Recurrent Glioblastoma Multiforme Research Articles

CTNI-05. A PROSPECTIVE STUDY OF TUMOR-TREATING FIELDS COMBINED WITH SYSTEMIC THERAPY IN RECURRENT GLIOBLASTOMA

Abstract BACKGROUND Tumor-treating Fields (TTFields) monotherapy was approved for recurrent glioblastoma. However, TTFields combined with systemic therapy has not been well studied in China. This study aims to explore the efficacy and safety of such combination therapy for recurrent GBM. METHOD This study is a prospective, single-arm, open-label clinical trial (NCT04689087) planning to enroll 40 recurrent supratentorial GBM patients and use TTFields combined with physician chose systemic therapy. Kaplan-Meier survival curve was used to estimate PFS, OS and survival rate. The primary endpoint was 6-months OS rate (OS6). Secondary endpoints were PFS, PFS6 and safety. OS and PFS were computed from the day of initiating TTFields. RESULT Fourty recurrent supratentorial GBM patients was enrolled from July 2020 to May 2023. The average age was 51 and median KPS score was 80. Sixty-eight percent (27/40) of them underwent total resection surgery and 5% (2/40) only experienced biopsy as their newly diagnosed GBM surgery. Eighty-eight percent (35/40) of patients started TTFields when they were first diagnosed as recurrence, while 12.5% (5/40) patients started TTFields at their second-time recurrence or latter. Median time from diagnosis of recurrence to initiating TTFields was 27 days. Median duration time of TTFields was 8.7 months and average compliance of TTFields was 87% (20.9 hours/day). As for molecular biomarkers, 50% (20/40) patients were MGMT protein positive and 32.5% (13/40) were TERT mutant. Chemotherapy was included in the systemic therapy in 80% (32/40) patients, antiangiogenic therapy in 60% (24/40) patients, BRAF inhibitor therapy in one patient and immune checkpoint inhibitor therapy in one patient. At data cut-off date of March 20, 2024, the median follow-up period was 20.8 months. The primary endpoint OS6 was 87.2%, the median OS was 20.2 months (95%CI 11.9-NR). Median PFS was 8.5months (95%CI 6.2-NR). PFS6 was 67.5% while the historical reference of physician’s best choice of active chemotherapy from EF-11 study showed a PFS6 of 15%. Scalp adverse events were the most common AE. Seventy-eight (31/40) of patients experienced grade 1 or 2 scalp adverse events which can be relieved by topical corticosteroids. CONCLUSION TTFields combined with systemic therapy showed favorable efficacy and safety in Chinese recurrent GBM patients. Key words: Recurrent GBM, TTFields, prospective study, systemic therapy

CTNI-48. A PHASE 1 STUDY OF ERAS-801, A POTENT, SELECTIVE, AND CENTRAL NERVOUS SYSTEM (CNS)-PENETRANT EPIDERMAL GROWTH FACTOR RECEPTOR (EGFR) INHIBITOR, FOR PATIENTS WITH RECURRENT GLIOBLASTOMA MULTIFORME (GBM)

Abstract EGFR is among the most common targets for genetic alterations in GBM. Changes in EGFR gene amplification and the extracellular domain result in receptor overexpression or constitutive activation, and enhanced oncogenic signaling. ERAS-801 is a potent, selective, and highly CNS-penetrant EGFR inhibitor being developed for the treatment of GBM, with a focus on tumors harboring EGFR genetic alterations. THUNDERBBOLT-1 is the first-in-human phase 1 dose escalation and expansion trial evaluating ERAS-801 monotherapy for patients with recurrent GBM. ERAS-801 is administered orally once daily for continuous 28-day cycles. As of April 10, 2024, a total of 52 patients were treated across 7 dose cohorts: 20 mg (n=3), 40 mg (n=5), 80 mg (n=3), 160 mg (n=6), 240 mg (n=25), 280 mg (n=4), or 320 mg (n=6). Key patient characteristics were median age of 60 years, 67% male, mostly one prior therapy, and 81% tumors with alterations. The MTD was 240 mg. Dose-limiting toxicities were observed at 320 mg (n=2, Grade 2 QT prolongation, Grade 3 rash and Grade 3 dermatitis acneiform), 280 mg (n=3, Grade 3 QT prolongation), and 240 mg (n=1, Grade 3 QT prolongation) doses. The most common treatment related adverse events (TRAEs), in >10% of patients, were dermatitis acneiform, diarrhea, and nausea. Electrocardiogram QT prolongation occurred in 11.5% of patients and was not associated with clinical findings. ERAS-801 showed rapid absorption; peak plasma concentration was generally achieved within 6 hours post dose. PK exposure increased in a dose-dependent manner over the doses evaluated. Across all doses there was a confirmed partial response (using mRANO) in 1 patient and 6 patients achieved a PFS of 6 months. ERAS-801 shows well behaved PK with substantial CNS penetration, preliminary safety, and tolerability in patients with recurrent GBM. The TRAEs were reversible, manageable, and consistent with known toxicities of EGFR inhibitors.

CTNI-68. UPDATES ON A POTENTIALLY PIVOTAL TRIAL CNS-201: A RANDOMIZED, CONTROLLED TRIAL OF BERUBICIN VS. LOMUSTINE AFTER FIRST-LINE THERAPY FOR GLIOBLASTOMA MULTIFORME (GBM)

Abstract Berubicin, derived from doxorubicin (Dox), appears to cross the BBB and has shown significant central nervous system (CNS) uptake and anti-tumor activity. A current, potentially pivotal trial for patients with recurrent GBM after first-line therapy has completed enrollment in the US and Europe: a total of 252 patients were randomized 2:1 (Berubicin:Lomustine) after failure of prior therapy. All patients had to have certification of progression by a central reader, were Grade 4 IDH WT, and were stratified by MGMT methylation status. The primary endpoint, overall survival (OS), is maturing in this blinded trial; however, data will be presented that will document the demographics of the Berubicin and Lomustine arms, and provide a comparison of safety profiles and disposition of the patients enrolled on the study. Recently, a pre-planned non-binding futility analysis of the primary endpoint, OS, was evaluated when the trial reached ~30% of expected events (44 events). This interim analysis was performed by an independent statistician under the supervision of the Data Safety Monitoring Board (DSMB), which was additionally comprised of two oncologists. The DSMB’s charter mandated that they review the primary endpoint, OS, as well as secondary endpoints and safety data to determine whether these data for the risk-benefit profile warranted modification or discontinuation of the study. The DSMB recommended that the study continue as it was currently planned, with no modifications required, having met a pre-determined conditional endpoint. After the results of this interim analysis, CNS Pharmaceuticals completed enrollment with 252 patients evaluable for efficacy based on OS evaluations. Based on the decision of the DSMB, as well as the data presented herein, which includes comparative safety and balanced randomization of the arms, we will provide our recommendations and highlight our further development of Berubicin as a therapeutic option for patients with recurrent GBM as well as other CNS malignancies.

NCMP-01. EARLY RECURRENCE OF GLIOBLASTOMA MULTIFORM INVOLVING MULTIPLE BRAIN REGIONS ASSOCIATED WITH MUTATIONS IN EXON 4 OF ISOCITRATE DEHYDROGENASE 1 COMPLICATED BY GADOLINIUM-INDUCED ACUTE KIDNEY FAILURE: A CASE REPORT

Abstract BACKGROUND Glioblastoma multiform (GBM) remains one of the most aggressive primary brain tumors with high recurrence rates. Case presentation We present a case of a 43-year-old female, Yira, diagnosed with early recurrence of GBM involving multiple brain regions, accompanied by mutations in exon 4 of isocitrate dehydrogenase 1 (IDH1), a marker associated with poor prognosis. Additionally, this case was complicated by gadolinium-induced acute kidney failure on postoperative day 3. The patient initially presented with progressive neurological symptoms, including headache and cognitive decline. Multiplanar multiecho MRI of the brain was performed with IV contrast in orthogonal plane and revealed a moderate sized multilobulated heterogeneously and predominantly peripherally enhancing mass lesion with irregular margins and central non enhancing areas of necrosis arising from the right corona radiata, insular cortex, external capsule, lentiform nucleus, temporal, and frontal white matter with blood products. Perilesional edema was seen. Effacement of sulcal spaces. Right sylvian fissure, compression over right ventricle and midline shift of 8mm toward left side. There was dilatation of the left lateral ventricle with periventricular cerebrospinal fluid ooze. Uncal herniation was right side. On MR spectroscopy large choline, creatinine levels were seen in the lesion with reduced N-acetyl aspartate levels as compared to the normal parenchyma. Findings were suggestive of neoplastic lesion mostly high-grade glioma. Polymerase chain reaction sequencing confirmed missense mutation R132H in exon 4 of isocitrate dehydrogenase 1 gene. Despite maximal safe surgical resection, the patient developed recurrent GBM within three months, with gadolinium-based contrast agent exposure leading to acute kidney injury. CONCLUSION The combination of aggressive tumor behavior and complications from contrast agent administration highlights the challenges in managing recurrent GBM. This case underscores the importance of vigilant monitoring for complications in GBM patients, particularly those with IDH1 mutations, and the need for further research into novel therapeutic strategies.

CTIM-23. A PHASE II STUDY OF RETIFANLIMAB (PD-1 INHIBITOR) AND EPACADOSTAT (IDO1 INHIBITOR) IN COMBINATION WITH BEVACIZUMAB AND HYPOFRACTIONATED RADIOTHERAPY FOR RECURRENT GLIOBLASTOMA: NCT03532295

Abstract INTRODUCTION Immunotherapy has not improved survival in recurrent GBM (rGBM). Indoleamine 2,3 dioxygenase 1 (IDO1), highly expressed in ~90% of patients with malignant glioma, is a rate-limiting enzyme that catabolizes tryptophan (Trp) into kynurenine (Kyn) and enables immune escape. METHODS We hypothesized combining therapies targeting immunosuppressive pathways with cytotoxic and antiangiogenic therapies would overcome tumor-related immunosuppression. This was an open-label Phase II study of two regimens: Arm A consisted of retifanlimab (anti-PD1, 500mg IV Q4W) + bevacizumab (10mg/kg IV Q2W) + HFRT (3.5Gy/day x 10) in patients with IDH1/2-WT rGBM. Regimen B added the IDO inhibitor, epacadostat (400mg po BID), initiated prior to HFRT. Key inclusion criteria included dexamethasone ≤ 4 mg/day. The primary endpoint was overall survival (OS) at 9 months (OS-9). 24 evaluable patients were required to detect an OS-9 of 60% with 80% power, compared to 38% in historical controls (bevacizumab alone) by 1-sided 1-sample log rank test at alpha=0.1. RESULTS We previously reported Arm A. Here, we present results from Arm B. 25 of the 27 patients enrolled to regimen B were evaluable: median age 58years (23-71); 28% female; 23% MGMT promotor methylated; median KPS 90 (70 - 100); a median of 6 cycles of epacadostat as of May 2024 (1 - 13). 18 of 25 died with a median follow up 9.23 months. Median PFS was 7.52 months (95%CI: 5.52-9.43). Median OS was 9.5 months (95%CI 8.08-11.96). Regimen B met its primary endpoint with OS-9 of 61.07% (95%CI: 38.23-77.65%). There were 5 possible immune-related grade 3+ toxicities to date (2 ALT/AST increase; 3 rash). CONCLUSIONS Retifanlimab, epacadostat, HFRT, and bevacizumab in rGBM is well-tolerated, with encouraging OS and PFS at the time of submission. Arm B met its primary endpoint. Further studies are warranted to identify biomarkers to predict long-term responders.

CTNI-76. A PHASE 1/2 DOSE ESCALATION AND EXPANSION STUDY OF SONODYNAMIC THERAPY WITH SONALA-001 IN COMBINATION WITH NON-ABLATIVE MR-GUIDED FOCUSED ULTRASOUND IN SUBJECTS WITH PROGRESSIVE OR RECURRENT GLIOBLASTOMA

Abstract Recurrent glioblastoma (rGBM) is a lethal brain tumor with no effective standard of care option and an extremely poor prognosis (median survival 6 to 8 months after first recurrence). Sonodynamic therapy (SDT) is a non-invasive combination therapy that utilizes a drug, aminolevulinic acid HCL (SONALA-001, ALA), and a device, the Exablate 4000 Type 2.0 to deliver MR-guided focused ultrasound (MRgFUS). Preclinical studies have shown that SDT activates protoporphyrin IX (PpIX) to generate reactive oxygen species that lead to tumor cell death and improved survival in animal glioma models. A first-in-human Phase 0 trial (NCT04559685) indicated that ALA SDT was well-tolerated and not associated with off-target cellular or radiographic effects and provided direct evidence of reactive oxygen species formation and targeted tumor cell death in recurrent high-grade glioma (rHGG). SDT-202 is a Phase 1/2 multicenter, open-label, dose escalation and expansion study (NCT05370508) of iv SONALA-001 (ALA) in combination with MRgFUS for SDT in patients with progressive or recurrent GBM. Dose escalation will include an initial drug and energy dose escalation of ALA SDT utilizing an accelerated titration design with single subject cohorts for dose level cohorts 1 and 2, followed by cohort 3 with 3 + 3 design for additional dose escalation. SONALA-001 is administered 6 to 9 hours prior to MRgFUS treatment. Once the RP2D is determined, Phase 2 dose expansion will enroll approximately 36 additional subjects to assess safety and efficacy of repeated cycles of ALA SDT at the optimized RP2D. Endpoints of this study are safety evaluation, maximum tolerated dose (MTD), recommended Phase 2 dose (RP2D), and determination of pharmacokinetic (PK) parameters. The Phase 2 portion will further characterize safety of RP2D along with evaluation of efficacy with PFS6 (mRANO), ORR, CBR, DOR, DOCR, TTR, and OS. Preliminary PK and safety results will be presented.

RTID-04. A MULTICENTER, RANDOMIZED, CONTROLLED PHASE 2B TRIAL OF SURVIVIN VACCINE SURVAXM PLUS ADJUVANT TEMOZOLOMIDE FOR NEWLY-DIAGNOSED GLIOBLASTOMA (SURVIVE)

Abstract BACKGROUND Glioblastoma cells express high levels of survivin protein, whose presentation by MHC class I gets recognized by antibodies and cytotoxic T-lymphocytes (CTLs). A phase 2a trial (NCT02455557) demonstrated a median overall survival (OS) of 25.9 months in newly-diagnosed glioblastoma (nGBM) patients with 15-amino-acid-peptide-conjugate survivin vaccine (SurVaxM), which also stimulated production of survivin-directed antibodies and anti-tumor CTL. This phase 2b trial aims to further investigate efficacy and safety of SurVaxM plus adjuvant temozolomide (TMZ) for nGBM. METHODS SURVIVE is an ongoing, multicenter, randomized, placebo-controlled, investigator- and patient-blinded, phase 2b trial that randomizes nGBM patients receiving standard-of-care therapies to either SurVaxM (SurVaxM arm) or saline (control arm) in 3:2 ratio at 15 sites. Included patients have age ≥18 years, normal organ function, KPS≥70, and receive surgical resection with ≤1cm3 residual MRI contrast enhancement within 72 hours post-resection plus TMZ. Patients with recurrent, multicentric, brainstem- or cerebellar-origin GBM are excluded as well as patients on TTFields or other immunotherapies. All patients undergo 3 phases: (1) vaccine priming (VP) phase, starting ≤4 weeks after completing chemoradiation – 4 doses of SurVaxM or placebo administered q2weeks; (2) TMZ phase, started after ≥1 VP dose; and (3) vaccine maintenance phase, started 8 weeks after VP, with SurVaxM or placebo given q8weeks. TMZ phase overlaps with VP and VM phases. Primary endpoint is median OS. Assuming 1-year-OS of 75% in SurVaxM arm, based on prior trials, and 60% for control, the required sample size is N=228; 137 in SurVaxM and 91 in control arm. Accounting for dropouts, we aimed to enroll 239 patients. A log-rank test stratified by KPS (70-80 vs 90-100), MGMT methylation status, and IDH mutation status will be used for analysis. Secondary endpoints are OS and PFS at 15, 18, and 24 months, median PFS, and toxicity. A single sequential OS-driven interim analysis is planned when 50% of deaths occur. Trial is fully enrolled (NCT05163080).

EPCO-38. IDENTIFYING THE MOLECULAR SIGNATURE OF INFILTRATING EDGE IN GLIOBLASTOMA AS DRIVERS OF TUMOUR INVASION AND RECURRENCE

Abstract Complete tumour resection in glioblastoma patients is not possible. Residual therapy-resistant edge-derived cells drive tumour recurrence and infiltrative expansion in glioblastoma. Features that are specific to malignant edge-derived cells may serve as predictive biomarkers to allow individual tailoring of the treatment plan to slow down tumour invasion and prevent tumour recurrence in GBM patients following standard therapy. Intratumoural spatial heterogeneity facilitates therapeutic resistance and recurrence in glioblastoma. Our knowledge on glioblastoma heterogeneity is mostly restricted to the surgically resectable tumour core, while the functional characterization of tumour cells at the infiltrating edge remains largely elusive due to the presence of normal functional brain tissue in the peritumoural lesion. Edge-derived cells exhibit larger capacity for infiltrative expansion and are the main drivers of treatment failure and tumour recurrence, making them action targets for novel treatment approaches in glioblastoma. To resolve the transcriptional heterogeneity of GBM within the spatial context, we profiled gene expression of different tumour regions (“edge” and “core”) obtained at initial surgical resection from primary and recurrent IDH-WT GBM patients with Visium 10x and GeoMx. We show that infiltrative edge-derived cells are spatially segregated and are characterized by regionally shared distinct genomic and transcriptomic signatures that promote invasiveness and underly disease recurrence. Tumour edge is enriched for neuronal signatures, while tumour core displays larger transcriptional subpopulation diversity and abundance of proliferative cells with a high capacity for self-renewal, consistent with the proliferative and cancer stem cell-enriched phenotype in early GBM progressors. Upregulated DEGs of tumour edge cells are significantly associated with ion regulation of transport, chemical synaptic transmission, and nervous system development. These modules may represent tumour cell hijacking of neuronal programs specifically at the tumour periphery as described in the context of glioma-neuron synaptic communication and formation of neurite-like microtubes. Upregulation of ion regulation transport at the tumour periphery indicates enhanced neuronal activity and excitability driving infiltrating growth.

CNSC-08. PROGNOSTIC BIOMARKER DISCOVERY THROUGH PROTEOMIC ANALYSIS OF GLIOBLASTOMA MULTIFORME

Abstract BACKGROUND Glioblastoma multiforme (GBM) is an aggressively malignant brain tumor known for its high recurrence rates and dismal survival outcomes. Despite advancements in surgical and therapeutic strategies, the prognosis for GBM patients remains poor. This study applies proteomic analysis to postoperative GBM tumor specimens to identify molecular markers that could enhance prognosis prediction. Through the analysis of protein expression profiles before and after tumor recurrence, we identified significant alterations in protein pathways via Gene Set Enrichment Analysis (GSEA), highlighting potential biomarkers for disease outcome prediction. METHODS We employed Sequential Window Acquisition of All Theoretical Fragment Ion Spectra (SWATH-MS) proteomics to analyze protein samples from both primary and recurrent GBM patients. Gene Set Enrichment Analysis (GSEA) was utilized to compare protein expression profiles and discern significantly altered pathways. RESULTS Analysis revealed 778 differentially expressed proteins (DEPs), with notable alterations in pathways such as glycolysis, interleukin signaling, and MAPK signaling. Proteins such as TOLLIP, ENO1, and ITGA2B emerged as potential prognostic markers. Validation through an online tumor prognostic analysis platform (ToPP), integrated with The Cancer Genome Atlas (TCGA) data, facilitated the development of a prognostic risk score model. This model effectively categorized patients into high and low-risk groups based on their protein expression profiles, enhancing the prediction of patient outcomes. The proteins and pathways identified offer new insights into the molecular dynamics of GBM postoperatively. The association between protein expression profiles and patient prognosis underscores the potential of these markers in developing customized therapeutic strategies. Additionally, the prognostic risk score model serves as a valuable tool for improving prognostic accuracy and could guide personalized treatment plans. CONCLUSION Proteomic profiling of GBM tumors significantly contributes to uncovering the molecular mechanisms driving this aggressive cancer and facilitates the development of dependable prognostic tools. These findings not only affirm the critical role of proteomics in cancer research but also advance personalized medicine strategies in GBM management.

TMET-30. ONCOLYTIC HSV REWIRES METABOLISM TO PROMOTE ANTITUMOR IMMUNITY THROUGH REDUCTIVE CARBOXYLATION AND FERROPTOSIS

Abstract Cancer cells autonomously rewire metabolism to meet increased bioenergetic demands. Oncolytic HSVs (oHSVs) are attenuated Herpes simplex type 1 derived viruses that lyse tumor cells releasing damage-associated molecules triggering antitumor immunity. Currently one oHSV-1 derived virus is approved for melanoma treatment in the USA and another for recurrent GBM in Japan. While several other viruses are being evaluated in clinical trials for safety and efficacy, an understanding of the impact of oHSV therapy on cancer cell metabolism is largely unexplored. A detailed understanding of how oHSV impact tumor cell metabolism and oxidative stress is important to understand the unique susceptibilities that can further be exploited to improve the therapeutic index. Here, we analyzed transcriptomic changes in tumor biopsies of recurrent high-grade glioma patients treated with oHSV. RNA-seq data obtained from pre- and post-G207 treated biopsies from phase-Ib study patients (NCT00028158) revealed enrichment in pathways related to citric acid cycle, oxidative phosphorylation, and glutamate metabolism. We confirmed these changes by RNA sequencing of oHSV-infected patient derived GBM cells. Mechanistically, oHSV hijacked cellular glucose metabolism to increase oxidative phosphorylation and modulated cellular glutamine metabolism towards reductive carboxylation and reduced free glutathione, collectively contributing to increased ROS generation. Kinome profiling revealed PKC activation upon treatment with oHSV. Increased ROS combined with reduced glutathione, and PKC activation promoted ferroptotic cell death characterized by increased lipid peroxidation and smaller, ruptured mitochondria, and contributed to immunotherapy by this treatment. IDH mutant tumors that block reductive carboxylation were resistant to oHSV-induced ferroptotic cell death and did not benefit from oHSV-induced antitumor benefit. Together, this study presents avenues to enhance antitumor immunity by oHSV therapy.

INNV-08. PRE-CLINICAL AND CLINICAL EVIDENCE FOR THE TREATMENT OF DMG/DIPG USING EMULATE THERAPEUTICS’ ULTRA-LOW RADIO FREQUENCY MAGNETIC FIELD SIGNAL TECHNOLOGY

Abstract EMulate Therapeutics, Inc. (EMTx) has developed a technology that emulates the effects of chemical compounds via a magnetic field. Our research has led to the development of a radio frequency energy (RFE) signal (A1A) that emulates the effects of paclitaxel. Pre-clinical studies demonstrate an effect in slowing down and inhibiting tumor growth. The results of feasibility (Phase I/II) clinical trials testing the EMTx technology for treating recurrent GBM (rGBM) were published in CNS Oncology (CNS Oncol 2023 Pages CNS102, Accession Number: 37462385 DOI: 10.2217/cns-2022-0016). Reported results suggest that the A1A signal is non-inferior to best supportive care (BSC) and when the A1A signal is combined with BSC, a 3-month increase in overall survival (OS) was observed. Diffuse intrinsic pontine gliomas (DIPG) are a rare pediatric central nervous system (CNS) tumor. Survival is measured at under 12 months, with no clinical trials demonstrating a significant increase in OS in 20 years (9 months median survival post radiation therapy). EMTx’s compassionate use program (Hælo® medical device) demonstrated safety and suggested a clinical benefit, with 12 of 14 patients surviving more than 12 months, with median survival of 17 months. EMTx recently completed an orthotopic mouse model of DIPG at University of California San Francisco. The results from exposing the mice to the A1A signal demonstrated a significant survival advantage (P = 0.0163) via the slowing down of cell division. Data to be submitted for peer review publication. The animal model is encouraging and supports the observed results of our compassionate use program. EMTX will submit these results to the FDA for regulatory approval via the Humanitarian Device Exemption pathway. The company will conduct a study with DIPG patients from both the US and India. Subject to FDA protocol approval, 30-35 patients will be recruited to participate in this pediatric neuro-oncology trial, which will be a best supportive care + single therapy (Hælo®) clinical trial.

CTIM-34. EFFECTS OF NEOADJUVANT IMMUNE CHECKPOINT INHIBITION ON PEDIATRIC AND ADULT HIGH-GRADE GLIOMAS

Abstract High-grade gliomas (HGG) are lethal tumors with few long-term survivors affecting adult and pediatric patients. Studies investigating immune checkpoint inhibition (ICI) suggest administration of neoadjuvant anti-PD1 blockade (neo-aPD1) enhances local and systemic anti-tumor responses. This data is supported by increased T cell density in the tumor and proportion of cytotoxic T cells in peripheral blood. In a previous randomized clinical trial, neo-aPD1 improved survival in adult with recurrent glioblastoma. In this study, we utilized multiplex immunofluorescence (mIF), and single-cell RNA sequencing (scRNA-seq) to investigate the effects of neoadjuvant ICI on the TME and compare between pediatric and adult populations. Tissue samples from adult patients with recurrent GBM treated with neo-aPD1 (n=22) or adjuvant only therapy (n=5) were obtained from our UCLA off-label neo-PD1 study. Tissue samples were also obtained from pediatric patients with recurrent/progressive HGG treated with neoadjuvant ICI from the ongoing Pediatric Neuro-Oncology Consortium study PNOC19. Samples included diagnostic tissue from two patients and on study surgery tissue from four patients. All tissue samples were subjected to mIF and underwent imaging analysis to assess immune cell infiltration by quantifying lymphoid and myeloid cell densities across the two treatment groups. Our preliminary findings elucidated a trend of higher T cell infiltration in adult neoadjuvant compared to adjuvant-only treated patients (median density 58.11 vs 15.15 T-cells/mm2). Compared to their adult counterparts, neoadjuvant ICI treated pediatric patients had even more robust total T cell infiltration (median density 268.10 vs 58.11 T-cell/mm2, pediatric vs adult respectively). scRNA-seq analysis revealed a greater enrichment of monocytic macrophages in the pediatric population compared to tissue resident microglia in the adults. This early data requires analysis of additional samples to better understand differences in the anti-tumor immune response between adult and pediatric recurrent/progressive HGG patients.

EXTH-31. TARGETINGMIR-19B/PPP2R5E REGULATORY AXIS TO MAXIMISE ALKYLATING AGENT EFFICACY: A NEW AVENUE TO COUNTERACT TEMOZOLOMIDE RESISTANCE IN RECURRENT GLIOBLASTOMAS

Abstract Glioblastoma, IDH-wildtype (GBM), notorious for its inevitable recurrence despite aggressive multi-modal standard of care, presents a pressing need for novel treatment paradigms. The extensive DNA damage caused by the frontline DNA alkylating agent, temozolomide (TMZ) is counteracted by intricate or acquired survival mechanisms. Through functional microRNA screens we identified miR-19b-overexpressing clones possessing extra fitness in presence of escalating doses of TMZ. Our study uncovers a previously unrecognized TMZ resistance mechanism governed by miR-19b. Notably, miR-19b attenuation intensified DNA damage response and CHEK1 and CHEK2 phosphorylation, instigating persistent DNA lesions and consequently priming GBM cells for heightened TMZ cytotoxicity. Mechanistically, we showed that miR-19b exerts its function by targeting PPP2R5E, a subunit of protein phosphatase PP2A, frequently downregulated in GBM. We uncovered that the elevated DNA damage response in the miR-19b-attenuated cells was a consequence of enhanced nuclear and mitochondrial ROS production. This in turn, induced ROS-mediated senescence, and an intriguing susceptibility to ferroptosis, possibly due to increased ROS-mediated lipid peroxidation. Of note, all these phenotypes were reversed in GBM cells with concomitant miR-19b and PPP2R5E attenuation, demonstrating that miR-19b exerts its role in TMZ resistance by targeting PPP2R5E. In line with this finding, an orthotopic human-derived glioblastoma stem cell xenograft model confirmed that PPP2R5E attenuation not only decreases TMZ cytotoxicity in the brain, but also at the spinal metastatic location. Consistently, treating cells with the PP2A-activating drug FTY720 or knocking down endogenous PP2A-inhibiting proteins mirrored the effects of miR-19b attenuation in enhancing TMZ cytotoxicity. This intricate interplay between miR-19b and PPP2R5E underscores a novel strategy to modulate the TMZ response, highlighting promising results in our pre-clinical models. In conclusion, our findings advocate for the therapeutic targeting of the miR-19b/PPP2R5E regulatory axis as a potential novel strategy in the pursuit of effective therapeutic interventions for the formidable recurrent GBM tumours.

CTNI-55. A PHASE 0/1B STUDY OF AZD1390 PLUS RADIOTHERAPY IN NEWLY DIAGNOSED, MGMT-UNMETHYLATED AND RECURRENT GLIOBLASTOMA PATIENTS

Abstract BACKGROUND ATM inhibition is hypothesized to potentiate the effects of radiation by preventing acute phase DNA damage repair. This Phase 0/1b study evaluated the pharmacokinetics (PK) and pharmacodynamics (PD) of AZD1390, a first-in-class ATM inhibitor, in combination with radiation in newly-diagnosed and recurrent GBM patients (NCT05182905). METHODS All patients received 3 days of AZD1390 prior to planned resection at 2-4, 4-6 or 23-25 hrs following the final dose (120/300mg for nGBM and 400mg for rGBM). Tumor tissue, cerebrospinal fluid (CSF), and plasma were collected. Total and unbound drug concentrations were measured using validated LC-MS/MS methods. ATM inhibition was assessed via ex vivo tissue radiation, quantifying pRAD50 levels compared to non-radiated control. A PK ‘trigger’ determined eligibility for Phase 1b and patients exceeding the PK threshold (2 nM unbound drug levels in Gd-non-enhancing tumor region) were eligible for therapeutic dosing of AZD1390 plus radiotherapy. RESULTS Thirty nGBM patients and twenty-nine rGBM patients were enrolled. Forty-eight out of the forty-nine evaluable patients exceeded the PK threshold and qualified for therapeutic dosing. The mean unbound concentrations of AZD1390 in Gd-nonenhancing tumors of both nGBM and rGBM patients were significantly above the threshold at all dose levels and time intervals. Following 5Gy ex vivo radiation of surgical specimens, pRAD50 expression was significantly suppressed in AZD1390-treated patients compared to untreated controls. To date, 6 MGMT-unmethylated nGBM patients and 15 rGBM patients were enrolled in the Phase 1b component of the study, with median clinical follow-up of 7.0 months. Median PFS and OS have not been reached in the nGBM population. Median OS for rGBM patients was 15.4 months. CONCLUSION AZD1390 is well-tolerated in both newly-diagnosed and recurrent GBM patients, achieving pharmacologically relevant concentrations in Gd-nonenhancing tumor tissue, and suppressing radiation-induced increase in pRAD50 levels. These data are the first to demonstrate AZD1390-mediated PD and PK responses in nGBM and rGBM patients. Clinical outcomes data are maturing and will be reported.

CTNI-17. A PHASE 2 STUDY OF SAFETY AND EFFICACY OF CONCURRENT ACT001 AND RADIATION TREATMENT FOLLOWED BY ACT001 MAINTENANCE THERAPY IN NEWLY DIAGNOSED PEDIATRIC PATIENTS WITH DIFFUSE INTRINSIC PONTINE GLIOMA (DIPG)

Abstract BACKGROUND ACT001, an oral parthenolide derivative targeting NF-κB and STAT3 pathways, has shown activity in preclinical DIPG model and dose-finding study in patients with diffuse midline glioma. We further evaluated safety and activity of ACT001 in newly diagnosed DIPG patients and presented the interim data from exploratory stage of this phase 2 study. METHODS Eligible patients ≥ 5 and ≤ 15 years old were treated with concurrent ACT001 and standard radiation followed by ACT001 single agent treatment in this single arm, open label, multicenter phase 2 study. Tumor lesions were evaluated at baseline, 4 weeks and then every 8 weeks after the end of radiation therapy per RAPNO criteria with ORR as primary endpoint. Interim data analysis was performed when data from approximately 20 efficacy evaluable patients became available during the exploratory stage of this study. RESULTS Among 30 patients enrolled since Sept, 2023, 27 took at least one dose of ACT001 by April 30th, 2024, the data cutoff date (with exception for May 15th as the MRI cutoff date). While 3 patients were quickly taken off study due to a disease progression or consent withdrawal, 17 out of 27 patients finished at least one post-radiation MRI exam whereas MRI results are pending for 7 other patients by this interim analysis. Median age was 8 years old and male to female patient ratio is 17:10. The median LPS score is 70.0. Among 17 efficacy evaluable subjects, 8 patients exhibited partial response (6 confirmed) including one with a deep tumor reduction (-91.7%) noted three months after end of radiation. Among 9 other evaluable patients, 5 and 4 exhibited ongoing stable disease and progressive disease respectively. Subject 05001 was considered PD despite confirmed objective response for the target lesion upon development of new lesions. Two patients withdrew consent after finishing first post-radiation MRI scans despite initial tumor burden reduction which were both close to PR criteria. Patients tolerated concurrent ACT001 and radiation well. In total, 289 TEAE and 184 TRAE events were reported in 23 and 22 patients respectively. There were two ACT001-related grade 3 or 4 adverse events including one grade 4 hemorrhagic tumor necrosis (a SUSAR event and the only ACT001 related SAE) likely due to a therapeutic effect of ACT001 and one clinically insignificant grade 3 decreased lymphocyte count. Most common TRAE were manageable grade 1 or 2 events such as weight loss (15/184), vomiting (71/184), decreased lymphocyte count (13/184) and abdominal bloating (7/184). No study discontinuation occurred due to ACT001 or radiation related TRAEs. Conclusion. Concurrent ACT001 and radiation treatment was well tolerated. Preliminary evidence of anti-tumor activity was shown in about 50% efficacy evaluable DIPG patients. It is worthwhile to explore ACT001 and temozolomide combination in future study based on safety and efficacy signal from DIPG and recurrent GBM studies. The confirmatory stage of this study is in planning to further evaluate the anti-tumor efficacy signal of this NF-κB and STAT3 dual inhibitor.

DESIGN AND SET UP OF A RANDOMISED CONTROLLED TRIAL OF MEDICINAL CANNABINOIDS IN RECURRENT GLIOBLASTOMA - THE ARISTOCRAT TRIAL

Abstract AIMS ARISTOCRAT is a unique, randomised, double-blind, placebo-controlled phase II trial of cannabinoids (nabixo- mols) alongside temozolomide in patients with MGMT-methylated recurrent GBM and is open to recruitment in 12 centres across the UK. It was rapidly funded through a crowdfunding campaign organised by The Brain Tumour Charity during the COVID-19 pandemic. METHOD This pragmatic phase II randomised trial was designed and set up by a multi-disciplinary team of co-applicants and trial management group (TMG) members comprising of clinicians, statisticians, trialists, Patient & Public Involvement (PPI), pharmacists and quality of life (QoL) researchers. The protocol randomises on a 2:1 ratio between nabiximols or matched placebo with standard dose temozolomide in patients at first recurrence of IDH wild-type GBM. Unique aspects include self-titration of nabiximols based on individual tolerance, and fully blinded randomisation with matched placebo. The primary outcome measure is overall survival time with key secondary outcomes including survival at 6, 12 and 24 months, progression-free survival time, health-related QoL and adverse events. Intermediate assessment of feasibility to confirm safety, compliance and achievability of recruitment will be undertaken after 40 patients are randomised. PPI input has been critical in the trial and patient-facing information design. RESULTS The trial has promoted a high level of patient and public interest, including press coverage. The trial aims to recruit a total of 234 patients over an 18 month period. CONCLUSION ARISTOCRAT will provide unique, robust clinical data on the role of nabiximols (combined with temozolomide) in improving overall survival and the impact on QoL for patients with recurrent GBM and is the first of its kind in cancer patients.

Local Delivery of Irinotecan to Recurrent GBM Patients at Reoperation Offers a Safe Route of Administration.

Glioblastomas are impossible to completely resect and almost always recur at the borders of the resection margin. There is no established chemotherapy regimen available to patients who recur, while systemic treatment is hampered by the blood-brain barrier. Here, we report on the first evaluation in humans of the intraparenchymal injection of irinotecan into the resection cavity after surgical resection of recurrent glioblastoma patients. The cytotoxicity of irinotecan was compared to SN-38 in primary cells from recurrent glioblastoma patients. Irinotecan was injected at multiple (~30) sites of the resection cavity wall at a depth of 3 to 5 mm. SN-38 was more cytotoxic than irinotecan at concentrations below 1 µM due to enzyme kinetics. The intraparenchymal administration of irinotecan was safe, with good wound healing and an absence of swelling, inflammation, or pseudo-abscess formation. The median survival post irinotecan administration was 32.6 weeks. The median overall survival was 30.5 months, with a two-year survival rate of 56%. This study demonstrates that local delivery of irinotecan into the brain parenchyma offers a safe route of administration over systemic delivery in the treatment of recurrent glioblastoma.

Surgical window of opportunity trial reveals mechanisms of response and resistance to navtemadlin (KRT-232) in patients with recurrent glioblastoma.

Tissue sampling during this clinical trial allowed us to assess mechanisms of response and resistance associated with navtemadlin treatment in recurrent GBM. We report that clinically achievable doses of navtemadlin induce pharmacodynamic effects in tumor tissue, and suggest combinations with standard-of-care chemotherapy for durable clinical benefit.

Preclinical evaluation of CXCR4 peptides for targeted radionuclide therapy in glioblastoma

BackgroundGlioblastoma (GBM), is the most fatal form of brain cancer, with a high tendency for recurrence despite combined treatments including surgery, radiotherapy, and chemotherapy with temozolomide. The C-X-C chemokine receptor 4 (CXCR4) plays an important role in tumour radioresistance and recurrence, and is considered as an interesting GBM target. TRT holds untapped potential for GBM treatment, with CXCR4-TRT being a promising strategy for recurrent GBM treatment. Our study focuses on the preclinical assessment of different 177Lu-labelled CXCR4-targeting peptides, CTCE-9908, DV1-K-DV3, and POL3026 for GBM treatment and exploring some of the radiobiological mechanisms underlying these therapies.ResultsAll three DOTA-conjugated peptides could be radiolabelled with 177Lu with > 95% radiochemical yield. Binding studies show high specific binding of [177Lu]Lu-DOTA-POL3026 to U87-CXCR4 + cells, with 42% of the added activity binding to the membrane at 1 nM, and 6.5% internalised into the cells. In the presence of the heterologous CXCR4 blocking agent, AMD11070, membrane binding was reduced by 95%, a result confirmed by quantitative in vitro autoradiography of orthotopic GBM xenograft sections. An activity-dependent decrease in cell viability was observed for [177Lu]Lu-DOTA-DV1-K-DV3 and [177Lu]Lu-DOTA-POL3026, along with a slight increase in the induction of apoptotic markers. Additionally, the expression of γH2AX increased in a time-and activity-dependent manner. Ex vivo biodistribution studies with [177Lu]Lu-DOTA-POL3026 show uptake in the tumour reaching a SUV of 1.9 at 24 h post-injection, with higher uptake in the kidneys, lungs, spleen, and liver. Dosimetry estimations show an absorbed dose of 0.93 Gy/MBq in the tumour. A blocking study with AMD11070 showed a 38% reduction in tumour uptake, with no significant reduction observed in µSPECT imaging. Although no brain uptake was observed in the ex vivo biodistribution study, autoradiography on U87-CXCR4 + tumour inoculated mouse brain slices shows non-specific binding in the brain, next to high specific binding to the tumour.ConclusionsIn conclusion, we compared different 177Lu-radiolabelled CXCR4-targeting peptides for their binding potential in GBM, and demonstrated their varied cytotoxic action against GBM cells in vitro, with POL3026 being the most promising, causing considerable DNA damage. Though the peptide’s systemic biodistribution remains to be improved, our data demonstrate the potential of [177Lu]Lu-DOTA-POL3026 for CXCR4-TRT in the context of GBM.

Improving Glioblastoma Multiforme Recurrence Prediction through Integrated Radiomics and Deep Learning Techniques

Glioblastoma multiforme (GBM) is one of the most lethal forms of brain cancer, with a five-year survival rate of only 4% to 5%. The recurrence rate is alarmingly high, reaching up to 90%. While tumor-treating fields have shown potential in extending survival, their efficacy in treating recurrent GBM remains limited. This study aims to leverage Deep Learning (DNN) to predict the recurrence of GBM in patients, both pre- and post-surgery. Utilizing advanced computational techniques, this research employs radiomics to analyze brain tumor images, aiding clinicians in identifying tumor spread, predicting post-surgical recurrence, and estimating patient survival. Pre-surgery, Multi-Parametric Magnetic Resonance Imaging (MP-MRI) scans are used to detect tumor locations and forecast potential recurrences. To enhance image processing, Z-score normalization and spatial resampling are applied. Additionally, a model was developed to address the issue of imbalanced data in medical imaging. The study utilized Contrast-Enhanced T1-Weighted Imaging (CE-T1WI) MRI to assess treatment effectiveness and predict recurrence-free survival. A Deep Neural Network was trained to forecast tumor recurrence, identifying patients at risk of early recurrence. Feature extraction from brain images was performed using the Inheritable Bi-Objective Combinatorial Genetic Algorithm. The accuracy of the recurrence predictions was validated and compared against other models, including CNN Inception-V3, CNN AlexNet, and VGG16, using the Python programming language. Results indicate that the proposed method surpasses existing techniques by 3%, 4%, and 5% in accuracy, specificity, and sensitivity, respectively. This research demonstrates that in a retrospective patient population, predictions of patient survival and time to recurrence exhibit high sensitivity, specificity, and accuracy, offering a promising tool for improving GBM management and patient outcomes.