Recurrent Glioma Research Articles

10082-RT-1 LONG-TERM RESULTS OF A BNCT PHASE II CLINICAL TRIAL USING AN ACCELERATOR-BASED NEUTRON SOURCE FOR PATIENTS WITH RECURRENT GLIOBLASTOMA

Abstract PURPOSE Accelerator-based neutron sources have received regulatory approval and boron neutron capture therapy (BNCT) for head and neck cancer has been introduced into clinical treatment in earnest. BNCT is a radiotherapy with cell-selective characteristics, and its application to highly invasive malignant gliomas (MG) is the origin of its development. This study reports the long-term results of a phase II study of accelerator-based BNCT (AB-BNCT) using a cyclotron-based neutron source (BNCT30) and a boronophenylalanine product (SPM-011) in patients with recurrent MG. METHODS A phase 2 clinical trial (JG002) in 27 patients with recurrent malignant glioma (MG) (24 with glioblastoma (GB)) was conducted using SPM-011 and BNCT30. Eligibility criteria were radiation re-irradiation with MG not previously treated with bevacizumab and patients relapsing after standard of care (radiotherapy and chemotherapy with temozolomide). The primary endpoint was one-year survival from BNCT treatment, and secondary endpoints included median overall survival (mOS) and median progression-free survival (mPFS). The 1-year survival and mOS of patients with relapsed GB in JG002 were 79.2% (95% CI: 57.0-90.8) and 18.7 months, respectively. The current long-term observation resulted in an mOS of 19.2 months (95% CI: 13.1-24.8) and survival rates of 33.3 and 20.8% at 2 and 3 years from treatment, respectively. The adverse event was cerebral edema, and 21 of the 27 patients received bevacizumab treatment after decision of disease progression (PD) on imaging. CONCLUSION AB-BNCT showed an acceptable safety and survival benefit in relapsed MG, predominantly GB. Following BNCT treatment, the tumor may have shown a contrast enhancement in the irradiated field, with associated brain edema. BNCT showed a survival benefit in patients with recurrent malignant gliomas, even in the long term.

Focused ultrasound combined with radiotherapy for malignant brain tumor: a preclinical and clinical study.

Blood-brain barrier (BBB) remains to be the major obstacle to conquer in treating patients with malignant brain tumors. Radiation therapy (RT), despite being the mainstay adjuvant modality regardless of BBB, the effect of radiation induced cell death is hindered by the hypoxic microenvironment. Focused ultrasound (FUS) combined with systemic microbubbles has been shown not only to open BBB but also potentially increased regional perfusion. However, no clinical study has investigated the combination of RT with FUS-BBB opening (RT-FUS). We aimed to provide preclinical evidence of RT-FUS combination in GBM animal model, and to report an interim analysis of an ongoing single arm, prospective, pilot study (NCT01628406) of combining RT-FUS for recurrent malignant high grade glioma patients, of whom re-RT was considered for disease control. In both preclinical and clinical studies, FUS-BBB opening was conducted within 2h before RT. Treatment responses were evaluated by objective response rate (ORR) using magnetic resonance imaging, progression free survival, and overall survival, and adverse events (AE) in clinical study. Survival analysis was performed in preclinical study and descriptive analysis was performed in clinical study. In mouse GBM model, the survival analysis showed RT-FUS (2Gy) group was significantly longer than RT (2Gy) group and control, but not RT (5Gy) group. In the pilot clinical trial, an interim analysis of six recurrent malignant high grade glioma patients underwent a total of 24 RT-FUS treatments was presented. Three patients had rapid disease progression at a mean of 33days after RT-FUS, while another three patients had at least stable disease (mean 323days) after RT-FUS with or without salvage chemotherapy or target therapy. One patient had partial response after RT-FUS, making the ORR of 16.7%. There was no FUS-related AEs, but one (16.7%) re-RT-related grade three radiation necrosis. Reirradiation is becoming an option after disease recurrence for both primary and secondary malignant brain tumors since systemic therapy significantly prolongs survival in cancer patients. The mechanism behind the synergistic effect of RT-FUS in preclinical model needs further study. The clinical evidence from the interim analysis of an ongoing clinical trial (NCT01628406) showed a combination of RT-FUS was safe (no FUS-related adverse effect). A comprehensive analysis of radiation dosimetry and FUS energy distribution is expected after completing the final recruitment.

Abstract LB_A12: Initial results from 2 Phase I studies of NMS-03305293, a selective PARP1 inhibitor

Abstract Background PARP-1 has a well-established role in DNA repair. PARP-1 selective inhibitors are a new subclass of PARPi that offer potential for improved tolerability. NMS-03305293 (NMS-293) is an oral, brain-penetrant PARP-1 selective inhibitor with strong antitumor activity in BRCA mutated preclinical models. Furthermore, NMS-293 is synergistic with temozolomide (TMZ) in glioblastoma mouse models. Methods Two phase I/I-II dose-escalation/expansion studies assessed safety, tolerability, and preliminary antitumor activity of NMS-293. Both are actively recruiting. In PARPA-293-001 (NCT04182516), NMS-293 was administered orally, ranging from 20 mg (QD) to 160 mg (BID) for 21 or 28 days on 28-day cycle in adult patients with advanced/metastatic, relapsed/refractory solid tumors who have exhausted standard treatment options. In PARPA-293-002 (NCT04910022), NMS-293 was administered in a range of doses orally, QD or BID on days 1-7 plus TMZ 150mg/m2 QD on days 1-5 in repeated 28-day cycle in adult patients with recurrent diffuse gliomas. Tumor responses were measured by investigator-assessed RANO criteria. Results The unpooled safety database at the data-cut-off (02-AUG-23), includes 45 patients in PARPA-001 and 21 patients in PARPA-002. PARPA-001 showed an MTD of 100 mg BID for 28 days on a 28-day cycle, a dose with meaningful PK relative to preclinical activity. PARPA-002 dose finding is ongoing with no DLTs as of cutoff date. The most frequent (≥10%) any-grade treatment related adverse events (TRAEs) in PARPA-001 were reversible QTcF prolongation, nausea, asthenia, decreased appetite and vomiting, mainly mild/moderate. In PARPA-002, with discontinuous NMS-293 plus TMZ, no G≥3 TRAEs were reported. The most frequent (≥10%) any-grade TRAEs were: nausea, fatigue, vomiting, decreased appetite, and platelet count decreased, mainly G1 adverse events. Overall, no dose-dependent trends of myelosuppression have been observed. 14 recurrent glioma patients across dose levels in PARPA-002 were evaluable for tumor response. A patient with glioblastoma had confirmed partial response (PR) with duration 7.6+ weeks, remaining on treatment at cutoff date. A patient with grade 3 IDH-mutant astrocytoma had unconfirmed PR with ongoing tumor shrinkage at 16.1+ weeks. A patient with glioblastoma had complete radiological disappearance of enhancing non-target lesions, remaining on treatment at cutoff date. NMS-293 PK profiles showed an increase in exposure with the dose with approximately 5 to 13 hours half-life. Conclusion NMS-293, a PARP-1 selective, brain penetrant inhibitor was well tolerated in phase I clinical trials with no dose dependent trends of myelosuppression. Furthermore, NMS-293 showed encouraging clinical activity in combination with TMZ in difficult-to-treat recurrent glioma patients. Citation Format: Marjolein Geurts, Dorothee Gramatzki, Sara Merler, Matteo Duca, Fabio Girardi, Ugur T. Sener, Domenico Roberti, Grazia Saturno, Patrizia Crivori, Alessia Montagnoli, Lisa Mahnke, Siqing Fu, Paola Gaviani, Kurt A. Jaeckle, Jian Zhang, Yehui Shi, Valentina Guarneri, Michael Weller, Sani H. Kizilbash, Martin J. van den Bent, Michele Milella, Silvia Damian. Initial results from 2 Phase I studies of NMS-03305293, a selective PARP1 inhibitor [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr LB_A12.

The potential use of crossed cerebro-cerebellar activation to evaluate language reorganization: A case study of recurrent malignant glioma

The potential use of crossed cerebro-cerebellar activation to evaluate language reorganization: A case study of recurrent malignant glioma

Development of a "Geo-Tagged" tumor sample registry: intra-operative linkage of sample location to imaging.

There is a growing body of literature documenting glioma heterogeneity in terms of radiographic, histologic, molecular, and genetic characteristics. Incomplete spatial specification of intraoperative tumor samples may contribute to variability in the results of pathological and biological investigations. We have developed a system, termed geo-tagging, for routine intraoperative linkage of each tumor sample to its location via neuronavigation. This is a single-institution, IRB approved, prospective database of undergoing clinically indicated surgery. We evaluated relevant factors affecting data collection by this registry, including tumor and surgical factors (e.g. tumor volume, location, grade and surgeon). Over a 2-year period, 487 patients underwent craniotomy for an intra-axial tumor. Of those, 214 underwent surgery for a newly diagnosed or recurrent glioma. There was significant variation in the average number of samples collected per registered case, with a range of samples from 2.53 to 4.75 per tumor type. Histology and grade impacted on sampling with a range of 2.0 samples per tumor in Grade four, IDH-WT gliomas to 4.5 samples in grade four, IDH-mutant gliomas. The range of cases with sampling per surgeon was 6 to 99 with a mean of 47.6 cases and there was a statistically significant differences between surgeons. Tumor grade did not have a statistically significant impact on number of samples per case. No significant correlation was found between the number of samples collected and enhancing tumor volume, EOR, or volume of tumor resected. We are using the results of this analysis to develop a prospective sample collection protocol.

RTID-07. A RANDOMIZED WINDOW OF OPPORTUNITY TRIAL WITH DOSE ESCALATION TO EVALUATE FLUOXETINE AND TEMOZOLOMIDE IN GLIOMA

Abstract The blood brain barrier limits the efficacy of many drugs in brain tumors. Fluoxetine (Prozac) is FDA-approved and brain penetrant. Preclinical studies show synergy between fluoxetine and temozolomide (TMZ), resulting in lysosomal stress and enhanced DNA damage in human-derived glioma in vitro and in vivo. We present our randomized surgical window of opportunity trial (NCT05634707) in patients with recurrent IDH wild type glioma. The primary objective is to evaluate if fluoxetine induces tumoral lysosomal stress while exploratory objectives will determine if combination therapy enhances tumor DNA damage. We will randomize 30 patients, ≥ 24yo, with recurrent glioma and who are eligible for re-treatment with TMZ (MGMT methylated, progression >6 months post TMZ). Following informed consent, patients will be randomized 1:2 to control or experimental arms. Control patients will receive 50 mg/m2 TMZ for 7 days pre-resection. The experimental arm will receive 20 mg/day fluoxetine for 5 days before escalating to 40 mg/day. If < 3/10 participants receiving 40mg/day experience dose-limiting toxicity (DLT), subsequent experimental arm patients will escalate to 60 mg/day. All experimental arm participants will receive 50 mg/m2 TMZ for 7 days after starting fluoxetine, starting 21 days pre-resection. The regimen of 50 mg/m2 TMZ for 7 days is based on a similar pre-surgical trial combining TMZ with experimental therapy (NCT05188508). This reduced dose was chosen to limit potential synergistic toxicities like thrombocytopenia or neutropenia. Following resection, patients will continue TMZ, initially at reduced dose for the first post-op cycle, before reverting to standard doses of 150-200mg/m2 (up to 12 cycles or progression). All patients (control and experimental) will be offered fluoxetine post-operatively. The primary study outcome will be quantification of tumoral lysosomal stress via Lysosomal-associated membrane protein 1 (LAMP1) expression while DNA damage will be assessed via γH2A histone family member X (γH2AX) using immunohistochemistry.

NIMG-51. RADIOGRAPHIC IMPROVEMENT IN A PATIENT WITH OLIGODENDROGLIOMA UNDERGOING TREATMENT FOR ACUTE MYELOID LEUKEMIA

Abstract INTRODUCTION: The standard chemotherapy for treating oligodendroglioma consists of a combination of procarbazine, lomustine, and vincristine (PCV). The combination of hypomethylating agents, like azacitidine, and BCL2 inhibitors like venetoclax have not been formally studied in the treatment of glial tumors. The combination of these two drugs is commonly used to treat acute myeloid leukemia, with IDH mutant disease being a particularly sensitive subtype. CASE REPORT: A 48-year-old man was diagnosed with a left frontal, grade II oligodendroglioma following multiple episodes of speech arrest and right-hand numbness. He was subsequently treated with six cycles of PCV with a minor response. After slow progression over eight years, the tumor started displaying contrast enhancement. While planning for radiation therapy, he presented to the Emergency Department with severe fatigue and shortness of breath. Workup led to a diagnosis of pure erythroid leukemia, with molecular and cytogenetic studies suggesting a neoplasm related to prior exposure to cytotoxic chemotherapy. He was treated with three cycles of venetoclax and azacitidine, but unfortunately, the erythroleukemia progressed after a transient response to this treatment. On the other hand, however, a re-staging MRI brain showed a remarkable reduction of his tumor size of approximately 40% per RANO criteria. The patient was off steroids and remained neurologically asymptomatic during this time. Discussion: The use of azacitidine for the treatment of IDH mutant gliomas has been reported in the literature, with mixed results that might suggest at least some benefit in a subtype of patients. Other studies have also suggested that the BCL2 gene is associated with treatment resistance and tumor recurrence in gliomas. Our case presents an interesting observation that combining a hypomethylating agent with a BCL2 inhibitor might convey clinical and radiographic benefits for patients with relapsed IDH mutant gliomas.

BIOM-16. LONGITUDINAL GLIOMA CEREBROSPINAL FLUID CELL-FREE DNA FOR MONITORING AND TREATMENT RESPONSE ASSESSMENT

Abstract Few methods exist via which to assess treatment response with high fidelity in gliomas. While CSF has previously been used as a source of cfDNA, it remains unknown how cfDNA abundance and sequencing changes throughout treatment and inevitable recurrence in gliomas. We utilized our biobank of longitudinal intracranial CSF specimens to determine the potential utility of CSF cfDNA as a monitoring tool for treatment response in patients with gliomas. Longitudinal CSF specimens were acquired via Ommaya reservoirs (NCT04692337) or ventriculoperitoneal shunts (NCT04692324) in patients with gliomas. cfDNA was extracted from 1-5 mL of CSF, and next-Generation sequencing or low-pass whole genome sequencing (LPWGS) was performed by Predicine, Inc. CSF acquired prior to versus after resection demonstrated an increase in quantified cfDNA (2.97x, range: 1.58-5.26x), consistent with the impact of increased parenchymal disruption and closer contact with CSF. Thereafter, CSF cfDNA continued to decrease throughout chemoradiation and adjuvant treatment and increased at recurrence, including in patients co-enrolled in immunotherapy trials for IL-7 agonists and pembrolizumab. Copy number burden (CNB) increased by the time of recurrence in three patients with known disease progression, and continued to decrease throughout immunotherapy treatment in one patient despite concerns of pseudoprogression. In one patient with a hypermutated glioblastoma, CSF cfDNA revealed over 59 genomic alterations, including MAP2K1, KIT, and PDGFRA, excluding even more variants of unknown significance, each of which had been detected in sequencing of the tissue acquired at resection and subsequently decreased with chemoradiation. In another patient with a known progressing EGFR-amplified GBM, over 200 new variants were identified by the patient’s final sample and EGFR copy number increased from 2 to over 30. In conclusion, cfDNA analysis over a patient’s disease course, including resection and treatment with standard-of-care and experimental therapies, may be of use for disease monitoring and treatment response.

CTNI-50. UPDATE REPORT OF THE RESPECT-GBM PHASE I/IIA DOSE ESCALATION TRIAL OF RHENIUM-186 NANOLIPOSOME (186RNL) IN RECURRENT GLIOMA [RGBM] VIA CONVECTION ENHANCED DELIVERY (CED)

Abstract BACKGROUND A Phase1/2a dose-escalation trial was initiated to determine the safety and recommended phase2 186RNL-dose(RP2D). Liposomal-rhenium-186(186RNL) is a source of high-energy beta-particles with gamma-photons representing attractive brain CED properties. METHODS A 3 + 3 Phase1 design was implemented per protocol [modified-Fibonacci dosing sequence]. We report safety and overall survival (OS) in 27 patients assigned to cohorts1-8. Patients with biopsy proven recurrent glioma had computerized treatment planning and placement of up to 5 intracranial catheter(s) single CED-186RNL administration. Whole body planar and SPECT/CT imaging through ~1 week following treatment was performed. Patients were followed for safety, sufficiency of delivery and OS. The significance of variation in OS was assessed with a 2-sided logrank test with α = 0.05. RESULTS Cohorts dosing ranged from 1mCi-in-0.6mL to 41.5mCi-in-16.3ml, MTD not reached, and no CED failures. No dose limiting toxicities were observed. Most common AEs were pre-existing GBM related signs/symptoms [weakness, fatigue, headache, seizure, scalp discomfort after CED] and >80% of AEs unrelated/unlikely relationship. Median absorbed radiation dose to the tumor (MARDT) was 308.4 Gy (8.9 Gy to 739.5 Gy). Patients were stratified by MARDT (< 100 Gy, ≥100 Gy). In all patients (N = 27), the median overall survival (OS) was 8 months (m), 95% CI 5 m to 13 m). In those receiving <100 Gy (N = 10), the median OS was 5 m (95% CI 1 m to 11 m) and in those with ≥ 100 Gy (N = 17) the median was 12 m (95% CI 5 m to 30 m), p < 0.001. CONCLUSION A single administration of 186RNL by CED in recurrent glioma patients is feasible, safe, and potentially effective in increasing overall survival when >100Gy radiation is delivered to the tumor. A RP2D of 22.3mCi in 8.8mL was selected for patients with tumor size of ≤20mL in the planned Phase 2B.

RADT-30. PROTON THERAPY FOR RE-IRRADIATION OF RECURRENT GLIOMA

Abstract BACKGROUND Proton therapy may improve the side effect profile of re-irradiation for recurrent glioma by limiting the overlap with previous radiation dose received by the brain. Limited data exist regarding the outcomes or side effects after proton re-irradiation. METHODS We retrospectively reviewed the charts of 43 consecutive adult patients with glioma treated with uniform scanning or pencil beam scanning proton re-irradiation from June 2014-June 2022. Outcomes were estimated utilizing Kaplan-Meier analysis. RESULTS Median age of the cohort was 45 years (range 19-74). Initial histologic diagnosis was glioblastoma for 18 (42%), astrocytoma for 16 (37%), oligodendroglioma for 8 (19%) and diffuse glioma NOS for 1 (2%) patient. The median initial prescription dose was 60 Gy (range 54-61.2 Gy) with 86% receiving concurrent temozolomide. The median interval between initial radiation therapy (RT) and re-irradiation was 51 months (range 6-185 months). The median re-irradiation dose delivered was 37.5 cobalt gray equivalent (CGE) in 15 fractions (range 6-50.4 CGE in 2-28 fractions) with 34 patients receiving this dose fractionation. Concurrent systemic therapy included bevacizumab (8), chemotherapy (5), immunotherapy (2) or none (28). Overall, 40 (93%) finished the planned course and three stopped early given progression. Median survival was 11.5 months for the full cohort (95% confidence interval: 6.8-13.6 months). For patients with glioblastoma, median survival was 6.4 months (95%CI 5.0-13.5 months). For patients without glioblastoma, median survival was 11.6 months (95%CI 9.2-34.3 months). Twelve patients (28%) developed symptomatic pseudoprogression/radiation necrosis, with ten requiring increased steroids and four requiring bevacizumab. CONCLUSIONS Proton re-irradiation was well tolerated in patients with recurrent glioma, with 6.4 and 11.6 month median survival estimates for glioblastoma and non-glioblastoma histologies, respectively. Symptomatic pseudoprogression/radiation necrosis was common. Further study is needed to determine whether proton re-irradiation has improved tolerability compared to photons.

CTIM-10. A SURGICAL WINDOW-OF-OPPORTUNITY CLINICAL TRIAL EVALUATING THE PCSK9 INHIBITOR EVOLOCUMAB IN PATIENTS WITH GLIOMA

Abstract Gliomas evade the immune system by downregulating cell surface expression of major histocompatibility class (MHC)-I. Antagonism of proprotein convertase subtilisin/kexin type 9 (PCSK9) increases MHC-I expression and can enhance checkpoint inhibition in vivo. Evolocumab is an FDA approved monoclonal antibody (mAb) for hyperlipidemia that inhibits PCSK9. However, large constructs such as mAbs typically have limited penetrance across the blood-brain-barrier. We report the preliminary results of a surgical window-of-opportunity study evaluating if Evolocumab administered subcutaneously pre-preoperatively is detectable in tumor tissue from patients with newly diagnosed or recurrent glioma (PESKe; NCT04937413). Twenty contemporaneous control samples are prospectively collected from patients undergoing craniotomy without receiving Evolocumab. Although non-randomized, these specimens provide valuable information for exploratory comparison of the treated and untreated specimens in terms of drug penetrance and MHC-I expression. To date, 24 patients have been enrolled (M: 14, F: 10) with a median age of 46.5. Of these, 5 received pre-procedure subcutaneous Evolocumab (420mg), while the remaining 19 were analyzed as controls. In treated patients, Evolocumab was detectable via mass spectroscopy (LC-MS/MS) in all analyzed cases, including in tumor tissue from both contrast-enhancing and non-contrast-enhancing regions. Ratios of drug in tumor relative to intra-operative blood were markedly higher in samples from contrast-enhancing regions compared to non-contrast enhancing regions (median ratio of tumor to blood of 0.1503 vs 0.0248 respectively). The tumor proteome was also analyzed using LC-MS/MS to quantitate MHC-I and MHC-II proteins. Initial analysis found increased MHC-I (HLA-A, HLA-B, HLA-C) quantitation via mass spectroscopic analysis of the tumor proteome in treated samples compared to contemporaneous untreated controls. No significant adverse events have been reported in those who received pre-procedure Evolocumab. Ongoing analyses will seek to determine whether increased MHC-I quantities in tumor correspond with increased cell surface expression via immunofluorescence and immunohistochemistry.

INNV-25. PROLONGED FOLLOW-UP OF AN OLIGODENDROGLIOMA PATIENT WITH HISTORY OF TUMOR TREATING FIELDS (TTF) AS POST CHEMO-RADIATION MAINTENANCE THERAPY

Abstract INTRODUCTION: Recurrence of low and high-grade gliomas are common after radiation and chemotherapy. Despite continued research on glioma’s management, there is limited knowledge regarding the role of maintenance treatment after standard radiation and chemotherapy therapy. Tumor Treating Fields as maintenance therapy after radiation and chemotherapy may potentially help prevent recurrence of oligodendroglioma. Case Report: A 35-year-old male developed headaches and a non-enhancing mass was detected on his brain MRI in 2011. Observation was advised by his surgeon. The patient presented with seizures in early 2014, and his brain MRI found the mass developed new enhancement. In late 2014, the patient had multiple seizures, and significant progression of the tumor was discovered. The patient underwent craniotomy and biopsy in the middle cerebral artery distribution area in early 2015. Pathology reported grade II oligodendroglioma; however, a biopsy might have missed the high-grade glioma region. His brain MRI showed a significant enhancing lesion, which was clinically also consistent with grade III oligodendroglioma due to rapid growth. Radiation was conducted followed by 6 cycles of PCV chemotherapy throughout 11 months. Post-radiation-chemotherapy brain MRI was stable with a moderate size residue tumor at the right insula region. Following patient wishes, NovoTTF-100A, or Optune, was administered 6 weeks after completion of chemotherapy as maintenance therapy for 2 years to prevent tumor progression. Now, after 5 years being off Optune, the patient is full-functional, and his brain MRI is stable without tumor progression. Discussion: Our case highlights the potential effect of Tumor Treating Fields as maintenance therapy after initial radiation and chemotherapy for lower and higher grade oligodendrogliomas. The patient had rapid tumor progression on brain MRI prior to treatment and only underwent a biopsy without resection, yet uncommonly, remains survival and full functional since initial image diagnosis 12 years ago and tissue diagnosis 8 years ago.

CTIM-41. ONCOLYTIC IMMUNOTHERAPY LINKS IMMUNOACTIVATION TO SUBJECT SURVIVAL IN PHASE I TRIAL OF RECURRENT GLIOBLASTOMA

Abstract A “first-in-human” phase 1 trial of intralesional injection of CAN-3110, an immunotherapeutic oncolytic based on herpes simplex virus 1 (HSV1), was conducted in 41 subjects with recurrent high-grade glioma (rHGG). The impact of CAN-3110 on the tumor immune microenvironment was assessed using immunohistochemistry, multiplexed immunofluorescence, TCR-beta DNA sequencing, and bulk RNA sequencing of paired pre- and post-treatment samples. These analyses were combined with patient features to identify potential biomarkers of therapy response in rHGG. In IDH wild type recurrent glioblastoma (IDHwt rGBM) patients, post-treatment survival times were positively associated with positive pre-treatment HSV1 serology after controlling for additional covariates such as tumor volume, age, gender, CAN-3110 dose, etc. (HR = 0.16, p < 0.001, n = 32, CoxPH). Positive HSV1 serology was also significantly associated with clearance of CAN-3110 from injected tumors. Interestingly, increased intratumoral CD8 and CD4 T cell numbers following treatment were positively associated with prolonged survival in HSV1 seropositive patients (p = 0.017 and 0.026, respectively), but not when analyses were conducted including HSV1 seronegative patients. Likewise, post-treatment immune expression signatures (such as for antitumor cytokines, T cell traffic, etc.) were more strongly associated with prolonged survival for HSV1 seropositive patients than for seronegative patients, and most assessed immune signatures only became associated with survival after CAN-3110 treatment. Extended survival was also associated with increased TCR-beta diversity following therapy in both the tumor and in PBMCs. Combined with a lack of observed dose-limiting toxicities and a median post-treatment survival of 14.2 months (95% CI: 9.5-15.7) in IDHwt rGBM patients with positive HSV1 serology, these data provide evidence that intralesional CAN-3110 treatment can instigate immune activation in a traditionally immunologically cold tumor and that this immune activation may influence survival time—particularly when patients have had prior exposure to HSV1. (clinicaltrials.gov NCT03152318).

NCOG-17. RETROSPECTIVE REVIEW OF THE TREATMENT OF VENOUS THROMBOEMBOLISM IN GLIOBLASTOMA PATIENTS RECEIVING BEVACIZUMAB

Abstract Patients with malignant gliomas have an inherently high risk of venous thromboembolism (VTE).1 Bevacizumab is an anti-vascular endothelial growth factor (VEGF) monoclonal antibody commonly used in the treatment of recurrent high-grade gliomas and is known to increase the risk of VTE as well as intracranial hemorrhage.2 Anticoagulation (AC) for VTE also increases the risk intracranial hemorrhage in patients with malignant brain tumors.3 This makes the treatment of VTE in patients with GBM receiving bevacizumab therapy particularly challenging. Here we completed a single center retrospective chart review of patients with glioblastoma (GBM) treated concurrently with anticoagulation for VTE and bevacizumab therapy. The purpose of this review was to assess the safety of concurrent use of these therapies and to note any statistically significant difference in the incidence of hemorrhagic complications between patients treated with anticoagulation at therapeutic versus prophylactic dosing. METHODS: 144 patients with a diagnosis of high-grade glioma and were treated at UCI from 1/1/2019 through 1/1/2022 were screened for the study. 13 GBM patients on treatment with bevacizumab and concurrent anticoagulation were included. Clinical records of these patients were reviewed for the incidence of intracranial hemorrhage or any clinically significant bleeding. RESULTS: The incidence of ICH in GBM patients on concurrent therapy with bevacizumab and anticoagulation was 7.7% and the incidence of other minor bleeding complications was 7.7%. ICH and other minor bleeding was exclusively seen in patients on therapeutic anticoagulant dosing. No bleeding complications were noted in patients on prophylactic AC dosing. CONCLUSION: There is a risk of ICH in patients receiving both bevacizumab and anticoagulation, however compared to historical data, the incidence reported in our study is less than the incidence of ICH in GBM patients on anticoagulation alone. Our study suggests that it is relatively safe to treat patients with these therapies simultaneously.

CTNI-47. DOSE ESCALATION OF ASTX727 IN ADULT PATIENTS WITH RECURRENT/PROGRESSIVE NON-ENHANCING IDH MUTANT GLIOMAS

Abstract BACKGROUND IDH mutant gliomas typically display a hypermethylation pattern known as the glioma CpG island methylator phenotype (G-CIMP) which results in gene activation that promotes gliomagenesis. This study aims to reverse this methylation signature and disrupt tumor growth via treatment with an oral demethylating agent. METHODS This is 2-stage clinical trial investigating oral ASTX727 (decitabine + cedazuridine, a cytidine deaminase inhibitor, as a combination tablet) in patients with recurrent primarily non-enhancing IDH mutant gliomas. The Dose Escalation Stage consisted of a single arm 3 + 3 design. The primary objective was to establish the MTD and assess safety in this patient population. RESULTS Eleven pts (F = 45%, M = 55%) with a median age of 44 yrs (range 26-61 yrs) were enrolled. Two DLTs (grade 4 neutropenia for >72 hrs) were observed in 5 pts enrolled at the starting dose (35 mg decitabine/ 100 mg cedazuridine for 5 consecutive days). Six additional patients were enrolled at dose level -1 (35 mg decitabine/100 mg cedazuridine for 4 consecutive days). There were no DLTs at dose level -1 and this was declared the MTD. Grade ≥ 3 AEs included neutropenia (5 pts), leukopenia (1 pt), lymphopenia (1 pt), hyponatremia (1 pt) and increased ALT (1 pt). Best treatment response was SD in 11 patients. At the time of last follow-up (5/15/23) 10 pts have discontinued treatment (8 for PD, and 2 based on physician decision), 2 pts (18%) have died due to disease progression, 8 pts remain alive and in follow-up, and 1 patient remains on treatment. Median duration on treatment was 212 days (range 36 days – not reached). CONCLUSIONS ASTX727 was well tolerated in patients with recurrent non-enhancing IDH mutant glioma at dose level -1 with no DLTs . A surgical expansion cohort is currently enrolling to confirm drug target engagement and explore pharmacodynamics.

IMMU-29. A CHIMERIC ONCOLYTIC ADENOVIRUS CIRCUMVENTS NEUTRALIZING ANTIBODIES DEVELOPED BY PATIENTS WITH RECURRENT GLIOBLASTOMA TREATED WITH DELTA-24-RGD

Abstract Oncolytic virotherapy holds great potential to treat high-grade gliomas by harnessing virus-mediated oncolysis to stimulate anti-tumor immune responses. However, the efficacy of oncolytic adenoviruses can be hampered by neutralizing antibodies. In this study, we examined sera obtained from a phase 1 clinical trial using oncolytic adenovirus Delta-24-RGD to treat patients with recurrent malignant gliomas. We found that a single intratumoral injection of Delta-24-RGD induced the development of neutralizing antibodies in less than half of the patients but demonstrated remarkable outcomes, with 20% of the patients surviving beyond three years. Conversely, multiple injections of the oncolytic adenovirus induced neutralizing antibodies in 80% of patients (P=0.05) but resulted in no long-term survivors. This inverse correlation led us to further investigate the role of neutralizing antibodies during glioma virotherapy. Examination of Delta-24-RGD-treated murine brain tumors using immunofluorescence displayed colocalization of antibodies and viral proteins. To counteract virus neutralization and maximize oncolysis, we engineered a chimeric virus, Delta-24-RGD-H43m, by replacing the hypervariable regions of the hexon protein from the prevalent serotype 5-based Delta-24-RGD with those from the rare serotype 43. The infectivity, replication, and oncolytic capabilities of Delta-24-RGD-H43m were similar to those of the parental virus. Using clinical trial patient sera, we observed that Delta-24-RGD-H43m displayed significant resilience against the inhibitory effects of neutralizing sera from patients (P=0.01). In murine models with pre-existing immunity to adenovirus, Delta-24-RGD-H43m treatment led to a significantly extended median survival and resulted in a higher percentage of long-term survivors than the parental virus (P=0.005). These results underscore the effectiveness of hexon swapping as a strategy to overcome the dominant immune response against oncolytic viruses, provide valuable insights into the interaction between oncolytic viruses and the host immune system, and lay the foundation to translate to the clinical setting immune-evading virotherapies for glioma patients.

CTIM-05. RESULTS OF SAFETY LEAD IN OF PHASE II TRIAL OF COMBINATION OLAPARIB, TEMOZOLOMIDE, AND PEMBROLIZUMAB FOR PATIENTS WITH IDH-MUTANT GLIOMA

Abstract BACKGROUND Recurrent gliomas are universally fatal with few adequate treatment options. IDH-mutant gliomas may be susceptible to PARP inhibition, thus combination therapy using alkylating agents and checkpoint inhibition could be synergistic. METHODS This is an open label, phase II study of olaparib, temozolomide, and pembrolizumab for patients with recurrent IDH-mutant glioma, grade 2 or 3, with measurable enhancing disease per RANO. Patients received pembrolizumab 200mg IV on day 1 of each 21-day cycle. Oral olaparib 200mg twice daily and temozolomide 50mg/m2 daily were given days 1-7 of cycles 3-11. Here, we report the results of our safety lead in, consisting of the first 6 patients to complete cycle 3. RESULTS A total of seven patients were enrolled to the safety lead-in: 2 women; 5 patients with astrocytoma, 2 oligodendroglioma. Patients had a median age of 45 (range 29-63) and median KPS 90 (range 80-100). Median number of recurrences was 3.5 (range 1-5). All had received prior alkylating therapy and all but 1 patient had received prior RT. No patients were taking steroids at the time of enrollment. Six patients completed the dose-limiting toxicity (DLT) period without any DLTs. One patient experienced clinical progression on pembrolizumab monotherapy prior to the start of combination therapy and was thus replaced. No grade 3 or 4 toxicities were seen through the DLT period. The most common clinical toxicities at least possibly related to treatment were grade 1 and 2 fatigue (n = 4), nausea (n = 3) and constipation (n = 2). Hematological toxicities include grade 1 anemia (n = 2) and decreased platelet count (n = 1). CONCLUSIONS The combination of olaparib, temozolomide, and pembrolizumab was well tolerated in this cohort. Following completion of the safety lead-in, the trial was redesigned to minimize the length of pembrolizumab monotherapy and introduce combination therapy in cycle 1. Enrollment is ongoing. NCT05188508.

NIMG-24. RECURRENT OLIGODENDROGLIOMA DEMONSTRATES EARLY INCREASE IN CEREBRAL BLOOD FLOW AND NORMALIZATION IN RESPONSE TO TREATMENT

Abstract Oligodendrogliomas, molecularly defined by the presence of both IDH mutation and 1p/19q codeletion, are more treatment responsive than other gliomas, and due to short capillary segments, demonstrate elevated CBF regardless of grade or contrast enhancement. Arterial Spin Labeling (ASL) allows noninvasive perfusion imaging assessment of cerebral blood flow (CBF) without contrast administration. Changes in CBF are recognized in association with malignant transformation of gliomas however in the setting of treatment, CBF has only been studied to assist in differentiating radiation treatment effect from progressive glioma. This single center retrospective study was undertaken to evaluate if CBF, measured by ASL, might normalize following treatment of recurrent oligodendrogliomas. Clinical database query identified 151 patients with molecularly confirmed oligodendroglioma, 34 of which had available ASL imaging. Expert reader review of all available MRI sequences, blinded to treatment timeline, were performed by two independent radiologists at a PACS station. There were 6 radiographic recurrences identified and in 5/6 CBF was the first radiographic change. Contrast enhancement did not develop for 1.5-12 months after change in CBF for 4/5 recurrences. ASL imaging before and after non-surgical therapy for recurrent disease was available for 4 patients. Two patients were treated with lomustine, one with bevacizumab and one with proton re-radiation. By the second MRI following treatment initiation, all patients had normalization of CBF. At the first post treatment MRI, 3/4 of patients demonstrated normalization of CBF while only 2/4 demonstrated normalization of dynamic susceptibility contrast-derived cerebral blood volume. During the subsequent 6 months, FLAIR hyperintensities remained stable in all patients. This work supports further study if normalization of ASL-derived CBF may be an early radiographic biomarker for response to treatment, especially in non or minimally enhancing recurrent gliomas.

CTNI-23. SINGLE CELL TRANSCRIPTOMICS, PHARMACOKINETICS, AND PHARMACODYNAMICS OF COMBINED CDK4/6 AND MTOR INHIBITION IN A PHASE 0 TRIAL OF RECURRENT HIGH-GRADE GLIOMA

Abstract Adult High-grade gliomas (HGGs) often exhibit deregulation of RB-CDK4/6 and mTOR signaling pathways. This study investigated tumor single cell transcriptomics, pharmacokinetics, and pharmacodynamics immediately following combined CDK4/6 (ribociclib) and mTOR (everolimus) inhibition in recurrent HGG. 24 patients with recurrent gliomas harboring RB+, CDKN2A/B deletion or CDK4/6 amplification, and PTEN loss or PIK3CA mutations were enrolled in a phase 0 trial. Patients received ribociclib treatment for 5 days before surgery, including six who received ribociclib (400mg QD) plus everolimus (2.5mg QD), and six dose-escalation cohorts (n = 3 each) reaching ribociclib 600mg QD plus everolimus 70mg QW. No dose-limiting toxicities were observed. Validated LC-MS/MS methods determined total and unbound drug concentrations. Preoperative MRI revealed a marked decrease in gadolinium-enhancement in all patients. In gadolinium-nonenhancing tumor regions, the median unbound concentration of ribociclib was 561 nM, while no unbound everolimus concentrations were detected. Ribociclib’s pharmacodynamic effects in surgical specimens were compared with matched archival tissue using IHC. Across IDH-wild-type tumors, there was significant decrease in MIB1 levels between the matched archival and surgical specimens (p < 0.05) suggesting drug-associated cell cycle inhibition. Single nuclei RNAseq (snRNA) analyses were performed on 17 IDH-wild-type recurrent samples treated with ribociclib plus everolimus and 29 IDH-wild-type recurrences treated with standard therapies. Cellular state analysis based on snRNAseq data demonstrated a decreased neural progenitor-like (NPC-like) malignant cell state compared with standard therapies (p < 0.01), indicating inhibition of the CDK4-driven neural progenitor-like cell state. This observation was validated using snRNA and patient-derived glioma cell lines exposed to ribociclib, showing a consistent decrease in NPC-like proportions and cycling cells (p < 0.05). This study highlights the value of integrating pharmacokinetics/pharmacodynamics and snRNA data to assess treatment effects in phase 0 surgical tissues. These findings support further development of ribociclib, but not everolimus, for the treatment of glioma patients.

INNV-06. SIGNIFICANCE OF MOLECULAR DIAGNOSTICS FOR THERAPEUTIC DECISION-MAKING IN RECURRENT GLIOMA

Abstract BACKGROUND Targeted therapies have substantially improved survival in cancer patients with malignancies outside the brain. Whether in-depth analysis for molecular alterations may also offer therapeutic avenues in primary brain tumors remains unclear. We herein present our institutional experience for glioma patients discussed in our interdisciplinary Molecular Tumor Board (MTB) implemented at the Comprehensive Cancer Center Munich (LMU). METHODS We retrospectively searched the database of the MTB for all recurrent glioma patients after previous therapy. Recommendations were based upon next-generation sequencing results of individual patient’s tumor tissue. Clinical and molecular information, previous therapy regimens and outcome parameters were collected. RESULTS Overall, 73 consecutive recurrent glioma patients were identified. In the median, advanced molecular testing was initiated with the third tumor recurrence. The median turnaround time between initiation of molecular profiling and MTB case discussion was 48 ± 75 days (range: 32 - 536 days). Targetable mutations were found for 50 recurrent glioma patients (68.5%). IDH1 mutation (27/73; 37%), EGFR amplification (19/73; 26%) and NF1 mutation (8/73; 11%) were the most detected alterations and a molecular-based treatment recommendation could be made for all of them. Therapeutic recommendations were implemented in 12 cases (24%) and one third of these heavily pretreated patients experienced clinical benefit with at least disease stabilization. CONCLUSION In-depth molecular analysis of tumor tissue may guide targeted therapy also in brain tumor patients and considerable anti-tumor effects might be observed in selected cases. However, future studies to corroborate our results are needed.