The cytokine Meteorin-like inhibits anti-tumor CD8+ T cell responses by disrupting mitochondrial function.

Tumor-infiltrating lymphocyte (TIL) hypofunction contributes to the progression of advanced cancers and is a frequent target of immunotherapy. Emerging evidence indicates that metabolic insufficiency drives T cell hypofunction during tonic stimulation, but the signals that initiate metabolic reprogramming in this context are largely unknown. Here, we found that Meteorin-like (METRNL), a metabolically active cytokine secreted by immune cells in the tumor microenvironment (TME), induced bioenergetic failure of CD8+ T cells. METRNL was secreted by CD8+ T cells during repeated stimulation and acted via both autocrine and paracrine signaling. Mechanistically, METRNL increased E2F-peroxisome proliferator-activated receptor delta (PPARδ) activity, causing mitochondrial depolarization and decreased oxidative phosphorylation, which triggered a compensatory bioenergetic shift to glycolysis. Metrnl ablation or downregulation improved the metabolic fitness of CD8+ T cells and enhanced tumor control in several tumor models, demonstrating the translational potential of targeting the METRNL-E2F-PPARδ pathway to support bioenergetic fitness of CD8+ TILs.

18F-FSPG PET/CT Imaging of System xC- Transporter Activity in Patients with Primary and Metastatic Brain Tumors.

Background The PET tracer (4S)-4-(3-[18F]fluoropropyl)-l-glutamate (18F-FSPG) targets the system xC- cotransporter, which is overexpressed in various tumors. Purpose To assess the role of 18F-FSPG PET/CT in intracranial malignancies. Materials and Methods Twenty-six patients (mean age, 54 years ± 12; 17 men; 48 total lesions) with primary brain tumors (n = 17) or brain metastases (n = 9) were enrolled in this prospective, single-center study (ClinicalTrials.gov identifier: NCT02370563) between November 2014 and March 2016. A 30-minute dynamic brain 18F-FSPG PET/CT scan and a static whole-body (WB) 18F-FSPG PET/CT scan at 60-75 minutes were acquired. Moreover, all participants underwent MRI, and four participants underwent fluorine 18 (18F) fluorodeoxyglucose (FDG) PET imaging. PET parameters and their relative changes were obtained for all lesions. Kinetic modeling was used to estimate the 18F-FSPG tumor rate constants using the dynamic and dynamic plus WB PET data. Imaging parameters were correlated to lesion outcomes, as determined with follow-up MRI and/or pathologic examination. The Mann-Whitney U test or Student t test was used for group mean comparisons. Receiver operating characteristic curve analysis was used for performance comparison of different decision measures. Results 18F-FSPG PET/CT helped identify all 48 brain lesions. The mean tumor-to-background ratio (TBR) on the whole-brain PET images at the WB time point was 26.6 ± 24.9 (range: 2.6-150.3). When 18F-FDG PET was performed, 18F-FSPG permitted visualization of non-18F-FDG-avid lesions or allowed better lesion differentiation from surrounding tissues. In participants with primary brain tumors, the predictive accuracy of the relative changes in influx rate constant Ki and maximum standardized uptake value to discriminate between poor and good lesion outcomes were 89% and 81%, respectively. There were significant differences in the 18F-FSPG uptake curves of lesions with good versus poor outcomes in the primary brain tumor group (P < .05) but not in the brain metastases group. Conclusion PET/CT imaging with (4S)-4-(3-[18F]fluoropropyl)-l-glutamate (18F-FSPG) helped detect primary brain tumors and brain metastases with a high tumor-to-background ratio. Relative changes in 18F-FSPG uptake with multi-time-point PET appear to be helpful in predicting lesion outcomes. Clinical trial registration no. NCT02370563 © RSNA, 2022 Online supplemental material is available for this article.

Focused ultrasound: growth potential and future directions in neurosurgery.

Over the past two decades, vast improvements in focused ultrasound (FUS) technology have made the therapy an exciting addition to the neurosurgical armamentarium. In this time period, FUS has gained US Food and Drug Administration (FDA) approval for the treatment of two neurological disorders, and ongoing efforts seek to expand the lesion profile that is amenable to ultrasonic intervention. In the following review, we highlight future applications for FUS therapy and compare its potential role against established technologies, including deep brain stimulation and stereotactic radiosurgery. Particular attention is paid to tissue ablation, blood-brain-barrier opening, and gene therapy. We also address technical and infrastructural challenges involved with FUS use and summarize the hurdles that must be overcome before FUS becomes widely accepted in the neurosurgical community.

Local control of brain metastases with osimertinib alone in patients with EGFR-mutant non-small cell lung cancer.

PURPOSE: Although osimertinib has excellent intracranial activity in metastatic non-small cell lung cancer (NSCLC) with exon 19 deletion or L858R EGFR alterations, measures of local control of brain metastases are less well-reported. We describe lesion-level outcomes of brain metastases treated with osimertinib alone. METHODS: We retrospectively reviewed patients with EGFR-mutant NSCLC with untreated brain metastasis measuring ≥ 5 mm at the time of initiating osimertinib. Cumulative incidence of local recurrence in brain (LRiB) was calculated with death as a competing risk, and univariable and multivariable analyses were conducted to identify factors associated with LRiB. RESULTS: We included 284 brain metastases from 37 patients. Median follow-up was 20.1 months. On initial MRI after starting osimertinib, patient-level response was complete response (CR) in 11 (15%), partial response (PR) in 33 (45%), stable disease (SD) in 18 (25%) and progressive disease (PD) in 11 (15%). The 1-year cumulative incidence of LRiB was 14% (95% CI 9.9-17.9) and was significantly different in patients with a CR (0%), PR (4%), and SD (11%; p = 0.02). Uncontrolled primary tumor (adjusted hazard ratio [aHR] 3.78, 95% CI 1.87-7.66; p < 0.001), increasing number of prior systemic therapies (aHR 2.12, 95% CI 1.49-3.04; p < 0.001), and higher ECOG score (aHR 7.8, 95% CI 1.99-31.81; p = 0.003) were associated with LRiB. CONCLUSIONS: Although 1-year cumulative incidence of LRiB is < 4% with a CR or PR, 1-year cumulative incidence of LRiB is over 10% for patients with less than a PR to osimertinib on initial MRI. These patients should be followed closely for need for additional treatment such as stereotactic radiosurgery.

Stereotactic radiosurgery for trigeminal neuralgia secondary to tumor: a single-institution retrospective series.

OBJECTIVE: Trigeminal neuralgia (TN) secondary to tumor represents a rare and diverse entity, and treatment for secondary TN remains controversial. This report reviews a single institution's experience in treating secondary TN with stereotactic radiosurgery (SRS) and focuses on the durability of pain relief with respect to various treatment targets, i.e., the trigeminal nerve, offending tumor, or both. METHODS: Between the years 2009 and 2021, 21 patients with TN secondary to benign (n = 13) or malignant (n = 8) tumors underwent SRS. Barrow Neurological Institute (BNI) pain intensity scale scores were collected from patient electronic medical records at baseline, initial follow-up, and 1 and 3 years post-SRS. The interval change in BNI scale score (ΔBNI) at the various follow-up time points was also calculated to assess the durability of pain relief following SRS. RESULTS: The median follow-up period was 24 (range 0.5-155) months. Five patients (24%) received treatment to the trigeminal nerve only, 10 (48%) received treatment to the tumor only, and 6 (29%) had treatment to both the nerve and tumor. The overall radiation dosage ranged from 14 to 60 Gy delivered in 1-5 fractions, with a median overall dose of 26 Gy. The median dose to the tumor was 22.5 (range 14-35) Gy, delivered in 1-5 fractions. Of the treatments targeting the tumor, 25% were delivered in a single fraction with doses ranging from 14 to 20 Gy, 60% were delivered in 3 fractions with doses ranging from 18 to 27 Gy, and 15% were delivered in 5 fractions with doses ranging from 25 to 35 Gy. The most common dose regimen for tumor treatment was 24 Gy in 3 fractions. The median biologically effective dose (with an assumed alpha/beta ratio of 10 [BED10]) for tumor treatments was 43.1 (range 13.3-60.0) Gy. There was a significant difference in the proportion of patients with recurrent pain (ΔBNI score ≥ 0) at the time of last follow-up across the differing SRS treatment targets: trigeminal nerve only, tumor only, or both (p = 0.04). At the time of last follow-up, the median ΔBNI score after SRS to the nerve only was -1, 0 after SRS to tumor only, and -2 after SRS to both targets. CONCLUSIONS: SRS offers clinical symptomatic benefit to patients with TN secondary to tumor. For optimal pain relief and response durability, treatment targeting both the tumor and the trigeminal nerve appears to be most advantageous.

An integrated risk model stratifying seizure risk following brain tumor resection among seizure-naive patients without antiepileptic prophylaxis.

OBJECTIVE: The natural history of seizure risk after brain tumor resection is not well understood. Identifying seizure-naive patients at highest risk for postoperative seizure events remains a clinical need. In this study, the authors sought to develop a predictive modeling strategy for anticipating postcraniotomy seizures after brain tumor resection. METHODS: The IBM Watson Health MarketScan Claims Database was canvassed for antiepileptic drug (AED)- and seizure-naive patients who underwent brain tumor resection (2007-2016). The primary event of interest was short-term seizure risk (within 90 days postdischarge). The secondary event of interest was long-term seizure risk during the follow-up period. To model early-onset and long-term postdischarge seizure risk, a penalized logistic regression classifier and multivariable Cox regression model, respectively, were built, which integrated patient-, tumor-, and hospitalization-specific features. To compare empirical seizure rates, equally sized cohort tertiles were created and labeled as low risk, medium risk, and high risk. RESULTS: Of 5470 patients, 983 (18.0%) had a postdischarge-coded seizure event. The integrated binary classification approach for predicting early-onset seizures outperformed models using feature subsets (area under the curve [AUC] = 0.751, hospitalization features only AUC = 0.667, patient features only AUC = 0.603, and tumor features only AUC = 0.694). Held-out validation patient cases that were predicted by the integrated model to have elevated short-term risk more frequently developed seizures within 90 days of discharge (24.1% high risk vs 3.8% low risk, p < 0.001). Compared with those in the low-risk tertile by the long-term seizure risk model, patients in the medium-risk and high-risk tertiles had 2.13 (95% CI 1.45-3.11) and 6.24 (95% CI 4.40-8.84) times higher long-term risk for postdischarge seizures. Only patients predicted as high risk developed status epilepticus within 90 days of discharge (1.7% high risk vs 0% low risk, p = 0.003). CONCLUSIONS: The authors have presented a risk-stratified model that accurately predicted short- and long-term seizure risk in patients who underwent brain tumor resection, which may be used to stratify future study of postoperative AED prophylaxis in highest-risk patient subpopulations.

Stereotactic radiosurgery for recurrent pediatric brain tumors: clinical outcomes and toxicity.

OBJECTIVE: Recurrence of brain tumors in children after the initial course of treatment remains a problem. This study evaluated the efficacy and safety of reirradiation using stereotactic radiosurgery (SRS) in patients with recurrent pediatric primary brain tumors. METHODS: This IRB-approved retrospective review included pediatric patients with recurrent primary brain tumors treated at Stanford University from 2000 to 2019 using frameless SRS. Time to local failure (LF) and distant intracranial failure (DIF) were measured from the date of SRS and analyzed using competing risk analysis. Overall survival (OS) and progression-free survival (PFS) were analyzed with the Kaplan-Meier method. RESULTS: In total, 37 patients aged 2-24 years (median age 11 years at recurrence) were treated for 48 intracranial tumors. Ependymoma (38%) and medulloblastoma (22%) were the most common tumor types. The median (range) single fraction equivalent dose of SRS was 16.4 (12-24) Gy. The median (range) follow-up time was 22.9 (1.5-190) months. The median OS of all patients was 36.8 months. Eight of 40 (20%) lesions with follow-up imaging locally recurred. The 2-year cumulative incidence of LF after reirradiation with SRS was 12.8% (95% CI 4.6%-25.4%). The 2-year cumulative incidence of DIF was 25.3% (95% CI 12.9%-39.8%). The median PFS was 18 months (95% CI 8.9-44). Five (10.4%) patients developed toxicities potentially attributed to SRS, including cognitive effects and necrosis. CONCLUSIONS: Reirradiation using SRS for recurrent pediatric brain tumors appears safe with good local control. Innovations that improve overall disease control should continue because survival outcomes after relapse remain poor.

The effect of socioeconomic status on age at diagnosis and overall survival in patients with intracranial meningioma.

BACKGROUND: Intracranial meningiomas are the most common primary tumors of the central nervous system. How socioeconomic status (SES) impacts treatment access and outcomes for brain tumor subtypes is an emerging area of research. Few studies have examined the relationship between SES and meningioma survival and management with reference to relevant clinical factors, including age at diagnosis. We studied the independent effects of SES on receiving surgery and survival probability in patients with intracranial meningioma. METHODS: 54,282 patients diagnosed with intracranial meningioma between 2003 and 2012 from the Surveillance, Epidemiology, and End Results (SEER) Program at the National Cancer Institute database were included. Patient SES was divided into tertiles. Patient age groups included 'older' (>65, the median patient age) and 'younger'. Multivariable linear regression and Cox proportional hazards model were used with SAS v9.4. Results were adjusted for race, sex, and tumor grade. Kaplan-Meier survival curves were constructed according to SES tertiles and age groups. RESULTS: Meningioma prevalence increased with higher SES tertile. Higher SES tertile was also associated with younger age at diagnosis (OR = 0.890, p < 0.05), an increased likelihood of undergoing gross total resection (GTR) (OR = 1.112, p < 0.05), and a trend toward greater 5-year survival probability (HR = 1.773, p = 0.0531). Survival probability correlated with younger age at diagnosis (HR = 2.597, p < 0.001), but not with GTR receipt. CONCLUSION: The findings from this national longitudinal study on patients with meningioma suggest that SES affects age at diagnosis and treatment access for intracranial meningiomas patients. Further studies are required to understand and address the mechanisms underlying these disparities.

Improved survival and disease control following pembrolizumab-induced immune-related adverse events in high PD-L1 expressing non-small cell lung cancer with brain metastases.

INTRODUCTION: Immune checkpoint inhibitors have become standard of care for many patients with non-small cell lung cancer (NSCLC). These agents often cause immune-related adverse events (IRAEs), which have been associated with increased overall survival (OS). Intracranial disease control and OS for patients experiencing IRAEs with metastatic NSCLC and brain metastases have not yet been described. METHODS: We performed a single-institution, retrospective review of patients with NSCLC and existing diagnosis of brain metastasis, who underwent pembrolizumab treatment and developed any grade IRAE. The primary outcome of the study was intracranial time to treatment failure (TTF), defined from time of pembrolizumab initiation to new intracranial disease progression or death. Kaplan-Meier and Cox proportional hazard analyses were performed. RESULTS: A total of 63 patients with NSCLC brain metastasis were identified, and 24 developed IRAEs. Patients with any grade IRAEs had longer OS (21 vs. 10 months, p = 0.004), systemic TTF (15 vs. 4 months, p < 0.001) and intracranial TTF (14 vs. 5 months, p = 0.001), relative to patients without IRAEs. Presence of IRAEs and high PD-L1 (≥ 50%), but not absent/moderate PD-L1 (0-49%), had a positive association for OS, systemic TTF, and intracranial TTF. Following multivariable analysis, IRAE experienced on pembrolizumab was an independent predictor of OS, systemic TTF, and intracranial TTF. CONCLUSIONS: In our series of patients with NSCLC and brain metastases treated with pembrolizumab, IRAE presence was associated with a significant increase in OS, systemic TTF, and intracranial TTF. Future studies with increased cohorts will clarify how IRAEs should be interpreted among molecular subtypes.

From parvenu to "highbrow" tastes: The rise of cultural capital in China's intergenerational elites.

A new generation of elites distinguished by their cultural endowments has emerged in China. Unlike the older generation of elites who signaled status through the display of wealth but shared similar tastes, the new generation of cultured elites has sophisticated, often Western-oriented "highbrow" tastes in their cultural consumption. By comparing the upbringings and the tastes of interviewees from various backgrounds, this study suggests a widening taste-chasm between the elites and the underclasses in urban cities. The social process behind this is argued to be the rapid formation of cultural capital in China, in which parental privileges accumulated in the market economy converted into cultural privileges in the new generation of new elites.

Omnidirectional field enhancements drive giant nonlinearities in epsilon-near-zero waveguides.

Bulk materials with a relative electric permittivity ε close to zero exhibit giant Kerr nonlinearities. However, harnessing this response in guided-wave geometries is not straightforward, due to the extreme and counterintuitive properties of such epsilon-near-zero materials. Here we investigate, through rigorous calculations of the nonlinear coefficient, how the remarkable nonlinear properties of such materials can be exploited in several structures, including bulk films, plasmonic nanowires, and metal nanoapertures. We find the largest nonlinear response when the modal area and group velocity are simultaneously minimized, leading to omnidirectional field enhancement. This insight will be key for understanding nonlinear nanophotonic systems with extreme nonlinearities and points to new design paradigms.

Establishing the nonlinear coefficient for extremely lossy waveguides.

The nonlinear coefficient γ is central to the study of cubically nonlinear optical guided-wave structures. It is well understood for lossless waveguides, but less so for lossy systems. A number of methods for calculating γ in lossy systems have been proposed, each resulting in different expressions. Here we identify the most accurate and practical expression for γ. We do so by applying the different expressions γ to air-gold surface plasmon polariton modes in the interband region of gold and compare with a fully numerical iterative method. We thus resolve the outstanding issue of which expression for the nonlinear coefficient to use for lossy waveguides, enabling new insights into the nonlinear response of such systems.

Osimertinib for EGFR-Mutant Lung Cancer with Brain Metastases: Results from a Single-Center Retrospective Study.

INTRODUCTION: Osimertinib is a third-generation tyrosine kinase inhibitor, initially approved for epidermal growth factor receptor (EGFR) mutant non-small cell lung cancer (NSCLC) with T790M acquired resistance, and now approved in the first-line setting. However, data supporting the use of osimertinib in untreated brain metastases are limited, although it has established central nervous system (CNS) activity. Our study compares the clinical outcomes of patients experiencing progressing brain metastases treated with cranial irradiation and osimertinib with those treated with osimertinib alone. METHODS: Forty patients who were treated with osimertinib at the Stanford Cancer Center from November 2015 to December 2016 were identified by searching an electronic medical record database. Eleven patients had progressing brain metastases and did not receive radiation (group A), 9 patients had progressing brain metastases and received radiation when starting osimertinib (group B), and 20 patients had stable brain metastases at the time of initiating osimertinib (group C). Patient and disease characteristics, radiographic responses, and survival outcomes were evaluated retrospectively for the three groups. RESULTS: The CNS response rate was 32.3%. Median time to treatment failure (TTF), overall progression-free survival (PFS), and overall survival (OS) were 10.0 months (95% confidence interval [CI], 4.5-11.8), 8.8 months (95% CI, 6.2-12.1), and 16.2 months, respectively. Median TTF was 15.1 months for group A (95% CI, 1.7-28.5), 7.7 months for group B (95% CI, 0-15.5), and 10.7 months for group C (95% CI, 9.0-12.5). The median PFS was 8.8 months for group A (95% CI, 4.3-13.4), not reached for group B, and 8.4 months for group C (95% CI, 5.6-11.1). The median OS was not reached for group A and C, and was 16.2 months for group B. There was no apparent difference in TTF, PFS, or OS between the three groups. CONCLUSION: Receiving radiation prior to starting osimertinib for patients with progressing brain metastases did not prolong TTF, PFS, or OS in our series. To minimize the risks of radiation-related toxicity, delaying radiation could be considered for some patients with EGFR-mutant NSCLC with brain metastases who initially respond to osimertinib in the second-line setting. IMPLICATIONS FOR PRACTICE: Osimertinib is a third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor recently approved for the first-line treatment of EGFR-mutant non-small cell lung cancer. Although it appears to have central nervous system (CNS) activity, most clinical trials have excluded patients with untreated, progressing brain metastases. This study included patients with stable and progressing CNS metastases treated with osimertinib and found no apparent differences in median time to treatment failure, time to progression, and overall survival in patients who received osimertinib alone compared with those who received osimertinib and radiosurgery. This may support a clinician's decision to defer radiation for selected patients with untreated brain metastases who are candidates for osimertinib therapy.

Quantification of Macrophages in High-Grade Gliomas by Using Ferumoxytol-enhanced MRI: A Pilot Study.

Purpose To investigate ferumoxytol-enhanced MRI as a noninvasive imaging biomarker of macrophages in adults with high-grade gliomas. Materials and Methods In this prospective study, adults with high-grade gliomas were enrolled between July 2015 and July 2017. Each participant was administered intravenous ferumoxytol (5 mg/kg) and underwent 3.0-T MRI 24 hours later. Two sites in each tumor were selected for intraoperative sampling on the basis of the degree of ferumoxytol-induced signal change. Susceptibility and the relaxation rates R2* (1/T2*) and R2 (1/T2) were obtained by region-of-interest analysis by using the respective postprocessed maps. Each sample was stained with Prussian blue, CD68, CD163, and glial fibrillary acidic protein. Pearson correlation and linear mixed models were performed to assess the relationship between imaging measurements and number of 400× magnification high-power fields with iron-containing macrophages. Results Ten adults (four male participants [mean age, 65 years ± 9 {standard deviation}; age range, 57-74 years] and six female participants [mean age, 53 years ± 12 years; age range, 32-65 years]; mean age of all participants, 58 years ± 12 [age range, 32-74 years]) with high-grade gliomas were included. Significant positive correlations were found between susceptibility, R2*, and R2' and the number of high-power fields with CD163-positive (r range, 0.64-0.71; P < .01) and CD68-positive (r range, 0.55-0.57; P value range, .01-.02) iron-containing macrophages. No significant correlation was found between R2 and CD163-positive (r = 0.33; P = .16) and CD68-positive (r = 0.24; P = .32) iron-containing macrophages. Similar significance results were obtained with linear mixed models. At histopathologic analysis, iron particles were found only in macrophages; none was found in glial fibrillary acidic protein-positive tumor cells. Conclusion MRI measurements of susceptibility, R2*, and R2' (R2* - R2) obtained after ferumoxytol administration correlate with iron-containing macrophage concentration, and this shows their potential as quantitative imaging markers of macrophages in malignant gliomas. © RSNA, 2018 Online supplemental material is available for this article.

Stereotactic Radiosurgery for Pediatric and Adult Intracranial and Spinal Ependymomas.

OBJECTIVE/BACKGROUND: We report efficacy and toxicity outcomes with stereotactic radiosurgery (SRS) for intracranial and spinal ependymoma. METHODS: We analyzed adult and pediatric patients with newly diagnosed or recurrent intracranial or spinal ependymoma lesions treated with SRS at our institution. Following SRS, local failure (LF) was defined as failure within or adjacent to the SRS target volume, while distant failure (DF) was defined as failure outside of the SRS target volume. Time to LF and DF was analyzed using competing risk analysis with death as a competing risk.Overall survival (OS) was calculated from the date of first SRS to the date of death or censored at the date of last follow-up using the Kaplan-Meier method. RESULTS: Twenty-one patients underwent SRS to 40 intracranial (n = 30) or spinal (n = 10) ependymoma lesions between 2007 and 2018, most commonly with 18 or 20 Gy in 1 fraction. Median follow-up for all patients after first SRS treatment was 54 months (range 2-157). The 1-year, 2-year, and 5-year rates of survival among patients with initial intracranial ependymoma were 86, 74, and 52%, respectively. The 2-year cumulative incidences of LF and DF after SRS among intracranial ependymoma patients were 25% (95% CI 11-43) and 42% (95% CI 22-60), respectively. No spinal ependymoma patient experienced LF, DF, or death within 2 years of SRS. Three patients had adverse radiation effects. CONCLUSIONS: SRS is a viable treatment option for intracranial and spinal ependymoma with excellent local control and acceptable toxicity.

New tools for studying microglia in the mouse and human CNS.

The specific function of microglia, the tissue resident macrophages of the brain and spinal cord, has been difficult to ascertain because of a lack of tools to distinguish microglia from other immune cells, thereby limiting specific immunostaining, purification, and manipulation. Because of their unique developmental origins and predicted functions, the distinction of microglia from other myeloid cells is critically important for understanding brain development and disease; better tools would greatly facilitate studies of microglia function in the developing, adult, and injured CNS. Here, we identify transmembrane protein 119 (Tmem119), a cell-surface protein of unknown function, as a highly expressed microglia-specific marker in both mouse and human. We developed monoclonal antibodies to its intracellular and extracellular domains that enable the immunostaining of microglia in histological sections in healthy and diseased brains, as well as isolation of pure nonactivated microglia by FACS. Using our antibodies, we provide, to our knowledge, the first RNAseq profiles of highly pure mouse microglia during development and after an immune challenge. We used these to demonstrate that mouse microglia mature by the second postnatal week and to predict novel microglial functions. Together, we anticipate these resources will be valuable for the future study and understanding of microglia in health and disease.

Clinical factors associated with mortality within three months after radiosurgery of asymptomatic brain metastases from non-small cell lung cancer.

PURPOSE: Routine brain MRI surveillance frequently diagnoses small, asymptomatic brain metastases from non-small cell lung cancer (NSCLC) that are effectively treated with stereotactic radiosurgery (SRS). A subset of patients, however, may die prior to the onset of symptoms. This study identifies clinical features that distinguish neurologically-asymptomatic NSCLC brain metastases patients that die prior to routine 3 month follow-up after SRS. METHODS: Retrospective chart review from 2007 to 2017 identified 18 patients with neurologically-asymptomatic NSCLC brain metastases who died < 3 months after SRS. Twenty-eight additional patients meeting criteria and surviving > 6 months after SRS were identified. Clinical factors were examined to determine characteristics correlated with survival using cox proportional hazards and nominal logistic regression models. Logistic regression models using salient factors were trained with 10-fold cross-validation and compared to the graded prognostic assessment (GPA) and score index of radiosurgery (SIR) using the AUC from receiver operant characteristic curves. RESULTS: The median survival following SRS was 1.4 and 9.2 months for the < 3 months and > 6 months groups, respectively. Age, number of brain metastases, and Karnofsky performance status were associated with overall survival while gender and interval between primary cancer and first brain metastasis diagnoses were associated with < 3 months and > 6 months survival, respectively. Models using GPA and SIR performed poorly compared to preliminary metrics generated in this study for prognosis of both < 3 months and > 6 months survival. CONCLUSION: Physicians require data to provide high-value, cost-conscious health care. Clinical metrics can screen patients with asymptomatic NSCLC brain metastases likely to die prior to the standard screening interval and observation could be considered.

Imaging changes over 18 months following stereotactic radiosurgery for brain metastases: both late radiation necrosis and tumor progression can occur.

Following stereotactic radiosurgery (SRS) for brain metastases, the median time range to develop adverse radiation effect (ARE) or radiation necrosis is 7-11 months. Similarly, the risk of local tumor recurrence following SRS is < 5% after 18 months. With improvements in systemic therapy, patients are living longer and are at risk for both late (defined as > 18 months after SRS) tumor recurrence and late ARE, which have not previously been well described. An IRB-approved, retrospective review identified patients treated with SRS who developed new MRI contrast enhancement > 18 months following SRS. ARE was defined as stabilization/shrinkage of the lesion over time or pathologic confirmation of necrosis, without tumor. Local failure (LF) was defined as continued enlargement of the lesion over time or pathologic confirmation of tumor. We identified 16 patients, with a median follow-up of 48.2 months and median overall survival of 73.0 months, who had 19 metastases with late imaging changes occurring a median of 32.9 months (range 18.5-63.2 months) after SRS. Following SRS, 12 lesions had late ARE at a median of 33.2 months and 7 lesions had late LF occurring a median of 23.6 months. As patients with cancer live longer and as SRS is increasingly utilized for treatment of brain metastases, the incidence of these previously rare imaging changes is likely to increase. Clinicians should be aware of these late events, with ARE occurring up to 5.3 years and local failure up to 3.8 years following SRS in our cohort.

First-in-human intraoperative near-infrared fluorescence imaging of glioblastoma using cetuximab-IRDye800.

INTRODUCTION: Maximizing extent of surgical resection with the least morbidity remains critical for survival in glioblastoma patients, and we hypothesize that it can be improved by enhancements in intraoperative tumor detection. In a clinical study, we determined if therapeutic antibodies could be repurposed for intraoperative imaging during resection. METHODS: Fluorescently labeled cetuximab-IRDye800 was systemically administered to three patients 2 days prior to surgery. Near-infrared fluorescence imaging of tumor and histologically negative peri-tumoral tissue was performed intraoperatively and ex vivo. Fluorescence was measured as mean fluorescence intensity (MFI), and tumor-to-background ratios (TBRs) were calculated by comparing MFIs of tumor and histologically uninvolved tissue. RESULTS: The mean TBR was significantly higher in tumor tissue of contrast-enhancing (CE) tumors on preoperative imaging (4.0 ± 0.5) compared to non-CE tumors (1.2 ± 0.3; p = 0.02). The TBR was higher at a 100 mg dose than at 50 mg (4.3 vs. 3.6). The smallest detectable tumor volume in a closed-field setting was 70 mg with 50 mg of dye and 10 mg with 100 mg. On sections of paraffin embedded tissues, fluorescence positively correlated with histological evidence of tumor. Sensitivity and specificity of tumor fluorescence for viable tumor detection was calculated and fluorescence was found to be highly sensitive (73.0% for 50 mg dose, 98.2% for 100 mg dose) and specific (66.3% for 50 mg dose, 69.8% for 100 mg dose) for viable tumor tissue in CE tumors while normal peri-tumoral tissue showed minimal fluorescence. CONCLUSION: This first-in-human study demonstrates the feasibility and safety of antibody based imaging for CE glioblastomas.

How Intraoperative Tools and Techniques Have Changed the Approach to Brain Tumor Surgery.

PURPOSE OF REVIEW: Surgical treatment of brain tumors remains an integral part of a comprehensive treatment plan. Here, we review technological advances that have enhanced what surgeons are capable of doing within and outside the traditional operating room. RECENT FINDINGS: Extent of surgical resection has improved with the use of MRI and fluorescent dyes intraoperatively. Neurological injury during brain tumor surgery has decreased with appropriate use of neurophysiological monitoring. New operative scopes have enhanced ability of surgeons to visualize tissues during dissection. Laser interstitial therapy and radiation treatment have made possible the treatment of previously considered non-operable brain tumors in addition to replacing or serving as adjunct to surgical treatment of brain tumors. Surgery remains an important pillar in treatment of most brain tumors. Ongoing technological advances have augmented extent of what is possible in this realm.