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Immunotherapy has revolutionized cancer treatment in the past decade, but significant hurdles remain. Human studies with immune checkpoint inhibitors targeting programmed cell death protein have demonstrated suboptimal efficacy in the setting of low-grade gliomas (LGGs). Identification of mechanisms leading to inadequate anti-tumor immunity is paramount. The current study evaluates and validates barriers to immunotherapy using a novel machine learning algorithm.We utilized The Cancer Genome Atlas (TCGA) to generate expression levels of 28 immune genes related to known immunotherapeutic targets or lymphocyte cytolytic activity. We created training and testing groups and 3 machine learning models to determine the genes most highly correlated to cytolytic activity (CYT). The 3 models were run through multiple regression by exhaustive selection, LASSO, and random forest. We validated computational results by comparing expression of pertinent genes in patient-derived glioma samples.Our models demonstrated linearity, a low mean-squared error, and consistent results with respect to the most important variables. Expression of ICOS, IDO1, and CD40 were the most important variables in all models and demonstrated positive correlation with CYT. Other variables included TIGIT and CD137. Genetic analysis from 3 IDH-mutants (IDHm) and 3 IDH-wild type (IDHwt) patient-derived glioma samples validated TCGA data and demonstrated lower levels of CYT in IDHm gliomas compared with IDHwt.This novel methodology has elucidated 3 potential targets for immunotherapy development in LGGs. We also demonstrated a novel method of analyzing data using advanced statistical techniques that can be further used in developing treatments for other diseases as well.

Supplementary Table 2. Comparison of ELISPOT responses between the current study and our recent study in pediatric glioma patients

Supplementary Table 1. Associations between baseline IFN-γ ELISPOT values vs. PFS or subsequent IFN-γ ESLIPOT responses

Purpose: WHO grade 2 low-grade gliomas (LGG) with high risk factors for recurrence are mostly lethal despite current treatments. We conducted a phase I study to evaluate the safety and immunogenicity of subcutaneous vaccinations with synthetic peptides for glioma-associated antigen (GAA) epitopes in HLA-A2+ adults with high-risk LGGs in the following three cohorts: (i) patients without prior progression, chemotherapy, or radiotherapy (RT); (ii) patients without prior progression or chemotherapy but with prior RT; and (iii) recurrent patients.Experimental Design: GAAs were IL13Rα2, EphA2, WT1, and Survivin. Synthetic peptides were emulsified in Montanide-ISA-51 and given every 3 weeks for eight courses with intramuscular injections of poly-ICLC, followed by q12 week booster vaccines.Results: Cohorts 1, 2, and 3 enrolled 12, 1, and 10 patients, respectively. No regimen-limiting toxicity was encountered except for one case with grade 3 fever, fatigue, and mood disturbance (cohort 1). ELISPOT assays demonstrated robust IFNγ responses against at least three of the four GAA epitopes in 10 and 4 cases of cohorts 1 and 3, respectively. Cohort 1 patients demonstrated significantly higher IFNγ responses than cohort 3 patients. Median progression-free survival (PFS) periods since the first vaccine are 17 months in cohort 1 (range, 10–47+) and 12 months in cohort 3 (range, 3–41+). The only patient with large astrocytoma in cohort 2 has been progression-free for more than 67 months since diagnosis.Conclusion: The current regimen is well tolerated and induces robust GAA-specific responses in WHO grade 2 glioma patients. These results warrant further evaluations of this approach. Clin Cancer Res; 21(2); 286–94. ©2014 AACR.

Supplementary Figure 1. T2-Flair MRI images of 2 cases (Patient 9 in Cohort 1 and Patient 1 in Cohort 2)

Supplementary Figure 2. Immunohistochemistry evaluating expression of vaccine-targeted antigens in resected tumor tissues.

PDF file, 65K, mAb-mediated depletion of T-cells.

PDF file, 66K, Murine glioma-derived CD11b+ cells inhibit CD8+ T-cells in vitro.

PDF file, 129K, Critical role of IL-4Ralpha in T-cell-suppressing function of BM-derived myeloid cells.

PDF file, 65K, Confirmation of chimerism using enhanced green fluorescence protein (EGFP+) donor BM cells.

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Malignant gliomas are lethal cancers in the brain and heavily infiltrated by myeloid cells. Interleukin-4 receptor-α (IL-4Rα) mediates the immunosuppressive functions of myeloid cells, and polymorphisms in the IL-4Rα gene are associated with altered glioma risk and prognosis. In this study, we sought to evaluate a hypothesized causal role for IL-4Rα and myeloid suppressor cells in glioma development. In both mouse de novo gliomas and human glioblastoma cases, IL-4Rα was upregulated on glioma-infiltrating myeloid cells but not in the periphery or in normal brain. Mice genetically deficient for IL-4Rα exhibited a slower growth of glioma associated with reduced production in the glioma microenvironment of arginase, a marker of myeloid suppressor cells, which is critical for their T-cell inhibitory function. Supporting this result, investigations using bone marrow-derived myeloid cells showed that IL-4Rα mediates IL-13–induced production of arginase. Furthermore, glioma-derived myeloid cells suppressed T-cell proliferation in an IL-4Rα–dependent manner, consistent with their identification as myeloid-derived suppressor cells (MDSC). Granulocyte macrophage colony-stimulating factor (GM-CSF) plays a central role for the induction of IL-4Rα expression on myeloid cells, and we found that GM-CSF is upregulated in both human and mouse glioma microenvironments compared with normal brain or peripheral blood samples. Together, our findings establish a GM-CSF–induced mechanism of immunosuppression in the glioma microenvironment via upregulation of IL-4Rα on MDSCs. Cancer Res; 73(21); 6413–23. ©2013 AACR.

PDF file, 129K, IL-4Ralpha on CD11b+Gr1+ BILs and SPCs.

Patients with glioblastoma (GBM) need bold new approaches to their treatment, yet progress has been hindered by a relative inability to dynamically track treatment response, mechanisms of resistance, evolution of targetable mutations, and changes in mutational burden. We are writing on behalf of a multidisciplinary group of academic neuro-oncology professionals who met at the collaborative Christopher Davidson Forum at Washington University in St Louis in the fall of 2019. We propose a dramatic but necessary change to the routine management of patients with GBM to advance the field: to routinely biopsy recurrent GBM at the time of presumed recurrence. Data derived from these samples will identify true recurrence vs treatment effect, avoid treatments with little chance of success, enable clinical trial access, and aid in the scientific advancement of our understanding of GBM.

OBJECTIVES Although the impact of surgery in glioblastoma (GBM) is well-established, there is insufficient data to determine how surgical resection affects overall survival (OS). The impact of other GBM genomic alterations on EOR-induced survival remains poorly understood. Here, we leverage a large cohort of GBM patients with genomic data to establish the impact of genomic alterations on resection-dependent overall survival in GBM. METHODS 537 IDH WT GBMs from UPMC were analyzed using Glioseq next generation sequencing panel. Using molecular profiles derived from Glioseq data, semi-supervised Monte Carlo reference-based consensus clustering was used to define 5 distinct groups. Cox Proportional Hazards models were used to identify predictors of OS within molecular groups. RESULTS Clustering of 537 IDH wild-type GBM identified 5 distinct groups: 1: TERT mutated/MGMT methylated/EGFR mutated or gain; 2: TERT mutated /MGMT methylated/p53 mutated; 3: TERT WT; 4: TERT mutated/MGMT methylated/CDKN2A loss; 5: TERT mutated/MGMT unmethylated. Thresholds in postoperative residual contrast enhancing volume (rCEV) and residual non-contrast enhancing volume (rNCEV) were identified which marked significant differences in median overall survival (MOS) between molecular groups in rCEV -Group 1: 11.7cc, Group 2: 14.4cc, Group 3: 1.1cc, Group 4: 0.1cc, and Group 5 1.1cc. Sex, age, KPS >70, temozolomide, and radiation along with thresholded rCEV and rNCEV were used in multivariate Cox analyses. Groups demonstrated distinct predictors of OS: radiation only in Group 1 tumors, low rCEV in Group 2 tumors, younger age, temodar, low CEV, and KPS >70 in Group 3 tumors, female sex, younger age, radiation, KPS >70 low rCEV in Group 4 tumors, and KPS >70, temodar, and low rCEV in Group 5 tumors. CONCLUSIONS Clustering results suggest that there are clinically distinct molecular groups of IDH wild-type glioblastomas. Age, sex, KPS >70, temozolomide treatment, radiation therapy, and EOR have varying affects on these molecular groups.

The therapeutic promise of oncolytic viruses (OVs) rests on their ability to both selectively kill tumor cells and induce anti-tumor immunity. The potential of tumors to be recognized and eliminated by an effective anti-tumor immune response has been spurred on by the discovery that immune checkpoint inhibition can overcome tumor-specific cytotoxic T cell (CTL) exhaustion and provide durable responses in multiple tumor indications. OV-mediated tumor destruction is now recognized as a powerful means to assist in the development of anti-tumor immunity for two important reasons: (i) OVs, through the elicitation of an anti-viral response and the production of type I interferon, are potent stimulators of inflammation and can be armed with transgenes to further enhance anti-tumor immune responses, and (ii) lytic activity can promote the release of tumor-associated antigens (TAAs) and tumor neoantigens that function as in situ tumor-specific vaccines to elicit adaptive immunity. Oncolytic herpes simplex viruses (oHSVs) are among the most widely studied OVs for the treatment of solid malignancies, and Amgen's oHSV Imlygic® for the treatment of melanoma is the only OV approved in major markets. Here we describe important biological features of HSV that make it an attractive OV, clinical experience with HSV-based vectors, and strategies to increase applicability to cancer treatment.

It has now been nearly 15 years since the last major advance in the treatment of patients with glioma. "The addition of temozolomide to radiotherapy for newly diagnosed glioblastoma resulted in a clinically meaningful and statistically significant survival benefit with minimal additional toxicity". Autophagy is primarily a survival pathway, literally self-eating, that is utilized in response to stress (such as radiation and chemotherapy), enabling clearance of effete protein aggregates and multimolecular assemblies. Promising results have been observed in patients with glioma for over a decade now when autophagy inhibition with chloroquine derivatives coupled with conventional therapy. The application of autophagy inhibitors, the role of immune cell-induced autophagy, and the potential role of novel cellular and gene therapies, should now be considered for development as part of this well-established regimen.

Glioma is one of the most common primary malignant tumors of the central nervous system accounting for approximately 40% of all intracranial tumors. Temozolomide is a conventional chemotherapy drug for adjuvant treatment of patients with high-risk gliomas, including grade II to grade IV. Our bioinformatic analysis of The Cancer Genome Atlas and Chinese Glioma Genome Atlas datasets and immunoblotting assay show that SLC12A2 gene and its encoded Na+-K+-2Cl− cotransporter isoform 1 (NKCC1) protein are abundantly expressed in grade II–IV gliomas. NKCC1 regulates cell volume and intracellular Cl− concentration, which promotes glioma cell migration, resistance to temozolomide, and tumor-related epilepsy in experimental glioma models. Using mouse syngeneic glioma models with intracranial transplantation of two different glioma cell lines (GL26 and SB28), we show that NKCC1 protein in glioma tumor cells as well as in tumor-associated reactive astrocytes was significantly upregulated in response to temozolomide monotherapy. Combination therapy of temozolomide with the potent NKCC1 inhibitor bumetanide reduced tumor proliferation, potentiated the cytotoxic effects of temozolomide, decreased tumor-associated reactive astrogliosis, and restored astrocytic GLT-1 and GLAST glutamate transporter expression. The combinatorial therapy also led to suppressed tumor growth and prolonged survival of mice bearing GL26 glioma cells. Taken together, these results demonstrate that NKCC1 protein plays multifaceted roles in the pathogenesis of glioma tumors and presents as a therapeutic target for reducing temozolomide-mediated resistance and tumor-associated astrogliosis.

The use of mutant strains of oncolytic herpes simplex virus (oHSV) in early-phase human clinical trials for the treatment of glioblastoma multiforme (GBM) has proven safe, but limited efficacy suggests that more potent vector designs are required for effective GBM therapy. Inadequate vector performance may derive from poor intratumoral vector replication and limited spread to uninfected cells. Vector replication may be impaired by mutagenesis strategies to achieve vector safety, and intratumoral virus spread may be hampered by vector entrapment in the tumor-specific extracellular matrix (ECM) that in GBM is composed primarily of type IV collagen. In this report, we armed our previously described epidermal growth factor receptor (EGFR)vIII-targeted, neuronal microRNA-sensitive oHSV with a matrix metalloproteinase (MMP9) to improve intratumoral vector distribution. We show that vector-expressed MMP9 enhanced therapeutic efficacy and long-term animal survival in a GBM xenograft model. Keywords: matrix metalloproteinase 9 = MMP9, extracellular matrix = ECM, Oncolytic vectors = OVs, Glioblastoma multiforme = GBM, OVs derived from herpes simplex virus = oHSV

Background Fluorescein is an agent that accumulates in areas of blood-brain barrier breakdown and is commonly used in neurosurgical oncology to assist with lesion localization and visualizing the extent of resection. It is considered to be cost-effective and has a favorable safety profile. Studies on the utilization of fluorescein demonstrate an improved extent of tumor resection and increased overall survival. Currently, fluorescein detection systems are all microscope based, leading to limitations such as decreased maneuverability, limited visualization of the entire operative field, and significant cost associated with obtaining and maintaining a neurosurgical operating microscope. Methods Three consecutive craniotomy patients for tumor resection were included, and surgery was carried out under loupe fluorescence guidance using the ReVeal 450 System, and also a surgical microscope for comparison. Results Loupe-mounted fluorescence system enabled excellent visualization of fluorescence in all three cases. Conclusions In this manuscript, we describe our experience with a loupe-mounted fluorescein detection system in 3 patients with malignant gliomas. We found that the loupe-mounted system offered excellent ability to visualize fluorescein fluorescence. Although loupe-mounted systems are not an alternative to surgical microscopes, they could be a useful surgical adjunct for superficial lesions and in low-middle income counties.

Glioblastoma (GBM) is a malignant tumor with a median survival rate of 15-16 months with standard care; however, cases of successful treatment offer hope that an enhanced understanding of the pathology will improve the prognosis. The cell of origin in GBM remains controversial. Recent evidence has implicated stem cells as cells of origin in many cancers. Neural stem/precursor cells (NSCs) are being evaluated as potential initiators of GBM tumorigenesis. The NSCs in the subventricular zone (SVZ) have demonstrated similar molecular profiles and share several distinctive characteristics to proliferative glioblastoma stem cells (GSCs) in GBM. Genomic and proteomic studies comparing the SVZ and GBM support the hypothesis that the tumor cells and SVZ cells are related. Animal models corroborate this connection, demonstrating migratory patterns from the SVZ to the tumor. Along with laboratory and animal research, clinical studies have demonstrated improved progression-free survival in patients with GBM after radiation to the ipsilateral SVZ. Additionally, key genetic mutations in GBM for the most part carry regulatory roles in the SVZ as well. An exciting avenue towards SVZ modeling and determining its role in gliomagenesis in the human context is human brain organoids. Here we comprehensively discuss and review the role of the SVZ in GBM genesis, maintenance, and modeling.

BACKGROUND GBM genomic profiling relies on sequencing a limited tumor tissue sample, which is invasive and may underrepresent molecular heterogeneity. CSF, which can be obtained less invasively, is in intimate contact with tumor lesions and may better capture the full genomic profile of the tumor. However, datasets with contemporaneously collected CSF and tissue to support this claim have been lacking. To evaluate the performance of CSF NGS, we conducted a pilot study in patients with GBM undergoing a resection for suspected recurrence following first-line chemoradiotherapy. METHODS Paired CSF and tissue samples were sequenced using a hybrid capture-based NGS assay. Clinically meaningful variants were defined as those that are potentially targetable using off-label or clinical trial options, exhibit prognostic value, or may predict response or resistance to specific treatments. RESULTS Eighteen patients were enrolled, and 13 of 18 CSF samples (72.2%) were sequenced successfully. At least one variant was detected in all CSF samples analyzed. A median of 7 variants (range 1—67) was detected per sample across 54 genes. The median variant allele fraction was 0.6% (range 0.2—72.4%). Among 38 clinically meaningful genes, 102 variants were detected; 25 (24.5%) were detected in both tissue and CSF, while 60 (58.8%) were detectable solely in CSF. Hypermutation was detected by CSF in one patient. Of the 82 variants detected in this patient’s tumor, 15 (18.3%) were identified in both tissue and CSF, 15 (18.3%) were identified only in the tissue, and 52 (63.2%) were identified only in the CSF. CONCLUSIONS CSF NGS detects clinically meaningful variants at a substantial rate and frequently identifies mutations not detected by matched tissue NGS. These results suggest that CSF may be a suitable source material for tumor profiling, overcoming the limitations of tissue, and may also provide a more comprehensive tumor profile.

PURPOSE Differentiation of tumor progression (TP) from pseudoprogression (PsP) is a major unmet need in post-treatment glioblastoma (GBM). 18F-Fluciclovine is a synthetic amino acid PET radiotracer with higher uptake in tumor tissue vs. areas of treatment-related change. We investigated the value of 18F-Fluciclovine PET for differentiating PsP from TP independent from and in combination with multi-parametric MRI. METHODS We prospectively enrolled 30 patients with GBM with a new or enlarging contrast-enhancing lesion on MRI after chemoradiotherapy who were planned for surgical resection of the lesion. Patients underwent pre-operative 18F-Fluciclovine PET and multi-parametric MRI. Following surgery, the relative percentages of viable tumor and therapy-related changes observed in histopathology were quantified. Patients were categorized as TP if viable tumor represented ≥ 50% of the specimen, mixed TP if < 50% and > 10%, and PsP if ≤ 10%. RESULTS 18 patients had TP, 4 had mixed TP, and 8 PsP. Patients with TP/mixed TP had a significantly higher 40-50 minutes SUVmax (6.64 + 1.88 vs 4.11± 1.52, p=0.009) and an SUVmax cut-off of 4.66 provided 90% sensitivity and 83% specificity for differentiation of TP/mixed TP from PsP (AUC=0.856). A maximum cerebral blood volume (CBVmax) cut-off of 3.67 provided 90% sensitivity and 71% specificity for differentiation of TP/mixed TP from PsP (AUC=0.779). Combining a 40-50 minutes SUVmax cut-off of 4.662 and a relative CBVmax cut-off of 3.67 provided 100% sensitivity and 80% specificity for differentiating TP/mixed TP from PsP (AUC=0.95). The time activity curve patterns and time to peaks were not different between the groups. Normalization of PET parameters to normal brain parenchyma were not helpful to differentiate the groups due to variability in radiotracer uptake in normal brain between subjects. CONCLUSION 18F-Fluciclovine PET uptake can accurately differentiate PsP from TP in GBM patients, with even more accurate differentiation achieved when combined with MRI.

Diffuse gliomas are fatal, immunologically cold tumors characterized by mutations in isocitrate dehydrogenase 1 or 2 (IDH1/2) genes. IDH mutations have been shown to result in global genomic hypermethylation and drastically altered transcriptomic landscape. We and others have shown that IDH mutation is direct responsible for the immunological cold landscape observed in IDH mutated glioma. Using a combination of animal models and patient-derived glioma stem cells (GSCs), we identify retinoic acid signaling as a primary regulator of innate and adaptive immune activation in IDHm gliomas. Using the Sleeping Beauty (SB) orthotopic murine model of IDH glioma, which faithfully recapitulates the TME seen in patients, we show that intracellular accumulation of oncometabolite 2-HG leads to hypermethylation and transcriptional repression of Retinol Binding Protein-1 (RBP1), which encode CRBP1, a key chaperone protein required for intracellular all-trans-retinoic-acid biosynthesis in glial cells. Restoration retinoic acid signaling through the addition of all-trans retinoic acid (ATRA) resulted in spontaneous tumor regression and prolonged survival. ATRA administration is further correlated with increased CD8, NK, M1 macrophages and decreased Treg and MDSC populations within the TME. Single-cell sequencing of the TME shows increased type I interferon signaling, myeloid cell polarization, T cell activation, and TCR diversity. Using knockdown and overexpression techniques in patient-derived GSCs, we show that CRBP1 activity is critical for NK mediated immune surveillance and cytotoxicity through regulation of NKG2D ligand expression and immune cell migration through differential regulation of CXCL12 and CCL2. In summary, epigenetic silencing of RBP1 by 2-HG induced hypermethylation leads to a global immune dysregulation resulting in an immunologically cold landscape. Restoration of retinoic acid signaling is a promising immunotherapeutic approach for the treatment of IDHm gliomas.

BACKGROUND We evaluated the combination of retifanlimab, INCAGN01876, and FSRT in patients with recurrent GBM. METHODS Phase II, single-center, 2 cohort study (A: single-arm non-surgical cohort; B, two-arm neoadjuvant/surgical cohort). Cohort A patients received pre-FSRT one-time doses of retifanlimab (500mg) and INCAGN01876 (300mg), FSRT (8 Gy x 3 fractions), and post-FSRT 28-day treatment cycles (retifanlimab, day 1; INCAGN01876, days 1, 15). Cohort B patients received pre-surgery doses of retifanlimab + INCAGN01876; subsequently, patients either went directly to resection (Sub-Arm 1) or to FSRT followed by resection (Sub-Arm 2). All patients resumed immunotherapy post-operatively. Primary endpoint: ORR in Cohort A. Data cut-off for this analysis was June 30, 2022. RESULTS Thirty-two evaluable patients: Cohort A, n=16; Cohort B, n=16 (Sub-Arm 1, n=8, Sub-Arm 2, n=8). Median follow-up time: Cohort A, 13.6 months; Cohort B, 8.8 months. Forty-four percent women, median age 64 (IQR, 55–65), 56% MGMT unmethylated. Most common grade 3/4 treatment-related AEs included cerebral edema (25%), lymphopenia (16%), and cognitive disturbance (13%). Efficacy in Cohort A: no objective responses observed, best response of stable disease achieved in 9/16 patients (56%), median PFS 3.9 months (95% CI 2.1 – 6.2 months), median OS 9.8 months (95% CI 8.3 months – not reached [NR]). Efficacy in Cohort B: median PFS NR, median OS 15.1 months (95% CI 8.5 months – NR). Median PFS and OS are longer in Cohort B Sub-Arm 2 compared to Cohort B Sub-Arm 1 (PFS, NR vs. 2.2 months, p = 0.009; OS, NR vs. 8.5 months, p=0.026). Results of tissue and blood-based immune correlative analyses will be presented. CONCLUSIONS The combination of retifanlimab, INCAGN01876, and FSRT is generally well-tolerated in patients with recurrent GBM when administered with or without surgical resection. Survival outcomes in the neoadjuvant cohort are encouraging, largely driven by patients that received neoadjuvant FSRT.

INTRODUCTION Preoperative stereotactic radiosurgery (SRS) is an emerging therapeutic strategy for treatment of brain metastasis requiring surgical resection. Prior reports have been highly-controlled, excluding very large brain metastases. Here, we report a prospectively-collected preoperative series reflective of a real-world neurosurgical patient cohort, with a particular focus on resumption of immunotherapy. METHODS Our series included Nf27 prospective preoperative compared to concurrently collected Nf37 postoperative patients. Demographic, SRS volumes/dose, pre/postoperative immunotherapy, and clinical outcomes were collected. Subsequent univariate comparisons between groups were performed. RESULTS Pre/postoperative tumor volumes (19.1 [range: 2.4-65.1] vs. 12.5 [3.6-80.3]cc, p=0.20); local tumor control at 1 year (77.6% vs. 71.4%, p=0.616); overall survival (1.0 [0.8-2.2] vs. 1.3 [0.7-NR] years, p=0.8) were comparable between groups. Rates of LMD (3.7% vs. 8.0%, p=0.39) and subsequent WBRT (8.0% vs. 16.2%, p=0.46) were not statistically different. OR time (168 vs. 173 min, p=0.64), estimated blood loss (133 vs. 180 mL, p=0.31), and wound infections (1 vs. 1, p=1.00) were not significantly different.An ostensible advantage to preoperative SRS is that steroids may be weaned more quickly to allow resumption of immunotherapy. Median steroid taper length was significantly shorter (8 vs. 21.5 days, p=0.007), and median daily Dexamethasone dose at 1 week post-op was significantly lower in the preoperative group (1 vs. 7mg d, p=0.007). All preoperative patients eligible for resumption of immunotherapy (Nf5) resumed treatment within 6 weeks. Conversely, only 2/6 in postoperative patients resumed treatment within 6 weeks, (p=0.07), while 4 failed to resume immunotherapy altogether. In patients initiating immunotherapy after OR/SRS, time to initiation was non-significantly lower in the preoperative group (52[38-84] vs.163[108-208] days, p=0.06). CONCLUSIONS Preoperative SRS is safe and provides comparable local tumor control rate even in large tumors ( >20cc). In patients requiring resumption of immunotherapy, preoperative SRS may provide a faster pathway towards resumption of systemic therapy.

Although KIT-mutant GISTs can be effectively treated with tyrosine kinase inhibitors (TKIs), many patients develop resistance to imatinib mesylate (IM) as well as the FDA-approved later-line agents sunitinib, regorafenib and ripretinib. Resistance mechanisms mainly involve secondary mutations in the KIT receptor tyrosine kinase gene indicating continued dependency on the KIT signaling pathway. The fact that the type of secondary mutation confers either sensitivity or resistance towards TKIs and the notion that secondary mutations exhibit intra- and intertumoral heterogeneity complicates the optimal choice of treatment in the imatinib-resistant setting. Therefore, new strategies that target KIT independently of its underlying mutations are urgently needed. Homoharringtonine (HHT) is a first-in-class inhibitor of protein biosynthesis and is FDA-approved for the treatment of chronic myeloid leukemia (CML) that is resistant to at least two TKIs. HHT has also shown activity in KIT-mutant mastocytosis models, which are intrinsically resistant to imatinib and most other TKIs. We hypothesized that HHT could be effective in GIST through downregulation of KIT expression and subsequent decrease of KIT activation and downstream signaling. Testing several GIST cell line models, HHT led to a significant reduction in nascent protein synthesis and was highly effective in the nanomolar range in IM-sensitive and IM-resistant GIST cell lines. HHT treatment resulted in a rapid and complete abolishment of KIT expression and activation, while KIT mRNA levels were minimally affected. The response to HHT involved induction of apoptosis as well as cell cycle arrest. The antitumor activity of HHT was confirmed in a GIST xenograft model. Taken together, inhibition of protein biosynthesis is a promising strategy to overcome TKI resistance in GIST.

Over the past decade, the use of induced pluripotent stem cells (IPSCs), as both direct therapeutics and building blocks for 3D in vitro models, has exhibited exciting potential in both helping to elucidate pathogenic mechanisms and treating diseases relevant to neurosurgery. Transplantation of IPSCs is being studied in neurological injuries and diseases, such as spinal cord injury and Parkinson's disease, whose clinical manifestations stem from underlying neuronal and/or axonal degeneration. Both animal models and clinical trials have shown that IPSCs have the ability to regenerate damaged neural tissue. Such evidence makes IPSCs a potentially promising therapeutic modality for patients who suffer from these neurological injuries/diseases. In addition, the cerebral organoid, a 3D assembly of IPSC aggregates that develops heterogeneous brain regions, has become the first in vitro model to closely recapitulate the complexity of the brain extracellular matrix, a 3-dimensional network of molecules that structurally and biochemically support neighboring cells. Cerebral organoids have become an exciting prospect for modeling and testing drug susceptibility of brain tumors, such as glioblastoma and metastatic brain cancer. As patient-derived organoid models are becoming more faithful to the brain, they are becoming an increasingly accurate substitute for patient clinical trials; such patient-less trials would protect the patient from potentially ineffective drugs, and speed up trial results and optimize cost. In this review, we aim to describe the role of IPSCs and cerebral organoids in treating and modeling diseases that are relevant to neurosurgery.

Purpose/Objective(s) Brain metastasis is a frequent cause of morbidity and mortality in stage IV cancer patients. Efforts to treat brain metastasis include surgical resection, whole brain radiation treatment (WBRT), and stereotactic radiosurgery (SRS). In contemporary times, SRS is deployed utilizing conformal, high dose radiation with rapid dose fall off to limit neurocognitive toxicity seen with WBRT. In the combined modality setting wherein surgical resection is required, post-operative SRS is utilized with excellent local control. However, several difficulties may arise from treatment in the post-operative setting. Changes to the tumor bed necessitating increased margin for uncertainty, increased treatment normal brain tissue, treatment in a hypoxic field may portend for less-than-ideal treatment. Therefore, pre-operative SRS is being explored due to potentially better-defined target, less target uncertainty, and reports of less radionecrosis and less leptomeningeal disease. Therefore, our group conducted a phase II clinical trial exploring the efficacy of the preoperative SRS approach in regard to local brain control, distant brain control, and overall survival. Materials/Methods A phase II institutional non-randomized clinical trial was initiated at UPMC Hillman Cancer Center enrolling patients with brain metastasis of any malignant histology. Lymphoma, leukemia, multiple myeloma, or germ cell tumors were excluded due to their radiosensitive nature. Patients were to receive SRS followed by surgical resection. Inclusion criteria included ≥18yo, KPS≥50 with a life expectancy of 12 weeks. Patients could have no more than four lesions measuring 1.5-4.0cm in size. Patients that had tumors Results A total of 24 patients were enrolled on study. One patient was deemed unresectable due to risk to the peri- rolandic location. Median number of brain metastasis treated was one (range 1-3). The most common treated histology was non-small cell lung carcinoma (NSCLC) (9). Median days from consult to SRS was 3.9 days. Median SRS dose and fraction was 16.5Gy [range: 15-24Gy] in a single fraction. The median number of surveillance MRIs performed was 6 [range 1-17]. Local brain control was 90%, 90%, and 74% at 6, 12, and 24 months. Distant brain control at 6, 12, and 24 months was 66%, 60%, and 54% respectively. Progression free survival (PFS) and overall survival (OS) at 6, 12, and 24 months were as followed [46%, 38%, 29%] and [66%, 58%, 50%] respectively. Conclusion Preoperative stereotactic radiosurgery appears to have excellent local control with a 6- and 12-month local control rates of 90%. Further study is warranted in the continued exploration of preoperative radiation therapy.

2015 Background: Glioblastoma (GBM) is associated with a high rate of venous thromboembolism (VTE), but there is little data to guide anticoagulation in GBM patients, in whom the risks of VTE must be balanced against the risk of intracranial hemorrhage (ICH). Methods: We performed a single-institution retrospective cohort study of patients with GBM diagnosed with VTE from 2014-2021 who were treated with low molecular weight heparin (LMWH) or a direct oral anticoagulant (DOAC). The cumulative incidence of ICH was compared between the LMWH and DOAC groups. The primary outcome was clinically relevant ICH within the first 30 days of anticoagulation, defined as any ICH that was fatal, symptomatic, required surgical intervention, and/or led to cessation of anticoagulation. Key secondary outcomes included clinically relevant ICH within 6 months, fatal ICH within 30 days and 6 months, any bleeding within 30 days and 6 months, and recurrent VTE within 6 months. Fisher’s exact test was used for comparison of primary and secondary endpoints between the two groups. Cumulative incidence curves were generated using the Kaplan-Meier method, and the cumulative incidence of clinically relevant ICH at both the 30-day timepoint and 6-month timepoint was compared between the DOAC and LMWH groups using the Gray test to account for death as a competing risk. Results: A total of 121 patients were identified in the primary cohort for 30-day outcome analyses (DOAC, n = 33; LMWH, n = 88). For 6-month outcome analyses, the cohort included only patients who were maintained on their initial anticoagulant (DOAC or LMWH) and did not switch anticoagulants during the 6 months following diagnosis of VTE (DOAC, n = 32; LMWH, n = 75). The cumulative incidence of clinically relevant ICH at 30 days was 0% (0/33) in the DOAC group and 9% (8/88) in the LMWH group (p = 0.11). The cumulative incidence of clinically relevant ICH at 6 months was 0% (0/32) in the DOAC group and 24% (18/75) in the LMWH group (p = 0.001), with 4 fatal ICHs in the LMWH group. Other outcomes are displayed in the Table. Conclusions: Our study suggests that DOACs are associated with a lower incidence of clinically relevant ICH in patients with GBM-associated VTE compared to LMWH. These data support the use of DOACs as a safe alternative to LMWH in patients with GBM.[Table: see text]

Glioblastoma is a highly malignant and incurable brain tumor characterized by intrinsic and adaptive resistance to immunotherapies. However, how glioma cells induce tumor immunosuppression and escape immunosurveillance remains poorly understood. Here, we find upregulation of cancer-intrinsic Chitinase-3-like-1 (CHI3L1) signaling modulating an immunosuppressive microenvironment by reprogramming tumor-associated macrophages (TAMs). Mechanistically, CHI3L1 binding with Galectin-3 (Gal3) selectively promotes TAM migration and infiltration with a protumor M2-like but not an antitumor M1-like phenotype in vitro and in vivo, governed by a transcriptional program of NFκB/CEBPβ in the CHI3L1/Gal3-PI3K/AKT/mTOR axis. Conversely, Galectin-3-binding protein (Gal3BP) negatively regulates this process by competing with Gal3 to bind CHI3L1. Administration of a Gal3BP mimetic peptide in syngeneic glioblastoma mouse models reverses immune suppression and attenuates tumor progression. These results shed light on the role of CHI3L1 protein complexes in immune evasion by glioblastoma and as a potential immunotherapeutic target for this devastating disease.

Background We and others have identified mutually exclusive molecular subgroups of meningiomas; however, the implications of this classification for clinical prognostication remain unclear. Integrated genomic and epigenomic analyses implicate unique oncogenic processes associated with each subgroup, suggesting the potential for divergent clinical courses. The aim of this study was to understand the associated clinical outcomes of each subgroup, as this could optimize treatment for patients. Methods We analyzed outcome data for 469 meningiomas of known molecular subgroup, including extent of resection, postoperative radiation, surveillance imaging, and time to recurrence, when applicable. Statistical relationships between outcome variables and subgroup were assessed. Features previously associated with recurrence were further investigated after stratification by subgroup. We used Kaplan–Meier analyses to compare progression-free survival, and identified factors significantly associated with recurrence using Cox proportional hazards modeling. Results Meningioma molecular subgroups exhibited divergent clinical courses at 2 years of follow-up, with several aggressive subgroups (NF2, PI3K, HH, tumor necrosis factor receptor–associated factor 7 [TRAF7]) recurring at an average rate of 22 times higher than others (KLF4, POLR2A, SMARCB1). PI3K-activated tumors recurred earlier than other subgroups but had intermediate long-term outcome. Among low-grade tumors, HH and TRAF7 meningiomas exhibited elevated recurrence compared with other subgroups. Recurrence of NF2 tumors was associated with male sex, high grade, and elevated Ki-67. Multivariate analysis identified molecular subgroup as an independent predictor of recurrence, along with grade and previous recurrence. Conclusion We describe distinct clinical outcomes and recurrence rates associated with meningioma molecular subgroups. Our findings emphasize the importance of genomic characterization to guide postoperative management decisions for meningiomas.

Glioblastoma (GBM) is the most fatal brain tumor in adults. Current survival rates of GBM remain below 2 years due to GBM’s aggressive cellular migration and genetically driven treatment escape pathways. Despite our rapidly increasing understanding of GBM biology, earlier diagnoses, and refined surgical techniques, only moderate survival benefits have been achieved. Nonetheless, the pressing need for better survival rates has brought forward a multitude of newer therapeutic approaches and opened the door for potential personalization of these modalities in the near future. We reviewed the published literature discussing the current state of knowledge regarding GBM biology and therapy and summarized the information that may point toward future personalized therapeutic strategies. Several novel modalities such as oncolytic viruses, targeted immune, and molecular therapies, and tumor treating fields have been introduced. To date, there is no single treatment modality for GBM, but rather a wide spectrum of combined modalities that address intratumoral cellular and genetic variabilities. While the current state of GBM research and clinical trial landscape may hold promise, current literature lacks any fruitful progress towards personalized GBM therapy. In this review, we are discussing our recent knowledge of the GBM genetic biologic landscape and the current advances in therapy, as well as providing a blueprint for an envisioned GBM management paradigm that should be personalized and adaptable to accommodate each patient’s diverse genetic variations and therapy response/escape patterns.

Background: Leptomeningeal disease (LMD) from melanoma is rapidly fatal with median overall survival between 6.9 weeks and 3.5 months. It is not known whether immune checkpoint inhibitors have a role in treating LMD. Case presentation: We report a 33-year-old male patient who developed LMD from a BRAF V600E-mutated melanoma brain metastasis, despite prior treatment with surgical resection, radiotherapy and dabrafenib/trametinib. He underwent whole brain radiotherapy with stereotactic radiotherapy to the lumbosacral spine, and was started on nivolumab, which led to prolonged remission lasting 2 years and 3 months, before disease progression and death. Conclusion: This is the first case report to highlight a potential long-term efficacy of radiotherapy and anti-PD-1 immunotherapy, in treating LMD from metastatic melanoma that is resistant to targeted therapy.

OBJECTIVEAkin to the nonoperative management of benign intracranial tumors, stereotactic body radiation therapy (SBRT) has emerged as a nonoperative treatment option for noninfiltrative primary spine tumors such as meningioma and schwannoma. The majority of initial series used higher doses of 16–24 Gy in 1–3 fractions. The authors hypothesized that lower doses (such as 12–13 Gy in 1 fraction) might provide an efficacy similar to that found with the dose de-escalation commonly used for intracranial radiosurgery to treat acoustic neuroma or meningioma and with a lower risk of toxicity.METHODSThe authors identified 38 patients in a prospectively maintained institutional radiosurgery database who were treated with definitive SBRT for a total of 47 benign primary spine tumors between 2004 and 2016. SBRT consisted of 9–21 Gy in 1–3 fractions using the CyberKnife (n = 11 [23%]), Synergy S (n = 21 [45%]), or TrueBeam (n = 15 [32%]) radiosurgery platform. For a comparison of SBRT doses, patients were dichotomized into 1 of 2 groups (low-dose or high-dose SBRT) using a cutoff biologically effective dose (BED10Gy) of 30 Gy. Tumor control was calculated from the date of SBRT to the last follow-up using Kaplan-Meier survival analysis, with comparisons between groups completed using a log-rank method. To account for potential indication bias, a propensity score analysis was completed based on the conditional probabilities of SBRT dose selection. Toxicity was graded using Common Terminology Criteria for Adverse Events version 4.0 with a focus on grade 3+ toxicity and the incidence of pain flare.RESULTSFor the 38 patients, the most common histological findings were meningioma (15 patients), schwannoma (13 patients), and hemangioblastoma (7 patients). The median age at SBRT was 58 years (range 25–91 years). The 47 treated lesions were located in the cervical (n = 18), thoracic (n = 19), or lumbosacral (n = 10) spine. Five (11%) lesions were lost to follow-up after SBRT. The median follow-up duration for the remaining 42 lesions was 54 months (range 1.2–133 months). Six (16%) patients (with a total of 8 lesions) experienced pain flare after SBRT; no significant predictor of pain flare was identified. No grade 3+ acute- or late-onset complication was noted. The 5-year local control rate was 76% (95% CI 61%–91%). No significant difference in local control according to dose, fractionation, previous radiation, surgery, tumor histology, age, treatment platform, planning target volume, or spine level treated was found. The 5-year local control rates for low- and high-dose treatments were 73% (95% CI 53%–93%) and 83% (95% CI 61%–100%) (p = 0.52). In propensity score–adjusted multivariable analysis, no difference in local control was identified (HR 0.30, 95% CI 0.02–5.40; p = 0.41).CONCLUSIONSLong-term follow-up of patients treated with SBRT for benign spinal lesions revealed no significant difference between low-dose (BED10Gy ≤ 30) and high-dose SBRT in local control, pain-flare rate, or long-term toxicity.

OBJECTIVERecent large-cohort sequencing studies have investigated the genomic landscape of meningiomas, identifying somatic coding alterations in NF2, SMARCB1, SMARCE1, TRAF7, KLF4, POLR2A, BAP1, and members of the PI3K and Hedgehog signaling pathways. Initial associations between clinical features and genomic subgroups have been described, including location, grade, and histology. However, further investigation using an expanded collection of samples is needed to confirm previous findings, as well as elucidate relationships not evident in smaller discovery cohorts.METHODSTargeted sequencing of established meningioma driver genes was performed on a multiinstitution cohort of 3016 meningiomas for classification into mutually exclusive subgroups. Relevant clinical information was collected for all available cases and correlated with genomic subgroup. Nominal variables were analyzed using Fisher’s exact tests, while ordinal and continuous variables were assessed using Kruskal-Wallis and 1-way ANOVA tests, respectively. Machine-learning approaches were used to predict genomic subgroup based on noninvasive clinical features.RESULTSGenomic subgroups were strongly associated with tumor locations, including correlation of HH tumors with midline location, and non-NF2 tumors in anterior skull base regions. NF2 meningiomas were significantly enriched in male patients, while KLF4 and POLR2A mutations were associated with female sex. Among histologies, the results confirmed previously identified relationships, and observed enrichment of microcystic features among “mutation unknown” samples. Additionally, KLF4-mutant meningiomas were associated with larger peritumoral brain edema, while SMARCB1 cases exhibited elevated Ki-67 index. Machine-learning methods revealed that observable, noninvasive patient features were largely predictive of each tumor’s underlying driver mutation.CONCLUSIONSUsing a rigorous and comprehensive approach, this study expands previously described correlations between genomic drivers and clinical features, enhancing our understanding of meningioma pathogenesis, and laying further groundwork for the use of targeted therapies. Importantly, the authors found that noninvasive patient variables exhibited a moderate predictive value of underlying genomic subgroup, which could improve with additional training data. With continued development, this framework may enable selection of appropriate precision medications without the need for invasive sampling procedures.

In recent years, health care has been increasingly delivered by interprofessional teams in the inpatient, outpatient, and transition-of-care arenas. For many reasons, effective communication between patient-centered care teams and patients is critically important in order to optimize care, ensure patient safety, and prevent medical and medication misadventures. In rapid-paced, high-stress medical environments, it is especially important to carefully evaluate the causes of all misadventures in a manner that avoids assigning blame and identifies the root causes and, through team activity, leads to development of remedies that reduce the likelihood of future misadventures. Using a series of illustrative cases, this paper seeks to bring attention to these issues and provide insights regarding some tools developed to assist in improving patient safety and effective team communication.

BACKGROUND CAN-2409 is a replication-deficient adenovirus that delivers HSV thymidine kinase to cancer cells, resulting in local conversion of orally administered valacyclovir into a toxic metabolite. Previously, a phase 1b/2 clinical trial of CAN-2409 combined with standard-of-care (SOC) demonstrated safety and improved survival in HGG patients. Addition of CAN-2409 to nivolumab has the potential to activate locally recruited lymphocytes and teach them to recognize tumor neoantigens, changing the ‘cold’ immunosuppressive tumor microenvironment, and synergizing with the activity mediated by immune checkpoint inhibitors. This notion is supported by preclinical experiments showing that the combination of CAN-2409 with anti-PD1 therapy was more effective than either treatment alone. METHODS This ongoing phase 1 clinical trial evaluates safety and initial efficacy of CAN-2409 combined with nivolumab and SOC in newly diagnosed HGG. CAN-2409 is injected during neurosurgery into the tumor bed, followed by 14-days of valacyclovir. Radiation starts within 8 (+/-4) days of surgery. Temozolomide is administered to MGMT-methylation positive patients only. Nivolumab is given every 2 weeks, up to 52-weeks. Deep immune profiling studies are ongoing and initial results will be available shortly. RESULTS From February 2019 to March 2021, 41 patients were enrolled and 35 were evaluable for safety from the combination of CAN-2409, nivolumab and SOC: 24 male and 11 female; 34 glioblastoma, 1 diffuse astrocytoma; 33 IDH-wildtype, 2 IDH-mutant; 15 MGMT-methylated, 20 unmethylated. Median age was 62-years (range 28-79), median KPS 90 (range 80-100). With 13 months median follow-up, no unexpected serious adverse events were observed, and 23 patients are still alive. The most frequent possibly related adverse events (>10%) were nausea, fatigue, fever, headache, and increased ALT. CONCLUSIONS The combination of CAN-2409 + nivolumab + SOC was well tolerated. Clinical follow-up and extensive biomarker analyses will provide a better understanding of the therapeutic potential of this approach.

Up to 80% of meningiomas are classified as clinically low-grade, however, a subset of these ‘benign’ cases will ultimately recur and require additional treatment. The role of molecular subgroup in meningioma recurrence has not been thoroughly investigated, despite correlations of this variable with other clinical features. Indeed, epigenetic and transcriptional evidence supports involvement of distinct oncogenic processes within each subgroup, and as shown in other brain tumors, this may result in divergent clinical courses. In the present study, we classified 429 meningiomas into six established molecular subgroups based on genomic driver, and investigated associations of each subgroup with tumor recurrence. At two years of follow-up, we observed differences in progression free survival curves among relatively aggressive (NF2-loss, PI3K-activated, Hedgehog-activated) and quiescent (KLF4-mutant, SMARCB1-mutant, POLR2A-mutant) subgroups (log rank p = 4.3 x 10-2), with the former group recurring at a rate 14x higher. We found PI3K-activated meningiomas recurred significantly earlier than other subgroups (average time to recurrence of 19.2 months; p = 2.2 x 10-2), though we observed an intermediate long-term outcome relative to the Hedgehog and NF2 lesions. Overall, Hedgehog tumors recurred significantly more frequently than other low-grade meningiomas (adj. p = 3.1 x 10-2), and this subgroup was found to be an independent predictor of progression free survival using cox proportional hazards modelling (HR = 3.1; p = 2.4 x 10-2). By contrast, the aggressiveness of NF2 meningiomas was found to depend upon gender, WHO grade, and elevated Ki-67 index, and this subgroup was not an independent prognostic predictor. Our results suggest molecular subgroup is predictive of recurrence in low-grade meningiomas, and thus is an important consideration in post-operative management decisions. Routine genotyping to detect Hedgehog and PI3K mutant lesions may identify patients that would benefit from closer follow-up and consideration of adjuvant therapies.