The longitudinal risk of hemorrhage of melanoma brain metastases after Gamma Knife radiosurgery

OBJECTIVE

The objective of this study was to analyze the hemorrhagic risk of melanoma brain metastases after Gamma Knife radiosurgery (GKRS).

METHODS

A prospective institutional database was retrospectively queried to identify patients who underwent GKRS for melanoma brain metastases between 1990 and 2021. Lesional hemorrhage was defined as definite or possible based on radiologists' readings, and severity was graded according to Common Terminology Criteria for Adverse Events.

RESULTS

Two hundred ninety-one patients with 1083 lesions treated in 419 sessions were identified. The mean (± SD) patient age was 60 ± 15 years, and 61% were male. The median follow-up period for overall survival (OS) was 11 (range 0-214) months with 581 patient-years. Definite/possible lesional hemorrhages occurred in 13% of lesions, with grade 3 hemorrhages observed in 4% of lesions. Surgical intervention was required in 2% of cases (5% of patients), and all resected lesions were pathologically consistent with melanoma. A decreased risk of definite/possible lesional hemorrhage was associated with a later time period between 2015 and 2021 (OR 0.45, 95% CI 0.266-0.75, p = 0.0021), increased marginal dose (OR 0.91, 95% CI 0.83-0.99, p = 0.037), antiplatelet use post-GKRS (OR 0.195, 95% CI 0.083-0.46, p < 0.001), and whole-brain radiotherapy (WBRT; OR 0.53, 95% CI 0.344-0.82, p = 0.0042). After 2015, more patients received anticoagulation, B-Raf proto-oncogene inhibitors, and immune checkpoint inhibitors, and fewer received bevacizumab (p < 0.001). The cumulative risk of lesional hemorrhage was 17%-20% at 36 months from GKRS, with 95%-96% of cases occurring within 12 months. The median patient OS was 11 (95% CI 9-13) months, and multivariate Cox regression analysis revealed that antiplatelet agents (hazard ratio [HR] 0.66, 95% CI 0.45-0.96, p = 0.031) and immune checkpoint inhibitors (HR 0.35, 95% CI 0.26-0.48, p < 0.001) were associated with longer OS, while WBRT (HR 1.36, 95% CI 1.02-1.81, p = 0.037) and definite/possible hemorrhage (HR 1.39, 95% CI 1.04-1.85, p = 0.024) were associated with shorter OS.

CONCLUSIONS

The definite hemorrhage risk of melanoma brain metastases after GKRS was 17% in the first 3 years and 95% of the lesional hemorrhage occurred within the 1st year. Surgical intervention was needed in 5% of patients. Antiplatelet agents and immune checkpoint inhibitors were associated with improved OS, while definite/possible hemorrhage was associated with worse OS.

Pre-operative vs. post-operative stereotactic radiosurgery for operative metastatic brain tumors: study protocol for a phase III clinical trial

BACKGROUND AND OBJECTIVES

Almost one third of cancer patients in the United States will develop brain metastases on an annual basis. Surgical resection is indicated in the setting of brain metastases for reasons, such as maximizing local control in select patients, decompression of mass effect, and/or tissue diagnosis. The current standard of care following resection of a brain metastasis has shifted from whole brain radiation therapy to post-operative stereotactic radiosurgery (SRS). However, there is a significant rate of local recurrence within one year of postoperative SRS. Emerging retrospective and prospective data suggest pre-operative SRS is a safe and potentially effective treatment paradigm for surgical brain metastases. This trial intends to determine, for patients with an indication for resection of a brain metastasis, whether there is an increase in the time to a composite endpoint of adverse outcomes; including the first occurrence of either: local recurrence, leptomeningeal disease, or symptomatic radiation brain necrosis - in patients who receive pre-operative SRS as compared to patients who receive post-operative SRS.

METHODS

This randomized phase III clinical trial compares pre-operative with post-operative SRS for brain metastases. A dynamic random allocation procedure will allocate an equal number of patients to each arm: pre-operative SRS followed by surgery or surgery followed by post-operative SRS.

EXPECTED OUTCOMES

If pre-operative SRS improves outcomes relative to post-operative SRS, this will establish pre-operative SRS as superior. If post-operative SRS proves superior to pre-operative SRS, it will remain a standard of care and halt the increasing utilization of pre-operative SRS. If there is no difference in pre- versus post-operative SRS, then pre-operative SRS may still be preferred, given patient convenience and the potential for a condensed timeline.

DISCUSSION

Emerging retrospective and prospective data have demonstrated some benefits of pre-op SRS vs. post-op SRS. This study will show whether there is an increase in the time to the composite endpoint. Additionally, the study will compare overall survival; patient-reported outcomes; morbidity; completion of planned therapies; time to systemic therapy; time to regional progression; time to CNS progression; time to subsequent treatment; rate of radiation necrosis; rate of local recurrence; and rate of leptomeningeal disease.

TRIAL REGISTRATION NUMBER

NCT03750227 (Registration date: 21/11/2018).

Safety of the immediate use of nonsteroidal anti-inflammatory drugs after adult craniotomy for tumor

OBJECTIVE

Poor pain control has a negative impact on postoperative recovery and patient satisfaction. However, overzealous pain management, particularly with opioids, can confound serial neurological assessments, increase morbidity, and predispose patients to long-term dependence. Nonsteroidal anti-inflammatory drugs (NSAIDs) are effective in treating postoperative pain and can limit opioid intake, but their use has been limited in patients undergoing craniotomy for brain tumor resection due to concerns of an increased hemorrhage risk. Herein, the authors aim to 1) address the safety of NSAID use in the immediate postoperative setting and 2) determine whether NSAID administration decreases opioid use following craniotomy for tumor resection in adult patients.

METHODS

The authors conducted a retrospective cohort study of patients 18 years and older with an estimated glomerular filtration rate ≥ 60 ml/min/body surface area who had undergone craniotomy for tumor resection at their institution between 2019 and 2021. NSAID use in the first 48 hours following surgery was recorded. Primary outcomes were postoperative hemorrhage requiring a return to the operating room before hospital discharge and within 30 days of surgery. Secondary outcomes were more-than-minimal hemorrhage that did not require reoperation, acute kidney injury, and total opioid use within 48 hours after craniotomy.

RESULTS

Among 1765 reviewed patient records, 1182 were eligible for inclusion in this analysis. Amid these records were 114 patients (9.6%) who had received at least one dose of an NSAID within 48 hours of their craniotomy. Four (0.3%) patients experienced bleeding requiring a return to operating room, one of whom was from the NSAID-treated group (RR 3.12, 95% CI 0.33-29.77, p = 0.30). No significant difference in nonoperative intracranial hemorrhage (RR 1.34, 95% CI 0.54-3.35, p = 0.53), postoperative acute kidney injury, or clinically significant extracranial bleeding was found between the NSAID and no-NSAID groups. Patients in the NSAID group had significantly higher oral morphine equivalent use (median 68 vs 30, p < 0.001).

CONCLUSIONS

Postoperative NSAID use following craniotomy for tumor resection was not associated with an increased risk of hemorrhage requiring a return to the operating room. The authors noted higher opioid use in the patients treated with NSAIDs, which may reflect underlying reasons for the decision to treat patients with NSAIDs in the immediate postoperative period. These data warrant further investigation of NSAIDs as a safe, opioid-sparing postoperative pain management strategy in patients with normal kidney function who are undergoing intracranial tumor resection.

Carcinoembryonic antigen-expressing oncolytic measles virus derivative in recurrent glioblastoma: a phase 1 trial

Measles virus (MV) vaccine strains have shown significant preclinical antitumor activity against glioblastoma (GBM), the most lethal glioma histology. In this first in human trial (NCT00390299), a carcinoembryonic antigen-expressing oncolytic measles virus derivative (MV-CEA), was administered in recurrent GBM patients either at the resection cavity (Group A), or, intratumorally on day 1, followed by a second dose administered in the resection cavity after tumor resection on day 5 (Group B). A total of 22 patients received study treatment, 9 in Group A and 13 in Group B. Primary endpoint was safety and toxicity: treatment was well tolerated with no dose-limiting toxicity being observed up to the maximum feasible dose (2×107 TCID50). Median OS, a secondary endpoint, was 11.6 mo and one year survival was 45.5% comparing favorably with contemporary controls. Other secondary endpoints included assessment of viremia, MV replication and shedding, humoral and cellular immune response to the injected virus. A 22 interferon stimulated gene (ISG) diagonal linear discriminate analysis (DLDA) classification algorithm in a post-hoc analysis was found to be inversely (R = -0.6, p = 0.04) correlated with viral replication and tumor microenvironment remodeling including proinflammatory changes and CD8 + T cell infiltration in post treatment samples. This data supports that oncolytic MV derivatives warrant further clinical investigation and that an ISG-based DLDA algorithm can provide the basis for treatment personalization.

Clinical presentation, role of surgery and prognosis in spinal astrocytoma: Cohort study

Spinal astrocytoma is a rare neoplasm with discouraging prognosis, which accounts for 6-8 % of total intramedullary spinal tumors. As this is a rare entity, details of the clinical and molecular features have not been fully unraveled. We evaluated the radiologic findings, perioperative clinical presentation, histopathological features and treatment response in a single institution series of 37 consecutive cases of spinal astrocytomas (WHO grades 1 to 4). We identified 8, 16, 8, and 5 patients with grade 1, 2, 3, and 4 lesions, respectively, from 1988 to 2017. Peak ages were youngest in grade 1, followed in order by grades 4, 3 and 2. Whereas all cases of grade 1 and 4 enhanced with contrast, less than half of the cases of grade 2 tumors enhanced (44 %). Grade 3 tumors had a higher rate of multiplicity at presentation (50 %). A concomitant brain lesion at presentation was present in 14 % and 43 % of grade 2 and 3 lesions, respectively. Progression-free and overall survival were worse in grades 3 and 4 compared to grade 2 lesions but no significant difference was observed between grade 3 and 4. Many patients (16-of-36) experienced new neurological deficits postoperatively regardless of grade. Most patients (88 %) required postoperative rehabilitation, and 61 % were not discharged to home. Discharge destination closely correlated with age (p = 0.002). These clinical findings may be useful in understanding the clinical phenotype and improving the management of this rare disease.

Methodological and analytical considerations for intra-operative microdialysis

BACKGROUND

Microdialysis is a technique that can be utilized to sample the interstitial fluid of the central nervous system (CNS), including in primary malignant brain tumors known as gliomas. Gliomas are mainly accessible at the time of surgery, but have rarely been analyzed via interstitial fluid collected via microdialysis. To that end, we obtained an investigational device exemption for high molecular weight catheters (HMW, 100 kDa) and a variable flow rate pump to perform microdialysis at flow rates amenable to an intra-operative setting. We herein report on the lessons and insights obtained during our intra-operative HMW microdialysis trial, both in regard to methodological and analytical considerations.

METHODS

Intra-operative HMW microdialysis was performed during 15 clinically indicated glioma resections in fourteen patients, across three radiographically diverse regions in each patient. Microdialysates were analyzed via targeted and untargeted metabolomics via ultra-performance liquid chromatography tandem mass spectrometry.

RESULTS

Use of albumin and lactate-containing perfusates impacted subsets of metabolites evaluated via global metabolomics. Additionally, focal delivery of lactate via a lactate-containing perfusate, induced local metabolic changes, suggesting the potential for intra-operative pharmacodynamic studies via reverse microdialysis of candidate drugs. Multiple peri-operatively administered drugs, including levetiracetam, cefazolin, caffeine, mannitol and acetaminophen, could be detected from one microdialysate aliquot representing 10 min worth of intra-operative sampling. Moreover, clinical, radiographic, and methodological considerations for performing intra-operative microdialysis are discussed.

CONCLUSIONS

Intra-operative HMW microdialysis can feasibly be utilized to sample the live human CNS microenvironment, including both metabolites and drugs, within one surgery. Certain variables, such as perfusate type, must be considered during and after analysis. Trial registration NCT04047264.

Plasma exchange as a tool for removal of bevacizumab: Highlighting application for urgent surgery

Background

Bevacizumab is commonly used to manage cerebral edema associated with brain tumors. However, its long half-life poses challenges for patients requiring urgent surgery due to wound complications. We present a case of utilizing therapeutic plasma exchange (TPE) to remove bevacizumab in a patient with recurrent glioblastoma requiring urgent surgery.

Methods

A 58-year-old male with recurrent glioblastoma, IDH-wildtype, presented with clinical and radiographic concern for ventriculitis requiring urgent wound washout only 4 days after his last bevacizumab infusion. TPE was performed for 3 sessions after surgery using a centrifugation-based cell separator. Replacement fluids included normal serum albumin, normal saline, and fresh frozen plasma. Bevacizumab levels were quantified using an enzyme-linked immunoabsorbent assay before and after each TPE session.

Results

TPE effectively removed bevacizumab, enabling safe surgery without new complications. Plasma bevacizumab levels decreased from 1087.63 to 145.35 ng/mL (13.4% of original) by the end of the last TPE session. This decline is consistent with nearly 3 half-lives, which compares favorably to the expected timeline of natural decline given the 21-day half-life.

Conclusions

We report a complex clinical scenario of a patient requiring urgent wound washout 4 days after last bevacizumab infusion for CNS infection. Surgery was successfully performed without new complications with use of TPE to remove bevacizumab immediately following surgery. This case highlights the feasibility of this approach, which may be utilized effectively in patients requiring surgery after having recently received bevacizumab.

An untapped window of opportunity for glioma: targeting therapy-induced senescence prior to recurrence

High-grade gliomas are primary brain tumors that are incredibly refractory long-term to surgery and chemoradiation, with no proven durable salvage therapies for patients that have failed conventional treatments. Post-treatment, the latent glioma and its microenvironment are characterized by a senescent-like state of mitotic arrest and a senescence-associated secretory phenotype (SASP) induced by prior chemoradiation. Although senescence was once thought to be irreversible, recent evidence has demonstrated that cells may escape this state and re-enter the cell cycle, contributing to tumor recurrence. Moreover, senescent tumor cells could spur the growth of their non-senescent counterparts, thereby accelerating recurrence. In this review, we highlight emerging evidence supporting the use of senolytic agents to ablate latent, senescent-like cells that could contribute to tumor recurrence. We also discuss how senescent cell clearance can decrease the SASP within the tumor microenvironment thereby reducing tumor aggressiveness at recurrence. Finally, senolytics could improve the long-term sequelae of prior therapy on cognition and bone marrow function. We critically review the senolytic drugs currently under preclinical and clinical investigation and the potential challenges that may be associated with deploying senolytics against latent glioma. In conclusion, senescence in glioma and the microenvironment are critical and potential targets for delaying or preventing tumor recurrence and improving patient functional outcomes through senotherapeutics.

Glioma Metabolic Feedback In Situ: A First-In-Human Pharmacodynamic Trial of Difluoromethylornithine + AMXT-1501 Through High-Molecular Weight Microdialysis

BACKGROUND AND OBJECTIVES

No new drug has improved survival for glioblastoma since temozolomide in 2005, due in part to the relative inaccessibility of each patient's individualized tumor biology and its response to therapy. We have identified a conserved extracellular metabolic signature of enhancing high-grade gliomas enriched for guanidinoacetate (GAA). GAA is coproduced with ornithine, the precursor to protumorigenic polyamines through ornithine decarboxylase (ODC). AMXT-1501 is a polyamine transporter inhibitor that can overcome tumoral resistance to the ODC inhibitor, difluoromethylornithine (DFMO). We will use DFMO with or without AMXT-1501 to identify candidate pharmacodynamic biomarkers of polyamine depletion in patients with high-grade gliomas in situ . We aim to determine (1) how blocking polyamine production affects intratumoral extracellular guanidinoacetate abundance and (2) the impact of polyamine depletion on the global extracellular metabolome within live human gliomas in situ.

METHODS

DFMO, with or without AMXT-1501, will be administered postoperatively in 15 patients after clinically indicated subtotal resection for high-grade glioma. High-molecular weight microdialysis catheters implanted into residual tumor and adjacent brain will be used for postoperative monitoring of extracellular GAA and polyamines throughout therapeutic intervention from postoperative day (POD) 1 to POD5. Catheters will be removed on POD5 before discharge.

EXPECTED OUTCOMES

We anticipate that GAA will be elevated in tumor relative to adjacent brain although it will decrease within 24 hours of ODC inhibition with DFMO. If AMXT-1501 effectively increases the cytotoxic impact of ODC inhibition, we expect an increase in biomarkers of cytotoxicity including glutamate with DFMO + AMXT-1501 treatment when compared with DFMO alone.

DISCUSSION

Limited mechanistic feedback from individual patients' gliomas hampers clinical translation of novel therapies. This pilot Phase 0 study will provide in situ feedback during DFMO + AMXT-1501 treatment to determine how high-grade gliomas respond to polyamine depletion.

Blood-brain barrier disruption defines the extracellular metabolome of live human high-grade gliomas

The extracellular microenvironment modulates glioma behaviour. It remains unknown if blood-brain barrier disruption merely reflects or functionally supports glioma aggressiveness. We utilised intra-operative microdialysis to sample the extracellular metabolome of radiographically diverse regions of gliomas and evaluated the global extracellular metabolome via ultra-performance liquid chromatography tandem mass spectrometry. Among 162 named metabolites, guanidinoacetate (GAA) was 126.32x higher in enhancing tumour than in adjacent brain. 48 additional metabolites were 2.05-10.18x more abundant in enhancing tumour than brain. With exception of GAA, and 2-hydroxyglutarate in IDH-mutant gliomas, differences between non-enhancing tumour and brain microdialysate were modest and less consistent. The enhancing, but not the non-enhancing glioma metabolome, was significantly enriched for plasma-associated metabolites largely comprising amino acids and carnitines. Our findings suggest that metabolite diffusion through a disrupted blood-brain barrier may largely define the enhancing extracellular glioma metabolome. Future studies will determine how the altered extracellular metabolome impacts glioma behaviour.

Cerebrospinal fluid 2-hydroxyglutarate (2-HG) as a monitoring biomarker for IDH-mutant gliomas

D-2-hydroxyglutarate (D-2-HG) is a well-established oncometabolite of isocitrate dehydrogenase (IDH) mutant gliomas. While prior studies have demonstrated that D-2-HG is elevated in the cerebrospinal fluid (CSF) of patients with IDH-mutant gliomas ^1,2 , no study has determined if CSF D-2-HG can provide a plausible method to evaluate therapeutic response. We are obtaining CSF samples from consenting patients during their disease course via intra-operative collection and Ommaya reservoirs. D-2-HG and D/L-2-HG consistently decreased following tumor resection and throughout chemoradiation in patients monitored longitudinally. Our early experience with this strategy demonstrates the potential for intracranial CSF D-2-HG as a monitoring biomarker for IDH-mutant gliomas.

Effect of Extent of Resection on Survival of Patients with Glioblastoma, IDH-Wild-Type, WHO Grade 4 (WHO 2021): Systematic Review and Meta-Analysis

BACKGROUND

In light of the recently updated World Health Organization (WHO) 2021 central nervous system tumor classifications, the aim of the present study was to establish the effect of the resection extent on overall survival (OS) and progression-free survival (PFS) for patients who met the current diagnostic criteria for glioblastoma, isocitrate dehydrogenase (IDH)-wild-type (WT), WHO grade 4.

METHODS

A systematic literature search was performed using the following databases: PubMed, Web of Science, Cochrane Central Register of Controlled Trials, and Cochrane Database of Systematic Reviews and ClinicalTrials.gov to identify studies that had compared OS and PFS after gross total resection (GTR) versus subtotal resection (STR) or biopsy for glioblastoma IDH-WT.

RESULTS

We identified 1439 studies, of which 9 met the inclusion and/or exclusion criteria. Of the 2023 patients, 788 had undergone GTR. The meta-analysis showed a significant increase in the OS and PFS duration after GTR for glioblastoma IDH-WT, with a median OS of 20 months (95% confidence interval [CI], 17-25) after GTR versus 12 months (95% CI, 9-15) after STR (P < 0.0001). The median PFS was 11 months (95% CI, 9-12) after GTR versus 7 months (95% CI, 5-7) after STR (P < 0.0001). GTR was associated with a 51% reduction in the mortality risk (hazard ratio, 0.49; 95% CI, 0.36-0.65) and a 42% reduction in the progression risk (hazard ratio, 0.58; 95% CI, 0.39-0.88) compared with STR.

CONCLUSIONS

The results from our systematic review suggest that GTR is associated with improved OS and PFS compared with STR for glioblastoma, IDH-WT, WHO grade 4 (WHO 2021). However, our findings were limited by the various study designs and significant clinical and methodologic heterogeneity among the studies.

A 42-Year-Old Man with a Seizure

A 42-Year-Old Man with a SeizureA 42-year-old man with acute myeloid leukemia presented for evaluation after an episode of convulsions. Six weeks before this event, he had a cough productive of yellow sputum. Two weeks later, he started having a headache and fevers. How do you approach the evaluation, and what is the diagnosis?

P21 Overexpression Promotes Cell Death and Induces Senescence in Human Glioblastoma

High-grade gliomas are the most common and aggressive adult primary brain tumors with a median survival of only 12-15 months. Current standard therapy consists of maximal safe surgical resection followed by DNA-damaging agents, such as irradiation and chemotherapy that can delay but not prevent inevitable recurrence. Some have interpreted glioma recurrence as evidence of glioma stem cells which persist in a relatively quiescent state after irradiation and chemotherapy, before the ultimate cell cycle re-entry and glioma recurrence. Conversely, latent cancer cells with a therapy-induced senescent phenotype have been shown to escape senescence, giving rise to more aggressive stem-like tumor cells than those present in the original tumor. Therefore, approaches are needed to either eliminate or keep these glioma initiating cells in a senescent state for a longer time to prolong survival. In our current study, we demonstrate that the radiation-induced cell cycle inhibitor P21 can provide a powerful route to induce cell death in short-term explants of PDXs derived from three molecularly diverse human gliomas. Additionally, cells not killed by P21 overexpression were maintained in a stable senescent state for longer than control cells. Collectively, these data suggest that P21 activation may provide an attractive therapeutic target to improve therapeutic outcomes.

Development of an integrated microperfusion-EEG electrode for unbiased multimodal sampling of brain interstitial fluid and concurrent neural activity

Objective. To modify off-the-shelf components to build a device for collecting electroencephalography (EEG) from macroelectrodes surrounded by large fluid access ports sampled by an integrated microperfusion system in order to establish a method for sampling brain interstitial fluid (ISF) at the site of stimulation or seizure activity with no bias for molecular size.Approach. Twenty-four 560µm diameter holes were ablated through the sheath surrounding one platinum-iridium macroelectrode of a standard Spencer depth electrode using a femtosecond UV laser. A syringe pump was converted to push-pull configuration and connected to the fluidics catheter of a commercially available microdialysis system. The fluidics were inserted into the lumen of the modified Spencer electrode with the microdialysis membrane removed, converting the system to open flow microperfusion. Electrical performance and analyte recovery were measured and parameters were systematically altered to improve performance. An optimized device was tested in the pig brain and unbiased quantitative mass spectrometry was used to characterize the perfusate collected from the peri-electrode brain in response to stimulation.Main results. Optimized parameters resulted in >70% recovery of 70 kDa dextran from a tissue analog. The optimized device was implanted in the cortex of a pig and perfusate was collected during four 60 min epochs. Following a baseline epoch, the macroelectrode surrounded by microperfusion ports was stimulated at 2 Hz (0.7 mA, 200µs pulse width). Following a post-stimulation epoch, the cortex near the electrode was stimulated with benzylpenicillin to induce epileptiform activity. Proteomic analysis of the perfusates revealed a unique inflammatory signature induced by electrical stimulation. This signature was not detected in bulk tissue ISF.Significance. A modified dual-sensing electrode that permits coincident detection of EEG and ISF at the site of epileptiform neural activity may reveal novel pathogenic mechanisms and therapeutic targets that are otherwise undetectable at the bulk tissue level.

P300 promotes tumor recurrence by regulating radiation-induced conversion of glioma stem cells to vascular-like cells

Glioma stem cells (GSC) exhibit plasticity in response to environmental and therapeutic stress leading to tumor recurrence, but the underlying mechanisms remain largely unknown. Here, we employ single-cell and whole transcriptomic analyses to uncover that radiation induces a dynamic shift in functional states of glioma cells allowing for acquisition of vascular endothelial-like and pericyte-like cell phenotypes. These vascular-like cells provide trophic support to promote proliferation of tumor cells, and their selective depletion results in reduced tumor growth post-treatment in vivo. Mechanistically, the acquisition of vascular-like phenotype is driven by increased chromatin accessibility and H3K27 acetylation in specific vascular genes allowing for their increased expression post-treatment. Blocking P300 histone acetyltransferase activity reverses the epigenetic changes induced by radiation and inhibits the adaptive conversion of GSC into vascular-like cells and tumor growth. Our findings highlight a role for P300 in radiation-induced stress response, suggesting a therapeutic approach to prevent glioma recurrence.

Outcomes and Principles of Patient Selection for Laser Interstitial Thermal Therapy for Metastatic Brain Tumor Management: A Multisite Institutional Case Series

BACKGROUND

Laser interstitial thermal therapy (LITT) is an emerging treatment modality for both primary brain tumors and metastases. We report initial outcomes after LITT for metastatic brain tumors across 3 sites at our institution and discuss potential strategies for optimal patient selection and outcomes.

METHODS

International Classification of Diseases, Ninth Revision and Tenth Revision codes were used to identify patients with malignant brain tumors treated via LITT across all 3 Mayo Clinic sites with at least 6 months follow-up. Local control was based on radiologic and clinical evidence. Overall survival was measured from time of receiving LITT until death or end of the study period.

RESULTS

Twenty-three patients were treated for progression of a single (n = 21) or multiple (n = 2) previously radiated metastatic lesions and/or radiation necrosis. Median age was 56 years (interquartile range, 47-66.5 years). LITT achieved local control of the lesion in most patients with metastatic tumors or radiation necrosis (n = 18; 81.8%) for the duration of follow-up. One patient did not have local control data available. Thirteen (56.5%) patients remained alive at the end of the study period. No other patients died of their treated disease during the study period; 5 of 10 deaths were attributable to central nervous system progression outside the treated lesion. Although median survival for this cohort has not yet been reached, the current median survival is 16 months (interquartile range, 12-48.5 months) after LITT for metastatic/radiation necrosis lesions.

CONCLUSIONS

LITT was associated with sustained local control in 81.8% of patients treated for radiographic progression of metastatic central nervous system disease.

Presentation, imaging, patterns of care, growth, and outcome in sporadic and von Hippel-Lindau-associated central nervous system hemangioblastomas

OBJECT

Hemangioblastoma is a relatively rare neoplasm occurring mostly in the cerebellum that may arise sporadically or in the context of von Hippel-Lindau (VHL) syndrome. Presentation, imaging, natural history, surgical patterns of care, and outcomes are incompletely defined for this uncommon lesion. We reviewed our large institutional series to help clarify these issues.

METHODS

Retrospective analysis of consecutive, neurosurgically managed CNS hemangioblastomas at Mayo Clinic, 1988-2018.

RESULTS

Two hundred and eighty five hemangioblastomas were treated in 184 unique patients (115 sporadic, 69 VHL). Compared to sporadic patients, VHL patients were younger (36.7 vs 51.7 years; p < 0.0001), were treated while asymptomatic more commonly (47.3 vs 4.2%; p < 0.0001), had smaller lesions (6.6 vs 13.9 mL; p < 0.0001), and harbored lesions with associated cysts less frequently (51.0 vs 75.0%; p = 0.0002). Macrocystic tumor architecture was associated with larger lesion size and greater symptom severity. Solid lesions later formed cysts at a median 130 months. Growth in both total volume and solid component accelerated after cyst formation (10.6 and 6.0 times median rate prior to cyst emergence). VHL patients died at a younger age (47.9 vs 74.5, p = 0.0017) and were more likely to die of direct disease sequelae. Though treatment-free survival time was significantly longer in sporadic cases, a substantial fraction (> 40%) developed tumor recurrence/progression requiring additional treatment.

CONCLUSIONS

Hemangioblastoma presentation varies with etiology and clinical course is more complicated in VHL cases. Nodular lesions often develop cysts over time which is associated with accelerated tumor growth. Sporadic cases have a previously unappreciated but substantial risk of late recurrence/progression requiring treatment.

Selective Vulnerability of Senescent Glioblastoma Cells to BCL-XL Inhibition

Glioblastoma (GBM) is a rapidly fatal malignancy typically treated with radiation and temozolomide (TMZ), an alkylating chemotherapeutic. These cytotoxic therapies cause oxidative stress and DNA damage, yielding a senescent-like state of replicative arrest in surviving tumor cells. Unfortunately, recurrence is inevitable and may be driven by surviving tumor cells eventually escaping senescence. A growing number of so-called "senolytic" drugs have been recently identified that are defined by their ability to selectively eliminate senescent cells. A growing inventory of senolytic drugs is under consideration for several diseases associated with aging, inflammation, DNA damage, as well as cancer. Ablation of senescent tumor cells after radiation and chemotherapy could help mitigate recurrence by decreasing the burden of residual tumor cells at risk of recurrence. This strategy has not been previously explored for GBM. We evaluated a panel of 10 previously described senolytic drugs to determine whether any could exhibit selective activity against human GBM persisting after exposure to radiation or TMZ. Three of the 10 drugs have known activity against BCL-XL and preferentially induced apoptosis in radiated or TMZ-treated glioma. This senolytic activity was observed in 12 of 12 human GBM cell lines. Efficacy could not be replicated with BCL-2 inhibition or senolytic agents acting against other putative senolytic targets. Knockdown of BCL-XL decreased survival of radiated GBM cells, whereas knockdown of BCL-2 or BCL-W yielded no senolytic effect.

IMPLICATIONS

These findings imply that molecularly heterogeneous GBM lines share selective senescence-induced BCL-XL dependency increase the significance and translational relevance of the senolytic therapy for latent glioma.

PATH-16. Noninvasive diagnosis of gliomas through CSF cfDNA sequencing in pediatric and adolescent and young adult (AYA) patients

PURPOSE: A subset of pediatric, adolescent and young adult (AYA) gliomas are located in the brainstem, eloquent locations, or present with diffuse/leptomeningeal disease, and are associated with high risk and low yield of biopsy. At the same time, accurate molecular diagnosis is necessary to direct optimal therapy. In such cases, analysis of cell free DNA (cfDNA) form cerebral spinal fluid (CSF) may represent a diagnostic alternative to biopsy. METHODS: We investigated the utility of CSF cfDNA sequencing through a stepwise approach, using clinically validated, targeted molecular assays. Testing was performed using a broad hybrid capture next generation sequencing assay (MSK-IMPACT) and subsequent targeted digital droplet PCR in a subset of cases. RESULTS: We analyzed 17 CSF samples from 17 pediatric (n=6) and AYA (n=11) glioma patients with primary or recurrent disease. Thirteen had tumors located within the brainstem, and four had leptomeningeal involvement. Somatic alterations were detected in 12/17 samples (71%). In 3/4 patients with leptomeningeal involvement, cfDNA testing revealed a BRAF fusion consistent with the diagnosis of diffuse leptomeningeal glioneuronal tumor (DLGNT). Among the 13 patients with brainstem involvement, four had somatic H3 K27M mutations, three had IDH mutations, and one had TP53 and ATRX mutations; five patients had no detectable mutations. CONCLUSION: In our analysis, we found that established glioma hotspot mutations were able to be detected within the CSF. We propose that in patients for whom tissue biopsy is high risk, not feasible, or tissue was nondiagnostic, CSF cfDNA sequencing has a substantial diagnostic yield and should be considered as a valuable novel diagnostic tool. Ongoing research is aiming to further increase the sensitivity of cfDNA testing, especially in patients with very low levels of CSF cfDNA.

MDACT: A New Principle of Adjunctive Cancer Treatment Using Combinations of Multiple Repurposed Drugs, with an Example Regimen

In part one of this two-part paper, we present eight principles that we believe must be considered for more effective treatment of the currently incurable cancers. These are addressed by multidrug adjunctive cancer treatment (MDACT), which uses multiple repurposed non-oncology drugs, not primarily to kill malignant cells, but rather to reduce the malignant cells' growth drives. Previous multidrug regimens have used MDACT principles, e.g., the CUSP9v3 glioblastoma treatment. MDACT is an amalgam of (1) the principle that to be effective in stopping a chain of events leading to an undesired outcome, one must break more than one link; (2) the principle of Palmer et al. of achieving fractional cancer cell killing via multiple drugs with independent mechanisms of action; (3) the principle of shaping versus decisive operations, both being required for successful cancer treatment; (4) an idea adapted from Chow et al., of using multiple cytotoxic medicines at low doses; (5) the idea behind CUSP9v3, using many non-oncology CNS-penetrant drugs from general medical practice, repurposed to block tumor survival paths; (6) the concept from chess that every move creates weaknesses and strengths; (7) the principle of mass-by adding force to a given effort, the chances of achieving the goal increase; and (8) the principle of blocking parallel signaling pathways. Part two gives an example MDACT regimen, gMDACT, which uses six repurposed drugs-celecoxib, dapsone, disulfiram, itraconazole, pyrimethamine, and telmisartan-to interfere with growth-driving elements common to cholangiocarcinoma, colon adenocarcinoma, glioblastoma, and non-small-cell lung cancer. gMDACT is another example of-not a replacement for-previous multidrug regimens already in clinical use, such as CUSP9v3. MDACT regimens are designed as adjuvants to be used with cytotoxic drugs.

Survival and Associated Predictors for Patients with Pineoblastoma or Pineal Parenchymal Tumor of Intermediate Differentiation Older than 3 years: Insights from the National Cancer Database

Background

The management of pineal parenchymal tumors remains controversial.

Methods

The 2004-2017 National Cancer Database was queried for cases (age >3 years) with histologically confirmed pineal parenchymal tumors of intermediate differentiation (PPTID, n = 90) or pineoblastoma (n = 106).

Results

Within the PPTID group, median age was 41 years; 49% were males. Five- and 10-year survival were 83% and 78%, respectively. Adjuvant radiation and chemotherapy were administered in 64% and 17% patients, respectively. The effect of radiation with or without chemotherapy (HR 1.15, P = .81, and HR 1.31, P = .72, respectively), and extent of resection (HR = 1.07, P = .93) was not significant. Within the pineoblastoma group, median age was 25 years; 51% were males. Five- and 10-year survival were 66% and 42%, respectively. Adjuvant radiation and chemotherapy were administered in 72% and 51%, respectively. In multivariable analysis, patients with pineoblastoma who received both radiation and chemotherapy (n = 39) had significantly lower hazard of death (HR 0.35, 95% CI 0.14-0.85, P = .02) compared to those who received radiation alone (n = 20) or no adjuvant treatment (n = 19). Finally, females in the pineoblastoma group were found to have a lower hazard of death compared to males (HR 0.24, 95% CI 0.10-0.58, P = .001); this comparison trended toward statistical significance in the PPTID subgroup (HR 0.40, 95% CI 0.14-1.08, P = .07).

Conclusions

Survival rates were higher in patients with PPTID vs patients with pineoblastoma. Adjuvant chemoradiation was associated with improved survival in pineoblastoma and females had lower hazards of death. Further research should identify specific patient profiles and molecular subgroups more likely to benefit from multimodality therapy.

Advanced MRI Protocols to Discriminate Glioma From Treatment Effects: State of the Art and Future Directions

In the follow-up treatment of high-grade gliomas (HGGs), differentiating true tumor progression from treatment-related effects, such as pseudoprogression and radiation necrosis, presents an ongoing clinical challenge. Conventional MRI with and without intravenous contrast serves as the clinical benchmark for the posttreatment surveillance imaging of HGG. However, many advanced imaging techniques have shown promise in helping better delineate the findings in indeterminate scenarios, as posttreatment effects can often mimic true tumor progression on conventional imaging. These challenges are further confounded by the histologic admixture that can commonly occur between tumor growth and treatment-related effects within the posttreatment bed. This review discusses the current practices in the surveillance imaging of HGG and the role of advanced imaging techniques, including perfusion MRI and metabolic MRI.

A clinical primer for the glymphatic system

The complex and dynamic system of fluid flow through the perivascular and interstitial spaces of the central nervous system has new-found implications for neurological diseases. Cerebrospinal fluid movement throughout the CNS parenchyma is more dynamic than could be explained via passive diffusion mechanisms alone. Indeed, a semi-structured glial-lymphatic (glymphatic) system of astrocyte-supported extracellular perivascular channels serves to directionally channel extracellular fluid, clearing metabolites and peptides to optimize neurologic function. Clinical studies of the glymphatic network has to date proven challenging, with most data gleaned from rodent models and post-mortem investigations. However, increasing evidence suggests that disordered glymphatic function contributes to the pathophysiology of CNS aging, neurodegenerative disease, and CNS injuries, as well as normal pressure hydrocephalus. Unlocking such pathophysiology could provide important avenues toward novel therapeutics. We here provide a multidisciplinary overview of glymphatics and critically review accumulating evidence regarding its structure, function, and hypothesized relevance to neurological disease. We highlight emerging technologies of relevance to the longitudinal evaluation of glymphatic function in health and disease. Finally, we discuss the translational opportunities and challenges of studying glymphatic science.

Methods for intratumoral microdialysis probe targeting and validation in murine brain tumor models

BACKGROUND

Microdialysis is a well validated sampling technique that can be used for pharmacokinetic studies of oncological drugs targeting the central nervous system. This technique has also been applied to evaluate tumor metabolism and identify pharmacodynamic biomarkers of drug activity. Despite the potential utility of microdialysis for therapeutic discovery, variability in tumor size and location hamper routine use of microdialysis as a preclinical tool. Quantitative validation of microdialysis membrane location relative to radiographically evident tumor regions could facilitate rigorous preclinical studies. However, a widely accessible standardized workflow for preclinical catheter placement and validation is needed.

NEW METHOD

We provide methods for a workflow to yield tailored placement of microdialysis probes within a murine intracranial tumor and illustrate in an IDH1-mutant patient-derived xenograft (PDX) model. This detailed workflow uses a freely available on-line tool built within 3D-slicer freeware to target microdialysis probe placement within the tumor core and validate probe placement fully within the tumor.

RESULTS

We illustrate use of this workflow to validate microdialysis probe location relative to implanted IDH1-mutant PDXs, using the microdialysis probes to quantify levels of extracellular onco-metabolite D-2 hydroxyglutarate.

COMPARISON WITH EXISTING METHODS

Previous methods have used 3D slicer to reliably measure tumor volumes. Prior microdialysis studies have targeted expected tumor locations without validation.

CONCLUSIONS

The new method offers a streamlined and freely available workflow in 3D slicer to optimize and validate microdialysis probe placement within a murine brain tumor.

The role of single-fraction stereotactic radiosurgery for atypical meningiomas (WHO grade II): treatment results based on a 25-year experience

PURPOSE

To clarify the role of stereotactic radiosurgery (SRS) for atypical meningiomas (AM).

METHODS

A retrospective analysis of 68 patients with AM having SRS from 1995 until 2019.

RESULTS

Nineteen patients (28%) had undergone prior external beam radiation therapy (EBRT) (median dose, 54 Gy). The median follow-up period was 52 months. Eighteen (26%), 17 (25%), and 33 (49%) patients received SRS as an upfront adjuvant (≤ 6 months), early salvage (7-18 months), or late salvage treatment (> 18 months), respectively. The 3-, 5-, and 10-year progression-free survivals (PFSs) were 52%, 35%, and 25%, respectively. The 3-, 5-, and 10-year disease-specific survivals were 85%, 78%, and 61%, respectively. Adverse radiation events (AREs) were observed in 12 patients (18%), with increased or new seizures being the most frequent complication (n = 7). Prior EBRT was associated with reduced PFS (HR 5.92, P < 0.01), reduced DSS (HR 5.84, P < 0.01), and an increased risk of ARE (HR 3.31, P = 0.04). Timing of SRS was correlated with reduced PFS for patients having early salvage treatment compared to upfront adjuvant (HR 3.17, P = 0.01) or late salvage treatment (HR 4.39, P < 0.01).

CONCLUSION

PFS for patients with residual/recurrent AM remains poor despite SRS. Prior EBRT was associated with worse tumor control, higher tumor-related mortality, and an increased risk of ARE. Further study on the timing of SRS is needed to determine if upfront adjunctive SRS improves tumor control compared to salvage SRS.

Elimination of Radiation-Induced Senescence in the Brain Tumor Microenvironment Attenuates Glioblastoma Recurrence

Glioblastomas (GBM) are routinely treated with ionizing radiation (IR) but inevitably recur and develop therapy resistance. During treatment, the tissue surrounding tumors is also irradiated. IR potently induces senescence, and senescent stromal cells can promote the growth of neighboring tumor cells by secreting factors that create a senescence-associated secretory phenotype (SASP). Here, we carried out transcriptomic and tumorigenicity analyses in irradiated mouse brains to elucidate how radiotherapy-induced senescence of non-neoplastic brain cells promotes tumor growth. Following cranial irradiation, widespread senescence in the brain occurred, with the astrocytic population being particularly susceptible. Irradiated brains showed an altered transcriptomic profile characterized by upregulation of CDKN1A (p21), a key enforcer of senescence, and several SASP factors, including HGF, the ligand of the receptor tyrosine kinase (RTK) Met. Preirradiation of mouse brains increased Met-driven growth and invasiveness of orthotopically implanted glioma cells. Importantly, irradiated p21^-/- mouse brains did not exhibit senescence and consequently failed to promote tumor growth. Senescent astrocytes secreted HGF to activate Met in glioma cells and to promote their migration and invasion in vitro, which could be blocked by HGF-neutralizing antibodies or the Met inhibitor crizotinib. Crizotinib also slowed the growth of glioma cells implanted in preirradiated brains. Treatment with the senolytic drug ABT-263 (navitoclax) selectively killed senescent astrocytes in vivo, significantly attenuating growth of glioma cells implanted in preirradiated brains. These results indicate that SASP factors in the irradiated tumor microenvironment drive GBM growth via RTK activation, underscoring the potential utility of adjuvant senolytic therapy for preventing GBM recurrence after radiotherapy. SIGNIFICANCE: This study uncovers mechanisms by which radiotherapy can promote GBM recurrence by inducing senescence in non-neoplastic brain cells, suggesting that senolytic therapy can blunt recurrent GBM growth and aggressiveness.

Clinical utility of brain biopsy for presumed CNS relapse of systemic lymphoma

OBJECTIVE

The objective of this study was to determine the frequency with which brain biopsy for presumed CNS relapse of systemic hematological malignancies yields new, actionable diagnostic information. Hematological malignancies represent a disparate group of genetic and histopathological disorders. Proclivity for brain involvement is dependent on the unique entity and may occur synchronously or metasynchronously with the systemic lesion. Diffuse large B-cell lymphomas (DLBCLs) have a high propensity for brain involvement. Patients in remission from systemic DLBCL may present with a lesion suspicious for brain relapse. These patients often undergo brain biopsy. The authors' a priori hypothesis was that brain biopsy in patients with a history of systemic DLBCL and a new brain MRI lesion would have lower diagnostic utility compared with patients with non-DLBCL systemic malignancies.

METHODS

The authors performed a retrospective review of patients who underwent brain biopsy between 2000 and 2019. Inclusion criteria were patients ≥ 18 years of age with a prior systemic hematological malignancy in remission presenting with a new brain MRI lesion concerning for CNS relapse. Patients with a history of any CNS neoplasms, demyelinating disorders, or active systemic disease were excluded. The main outcome was the proportion of patients with a distinct histopathological brain diagnosis compared with the systemic malignancy. The authors secondarily assessed overall survival, procedure-related morbidity, and 30-day mortality.

RESULTS

Sixty patients met inclusion criteria (40 males and 20 females); the median age at brain biopsy was 67 years (range 23-88 years). The median follow-up was 8.5 months (range 0.1-231 months). Thirty-nine (65.0%) patients had DLBCL and 21 (35%) had non-DLBCL malignancies. Thirty-five of 36 (97.2%) patients with prior systemic DLBCL and a diagnostic biopsy had histopathological confirmation of the original systemic disease versus 0 of 21 patients with non-DLBCL systemic malignancies (p < 0.001). Morbidity and 30-day mortality were 8.3% and 10.0%, respectively; 2 of 6 30-day mortalities were directly attributable to the biopsy. The median overall survival following brain biopsy was 10.8 months.

CONCLUSIONS

Patients with a history of systemic DLBCL and presumed CNS relapse gained minimal clinical benefit from brain biopsy but were at high risk of morbidity and mortality. In patients with a history of non-DLBCL systemic malignancies, brain biopsy remained critical given the high likelihood for discovery of distinct diagnostic entities. It was determined that patients with a prior systemic DLBCL and presumed brain relapse should likely receive empirical therapy obviating treatment delay and the risks of brain biopsy.

Remyelination therapies for multiple sclerosis: optimizing translation from animal models into clinical trials

Introduction: Multiple sclerosis (MS) is the most common inflammatory disease of the central nervous system (CNS). Demyelination, the main pathology in MS, contributes to clinical symptoms and long-term neurological deficits if left untreated. Remyelination, the natural repair of damaged myelin by cells of the oligodendrocyte lineage, occurs in MS, but eventually fails in most patients as they age. Encouraging timely remyelination can restore axon conduction and minimize deficits.Areas covered: We discuss and correlate human MS pathology with animal models, propose methods to deplete resident oligodendrocyte progenitor cells (OPCs) to determine whether mature oligodendrocytes support remyelination, and review remyelinating agents, mechanisms of action, and available clinical trial data.Expert opinion: The heterogeneity of human MS may limit successful translation of many candidate remyelinating agents; some patients lack the biological targets necessary to leverage current approaches. Development of therapeutics for remyelination has concentrated almost exclusively on mobilization of innate OPCs. However, mature oligodendrocytes appear an important contributor to remyelination in humans. Limiting the contribution of OPC mediated repair in models of MS would allow the evaluation of remyelination-promoting agents on mature oligodendrocytes. Among remyelinating reagents reviewed, only rHIgM22 targets both OPCs and mature oligodendrocytes.

Regenerative medicine for neurological diseases-will regenerative neurosurgery deliver?

Regenerative medicine aspires to transform the future practice of medicine by providing curative, rather than palliative, treatments. Healing the central nervous system (CNS) remains among regenerative medicine's most highly prized but formidable challenges. "Regenerative neurosurgery" provides access to the CNS or its surrounding structures to preserve or restore neurological function. Pioneering efforts over the past three decades have introduced cells, neurotrophins, and genes with putative regenerative capacity into the CNS to combat neurodegenerative, ischemic, and traumatic diseases. In this review we critically evaluate the rationale, paradigms, and translational progress of regenerative neurosurgery, harnessing access to the CNS to protect, rejuvenate, or replace cell types otherwise irreversibly compromised by neurological disease. We discuss the evidence surrounding fetal, somatic, and pluripotent stem cell derived implants to replace endogenous neuronal and glial cell types and provide trophic support. Neurotrophin based strategies via infusions and gene therapy highlight the motivation to preserve neuronal circuits, the complex fidelity of which cannot be readily recreated. We specifically highlight ongoing translational efforts in Parkinson's disease, amyotrophic lateral sclerosis, stroke, and spinal cord injury, using these to illustrate the principles, challenges, and opportunities of regenerative neurosurgery. Risks of associated procedures and novel neurosurgical trials are discussed, together with the ethical challenges they pose. After decades of efforts to develop and refine necessary tools and methodologies, regenerative neurosurgery is well positioned to advance treatments for refractory neurological diseases. Strategic multidisciplinary efforts will be critical to harness complementary technologies and maximize mechanistic feedback, accelerating iterative progress toward cures for neurological diseases.

Laser Interstitial Thermal Therapy for Recurrent Glioblastoma: Pooled Analyses of Available Literature

OBJECTIVE/BACKGROUND

The efficacy of laser interstitial thermal therapy (LITT) in recurrent glioblastoma (rGBM) is unknown. The goal of this study was to conduct a systematic review and pooled analysis of the literature for outcomes on patients with rGBM undergoing LITT.

METHODS

A literature search was performed to retrieve all studies investigating overall survival, postprocedure survival, and progression-free survival outcomes of patients with rGBM undergoing LITT. Statistics were pooled together by meta-analysis of mean using a weighted random-effects or fixed-effect model.

RESULTS

Eleven studies were included in the final cohort, representing a total of 134 patients with rGBM. The pooled mean age of the cohort at the time of recurrence was 56.7 ± 4.56 years; 41% of the cohort were female. For delivery of LITT, 2 studies used neodymium-yttrium aluminum-garnet laser (Nd:YAG laser), 3 studies used the Visualase system, 5 studies used the NeuroBlate system, and 1 study used both the NeuroBlate and the Visualase system. A total of 8 studies with 107 patients had available data for overall median survival. The pooled overall survival was found to be 18.6 months (95% confidence interval [CI] 16.2-21.1). A total of 6 studies with 93 patients had available data for post-LITT survival. The pooled post-LITT survival was found to be 10.1 months (95% CI 8.8-11.6). A total of 8 studies with 119 patients had available data for progression-free survival. Pooled progression free survival was found to be 6 months (95% CI 5.3-6.7).

CONCLUSIONS

LITT is a novel minimally invasive procedure which, when used with optimal adjuvant therapy, may confer survival benefit for patients with rGBM.

Consensus recommendations for a standardized brain tumor imaging protocol for clinical trials in brain metastases

A recent meeting was held on March 22, 2019, among the FDA, clinical scientists, pharmaceutical and biotech companies, clinical trials cooperative groups, and patient advocacy groups to discuss challenges and potential solutions for increasing development of therapeutics for central nervous system metastases. A key issue identified at this meeting was the need for consistent tumor measurement for reliable tumor response assessment, including the first step of standardized image acquisition with an MRI protocol that could be implemented in multicenter studies aimed at testing new therapeutics. This document builds upon previous consensus recommendations for a standardized brain tumor imaging protocol (BTIP) in high-grade gliomas and defines a protocol for brain metastases (BTIP-BM) that addresses unique challenges associated with assessment of CNS metastases. The "minimum standard" recommended pulse sequences include: (i) parameter matched pre- and post-contrast inversion recovery (IR)-prepared, isotropic 3D T1-weighted gradient echo (IR-GRE); (ii) axial 2D T2-weighted turbo spin echo acquired after injection of gadolinium-based contrast agent and before post-contrast 3D T1-weighted images; (iii) axial 2D or 3D T2-weighted fluid attenuated inversion recovery; (iv) axial 2D, 3-directional diffusion-weighted images; and (v) post-contrast 2D T1-weighted spin echo images for increased lesion conspicuity. Recommended sequence parameters are provided for both 1.5T and 3T MR systems. An "ideal" protocol is also provided, which replaces IR-GRE with 3D TSE T1-weighted imaging pre- and post-gadolinium, and is best performed at 3T, for which dynamic susceptibility contrast perfusion is included. Recommended perfusion parameters are given.

Adult diffuse glioma GWAS by molecular subtype identifies variants in D2HGDH and FAM20C

BACKGROUND

Twenty-five germline variants are associated with adult diffuse glioma, and some of these variants have been shown to be associated with particular subtypes of glioma. We hypothesized that additional germline variants could be identified if a genome-wide association study (GWAS) were performed by molecular subtype.

METHODS

A total of 1320 glioma cases and 1889 controls were used in the discovery set and 799 glioma cases and 808 controls in the validation set. Glioma cases were classified into molecular subtypes based on combinations of isocitrate dehydrogenase (IDH) mutation, telomerase reverse transcriptase (TERT) promoter mutation, and 1p/19q codeletion. Logistic regression was applied to the discovery and validation sets to test for associations of variants with each of the subtypes. A meta-analysis was subsequently performed using a genome-wide P-value threshold of 5 × 10-8.

RESULTS

Nine variants in or near D-2-hydroxyglutarate dehydrogenase (D2HGDH) on chromosome 2 were genome-wide significant in IDH-mutated glioma (most significant was rs5839764, meta P = 2.82 × 10-10). Further stratifying by 1p/19q codeletion status, one variant in D2HGDH was genome-wide significant in IDH-mutated non-codeleted glioma (rs1106639, meta P = 4.96 × 10-8). Further stratifying by TERT mutation, one variant near FAM20C (family with sequence similarity 20, member C) on chromosome 7 was genome-wide significant in gliomas that have IDH mutation, TERT mutation, and 1p/19q codeletion (rs111976262, meta P = 9.56 × 10-9). Thirty-six variants in or near GMEB2 on chromosome 20 near regulator of telomere elongation helicase 1 (RTEL1) were genome-wide significant in IDH wild-type glioma (most significant was rs4809313, meta P = 2.60 × 10-10).

CONCLUSIONS

Performing a GWAS by molecular subtype identified 2 new regions and a candidate independent region near RTEL1, which were associated with specific glioma molecular subtypes.

Short review of SEC, a potential dexamethasone-sparing regimen for glioblastoma: Spironolactone, ecallantide, clotrimazole

This paper presents a short review of data supporting a dexamethasone sparing regimen, SEC, to reduce glioblastoma related brain edema. The conclusion of the reviewed data is that the rationale and risk/benefit ratio favors a pilot study to determine if the three drug regimen of SEC can reduce need for corticosteroid use during the course of glioblastoma. Details of how selected pathophysiological aspects of brain edema occurring during the course of glioblastoma and its treatment intersect with the established action of the three old drugs of SEC indicate that they can be repurposed to reduce that edema. Current first-line treatment of this edema is dexamethasone or related corticosteroids. There are multiple negative prognostic implications of both the edema itself and of dexamethasone, prime among them shortened survival, making a dexamethasone sparing regimen highly desirable. SEC uses spironolactone, an antihypertensive potassium-sparing diuretic acting by mineralocorticoid receptor inhibition, ecallantide acting to inhibit kallikrein activation marketed to treat hereditary angioedema, and clotrimazole, an old antifungal drug that inhibits intermediate conductance Ca++ activated K+ channel (KCa3.1). These three old drugs are well known to most clinicians, have a well-tolerated safety history, and have a robust preclinical database showing their potential to reduce the specific edema of glioblastoma. Additionally, these three drugs were chosen by virtue of each having preclinical evidence of glioblastoma growth and/or migration inhibition independent of their edema reduction action. A clinical study of SEC is being planned.

TAMI-13. IMPORTANCE OF CD38 INHIBITION IN PRE-RECURRENT GLIOBLASTOMA

Glioblastoma multiforme (GBM) is the most aggressive CNS neoplasm with a mere 15 month progression-free survival following current standards-of-care. Furthermore, conventional therapies have been effective, in part, by inducing a senescent-like phenotype in at least a proportion of glioma, as well as within the tumor-adjacent, healthy brain cells. Through an N-glyco-capture large-scale screening method, we were able to identify 25 genes exclusively overexpressed on glioma cell surfaces. Of those 25 targets, CD38 was an attractive target due to pre-existing FDA approved therapeutics. Recent studies have shown, however, that senescent cells, such as those induced via chemo- and radiotherapies, secrete a pro-inflammatory array of cytokines, known collectively as senescence associated secretory phenotype (SASP), that are capable of increasing CD38 expression in monocytes. CD38 functions as an ectoenzyme to convert extracellular NAD+ to nicotinamide (required for glioma cell salvage pathway NAD+ synthesis) and ADPR/cADPR (a cellular proliferation signal). To examine the effects of radiation on human glioma tissue, we performed reverse cyclase assays (RCA) on paired primary and recurrent human glioma tissue samples and found an increase in CD38 activity in post-irradiated tissues (recurrent glioma) compared to pre-irradiated (primary glioma). Through proliferation assays, we also found an increase in glioma cell growth following treatment with cADPR compared to untreated. Our results demonstrate that CD38 activity is tumorgenic, and furthermore that conventional chemo- and radiotherapies increase this CD38 activity. This indicates that treating CD38 with previously FDA approved therapeutics may provide hope for increasing progression free survival in our GBM patient population, and moreover emphasize the importance of leveraging novel large scale screening methods for identifying additional opportunities for treatment.

BIOM-11. ENZYMATIC ASSAY USED TO MONITOR CHANGES IN ONCO-METABOLITE, D2HG, IN RESPONSE TO THERAPY

INTRODUCTION

Gliomas are the most common and deadly adult brain cancers with a median survival time of less than 18 months. Many therapeutics have failed translating into effective therapies due to incomplete understanding of the disease and heterogeneity of tumors between patients. There is a need for methods that allow for continual access and analysis of glioma biomarkers. We sought to establish a reliable method for quantifying the onco-metabolite, D2HG. After optimizing this method, we used microdialysate and microperfusate to test our hypothesis that analysis of D2HG in response to therapy can indicate therapeutic efficacy sooner than current methods permit.

METHODS

Microdialysate and microperfusate were collected from the tumor centers and lateral ventricles of athymic nude mice implanted with IDH1 mutant PDX line GBM196. We performed microdialysis and microperfusion on consecutive days to determine baseline D2HG concentration. Following a five day period of TMZ treatment, we collected another round of microdialysis and microperfusion one week after treatment and again two weeks after treatment. We then used our optimized D2HG enzymatic assay to quantify the changes in D2HG in response to therapy.

RESULTS

Using our enzymatic D2HG assay, we were able to quantify D2HG as low as 30nM (30fmol/uL). We found a ~20% decrease in D2HG concentration in the tumor center and right lateral ventricle after 1 week of TMZ treatment (n=2), and ~36% decrease after 2 weeks of TMZ treatment (n=2).

CONCLUSION

Using a D2HG quantification assay to monitor changes in concentration of D2HG in microdialysate/microperfusate can predict sensitivity to therapy.

CBIO-15. MDM2 INHIBITOR SYNERGY WITH BCL-XL INHIBITION FOR p53 WILD TYPE GLIOBLASTOMA

BACKGROUND

Glioblastoma (GBM) is an infiltrative, uniformly fatal brain tumor, treated with surgery, radiation, and Temozolomide (TMZ). Chemoradiation induces a senescent-like phenotype, which contributes to disease recurrence. We recently found that, radiated GBM cells can be eliminated by inhibition of BCL-XL. However, it remains unknown whether p53 is involved in this process and whether the elimination of senescent cells by BCL-XL inhibition could be augmented by MDM2 inhibition, a negative p53 regulator.

METHODS

p53-mutant (GBM6/GBM123) and p53-WT (GBM39/GBM76) human GBM cells were treated with 5Gy or TMZ following 48 hours of MDM2 inhibitor (AMG232) or vehicle treatment and maintained for seven days to establish a senescent-like phenotype. We evaluated the IC50 for BCL-XL inhibitor (A1331852) in radiated vs. non-radiated cells with or without MDM2 inhibitor pre-treatment.

RESULTS

MDM2-inhibitor treatment prior to radiation increased the expression of p21 and lead to increased cell death when combined with BCL-XL inhibition in p53-WT GBM cells. IC50 of BCL-XL inhibitor after prior MDM2 pretreatment and radiation in GBM76 was 4.5□M compared to 33.5□M, 18.1□M, and 32.3□M in vehicle without radiation, vehicle with radiation, and MDM2 inhibitor-alone treatment groups, respectively(p=0.0036). The IC50 of BCL-XL inhibitor without MDM2-inhibition in non-irradiated and radiated, as well as pre-administration of MDM2 inhibitor in non-irradiated and radiated GBM39 cells was 5618nM, 16117nM, 3926nM and 276.5nM, respectively(p=0.0003). Conversely, MDM2 co-inhibition with BCL-XL did not lead to increased rates of cell death in p53-mutant cell(p&gt;0.05).

CONCLUSION

We previously identified that BCL-XL inhibition promotes cell death in senescent GBM cells. We build upon that work, demonstrating the increased rates of cell death can be augmented by MDM2 inhibition, but only in p53-WT cells. These findings highlight a novel therapeutic target for treating latent GBM tumors prior to recurrence, with the additional of MDM2 inhibition greatly increasing the efficacy of BCL-XL targeting agents.

RBIO-03. HETEROGENEITY OF HUMAN PATIENT-DERIVED XENOGRAFTS GROWTH RATES RESPONSES TO THE RADIATED MICROENVIRONMENT

BACKGROUND

Radiotherapy, combined with surgical resection and chemotherapy, remains a first-line treatment for infiltrative gliomas. However, these tumors are not surgically curable, and often recur, even within the prior radiation field, and may demonstrate a more aggressive phenotype. Importantly, high grade gliomas display diverse molecular phenotypes, and whether this genetic variability leads to divergent behaviour in the radiated tumor microenvironment is unknown. Herein, we characterize the effects of the irradiated brain microenvinroment on nine additional unique GBM cell lines to better understand the nuances of how tumor molecular phenotypes influence cellular dynamics.

METHODS

Female athymic nude mice were randomly divided into cranial radiation (15 Gy) and non-radiated groups. Mice then underwent intracranial implantation with one of the selected patient-derived xenograft (PDX) GBM cell lines (GBM 6, 10, 12, 39, 46, 76, 123, 164, 196; total n=8-15, per group, per line). Kaplan-Meyer (K-M) and log-rank tests were performed to compare the survival between irradiated and non-irradiated groups.

RESULT

Of nine previously untested human GBM lines, we found that five demonstrated shorter survival in the pre-radiated brain (GBM 6, 46, 76, 164, 196). However, two lines yielded prolonged survival in the pre-radiated brain (GBM 10, 12); GBM 39, 123 whose rate of growth was not impacted by the radiated brain.

CONCLUSION

These results highlight the likely critical impact of the irradiated microenvironment on tumor behaviour, yet illustrate that different tumors may exhibit opposing responses. Although further evaluation will be needed to understand mechanisms of divergent behavior, our data suggest the increased rate of growth in the radiated microenvironment may not apply to the fastest-growing tumor lines, which could instead demonstrate a paradoxical response.

CBIO-11. NOVEL THERAPY TO TARGET PR-RECURRENT GLIOMA

BACKGROUND

Glioblastoma is a fatal infiltrative primary brain tumor, and standard care includes maximal safe surgical resection followed by radiation and Temozolomide (TMZ). Therapy-resistant residual cells persist in a latent state a long time before inevitable recurrence. Conventional radiation and Temozolomide (TMZ) treatment cause oxidative stress and DNA damage resulting senescent-like state of cell-cycle arrest. However, increasing evidence demonstrates escaping senescence leads to tumor recurrence. Thus, the ablation of senescent tumor cells after chemoradiation may be an avenue to limit tumor recurrence.

METHODS

100uM TMZ for 7days or 10-20Gy radiation (cesium gamma radiator) was used for senescence induction in human glioblastoma in vitro and confirmed by SA-Beta gal staining and PCR. Replication arrest assessed by automated quantification of cellular confluence (Thermo Scientific Series 8000 WJ Incubator). We evaluated the IC50 for several senolytics targeting multiple SCAPs, including Dasatinib, Quercetin, AMG-232, Fisetin, Onalespib, Navitoclax, and A1331852, and in senescent vs. proliferating cells.

RESULTS

Among the senolytic tested, the Bcl-XL inhibitors A1331852 and Navitoclax both shown senolytic effect by selectively killing radiated, senescent tumor cells at lower concentrations as compared to 0Gy treated non-senescent cells. Across 12 GBM cell lines, IC50 for senescent cells was 6–500 times lower than non-senescent GBM(p&lt; 0.005). Such differential sensitivity to Bcl-XL inhibition after radiation has also observed by BCL-XL knockdown in radiated glioma.

CONCLUSION

These findings suggest the potential to harness radiation-induced biology to ablate surviving quiescent cells and demonstrate Bcl-XL dependency as a potential vulnerability of surviving tumor cells after exposure to chemoradiation.

SURG-31. SURGICAL OUTCOME ANALYSES ON 244 CENTRAL NERVOUS SYSTEM HEMANGIOBLASTOMA

BACKGROUND

Surgical resection of the central nervous system hemangioblastoma is often challenging, with vascular-rich nature and surrounding critical structures. von Hippel-Lindau (VHL) disease cases make the management more difficult with repeated surgeries required for multiple lesions. Here we investigated the surgical outcome of CNS HGBs on a large cohort to clarify the clinical and radiological parameters pertaining to the surgical success.

METHODS

Retrospective analysis of consecutive, neurosurgically managed CNS HGB at Mayo Clinic, 1988-2018.

RESULTS

Total 244 surgeries were performed for 172 patients. Gross total resection (GTR) was achieved in 90.0%, which was lower in cases brainstem lesions (78.3%) and was associated with the tumor, especially solid-portion volume (p=0.017). Intraoperative blood loss correlated with the size of solid portions, and the transfusion was performed in 7.5%. Postoperative complication was observed in 52.2%, including new/worsening neurological deficit in 45.4%, wound complication in 9.1% and systemic complication in 4.0%. Postoperative rehabilitation was introduced in 61.7% of the patients, which was statistically associated with age, non-GTR and tumor location (brainstem and spine) on multivariate analysis (p=0.0031, 0.027 and 0.0066, respectively). Treatment-free survival was longer in VHL (vs sporadic) cases and GTR (vs non-GTR) cases, and multivariate analysis showed GTR was the only factor associated with treatment-free survival (p=0.0015).

CONCLUSIONS

Surgery for CNS HGBs was shown to be challenging, with abundant intraoperative bleeding and high risk of postoperative complications necessitating rehabilitation. GTR of the lesion is of utmost importance, which increases the chance of long treatment-free survival as well as favorable direct postoperative clinical course.

Sumatriptan improves the locomotor activity and neuropathic pain by modulating neuroinflammation in rat model of spinal cord injury

OBJECTIVES

To investigate the therapeutic effects of sumatriptan in a rat model of spinal cord injury (SCI) and possible anti-inflammatory and analgesic mechanisms underlying this effect.

METHODS

Using an aneurysm mini-clip model of contusive SCI, T9-10 laminectomies were performed for 60 male rats. Animals were divided into six experimental groups (n = 10 per group) as follows: a minocycline administered positive control group, a saline-vehicle negative control group, a sham-operated group, and three experimental groups which received separate doses of sumatriptan (0.1, 0.3 and 1 mg/kg). Behavioural assessments were used to evaluate locomotor activity and neuropathic pain for 28 days. At the end of the study, spinal cord tissues were collected from sacrificed animals for histopathological analysis. Levels of calcitonin gene-related peptide (CGRP) and two pro-inflammatory cytokines (tumor necrosis factor [TNF]-α and interleukin [IL]-1β) were assessed by the enzyme-linked immunosorbent assay (ELISA).

RESULTS

Sumatriptan significantly (P < 0.001) improved the locomotor activity in SCI group. Sumatriptan was also more effective than the positive control, i.e. minocycline (0.3 mg/kg). Additionally, sumatriptan and minocycline similarly attenuated the mechanical and thermal allodynia in SCI (P < 0.001). TNF-α, IL-1β and CGRP levels in sumatriptan- and minocycline-treated groups significantly (P < 0.001) decreased compared to controls. Histopathological analysis also revealed a markedly improvement in hemorrhage followed by inflammatory cell invasion, neuronal vacuolation, and cyst formation in both sumatriptan- and minocycline-treated groups compared to control animals.

CONCLUSIONS

Sumatriptan improves functional recovery from SCI through its anti-inflammatory effects and reducing pro-inflammatory and pain mediators.

Adjuvant radiation for WHO grade II and III intracranial meningiomas: insights on survival and practice patterns from a National Cancer Registry

INTRODUCTION

WHO grades II (atypical) and III (malignant) meningiomas are associated with significant morbidity and mortality. The role of adjuvant radiotherapy (RT) in management remains controversial. The goal of this study was to evaluate the impact of adjuvant RT on 5-year survival in patients with atypical and malignant meningiomas. We secondarily aimed to assess contemporary practice patterns and the impact of sociodemographic factors on outcome.

METHODS

We queried the National Cancer Database for patients ≥ 18 years of age with cranial atypical or malignant meningiomas from 2010 through 2015 who underwent surgical resection with or without adjuvant radiotherapy. Subjects with unknown WHO grade or radiation status and those not receiving any surgical procedure were excluded from analysis.

RESULTS

The study includes 7486 patients, 6788 with atypical and 698 with malignant meningiomas. Overall 5-year survival was 76.9% (95% CI 75.5-78.3%) and 43.3% (95% CI 38.8-48.2%) among patients with WHO grades II and III meningiomas, respectively. Adjuvant RT correlated with improved survival in a multivariable model in patients with grade II tumors (HR 0.78; p = 0.029) regardless of the extent of resection. Age (HR 2.33; p < 0.001), male sex (HR 1.27; p < 0.001), Black race (HR 1.27; p = 0.011) and Charlson-Deyo Score ≥ 2 (1.35; p = 0.001) correlated with poorer survival whereas private insurance (HR 0.71; p < 0.001) correlated with improved survival. Adjuvant RT was also associated with improved 5-year survival among those with grade III tumors on univariate analysis (log-rank p = 0.006) but was underpowered for multivariable modeling. Utilization of adjuvant radiotherapy was only 28.4% and correlated with private insurance status. Academic institutions (25.3%) and comprehensive community cancer programs (21.4%) had lower radiotherapy utilization rates compared with integrated network cancer programs (30.5%) and community cancer programs (29.7%).

CONCLUSIONS

Adjuvant RT may correlate with improved overall survival in patients with grades II and III intracranial meningiomas regardless of the extent of resection. There is poor utilization of adjuvant RT for patients with grades II and III meningiomas likely due to a paucity of quality data on the subject. These findings will be strengthened with prospective data evaluating the role of adjuvant RT.

Glioblastoma Recurrence Versus Treatment Effect in a Pathology-Documented Series

OBJECTIVE

Patients diagnosed with glioblastoma (GBM) are treated with surgery followed by fractionated radiotherapy with concurrent and adjuvant temozolomide. Patients are monitored with serial magnetic resonance imaging (MRI). However, treatment-related changes frequently mimic disease progression. We reviewed a series of patients undergoing surgery for presumed first-recurrence GBM, where pathology reports were available for tissue diagnosis, in order to better understand factors associated with a diagnosis of treatment-related changes on final pathology.

METHODS

Patient records at a single institution between 2005 and 2015 were retrospectively reviewed. Pathology reports were reviewed to determine diagnosis of recurrent GBM or treatment effect. Survival analysis was performed interrogating overall survival (OS) and progression-free survival (PFS). Correlation with radiation treatment plans was also examined.

RESULTS

One-hundred-twenty-three patients were identified. One-hundred-sixteen patients (94%) underwent resection and seven underwent biopsy. Treatment-related changes were reported in 20 cases (16%). These patients had longer median OS and PFS from the time of recurrence than patients with true disease progression. However, there was no significant difference in OS from the time of initial diagnosis. Treatment effect was associated with surgery within 90 days of completing radiation. In patients receiving radiation at our institution (n = 53), larger radiation target volume and a higher maximum dose were associated with treatment effect.

CONCLUSION

Treatment effect was associated with surgery nearer to completion of radiation, a larger radiation target volume, and a higher maximum point dose. Treatment effect was associated with longer PFS and OS from the time of recurrence, but not from the time of initial diagnosis.

Radiation Induced Metabolic Alterations Associate With Tumor Aggressiveness and Poor Outcome in Glioblastoma

Glioblastoma (GBM) is uniformly fatal with a 1-year median survival, despite best available treatment, including radiotherapy (RT). Impacts of prior RT on tumor recurrence are poorly understood but may increase tumor aggressiveness. Metabolic changes have been investigated in radiation-induced brain injury; however, the tumor-promoting effect following prior radiation is lacking. Since RT is vital to GBM management, we quantified tumor-promoting effects of prior RT on patient-derived intracranial GBM xenografts and characterized metabolic alterations associated with the protumorigenic microenvironment. Human xenografts (GBM143) were implanted into nude mice 24 hrs following 20 Gy cranial radiation vs. sham animals. Tumors in pre-radiated mice were more proliferative and more infiltrative, yielding faster mortality (p < 0.0001). Histologic evaluation of tumor associated macrophage/microglia (TAMs) revealed cells with a more fully activated ameboid morphology in pre-radiated animals. Microdialyzates from radiated brain at the margin of tumor infiltration contralateral to the site of implantation were analyzed by unsupervised liquid chromatography-mass spectrometry (LC-MS). In pre-radiated animals, metabolites known to be associated with tumor progression (i.e., modified nucleotides and polyols) were identified. Whole-tissue metabolomic analysis of pre-radiated brain microenvironment for metabolic alterations in a separate cohort of nude mice using ¹H-NMR revealed a significant decrease in levels of antioxidants (glutathione (GSH) and ascorbate (ASC)), NAD⁺, Tricarboxylic acid cycle (TCA) intermediates, and rise in energy carriers (ATP, GTP). GSH and ASC showed highest Variable Importance on Projection prediction (VIPpred) (1.65) in Orthogonal Partial least square Discriminant Analysis (OPLS-DA); Ascorbate catabolism was identified by GC-MS. To assess longevity of radiation effects, we compared survival with implantation occurring 2 months vs. 24 hrs following radiation, finding worse survival in animals implanted at 2 months. These radiation-induced alterations are consistent with a chronic disease-like microenvironment characterized by reduced levels of antioxidants and NAD⁺, and elevated extracellular ATP and GTP serving as chemoattractants, promoting cell motility and vesicular secretion with decreased levels of GSH and ASC exacerbating oxidative stress. Taken together, these data suggest IR induces tumor-permissive changes in the microenvironment with metabolomic alterations that may facilitate tumor aggressiveness with important implications for recurrent glioblastoma. Harnessing these metabolomic insights may provide opportunities to attenuate RT-associated aggressiveness of recurrent GBM.

Hospital volume-outcome relationship in severe traumatic brain injury: stratified analysis by level of trauma center

OBJECTIVE

The nature of the volume-outcome relationship in cases with severe traumatic brain injury (TBI) remains unclear, with considerable interhospital variation in patient outcomes. The objective of this study was to understand the state of the volume-outcome relationship at different levels of trauma centers in the United States.

METHODS

The authors queried the National Trauma Data Bank for the years 2007-2014 for patients with severe TBI. Case volumes for each level of trauma center organized into quintiles (Q1-Q5) served as the primary predictor. Analyzed outcomes included in-hospital mortality, total hospital length of stay (LOS), and intensive care unit (ICU) stay. Multivariable regression models were performed for in-hospital mortality, overall complications, and total hospital and ICU LOSs to adjust for possible confounders. The analysis was stratified by level designation of the trauma center. Statistical significance was established at p < 0.001 to avoid a type I error due to a large sample size.

RESULTS

A total of 122,445 patients were included. Adjusted analysis did not demonstrate a significant relationship between increasing hospital volume of severe TBI cases and in-hospital mortality, complications, and nonhome hospital discharge disposition among level I-IV trauma centers. However, among level II trauma centers, hospital LOS was longer for the highest volume quintile (adjusted mean difference [MD] for Q5: 2.83 days, 95% CI 1.40-4.26 days, p < 0.001, reference = Q1). For level III and IV trauma centers, both hospital LOS and ICU LOS were longer for the highest volume quintile (adjusted MD for Q5: LOS 4.6 days, 95% CI 2.3-7.0 days, p < 0.001; ICU LOS 3.2 days, 95% CI 1.6-4.8 days, p < 0.001).

CONCLUSIONS

Higher volumes of severe TBI cases at a lower level of trauma center may be associated with a longer LOS. These results may assist policymakers with target interventions for resource allocation and point to the need for careful prehospital decision-making in patients with severe TBI.