Abstract 2876: Adhesion GPCR CD97/ADGRE5 facilitates invasion in patient-derived glioma stem cells and induces changes in EGFR and Sox2 expression

The main obstacles for effective treatment of Glioblastoma (GBM) are high invasiveness and heterogeneity. Each GBM tumor is composed of multiple genetically distinct subpopulations of Glioma Stem Cells (GSCs), exhibiting high cell plasticity affecting their invasive and proliferative properties. Treatment interventions and changes in microenvironment force GSCs to adapt through gene expression that supports therapeutic resistance. Expression level of the surface receptor CD97/ADRGE5 positively correlates with poor GBM patient prognosis, but its role in this tumor has not been elucidated. Here, we examined the function of CD97 in primary GSCs derived from five GBM tumors, which belong to three major genetic subtypes. We manipulated CD97 levels in these GSCs by knockdown and overexpression and analyzed the following: (i) expression of stem and subtype markers, (ii) in vitro invasive properties, (iii) cell proliferation, (iv) expression of the key proteins that regulate GSCs cellular state and influence their adaptive behavior. Our data showed that CD97 knockdown in GSCs of mesenchymal and classical subtype reduced their invasion rate in vitro. CD97 signaling positively affected expression of Epidermal Growth Factor Receptor, the main driver of astrocyte-like fate in GSCs and changed the expression of the astrocytic marker GFAP. Finally, we discovered a possible link between CD97 and expression of transcription factor Sox2, the key regulator of the endothelial-to-mesenchymal transition process that plays a crucial role in initiation of cancer cell invasion.

Citation Format: Tatiana I. Slepak, Daniel G. Eichberg, Ana L. Pascoini, Ricardo J. Komotar, Michael E. Ivan. Adhesion GPCR CD97/ADGRE5 facilitates invasion in patient-derived glioma stem cells and induces changes in EGFR and Sox2 expression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2876.

A Cohort Study on Prognostic Factors for Laser Interstitial Thermal Therapy Success in Newly Diagnosed Glioblastoma

BACKGROUND

Laser interstitial thermal therapy (LITT) is a promising approach for cytoreduction of deep-seated gliomas. However, parameters contributing to treatment success remain unclear.

OBJECTIVE

To identify extent of ablation (EOA) and time to chemotherapy (TTC) as predictors of improved overall and progression-free survival (OS, PFS) and suggest laser parameters to achieve optimal EOA.

METHODS

Demographic, clinical, and survival data were collected retrospectively from 20 patients undergoing LITT for newly diagnosed glioblastoma (nGBM). EOA was calculated through magnetic resonance imaging-based volumetric analysis. Kaplan-Meier and multivariate Cox regression were used to examine the relationship between EOA with OS and PFS accounting for covariates (age, isocitrate dehydrogenase-1 (IDH1) mutation, O6-methylguanine-DNA methyltransferase hypermethylation). The effect of laser thermodynamic parameters (power, energy, time) on EOA was identified through linear regression.

RESULTS

Median OS and PFS for the entire cohort were 36.2 and 3.5 mo respectively. Patient's with >70% EOA had significantly improved PFS compared to ≤70% EOA (5.2 vs 2.3 mo, P = .01) and trended toward improved OS (36.2 vs 11 mo, P = .07) on univariate and multivariate analysis. Total laser power was a significant predictor for increased EOA when accounting for preoperative lesion volume (P = .001). Chemotherapy within 16 d of surgery significantly predicted improved PFS compared to delaying chemotherapy (9.4 vs 3.1 mo, P = .009).

CONCLUSION

Increased EOA was a predictor of improved PFS with evidence of a trend toward improved OS in LITT treatment of nGBM. A strategy favoring higher laser power during tumor ablation may achieve optimal EOA. Early transition to chemotherapy after LITT improves PFS.

Multiple Iterations of Magnetic Resonance-Guided Laser Interstitial Thermal Ablation of Brain Metastases: Single Surgeon's Experience and Review of the Literature

BACKGROUND

Prior treatment with magnetic resonance-guided, laser-induced thermal therapy (LITT) is widely assumed not to be a contraindication for further treatment of brain lesions, including further iterations of LITT. However, the safety and efficacy of repeat LITT treatments have never been formally investigated.

OBJECTIVE

To evaluate treatment with multiple iterations of LITT.

METHODS

All patients treated with LITT at least twice at our institution were included in the study. Outcomes and neurological examinations from before and after surgery were retrospectively examined from clinic notes. Perilesonal edema was determined at various timepoints using volumetric data derived from manual tracings of fluid-attenuated inversion recovery (FLAIR) enhancement on magnetic resonance imaging (MRI). Finally, a literature review of prior cases of repeat LITT was performed.

RESULTS

A total of 9 patients underwent 18 treatments with LITT; all but 1 of whom were treated for metastatic brain lesions. One patient had a transient cerebrospinal fluid leak, whereas a second patient had a superficial wound infection, both of which resolved with standard medical care. The remaining 7 patients tolerated all LITT procedures without complication. Analysis of perilesional edema volume demonstrated a correlation with the amount of energy delivered during LITT. Literature review found 5 published papers describing 9 patients who underwent LITT more than once, the majority of whom tolerated repeat LITT well.

CONCLUSION

LITT is a safe and promising treatment modality and may be used multiple times without issue. There appears to be an association between the amount of energy delivered during a LITT session and the degree of postoperative perilesional edema.

The role of human endogenous retroviruses in gliomas: from etiological perspectives and therapeutic implications

Accounting for approximately 8% of the human genome, Human Endogenous Retroviruses (HERVs) have been implicated in a variety of cancers including gliomas. In normal cells, tight epigenetic regulation of HERVs prevent aberrant expression; however, in cancer cells, HERVs expression remains pervasive, suggesting a role of HERVs in oncogenic transformation. HERVs may contribute to oncogenesis in several ways including insertional mutagenesis, chromosomal rearrangements, proto-oncogene formation, and maintenance of stemness. On the other hand, recent data has suggested that reversing epigenetic silencing of HERVs may induce robust anti-tumor immune responses, suggesting HERVs' potential therapeutic utility in gliomas. By reversing epigenetic modifications that silence HERVs, DNA methyltransferase and histone deacetylase inhibitors may stimulate a viral-mimicry cascade via HERV-derived dsRNA formation that induce interferon-mediated apoptosis. Leveraging this anti-tumor autoimmune response may be a unique avenue to target certain subsets of epigenetically-dysregulated gliomas. Nevertheless, the role of HERVs in gliomas as either arbitrators of oncogenesis or forerunners of the innate anti-tumor immune response remains unclear. Here, we review the role of HERVs in gliomas, their potential dichotomous function in propagating oncogenesis and stimulating the anti-tumor immune response and identify future directions for research.

30-Day Readmissions and Coordination of Care Following Endoscopic Transsphenoidal Pituitary Surgery: Experience with 409 Patients

Objective The study aimed to (1) quantify readmission rates and common causes of readmission following endoscopic transsphenoidal pituitary surgery (ETPS); (2) identify risk factors that may predict readmission within 30 days; (3) assess postoperative care coordination with endocrinology follow-up; and (4) identify patients for whom targeted interventions may reduce 30-day readmissions.

Methods Retrospective quality improvement review of patients with pituitary adenoma who underwent ETPS from December 2010 to 2018 at a single tertiary care center.

Results A total of 409 patients were included in the study, of which 57 (13.9%) were readmitted within 30 days. Hyponatremia was the most common cause of readmission (4.2%) followed by pain/headache (3.9%), cerebrospinal fluid leak (3.4%), epistaxis (2.7%), hypernatremia (1.2%), and adrenal insufficiency (1.2%). Patients with hyponatremia were readmitted significantly earlier than other causes (4.3 ± 2.2 vs. 10.6 ± 10.9 days from discharge, p = 0.032). Readmitted patients had significantly less frequent outpatient follow-up with an endocrinologist than the nonreadmitted cohort (56.1 vs. 70.5%, p = 0.031). Patients who had outpatient follow-up with an endocrinologist were at lower risk of readmission compared with those without (odds ratio: 0.46; 95% confidence interval: 0.24–0.88).

Conclusion Delayed hyponatremia is one of the most common causes of 30-day readmission following ETPS. Postoperative follow-up with an endocrinologist may reduce risk of 30-day readmission following ETPS.

Implications for Clinical Practice A multidisciplinary team incorporating otolaryngologist, neurosurgeons, and endocrinologist may identify patients at risk of 30-day readmissions. Protocols checking serum sodium within 1 week of surgery in conjunction with endocrinologist to tailor fluid restriction may reduce readmissions from delayed hyponatremia.

Emergent Radiotherapy for Leukemia-Induced Cranial Neuropathies Refractory to Intrathecal Therapy

Neurologic symptoms from leukemic infiltration of the central nervous system are an oncologic emergency, and expeditious treatment is required to preserve function. We report the case of a 44-year-old patient with relapsed acute myeloid leukemia (AML) who developed sub-acute cranial neuropathies refractory to treatment with intrathecal (IT) chemotherapy. The patient was therefore treated with an emergent course of whole-brain radiotherapy, resulting in immediate improvement and subsequent resolution of cranial neuropathies. This case illustrates that while central nervous system involvement by AML is rare, radiotherapy remains an effective modality to avoid long-term morbidity in patients failing to respond to systemic or IT chemotherapy.

Current experimental therapies for atypical and malignant meningiomas

INTRODUCTION

Atypical (WHO grade II) and malignant meningiomas (WHO Grade III) are a rare subset of primary intracranial tumors. Given their relatively high recurrence rate after surgical resection and radiotherapy, there has been a recent push to explore other adjuvant treatment options for these treatment-refractory tumors. Recent advances in molecular sequencing of tumors have elucidated new pathways and drug targets which are currently being studied. This article provides a thorough overview of novel investigational therapeutics including targeted therapy, immunotherapy, and new technological modalities for atypical and malignant meningiomas.

METHODS

We performed a comprehensive review of the available literature regarding preclinical and clinical evidence for emerging treatments for high grade meningiomas from 1980 to 2020 including contemporaneous clinical trials.

RESULTS

There is encouraging preclinical evidence regarding the efficacy of the emerging treatments discussed in this article. Several clinical trials are currently recruiting patients to translate targeted molecular therapy for meningiomas. Several clinical studies have suggested a clinical benefit of combinatorial treatment for these treatment-refractory tumors.

CONCLUSION

With numerous active clinical trials for high grade meningiomas, a meaningful improvement in the outcomes for these tumors may be on the horizon.

Stimulated Raman Histology for Rapid Intraoperative Diagnosis of Gliomas

BACKGROUND

Intraoperative pathologic diagnosis traditionally involves frozen section histopathology, which may be labor and time intensive. Indeed, a technique that streamlines the acquisition and evaluation of intraoperative histologic data may expedite surgical decision-making and shorten operative time. Stimulated Raman histology (SRH) is an emerging technology that allows for more rapid acquisition and interpretation of intraoperative histopathologic data.

METHODS

A blinded, prospective cohort study was performed for 82 patients undergoing resection for a central nervous system tumor. Of these, 21 patients were diagnosed with glioma either intraoperatively or postoperatively on permanent section histology and included in this study. Time to diagnosis (TTD) and diagnostic accuracy relative to permanent section (the gold standard) were compared between SRH-based diagnosis and conventional frozen section histology. Diagnostic concordance with permanent section was also compared between frozen histopathology and SRH diagnosis.

RESULTS

Diagnostic accuracy was not significantly different between methods (P = 1.00). Diagnostic concordance was not significantly different between methods when comparing 95% confidence intervals for kappa values (κ = 0.215; κ = 0.297; κ = 0.369). Lastly, mean TTD was significantly shorter with SRH-based diagnosis compared with frozen section (43 vs. 9.7 minutes, P < 0.0001). SRH was able to identify key features associated with varying glioma types.

CONCLUSIONS

SRH allows for rapid intraoperative diagnosis without sacrificing diagnostic accuracy. SRH may serve as a promising adjuvant to conventional histopathology to expedite intraoperative pathology consultation and surgical decision-making.

Rapid Intraoperative Diagnosis of Meningiomas using Stimulated Raman Histology

BACKGROUND

Frozen section is a time- and labor-intensive method for intraoperative pathologic diagnosis. As a result, there exists a need to expedite and streamline the acquisition and interpretation of diagnostic histologic data to inform surgical decision making. Stimulated Raman histology (SRH) is an emerging technology that may serve to expedite the acquisition and interpretation of histologic data in the operating room.

METHODS

A blinded, prospective cohort study of 82 patients undergoing resection for tumors of the central nervous system was performed. Twenty-six patients with diagnoses of meningioma on SRH, frozen, or permanent section were included in this subanalysis. Diagnostic time and accuracy of stimulated SRH histology images were compared with the gold standard (frozen section). Agreement of SRH and frozen section diagnosis with permanent section (true) diagnosis was also compared.

RESULTS

Mean time-to-diagnosis was significantly shorter for SRH-mediated diagnosis compared with frozen section (9.2 vs. 35.8, P < 0.0001). Diagnostic accuracy was not significantly different between methods (P = 0.15). Diagnostic agreement was not significantly different between SRH versus frozen, SRH versus permanent, or frozen versus permanent section methods (P = 0.5, P = 0.5, P = 1.00).

CONCLUSIONS

SRH is a promising adjuvant technology that may expedite intraoperative neuropathologic consult without sacrificing diagnostic accuracy.

The Focused Neurosurgical Examination During Telehealth Visits: Guidelines During the COVID-19 Pandemic and Beyond

OBJECTIVE

 To provide guidelines to healthcare workers for performing a focused neurological examination via telemedicine during the coronavirus disease-2019 (COVID-2019) pandemic.

METHODS

 We reviewed our department's outpatient clinic visits after the implementation of a telemedicine protocol in response to the COVID-19 crisis. Crossover rates from telehealth to in-person visits were evaluated and guidelines for performing a telemedicine neurological exam were created based on the consensus of 16 neurosurgical attending providers over a four-month period.

RESULTS

 From March 23, 2020 to July 20, 2020, some 2157 telehealth visits were performed in our department. Some 26 were converted to in-person visits by the provider request with the most cited reason for conversion being the need for a more detailed patient evaluation. Based on these experiences, we created a graphical tutorial to address the key components of the neurological exam with adaptations specific to the telehealth visit.

CONCLUSIONS

 In response to the global coronavirus pandemic, telemedicine has become an integral part of neurosurgeons' daily practice. Telemedicine failures remain low but primarily occur due to a need for more comprehensive evaluations. We provide guidelines for the neurosurgical exam during telehealth visits in an effort to assuage some of these issues.

Clinical trials using oncolytic viral therapy to treat adult glioblastoma: a progress report

OBJECTIVE

Adult glioblastoma (GBM) has proven refractory to decades of innovation. Oncolytic viral therapy represents a novel therapy that uses viral vectors as both a delivery and therapeutic mechanism to target GBM cells. Despite the growing body of basic science data supporting the feasibility of viral therapy to treat GBM, the reporting of clinical trial results is heterogeneous. Correspondingly, the aim of this study was to present a contemporary summary of the progress all clinical trials have made to date.

METHODS

The ClinicalTrials.gov database was reviewed in August 2020 for all possible interventional clinical trials involving viral vector-based therapy to treat adult GBM. These were then screened against selection criteria to identify pertinent clinical trials.

RESULTS

A total of 29 oncolytic viral therapy trials treating adult GBM were identified. The median start and expected completion years were 2014 and 2020, respectively. At the time of this writing, 10 (35%) trials were reported to have completed recruitment, whereas 7 (24%) were actively recruiting. The median target enrollment number was 36 (range 13-108), with the majority of trials being phase I (n = 18, 62%), and involving secondary GBM among other malignant glioma (n = 19, 66%). A total of 10 unique viral vectors were used across all trials, with the most common being adenovirus (n = 16, 55%). Only 2 (7%) phase I trials to date have reported outcomes on the ClinicalTrials.gov portal. Results of 12 additional clinical trials were found in academic publications, with median progression-free and overall survival times of 3 and 15 months, respectively, after the first viral dose at recurrence. The coordination of the large majority of trials originated from the US (n = 21, 72%), and the median number of testing sites per trial was 1 (range 1-15), via industry funding (n = 18 trials, 62%).

CONCLUSIONS

There are multiple early-stage oncolytic viral therapy clinical trials for adult GBM currently active. To date, limited results and outcomes are promising but scarce. The authors expect this to change in the near future because many trials are scheduled to have either nearly or actually reached their expected recruitment completion time. How exactly oncolytic viral therapy will fit into the current treatment paradigms for primary and secondary GBM remains to be seen, and will not be known until safety and toxicity profiles are established by these clinical trials.

The Role of Laser Interstitial Thermal Therapy in Surgical Neuro-Oncology: Series of 100 Consecutive Patients

BACKGROUND

Laser interstitial thermal therapy (LITT) is an adjuvant treatment for intracranial lesions that are treatment refractory or in deep or eloquent brain. Initial studies of LITT in surgical neuro-oncology are limited in size and follow-up.

OBJECTIVE

To present our series of LITT in surgical neuro-oncology to better evaluate procedural safety and outcomes.

METHODS

An exploratory cohort study of all patients receiving LITT for brain tumors by a single senior neurosurgeon at a single center between 2013 and 2018. Primary outcomes included extent of ablation (EOA), time to recurrence (TTR), local control at 1-yr follow-up, and overall survival (OS). Secondary outcomes included complication rate. Outcomes were compared by tumor subtype. Predictors of outcomes were identified.

RESULTS

A total of 91 patients underwent 100 LITT procedures; 61% remain alive with 72% local control at median 7.2 mo follow-up. Median TTR and OS were 31.9 and 16.9 mo, respectively. For lesion subtypes, median TTR (months, not applicable [N/A] if <50% rate observed), local control rates at 1-yr follow-up, and median OS (months) were the following: dural-based lesions (n = 4, N/A, 75%, 20.7), metastases (n = 45, 55.9, 77.4%, 16.9), newly diagnosed glioblastoma (n = 11, 31.9, 83.3%, 32.3), recurrent glioblastoma (n = 14, 5.6, 24.3%, 7.3), radiation necrosis (n = 20, N/A, 67.2%, 16.4), and other lesions (n = 6, 12.3, 80%, 24.4). TTR differed by tumor subtype (P = .02, log-rank analysis). EOA predicted local control (P = .009, multivariate proportional hazards regression); EOA > 85% predicted longer TTR (P = .006, log-rank analysis). Complication rate was 4%.

CONCLUSION

Our series of LITT in surgical neuro-oncology, 1 of the largest to date, further evidences its safety and outcomes profile.

Telemedicine in Neurosurgery: Lessons Learned from a Systematic Review of the Literature for the COVID-19 Era and Beyond

BACKGROUND

Evolving requirements for patient and physician safety and rapid regulatory changes have stimulated interest in neurosurgical telemedicine in the COVID-19 era.

OBJECTIVE

To conduct a systematic literature review investigating treatment of neurosurgical patients via telemedicine, and to evaluate barriers and challenges. Additionally, we review recent regulatory changes that affect telemedicine in neurosurgery, and our institution's initial experience.

METHODS

A systematic review was performed including all studies investigating success regarding treatment of neurosurgical patients via telemedicine. We reviewed our department's outpatient clinic billing records after telemedicine was implemented from 3/23/2020 to 4/6/2020 and reviewed modifier 95 inclusion to determine the number of face-to-face and telemedicine visits, as well as breakdown of weekly telemedicine clinic visits by subspecialty.

RESULTS

A total of 52 studies (25 prospective and 27 retrospective) with 45 801 patients were analyzed. A total of 13 studies were conducted in the United States and 39 in foreign countries. Patient management was successful via telemedicine in 99.6% of cases. Telemedicine visits failed in 162 cases, 81.5% of which were due to technology failure, and 18.5% of which were due to patients requiring further face-to-face evaluation or treatment. A total of 16 studies compared telemedicine encounters to alternative patient encounter mediums; telemedicine was equivalent or superior in 15 studies. From 3/23/2020 to 4/6/2020, our department had 122 telemedicine visits (65.9%) and 63 face-to-face visits (34.1%). About 94.3% of telemedicine visits were billed using face-to-face procedural codes.

CONCLUSION

Neurosurgical telemedicine encounters appear promising in resource-scarce times, such as during global pandemics.

Remote Cerebellar Hemorrhage Associated With Intra-Operative Cerebrospinal Fluid Leak: A Report of Two Rare Case Presentations and Review of the Literature

Remote cerebellar hemorrhage (RCH) is a rare complication following cranial or spinal neurosurgical procedures. Traditionally, RCH has been associated with frontal or frontotemporal craniotomy with supine patient positioning. Though the exact etiology is unknown, theories have described patient positioning and excessive cerebrospinal fluid (CSF) drainage intra-operatively as contributing factors to cerebellar displacement (cerebellar sag), obstruction of venous flow, and pathogenesis of RCH. 

We report two cases of RCH following a prone, suboccipital craniotomy-C1 laminectomy and a temporal burr hole evacuation of a subdural hygroma. In each case, a large volume of CSF was rapidly evacuated intra-operatively. To the best of our knowledge, both instances represent relatively rare settings for RCH. Additionally, we conducted a comprehensive literature review of PubMed, EMBASE, and Web of Science for all cases of RCH in which peri-operative CSF leakage was explicitly detailed.

Although RCH is thought to be a rare complication of frontotemporal and frontal craniotomies, this case report signifies that RCH may occur in the setting of sub-occipital craniotomy or even after minimally invasive burr hole procedures. For these procedures, careful symptomatic monitoring and follow-up imaging remain essential in diagnosis. Controlled CSF drainage may be useful in mediating dramatic alterations in intracranial pressure (ICP) and cerebellar sag contributing to RCH.