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Advanced molecular and pathophysiologic characterization of primary central nervous system lymphoma (PCNSL) has revealed insights into promising targeted therapeutic approaches. Medical imaging plays a fundamental role in PCNSL diagnosis, staging, and response assessment. Institutional imaging variation and inconsistent clinical trial reporting diminishes the reliability and reproducibility of clinical response assessment. In this context, we aimed to: (1) critically review the use of advanced positron emission tomography (PET) and magnetic resonance imaging (MRI) in the setting of PCNSL; (2) provide results from an international survey of clinical sites describing the current practices for routine and advanced imaging, and (3) provide biologically based recommendations from the International PCNSL Collaborative Group (IPCG) on adaptation of standardized imaging practices. The IPCG provides PET and MRI consensus recommendations built upon previous recommendations for standardized brain tumor imaging protocols (BTIP) in primary and metastatic disease. A biologically integrated approach is provided to addresses the unique challenges associated with the imaging assessment of PCNSL. Detailed imaging parameters facilitate the adoption of these recommendations by researchers and clinicians. To enhance clinical feasibility, we have developed both “ideal” and “minimum standard” protocols at 3T and 1.5T MR systems that will facilitate widespread adoption.

BACKGROUND: Noninvasively differentiating therapy-induced pseudoprogression from recurrent disease in patients with glioblastoma is prospectively difficult due to the current lack of a biologically specific imaging metric. Ferumoxytol iron oxide nanoparticle MRI contrast characterizes innate immunity mediated neuroinflammation; therefore, we hypothesized that combined ferumoxytol and gadolinium enhanced MRI could serve as a biomarker of glioblastoma pseudoprogression. METHODS: In this institutional review board-approved, retrospective study, we analyzed ferumoxytol and gadolinium contrast enhanced T1-weighted 3T MRI in 45 patients with glioblastoma over multiple clinical timepoints. Isocitrate dehydrogenase 1 (IDH-1) mutational status was characterized by exome sequencing. Sum of products diameter measurements were calculated according to Response Assessment in Neuro-Oncology criteria from both gadolinium and ferumoxytol enhanced sequences. Enhancement mismatch was calculated as the natural log of the ferumoxytol to gadolinium sum of products diameter ratio. Analysis of variance and Student’s t-test assessed differences in mismatch ratios. P-value

Overexpression of O6-methylguanine DNA methyltransferase (MGMT) contributes to brain tumor chemo-resistance. Previously we found that non-cytotoxic radiation improved anti-MGMT Morpholino Oligonucleotides (AMONs) delivery to reduce MGMT levels in subcutaneous tumor xenografts. Here we evaluated if radiation enhanced the delivery of intravenous (IV) AMONs to rat brain and improved chemo-radiation therapy (CRT) efficacy using rat models of human brain tumors. Athymic nude rats bearing orthotopic cerebellar D283 medulloblastoma or intracerebral H460 non-small cell lung carcinoma (NSCLC) brain metastasis xenografts were used. The impact of cranial radiation on delivery of IV 3’-carboxyfluorescein labeled oligonucleotides across the neurovascular unit was evaluated using confocal microscopy. We found that high brain parencymal fluorescence in radiated compared to non-radiated rats. MGMT protein silencing was assessed by immunoblot in tumor-bearing rats 3 d after 2 Gy cranial radiation alone or followed in 1 d by IV AMONs (10.5 mg/kg). Radiation followed by AMONs reduced MGMT expression by 50% in both xenograft models. To evaluate efficacy, tumor-bearing rats received one dose of 2 Gy radiation plus oral temozolomide (20 mg/kg x 4d) with or without IV AMONs. AMONs concurrent with CRT reduced tumor volumes in the medulloblastoma model (p=0.012), and a similar trend was found in the NSCLC brain metastasis model. In conclusion, we demonstrate the use of a single clinically relevant radiation dose fraction to guide and enhance the delivery of oligonucleotides into brain tumor xenograft models to reduce MGMT levels and improve CRT efficacy.

BACKGROUND Treatment of glioblastoma multiforme (GBM) is complicated by extensive tumor heterogeneity. We hypothesize that transcriptomic analysis of brain tumor regions with different magnetic resonance imaging (MRI) characteristics will define specific biological processes, providing a non-invasive method for tumor characterization and stratification. METHODS Previously at the University of California San Francisco, treatment naïve GBM tissue from gadolinium contrast enhancing lesion (CEL) and non-enhancing lesion (NCEL) regions were stereotactically sampled; prior to resection, relative cerebral blood volume (rCBV) and apparent diffusion coefficient (ADC) were determined. The tissue samples were characterized by immunohistochemistry and assessed for gene expression by microarray analysis. We correlated gene expression patterns in the CEL, NCEL, and non-tumor gliotic brain samples with multimodal physiological imaging metrics and immunohistochemical phenotypes. Gene expression networks were probed using Gene Set Enrichment Analysis. Key immunologic genes were examined individually. RESULTS Samples with differing MRI and histological phenotypes demonstrated transcriptomic variance reflecting distinct biological networks. We found significant differences in immune pathways, with immune gene signature prominent in CEL areas, moderate in NCEL and low in gliotic non-tumor brain. Within homogenously enhancing areas of CEL and NCEL there was underlying heterogeneity detectable by variable rCBV, ADC and histological phenotypes, which correlate with differing gene expression profiles indicative of biological and immunological tumor microenvironments. Increasing rCBV was correlated with an anti-inflammatory immune response in the CEL and a pro-inflammatory immune response in the NCEL. ADC was negatively correlated with cell cycle and immune networks in CEL, while NCEL ADC was positively correlated with immune processes. GBM samples with the mesenchymal molecular subtype had the greatest immune response. CONCLUSIONS Multimodal MRI features identify regionally diverse transcriptomic-based biological and immunological phenotypes in GBM. We propose that imaging genomics provides a technique for localizing biological processes and tumor immune microenvironments across space and time in GBM.

OBJECTIVE Personalized treatment strategies in Glioblastoma multiforme (GBM) has been hampered by intra-tumoral heterogeneity. The goals of this study were to (1) determine the impact of intra-tumoral heterogeneity on established predictive and prognostic transcriptional signatures in human GBM, and (2) develop methods to mitigate the impact of tissue heterogeneity on transcriptomic-based patient stratification. METHODS We analyzed transcriptional profiles of GBM histological structures from the open-source Ivy Glioblastoma Atlas Project. To generate these data, infiltrative tumor, leading edge, cellular tumor [CT], perinecrotic zones, pseudopalisading cells, hyperplastic blood vessels and microvascular proliferation were microdissected from 34 newly diagnosed GBM and underwent RNA sequencing. Data from The Cancer Genome Atlas were used for validation. Principle component analysis, network analysis and gene set enrichment analysis were used to probe gene expression patterns. RESULTS Distinct biological networks were enriched in each tumor histological structure. Classification of patients into GBM molecular subtypes varied based on the structure assessed, with many patients classified as every subtype depending on the structure analyzed. Using only CT to classify subtypes, we identified biologically unique patterns suggesting that proneural and mesenchymal tumors may be more sensitive to chemoradiotherapy and immunotherapy, respectively. Survival outcome predicted by an established multigene panel was confounded by histologic structure. Utilizing CT transcriptomics we developed a novel survival prediction gene signature that identified the highest-risk GBM patients in both CT and bulk tissue gene expression profiles. CONCLUSIONS Histologic structures contribute to intra-tumoral heterogeneity in GBM. Using mixed-structure biopsy samples could incorrectly subtype tumors and produce invalid patient stratification. Limiting transcriptomic analysis to the CT allowed us to develop a new survival prediction gene signature that appears accurate even in mixed tissue samples. The biological patterns uncovered in the subtypes and risk-stratified groups have important implications for guiding the development of precision medicine in GBM.

While the use of targeted therapies, particularly radiosurgery, has broadened therapeutic options for CNS metastases, patients respond minimally and prognosis remains poor. The inability of many systemic chemotherapeutic agents to penetrate the blood-brain barrier (BBB) has limited their use and allowed brain metastases to become a burgeoning clinical challenge. Adequate preclinical models that appropriately mimic the metastatic process, the BBB, and blood-tumor barriers (BTB) are needed to better evaluate therapies that have the ability to enhance delivery through or penetrate into these barriers and to understand the mechanisms of resistance to therapy. The heterogeneity among and within different solid tumors and subtypes of solid tumors further adds to the difficulties in determining the most appropriate treatment approaches and methods of laboratory and clinical studies. This review article discusses therapies focused on prevention and treatment of CNS metastases, particularly regarding the BBB, and the challenges and opportunities these therapies present.

Background. Diagnosis of pseudoprogression in patients with glioblastoma multiforme (GBM) is limited by Response Assessment in Neuro-Oncology (RANO) criteria to 3 months after chemoradiotherapy (CRT). Frequency of pseudoprogression occurring beyond this time limit was determined. Survival comparison was made between pseudoprogression and true progression patients as determined by using perfusion magnetic resonance imaging with ferumoxytol (p-MRI-Fe). Methods. Fifty-six patients with GBM who demonstrated conventional findings concerning for progression of disease post CRT were enrolled in institutional review board-approved MRI protocols. Dynamic susceptibility-weighted contrast-enhanced p-MRI-Fe was used to distinguish true progression from pseudoprogression using relative cerebral blood volume (rCBV) values. rCBV of 1.75 was assigned as the cutoff value. Participants were followed up using RANO criteria, and survival data were analyzed. Results. Twenty-seven participants (48.2%) experienced pseudoprogression. Pseudoprogression occurred later than 3 months post CRT in 8 (29.6%) of these 27 participants (ie, 8 [14.3%] of the 56 patients meeting the inclusion criteria). Overall survival was significantly longer in participants with pseudoprogression (35.2 months) compared with those who never experienced pseudoprogression (14.3 months; P , .001). Conclusions. Pseudoprogression presented after 3 months post CRT in a considerable portion of patients with GBM, which raises doubts about the value of the 3-month time limit of the RANO criteria. Accurate rCBV measurement (eg, p-MRI-Fe) is suggested when there are radiographical concerns about progression of disease in GBM patients, regardless of any time limit. Pseudoprogression correlates with significantly better survival outcomes.

Platinum based chemotherapies are essential for treating certain pediatric cancers, but cause significant ototoxicity in many patients. While patients with localized medulloblastoma have an overall survival of more than 80%, many survivors develop hearing loss requiring lifelong use of hearing aids and have markedly decreased long term quality of life. In a series of 41 pediatric patients at OHSU treated for standard risk medulloblastoma, 7 (17%) developed ototoxicity after the second cisplatin cycle and 26 (63%) had hearing loss following the fourth cycle. Cisplatin dose reductions were required for 24 (59%) patients due to hearing loss. At the end of treatment 32/38 (84%) had hearing loss and 12 required hearing aids. Two randomized phase III trials, one conducted by the Children’s Oncology Group (COG ACCL0431) and the other by the Société Internationale d’Oncologie Pédiatrique - Epithelial Liver Tumor Study Group (SIOPEL 6), have demonstrated the efficacy of sodium thiosulfate (STS) in protecting children from cisplatin-induced hearing loss. Both studies showed no impact of STS on progression-free or overall survival in patients with localized disease (Freyer, 2017; Brock, 2017). In the COG study medulloblastoma subgroup, hearing loss was seen in 33% (3/9) of those treated with STS vs 100% (10/10) in the observation arm. We conclude that STS may safely and effectively protect against hearing loss in medulloblastoma patients with localized disease.

CLIN-NEURO-COGNITIVE NC-02. ASSESSING NEURO-COGNITIVE STATUS IN NEWLY PRESENTING PATIENTS WITH SUPRATENTORIAL INTRACRANIAL TUMOURS. Jennifer L. Scotland1, Ian R. Whittle1, and Ian J. Deary2; University of Edinburgh, Edinburgh, United Kingdom; Centre for Cognitive Ageing and Cognitive Epidemiology, Dept. of Psychology, University of Edinburgh, Edinburgh, United Kingdom INTRODUCTION: Neurocognitive endpoints are increasingly included in clinical trials in neuro-oncological settings (Meyers & Brown, 2006). There is a need to identify short, repeatable measures of cognition that are sensitive to impairment in this group. Previous authors have proposed such batteries. METHODS: Newly presenting patients with a radiological diagnosis of any intracranial tumour (n 1⁄4 118) were assessed, prior to any surgical intervention, on a number of standardised cognitive and other measures as part of a larger study (Scotland et al., 2012). Their performance was compared with that of patients admitted for elective spinal surgery (n 1⁄4 85) and a healthy control group (n 1⁄4 80). RESULTS: Analysis of covariance compared the performance of the three groups. Age, sex, and National Adult Reading Test score (used to assess premorbid function) were the covariates. Patients with intracranial tumours performed significantly worse on the majority of the tests. The intracranial tumour cohort had significantly lower scores than did the spinal surgery and healthy control groups on the following measures: immediate and delayed memory (Rey Auditory Verbal Learning Test, RAVLT; p , 0.001); Trail Making Test Part B (p , 0.001); digit-symbol coding (p , 0.001); and verbal fluency (Controlled Oral Word Association Test, COWAT; p 1⁄4 0.002 and p , 0.001, respectively). There was a moderate-to-large effect size in the participant group for all tests. DISCUSSION/CONCLUSIONS: The RAVLT, Trail Making Test Part B, and COWAT are sensitive measures of cognitive impairment in patients with brain tumours and support Meyers & Brown’s (2006) proposal for the inclusion of these tests in clinical trials that have neurocognitive endpoints. The verbal fluency test, in particular, has a number of potential advantages for use in neuro-oncological settings, given that it can be completed by patients with focal motor deficits and is available in alternate forms to reduce practice effects. NC-03. A STANDARD NEUROLINGUISTIC APPROACH TO

We used dynamic MRI to evaluate the effects of monoclonal antibodies targeting brain tumor vasculature. Female athymic rats with intracerebral human tumor xenografts were untreated or treated with intetumumab, targeting α(V)-integrins, or bevacizumab, targeting vascular endothelial growth factor (n = 4-6 per group). Prior to treatment and at 1, 3, and 7 days after treatment, we performed standard MRI to assess tumor volume, dynamic susceptibility-contrast MRI with the blood-pool iron oxide nanoparticle ferumoxytol to evaluate relative cerebral blood volume (rCBV), and dynamic contrast-enhanced MRI to assess tumor vascular permeability. Tumor rCBV increased by 27 ± 13% over 7 days in untreated rats; intetumumab increased tumor rCBV by 65 ± 10%, whereas bevacizumab reduced tumor rCBV by 31 ± 10% at 7 days (P < .001 for group and day). Similarly, intetumumab increased brain tumor vascular permeability compared with controls at 3 and 7 days after treatment, whereas bevacizumab decreased tumor permeability within 24 hours (P = .0004 for group, P = .0081 for day). All tumors grew over the 7-day assessment period, but bevacizumab slowed the increase in tumor volume on MRI. We conclude that the vascular targeting agents intetumumab and bevacizumab had diametrically opposite effects on dynamic MRI of tumor vasculature in rat brain tumor models. Targeting α(V)-integrins increased tumor vascular permeability and blood volume, whereas bevacizumab decreased both measures. These findings have implications for chemotherapy delivery and antitumor efficacy.

Brain tumor treatment is limited by a lack of effective therapies and inadequate drug delivery across the blood-brain barrier (BBB). The antibody-drug conjugate (ADC) ABT-414 (AbbVie Pharmaceuticals) couples the toxin monomethyl auristatin F to a humanized monoclonal antibody targeting overexpressed and mutant epidermal growth factor receptor (EGFR). ABT-414 inhibits tumor growth in multiple preclinical subcutaneous tumor models, but its efficacy in brain tumors may be reduced by inadequate delivery of the ADC across the BBB after intravenous administration. We have shown that intra-arterial infusion of hypertonic mannitol transiently disrupts the BBB to safely increase delivery of chemotherapy, antibodies and nanoparticles to the brain. We hypothesized that BBB disruption (BBBD) would improve ABT-414 efficacy in rat models of human brain tumors. Using intracerebral xenografts of U87MG human glioma cells expressing EGFRvIII (U87-EGFRv3), we found that ABT-414 is highly effective when delivered with BBBD as a single dose at concentrations as low as 1 mg/kg. One week after treatment, the tumor volume of treated animals was 0.47 ± 0.27mm3 (n=3) relative to controls 31.1 ± 8.3mm3 (n=10) (P

Treatment of Glioblastoma Multiforme (GBM) with temozolomide (TMZ) plus radiotherapy [chemoradiotherapy (CRT)] can induce the inflammatory reaction known as pseudoprogression in a large proportion of patients. Pseudoprogression (Ps) is associated with increased survival; however, it is difficult to differentiate Ps from true tumor progression on conventional magnetic resonance imaging (MRI), and the time course, true incidence, and mechanisms to increase or decrease Ps are not known. This IRB-approved retrospective study determined the rate and timing of pseudoprogression and the survival of GBM patients who received adjuvant TMZ until tumor progression. METHODS: Patients with biopsy-proven newly diagnosed GBM at Oregon Health and Science University from January 2006 to June 2012 after standard CRT received adjuvant TMZ until tumor progression. Diagnosis of Ps was made using dynamic perfusion MRI with ferumoxytol (a nanoparticle blood pool agent) in comparison to RANO criteria. Patients received bevacizumab (Avastin) anti-VEGF monoclonal antibody upon tumor progression. RESULTS: In our single institutional experience with 68 consecutive patients, the overall median survival was 19.9 months. Perfusion MRI revealed Ps in 24 (35%) patients. Pseudoprogression developed in 12.5% of our patient population at time points beyond the arbitrary 3 month cutoff defined by the RANO criteria. Survival was significantly greater in patients with Ps than in patients without Ps, 34.7 months versus 13.4 months, respectively. The subgroup of patients with Ps and hypermethylated MGMT had longer survival than patients with Ps and nonhypermethylated MGMT: 54.1 versus 28.2 months respectively. The patients that never experienced Ps had poor survival despite receiving bevacizumab. DISCUSSION: Ps is associated with better outcome, especially if concurs with MGMT promoter methylation. This study emphasizes the importance of differentiating tumor progression and Ps for treatment decisions and survival prediction, and emphasizes that ferumoxytol perfusion MRI may help as a diagnostic tool. Our results compare favorably with the recent report of the AVAglio trial of bevacizumab in GBM. Ps was diagnosed in only 9.3% of patients within 1 month after CRT in the AVAglio trial. Usage of upfront bevacizumab in the AVAglio trial further decreased the rate of Ps to 2.2%. The decrease in the beneficial inflammatory effects of Ps may explain why patients treated with upfront bevacizumab show increased progression-free survival without an increased overall survival benefit. Altogether these results demonstrate a need to reevaluate the RANO criteria in GBM.

To determine the efficacy of methotrexate and/or rituximab in a CNS lymphoma model and to evaluate MRI modalities for monitoring efficacy, we inoculated female athymic nude rats (rnu/rnu) intracerebrally with human MC116 B-lymphoma cells. Between days 16 and 26, rats were randomized to receive intravenous (IV) treatment with (1) saline (controls, n = 15), (2) methotrexate 1,000 mg/m(2) (n = 6), (3) rituximab 375 mg/m(2) (n = 6), or (4) rituximab plus methotrexate (n = 6). T2/fluid-attenuated inversion recovery (FLAIR) and gadolinium contrast-enhanced T1 MRI sequences were performed prior to and 1 week after treatment. IV rituximab gave an objective tumor response in four of six animals (>50% reduction in tumor volume comparing pre- and posttreatment T2/FLAIR MRI) and resulted in stable disease (50%-125% of baseline) in another animal. The percent change in tumor volume on T2/FLAIR images was significantly different in the control versus rituximab group (p = 0.0051). IV methotrexate slowed tumor growth, compared to controls, but only one of six animals had an objective response. In untreated controls, tumor histological volumes correlated well with T2/FLAIR or contrast-enhanced T1 images (r = 0.877). In the treatment groups, T2/FLAIR correlation was good, but the gadolinium-enhanced T1 MRI was not significantly correlated with histology (r = 0.19). The MC116 CNS lymphoma model seems valuable for preclinical testing of efficacy and toxicity of treatment regimens. IV rituximab was highly effective, but methotrexate was only minimally effective. T2/FLAIR was superior to contrast-enhanced T1 for monitoring efficacy.