Induction of Tertiary Lymphoid Structures With Antitumor Function by a Lymph Node-Derived Stromal Cell Line

Comparative Automated Quantification of Tertiary Lymphoid Structures in Two Distinct Mouse Models of Inflammation

Tertiary lymphoid structures (TLS) have been reported to form within nonlymphoid tissues upon various inflammatory conditions, such as tumors or bacterial infections. In particular, the lungs of patients with NSCLC or bacterial infections (such as tuberculosis or aspergillosis) are the sites of TLS neogenesis. An increasing number of preclinical models have been used over the years to recapitulate as accurately as possible the mechanisms and kinetics of TLS formation that are continuously reported in the clinic.We used herein two distinct murine models of pulmonary inflammation, relying on orthotopic lung tumor implantation, or intranasal administration of bacterial products, to generate TLS formation within mouse lung tissue. This review compares different workflows aiming at the detection and quantification of TLS using automated image analysis and artificial intelligence-assisted tissue classification. We also describe different methods for partitioning serial sections, depending on the tissue morphology and the experimental goal.

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.

Research trends, hotspots and future directions of tertiary lymphoid structures in cancer: a comprehensive informatics analysis and visualization study

Many studies have reported the presence of tertiary lymphoid structures (TLSs) in cancer, but the research progress of TLSs in cancer has not been systematically analyzed. Therefore, we analyzed the global scientific knowledge in the field using informatics methods. The results showed that TLSs in cancer have received increasing attention since the 21st century, with an annual publication growth rate of 27.86%. Unsupervised hierarchical clustering based on machine learning further categorized the research features into four clusters, with the cluster related to immunotherapy being considered an emerging cluster. TLSs and immunotherapy were identified as the top two hotspots with the highest occurrence frequency and total link strength. The Walktrap algorithm indicated that "TLSs, carcinoma, prognostic value" and "high endothelial venules, germinal-centers, node-like structures" are important to TLSs but remain underexplored, representing promising research directions. These findings suggest that cancer-related TLSs have brought new insights into antitumor immunity, and targeting TLSs has the potential to transform the landscape of antitumor immunotherapy.

Tertiary lymphoid structures in ovarian cancer

Ovarian cancer (OC) is a significant cause of cancer-related mortality in women worldwide. Despite advances in treatment modalities, including surgery and chemotherapy, the overall prognosis for OC patients remains poor, particularly for patients with advanced or recurrent disease. Immunotherapy, particularly immune checkpoint blockade (ICB), has revolutionized cancer treatment in various malignancies but has shown limited efficacy in treating OC, which is primarily attributed to the immunologically. Tertiary lymphoid structures (TLSs), which are ectopic aggregates of immune cells, have emerged as potential mediators of antitumor immunity. This review explores the composition, formation, and induction of tumor associated TLS (TA-TLS) in OC, along with their role and therapeutic implications in disease development and treatment. By elucidating the roles TA-TLSs and their cellular compositions played in OC microenvironment, novel therapeutic targets may be identified to overcome immune suppression and enhance immunotherapy efficacy in ovarian cancer.

Tertiary Lymphoid Structures in Microorganism-Related Cancer

Tertiary lymphoid structures (TLSs) are ectopic lymphoid tissues formed by the accumulation of lymphocytes and other components outside lymphoid organs. They have been shown to be widespread in cancers and have predictive effects on prognosis and immunotherapy efficacy; however, there is no standardized measurement guide. This paper provides a reference for future research. Moreover, the induction strategy for the formation mechanism of TLSs is a new direction for future cancer treatment, such as cancer vaccines for microorganisms. The effects of microorganisms on cancer are dual. The role of microorganisms, including bacteria, parasites, viruses, and fungi, in promoting cancer has been widely confirmed. However, the specific mechanism of their tumor suppressor effect, particularly the promotion of TLS formation, is currently unknown. In this review, we summarize the role of TLSs in cancer related to microbial infection and provide new ideas for further understanding their mechanisms of action in cancer.

Tertiary lymphoid structures and their therapeutic implications in cancer

Tertiary lymphoid structures (TLSs) are ectopic lymphoid aggregates formed by the structured accumulation of immune cells such as B cells and T cells in non-lymphoid tissues induced by infection, inflammation, and tumors. They play a crucial role in the immune response, particularly in association with tumor development, where they primarily exert anti-tumor immune functions during tumorigenesis. Current research suggests that TLSs inhibit tumor growth by facilitating immune cell infiltration and are correlated with favorable prognosis in various solid tumors, serving as an indicator of immunotherapy effectiveness to some extent. Therefore, TLSs hold great promise as a valuable biomarker. Most importantly, immunotherapies aimed to prompting TLSs formation are anticipated to be potent adjuncts to current cancer treatment. This review focuses on the formation process of TLSs and their potential applications in cancer therapy.

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.

Lymphocyte Function in Tertiary Lymphoid Structures Predicts Hepatocellular Carcinoma Outcome

An increasing number of studies have revealed a correlation between tertiary lymphoid structures (TLSs) and the outcome of hepatocellular carcinoma (HCC). Nevertheless, the associations between the heterogeneity of cellular composition and the overall survival (OS) in HCC remain unexplored. Here, we evaluated the cancer tissues from 150 HCC individuals using multiplex immunofluorescence to determine the presence and characteristics of TLS and to investigate the relationship between intra-TLS immunologic activity, TLS maturation, and intratumoral immune cell infiltration. Prognostic factors influencing the outcome were identified through both univariate and multivariate analyses. Additionally, the levels of cytotoxic T-lymphocyte antigen-4 (CTLA-4), programmed death 1, programmed death-ligand 1, and lymphocyte activation gene-3 were determined, as well as their relationship with TLS features were determined. TLS was detected in 71 (47.3%) of the 150 HCC cases and was related to higher intratumoral infiltration levels of lymphocytes. Additionally, intra-TLS lymphocyte proliferation correlated with that of intratumoral lymphocytes, and the presence of TLS and a high proportion of mature TLS demonstrated a significant correlation with better prognosis (P = .013 and P = .03, respectively). Among TLS-positive tumors, a high proportion of B cells expressing activation-induced cytidine deaminase and a high proportion of CD8+ T cells expressing CD45RO were significantly related to improved OS (P = .01 and P < .001, respectively). Comparatively, a high proportion of CD21+CD20+ B cells demonstrated a significant correlation with poorer OS (P < .001). A markedly reduced number of CTLA-4+ cells in the stromal regions in TLS-negative tumors was observed compared with TLS-positive tumors (P = .01). These findings reveal a correlation between TLS presence and improved OS in HCC patients. However, TLS exhibited significant variation in maturation state, T- and B-cell proliferation, and expression of markers related to B- and T-cell function. Notably, these characteristics were also found to possess prognostic significance, indicating that certain TLS might hinder tumor immunity by inhibiting immune cells, whereas others may foster antigen-driven immune responses, likely influenced by the composition and functional status of intra-TLS lymphocytes.

Tertiary lymphoid structures in diseases: immune mechanisms and therapeutic advances

Tertiary lymphoid structures (TLSs) are defined as lymphoid aggregates formed in non-hematopoietic organs under pathological conditions. Similar to secondary lymphoid organs (SLOs), the formation of TLSs relies on the interaction between lymphoid tissue inducer (LTi) cells and lymphoid tissue organizer (LTo) cells, involving multiple cytokines. Heterogeneity is a distinguishing feature of TLSs, which may lead to differences in their functions. Growing evidence suggests that TLSs are associated with various diseases, such as cancers, autoimmune diseases, transplant rejection, chronic inflammation, infection, and even ageing. However, the detailed mechanisms behind these clinical associations are not yet fully understood. The mechanisms by which TLS maturation and localization affect immune function are also unclear. Therefore, it is necessary to enhance the understanding of TLS development and function at the cellular and molecular level, which may allow us to utilize them to improve the immune microenvironment. In this review, we delve into the composition, formation mechanism, associations with diseases, and potential therapeutic applications of TLSs. Furthermore, we discuss the therapeutic implications of TLSs, such as their role as markers of therapeutic response and prognosis. Finally, we summarize various methods for detecting and targeting TLSs. Overall, we provide a comprehensive understanding of TLSs and aim to develop more effective therapeutic strategies.

Tumor-associated tertiary lymphoid structures in cancer: implications for immunotherapy

INTRODUCTION

Tertiary lymphoid structures (TLS) arise at chronic inflammatory sites where they function as miniature lymph nodes to generate immune responses, which can be beneficial or detrimental, in diseases as diverse as autoimmunity, chronic infections and cancer. A growing number of studies show that a TLS presence in tumors from cancer patients treated with immune checkpoint inhibitors is closely linked with improved clinical outcomes. TLS may foster the generation of specific anti-tumor immune responses and immunological memory that recognizes a patient's own tumor. Due to repeated rounds of chronic inflammation, some tumor-associated TLS may be immunologically inactive, with immune checkpoint inhibitors functioning to revitalize them through pathway activation.

AREAS COVERED

This review summarizes work on TLS and how they mediate immune responses in human tumors. We also explore TLS as potential prognostic and predictive biomarkers for immunotherapy.

EXPERT OPINION

The presence of TLS in human tumors has been linked with a better clinical prognosis, response to treatment(s) and overall survival. TLS provide a structured microenvironment for the activation, expansion and maturation of immune cells at the tumor site. These activities can enhance the efficacy of immunotherapeutic treatments such as checkpoint inhibitors and cancer vaccines by revitalizing local anti-tumor immunity.

The roles of tertiary lymphoid structures in genitourinary cancers: molecular mechanisms, therapeutic strategies, and clinical applications

The presence of tertiary lymphoid structures (TLSs) associated with distinct treatment efficacy and clinical prognosis has been identified in various cancer types. However, the mechanistic roles and clinical implications of TLSs in genitourinary (GU) cancers remain incompletely explored. Despite their potential role as predictive markers described in numerous studies, it is essential to comprehensively evaluate the characteristics of TLSs, including drivers of formation, structural foundation, cellular compositions, maturation stages, molecular features, and specific functionality to maximize their positive impacts on tumor-specific immunity. The unique contributions of these structures to cancer progression and biology have fueled interest in these structures as mediators of antitumor immunity. Emerging data are trying to explore the effects of therapeutic interventions targeting TLSs. Therefore, a better understanding of the molecular and phenotypic heterogeneity of TLSs may facilitate the development of TLSs-targeting therapeutic strategies to obtain optimal clinical benefits for GU cancers in the setting of immunotherapy. In this review, the authors focus on the phenotypic and functional heterogeneity of TLSs in cancer progression, current therapeutic interventions targeting TLSs and the clinical implications and therapeutic potential of TLSs in GU cancers.

Mature tertiary lymphoid structures: important contributors to anti-tumor immune efficacy

Tertiary lymphoid structures (TLS) represent the ectopic aggregations of immune cells arising during chronic inflammation or tumor progression. In cancer, TLS are often associated with beneficial clinical outcomes in patients undergoing immunotherapy, underscoring their prognostic and predictive significance. Mature TLS, characterized by germinal centers and areas of T-cell and B-cell aggregation, are considered primary locations for activating and maintaining both humoral and cellular anti-tumor immune effects. Despite their recognized importance, the mechanisms driving the formation of mature TLS in cancer and their influence on the immune response within tumors remain insufficiently understood. Therefore, this review aims to comprehensively explore the structural composition, development mechanisms, maturity impact factors, immunological function, and innovative therapeutic strategies of mature TLS within the tumor microenvironment. The research summarized herein offers novel insights and considerations for therapeutic approaches to promote TLS generation and maturation in patients with cancer, representing a promising avenue for future cancer therapies.

Tertiary lymphoid structures: new immunotherapy biomarker

Immunotherapy shows substantial advancement in cancer and is becoming widely used in clinical practice. A variety of biomarkers have been proposed to predict the efficacy of immunotherapy, but most of them have low predictive ability. Tertiary lymphoid structures (TLSs), the aggregation of multiple lymphocytes, have been found to exist in various tumor tissues. TLSs have been shown to correlate with patient prognosis and immunotherapy response. This review summarizes the characteristics of TLSs and the inducing factors of TLS formation, presents available evidence on the role of TLSs in predicting immunotherapy response in different cancers, and lastly emphasizes their predictive potential for neoadjuvant immunotherapy efficacy.

Intratumoral Fc-optimized agonistic CD40 antibody induces tumor rejection and systemic antitumor immunity in patients with metastatic cancer

While CD40 agonism is an attractive approach for activating antigen-presenting cells and initiating antitumor responses, previous attempts have encountered limited clinical efficacy coupled with toxicity. We previously demonstrated that interactions between the antibody Fc domain and the inhibitory receptor FcγRIIB are critical for enhanced antitumor activity. Here, we present the results of a phase 1 study on intratumoral administration of an anti-CD40 agonistic antibody (2141-V11) Fc-engineered to enhance FcγRIIB binding. Primary endpoints included safety, maximum tolerated dose (MTD), and recommended phase 2 dose. Secondary objectives included preliminary clinical activity and correlative studies from biospecimens. 2141-V11 was well-tolerated without dose-limiting toxicities and MTD was not reached. In ten evaluable patients with metastatic cancer, the overall response rate was 20%, with complete responses in two patients (melanoma and breast carcinoma) and stable disease in six patients. 2141-V11 induced tumor regression in injected and non-injected lesions, with increased leukocyte infiltration and tertiary lymphoid structures (TLS) formation in post-treatment biopsies. In a humanized mouse model for CD40 and FcγRs, 2141-V11 induced TLS formation in mice bearing orthotopic breast carcinoma, correlating with local and abscopal antitumor effects, systemic immune activation, and immune memory. These findings support the safety and efficacy of 2141-V11, warranting phase 2 studies and suggesting a unique mechanism of action for this Fc-enhanced immunotherapy (NCT04059588).

Targeting lymph nodes for enhanced cancer vaccination: From nanotechnology to tissue engineering

Lymph nodes (LNs) occupy a critical position in initiating and augmenting immune responses, both spatially and functionally. In cancer immunotherapy, tumor-specific vaccines are blooming as a powerful tool to suppress the growth of existing tumors, as well as provide preventative efficacy against tumorigenesis. Delivering these vaccines more efficiently to LNs, where antigen-presenting cells (APCs) and T cells abundantly reside, is under extensive exploration. Formulating vaccines into nanomedicines, optimizing their physiochemical properties, and surface modification to specifically bind molecules expressed on LNs or APCs, are common routes and have brought encouraging outcomes. Alternatively, porous scaffolds can be engineered to attract APCs and provide an environment for them to mature, proliferate and migrate to LNs. A relatively new research direction is inducing the formation of LN-like organoids, which have shown positive relevance to tumor prognosis. Cutting-edge advances in these directions and discussions from a future perspective are given here, from which the up-to-date pattern of cancer vaccination will be drawn to hopefully provide basic guidance to future studies.

PI3Kγ inhibition combined with DNA vaccination unleashes a B-cell-dependent antitumor immunity that hampers pancreatic cancer

Phosphoinositide-3-kinase γ (PI3Kγ) plays a critical role in pancreatic ductal adenocarcinoma (PDA) by driving the recruitment of myeloid-derived suppressor cells (MDSC) into tumor tissues, leading to tumor growth and metastasis. MDSC also impair the efficacy of immunotherapy. In this study we verify the hypothesis that MDSC targeting, via PI3Kγ inhibition, synergizes with α-enolase (ENO1) DNA vaccination in counteracting tumor growth.Mice that received ENO1 vaccination followed by PI3Kγ inhibition had significantly smaller tumors compared to those treated with ENO1 alone or the control group, and correlated with i) increased circulating anti-ENO1 specific IgG and IFNγ secretion by T cells, ii) increased tumor infiltration of CD8+ T cells and M1-like macrophages, as well as up-modulation of T cell activation and M1-like related transcripts, iii) decreased infiltration of Treg FoxP3+ T cells, endothelial cells and pericytes, and down-modulation of the stromal compartment and T cell exhaustion gene transcription, iv) reduction of mature and neo-formed vessels, v) increased follicular helper T cell activation and vi) increased "antigen spreading", as many other tumor-associated antigens were recognized by IgG2c "cytotoxic" antibodies. PDA mouse models genetically devoid of PI3Kγ showed an increased survival and a pattern of transcripts in the tumor area similar to that of pharmacologically-inhibited PI3Kγ-proficient mice. Notably, tumor reduction was abrogated in ENO1 + PI3Kγ inhibition-treated mice in which B cells were depleted.These data highlight a novel role of PI3Kγ in B cell-dependent immunity, suggesting that PI3Kγ depletion strengthens the anti-tumor response elicited by the ENO1 DNA vaccine.

Tertiary lymphoid structures in cancer: maturation and induction

Tertiary lymphoid structure (TLS) is an ectopic lymphocyte aggregate formed in peripheral non-lymphoid tissues, including inflamed or cancerous tissue. Tumor-associated TLS serves as a prominent center of antigen presentation and adaptive immune activation within the periphery, which has exhibited positive prognostic value in various cancers. In recent years, the concept of maturity regarding TLS has been proposed and mature TLS, characterized by well-developed germinal centers, exhibits a more potent tumor-suppressive capacity with stronger significance. Meanwhile, more and more evidence showed that TLS can be induced by therapeutic interventions during cancer treatments. Thus, the evaluation of TLS maturity and the therapeutic interventions that induce its formation are critical issues in current TLS research. In this review, we aim to provide a comprehensive summary of the existing classifications for TLS maturity and therapeutic strategies capable of inducing its formation in tumors.

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.

Exploring the dual role of B cells in solid tumors: implications for head and neck squamous cell carcinoma

In the tumor milieu of head and neck squamous cell carcinoma (HNSCC), distinct B cell subpopulations are present, which exert either pro- or anti-tumor activities. Multiple factors, including hypoxia, cytokines, interactions with tumor cells, and other immune infiltrating lymphocytes (TILs), alter the equilibrium between the dual roles of B cells leading to cancerogenesis. Certain B cell subsets in the tumor microenvironment (TME) exhibit immunosuppressive function. These cells are known as regulatory B (Breg) cells. Breg cells suppress immune responses by secreting a series of immunosuppressive cytokines, including IL-10, IL-35, TGF-β, granzyme B, and adenosine or dampen effector TILs by intercellular contacts. Multiple Breg phenotypes have been discovered in human and mouse cancer models. However, when compartmentalized within a tertiary lymphoid structure (TLS), B cells predominantly play anti-tumor effects. A mature TLS contains a CD20+ B cell zone with several important types of B cells, including germinal-center like B cells, antibody-secreting plasma cells, and memory B cells. They kill tumor cells via antibody-dependent cytotoxicity and phagocytosis, and local complement activation effects. TLSs are also privileged sites for local T and B cell coordination and activation. Nonetheless, in some cases, TLSs may serve as a niche for hidden tumor cells and indicate a bad prognosis. Thus, TIL-B cells exhibit bidirectional immune-modulatory activity and are responsive to a variety of immunotherapies. In this review, we discuss the functional distinctions between immunosuppressive Breg cells and immunogenic effector B cells that mature within TLSs with the focus on tumors of HNSCC patients. Additionally, we review contemporary immunotherapies that aim to target TIL-B cells. For the development of innovative therapeutic approaches to complement T-cell-based immunotherapy, a full understanding of either effector B cells or Breg cells is necessary.

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.

Cancer-associated fibroblasts drive CXCL13 production in activated T cells via TGF-beta

Introduction

Tumour-reactive T cells producing the B-cell attractant chemokine CXCL13, in solid tumours, promote development of tertiary lymphoid structures (TLS) and are associated with improved prognosis and responsiveness to checkpoint immunotherapy. Cancer associated fibroblasts are the dominant stromal cell type in non-small cell lung cancer (NSCLC) where they co-localise with T cells and can influence T cell activation and exhaustion. We questioned whether CAF directly promote CXCL13-production during T cell activation.

Methods

We characterised surface markers, cytokine production and transcription factor expression in CXCL13-producing T cells in NSCLC tumours and paired non-cancerous lung samples using flow cytometry. We then assessed the influence of human NSCLC-derived primary CAF lines on T cells from healthy donors and NSCLC patients during activation in vitro measuring CXCL13 production and expression of cell-surface markers and transcription factors by flow cytometry.

Results

CAFs significantly increased the production of CXCL13 by both CD4+ and CD8+ T cells. CAF-induced CXCL13-producing cells lacked expression of CXCR5 and BCL6 and displayed a T peripheral helper cell phenotype. Furthermore, we demonstrate CXCL13 production by T cells is induced by TGF-β and limited by IL-2. CAF provide TGF-β during T cell activation and reduce availability of IL-2 both directly (by reducing the capacity for IL-2 production) and indirectly, by expanding a population of activated Treg. Inhibition of TGF-β signalling prevented both CAF-driven upregulation of CXCL13 and Treg expansion.

Discussion

Promoting CXCL13 production represents a newly described immune-regulatory function of CAF with the potential to shape the immune infiltrate of the tumour microenvironment both by altering the effector-function of tumour infiltrating T-cells and their capacity to attract B cells and promote TLS formation.

Nanovaccines Fostering Tertiary Lymphoid Structure to Attack Mimicry Nasopharyngeal Carcinoma

Tertiary lymphoid structures (TLSs) are formed in inflamed tissues, and recent studies demonstrated that the appearance of TLSs in tumor sites is associated with a good prognosis for tumor patients. However, the process of natural TLSs' formation was slow and uncontrollable. Herein, we developed a nanovaccine consisting of Epstein-Barr virus nuclear antigen 1 (EBNA1) and a bi-adjuvant of Mn²⁺ and cytosine-phosphate-guanine (CpG) formulated with tannic acid that significantly inhibited the development of mimicry nasopharyngeal carcinoma by fostering TLS formation. The nanovaccine activated LT-α and LT-β pathways, subsequently enhancing the expression of downstream chemokines, CCL19/CCL21, CXCL10 and CXCL13, in the tumor microenvironment. In turn, normalized blood and lymph vessels were detected in the tumor tissues of the nanovaccine group, correlated with increased infiltration of lymphocytes. Especially, the proportion of the B220⁺ CD8⁺ T, which was produced via trogocytosis between T and B cells during activation of T cells, was increased in tumors of the nanovaccine group. Furthermore, the intratumoral effector memory T cells (Tem), CD45⁺, CD3⁺, CD8⁺, CD44⁺, and CD62L^-, did not decrease after blocking the egress of T cells from tumor-draining lymph nodes by FTY-720. These results demonstrated that the nanovaccine can foster TLS formation, which thus enhances local immune responses significantly, delays tumor outgrowth, and prolongs the median survival time of murine models of mimicry nasopharyngeal carcinoma, demonstrating a promising strategy for nanovaccine development.

Adoptive neoantigen-reactive T cell therapy: improvement strategies and current clinical researches

Neoantigens generated by non-synonymous mutations of tumor genes can induce activation of neoantigen-reactive T (NRT) cells which have the ability to resist the growth of tumors expressing specific neoantigens. Immunotherapy based on NRT cells has made preeminent achievements in melanoma and other solid tumors. The process of manufacturing NRT cells includes identification of neoantigens, preparation of neoantigen expression vectors or peptides, induction and activation of NRT cells, and analysis of functions and phenotypes. Numerous improvement strategies have been proposed to enhance the potency of NRT cells by engineering TCR, promoting infiltration of T cells and overcoming immunosuppressive factors in the tumor microenvironment. In this review, we outline the improvement of the preparation and the function assessment of NRT cells, and discuss the current status of clinical trials related to NRT cell immunotherapy.

The roles of tertiary lymphoid structures in chronic diseases

Tertiary lymphoid structures (TLSs) are ectopic lymphoid tissues that drive antigen-specific immune responses at sites of chronic inflammation. Unlike secondary lymphoid organs such as lymph nodes, TLSs lack capsules and have their own unique characteristics and functions. The presumed influence of TLSs on the disease course has led to widespread interest in obtaining a better understanding of their biology and function. Studies using single-cell analyses have suggested heterogeneity in TLS composition and phenotype, and consequently, functional correlates with disease progression are sometimes conflicting. The presence of TLSs correlates with a favourable disease course in cancer and infection. Conversely, in autoimmune diseases and chronic age-related inflammatory diseases including chronic kidney disease, the presence of TLSs is associated with a more severe disease course. However, the detailed mechanisms that underlie these clinical associations are not fully understood. To what extent the mechanisms of TLS development and maturation are shared across organs and diseases is also still obscure. Improved understanding of TLS development and function at the cellular and molecular levels may enable the exploitation of these structures to improve therapies for chronic diseases, including chronic kidney disease.

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.

Murine neonatal dermal fibroblast acquires a lymphoid tissue organizer cell-like activity upon synergistic activation of TNF-α receptor and LTβ receptor

Tertiary lymphoid organs (TLOs) are ectopic aggregates of immune cells. As accumulating studies demonstrate TLOs as a predictor of better prognosis in certain cancers, targeting TLO formation, which is tightly regulated by the lymphoid tissue organizer cells (LTOs), has become intriguing in cancer treatment. However, the clinical outcome of these attempts is limited, because the approaches for activating tumor adjacent LTO is lack and little is known about what type of self-cell can be used as LTO to initiate TLO formation. Here we demonstrate that co-stimulation with membrane-bound ligand LTα₁β₂ and soluble TNF-α could induced an LTO-like activity in murine neonatal dermal fibroblast, featured by high expression of cell migration-associated chemokines and adhesion molecules that resemble typical LTO gene signature. Furthermore, the LTO-phenotypic dermal fibroblast could enhance the attachment and survival of T and B cell and proliferation of T cell. These findings suggest dermal fibroblast as a promising target for TLO induction to improve cancer immunotherapy.

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.

Tertiary Lymphoid Structures: A Potential Biomarker for Anti-Cancer Therapy

A tertiary lymphoid structure (TLS) is a special component in the immune microenvironment that is mainly composed of tumor-infiltrating lymphocytes (TILs), including T cells, B cells, DC cells, and high endothelial venules (HEVs). For cancer patients, evaluation of the immune microenvironment has a predictive effect on tumor biological behavior, treatment methods, and prognosis. As a result, TLSs have begun to attract the attention of researchers as a new potential biomarker. However, the composition and mechanisms of TLSs are still unclear, and clinical detection methods are still being explored. Although some meaningful results have been obtained in clinical trials, there is still a long way to go before such methods can be applied in clinical practice. However, we believe that with the continuous progress of basic research and clinical trials, TLS detection and related treatment can benefit more and more patients. In this review, we generalize the definition and composition of TLSs, summarize clinical trials involving TLSs according to treatment methods, and describe possible methods of inducing TLS formation.

Tertiary lymphoid structures and their association to immune phenotypes and circulatory IL2 levels in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDA) is usually unresponsive to immunotherapeutic approaches. However, tertiary lymphoid structures (TLS) are associated with favorable patient outcomes in PDA. A better understanding of the B cell infiltrate and biological features of TLS formation is needed to further explore their potential and improve patient management. We analyzed tumor tissues (n = 55) and corresponding blood samples (n = 51) from PDA patients by systematical immunohistochemistry and multiplex cytokine measurements. The tissue was compartmentalized in "tumor" and "stroma" and separately examined. Clinical patient information was used to perform survival analyses. We found that the mere number of B cells is not associated with patient survival, but formation of TLS in the peritumoral stroma is a prognostic favorable marker in PDA patients. TLS-positive tissues show a higher density of CD8+ T cells and CD20+ B cells and a higher IL2 level in the peritumoral stroma than tissues without TLS. Compartmental assessment shows that gradients of IL2 expression differ with regard to TLS formation: TLS presence is associated with higher IL2 levels in the stromal than in the tumoral compartment, while no difference is seen in patients without TLS. Focusing on the stroma-to-serum gradient, only patients without TLS show significantly higher IL2 levels in the serum than in stroma. Finally, low circulatory IL2 levels are associated with local TLS formation. Our findings highlight that TLS are prognostic favorable and associated with antitumoral features in the microenvironment of PDA. Also, we propose easily accessible serum IL2 levels as a potential marker for TLS prediction.

TGF-β-mediated silencing of genomic organizer SATB1 promotes Tfh cell differentiation and formation of intra-tumoral tertiary lymphoid structures

The immune checkpoint receptor PD-1 on T follicular helper (Tfh) cells promotes Tfh:B cell interactions and appropriate positioning within tissues. Here, we examined the impact of regulation of PD-1 expression by the genomic organizer SATB1 on Tfh cell differentiation. Vaccination of CD4^CreSatb1^f/f mice enriched for antigen-specific Tfh cells, and TGF-β-mediated repression of SATB1 enhanced Tfh differentiation of human T cells. Mechanistically, high Icos expression in Satb1^-/- CD4⁺ T cells promoted Tfh cell differentiation by preventing T follicular regulatory cell skewing and resulted in increased isotype-switched B cell responses in vivo. Ovarian tumors in CD4^CreSatb1^f/f mice accumulated tumor antigen-specific, LIGHT⁺CXCL13⁺IL-21⁺ Tfh cells and tertiary lymphoid structures (TLS). TLS formation decreased tumor growth in a CD4⁺ T cell and CXCL13-dependent manner. The transfer of Tfh cells, but not naive CD4⁺ T cells, induced TLS at tumor beds and decreased tumor growth. Thus, TGF-β-mediated silencing of Satb1 licenses Tfh cell differentiation, providing insight into the genesis of TLS within tumors.

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

The complex tumor microenvironment (TME) plays a vital role in cancer development and dramatically determines the efficacy of immunotherapy. Tertiary lymphoid structures (TLSs) within the TME are well recognized and consist of T cell-rich areas containing dendritic cells (DCs) and B cell-rich areas containing germinal centers (GCs). Accumulating research has indicated that there is a close association between tumor-associated TLSs and favorable clinical outcomes in most types of cancers, though a minority of studies have reported an association between TLSs and a poor prognosis. Overall, the double-edged sword role of TLSs in the TME and potential mechanisms need to be further investigated, which will provide novel therapeutic perspectives for antitumor immunoregulation. In this review, we focus on discussing the main functions of TLSs in the TME and recent advances in the therapeutic manipulation of TLSs through multiple strategies to enhance local antitumor immunity.

Tumor-Associated Tertiary Lymphoid Structures: From Basic and Clinical Knowledge to Therapeutic Manipulation

The tumor microenvironment is a complex ecosystem almost unique to each patient. Most of available therapies target tumor cells according to their molecular characteristics, angiogenesis or immune cells involved in tumor immune-surveillance. Unfortunately, only a limited number of patients benefit in the long-term of these treatments that are often associated with relapses, in spite of the remarkable progress obtained with the advent of immune checkpoint inhibitors (ICP). The presence of “hot” tumors is a determining parameter for selecting therapies targeting the patient immunity, even though some of them still do not respond to treatment. In human studies, an in-depth analysis of the organization and interactions of tumor-infiltrating immune cells has revealed the presence of an ectopic lymphoid organization termed tertiary lymphoid structures (TLS) in a large number of tumors. Their marked similarity to secondary lymphoid organs has suggested that TLS are an “anti-tumor school” and an “antibody factory” to fight malignant cells. They are effectively associated with long-term survival in most solid tumors, and their presence has been recently shown to predict response to ICP inhibitors. This review discusses the relationship between TLS and the molecular characteristics of tumors and the presence of oncogenic viruses, as well as their role when targeted therapies are used. Also, we present some aspects of TLS biology in non-tumor inflammatory diseases and discuss the putative common characteristics that they share with tumor-associated TLS. A detailed overview of the different pre-clinical models available to investigate TLS function and neogenesis is also presented. Finally, new approaches aimed at a better understanding of the role and function of TLS such as the use of spheroids and organoids and of artificial intelligence algorithms, are also discussed. In conclusion, increasing our knowledge on TLS will undoubtedly improve prognostic prediction and treatment selection in cancer patients with key consequences for the next generation immunotherapy.

Therapeutic Induction of Tertiary Lymphoid Structures in Cancer Through Stromal Remodeling

Improving the effectiveness of anti-cancer immunotherapy remains a major clinical challenge. Cytotoxic T cell infiltration is crucial for immune-mediated tumor rejection, however, the suppressive tumor microenvironment impedes their recruitment, activation, maturation and function. Nevertheless, solid tumors can harbor specialized lymph node vasculature and immune cell clusters that are organized into tertiary lymphoid structures (TLS). These TLS support naïve T cell infiltration and intratumoral priming. In many human cancers, their presence is a positive prognostic factor, and importantly, predictive for responsiveness to immune checkpoint blockade. Thus, therapeutic induction of TLS is an attractive concept to boost anti-cancer immunotherapy. However, our understanding of how cancer-associated TLS could be initiated is rudimentary. Exciting new reagents which induce TLS in preclinical cancer models provide mechanistic insights into the exquisite stromal orchestration of TLS formation, a process often associated with a more functional or "normalized" tumor vasculature and fueled by LIGHT/LTα/LTβ, TNFα and CC/CXC chemokine signaling. These emerging insights provide innovative opportunities to induce and shape TLS in the tumor microenvironment to improve immunotherapies.

Inducible Tertiary Lymphoid Structures: Promise and Challenges for Translating a New Class of Immunotherapy

Tertiary lymphoid structures (TLS) are ectopically formed aggregates of organized lymphocytes and antigen-presenting cells that occur in solid tissues as part of a chronic inflammation response. Sharing structural and functional characteristics with conventional secondary lymphoid organs (SLO) including discrete T cell zones, B cell zones, marginal zones with antigen presenting cells, reticular stromal networks, and high endothelial venues (HEV), TLS are prominent centers of antigen presentation and adaptive immune activation within the periphery. TLS share many signaling axes and leukocyte recruitment schemes with SLO regarding their formation and function. In cancer, their presence confers positive prognostic value across a wide spectrum of indications, spurring interest in their artificial induction as either a new form of immunotherapy, or as a means to augment other cell or immunotherapies. Here, we review approaches for inducible (iTLS) that utilize chemokines, inflammatory factors, or cellular analogues vital to TLS formation and that often mirror conventional SLO organogenesis. This review also addresses biomaterials that have been or might be suitable for iTLS, and discusses remaining challenges facing iTLS manufacturing approaches for clinical translation.

Cancer-Associated Fibroblasts and T Cells: From Mechanisms to Outcomes

Over the past decade, T cell immunotherapy has changed the face of cancer treatment, providing robust treatment options for several previously intractable cancers. Unfortunately, many epithelial tumors with high mortality rates respond poorly to immunotherapy, and an understanding of the key impediments is urgently required. Cancer-associated fibroblasts (CAFs) comprise the most frequent nonneoplastic cellular component in most solid tumors. Far from an inert scaffold, CAFs significantly influence tumor neogenesis, persistence, and metastasis and are emerging as a key player in immunotherapy resistance. In this review, we discuss the physical and chemical barriers that CAFs place between effector T cells and their tumor cell targets, and the therapies poised to target them.

High endothelial venules (HEVs) in immunity, inflammation and cancer

High endothelial venules (HEVs) are specialized blood vessels mediating lymphocyte trafficking to lymph nodes (LNs) and other secondary lymphoid organs. By supporting high levels of lymphocyte extravasation from the blood, HEVs play an essential role in lymphocyte recirculation and immune surveillance for foreign invaders (bacterial and viral infections) and alterations in the body’s own cells (neoantigens in cancer). The HEV network expands during inflammation in immune-stimulated LNs and is profoundly remodeled in metastatic and tumor-draining LNs. HEV-like blood vessels expressing high levels of the HEV-specific sulfated MECA-79 antigens are induced in non-lymphoid tissues at sites of chronic inflammation in many human inflammatory and allergic diseases, including rheumatoid arthritis, Crohn’s disease, allergic rhinitis and asthma. Such vessels are believed to contribute to the amplification and maintenance of chronic inflammation. MECA-79⁺ tumor-associated HEVs (TA-HEVs) are frequently found in human tumors in CD3⁺ T cell-rich areas or CD20⁺ B-cell rich tertiary lymphoid structures (TLSs). TA-HEVs have been proposed to play important roles in lymphocyte entry into tumors, a process essential for successful antitumor immunity and lymphocyte-mediated cancer immunotherapy with immune checkpoint inhibitors, vaccines or adoptive T cell therapy. In this review, we highlight the phenotype and function of HEVs in homeostatic, inflamed and tumor-draining lymph nodes, and those of HEV-like blood vessels in chronic inflammatory diseases. Furthermore, we discuss the role and regulation of TA-HEVs in human cancer and mouse tumor models.

Epigenetic reprogramming of tumor cell-intrinsic STING function sculpts antigenicity and T cell recognition of melanoma

Lack or loss of tumor antigenicity represents one of the key mechanisms of immune escape and resistance to T cell-based immunotherapies. Evidence suggests that activation of stimulator of interferon genes (STING) signaling in tumor cells can augment their antigenicity by triggering a type I IFN-mediated sequence of autocrine and paracrine events. Although suppression of this pathway in melanoma and other tumor types has been consistently reported, the mechanistic basis remains unclear. In this study, we asked whether this suppression is, in part, epigenetically regulated and whether it is indeed a driver of melanoma resistance to T cell-based immunotherapies. Using genome-wide DNA methylation profiling, we show that promoter hypermethylation of cGAS and STING genes mediates their coordinated transcriptional silencing and contributes to the widespread impairment of the STING signaling function in clinically-relevant human melanomas and melanoma cell lines. This suppression is reversible through pharmacologic inhibition of DNA methylation, which can reinstate functional STING signaling in at least half of the examined cell lines. Using a series of T cell recognition assays with HLA-matched human melanoma tumor-infiltrating lymphocytes (TIL), we further show that demethylation-mediated restoration of STING signaling in STING-defective melanoma cell lines can improve their antigenicity through the up-regulation of MHC class I molecules and thereby enhance their recognition and killing by cytotoxic T cells. These findings not only elucidate the contribution of epigenetic processes and specifically DNA methylation in melanoma-intrinsic STING signaling impairment but also highlight their functional significance in mediating tumor-immune evasion and resistance to T cell-based immunotherapies.

Immunotherapy for Hepatocellular Carcinoma: Current Limits and Prospects

Although many approaches have been used to treat hepatocellular carcinoma (HCC), the clinical benefits remain limited, particularly for late stage HCC. In recent years, studies have focused on immunotherapy for HCC. Immunotherapies have shown promising clinical outcomes in several types of cancers and potential therapeutic effects for advanced HCC. In this review, we summarize the immune tolerance and immunotherapeutic strategies for HCC as well as the main challenges of current therapeutic approaches. We also present alternative strategies for overcoming these limitations.

Cutaneous Melanoma: Mutational Status and Potential Links to Tertiary Lymphoid Structure Formation

Recent advances in immunotherapy have enabled rapid evolution of novel interventional approaches designed to reinvigorate and expand patient immune responses against cancer. An emerging approach in cancer immunology involves the conditional induction of tertiary lymphoid structures (TLS), which are non-encapsulated ectopic lymphoid structures forming at sites of chronic, pathologic inflammation. Cutaneous melanoma (CM), a highly-immunogenic form of solid cancer, continues to rise in both incidence and mortality rate, with recent reports supporting a positive correlation between the presence of TLS in melanoma and beneficial treatment outcomes amongst advanced-stage patients. In this context, TLS in CM are postulated to serve as dynamic centers for the initiation of robust anti-tumor responses within affected regions of active disease. Given their potential importance to patient outcome, significant effort has been recently devoted to gaining a better understanding of TLS neogenesis and the influence these lymphoid organs exert within the tumor microenvironment. Here, we briefly review TLS structure, function, and response to treatment in the setting of CM. To uncover potential tumor-intrinsic mechanisms that regulate TLS formation, we have taken the novel perspective of evaluating TLS induction in melanomas impacted by common driver mutations in BRAF, PTEN, NRAS, KIT, PRDM1, and MITF. Through analysis of The Cancer Genome Atlas (TCGA), we show expression of DNA repair proteins (DRPs) including BRCA1, PAXIP, ERCC1, ERCC2, ERCC3, MSH2, and PMS2 to be negatively correlated with expression of pro-TLS genes, suggesting DRP loss may favor TLS development in support of improved patient outcome and patient response to interventional immunotherapy.

Tumor-Associated Tertiary Lymphoid Structures: A Cancer Biomarker and a Target for Next-generation Immunotherapy

The different forms of lymphoid organization that coexist in our bodies appeared at distinct time points during the evolution of the animal kingdom. Some of these forms are constitutive, either in fully dedicated organs, such as lymph nodes, or in tissue interfacing with the external environment, such as mucosal-associated lymphoid tissues. Others, known as tertiary lymphoid structures (TLS), are selectively induced in response to inflammation in any peripheral tissues and organs. In this chapter, we discuss the functional interest of each of these lymphoid organizations under different physiopathological conditions. In the context of cancer, recent findings have identified TLS formation as a hallmark of active T- and B-cell immune responses against tumors. TLS are thus a powerful prognostic factor in nearly all solid cancers, which must be taken into account along with the tumor microenvironment. The presence of TLS also predicts the response to immunotherapy including immune checkpoint blockade. With tumor-associated TLS now a key target for the next generation of immunotherapy, this chapter discusses their potential therapeutic manipulations in oncology.

Cell and tissue engineering in lymph nodes for cancer immunotherapy

In cancer, lymph nodes (LNs) coordinate tumor antigen presentation necessary for effective antitumor immunity, both at the levels of local cellular interactions and tissue-level organization. In this review, we examine how LNs may be engineered to improve the therapeutic outcomes of cancer immunotherapy. At the cellular scale, targeting the LNs impacts the potency of cancer vaccines, immune checkpoint blockade, and adoptive cell transfer. On a tissue level, macro-scale biomaterials mimicking LN features can function as immune niches for cell reprogramming or delivery in vivo, or be utilized in vitro to enable preclinical testing of drugs and vaccines. We additionally review strategies to induce ectopic lymphoid sites reminiscent of LNs that may improve antitumor T cell priming.

Humoral immune responses: Unsung heroes of the war on cancer

Solid cancers progress from primordial lesions through complex interactions between tumor-promoting and anti-tumor immune cell types, ultimately leading to the orchestration of humoral and T cell adaptive immune responses, albeit in an immunosuppressive environment. B cells infiltrating most established tumors have been associated with a dual role: Some studies have associated antibodies produced by tumor-associated B cells with the promotion of regulatory activities on myeloid cells, and also with direct immunosuppression through the production of IL-10, IL-35 or TGF-β. In contrast, recent studies in multiple human malignancies identify B cell responses with delayed malignant progression and coordinated T cell protective responses. This includes the elusive role of Tertiary Lymphoid Structures identified in many human tumors, where the function of B cells remains unknown. Here, we discuss emerging data on the dual role of B cell responses in the pathophysiology of human cancer, providing a perspective on future directions and possible novel interventions to restore the coordinated action of both branches of the adaptive immune response, with the goal of maximizing immunotherapeutic effectiveness.

Oral cancer-associated tertiary lymphoid structures: gene expression profile and prognostic value

Tertiary lymphoid structure (TLS) provides a local and critical microenvironment for both cellular and humoral immunity and supports effective antigen presentation and lymphocyte activation. However, the gene expression profile and prognostic significance of TLS in oral cancer remain largely unrevealed. In this study, we found the presence of both intratumoral and peritumoral TLSs in a series of 65 patients with oral cancer treated by surgical resection, with positive detection rates of 33.8 and 75.4%, respectively. The presence of intratumoral TLSs, but not peritumoral TLSs, was significantly associated with decreased P53 and Ki67 scores (P = 0·027 and 0·047, respectively). The survival analyses revealed that oral cancer patients with higher grades of TLSs was associated with improved disease-free survival (DFS) and overall survival (OS) (P = 0·037 and 0·031, respectively). Gene expression profiling analysis of the cytokines and chemokines responsible for lymph-node neogenesis identified a three-up-regulated-gene set, i.e. IL7, LTB and CXCL13, which was shown to be correlated with human oral cancer-associated TLSs. This study provides a framework for better understanding of oral cancer-associated TLSs and for delineating future innovative prognostic biomarkers and immune therapeutic strategies for oral cancer.

STING Signaling in Melanoma Cells Shapes Antigenicity and Can Promote Antitumor T-cell Activity

STING (stimulator of IFN genes) signaling is an innate immune pathway for induction of a spontaneous antitumor T-cell response against certain immunogenic tumors. Although antigen-presenting cells are known to be involved in this process, insight into the participation of tumor cell-intrinsic STING signaling remains weak. In this study, we find diversity in the regulation of STING signaling across a panel of human melanoma cell lines. We show that intact activation of STING signaling in a subset of human melanoma cell lines enhances both their antigenicity and susceptibility to lysis by human melanoma tumor-infiltrating lymphocytes (TIL) through the augmentation of MHC class I expression. Conversely, defects in the STING signaling pathway protect melanoma cells from increased immune recognition by TILs and limit their sensitivity to TIL lysis. Based on these findings, we propose that defects in tumor cell-intrinsic STING signaling can mediate not only tumor immune evasion but also resistance to TIL-based immunotherapies.

The Crohn's-Like Lymphoid Reaction to Colorectal Cancer-Tertiary Lymphoid Structures With Immunologic and Potentially Therapeutic Relevance in Colorectal Cancer

The Crohn's-like lymphoid reaction (CLR) to colorectal cancer (CRC), a CRC-specific ectopic lymphoid reaction, is thought to play an important role in the host response to CRC. CLR is characterized by peritumoral lymphocytic aggregates that are found at the advancing edge of the tumor. Spatial and molecular characterization of CLR within the tumor microenvironment (TME) have uncovered a spectrum of peritumoral lymphoid aggregates with varying levels of organization and maturation. In early stages of CLR development, CD4+ T-cells cluster predominantly with mature antigen presenting dendritic cells. As CLR matures, increasing numbers of B-cells, as well as follicular dendritic cells are recruited to create lymphoid follicles. When highly organized, CLR resembles functional tertiary lymphoid structures (TLS), allowing for lymphocyte recruitment to the TME and promoting a tumor-specific adaptive immune response. CLR has been consistently associated with favorable prognostic factors and improved survival among CRC patients, often providing more prognostic information than current clinical staging systems. However, consensus is lacking regarding CLR scoring and it is not clinically assessed or reported. Differences between CLR and other cancer-associated lymphoid structures exist both in primary and metastatic disease, underscoring the need to characterize organ-specific TLS. Further research is needed to explore the role of CLR in predicting response to immunotherapy and to leverage CLR to promote immunotherapeutic strategies in CRC.

Tertiary lymphoid structures in the era of cancer immunotherapy

Tertiary lymphoid structures (TLSs) are ectopic lymphoid organs that develop in non-lymphoid tissues at sites of chronic inflammation including tumours. Key common characteristics between secondary lymphoid organogenesis and TLS neogenesis have been identified. TLSs exist under different maturation states in tumours, culminating in germinal centre formation. The mechanisms that underlie the role of TLSs in the adaptive antitumour immune response are being deciphered. The description of the correlation between TLS presence and clinical benefit in patients with cancer, suggesting that TLSs could be a prognostic and predictive factor, has drawn strong interest into investigating the role of TLSs in tumours. A current major challenge is to exploit TLSs to promote lymphocyte infiltration, activation by tumour antigens and differentiation to increase the antitumour immune response. Several approaches are being developed using chemokines, cytokines, antibodies, antigen-presenting cells or synthetic scaffolds to induce TLS formation. Strategies aiming to induce TLS neogenesis in immune-low tumours and in immune-high tumours, in this case, in combination with therapeutic agents dampening the inflammatory environment and/or with immune checkpoint inhibitors, represent promising avenues for cancer treatment.