Tertiary Lymphoid Structures in Cancer: The Double-Edged Sword Role in Antitumor Immunity and Potential Therapeutic Induction Strategies

An Introduction to Tertiary Lymphoid Structures in Cancer

Immunotherapy has revolutionized therapeutics for cancer patients, which signifies the importance of effective antitumor immunity in combatting cancer. However, the benefit of immunotherapies is limited to specific patient populations and tumor types, suggesting the overt need for new immunotherapeutic targets. Tertiary lymphoid structures (TLS) are ectopic lymph node-like structures that develop at the sites of chronic inflammation such as cancer. TLS are correlated with favorable clinical outcomes across multiple solid tumors and are associated with increased tumor-infiltrating lymphocytes (TILs), particularly effector memory CD8+ T cells. Despite strong clinical data in humans, there are still major knowledge gaps on the function of TLS in cancer. Herein, we highlight the known biology and clinical impact of TLS, which offer further evidence to harness TLS for improved immunotherapeutics.

FOXP3/TLS; a prognostic marker in patients with bladder carcinoma without muscle invasion

OBJECTIVE

Bladder carcinoma (BC) is a common type of cancer. Approximately 20% of BC patients have non-muscle invasive bladder cancer (NMIBC). Despite adequate BCG treatment, recurrence occurs in approximately 40% of the patients. There is no adequate prognostic marker for recurrence in a group of patients. Forkhead box P3 (FOXP3) is a regulatory T cell marker that sometimes exhibits anti-tumoral effects and can be used as a tumor marker. T-cell immunoglobulin and mucin domain 3 (TIM-3) is an immune checkpoint inhibitor of T cells. Tertiary lymphoid structures (TLS) increase malignancy and inflammation in non-lymphoid organs. Therefore, we aimed to evaluate the prognostic value of FOXP3, TIM-3, and TLS in patients with NMIBC.

METHODS

Patients with pathologically confirmed NMIBC were included in this study. Stromal and intraepithelial cells were evaluated separately using immunohistochemistry, and FOXP3, TIM-3, TLS, FOXP3/TLS, and TIM-3/TLS were calculated and noted. The cutoff value was determined using ROC analysis. Recurrence-free survival (RFS) and overall survival (OS) were evaluated using univariate and multivariate Cox proportional hazard analyses.

RESULTS

The study included ninety-six patients. FOXP3/TLS high group had a better RFS than FOXP3/TLS low group (P = 0.001; HR, 0.079; 95% CI, 0.019-0.337). This was also significant in the multivariate analysis (P = 0.018; HR, 0.125; 95% CI, 0.022-0.705). In the group receiving BCG, FOXP3/TLS, FOXP3-TLS, TIM-3-TLS and TIM-3/TLS elevation were lower in patients with relapse than in patients without relapse and were statistically significant. Combined TIM-3 and FOXP3 elevation was found to be good prognostic regardless of whether it was found in intraepithelial, stromal or TLS.

CONCLUSION

FOXP3/TLS elevation is a good prognostic and predictive marker in all non-muscle invasive bladder cancer cases and in the subgroup receiving BCG. Elevation of FOXP3-TLS, TIM-3-TLS, and TIM-3/TLS is associated with longer RFS in patients receiving BCG. Combined TIM-3 and FOXP3 elevation is indicative of a low recurrence rate in NMIBC.

Heterogeneity of tertiary lymphoid structures predicts the response to neoadjuvant therapy and immune microenvironment characteristics in triple-negative breast cancer

BACKGROUND

Tertiary lymphoid structures (TLSs) impact cancer outcomes, including in triple-negative breast cancer (TNBC), where their role in immune modulation during neoadjuvant therapy (NAT) is underexplored.

METHODS

This study employed single-cell RNA sequencing (scRNA-seq), multiplex immunofluorescence (mIF) staining, and radiomic techniques to evaluate TLSs and the tumour microenvironment (TME) in TNBC patient samples before and after NAT.

RESULTS

The presence of TLSs in TNBC was associated with B-cell maturation and T-cell activation. Compared with TLS-low TNBC, TLS-high TNBC showed significantly greater expression of immunoglobulin family genes (IGHM and IGHG1) in B cells and greater cytotoxicity of neoantigen-specific CD8 + T cells (neoTCR8). Additionally, mIF revealed notable differences between TLSs and the TME in TNBC. Although CD8 + T-cell levels do not predict the NAT response effectively, TLS maturity strongly correlated with better NAT outcomes and prognosis (P < 0.05). An imaging biomarker scoring system was also developed to predict TLS status and NAT efficacy.

CONCLUSION

Our results demonstrated changes in TLSs and the TME in TNBC patients post-NAT. These findings confirm the predictive value of mature TLSs (mTLSs) and support the use of personalised immunotherapy based on post-NAT immune characteristics, thereby improving clinical outcomes.

The Immune Microenvironment in Prostate Cancer: A Comprehensive Review

BACKGROUND

Prostate cancer (PCa) is a malignancy with significant immunosuppressive properties and limited immune activation. This immunosuppression is linked to reduced cytotoxic T cell activity, impaired antigen presentation, and elevated levels of immunosuppressive cytokines and immune checkpoint molecules. Studies demonstrate that cytotoxic CD8+ T cell infiltration correlates with improved survival, while increased regulatory T cells (Tregs) and tumor-associated macrophages (TAMs) are associated with worse outcomes and therapeutic resistance. Th1 cells are beneficial, whereas Th17 cells, producing interleukin-17 (IL-17), contribute to tumor progression. Tumor-associated neutrophils (TANs) and immune checkpoint molecules, such as PD-1/PD-L1 and T cell immunoglobulin-3 (TIM-3) are also linked to advanced stages of PCa. Chemotherapy holds promise in converting the "cold" tumor microenvironment (TME) to a "hot" one by depleting immunosuppressive cells and enhancing tumor immunogenicity.

SUMMARY

This comprehensive review examines the immune microenvironment in PCa, focusing on the intricate interactions between immune and tumor cells in the TME. It highlights how TAMs, Tregs, cytotoxic T cells, and other immune cell types contribute to tumor progression or suppression and how PCa's low immunogenicity complicates immunotherapy.

KEY MESSAGES

The infiltration of cytotoxic CD8+ T cells and Th1 cells correlates with better outcomes, while elevated T regs and TAMs promote tumor growth, metastasis, and resistance. TANs and natural killer (NK) cells exhibit dual roles, with higher NK cell levels linked to better prognoses. Immune checkpoint molecules like PD-1, PD-L1, and TIM-3 are associated with advanced disease. Chemotherapy can improve tumor immunogenicity by depleting T regs and myeloid-derived suppressor cells, offering therapeutic promise.

Spatial multiplexed immunofluorescence analysis reveals coordinated cellular networks associated with overall survival in metastatic osteosarcoma

Patients diagnosed with advanced osteosarcoma, often in the form of lung metastases, have abysmal five-year overall survival rates. The complexity of the osteosarcoma immune tumor microenvironment has been implicated in clinical trial failures of various immunotherapies. The purpose of this exploratory study was to spatially characterize the immune tumor microenvironment of metastatic osteosarcoma lung specimens. Knowledge of the coordinating cellular networks within these tissues could then lead to improved outcomes when utilizing immunotherapy for treatment of this disease. Importantly, various cell types, interactions, and cellular neighborhoods were associated with five-year survival status. Of note, increases in cellular interactions between T lymphocytes, positive for programmed cell death protein 1, and myeloid-derived suppressor cells were observed in the 5-year deceased cohort. Additionally, cellular neighborhood analysis identified an Immune-Cold Parenchyma cellular neighborhood, also associated with worse 5-year survival. Finally, the Osteosarcoma Spatial Score, which approximates effector immune activity in the immune tumor microenvironment through the spatial proximity of immune and tumor cells, was increased within 5-year survivors, suggesting improved effector signaling in this patient cohort. Ultimately, these data represent a robust spatial multiplexed immunofluorescence analysis of the metastatic osteosarcoma immune tumor microenvironment. Various communication networks, and their association with survival, were described. In the future, identification of these networks may suggest the use of specific, combinatory immunotherapeutic strategies for improved anti-tumor immune responses and outcomes in osteosarcoma.

Exploring the impact of tertiary lymphoid structures maturity in NSCLC: insights from TLS scoring

Tertiary Lymphoid Structures (TLS) are lymphoid structures commonly associated with improved survival of cancer patients and response to immunotherapies. However, conflicting reports underscore the need to consider TLS heterogeneity and multiple features such as TLS size, composition, and maturation status, when assessing their functional impact. With the aim of gaining insights into TLS biology and evaluating the prognostic impact of TLS maturity in Non-Small Cell Lung Carcinoma (NSCLC), we developed a multiplex immunofluorescent (mIF) panel including T cell (CD3, CD8), B cell (CD20), Follicular Dendritic cell (FDC) (CD21, CD23) and mature dendritic cell (DC-LAMP) markers. We deployed this panel across a cohort of primary tumor resections from NSCLC patients (N=406) and established a mIF image analysis workstream to specifically detect TLS structures and evaluate the density of each cell phenotype. We assessed the prognostic significance of TLS size, number, and composition, to develop a TLS scoring system representative of TLS biology within a tumor. TLS relative area, (total TLS area divided by the total tumor area), was the most prognostic TLS feature (C-index: 0.54, p = 0.04). CD21 positivity was a marker driving the favorable prognostic impact, where CD21+ CD23- B cells (C-index: 0.57, p = 0.04) and CD21+ CD23- FDC (C-index: 0.58, p = 0.01) were the only prognostic cell phenotypes in TLS. Combining the three most robust prognostic TLS features: TLS relative area, the density of B cells, and FDC CD21+ CD23- we generated a TLS scoring system that demonstrated strong prognostic value in NSCLC when considering the effect of age, sex, histology, and smoking status. This TLS Score also demonstrated significant association with Immunoscore, EGFR mutational status and gene expression-based B-cell and TLS signature scores. It was not correlated with PD-L1 status in tumor cells or immune cells. In conclusion, we generated a prognostic TLS Score representative of the TLS heterogeneity and maturity undergoing within NSCLC tissues. This score could be used as a tool to explore how TLS presence and maturity impact the organization of the tumor microenvironment and support the discovery of spatial biomarker surrogates of TLS maturity, that could be used in the clinic.

The efficacy of neoadjuvant immunotherapy and lymphocyte subset predictors in locally advanced esophageal squamous cell carcinoma: A retrospective study

BACKGROUND

Despite the recognized therapeutic potential of programmed cell death protein 1/programmed death-ligand 1 (PD-1/PD-L1) inhibitors in advanced esophageal squamous cell carcinoma (ESCC), their role in neoadjuvant therapy and reliable efficacy biomarkers remain elusive.

MATERIALS AND METHODS

We retrospectively analyzed locally advanced ESCC patients who underwent surgery following a 2-cycle platinum and paclitaxel-based treatment, with or without PD-1 inhibitors (January 2020-March 2023). We assessed peripheral blood indexes and tertiary lymphoid structures (TLS) density to evaluate their impact on pathological response and prognosis, leading to a clinical prediction model for treatment efficacy and survival.

RESULTS

Of the 157 patients recruited, 106 received immunochemotherapy (ICT) and 51 received chemotherapy (CT) alone. The ICT group demonstrated a superior pathological response rate (PRR) (47.2% vs. 29.4%, p = 0.034) with comparable adverse events and postoperative complications. The ICT group also showed a median disease-free survival (DFS) of 39.8 months, unattained by the CT group. The 1-year DFS and overall survival (OS) rates were 73% and 91% for the ICT group, and 68% and 81% for the CT group, respectively. We found higher baseline activated T cells, lower baseline Treg cells, and a decreased posttreatment total lymphocyte and CD4+/CD8+ ratio predicted an enhanced PRR. Reduced posttreatment CD4+/CD8+ ratio and increased NK cells were associated with prolonged survival, while higher TLS density indicated poorer prognosis. Among ICT group, a lower posttreatment CD4+/CD8+ ratio indicated longer DFS and reduced posttreatment B cells indicated longer OS. A nomogram integrating these predictors was developed to forecast treatment efficacy and survival.

CONCLUSION

The combination of PD-1 inhibitors and chemotherapy appears promising for locally advanced ESCC. Evaluating the differentiation status and dynamic changes of peripheral blood immune cells may provide valuable predictive insights into treatment efficacy and prognosis.

Lymphocyte homing and recirculation with tumor tertiary lymphoid structure formation: predictions for successful cancer immunotherapy

The capacity of lymphocytes continuously home to lymphoid structures is remarkable for cancer immunosurveillance and immunotherapy. Lymphocyte homing and recirculation within the tumor microenvironment (TME) are now understood to be adaptive processes that are regulated by specialized cytokines and adhesion molecule signaling cascades. Restricted lymphocyte infiltration and recirculation have emerged as key mechanisms contributing to poor responses in cancer immunotherapies like chimeric antigen receptor (CAR)-T cell therapy and immune checkpoint blockades (ICBs). Uncovering the kinetics of lymphocytes in tumor infiltration and circulation is crucial for improving immunotherapies. In this review, we discuss the current insights into the adhesive and migrative molecules involved in lymphocyte homing and transmigration. The potential mechanisms within the TME that restrain lymphocyte infiltration are also summarized. Advanced on these, we outline the determinates for tertiary lymphoid structures (TLSs) formation within tumors, placing high expectations on the prognostic values of TLSs as therapeutic targets in malignancies.

Lymphotoxin β receptor and tertiary lymphoid organs shape acute and chronic allograft rejection

Solid organ transplantation remains the life-saving treatment for end-stage organ failure, but chronic rejection remains a major obstacle to long-term allograft outcomes and has not improved substantially. Tertiary lymphoid organs (TLOs) are ectopic lymphoid structures that form under conditions of chronic inflammation, and evidence from human transplantation suggests that TLOs regularly form in allografts undergoing chronic rejection. In this study, we utilized a mouse renal transplantation model and manipulation of the lymphotoxin αβ/lymphotoxin β receptor (LTαβ/LTβR) pathway, which is essential for TLO formation, to define the role of TLOs in transplantation. We showed that intragraft TLOs are sufficient to activate the alloimmune response and mediate graft rejection in a model where the only lymphoid organs are TLOs in the allograft. When transplanted to recipients with a normal set of secondary lymphoid organs, the presence of graft TLOs or LTα overexpression accelerated rejection. If the LTβR pathway was disrupted in the donor graft, TLO formation was abrogated, and graft survival was prolonged. Intravital microscopy of renal TLOs demonstrated that local T and B cell activation in TLOs is similar to that observed in secondary lymphoid organs. In summary, we demonstrated that immune activation in TLOs contributes to local immune responses, leading to earlier allograft failure. TLOs and the LTαβ/LTβR pathway are therefore prime targets to limit local immune responses and prevent allograft rejection. These findings are applicable to other diseases, such as autoimmune diseases or tumors, where either limiting or boosting local immune responses is beneficial and improves disease outcomes.

Impact of tertiary lymphoid structures on prognosis and therapeutic response in pancreatic ductal adenocarcinoma

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is known to have a heterogeneous desmoplastic tumour microenvironment (TME) with a large number of immunosuppressive cells. Recently, high B-cell infiltration in PDAC has received growing interest as a potential therapeutic target.

METHODS

Our literature review summarises the characteristics of tumour-associated tertiary lymphoid structures (TLSs) and highlight the key studies exploring the clinical outcomes of TLSs in PDAC patients and the direct effect on the TME.

RESULTS

The location, density and maturity stages of TLSs within tumours play a key role in determining the prognosis and is a new emerging target in cancer immunotherapy.

DISCUSSION

TLS development is imperative to improve the prognosis of PDAC patients. In the future, studying the genetics and immune characteristics of tumour infiltrating B cells and TLSs may lead towards enhancing adaptive immunity in PDAC and designing personalised therapies.

The promise, progress, and challenges of in situ immunization agents in cancer immunotherapy

In situ immunization (ISI) agents are an emerging and diverse class of locally acting cancer immunotherapeutic agents designed to promote innate immune activation in the early steps of the cancer immunity cycle to ultimately support development of a systemic tumor-specific immune response and protective immunologic memory. The aims of this review are to: (i) provide an introduction to ISI; (ii) summarize the history of ISI agents; (iii) expound upon the mechanism(s) and therapeutic objective(s) of ISI; (iv) compare the various approaches and therapeutic modalities developed and investigated to date; and (v) summarize clinical experiences in an effort to highlight the utility as well as the lessons and challenges of this promising approach. A prospective roadmap for future clinical development is provided that focuses on early and late-stage trial design considerations, the rationale and importance of investigating combination treatment, and the prospective use of ISI agents in the neoadjuvant setting.

Immunological landscape of solid cancer: Interplay between tumor and autoimmunity

The immune system, a central player in maintaining homeostasis, emerges as a pivotal factor in the pathogenesis and progression of two seemingly disparate yet interconnected categories of diseases: autoimmunity and cancer. This chapter delves into the intricate and multifaceted role of the immune system, particularly T cells, in orchestrating responses that govern the delicate balance between immune surveillance and self-tolerance. T cells, pivotal immune system components, play a central role in both diseases. In autoimmunity, aberrant T cell activation drives damaging immune responses against normal tissues, while in cancer, T cells exhibit suppressed responses, allowing the growth of malignant tumors. Immune checkpoint receptors, example, initially explored in autoimmunity, now revolutionize cancer treatment via immune checkpoint blockade (ICB). Though effective in various tumors, ICB poses risks of immune-related adverse events (irAEs) akin to autoimmunity. This chapter underscores the importance of understanding tumor-associated antigens and their role in autoimmunity, immune checkpoint regulation, and their implications for both diseases. It also explores autoimmunity resulting from cancer immunotherapy and shared molecular pathways in solid tumors and autoimmune diseases, highlighting their interconnectedness at the molecular level. Additionally, it sheds light on common pathways and epigenetic features shared by autoimmunity and cancer, and the potential of repurposing drugs for therapeutic interventions. Delving deeper into these insights could unlock therapeutic strategies for both autoimmunity and cancer.

Recent Findings on Therapeutic Cancer Vaccines: An Updated Review

Cancer remains one of the global leading causes of death and various vaccines have been developed over the years against it, including cell-based, nucleic acid-based, and viral-based cancer vaccines. Although many vaccines have been effective in in vivo and clinical studies and some have been FDA-approved, there are major limitations to overcome: (1) developing one universal vaccine for a specific cancer is difficult, as tumors with different antigens are different for different individuals, (2) the tumor antigens may be similar to the body's own antigens, and (3) there is the possibility of cancer recurrence. Therefore, developing personalized cancer vaccines with the ability to distinguish between the tumor and the body's antigens is indispensable. This paper provides a comprehensive review of different types of cancer vaccines and highlights important factors necessary for developing efficient cancer vaccines. Moreover, the application of other technologies in cancer therapy is discussed. Finally, several insights and conclusions are presented, such as the possibility of using cold plasma and cancer stem cells in developing future cancer vaccines, to tackle the major limitations in the cancer vaccine developmental process.

Multicellular ecotypes shape progression of lung adenocarcinoma from ground-glass opacity toward advanced stages

Lung adenocarcinoma is a type of cancer that exhibits a wide range of clinical radiological manifestations, from ground-glass opacity (GGO) to pure solid nodules, which vary greatly in terms of their biological characteristics. Our current understanding of this heterogeneity is limited. To address this gap, we analyze 58 lung adenocarcinoma patients via machine learning, single-cell RNA sequencing (scRNA-seq), and whole-exome sequencing, and we identify six lung multicellular ecotypes (LMEs) correlating with distinct radiological patterns and cancer cell states. Notably, GGO-associated neoantigens in early-stage cancers are recognized by CD8+ T cells, indicating an immune-active environment, while solid nodules feature an immune-suppressive LME with exhausted CD8+ T cells, driven by specific stromal cells such as CTHCR1+ fibroblasts. This study also highlights EGFR(L858R) neoantigens in GGO samples, suggesting potential CD8+ T cell activation. Our findings offer valuable insights into lung adenocarcinoma heterogeneity, suggesting avenues for targeted therapies in early-stage disease.

Light deficiency in Apoe-/-mice increases atheroma plaque size and vulnerability by modulating local immunity

Previous research suggests a potential involvement of the cytokine LIGHT (TNFSF14) in atherosclerosis. In this study, the genetic inactivation of Light in Apolipoprotein E deficient mice (male and female C57BL) augmented plaque size and vulnerability while decreasing Treg cells. Human and mouse transcriptomic results demonstrated deranged immune pathways in human atheromas with low LIGHT expression levels and in Light-deficient murine atheromas. In agreement with this, in vitro LIGHT-treatment of human lymphocytes, induced an elevation of Treg cell prevalence while proteomic analysis showed a downregulation of apoptotic and leukocyte cytotoxic pathways. Consistently, Light-deficient mouse lesions displayed increased plaque apoptosis and detrimental adventitial T-lymphocyte aggregates. Altogether suggested that LIGHT could promote a Treg prevalence in the local immunity to prevent the generation of vulnerable plaques via decreased cytotoxic microenvironment and apoptosis. Light gene delivery in Apoe-/-Light-/- mice, through bone marrow transplantation approaches, consistently diminished lesion size and restored local plaque immunity. Altogether demonstrate that Light-deficiency promotes atheroma plaque progression, at least in part through local loss of immune homeostasis and increased apoptosis. This study suggest that therapies based on the local delivery of LIGHT within plaques might therefore prevent immune cell derangement and advanced atherosclerosis.

MRI-based radiomic models to predict surgical margin status and infer tumor immune microenvironment in breast cancer patients with breast-conserving surgery: a multicenter validation study

OBJECTIVES

Accurate preoperative estimation of the risk of breast-conserving surgery (BCS) resection margin positivity would be beneficial to surgical planning. In this multicenter validation study, we developed an MRI-based radiomic model to predict the surgical margin status.

METHODS

We retrospectively collected preoperative breast MRI of patients undergoing BCS from three hospitals (SYMH, n = 296; SYSUCC, n = 131; TSPH, n = 143). Radiomic-based model for risk prediction of the margin positivity was trained on the SYMH patients (7:3 ratio split for the training and testing cohorts), and externally validated in the SYSUCC and TSPH cohorts. The model was able to stratify patients into different subgroups with varied risk of margin positivity. Moreover, we used the immune-radiomic models and epithelial-mesenchymal transition (EMT) signature to infer the distribution patterns of immune cells and tumor cell EMT status under different marginal status.

RESULTS

The AUCs of the radiomic-based model were 0.78 (0.66-0.90), 0.88 (0.79-0.96), and 0.76 (0.68-0.84) in the testing cohort and two external validation cohorts, respectively. The actual margin positivity rates ranged between 0-10% and 27.3-87.2% in low-risk and high-risk subgroups, respectively. Positive surgical margin was associated with higher levels of EMT and B cell infiltration in the tumor area, as well as the enrichment of B cells, immature dendritic cells, and neutrophil infiltration in the peritumoral area.

CONCLUSIONS

This MRI-based predictive model can be used as a reliable tool to predict the risk of margin positivity of BCS. Tumor immune-microenvironment alteration was associated with surgical margin status.

CLINICAL RELEVANCE STATEMENT

This study can assist the pre-operative planning of BCS. Further research on the tumor immune microenvironment of different resection margin states is expected to develop new margin evaluation indicators and decipher the internal mechanism.

KEY POINTS

• The MRI-based radiomic prediction model (CSS model) incorporating features extracted from multiple sequences and segments could estimate the margin positivity risk of breast-conserving surgery. • The radiomic score of the CSS model allows risk stratification of patients undergoing breast-conserving surgery, which could assist in surgical planning. • With the help of MRI-based radiomics to estimate the components of the immune microenvironment, for the first time, it is found that the margin status of breast-conserving surgery is associated with the infiltration of immune cells in the microenvironment and the EMT status of breast tumor cells.

scCancer2: data-driven in-depth annotations of the tumor microenvironment at single-level resolution

SUMMARY

Single-cell RNA-seq (scRNA-seq) is a powerful technique for decoding the complex cellular compositions in the tumor microenvironment (TME). As previous studies have defined many meaningful cell subtypes in several tumor types, there is a great need to computationally transfer these labels to new datasets. Also, different studies used different approaches or criteria to define the cell subtypes for the same major cell lineages. The relationships between the cell subtypes defined in different studies should be carefully evaluated. In this updated package scCancer2, designed for integrative tumor scRNA-seq data analysis, we developed a supervised machine learning framework to annotate TME cells with annotated cell subtypes from 15 scRNA-seq datasets with 594 samples in total. Based on the trained classifiers, we quantitatively constructed the similarity maps between the cell subtypes defined in different references by testing on all the 15 datasets. Secondly, to improve the identification of malignant cells, we designed a classifier by integrating large-scale pan-cancer TCGA bulk gene expression datasets and scRNA-seq datasets (10 cancer types, 175 samples, 663 857 cells). This classifier shows robust performances when no internal confidential reference cells are available. Thirdly, scCancer2 integrated a module to process the spatial transcriptomic data and analyze the spatial features of TME.

AVAILABILITY AND IMPLEMENTATION

The package and user documentation are available at http://lifeome.net/software/sccancer2/ and https://doi.org/10.5281/zenodo.10477296.

Epigenetic targets to enhance antitumor immune response through the induction of tertiary lymphoid structures

Tertiary lymphoid structures (TLS) are ectopic lymphoid aggregates found in sites of chronic inflammation such as tumors and autoimmune diseases. The discovery that TLS formation at tumor sites correlated with good patient prognosis has triggered extensive research into various techniques to induce their formation at the tumor microenvironment (TME). One strategy is the exogenous induction of specific cytokines and chemokine expression in murine models. However, applying such systemic chemokine expression can result in significant toxicity and damage to healthy tissues. Also, the TLS formed from exogenous chemokine induction is heterogeneous and different from the ones associated with favorable prognosis. Therefore, there is a need to optimize additional approaches like immune cell engineering with lentiviral transduction to improve the TLS formation in vivo. Similarly, the genetic and epigenetic regulation of the different phases of TLS neogenesis are still unknown. Understanding these molecular regulations could help identify novel targets to induce tissue-specific TLS in the TME. This review offers a unique insight into the molecular checkpoints of the different stages and mechanisms involved in TLS formation. This review also highlights potential epigenetic targets to induce TLS neogenesis. The review further explores epigenetic therapies (epi-therapy) and ongoing clinical trials using epi-therapy in cancers. In addition, it builds upon the current knowledge of tools to generate TLS and TLS phenotyping biomarkers with predictive and prognostic clinical potential.

The Emerging Role of Tertiary Lymphoid Structures in Breast Cancer: A Narrative Review

This narrative review aims to clarify the role of tertiary lymphoid structures in breast cancer. We examine their development, composition, and prognostic value, and current ways of recognizing them. A comprehensive literature review was performed using the PubMed/Medline, Scopus, and EMBASE databases. A significant area of interest in breast cancer research involves targeting immune checkpoint molecules, particularly in the triple-negative subtype, where treatment options remain limited. However, existing biomarkers have limitations in accurately predicting treatment response. In this context, tertiary lymphoid structures (TLSs) emerge as a prognostic biomarker and also as a promising predictive marker for response. TLSs are ectopic lymphoid formations or neo-organogenesis that can develop after prolonged exposure to inflammatory signals mediated by chemokines and cytokines. Their presence is inversely correlated with estrogen receptor (ER) and/or progesterone receptor (PR) expression, but positively associated with a higher pathologic complete response rate and improved overall survival. In certain scenarios, TLS-positive tumors were associated with improved outcomes regardless of the presence of PDL-1 (programmed cell death ligand 1) expression or TILs (tumor-infiltrating lymphocytes).

Emerging roles for tumor stroma in antigen presentation and anti-cancer immunity

Advances in immunotherapy in the last decade have revolutionized treatment paradigms across multiple cancer diagnoses. However, only a minority of patients derive durable benefit and progress with traditional approaches, such as cancer vaccines, remains unsatisfactory. A key to overcoming these barriers resides with a deeper understanding of tumor antigen presentation and the complex and dynamic heterogeneity of tumor-infiltrating antigen-presenting cells (APCs). Reminiscent of the 'second touch' hypothesis proposed by Klaus Ley for CD4+ T cell differentiation, the acquisition of full effector potential by lymph node- primed CD8+ T cells requires a second round of co-stimulation at the site where the antigen originated, i.e. the tumor bed. The tumor stroma holds a prime role in this process by hosting specialized APC niches, apparently distinct from tertiary lymphoid structures, that support second antigenic touch encounters and CD8+ T cell effector proliferation and differentiation. We propose that APC within second-touch niches become licensed for co-stimulation through stromal-derived instructive signals emulating embryonic or wound-healing provisional matrix remodeling. These immunostimulatory roles of stroma contrast with its widely accepted view as a physical and functional 'immune barrier'. Stromal control of antigen presentation makes evolutionary sense as the host stroma-tumor interface constitutes the prime line of homeostatic 'defense' against the emerging tumor. In this review, we outline how stroma-derived signals and cells regulate tumor antigen presentation and T-cell effector differentiation in the tumor bed. The re-definition of tumor stroma as immune rheostat rather than as inflexible immune barrier harbors significant untapped therapeutic opportunity.

The Tumor Immune Microenvironment Architecture Correlates with Risk of Recurrence in Head and Neck Squamous Cell Carcinoma

Emerging evidence suggests that not only the frequency and composition of tumor-infiltrating leukocytes but also their spatial organization might be a major determinant of tumor progression and response to therapy. Therefore, mapping and analyzing the fine tumor immune architecture could potentially provide insights for predicting cancer prognosis. Here, we performed an explorative, prospective clinical study to assess whether structures within the tumor microenvironment can predict recurrence after salvage surgery in head and neck squamous cell carcinoma (HNSCC). The major immune subsets were measured using flow cytometry and co-detection by indexing (CODEX) multiparametric imaging. Flow cytometry underestimated the number of PMN-MDSCs and neutrophils in the tumor and overestimated the tumor-infiltrating lymphocyte frequency. An ad hoc computational framework was used to identify and analyze discrete cellular neighborhoods. A high frequency of tertiary lymphoid structures composed of CD31highCD38high plasma cells was associated with reduced recurrence after surgery in HNSCC. These data support the notion that the structural architecture of the tumor immune microenvironment plays an essential role in tumor progression and indicates that type 1 tertiary lymphoid structures and long-lived CD31highCD38high plasma cells are associated with good prognosis in HNSCC.

SIGNIFICANCE

Imaging the spatial tumor immune microenvironment and evaluating the presence of type 1 tertiary lymphoid structures enables prediction of recurrence after surgery in patients with head and neck squamous cell carcinoma.

Prognostic Impact of Tumor-Infiltrating Lymphocytes, Tertiary Lymphoid Structures, and Neutrophil-to-Lymphocyte Ratio in Pulmonary Metastases from Uterine Leiomyosarcoma

BACKGROUND

The presence of tumor-infiltrating lymphocytes (TILs) and tertiary lymphoid structures (TLSs) in tumor tissue has been related to the prognosis in various malignancies. Meanwhile, neutrophil-to-lymphocyte ratio (NLR) as a systemic inflammation marker also has been associated with the prognosis in them. However, few reports have investigated the relationship between pulmonary metastases from sarcoma and these biomarkers.

METHODS

We retrospectively recruited 102 patients undergoing metastasectomy for pulmonary metastases from uterine leiomyosarcoma at Okayama University Hospital from January 2006 to December 2019. TILs and TLSs were evaluated by immunohistochemical staining of surgically resected specimens of pulmonary metastases using anti-CD3/CD8/CD103/Foxp3/CD20 antibodies. NLR was calculated from the blood examination immediately before the most recent pulmonary metastasectomy. We elucidated the relationship between the prognosis and these factors. Because we considered that the status of tumor tissue and systemic inflammation were equally valuable, we also assessed the impact of the combination of TILs or TLSs and NLR on the prognosis.

RESULTS

As for TILs, CD3-positive cells and CD8-positive cells were correlated with the prognosis. The prognosis was significantly better in patients with CD3-high group, CD8-high group, TLSs-high group, and NLR-low group, respectively. The prognosis of CD8-high/NLR-low group and TLSs-high/NLR-low group was significantly better than that of CD8-low/NLR-high group and TLSs-low/NLR-high group, respectively.

CONCLUSIONS

CD3-positive TILs, CD8-positive TILs, TLSs, and NLR are correlated with the prognosis, respectively. The combination of CD8-positive TILs or TLSs and NLR may be the indicators to predict the prognosis of patients with pulmonary metastases from uterine leiomyosarcoma.

Molecular Mechanisms Underpinning Immunometabolic Reprogramming: How the Wind Changes during Cancer Progression

Metabolism and the immunological state are intimately intertwined, as defense responses are bioenergetically expensive. Metabolic homeostasis is a key requirement for the proper function of immune cell subsets, and the perturbation of the immune-metabolic balance is a recurrent event in many human diseases, including cancer, due to nutrient fluctuation, hypoxia and additional metabolic changes occurring in the tumor microenvironment (TME). Although much remains to be understood in the field of immunometabolism, here, we report the current knowledge on both physiological and cancer-associated metabolic profiles of immune cells, and the main molecular circuits involved in their regulation, highlighting similarities and differences, and emphasizing immune metabolic liabilities that could be exploited in cancer therapy to overcome immune resistance.

Tertiary lymphoid structures correlate with enhancement of antitumor immunity in esophageal squamous cell carcinoma

BACKGROUND

Tertiary lymphoid structures (TLSs) are associated with a favorable prognosis in several cancers. However, the correlation between TLSs and outcomes of esophageal squamous cell carcinoma (ESCC) and the impact of TLSs on the tumor immune microenvironment (TIME) remain unknown.

METHODS

We pathologically evaluated the significance of TLSs in ESCC focusing on TLS maturation using 180 ESCC specimens and performed single-cell RNA sequencing (scRNA-seq) using 14 ESCC tissues to investigate functional differences of immune cells according to TLS presence.

RESULTS

TLS+ cases had better recurrence-free-survival (RFS) (p < 0.0001) and overall survival (OS) (p = 0.0016) compared with TLS- cases. Additionally, mature TLS+ cases had better RFS and OS compared with immature TLS+ cases (p = 0.019 and p = 0.015) and TLS- cases (p < 0.0001 and p = 0.0002). The scRNA-seq showed that CD8+ T cells in TLS+ tumors expressed high levels of cytotoxic signatures and antigen-presentation of dendritic cells (DCs) was enhanced in TLS+ tumors. Immunohistochemistry showed that the densities of tumor-infiltrating CD8+ T cells and DCs were significantly higher in TLS+ tumors than those in TLS- tumors.

CONCLUSIONS

These data suggest the prognostic and functional significance of TLSs in ESCC and provides new insights into TLSs on the TIME.

ABCB11 accumulated in immature tertiary lymphoid structures participates in xenobiotic metabolic process and predicts resistance to PD-1/PD-L1 inhibitors in head and neck squamous cell carcinoma

Head and neck squamous cell carcinomas (HNSCC) are at a high risk of recurrence and multimodal therapy have not significantly improved survival in recent decades. Although immune checkpoint inhibitors (ICIs) are effective in a small proportion of HNSCC patients, the majority do not respond. In this study, we for the first time revealed that xenobiotic metabolic process was significantly associated with resistance to programmed death-1 (PD-1)/programmed death-ligand 1 (PD-L1) inhibitors in HNSCC and found that ATP binding cassette subfamily B member 11 (ABCB11) accumulated in immature tertiary lymphoid structures (TLSs) predicted worse progression-free survival (PFS) and overall survival (OS) after PD-1/PD-L1 inhibitors therapy. Moreover, the expression of cytochrome P450 1A2 (CYP1A2), a cytochrome P450 (CYP) enzyme that participates in xenobiotic metabolic process, was significantly upregulated in CD45+ABCB11+ tumor-infiltrating lymphocytes (TILs) compared with CD45+ABCB11-TILs in HNSCC tissues. Whole slide scans of 110 HNSCC tissues with hematoxylin-eosin (HE) and multispectral immuno-fluorescent (mIF) staining revealed that ABCB11 had a high co-expression with CYP1A2 in immature TLSs, and colocalization of ABCB11 and CYP1A2 in immature TLs significantly associated with high infiltration of immunosuppressive T-regulatory (Treg). Our study revealed that ABCB11 accumulated in immature TLSs might upregulate CYP1A2 to mediate xenobiotic metabolic process, thus increase the immunosuppressive Treg infiltration, and induce resistance to PD-1/PD-L1 inhibitors in HNSCC.

Detection and quantitative analysis of tumor-associated tertiary lymphoid structures

Tumor-associated tertiary lymphoid structures (TLSs) are ectopic lymphoid formations within tumor tissue, with mainly B and T cell populations forming the organic aggregates. The presence of TLSs in tumors has been strongly associated with patient responsiveness to immunotherapy regimens and improving tumor prognosis. Researchers have been motivated to actively explore TLSs due to their bright clinical application prospects. Various studies have attempted to decipher TLSs regarding their formation mechanism, structural composition, induction generation, predictive markers, and clinical utilization. Meanwhile, the scientific approaches to qualitative and quantitative descriptions are crucial for TLS studies. In terms of detection, hematoxylin and eosin (H&E), multiplex immunohistochemistry (mIHC), multiplex immunofluorescence (mIF), and 12-chemokine gene signature have been the top approved methods. However, no standard methods exist for the quantitative analysis of TLSs, such as absolute TLS count, analysis of TLS constituent cells, structural features, TLS spatial location, density, and maturity. This study reviews the latest research progress on TLS detection and quantification, proposes new directions for TLS assessment, and addresses issues for the quantitative application of TLSs in the clinic.

Bidirectional crosstalk between the peripheral nervous system and lymphoid tissues/organs

The central nervous system (CNS) influences the immune system generally by regulating the systemic concentration of humoral substances (e.g., cortisol and epinephrine), whereas the peripheral nervous system (PNS) communicates specifically with the immune system according to local interactions/connections. An imbalance between the components of the PNS might contribute to pathogenesis and the further development of certain diseases. In this review, we have explored the "thread" (hardwiring) of the connections between the immune system (e.g., primary/secondary/tertiary lymphoid tissues/organs) and PNS (e.g., sensory, sympathetic, parasympathetic, and enteric nervous systems (ENS)) in health and disease in vitro and in vivo. Neuroimmune cell units provide an anatomical and physiological basis for bidirectional crosstalk between the PNS and the immune system in peripheral tissues, including lymphoid tissues and organs. These neuroimmune interactions/modulation studies might greatly contribute to a better understanding of the mechanisms through which the PNS possibly affects cellular and humoral-mediated immune responses or vice versa in health and diseases. Physical, chemical, pharmacological, and other manipulations of these neuroimmune interactions should bring about the development of practical therapeutic applications for certain neurological, neuroimmunological, infectious, inflammatory, and immunological disorders/diseases.

Application of radiomics-based multiomics combinations in the tumor microenvironment and cancer prognosis

The advent of immunotherapy, a groundbreaking advancement in cancer treatment, has given rise to the prominence of the tumor microenvironment (TME) as a critical area of research. The clinical implications of an improved understanding of the TME are significant and far-reaching. Radiomics has been increasingly utilized in the comprehensive assessment of the TME and cancer prognosis. Similarly, the advancement of pathomics, which is based on pathological images, can offer additional insights into the panoramic view and microscopic information of tumors. The combination of pathomics and radiomics has revolutionized the concept of a "digital biopsy". As genomics and transcriptomics continue to evolve, integrating radiomics with genomic and transcriptomic datasets can offer further insights into tumor and microenvironment heterogeneity and establish correlations with biological significance. Therefore, the synergistic analysis of digital image features (radiomics, pathomics) and genetic phenotypes (genomics) can comprehensively decode and characterize the heterogeneity of the TME as well as predict cancer prognosis. This review presents a comprehensive summary of the research on important radiomics biomarkers for predicting the TME, emphasizing the interplay between radiomics, genomics, transcriptomics, and pathomics, as well as the application of multiomics in decoding the TME and predicting cancer prognosis. Finally, we discuss the challenges and opportunities in multiomics research. In conclusion, this review highlights the crucial role of radiomics and multiomics associations in the assessment of the TME and cancer prognosis. The combined analysis of radiomics, pathomics, genomics, and transcriptomics is a promising research direction with substantial research significance and value for comprehensive TME evaluation and cancer prognosis assessment.

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.

Expression of a STING Gain-of-function Mutation in Endothelial Cells Initiates Lymphocytic Infiltration of the Lungs

Patients afflicted with STING gain-of-function mutations frequently present with debilitating interstitial lung disease ( ILD ) that is recapitulated in mice expressing the STING V154M mutation ( VM ). Prior radiation chimera studies revealed an unexpected and critical role for non-hematopoietic cells in the initiation of ILD. To identify STING-expressing non-hematopoietic cell types relevant to ILD, we generated a conditional knock-in ( CKI ) model in which expression of the VM allele was directed to hematopoietic cells, fibroblasts, epithelial cells, or endothelial cells. Only endothelial cell-targeted expression of the mutant allele resulted in the recruitment of immune cells to the lung and the formation of bronchus-associated lymphoid tissue, as seen in the parental VM strain. These findings reveal the importance of endothelial cells as instigators of STING-driven lung disease and suggest that therapeutic targeting of STING inhibitors to endothelial cells could potentially mitigate inflammation in the lungs of SAVI patients or patients afflicted with other ILD-related disorders.

Summary

Patients with STING gain-of-function (GOF) mutations develop life-threatening lung autoinflammation. In this study, Gao et al. utilize a mouse model of conditional STING GOF to demonstrate a role for endothelial STING GOF in initiating immune cell recruitment into lung tissues of SAVI mice.

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.

Recent advancements in tumour microenvironment landscaping for target selection and response prediction in immune checkpoint therapies achieved through spatial protein multiplexing analysis

Immune checkpoint therapies have significantly advanced cancer treatment. Nevertheless, the high costs and potential adverse effects associated with these therapies highlight the need for better predictive biomarkers to identify patients who are most likely to benefit from treatment. Unfortunately, the existing biomarkers are insufficient to identify such patients. New high-dimensional spatial technologies have emerged as a valuable tool for discovering novel biomarkers by analysing multiple protein markers at a single-cell resolution in tissue samples. These technologies provide a more comprehensive map of tissue composition, cell functionality, and interactions between different cell types in the tumour microenvironment. In this review, we provide an overview of how spatial protein-based multiplexing technologies have fuelled biomarker discovery and advanced the field of immunotherapy. In particular, we will focus on how these technologies contributed to (i) characterise the tumour microenvironment, (ii) understand the role of tumour heterogeneity, (iii) study the interplay of the immune microenvironment and tumour progression, (iv) discover biomarkers for immune checkpoint therapies (v) suggest novel therapeutic strategies.

Microenvironmental Changes in Mediastinal Fat-associated Lymphoid Clusters and Lungs in Early and Late Stages of Metastatic Lung Cancer Induction

The prognosis of metastatic lung melanoma (MLM) has been reported to be poor. An increasing number of studies have reported the function of several immune cells in cancer regression. Although the function of mediastinal fat-associated lymphoid clusters (MFALCs) in the progression of inflammatory lung lesions has been previously reported, the association between MLM progression and MFALCs development has remained unexplored. Herein, we compared the microenvironmental changes in the lungs and MFALCs among phosphate-buffered saline (PBS) and cancer groups at early (1 week) and late (2 weeks) stages following the intravenous injection of B16-F10 melanoma cells into C57BL/6 mice. Except for lung CD4+ helper T-cells and Iba1+ macrophage populations of early stage, we observed a significant increase in the proliferating and immune cell (CD20+ B-lymphocytes, CD3+ T-lymphocytes, CD8+ cytotoxic T-cells, CD16+ natural killer (NK) cells populations, area of high endothelial venules, and lung lymphatic vessels in cancer groups at both the stages as compared with the PBS groups. Furthermore, a significant positive correlation was observed between immune cell populations in MFALCs and the lungs (B- and T-lymphocytes, and NK cells in both stages). Collectively, our findings suggest a promising cancer therapeutic strategy via targeting immune cells in MFALCs.

Dynamic polarization of tumor-associated macrophages and their interaction with intratumoral T cells in an inflamed tumor microenvironment: from mechanistic insights to therapeutic opportunities

Immunotherapy has brought a paradigm shift in the treatment of tumors in recent decades. However, a significant proportion of patients remain unresponsive, largely due to the immunosuppressive tumor microenvironment (TME). Tumor-associated macrophages (TAMs) play crucial roles in shaping the TME by exhibiting dual identities as both mediators and responders of inflammation. TAMs closely interact with intratumoral T cells, regulating their infiltration, activation, expansion, effector function, and exhaustion through multiple secretory and surface factors. Nevertheless, the heterogeneous and plastic nature of TAMs renders the targeting of any of these factors alone inadequate and poses significant challenges for mechanistic studies and clinical translation of corresponding therapies. In this review, we present a comprehensive summary of the mechanisms by which TAMs dynamically polarize to influence intratumoral T cells, with a focus on their interaction with other TME cells and metabolic competition. For each mechanism, we also discuss relevant therapeutic opportunities, including non-specific and targeted approaches in combination with checkpoint inhibitors and cellular therapies. Our ultimate goal is to develop macrophage-centered therapies that can fine-tune tumor inflammation and empower immunotherapy.

Tertiary Lymphoid Structures (TLSs) and Stromal Blood Vessels Have Significant and Heterogeneous Impact on Recurrence, Lymphovascular and Perineural Invasion amongst Breast Cancer Molecular Subtypes

BACKGROUND

Tertiary lymphoid structures (TLSs) mediate local antitumor immunity, and interest in them significantly increased since cancer immunotherapy was implemented. We examined TLS- tumor stromal blood vessel interplay for each breast cancer (BC) molecular subtype related to recurrence, lymphovascular invasion (LVI), and perineural invasion (PnI).

METHODS

TLSs were quantified on hematoxylin and eosin stain specimens followed by CD34/smooth muscle actin (SMA) double immunostaining for stromal blood vessel maturation assessment. Statistical analysis linked microscopy to recurrence, LVI, and PnI.

RESULTS

TLS negative (TLS-) subgroups in each BC molecular subtype (except to Luminal A) have higher LVI, PnI, and recurrence. A significant rise in LVI and PnI were observed for the HER2+/TLS- subgroup (p < 0.001). The triple negative breast cancer (TNBC)/TLS- subgroup had the highest recurrence and invasion risk which was also significantly related to tumor grade. PnI but not LVI significantly influenced recurrence in the TNBC/TLS+ subgroup (p < 0.001). TLS-stromal blood vessel interrelation was different amongst BC molecular subtypes.

CONCLUSION

BC invasion and recurrence are strongly influenced by TLS presence and stromal blood vessels, especially for HER2 and TNBC BC molecular subtypes.

Single-cell RNA-seq reveals intratumoral heterogeneity in osteosarcoma patients: A review

While primary bone malignancies make up just 0.2% of all cancers, osteosarcoma (OS) is the third most common cancer in adolescents. Due to its highly complex and heterogeneous tumor microenvironment (TME), OS has proven difficult to treat. There has been little to no improvement in therapy for this disease over the last 40 years. Even the recent success of immunotherapies in other blood-borne and solid malignancies has not translated to OS. With frequent recurrence and lung metastases continuing to pose a challenge in the clinic, recent advancements in molecular profiling, such as single-cell RNA sequencing (scRNA-seq), have proven useful in identifying novel biomarkers of OS tumors while providing new insight into this TME that could potentially lead to new therapeutic options. This review combines the analyses of over 150,000 cells from 18 lesions ranging from primary, recurrent, and metastatic OS lesions, revealing distinct cellular populations and gene signatures that exist between them. Here, we detail these previous findings and ultimately convey the intratumoral heterogeneity that exists within OS tumor specimens.

B cells in the tumor microenvironment: Multi-faceted organizers, regulators, and effectors of anti-tumor immunity

Our understanding of tumor-infiltrating lymphocytes (TILs) is rapidly expanding beyond T cell-centric perspectives to include B cells and plasma cells, collectively referred to as TIL-Bs. In many cancers, TIL-Bs carry strong prognostic significance and are emerging as key predictors of response to immune checkpoint inhibitors. TIL-Bs can perform multiple functions, including antigen presentation and antibody production, which allow them to focus immune responses on cognate antigen to support both T cell responses and innate mechanisms involving complement, macrophages, and natural killer cells. In the stroma of the most immunologically "hot" tumors, TIL-Bs are prominent components of tertiary lymphoid structures, which resemble lymph nodes structurally and functionally. Additionally, TIL-Bs participate in a variety of other lympho-myeloid aggregates and engage in dynamic interactions with the tumor stroma. Here, we summarize our current understanding of TIL-Bs in human cancer, highlighting the compelling therapeutic opportunities offered by their unique tumor recognition and effector mechanisms.

Why does understanding the biology of fibroblasts in immunity really matter?

Fibroblasts are known for their ability to make and modify the extracellular matrix. However, there is more to them than meets the eye. It is now clear that they help define tissue microenvironments and support immune responses in organs. As technology advances, we have started to uncover the secrets of fibroblasts. In this Essay, we present fibroblasts as not only the builders and renovators of tissue environments but also the rheostat cells for immune circuits. Although they perform location-specific functions, they do not have badges of fixed identity. Instead, they display a spectrum of functional states and can swing between these states depending on the needs of the organ. As fibroblasts participate in a range of activities both in health and disease, finding the key factors that alter their development and functional states will be an important goal to restore homeostasis in maladapted tissues.

Turning Tertiary Lymphoid Structures (TLS) into Hot Spots: Values of TLS in Gastrointestinal Tumors

Tertiary lymphoid structures (TLSs) are ectopic lymphocyte aggregation structures found in the tumor microenvironment (TME). Emerging evidence shows that TLSs are significantly correlated with the progression of gastrointestinal tumors, patients' prognosis, and the efficacy of adjuvant therapy. Besides, there are still some immunosuppressive factors in the TLSs that may affect the anti-tumor responses of TLSs, including negative regulators of anti-tumor immune responses, the immune checkpoint molecules, and inappropriate tumor metabolism. Therefore, a more comprehensive understanding of TLSs' responses in gastrointestinal tumors is essential to fully understand how TLSs can fully exert their anti-tumor responses. In addition, targeting TLSs with immune checkpoint inhibitors and vaccines to establish mature TLSs is currently being developed to reprogram the TME, further benefiting cancer immunotherapies. This review summarizes recent findings on the formation of TLSs, the mechanisms of their anti-tumor immune responses, and the association between therapeutic strategies and TLSs, providing a novel perspective on tumor-associated TLSs in gastrointestinal tumors.

"Open Sesame" to the complexity of pattern recognition receptors of myeloid-derived suppressor cells in cancer

Pattern recognition receptors are primitive sensors that arouse a preconfigured immune response to broad stimuli, including nonself pathogen-associated and autologous damage-associated molecular pattern molecules. These receptors are mainly expressed by innate myeloid cells, including granulocytes, monocytes, macrophages, and dendritic cells. Recent investigations have revealed new insights into these receptors as key players not only in triggering inflammation processes against pathogen invasion but also in mediating immune suppression in specific pathological states, including cancer. Myeloid-derived suppressor cells are preferentially expanded in many pathological conditions. This heterogeneous cell population includes immunosuppressive myeloid cells that are thought to be associated with poor prognosis and impaired response to immune therapies in various cancers. Identification of pattern recognition receptors and their ligands increases the understanding of immune-activating and immune-suppressive myeloid cell functions and sheds light on myeloid-derived suppressor cell differences from cognate granulocytes and monocytes in healthy conditions. This review summarizes the different expression, ligand recognition, signaling pathways, and cancer relations and identifies Toll-like receptors as potential new targets on myeloid-derived suppressor cells in cancer, which might help us to decipher the instruction codes for reverting suppressive myeloid cells toward an antitumor phenotype.

Intra-Tumoral Secondary Follicle-like Tertiary Lymphoid Structures Are Associated with a Superior Prognosis of Overall Survival of Perihilar Cholangiocarcinoma

Ectopic lymphoid structures termed tertiary lymphoid structures (TLSs) have an immunomodulatory function and positively affect prognosis in certain cancers. However, their clinical relevance and prognostic utility in perihilar cholangiocarcinoma (pCCA) are unknown. Therefore, determining the involvement and prognostic utility of TLSs in pCCA is the aim of this study. Ninety-three patients with surgically resected pCCA were included retrospectively. Hematoxylin and eosin and immunohistochemical staining identified and classified the TLSs, and multiplex immunofluorescence determined the TLS composition in the pCCA sample. The correlations between clinical features and TLSs were analyzed using either Fisher's exact test or the Chi-squared test. Recurrence-free survival (RFS) and overall survival (OS) correlations with TLSs were analyzed using Cox regression and Kaplan-Meier analyses. We identified TLSs in 86% of patients with pCCA, including lymphoid aggregates (6.45%), primary (13.98%) and secondary follicles (65.59%). Patients with intra-tumoral secondary follicle-like TLSs (S-TLSs) had better OS (p = 0.003) and RFS (p = 0.0313). The multivariate analysis identified the presence of S-TLSs as a good independent prognostic indicator for OS but not for RFS. Interestingly, the presence of S-TLS only indicated better 5-year OS in 54 patients without lymph node metastasis (LNM-, p = 0.0232) but not in the 39 patients with lymph node metastasis (LNM+, p = 0.1244). Intra-tumoral S-TLSs predicted longer OS in patients with surgically resected pCCA, suggesting intra-tumoral S-TLSs' contribution to effective antitumor immunity and that S-TLSs hold promise for diagnostic and therapeutic development in pCCA.

Stromal and Immune Cell Dynamics in Tumor Associated Tertiary Lymphoid Structures and Anti-Tumor Immune Responses

Tertiary lymphoid structures (TLS) are ectopic lymphoid organs that have been observed in chronic inflammatory conditions including cancer, where they are thought to exert a positive effect on prognosis. Both immune and non-immune cells participate in the genesis of TLS by establishing complex cross-talks requiring both soluble factors and cell-to-cell contact. Several immune cell types, including T follicular helper cells (Tfh), regulatory T cells (Tregs), and myeloid cells, may accumulate in TLS, possibly promoting or inhibiting their development. In this manuscript, we propose to review the available evidence regarding specific aspects of the TLS formation in solid cancers, including 1) the role of stromal cell composition and architecture in the recruitment of specific immune subpopulations and the formation of immune cell aggregates; 2) the contribution of the myeloid compartment (macrophages and neutrophils) to the development of antibody responses and the TLS formation; 3) the immunological and metabolic mechanisms dictating recruitment, expansion and plasticity of Tregs into T follicular regulatory cells, which are potentially sensitive to immunotherapeutic strategies directed to costimulatory receptors or checkpoint molecules.

Oncolytic Vaccinia Virus Augments T Cell Factor 1-Positive Stem-like CD8+ T Cells, Which Underlies the Efficacy of Anti-PD-1 Combination Immunotherapy

Oncolytic virotherapy has garnered attention as an antigen-agnostic therapeutic cancer vaccine that induces cancer-specific T cell responses without additional antigen loading. As anticancer immune responses are compromised by a lack of antigenicity and chronic immunosuppressive microenvironments, an effective immuno-oncology modality that converts cold tumors into hot tumors is crucial. To evaluate the immune-activating characteristics of oncolytic vaccinia virus (VACV; JX-594, pexastimogene devacirepvec), diverse murine syngeneic cancer models with different tissue types and immune microenvironments were used. Intratumorally administered mJX-594, a murine variant of JX-594, potently increased CD8+ T cells, including antigen-specific cancer CD8+ T cells, and decreased immunosuppressive cells irrespective of tissue type or therapeutic efficacy. Remodeling of tumors into inflamed ones by mJX-594 led to a response to combined anti-PD-1 treatment, but not to mJX-594 or anti-PD-1 monotherapy. mJX-594 treatment increased T cell factor 1-positive stem-like T cells among cancer-specific CD8+ T cells, and anti-PD-1 combination treatment further increased proliferation of these cells, which was important for therapeutic efficacy. The presence of functional cancer-specific CD8+ T cells in the spleen and bone marrow for an extended period, which proliferated upon encountering cancer antigen-loaded splenic dendritic cells, further indicated that long-term durable anticancer immunity was elicited by oncolytic VACV.

Dual Effect of Immune Cells within Tumour Microenvironment: Pro- and Anti-Tumour Effects and Their Triggers

Our body is constantly exposed to pathogens or external threats, but with the immune response that our body can develop, we can fight off and defeat possible attacks or infections. Nevertheless, sometimes this threat comes from an internal factor. Situations such as the existence of a tumour also cause our immune system (IS) to be put on alert. Indeed, the link between immunology and cancer is evident these days, with IS being used as one of the important targets for treating cancer. Our IS is able to eliminate those abnormal or damaged cells found in our body, preventing the uncontrolled proliferation of tumour cells that can lead to cancer. However, in several cases, tumour cells can escape from the IS. It has been observed that immune cells, the extracellular matrix, blood vessels, fat cells and various molecules could support tumour growth and development. Thus, the developing tumour receives structural support, irrigation and energy, among other resources, making its survival and progression possible. All these components that accompany and help the tumour to survive and to grow are called the tumour microenvironment (TME). Given the importance of its presence in the tumour development process, this review will focus on one of the components of the TME: immune cells. Immune cells can support anti-tumour immune response protecting us against tumour cells; nevertheless, they can also behave as pro-tumoural cells, thus promoting tumour progression and survival. In this review, the anti-tumour and pro-tumour immunity of several immune cells will be discussed. In addition, the TME influence on this dual effect will be also analysed.

Human B Cells Mediate Innate Anti-Cancer Cytotoxicity Through Concurrent Engagement of Multiple TNF Superfamily Ligands

The essential innate immunity effector cells, natural killer and dendritic cells, express multiple plasma membrane-associated tumor necrosis factor (TNF) superfamily (TNFSF) ligands that, through simultaneous and synergistic engagement, mediate anti-cancer cytotoxicity. Here, we report that circulating B cells, mediators of adaptive humoral immunity, also mediate this innate anti-cancer immune mechanism. We show that resting human B cells isolated from peripheral blood induce apoptosis of, and efficiently kill a large variety of leukemia and solid tumor cell types. Single-cell RNA sequencing analyses indicate, and flow cytometry data confirm that B cells from circulation express transmembrane TNF, Fas ligand (FasL), lymphotoxin (LT) α1β2 and TNF-related apoptosis-inducing ligand (TRAIL). The cytotoxic activity can be inhibited by individual and, especially, combined blockade of the four transmembrane TNFSF ligands. B cells from tumor-bearing head and neck squamous cell carcinoma patients express lower levels of TNFSF ligands and are less cytotoxic than those isolated from healthy individuals. In conclusion, we demonstrate that B cells have the innate capacity to mediate anti-cancer cytotoxicity through concurrent activity of multiple plasma membrane-associated TNFSF ligands, that this mechanism is deficient in cancer patients and that it may be part of a general cancer immunosurveillance mechanism.

Targeting TNFR2 in Cancer: All Roads Lead to Rome

TNF receptor 2 (TNFR2) has become one of the best potential immune checkpoints that might be targeted, mainly because of its vital role in tumor microenvironments (TMEs). Overexpression of TNFR2 in some tumor cells and essential function in immunosuppressive cells, especially regulatory T cells (Tregs), makes blocking TNFR2 an excellent strategy in cancer treatment; however, there is evidence showing that activating TNFR2 can also inhibit tumor progression in vivo. In this review, we will discuss drugs that block and activate TNFR2 under clinical trials or preclinical developments up till now. Meanwhile, we summarize and explore the possible mechanisms related to them.

Tertiary Lymphoid Structures and Chemokine Landscape in Virus-Positive and Virus-Negative Merkel Cell Carcinoma

Tertiary lymphoid structures (TLSs) are used as biomarkers in many cancers for predicting the prognosis and assessing the response to immunotherapy. In Merkel cell carcinoma (MCC), TLSs have only been examined in MCPyV-positive cases. Here, we examined the prognostic value of the presence or absence of TLSs in 61 patients with MCC, including MCPyV-positive and MCPyV-negative cases. TLS-positive samples had a significantly better prognosis than TLS-negative samples. MCPyV-positive samples had a good prognosis with or without TLSs, and MCPyV-negative/TLS-positive samples had a similarly good prognosis as MCPyV-positive samples. Only MCPyV-negative/TLS-negative samples had a significantly poor prognosis. All cases with spontaneous regression were MCPyV-positive/TLS-positive. We also performed a comprehensive analysis of the chemokines associated with TLS formation using next-generation sequencing (NGS). The RNA sequencing results revealed 5 chemokine genes, CCL5, CCR2, CCR7, CXCL9, and CXCL13, with significantly high expression in TLS-positive samples compared with TLS-negative samples in both MCPyV-positive and MCPyV-negative samples. Only 2 chemokine genes, CXCL10 and CX3CR1, had significantly different expression levels in the presence or absence of MCPyV infection in TLS-negative samples. Patients with high CXCL13 or CCL5 expression have a significantly better prognosis than those with low expression. In conclusion, the presence of TLSs can be a potential prognostic marker even in cohorts that include MCPyV-negative cases. Chemokine profiles may help us understand the tumor microenvironment in patients with MCPyV-positive or MCPyV-negative MCC and may be a useful prognostic marker in their own right.