tissue as well as reduced EGFRvIII expression. Serial brain imaging demonstrated a significant reduction in relative cerebral blood volume (rCBV), a measure strongly associated with tumor proliferative activity, at early time points following CAR T treatment. Notably, CAR T-EGFRvIII cells persisted in her peripheral circulation during 29 months of follow-up, the longest period of CAR T persistence reported in GBM trials to date. These findings in a long-term survivor show that peripherally administered CAR T-EGFRvIII cells can persist for years in the circulation and suggest that this cell therapy approach could be optimized to achieve broader efficacy in recurrent GBM patients.
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http://dx.doi.org/10.3389/fonc.2021.669071DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8138201PMC
May 2021

Multi-institutional noninvasive in vivo characterization of , 1p/19q, and EGFRvIII in glioma using neuro-Cancer Imaging Phenomics Toolkit (neuro-CaPTk).

Neurooncol Adv 2020 Dec 23;2(Suppl 4):iv22-iv34. Epub 2021 Jan 23.

Center for Biomedical Image Computing and Analytics, University of Pennsylvania, Philadelphia, Pennsylvania, USA.

Background: Gliomas represent a biologically heterogeneous group of primary brain tumors with uncontrolled cellular proliferation and diffuse infiltration that renders them almost incurable, thereby leading to a grim prognosis. Recent comprehensive genomic profiling has greatly elucidated the molecular hallmarks of gliomas, including the mutations in and ( and ), loss of chromosomes 1p and 19q (1p/19q), and epidermal growth factor receptor variant III (EGFRvIII). Detection of these molecular alterations is based on ex vivo analysis of surgically resected tissue specimen that sometimes is not adequate for testing and/or does not capture the spatial tumor heterogeneity of the neoplasm.

Methods: We developed a method for detection of radiogenomic markers of both in lower-grade gliomas (WHO grade II and III tumors) and glioblastoma (WHO grade IV), 1p/19q in -mutant lower-grade gliomas, and EGFRvIII in glioblastoma. Preoperative MRIs of 473 glioma patients from 3 of the studies participating in the ReSPOND consortium (collection I: Hospital of the University of Pennsylvania [HUP: = 248], collection II: The Cancer Imaging Archive [TCIA; = 192], and collection III: Ohio Brain Tumor Study [OBTS, = 33]) were collected. Neuro-Cancer Imaging Phenomics Toolkit (neuro-CaPTk), a modular platform available for cancer imaging analytics and machine learning, was leveraged to extract histogram, shape, anatomical, and texture features from delineated tumor subregions and to integrate these features using support vector machine to generate models predictive of , 1p/19q, and EGFRvIII. The models were validated using 3 configurations: (1) 70-30% training-testing splits or 10-fold cross-validation within individual collections, (2) 70-30% training-testing splits within merged collections, and (3) training on one collection and testing on another.

Results: These models achieved a classification accuracy of 86.74% (HUP), 85.45% (TCIA), and 75.15% (TCIA) in identifying EGFRvIII, , and 1p/19q, respectively, in configuration I. The model, when applied on combined data in configuration II, yielded a classification success rate of 82.50% in predicting mutation (HUP + TCIA + OBTS). The model when trained on TCIA dataset yielded classification accuracy of 84.88% in predicting in HUP dataset.

Conclusions: Using machine learning algorithms, high accuracy was achieved in the prediction of , 1p/19q, and EGFRvIII mutation. Neuro-CaPTk encompasses all the pipelines required to replicate these analyses in multi-institutional settings and could also be used for other radio(geno)mic analyses.
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http://dx.doi.org/10.1093/noajnl/vdaa128DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7829474PMC
December 2020

Neuropathology associated with SARS-CoV-2 infection.

Lancet 2021 01;397(10271):277

Division of Neuropathology, Department of Pathology and Laboratory Medicine, Hospital of the University of Pennsylvania, Philadelphia, PA 19104, USA.

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http://dx.doi.org/10.1016/S0140-6736(21)00096-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7825880PMC
January 2021

The spectrum of rare central nervous system (CNS) tumors with EWSR1-non-ETS fusions: experience from three pediatric institutions with review of the literature.

Brain Pathol 2021 01 6;31(1):70-83. Epub 2020 Nov 6.

General Pathology and Cytopathology Unit, Department of Medicine-DIMED, University of Padova, Padova, Italy.

The group of CNS mesenchymal (non-meningothelial) and primary glial/neuronal tumors in association with EWSR1-non-ETS rearrangements comprises a growing spectrum of entities, mostly reported in isolation with incomplete molecular profiling. Archival files from three pediatric institutions were queried for unusual cases of pediatric (≤21 years) CNS EWSR1-rearranged tumors confirmed by at least one molecular technique. Extra-axial tumors and cases with a diagnosis of Ewing sarcoma (EWSR1-ETS family fusions) were excluded. Additional studies, including anchored multiplex-PCR with next-generation sequencing and DNA methylation profiling, were performed as needed to determine fusion partner status and brain tumor methylation class, respectively. Five cases (median 17 years) were identified (M:F of 3:2). Location was parenchymal (n = 3) and undetermined (n = 2) with topographic distributions including posterior fossa (n = 1), frontal (n = 1), temporal (n = 1), parietal (n = 1) and occipital (n = 1) lobes. Final designation with fusion findings included desmoplastic small round cell tumor (EWSR1-WT1; n = 1) and tumors of uncertain histogenesis (EWSR1-CREM, n = 1; EWSR1-CREB1, n = 1; EWSR1-PLAGL1, n = 1; and EWSR1-PATZ1, n = 1). Tumors showed a wide spectrum of morphology and biologic behavior. For EWSR1-CREM, EWSR1-PLAGL1 and EWSR1-PATZ1 tumors, no significant methylation scores were reached in the known brain tumor classes. Available outcome (4/5) was reported as favorable (n = 2) and unfavorable (n = 2) with a median follow-up of 30 months. In conclusion, we describe five primary EWSR1-non-ETS fused CNS tumors exhibiting morphologic and biologic heterogeneity and we highlight the clinical importance of determining specific fusion partners to improve diagnostic accuracy, treatment and monitoring. Larger prospective clinicopathological and molecular studies are needed to determine the prognostic implications of histotypes, anatomical location, fusion partners, breakpoints and methylation profiles in patients with these rare tumors.
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http://dx.doi.org/10.1111/bpa.12900DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8018079PMC
January 2021

Towards Population-Based Histologic Stain Normalization of Glioblastoma.

Brainlesion 2020 19;11992:44-56. Epub 2020 May 19.

Center for Biomedical Image Computing and Analytics (CBICA), University of Pennsylvania, Philadelphia, PA, USA.

Glioblastoma ( ) is the most aggressive type of primary malignant adult brain tumor, with very heterogeneous radio-graphic, histologic, and molecular profiles. A growing body of advanced computational analyses are conducted towards further understanding the biology and variation in glioblastoma. To address the intrinsic heterogeneity among different computational studies, reference standards have been established to facilitate both radiographic and molecular analyses, e.g., anatomical atlas for image registration and housekeeping genes, respectively. However, there is an apparent lack of reference standards in the domain of digital pathology, where each independent study uses an arbitrarily chosen slide from their evaluation dataset for normalization purposes. In this study, we introduce a novel stain normalization approach based on a composite reference slide comprised of information from a large population of anatomically annotated hematoxylin and eosin ( ) whole-slide images from the Ivy Glioblastoma Atlas Project ( ). Two board-certified neuropathologists manually reviewed and selected annotations in 509 slides, according to the World Health Organization definitions. We computed summary statistics from each of these approved annotations and weighted them based on their percent contribution to overall slide ( ), to form a global histogram and stain vectors. Quantitative evaluation of pre- and post-normalization stain density statistics for each annotated region with PCOS > 0.05% yielded a significant (largest = 0.001, two-sided Wilcoxon rank sum test) reduction of its intensity variation for both & . Subject to further large-scale evaluation, our findings support the proposed approach as a potentially robust population-based reference for stain normalization.
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http://dx.doi.org/10.1007/978-3-030-46640-4_5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7394499PMC
May 2020

Molecular and clinicopathologic features of gliomas harboring NTRK fusions.

Acta Neuropathol Commun 2020 07 14;8(1):107. Epub 2020 Jul 14.

Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, 75 Francis Street, Boston, MA, 02115, USA.

Fusions involving neurotrophic tyrosine receptor kinase (NTRK) genes are detected in ≤2% of gliomas and can promote gliomagenesis. The remarkable therapeutic efficacy of TRK inhibitors, which are among the first Food and Drug Administration-approved targeted therapies for NTRK-fused gliomas, has generated significant clinical interest in characterizing these tumors. In this multi-institutional retrospective study of 42 gliomas with NTRK fusions, next generation DNA sequencing (n = 41), next generation RNA sequencing (n = 1), RNA-sequencing fusion panel (n = 16), methylation profile analysis (n = 18), and histologic evaluation (n = 42) were performed. All infantile NTRK-fused gliomas (n = 7) had high-grade histology and, with one exception, no other significant genetic alterations. Pediatric NTRK-fused gliomas (n = 13) typically involved NTRK2, ranged from low- to high-histologic grade, and demonstrated histologic overlap with desmoplastic infantile ganglioglioma, pilocytic astrocytoma, ganglioglioma, and glioblastoma, among other entities, but they rarely matched with high confidence to known methylation class families or with each other; alterations involving ATRX, PTEN, and CDKN2A/2B were present in a subset of cases. Adult NTRK-fused gliomas (n = 22) typically involved NTRK1 and had predominantly high-grade histology; genetic alterations involving IDH1, ATRX, TP53, PTEN, TERT promoter, RB1, CDKN2A/2B, NF1, and polysomy 7 were common. Unsupervised principal component analysis of methylation profiles demonstrated no obvious grouping by histologic grade, NTRK gene involved, or age group. KEGG pathway analysis detected methylation differences in genes involved in PI3K/AKT, MAPK, and other pathways. In summary, the study highlights the clinical, histologic, and molecular heterogeneity of NTRK-fused gliomas, particularly when stratified by age group.
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http://dx.doi.org/10.1186/s40478-020-00980-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7362646PMC
July 2020

Immunotherapy and Response Assessment in Malignant Glioma: Neuro-oncology Perspective.

Top Magn Reson Imaging 2020 Apr;29(2):95-102

Glioblastoma Translational Center of Excellence, Abramson Cancer Center, University of Pennsylvania, Philadelphia, PA.

Glioblastoma (GBM) is the deadliest form of brain cancer and recurs uniformly. Despite aggressive treatment with maximal safe surgical resection, adjuvant radiation with temozolomide chemotherapy, and alternating electrical field therapy, median survival for newly diagnosed GBM remains <2 years. Novel therapies are desperately needed. Immunotherapy, which has led to significant improvement in patient outcomes across many tumor types, is currently being studied in a large number of GBM clinical trials. One of the biggest challenges in immunotherapy trials in GBM has been accurate response assessment using currently available imaging modalities, including magnetic resonance imaging. In this review, we will discuss the rationale for immunotherapy for GBM, immunotherapeutic modalities currently under clinical evaluation in GBM, and the challenges and recent advances in imaging response assessment in GBM immunotherapy.
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http://dx.doi.org/10.1097/RMR.0000000000000233DOI Listing
April 2020

Imaging and histopathologic correlates of plasma cell-free DNA concentration and circulating tumor DNA in adult patients with newly diagnosed glioblastoma.

Neurooncol Adv 2020 Jan-Dec;2(1):vdaa016. Epub 2020 Feb 27.

Glioblastoma Translational Center of Excellence, Abramson Cancer Center, University of Pennsylvania, Philadelphia, Pennsylvania, USA.

Background: Plasma cell-free DNA (cfDNA) concentration is lower in glioblastoma (GBM) compared to other solid tumors, which can lead to low circulating tumor DNA (ctDNA) detection. In this study, we investigated the relationship between multimodality magnetic resonance imaging (MRI) and histopathologic features with plasma cfDNA concentration and ctDNA detection in patients with treatment-naive GBM.

Methods: We analyzed plasma cfDNA concentration, MRI scans, and tumor histopathology from 42 adult patients with newly diagnosed GBM. Linear regression analysis was used to examine the relationship of plasma cfDNA concentration before surgery to imaging and histopathologic characteristics. In a subset of patients, imaging and histopathologic metrics were also compared between patients with and without a detected tumor somatic mutation.

Results: Tumor volume with elevated (>1.5 times contralateral white matter) rate transfer constant ( , a surrogate of blood-brain barrier [BBB] permeability) was independently associated with plasma cfDNA concentration ( = .001). Histopathologic characteristics independently associated with plasma cfDNA concentration included CD68+ macrophage density ( = .01) and size of tumor vessels ( = .01). Patients with higher (grade ≥3) perivascular CD68+ macrophage density had lower volume transfer constant ( , = .01) compared to those with lower perivascular CD68+ macrophage density. Detection of at least 1 somatic mutation in plasma cfDNA was associated with significantly lower perivascular CD68+ macrophages ( = .01).

Conclusions: Metrics of BBB disruption and quantity and distribution of tumor-associated macrophages are associated with plasma cfDNA concentration and ctDNA detection in GBM patients. These findings represent an important step in understanding the factors that determine plasma cfDNA concentration and ctDNA detection.
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http://dx.doi.org/10.1093/noajnl/vdaa016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7045782PMC
February 2020

Histopathology-validated machine learning radiographic biomarker for noninvasive discrimination between true progression and pseudo-progression in glioblastoma.

Cancer 2020 06 4;126(11):2625-2636. Epub 2020 Mar 4.

Center for Biomedical Image Computing and Analytics, University of Pennsylvania, Philadelphia, Pennsylvania.

Background: Imaging of glioblastoma patients after maximal safe resection and chemoradiation commonly demonstrates new enhancements that raise concerns about tumor progression. However, in 30% to 50% of patients, these enhancements primarily represent the effects of treatment, or pseudo-progression (PsP). We hypothesize that quantitative machine learning analysis of clinically acquired multiparametric magnetic resonance imaging (mpMRI) can identify subvisual imaging characteristics to provide robust, noninvasive imaging signatures that can distinguish true progression (TP) from PsP.

Methods: We evaluated independent discovery (n = 40) and replication (n = 23) cohorts of glioblastoma patients who underwent second resection due to progressive radiographic changes suspicious for recurrence. Deep learning and conventional feature extraction methods were used to extract quantitative characteristics from the mpMRI scans. Multivariate analysis of these features revealed radiophenotypic signatures distinguishing among TP, PsP, and mixed response that compared with similar categories blindly defined by board-certified neuropathologists. Additionally, interinstitutional validation was performed on 20 new patients.

Results: Patients who demonstrate TP on neuropathology are significantly different (P < .0001) from those with PsP, showing imaging features reflecting higher angiogenesis, higher cellularity, and lower water concentration. The accuracy of the proposed signature in leave-one-out cross-validation was 87% for predicting PsP (area under the curve [AUC], 0.92) and 84% for predicting TP (AUC, 0.83), whereas in the discovery/replication cohort, the accuracy was 87% for predicting PsP (AUC, 0.84) and 78% for TP (AUC, 0.80). The accuracy in the interinstitutional cohort was 75% (AUC, 0.80).

Conclusion: Quantitative mpMRI analysis via machine learning reveals distinctive noninvasive signatures of TP versus PsP after treatment of glioblastoma. Integration of the proposed method into clinical studies can be performed using the freely available Cancer Imaging Phenomics Toolkit.
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http://dx.doi.org/10.1002/cncr.32790DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7893811PMC
June 2020

Intraoperative cytology of pituicytomas.

Diagn Cytopathol 2020 Apr 28;48(4):342-349. Epub 2019 Dec 28.

Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.

Background: Pituicytoma is a rare tumor of the sella and suprasellar region. It is common for these tumors to be misdiagnosed radiographically as pituitary adenomas, meningiomas, and craniopharyngiomas. Histologically, pituicytomas are also known to show variable morphology. These factors often complicate intraoperative consultation, especially when tissue is limited.

Methods: A database search (January 1990-June 2019) identified 13 surgically resected pituicytomas that were sent for intraoperative consultation. The intraoperative cytology was reviewed by two pathologists, and both squash preparations/smears and touch preparations were included.

Results: The cytological features of pituicytomas were variable. The cytoplasm ranged from fibrillary to fine and wispy. The nuclei were round to ovoid with occasional tumors showing spindled morphology. Small nucleoli were seen in all tumors, and chromatin was fine to vesicular. While squash preparations were cellular and revealed cohesive groups of tumor cells, touch preparations were often paucicellular with the exception of one tumor. The cytological features of pituicytomas are compared to those of other tumors with similar radiographic appearances.

Conclusions: Our findings illustrate the range of cytological features of these rare tumors and highlight the difficulty in making a definitive intraoperative diagnosis. Pituicytomas should be considered in the differential of a sellar/suprasellar lesion with glial and meningioma-like cytological features.
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http://dx.doi.org/10.1002/dc.24372DOI Listing
April 2020

Rapid and ultrasensitive digital PCR (dPCR) profiling of EGFRvIII in tumor cells and tissues.

Neurooncol Adv 2019 May-Dec;1(1):vdz030. Epub 2019 Nov 28.

Department of Radiation Oncology.

Background: Amplification of the epidermal growth factor receptor () gene is commonly found in glioblastoma (GBM). About 57% GBM overexpresses EGFR and are associated with tumor progression, poor prognosis, and shorter life expectancy. Molecular profiling of solid tumors usually takes several weeks and may be biased by intrinsic tumor heterogeneity.

Methods: The unique sequence created by the fusion of exon 1 and exon 8 in EGFRvIII was used to guide the design of primers and a Minor Groove Binder (MGB) probe. Extracted total RNA was reverse transcribed and pre-amplified by PCR, followed by detection of the EGFRvIII mutation by dPCR.

Results: The lowest limit of quantification of our EGFRvIII assay was 0.003%. The EGFRvIII variant was identified in patient-derived glioma neurosphere cell lines, xenograft mouse model, and patient-derived tumor specimens. The overall workflow can be accomplished within 24 hours. In certain samples, EGFRvIII was detected when next-generation sequencing was unable to identify the variant. This finding highlights the ability of the dPCR assay to identify EGFRvIII mutations in heterogeneous solid tumors such as GBM in a rapid fashion by profiling samples from spatially distinct areas of tumors from the same patient.

Conclusions: In this study, we developed a highly sensitive digital PCR (dPCR) platform and leveraged our assay to detect the variant III alteration of EGFR (EGFRvIII) and amplified EGFR in patient-derived glioma neurosphere cell lines, orthotopic xenograft GBM mouse models, and patient-derived tumor specimens in less than 24 hours from minute quantities of starting material.
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http://dx.doi.org/10.1093/noajnl/vdz030DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6881905PMC
November 2019

Clinical activity of the tyrosine kinase inhibitor osimertinib in -mutant glioblastoma.

CNS Oncol 2019 11 15;8(3):CNS43. Epub 2019 Nov 15.

Division of Hematology & Oncology, Department of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.

Glioblastoma (GBM) is the most common primary malignant brain tumor in adults and carries a dismal prognosis. The gene is among the most commonly deranged genes in GBM and thus an important therapeutic target. We report the case of a young female with heavily pretreated -mutated GBM, for whom we initiated osimertinib, an oral, third-generation tyrosine kinase inhibitor that irreversibly inhibits EGFR and has significant brain penetration. We then review some of the main challenges in targeting EGFR, including lack of central nervous system penetration with most tyrosine kinase inhibitors, molecular heterogeneity of GBM and the need for enhanced specificity for the mutations relevant in GBM.
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http://dx.doi.org/10.2217/cns-2019-0014DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6880297PMC
November 2019

Clinical Utility of Plasma Cell-Free DNA in Adult Patients with Newly Diagnosed Glioblastoma: A Pilot Prospective Study.

Clin Cancer Res 2020 01 30;26(2):397-407. Epub 2019 Oct 30.

Division of Hematology/Oncology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania.

Purpose: The clinical utility of plasma cell-free DNA (cfDNA) has not been assessed prospectively in patients with glioblastoma (GBM). We aimed to determine the prognostic impact of plasma cfDNA in GBM, as well as its role as a surrogate of tumor burden and substrate for next-generation sequencing (NGS).

Experimental Design: We conducted a prospective cohort study of 42 patients with newly diagnosed GBM. Plasma cfDNA was quantified at baseline prior to initial tumor resection and longitudinally during chemoradiotherapy. Plasma cfDNA was assessed for its association with progression-free survival (PFS) and overall survival (OS), correlated with radiographic tumor burden, and subjected to a targeted NGS panel.

Results: Prior to initial surgery, GBM patients had higher plasma cfDNA concentration than age-matched healthy controls (mean 13.4 vs. 6.7 ng/mL, < 0.001). Plasma cfDNA concentration was correlated with radiographic tumor burden on patients' first post-radiation magnetic resonance imaging scan (ρ = 0.77, = 0.003) and tended to rise prior to or concurrently with radiographic tumor progression. Preoperative plasma cfDNA concentration above the mean (>13.4 ng/mL) was associated with inferior PFS (median 4.9 vs. 9.5 months, = 0.038). Detection of ≥1 somatic mutation in plasma cfDNA occurred in 55% of patients and was associated with nonstatistically significant decreases in PFS (median 6.0 vs. 8.7 months, = 0.093) and OS (median 5.5 vs. 9.2 months, = 0.053).

Conclusions: Plasma cfDNA may be an effective prognostic tool and surrogate of tumor burden in newly diagnosed GBM. Detection of somatic alterations in plasma is feasible when samples are obtained prior to initial surgical resection.
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http://dx.doi.org/10.1158/1078-0432.CCR-19-2533DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6980766PMC
January 2020

Negative prognostic impact of epidermal growth factor receptor copy number gain in young adults with isocitrate dehydrogenase wild-type glioblastoma.

J Neurooncol 2019 Nov 21;145(2):321-328. Epub 2019 Sep 21.

Division of Hematology and Oncology, Department of Medicine, University of Pennsylvania, 10th Floor, South Pavilion, 3400 Civic Center Blvd, Philadelphia, PA, 19104, USA.

Purpose: Young adults with isocitrate-dehydrogenase wild-type (IDH-WT) glioblastoma (GBM) represent a rare, understudied population compared to pediatric high-grade glioma, IDH-mutant GBM, or IDH-WT GBM in older patients. We aimed to explore the prognostic impact of epidermal growth factor receptor copy number gain (EGFR CN gain), one of the most common genetic alterations in IDH-WT glioma, in young adults with IDH-WT GBM.

Methods: We performed a retrospective cohort study of patients 18-45 years old with newly diagnosed, IDH-WT GBM whose tumors underwent next-generation sequencing at our institution between 2014 and 2018. The impact of EGFR CN gain on time to tumor progression (TTP) and overall survival (OS) was assessed. A validation cohort of patients 18-45 years old with IDH-WT GBM was analyzed from The Cancer Genome Atlas (TCGA).

Results: Ten of 28 patients (36%) from our institution had EGFR CN gain, which was associated with shorter TTP (median 6.5 vs. 11.9 months; p = 0.06) and OS (median 16.3 vs. 23.5 months; p = 0.047). The negative prognostic impact of EGFR CN gain on OS persisted in a multivariate model (HR 6.40, 95% CI 1.3-31.0, p = 0.02). In the TCGA cohort (N = 43), EGFR CN gain was associated with shorter TTP and worse OS, although these did not reach statistical significance (TTP, median 11.5 vs. 14.4 months, p = 0.18; OS, median 23.6 vs. 27.8 months; p = 0.18).

Conclusions: EGFR CN gain may be associated with inferior outcomes in young adults with newly diagnosed, IDH-WT GBM, suggesting a potential role for targeting EGFR in this population.
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http://dx.doi.org/10.1007/s11060-019-03298-6DOI Listing
November 2019

Molecular Neuropathology in Practice: Clinical Profiling and Integrative Analysis of Molecular Alterations in Glioblastoma.

Acad Pathol 2019 Jan-Dec;6:2374289519848353. Epub 2019 May 27.

Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.

Molecular profiling of glioblastoma has revealed complex cytogenetic, epigenetic, and molecular abnormalities that are necessary for diagnosis, prognosis, and treatment. Our neuro-oncology group has developed a data-driven, institutional consensus guideline for efficient and optimal workup of glioblastomas based on our routine performance of molecular testing. We describe our institution's testing algorithm, assay development, and genetic findings in glioblastoma, to illustrate current practices and challenges in neuropathology related to molecular and genetic testing. We have found that coordination of test requisition, tissue handling, and incorporation of results into the final pathologic diagnosis by the neuropathologist improve patient care. Here, we present analysis of promoter methylation and next-generation sequencing results of 189 patients, obtained utilizing our internal processes led by the neuropathology team. Our institutional pathway for neuropathologist-driven molecular testing has streamlined the management of glioblastoma samples for efficient return of results for incorporation of genomic data into the pathological diagnosis and optimal patient care.
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http://dx.doi.org/10.1177/2374289519848353DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6537274PMC
May 2019

Histologic, immunohistochemical, and molecular features of pituicytomas and atypical pituicytomas.

Acta Neuropathol Commun 2019 05 2;7(1):69. Epub 2019 May 2.

Department of Pathology and Laboratory Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA.

Pituicytoma is a rare, poorly characterized tumor of the sellar region that is thought to be derived from neurohypophyseal pituicytes. Resection of pituicytomas is often associated with significant morbidity including diabetes insipidus and panhypopituitarism. Most of the literature on this tumor exists as small case series or case reports. Here we describe a cohort of fourteen pituicytoma resections from eleven patients. The average follow-up on these cases is 3.7 years with some patients having over 10 years of follow-up data available in the electronic medical record. Pituicytomas were frequently misdiagnosed on pre-operative imaging, and surgical resection was associated with persistent endocrine abnormalities. Histologically, the tumors showed a range of morphologies from epithelioid to spindled. All tumors were positive for TTF-1 with variable immunostaining for other markers including GFAP, EMA, S100, SSTR2A, and synaptophysin. Within this cohort are two patients with atypical pituicytomas which showed increased cellularity, pleomorphism, mitoses and elevated Ki-67 proliferation indexes when compared to non-atypical pituicytomas. Next generation sequencing performed on three tumors revealed alterations in genes involved in the MAPK pathway. Additionally, immunohistochemical staining for phosphorylated-ERK was positive in the majority of tumors. Increased awareness of the neoplastic entity and identification of targetable mutations have the potential to decrease the morbidity associated with resection of pituicytomas.
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http://dx.doi.org/10.1186/s40478-019-0722-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6498683PMC
May 2019

Intraoperative Molecular Imaging with Second Window Indocyanine Green Facilitates Confirmation of Contrast-Enhancing Tissue During Intracranial Stereotactic Needle Biopsy: A Case Series.

World Neurosurg 2019 Jun 15;126:e1211-e1218. Epub 2019 Mar 15.

Department of Neurosurgery, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA. Electronic address:

Background: Stereotactic needle biopsy provides a minimally invasive option for the diagnosis of intracranial lesions but is limited by inconclusive diagnoses on frozen pathology. For rapid pathology, 5-aminovelunic acid and sodium fluorescein have previously demonstrated potential as diagnostic adjuvants. Stereotactic biopsy with near-infrared (NIR) fluorophores has not been reported. We identified 5 representative cases using NIR fluorescent dye indocyanine green (ICG) administered in a high dose, delayed manner.

Methods: Five patients underwent second window indocyanine green (SWIG)-guided stereotactic biopsy for diagnosis of suspected glioma or tumor recurrence. Up to 5 mg/kg ICG was administered approximately 24 hours prior to surgery. Biopsies were conducted in the standard fashion, targeting regions of suspected tumor using intraoperative frameless navigation. Samples were examined intraoperatively under standard visible light and for fluorescence using conventional NIR imaging platforms. Findings were correlated with frozen and final tumor pathology for all cases.

Results: A total of 10 biopsy specimens were obtained. Three did not fluoresce and did not demonstrate tumor on preliminary or final pathology, including a non-gadolinium-enhancing sample taken proximal to the final target. The remaining 7 fluoresced, of which 6 contained tumor and 1 contained necrosis. Fluorescence was also noted in a patient with radiation treatment effect. Overall fluorescence characteristics were highly concordant with preliminary and final diagnoses.

Conclusions: SWIG provides rapid intraoperative confirmation of pathologic brain tissue by permeating neoplastic or inflammatory brain tissue via a mechanism similar to that of gadolinium enhancement. SWIG-guided stereotactic biopsy can improve surgical efficiency by enhancing confidence in acquisition of target tissue.
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http://dx.doi.org/10.1016/j.wneu.2019.02.231DOI Listing
June 2019

Multiparametric magnetic resonance imaging in the assessment of anti-EGFRvIII chimeric antigen receptor T cell therapy in patients with recurrent glioblastoma.

Br J Cancer 2019 01 27;120(1):54-56. Epub 2018 Nov 27.

Department of Radiology, Division of Neuroradiology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA.

EGFRvIII targeted chimeric antigen receptor T (CAR-T) cell therapy has recently been reported for treating glioblastomas (GBMs); however, physiology-based MRI parameters have not been evaluated in this setting. Ten patients underwent multiparametric MRI at baseline, 1, 2 and 3 months after CAR-T therapy. Logistic regression model derived progression probabilities (PP) using imaging parameters were used to assess treatment response. Four lesions from "early surgery" group demonstrated high PP at baseline suggestive of progression, which was confirmed histologically. Out of eight lesions from remaining six patients, three lesions with low PP at baseline remained stable. Two lesions with high PP at baseline were associated with large decreases in PP reflecting treatment response, whereas other two lesions with high PP at baseline continued to demonstrate progression. One patient didn't have baseline data but demonstrated progression on follow-up. Our findings indicate that multiparametric MRI may be helpful in monitoring CAR-T related early therapeutic changes in GBM patients.
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http://dx.doi.org/10.1038/s41416-018-0342-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6325110PMC
January 2019

Histopathologic quantification of viable tumor versus treatment effect in surgically resected recurrent glioblastoma.

J Neurooncol 2019 Jan 16;141(2):421-429. Epub 2018 Nov 16.

Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.

Purpose: The prognostic impact of the histopathologic features of recurrent glioblastoma surgical specimens is unknown. We sought to determine whether key histopathologic characteristics in glioblastoma tumors resected after chemoradiotherapy are associated with overall survival (OS).

Methods: The following characteristics were quantified in recurrent glioblastoma specimens at our institution: extent of viable tumor (accounting for % of specimen comprised of tumor and tumor cellularity), mitoses per 10 high-power fields (0, 1-10, > 10), Ki-67 proliferative index (0-100%), hyalinization (0-6; none to extensive), rarefaction (0-6), hemosiderin (0-6), and % of specimen comprised of geographic necrosis (0-100%; converted to 0-6 scale). Variables associated with OS in univariate analysis, as well as age, eastern cooperative oncology group performance status (ECOG PS), extent of repeat resection, time from initial diagnosis to repeat surgery, and O-methylguanine-DNA methyltransferase promoter methylation, were included in a multivariable Cox proportional hazards model.

Results: 37 specimens were assessed. In a multivariate model, high Ki-67 proliferative index was the only histopathologic characteristic associated with worse OS following repeat surgery for glioblastoma (hazard ratio (HR) 1.3, 95% CI 1.1-1.5, p = 0.003). Shorter time interval from initial diagnosis to repeat surgery (HR 1.11, 95% CI 1.02-1.21, p = 0.016) and ECOG PS ≥ 2 (HR 4.19, 95% CI 1.72-10.21, p = 0.002) were also independently associated with inferior OS.

Conclusion: In patients with glioblastoma undergoing repeat resection following chemoradiotherapy, high Ki-67 index in the recurrent specimen, short time to recurrence, and poor PS are independently associated with worse OS. Histopathologic quantification of viable tumor versus therapy-related changes has limited prognostic influence.
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http://dx.doi.org/10.1007/s11060-018-03050-6DOI Listing
January 2019

SETD2 mutations in primary central nervous system tumors.

Acta Neuropathol Commun 2018 11 12;6(1):123. Epub 2018 Nov 12.

Department of Pathology and Laboratory Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA.

Mutations in SETD2 are found in many tumors, including central nervous system (CNS) tumors. Previous work has shown these mutations occur specifically in high grade gliomas of the cerebral hemispheres in pediatric and young adult patients. We investigated SETD2 mutations in a cohort of approximately 640 CNS tumors via next generation sequencing; 23 mutations were detected across 19 primary CNS tumors. Mutations were found in a wide variety of tumors and locations at a broad range of allele frequencies. SETD2 mutations were seen in both low and high grade gliomas as well as non-glial tumors, and occurred in patients greater than 55 years of age, in addition to pediatric and young adult patients. High grade gliomas at first occurrence demonstrated either frameshift/truncating mutations or point mutations at high allele frequencies, whereas recurrent high grade gliomas frequently harbored subclones with point mutations in SETD2 at lower allele frequencies in the setting of higher mutational burdens. Comparison with the TCGA dataset demonstrated consistent findings. Finally, immunohistochemistry showed decreased staining for H3K36me3 in our cohort of SETD2 mutant tumors compared to wildtype controls. Our data further describe the spectrum of tumors in which SETD2 mutations are found and provide a context for interpretation of these mutations in the clinical setting.
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http://dx.doi.org/10.1186/s40478-018-0623-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6231273PMC
November 2018

Folate Receptor Overexpression in Human and Canine Meningiomas-Immunohistochemistry and Case Report of Intraoperative Molecular Imaging.

Neurosurgery 2019 09;85(3):359-368

Department of Neurosurgery, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania.

Background: Meningiomas are well-encapsulated benign brain tumors and surgical resection is often curative. Nevertheless, this is not always possible due to the difficulty of identifying residual disease intraoperatively. We hypothesized that meningiomas overexpress folate receptor alpha (FRα), allowing intraoperative molecular imaging by targeting FRα with a near-infrared (NIR) dye.

Objective: To determine FRα expression in both human and canine meningioma cohorts to prepare for future clinical studies. Present a case study of a meningioma resection with intraoperative NIR fluorescence imaging.

Methods: Tissue samples of 27 human meningioma specimens and 7 canine meningioma specimens were immunohistochemically stained for FRα along with normal dura, skeletal muscle, and kidney tissue. We then enrolled a patient with a pituitary adenoma and tuberculum sella meningioma in a clinical trial in which the patient received an infusion of folate-linked, NIR fluorescent dye prior to surgery.

Results: In the cohort of human meningiomas, 9 WHO grade I, 12 grade II, and 6 grade III tumors were identified. Eighty-nine percent of WHO grade I, 67% of grade II, and 50% of grade III tumors overexpressed FRα. In the 7 canine meningioma samples, 100% stained positively for FRα. Both human and canine normal dura from autopsy samples demonstrated no evidence of FRα overexpression. In the case study, the meningioma demonstrated a high NIR signal-to-background-ratio of 4.0 and demonstrated strong FRα immunohistochemistry staining.

Conclusion: This study directly demonstrates FRα overexpression in both human and canine meningiomas. We also demonstrate superb intraoperative imaging of a meningioma using a FRα-targeting dye.
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http://dx.doi.org/10.1093/neuros/nyy356DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6904722PMC
September 2019

Epidermal Growth Factor Receptor Extracellular Domain Mutations in Glioblastoma Present Opportunities for Clinical Imaging and Therapeutic Development.

Cancer Cell 2018 07;34(1):163-177.e7

Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Center for Biomedical Image Computing and Analytics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Abramson Cancer Center, University of Pennsylvania, Philadelphia, PA 19104, USA. Electronic address:

We explored the clinical and pathological impact of epidermal growth factor receptor (EGFR) extracellular domain missense mutations. Retrospective assessment of 260 de novo glioblastoma patients revealed a significant reduction in overall survival of patients having tumors with EGFR mutations at alanine 289 (EGFR). Quantitative multi-parametric magnetic resonance imaging analyses indicated increased tumor invasion for EGFR mutants, corroborated in mice bearing intracranial tumors expressing EGFR and dependent on ERK-mediated expression of matrix metalloproteinase-1. EGFR tumor growth was attenuated with an antibody against a cryptic epitope, based on in silico simulation. The findings of this study indicate a highly invasive phenotype associated with the EGFR mutation in glioblastoma, postulating EGFR as a molecular marker for responsiveness to therapy with EGFR-targeting antibodies.
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http://dx.doi.org/10.1016/j.ccell.2018.06.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6424337PMC
July 2018

In vivo evaluation of EGFRvIII mutation in primary glioblastoma patients via complex multiparametric MRI signature.

Neuro Oncol 2018 07;20(8):1068-1079

Center for Biomedical Image Computing and Analytics, Perelman School of Medicine, University of Pennsylvania, Philadephia, Pennsylvania.

Background: Epidermal growth factor receptor variant III (EGFRvIII) is a driver mutation and potential therapeutic target in glioblastoma. Non-invasive in vivo EGFRvIII determination, using clinically acquired multiparametric MRI sequences, could assist in assessing spatial heterogeneity related to EGFRvIII, currently not captured via single-specimen analyses. We hypothesize that integration of subtle, yet distinctive, quantitative imaging/radiomic patterns using machine learning may lead to non-invasively determining molecular characteristics, and particularly the EGFRvIII mutation.

Methods: We integrated diverse imaging features, including the tumor's spatial distribution pattern, via support vector machines, to construct an imaging signature of EGFRvIII. This signature was evaluated in independent discovery (n = 75) and replication (n = 54) cohorts of de novo glioblastoma, and compared with the EGFRvIII status obtained through an assay based on next-generation sequencing.

Results: The cross-validated accuracy of the EGFRvIII signature in classifying the mutation status in individual patients of the independent discovery and replication cohorts was 85.3% (specificity = 86.3%, sensitivity = 83.3%, area under the curve [AUC] = 0.85) and 87% (specificity = 90%, sensitivity = 78.6%, AUC = 0.86), respectively. The signature was consistent with EGFRvIII+ tumors having increased neovascularization and cell density, as well as a distinctive spatial pattern involving relatively more frontal and parietal regions compared with EGFRvIII- tumors.

Conclusions: An imaging signature of EGFRvIII was found, revealing a complex, yet distinct macroscopic glioblastoma phenotype. By non-invasively capturing the tumor in its entirety, the proposed methodology can assist in evaluating the tumor's spatial heterogeneity, hence overcoming common spatial sampling limitations of tissue-based analyses. This signature can preoperatively stratify patients for EGFRvIII-targeted therapies, and potentially monitor dynamic mutational changes during treatment.
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http://dx.doi.org/10.1093/neuonc/noy033DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6280148PMC
July 2018

Radiomic MRI signature reveals three distinct subtypes of glioblastoma with different clinical and molecular characteristics, offering prognostic value beyond IDH1.

Sci Rep 2018 03 23;8(1):5087. Epub 2018 Mar 23.

Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.

The remarkable heterogeneity of glioblastoma, across patients and over time, is one of the main challenges in precision diagnostics and treatment planning. Non-invasive in vivo characterization of this heterogeneity using imaging could assist in understanding disease subtypes, as well as in risk-stratification and treatment planning of glioblastoma. The current study leveraged advanced imaging analytics and radiomic approaches applied to multi-parametric MRI of de novo glioblastoma patients (n = 208 discovery, n = 53 replication), and discovered three distinct and reproducible imaging subtypes of glioblastoma, with differential clinical outcome and underlying molecular characteristics, including isocitrate dehydrogenase-1 (IDH1), O-methylguanine-DNA methyltransferase, epidermal growth factor receptor variant III (EGFRvIII), and transcriptomic subtype composition. The subtypes provided risk-stratification substantially beyond that provided by WHO classifications. Within IDH1-wildtype tumors, our subtypes revealed different survival (p < 0.001), thereby highlighting the synergistic consideration of molecular and imaging measures for prognostication. Moreover, the imaging characteristics suggest that subtype-specific treatment of peritumoral infiltrated brain tissue might be more effective than current uniform standard-of-care. Finally, our analysis found subtype-specific radiogenomic signatures of EGFRvIII-mutated tumors. The identified subtypes and their clinical and molecular correlates provide an in vivo portrait of phenotypic heterogeneity in glioblastoma, which points to the need for precision diagnostics and personalized treatment.
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http://dx.doi.org/10.1038/s41598-018-22739-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5865162PMC
March 2018

A single dose of peripherally infused EGFRvIII-directed CAR T cells mediates antigen loss and induces adaptive resistance in patients with recurrent glioblastoma.

Sci Transl Med 2017 07;9(399)

Cellular Immunotherapy Program, Cancer Center and Department of Medicine, Massachusetts General Hospital, Boston, MA 02129, USA.

We conducted a first-in-human study of intravenous delivery of a single dose of autologous T cells redirected to the epidermal growth factor receptor variant III (EGFRvIII) mutation by a chimeric antigen receptor (CAR). We report our findings on the first 10 recurrent glioblastoma (GBM) patients treated. We found that manufacturing and infusion of CAR-modified T cell (CART)-EGFRvIII cells are feasible and safe, without evidence of off-tumor toxicity or cytokine release syndrome. One patient has had residual stable disease for over 18 months of follow-up. All patients demonstrated detectable transient expansion of CART-EGFRvIII cells in peripheral blood. Seven patients had post-CART-EGFRvIII surgical intervention, which allowed for tissue-specific analysis of CART-EGFRvIII trafficking to the tumor, phenotyping of tumor-infiltrating T cells and the tumor microenvironment in situ, and analysis of post-therapy EGFRvIII target antigen expression. Imaging findings after CART immunotherapy were complex to interpret, further reinforcing the need for pathologic sampling in infused patients. We found trafficking of CART-EGFRvIII cells to regions of active GBM, with antigen decrease in five of these seven patients. In situ evaluation of the tumor environment demonstrated increased and robust expression of inhibitory molecules and infiltration by regulatory T cells after CART-EGFRvIII infusion, compared to pre-CART-EGFRvIII infusion tumor specimens. Our initial experience with CAR T cells in recurrent GBM suggests that although intravenous infusion results in on-target activity in the brain, overcoming the adaptive changes in the local tumor microenvironment and addressing the antigen heterogeneity may improve the efficacy of EGFRvIII-directed strategies in GBM.
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http://dx.doi.org/10.1126/scitranslmed.aaa0984DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5762203PMC
July 2017

Non-invasive detection of 2-hydroxyglutarate in IDH-mutated gliomas using two-dimensional localized correlation spectroscopy (2D L-COSY) at 7 Tesla.

J Transl Med 2016 Sep 22;14(1):274. Epub 2016 Sep 22.

Department of Cellular and Molecular Biology, University of Liverpool, Liverpool, UK.

Background: Mutations in the isocitrate dehydrogenase enzyme are present in a majority of lower-grade gliomas and secondary glioblastomas. This mis-sense mutation results in the neomorphic reduction of isocitrate dehydrogenase resulting in an accumulation of the "oncometabolite" 2-hydroxyglutarate (2HG). Detection of 2HG can thus serve as a surrogate biomarker for these mutations, with significant translational implications including improved prognostication. Two dimensional localized correlated spectroscopy (2D L-COSY) at 7T is a highly-sensitive non-invasive technique for assessing brain metabolism. This study aims to assess tumor metabolism using 2D L-COSY at 7T for the detection of 2HG in IDH-mutant gliomas.

Methods: Nine treatment-naïve patients with suspected intracranial neoplasms were scanned at 7T MRI/MRS scanner using the 2D L-COSY technique. 2D-spectral processing and analyses were performed using a MATLAB-based reconstruction algorithm. Cross and diagonal peak volumes were quantified in the 2D L-COSY spectra and normalized with respect to the creatine peak at 3.0 ppm and quantified data were compared with previously-published data from six normal subjects. Detection of 2HG was validated using findings from immunohistochemical (IHC) staining in patients who subsequently underwent surgical resection.

Results: 2HG was detected in both of the IDH-mutated gliomas (grade III Anaplastic Astrocytoma and grade II Diffuse Astrocytoma) and was absent in IDH wild-type gliomas and in a patient with breast cancer metastases. 2D L-COSY was also able to resolve complex and overlapping resonances including phosphocholine (PC) from glycerophosphocholine (GPC), lactate (Lac) from lipids and glutamate (Glu) from glutamine (Gln).

Conclusions: This study demonstrates the ability of 2D L-COSY to unambiguously detect 2HG in addition to other neuro metabolites. These findings may aid in establishing 2HG as a biomarker of malignant progression as well as for disease monitoring in IDH-mutated gliomas.
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http://dx.doi.org/10.1186/s12967-016-1035-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5034563PMC
September 2016
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