Intrinsically de-sialylated CD103(+) CD8 T cells mediate beneficial anti-glioma immune responses

Sialic acid in the regulation of blood cell production, differentiation and turnover

Sialic acid is a unique sugar moiety that resides in the distal and most accessible position of the glycans on mammalian cell surface and extracellular glycoproteins and glycolipids. The potential for sialic acid to obscure underlying structures has long been postulated, but the means by which such structural changes directly affect biological processes continues to be elucidated. Here, we appraise the growing body of literature detailing the importance of sialic acid for the generation, differentiation, function and death of haematopoietic cells. We conclude that sialylation is a critical post-translational modification utilized in haematopoiesis to meet the dynamic needs of the organism by enforcing rapid changes in availability of lineage-specific cell types. Though long thought to be generated only cell-autonomously within the intracellular ER-Golgi secretory apparatus, emerging data also demonstrate previously unexpected diversity in the mechanisms of sialylation. Emphasis is afforded to the mechanism of extrinsic sialylation, whereby extracellular enzymes remodel cell surface and extracellular glycans, supported by charged sugar donor molecules from activated platelets.

Immunotherapeutic Strategies for the Treatment of Glioblastoma: Current Challenges and Future Perspectives

Despite decades of research and the best up-to-date treatments, grade 4 Glioblastoma (GBM) remains uniformly fatal with a patient median overall survival of less than 2 years. Recent advances in immunotherapy have reignited interest in utilizing immunological approaches to fight cancer. However, current immunotherapies have so far not met the anticipated expectations, achieving modest results in their journey from bench to bedside for the treatment of GBM. Understanding the intrinsic features of GBM is of crucial importance for the development of effective antitumoral strategies to improve patient life expectancy and conditions. In this review, we provide a comprehensive overview of the distinctive characteristics of GBM that significantly influence current conventional therapies and immune-based approaches. Moreover, we present an overview of the immunotherapeutic strategies currently undergoing clinical evaluation for GBM treatment, with a specific emphasis on those advancing to phase 3 clinical studies. These encompass immune checkpoint inhibitors, adoptive T cell therapies, vaccination strategies (i.e., RNA-, DNA-, and peptide-based vaccines), and virus-based approaches. Finally, we explore novel innovative strategies and future prospects in the field of immunotherapy for GBM.

A Holistic Approach to Hard-to-Treat Cancers: The Future of Immunotherapy for Glioblastoma, Triple Negative Breast Cancer, and Advanced Prostate Cancer

Immunotherapy represents an attractive avenue for cancer therapy due to its tumour specificity and relatively low frequency of adverse effects compared to other treatment modalities. Despite many advances being made in the field of cancer immunotherapy, very few immunotherapeutic treatments have been approved for difficult-to-treat solid tumours such as triple negative breast cancer (TNBC), glioblastoma multiforme (GBM), and advanced prostate cancer (PCa). The anatomical location of some of these cancers may also make them more difficult to treat. Many trials focus solely on immunotherapy and have failed to consider or manipulate, prior to the immunotherapeutic intervention, important factors such as the microbiota, which itself is directly linked to lifestyle factors, diet, stress, social support, exercise, sleep, and oral hygiene. This review summarises the most recent treatments for hard-to-treat cancers whilst factoring in the less conventional interventions which could tilt the balance of treatment in favour of success for these malignancies.

Tumor-resident memory T cells as a biomarker of the response to cancer immunotherapy

Tumor-infiltrating lymphocytes (TIL) often include a substantial subset of CD8+ tissue-resident memory T (TRM) cells enriched in tumor-specific T cells. These TRM cells play a major role in antitumor immune response. They are identified on the basis of their expression of the CD103 (αE(CD103)β7) and/or CD49a (α1(CD49a)β1) integrins, and the C-type lectin CD69, which are involved in tissue residency. TRM cells express several T-cell inhibitory receptors on their surface but they nevertheless react strongly to malignant cells, exerting a strong cytotoxic function, particularly in the context of blocking interactions of PD-1 with PD-L1 on target cells. These TRM cells form stable conjugates with autologous tumor cells and interact with dendritic cells and other T cells within the tumor microenvironment to orchestrate an optimal in situ T-cell response. There is growing evidence to indicate that TGF-β is essential for the formation and maintenance of TRM cells in the tumor, through the induction of CD103 expression on activated CD8+ T cells, and for the regulation of TRM effector functions through bidirectional integrin signaling. CD8+ TRM cells were initially described as a prognostic marker for survival in patients with various types of cancer, including ovarian, lung and breast cancers and melanoma. More recently, these tumor-resident CD8+ T cells have been shown to be a potent predictive biomarker of the response of cancer patients to immunotherapies, including therapeutic cancer vaccines and immune checkpoint blockade. In this review, we will highlight the major characteristics of tumor TRM cell populations and the possibilities for their exploitation in the design of more effective immunotherapy strategies for cancer.

Glioma immunotherapy enhancement and CD8-specific sialic acid cleavage by isocitrate dehydrogenase (IDH)-1

The promise of adaptive cancer immunotherapy in treating highly malignant tumors such as glioblastoma multiforme (GBM) can only be realized through expanding its benefits to more patients. Alleviating various modes of immune suppression has so far failed to achieve such expansion, but exploiting endogenous immune enhancers among mutated cancer genes could represent a more direct approach to immunotherapy improvement. We found that Isocitrate Dehydrogenase-1 (IDH1), which is commonly mutated in gliomas, enhances glioma vaccine efficacy in mice and discerns long from short survivors after vaccine therapy in GBM patients. Extracellular IDH1 directly enhanced T cell responses to multiple tumor antigens, and prolonged experimental glioma cell lysis. Moreover, IDH1 specifically bound to and exhibited sialidase activity against CD8. By contrast, mutant IDH1R132H lacked sialidase activity, delayed killing in glioma cells, and decreased host survival after immunotherapy. Overall, our findings identify IDH1 as an immunotherapeutic enhancer that mediates the known T cell-enhancing reaction of CD8 desialylation. This uncovers a new axis for immunotherapeutic improvement in GBM and other cancers, reveals novel physiological and molecular functions of IDH1, and hints at an unexpectedly direct link between lytic T cell function and metabolic activity in target cells.

CD103 Deficiency Promotes Autism (ASD) and Attention-Deficit Hyperactivity Disorder (ADHD) Behavioral Spectra and Reduces Age-Related Cognitive Decline

The incidence of autism spectrum disorders (ASD) and attention deficit hyperactivity disorder (ADHD), which frequently co-occur, are both rising. The causes of ASD and ADHD remain elusive, even as both appear to involve perturbation of the gut-brain-immune axis. CD103 is an integrin and E-cadherin receptor most prominently expressed on CD8 T cells that reside in gut, brain, and other tissues. CD103 deficiency is well-known to impair gut immunity and resident T cell function, but it's impact on neurodevelopmental disorders has not been examined. We show here that CD8 T cells influence neural progenitor cell function, and that CD103 modulates this impact both directly and potentially by controlling CD8 levels in brain. CD103 knockout (CD103KO) mice exhibited a variety of behavioral abnormalities, including superior cognitive performance coupled with repetitive behavior, aversion to novelty and social impairment in females, with hyperactivity with delayed learning in males. Brain protein markers in female and male CD103KOs coincided with known aspects of ASD and ADHD in humans, respectively. Surprisingly, CD103 deficiency also decreased age-related cognitive decline in both sexes, albeit by distinct means. Together, our findings reveal a novel role for CD103 in brain developmental function, and identify it as a unique factor linking ASD and ADHD etiology. Our data also introduce a new animal model of combined ASD and ADHD with associated cognitive benefits, and reveal potential therapeutic targets for these disorders and age-related cognitive decline.

Large-Scale Analysis Reveals the Specific Clinical and Immune Features of DGCR5 in Glioma

Purpose

Long non-coding RNA DGCR5 plays different roles in different types of cancer. The purpose of this study was to investigate the clinicopathological features, potential biological functions and prognostic significance of DGCR5 in glioma in a large-scale study.

Materials and Methods

A total of 697 RNA-seq data from The Cancer Genome Atlas (TCGA) and 301 mRNA microarray data from Chinese Glioma Genome Atlas (CGGA) were enrolled in this study. R language was used as the main tool for statistical analysis and graphical work.

Results

DGCR5 showed a negative correlation with the WHO grade of malignancy in glioma. Specifically, DGCR5 expression was significantly decreased in GBM and IDH wild-type glioma. Gene ontology analysis showed that DGCR5 was predominantly enriched in immune-related biological processes. Additionally, DGCR5 showed a significant correlation with stromal and immune cell populations, inflammatory activities and immune checkpoints. Clinically, patients with low-expression level of DGCR5 exhibited a worse overall survival.

Conclusion

DGCR5 expression is downregulated in glioma, and low DGCR5 independently predicts worse prognosis in glioma patients. Moreover, DGCR5 is significantly associated with immune response and immune infiltration. These findings suggest that DGCR5 is a promising immunotherapy target and a novel prognostic biomarker for glioma.

4-1BB Agonism Combined With PD-L1 Blockade Increases the Number of Tissue-Resident CD8+ T Cells and Facilitates Tumor Abrogation

Although the milestone discovery of immune checkpoint blockade (ICB) has been translated into clinical practice, only a fraction of patients can benefit from it with durable responses and subsequent long-term survival. Here, we tested the anti-tumor effect of combining PD-L1 blockade with 4-1BB costimulation in 3LL and 4T1.2 murine tumor models. Dual treatment induced further tumor regression and enhanced survival in tumor-bearing mice more so than PD-L1 and 4-1BB mAb alone. It was demonstrated that dual anti-PD-L1/anti-4-1BB immunotherapy increased the number of intratumoral CD103+CD8+ T cells and altered their distribution. Phenotypically, CD103+CD8+ T cells expressed a higher level of 4-1BB and PD-1 than their CD103− counterparts. Administration of PD-L1 mAb and 4-1BB mAb further increased the cytolytic capacity of CD103+CD8+ T cells. In vivo, CD103−CD8+ T cells could differentiate into CD103+CD8+ progeny cells. In a human setting, more CD8+ T cells differentiated into CD103+CD8+ T cells in the peripheral tumor region of lung cancer tissues than in the central tumor region. Collectively, infiltrated CD103+CD8+ T cells served as a potential effector T cell population. Combining 4-1BB agonism with PD-L1 blockade could increase tumor-infiltrated CD103+CD8+T cells, thereby facilitating tumor regression.

Pathogen-Boosted Adoptive Cell Transfer Therapy Induces Endogenous Antitumor Immunity through Antigen Spreading

Loss of target antigens in tumor cells has become one of the major hurdles limiting the efficacy of adoptive cell therapy (ACT)-based immunotherapies. The optimal approach to overcome this challenge includes broadening the immune response from the initially targeted tumor-associated antigen (TAA) to other TAAs expressed in the tumor. To induce a more broadly targeted antitumor response, we utilized our previously developed Re-energized ACT (ReACT), which capitalizes on the synergistic effect of pathogen-based immunotherapy and ACT. In this study, we showed that ReACT induced a sufficient endogenous CD8+ T-cell response beyond the initial target to prevent the outgrowth of antigen loss variants in a B16-F10 melanoma model. Sequentially, selective depletion experiments revealed that Batf3-driven cDC1s were essential for the activation of endogenous tumor-specific CD8+ T cells. In ReACT-treated mice that eradicated tumors, we observed that endogenous CD8+ T cells differentiated into memory cells and facilitated the rejection of local and distal tumor rechallenge. By targeting one TAA with ReACT, we provided broader TAA coverage to counter antigen escape and generate a durable memory response against local relapse and metastasis.See related Spotlight on p. 2.

CD8 Binding of MHC-Peptide Complexes in cis or trans Regulates CD8+ T-cell Responses

The coreceptor CD8αβ can greatly promote activation of T cells by strengthening T-cell receptor (TCR) binding to cognate peptide-MHC complexes (pMHC) on antigen presenting cells and by bringing p56^Lck to TCR/CD3. Here, we demonstrate that CD8 can also bind to pMHC on the T cell (in cis) and that this inhibits their activation. Using molecular modeling, fluorescence resonance energy transfer experiments on living cells, biochemical and mutational analysis, we show that CD8 binding to pMHC in cis involves a different docking mode and is regulated by posttranslational modifications including a membrane-distal interchain disulfide bond and negatively charged O-linked glycans near positively charged sequences on the CD8β stalk. These modifications distort the stalk, thus favoring CD8 binding to pMHC in cis. Differential binding of CD8 to pMHC in cis or trans is a means to regulate CD8⁺ T-cell responses and provides new translational opportunities.

Differential expression of N-linked oligosaccharides in methotrexate-resistant primary central nervous system lymphoma cells

Background

Oligosaccharides of glycoprotein, particularly negatively-charged sialylated N-glycans, on the surface of lymphomas play important roles in cell–cell interactions and bind immunoglobulin-like lectins, causing inflammatory responses and bioregulation. However, their characterizations have largely been unknown in central nervous system (CNS) lymphoma.

Methods

Here, we investigated expression patterns of N-linked oligosaccharides of glycoproteins in cells derived from CNS lymphomas and clinical specimens.

Results

We first generated methotrexate (MTX)-resistant cells derived from HKBML and TK as CNS lymphoma, and RAJI as non-CNS lymphoma and determined N-linked oligosaccharide structures in these cells and other non-CNS lymphoma-derived cells including A4/FUK, OYB, and HBL1. Major components of the total oligosaccharides were high-mannose type N-glycans, whose level increased in MTX-resistant HKBML and TK but decreased in MTX-resistant RAJI. We also detected sialylated biantennary galactosylated N-glycans with α1,6-fucosylation, A2G2F, and A2G2FB from HKBML, TK, and RAJI. Sialylated A4G4F was specifically isolated from RAJI. However, the ratios of these sialylated N-glycans slightly decreased against MTX-resistant compared to non-resistant cells. Interestingly, almost all complex-type oligosaccharides were α2,6-sialylated.

Discussion

This is the first study for the expression profile of N-oligosaccharides on MTX-resistant primary CNS lymphoma-derived cells HKBML and TK, and tumor tissues resected from patients with CNS lymphoma,

Conclusion

These results propose a possibility that the differential expression of high-mannose types and sialylated A2G2F, A2G2FB, and A4G4F on the surface of CNS lymphomas may provide a hint for targets for diagnoses and treatments of the oligosaccharide type-specific lymphomas.

Radiation and Immunotherapy in High-grade Gliomas: Where Do We Stand?

High-grade glioma is the most common primary brain tumor, with glioblastoma multiforme (GBM) accounting for 52% of all brain tumors. The current standard of care (SOC) of GBM involves surgery followed by adjuvant fractionated radiotherapy and chemotherapy. However, little progress has been made in extending overall survival, progression-free survival, and quality of life. Attempts to characterize and customize treatment of GBM have led to mitigating the deleterious effects of radiotherapy using hypofractionated radiotherapy, as well as various immunotherapies as a promising strategy for the incurable disease. A combination of radiotherapy and immunotherapy may prove to be even more effective than either alone, and preclinical evidence suggests that hypofractionated radiotherapy can actually prime the immune system to make immunotherapy more effective. This review addresses the complications of the current radiotherapy regimen, various methods of immunotherapy, and preclinical and clinical data from combined radioimmunotherapy trials.

Desialylation in physiological and pathological processes: New target for diagnostic and therapeutic development

Desialylation is a pivotal part of sialic acid metabolism, which initiates the catabolism of glycans by removing the terminal sialic acid residues on glycans, thereby modulating the structure and functions of glycans, glycoproteins, or glycolipids. The functions of sialic acids have been well recognized, whereas the function of desialylation process is underappreciated or largely ignored. However, accumulating evidence demonstrates that desialylation plays an important role in a variety of physiological and pathological processes. This chapter summarizes the current knowledge pertaining to desialylation in a variety of physiological and pathological processes, with a focus on the underlying molecular mechanisms. The potential of targeting desialylation process for diagnostic and therapeutic development is also discussed.

Resident memory T cells, critical components in tumor immunology

CD8⁺ T lymphocytes are the major anti-tumor effector cells. Most cancer immunotherapeutic approaches seek to amplify cytotoxic T lymphocytes (CTL) specific to malignant cells. A recently identified subpopulation of memory CD8⁺ T cells, named tissue-resident memory T (T_RM) cells, persists in peripheral tissues and does not recirculate. This T-cell subset is considered an independent memory T-cell lineage with a specific profile of transcription factors, including Runx3⁺, Notch⁺, Hobit⁺, Blimp1⁺, BATF⁺, AHR⁺, EOMES^neg and Tbet^low. It is defined by expression of CD103 (α_E(CD103)β₇) and CD49a (VLA-1 or α₁β₁) integrins and C-type lectin CD69, which are most likely involved in retention of T_RM cells in non-lymphoid tissues, including solid tumors. CD103 binds to the epithelial cell marker E-cadherin, thereby favoring the location and retention of T_RM in epithelial tumor regions in close contact with malignant cells. The CD103-E-cadherin interaction is required for polarized exocytosis of lytic granules, in particular, when ICAM-1 expression on cancer cells is missing, leading to target cell death. T_RM cells also express high levels of granzyme B, IFNγ and TNFα, supporting their cytotoxic features. Moreover, the local route of immunization targeting tissue dendritic cells (DC), and the presence of environmental factors (i.e. TGF-β, IL-33 and IL-15), promote differentiation of this T-cell subtype. In both spontaneous tumor models and engrafted tumors, natural T_RM cells or cancer-vaccine-induced T_RM directly control tumor growth. In line with these results, T_RM infiltration into various human cancers, including lung cancer, are correlated with better clinical outcome in both univariate and multivariate analyses independently of CD8⁺ T cells. T_RM cells also predominantly express checkpoint receptors such as PD-1, CTLA-4 and Tim-3. Blockade of PD-1 with neutralizing antibodies on T_RM cells isolated from human lung cancer promotes cytolytic activity toward autologous tumor cells. Thus, T_RM cells appear to represent important components in tumor immune surveillance. Their induction by cancer vaccines or other immunotherapeutic approaches may be critical for the success of these treatments. Several arguments, such as their close contact with tumor cells, dominant expression of checkpoint receptors and their recognition of cancer cells, strongly suggest that they may be involved in the success of immune checkpoint inhibitors in various cancers.

Tissue-resident memory T cells at the center of immunity to solid tumors

Immune responses in tissues are constrained by the physiological properties of the tissue involved. Tissue-resident memory T cells (T_RM cells) are a recently discovered lineage of T cells specialized for life and function within tissues. Emerging evidence has shown that T_RM cells have a special role in the control of solid tumors. A high frequency of T_RM cells in tumors correlates with favorable disease progression in patients with cancer, and studies of mice have shown that T_RM cells are necessary for optimal immunological control of solid tumors. Here we describe what defines T_RM cells as a separate lineage and how these cells are generated. Furthermore, we discuss the properties that allow T_RM cells to operate in normal and transformed tissues, as well as implications for the treatment of patients with cancer.

Sialic acid removal from dendritic cells improves antigen cross-presentation and boosts anti-tumor immune responses

Dendritic cells (DCs) hold promise for anti-cancer immunotherapy. However, clinically, their efficiency is limited and novel strategies to improve DC-mediated anti-tumor responses are needed. Human DCs display high content of sialic acids, which inhibits their maturation and co-stimulation capacity. Here, we aimed to understand whether exogenous desialylation of DCs improves their anti-tumor immunity. Compared to fully sialylated DCs, desialylated human DCs loaded with tumor-antigens showed enhanced ability to induce autologous T cells to proliferate, to secrete Th1 cytokines, and to specifically induce tumor cell apoptosis. Desialylated DCs showed an increased expression of MHC-I and -II, co-stimulatory molecules and an augmented secretion of IL-12. Desialylated HLA-A*02:01 DCs pulsed with gp100 peptides displayed enhanced peptide presentation through MHC-I, resulting in higher activation ofgp100_280–288 specific CD8⁺ cytotoxic T cells. Desialylated murine DCs also exhibited increased MHC and co-stimulatory molecules and higher antigen cross-presentation via MHC-I. These DCs showed higher ability to activate antigen-specific CD4⁺ and CD8⁺ T cells, and to specifically induce tumor cell apoptosis. Collectively, our data demonstrates that desialylation improves DCs' ability to elicit T cell-mediated anti-tumor activity, due to increased MHC-I expression and higher antigen presentation via MHC-I. Sialidase treatment of DCs may represent a technology to improve the efficacy of antigen loaded-DC-based vaccines for anti-cancer immunotherapy.

How immunotherapies are targeting the glioblastoma immune environment

The diagnosis of glioblastoma remains one of the most dismal in medical practice, with current standard care only providing a median survival of 14.6 months. The need for new therapies is desperately clear. Components of the tumour microenvironment are demonstrating growing importance in the field, given they allow the tumour to utilise pathways involved in autoimmune prevention, something that enables the tumour's establishment and growth. As with many different cancers, the search for a new standard has progressed to the design of immunotherapies, which aim to counteract the immune changes within this microenvironment. Serotherapy, adoptive lymphocyte transfer, peptide and dendritic cell vaccines and a range of other methods are currently under investigation, while intracranial infection has also been researched for its capacity to reverse glioblastoma mediated immunosuppression. Some of these new therapies have shown promise, but it is a long road ahead before their incorporation into glioblastoma standard therapy.

Prognostic implications of intratumoral CD103+ tumor-infiltrating lymphocytes in pulmonary squamous cell carcinoma

CD103 is the α_E subunit of α_Eβ₇ integrin that is expressed in tissue-resident memory T cells, where it promotes cytotoxic T cell responses against tumors. However, little is known about its expression or clinicopathological implications in non-small cell lung cancer (NSCLC). This study investigated the prognostic implications of CD103⁺ tumor-infiltrating lymphocytes (TILs) in NSCLC. We established two cohorts: patients with resected NSCLC (n = 132) and patients with pulmonary squamous cell carcinoma (pSCC), a subset of NSCLC (n = 378), to estimate the prognostic significance of CD103⁺ TILs. The numbers of CD103⁺ TILs in the intratumoral (i.e., intraepithelial) and stromal regions of NSCLC were estimated using immunohistochemistry and automated image analysis. In the NSCLC cohort, high numbers of intratumoral CD103⁺ TILs were significantly associated with prolonged disease-free survival (DFS) and overall survival (OS) in patients with pSCC but not in those with pulmonary adenocarcinoma. In the pSCC cohort, a positive correlation was observed between the numbers of intratumoral CD103⁺ and CD8⁺ TILs (correlation coefficient = 0.736, P < 0.001). The ratio of intratumoral/stromal CD103⁺ TILs was higher in pSCC with high compared to low E-cadherin expression (P = 0.021). According to Kaplan-Meier analysis, high intratumoral but not stromal CD103⁺ TILs were associated with prolonged DFS and OS in patients with resected pSCC (P = 0.021 and 0.002, respectively). Multivariate analysis revealed that a high number of intratumoral CD103⁺ TILs is an independent predictor of a more favorable DFS (P = 0.021). Thus, a high number of intratumoral CD103⁺ TILs is a favorable prognostic indicator in patients with pSCC.

Tumoricidal efficacy coincides with CD11c up-regulation in antigen-specific CD8(+) T cells during vaccine immunotherapy

Background

Dendritic cells (DCs) mount tumor-associated antigens (TAAs), and the double-stranded RNA adjuvant Poly(I:C) stimulates Toll-like receptor 3 (TLR3) signal in DC, which in turn induces type I interferon (IFN) and interleukin-12 (IL-12), then cross-primes cytotoxic T lymphocytes (CTLs). Proliferation of CTLs correlates with tumor regression. How these potent cells expand with high quality is crucial to the outcome of CTL therapy. However, good markers reflecting the efficacy of DC-target immunotherapy have not been addressed.

Methods

Using an EG7 (ovalbumin, OVA-positive) tumor-implant mouse model, we examined what is a good marker for active CTL induction in treatment with Poly(I:C)/OVA.

Results

Simultaneous administration of Poly(I:C) and antigen (Ag) OVA significantly increased a minor population of CD8⁺ T cells, that express CD11c in lymphoid and tumor sites. The numbers of the CD11c⁺ CD8⁺ T cells correlated with those of induced Ag-specific CD8⁺ T cells and tumor regression. The CD11c⁺ CD8⁺ T cell moiety was characterized by its high killing activity and IFN-γ-producing ability, which represent an active phenotype of the effector CTLs. Not only a TLR3-specific (TICAM-1-dependent) signal but also TLR2 (MyD88) signal in DC triggered the expansion of CD11c⁺ CD8⁺ T cells in tumor-bearing mice. Notably, human CD11c⁺ CD8⁺ T cells also proliferated in peripheral blood mononuclear cells (PBMC) stimulated with cytomegalovirus (CMV) Ag.

Conclusions

CD11c expression in CD8⁺ T cells reflects anti-tumor CTL activity and would be a marker for immunotherapeutic efficacy in mouse models and probably cancer patients as well.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-016-0416-x) contains supplementary material, which is available to authorized users.

Tumor antigen-specific T cells for immune monitoring of dendritic cell-treated glioblastoma patients

BACKGROUND AIMS

CD8(+) T cells are part of the adaptive immune system and, as such, are responsible for the elimination of tumor cells. Dendritic cells (DC) are professional antigen-presenting cells (APC) that activate CD8(+) T cells. Effector CD8(+) T cells in turn mediate the active immunotherapeutic response of DC vaccination against the aggressive glioblastoma (GBM). The lack of tumor response assays complicates the assessment of treatment success in GBM patients.

METHODS

A novel assay to identify specific cytotoxicity of activated T cells by APC was evaluated. Tumor antigen-pulsed DCs from HLA-A*02-positive GBM patients were cultivated to stimulate autologous cytotoxic T lymphocytes (CTL) over a 12-day culture period. To directly correlate antigen specificity and cytotoxic capacity, intracellular interferon (IFN)-γ fluorescence flow cytometry-based measurements were combined with anti-GBM tumor peptide dextramer staining. IFN-γ response was quantified by real-time polymerase chain reaction (PCR), and selected GBM genes were compared with healthy human brain cDNA by single specific primer PCR characterization.

RESULTS

Using CTL of GBM patients stimulated with GBM lysate-pulsed DCs increased IFN-γ messenger RNA levels, and intracellular IFN-γ protein expression was positively correlated with specificity against GBM antigens. Moreover, the GBM peptide-specific CD8(+) T-cell response correlated with specific GBM gene expression. Following DC vaccination, GBM patients showed 10-fold higher tumor-specific signals compared with unvaccinated GBM patients.

DISCUSSION

These data indicate that GBM tumor peptide-dextramer staining of CTL in combination with intracellular IFN-γ staining may be a useful tool to acquire information on whether a specific tumor antigen has the potential to induce an immune response in vivo.

Dendritic cell immunotherapy for brain tumors

Glioblastomas are characterized by immunosuppression, rapid proliferation, angiogenesis, and invasion into the surrounding brain parenchyma. Limitations in current therapeutic approaches have spurred the development of personalized, patient-specific treatments. Among these, active immunotherapy has emerged as a viable option for glioma treatment. The ability to generate an immune response utilizing patient-derived dendritic cells (DCs) (professional antigen-presenting cells) is especially attractive. This approach to glioma treatment allows for the immunologic targeting and destruction of malignant cells. Data acquired in multiple pre-clinical models and clinical trials have shown significant responses and prolonged survival. Here we provide an overview of the current status of DC vaccination for the treatment of gliomas.

Anti-CD40-induced inflammatory E-cadherin+ dendritic cells enhance T cell responses and antitumour immunity in murine Lewis lung carcinoma

Background

Agonistic CD40 antibodies have been demonstrated to activate antigen-presenting cells (APCs) and enhance antitumour T cell responses, thereby providing a new therapeutic option in cancer immunotherapy. In agonistic CD40 antibody-mediated inflammatory responses, a novel subset of E-cadherin + dendritic cells (DCs) has been identified, and little is known about the role of these DCs in tumour immunity. This study investigated the effect of anti-CD40-mediated inflammatory E-cadherin + DCs in murine Lewis lung carcinoma (LLC).

Methods

The phenotype and characteristics of anti-CD40-mediated inflammatory E-cadherin + DCs isolated from the anti-CD40 model were assessed in vitro. The antitumour activity of E-cadherin + DCs were evaluated in vivo by promoting the differentiation of effector CD4+ T cells, CEA-specific CD8+ T cells and CD103+ CD8+ T cells and assessing their resistance to tumour challenge, including variations in tumour volume and survival curves.

Results

Here, we demonstrated that anti-CD40-mediated E-cadherin + inflammatory DCs accumulate in the lungs of Rag1 KO mice and were able to stimulate naïve CD4+ T cells to induce Th1 and Th17 cell differentiation and polarisation and to inhibit regulatory T cell and Th2 responses. Importantly, with the adoptive transfer of E-cadherin + DCs into the Lewis lung cancer model, the inflammatory DCs increased the Th1 and Th17 cell responses and reduced the Treg cell and Th2 responses. Interestingly, following the injection of inflammatory E-cadherin + DCs, the CD103+ CD8+ T cell and CEA-specific CD8+ T cell responses increased and exhibited potent antitumour immunity.

Conclusions

These findings indicate that anti-CD40-induced E-cadherin + DCs enhance T cell responses and antitumour activity in non-small cell lung cancer (NSCLC)-bearing mice and may be used to enhance the efficacy of DC-based peptide vaccines against NSCLC.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-015-0126-9) contains supplementary material, which is available to authorized users.

Overview of current immunotherapeutic strategies for glioma

In the last decade, numerous studies of immunotherapy for malignant glioma (glioblastoma multiforme) have brought new knowledge and new hope for improving the prognosis of this incurable disease. Some clinical trials have reached Phase III, following positive outcomes in Phase I and II, with respect to safety and immunological end points. Results are encouraging especially when considering the promise of sustained efficacy by inducing antitumor immunological memory. Progress in understanding the mechanisms of tumor-induced immune suppression led to the development of drugs targeting immunosuppressive checkpoints, which are used in active clinical trials for glioblastoma multiforme. Insights related to the heterogeneity of the disease bring new challenges for the management of glioma and underscore a likely cause of therapeutic failure. An emerging therapeutic strategy is represented by a combinatorial, personalized approach, including the standard of care: surgery, radiation, chemotherapy with added active immunotherapy and multiagent targeting of immunosuppressive checkpoints.