Inhibitory CD161 receptor identified in glioma-infiltrating T cells by single-cell analysis.

T cells are critical effectors of cancer immunotherapies, but little is known about their gene expression programs in diffuse gliomas. Here, we leverage single-cell RNA sequencing (RNA-seq) to chart the gene expression and clonal landscape of tumor-infiltrating T cells across 31 patients with isocitrate dehydrogenase (IDH) wild-type glioblastoma and IDH mutant glioma. We identify potential effectors of anti-tumor immunity in subsets of T cells that co-express cytotoxic programs and several natural killer (NK) cell genes. Analysis of clonally expanded tumor-infiltrating T cells further identifies the NK gene KLRB1 (encoding CD161) as a candidate inhibitory receptor. Accordingly, genetic inactivation of KLRB1 or antibody-mediated CD161 blockade enhances T cell-mediated killing of glioma cells in vitro and their anti-tumor function in vivo. KLRB1 and its associated transcriptional program are also expressed by substantial T cell populations in other human cancers. Our work provides an atlas of T cells in gliomas and highlights CD161 and other NK cell receptors as immunotherapy targets.

Autoimmune Disorders Associated With Surgical Remission of Cushing's Disease : A Cohort Study.

BACKGROUND: Glucocorticoids suppress inflammation. Autoimmune disease may occur after remission of Cushing's disease (CD). However, the development of autoimmune disease in this context is not well described. OBJECTIVE: To determine 1) the incidence of autoimmune disease in patients with CD after surgical remission compared with patients with nonfunctioning pituitary adenomas (NFPAs) and 2) the clinical presentation of and risk factors for development of autoimmune disease in CD after remission. DESIGN: Retrospective matched cohort analysis. SETTING: Academic medical center/pituitary center. PATIENTS: Patients with CD with surgical remission and surgically treated NFPA. MEASUREMENTS: Cumulative incidence of new-onset autoimmune disease at 3 years after surgery. Assessment for hypercortisolemia included late-night salivary cortisol levels, 24-hour urine free cortisol (UFC) ratio (UFC value divided by the upper limit of the normal range for the assay), and dexamethasone suppression tests. RESULTS: Cumulative incidence of new-onset autoimmune disease at 3 years after surgery was higher in patients with CD (10.4% [95% CI, 5.7% to 15.1%]) than in those with NFPAs (1.6% [CI, 0% to 4.6%]) (hazard ratio, 7.80 [CI, 2.88 to 21.10]). Patients with CD showed higher prevalence of postoperative adrenal insufficiency (93.8% vs. 16.5%) and lower postoperative nadir serum cortisol levels (63.8 vs. 282.3 nmol/L) than patients with NFPAs. Compared with patients with CD without autoimmune disease, those who developed autoimmune disease had a lower preoperative 24-hour UFC ratio (2.7 vs. 6.3) and a higher prevalence of family history of autoimmune disease (41.2% vs. 20.9%). LIMITATION: The small sample of patients with autoimmune disease limited identification of independent risk factors. CONCLUSION: Patients achieving surgical remission of CD have higher incidence of autoimmune disease than age- and sex-matched patients with NFPAs. Family history of autoimmune disease is a potential risk factor. Adrenal insufficiency may be a trigger. PRIMARY FUNDING SOURCE: Recordati Rare Diseases Inc.

A rapid genotyping panel for detection of primary central nervous system lymphoma.

Diagnosing primary central nervous system lymphoma (PCNSL) frequently requires neurosurgical biopsy due to nonspecific radiologic features and the low yield of cerebrospinal fluid (CSF) studies. We characterized the clinical evaluation of suspected PCNSL (N = 1007 patients) and designed a rapid multiplexed genotyping assay for MYD88, TERT promoter, IDH1/2, H3F3A, and BRAF mutations to facilitate the diagnosis of PCNSL from CSF and detect other neoplasms in the differential diagnosis. Among 159 patients with confirmed PCNSL, the median time to secure a diagnosis of PCNSL was 10 days, with a range of 0 to 617 days. Permanent histopathology confirmed PCNSL in 142 of 152 biopsies (93.4%), whereas CSF analyses were diagnostic in only 15/113 samplings (13.3%). Among 86 archived clinical specimens, our targeted genotyping assay accurately detected hematologic malignancies with 57.6% sensitivity and 100% specificity (95% confidence interval [CI]: 44.1% to 70.4% and 87.2% to 100%, respectively). MYD88 and TERT promoter mutations were prospectively identified in DNA extracts of CSF obtained from patients with PCNSL and glioblastoma, respectively, within 80 minutes. Across 132 specimens, hallmark mutations indicating the presence of malignancy were detected with 65.8% sensitivity and 100% specificity (95% CI: 56.2%-74.5% and 83.9%-100%, respectively). This targeted genotyping approach offers a rapid, scalable adjunct to reduce diagnostic and treatment delays in PCNSL.

Microscale Physiological Events on the Human Cortical Surface.

Despite ongoing advances in our understanding of local single-cellular and network-level activity of neuronal populations in the human brain, extraordinarily little is known about their "intermediate" microscale local circuit dynamics. Here, we utilized ultra-high-density microelectrode arrays and a rare opportunity to perform intracranial recordings across multiple cortical areas in human participants to discover three distinct classes of cortical activity that are not locked to ongoing natural brain rhythmic activity. The first included fast waveforms similar to extracellular single-unit activity. The other two types were discrete events with slower waveform dynamics and were found preferentially in upper cortical layers. These second and third types were also observed in rodents, nonhuman primates, and semi-chronic recordings from humans via laminar and Utah array microelectrodes. The rates of all three events were selectively modulated by auditory and electrical stimuli, pharmacological manipulation, and cold saline application and had small causal co-occurrences. These results suggest that the proper combination of high-resolution microelectrodes and analytic techniques can capture neuronal dynamics that lay between somatic action potentials and aggregate population activity. Understanding intermediate microscale dynamics in relation to single-cell and network dynamics may reveal important details about activity in the full cortical circuit.

Pituitary surgery in Cushing's disease: first line treatment and role of reoperation.

Cushing's disease is the most common cause of endogenous hypercortisolemia, and transsphenoidal surgery remains the first line therapy for removal of the ACTH-secreting adenoma. While post-operative remission rates are high in experienced hands, there remains a 2% risk of recurrence per year. Patients with the highest chance for cure are those with small, non-invasive tumors that are visible on pre-operative MRI and identified during surgery and are performed by high-volume pituitary neurosurgeons. Surgery for persistent or recurrent disease is frequently indicated and is most successful in the hands of experienced surgeons and in cases where tumor is visible on MRI.

Introduction to special issue dedicated to the 35th anniversary of the joint section on tumors.

The American Association of Neurological Surgeons (AANS)/Congress of Neurological Surgeons (CNS) Joint Section on Tumors was formed in December of 1984 as the first professional organization devoted to the study and treatment of brain tumors. One year earlier, the Journal of Neuro-Oncology had been established and went on to be sponsored by the Joint Section on Tumors. To celebrate the 35th anniversary of the founding of the Section, we are thrilled to bring you this special issue of Journal of Neuro-Oncology in which current leaders of the Joint Section on Tumors highlight their work and the work of others that have led to significant recent advances in the management of tumors of the central nervous system.

Intraoperative MRI for Brain Tumors.

INTRODUCTION: The use of intraoperative imaging has been a critical tool in the neurosurgeon's armamentarium and is of particular benefit during tumor surgery. This article summarizes the history of its development, implementation, clinical experience and future directions. METHODS: We reviewed the literature focusing on the development and clinical experience with intraoperative MRI. Utilizing the authors' personal experience as well as evidence from the literature, we present an overview of the utility of MRI during neurosurgery. RESULTS: In the 1990s, the first description of using a low field MRI in the operating room was published describing the additional benefit provided by improved resolution of MRI as compared to ultrasound. Since then, implementation has varied in magnetic field strength and in configuration from floor mounted to ceiling mounted units as well as those that are accessible to the operating room for use during surgery and via an outpatient entrance to use for diagnostic imaging. The experience shows utility of this technique for increasing extent of resection for low and high grade tumors as well as preventing injury to important structures while incorporating techniques such as intraoperative monitoring. CONCLUSION: This article reviews the history of intraoperative MRI and presents a review of the literature revealing the successful implementation of this technology and benefits noted for the patient and the surgeon.

Pituitary society expert Delphi consensus: operative workflow in endoscopic transsphenoidal pituitary adenoma resection.

PURPOSE: Surgical workflow analysis seeks to systematically break down operations into hierarchal components. It facilitates education, training, and understanding of surgical variations. There are known educational demands and variations in surgical practice in endoscopic transsphenoidal approaches to pituitary adenomas. Through an iterative consensus process, we generated a surgical workflow reflective of contemporary surgical practice. METHODS: A mixed-methods consensus process composed of a literature review and iterative Delphi surveys was carried out within the Pituitary Society. Each round of the survey was repeated until data saturation and > 90% consensus was reached. RESULTS: There was a 100% response rate and no attrition across both Delphi rounds. Eighteen international expert panel members participated. An extensive workflow of 4 phases (nasal, sphenoid, sellar and closure) and 40 steps, with associated technical errors and adverse events, were agreed upon by 100% of panel members across rounds. Both core and case-specific or surgeon-specific variations in operative steps were captured. CONCLUSIONS: Through an international expert panel consensus, a workflow for the performance of endoscopic transsphenoidal pituitary adenoma resection has been generated. This workflow captures a wide range of contemporary operative practice. The agreed "core" steps will serve as a foundation for education, training, assessment and technological development (e.g. models and simulators). The "optional" steps highlight areas of heterogeneity of practice that will benefit from further research (e.g. methods of skull base repair). Further adjustments could be made to increase applicability around the world.

Navigating the Landscape of Tumor Extracellular Vesicle Heterogeneity.

The last decade has seen a rapid expansion of interest in extracellular vesicles (EVs) released by cells and proposed to mediate intercellular communication in physiological and pathological conditions. Considering that the genetic content of EVs reflects that of their respective parent cell, many researchers have proposed EVs as a source of biomarkers in various diseases. So far, the question of heterogeneity in given EV samples is rarely addressed at the experimental level. Because of their relatively small size, EVs are difficult to reliably isolate and detect within a given sample. Consequently, standardized protocols that have been optimized for accurate characterization of EVs are lacking despite recent advancements in the field. Continuous improvements in pre-analytical parameters permit more efficient assessment of EVs, however, methods to more objectively distinguish EVs from background, and to interpret multiple single-EV parameters are lacking. Here, we review EV heterogeneity according to their origin, mode of release, membrane composition, organelle and biochemical content, and other factors. In doing so, we also provide an overview of currently available and potentially applicable methods for single EV analysis. Finally, we examine the latest findings from experiments that have analyzed the issue at the single EV level and discuss potential implications.

Ipilimumab and craniotomy in patients with melanoma and brain metastases: a case series.

OBJECT In patients with large or symptomatic brain lesions from metastatic melanoma, the value of resection of metastases to facilitate administration of systemic ipilimumab therapy has not yet been described. The authors undertook this study to investigate whether craniotomy creates the opportunity for patients to receive and benefit from ipilimumab who would otherwise succumb to brain metastasis prior to the onset of regression. METHODS All patients with metastatic melanoma who received ipilimumab and underwent craniotomy for metastasis resection between 2008 and 2014 at the Massachusetts General Hospital were identified through retrospective chart review. The final analysis included cases involving patients who underwent craniotomy within 3 months prior to initiation of therapy or up to 6 months after cessation of ipilimumab administration. RESULTS Twelve patients met the inclusion criteria based on timing of therapy (median age 59.2). The median number of metastases at the time of craniotomy was 2. The median number of ipilimumab doses received was 4. Eleven of 12 courses of ipilimumab were stopped for disease progression, and 1 was stopped for treatment-induced colitis. Eight of 12 patients had improvement in their performance status following craniotomy. Of the 6 patients requiring corticosteroids prior to craniotomy, 3 tolerated corticosteroid dose reduction after surgery. Ten of 12 patients had died by the time of data collection, with 1 patient lost to follow-up. The median survival after the start of ipilimumab treatment was 7 months. CONCLUSIONS In this series, patients who underwent resection of brain metastases in temporal proximity to receiving ipilimumab had qualitatively improved performance status following surgery in most cases. Surgery facilitated corticosteroid reduction in select patients. Larger analyses are required to better understand possible synergies between craniotomy for melanoma metastases and ipilimumab treatment.

Neurological Surgery Residency Programs in the United States: A National Cross-Sectional Survey.

BACKGROUND AND OBJECTIVES: The Accreditation Council for Graduate Medical Education has approved 117 neurological surgery residency programs which develop and educate neurosurgical trainees. We present the current landscape of neurosurgical training in the United States by examining multiple aspects of neurological surgery residencies in the 2022-2023 academic year and investigate the impact of program structure on resident academic productivity. METHODS: Demographic data were collected from publicly available websites and reports from the National Resident Match Program. A 34-question survey was circulated by e-mail to program directors to assess multiple features of neurological surgery residency programs, including curricular structure, fellowship availability, recent program changes, graduation requirements, and resources supporting career development. Mean resident productivity by program was collected from the literature. RESULTS: Across all 117 programs, there was a median of 2.0 (range 1.0-4.0) resident positions per year and 1.0 (range 0.0-2.0) research/elective years. Programs offered a median of 1.0 (range 0.0-7.0) Committee on Advanced Subspecialty Training-accredited fellowships, with endovascular fellowships being most frequently offered (53.8%). The survey response rate was 75/117 (64.1%). Of survey respondents, the median number of clinical sites was 3.0 (range 1.0-6.0). Almost half of programs surveyed (46.7%) reported funding mechanisms for residents, including R25, T32, and other in-house grants. Residents received a median academic stipend of $1000 (range $0-$10 000) per year. Nearly all programs (93.3%) supported wellness activities for residents, which most frequently occurred quarterly (46.7%). Annual academic stipend size was the only significant predictor of resident academic productivity (R 2 = 0.17, P = .002). CONCLUSION: Neurological surgery residency programs successfully train the next generation of neurosurgeons focusing on education, clinical training, case numbers, and milestones. These programs offer trainees the chance to tailor their career trajectories within residency, creating a rewarding and personalized experience that aligns with their career aspirations.

The inactive X chromosome drives sex differences in microglial inflammatory activity in human glioblastoma.

Biological sex is an important risk factor in cancer, but the underlying cell types and mechanisms remain obscure. Since tumor development is regulated by the immune system, we hypothesize that sex-biased immune interactions underpin sex differences in cancer. The male-biased glioblastoma multiforme (GBM) is an aggressive and treatment-refractory tumor in urgent need of more innovative approaches, such as considering sex differences, to improve outcomes. GBM arises in the specialized brain immune environment dominated by microglia, so we explored sex differences in this immune cell type. We isolated adult human TAM-MGs (tumor-associated macrophages enriched for microglia) and control microglia and found sex-biased inflammatory signatures in GBM and lower-grade tumors associated with pro-tumorigenic activity in males and anti-tumorigenic activity in females. We demonstrated that genes expressed or modulated by the inactive X chromosome facilitate this bias. Together, our results implicate TAM-MGs, specifically their sex chromosomes, as drivers of male bias in GBM.

Radical surgical resection with molecular margins is associated with improved survival in IDH wildtype GBM.

BACKGROUND: Survival is variable in patients with glioblastoma IDH wild-type (GBM), even after comparable surgical resection of radiographically-detectable disease, highlighting the limitations of radiographic assessment of infiltrative tumor anatomy. The majority of post-surgical progressive events are failures within 2cm of the resection margin, motivating supramaximal resection strategies to improve local control. However, which patients benefit from such radical resections remains unknown. METHODS: We developed a predictive model to identify which IDH wild-type GBM are amenable to radiographic gross total resection (GTR). We then investigated whether GBM survival heterogeneity following GTR is correlated with microscopic tumor burden a by analyzing tumor cell content at the surgical margin with a rapid qPCR-based method for detection of TERT promoter mutation. RESULTS: Our predictive model for achievable GTR, developed on retrospective radiographic and molecular data of GBM patients undergoing resection, had an AUC of 0.83, sensitivity of 62%, and specificity of 90%. Prospective analysis of this model in 44 patients found 89% of patients were correctly predicted to achieve a RV<4.9cc. Of the 44 prospective patients undergoing rapid qPCR TERT promoter mutation analysis at the surgical margin, 7 had undetectable TERT mutation, of which 5 also had a gross total resection (RV<1cc). In these 5 patients at 30 months follow up, 75% showed no progression, compared to 0% in the group with TERT mutations detected at the surgical margin (p=0.02). CONCLUSIONS: These findings identify a subset of patients with GBM that may derive local control benefit from radical resection to undetectable molecular margins.

Glioblastoma-Infiltrating CD8+ T Cells Are Predominantly a Clonally Expanded GZMK+ Effector Population.

Recent clinical trials have highlighted the limited efficacy of T cell-based immunotherapy in patients with glioblastoma (GBM). To better understand the characteristics of tumor-infiltrating lymphocytes (TIL) in GBM, we performed cellular indexing of transcriptomes and epitopes by sequencing and single-cell RNA sequencing with paired V(D)J sequencing, respectively, on TILs from two cohorts of patients totaling 15 patients with high-grade glioma, including GBM or astrocytoma, IDH-mutant, grade 4 (G4A). Analysis of the CD8+ TIL landscape reveals an enrichment of clonally expanded GZMK+ effector T cells in the tumor compared with matched blood, which was validated at the protein level. Furthermore, integration with other cancer types highlights the lack of a canonically exhausted CD8+ T-cell population in GBM TIL. These data suggest that GZMK+ effector T cells represent an important T-cell subset within the GBM microenvironment and may harbor potential therapeutic implications. SIGNIFICANCE: To understand the limited efficacy of immune-checkpoint blockade in GBM, we applied a multiomics approach to understand the TIL landscape. By highlighting the enrichment of GZMK+ effector T cells and the lack of exhausted T cells, we provide a new potential mechanism of resistance to immunotherapy in GBM. This article is featured in Selected Articles from This Issue, p. 897.

Molecular genetics of low-grade gliomas: genomic alterations guiding diagnosis and therapeutic intervention. 11th annual Frye-Halloran Brain Tumor Symposium.

OBJECT: The authors' goal was to review the current understanding of the underlying molecular and genetic mechanisms involved in low-grade glioma development and how these mechanisms can be targets for detection and treatment of the disease and its recurrence. METHODS: On October 4, 2012, the authors convened a meeting of researchers and clinicians across a variety of pertinent medical specialties to review the state of current knowledge on molecular genetic mechanisms of low-grade gliomas and to identify areas for further research and drug development. RESULTS: The meeting consisted of 3 scientific sessions ranging from neuropathology of IDH1 mutations; CIC, ATRX, and FUBP1 mutations in oligodendrogliomas and astrocytomas; and IDH1 mutations as therapeutic targets. Sessions consisted of a total of 10 talks by international leaders in low-grade glioma research, mutant IDH1 biology and its application in glioma research, and treatment. CONCLUSIONS: The recent discovery of recurrent gene mutations in low-grade glioma has increased the understanding of the molecular mechanisms involved in a host of biological activities related to low-grade gliomas. Understanding the role these genetic alterations play in brain cancer initiation and progression will help lead to the development of novel treatment modalities than can be personalized to each patient, thereby helping transform this now often-fatal malignancy into a chronic or even curable disease.

Skull Base Tumors.

OBJECTIVE: This article reviews the presenting features, molecular characteristics, diagnosis, and management of selected skull base tumors, including meningiomas, vestibular schwannomas, pituitary neuroendocrine tumors, craniopharyngiomas, chordomas, ecchordosis physaliphora, chondrosarcomas, esthesioneuroblastomas, and paragangliomas. LATEST DEVELOPMENTS: Skull base tumors pose a management challenge given their complex location and, as a result, the tumors and treatment can result in significant morbidity. In most cases, surgery, radiation therapy, or both yield high rates of disease control, but the use of these therapies may be limited by the surgical accessibility of these tumors and their proximity to critical structures. The World Health Organization classification of pituitary neuroendocrine tumors was updated in 2022. Scientific advances have led to an enhanced understanding of the genetic drivers of many types of skull base tumors and have revealed several potentially targetable genetic alterations. This information is being leveraged in the design of ongoing clinical trials, with the hope of rendering these challenging tumors treatable through less invasive and morbid measures. ESSENTIAL POINTS: Tumors involving the skull base are heterogeneous and may arise from bony structures, cranial nerves, the meninges, the sinonasal tract, the pituitary gland, or embryonic tissues. Treatment often requires a multidisciplinary approach, with participation from radiation oncologists, medical oncologists, neuro-oncologists, and surgical specialists, including neurosurgeons, otolaryngologists, and head and neck surgeons. Treatment has largely centered around surgical resection, when feasible, and the use of first-line or salvage radiation therapy, with chemotherapy, targeted therapy, or both considered in selected settings. Our growing understanding of the molecular drivers of these diseases may facilitate future expansion of pharmacologic options to treat skull base tumors.

Spontaneous rupture of an arachnoid cyst in an adult: illustrative case.

BACKGROUND: Arachnoid cysts are common intracranial mass lesions frequently discovered as incidental findings on radiographic imaging. It is routine practice to monitor these lesions as a large majority remain stable. Although traumatic cyst rupture is a known risk, it is rare for patients to present with spontaneous rupture. OBSERVATIONS: The authors report the case of a 32-year-old patient who required emergent neurosurgical intervention for spontaneous rupture of a left hemispheric arachnoid cyst. LESSONS: Patients with ruptured arachnoid cysts can present with vague, nonspecific symptoms that may delay diagnosis. If not diagnosed and treated promptly, arachnoid cyst rupture can progress to a neurosurgical emergency as the subdural collection may cause extensive mass effect and even cerebral herniation.

Treatment of IgG4-related disease-associated hypertrophic pachymeningitis with intrathecal rituximab: a case report.

IgG4-related disease-associated hypertrophic pachymeningitis (IgG4RD-HP) is a fibroinflammatory autoimmune disorder in which diagnosis is difficult without biopsy. Guidance on management of disease refractory to glucocorticoids and intravenous rituximab is limited. We present the case of a 68-year-old woman with IgG4RD-HP who developed sensorineural hearing loss with associated bulky basilar pachymeningeal enhancement. Her cerebrospinal fluid was inflammatory and had an elevated IgG4 concentration, strongly suggestive of IgG4RD-HP. Biopsy of involved meninges was not possible due to surgical risk. Over years she developed bilateral optic neuropathies and hydrocephalus, requiring intravenous rituximab and ventriculoperitoneal shunt. Her disease was refractory to glucocorticoids. Despite maintenance intravenous rituximab, she developed slowly progressive symptoms of intracranial hypertension and hydrocephalus with persistently inflammatory spinal fluid. Switching to intrathecal rituximab therapy led to dramatic improvement in gait and headache and reduced pachymeningeal bulk and metabolic activity. In patients with IgG4RD-HP refractory to glucocorticoids and intravenous rituximab, intrathecal rituximab may be an efficacious therapy.