tbuckley/cabot-search huggingface dataset:
DNAR-14. MODULATING POPULATIONAL VARIANCE OF METHYL-GUANINE METHYL TRANSFERASE (MGMT) EXPRESSION THROUGH MICRORNA DEGRADATION: A NOVEL MECHANISM OF TEMOZOLOMIDE RESISTANCE
Authors: Gatikrushna Singh, Valya Ramakrishnan, Shilpi Singh, Beibei Xu, Johnny Akers, Tao Jiang, Hua Wei, Mao Ying, Clark Chen
Journal: Neuro-Oncology (2024)

Abstract O6 methyl-guanine methyltransferase (MGMT) restores alkylated DNA to its undamaged form in a stochiometric manner to prevent the cytotoxic effects of temozolomide (TMZ), a DNA alkylating agent used as a standard-of-care treatment for glioblastomas. We previously demonstrated that he microRNA, miR-181d, post-transcriptionally repressed MGMT expression. Here, we show that treatment of glioblastoma cells with TMZ induced a feed-forward cascade resulting in an ataxia telangiectasia and Rad3 (ATR) and polyribonucleotide nucleotidyl transferase 1 (PNPT1)-dependent degradation of miR-181d. Single-cell analyses revealed such miR-181d degradation induced an: 1) increased mean level of MGMT expression and 2) widened the variance in MGMT expression in the cell population. While the former is known to confer increased population fitness to temozolomide, the importance of the latter is unknown. By mixing cultures derived from isogenic glioblastoma subclones with distinct MGMT expression levels, we generated glioblastoma cell populations with comparable mean MGMT expression levels while differing in the populational variance in MGMT expression (classified as “wide” or “narrow”). Despite comparable mean levels of MGMT expression, the glioblastoma population with wide variance exhibited increased temozolomide resistance relative to the population with the narrow variance, in vitro and in vivo. Transfection of miR-181d into the wide-variance population narrows the variance of MGMT expression and restores TMZ sensitivity to levels comparable to that observed in miR-181d transfected narrow-variance populations. These findings suggest that TMZ-induced miR-181d degradation enhanced TMZ resistance through modulation of both the mean and variance of MGMT expression, mechanisms which may be extrapolated to microRNA biology in general.
EXTH-47. ENHANCING GD2.CART THERAPY FOR DIFFUSE MIDLINE GLIOMA WITH LSD1 AND HDAC INHIBITORS
Authors: Rebecca Murdaugh, Meghan Shekar, Brittany Eberl, Jack Tremblay, Rosemary Richard, Akdes Serin Harmanci, Bilal Omer, Jamie Anastas
Journal: Neuro-Oncology (2024)

Abstract Chimeric antigen receptor T cells against the glycolipid GD2 (GD2.CARTs) are showing promise in diffuse midline glioma (DMG) but are not yet curative. Since low target antigen expression is one potential mechanism by which tumor cells can escape CART therapy, we profiled GD2 expression levels on 9 different H3K27M-mutant DMG cell lines using flow cytometry. This analysis shows that only 5 of the 9 cell lines exhibit high GD2 expression while the remaining 4 lines have low GD2-expressing cells. When treating these cell lines with GD2.CARTs in co-culture assays and xenograft mice, we find that low GD2 expression on DMG cells correlates with tumor cell escape from GD2.CARTs and therapeutic resistance in vivo. Our lab previously found that simultaneous inhibition of histone deacetylases (HDACs) and lysine-demethylase 1 (LSD1) in DMG cells causes synergistic increases in gene expression and tumor cell death. Previous studies in neuroblastoma also demonstrate that HDAC inhibitor (HDACi) treatment can increase GD2 on tumor cells and improve targeting by GD2.CARTs. We therefore decided to assess whether treating GD2-low DMG cell lines with combinations of LSD1 inhibitors (LSD1i) and HDACi improves DMG response to GD2.CARTs. Immunofluorescence and flow cytometric analyses show that GD2 expression is increased on LSD1i+HDACi-treated GD2-low DMG cells and that there is enhanced tumor cell targeting by GD2.CARTs in subsequent co-culture assays. Treating mice transplanted with GD2-low DMG cells with LSD1i+HDACi followed by intravenous GD2.CART infusion also led to reduced tumor growth. These results suggest that LSD1i+HDACi pre-treatment may provide a way to improve DMG patient responses to GD2.CART therapy by increasing target antigen expression.
DDDR-38. TRANSLATIONAL STEPS OF THE ANTITUMOR PEPTIDE TAT-CX43266-283 AS A TREATMENT FOR GLIOBLASTOMA: EGFR AS A TREATMENT RESPONSE BIOMARKER AND RESULTS OF COMBINATION THERAPY IN A PRECLINICAL RESECTION MODEL
Authors: Andrea Álvarez-Vázquez, Josephine Volovetz, Laura San-Segundo, Pilar Cerveró-García, Raquel Flores-Hernández, Claudia Ollauri-Ibáñez, Berta Segura-Collar, Christopher G Hubert, Pilar Sánchez-Gómez, Steven M Pollard, Justin D Lathia, Arantxa Tabernero
Journal: Neuro-Oncology (2024)

Abstract Glioblastomas (GBM) are the most malignant primary brain tumors, and they remain incurable. Despite the current standard of care (surgical resection of the tumor and administration of chemotherapy and radiotherapy) some GBM stem cells (GSCs) remain in the brain parenchyma causing tumor recurrence. The Src-inhibitory peptide TAT-Cx43266-283 has shown promising antitumor results in GBM preclinical models, reducing GSC viability and increasing survival in GBM-bearing mice. Here we have investigated some of the main gaps to overcome when translating preclinical results to the clinic, to promote the progress of TAT-Cx43266-283 as a clinical therapy to fight GBM. First, we investigated biomarkers of treatment response to design a more targeted therapy. We assessed cell viability after treatment with TAT-Cx43266-283 in 13 patient-derived GSC lines and we found a stronger treatment response in those GSCs that had alterations in the Epidermal Growth Factor Receptor (EGFR). This was further confirmed in several murine GBM lines. Importantly, we found that treatment with TAT-Cx43266-283 was more effective in vitro than temozolomide or the classical EGFR inhibitor, erlotinib. Moreover, we showed that EGFR participates in TAT-Cx43266-283 response together with Src, by decreasing EGFR and EGFRvIII activity in some GSCs and increasing survival in mice bearing tumors with EGFR alterations. Next, we studied the effect of TAT-Cx43266-283 in a clinical context by administering it in a murine model of tumor resection. We analyzed the histopathology of this GBM model, uncovering histological features typical of human GBM. We found that resection alone improved, although not significantly, GBM-bearing mice survival. However, tumors that regrew after resection exhibited more aggressive features. Importantly, the combination of tumor resection and TAT-Cx43266-283 achieved better survival outcomes and showed reduced invasive features. Altogether, these results serve as a base for future clinical investigations and support the therapeutic potential of TAT-Cx43266-283 as a treatment for GBM.
RADT-47. CLINICAL OUTCOMES AFTER SURGICAL RESECTION OF BRAIN METASTASES IN SMALL CELL LUNG CANCER PATIENTS
Authors: Tanya Qureshi, Andrew Zureick, Neal McCall, Tyler Wilhite, Christopher Wilke, Timothy Burns, Costas Hadjipanayis, Steven Burton, Serah Choi
Journal: Neuro-Oncology (2024)

Abstract Small cell lung cancer (SCLC) has a high propensity to metastasize to the brain. Radiotherapy is the primary treatment for SCLC brain metastases. Whole brain radiotherapy (WBRT) has been the standard of care, but recent studies show similar overall survival (OS) in patients treated with upfront stereotactic radiosurgery (SRS). Surgery does not typically have a role in SCLC although it can provide relief of neurologic symptoms and pathologic diagnosis. We sought to determine the clinical outcomes of patients who underwent surgical resection of SCLC brain metastases. A retrospective chart review of SCLC patients treated at UPMC from 2010 – 2022 was performed. OS after resection was estimated using the Kaplan-Meier method with log-rank test. 4,213 patients were diagnosed with SCLC, of which 715 patients (17%) had synchronous brain metastases at initial diagnosis. Forty patients underwent resection of SCLC brain metastases, all of whom were symptomatic. The median diameter of the resected brain metastases was 3.8 cm (range 1.7 – 8 cm). Seventy-five percent (n=30) had resection of synchronous brain metastases and 25% (n=10) had resection of metachronous brain metastases. Median OS for the surgical cohort was 13.6 months (interquartile range (IQR), 3.4 – 21.9 months). Patients with metachronous and synchronous brain metastases had median OS of 6.8 months (IQR, 2.8 – 24.6 months) and 14.3 months (IQR, 3.6 – 20.4), respectively. Of patients with synchronous brain metastases (n=30), 53% (n=16) received post-operative WBRT, 40% (n=11) received post-operative SRS and 10% (n=3) died within 7 weeks of surgery. Median OS of patients with synchronous brain metastases treated with WBRT and SRS were 11.9 months (IQR, 3.8 – 21.7) and 19.0 months (IQR, 14.6 – 30.3), respectively, and the difference was not statistically significant (p=0.53). Surgery for SCLC brain metastases is uncommon. Patients who received SRS versus WBRT post-operatively for synchronous brain metastases had no difference in OS.
CSIG-05. IS THERE ANY BRAIN TUMOR PREDISPOSITION IN RELATED PALLISTER-HALL SYNDROMES AT THE NEW GENOMICS ERA
Authors: Nouha Bouayed Abdelmoula, Sonda Kammoun, Mona Rekik, Saloua Ben Amor, Mzid Abid Fatma, Sahla Sellami, Mariem Sehli, Aymen Ben Mrad, Karim Chaabouni, Amira Trigui
Journal: Neuro-Oncology (2024)

Abstract Pallister-Hall Syndrome (PHS) and its related syndromes are a spectrum of congenital malformations. They are associated to GLI3 mutations and specific brain tumors. Considered as lethal, it is now well established that this disease may be miss-diagnosed with the report of adult cases. Here, we discuss the management of the genetic counselling and the risk of neurologic tumor predisposition in GLI3-related PHS. We comprehensively reviewed the scientific literature using various databases to explore the risk of neurologic tumors and evolving practice of neuro-cancer genetic counseling in GLI3-related PHS. The review of literature showed that GLI3 is involved in tissue development as well as in cancer. GLI3 was identified as either a pro or anti-cancerous protein. In fact, GLI3 is described as upregulated in multiple cancers and is found to positively regulate malignant behavior. In neuro-oncology GLI gene was first identified as a highly expressed gene in human glioma and then as having an anti-cancerous role in medulloblastoma where GLI3 seems act as a tumor suppressor. In mutational studies, GLI3-germinal mutations are characterized by a high recurrence of hypothalamic hamartoma in syndromic patients. GLI3-somatic alterations have been also demonstrated in cell samples of patients with non-syndromic hypothalamic hamartoma. In addition, while inactivation of GLI3 is suggested to be associated with medulloblastoma, mutations are not common in sporadic medulloblastoma. The association of germinal GLI3 variants in syndromic patients with medulloblastoma has been identified in only one patient harboring GLI3 H302X variant. Our review permitted us to conclude that germline GLI3 mutations may predispose to a specific non-severe form of delayed hypothalamic hamartoma, which can be revealed in pauci or asymptomatic and unrecognized mutated individuals. The likelihood of having a neuro-cancer predisposition in GLI3 mutated families seems to be insignificant.
RADT-05. VASCULAR OVERLAP PROVIDES PROTECTION FROM GAMMA-KNIFE-INDUCED RADIATION NECROSIS IN A METASTATIC BRAIN TUMOR COHORT
Authors: Chandler Berke, Maxon Knott, Jordan Spatz, Michael Silva, Adham Khalafallah, Alessandro Valderrama, Tejan Diwanji, Ricardo Komotar, Michael Ivan, Benjamin Rich, Carolina Benjamin
Journal: Neuro-Oncology (2024)

Abstract INTRODUCTION Radiation necrosis (RN) is a long-term complication of Gamma-Knife (GK) Radiosurgery, an established treatment for metastatic brain tumors. Few dosimetric parameters have shown to predict RN, including tumor target volume, treatment dose, and V12 Gy (volume of normal brain receiving 12 Gy). Vascularity has yet to be explored as an independent predictor of RN. OBJECTIVE To evaluate the role of vascular overlap in GK-induced RN. METHODS All metastatic brain tumor patients treated with GK between 2014-2019 were retrospectively screened for post-treatment radiographic RN. Vascular overlap, defined by the MCA-ACA and MCA-PCA border regions, was determined by two blinded neurosurgeons and one radiation oncologist. Multivariate logistic regression analysis was performed to determine factors predictive of RN using variables determined significant by univariate analysis and clinical relevance. Covariates included V12 as a binary variable (≥8 vs. &amp;lt;8 cm3), vascular overlap, supratentorial location, and eloquent location. RESULTS 6% (20/321) of all metastatic brain tumor patients developed RN and were included for analysis, with the final cohort being 60% (12/20) female with a mean age of 59 years, comprising 77 lesions. V12 (≥8 cm3) showed a significant increase in risk of developing RN [OR = 8.18; (coef, 95% CI: 2.10 (0.49, 3.72), p=0.011)]. Conversely, vascular overlap showed a protective effect against RN [OR = 0.23 (-1.49 (-2.79, -0.19), p=0.024)], with a lower rate of RN in areas of vascular overlap (10%) than non-vascular overlap (26%). Neither supratentorial location [OR = 3.31 (1.20 (-0.76, 3.16), p=0.231)] nor location within eloquent brain [OR = 0.96 (-0.04 (-1.48, 1.39), p=0.95)] showed significance. CONCLUSION For the first time, we show that patients with metastatic brain lesions in anatomical regions of vascular overlap treated with GK are less likely to develop RN. Future work should validate these findings with the goal of optimizing radiation dosing to mitigate RN incidence and recurrence rates.
DNAR-11. INHIBITION OF RAD52 ACTIVITY INDUCES DNA DAMAGE BY ACCUMULATING R-LOOPS IN DIFFUSE MIDLINE GLIOMA
Authors: Eita Uchida, Yukitomo Ishi, Jun Watanabe, Savneet Kaur, Kentaro Mineji, Hiam Abdala-Valencia, Benjamin Singer, Samantha Gadd, Rintaro Hashizume
Journal: Neuro-Oncology (2024)

Abstract Diffuse midline glioma (DMG) is one of the most devastating childhood cancers with a median survival of &amp;lt; 1year from diagnosis. There is a critical need for new therapeutics for improving treatment outcomes for DMG patients. We performed genome-wide CRISPR/Cas9 screening and identified RAD52 as a potential therapeutic target in DMG cells. RAD52 inhibition, using shRNA-mediated RAD52 depletion and treatment with RAD52 inhibitor, D-I03, suppressed DMG cell proliferation. Western blotting revealed that RAD52 inhibition increased DNA double-starand breaks (DSBs) marker γH2AX while it decreased repair markers BRCA1 and RAD51. Also, RAD52 inhibition causes a sustained level of phosphorylated RAD50 and γH2AX in irradiated DMG cells over 24 hours. Immunocytochemistry (ICC) of γH2AX and repair marker 53BP1 showed that RAD52 inhibition sustained DNA damage with high levels of γH2AX at 24 hours following radiation while the level of 53BPI was decreased, thereby inhibiting DNA DSB repair. DNA repair assay showed that RAD52 inhibition suppressed DNA DSB repair through a homologous recombination pathway. RNA sequencing showed that RAD52 inhibition downregulated genes associated with the DNA repair pathway. Importantly, RAD52 inhibition increased the radiosensitivity of DMG cells. To understand the mechanism of RAD52 inhibition on DNA damage, we performed dot plot assay and ICC of S9.6 which recognizes DNA-RNA hybrids (also known as R-loops) and found accumulation of R-loop formation in DMG cells treated with RAD52 inhibitor. In addition, RAD52 inhibition decreased the expression of RNA polymerase II. Finally, the combination therapy of RAD52 inhibitor and radiation inhibited tumor growth and increased survival of mice bearing DMG patient-derived xenografts, outperforming either monotherapy. Together, our results highlight that RAD52 inhibition induces DNA damage by accumulating R-loops, results in reducing DMG cell proliferation, while also increase DMG radiosensitivty, and providing a rationale for developing combination therapy with radiation for the treatment of DMG.
EXTH-50. THYROID HORMONE-INDUCED DIFFERENTIATION: A PROMISING THERAPEUTIC STRATEGY FOR MEDULLOBLASTOMA
Authors: Yijun Yang, Silvia Valdes-Rives, Rebecca Ronsley, Sarah Leary, Robert Wechsler-Reya, Zeng-jie Yang
Journal: Neuro-Oncology (2024)

Abstract Medulloblastoma (MB) is the most common malignant brain tumor in children, consisting of four major subgroups (WNT, SHH, Group 3, and Group 4) that differ in genetic/epigenetic profiles and prognoses. Despite current therapy, a significant proportion of patients still succumb to MB. Moreover, survivors often suffer severe side effects from aggressive treatments. Therefore, improved strategies to treat MB are urgently needed. MB tumor cells retain the capacity for differentiation and can undergo terminal differentiation, after which they lose their proliferative and tumorigenic capacity. This suggests that MB can potentially be treated by inducing tumor cell differentiation. However, the mechanisms underlying MB tumor cell differentiation remain unclear. Our recent studies reveal that thyroid hormone (TH) plays a critical role in promoting tumor cell differentiation in MB. Reduced TH levels free the TH receptor, TRα1, to bind to EZH2 and repress the expression of NeuroD1, a transcription factor that drives tumor cell differentiation. Increased TH levels reverse the EZH2-mediated repression of NeuroD1 by disrupting the binding between EZH2 and TRα1, thereby stimulating tumor cell differentiation and reducing MB growth. Importantly, triiodothyronine (T3, active form of TH) inhibits the growth of both SHH- and Group 3 tumors, suggesting that the tumor-inhibitory effect of T3 is not restricted by MB subgroups. Additionally, this effect is significantly enhanced by concurrent chemotherapy. These findings establish an unprecedented association between TH signaling and MB pathogenicity, providing solid evidence for TH as a promising therapeutic modality for MB treatment.
IMMU-02. INTRACRANIAL PROGRESSION IS LESS COMMON IN PATIENTS WITH ADVANCED NSCLC RECEIVING CANCER IMMUNOTHERAPY
Authors: Naoya Kemmotsu, Kiichiro Ninomiya, Yoshihiro Otani, Hiroyuki Michiue, Shota Tanaka, Yosuke Togashi
Journal: Neuro-Oncology (2024)

Abstract BACKGROUND Intracranial metastases are common in patients with non-small cell lung cancer (NSCLC) and their prognosis is very poor. Furthermore, intracranial progression is common during systemic therapy due to the inability to cross the blood brain barrier, but the impact of cancer immunotherapy on intracranial progression remains unclear. METHODS We analyzed clinical data to evaluate the frequency of intracranial progression in patients with advanced NSCLC treated with PD-1 blockade therapies compared to patients not treated with PD-1 blockade therapies (Approval number: 2201-022). We also evaluated durable responses to PD-1 blockade and analyzed tumor-infiltrating lymphocytes using tumor-rechallenging murine models. RESULTS The clinical data analysis showed that the frequency of intracranial progression was significantly lower in patients with advanced NSCLC treated with PD-1 blockade than in patients treated with cytotoxic chemotherapy. In murine models, intracranial rechallenged tumors after initial rejection by PD-1 blockade therapy were suppressed, as observed for subcutaneous tumors. Accordingly, PD-1 blockade increased long-lived memory precursor effector T cells and antigen-specific T cells in intracranial lesions. In contrast, intracranial rechallenged different tumors were not suppressed. CONCLUSIONS The CNS has been considered a site in which cancer patients tend to experience progression during systemic therapies, however our results indicate that cancer immunotherapies can prevent intracranial progression, maintaining long-term effects intracranially as well as systemically. (Kemmotsu N. et. al., Int J Cancer, 2024)
IMMU-27. INHIBITION OF THE EXTRACELLULAR MATRIX PROTEIN EFEMP1/FIBULIN-3 REDUCES IMMUNOSUPPRESIVE SIGNALING IN TUMOR STEM CELLS AND INCREASES MACROPHAGE ACTIVATION AGAINST GLIOBLASTOMA
Authors: Somanath Kundu, Soham Mitra, Roshini Arivazhagan, John Longo, Sharon Longo, Abigail Venskus, Harish Babu, Mariano Viapiano
Journal: Neuro-Oncology (2024)

Abstract Glioblastoma tumors remain a formidable challenge for immune-based treatments because of their molecular heterogeneity, poor immunogenicity, and growth in the largely isolated and immunosuppresive neural environment. As the tumor grows, GBM cells change the composition and architecture of the neural extracellular matrix (ECM), affecting the mobility, survival, and function of immune cells such as tumor-associated microglia and infiltrated macrophages (TAMs). We have previously described the unique expression of the ECM protein EFEMP1/fibulin-3 in GBM compared to normal brain and demonstrated that this secreted protein promotes growth and resistance of the GBM stem cell (GSC) population. Here, we describe a novel immunomodulatory role of fibulin-3 and the immuno-boosting effects of targeting this ECM protein. Mice carrying fibulin-3-deficient intracranial tumors showed increased myeloid infiltration and reduced expression of TAM pro-tumoral markers (Arginase, CD206) compared to controls. The opposite was observed in orthotopic tumors overexpressing fibulin-3. In silico dataset analysis revealed positive correlation of fibulin-3 with an immunosuppresive signature in GBM, which was validated in GBM stem cells (GSCs). Accordingly, expression of fibulin-3 by GSCs promoted anti-inflammatory polarization of co-cultured macrophages. We further demonstrated that fibulin-3 regulated the expression of immunosuppresive signals (CSF-1, TGFbeta) and the innate immune checkpoint CD47 in GSCs via autocrine activation of NF-kB signaling. Immunosuppresive signals in GSCs were downregulated by knockdown of fibulin-3 or inhibition of this protein with an anti-fibulin-3 antibody (mAb428.2). Genetic or antibody-mediated targeting of fibulin-3 in GSCs co-cultured with macrophages (U937 and THP1 lines) increased macrophage phagocytosis and reduced the viability of the tumor cells. Furthermore, local delivery of mAb428.2 in mice carrying intracranial GBM resulted in increased infiltration of TAMs expressing pro-inflammatory markers and reducing tumor viability. Our findings show that anti-fibulin-3 approaches, which impact the tumor ECM, can diminish immunosuppression in GBM and boost innate immune responses against the tumor.