Citations

Abstract Introduction Glioblastoma (GBM), the most aggressive primary brain tumor in adults, is marked by profound immune suppression. Tumor-derived extracellular vesicles (TEVs) are increasingly recognized as key mediators of this immunosuppressive environment. Methods In this study, we examined the tumor-immune microenvironment using ultrasonic aspirate samples from GBM patients (n = 14). Results Several immune checkpoint molecules, including PDL1, B7-H3, and VISTA, were notably elevated. TIGIT, a receptor typically associated with T cells, was widely expressed across multiple myeloid subsets, including monocytic myeloid-derived suppressor cells (mMDSCs; 64.27±7.99%) and non-classical monocytes (NCM; 39.8±4.37%). Co-culture of healthy donor CD11b+ cells (n = 10) with TEVs replicated similar effects (mMDSCs; control 11.691.87 vs EV treated 23.322.0). We found CD155, a primary TIGIT ligand, to be heavily enriched in TEVs and co-localized with TIGIT in co-culture, suggesting the TIGIT/CD155 axis may be involved in promoting immune suppression. induced MDSCs markedly suppressed T cell proliferation (30.65 ± 5.97% vs. control 86.47 ± 2.94, p = 0.0001), accompanied by elevated Th2 cytokine production and increased NLRP3 and IL-1β expression. Interestingly, TIGIT knockdown did not affect NLRP3 expression, but did restore T cell proliferation (64.13±1.33%; p = 0.02) and pro-inflammatory cytokine production. However, this effect was lost upon NLRP3 knockdown, indicating its essential role in mediating immune rescue. Furthermore, IL-13 (a Th2 cytokine) blockade, in this model, enhanced pro-inflammatory response by suppressing phosphorylation of STAT-6 protein. Conclusion Overall, our findings highlight a crucial role for the TIGIT/CD155 axis in driving myeloid-mediated immune suppression in GBM. Furthermore, TIGIT inhibition may unmask NLRP3 function, potentially contributing to immune rescue. Funding Source Neurosurgery Research & Education Foundation through the B*CURED & NREF Young Clinician Investigator Award, as well as intramural K12 funding through the Institute for Clinical and Translational Research and the NCI Paul Calabresi Career Development Award (1K12CA279871). Topic Categories Tumor Immunology: Cellular Responses and Tumor Microevironment (TIME)

Abstract Description Glioblastoma (GBM), the most common and malignant primary brain tumor, exhibits profound immune suppression, hindering immunotherapy efficacy. GBM-derived extracellular vesicles (EVs) play a major role through the immunosuppressive polarization of myeloid cells. Inhibition of EV-myeloid cell interactions thus represents a novel target to mitigate GBM-mediated immune suppression. However, there are multiple mechanisms of EV-target interaction, and downstream pathways of GBM-EV signaling are poorly understood. We explored two pharmacological agents targeting different mechanisms of EV uptake: Methyl-B-cyclodextrin (MBCD), which disrupts lipid rafts, and cytochalasin D, which inhibits actin polymerization. Our results showed immunosuppressive myeloid cell (CD11b+/ CD15-/ HLA-DRlow/ CD14high) populations increased upon GBM-EV treatment. Following cytochalasin D treatment, fewer immunosuppressive myeloid cells were observed (7.40%±1.01 vs. untreated 9.66%±2.86), with rescuing T cell proliferation. Conversely, MBCD treatment increased immunosuppressive myeloid cell levels (10.42%±2.38 vs. untreated 8.87%±3.97) without impacting T cell proliferation. This study demonstrates the feasibility of pharmacologically targeting EV-myeloid cell interactions to rescue tumor mediated immune suppression by inhibiting actin-dependent endocytosis with cytochalasin D. The converse results using MBCD treatment indicate differential importance of different EV uptake pathways in monocyte regulation. Topic Categories Tumor Immunology: Cellular Responses and Tumor Microevironment (TIME)

Abstract Description Glioblastoma (GBM), the most common and malignant primary brain tumor, exhibits profound immune suppression, hindering immunotherapy efficacy. GBM-derived extracellular vesicles (EVs) play a major role through the immunosuppressive polarization of myeloid cells. Inhibition of EV-myeloid cell interactions thus represents a novel target to mitigate GBM-mediated immune suppression. However, there are multiple mechanisms of EV-target interaction, and downstream pathways of GBM-EV signaling are poorly understood. We explored two pharmacological agents targeting different mechanisms of EV uptake: Methyl-B-cyclodextrin (MBCD), which disrupts lipid rafts, and cytochalasin D, which inhibits actin polymerization. Our results showed immunosuppressive myeloid cell (CD11b+/ CD15-/ HLA-DRlow/ CD14high) populations increased upon GBM-EV treatment. Following cytochalasin D treatment, fewer immunosuppressive myeloid cells were observed (7.40%±1.01 vs. untreated 9.66%±2.86), with rescuing T cell proliferation. Conversely, MBCD treatment increased immunosuppressive myeloid cell levels (10.42%±2.38 vs. untreated 8.87%±3.97) without impacting T cell proliferation. This study demonstrates the feasibility of pharmacologically targeting EV-myeloid cell interactions to rescue tumor-mediated immune suppression by inhibiting actin-dependent endocytosis with cytochalasin D. The converse results using MBCD treatment indicate differential importance of different EV uptake pathways in monocyte regulation. Topic Categories Tumor Immunology: Checkpoints, Prevention, and Treatment (TIPT)

Abstract Description Glioblastoma (GBM), the most common and deadly primary brain tumor in adults, is associated with profound local and systemic immune suppression. Increasing evidence points to tumor-derived extracellular vesicles (EVs) as key mediators of this immunosuppression. In surveying the tumor-immune microenvironment in samples of ultrasonic aspirate collected during surgical resection of GBM (n = 12), we identified several key immunomodulatory markers expressed across a range of immune cells in the tumor microenvironment. Particularly, we found TIGIT, classically understood as a T cell inhibitory protein, expressed across a range of myeloid cell populations, including in myeloid-derived suppressor cells (MDSCs, 46.84±16.78% of total monocytic MDSCs). Co-culture of healthy donor monocytes (n = 10) with patient-derived EVs replicated similar effects (control 11.69±1.87 vs EV treated 23.32±2.0). Furthermore, Induced MDSCs significantly inhibit T cell proliferation (30.65±5.97% proliferation, v/s control 86.47±2.94, p = 0.0001), concomitant with a surge in Th2 immune responses via TIGIT+ suppressive monocytes. Targeted TIGIT inhibition restored T cell proliferation (64.13±1.327% v/s non-inhibited, 30.65±5.97%; p = 0.02) and protective immune response, confirming a pivotal role of TIGIT in immune suppressive GBM microenvironment. Furthermore, TIGIT inhibition may unmask NLRP3 function, potentially contributing to immune rescue. Funding Sources Neurosurgery Research& Education Foundation, K12 grant Topic Categories Tumor Immunology: Checkpoints, Prevention, and Treatment (TIPT)

Abstract Glioblastoma (GBM), the most aggressive primary brain tumor in adults, is marked by profound immune suppression. Tumor-derived extracellular vesicles (TEVs) are increasingly recognized as key mediators of this immunosuppressive environment. In this study, we examined the tumor-immune microenvironment using ultrasonic aspirate samples from GBM patients (n = 14). Several immune checkpoint molecules, including PDL1, B7-H3, and VISTA, were notably elevated. TIGIT, a receptor typically associated with T cells, was widely expressed across multiple myeloid subsets, including monocytic myeloid-derived suppressor cells (mMDSCs; 64.27 ± 7.99%) and non-classical monocytes (NCM; 39.8 ± 4.37%). Co-culture of healthy donor monocytes (n=10) with TEVs replicated similar effects (control 11.69±1.87 vs EV treated 23.32±2.0). We found CD155, the primary TIGIT ligand, to be heavily enriched in TEVs and co-expressed with TIGIT in co-culture, suggesting the TIGIT/CD155 axis may be involved in promoting immune suppression. Additionally, induced MDSCs significantly inhibit T cell proliferation (30.65±5.97% proliferation, v/s control 86.47±2.94, p=0.0001), concomitant with a surge in Th2 immune responses via TIGIT+ monocytes along with an increase in NLRP3 and IL-1β expressing cells. Interestingly, TIGIT knockdown did not affect NLRP3 expression but did restore T cell proliferation (64.13 ± 1.33%; p = 0.02) and pro-inflammatory cytokine production. However, the restoration of T cell proliferation was lost when NLRP3 was also silenced, indicating its essential role in mediating immune rescue. Overall, our findings highlight a crucial role of TIGIT in driving myeloid-mediated immune suppression in GBM. Furthermore, TIGIT inhibition may unmask NLRP3 function, potentially contributing to immune rescue.

Abstract Standard of care (SOC) for ndGBM begins with maximal safe resection followed by adjuvant radiotherapy and temozolomide, and maintenance temozolomide. IGV-001 is an autologous biologic-device combination immunotherapy for the treatment of ndGBM that consists of autologous GBM tumor cells and an antisense oligonucleotide against IGF-1R mRNA, irradiated and administered via biodiffusion chambers implanted in the abdomen. In a phase 1b study, IGV-001 was well tolerated without unexpected adverse events in subjects with ndGBM. Multiple efficacy signals were observed, including significant improvements in progression-free survival (PFS), overall survival (OS), radiographic evidence of tumor response, and changes in immune response biomarkers. Here, we present early safety data from the phase 2b randomized, multicenter, double-blind, placebo-controlled study (NCT04485949) designed to assess efficacy and safety of IGV-001 in subjects with ndGBM across 20 sites in the United States. After surgical resection, subjects were randomized 2:1 and treated with IGV-001 or placebo followed by SOC. The primary outcome is PFS, defined as the time from randomization to first progression, as determined by blinded central radiology review, or death. Secondary outcomes include OS, defined as the time from randomization to death due to any cause, and safety. As of May 22, 2024, 99 subjects were randomized and 95 implanted with IGV-001 or placebo plus SOC. A total of 39/45 (86.7%) subjects had sufficient follow-up time after initiated treatment with concurrent radiation and temozolomide. Nine of 72 randomized (12.5%) discontinued treatment, including 7 who stopped during the SOC treatment period. None ceased treatment for adverse events, protocol deviations, or death. A total of 11/72 (15.3%) randomized subjects discontinued the study after randomization. A review of blinded safety data did not show any emerging risk and supports no change to the benefit-risk profile of IGV-001 versus placebo. Updated data will be presented.

Abstract BACKGROUND Glioblastoma (GBM) is the most common primary brain malignancy in adults. Standard of care (SOC) for suspected GBM begins with maximal safe resection followed by adjuvant radiotherapy and temozolomide, and maintenance temozolomide. Imvax has utilized its Goldspire™ platform to create IGV-001, an autologous biologic-device combination product for the treatment of newly diagnosed GBM (ndGBM). IGV-001 consists of autologous GBM tumor cells and an antisense oligonucleotide against IGF-1R mRNA (IMV-001), irradiated and administered via biodiffusion chambers implanted in the abdomen. Together, these components stimulate immunogenic cell death and antigen release. In a phase 1b study in patients with ndGBM, IGV-001 was well tolerated without unexpected adverse events. Multiple efficacy signals were also observed, including significant improvements in progression-free survival, overall survival, radiographic evidence of tumor response, and changes in immune response biomarkers. A phase 2b randomized, multicenter, double-blind, placebo-controlled study to assess the safety and efficacy of IGV-001 in patients with ndGBM (ClinicalTrials.gov identifier: NCT04485949) is ongoing. Here, we present the first safety data from the study. MATERIAL AND METHODS After surgical resection, patients are treated with IGV-001 or placebo followed by SOC. The study will enroll approximately 93 patients at 20 sites in the United States, with a 2:1 randomization favoring IGV-001. The primary outcome is progression-free survival, defined as the time from randomization to first progression, as determined by blinded central radiology review, or death. Secondary outcomes include overall survival, defined as the time from randomization to death due to any cause, and safety. RESULTS As of February 2, 2024, a total of 72 patients have been randomized and 69 have been implanted with IGV-001 or placebo plus SOC. The median age was 60.0 years (range, 24-70 years). Most randomized patients (76.4%) were 51-70 years of age, and the male:female ratio was 2.27. A total of 39/45 (86.7%) patients with enough follow-up time, initiated treatment with concurrent radiation and temozolomide. A total of 9/72 (12.5%) randomized patients discontinued treatment, including 7 patients who discontinued during the SOC treatment period. No patients discontinued treatment for adverse events, protocol deviations, or death. A total of 11/72 (15.3%) randomized patients discontinued the study after randomization. CONCLUSION To date, the review of blinded safety data did not show any emerging risk and supports that there is no change to the benefit-risk profile of treatment with IGV-001 versus placebo. The data will be updated before presentation.

Abstract Glioblastoma (GBM) is the most common primary brain malignancy in adults. Standard of care (SOC) for suspected GBM begins with maximal safe resection followed by adjuvant radiotherapy and temozolomide, and maintenance temozolomide. Imvax has developed the Goldspire™ platform to create IGV-001, an autologous biologic-device combination product for the treatment of newly diagnosed GBM (ndGBM). IGV-001 consists of autologous GBM tumor cells and an antisense oligonucleotide against IGF-1R mRNA (IMV-001), irradiated and administered via biodiffusion chambers implanted in the abdomen. Together, these components stimulate immunogenic cell death and antigen release. IGV-001 was well tolerated and multiple efficacy signals were observed in a Phase 1b study in patients with ndGBM, including significant improvements in progression-free survival (PFS), radiographic evidence of tumor response, and changes in immune response biomarkers. A Phase 2b randomized, multicenter, double-blind, placebo-controlled study has been initiated to assess the safety and efficacy of IGV-001 in patients with ndGBM (NCT04485949). After surgical resection, patients will be treated with IGV-001 or placebo followed by SOC. 25 US sites have been selected with a target enrollment of 93 patients (2:1 randomization) and the study is open to enrollment. Key inclusion criteria are 18 to 70 years of age, Karnofsky performance status score ≥ 70, diagnosis of GBM based on the treating neurosurgeon's best clinical judgement, confirmed measurable disease pre-operatively, tumor located in the supratentorial compartment, and adequate bone marrow and organ function. Key exclusion criteria include bihemispheric disease, multicentric disease, or treatment with Tumor Treating Fields prior to documented progression. The primary outcome is PFS, defined as the time from randomization to first progression, as determined by blinded central radiology review, or death. Secondary outcomes include overall survival, defined as the time from randomization to death due to any cause, and safety.