Interrogation of the Microenvironmental Landscape in Brain Tumors Reveals Disease-Specific Alterations of Immune Cells.

Brain malignancies encompass a range of primary and metastatic cancers, including low-grade and high-grade gliomas and brain metastases (BrMs) originating from diverse extracranial tumors. Our understanding of the brain tumor microenvironment (TME) remains limited, and it is unknown whether it is sculpted differentially by primary versus metastatic disease. We therefore comprehensively analyzed the brain TME landscape via flow cytometry, RNA sequencing, protein arrays, culture assays, and spatial tissue characterization. This revealed disease-specific enrichment of immune cells with pronounced differences in proportional abundance of tissue-resident microglia, infiltrating monocyte-derived macrophages, neutrophils, and T cells. These integrated analyses also uncovered multifaceted immune cell activation within brain malignancies entailing converging transcriptional trajectories while maintaining disease- and cell-type-specific programs. Given the interest in developing TME-targeted therapies for brain malignancies, this comprehensive resource of the immune landscape offers insights into possible strategies to overcome tumor-supporting TME properties and instead harness the TME to fight cancer.

Gboxin is an oxidative phosphorylation inhibitor that targets glioblastoma.

Cancer-specific inhibitors that reflect the unique metabolic needs of cancer cells are rare. Here we describe Gboxin, a small molecule that specifically inhibits the growth of primary mouse and human glioblastoma cells but not that of mouse embryonic fibroblasts or neonatal astrocytes. Gboxin rapidly and irreversibly compromises oxygen consumption in glioblastoma cells. Gboxin relies on its positive charge to associate with mitochondrial oxidative phosphorylation complexes in a manner that is dependent on the proton gradient of the inner mitochondrial membrane, and it inhibits the activity of F0F1 ATP synthase. Gboxin-resistant cells require a functional mitochondrial permeability transition pore that regulates pH and thus impedes the accumulation of Gboxin in the mitochondrial matrix. Administration of a metabolically stable Gboxin analogue inhibits glioblastoma allografts and patient-derived xenografts. Gboxin toxicity extends to established human cancer cell lines of diverse organ origin, and shows that the increased proton gradient and pH in cancer cell mitochondria is a mode of action that can be targeted in the development of antitumour reagents.

18F-Fluorocholine PET uptake correlates with pathologic evidence of recurrent tumor after stereotactic radiosurgery for brain metastases.

PURPOSE: Radiographic changes of brain metastases after stereotactic radiosurgery (SRS) can signify tumor recurrence and/or radiation necrosis (RN); however, standard imaging modalities cannot easily distinguish between these two entities. We investigated whether 18F-Fluorocholine uptake in surgical samples of the resected lesions correlates with pathologic evidence of recurrent tumor and PET imaging. METHODS: About 14 patients previously treated with SRS that developed radiographic changes were included. All patients underwent a preoperative 40-min dynamic PET/CT concurrent with 392 ± 11 MBq bolus injection of 18F-Fluorocholine. 18F-Fluorocholine pharmacokinetics were evaluated by standardized uptake value (SUV), graphical analysis (Patlak plot; KiP) and an irreversible two-compartment model (K1, k2, k3, and Ki). 12 out of 14 patients were administered an additional 72 ± 14 MBq injection of 18F-Fluorocholine 95 ± 26 minutes prior to surgical resection. About 113 resected samples from 12 patients were blindly reviewed by a neuropathologist to assess the viable tumor and necrotic content, microvascular proliferation, reactive gliosis, and mono- and polymorphonuclear inflammatory infiltrates. Correlation between these metrics 18F-Fluorocholine SUV was investigated with a linear mixed model. Comparison of survival distributions of two groups of patients (population median split of PET SUVmax) was performed with the log-rank test. RESULTS: Exactly 10 out of 12 patients for which surgical samples were acquired exhibited pathologic recurrence. Strong correlation was observed between SUVmax as measured from a surgically removed sample with highest uptake and by PET (Pearson's r = 0.66). Patients with 18F-Fluorocholine PET SUVmax > 6 experienced poor survival. Surgical samples with viable tumor had higher 18F-fluorocholine uptake (SUV) than those without tumor (4.5 ± 3.7 and 2.6 ± 3.0; p = 0.01). 18F-fluorocholine count data from surgical samples is driven not only by the percentage viable tumor but also by the degree of inflammation and reactive gliosis (p ≤ 0.02; multivariate regression). CONCLUSIONS: 18F-Fluorocholine accumulation is increased in viable tumor; however, inflammation and gliosis may also lead to elevated uptake. Higher 18F-Fluorocholine PET uptake portends worse prognosis. Kinetic analysis of dynamic 18F-Fluorocholine PET imaging supports the adequacy of the simpler static SUV metric.

Prior malignancies in patients harboring glioblastoma: an institutional case-study of 2164 patients.

More patients are surviving long-term following a cancer diagnosis and as such are at risk for second malignancies. As the most common primary brain tumor, glioblastoma (GBM) will not infrequently occur in this population. No study has examined the incidence of prior cancer (PC) in patients harboring GBM. Here we evaluate the epidemiological features, as well as the molecular and clinical characteristics of GBM as a second cancer. Utilizing a web-based cancer data management system at our institution, we identified 2164 patients harboring GBM from 2007 to 2014. We collected baseline demographic, molecular, and clinical data. Univariate analysis was performed to compare the cohort of GBM patients with and without PC diagnosis. Survival differences were analyzed with Kaplan-Meier and log-rank testing. A Cox-proportional hazards model was fit for multivariable analysis. 170 patients (7.9%) harboring GBM had a PC diagnosis. The median interval between diagnoses was 79 months. The most common pathologies were breast (18.8%) and prostate (18.8%) cancer. Patients with a PC were older at the time of GBM diagnosis than those without PC (66 vs. 59 years, p < 0.001) and were more likely to be white (88.2 vs. 72.8%, p < 0.001). Patients with PC were more likely to harbor an EGFR (20 vs. 12.3%, p < 0.001) or MGMT mutation (17.6 vs. 11.6%, p < 0.001). Median survival was 13 months in the PC cohort and 15 months in the cohort without PC (p = NS). Age, KPS, and diagnosis year were the only factors which influenced outcome in multivariable analysis. Patients who develop GBM following a prior malignancy constitute ~8% of patients with GBM. Despite significant molecular differences these two cohorts appear to have a similar overall prognosis and clinical course. Thus, whether or not a patient harbors a malignancy prior to diagnosis of GBM should not exclude him or her from aggressive treatment or for consideration of novel investigational therapies.

Long-term risk of radionecrosis and imaging changes after stereotactic radiosurgery for brain metastases.

Radionecrosis is a well-characterized effect of stereotactic radiosurgery (SRS) and is occasionally associated with serious neurologic sequelae. Here, we investigated the incidence of and clinical variables associated with the development of radionecrosis and related radiographic changes after SRS for brain metastases in a cohort of patients with long-term follow up. 271 brain metastases treated with single-fraction linear accelerator-based SRS were analyzed. Radionecrosis was diagnosed either pathologically or radiographically. Univariate and multivariate Cox regression was performed to determine the association between radionecrosis and clinical factors available prior to treatment planning. After median follow up of 17.2 months, radionecrosis was observed in 70 (25.8%) lesions, including 47 (17.3%) symptomatic cases. 22 of 70 cases (31.4%) were diagnosed pathologically and 48 (68.6%) were diagnosed radiographically. The actuarial incidence of radionecrosis was 5.2% at 6 months, 17.2% at 12 months and 34.0% at 24 months. On univariate analysis, radionecrosis was associated with maximum tumor diameter (HR 3.55, p < 0.001), prior whole brain radiotherapy (HR 2.21, p = 0.004), prescription dose (HR 0.56, p = 0.02) and histology other than non-small cell lung, breast or melanoma (HR 1.85, p = 0.04). On multivariate analysis, only maximum tumor diameter (HR 3.10, p < 0.001) was associated with radionecrosis risk. This data demonstrates that with close imaging follow-up, radionecrosis after single-fraction SRS for brain metastases is not uncommon. Maximum tumor diameter on pre-treatment MR imaging can provide a reliable estimate of radionecrosis risk prior to treatment planning, with the greatest risk among tumors measuring >1 cm.

Tracking normalization of brain tumor vasculature by magnetic imaging and proangiogenic biomarkers.

Clinical assessment of the response to antiangiogenic therapy has been cumbersome. A study in this issue of Cancer Cell demonstrates that a combination of magnetic resonance imaging (MRI) for quantification of normalized vessels with measurements of circulating levels of proangiogenic factors, including FGF2, SDF1, and viable circulating endothelial cells, provides an effective means to evaluate the response of recurrent glioblastoma to a prototypical pan-VEGF receptor tyrosine kinase inhibitor, AZD2171.

Temporal relationship of post-operative radiotherapy with temozolomide and oncologic outcome for glioblastoma.

To determine the impact of delay between surgery and radiotherapy on overall survival (OS) in temozolomide treatmented patients with the incorporation of O6-methylguanine-DNA methyltransferase (MGMT). From 2000 to 2012, 345 consecutive glioblastoma patients were treated with surgery, radiotherapy, and temozolomide at our institution. A Cox-regression model was constructed using significant univariate parameters, known prognostic factors including MGMT, and the interval from surgery to radiotherapy (≤ 2, 2-5, and ≥ 6 weeks). Survival rates were calculated by Kaplan-Meier methods. Cox-regression was utilized to calculate adjusted hazard ratios (HR). The median survival for the entire cohort was 12.2 months. The 1 year actuarial OS was 43.1 %, 53.3 %, and 64.3 % (p = 0.11), for intervals from surgery to radiotherapy of ≤ 2, 2-5, and ≥ 6 weeks, respectively. Patients radiated within 2 weeks post-surgery were more likely to have older age (p = 0.03), treated with 2D techniques (p < 0.001) and dose <36 Gy (p < 0.001), undergo a biopsy only (p < 0.001), KPS of <70 (p < 0.001), severe pre-radiotherapy neurologic symptoms (p = 0.04), and bilateral disease (p = 0.02). Multivariate analysis including MGMT status demonstrated a significant detriment in delaying radiotherapy (≤ 2 weeks as reference); 3-5 weeks (HR 2.80 [0.72-10.89], p = 0.14), and >6 weeks (HR 3.76 [1.01-14.57], p = 0.05). We report the first analysis on the survival impact of delaying post-operative radiotherapy for temozolomide treated glioblastoma patients with MGMT information. Our data does not support the OS benefit previously seen in delayed RT when correcting for important covariates. We demonstrate a survival detriment with delaying RT post-surgery greater than 6 weeks on multivariate analysis.

Resection of glioma in an fMRI-defined "split" Broca's area.

Gross total resection of gliomas can be limited by the involvement of tumor in eloquent areas. Moreover, lesions can impart cortical reorganization and make the precise determination of hemispheric dominance and localization of language function even more difficult. Preoperative mapping with functional magnetic resonance imaging (fMRI), intraoperative imaging modalities, and intraoperative direct cortical stimulation enable surgeons to map the functional topography of the brain in relation to the tumor and perform a safe maximal resection. In this report, we present a patient with left frontal glioma of complex morphology, wherein the tumor was enveloped by Broca's area on fMRI. Intraoperative mapping and intraoperative magnetic resonance imaging (iMRI) allowed gross total resection of the tumor with preservation of language function and illustrate the utility of multiple contemporary modalities in the surgical management of low-grade gliomas located in eloquent cortices.

Abbreviated course of radiation therapy with concurrent temozolomide for high-grade glioma in patients of advanced age or poor functional status.

Elderly or frail patients with high-grade gliomas (HGG) can be effectively treated with an abbreviated course of radiation therapy (RT) consisting of 40 Gy in 15 fractions. Concurrent temozolomide (TMZ) improves survival in non-elderly patients with glioblastoma treated with standard schedule of 60 Gy in 30 fractions. We describe our institutional experience of combining abbreviated RT with concurrent TMZ for treatment of HGG. Between 1/1/2004 and 2/5/2010 31 patients were treated. Survival was estimated with the Kaplan-Meier method. Toxicity was scored according to CTCAE 3.0. Median age was 66 years (range 32-90), and 17 patients had Karnofsky performance score <70. At the time of analysis, 30 patients (98 %) had died, with a followup of 14 months in the surviving patient. Median survival was 11 months (range 1-20), and 41 % of patients were alive at 12 months. Thirty patients (97 %) had a decreased corticosteroid requirement after completion of therapy. Only one new hospitalization for worsening neurologic status was required during therapy. Grade 3-4 hematologic toxicity occurred in 11 patients. Abbreviated RT with concurrent TMZ provides a clinical benefit, is safe and tolerable in patients of advanced age or poor functional status.

Radiotherapy and concomitant temozolomide may improve survival of elderly patients with glioblastoma.

Survival of elderly patients with glioblastoma (GBM) is poor, but improves with tumor resection and radiotherapy (RT). Concurrent temozolomide (TMZ) chemotherapy during RT improves the survival of younger patients with GBM, but the benefit in elderly patients is unclear. Medical records of patients ≥65 years old with primary GBM, histologically confirmed at Memorial Sloan-Kettering Cancer Center and treated with RT, were reviewed. Survival was associated with patient (age, performance status), tumor (single or multiple), and treatment (extent of surgery, RT field, technique, fractionation and use of concurrent TMZ) characteristics in a multivariable Cox regression model. Grade ≥3 hematologic toxicity rates were compared to reported rates in younger patients. Median age of the 291 patients studied was 71 years. Longer survival was associated with younger age, tumor resection, and concomitant TMZ and RT (p < 0.01). Concurrent TMZ and RT improved median survival of patients with favorable prognostic factors from 12 to 21 months and from 10 to 13 months in patients 65-70 and ≥71 years old, respectively. Concomitant TMZ and RT increased the 2 year OS rate from 14 to 41 % and from 5 to 24 % in patients 65-70 and ≥71 years old, respectively. Grade 3-4 thrombocytopenia was significantly more frequent in the present cohort. Survival of elderly patients with GBM may be prolonged with the use of concomitant TMZ during RT. An ongoing randomized study will determine the benefit of this approach in a prospective fashion.

Magnetic resonance spectroscopy imaging in radiotherapy planning for recurrent glioma.

PURPOSE: The purpose of this study was to investigate how incorporation of magnetic resonance spectroscopy imaging (MRSI) into radiotherapy planning would increase the target volume for patients with recurrent glioma. METHODS: After prior standard radiotherapy, 25 patients with recurrent glioma were treated with bevacizumab and concurrent hypofractionated stereotactic radiotherapy (HFSRT), delivering 30 Gy in five fractions. MRSI were acquired for 12 patients. Areas with markedly higher choline levels relative to the levels of total creatine and N-acetylaspartate were identified and referred to as MRSI voxels with elevated metabolite ratios (EMR). Gross tumor volume (GTV) consisted of contrast-enhancing tumor on T1-weighted magnetic resonance images (MRI) and computed tomography. Clinical target volume (CTV) was GTV + 5 mm margin and MRSI voxels with EMR. Overall survival (OS) and 6-month progression free survival (PFS) for these patients were reported in a prior publication [Gutin et al., Int. J. Radiat. Oncol., Biol., Phys. 75(1), 156-163 (2009)], and the outcome was correlated with the GTV and the volume of MRSI voxels with EMR in this study. RESULTS: Seven of the 12 patients had MRSI voxels with EMR. If none of the MRSI voxels with EMR were included, the CTV would range from 9.2 to 73.0 cm3 with a median of 31.0 cm3, whereas if all voxels were included, the CTV would range from 27.4 to 74.4 cm3 with a median of 35.0 cm3. For three of the seven patients, including the voxels with EMR, would have increased the CTV by 14%-23%. For one patient, where the MRSI voxels with EMR did not overlap the GTV, including these voxels would increase the CTV by 198%. No correlation could be found between the OS and PFS and the GTV or the volume of MRSI voxels with EMR. CONCLUSIONS: Seven of 12 patients with recurrent glioma had MRSI voxels with EMR. For four of these seven patients, including the MRSI voxels with EMR, significantly increased the CTV. This study does not have statistical power to conclude on the importance of including areas with MRSI-suspect disease into the radiation target volume.

Neurosurgery for brain tumors: update on recent technical advances.

Advances in diagnostic imaging modalities and improved access to specialty care have led directly to an increased diagnosis of both metastatic and primary brain tumors. As technology has improved, so has the ability to treat this larger patient population. Diffusion tensor imaging (DTI) has recently shown the potential to aid in histologic diagnosis as well as to identify local brain invasion outside of that readily identifiable by conventional MRI. Similar to DTI, functional MRI provides a noninvasive means of delineating tumor margin from eloquent cortex and aids in preoperative surgical planning. As the literature shows increasing support for the advantages of extensive resection in glioma patients, modalities that aid in this regard are displaying increased importance. Surgeons have recently demonstrated the utility of intraoperative MRI in increasing extent of resection in both low- and high-grade glioma patients. Intraoperative tumor fluorescence provided by the chemical compound 5-aminolevulinic acid assists surgeons in identifying the true tumor margin during resection of glial neoplasms consequently increasing extent of resection. Finally, laser interstitial thermal therapy is an emerging treatment modality allowing surgeons to treat small intracranial lesions with potentially decreased morbidity via this minimally invasive approach. The following review analyzes the recent literature in an effort to describe how these modalities can and should be used in the treatment of patients with intracranial pathology.

Functional MRI in the presurgical evaluation of patients with brain tumors: characterization of the statistical threshold.

We investigated whether an optimal statistical threshold could be obtained in healthy controls and patients with brain tumors undergoing presurgical functional MRI assessment. The volumes of activation of the primary motor cortex (PMC) and the lateral prefrontal cortex (PFC) were measured for the tumor and nontumor sides in 24 patients and 8 controls using four parameters; p values ranged between 10(-2) and 10(-31). The mean r value for first activation in the PMC was higher in controls than for both the tumor and nontumor sides in patients. The mean r value for 'first activation in the noise area' and 'PMC and PFC ratio' in controls was significantly different from the mean r value for the tumor and nontumor sides in patients (p < 0.05). The magnitude of the range of r values for the nontumor side was closer to the tumor side data than to the control data. It is imperative to evaluate functional MRI data with a wide range of statistical parameters, especially in the assessment of tumor patients.

Adenovirus-mediated expression of a dominant negative Ku70 fragment radiosensitizes human tumor cells under aerobic and hypoxic conditions.

Ku70 is one component of a protein complex, the Ku70/Ku80 heterodimer, which binds to DNA double-strand breaks and activates DNA-dependent protein kinase (DNA-PK), leading to DNA damage repair. Our previous work has confirmed that Ku70 is important for DNA damage repair in that Ku70 deficiency compromises the ability of cells to repair DNA double-strand breaks, increases the radiosensitivity of cells, and enhances radiation-induced apoptosis. Because of the radioresistance of some human cancers, particularly glioblastoma, we examined the use of a radio-gene therapy paradigm to sensitize cells to ionizing radiation. Based on the analysis of the structure-function of Ku70 and the crystal structure of Ku70/Ku80 heterodimer, we designed and identified a candidate dominant negative fragment involving an NH(2)-terminal deletion, and designated it as DNKu70. We generated this mutant construct, stably overexpressed it in Rat-1 cells, and showed that it has a dominant negative effect (i.e., DNKu70 overexpression results in decreased Ku-DNA end-binding activity, and increases radiosensitivity). We then constructed and generated recombinant replication-defective adenovirus, with DNKu70 controlled by the cytomegalovirus promoter, and infected human glioma U-87 MG cells and human colorectal tumor HCT-8 cells. We show that the infected cells significantly express DNKu70 and are greatly radiosensitized under both aerobic and hypoxic conditions. The functional ramification of DNKu70 was further shown in vivo: expression of DNKu70 inhibits radiation-induced DNA-PK catalytic subunit autophosphorylation and prolongs the persistence of gamma-H2AX foci. If radiation-resistant tumor cells could be sensitized by down-regulating the cellular level/activity of Ku/DNA-PK, this approach could be evaluated as an adjuvant to radiation therapy.

Genomic Correlates of Disease Progression and Treatment Response in Prospectively Characterized Gliomas.

PURPOSE: The genomic landscape of gliomas has been characterized and now contributes to disease classification, yet the relationship between molecular profile and disease progression and treatment response remain poorly understood.Experimental Design: We integrated prospective clinical sequencing of 1,004 primary and recurrent tumors from 923 glioma patients with clinical and treatment phenotypes. RESULTS: Thirteen percent of glioma patients harbored a pathogenic germline variant, including a subset associated with heritable genetic syndromes and variants mediating DNA repair dysfunctions (29% of the total) that were associated with somatic biallelic inactivation and mechanism-specific somatic phenotypes. In astrocytomas, genomic alterations in effectors of cell-cycle progression correlated with aggressive disease independent of IDH mutation status, arose preferentially in enhancing tumors (44% vs. 8%, P < 0.001), were associated with rapid disease progression following tumor recurrence (HR = 2.6, P = 0.02), and likely preceded the acquisition of alkylating therapy-associated somatic hypermutation. Thirty-two percent of patients harbored a potentially therapeutically actionable lesion, of whom 11% received targeted therapies. In BRAF-mutant gliomas, response to agents targeting the RAF/MEK/ERK signaling axis was influenced by the type of mutation, its clonality, and its cellular and genomic context. CONCLUSIONS: These data reveal genomic correlates of disease progression and treatment response in diverse types of glioma and highlight the potential utility of incorporating genomic information into the clinical decision-making for patients with glioma.

Tumor mutational load predicts survival after immunotherapy across multiple cancer types.

Immune checkpoint inhibitor (ICI) treatments benefit some patients with metastatic cancers, but predictive biomarkers are needed. Findings in selected cancer types suggest that tumor mutational burden (TMB) may predict clinical response to ICI. To examine this association more broadly, we analyzed the clinical and genomic data of 1,662 advanced cancer patients treated with ICI, and 5,371 non-ICI-treated patients, whose tumors underwent targeted next-generation sequencing (MSK-IMPACT). Among all patients, higher somatic TMB (highest 20% in each histology) was associated with better overall survival. For most cancer histologies, an association between higher TMB and improved survival was observed. The TMB cutpoints associated with improved survival varied markedly between cancer types. These data indicate that TMB is associated with improved survival in patients receiving ICI across a wide variety of cancer types, but that there may not be one universal definition of high TMB.

Brain and leptomeningeal metastases from cutaneous melanoma: survival outcomes based on clinical features.

Brain metastases (BM) are among the most devastating and debilitating complications of melanoma. This retrospective study was conducted to gain a better understanding of patient and disease characteristics that have the greatest impact on overall survival in melanoma patients with BM; therapeutic interventions were also assessed. The records of all patients diagnosed with cutaneous melanoma and BM who were seen at Memorial Sloan-Kettering Cancer Center between 1991 and 2001 were retrospectively reviewed. A variety of factors, including age at diagnosis of stage IV disease, gender, race, disease stage at diagnosis, presence of BM at diagnosis of stage IV disease, neurologic symptoms, radiographic findings, number of BM, status and site(s) of extracranial metastasis, and treatment modalities, were analyzed for correlation with overall survival using univariate and multivariate Cox regression models. The records of 355 patients with BM were included in the analysis. On univariate analysis, seven patient and disease characteristics were significantly associated with poorer survival: age > 65 years, extracranial metastases, BM at stage IV diagnosis, neurologic symptoms, four or more BM, hydrocephalus, and leptomeningeal metastases. Of these, age, extracranial metastasis, neurologic symptoms, and number of BM were significantly associated with poorer survival in a multivariate analysis. Multivariate analysis of treatment modalities suggested that patients who had surgery, radiosurgery, or chemotherapy with temozolomide had improved survival outcomes, although this analysis has limitations. The prognostic factors identified in this retrospective study should be considered when making treatment decisions for patients with BM and used as stratification factors in future clinical trials.

Migration and differentiation of neural precursors derived from human embryonic stem cells in the rat brain.

Human embryonic stem (hES) cells provide a potentially unlimited cell source for regenerative medicine. Recently, differentiation strategies were developed to direct hES cells towards neural fates in vitro. However, the interaction of hES cell progeny with the adult brain environment remains unexplored. Here we report that hES cell-derived neural precursors differentiate into neurons, astrocytes and oligodendrocytes in the normal and lesioned brain of young adult rats and migrate extensively along white matter tracts. The differentiation and migration behavior of hES cell progeny was region specific. The hES cell-derived neural precursors integrated into the endogenous precursor pool in the subventricular zone, a site of persistent neurogenesis. Like adult neural stem cells, hES cell-derived precursors traveled along the rostral migratory stream to the olfactory bulb, where they contributed to neurogenesis. We found no evidence of cell fusion, suggesting that hES cell progeny are capable of responding appropriately to host cues in the subventricular zone.