Immune Checkpoint Inhibitors In Glioblastoma Research Articles

Role of gut microbiota in regulating immune checkpoint inhibitor therapy for glioblastoma.

Glioblastoma (GBM) is a highly malignant, invasive, and poorly prognosed brain tumor. Unfortunately, active comprehensive treatment does not significantly prolong patient survival. With the deepening of research, it has been found that gut microbiota plays a certain role in GBM, and can directly or indirectly affect the efficacy of immune checkpoint inhibitors (ICIs) in various ways. (1) The metabolites produced by gut microbiota directly affect the host's immune homeostasis, and these metabolites can affect the function and distribution of immune cells, promote or inhibit inflammatory responses, affect the phenotype, angiogenesis, inflammatory response, and immune cell infiltration of GBM cells, thereby affecting the effectiveness of ICIs. (2) Some members of the gut microbiota may reverse T cell function inhibition, increase T cell anti-tumor activity, and ultimately improve the efficacy of ICIs by targeting specific immunosuppressive metabolites and cytokines. (3) Some members of the gut microbiota directly participate in the metabolic process of drugs, which can degrade, transform, or produce metabolites, affecting the effective concentration and bioavailability of drugs. Optimizing the structure of the gut microbiota may help improve the efficacy of ICIs. (4) The gut microbiota can also regulate immune cell function and inflammatory status in the brain through gut brain axis communication, indirectly affecting the progression of GBM and the therapeutic response to ICIs. (5) Given the importance of gut microbiota for ICI therapy, researchers have begun exploring the use of fecal microbiota transplantation (FMT) to transplant healthy or optimized gut microbiota to GBM patients, in order to improve their immune status and enhance their response to ICI therapy. Preliminary studies suggest that FMT may enhance the efficacy of ICI therapy in some patients. In summary, gut microbiota plays a crucial role in regulating ICIs in GBM, and with a deeper understanding of the relationship between gut microbiota and tumor immunity, it is expected to develop more precise and effective personalized ICI therapy strategies for GBM, in order to improve patient prognosis.

DNAR-09. THE ROLE OF MSH2 IN GLIOBLASTOMA GROWTH AND TEMOZOLOMIDE RESISTANCE

Abstract Despite all the advances in understanding and finding new therapeutic approaches, glioblastoma (GBM) remains incurable. The standard of care is surgical resection when feasible, combined with radiotherapy and chemotherapy using temozolomide (TMZ). Different mechanisms have been suggested to contribute to this failure: intrinsic or acquired resistance to TMZ and deficiencies in DNA mismatch repair (MMR) genes such as MSH2 that promote tumor progression. In this study, we have identified a correlation between low MSH2 expression and shorter patient survival utilizing patient GBM samples from the TCGA. Furthermore, we have generated immunocompetent genetically engineered mouse models (GEMMs) of GBM with germline or somatic loss of Msh2 to test the biological significance of Msh2 in GBM growth and resistance to TMZ and immunotherapy. We have generated tumors with reduced or abrogated Msh2 using GEMMs based on the RCAS/tv-a gene transfer system in combination with mice that exhibited heterozygous and homozygous loss of Msh2. Tumors with overexpression of PDGFB in combination with Tp53 silencing in mice with reduced or deficient Msh2 demonstrated shorter survival time and increased tumor growth compared to wild-type tumor-bearing mice. In addition, our results indicate that Msh2 deficiency increases the malignancy of gliomas. Finally, our data demonstrate that TMZ treatment for two weeks provides a significant survival advantage in WT tumor-bearing mice, while no efficacy was observed in tumor-bearing mice with either heterozygous or homozygous loss of Msh2, recapitulating what is observed in clinics. We are currently evaluating the role of Msh2 in the efficacy of immune checkpoint inhibitors in GBM.

Losartan and Immune Checkpoint Inhibitors in Glioblastoma: An Appropriate Substitute for Steroids.

Losartan and Immune Checkpoint Inhibitors in Glioblastoma: An Appropriate Substitute for Steroids.

The applications, limitations, and future consideration of immune checkpoint inhibitors in glioblastoma

Glioblastoma multiforme is a grade IV malignant tumor found in the brain, formed by mutated astrocytes. Patients with glioblastoma may experience headaches and nausea, and several different symptoms depending on where the tumor is located. Surgery is the primary treatment used for glioblastoma to remove the tumor, but the diffusive nature of this tumor makes it hard to completely remove. The survival years after treatments had not shown improvement with surgeries along with chemo and radiotherapy. Immune checkpoint inhibitors, a type of immunotherapy, were seen to provide a foreground to the development of an effective treatment. Immune checkpoint inhibitors block pathways that create suppression of T cells to restore their function and allow them to attack cancerous cells again, stimulating an immune response. Even though immune checkpoint inhibitors had shown effectiveness and success in preclinical trials and in treating other cancers, clinical trials using these drugs failed to show improved effectiveness and prognosis of patients with immune checkpoint inhibitors. Some patients didn’t generate a response to the checkpoint inhibitors, while for others the effect of checkpoint inhibitors lasted relatively shortly. Though, several proposals for solutions to the limitations of checkpoint inhibitors were raised by scientists. Immune checkpoint inhibitor shows the potential of being a hope to enhance survival years and prognosis of this currently uncurable disease. The research targets at discussing the mechanisms of ipilimumab, nivolumab, and bevacizumab (types of immune checkpoint inhibitors) and their limitations to provide suggestions of different methods that could be applied to potentially solve the problem and enhance their effectiveness.

Novel macrophage-related gene prognostic index for glioblastoma associated with M2 macrophages and T cell dysfunction.

This study aims to construct a Macrophage-Related Gene Prognostic Index (MRGPI) for glioblastoma (GBM) and explore the underlying molecular, metabolic, and immunological features. Based on the GBM dataset from The Cancer Genome Atlas (n = 156), 13 macrophage-related hub genes were identified by weighted gene co-expression network (WGCNA) analysis. 5 prognostic genes screened by Kaplan-Meire (K-M) analysis and Cox regression model were used to construct the MRGPI, including GPR84, NCF2, HK3, LILRB2, and CCL18. Multivariate Cox regression analysis found that the MRGPI was an independent risk factor (HR = 2.81, CI95: 1.13-6.98, p = 0.026), leading to an unfavorable outcome for the MRGPI-high group, which was further validated by 4 validation GBM cohorts (n = 728). Thereafter, the molecular, metabolic, and immune features and the clinical implications of the MRGPI-based groups were comprehensively characterized. Gene set enrichment analysis (GSEA) found that immune-related pathways, including inflammatory and adaptive immune response, and activated eicosanoid metabolic pathways were enriched in the MRGPI-high group. Besides, genes constituting the MRGPI was primarily expressed by monocytes and macrophages at single-cell scope and was associated with the alternative activation of macrophages. Moreover, correlation analysis and receiver operating characteristic (ROC) curves revealed the relevance between the MRGPI with the expression of immune checkpoints and T cell dysfunction. Thus, the responsiveness of samples in the MRGPI-high group to immune checkpoint inhibitors (ICI) was detected by algorithms, including Tumor Immune Dysfunction and Exclusion (TIDE) and Submap. In contrast, the MRGPI-low group had favorable outcome, was less immune active and insensitive to ICI. Together, we have developed a promising biomarker to classify the prognosis, metabolic and immune features for GBM, and provide references for facilitating the personalized application of ICI in GBM.

Abstract 1634: Reduction or loss of Msh2 confers resistance to temozolomide in glioblastoma

Abstract Glioblastoma (GBM) is the most common and aggressive primary brain tumor. The only intervention that has improved the survival rate of GBM patients over the past several decades has been combining temozolomide (TMZ) with radiotherapy (RT), which increased median survival by only ~2.5 months to where it currently stands at ~15 months. Unfortunately, all GBM patients eventually die due to tumor recurrence. Intrinsic or acquired resistance to TMZ is a significant contributing factor to tumor progression, and various mechanisms have been suggested, including deficiencies in DNA mismatch repair (MMR) genes such as MSH2. Utilizing patient GBM samples from the TCGA, we have identified a correlation between low MSH2 expression and shorter patient survival. To test the biological significance of Msh2 in GBM growth and resistance to TMZ and immunotherapy, we have generated immunocompetent genetically engineered mouse models (GEMMs) of GBM with germline or somatic loss of Msh2. To generate tumors with reduced or abrogated Msh2, we utilized GEMMs based on the RCAS/tv-a gene transfer system in combination with mice that exhibited heterozygous and homozygous loss of Msh2. When PDGFB was overexpressed in combination with the silencing of Tp53 to induce tumors, tumor-bearing mice with reduced or deficient Msh2 demonstrated shorter survival time compared to wild-type tumor-bearing mice. In addition, our results indicate Msh2 deficiency increases the malignancy of gliomas. Our data demonstrate that two weeks of TMZ treatment at a clinically relevant dose of 25 mg/kg provides a significant survival advantage in WT-tumor-bearing mice, while no efficacy was observed in tumor-bearing mice with either heterozygous or homozygous loss of Msh2. We are currently evaluating the role of Msh2 in the efficacy of immune checkpoint inhibitors in glioblastoma. Citation Format: Montserrat Puigdelloses Vallcorba, Alice Buonfiglioli, Gonzalo Piñero, Zhihong Chen, Dolores Hambardzumyan. Reduction or loss of Msh2 confers resistance to temozolomide in glioblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1634.

Fatty Acid Metabolic Signaling Pathway Alternation Predict Prognosis of Immune Checkpoint Inhibitors in Glioblastoma

IntroductionGlioblastoma(GBM) is a highly malignant primary brain tumor. Even after undergoing surgery and chemotherapy, patients with this affliction still have little to no chance of survival. Current research on immunotherapy treatment for GBM shows that immune-checkpoint inhibitors (ICIs) may be a promising new treatment method. However, at present, the relationship between the fatty acid metabolic process and the prognosis of GBM patients who are receiving immunotherapy is not clear.MethodsFirst, we downloaded a GBM cohort that had been treated with immunotherapy, which included the mutation and prognosis data, and the TCGA-GBM and Jonsson-GBM queues. CIBERSORT and single sample gene set enrichment analysis(ssGSEA) were used to evaluate immune cell scores. Gene set enrichment analysis (GSEA) was used to evaluate the patient’s accessment score. The pRRophetic algorithm was used to evaluate the drug sensitivity of each patient. Univariable and multivariate cox regression analyses, as well as the Kaplan-Meier (KM) method, were used to evaluate the relationship between the fatty acid metabolic process and the prognosis of GBM patients.ResultsThe univariate and multivariate cox regression models showed that the fatty acid metabolic process mutant-type (MT) can be used as an independent predictor of the efficacy of immunotherapy for GBM patients. In addition, fatty acid metabolic process MT is related with significantly longer overall survival (OS) time than the wild-type(WT) variant. However, the mutation status of the fatty acid metabolic process has nothing to do with the prognosis of GBM patients who are receiving conventional treatment. Our analysis showed that fatty acid metabolic process MT correlated with significantly increased natural killer T (NKT) cells and significantly decreased CD8+T cells. At the same time, GSEA analysis revealed that fatty acid metabolic process MT was associated with significantly increased immune activation pathways and an enriched fraction of cytokine secretion compared with WT.ConclusionsWe found that fatty acid metabolic process MT may be used as an independent predictor of the efficacy of ICI treatment in GBM patients. Use of the fatty acid metabolic process MT will result in higher immunogenicity rates, a significant increase in the proportion of activated immune cells, and improvement of the immune microenvironment.

Profiling of inhibitory immune checkpoints in glioblastoma: Potential pathogenetic players.

Glioblastoma (GBM) represents the most frequent glial tumor, with almost 3 new cases per 100,000 people per year. Despite treatment, the prognosis for GBM patients remains extremely poor, with a median survival of 14.6 months, and a 5-year survival less than 5%. It is generally believed that GBM creates a highly immunosuppressive microenvironment, sustained by the expression of immune-regulatory factors, including inhibitory immune checkpoints, on both infiltrating cells and tumor cells. However, the trials assessing the efficacy of current immune checkpoint inhibitors in GBM are still disappointing. In the present study, the expression levels of several inhibitory immune checkpoints in GBM (CD276, VTCN1, CD47, PVR, TNFRSF14, CD200, LGALS9, NECTIN2 and CD48) were characterized in order to evaluate their potential as prognostic and eventually, therapeutic targets. Among the investigated immune checkpoints, TNFRSF14 and NECTIN2 were identified as the most promising targets in GBM. In particular, a higher TNFRSF14 expression was associated with worse overall survival and disease-free survival, and with a lower Th1 response.

Glucocorticoids and immune checkpoint inhibitors in glioblastoma.

Immunotherapy, activation of the immune system to target tumor cells, represents a paradigm shift in the treatment of cancer. Immune checkpoint therapies, which target immunomodulatory molecules expressed on T-lymphocytes, have demonstrated improved survival in a variety of malignancies. However, benefit in glioblastoma, the most common and devastating malignant brain tumor, remains to be seen. With several recent clinical trials failing to show efficacy of immunotherapy, concerns have been raised regarding the impact of glucocorticoid use in this patient population that may impair the ability for immune checkpoint inhibitors to affect a response. For this article we examined the mechanism by which immune checkpoint inhibitors activate, and glucocorticoids impair, T-lymphocyte function. In this context, we review the clinical data of immune checkpoint inhibitors in glioblastoma as well as the impact glucocorticoids have on immune checkpoint inhibitor efficacy. Finally, we highlight key questions that remain in the field, and the potential benefit of further research for central nervous system tumors. More information on the extent, character and duration of glucocorticoids on patients treated with PD-(L)1 will better inform both clinical management and novel therapeutic development of immunotherapy in patients with CNS malignancies.

IMMU-05. DISRUPTION OF THE CCR2 CHEMOKINE RECEPTOR PATHWAY OVERCOMES THERAPEUTIC RESISTANCE TO PD-1 BLOCKADE IN MALIGNANT GLIOMA

Abstract INTRODUCTION Large scale clinical trials have failed to determine efficacy of adjuvant PD-1 blockade in recurrent glioblastoma (GBM). However, recent phase 2 clinical trial results demonstrating the potential of neo-adjuvant anti-PD-1 treatment have renewed enthusiasm for the use of immune checkpoint inhibitors (ICIs) in GBM. Additional benefit of ICIs in GBM will likely derive from development of novel therapies directed against immunosuppressive resistance mechanisms. Chemokine receptor 2 (CCR2) expressing tumor infiltrative immune suppressive myeloid cells represent a targetable axis within ICI resistant gliomas. We have established that CCR2 disruption unmasks an effect of anti-PD-1 therapy in ICI resistant murine glioma models. However, the mechanism(s) by which combined inhibition of PD-1 and CCR2 achieves efficacy is unknown. OBJECTIVE Determine the impact of combination anti-PD-1 and CCR2 antagonism on immune cells within anti-PD-1 resistant gliomas. METHODS Immune cell characteristics were determined in CCR2 antagonist (CCX872)/anti-PD-1 treated KR158 or 005 GSC glioma-bearing wild type or CCR2+/rfp/CX3CR1+/gfp reporter mice. RESULTS CCX872 increased median survival (32 vs. 50 days, P=.002) in KR158 tumor-bearing animals and in combination with anti-PD-1 significantly increased durable survival (P=.0005). In 005 GSC glioma-bearing mice, combination therapy also enhanced median survival (30 vs. 49 days, P=.005). CCX872 decreased CD45+/CD11bhi/Ly6Chi MDSCs (40%, P=.038) within gliomas, and increased these cells within bone marrow in both models (74%, P=.020). Three distinct intra-tumoral populations of CCR2+ and CX3CR1+ cells were identified in both glioma models including CCR2+/CX3CR1-/CD45hi/CD11blo, CCR2+/CX3CR1+/CD45hi/CD11bhi/Ly6Chi, and CX3CR1+/CD45lo/CD11bhi/F4/80+/MHCII+, with both CCR2+ populations being reduced by CCX872 treatment. Examination of tumor infiltrating lymphocytes revealed both increased presence and decreased exhaustion (PD-1+/Tim3+) of CD4+ (P=.029) and CD8+ (P=.011) T-cells following CCX872/anti-PD-1 treatment. CONCLUSION CCX872/anti-PD-1 combination therapy is effective in clinically relevant murine glioma models, providing a basis to progress this novel combinatorial treatment to human clinical trials.

PD-1/PD-L1 immune-checkpoint inhibitors in glioblastoma: A concise review.

Glioblastoma is the most aggressive and most common primary brain tumor in adults, with a very poor prognosis, due to limited therapeutic efficacy of available treatments. The promising data deriving from the use of immune checkpoint inhibitors (ICI) in other cancers have prompted evaluation of its efficacy and possible use in patients with glioblastoma. In this review, we analyzed the available data about these drugs in glioblastoma. Although data are not yet mature and preliminary studies do not show a clear-cut benefit, we are far from excluding the concrete possibility of using ICI as potential treatment in patients with glioblastoma. Moreover, many molecular and immunological aspects of this approach have yet to be clarified. For this reason, it is essential to identify potential predictive biomarkers for the selection of patients who will benefit most from treatment with ICI. Additional effort is needed to better understand the mechanisms that will allow us to establish whether ICI have a place in the treatment of patients with glioblastoma.

Combination of oncolytic viruses and immune checkpoint inhibitors in glioblastoma

Glioblastoma is associated with poor prognosis with a mean survival of 15 months after diagnosis. The current standard of care includes surgery, radiation, and temozolomide with the use of tumor-treating fields in select patient population. The past decade has witnessed a convergence in our understanding of tumor biology and the role of the immune system in fighting cancer. The highly immunosuppressive tumor microenvironment exerted by glioblastoma cells has contributed to the lack of success of novel immunotherapies till date (including checkpoint inhibitors). Oncolytic viral-based approaches are of renewed interest given advances in tumor cell tropism, pathogenicity, and immunogenicity. More importantly, oncolytic viruses have been shown to initiate a broad immune response through various mechanisms including dual activation of the innate and adaptive arms of the host immune system. Because the initial clinical studies with monotherapy checkpoint inhibition in glioblastoma have failed to demonstrate a survival advantage, most trials in glioblastoma are testing combinations that seek to augment the immune response through mutually reinforcing approaches that can overcome the immunosuppressive milieu. Preclinical data in glioblastoma models with combined oncolytic viruses therapy and checkpoint blockade are favorable and provide rationale to initiate first-in-human trials. Even though the number of clinical trials testing this combination in glioblastoma is limited, more studies are expected in the future.

Use of targeted next generation sequencing (NGS) to assess mutational load in glioblastoma (GBM).

2027 Background: Trials of immune checkpoint inhibitors in GBM are ongoing. Evidence from other tumors suggests that high mutational load predicts response to these agents. We estimated mutational load in adults with newly diagnosed GBM using targeted NGS and assessed its association with other clinicopathologic parameters. Methods: NGS was performed for all patients diagnosed with isocitrate dehydrogenase wild-type (IDH-WT) GBM at our institution since September 1, 2016. Our panel performs targeted exome sequencing of 153 cancer-related genes (+/- 10 bp at intron/exon boundaries) and detects insertions, deletions, and single nucleotide variants at an allele frequency of 2%. Polymorphisms present in > 0.1% of the population according to the ExAC database and 1000 Genomes Project were filtered to reduce germline variants in the absence of matched normals. To avoid upward skewing of mutational load due to the panel’s preferential detection of genes recurrently mutated in cancer, alterations with known or likely functional disruption per the COSMIC database and/or our internal variant knowledge base were also not counted. The number of mutations counted was divided by the coding region target territory of the NGS panel (~0.5 Mb) to extrapolate mutational load to the whole exome. The Mann-Whitney U test was used to compare mutational load according to sex, age (≥65 vs. < 65), and MGMT methylation status (positive vs. negative). Results: Of 28 patients, median age was 65, 75% were male, and 37% were MGMT-methylated. Mean mutational load was 3.6 mutations/Mb (range 0-8, standard deviation 2.3) and was higher in males (4.3, 95% CI 3.3-5.3) compared to females (1.4, 95% CI 0.03-2.8) (p = 0.004). Mutational load did not differ according to age or MGMT methylation. Conclusions: In newly diagnosed IDH-WT GBM, targeted NGS revealed an estimated mutation rate similar to that reported in whole exome sequencing studies. In addition, we detected a higher mutational load in males compared to females. The latter finding adds to recent evidence suggesting sex-specific differences in the biology of GBM, and implies that future studies should account for sex when assessing mutational load as a predictive marker of immune checkpoint inhibition.

Possible role for immune checkpoint inhibitors in glioblastoma

Possible role for immune checkpoint inhibitors in glioblastoma