Citations

Abstract Pleomorphic xanthoastrocytomas (PXAs) are rare primary brain tumors that mainly affect children and young adults. We report a case of recurrent PXA in an adult and review the literature. To our knowledge, this is the first adult report highlighting clinical, CSF, and imaging findings of recurrent PXA with leptomeningeal spread. A 60-year-old woman presented with a 2-month history of fluctuating mental status, aphasia, low-back pain, progressive paraparesis, and urinary retention. She was previously diagnosed with a left temporal PXA 17 years prior and underwent gross total resection with no evidence of tumor recurrence for the next several years. Approximately 10 months prior to her current presentation, she was found to have radiographic recurrence of the left temporal PXA. She underwent gross total resection, with final pathology revealing anaplastic transformation, WHO grade 3, BRAF V600E mutation positive. She next underwent photon radiotherapy, and chemotherapy with temozolomide. She had good clinical and radiographic response to treatment for 8 months prior to developing her current symptomatology. MRI of the brain and spine showed local recurrence with new diffuse contrast enhancement of the spinal cord and nerve roots. Cerebrospinal fluid (CSF) analysis showed a total nucleated cell count of 10/mcL, protein >1250 mg/dL, glucose < 20 mg/dL, and xanthochromia. CSF cytology was positive for malignant cells consistent with PXA. Although PXA is often associated with a favorable prognosis, recurrence with anaplastic transformation can be associated with dissemination throughout the nervous system and worse outcomes. Despite the rarity of such cases, clinicians should remain vigilant, especially when anaplastic transformation occurs. Early detection of leptomeningeal involvement through thorough CSF analysis and appropriate imaging can facilitate prompt intervention and potentially improve patient outcomes.

Abstract INTRODUCTION Glioblastoma (GBM) is the most common primary malignant brain tumor and has a poor clinical outcome. Extracellular vesicles (EVs) are promising biomarkers to assist the differential diagnosis between pseudoprogression and true tumor progression. We aimed to identify non-tumor plasma EV markers that predicted GBM occurrence using trained multiple tree-based machine learning algorithms. METHODS We included plasma samples of 40 GBM and 40 non-GBM (20 brain metastasis, 20 normal donors). Spectral flow cytometry was performed to determine plasma EV subpopulation frequency based on CD9,CD81,CD63,CD11b,CD45,CD31, and CD41a expression. Multiparametric t-SNE and FlowSOM analysis clustered plasma EVs based on these markers. Decision trees and random forest classifiers were trained and tested to predict the disease status (GBM vs non-GBM) based on plasma EV subpopulations. RESULTS Compared to non-GBM, GBM had increased frequency of CD9+ EVs (64.52% vs 40.69%, p< 0.0001), CD9+CD63-CD81- EVs (54.45% vs 37.26%, p< 0.0001) and myeloid-derived EVs (CD9+CD11b+ EVs, 20.77% vs 12.48%, p = 0.0241). In the decision tree analysis, low frequency of CD9+ EVs was found in 44% of all cases and represented a chance of 75% to be classified as non-GBM cases. An algorithm based on random forest analysis (n = 500 trees) using these markers had a sensitivity of 85.71% and specificity of 77.8% with an overall accuracy of 81.25% for identifying GBM. The frequencies of CD9+, CD9+CD63-CD81-, and CD9+CD63+CD81+ were the most critical factors in predicting GBM diagnosis. FlowSOM analysis identified 20 plasma EV subpopulations but had a lower accuracy (62.5%) when combined with our machine learning algorithm. CONCLUSIONS Non-tumor plasma EV expression profile combined with tree-based machine learning demonstrated high accuracy in predicting patient disease status. CD9+ EV frequency was one of the most promising biomarkers to assist in this diagnosis. We will continue to test our established algorithm and further validate our findings in a larger cohort.

Abstract GB13 is a novel biologic therapy in the final stages of preclinical development for the treatment of glioblastoma (GBM) and H3 K27-altered diffuse midline glioma (DMG) that has received Orphan Drug Designation by the Food and Drug Administration for treatment of malignant gliomas. GB13 targets a specific tumor-restricted receptor of interleukin 13 called interleukin 13 receptor alpha 2 (IL13Rα2). IL13Rα2 is highly expressed in malignant gliomas and, importantly, is not expressed on non-cancerous cells of the brain. GB13 consists of an engineered proprietary mutant of IL13, which binds exclusively to IL13Rα2, and is fused to a highly cytotoxic exotoxin molecule. In vitro data demonstrate that GB13 potently kills IL13Rα2+ cancer cells while sparing non-cancerous cells. These characteristics make GB13 an attractive agent for safe and efficacious targeting of tumor cells expressing IL13Rα2 in upcoming clinical trials. In the current studies, we employed patient-derived GBM and DMG cell and animal models to provide key conclusions that support GB13 as an effective treatment option for gliomas in the clinic. First, we demonstrated that single acute infusions of GB13 by enhanced delivery (CED) is effective at decreasing orthotopic tumor volumes and increasing animal survival and that a long-term infusion can more significantly extend animal survival. Second, we determined that IL13Rα2 is requisite for GB13 activity as tumors that do not express the receptor are insensitive to the cytotoxic effects of GB13, demonstrating a precise and clear biomarker for clinical trial patient selection. Finally, we determined that GB13 works in concert with clinical standard-of-care radiation therapy to increase cell death, compared to radiation alone. Based on this work, we and our clinical collaborators are confident that the current work confirms GB13 has many important characteristics as an exciting therapy, which continues development towards a Phase I clinical trial for both GBM and pediatric DMG.

Abstract Tumor cells require the mitotic spindle to drive chromosome separation in metaphase, which has made the spindle a compelling target for development of anti-mitotics. However, most of these spindle inhibitors target microtubules and can thereby be highly neurotoxic. This has motivated development of targeted anti-mitotics that inhibit non-microtubule components of the spindle, including kinesins and mitotic kinases. These drugs are not neurotoxic and prolong survival in tumor patients, but resistance limits their efficacy. We reported (Kenchappa et al., Cell Reports, 2022) that resistance to one of these—ispinesib, a highly specific inhibitor of the mitotic kinesin Kif11—requires two functions of STAT3: activation of transcription in the nucleus and of oxidative phosphorylation in the mitochondria. Inhibiting both functions reverses ispinesib resistance. Furthermore, combining ispinesib with a CNS-permeant STAT3 inhibitor significantly prolongs survival over ispinesib alone in both immunocompetent and PDX GBM models. We now report that resistance to two other targeted anti-mitotics—alisertib (Aurora Kinase inhibitor) and volasertib (Polo Like Kinase inhibitor)—works similarly and can likewise be reversed with STAT3 inhibitors. For all three of these anti-mitotics, resistance goes hand-in-hand with development of therapy-induced senescence (TIS) in approximately half of GBM cells. TIS cells secrete a variety of soluble factors, referred to as the senescence associated secretory phenotype (SASP), which stimulate stemness, angiogenesis, and immunosuppression. We propose that: 1) TIS cells require STAT3 for survival, and that they in turn maintain a drug resistant state by suppressing mitosis in the remaining, non senescent cells through components of the SASP; and 2) by killing TIS cells, STAT3 inhibitors restore anti-mitotic sensitivity in the remaining, non-senescent tumor cells. We propose that this STAT3/TIS model of resistance may also apply to how resistance develops to other GBM therapies, and may guide similar translational approaches to enhancing therapeutic efficacy.

Abstract α-PD-1 checkpoint blockade is a promising immunotherapeutic approach for many solid tumors; however, this strategy is minimally effective for GBM patients as a monotherapy. One potential reason why α-PD-1 checkpoint blockade is ineffective is the tumor microenvironment and systemic derangements of the immune system which are prevalent in GBM patients. We have successfully modeled peripheral immune derangements in experimental murine GBM models. These include low peripheral blood CD4 T cell counts, reduced MHC class II expression on monocytes, and atrophy of primary immune organs in animals harboring gliomas. We therefore hypothesized that extended half-life IL-2, a potent cytokine which promotes the proliferation, differentiation, and killing activity of T cells, could overcome immune derangements and could potentially synergize with α-PD-1 checkpoint blockade therapy. In cohorts of C57Bl/6 mice, we supplemented α-PD-1 checkpoint blockade with multiple bio-engineered extended half-life IL-2 molecules to treat GL261 and CT2A orthotopic glioma models which are normally resistant to monotherapy. We observe a statistically significant increase in survival in GL261-bearing animals receiving the combination of extended half-life IL-2 reagents and αPD-1 therapy relative to control-treated mice. Some animals receiving this combination therapy had a reduction in tumor burden to levels below detection. These long-term survivors underwent a rechallenge experiment with a second inoculation of GL261-Luc and effectively cleared tumor without further therapeutic intervention. This intervention causes a significant shift in the immune profile, including the formation of mature T cell responses, as well as restoring the diminished peripheral immune cell counts in GL261-bearing animals. Finally, combining extended half-life IL-2 with α-PD-1 checkpoint blockade is effective independently of the CD8 T cell response. Together, these data suggest that combination immunotherapies employing extended half-life IL-2 fusion proteins are translational to the clinic and do not require the identification of tumor specific antigens for efficacy

Abstract INTRODUCTION NF2-related schwannomatosis (NF2-SWN) predisposes affected individuals to vestibular schwannomas (VS), non-vestibular schwannomas (NVS), meningiomas, and ependymomas. The rarity of NF2-SWN and the presence of multiple tumor types has impeded clinical trials. We conducted a multi-center, adaptive, platform-basket trial to screen multiple drugs against progressive NF2-SWN tumors. We report the final analysis of the first treatment arm with brigatinib, an oral ALK inhibitor that inhibits multiple tyrosine kinases. METHODS This study enrolled participants ≥ 12 years with NF2-SWN and progressive target tumors (baskets: VS, NVS, meningioma, or ependymoma Radiographic response (RR) was defined as ≥ 20% decrease in target tumor volume from baseline. The primary outcome was RR rate. Secondary outcomes included safety, hearing response, and RR in non-target tumors. Tumor response was evaluated by MRI every 3 months in year 1 and every 6 months thereafter. In stage 1, 20 participants received brigatinib 180 mg daily. Interim analysis suggested activity in NVS and meningioma. Thus, an additional 20 participants with progressive meningioma or NVS were enrolled in stage 2. RESULTS Forty participants (median age 26 years, 12 pediatric, 28 female) were treated. Prior treatment included surgery (90%), radiation therapy (20%) and chemotherapy (55%). Target tumors included 10 VS, 9 NVS, 19 meningiomas, and 2 ependymomas. Overall RR rate was 10% for all target tumors (22% for non-VS, 11% for meningioma, 0% for VS, and 0% for ependymomas). There were no grade 4 or 5 treatment-related adverse events (AEs). The most common AEs were diarrhea (63%), nausea (40%), muscle cramps (33%), increased LDH (35%), increased AST (33%), and increased ALT (23%). CONCLUSION Brigatinib treatment was associated with RR in NVS and meningiomas in a heavily pretreated cohort of participants with progressing NF2-SWN tumors. This novel design provides unique ability to assess treatments for hereditary syndromes with multiple primary tumors.

Abstract INTRODUCTION Prior to 2021, (classic) glioblastoma (GBM) required absence of IDH mutation and histologic features of hypercellularity, nuclear atypia, microvascular proliferation (MVP), and necrosis. Absence of histologic features can be a result of undersampling, with molecular, radiologic, and clinical features consistent with GBM. Accordingly, WHO 2021 defined molecular glioblastoma as diffuse glioma IDHwt, H3wt, with one or more of MVP, necrosis, TERT promoter mutation, EGFR gene amplification (EGFRamp), and/or +7/−10. We hypothesized that there is clinical and radiographic heterogeneity among tumors defined as molecular GBM. METHODS We identified 121 patients that met the criteria for molecular GBM. 121 Classic GBM, defined as IDHwt with hypercellularity, MVP or necrosis, were matched to molecular GBM cases by age, sex, and diagnosis date. All cases were reviewed for relevant histologic features and molecular features. Examined clinical variables included: first symptom, time from first symptom to date of pathological diagnosis, date of first MRI, tumor location, radiographic features of enhancement, diffusion or mass effect, time to progression and overall survival. Clinical, radiologic, and molecular features were compared between classic and molecular GBM. RESULTS Currently,160 cases have been reviewed. Preliminary results show that there is a longer time from first symptom to diagnosis for molecular GBM. Molecular GBM is significantly more likely to be discovered coincidentally, and without enhancement or radiographic necrosis. Classic GBM is significantly more likely to present with focal neurologic deficit as first symptom, regional mass effect on index imaging and have monosomy 10. CONCLUSION While pathologic undersampling accounts for a significant proportion of molecular GBM, our data suggest that there are significant clinical, radiographic, and outcome differences between classical and molecular GBM. Final analysis of the entire cohort will help better define this clinical spectrum.

Abstract OBJECTIVE This study aimed to analyze the hemorrhagic risk of melanoma brain metastases following SRS. METHODS A retrospective analysis was conducted using a prospective institutional database between 1990 and 2021. Lesional hemorrhage was categorized as definite or possible, and hemorrhage severity was graded using CTCAE. RESULTS The study identified 291 patients with 1083 lesions. The mean age of patients was 60 ± 15 years, with 61% being male. Median follow-up was 11 months, corresponding to 581 patient-years. Among the patients, 82 (28%) experienced 135 lesional hemorrhages (13%). Of these, 88 lesions in 61 patients were grade 1-2 hemorrhages, 42 lesions in 25 patients were grade 3, and five lesions in five patients progressed from grade 1 to 3. Surgical intervention was required for 17 lesions (2%) in 16 patients (5%). Lesional hemorrhage was associated with radiosurgery performed between 2015 and 2021 (OR, 0.373; 95% CI, 0.231-0.60; p < 0.001), increasing marginal dose (OR, 0.89; 95% CI, 0.82-0.98; p = 0.017), antiplatelet use (OR, 0.192; 95% CI, 0.082-0.45; p < 0.001), and WBRT (OR, 0.51; 95% CI, 0.330-0.77; p = 0.0017). The cumulative lesional hemorrhage risk reached 17–20% at 36 months following radiosurgery, with 95-96% of hemorrhages occurring within the initial year. Median OS was 11 months (95% CI, 9-13 months). Patients who received radiosurgery between 2015 and 2021 exhibited a median OS of 17 months (95% CI, 10-24 months; p < 0.001), while those without hemorrhage had a median OS of 12 months (95% CI, 10-14 months; p = 0.054). CONCLUSIONS Definitive hemorrhage risk was 17% for melanoma brain metastases after SRS within the first three years, with 95% of lesional hemorrhages occurring within the initial year. Surgical intervention was necessary in 5% of patients. Hemorrhage risk and overall survival improved after 2015.

Abstract H3K27M-mutant diffuse midline glioma (DMG) patients have no proven effective therapies beyond radiation. ONC201, a mitochondrial protease ClpP agonist, has recently demonstrated efficacy in these patients, but the mechanism behind this remains unknown. We assessed clinical outcomes, tumor sequencing, and tissue samples from patients treated in two completed multi-site clinical studies (n=71). Patients treated with ONC201 monotherapy following initial radiation but prior to recurrence (n=35) demonstrated a median overall survival of 21.7 months and a median progression-free survival of 12.2 months. Radiographic response was associated with increased expression of key tricarboxylic acid cycle-related genes in baseline tumor sequencing. Similar survival benefits were observed using in utero electroporation and orthotopic mouse models of H3K27M-DMG (median 107 versus 77 days [p=0.02] and median 97 versus 141 days [p=0.004], respectively). Integrated transcriptomic and metabolomic analysis of ONC201-treated H3K27M-DMG cells revealed downregulation of TCA cycle, glycolysis, and pyruvate metabolism genes, most notably oxoglutarate dehydrogenase (OGDH), and concomitant changes in levels of associated metabolites including ɑ-ketoglutarate (ɑ-KG). Interestingly, L-2-hydroxyglutarate (L-2HG), a known inhibitor of the Jumonji C domain family of histone lysine demethylases, was also increased. This corresponded with increases in repressive H3K27me3 in vitro and in human tumors accompanied by epigenetic downregulation of cell cycle regulation and neuro-glial differentiation genes. Genetic knockdown of OGDH recapitulated ONC201-mediated increases in H3K27me3. In contrast, genetic knockdown of ClpP or lactate dehydrogenase A or overexpression of L-2-hydroxyglutarate dehydrogenase (L-2HGDH), but not D-2HGDH, abrogated ONC201-mediated increases in H3K27me3, demonstrating that ONC201 induces the production of L-2HG in H3K27M-DMG cells leading to increased H3K27me3. Overall, our data demonstrates the efficacy of ONC201 in H3K27M-mutant DMG and supports ONC201 as the first monotherapy to improve outcomes in patients with H3K27M-mutant DMG for whom few therapeutic options currently exist. Mechanistically, ONC201 disrupts integrated metabolic and epigenetic pathways and reverses pathognomonic H3K27me3 reduction.

Abstract Low-grade meningiomas with subtotal resection carry significantly shorter recurrence-free survival rates than those with gross total resection. We report the natural history of a case of low-grade meningioma after subtotal resection and review the literature. We aim to highlight known global health disparities in oncology treatment by describing a case of meningioma progression following subtotal resection. A 40-year-old Kenyan woman presented locally with headache, nausea, and vision loss over approximately a six month time period. A 5 cm olfactory groove meningioma was discovered, and she subsequently underwent subtotal resection that was likely limited due to hemorrhagic complications. Over the following two years, she developed progressive dizziness, nausea, gait instability, difficulty performing tasks, and visual loss prompting medical evaluation at our institution. Physical examination demonstrated blindness, bilateral proptosis with severe vertical gaze palsy, and prominent frontal bossing. MRI Brain revealed a 9 cm enhancing mass arising from the cribriform plate with elevation of an ununited overlying frontal craniotomy flap and apparent meningoceles extending through the presumed osteotomy bilaterally. She underwent successful resection with pathology demonstrating CNS WHO Grade 1 meningioma. Her postoperative neurologic exam showed subtle improvement, specifically in regards to orientation questions. In this patient, bone flap displacement from prior craniotomy allowed significant interval tumor growth while minimizing mass effect on brain parenchyma. This case highlights global health disparities in low-grade meningioma management related to appropriate healthcare access in underserved patients.