Forced LIGHT expression in prostate tumors overcomes Treg mediated immunosuppression and synergizes with a prostate tumor therapeutic vaccine by recruiting effector T lymphocytes

Harnessing the power of oncolytic virotherapy and tertiary lymphoid structures to amplify antitumor immune responses in cancer patients

Tertiary lymphoid structures (TLS) are ectopic aggregates of immune cells that develop in non-lymphoid tissues under persistent inflammation. Since their presence has been associated with a better prognosis in cancer patients, modulating TLS formation is being part of new challenges in immunotherapy. Although mechanisms underlying TLS genesis are still not fully understood, different strategies have been developed in preclinical models to induce their formation and ultimately enhance antitumor responses. Herein, we will discuss a new approach that would consist in using oncolytic viruses (OV). These viruses have the unique feature to preferentially infect, replicate in and kill cancer cells. Their immunoadjuvant property, their use as a vector of therapeutic molecules and their selectivity for cancer cells, make them an attractive strategy to induce TLS in the tumor microenvironment. This review will examine the current knowledge about TLS neogenesis, approaches for inducing them, and relevance of using OV for this purpose, especially in combination with immunotherapy such as immune checkpoint blockade.

Comprehensive characterization of TNFSF14/LIGHT with implications in prognosis and immunotherapy of human gliomas

Glioblastoma multiforme (GBM) is a common central neural system malignant tumor among adults. Alongside its microscopic spread, immunosuppression in the tumor microenvironment also induces its refractoriness, which makes immunotherapy for GBM particularly important. Unfortunately, traditional immune checkpoint inhibitors (ICIs) often show limited therapeutic effects in GBM clinical trials, and new therapeutic strategies or targets are urgently needed. TNFSF14/LIGHT is a novel immune checkpoint molecule that plays essential roles in both innate and acquired immunity. Despite recent advances in our understanding of the function of TNFSF14/LIGHT in a variety of cancer types, the clinical and immunological importance of TNFSF14/LIGHT in human gliomas has not been fully explained. Here, we employed a comprehensive in silico analysis with publicly available data to analyze the molecular and immune characteristics of TNFSF14/LIGHT to explore its feasibility as an immunotherapy target. Totally, 2215 glioma cases were enrolled in the current study. Immunohistochemistry staining based on patient tissues (n = 34) was performed for the validation. TNFSF14/LIGHT was expressed higher in higher-WHO-grade gliomas and mesenchymal subtypes, and it was sensitive as a prognostic marker in GBM and low-grade glioma (LGG). A nomogram prognostic model was established based on TNFSF14/LIGHT expression together with other risk factors. Additionally, Gene Ontology and pathway analysis revealed that TNFSF14/LIGHT participated in T-cell activities and inflammatory processes. Moreover, analysis based on the structure and interactions of TNFSF14/LIGHT revealed its mutation sites in tumors as well as crucial interacting proteins. Analysis of IMvigor210 indicated the role of TNFSF14/LIGHT in immunotherapy. Altogether, our results reveal an underlying role of TNFSF14/LIGHT as an immunotherapy target in GBM.

Prostate Cancer Survivors Present Long-Term, Residual Systemic Immune Alterations

Simple Summary

The development of cancer is very often accompanied by systemic immune alterations which can be further aggravated by major anti-cancer therapies. However, there is very little known about how long these alterations persist in patients successfully cured of cancer. The aim of our work was to investigate how cancer and radiotherapy as major anti-cancer treatment modalities impact the immune system long after the successful treatment of a tumor. We investigated prostate cancer patients treated with a special form of radiotherapy (low-dose rate brachytherapy) often used for the treatment of prostate cancer and followed a wide range of immune parameters at regular intervals up to 3 years after the start of the treatment. Our results showed that some immune alterations did not recover after the treatment of the disease, on the contrary, they persisted, and in some cases got even worse. Further studies are needed to explain the causes and the potential long-term consequences of these alterations.

Abstract

Background: The development of cancer and anti-tumor therapies can lead to systemic immune alterations but little is known about how long immune dysfunction persists in cancer survivors. Methods: We followed changes in the cellular immune parameters of prostate cancer patients with good prognostic criteria treated with low dose rate brachytherapy before and up to 3 years after the initiation of therapy. Results: Patients before therapy had a reduced CD4+ T cell pool and increased regulatory T cell fraction and these alterations persisted or got amplified during the 36-month follow-up. A significant decrease in the total NK cell number and a redistribution of the circulating NK cells in favor of a less functional anergic subpopulation was seen in patients before therapy but tumor regression led to the regeneration of the NK cell pool and functional integrity. The fraction of lymphoid DCs was increased in patients both before therapy and throughout the whole follow-up. Increased PDGF-AA, BB, CCL5 and CXCL5 levels were measured in patients before treatment but protein levels rapidly normalized. Conclusions: while NK cell dysfunction recovered, long-term, residual alterations persisted in the adaptive and partly in the innate immune system.

Current strategies in engaging oncolytic viruses with antitumor immunity

Oncolytic virotherapy has produced promising yet limited results in preclinical and clinical studies. Besides direct oncolytic activity, a significant therapeutic mechanism of oncolytic virotherapy is the induction of tumor-specific immunity. Consequently, the efficacy of oncolytic viruses can be improved by the insertion of immune stimulator genes and rational combinatorial therapy with other immunotherapies. This article reviews recent efforts on arming oncolytic viruses with a variety of immune stimulator molecules, immune cell engagers, and other immune potentiating molecules. We outline what is known about the mechanisms of action and the corresponding results. The review also discusses recent preclinical and clinical studies of combining oncolytic virotherapy with immune-checkpoint inhibitors and the role of oncolytic virotherapy in changing the tumor microenvironment.

Molecular and Clinical Characterization of LIGHT/TNFSF14 Expression at Transcriptional Level via 998 Samples With Brain Glioma

LIGHT, also termed TNFSF14, has been reported to play a vital role in different tumors. However, its role in glioma remains unknown. This study is aimed at unveiling the characterization of the transcriptional expression profiling of LIGHT in glioma. We selected 301 glioma patients with mRNA microarray data from the CGGA dataset and 697 glioma patients with RNAseq data from the TCGA dataset. Transcriptome data and clinical data of 998 samples were analyzed. Statistical analyses and figure generation were performed with R language. LIGHT expression showed a positive correlation with WHO grade of glioma. LIGHT was significantly increased in mesenchymal molecular subtype. Gene Ontology analysis demonstrated that LIGHT was profoundly involved in immune response. Moreover, LIGHT was found to be synergistic with various immune checkpoint members, especially HVEM, PD1/PD-L1 pathway, TIM3, and B7-H3. To get further understanding of LIGHT-related immune response, we put LIGHT together with seven immune signatures into GSVA and found that LIGHT was particularly correlated with HCK, LCK, and MHC-II in both datasets, suggesting a robust correlation between LIGHT and activities of macrophages, T-cells, and antigen-presenting cells (APCs). Finally, higher LIGHT indicated significantly shorter survival for glioma patients. Cox regression models revealed that LIGHT expression was an independent variable for predicting survival. In conclusion, LIGHT was upregulated in more malignant gliomas including glioblastoma, IDH wildtype, and mesenchymal subtype. LIGHT was mainly involved in the immune function of macrophages, T cells, and APCs and served as an independent prognosticator in glioma.

Oncolytic adenovirus encoding LIGHT (TNFSF14) inhibits tumor growth via activating anti-tumor immune responses in 4T1 mouse mammary tumor model in immune competent syngeneic mice

LIGHT, also known as tumor-necrosis factor (TNF) superfamily member 14 (TNFSF14), is predominantly expressed on activated immune cells and some tumor cells. LIGHT is a pivotal regulator both for recruiting and activating immune cells in the tumor lesions. In this study, we armed human telomerase reverse transcriptase (TERT) promoter controlled oncolytic adenovirus with LIGHT to generate rAd.Light. rAd.Light effectively transduced both human and mouse breast tumor cell lines in vitro, and expressed LIGHT protein on the surface of tumor cells. Both rAd.Null, and rAd.Light could replicate in human breast cancer cells, and produced cytotoxicity to human and mouse mammary tumor cells. rAd.Light induced apoptosis resulting in tumor cell death. Using a subcutaneous model of 4T1 cells in BALB/c mice, rAd.Light was delivered intratumorally to evaluate the anti-tumor responses. Both rAd.Light and rAd.Null significantly inhibited the tumor growth, but rAd.Light produced much stronger anti-tumor effects. Histopathological analysis showed the infiltration of T lymphocytes in the tumor tissues. rAd.Light also induced stronger cellular apoptosis than rAd.Null in the tumors. Interestingly, on day 15, compared to rAd.Null, there was a significant reduction of Tregs following rAd.Light treatment. rAd.Light significantly increased Th1 cytokine interleukin (IL)-2 expression, and reduced Th2 cytokines expression, such as transforming growth factor β (TGF-β) and IL-10 in the tumors. These results suggest rAd.Light induced activation of anti-tumor immune responses. In conclusion, rAd.Light produced anti-tumor effect in a subcutaneous model of breast cancer via inducing tumor apoptosis and evoking strong anti-tumor immune responses. Therefore, rAd.Light has great promise to be developed as an effective therapeutic approach for the treatment of breast cancer.

The impact of TNFSF14 on prognosis and immune microenvironment in clear cell renal cell carcinoma

BACKGROUND

TNFSF14 has been proven to play an important role in various types of tumors. However, its function in renal cell carcinoma (RCC) has not yet been fully elucidated.

OBJECTIVE

In order to explore molecular mechanism of RCC, we evaluated the effect of TNFSF14 on RCC progression, prognosis and immune microenvironment.

METHODS

Using TCGA database, the differential expression of TNFSF14 and its relationships between clinicopathological features and prognosis were determined. Cox univariate and multivariate analyses were successively performed to identify whether TNFSF14 was an independent prognostic factor. The discriminating ability of TNFSF14 in RCC prognosis analysis was validated under the same clinical subgroups. Tumor mutational burden (TMB) of each RCC samples was calculated and the differential expression of TNFSF14 between high- and low-TMB groups was analyzed. The immune abundances of 22 leukocyte subtypes in each RCC samples were presented through the CIBERSORT algorithm. TIMER database was used to explore the relationships between copy number of TNFSF14 and the infiltration levels of 6 immune cells.

RESULTS

Overexpression of TNFSF14 implied adverse clinicopathological features and poor prognosis. Meanwhile, TNFSF14 was identified as an independent prognostic factor (HR = 1.047, P = 0.028) and possessed prevalent applicability in RCC prognostic analysis. TNFSF14 was upregulated in high-TMB group than that in low-TMB group (Log₂FC = 0.722). Moreover, overexpression of TNFSF14 brought alteration of immune abundance of 8 leukocyte subtypes. Besides, somatic copy number alteration (SCNA) of TNFSF14 was associated with infiltration levels of 6 immune cells.

CONCLUSIONS

TNFSF14 has crucial impact on progression, prognosis and immune microenvironment in RCC. Besides, TNFSF14 may be a potential biomarker for predicting the efficacy and response rate of RCC immunotherapy.

TNFSF14: LIGHTing the Way for Effective Cancer Immunotherapy

Tumor necrosis factor superfamily member 14 (LIGHT) has been in pre-clinical development for over a decade and shows promise as a modality of enhancing treatment approaches in the field of cancer immunotherapy. To date, LIGHT has been used to combat cancer in multiple tumor models where it can be combined with other immunotherapy modalities to clear established solid tumors as well as treat metastatic events. When LIGHT molecules are delivered to or expressed within tumors they cause significant changes in the tumor microenvironment that are primarily driven through vascular normalization and generation of tertiary lymphoid structures. These changes can synergize with methods that induce or support anti-tumor immune responses, such as checkpoint inhibitors and/or tumor vaccines, to greatly improve immunotherapeutic strategies against cancer. While investigators have utilized multiple vectors to LIGHT-up tumor tissues, there are still improvements needed and components to be found within a human tumor microenvironment that may impede translational efforts. This review addresses the current state of this field.

Dual-mechanism based CTLs infiltration enhancement initiated by Nano-sapper potentiates immunotherapy against immune-excluded tumors

The failure of immunotherapies in immune-excluded tumor (IET) is largely ascribed to the void of intratumoral cytotoxic T cells (CTLs). The major obstacles are the excessive stroma, defective vasculatures and the deficiency of signals recruiting CTLs. Here we report a dual-mechanism based CTLs infiltration enhancer, Nano-sapper, which can simultaneously reduce the physical obstacles in tumor microenvironment and recruiting CTLs to potentiate immunotherapy in IET. Nano-sapper consists a core that co-loaded with antifibrotic phosphates-modified α-mangostin and plasmid encoding immune-enhanced cytokine LIGHT. Through reversing the abnormal activated fibroblasts, decreasing collagen deposition, normalizing the intratumoral vasculatures, and in situ stimulating the lymphocyte-recruiting chemoattractants expression, Nano-sapper paves the road for the CTLs infiltration, induces the intratumoral tertiary lymphoid structures, thus reshapes tumor microenvironment and potentiates checkpoint inhibitor against IET. This study demonstrates that the combination of antifibrotic agent and immune-enhanced cytokine might represent a modality in promoting immunotherapy against IET.

The exclusion of cytotoxic T cells remains an important barrier to the efficacy of immunotherapies. Here the authors demonstrate that the combination anti-fibrosis agents and immune-enhanced cytokines can enhance T cell infiltration in a mouse model of pancreatic cancer.

HVEM network signaling in cancer

Somatic mutations in cancer cells may influence tumor growth, survival, or immune interactions in their microenvironment. The tumor necrosis factor receptor family member HVEM (TNFRSF14) is frequently mutated in cancers and has been attributed a tumor suppressive role in some cancer contexts. HVEM functions both as a ligand for the lymphocyte checkpoint proteins BTLA and CD160, and as a receptor that activates NF-κB signaling pathways in response to BTLA and CD160 and the TNF ligands LIGHT and LTα. BTLA functions to inhibit lymphocyte activation, but has also been ascribed a role in stimulating cell survival. CD160 functions to co-stimulate lymphocyte function, but has also been shown to activate inhibitory signaling in CD4⁺ T cells. Thus, the role of HVEM within diverse cancers and in regulating the immune responses to these tumors is likely context specific. Additionally, development of therapeutics that target proteins within this network of interacting proteins will require a deeper understanding of how these proteins function in a cancer-specific manner. However, the prominent role of the HVEM network in anti-cancer immune responses indicates a promising area for drug development.

Armed oncolytic viruses: A kick-start for anti-tumor immunity

Oncolytic viruses (OVs), viruses that specifically result in killing tumor cells, represent a promising class of cancer therapy. Recently, the focus in the OV therapy field has shifted from their direct oncolytic effect to their immune stimulatory effect. OV therapy can function as a "kick start" for the antitumor immune response by releasing tumor associated antigens and release of inflammatory signals. Combining OVs with immune modulators could enhance the efficacy of both immune and OV therapies. Additionally, genetic engineering of OVs allows local expression of immune therapeutics, thereby reducing related toxicities. Different options to modify the tumor microenvironment in combination with OV therapy have been explored. The possibilities and obstacles of these combinations will be discussed in this review.

Lymphotoxin signalling in tertiary lymphoid structures and immunotherapy

Tertiary lymphoid structures (TLS) often develop at sites of persistent inflammation, including cancers and autoimmune diseases. In most cases, the presence of TLS correlates with active immune responses. Because of their proximity to pathological loci, TLS are an intriguing target for the manipulation of immune responses. For several years, it has become clear that lymphotoxin (LT) signalling plays critical roles in lymphoid tissue organogenesis and maintenance. In the current review, we will discuss the role of LT signalling in the development of TLS. With a focus on cancers and autoimmune diseases, we will highlight the correlations between TLS and disease progression. We will also discuss the current efforts and potential directions for manipulating TLS for immunotherapies.

A Unique Cellular and Molecular Microenvironment Is Present in Tertiary Lymphoid Organs of Patients with Spontaneous Prostate Cancer Regression

Objective

Multiple solid cancers contain tertiary lymphoid organs (TLO). However, it is unclear whether they promote tumor rejection, facilitate tumor evasion, or simply whether they are a byproduct of chronic inflammation. We hypothesize that although chronic inflammation induces TLO formation, the tumor milieu can modulate TLO organization and functions in prostate cancer. Therefore, our study seeks to elucidate the cellular and molecular signatures in unique prostatectomy specimens from evanescent carcinoma patients to identify markers of cancer regression, which could be harnessed to modulate local immunosuppression or potentially enhance TLO function.

Methods

We used multicolor immunofluorescence to stain prostate tissues, collected at different stages of cancer progression (prostatic intraepithelial neoplasia, intermediate and advanced cancer) or from patients with evanescent prostate carcinoma. Tissues were stained with antibodies specific for pro-inflammatory molecules (cyclooxygenase 2, CXCL10, IL17), tumor-infiltrating immune cells (mature DC-LAMP⁺ dendritic cells, CD3⁺ T cells, CD3⁺Foxp3⁺ regulatory T cells (Treg), T bet⁺ Th1 cells, granzyme B⁺ cytotoxic cells), and stromal cell populations (lymphatic vessels, tumor neovessels, high endothelial venules (HEV), stromal cells), which promote prostate tumor growth or are critical components of tumor-associated TLO.

Results

Generally, inflammatory cells are located at the margins of tumors. Unexpectedly, we found TLO within prostate tumors from patients at different stages of cancer and in unique samples from patients with spontaneous cancer remission. In evanescent prostate carcinomas, accumulation of Treg was compromised, while Tbet⁺ T cells and CD8 T cells were abundant in tumor-associated TLO. In addition, we found a global decrease in tumor neovascularization and the coverage by cells positive for cyclooxygenase 2 (COX2). Finally, consistent with tumor regression, prostate stem cell antigen was considerably reduced in TLO and tumor areas from evanescent carcinoma patients.

Conclusion

Collectively, our results suggest that COX2 and Treg are attractive therapeutic targets that can be harnessed to enhance TLO-driven tumor immunity against prostate cancer. Specially, the presence of HEV and lymphatics indicate that TLO can be used as a platform for delivery of cell-based and/or COX2 blocking therapies to improve control of tumor growth in prostate cancer.

Therapeutic Lymphoid Organogenesis in the Tumor Microenvironment

The inflammatory status of the tumor microenvironment (TME) has been heavily investigated in recent years. Chemokine- and cytokine-signaling pathways such as CCR7, CXCR5, lymphotoxin, and IL-36, which are involved in the generation of secondary lymphoid organs and effector immune responses, are now recognized as having value both as prognostic factors and as immunomodulatory therapeutics in the context of cancer. Furthermore, when produced in the TME, these mediators have been shown to promote the recruitment of immune cells, including T cells, B cells, dendritic cells (DCs), and other specialized immune cell subsets such as follicular DCs and T follicular helper cells, in association with the formation of "tertiary" lymphoid structures (TLSs) within or adjacent to sites of disease. Although TLSs are composed of a heterogeneous collection of immune cell types, whose composition differs based on cancer subtype, the qualitative presence of TLSs has been shown to represent a biomarker of good prognosis for cancer patients. A comprehensive understanding of the role each of these pathways plays within the TME may support the rational design of future immunotherapies to selectively promote/bolster TLS formation and function, leading to improved clinical outcomes across the vast range of solid cancer types.

The effect of ionizing radiation on regulatory T cells in health and disease

Treg cells are key elements of the immune system which are responsible for the immune suppressive phenotype of cancer patients. Interaction of Treg cells with conventional anticancer therapies might fundamentally influence cancer therapy response rates. Radiotherapy, apart from its direct tumor cell killing potential, has a contradictory effect on the antitumor immune response: it augments certain immune parameters, while it depresses others. Treg cells are intrinsically radioresistant due to reduced apoptosis and increased proliferation, which leads to their systemic and/or intratumoral enrichment. While physiologically Treg suppression is not enhanced by irradiation, this is not the case in a tumorous environment, where Tregs acquire a highly suppressive phenotype, which is further increased by radiotherapy. This is the reason why the interest for combined radiotherapy and immunotherapy approaches focusing on the abrogation of Treg suppression has increased in cancer therapy in the last few years. Here we summarize the basic mechanisms of Treg radiation response both in healthy and cancerous environments and discuss Treg-targeted pre-clinical and clinical immunotherapy approaches used in combination with radiotherapy. Finally, the discrepant findings regarding the predictive value of Tregs in therapy response are also reviewed.