Citations

Abstract Innate immune cells of macrophage family predominate tumor immune microenvironment of CNS malignancies. Although macrophages exhibit myriads of protective functions such as clearance of malignant cells, immune surveillance, inflammation resolution and tissue repair, they are generally linked to immunosuppression in gliomas. To identify anti-glioma myeloid cell effectors, we performed directionally concatenated ligand-receptor (L-R) interactome analyses from dendritic cells (DC) and microglia (MG) to lymphoid (CD4+T, Tregs, CD8+T, NK and NKT) cells identified by single cell transcriptomics analyses of ~145,000 tumor-associated CD45+ leukocytes from tumor brains of eighteen high-grade and low-grade glioma patients. Amongst DC-specific (e.g. adhesion molecules) and MG-specific (e.g. chemokine family) interactomes, we identified LGALS9 encoding Galectin-9 as the most pertinent interactions (e.g. SORL1 encoding sortilin-related receptor 1) in MG of IDH-wild type gliomas. Spectral cytometry, immunohistochemistry and western blotting analyses of MG, macrophage, DC, lymphoid cells and tumor cells confirmed abundant expression of Galectin-9 in glioma-associated MG and not in Nestin+ tumor cells. Furthermore, differential gene enrichment analyses revealed transcripts associated with cellular adhesion (coronin 1A, integrin) and phagocytosis (FcγR, phospholipase D, Rab family proteins etc.) was significantly upregulated in Galectin-9hi compared to Galectin-9lo/- MG and macrophages predicting putative role of Galectin-9 in tumor cell adhesion and phagocytosis. Using glioblastoma relevant patient derived ex vivo primary microglia (pMGs; 707, 2103, 1805) and glioma stem cell (GSC) co-culture model system, we evaluated the functional role of Galectin-9. Confocal imaging analyses of co-cultured pMGs with GSC revealed that siRNA or neutralizing antibody mediated downregulation of Galectin-9 led to significantly impaired adhesion (p<0.001) between pMGs and GSC. Not only adhesion but even phagocytosis of GSC was dramatically attenuated (p<0.0001) across all Galectin-9 silenced or neutralized pMGs. Altogether, our study underscores unappreciated role of Galectin-9 in MG as regulator of glioma cell adhesion and phagocytosis that can be harnessed for glioblastoma immunotherapy.

Abstract BACKGROUND Mirdametinib is the first FDA-approved MEK1/2 inhibitor for both adults and children ≥2 years with NF1 who have symptomatic PN not amenable to complete resection. We report results from the phase 2b ReNeu trial (NCT03962543), including the LTFU. METHODS In ReNeu, mirdametinib was administered in 3-weeks-on/1-week-off 28-day cycles. Following the 24-cycle treatment phase, patients could continue mirdametinib in an optional LTFU. We report results through June 12, 2024, approximately 9 months from the previous data cutoff. RESULTS Fifty-eight adults and 56 children received mirdametinib. Median (range) duration of treatment was 21.8 (0.4, 54.4) months in adults and 25.4 (1.6, 48.5) months in children. Among LTFU-eligible patients, 26/31 (84%) adults and 32/37 (86%) children entered LTFU. Confirmed objective response rate (ORR, treatment+LTFU phases) was 47% (27/58; 95%CI, 33%, 60%) in adults and 55% (31/56; 95%CI, 42%, 69%) in children. Among confirmed responders, 18 adults and 19 children achieved a deep response (best target PN volume reduction from baseline of >50%). Median (range) best percentage change from baseline in target PN volume was –41% (–90%, 13%) in adults and –43% (–98%, 48%) in children. Median duration of response (DoR) was not reached for either age cohort. Treatment-related adverse events (TRAEs) in ≥25% of patients were dermatitis acneiform, diarrhea, nausea, and vomiting in adults; and diarrhea, dermatitis acneiform, and paronychia in children. Grade ≥3 TRAEs occurred in 17% of adults and 25% of children. Dose interruptions, dose reductions, and discontinuations due to TRAEs occurred in 9%, 17%, and 22%, respectively, of adults, and 14%, 14%, and 9%, respectively, of children. CONCLUSIONS Improved confirmed ORR was observed with longer duration of mirdametinib, with additional deep responses achieved in both adults and children. Mirdametinib continued to be well tolerated with a manageable safety profile and no new safety signals in the LTFU.

Abstract INTRODUCTION Brigatinib is an oral ALK inhibitor that inhibits multiple tyrosine kinases. We previously published outcomes of patients with NF2-related schwannomatosis treated with brigatinib for a median of 10.4 months. We report updated results of these patients with extended follow-up. METHODS This multicenter, phase II, open-label study included participants ≥12 years with NF2-SWN and progressive target tumors (baskets: VS, NVS, meningioma, or ependymoma). Patients were treated with brigatinib 180 mg daily. Patients discontinued treatment upon progression of target tumors but could continue treatment with isolated progression of non-target tumors if deemed clinically acceptable by the treating team and patient. One target and up to 5 non-target tumors were followed in each participant. Tumor response was evaluated by MRI every 3 months in year 1 and every 6 months thereafter with radiographic response (RR) defined as ≥20% decrease in volume compared to baseline. RESULTS Forty participants were treated for a median of 23 months (range, 3-40 months). Updated imaging data is available on 162 tumors (45 VS, 59 non-VS, 53 meningiomas, and 5 ependymomas). RR rate for all tumors was 28% and was 31% for non-VS, 28% for meningioma, 22% for VS, and 60% for ependymomas. The 12-month freedom from tumor progression was 77.1% for all tumors, 81.5% for non-VS, 78.1% for meningioma, 69.2% for VS, and 100.0% for ependymoma. The 24-month freedom from tumor progression was 73% for all tumors, 81.3% for non-VS, 72.4% for meningioma, 62.4% for VS, and 100.0% for ependymoma. There were no grade 4/5 treatment-related adverse events (AEs). The most common AEs were diarrhea (65%), nausea (40%), muscle cramps (40%), hypertension (35%), increased LDH (35%), increased AST (33%), and increased ALT (25%). CONCLUSION Brigatinib treatment was associated with high rates of tumor stability at 24 months across multiple tumor types in patients with NF2-related schwannomatosis.

Abstract BACKGROUND The majority of pituitary neuroendocrine tumors (PitNETs) are effectively managed with medical therapy, surgery, and/or radiation therapy; however, a subset of pituitary adenomas exhibit aggressive behavior. Temozolomide is thought to be an effective treatment option for patients with PitNETs. METHODS We identified and retrospectively reviewed 11 patients with pituitary tumors treated with temozolomide. We then conducted a review of the literature, combining 114 previously published cases with our cohort. RESULTS 125 cases were identified with diagnoses of pituitary adenomas (n=45), aggressive pituitary tumors (n=61), and pituitary carcinoma (n=19) treated with temozolomide. 79 patients were male (68.1%) with a median age of 47.5 (range 9-72). A variety of tumor types were represented: 50 corticotroph adenomas (40.7%), 37 prolactinomas (30.1%), 22 hormone nonfunctioning adenomas (17.9%), 8 somatotroph adenomas (6.5%), 6 other functioning adenomas (4.9%), and 2 cases where the functional status was not mentioned. Median treatment duration was 9 cycles (n=91, 150-200 mg/m2 days 1-5, 28-day cycles; n=2, 75 mg/m2, days 1-21, 28-day cycles; n=1, 75 mg/m2 daily). 27 patients received concurrent therapy with a dopamine agonist/somatostatin analogue (n=10), other chemotherapy agent (n=9) or radiotherapy (n=8). Radiographic responses included stable disease (n=40), partial response (n=35), complete response (n=8), and progressive disease (n=30). Hormonal responses included complete response (n=13), partial response (n=32), and no response (n=16). 22 patients (47.8%; out of 46 patients where progression/recurrence was assessed) experienced progression/recurrence following temozolomide initiation with a median progression free survival (PFS) of 24 months. There was no significant association between MGMT methylation status and radiological or hormonal response. No unexpected toxicities were observed. CONCLUSION In this cohort, temozolomide was well-tolerated with a median PFS of 24 months. MGMT methylation status did not predict temozolomide response. Temozolomide is an option with a survival benefit for patients with PitNETs.

Abstract WSD0922-Fu is an oral, CNS-penetrant, small molecule EGFR inhibitor which potently inhibits EGFR aberrations specific to non-small cell lung cancer (NSCLC) and glioblastoma (GBM). MC1914 (NCT04197934) is a first-in-human phase 1 trial in patients with EGFR aberrant recurrent GBM and NSCLC. After determining the maximum tolerated dose, adults with recurrent GBM were treated in two expansion cohorts: (a) non-surgical cohort (6/12 patients thus far): EGFRvIII mutation, first recurrence; food-effect study included (b) surgical cohort (6/6 patients), any EGFR mutation, any recurrence; window-of-opportunity study (WOO) included. Among these 12 patients, median age = 60 years; 50% female; 58% ECOG 0). All patients received prior radiation and temozolomide. After the WOO or food-effect study, patients were dosed at 120 mg BID (5 days on, 2 days off), and escalated to 160 mg BID (5 days on, 2 days off) based on tolerability. Common adverse events (>40%) are comparable to other EGFR inhibitors (acneiform rash, diarrhea, fatigue, xerosis, pruritis). Treatment-related grade 3+ adverse events were limited to lymphopenia (n = 1). WSD0922-Fu exposure in the fed state exceeded the fasted state (median plasma Cmax and AUC0-24h are 1.6x and 1.3x, respectively) with a delayed Tmax (6.0 vs 1.8 hours). For the WOO, time between last dose administered to tumor collection ranged between 4 - 13.5 hours. Median tumor WSD0922-Fu concentration was 0.76 µg/g; estimated median unbound tumor concentration was 24.9 ng/g and within expectations for pharmacodynamic effect. Median brain/plasma ratio = 0.59; median unbound brain/unbound plasma = 0.88. Enrollment to the non-surgical cohort is ongoing, so formal efficacy data remain immature. However, examples of clinical efficacy will be shown along with data on recurrence patterns. Phase 2 clinical trial development is in progress.

Abstract BACKGROUND Mixed histiocytic neoplasms with overlapping features of Erdheim-Chester Disease (ECD) and Rosai-Dorfman Disease (RDD) are extremely rare and diagnosis may be delayed due to lack of awareness and complex histology features. METHODS We report a case of mixed ECD/RDD misdiagnosed as IgG4-related disease and review the literature. RESULTS A 50-year-old man presented for evaluation of spastic paraparesis in the context of a thoracic dural lesion. Two years prior he developed an inflammatory monoarthritis concerning for rheumatoid arthritis unresponsive to methotrexate. Six months prior he developed leg spasms, gait spasticity, and urinary incontinence. MRI demonstrated a T2 hypointense enhancing epidural mass with spinal cord compression. Epidural biopsy showed fibrosis and non-specific inflammation. Given elevated serum IgG4 (170 mg/dL) and clinical findings, he was diagnosed with IgG4-related disease. He received high dose prednisone and etanercept without radiographic or clinical improvement. He then presented to our institution. Given high concern for RDD, he underwent FDG-PET CT which demonstrated an infiltrative process and FDG avid regions in the upper thoracic spinal cord, paranasal sinus, renal hilum, perivascular abdominal vessels, testicle, and multiple joint effusions. Biopsy of left testicle demonstrated CD163-positive histiocytes which coexpressed S100, cyclin D1, and OCT2, consistent with RDD. Biopsy of the left shoulder synovium demonstrated an atypical CD163-positive histiocytic infiltrate expressing Factor XIIIa, cyclin D1 and S100 (partial), and appeared negative for OCT2, consistent with ECD. The atypical histiocytes in both biopsies were negative for CD1a and BRAF V600E by immunohistochemistry. Genomic sequencing of the testicular tissue demonstrated a MAP2K1 (Q56P) alteration. He was treated with radiation therapy targeting the dural lesion with temporarily worsening symptoms improved with steroids and started on cobimetinib. DISCUSSION This case expands on the phenotypic description of mixed ECD/RDD. Histiocytic neoplasms should be considered in the differential diagnosis of dural based lesions.

Abstract BACKGROUND Patients with primary brain tumors often have very complex histories, but an accurate understanding of their care timeline is critical to provide the best care possible. Extracting pertinent facts from the medical record can be time consuming and frustrating. We sought to apply generative AI large language models (LLM) to this problem in order to supply providers with concise, accurate, and focused data including graphs and tables. METHODS After evaluating multiple LLMs, GEMINI 2.5 Pro was selected. Prompt engineering was iteratively refined across a range of patients to generate concise outputs using tables, graphs, and prose to describe timing of chemoradiation, tumor markers, procedures, and trends in MRI results. The model inferred BT-RADS scores from the MRI report prose. Using a 5-point Likert scale, neuroradiologists assessed the AI-output both prospectively and retrospectively comparing it to the medical record. LLM’s compared AI summaries to source material. RESULTS Six neuroradiologists each ranked 25 prospective patient outputs as accurate (82%/16%/1%), useful (94%/6%/0%), trustworthy (86%/13%/1%), and satisfactory (86%/10%/1%) for Likert ratings of highly agree/agree/neutral, respectively. No responses were disagree or highly disagree. Interobserver agreement was high (Gwent AC2 > 0.95). The LLM evaluation of referenced portions of the record determined > 85% of summary statements were supported by source documents. While users estimated time savings of a 1-10 minutes per case, they felt the greater benefit was having more organized data presented efficiently. CONCLUSIONS AI summaries of the medical record of complex patients with primary brain tumors give providers an accurate, well-organized display of the pertinent facts necessary for high quality care and save time in chart review. These summaries, which are generated early each morning, have been found to be helpful and are now being incorporated into our clinical practice and multidisciplinary tumor board.

Abstract The WHO 2021 classification of central nervous system tumors incorporated molecular markers to better define diffuse glioma subgroups. We analyzed array-based copy number, targeted next-generation sequencing, germline genotyping, and Illumina EPIC array methylation data from 404 primary IDH-mutant astrocytomas to further understand the relationship between copy number and outcomes. Loss of chromosome arm 13q was associated with poor overall survival after adjusting for age, sex, tumor grade, and treatment status (hazard ratio [HR]=2.04 (95% confidence interval: 1.25-3.33), p=0.004). Chromosome 13q loss was also significantly associated with the total number of copy number alterations (p<0.001). Loss of arm 11p was associated with poor survival in the adjusted analysis (HR=2.29 (1.38-3.79), p=0.001). Unsupervised clustering of the raw copy number data identified 12 clusters, where each cluster was defined by distinct copy number alteration(s). Clusters that contained 13q loss exhibited worse overall survival compared to other clusters. The clusters were significantly associated with age at diagnosis (p=0.015), tumor grade (p<0.001) and copy number complexity (p<0.001). The clusters with a high proportion of grade 4 tumors and with the highest complexity had the poorest overall survival. These findings highlight the prognostic relevance of chromosome 13q and 11p losses in IDH-mutant astrocytomas and support the integration of additional copy number alterations into molecular classification frameworks of IDH-mutant astrocytomas to improve risk stratification and patient management.

Abstract BACKGROUND Craniopharyngiomas are a rare tumor along the pituitary-hypothalamic axis. Genetic analysis revealed that 95% of papillary craniopharyngiomas (PCP) have BRAF V600E mutations (Brastianos et al. Nature Genetics 2014). We previously reported that BRAF/MEK inhibition was associated with significant anti-tumor activity in newly-diagnosed PCP patients (Brastianos et al. NEJM 2023). We have now evaluated the efficacy of vemurafenib/cobimetinib in a separate cohort of patients with recurrent PCP whose tumors progressed after prior radiation. METHODS In this multicenter, NCI-sponsored cooperative group trial, patients with histologically confirmed BRAF-positive PCP who progressed after radiation were treated with vemurafenib/cobimetinib. The primary endpoint of response rate (RR) based on centrally determined imaging data was to be evaluated in 16 patients, where a partial response was defined as ≥20% decrease in volume. This single arm, Simon two-stage phase 2 trial had 89% power to detect a true RR ≥ 30% (vs. null 5%; α=0.04). In this design, 3 or more observed responses in 16 evaluable patients would be considered evidence of promising activity. RESULTS Of the planned 16 patients, a total of 5 patients enrolled before the study was closed due to slow accrual. Median follow-up was 50 months (95% CI: 32 to not yet reached). Based on volumetric response criteria, all 5 patients had a response to treatment (100%; 95% CI: 47.8% to 100%). To date, 2 patients progressed, one of whom died 22 months after study entry. This cohort met the criteria for efficacy under the original design with >3 responders. No grade 4 or 5 toxicities were observed. CONCLUSIONS Vemurafenib/cobimetinib resulted in an objective response in all patients with previously treated PCP. The study met primary endpoint, similar to that reported for previously untreated PCP. Thus, BRAF/MEK inhibitors could be an effective tool for previously treated PCP and warrants further evaluation. SUPPORT U10CA180821; U10CA180882; Genentech, https://acknowledgments.alliancefound.org;ClinicalTrials.gov: NCT03224767

Abstract Aberrant vasculature is a hallmark of glioblastoma (GBM), contributing to both blood–brain barrier (BBB) dysfunction and frequent intracranial hemorrhage. Myeloid cells, including microglia and macrophages, are known to co-opt tumor vasculature during tumor progression, but the nature and consequences of their physical interactions with blood vessels require clearer definition. To address this, we characterize vessel-associated myeloid cells in murine gliomas with high spatial and temporal resolution, leveraging in vivo two-photon imaging, MRI, and transgenic mouse lines. To investigate the role of microglia in glioma vasculature, we pretreated glioma-bearing mice with CSF1R inhibitors (PLX3397 & PLX5622) to ablate microglia prior to tumor inoculation. Strikingly, over half of the microglia-depleted mice developed acute, lethal paralysis between days 11–15, whereas control tumor-bearing mice remained asymptomatic. MRI revealed extensive intracranial hemorrhage and edema, and two-photon imaging showed nodular, abnormal vasculature. This vascular dysfunction led to a dramatic reduction in median survival—from 30 days in control glioma-bearing mice to 15 days in PLX-treated mice with gliomas. To identify the protective microglial population involved, we examined vascular–myeloid interactions. We found that the peritumoral region harbored dense capillary networks supporting tumor expansion, along with a marked increase in myeloid cells with somas directly contacting blood vessels. Using TMEM119CreER/+:R26tdTomato/+ mice, we confirmed these vessel-associated cells as brain-resident microglia, not infiltrating macrophages. Quantitatively, ~60% of peritumoral microglia were vessel-associated, compared to ~30% in naïve or contralateral hemispheres. These microglia displayed elongated somata and processes aligned with vessels or wrapping around vessels, which is a phenotype also observed following single-vessel photothrombosis, suggesting a response to impaired blood flow and BBB leakage. Our findings uncover a critical neurovascular role for vessel-associated microglia in maintaining vascular integrity during glioma progression and highlight the importance of preserving, reprogramming, and further investigating this population in GBM therapies.