Recurrent High-grade Glioma Research Articles

447MO A clinical study of the safety and efficacy of anlotinib hydrochloride combined with temozolomide dose density scheme for the treatment of recurrent high grade glioma

447MO A clinical study of the safety and efficacy of anlotinib hydrochloride combined with temozolomide dose density scheme for the treatment of recurrent high grade glioma

763: Hyperoxygenation and re-irradiation for recurrent high grade glioma: innovative therapeutic strategy

763: Hyperoxygenation and re-irradiation for recurrent high grade glioma: innovative therapeutic strategy

Clinical Outcome of Patients with Epithelioid Glioblastoma Harboring BRAFV600E Mutation; A Single Institution Experience

Purpose Epithelioid glioblastoma (GBM) is a rare variant of GBM. The study aimed to look into clinicopathological details and outcomes of patients with epithelioid GBM harboring BRAFV600E mutation from a single institution. Methods Ten cases of epithelioid GBM diagnosed over the past 5 years were reviewed. All patients underwent surgical resection followed by adjuvant treatment as per protocol after initial diagnosis. Of these, seven patients were planned to redo surgery, reradiation, BRAF with MEK inhibitors, and bevacizumab based on clinical condition, magnetic resonance imaging findings, and progression-free survival after their recurrence. Four recurrent patients had received dabrafenib and trametinib. Results All tumor locations were supratentorial. The median follow-up was 2.3 years and the median time to recurrence was 19 months from the diagnosis (range 4–36 months). Four recurrent patients received BRAF + MEK inhibitors. One patient who started dabrafenib and trametinib experienced local progression after 33 months, followed by lung and bone metastasis. One patient died due to multiple subacute hemorrhages, who was a known case of congenital vascular malformations, and two patients remained disease-free after a year and 2 years. Conclusion Epithelioid GBM is a very rare, but well-documented entity. Therefore, careful preoperative imaging and detailed evaluation of genetic studies including BRAF V600E mutation are necessary for accurate diagnosis and appropriate selection of treatment for epithelioid GBM. Dabrafenib plus trametinib showed clinically meaningful activity in patients with BRAF V600E mutation-positive recurrent high-grade glioma.

An exploratory investigator-initiated trial via intrathecal or intracerebroventricular delivery of B7H3-specific allogeneic universal CAR-T cells in patients with recurrent high-grade gliomas.

23 Background: The MT027, developed by T-Maximum, is a B7-H3 (CD276)-directed genetically modified allogeneic T cell, targeting CD276-overexpressed tumor cells. Here, we reported a first-in-human, single-center, open-label investigator-initiated trial (IIT) via intrathecal or Intracerebroventricular delivery targeting recurrent high-grade glioma (ChiCTR2100047968). Methods: As of March 7, 2024, a total of 50 adult patients with recurrent high-grade glioma, B7H3+ expression, and KPS ≥40 were enrolled and administered at least one dose of MT027 (FAS), of whom, 32 received at least 3 doses (PPS1), 15 subjects with ≥3 doses and at least 1 efficacy visit (PPS2). 4 dose levels of 1.0, 1.5, 2.0, 2.5×107 cells per injection were administered once every 4 weeks. Results: The overall results demonstrated the favorable tolerability, safety, PK/PD characteristics, and preliminary efficacy. In FAS, the most common AE were fever and headache, without any CRS, ICANS, GvHD, or drug-related death. There were 4 cases (8%) of grade 3 AE or greater and 3 cases (6%) of SAEs. The copies of CAR in all groups reached 10000-100000 copy/ug, and persisted for > 60 days after a single dose. After multiple doses, the MT027 CAR-T cell numbers maintained at a high level (median 8850 copies /μg (range: 200-385900)) and for a long time. The levels of IL6, TNF-α and IFN-γ in CSF increased significantly and maintained for a long time. The mOS was 13.54 m (95% CI: 7.45; 19.63) and 20.73 m (95% CI: 16.12; 25.34) in PPS1 and PPS2, respectively. The 12-month OS rate was 53.30% (95%CI: 37.5%-75.7%) and 84.60% (95%CI: 67.1%-100%) in PPS1 and PPS2, respectively (historical data: 14%). The objective response rate (ORR) was 33% and the disease control rate (DCR) was 80% in PPS2. Conclusions: In patients with relapsed high-grade glioma, the intrathecal or ICV administration of MT027 cell therapy was found to be safe and well-tolerated. The toxicity of grade 3 or above was 1/5 of similar products. The pharmacokinetics and pharmacodynamics of single-dose and multiple-dose treatments were stable. MT027 exhibited longer persistence in the body of the patients, and the cell numbers and cytokine responses induced in vivo were 1-2 orders of magnitude higher than those of similar products. MT027 cell therapy demonstrated the excellent efficacy in treating relapsed high-grade glioma, with significantly prolonged overall survival and higher objective response rate compared to the historical data and similar product data. Currently, we are preparing for the IND filing in US (expected in 2024) with the recurrent glioblastoma as the first indication. Clinical trial information: ChiCTR2100047968 .

The Safety of Intraoperative Photodynamic Diagnosis Using 5-Aminolevulinic Acid Combined with Talaporfin Sodium Photodynamic Therapy in Recurrent High-Grade Glioma

Intraoperative photodynamic diagnosis (PDD) using 5-aminolevulinic acid (5-ALA) is a widely adopted technique to enhance the extent of resection during high-grade glioma (HGG) surgery. Recent updates to the package insert for 5-ALA in Japan now allow its use in combination with drugs that may induce photosensitivity, such as talaporfin sodium (TS). TS is employed in intraoperative photodynamic therapy (PDT) and has been shown to improve overall survival. The combination of 5-ALA with TS is expected to offer further benefits. However, the safety of this combination had not been established. This study reports on the safety of 5-ALA-PDD with TS-PDT in the treatment of recurrent HGG. 7 patients with recurrent HGG underwent tumor resection using a combination of 5-ALA-PDD and TS-PDT. The incidence of photosensitivity as an adverse effect associated with 5-ALA and TS was evaluated as described in the package insert. Adverse events were assessed according to the Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. Tumor-specific fluorescence intensity was strong in 4 cases and weak in 3. Photosensitivity occurred in only 1 patient (14.3%). Three patients exhibited CTCAE grade 1 or 2 abnormal liver function, and 1 patient experienced CTCAE grade 1 γ-GTP elevation. All abnormalities improved during follow-up. The combined use of 5-ALA-PDD and TS-PDT for HGG surgery did not increase the risk of serious adverse events in our study. Further investigations with a larger number of cases are needed for a more accurate assessment of its safety and efficacy.

AB048. Evidence of effectiveness of neoadjuvant camrelizumab and apatinib in patients with recurrent high-grade gliomas.

Recurrent high-grade glioma (HGG) is a challenge with limited treatment options and a poor prognosis. We conducted an open-label phase II study: neoadjuvant camrelizumab and apatinib in patients with recurrent high-grade gliomas (NCT04588987), and interim analysis showed very promising results. We are further searching for evidence of the effectiveness of this strategy. Patients with recurrent HGG received neoadjuvant treatment with camrelizumab (intravenous injection 200 mg on day 1) and apatinib (oral 250 mg per day on days 1-7), and 14 days later received surgery for recurrent tumor resection. Sequential therapy began 2 weeks after surgery with the biweekly camrelizumab (200 mg) and 4 weeks after surgery with the daily apatinib (250 mg) until investigator assessed progressive disease or unable to tolerate toxicity. The primary endpoint was overall survival (OS). When patients suspected progress during per-protocol treatment, re-surgery for resection of lesion was done, and the tissue was further examined. Between October 9, 2020, and March 30, 2024, 24 patients were enrolled [19 glioblastomas, one World Health Organization (WHO) grade 4 diffuse astrocytoma, three anaplastic astrocytoma, and one anaplastic oligodendroglioma]. Nineteen patients with interim analysis data, and showed the median progression-free survival (PFS) was 4.8 months [95% confidence interval (CI): 4.4-5.2], the median OS was 12.9 months (95% CI: 9.3-16.4) respectively, with a median follow-up time of 17.5 months (95% CI: 9.0-26.1). There were two patients who suspected progress and received second surgery. One patient showed real tumor progression with active tumor cells. While another patient the histology revealed mainly necrosis with inflammatory cells. Five patients initially showed increased enhancement on magnetic resonance imaging (MRI) but without increased symptoms, and showed continuous improvement when receiving further treatment. This immuno-target combination neoadjuvant therapy in recurrent HGG demonstrated encouraging efficacy and revealed some evidence of efficacy, and worth to further investigate.

Re-irradiation in High-grade Glioma: An Experience from A Series of Five Patients

ABSTRACT The management of recurrences or residual lesions following radiation therapy for brain tumors poses a challenging clinical scenario, necessitating careful consideration for treatment strategies. There is no standard of care for patients with recurrent high-grade glioma. Treatment strategies include resection, re-irradiation, systemic agents, and intratumoral thermotherapy using magnetic iron-oxide nanoparticles (nanotherapy). A small percentage of patients can undergo repeat surgery and re-radiation is also a matter of concern due to anticipated toxicities. However, advancements in radiation technology have made people more willing to consider re-irradiation. In this study, we retrospectively analyzed patients who underwent re-irradiation for high-grade glioma. In total, five patients were included in the study. All five patients had anaplastic astrocytoma. All patients were considered for surgery, followed by radiation therapy during the initial treatment. Three patients had an average of 4 years of symptom-free survival, while the other two had symptoms ranging from moderate to severe. Three of the five patients died within 1 year of taking the re-radiation; however, two patients are still in follow-up.

Comparison between Reirradiation by Stereotactic Body Radiation Therapy and Moderately Hypofractionated Radiotherapy in Combination with Temozolomide for Treatment of Recurrent High Grade Glioma.

High grade glioma (HGG) is considered a lethal disease with a high recurrence rate. There is no standard of care in recurrent HGG. Many treatment options are present, such as resurgery, systemic therapy, and re-irradiation. Re-irradiation seems to be a promising option. In this study, we aimed at comparing the efficacy and toxicity of two re-irradiation protocols. Forty patients with recurrent HGG were randomized equally into two arms. Arm A received 30 Gy/10f/2w, and arm B received stereotactic body radiotherapy (SBRT) 30 Gy/5f/1w. Concurrent temozolamide (TMZ) was given in both arms. Median progression free survival (PFS) and overall survival (OS) were calculated, and brain MRI was done after 2 months of radiotherapy and then every 2 months, with documented toxicity using the Common Terminology of Adverse Events version 5 (CTCAE). The median follow-up time after the re-irradiation course was 11 months (range 8-15 months). The median PFS after recurrence was 6.4 months (95% CI 5.3-7.4), the median OS after recurrence was 8.6 months (95% CI 7.5-8.7), and the median total OS form date of diagnosis was 18.5 months (95% CI 17.3-19.8) among the included patients. There was a statistically significant difference in PFS favoring arm B, with a median PFS of 7.3 versus 6.2 months in arm A, with p values of 0.004. There was no statistically significant difference in in median OS (9.3 months in arm B versus 8.4 months in arm A) with p values of 0.088. All patients tolerated their treatment well, and acute and subacute G1-G2 toxicity, consisting of headache, malaise, and nausea, were recorded during and shortly after the end of the re-irradiation course. Re-irradiation in recurrent HGG by both protocols is safe and effective, with a significant improvement in PFS in SBRT arm but no significant improvement in OS.

A multicenter, phase 1, Adult Brain Tumor Consortium trial of oral terameprocol for patients with recurrent high-grade glioma (GATOR)

Recurrent high-grade gliomas (rHGGs) have a dismal prognosis, where the maximum tolerated dose (MTD) of IV terameprocol (5days/month), a transcriptional inhibitor of specificity protein 1 (Sp1)-regulated proteins, is 1,700mg/day with median area under the plasma concentration-time curve (AUC) of 31.3μg∗h/mL. Given potentially increased efficacy with sustained systemic exposure and challenging logistics of daily IV therapy, here we investigate oral terameprocol for rHGGs in a multicenter, phase 1 trial (GATOR). Using a 3+ 3 dose-escalation design, we enroll 20 patients, with median age 60 years (range 31-80), 70% male, and median one relapse (range 1-3). Fasting patients tolerate 1,200mg/day (n= 3), 2,400mg/day (n= 6), 3,600mg/day (n= 3), and 6,000mg/day (n= 2) oral doses without major toxicities. However, increased dosage does not lead to increased systemic exposure, including in fed state (6,000mg/day, n= 4), with maximal AUC <5μg∗h/mL. These findings warrant trials investigating approaches that provide sustained systemic levels of transcription inhibitors to exploit their therapeutic potential. This study was registered at ClinicalTrials.gov (NCT02575794).

IMMU-17. A PHASE I STUDY OF INTRATUMORAL/PERITUMORAL HERPES SIMPLEX VIRUS-1 MUTANT HSV1716 IN PATIENTS WITH REFRACTORY OF RECURRENT HIGH-GRADE GLIOMAS: A PEDIATRIC BRAIN TUMOR CONSORTIUM STUDY

Abstract BACKGROUND Immune-modulatory strategies, including checkpoint inhibition and tumor vaccines, have been tested in efforts to mitigate the pro-tumor microenvironment in pediatric high-grade glioma (pHGG). HSV1716 is a first-generation oncolytic virus that was previously reported safe with evidence of response in pediatric patients with relapsed or refractory extracranial tumors and in adults with high-grade glioma. METHODS PBTC-037 was a multicenter, phase I trial developed and performed by the Pediatric Brain Tumor Consortium (PBTC) to estimate the maximum tolerated dose or recommended phase II dose of HSV1716 administered during surgical resection. Patients aged 12 to 21 years with recurrent or refractory pHGG for whom surgical resection was clinically indicated were eligible. After maximal tumor resection, patients received one intraoperative dose of HSV1716. RESULTS Two patients were enrolled; one was later deemed ineligible (due to out-of-window screening evaluations) yet was continued in follow up for safety. Shortly after enrollment of the 2 patients, the study was closed to accrual due to a change in the sponsor’s investment focus. One patient completed the 8-week reporting period without toxicities. The only grade 3 or higher adverse event noted was grade 3 hyperglycemia at 2- and 3-months post injection. The second patient that was later deemed ineligible received the injection of HSV1716 and had no evidence of dose-limiting toxicity. The two patients had progressive disease 1.9 and 2.9 months after enrollment; both eventually died due to progressive disease at 7.5 months. CONCLUSIONS We describe the administration of HSV1716 to two pediatric patients with recurrent high-grade glioma, without evidence of dose-limiting toxicity. Oncolytic viruses are currently being tested in pediatric patients in larger trials and in combinatorial trials in other tumor types. Despite the limited numbers, the data presented here will hopefully provide incremental steps toward improved immunovirotherapy of pediatric brain tumors.

HGG-12. A PHASE IB/II STUDY ON ASIDNA™ IN ASSOCIATION WITH RE-IRRADIATION IN CHILDREN, ADOLESCENTS AND YOUNG ADULTS WITH RELAPSING HIGH-GRADE GLIOMA

Abstract BACKGROUND AsiDNA is a synthetic cholesterol-oligodeoxyribonucleotide conjugate, inducing false DNA damage signaling, which prevents DNA repair in tumor cells. AsiDNA therefore increases the vulnerability of tumor cells to irradiation without increasing toxicity in healthy tissues. Preclinical data showed encouraging results of AsiDNA combined to irradiation in glioma and medulloblastoma models. We aimed to determine the safety and efficacy of AsiDNA, a DNA-repair inhibitor, in children, adolescents and young adults with recurrent High-grade Glioma (HGG) eligible for re-irradiation. METHODS AsiDNA was administered intravenously using a 3 consecutive days loading dose, followed by a weekly dose (350 mg/m2/dose or 600 mg for patients ≥ 50kg) for 11 weeks. Focal radiotherapy, using 1.8 Gy daily fraction, 5 days a week, was administered in combination during the first weeks: 18 Gy for brainstem diffuse midline glioma (DMG) and 36 Gy for supra-tentorial HGG (DMG or non-DMG). The first part of the study aimed to assess the safety and to confirm the recommended phase-II dose based on dose limiting toxicities (DLT) during the first 8 weeks. A second part was planned to assess activity/efficacy of the combination based on the progression-free survival (PFS) rate at 3 months. AsiDNA pharmacodynamics (PD) was studied in peripheral blood mononuclear cells (PMBC). RESULTS Eight (8) patients were enrolled: median age 14 y (6.2-24.5), 5 DMG. No DLT was observed. Median FU was 9.1 months, disease progression was observed in 8 patients; 6 died because of disease progression. Median PFS was 3.9 months. The PD results showed no significant target engagement in PBMCs. CONCLUSIONS Considering the low PFS as well as lack of efficacy on PD markers, the DSMB recommended stopping the study.

TRLS-03. A PHASE 1/2 STUDY ASSESSING SAFETY AND PHARMACOKINETICS OF CEMIPLIMAB IN PEDIATRIC PATIENTS WITH RELAPSED OR REFRACTORY SOLID OR CENTRAL-NERVOUS-SYSTEM TUMORS AND SAFETY AND EFFICACY OF CEMIPLIMAB IN COMBINATION WITH RADIOTHERAPY IN PATIENTS WITH NEWLY DIAGNOSED DIFFUSE INTRINSIC PONTINE GLIOMA, NEWLY DIAGNOSED HIGH-GRADE GLIOMA, OR RECURRENT HIGH-GRADE GLIOMA

Abstract BACKGROUND We investigated, for the first time, combination PD-1 inhibition (cemiplimab) and radiation therapy (RT) followed by cemiplimab monotherapy in children with solid tumors, diffuse intrinsic pontine glioma (DIPG) and high-grade glioma (HGG). METHODS We conducted a multicenter study through the Pediatric Neuro-Oncology Consortium. Phase 1 established the safety/pharmacokinetics of cemiplimab monotherapy in children (&amp;lt;18 years) with recurrent solid and central-nervous-system (CNS) tumors. Phase 2 evaluated cemiplimab/RT in children and young adults (3-25 years) with newly diagnosed (nd) DIPG, ndHGG or recurrent HGG (rHGG). Patients with ndDIPG and ndHGG were randomized to hypofractionated RT (hfRT) or conventionally fractionated RT (cRT). Primary endpoints included overall survival at 12 months (OS12) for ndDIPG and rHGG and progression-free survival at 12 months (PFS12) for ndHGG. Correlates included quality-of-life, circulating tumor DNA (ctDNA), immunogenicity, and PD-1 pathway components. RESULTS 25 patients (solid tumors, n=8; CNS tumors, n=17) were treated in phase 1; serum drug concentrations were comparable to adults. 32 patients were treated in phase 2. OS12 was 33.3% for ndDIPG treated with cemiplimab/hfRT (n=6), 0.0% for ndDIPG with cemiplimab/cRT (n=5), and 31.3% for rHGG (n=9). PFS12 was not estimable for ndHGG treated with cemiplimab/hfRT (n=5) and 20.0% for ndHGG treated with cemiplimab/cRT (n=7). 20 patients (35.1%) had grade 3/4 treatment-related AEs (TRAEs) and 13 (22.8%) had serious TRAEs. The most frequent grade 3/4 TRAE was decreased lymphocyte count (n=4 [7.0%]). 12 patients (21.1%) demonstrated treatment-emergent pseudo-progression, 2 (3.5%) grade 3/4. The most frequent serious TRAE was pseudo-progression (n=3 [5.3%]). CONCLUSIONS Cemiplimab/RT did not demonstrate an improvement in OS (ndDIPG and rHGG) or PFS (ndHGG), leading to early stopping for futility. However, the combination was tolerable, demonstrated similar outcomes across RT schedules, and showed similar exposure in serum compared to adults. Biologic and clinical correlate analyses are underway.

PALC-03. MEDICAL AID IN DYING: EXPERIENCE IN THE CENTER FOR CANCER AND BLOOD DISORDERS AT CHILDREN’S HOSPITAL COLORADO

Abstract BACKGROUND Medical Aid in Dying (MAiD) is now legal in 10 US states and Washington, DC, allowing terminally ill patients to self-administer medications to peacefully end their life. There is little published on pediatric hospitals’ approach to young adult patients requesting MAiD. METHODS We review the two patients who have participated in MAiD at the Center for Cancer and Blood Disorders at Children’s Hospital Colorado (CHCO). We also explore publicly available Colorado MAiD statistics. RESULTS Between 2017 and 2022, there have been 1,090 prescriptions written for MAiD medication in Colorado, 5 of which were for patients aged 18-34 (0.5%). Two of these patients were treated at CHCO. Patient A was a 26 year old male with a CNS non-germinomatous germ cell tumor whose treatment was complicated by mucormycosis and severe engraftment syndrome. He relapsed 23 months after completing therapy. He had neurologic decline including ataxia and blindness, at which time he requested MAiD. Patient B was a 24 year old male with multiply recurrent IDH-mutant medullary high grade glioma. With metastatic progression, he had many tumor-related symptoms including dysphagia, dysarthria, and weakness impacting his activities of daily living, so he requested MAiD. Both patients had multidisciplinary care conferences with neuro-oncology, social work, ethics, psychology, and palliative care. After completing psychological evaluation and all steps required by law, they were prescribed DDAMP2 (digoxin 50 mg, diazepam 1 gram, morphine 15 grams, and propranolol 2 grams). Both patients took the medications and died peacefully. Barriers encountered included infrequency of MAiD requests leading to unclear policies and processes. CONCLUSIONS Young adults represent a small but important subset of those seeking MAiD prescriptions. Despite challenges, patients were able to receive MAiD without delay in a compassionate manner. Our experience may be applicable to other pediatric hospitals facing these requests.

Single nucleus transcriptomics, pharmacokinetics, and pharmacodynamics of combined CDK4/6 and mTOR inhibition in a phase 0/1 trial of recurrent high-grade glioma.

Outcomes for adult patients with a high-grade glioma continue to be dismal and new treatment paradigms are urgently needed. To optimize the opportunity for discovery, we performed a phase 0/1 dose-escalation clinical trial that investigated tumor pharmacokinetics, pharmacodynamics, and single nucleus transcriptomics following combined ribociclib (CDK4/6 inhibitor) and everolimus (mTOR inhibitor) treatment in recurrent high-grade glioma. Patients with a recurrent high-grade glioma (n = 24) harboring 1) CDKN2A / B deletion or CDK4 / 6 amplification, 2) PTEN loss or PIK3CA mutations, and 3) wild-type retinoblastoma protein (Rb) were enrolled. Patients received neoadjuvant ribociclib and everolimus treatment and no dose-limiting toxicities were observed. The median unbound ribociclib concentrations in Gadolinium non-enhancing tumor regions were 170 nM (range, 65 - 1770 nM) and 634 nM (range, 68 - 2345 nM) in patients receiving 5 days treatment at the daily dose of 400 and 600 mg, respectively. Unbound everolimus concentrations were below the limit of detection (< 0.1 nM) in both enhancing and non-enhancing tumor regions at all dose levels. We identified a significant decrease in MIB1 positive cells suggesting ribociclib-associated cell cycle inhibition. Single nuclei RNAseq (snRNA) based comparisons of 17 IDH-wild-type on-trial recurrences to 31 IDH-wild-type standard of care treated recurrences data demonstrated a significantly lower fraction of cycling and neural progenitor-like (NPC-like) malignant cell populations. We validated the CDK4/6 inhibitor-directed malignant cell state shifts using three patient-derived cell lines. The presented clinical trial highlights the value of integrating pharmacokinetics, pharmacodynamics, and single nucleus transcriptomics to assess treatment effects in phase 0/1 surgical tissues, including malignant cell state shifts. ClinicalTrials.gov identifier: NCT03834740 .

Utility of circulating tumor DNA (ctDNA) from cerebrospinal fluid (CSF) for prognosis of patients with recurrent high grade glioma.

2010 Background: High-Grade Gliomas (HGGs) are the most aggressive primary brain tumors in adults and molecular characterization is crucial for diagnosis and optimal disease treatment. Due to the eloquent location of many HGGs, upfront or repeat tumor sampling may be sub-optimal. Hence, there is an urgent need to develop alternative, minimally invasive means to obtain diagnostic information and determine the expected clinical behavior. Here we report that circulating tumor DNA (ctDNA) from cerebrospinal fluid (CSF) can be used to identify disease defining genomic alterations and to track clonal evolution. Additionally, we demonstrate that detection of CSF ctDNA is positively correlated with leptomeningeal disease and overall survival suggesting that CSF ctDNA should be integrated into clinical decision making in the clinic. Methods: Our study includes 313 samples from 253 patients with recurrent glioma treated at Memorial Sloan Kettering Cancer Center who underwent CSF collection for routine clinical care and were sequenced using the MSK-IMPACT targeted clinical sequencing assay (468 and 505 genes). Alterations were classified as oncogenic based on OncoKB. 17% of genomic alterations detected were identified using a secondary bioinformatics analysis, following an informed approach with less stringent mutation calling criteria and Gaussian Mixture Model to call copy number events. CSF ctDNA positivity was determined by the presence of at least one oncogenic disease defining alteration or any shared alteration with the tumor. Results: Within this cohort, we found 193 CSF ctDNA positive (62%) and 120 CSF negative (38%) samples. Of note, CSF ctDNA positivity was the highest amongst histone mutant tumors with 94% CSF ctDNA positivity compared to 56% CSF ctDNA positivity for IDH-WT tumors. We noticed 44% of alterations shared between the tumor and the CSF, additionally, we noted considerable tumor evolution particularly within the growth signaling pathways (e.g. PDGFRA). The majority of the shared alterations were clonal, and we noticed the emergence of new clonal events in the CSF. Conclusions: Our cohort demonstrated that patients with positive CSF ctDNA had a significantly shorter overall survival compared to those who were CSF ctDNA negative (4.83 months vs 11.83 months, HR 2.1, p &lt; 0.001). In tandem with secondary clinical analysis, radiographic findings also correlated with CSF ctDNA positivity. Specifically, the presence of enhancing disease and contact of the tumor with the ventricular space were positively associated with detection of CSF ctDNA. Additionally, CSF ctDNA was associated with positive cytology in 21/21 cases (100%). With our improved bioinformatics pipeline, we hypothesize ctDNA from CSF may be used as a prognostic biomarker for survival, but confirmation requires further validation in a prospective study.

A phase I trial on the intra- and post-operative intracranial administration of ipilimumab and nivolumab in patients with recurrent high-grade glioma.

A phase I trial on the intra- and post-operative intracranial administration of ipilimumab and nivolumab in patients with recurrent high-grade glioma.

The TAC-GReD trial: The combination of talazoparib and carboplatin in DNA damage repair deficient recurrent high-grade glioma.

2047 Background: Recurrent high-grade glioma (rHGG) has a dismal prognosis with limited treatment options. Given that a high proportion of these gliomas harbor deficiencies in the DNA damage repair (DDRd) pathway, this genomic occurrence may confer synergistic lethality and sensitivity to poly (ADP-ribose) polymerase (PARP) inhibitors. Therefore, we hypothesize that DDRd rHGG may be sensitive to the combination of a PARP inhibitor, talazoparib, and carboplatin. Methods: This is a prospective phase II, single-arm open-label biomarker stratified single-institution trial conducted in Hong Kong (NCT04740190). Tumor tissue was sent for comprehensive next-generation sequencing (C-NGS) to screen for genomic aberrations associated with the DDRd pathway. Patients with rHGG (WHO grade III-IV) and at least one pathogenic mutation in the DDR pathway were deemed eligible. Patients were initially treated with whole-brain radiotherapy (2 Gy/1 Fr) on C1D1. Starting at dose level 0, talazoparib (0.75mg on Days 1-4) and carboplatin (AUC 1.5 on Day 1), were administered weekly for a total of 18 cycles, followed by maintenance talazoparib. The primary endpoint was the 6-month progression-free survival (PFS-6). Results: 61 patients were screened and 33 patients with DDRd rHGG were enrolled, 23 males, 10 females, and a median age of 55 years (range: 29-70 years). 73% (n=24) had a baseline ECOG PS of 0-1. Among the recruited patients, 12% (n=4) were classified as WHO grade III, while the remaining 88% (n=29) were WHO grade IV. Dose level escalation was achieved in 27% (n=9) of the cohort. The 6-PFS was 29% (95% CI 16.2-51.9%) and the median PFS was 3.5 months (95% CI: 2.4-6.3 months). The OS at 3 and 12 months were 90.4% (95% CI 80.7-100%) and 30% (95% CI 17-53%), respectively. The most common grade 3-4 toxicities were neutropenia (21.2%, n=7), thrombocytopenia (18.2%, n=6) and anemia (9.1%, n=3). One patient developed a grade 4 thromboembolic event. Dose level reduction was implemented in 54% (n=18) of patients and treatment was terminated in 6.1% (n=2) due to toxicity. Conclusions: Talazoparib and carboplatin in a DDRd-enriched rHGG is feasible and tolerable. Additional analysis including correlation of biomarkers with long-term outcomes is underway. Clinical trial information: NCT04740190 .

A phase 0/1 trigger trial of BDTX-1535 in patients with recurrent high-grade glioma (HGG) with EGFR alterations or fusions.

2069 Background: This Phase 0/1 clinical trial evaluates the pharmacokinetic (PK), pharmacodynamic (PD), and clinical response of recurrent high-grade glioma (HGG) patients with EGFR alterations and/or fusions to the ATP-competitive, irreversible EGFR inhibitor, BDTX-1535. Methods: Recurrent HGG patients with EGFR alterations (Arm A) or EGFR fusions (Arm B) received 5 days of BDTX-1535 (200 mg) prior to planned resection at 2-4 hours following the final dose. In the Phase 0 component of the study, total and unbound drug concentrations were measured in tumor tissue (Gadolinium enhancing and non-enhancing regions), cerebrospinal fluid (CSF), and plasma using validated LC-MS/MS methods. A PK ‘trigger’, defined as unbound drug concentration above 5-fold biochemical IC50 in Gadolinium (Gd)-nonenhancing tumor, determined eligibility for Phase 1. PD response was assessed by quantification of percentage of positive pEGFR, pERK and MIB-1 cells in the surgical tumor tissue compared to baseline pre-treatment tissue. Patients with tumors exceeding the PK threshold for unbound drug concentration were eligible for expansion phase therapeutic dosing of BDTX-1535. Results: A total of 7 patients with recurrent glioblastoma (Arm A) were enrolled in the Phase 0 component of the study. Two patients were excluded from PK analysis due to pseudoprogression. The mean unbound concentrations of BDTX-1535 in Gd-enhancing and nonenhancing tumor regions were 16.0 nM and 10.5 nM respectively. Four of five (80%) evaluable patients exceeded the PK threshold. The suppression of pEGFR and MIB1 was observed in 40% and 60% of patients, respectively. No serious adverse events were observed among patients in the Phase 1 component of the study and a clinical readout is planned in Q2 2024. Conclusions: BDTX-1535 is well-tolerated in recurrent HGG patients, achieves pharmacologically relevant concentrations in Gd-nonenhancing tumor tissue and is associated with suppression of EGFR signaling. Clinical trial information: NCT06072586 .

Outcomes and immune response after peptide vaccination targeting human cytomegalovirus antigen pp65 in children and young adults with recurrent high-grade glioma and medulloblastoma.

Outcomes and immune response after peptide vaccination targeting human cytomegalovirus antigen pp65 in children and young adults with recurrent high-grade glioma and medulloblastoma.

A phase II trial of olaparib and durvalumab in patients with recurrent IDH-mutated gliomas.

2013 Background: Isocitrate dehydrogenase mutations (IDHmt) define astrocytomas and oligodendrogliomas. IDHmt results in accumulation of R-2-hydroxyglutarate (2HG), leading to epigenetic dysregulation and defective homologous recombination repair, providing a rationale for poly (adenosine 5’-diphophate-ribose) polymerase (PARP) inhibitors. PARP inhibition upregulates PD-L1 so the combination with immune checkpoint inhibition is potentially synergistic. Methods: Patients (pts) with recurrent high-grade IDHmt gliomas were enrolled in this phase II open-label study (NCT03991832). Eligibility included progressive disease with up to 2 prior lines of systemic therapies and ECOG 0–1. Pts received olaparib 300 mg twice daily continuously and durvalumab 1500 mg IV every 4 weeks. Simon’s optimal two-stage design was used. The primary objective was overall response rate (ORR) and disease control rate (DCR) by RANO criteria. Secondary objectives included overall survival (OS), progression free survival (PFS) and safety.Exploratory biomarkers of response and resistance were assessed with serial blood samples using cell-free methylated DNA immunoprecipitation and high-throughput sequencing (cfMeDIP-seq) as well as multiplex-immunohistochemistry. Results: In the 29 pts enrolled between January 2020–February 2023, median age was 40.5 (range 23–66) and 41% were female. Initial tumor grade was 2 in 9, 3 in 8 and 4 in 12 pts, respectively. Median time to enrollment from tumour diagnosis was 5.9 years. All had prior resection and median number of prior systemic therapies was 2. One patient clinically deteriorated before starting treatment. ORR was 10%, 95% CI 2.2–27%, with responses in 3 pts. One pt with grade 4 astrocytoma had a complete response and remains on treatment after 33 months. The other 2 responders with grade 4 astrocytoma had response durations of 4.1 and 9.8 months. DCR was 28% (95% CI 12.7–47.2%) with 5 additional pts demonstrating stable disease. With a median follow-up of 33 months, mOS was 9.5 months (95% CI 4.3–19.3) and mPFS was 1.9 months (95% CI 1.8–3.0). There was no treatment-related grade 3–4 toxicities. Any grade toxicities included fatigue (48%), nausea (17%), diarrhea (10%), and cytopenias (3%). Using serial cfMeDIP-seq, cell free DNA methylomes comparing responders versus progressors using the top differentially methylated regions can predict treatment response with high accuracy (AUC 0.833). Post progression, differentially methylated genes converge on TGF-β and signal transduction pathways, suggesting possible mechanisms of resistance. Multi-modal analysis of long-term responders will additionally be presented. Conclusions: Combination treatment with olaparib and durvalumab for pts with IDHmt glioma is well tolerated but has limited efficacy in unselected pts. cfMeDIP-seq can reliably predict tumour progression providing a blood-based biomarker of treatment response. Clinical trial information: NCT03991832 .