Resected Brain Tumors Research Articles

Survival analysis of brain metastases secondary to breast cancer: A single-center experience.

e13111 Background: Brain metastasis (BM) contributes to substantial morbidity and mortality for breast cancer (BCa) patients (pts). Advances in systemic therapies have improved survival following BM diagnosis; however, other factors such as age, timing of BM development, and molecular features may also affect outcomes. Here we characterize the overall survival (OS) of pts with BM secondary to BCa treated at our institution with the aim of identifying predictors that can used to improve treatment and management. Methods: In an electronic medical record of “brain metastasis” and “breast cancer”, we identified pts aged >18 years treated between 2015 and 2022. All cases were manually reviewed by ≥2 reviewers. Cases with second metastatic (met) solid tumors, hematologic malignancies, or insufficient data were excluded. Only cases with intraparenchymal and/or leptomeningeal disease attributed to met BCa were included. Kaplan-Meier estimation and Cox regression were applied to OS. Results: Of 344 cases reviewed, 229 (1 male) were appropriate for inclusion. The median age at BM diagnosis (dx) was 58 years. 28% underwent surgical resection and 81% received radiation treatment for BM. With a median follow-up of 5 years, 82% of pts died and median OS (mOS) following BM dx was 14 months (95% CI: 9-19). Among 208 pts without de novo BM, time to BM development (mTBM) from primary BCa varied by subtype: mTBM (IQR) HR+HER2- of 6.4 years (3.9-10.5), HR+HER2+ of 3.5 years (2.0-9.1), HR-HER2+ of 2.1 years (1.2-3.1), TNBC of 2.4 years (1.1-4.9). mOS varied by BCa subtype (table, log-rank p=0.029). 41 cases had de novo met disease (met dx ≤2 months of BCa dx) with 21 (9%) having de novo BM. HER2+ BCa and shorter mTBM were associated with longer mOS (table). Pts with BM dx in 2nd or later met relapse vs. earlier BM (de novo or 1st met relapse), OS HR was 1.67 (95% CI: 1.24-2.25; p=0.001). OS did not vary by age at BM diagnosis. Conclusions: Our findings build on prior work showing differential BM survival by subtype. We observe significantly shorter post-BM survival among pts who develop BM after a second or later line of met treatment. Ongoing work will expand our database and explore molecular features of resected brain tumors. [Table: see text]

Optimizing perampanel monotherapy for surgically resected brain tumors.

Perampanel (PER) is an antiseizure medication (ASM) with a unique mechanism of action, which was approved in Japan for use in combination therapy in 2016 and as a monotherapy in 2020. It has exerted antitumor effects against several types of tumors in vitro. However, the efficacy of PER monotherapy for seizure control is not well-established in patients with brain tumor. In the present study, 25 patients with brain tumor treated using PER monotherapy at our institution were analyzed and compared with 45 patients treated using the most commonly prescribed ASM, levetiracetam (LEV). The PER group was younger and had a higher frequency of glioma cases. During drug administration, seizures were observed in two patients from the PER group (8.0%) and five patients from the LEV group (11.1%); however, the difference was not significant. The incidence of adverse effects did not significantly differ between the groups (12.0 and 2.2%, respectively). In the PER group, mild liver dysfunction was observed in two patients and drug rash in one. In the LEV group, a drug-induced rash was observed in one patient. PER monotherapy may be safe and effective for seizure treatment or prophylaxis in patients with brain tumor. Further large-scale clinical studies are warranted.

Abstract 4140: Enhanced microglial phagocytosis of metastatic brain tumor cells with Cd24a/Cd47 depletion

Abstract Despite the robust homeostasis of the brain, its high prevalence of tumor metastasis is intriguing and the underlying mechanism may contribute to the development of novel therapies. Microglia have emerged as promising therapeutic targets due to their role in brain parenchymal homeostasis. However, with evidence for both pro- and anti-tumorigenic functions, their role in brain metastasis (BrM) remains unclear. Here, we show that the microglial response to tumor cells within a single host is heterogeneous and can alter tumor fate. Single-cell RNA sequencing was performed on five surgically resected metastatic brain tumors, and the transcriptome of tumor-associated microglia was extracted by single-cell variational inference (scVI). Evidence for the coexistence of cytokine-secreting and angiogenesis-supporting subsets, as well as subsets associated with phagocytosis and antigen presentation, within each tumor sample was determined. To demonstrate the intra-tumoral functional heterogeneity of tumor-associated microglia, we established a metastatic brain tumor model that allows us to visualize the metastatic process and the dynamic microglial response in vivo by injecting mCherry-tagged allogeneic cancer cells into the internal carotid artery of CX3CR1-EGFP mice. Metastasis formation was suppressed in microglia-depleted mice, identifying a dominant microglial response that promotes tumor growth. However, continuous in vivo imaging of the BrM model revealed tumor-eradicating anti-tumor microglia coexisting with pro-tumor microglia in the same host. The transcriptome of anti-tumor microglia supported that they are enriched for phagocytosis, antigen processing and antigen presentation genes. The subset was identified in microglia extracted from human samples. We then examined the immune checkpoint of microglial phagocytosis in the tumor transcriptome and identified Cd24a and Cd47. Simultaneous deletion of both genes in cancer cells enhanced microglial phagocytosis, reduced tumor volume and improved survival, and rescue of both genes reversed these anti-tumor effects. The microglial dependency was addressed by microglial depletion experiments, and the anti-tumor effects were reproducible in nude mice lacking mature T cells. These results suggest that there are distinct immune cell subtypes that respond to lung tumor metastases in the brain and either promote tumor growth or inhibit metastasis through phagocytosis. Furthermore, anti-tumor activity in mouse models can be enhanced by genetic deletion of Cd24a and Cd47 in tumor cells, which regulate phagocytosis by microglia. Citation Format: Takahiro Tsuji, Haruka Hirose, Mariko Shindo, Rahadian Yudo Hartantyo, Yutaro Saito, Kazutaka Hosoya, Hiroshi Yoshida, Daisuke Kato, Akihiko Yoshizawa, Yoshiki Arakawa, Hiroaki Ozasa, Toyohiro Hirai, Hiroaki Wake. Enhanced microglial phagocytosis of metastatic brain tumor cells with Cd24a/Cd47 depletion [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4140.

A biosensor for D-2-hydroxyglutarate in frozen sections and intraoperative assessment of IDH mutation status

The oncometabolite D-2-hydroxyglutarate (D-2-HG) has emerged as a valuable biomarker in tumors with isocitrate dehydrogenase (IDH) mutations. Efficient detection methods are required and rapid intraoperative determination of D-2-HG remains a huge challenge. Herein, D-2-HG dehydrogenase from Achromobacter xylosoxidans (AX-D2HGDH) was found to have high substrate specificity. AX-D2HGDH dehydrogenizes D-2-HG and reduces flavin adenine dinucleotide (FAD) bound to the enzyme. Interestingly, the dye resazurin can be taken as another substrate to restore FAD. AX-D2HGDH thus catalyzes a bisubstrate and biproduct reaction: the dehydrogenation of D-2-HG to 2-ketoglutarate and simultaneous reduction of non-fluorescent resazurin to highly fluorescent resorufin. According to steady-state analysis, a ping-pong bi-bi mechanism has been concluded. The Km values for resazurin and D-2-HG were determined as 0.56 μM and 10.93 μM, respectively, suggesting high affinity to both substrates. On the basis, taking AX-D2HGDH and resazurin as recognition and fluorescence transducing element, a D-2-HG biosensor (HGAXR) has been constructed. HGAXR exhibits high sensitivity, accuracy and specificity for D-2-HG in different biological samples. With the aid of HGAXR and the matched low-cost palm-size detecting device, D-2-HG levels in frozen sections of resected brain tumor tissues can be measured in a direct, simple and accurate manner with a fast detection (1–3 min). As the technique of frozen section is familiar to surgeons and pathologists, HGAXR and the portable device can be easily integrated into the current workflow, having potential to provide rapid intraoperative pathology for IDH mutation status and guide decision-making during surgery.

Macrophages as a photosensitizer delivery system for photodynamic therapy: Potential for the local treatment of resected glioblastoma

BackgroundPhotodynamic therapy (PDT) efficacy is determined in part by the concentration of photosensitizer (PS) at the treatment site. The blood-brain barrier (BBB) poses a significant limitation on the transport of PS into the post-operative resection region where brain tumors most often recur. Macrophages (Ma), as opposed to free or nanoparticle bound agents, are known to actively migrate to and around tumors, and can therefore be used as delivery vectors for both drugs and photosensitizers. MethodsMouse Ma (RAW264.7) and F98 rat glioma cells were used in all experiments along with the photosensitizer AlPcS2a. Mitomycin-treated Ma were loaded with photosensitizer (PS) and mixed with glioma cells, forming hybrid spheroids. F98 spheroids were incubated with supernatants derived from PS-loaded Ma (MaPS). Light treatment (PDT) was administered at various radiant exposures from a 670 nm diode laser. The growth of both types of spheroids was evaluated by measurement of spheroid volume after 14 days in culture. ResultsPDT on F98 cell spheroid cultures, mediated by either free or PS-released from Ma, demonstrated a significant growth inhibition with supernatants harvested after 4 and 24 h. A significant PDT-induced growth inhibition was demonstrated in the MaPS/F98 hybrid spheroid experiments. ConclusionSince the efficacy of PDT, mediated by either free or released photosensitizer was comparable, the uptake and released photosensitizer was not degraded. MaPS, incorporated in hybrid tumor spheroids also mediated effective PDT. These results indicate that Ma have potential as an effective vector for photosensitizer delivery to resected brain tumors.

MODL-03. AN EX VIVO PLATFORM BASED ON ORGANOTYPIC BRAIN SLICE CULTURE FOR INFORMING PERSONALIZED BRAIN CANCER THERAPY

Abstract While the improved classification of CNS tumors is already enhancing the scientific rigor of clinical brain cancer treatment guidelines, the impact of these integrated diagnoses based on histopathological features or molecular insight on precision oncology medicine has yet to demonstrate widespread clinical benefit. Patient tumor-derived cancer models, including patient tumor-derived cell lines, organoids, and explants, have provided practical models based on a patient’s individual tumor for effective therapeutic drugs. Importantly, patient tumor-derived organoids have shown potential to guide personalized care and optimize clinical outcomes by functionally predicting patient response to antitumor drugs prior to in vivo treatment. Our team has built an organotypic brain slice culture (OBSC)-based platform and multi-parametric algorithm that allows for the ex vivo engraftment, rapid treatment, and systemic analysis of resected patient brain tumor tissue. This OBSC platform has successfully supported engraftment of each patient tumor tested to this point, including high- and low-grade adult and pediatric tumor tissue. The established patient tumor-derived organoids show the ability to activate the endogenous astrocytes within OBSCs, which have been reported in brain tumor. Whole exome sequencing analysis showed that patient tumor tissue engrafted onto OBSCs maintained a significant genetic resemblance to their parent tumor, while tumor tissue expanded in vitro displayed a distinctly different DNA profile. Additionally, our algorithm calculates dose-response relationships of both tumor kill and normal brain tissue toxicity, generating summarized drug sensitivity scores based on therapeutic window and allowing us to normalize response profiles across a panel of FDA-approved and exploratory agents. Summarized patient tumor scores after OBSC treatment revealed positive associations to clinical outcomes, suggesting the OBSC platform can provide rapid, accurate, functional testing to ultimately guide patient care.

Intracranial intraoperative radiotherapy (IORT): evaluation of electrocorticography and peri-operative seizure risk.

Intra-operative radiotherapy (IORT) for brain metastases (BMs) and primary brain tumors has emerged as an adjuvant radiation modality that allows for consolidation of care into a single anesthetic episode with surgical resection. Yet, there is a paucity of data regarding the impact that IORT may have on peri-operative and long-term seizure risk. A retrospective analysis of patients receiving IORT during tumor resection was performed via registry including data regarding peri-operative anti-seizure medications and anesthetic agents. Intra-operative neuromonitoring was performed using electrocorticography (ECoG) captured before-, during-, and after-IORT then analyzed for evidence of seizure or significant baseline changes. Kaplan-Meir estimations were used for overall survival analysis relative to documented clinical seizure incidence post-IORT. Of the 24 consecutive patients treated with IORT during tumor resection included, 18 (75%) patients were diagnosed with BMs while 6 (25%) had newly-diagnosed glioblastoma. Mean and median survival times were 487 and 372 days, respectively. Clinical seizures occurred in 3 patients post-IORT, 2 BMs patients within 9 months and 1 glioblastoma patient at 14 months. IORT time represented 9.5% of anesthetic time. ECoG recordings were available for 5 patients (4 BMs; 1 glioblastoma), with mean recording durations of 13% of the total anesthetic time and no evidence of high-frequency oscillations or seizure activity. IORT is an option for delivery of definitive radiation in surgically resected brain tumors without increasing the peri-operative or long-term risk of seizure. ECoG data during the delivery of radiation fail to demonstrate any electrophysiological changes in response to ionizing radiation.

Single-cell molecular profiling using ex vivo functional readouts fuels precision oncology in glioblastoma.

Functional profiling of freshly isolated glioblastoma (GBM) cells is being evaluated as a next-generation method for precision oncology. While promising, its success largely depends on the method to evaluate treatment activity which requires sufficient resolution and specificity. Here, we describe the 'precision oncology by single-cell profiling using ex vivo readouts of functionality' (PROSPERO) assay to evaluate the intrinsic susceptibility of high-grade brain tumor cells to respond to therapy. Different from other assays, PROSPERO extends beyond life/death screening by rapidly evaluating acute molecular drug responses at single-cell resolution. The PROSPERO assay was developed by correlating short-term single-cell molecular signatures using mass cytometry by time-of-flight (CyTOF) to long-term cytotoxicity readouts in representative patient-derived glioblastoma cell cultures (n = 14) that were exposed to radiotherapy and the small-molecule p53/MDM2 inhibitor AMG232. The predictive model was subsequently projected to evaluate drug activity in freshly resected GBM samples from patients (n = 34). Here, PROSPERO revealed an overall limited capacity of tumor cells to respond to therapy, as reflected by the inability to induce key molecular markers upon ex vivo treatment exposure, while retaining proliferative capacity, insights that were validated in patient-derived xenograft (PDX) models. This approach also allowed the investigation of cellular plasticity, which in PDCLs highlighted therapy-induced proneural-to-mesenchymal (PMT) transitions, while in patients' samples this was more heterogeneous. PROSPERO provides a precise way to evaluate therapy efficacy by measuring molecular drug responses using specific biomarker changes in freshly resected brain tumor samples, in addition to providing key functional insights in cellular behavior, which may ultimately complement standard, clinical biomarker evaluations.

Clinical feasibility of miniaturized Lissajous scanning confocal laser endomicroscopy for indocyanine green-enhanced brain tumor diagnosis.

Intraoperative real-time confocal laser endomicroscopy (CLE) is an alternative modality for frozen tissue histology that enables visualization of the cytoarchitecture of living tissues with spatial resolution at the cellular level. We developed a new CLE with a "Lissajous scanning pattern" and conducted a study to identify its feasibility for fluorescence-guided brain tumor diagnosis. Conventional hematoxylin and eosin (H&E) histological images were compared with indocyanine green (ICG)-enhanced CLE images in two settings (1): experimental study with in vitro tumor cells and ex vivo glial tumors of mice, and (2) clinical evaluation with surgically resected human brain tumors. First, CLE images were obtained from cultured U87 and GL261 glioma cells. Then, U87 and GL261 tumor cells were implanted into the mouse brain, and H&E staining was compared with CLE images of normal and tumor tissues ex vivo. To determine the invasion of the normal brain, two types of patient-derived glioma cells (CSC2 and X01) were used for orthotopic intracranial tumor formation and compared using two methods (CLE vs. H&E staining). Second, in human brain tumors, tissue specimens from 69 patients were prospectively obtained after elective surgical resection and were also compared using two methods, namely, CLE and H&E staining. The comparison was performed by an experienced neuropathologist. When ICG was incubated in vitro, U87 and GL261 cell morphologies were well-defined in the CLE images and depended on dimethyl sulfoxide. Ex vivo examination of xenograft glioma tissues revealed dense and heterogeneous glioma cell cores and peritumoral necrosis using both methods. CLE images also detected invasive tumor cell clusters in the normal brain of the patient-derived glioma xenograft model, which corresponded to H&E staining. In human tissue specimens, CLE images effectively visualized the cytoarchitecture of the normal brain and tumors. In addition, pathognomonic microstructures according to tumor subtype were also clearly observed. Interestingly, in gliomas, the cellularity of the tumor and the density of streak-like patterns were significantly associated with tumor grade in the CLE images. Finally, panoramic view reconstruction was successfully conducted for visualizing a gross tissue morphology. In conclusion, the newly developed CLE with Lissajous laser scanning can be a helpful intraoperative device for the diagnosis, detection of tumor-free margins, and maximal safe resection of brain tumors.

Target receptor identification and subsequent treatment of resected brain tumors with encapsulated and engineered allogeneic stem cells

Cellular therapies offer a promising therapeutic strategy for the highly malignant brain tumor, glioblastoma (GBM). However, their clinical translation is limited by the lack of effective target identification and stringent testing in pre-clinical models that replicate standard treatment in GBM patients. In this study, we show the detection of cell surface death receptor (DR) target on CD146-enriched circulating tumor cells (CTC) captured from the blood of mice bearing GBM and patients diagnosed with GBM. Next, we developed allogeneic “off-the-shelf” clinical-grade bifunctional mesenchymal stem cells (MSCBif) expressing DR-targeted ligand and a safety kill switch. We show that biodegradable hydrogel encapsulated MSCBif (EnMSCBif) has a profound therapeutic efficacy in mice bearing patient-derived invasive, primary and recurrent GBM tumors following surgical resection. Activation of the kill switch enhances the efficacy of MSCBif and results in their elimination post-tumor treatment which can be tracked by positron emission tomography (PET) imaging. This study establishes a foundation towards a clinical trial of EnMSCBif in primary and recurrent GBM patients.

To Analyze the Application Value of Perioperative Nursing Care in Patients with Resected Brain Tumor Accompanied with Epileptic Symptoms under Cortical Electrocorticography Monitoring

Objective To explore the application value of perioperative nursing for patients with brain tumors with epilepsy symptoms under the cortical electrocorticography (EEG) monitoring. Methods A total of 86 patients with brain tumor complicated with epilepsy admitted to the department of brain surgery of our hospital from January 2018 to December 2019 were selected as the research objects, and all underwent resection under cortical EEG monitoring. According to different nursing methods, they were divided into the control group and observation group, each with 43 cases. The control group was given perioperative basic nursing, and the observation group was given perioperative comprehensive nursing. The EEG image of the patient during the operation was observed by a portable EEG monitor. Anxiety and depression were assessed by self-rating anxiety scale (SAS) and self-rating depression scale (SDS) scores. The self-made satisfaction questionnaire was used to investigate the nursing satisfaction. A visual analogue (VAS) score is used to assess pain degree. A multiparameter monitor was used to detect the patient's heart rate (HR), systolic blood pressure (SBP), and diastolic blood pressure (DBP). The quality of life was assessed by the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Core 30 (EORTC QLQ-30). The complication rate and recurrence rate were also counted. Results Eighty-six patients with epileptic brain tumor developed spikes in 35 cases, including 7 meningiomas, 22 gliomas, and 6 cholesteatomas; 27 cases of sharp waves, including 14 meningiomas, 12 gliomas, and 1 case of cholesteatomas; and 24 cases of complex wave, including 9 cases of meningioma, 13 cases of glioma, and 2 cases of cholesteatoma. There was no significant difference in the scores of SAS, SDS, VAS, HR, SBP, DBP, and quality of life between the two groups at T0. The VAS score increased at T1 and T2, and the increase in the control group was greater than that in the observation group. At T3 and T4, the SAS, SDS, and VAS scores of the two groups decreased, and the observation group decreased more than the control group. HR, SBP, and DBP of the two groups showed an upward trend at T1 and T2, and the increase in the control group was more significant than that in the observation group. At T3, the three indicators of the two groups decreased, and the observation group decreased more significantly than the control group. At T4, the scores of all indicators of the quality of life of the two groups increased, and the observation group increased more significantly than the control group. The nursing satisfaction of the observation group was higher than that of the control group. The complication rate and recurrence rate in the observation group were decreased compared with the control group. Conclusion Perioperative comprehensive nursing intervention for patients with epileptic brain tumor undergoing resection under cortical EEG monitoring can reduce or even eliminate the recurrence rate of epilepsy, reduce the patient's pain and stress response, and improve the patient's quality of life. It can also reduce the occurrence of complications, improve nursing satisfaction, thereby improving patient compliance, and has a high clinical application value.

Intraoperative Radiotherapy in Brain Malignancies: Indications and Outcomes in Primary and Metastatic Brain Tumors.

Despite the continued controversy over defining an optimal delivery mechanism, the critical role of adjuvant radiation in the management of surgically resected primary and metastatic brain tumors remains one of the universally accepted standards in neuro-oncology. Local disease control still ranks as a significant predictor of survival in both high-grade glioma and treated intracranial metastases with radiation treatment being essential in maximizing tumor control. As with the emergence and eventual acceptance of cranial stereotactic radiosurgery (SRS) following an era dominated by traditional radiotherapy, evidence to support the use of intraoperative radiotherapy (IORT) in brain tumors requiring surgical intervention continues to accumulate. While the clinical trial strategies in treating glioblastoma with IORT involve delivery of a boost of cavitary radiation prior to the planned standard external beam radiation, the use of IORT in metastatic disease offers the potential for dose escalation to the level needed for definitive adjuvant radiation, eliminating the need for additional episodes of care while providing local control equal or superior to that achieved with SRS in a single fraction. In this review, we explore the contemporary clinical data on IORT in the treatment of brain tumors along with a discussion of the unique dosimetric and radiobiological factors inherent in IORT that could account for favorable outcome data beyond those seen in other techniques.

Differential and Common Signatures of miRNA Expression and Methylation in Childhood Central Nervous System Malignancies: An Experimental and Computational Approach.

Simple SummaryEpigenetic mechanisms, that are modifications of the genome without the presence of mutations, are known to play a crucial role in central nervous system (CNS) tumors during childhood. Two well-known epigenetic regulatory mechanisms include methylation and miRNA regulatory mechanisms. Therefore, in the present study we have investigated the presence of methylated genes in childhood CNS tumors, along with miRNA expression. We have searched for correlations between gene methylation and miRNA expression. In addition, we have investigated mRNA expression in order to search for possible miRNA targets. Such approaches could prove useful for the improvement of CNS tumor prognosis, as well as for the discovery of new therapeutic targets.Epigenetic modifications are considered of utmost significance for tumor ontogenesis and progression. Especially, it has been found that miRNA expression, as well as DNA methylation plays a significant role in central nervous system tumors during childhood. A total of 49 resected brain tumors from children were used for further analysis. DNA methylation was identified with methylation-specific MLPA and, in particular, for the tumor suppressor genes CASP8, RASSF1, MGMT, MSH6, GATA5, ATM1, TP53, and CADM1. miRNAs were identified with microarray screening, as well as selected samples, were tested for their mRNA expression levels. CASP8, RASSF1 were the most frequently methylated genes in all tumor samples. Simultaneous methylation of genes manifested significant results with respect to tumor staging, tumor type, and the differentiation of tumor and control samples. There was no significant dependence observed with the methylation of one gene promoter, rather with the simultaneous presence of all detected methylated genes’ promoters. miRNA expression was found to be correlated to gene methylation. Epigenetic regulation appears to be of major importance in tumor progression and pathophysiology, making it an imperative field of study.

An integrated pipeline for comprehensive analysis of immune cells in human brain tumor clinical samples.

Human tissue samples represent an invaluable source of information for the analysis of disease-specific cellular alterations and their variation between different pathologies. In cancer research, advancing a comprehensive understanding of the unique characteristics of individual tumor types and their microenvironment is of considerable importance for clinical translation. However, investigating human brain tumor tissue is challenging due to the often-limited availability of surgical specimens. Here we describe a multimodule integrated pipeline for the processing of freshly resected human brain tumor tissue and matched blood that enables analysis of the tumor microenvironment, with a particular focus on the tumor immune microenvironment (TIME). The protocol maximizes the information yield from limited tissue and includes both the preservation of bulk tissue, which can be performed within 1 h following surgical resection, as well as tissue dissociation for an in-depth characterization of individual TIME cell populations, which typically takes several hours depending on tissue quantity and further downstream processing. We also describe integrated modules for immunofluorescent staining of sectioned tissue, bulk tissue genomic analysis and fluorescence- or magnetic-activated cell sorting of digested tissue for subsequent culture or transcriptomic analysis by RNA sequencing. Applying this pipeline, we have previously described the overall TIME landscape across different human brain malignancies, and were able to delineate disease-specific alterations of tissue-resident versus recruited macrophage populations. This protocol will enable researchers to use this pipeline to address further research questions regarding the tumor microenvironment.

ML-23 The outcome of malignant lymphoma of the central nervous system in a single institution

Background: Although high dose-methotrexate therapy has been performed for primary central nervous system malignant lymphoma (PCNSL), R-MPV (rituximab, methotrexate (MTX), procarbazine and vincristine) therapy is currently the first line therapy for (PCNSL) in our hospital. This study examines the results of R-MPV therapy comparing with past treatment. Method/Subjects: Thirty-seven patients treated at our hospital from 2009 to 2020 were included. Overall survival time, progression free survival time, and toxicities were evaluated. Results: The average age of patients was 65.7 years. Patients included 21 males and 16 females. Thirty-six patients were diagnosed DLBCL by resected brain tumor tissues, and one was diagnosed DLBCL by vitreous biopsy. As initial treatment, rituximab±HD-MTX therapy (R±MTX group) was performed in 20 cases, HD-MTX therapy plus radiation (R±MTX+RT group) was performed in 12 cases, and RMPV therapy was performed in 5 cases (R-MPV group). Median OS of all cases was 69 months and median PFS was 38 months. Median OS was 69 months in R±MTX group and could not be calculated in R±MTX+RT, and R-MPV groups. Median PFS was 16 months and 56 months in R±MTX group and R±MTX+RT, respectively, and could not be calculated in the R-MPV group. Although the R-MPV group had a short follow-up period, the results were considered to be comparable to those of the R±MTX+RT group. On the other hand, grade 3/4 adverse events occurred in 50%, 25%, and 100%, respectively. Conclusion: R-MPV therapy may delay the timing of radiation and reduce the amount of radiation. On the other hand, the frequency of adverse events is high, and more strict management of treatment is required.

PATH-25. EXPERIENCE WITH AN RNA FUSION TRANSCRIPT PANEL FOR DETECTION OF POTENTIAL THERAPEUTIC TARGETS IN GLIOMAS

Abstract Next-generation sequencing to identify fusion proteins is increasingly employed across oncology to identify therapeutic targets.1 The clinical relevance of detecting fusion transcripts is well described in the pediatric glioma population, but similar reports for adult patients are scant.2 The University of Pennsylvania Health System (UPHS) has implemented routine use of an RNA fusion transcript panel (ArcherDX, Boulder, CO) on resected brain tumors since August 2017. Here we report the results of this analysis for adult patients with gliomas and highlight potentially targetable fusions. Over the period of August 2017 through December 2019, fusion analysis was performed on resected gliomas of over 200 patients. Ninety-seven patients were found to have a detected fusion protein. Eighty-three of the 97 patients (86%) had glioblastoma and 14 (14%) had lower grade gliomas. A total of 26 unique fusions were found. The most common (n=55) was EGFRvIII. NTRK fusions were of special interest as FDA-approved agents are available for patients harboring this genetic alteration.3 We identified 8 patients (8%) with NTRK fusions including ARHGEFF2:NTRK1, BNA: NTRK1, BCR: NTRK2, PDE5A/NTRK2, SKAP2/NTRK2, and STRN: NTRK2. Several of these patients went on to receive TRK kinase inhibitors with clinical benefit. Of the 97 patients with a detected fusion, 24 (25%) were found to have a potentially targetable fusion other than EGFRvIII, with inhibitors available in clinical trials or as off-label therapy. These fusions included BRAF (n=5; BRAF: LHFPL3, KIAA1549:BRAF), FGFR (n=9; FGFR3:BRAP, FGFR3:RENBP, FGFR3:TACC3), MET (n=7; CAPZA2-MET, KLF12:MET, PTPRZ1:MET, ST7:MET), and ROS1 (n=3; DLL: ROS1, GOPC: ROS1). In sum, routine clinical use of an RNA-based fusion transcript panel for adult patients with glioma may allow for detection of therapeutically targetable alterations in a meaningful proportion of cases. Prospective trials are needed to determine whether targeting specific fusions is beneficial for adult patients with glioma.

RADT-47. A MULTICENTER OBSERVATIONAL STUDY OF SURGICALLY TARGETED RADIATION THERAPY (START) USING IMPLANTED CS-131 SEEDS IN A COLLAGEN-BASED CARRIER TILE IN INTRACRANIAL BRAIN NEOPLASMS - PROTOCOL IN PROGRESS

Abstract INTRODUCTION Post-resection radiotherapy (RT) is the most effective adjuvant treatment for brain tumors. However, there is no current consensus as to the “best” type of post-resection RT, either at diagnosis or recurrence. The use of internally placed radiation (brachytherapy) allows immediate initiation of RT when residual tumor burden is minimal, which theoretically should lessen the risk of recurrence. Brachytherapy placement intraoperatively allows more precise identification of the tumor margins than by postoperative imaging. Traditional brachytherapy methods have several drawbacks, including uneven dose distribution, long operating room times, a need for expensive equipment, and/or frequent adverse events (AE). To address these issues, a device with Cs-131 radiation seeds in a resorbable collagen-based carrier tile (GammaTile, GT Medical Technologies, Tempe AZ) was developed and is described as Surgically Targeted Radiation Therapy or STaRT. The device has demonstrated excellent safety and local control in early commercial use. OBJECTIVE The objectives of this registry study are to evaluate real-world clinical outcomes and patient reported outcomes that measure the effectiveness and safety of STaRT. METHOD Patients (N=600) with surgically resected (R) brain tumors of any pathology who have undergone STaRT are eligible. Accrual to start at 20+ sites in Q3 2020. Data collected includes local control, overall survival, QOL, neurocognition, functional decline, and surgical and radiation associated AE’s. Data will be collected at 1, 3, 6, 9, and 12 months, then every 6 months through 5 years. RESULT Data will be used to benchmark clinical outcomes of STaRT therapy and allow for comparisons to existing standard-of-care treatments. CONCLUSION This will be the first observational registry study of R+STaRT, delivered by Cs-131 sources in permanently implanted resorbable collagen tile carriers. The outcome measures captured will allow for evaluation of the potential risks and benefits of this treatment approach for patients in a real-world setting.

Analysis of key clinical features for achieving complete remission in stage III and IV non-small cell lung cancer patients

BackgroundAlthough development of immune checkpoint inhibitors and various molecular target agents has extended overall survival time (OS) in advanced non-small cell lung cancer (NSCLC), a complete cure remains rare. We aimed to identify features and treatment modalities of complete remission (CR) cases in stages III and IV NSCLC by analyzing long-term survivors whose OS exceeded 3 years.MethodsFrom our hospital database, 1,699 patients, registered as lung cancer between 1st Mar 2004 and 30th Apr 2011, were retrospectively examined. Stage III or IV histologically or cytologically confirmed NSCLC patients with chemotherapy initiated during this period were enrolled. A Cox proportion hazards regression model was used. Data collection was closed on 13th Feb 2017.ResultsThere were 164 stage III and 279 stage IV patients, including 37 (22.6%) and 51 (18.3%) long-term survivors and 12 (7.3%) and 5 (1.8%) CR patients, respectively. The long-term survivors were divided into three groups: 3 ≤ OS < 5 years, 5 years ≤ OS with tumor, and 5 years ≤ OS without tumor (CR). The median OS of these groups were 1,405, 2,238, and 2,876 days in stage III and 1,368, 2,503, and 2,643 days in stage IV, respectively. The mean chemotherapy cycle numbers were 16, 20, and 10 in stage III and 24, 25, and 5 in stage IV, respectively. In the stage III CR group, all patients received chemoradiation, all oligometastases were controlled by radiation, and none had brain metastases. Compared with non-CR patients, the stage IV CR patients had smaller primary tumors and fewer metastases, which were independent prognostic factors for OS among long-term survivors. The 80% stage IV CR patients received radiation or surgery for controlling primary tumors, and the surgery rate for oligometastases was high. Pathological findings in the stage IV CR patients revealed that numerous inflammatory cells existed around and inside resected lung and brain tumors, indicating strong immune response.ConclusionsMultiple line chemotherapies with primary and oligometastatic controls by surgery and/or radiation might achieve cure in certain advanced NSCLC. Cure strategies must be changed according to stage III or IV.This study was retrospectively registered on 16th Jun 2019 in UMIN Clinical Trials Registry (number UMIN000037078).

Abstract 3103: Intraparenchymal delivery of chemokines and immunomodulators to eliminate pediatric brain tumor cells

Abstract Pediatric brain tumors are among the leading causes of cancer-related death in children. These malignancies tend to occur in locations of the brain where surgery and radiation can permanently impair a patient’s quality of life. Migratory cells from high grade brain tumors can invade nearby, inaccessible areas of the brain where they may grow unchecked and ultimately lead to patient death. This project seeks to tailor the microenvironment around the tumor cavity to promote the recruitment and elimination of remnant brain tumor cells by microglia and macrophages found in the brain. Our data suggests gradients of classical immune cell chemokines, like CCL2, are also potent chemotactic signals for a variety of patient-derived brain tumor types. Monoclonal antibody blockade of CD47, a cell-surface “don’t eat me” ligand often over-expressed on tumor cells, is effective at promoting the elimination of tumor cells in close-proximity to murine macrophages in vitro. We engineered user-programable hydrogel depots capable of month-long molecule release and implanted them into tumor-bearing mouse brains. Hydrogels incorporated with CCL2 and CD47mAb demonstrated statistically significant co-recruitment of tumor and immune cells and evidence of macrophage-mediated tumor cell death compared to PBS-incorporated gels. These results suggest proper stimulation of immune cells within the brain could be an effective means to eliminate pediatric brain tumor cells without causing structural damage to vital nervous tissues. Our data may be the first steps towards clinical trials for children with incompletely resected brain tumors. Citation Format: Eric S. Nealy, Cole A. DeForest, James Olson. Intraparenchymal delivery of chemokines and immunomodulators to eliminate pediatric brain tumor cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3103.

Selective enrichment of CD133+/SOX2+ glioblastoma stem cells via adherent culture.

Most of the brain tumors are malignant with an extremely poor survival rate. Recent progress in identifying cancer stem cells (CSCs) within the brain tumors is starting to revolutionize our understanding in the imitation and progression of tumors as well as relapse and the development of therapeutic strategies. Suspension spheroid body culture paradigm is a routine method in enriching CSCs. While, it was reported recently that CSCs within the brain tumor may also be enriched through adherent monolayer culture with optimized properties. In the present study, 18 surgically resected brain tumors were used for analyzing the feasibility of adherent enrichment of CSCs. The results indicated that 50% of glioblastomas were able to generate adherent CSCs, which were uniformly positive for Sox2, CD133, GFAP and Nestin. However, adherent culture paradigm failed to yield CSCs in secondary brain tumors, including neurocytomas, ependymomas, germ cell tumors or low-grade astrocytomas, which is most likely due to a lack of CD133+/Sox2+ cells within the original biopsies. Therefore, it was concluded that the adherent culture paradigm may serve as a reliable method in enriching brain CSCs, but this method is more suitable for enriching CD133+/Sox2+ CSCs in glioblastomas.