Molecular profiling of tumor-specific TH1 cells activated in vivo

Identification of tumor-specific T cell signature predicting cancer immunotherapy response in bladder cancer by multi-omics analysis and experimental verification

BACKGROUND

Numerous gene signatures predicting the prognosis of bladder cancer have been identified. However, a tumor-specific T cell signature related to immunotherapy response in bladder cancer remains under investigation.

METHODS

Single-cell RNA and TCR sequencing from the Gene expression omnibus (GEO) database were used to identify tumor-specific T cell-related genes in bladder cancer. Subsequently, we constructed a tumor-specific T cell signature (TstcSig) and validated its clinical relevance for predicting immunotherapy response in multiple immunotherapy cohorts. Further analyses explored the immune characteristics of TstcSig in bladder cancer patients from other cohorts in the TCGA and GEO databases. Western blot (WB), multicolor immunofluorescence (MIF), qRT-PCR and flow cytometry assays were performed to validate the results of bioinformatics analysis.

RESULTS

The established TstcSig, based on five tumor-specific T cell-related genes, could predict outcomes in a bladder cancer immunotherapy cohort. This was verified using two additional immunotherapy cohorts and showed better predictive performance compared to 109 published T cell signatures. TstcSig was strongly correlated with immune characteristics such as immune checkpoint gene expression, tumor mutation burden, and T cell infiltration, as validated by single-cell and spatial transcriptomics datasets. Notably, the positive correlation between TstcSig and T cell infiltration was confirmed in the TCGA cohort. Furthermore, pan-cancer analysis demonstrated the heterogeneity of the prognostic value of TstcSig. Tumor-specific T cells highly expressed CD27, IFNG, GZMB and CXCL13 and secreted more effector cytokines for tumor cell killing, as validated experimentally.

CONCLUSION

We developed a five-gene signature (including VAMP5, TIGIT, LCK, CD27 and CACYBP) based on tumor-specific T cell-related genes to predict the immunotherapy response in bladder cancer patients.

Expression and function of CD51 on CD8 T cells as an immunomodulatory target

T cell responses are regulated by co-stimulatory and inhibitory receptors along with T cell receptor- and cytokine-mediated signals. CD51 is a transmembrane glycoprotein of the integrin family that plays a role in cell adhesion, migration, tumorigenesis, and other cellular functions. In this study, we aimed to investigate the expression and function of CD51 on CD8 T cells. Upon in vitro T cell activation, CD51 expression was delayed but subsequently was upregulated in CD8 T cells upon cell division. Furthermore, CD51 was highly expressed in exhausted CD8 T cells in chronic LCMV infection, B16F10 melanoma, and CT26 colon carcinoma, and its expression level increased as cells became more differentiated. Using CRISPR-mediated knockdown, we found that the absence of CD51 led to a lower number of virus-specific CD8 T cells upon chronic lymphocytic choriomeningitis virus (LCMV) infection, although their granzyme B expression and cytokine production were maintained. Blocking CD51 also inhibited the in vitro proliferation of CD8 T cells. These results suggest that CD51 plays an important role in the early expansion of CD8 T cells and may have potential as an immunomodulatory target.

Combination TIGIT/PD-1 blockade enhances the efficacy of neoantigen vaccines in a model of pancreatic cancer

Background

Cancer neoantigens are important targets of cancer immunotherapy and neoantigen vaccines are currently in development in pancreatic ductal adenocarcinoma (PDAC) and other cancer types. Immune regulatory mechanisms in pancreatic cancer may limit the efficacy of neoantigen vaccines. Targeting immune checkpoint signaling pathways in PDAC may improve the efficacy of neoantigen vaccines.

Methods

We used KPC4580P, an established model of PDAC, to test whether neoantigen vaccines can generate therapeutic efficacy against PDAC. We focused on two immunogenic neoantigens associated with genetic alterations in the CAR12 and CDK12 genes. We tested a neoantigen vaccine comprised of two 20-mer synthetic long peptides and poly IC, a Toll-like receptor (TLR) agonist. We investigated the ability of neoantigen vaccine alone, or in combination with PD-1 and TIGIT signaling blockade to impact tumor growth. We also assessed the impact of TIGIT signaling on T cell responses in human PDAC.

Results

Neoantigen vaccines induce neoantigen-specific T cell responses in tumor-bearing mice and slow KPC4580P tumor growth. However, KPC4580P tumors express high levels of PD-L1 and the TIGIT ligand, CD155. A subset of neoantigen-specific T cells in KPC4580P tumors are dysfunctional, and express high levels of TIGIT. PD-1 and TIGIT signaling blockade in vivo reverses T cell dysfunction and enhances neoantigen vaccine-induced T cell responses and tumor regression. In human translational studies, TIGIT signaling blockade in vitro enhances neoantigen-specific T cell function following vaccination.

Conclusions

Taken together, preclinical and human translational studies support testing neoantigen vaccines in combination with therapies targeting the PD-1 and TIGIT signaling pathways in patients with PDAC.

Tackling cancer cell dormancy: Insights from immune models, and transplantation

Disseminated non-dividing (dormant) cancer cells as well as those in equilibrium with the immune response remain the major challenge for successful treatment of cancer. The equilibrium between disseminated dormant cancer cells and the immune system is reminiscent of states that can occur during infection or allogeneic tissue and cell transplantation. We discuss here the major competing models of how the immune system achieves a self nonself discrimination (pathogen/danger patterns, quorum, and coinhibition/tuning models), and suggest that taking advantage of a combination of the proposed mechanisms in each model may lead to increased efficacy in tackling cancer cell dormancy.

CD4+ T cells indirectly kill tumor cells via induction of cytotoxic macrophages in mouse models

It is well recognized that CD4⁺ T cells may play an important role in immunosurveillance and immunotherapy against cancer. However, the details of how these cells recognize and eliminate the tumor cells remain incompletely understood. For the past 25 years, we have focused on how CD4⁺ T cells reject multiple myeloma cells in a murine model (MOPC315). In our experimental system, the secreted tumor-specific antigen is taken up by tumor-infiltrating macrophages that process it and present a neoepitope [a V region-derived idiotypic (Id) peptide] on MHC class II molecules to Th1 cells. Stimulated Th1 cells produce IFNγ, which activates macrophages in a manner that elicits an M1-like, tumoricidal phenotype. Through an inducible nitric oxide synthetase (iNOS)-dependent mechanism, the M1 macrophages secrete nitric oxide (NO) that diffuses into neighboring tumor cells. Inside the tumor cells, NO-derived reactive nitrogen species, including peroxynitrite, causes nitrosylation of proteins and triggers apoptosis by the intrinsic apoptotic pathway. This mode of indirect tumor recognition by CD4⁺ T cells operates independently of MHC class II expression on cancer cells. However, secretion of the tumor-specific antigen, and uptake and MHCII presentation on macrophages, is required for rejection. Similar mechanisms can also be observed in a B-lymphoma model and in the unrelated B16 melanoma model. Our findings reveal a novel mechanism by which CD4⁺ T cells kill tumor cells indirectly via induction of intratumoral cytotoxic macrophages. The data suggest that induction of M1 polarization of tumor-infiltrating macrophages, by CD4⁺ T cells or through other means, could serve as an immunotherapeutic strategy.

Adoptive Transfer of Tumor-Specific Th2 Cells Eradicates Tumors by Triggering an In Situ Inflammatory Immune Response

Adoptive cell therapy (ACT) trials to date have focused on transfer of autologous tumor-specific cytotoxic CD8⁺ T cells; however, the potential of CD4⁺ T helper (Th) cells for ACT is gaining interest. While encouraging results have been reported with IFNγ-producing Th1 cells, tumor-specific Th2 cells have been largely neglected for ACT due to their reported tumor-promoting properties. In this study, we tested the efficacy of idiotype-specific Th2 cells for the treatment of mice with MHC class II-negative myeloma. Th2 ACT efficiently eradicated subcutaneous myeloma in an antigen-specific fashion. Transferred Th2 cells persisted in vivo and conferred long-lasting immunity. Cancer eradication mediated by tumor-specific Th2 cells did not require B cells, natural killer T cells, CD8⁺ T cells, or IFNγ. Th2 ACT was also curative against B-cell lymphoma. Upon transfer, Th2 cells induced a type II inflammation at the tumor site with massive infiltration of M2-type macrophages producing arginase. In vivo blockade of arginase strongly inhibited Th2 ACT, consistent with a key role of arginase and M2 macrophages in myeloma elimination by Th2 cells. These results illustrate that cancer eradication may be achieved by induction of a tumor-specific Th2 inflammatory immune response at the tumor site. Thus, ACT with tumor-specific Th2 cells may represent a highly efficient immunotherapy protocol against cancer. Cancer Res; 76(23); 6864-76. ©2016 AACR.

Interleukin-1 is required for cancer eradication mediated by tumor-specific Th1 cells

The role of inflammation in cancer is controversial as both tumor-promoting and tumor-suppressive aspects of inflammation have been reported. In particular, it has been shown that pro-inflammatory cytokines, like interleukin-1α (IL-1α), IL-1β, IL-6, and tumor necrosis factor α (TNFα), may either promote or suppress cancer. However, the cellular and molecular basis underlying these opposing outcomes remains enigmatic. Using mouse models for myeloma and lymphoma, we have recently reported that inflammation driven by tumor-specific T helper 1 (Th1) cells conferred protection against B-cell cancer and that interferon-γ (IFN-γ) was essential for this process. Here, we have investigated the contribution of several inflammatory mediators. Myeloma eradication by Th1 cells was not affected by inhibition of TNF-α, TNF-related weak inducer of apoptosis (TWEAK), or TNF-related apoptosis-inducing ligand (TRAIL). In contrast, cancer elimination by tumor-specific Th1 cells was severely impaired by the in vivo neutralization of both IL-1α and IL-1β (collectively named IL-1) with IL-1 receptor antagonist (IL-1Ra). The antitumor functions of tumor-specific Th1 cells and tumor-infiltrating macrophages were both affected by IL-1 neutralization. Secretion of the Th1-derived cytokines IL-2 and IFN-γ at the incipient tumor site was severely reduced by IL-1 blockade. Moreover, IL-1 was shown to synergize with IFN-γ for induction of tumoricidal activity in tumor-infiltrating macrophages. This synergy between IL-1 and IFN-γ may explain how inflammation, when driven by tumor-specific Th1 cells, represses rather than promotes cancer. Collectively, the data reveal a central role of inflammation, and more specifically of the canonical pro-inflammatory cytokine IL-1, in enhancing Th1-mediated immunity against cancer.

Programmed death-1 controls T cell survival by regulating oxidative metabolism

The coinhibitory receptor programmed death-1 (PD-1) maintains immune homeostasis by negatively regulating T cell function and survival. Blockade of PD-1 increases the severity of graft-versus-host disease (GVHD), but the interplay between PD-1 inhibition and T cell metabolism is not well studied. We found that both murine and human alloreactive T cells concomitantly upregulated PD-1 expression and increased levels of reactive oxygen species (ROS) following allogeneic bone marrow transplantation. This PD-1(Hi)ROS(Hi) phenotype was specific to alloreactive T cells and was not observed in syngeneic T cells during homeostatic proliferation. Blockade of PD-1 signaling decreased both mitochondrial H2O2 and total cellular ROS levels, and PD-1-driven increases in ROS were dependent upon the oxidation of fatty acids, because treatment with etomoxir nullified changes in ROS levels following PD-1 blockade. Downstream of PD-1, elevated ROS levels impaired T cell survival in a process reversed by antioxidants. Furthermore, PD-1-driven changes in ROS were fundamental to establishing a cell's susceptibility to subsequent metabolic inhibition, because blockade of PD-1 decreased the efficacy of later F1F0-ATP synthase modulation. These data indicate that PD-1 facilitates apoptosis in alloreactive T cells by increasing ROS in a process dependent upon the oxidation of fat. In addition, blockade of PD-1 undermines the potential for subsequent metabolic inhibition, an important consideration given the increasing use of anti-PD-1 therapies in the clinic.

CD30: from basic research to cancer therapy

The FDA recently approved an agonistic anti-CD30 drug conjugate, Brentuximab vedotin, for the treatment for CD30-positive lymphomas. The potent clinical activity of Brentuximab vedotin in Hodgkin's lymphoma and anaplastic large-cell lymphoma was greeted with great enthusiasm by oncologists as it provided a new treatment modality for these diseases. In this review, we will describe how we obtained the hybridoma by pursuing a basic research experiment unrelated to CD30. I will also review what we know about the normal biological functions of CD30 that were studied primarily in murine models of disease but also in patients. The picture emerging is that one of the primary functions of CD30 is the control of memory cells providing costimulation and trafficking information or inducing apoptosis in a microenvironment and cytokine milieu-dependent manner.

The microbiota and helminths: sharing the same niche in the human host

Human gastrointestinal bacteria often share their environment with parasitic worms, allowing physical and physiological interaction between the two groups. Such associations have the potential to affect host health as well as the bacterial and helminth populations. Although still in its early stages, research on the interaction between the microbiome and parasitic helminths in humans offers the potential to improve health by manipulating the microbiome. Previously, supplementation with various nutritional compounds has been found to increase the abundance of potentially beneficial gut commensal bacteria. Thus, nutritional microbiome manipulation to produce an environment which may decrease malnutrition associated with helminth infection and/or aid host recovery from disease is conceivable. This review discusses the influence of the gut microbiota and helminths on host nutrition and immunity and the subsequent effects on the human host's overall health. It also discusses changes occurring in the microbiota upon helminth infections and the underlying mechanisms leading to these changes. There are still significant knowledge gaps which need to be filled before meaningful progress can be made in translating knowledge from studying the human gut microbiome into therapeutic strategies. Ultimately this review aims to discuss our current knowledge as well as highlight areas requiring further investigation.

How Do CD4(+) T Cells Detect and Eliminate Tumor Cells That Either Lack or Express MHC Class II Molecules?

CD4⁺ T cells contribute to tumor eradication, even in the absence of CD8⁺ T cells. Cytotoxic CD4⁺ T cells can directly kill MHC class II positive tumor cells. More surprisingly, CD4⁺ T cells can indirectly eliminate tumor cells that lack MHC class II expression. Here, we review the mechanisms of direct and indirect CD4⁺ T cell-mediated elimination of tumor cells. An emphasis is put on T cell receptor (TCR) transgenic models, where anti-tumor responses of naïve CD4⁺ T cells of defined specificity can be tracked. Some generalizations can tentatively be made. For both MHCII^POS and MHCII^NEG tumors, presentation of tumor-specific antigen by host antigen-presenting cells (APCs) appears to be required for CD4⁺ T cell priming. This has been extensively studied in a myeloma model (MOPC315), where host APCs in tumor-draining lymph nodes are primed with secreted tumor antigen. Upon antigen recognition, naïve CD4⁺ T cells differentiate into Th1 cells and migrate to the tumor. At the tumor site, the mechanisms for elimination of MHCII^POS and MHCII^NEG tumor cells differ. In a TCR-transgenic B16 melanoma model, MHCII^POS melanoma cells are directly killed by cytotoxic CD4⁺ T cells in a perforin/granzyme B-dependent manner. By contrast, MHCII^NEG myeloma cells are killed by IFN-γ stimulated M1-like macrophages. In summary, while the priming phase of CD4⁺ T cells appears similar for MHCII^POS and MHCII^NEG tumors, the killing mechanisms are different. Unresolved issues and directions for future research are addressed.

Paradigm Shift in Dendritic Cell-Based Immunotherapy: From in vitro Generated Monocyte-Derived DCs to Naturally Circulating DC Subsets

Dendritic cell (DC)-based immunotherapy employs the patients’ immune system to fight neoplastic lesions spread over the entire body. This makes it an important therapy option for patients suffering from metastatic melanoma, which is often resistant to chemotherapy. However, conventional cellular vaccination approaches, based on monocyte-derived DCs (moDCs), only achieved modest response rates despite continued optimization of various vaccination parameters. In addition, the generation of moDCs requires extensive ex vivo culturing conceivably hampering the immunogenicity of the vaccine. Recent studies, thus, focused on vaccines that make use of primary DCs. Though rare in the blood, these naturally circulating DCs can be readily isolated and activated thereby circumventing lengthy ex vivo culture periods. The first clinical trials not only showed increased survival rates but also the induction of diversified anti-cancer immune responses. Upcoming treatment paradigms aim to include several primary DC subsets in a single vaccine as pre-clinical studies identified synergistic effects between various antigen-presenting cells.

Immune-related gene signatures predict the outcome of neoadjuvant chemotherapy

There is ample evidence that neoadjuvant chemotherapy of breast carcinoma is particularly efficient if the tumor presents signs of either a pre-existent or therapy-induced anticancer immune response. Antineoplastic chemotherapies are particularly beneficial if they succeed in inducing immunogenic cell death, hence converting the tumor into its own therapeutic vaccine. Immunogenic cell death is characterized by a pre-mortem stress response including endoplasmic reticulum stress and autophagy. Based on these premises, we attempted to identify metagenes that reflect an intratumoral immune response or local stress responses in the transcriptomes of breast cancer patients. No consistent correlations between immune- and stress-related metagenes could be identified across several cohorts of patients, representing a total of 1045 mammary carcinomas. Moreover, few if any, of the stress-relevant metagenes influenced the probability of pathological complete response to chemotherapy. In contrast, several immune-relevant metagenes had a significant positive impact on response rates. This applies in particular to a CXCL13-centered, highly reproducible metagene signature reflecting the intratumoral presence of interferon-γ-producing T cells.