Primary Malignant Tumors Research Articles

UK guidelines for the management of bone sarcomas.

This document is an update of the British Sarcoma Group guidelines (2016) and provides a reference standard for the clinical care of UK patients with primary malignant bone tumours (PMBT) and giant cell tumours (GCTB) of bone. The guidelines recommend treatments that are effective and should be available in the UK, and support decisions about management and service delivery. The document represents a consensus amongst British Sarcoma Group members in 2024. Key recommendations are that bone pain, or a palpable mass should always lead to further investigation and that patients with clinical or radiological findings suggestive of a primary bone tumour at any anatomic site should be referred to a specialist centre and managed by an accredited bone sarcoma multidisciplinary team. Treatment recommendations are provided for the major tumour types and for localised, metastatic and recurrent disease. Follow-up schedules are suggested.

Glioblastoma and its interaction with neurogenesis

Glioblastoma (GBM) is the most frequent and aggressive malignant primary tumor of the central nervous system in adults, with an incidence of 3.23 per 100,000 people. Despite the existence of various therapeutic approaches, the absence of a cure and the unfavorable prognosis persist for this neoplasm, with a median survival of approximately 8-15 months and a 5-year survival rate of 6.9%. In this review, we address the epidemiology, histopathology, molecular characteristics, and treatment of GBM. We highlight the relationship of GBM with the microenvironment in the lateral ventricle wall and the cerebrospinal fluid. The location of GBM in this region results in more aggressive tumors and shorter life expectancy for patients. Understanding the malignancy mechanisms that hinder remission, treatment, and positive prognosis opens the possibility of improving diagnostic and therapeutic interventions against GBM.

Amantadine against glioma via ROS-mediated apoptosis and autophagy arrest.

Glioma is a common primary nervous system malignant tumor with poor overall cure rate and low survival rate, yet successful treatment still remains a challenge. Here, we demonstrated that amantadine (AMT) exhibits the powerful anti-glioma effect by promoting apoptosis and autophagy in vivo and in vitro. Mechanistically, amantadine induces a large amount of reactive oxygen species (ROS) accumulation in glioma cells, and then triggers apoptosis by destroying mitochondria. In addition, amantadine induces the initiation of autophagy and inhibits the fusion of autophagosome and lysosome, consequently performing an anti-glioma role. Taken together, our findings suggest that amantadine could be a promising anti-glioma drug that inhibits glioma cells by inducing apoptosis and autophagy, which may provide a novel potential treatment option for patients.

The outcomes of children with primary malignant renal tumors: a 14-year single-center experience.

Wilms tumor (WT) is the most common malignant renal tumor in children. This study investigated the clinical features, pathological findings, and outcomes of children with malignant renal tumors in Southern Iran. Factors associated with recurrence and mortality were assessed. Electronic files of children with malignant renal tumors from 2009 to 2023 were reviewed. The 5-year overall survival (OS) and event-free survival (EFS) were reported. Eighty-three patients (44 males) with a median age of 40 months (range: 3-122) were included. WT was the most common pathological variant (94%). Anaplasia was found in 17.3% of patients. Upfront chemotherapy followed by nephrectomy was performed in 54.2% of the patients. Ten patients (12%) experienced relapse, and five patients (6%) died during the 14-year follow-up. The 5-year OS and EFS were 90.75% (95% CI, 78.64-96.16%) and 81.9% (95% CI, 70.10-89.38%), respectively, and were comparable between the two treatment strategies (upfront chemotherapy vs. upfront nephrectomy). Metastasis and residual disease were associated with relapse, whereas tumor recurrence was the only predictive factor of survival. WT is a curable disease with excellent outcomes if diagnosed and treated promptly. The timing of nephrectomy does not affect OS and EFS. Patients with low-stage tumors and those with complete surgical excision are at a lower risk of tumor recurrence. Relapse is the primary risk factor for death.

PATH-06. TRANSLATION INTO CLINICAL PRACTICE OF THE G1-G7 MOLECULAR SUBGROUP CLASSIFICATION OF GLIOBLASTOMA

Abstract Glioblastoma is the most frequent and malignant primary brain neoplasm. Glioblastoma growth is promoted by alterations in mediators from five major pathways: MAPK and PI3K canonical growth pathways, telomere elongation/TERT, cell cycle G1-phase and the p53 pathway. In a recent breakthrough study on a prospective Discovery cohort, I proposed the first all-inclusive molecular classification of glioblastoma into seven subgroups, G1-G7, based on MAPK pathway activation. New data from a subsequent, prospective Validation cohort validated the G1-G7 molecular subgroup classification, showing significant demographic and molecular differences between subgroups. Beside the initial histologic diagnosis, the G1-G7 classification requires next generation sequencing (NGS) of formalin-fixed paraffin-embeded (FFPE) samples and genomic-transcriptomic correlations between DNA mutations, copy number variations (CNVs) and RNA expression. Thus, in the Combined cohort containing tumors from over 220 glioblastoma patients, aproximately 75% of cases fell into three major subgroups, G1/EGFR, G3/NF1 and G7/Other, whereas the rest of 25% cases made up the four minor subgroups, G2/FGFR3, G4/RAF, G5/PDGFRA and G6/Multi-RTK. The name of the mutated most upstream, non-redundant, MAPK pathway effector corresponds to each subgroup, except for the G7/Other subgroup in which MAPK activation is minimal and PI3K pathway activation is dominant. The effectors of the other four pathways may be redundant; however, genomic-transcriptomic correlations showed subgroup specificity, with opposing trends for the G1/EGFR and G7/Other molecular subgroups. This first, all-inclusive, molecular subgroup classification of glioblastoma in a large prospective patient cohort allowed integrated pathway analysis, risk stratification and demographic comparison between Caucasian/White and African-American/Black patients. Most importantly, its implementation into clinical practice opened the avenue to controlled therapeutic approaches.

IMMU-41. GBM PLATELET HYPERACTIVITY DRIVES THE IMMUNOSUPPRESSIVE TME IN A SEX-DEPENDENT MANNER

Abstract Cancer-related thrombosis is the second leading cause of death for cancer patients, including those with glioblastoma (GBM), the most common primary malignant brain tumor. Patients with GBM have a 30% risk of venous thromboembolism. Moreover, sex biases are well established in GBM, with men 1.6-fold more likely to develop GBM and exhibiting a poorer prognosis than females. GBM is extremely difficult to treat due to its highly immunosuppressive tumor microenvironment (TME), often infiltrated with suppressive myeloid populations and a reduction in T-cells intratumorally and systemically. Our group has recently demonstrated these sex-biases in survival are due to differences in the immune cell populations making up the TME. Despite these findings, there is limited information as to how a hyper-thrombotic state contribute to the immunosuppressive TME. Additionally, the role that sex biases play in these mechanisms has not been explored. Our previous work demonstrated that thrombin, a major platelet activator through PAR1 and PAR4 receptor signaling, is secreted from cancer stem cells into the tumor microenvironment. We now show that GBM patient have elevated levels of the thrombin-antithrombin complex and have increased PAR4 receptor mediated platelet activation. Similarly, we show that tumor bearing mice have elevated PAR4 receptor mediated platelet activation relative to non-tumor bearing mice. We further demonstrate pharmacologically targeting the thrombin-PAR4 signaling axis in murine GBM models prolongs survival in females but has not affect in males by preventing female platelet hyperactivity and subsequently increasing the number and function of tumor infiltrating CD8+ T-cells. These findings demonstrate how activated platelets interact and regulate immune cell populations in GBM. These results suggest that the hyper-thrombotic state seen in many GBM patients simultaneously contributes to the immunosuppressive TME. In addition, these results identify therapeutic strategies to leverage the platelet hyperactivity seen in GBM by hyperactive thrombin-PAR4 for sex-dependent therapeutic purposes.

EXTH-65. EXPLORING ANTIHISTAMINES TO TREAT GLIOBLASTOMA

Abstract BACKGROUND Glioblastoma (GBM) is an aggressive and lethal primary malignant brain tumor with a 5-year survival of 6.8%. Interestingly, people with allergies, atopy, or asthma are less likely to develop GBM. A recent study recognized that high histamine receptor 1 (HRH1) expression is inversely related to overall and progression-free survival. METHODS We used a bioinformatics tool, iLINCS, which, after analyzing 99 GBM and 38 healthy samples, identified 36 drugs that can reverse GBM signatures. Based on the concordance score and blood-brain barrier permeability, we selected brompheniramine (Brom), a first-generation HRH1 antagonist, as a potential candidate. HRH1 expression analysis was done on human and mouse GBM cell lines by immunoblotting. The effect of Brom alone or in combination with temozolomide (TMZ) was investigated on proliferation, DNA damage and apoptosis in human (U118 and U251) and three syngeneic (EGFRvIII, p16-/- & GFAP Cre, PTEN+/-, p53R172H+/-, EGFRvIII & GFAP Cre, PTEN-/-, p53R172H-/- & GFAP Cre) cell lines. GBM orthograft mouse models were used to test the efficacy of combination therapy. RESULTS HRH1 is highly expressed in human and syngeneic GBM cells. This expression is further increased in TMZ-resistant cells. Interestingly, the addition of histamine, induced TMZ resistance in GBM cells. TMZ with Brom decreases proliferation in mouse and human GBM cells, and Brom is non-toxic to non-transformed cells. Combination treatment increases DNA damage and decreases the DNA repair mechanism, possibly by downregulating the expression of O6methylguanine-DNA methyltransferase (MGMT). In the GBM orthograft mouse model, the combination therapy reduced tumor volume and significantly increased survival compared to single-agent treatment. CONCLUSIONS Brom is non-toxic; Brom, in combination with TMZ, enhanced the anti-tumor efficacy of TMZ both in in vitro and in vivo GBM models. Further studies in spontaneous mouse models are planned.

BIOM-21. SMALL EXTRACELLULAR VESICLES AS A NOVEL LIQUID BIOPSY APPROACH FOR GLIOBLASTOMA

Abstract Glioblastoma (GBM) remains the most common and aggressive primary malignant brain tumor, with limited treatment options and poor overall survival. Diagnosis, prognosis, and assessment of treatment effectiveness are hampered by the lack of sensitive, tumor-specific, non-invasive blood-based assays which could be followed serially. Small extracellular vesicles (sEV) are nano-sized (≤200 nm) membrane-bound bodies secreted by all cells, encapsulating cargo reflective of their parent cells. sEVs have emerged as promising molecular disease indicators. Here, we report the feasibility of isolating glioma-specific sEV (sEVglioma) from plasma and characterizing them for GBM-specific molecular biomarkers. Plasma samples were collected from 31 glioma patients (grades 3 and 4 GBM, grades 2 and 3 astrocytoma) and 9 healthy individuals. Total sEVs (TE) were isolated from plasma by a modified precipitation (ExoQuick™) method, followed by immunoprecipitation to isolate sEVglioma employing surface markers targeting the cellular origin of gliomas, including astrocyte (GLAST and EAAT2), oligodendrocyte precursor cell (OSP and MOG), and neural stem cell (CD133). The average size of sEVglioma was less than 200 nm. Importantly, compared to TE, sEVglioma showed significant enrichment for glioma-specific biomarkers such as ephrin type-A receptor 2 (14.7-fold), tenascin-C (22.7-fold), and glial fibrillary acidic protein (8.4-fold). Similarly, sEVglioma demonstrated higher expression of the GBM biomarker EGFRvIII (3.6-fold). These results were confirmed by confocal microscopy. Interestingly, the expression of specific miRNAs (miR-9a-5p, miR-16-5p, miR-21-5p) in sEVglioma was higher in glioma patients with shorter survival (<12 months) compared to longer survival (>20 months). Lastly, we successfully detected the existence of wild-type IDH1 and absence of mutated IDH1 R132H in sEVglioma from GBM patients, validated with cell line experiments. In conclusion, we present a novel liquid biopsy approach for isolating sEVglioma from blood, providing valuable molecular and genetic information. This approach promises early detection, potential to distinguish pseudo-progression, and assessment of treatment effectiveness with remarkable precision.

TMIC-23. INVESTIGATING THE FUNCTIONAL ROLE OF SECRETED FERRITIN FROM GLIOBLASTOMA CELL TYPES

Abstract Glioblastoma (GBM) is the most common primary malignant brain tumor in adults with a survival rate ~5%. Our laboratory previously showed the inhibitory effect of iron and ferritin-bound iron on migration and spheroid formation in GBM cells. Furthermore, studies have shown the release of extracellular vesicles (EVs) and their iron-related cargoes are regulated by cellular iron concentrations. Building on these findings, this study aims to investigate the impact of EV-associated ferritin on migration in GBM. To achieve this, we examined the influence of iron on EV release from four GBM cell lines, comprising two cancer stem cells (CSCs) and two non-CSCs: T387, T3691, LN229, and T98G. Using Nanoparticle tracking analysis (NTA), we demonstrated that 100 μM of ferric ammonium citrate (FAC) significantly increases EV release in the CSC line after 24 hours (p-value <0.01). Conversely, there was no significant impact on the non-CSC line under the same conditions. Based on these results, the ability of iron to regulate EV release is dependent on CSC versus non-CSC status. Given the functional role of ferritin on migration potential in GBM, we used immunoblotting to examine ferritin release from cells following iron treatment. We observed a reduction in ferritin release from CSCs following FAC treatment compared to the control, while non-CSCs, in contrast, released more ferritin after treatment. Interestingly, ferritin released from CSCs was predominantly within EVs, whereas ferritin released from non-CSCs was not associated with EVs. To assess the functional impact of ferritin release on migration, we utilized a Transwell migration system, and observed that EVs from iron-treated cells reduced migration in the recipients. Together, these findings expand our understanding of differential responses of ferritin in CSC and non-CSC EVs to iron treatment and will allow us to identify new targets and strategies for managing GBM progression.

DDDR-45. INVESTIGATING TEMOZOLOMIDE RESISTANCE IN GLIOBLASTOMA USING A CLINICALLY RELEVANT DOSING REGIMEN

Abstract The standard of care of management for glioblastoma, the most common primary malignant brain tumor in adults, involves maximal safe surgical resection followed by adjuvant chemoradiotherapy and six cycles of adjuvant temozolomide (TMZ). Approximately half of all treated patients develop chemoresistance to TMZ. The evolution of chemoresistance to temozolomide in vitro has historically involved continuous exposure to drug, as opposed to clinical dosing schedules, which involve five days of treatment followed by 23 days of recovery. Thus, in this study, we examined the emergence of chemoresistance to TMZ in vitro, using a clinical dosing regimen. Temozolomide dose response to RN1, an MGMT promoter unmethylated, IDH-wildtype, patient-derived glioblastoma cell line, was determined using cell titer glo. Cells were treated with TMZ for five days, followed by 23 days of recovery, in cycles. In each subsequent cycle, the dose of TMZ used was adjusted to previous cycle’s IC50, the concentration at which 50% of cell growth is inhibited. This protocol was repeated over three rounds. Cells treated with TMZ, as compared to the DMSO-treated control population, gradually acquired chemoresistance with a continuous increase in IC50. Our protocol therefore highlights how a clinically relevant dosing regimen may help capture the trajectory by which chemoresistance emerges, also allowing for the exploration of the molecular mechanisms underlying this phenomenon.

CSIG-16. A CX43-WNK1-C-MYC SIGNALING AXIS DRIVES GLIOBLASTOMA CANCER STEM CELL SURVIVAL

Abstract Tumors represent a highly dynamic system that relies on coordinated signaling to drive growth and adapt to selective pressures, including those induced by anti-cancer therapies. Given the need for tumors to engage in rapid and coordinated cell-cell communication, mechanisms such as gap junction intracellular communication (GJIC) should be essential. However, the connexin proteins that make up gap junctions have traditionally been considered tumor suppressors based on the frequent loss of GJIC and lower connexin expression in tumor cells compared to non-neoplastic tissue. For this reason, connexin 43 (Cx43) has been proposed to suppress the growth of glioblastoma (GBM), the most common primary malignant brain tumor. However, recent data suggest that this tumor-suppressive effect is context dependent and that connexins can also function in a tumor-promoting role. Using next-generation sequencing techniques, we found Cx43 expressed at high levels in a panel of GBM patient-derived xenograft (PDX) CSCs and that these models rely on Cx43 for their survival and self-renewal. Mechanistically, depletion of Cx43 led to a dramatic loss of c-MYC expression through reduced phosphorylation of its upstream mediator WNK lysine-deficient protein kinase 1 (WNK1). Depletion of WNK1 phenocopied knockdown of Cx43 and reduced MYC protein and mRNA as well as tumor growth in vivo. Together, this work defines a novel signaling axis downstream of gap junction protein expression that promotes tumor growth and cancer stem cell phenotypes in GBM. Due to the difficulty in targeting both Cx43 and MYC, the identification of intermediate targetable signaling nodes may lead to improved therapies for patients with GBM.

DDEL-07. EFFICACY OF TEMOZOLOMIDE IN MEDULLOBLASTOMA PATIENTS: REVIEW OF SERIES OF TWO ADULT PATIENTS WITH RECENT UPDATES IN LITERATURE

Abstract Medulloblastoma is a primary malignant CNS tumor commonly seen in children and rarely in adults (20% vs 1% of all primary brain tumors). Maximal safe resection and craniospinal irradiation followed by adjuvant chemotherapy have proven to be an effective treatment in children. Due to insufficient data available in adult patients, it is also the usual approach in them despite unclear long-term outcomes. Standard chemotherapeutic regimens consisting of vincristine, cisplatin, and lomustine are known to cause greater toxicity in adults making adequate dose titration a challenge. Temozolomide is a second-generation cytotoxic alkylating agent with favorable CNS penetration. It is a potential alternative that has yielded superior results in treating gliomas and preventing recurrence along with minimal toxicity. We discuss a series of two adult medulloblastoma cases which were given 24 cycles of Temozolomide monotherapy over two years following surgical resection and craniospinal irradiation. Serial MRIs did not report any signs of recurrence rendering one case cancer-free for seventeen years and the other for ten. Minimal toxicity in the form of nausea, vomiting, headache, and reversible, temporary pancytopenia was seen in contrast to other agents. Improved survival with minimal toxicity was demonstrated in both cases proving the efficacy of Temozolomide as adjuvant chemotherapy for adult Medulloblastoma. While a regimen of Temozolomide is recommended for recurrent Medulloblastoma, there is no optimal regimen available for initially diagnosed, localized tumors, especially in adults. Multi-institutional clinical trials are required to study its role as a monotherapy during an early yet critical phase of management.

DDDR-25. IBUDILAST AND ANTI-PD-L1 COMBINATION TREATMENT SIGNIFICANTLY IMPROVES SURVIVAL IN A SEX-DEPENDENT MANNER IN A MURINE MODEL OF GLIOBLASTOMA

Abstract INTRODUCTION Glioblastoma (GBM) is the most common primary malignant brain tumor, and there remains a significant need for new treatments. Previous trials studying immune checkpoint inhibitors (ICI) as single agents have been negative. Ibudilast is a brain penetrant inhibitor of the macrophage migration inhibitory factor (MIF)-CD74 interaction that sensitizes GBM to temozolomide in vitro and alters myeloid-derived suppressor cells in vitro and in vivo. The purpose of this study was to investigate whether ibudilast increases ICI efficacy in a murine model of GBM. METHODS 6-week-old male and female C57BL/6 mice were implanted with SB28 cells intracranially. One week after implantation, each group was randomized to receive intraperitoneal treatment with either: ibudilast (50 mg/kg), anti-PD-L1 (1mg/kg), combination, or vehicle control. Mice were euthanized at neurological endpoint. Survival was modeled with Cox proportional hazards regression. RESULTS Among females, there was a significant difference in survival among treatment groups (p=0.0002). Specifically, combination treatment led to significantly longer survival compared to ibudilast (p=0.004) and control (p=0.03), but not anti-PD-L1 (p=0.12). Among males, there was no significant difference in survival among groups (p=0.40). Males had significantly shorter median survival compared to females (overall: 18 versus 22 days, combination treatment: 20 days versus 32 days, anti-PD-L1: 14 versus 22 days, ibudilast: 17 versus 17 days, control: 18 versus 22 days, p=0.02). CONCLUSIONS Ibudilast with anti-PD-L1 is a promising combination treatment against GBM. Future research is needed to identify the mechanisms underlying this treatment regimen and its sex-dependent effect. These results may inform the development of a combination new clinical trial, as ibudilast is currently being evaluated in the newly-diagnosed and recurrent GBM setting with temozolomide.

EPCO-56. INHERITED PREDISPOSITION TO ADULT GLIOMAS: OVERVIEW OF THE CURRENT CLINICAL PRACTICE AND FUTURE RECOMMENDATIONS

Abstract Gliomas are the most common adult primary malignant brain tumor and occur in ages 45-65 years old. While most gliomas are sporadic in nature, a small portion is related to cancer predisposition syndromes (CPS), such as Li Fraumeni or Lynch syndromes. Given that 5–10% of patients will have a family history of glioma, there is currently an effort in identifying germline variants associated with gliomas. Additionally, with the advent of somatic tumor testing, it is possible to pick up suspected germline mutations in genes that cause CPS. Our experience includes a 32-year-old patient diagnosed with astrocytoma IDH mutant, Grade 2 who was found to have a BRAC1 mutation on somatic brain tumor testing. 10 years later, the patient was found with metastatic ovarian cancer and a germline BRAC1 mutation. Early identification of CPS can lead to early detection or prevention of malignancies in affected patients and relatives. However, gliomas are rarely the primary or presenting tumor of CPS, and guidance of CPS screening for these individuals is still lacking. Due to the increasing interest and importance of CPS testing in patients with glioma we have developed a collaborative protocol between our neuro-oncologists and genetic counselors aso that patients have access to germline testing. We propose that all patients with glioma at age of 50 or under, patients with strong family history of cancer including gliomas, and patients with suspected germline mutations based on tumoral somatic mutational profile should be referred to the genetic counselors. Our preliminary findings include 8 patients who completed germline genetic testing. Of these, one patient tested positive for a BRCA1 pathogenic variant. We are planning to continue to collect this data to better inform clinical practice.

CNSC-54. CENTRAL AND BOUNDARY-DRIVEN GROWTH PATTERNS DOMINATE RESPECTIVELY IDH WILD-TYPE AND MUTANT GLIOMAS

Abstract Diffuse gliomas are the most prevalent primary malignant brain tumors in adults and are characterized by invasive growth and poor prognosis. Tumor cells infiltrate the brain parenchyma and spread to distant sites. The aim of this study is to characterize the spatial heterogeneity, mode, and direction of tumor development to identify key areas for localized treatment. Neuronavigation was employed to collect n=134 image-guided samples from n=16 adult patients with diffuse gliomas, including n=7 IDH wild-type (IDHwt) and n=9 IDH mutant (IDHmut) tumors from regions with and without MRI abnormalities. Collected samples were subjected to targeted and shallow whole-genome sequencing. Somatic variants were used to determine the evolutionary processes governing heterogeneity. Examination of the dN/dS ratio, Tajima’s D score, and MOBSTER model suggested that all tumors are consistent with neutral evolution, as previously reported. Considering that genetic heterogeneity was a result of stochastic mutations, we used phylogeographic relationships between samples to dissect the spatiotemporal development of these tumors. Evolutionary (patristic) and cartesian (Euclidean) distances between sample pairs from the same patient were correlated in n=2/9 IDHmut and n=2/7 IDHwt patients, suggesting that migratory or punctuated evolutionary processes play a major role in tumor diffusion. An examination of spatial diffusion revealed that the latest descendant appeared peripherally in n=5/9 IDHmut patients, suggesting boundary-driven growth. In the remaining cases, three patients exhibited centrally-driven growth, whereas a fourth patient displayed a mixed pattern. In contrast, in n=4/7 IDHwt patients, descendants appeared closer to the tumor center, suggesting centrally-driven growth. In the remaining three IDHwt patients, one patient showed a diffusion that was consistent with boundary-driven growth, while the other two patients showed a mixed pattern. Taken together our data suggest that IDHwt tumors tend to develop centrally, whereas IDHmut tumors preferably develop outward. Our data could aid in tailoring localized treatment based on projected growth patterns.

QOL-31. RESULTS OF A TELEHEALTH-BASED PSYCHOLOGICAL INTERVENTION FOR CAREGIVERS OF PATIENTS WITH PRIMARY MALIGNANT BRAIN TUMORS: A MODERATION ANALYSIS OF A RANDOMIZED CONTROLLED TRIAL

Abstract BACKGROUND In a recent randomized controlled trial, caregivers of patients with primary malignant brain tumors (PMBT) who received NeuroCARE—a six-session, telehealth-based psychological intervention—demonstrated improved anxiety and depression symptoms, coping, and self-efficacy at 11-weeks compared to usual care (UC) participants. We now explore how sociodemographic variables, disease-specific factors, and baseline mood symptoms moderate intervention effects on anxiety and depression symptoms. METHODS We examined data from 120 enrolled caregivers (Mage=53 years; 83% female, 92% White, 70% spouses/partners) of PMBT patients (84% glioblastoma). Eligible caregivers had elevated anxiety (Generalized Anxiety Disorder-7 ≥ 5). Participants were randomized 1:1 to NeuroCARE or UC and completed baseline sociodemographic questionnaires and the Hospital Anxiety and Depression Scale at baseline and 11-weeks. We used linear regression to evaluate whether selected sociodemographic characteristics (gender, age, relationship to patient), tumor characteristics (tumor location/laterality, IDH mutation status), and baseline mood symptoms moderated intervention effects on anxiety and depression symptoms. We report the group-by-moderator (b) effects, using a 0.20 significance level. RESULTS The beneficial effects of NeuroCARE on reducing 11-week anxiety symptoms were greater in women compared to men (b=-2.63, CI: -6.17, 0.91, p=0.14) and greater in caregivers who reported higher baseline anxiety symptoms (b=-0.43, CI: -0.78, -0.08, p=0.02) and depression symptoms (b=-0.56, CI: -0.96, -0.17, p=0.01). The beneficial effects of NeuroCARE on reducing 11-week depression symptoms were greater in caregivers of patients with IDH-wildtype tumors compared to caregivers of patients with IDH-mutant tumors (b=2.49, CI: -0.26, 5.24, p=0.08). Caregiver age, relationship to patient, and tumor location/laterality did not significantly moderate NeuroCARE effects on mood. CONCLUSIONS The positive effects of NeuroCARE were particularly salient for caregivers with elevated anxiety and/or depression symptoms and those caring for patients with IDH-wildtype tumors. Content may be further tailored to account for the unique needs of men and caregivers of patients with IDH-mutant tumors.

STEM-18. A HIGH THROUGHPUT NEUROSPHERE BASED COLONY FORMATION ASSAY TO VALIDATE DRUG AND RADIATION EFFECTIVENESS IN PATIENT DERIVED XENOLINES

Abstract Glioblastoma (GBM) is a primary malignant brain tumor developed from normal astrocytes. GBM patients’ median survival is less than 2 years despite safe surgical resection, fractionated conventional radiation, and temozolomide (TMZ) therapy. Few currently used drugs are successful in GBM although there are many FDA approved blood-brain barrier (BBB) penetrant drugs, for other uses that have not been screened in GBM. We utilized a panel of 734 of these BBB penetrant drugs in different GBM patient derived xenolines (PDX) along with acquired radio-resistant derivatives (-RT) including X1441, JX14P, JX14P-RT, JX39P, JX39P-RT and normal human astrocytes (NHA) as control and screened for viability with Cell Titer-Glo. We identified multiple candidate drugs that preferentially killed GBM PDX cells at 10 µM relative to NHA control. As we used stem cell media (serum free) in our drug screening study, it indicates that the potent drugs are also effective in killing cancer stem cells or brain tumor initiating cells. These drugs had targets ranging from PDGFR, DNA/RNA synthesis, as well as other kinase inhibitors. We developed a high throughput (HT), neurosphere based colony formation assay (CFA) in 96-well plate to screen multiple drugs and doses in combination with radiation. For visualizing the colonies, we use a Cytation 5 imager at 4X resolution and count the colonies based on parameters including object size, width, intensity and others. We plan on validating our drug screen and HT-CFA assay with high throughput PamChip kinase activity assays and with in vivo orthotopic tumor PDX models.

EXTH-72. INTEGRATED MULTIOMIC ANALYSIS OF ISOGENIC EGFRVIII MODELS OF GBM REVEALS EXPLOITABLE THERAPEUTIC VULNERABILITIES

Abstract Glioblastoma (GBM) is the most common primary malignant brain tumor with an abysmal 15-month median survival. Therefore, novel therapeutic interventions are urgently needed. EGFR is a receptor tyrosine kinase that is mutated in over 50% of GBM and is a logical target for precision oncology approaches. While aberrant EGFR signaling has been successfully targeted in other cancers, early attempts to target EGFR in GBM clinical trials have not been successful. Since these early trials, several studies have revealed that GBM EGFR biology is unique and cannot be generalized from other EGFR-driven neoplasms. To better understand EGFR biology in a GBM-specific context, we have characterized the GBM transcriptome with RNAseq, the epigenome with CUT&RUN, and the kinase proteome with Multiplexed inhibitor beads with Mass Spectrometry (MIB-MS), collectively referred to as ‘multiomics’, after modeling EGFR resistance. An isogenic mouse astrocyte (mAc) model of GBM was genetically engineered to overexpress EGFRvIII (CEv3), the most common EGFR mutation in GBM. Expression of EGFRvIII induces a unique multiomic profile that mediates many hallmark cancer phenotypes including proliferation and stemness. Chronic EGFR resistance was modeled both in vitro and in vivo through continuous exposure to erlotinib or gefitinib, EGFR tyrosine kinase inhibitors (TKI). Additionally, acute EGFR resistance was modeled using a single exposure to EGFR TKI afatinib or neratinib in vitro over a 48-hour time course. Preliminary multiomic characterization of these data has revealed several targets that can be further investigated for therapeutic exploitation. Further investigation into these targets using orthotopic allografts with CEv3 cells shows that combinatorial therapy with neratinib and abemacilib, a CDK inhibitor, significantly (p < 0.001, n= 20 mice per group) extends survival (56 days) compared to neratinib alone (31.5 days). Future integrated multiomic analysis aims to elucidate the synergistic relationship between neratinib and abemacilib.

IMMU-61. THE LAST OF US: A FUNGI BASED DENDRITIC CELL VACCINE

Abstract BACKGROUND Glioblastoma (GBM) is the most prevalent primary malignant brain tumor in adults. The current standard treatment for newly diagnosed GBM involves maximal surgical resection followed by radiotherapy and temozolomide. Despite these interventions, the median overall survival for GBM patients remains approximately 15 months, highlighting the critical need for innovative therapeutic approaches. OBJECTIVE Our laboratory has previously developed a subcutaneous autologous tumor vaccine incorporating irradiated (IR) tumor cells with phagocytosis-stimulating ligands (Mannan-BAM), toll-like receptor (TLR) agonists, and an immunostimulant anti-CD40 antibody (collectively termed MBT). This combination has shown efficacy in mouse models of colon carcinoma, breast cancer, melanoma, and, more recently, gliomas. Our study aimed to create a dendritic cell (DC) vaccine using this strategy. METHODS To evaluate whether MBT could induce the maturation of DCs in vitro, we harvested BMDCs from mice and co-cultured them in the presence of MBT-tagged irradiated tumor cells. We then analyzed the maturation markers using flow cytometry and assessed cytokine production via ELISA. To test the efficacy of this approach in vivo, we utilized two different murine glioma models (SB28 and GL261). RESULTS Using flow cytometry, we observed a significant upregulation of important co-stimulatory molecules. Additionally, ELISA analysis demonstrated that MBT-treated DCs significantly increased the secretion of Type 1 cytokines while limiting the secretion of the regulatory cytokine IL-10. MBT-primed DCs combined with immune checkpoint inhibitor PD-1 increased mouse survival in a glioma model compared to WT mice. However, mice eventually succumbed to cerebral edema. Histology demonstrated significant treatment effects. CONCLUSION Our results demonstrate that MBT effectively matures DCs ex-vivo. Further research is required to immunophenotype the response to vaccination in glioma models and explore ways to overcome resistance.

QOL-17. REFLECTIONS ON A PSYCHOEDUCATION INTERVENTION FOR PATIENTS WITH NEWLY DIAGNOSED BRAIN TUMORS (NEUROPATHWAYS): A QUALITATIVE STUDY

Abstract BACKGROUND Patients with newly diagnosed primary malignant brain tumors (PMBT) face unique challenges processing and absorbing information regarding their diagnosis, often while contending with cognitive and communication deficits. Limited research exists regarding optimal information provision and support for this highly distressed population. We used input from clinician, patient, and caregiver stakeholders to design a population-specific, psychoeducation intervention (“NeuroPathways”) to address these needs. METHODS We conducted a single-arm study (N=12) to pilot and refine NeuroPathways in English-speaking patients within six-weeks of a PMBT diagnosis. Neuropathways comprises 1) a comprehensive (105 pages) handbook covering information about PMBT diagnosis, treatment, coping, self-care, and vetted resources, and 2) four brief, individual telehealth sessions with a trained interventionist (e.g., psychologist, physician) over 4-8 weeks to assist and empower patients to obtain information, support, and coping guidance at their preferred depth and pace, using the handbook as a resource. Ten participants completed all four sessions and participated in semi-structured exit interviews. We used rapid qualitative analysis to explore participants’ perceptions of intervention delivery, content, and benefit. RESULTS Participants (83% male, median age=52 years) uniformly described NeuroPathways as accessible, citing the telehealth format as particularly important for facilitating participation given logistical challenges related to cancer treatment. Perceived benefits of participation included: a) access to well-organized information targeting both current and future disease- and treatment-related concerns; b) increased skill in problem solving and communication with loved ones and/or medical providers; c) personalized emotional support from interventionists. While most felt the timing was appropriate, several who enrolled later in the eligibility window stated a desire for earlier intervention. CONCLUSION Participant feedback highlights the accessibility and potential benefits of this psychoeducation intervention for patients with newly diagnosed PMBT. These data will inform refinement of NeuroPathways in preparation for a pilot randomized controlled trial to formally assess feasibility and acceptability.