Tumour-infiltrating bystander CD8+ T cells activated by IL-15 contribute to tumour control in non-small cell lung cancer

Lung cancer cell-intrinsic IL-15 promotes cell migration and sensitizes murine lung tumors to anti-PD-L1 therapy

BACKGROUND

IL-15 plays a vital role in enhancing NK cell- and T-cell-mediated antitumor immune responses; however, the direct effect of IL-15 on tumor cells has not been fully elucidated. Herein, we investigated the effect of IL-15 on lung adenocarcinoma cells.

METHODS

Silencing and overexpression techniques were used to modify endogenous IL-15 expression in tumor cells. Transwell assays were used to assess tumor cell migration and invasion; a live-cell analysis system was used to evaluate cell motility; cellular morphological changes were quantified by confocal fluorescence microscopy; the molecular mechanisms underlying the effect of IL-15 on tumor cells were analyzed by western blotting; and RhoA and Cdc42 activities were evaluated by a pulldown assay. NCG and C57BL/6 mouse models were used to evaluate the functions of IL-15 in vivo.

RESULTS

Cancer cell-intrinsic IL-15 promoted cell motility and migration in vitro and metastasis in vivo via activation of the AKT-mTORC1 pathway; however, exogenous IL-15 inhibited cell motility and migration via suppression of the RhoA-MLC2 axis. Mechanistic analysis revealed that both the intracellular and extracellular IL-15-mediated effects required the expression of IL-15Rα by tumor cells. Detailed analyses revealed that the IL-2/IL-15Rβ and IL-2Rγ chains were undetected in the complex formed by intracellular IL-15 and IL-15Rα. However, when exogenous IL-15 engaged tumor cells, a complex containing the IL-15Rα, IL-2/IL-15Rβ, and IL-2Rγ chains was formed, indicating that the differential actions of intracellular and extracellular IL-15 on tumor cells might be caused by their distinctive modes of IL-15 receptor engagement. Using a Lewis lung carcinoma (LLC) metastasis model, we showed that although IL-15 overexpression facilitated the lung metastasis of LLC cells, IL-15-overexpressing LLC tumors were more sensitive to anti-PD-L1 therapy than were IL-15-wild-type LLC tumors via an enhanced antitumor immune response, as evidenced by their increased CD8+ T-cell infiltration compared to that of their counterparts.

CONCLUSIONS

Cancer cell-intrinsic IL-15 and exogenous IL-15 differentially regulate cell motility and migration. Thus, cancer cell-intrinsic IL-15 acts as a double-edged sword in tumor progression. Additionally, high levels of IL-15 expressed by tumor cells might improve the responsiveness of tumors to immunotherapies.

Intratumoral T-cell receptor repertoire composition predicts overall survival in patients with pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a lethal malignancy that is refractory to immune checkpoint inhibitor therapy. However, intratumoral T-cell infiltration correlates with improved overall survival (OS). Herein, we characterized the diversity and antigen specificity of the PDAC T-cell receptor (TCR) repertoire to identify novel immune-relevant biomarkers. Demographic, clinical, and TCR-beta sequencing data were collated from 353 patients across three cohorts that underwent surgical resection for PDAC. TCR diversity was calculated using Shannon Wiener index, Inverse Simpson index, and "True entropy." Patients were clustered by shared repertoire specificity. TCRs predictive of OS were identified and their associated transcriptional states were characterized by single-cell RNAseq. In multivariate Cox regression models controlling for relevant covariates, high intratumoral TCR diversity predicted OS across multiple cohorts. Conversely, in peripheral blood, high abundance of T-cells, but not high diversity, predicted OS. Clustering patients based on TCR specificity revealed a subset of TCRs that predicts OS. Interestingly, these TCR sequences were more likely to encode CD8+ effector memory and CD4+ T-regulatory (Tregs) T-cells, all with the capacity to recognize beta islet-derived autoantigens. As opposed to T-cell abundance, intratumoral TCR diversity was predictive of OS in multiple PDAC cohorts, and a subset of TCRs enriched in high-diversity patients independently correlated with OS. These findings emphasize the importance of evaluating peripheral and intratumoral TCR repertoires as distinct and relevant biomarkers in PDAC.

A novel intranasal peptide vaccine inhibits non-small cell lung cancer with KRAS mutation

KRAS mutations occur commonly in the lung and can lead to the development of non-small cell lung cancer (NSCLC). While the mutated KRAS protein is a neoantigen, it usually does not generate an effective anti-tumor immune response on mucosal/epithelial surfaces. Despite this, mutated KRAS remains a potential target for immunotherapy since immune targeting of this protein in animal models has been effective at eliminating tumor cells. We attempted to develop a KRAS vaccine using mutated and wild-type KRAS peptides in combination with a nanoemulsion (NE) adjuvant. The efficacy of this approach was tested in an inducible mutant KRAS-mouse lung tumor model. Animals were immunized intranasally using NE with KRAS peptides. These animals had decreased CD4+FoxP3+ T cells in both lymph nodes and spleen. Immunized animals also showed higher IFN-γ and IL-17a levels to mutated KRAS that were produced by CD8+ T cells and enhancement in KRAS-specific Th1 and Th17 responses that persisted for 3 months after the last vaccination. Importantly, the immunized animals had significantly decreased tumor incidence compared to control animals. In conclusion, a mucosal approach to KRAS vaccination demonstrated the ability to induce local KRAS-specific immune responses in the lung and resulted in reduced tumor incidence.

Applications of Anti-Cytomegalovirus T Cells for Cancer (Immuno)Therapy

Infection with cytomegalovirus (CMV) is highly prevalent in the general population and largely controlled by CD8pos T cells. Intriguingly, anti-CMV T cells accumulate over time to extraordinarily high numbers, are frequently present as tumor-resident 'bystander' T cells, and remain functional in cancer patients. Consequently, various strategies for redirecting anti-CMV CD8pos T cells to eliminate cancer cells are currently being developed. Here, we provide an overview of these strategies including immunogenic CMV peptide-loading onto endogenous HLA complexes on cancer cells and the use of tumor-directed fusion proteins containing a preassembled CMV peptide/HLA-I complex. Additionally, we discuss conveying the advantageous characteristics of anti-CMV T cells in adoptive cell therapy. Utilization of anti-CMV CD8pos T cells to generate CAR T cells promotes their in vivo persistence and expansion due to appropriate co-stimulation through the endogenous (CMV-)TCR signaling complex. Designing TCR-engineered T cells is more challenging, as the artificial and endogenous TCR compete for expression. Moreover, the use of expanded/reactivated anti-CMV T cells to target CMV peptide-expressing glioblastomas is discussed. This review highlights the most important findings and compares the benefits, disadvantages, and challenges of each strategy. Finally, we discuss how anti-CMV T cell therapies can be further improved to enhance treatment efficacy.

Tumor and local lymphoid tissue interaction determines prognosis in high-grade serous ovarian cancer

Tertiary lymphoid structure (TLS) is associated with prognosis in copy-number-driven tumors, including high-grade serous ovarian cancer (HGSOC), although the function of TLS and its interaction with copy-number alterations in HGSOC are not fully understood. In the current study, we confirm that TLS-high HGSOC patients show significantly better progression-free survival (PFS). We show that the presence of TLS in HGSOC tumors is associated with B cell maturation and cytotoxic tumor-specific T cell activation and proliferation. In addition, the copy-number loss of IL15 and CXCL10 may limit TLS formation in HGSOC; a list of genes that may dysregulate TLS function is also proposed. Last, a radiomics-based signature is developed to predict the presence of TLS, which independently predicts PFS in both HGSOC patients and immune checkpoint inhibitor (ICI)-treated non-small cell lung cancer (NSCLC) patients. Overall, we reveal that TLS coordinates intratumoral B cell and T cell response to HGSOC tumor, while the cancer genome evolves to counteract TLS formation and function.

T lymphocyte cell: A pivotal player in lung cancer

Lung cancer is responsible for the leading cause of cancer-related death worldwide, which lacks effective therapies. In recent years, accumulating evidence on the understanding of the antitumor activity of the immune system has demonstrated that immunotherapy is one of the powerful alternatives in lung cancer therapy. T cells are the core of cellular immunotherapy, which are critical for tumorigenesis and the treatment of lung cancer. Based on the different expressions of surface molecules and functional points, T cells can be subdivided into regulatory T cells, T helper cells, cytotoxic T lymphocytes, and other unconventional T cells, including γδ T cells, nature killer T cells and mucosal-associated invariant T cells. Advances in our understanding of T cells' functional mechanism will lead to a number of clinical trials on the discovery and development of new treatment strategies. Thus, we summarize the biological functions and regulations of T cells on tumorigenesis, progression, metastasis, and prognosis in lung cancer. Furthermore, we discuss the current advancements of technologies and potentials of T-cell-oriented therapeutic targets for lung cancer.

Bodywide ecological interventions on cancer

Historically, cancer research and therapy have focused on malignant cells and their tumor microenvironment. However, the vascular, lymphatic and nervous systems establish long-range communication between the tumor and the host. This communication is mediated by metabolites generated by the host or the gut microbiota, as well by systemic neuroendocrine, pro-inflammatory and immune circuitries-all of which dictate the trajectory of malignant disease through molecularly defined biological mechanisms. Moreover, aging, co-morbidities and co-medications have a major impact on the development, progression and therapeutic response of patients with cancer. In this Perspective, we advocate for a whole-body 'ecological' exploration of malignant disease. We surmise that accumulating knowledge on the intricate relationship between the host and the tumor will shape rational strategies for systemic, bodywide interventions that will eventually improve tumor control, as well as quality of life, in patients with cancer.

Harnessing anti-cytomegalovirus immunity for local immunotherapy against solid tumors

Tumor infiltration by T cells profoundly affects cancer progression and responses to immunotherapy. However, the tumor immunosuppressive microenvironment can impair the induction, trafficking, and local activity of antitumor T cells. Here, we investigated whether intratumoral injection of virus-derived peptide epitopes could activate preexisting antiviral T cell responses locally and promote antitumor responses or antigen spreading. We focused on a mouse model of cytomegalovirus (CMV), a highly prevalent human infection that induces vigorous and durable T cell responses. Mice persistently infected with murine CMV (MCMV) were challenged with lung (TC-1), colon (MC-38), or melanoma (B16-F10) tumor cells. Intratumoral injection of MCMV-derived T cell epitopes triggered in situ and systemic expansion of their cognate, MCMV-specific CD4⁺ or CD8⁺ T cells. The MCMV CD8⁺ T cell epitopes injected alone provoked arrest of tumor growth and some durable remissions. Intratumoral injection of MCMV CD4⁺ T cell epitopes with polyinosinic acid:polycytidylic acid (pI:C) preferentially elicited tumor antigen-specific CD8⁺ T cells, promoted tumor clearance, and conferred long-term protection against tumor rechallenge. Notably, secondary proliferation of MCMV-specific CD8⁺ T cells correlated with better tumor control. Importantly, intratumoral injection of MCMV-derived CD8⁺ T cell-peptide epitopes alone or CD4⁺ T cell-peptide epitopes with pI:C induced potent adaptive and innate immune activation of the tumor microenvironment. Thus, CMV-derived peptide epitopes, delivered intratumorally, act as cytotoxic and immunotherapeutic agents to promote immediate tumor control and long-term antitumor immunity that could be used as a stand-alone therapy. The tumor antigen-agnostic nature of this approach makes it applicable across a broad range of solid tumors regardless of their origin.

Exhausted PD-1+ TOX+ CD8+ T Cells Arise Only in Long-Term Experimental Trypanosoma cruzi Infection

Infection with Trypanosoma cruzi remains the most important neglected zoonosis in Latin America. This infection does not lead to specific symptoms in the acute phase, but chronic infection can result in Chagas disease (CD) with cardiac and/or gastrointestinal manifestations that can lead to death. CD8⁺ T cells are highly effective and essential to control this infection, but fail to eliminate all parasites. In this study, we show that the CD8⁺ T cells are modulated by the transient induction of co-inhibitory receptors during acute infection of C57BL/6 mice. Therapeutic intervention strategies with blocking antibodies only had a marginal effect on the elimination of parasite reservoirs. Only long-term chronic infection gave rise to dysfunctional CD8⁺ T cells, which were characterized by high expression of the inhibitory receptor PD-1 and the co-expression of the transcription factor TOX, which plays a crucial role in the maintenance of the exhausted phenotype. PD-1⁺ TOX⁺ CD8⁺ T cells isolated from the site of infection produced significantly less IFN-γ, TNF-α and Granzyme B than their PD-1^- TOX^- CD8⁺ T cell counterparts after T. cruzi-specific stimulation ex vivo. Taken together, we provide evidence that, in the context of experimental infection of mice, the magnitude of the CD8⁺ T cell response in the acute phase is sufficient for parasite control and cannot be further increased by targeting co-inhibitory receptors. In contrast, persistent long-term chronic infection leads to an increase of exhausted T cells within the tissues of persistence. To our knowledge, this is the first description of infection-induced CD8⁺ T cells with an exhausted phenotype and reduced cytokine production in muscles of T. cruzi-infected mice.