Hormigo, Adı́lia

Abstract Background Immunotherapy has yet to make significant gains in glioblastoma (GBM) treatment, due in part to GBM-mediated immune suppression. Increasing evidence points to critical roles for tumor-derived extracellular vesicles (EVs) and immunosuppressive myeloid cells as key factors in this process. Methods Immunophenotyping of the tumor-immune microenvironment was performed using ultrasonic aspirate collected during GBM resection by high-dimensional flow cytometry. EVs collected from patient-derived GBM cell lines were used to condition myeloid cells collected from healthy donors to generate immunosuppressive myeloid cells. siRNA was used to knockdown TIGIT and/or NLRP3 expression prior to EV conditioning. T cell co-culture studies were performed with donor-matched T cells. Results Immune phenotyping of the tumor microenvironment and EV-conditioned myeloid cells revealed similar immunomodulatory protein expression across myeloid cell populations, with particularly elevated TIGIT expression. Knockdown of TIGIT reduced the immunosuppressive polarization of myeloid cells, resulting in improved T cell function. This finding proceeded in an NLRP3-dependent manner, with substantial co-expression of TIGIT and NLRP3 expression prior to knockdown, and concomitant knockdown of NLRP3 abrogating the effect of TIGIT knockdown. TIGIT expression correlated with increased IL-13 expression, and IL-13 blockade unmasked a pro-inflammatory myeloid cell phenotype. Conclusion TIGIT expression in myeloid cells in the GBM microenvironment is a functional marker of immunosuppressive activity, with TIGIT knockdown reducing IL-13 expression and unmasking the pro-inflammatory activity of NLRP3. This study bolsters our understanding of the immunosuppressive complexities of the GBM microenvironment and supports attenuation of immunosuppressive myeloid cell activity as a strategy to restore immune function in GBM.

Abstract Glioblastoma (GBM) is a deadly brain cancer with near-universal recurrence despite maximal treatment for which new innovations are sorely needed. Immunotherapy has yet to make significant gains in GBM treatment despite revolutionizing other cancer therapies, due in part to GBM-mediated immune suppression. This immune derangement proceeds through several mechanisms, but increasing evidence points to critical roles for tumor-derived extracellular vesicles (EVs) and immunosuppressive myeloid cells as key factors in this process. In the present study, we demonstrate broad expression of TIGIT across myeloid cell populations in the GBM microenvironment, a finding recapitulated by conditioning healthy monocytes with GBM-derived EVs. Further, knockdown of TIGIT expression reduced the immunosuppressive polarization of monocytes, resulting in improvement in T cell function. This finding proceeded in an NLRP3-dependent manner, with substantial co-localization of TIGIT and NLRP3 expression prior to knockdown. These findings point to a novel role for TIGIT expression in diverse myeloid cells in the GBM microenvironment as a marker of immunosuppressive activity and further indicate a hierarchy of immunomodulatory protein activity in these myeloid cells, with TIGIT knockdown unmasking the pro-inflammatory activity of NLRP3. This study bolsters understanding of the immunosuppressive complexities of myeloid cells in the GBM microenvironment, while lending further support to prevention or attenuation of immunosuppressive myeloid cell activity as a means of restoring immune function in GBM. Graphical abstract (Created in BioRender. Asad, M. (2025) https://BioRender.com/euiljoq Key Points Tumor-mediated immune suppression is a key barrier to the development of effective immunotherapies for GBM. TIGIT is broadly expressed in myeloid cells within the GBM microenvironment and can be induced by GBM-derived extracellular vesicles. Knockdown of TIGIT reduces immunosuppressive polarization of monocytes and enhances T cell activity via NLRP3 signaling, implicating TIGIT expression as a targetable modifier of immunosuppressive activity in GBM-associated myeloid cells. Importance of the Study Glioblastoma (GBM) remains a formidable clinical challenge, with poor prognosis and limited response to current immunotherapies. This study uncovers a novel immunosuppressive axis involving TIGIT expression in myeloid cells, which are key players in the GBM tumor microenvironment. By demonstrating GBM-derived extracellular vesicles induce TIGIT in healthy monocytes and TIGIT knockdown diminishes immunosuppressive polarization in an NLRP3-dependent manner, this study highlights TIGIT as both a marker and modulator of immune dysfunction in GBM. These findings introduce a functional hierarchy of immunoregulatory proteins in tumor-associated myeloid cells, positioning TIGIT as a potential checkpoint target. Restoring immune activity by disrupting this axis could enhance the efficacy of immunotherapy in GBM. Thus, this research not only advances our understanding of tumor-induced immune suppression but also opens a promising therapeutic avenue to reinvigorate anti-tumor immunity in a cancer type historically resistant to immunotherapeutic approaches.

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 Patients with glioblastoma (GBM) have a poor prognosis and limited effective treatment options. Bevacizumab has been approved for treatment of recurrent GBM, but there is questionable survival benefit. Based on preclinical and early clinical data indicating that CD105 upregulation may represent a mechanism of resistance to bevacizumab, we hypothesized that combining bevacizumab with the anti-CD105 antibody TRC105 may improve efficacy in recurrent GBM. Methods Phase I dose-escalation/comparative randomized phase II trial in patients with GBM. During phase I, the maximum tolerated dose (MTD) of TRC105 in combination with bevacizumab was determined. In phase II, patients were randomized 1:1 to TRC105 and bevacizumab or bevacizumab monotherapy. Patients received TRC105 (10 mg/kg) weekly and bevacizumab (10 mg/kg) every 2 weeks. Efficacy, as assessed by progression-free survival (PFS), was the primary endpoint; safety, quality of life, and correlative outcomes were also evaluated. Results In total, 15 patients were enrolled in phase I and 101 in phase II; 52 patients were randomized to TRC105 with bevacizumab and 49 to bevacizumab monotherapy. The MTD was determined to be 10 mg/kg TRC105 weekly plus bevacizumab 10 mg/kg every 2 weeks. An increased occurrence of grade ≥3 adverse events was seen in the combination arm, including higher incidences of anemia. Median PFS was similar in both treatment arms: 2.9 months for combination versus 3.2 months for bevacizumab monotherapy (HR = 1.16, 95% CI = 0.75–1.78, P = .51). Quality of life scores were similar for both treatment arms. Conclusions TRC105 in combination with bevacizumab was well tolerated in patients with recurrent GBM, but no difference in efficacy was observed compared to bevacizumab monotherapy.

2023 Background: TRC105 is a humanized antibody targeting CD105 (endoglin), a member of the TGFβ receptor superfamily. CD105 is expressed in glioma stem cells and circulating endothelial cells (CECs) in GBM patients (pts), increasing following VEGF inhibition. N1174 was conducted in recurrent bevacizumab (bev) naïve GBM pts to investigate the hypothesis that CD105 blockade+bev can delay development of bev resistance. Methods: After a ph I cohort (15 pts) established the ph II dose of TRC105 as 10 mg/kg IV over 4 hours every 7 days in combination with standard dose bev, the ph II trial used 1:1 randomization with 90% power and 0.10 type I error to detect a 3 month (mo) difference in progression-free survival (PFS) between the two arms. CECs including CD105 positive subsets were measured by flow cytometry at baseline and multiple time points. Results: Based on 101 evaluable ph II pts, there was no significant difference in PFS between TRC105+bev and bev only (2.9 vs 3.2 mo, respectively; HR=1.14, 95% CI 0.73-1.77, p=0.57), or overall survival (10.0 vs 7.4 mo; HR 1.02 95% CI 0.63-1.65, p=0.93). Response rate (complete or partial) was 12.2% (6/49) for TRC105+bev and 11.6% (5/43) for bev only. Overall incidence of grade (gr) 3+ toxicity was higher for TRC105+bev (67.3% vs 32.7%, p<0.001) mainly due to 14 pts with gr 3 anemia in the TRC105+bev arm vs 0 in the bev only pts. Gr 3+ non-heme toxicities were higher in pts receiving TRC105+bev vs bev only (50% vs 30.6%, p=0.07), mainly due to headache (6 vs 1 pts) and hyperglycemia (3 vs 0 pts). CECs remained stable in combination treated pts, suggesting a possible impact of the anti-CD105 blockade, but increased at progression in the bev only arm. There was no association between PFS and initial changes in CEC values, independent of treatment received. Conclusions: TRC105 plus bev did not prolong median PFS vs single agent bev in recurrent GBM pts, although it was associated with a non-significant prolongation of OS. These data and associated correlative analysis of CECs from study pts point against endoglin being a clinically significant factor for the development of bev resistance. Support: U10CA180821, U10CA180882. Clinical trial information: NCT01648348.