Dendritic cell targeting with Fc-enhanced CD40 antibody agonists induces durable antitumor immunity in humanized mouse models of bladder cancer

Emerging therapeutics targeting tumor-associated macrophages for the treatment of solid organ cancers

INTRODUCTION

Over the last decade, immune checkpoint inhibitors (ICIs) like PD-1/PD-L1 or CTLA-4, which reinvigorate T cells for tumor control have become standard-of-care treatment options. In response to the increasingly recognized mechanisms of resistance to T cell activation in immunologically cold tumors, immuno-oncology drug development has started to shift beyond T cell approaches. These include tumor-associated macrophages (TAMs), a major pro-tumor immune cell population in the tumor microenvironment known to silence immune responses.

AREAS COVERED

Here we outline anti-TAM therapies in current development, either as monotherapy or in combination with other treatment modalities. We describe emerging drugs targeting TAMs under investigation in phase II and III testing with a focus on their distinguishing mechanism of action which include (1) reprogramming of TAMs toward anti-tumor function and immune surveillance, (2) blockade of recruitment, and (3) reduction and ablation of TAMs.

EXPERT OPINION

Several new immuno-oncology agents are under investigation to harness anti-tumor functions of TAMs. While robust anti-tumor efficacy of anti-TAM therapies across advanced solid organ cancers remains elusive to-date, TAM reprogramming therapies have yielded benefits in select cancers. The inherent heterogeneity of the diverse TAM population will require enhanced investments into biomarker-driven approaches to fully leverage its therapeutic potential.

Unleashing the therapeutic potential of tumor-draining lymph nodes: spotlight on bladder cancer

Tumor-draining lymph nodes (TDLNs) are often involved during the metastasis of bladder cancer (BC), which is associated with a poor prognosis. Recent studies have shown that TDLNs are a major source of host anti-tumor immunity, which can impede tumor progression and favor tumor immunotherapy. However, during tumor progression, various tumor-derived mediators modulate the TDLN microenvironment, impairing their protective function. Ultimately, TDLNs provide the soil for the proliferation and dissemination of tumor cells. Therefore, surgical removal of TDLNs is commonly recommended in various solid tumors to prevent metastasis, but this poses significant challenges for leveraging TDLNs in immunotherapy. Additionally, lymph node dissection (LND) has not shown survival benefits in some tumors. Hence, the decision to remove TDLNs in oncological treatment needs to be reconsidered. Herein, we spotlight the TDLNs of BC and introduce how BC cells modulate stromal cells and immune cells to shape an immunosuppressive TDLN microenvironment for BC progression. We summarize the existing therapeutic strategies to reinvigorate anti-tumor immunity in TDLNs. Furthermore, we discuss whether to preserve TDLNs and the role of LND during oncological treatment.

Recent developments in myeloid immune modulation in cancer therapy

Myeloid cells play a crucial dual role in cancer progression and response to therapy, promoting tumor growth, enabling immune suppression, and contributing to metastatic spread. The ability of these cells to modulate the immune system has made them attractive targets for therapeutic strategies aimed at shifting their function from tumor promotion to fostering antitumor immunity. Therapeutic approaches targeting myeloid cells focus on modifying their numbers, genetics, metabolism, and interactions within the tumor microenvironment. These strategies aim to reverse their suppressive functions and redirect them to support antitumor immune responses by inhibiting immunosuppressive pathways, targeting specific receptors, and promoting their differentiation into less immunosuppressive phenotypes. Here, we discuss recent approaches to clinically target tumor myeloid cells, focusing on reprogramming myeloid cells to promote antitumor immunity.

Plasma membrane-coated nanoparticles and membrane vesicles to orchestrate multimodal antitumor immunity

BACKGROUND

A number of immunotherapeutic approaches have been developed and are entering the clinic. Bispecific antibodies (BsAbs) are one of these modalities and induce robust efficacy by endogenous T cells in several hematological malignancies. However, most of the treated patients experience only a temporary benefit. Currently available BsAbs provide only anti-CD3 antibody-mediated T-cell stimulation, but not the costimulation or cytokine signaling essential for full T-cell activation. Here, we hypothesized that the simultaneous input of more comprehensive signals would elicit more robust and durable effector T-cell functions.

METHODS

We genetically engineered the leukemia cell line K562 to express BsAbs, costimulatory ligands, cytokines, and blocking antibodies against immune checkpoint molecules on the cell surface, from which we obtained plasma membrane fractions by mechanical homogenization and subsequent isolation steps. Plasma membranes were reconstituted on the poly (lactic-co-glycolic acid) surface to generate membrane-coated nanoparticles (NPs). Alternatively, nano-sized membrane vesicles (MVs) were generated by ultrasonic dispersion of the isolated membranes. The antitumor function of NPs and MVs loaded with various immunomodulatory factors was evaluated in vitro and in vivo.

RESULTS

Both membrane-coated NPs and MVs induced BsAb-mediated antigen-specific cytotoxic activity in non-specific T cells, with MVs inducing a slightly better response in vivo. Importantly, T-cell activation was elicited only in the presence of target tumor cells, providing a safety advantage for clinical use. NPs and MVs expressing costimulatory molecules (CD80/4-1BBL) and cytokines (interleukin (IL)-7/IL-15) further enhanced effector T-cell function and induced therapeutic efficacy in vivo. In addition, MVs expressing immune checkpoint antibodies and inflammatory cytokines IL-12 and IL-18 induced objective antitumor responses in solid tumor models partly by converting immunosuppressive macrophages to proinflammatory phenotypes and inducing cytotoxic T-cell infiltration into the tumor. Finally, we showed that MVs were also engineered to activate natural killer (NK) cells by loading multiple ligands. MVs loaded with BsAbs, 4-1BBL, IL-15, and IL-21 induced NK-cell cytotoxic activity in an antigen-specific manner.

CONCLUSIONS

We developed antitumor NPs and MVs that efficiently induced antitumor immune responses in vivo by simultaneously delivering multiple immunostimulatory signals to endogenous T cells. This platform enables the delivery of desired combinations of antitumor immune signals into T cells and NK cells.

Tumor-associated macrophages in bladder cancer: roles and targeted therapeutic strategies

Bladder cancer (BC) is the ninth most common and "expensive" cancer in the world. Despite the availability of various treatment modalities such as chemotherapy, immunotherapy and surgery, the overall survival rate of patients with advanced bladder cancer remains low. As one of the most abundant infiltrating immune cells in bladder cancer, tumor-associated macrophages (TAMs) play an important role in the development of BC and in the standard regimen of intravesical BCG therapy. Targeting TAMs have achieved excellent results in clinical trials for a variety of other cancers, but few studies have been conducted for bladder cancer. Further exploration is still needed to develop TAM-related therapeutic strategies for BC treatment, which are expected to improve the therapeutic efficacy and life quality of patients. This review summarizes the relationship between TAMs in bladder cancer and disease staging, evolution, patient prognosis, and treatment outcome. Several potential TAM targets in BC are also pointed, which may help to inhibit tumor-promoting TAMs and provide new therapeutic approaches for advanced BC.

Linking Effector Function to Antitumor Monoclonal Antibody Efficacy

This Pillars of Immunology article is a commentary on “Inhibitory Fc receptors modulate in vivo cytoxicity against tumor targets”, a pivotal article written by R. A. Clynes, T. L. Towers, L. G. Presta, and J. V. Ravetch, and published in Nature Medicine, in 2000. https://www.nature.com/articles/nm0400_443.

Quantifying biomolecular organisation in membranes with brightness-transit statistics

Cells crucially rely on the interactions of biomolecules at their plasma membrane to maintain homeostasis. Yet, a methodology to systematically quantify biomolecular organisation, measuring diffusion dynamics and oligomerisation, represents an unmet need. Here, we introduce the brightness-transit statistics (BTS) method based on fluorescence fluctuation spectroscopy and combine information from brightness and transit times to elucidate biomolecular diffusion and oligomerisation in both cell-free in vitro and in vitro systems incorporating living cells. We validate our approach in silico with computer simulations and experimentally using oligomerisation of EGFP tethered to supported lipid bilayers. We apply our pipeline to study the oligomerisation of CD40 ectodomain in vitro and endogenous CD40 on primary B cells. While we find a potential for CD40 to oligomerize in a concentration or ligand depended manner, we do not observe mobile oligomers on B cells. The BTS method combines sensitive analysis, quantification, and intuitive visualisation of dynamic biomolecular organisation.

Ultrasound-Induced In Situ Dopamine Polymerization and Deep Mucosal Penetration for Intraluminal Drug Administration

Prolonging the residence time of drugs in the lumen and propelling them into deep lesions are highly desired for intraluminal drug administration. However, rapid drug efflux caused by dynamic intraluminal contents limits sustained drug concentrations, causing poor pharmaceutical absorption and reduced efficacy. Here, we combined theory and experiments to demonstrate a distinctive drug delivery strategy using clinically available medical ultrasound technology. Through ultrasound-induced in vivo dopamine polymerization and rapidly propelling high-energy shock waves, the resultant drug formulations can tolerate a variable intraluminal environment and penetrate deep mucosa. As a result, this ultrasound-mediated in situ adhesion and self-propelled technique signal a secure and universal strategy for the rapid coating of functional adhesion layers in vivo. Theoretically, this strategy is applicable to any hollow tissue, where ultrasound is accessible.

Fc engineering by monoclonal mammalian cell display for improved affinity and selectivity towards FcγRs

Fc optimization can significantly enhance therapeutic efficacy of monoclonal antibodies. However, existing Fc engineering approaches are sub-optimal with noted limitations, such as inappropriate glycosylation, polyclonal libraries, and utilizing fragment but not full-length IgG display. Applying cell cycle arrested recombinase-mediated cassette exchange, this study constructed high-quality monoclonal Fc libraries in CHO cells, displayed full-length IgG on cell surface, and preformed ratiometric fluorescence activated cell sorting (FACS) with the antigen and individual FcγRs. Identified Fc variants were quantitatively evaluated by flow cytometry, ELISA, kinetic and steady-state binding affinity measurements, and cytotoxicity assays. An error-prone Fc library focusing on the hinge-CH2 region was constructed in CHO cells with a functional diversity of 7.5 × 106. Panels of novel Fc variants with enhanced affinity and selectivity for FcγRs were isolated. Particularly, clone 2a-10 (G236E/K288R/K290W/K320M) showed increased binding strength towards FcγRIIa-131R and 131H allotypes with kinetic dissociation constants (KD-K) of 140 nM and 220 nM, respectively, while reduced binding strength towards FcγRIIb compared to WT Fc; clone 2b-1 (K222I/V302E/L328F/K334E) had KD-K of 180 nM towards FcγRIIb; clone 3a-2 (P247L/K248E/K334I) exhibited KD-K of 190 nM and 100 nM towards FcγRIIIa-176F and 176 V allotypes, respectively, and improved potency of 2.0 ng/ml in ADCC assays. Key mutation hotspots were identified, including P247 for FcγRIIIa, K290 for FcγRIIa, and K334 for FcγRIIb bindings. Discovery of Fc variants with enhanced affinity and selectivity towards individual FcγR and the identification of novel mutation hotspots provide valuable insights for further Fc optimization and serve as a foundation for advancing antibody therapeutics development.

The aged tumor microenvironment limits T cell control of cancer

The etiology and effect of age-related immune dysfunction in cancer is not completely understood. Here we show that limited priming of CD8+ T cells in the aged tumor microenvironment (TME) outweighs cell-intrinsic defects in limiting tumor control. Increased tumor growth in aging is associated with reduced CD8+ T cell infiltration and function. Transfer of T cells from young mice does not restore tumor control in aged mice owing to rapid induction of T cell dysfunction. Cell-extrinsic signals in the aged TME drive a tumor-infiltrating age-associated dysfunctional (TTAD) cell state that is functionally, transcriptionally and epigenetically distinct from canonical T cell exhaustion. Altered natural killer cell-dendritic cell-CD8+ T cell cross-talk in aged tumors impairs T cell priming by conventional type 1 dendritic cells and promotes TTAD cell formation. Aged mice are thereby unable to benefit from therapeutic tumor vaccination. Critically, myeloid-targeted therapy to reinvigorate conventional type 1 dendritic cells can improve tumor control and restore CD8+ T cell immunity in aging.

Agonist Antibodies for Cancer Immunotherapy: History, Hopes, and Challenges

Immunotherapy is among the most promising new treatment modalities to arise over the last two decades; antibody drugs are delivering immunotherapy to millions of patients with many different types of cancer. Initial success with antibody therapeutics came in the form of direct targeting or cytotoxic antibodies, such as rituximab and trastuzumab, which bind directly to tumor cells to elicit their destruction. These were followed by immunomodulatory antibodies that elicit antitumor responses by either stimulating immune cells or relieving tumor-mediated suppression. By far the most successful approach in the clinic to date has been relieving immune suppression, with immune checkpoint blockade now a standard approach in the treatment of many cancer types. Despite equivalent and sometimes even more impressive effects in preclinical models, agonist antibodies designed to stimulate the immune system have lagged behind in their clinical translation. In this review, we document the main receptors that have been targeted by agonist antibodies, consider the various approaches that have been evaluated to date, detail what we have learned, and consider how their anticancer potential can be unlocked.

Next-generation CD40 agonists for cancer immunotherapy

INTRODUCTION

There is a need for new therapies that can enhance response rates and broaden the number of cancer indications where immunotherapies provide clinical benefit. CD40 targeting therapies provide an opportunity to meet this need by promoting priming of tumor-specific T cells and reverting the suppressive tumor microenvironment. This is supported by emerging clinical evidence demonstrating the benefits of immunotherapy with CD40 antibodies in combination with standard of care chemotherapy.

AREAS COVERED

This review is focused on the coming wave of next-generation CD40 agonists aiming to improve efficacy and safety, using new approaches and formats beyond monospecific antibodies. Further, the current understanding of the role of different CD40 expressing immune cell populations in the tumor microenvironment is reviewed.

EXPERT OPINION

There are multiple promising next-generation approaches beyond monospecific antibodies targeting CD40 in immuno-oncology. Enhancing efficacy is the most important driver for this development, and approaches that maximize the ability of CD40 to both remodel the tumor microenvironment and boost the anti-tumor T cell response provide great opportunities to benefit cancer patients. Enhanced understanding of the role of different CD40 expressing immune cells in the tumor microenvironment may facilitate more efficient clinical development of these compounds.

Fcγ-Receptor-Independent Controlled Activation of CD40 Canonical Signaling by Novel Therapeutic Antibodies for Cancer Therapy

The activation of CD40-mediated signaling in antigen-presenting cells is a promising therapeutic strategy to promote immune responses against tumors. Most agonistic anti-CD40 antibodies currently in development require the Fcγ-receptor (FcγR)-mediated crosslinking of CD40 molecules for a meaningful activation of CD40 signaling but have limitations due to dose-limiting toxicities. Here we describe the identification of CD40 antibodies which strongly stimulate antigen-presenting cells in an entirely FcγR-independent manner. These Fc-silenced anti-CD40 antibodies induce an efficient upregulation of costimulatory receptors and cytokine release by dendritic cells. Finally, the most active identified anti-CD40 antibody shows activity in humanized mice. More importantly, there are no signs of obvious toxicities. These studies thus demonstrate the potent activation of antigen-presenting cells with anti-CD40 antibodies lacking FcγR-binding activity and open the possibility for an efficacious and safe combination therapy for cancer patients.

Advances in tumor microenvironment and underlying molecular mechanisms of bladder cancer: a systematic review

Bladder cancer is one of the most frequent malignant tumors of the urinary system. The prevalence of bladder cancer among men and women is roughly 5:2, and both its incidence and death have been rising steadily over the past few years. At the moment, metastasis and recurrence of advanced bladder cancer-which are believed to be connected to the malfunction of multigene and multilevel cell signaling network-remain the leading causes of bladder cancer-related death. The therapeutic treatment of bladder cancer will be greatly aided by the elucidation of these mechanisms. New concepts for the treatment of bladder cancer have been made possible by the advancement of research technologies and a number of new treatment options, including immunotherapy and targeted therapy. In this paper, we will extensively review the development of the tumor microenvironment and the possible molecular mechanisms of bladder cancer.

Bispecific antibodies tethering innate receptors induce human tolerant-dendritic cells and regulatory T cells

There is an urgent need for alternative therapies targeting human dendritic cells (DCs) that could reverse inflammatory syndromes in many autoimmune and inflammatory diseases and organ transplantations. Here, we describe a bispecific antibody (bsAb) strategy tethering two pathogen-recognition receptors at the surface of human DCs. This cross-linking switches DCs into a tolerant profile able to induce regulatory T-cell differentiation. The bsAbs, not parental Abs, induced interleukin 10 and transforming growth factor β1 secretion in monocyte-derived DCs and human peripheral blood mononuclear cells. In addition, they induced interleukin 10 secretion by synovial fluid cells in rheumatoid arthritis and gout patients. This concept of bsAb-induced tethering of surface pathogen-recognition receptors switching cell properties opens a new therapeutic avenue for controlling inflammation and restoring immune tolerance.

A potential novel cancer immunotherapy: Agonistic anti-CD40 antibodies

CD40, a novel immunomodulatory cancer therapy target, is expressed by B cells, macrophages, and dendritic cells (DCs) and mediates cytotoxic T cell priming through the CD40 ligand. Some tumors show promising responses to monotherapy or combination therapy with agonistic anti-CD40 antibodies. The development of improved anti-CD40 antibodies makes CD40 activation an innovative strategy in cancer immunotherapy. In this review, we trace the history of CD40 research and summarize preclinical and clinical findings. We emphasize the ongoing development of improved anti-CD40 antibodies and explore strategies for effective combination therapies. Guided by predictive biomarkers, future research should identify patient populations benefiting the most from CD40 activation.

Harnessing the potential of CD40 agonism in cancer therapy

CD40 is a member of the tumor necrosis factor (TNF) receptor superfamily of receptors expressed on a variety of cell types. The CD40-CD40L interaction gives rise to many immune events, including the licensing of dendritic cells to activate CD8+ effector T cells, as well as the facilitation of B cell activation, proliferation, and differentiation. In malignant cells, the expression of CD40 varies among cancer types, mediating cellular proliferation, apoptosis, survival and the secretion of cytokines and chemokines. Agonistic human anti-CD40 antibodies are emerging as an option for cancer treatment, and early-phase clinical trials explored its monotherapy or combination with radiotherapy, chemotherapy, immune checkpoint blockade, and other immunomodulatory approaches. In this review, we present the current understanding of the mechanism of action for CD40, along with results from the clinical development of agonistic human CD40 antibodies in cancer treatment (selicrelumab, CDX-1140, APX005M, mitazalimab, 2141-V11, SEA-CD40, LVGN7409, and bispecific antibodies). This review also examines the safety profile of CD40 agonists in both preclinical and clinical settings, highlighting optimized dosage levels, potential adverse effects, and strategies to mitigate them.

Bispecific dendritic-T cell engager potentiates anti-tumor immunity

Immune checkpoint inhibition treatment using aPD-1 monoclonal antibodies is a promising cancer immunotherapy approach. However, its effect on tumor immunity is narrow, as most patients do not respond to the treatment or suffer from recurrence. We show that the crosstalk between conventional type I dendritic cells (cDC1) and T cells is essential for an effective aPD-1-mediated anti-tumor response. Accordingly, we developed a bispecific DC-T cell engager (BiCE), a reagent that facilitates physical interactions between PD-1+ T cells and cDC1. BiCE treatment promotes the formation of active dendritic/T cell crosstalk in the tumor and tumor-draining lymph nodes. In vivo, single-cell and physical interacting cell analysis demonstrates the distinct and superior immune reprogramming of the tumors and tumor-draining lymph nodes treated with BiCE as compared to conventional aPD-1 treatment. By bridging immune cells, BiCE potentiates cell circuits and communication pathways needed for effective anti-tumor immunity.

The antitumor activities of anti-CD47 antibodies require Fc-FcγR interactions

While anti-CD47 antibodies hold promise for cancer immunotherapy, early-phase clinical trials have shown limited clinical benefit, suggesting that CD47 blockade alone might be insufficient for effective tumor control. Here, we investigate the contributions of the Fc domain of anti-CD47 antibodies required for optimal in vivo antitumor activity across multiple species-matched models, providing insights into the mechanisms behind the efficacy of this emerging class of therapeutic antibodies. Using a mouse model humanized for CD47, SIRPα, and FcγRs, we demonstrate that local administration of Fc-engineered anti-CD47 antibodies with enhanced binding to activating FcγRs promotes tumor infiltration of macrophages and antigen-specific T cells, while depleting regulatory T cells. These effects result in improved long-term systemic antitumor immunity and minimal on-target off-tumor toxicity. Our results highlight the importance of Fc optimization in the development of effective anti-CD47 therapies and provide an attractive strategy to enhance the activity of this promising immunotherapy.

Conventional type 1 dendritic cells (cDC1) in cancer immunity

Cancer immunotherapy, alone or in combination with conventional therapies, has revolutionized the landscape of antineoplastic treatments, with dendritic cells (DC) emerging as key orchestrators of anti-tumor immune responses. Among the distinct DC subsets, conventional type 1 dendritic cells (cDC1) have gained prominence due to their unique ability to cross-present antigens and activate cytotoxic T lymphocytes. This review summarizes the distinctive characteristics of cDC1, their pivotal role in anticancer immunity, and the potential applications of cDC1-based strategies in immunotherapy.

Immune mechanisms and molecular therapeutic strategies to enhance immunotherapy in non-muscle invasive bladder cancer: Invited review for special issue "Seminar: Treatment Advances and Molecular Biology Insights in Urothelial Carcinoma"

Intravesical immunotherapy with Bacillus Calmette-Guérin (BCG) has been the standard of care for patients with high-risk non non-muscle invasive bladder cancer (NMIBC) for over four decades. Despite its success as a cancer immunotherapy, disease recurrence and progression remain common. Current efforts are focused on developing effective and well-tolerated alternatives to BCG and salvage bladder preservation therapies after BCG has failed. The focus of this review is to synthesize our current understanding of the molecular biology and tumor immune microenvironment of NMIBC to provide rationale for existing and emerging therapeutic targets. We highlight recent and ongoing clinical trials and define the current treatment landscape, challenges, and future directions of salvage treatment. Combination regimens that are rationally designed will be needed to make meaningful therapeutic advancements. Investigations into the molecular underpinnings of NMIBC are leading to the emergence of predictive molecular biomarkers that provide greater insight into the clinical heterogeneity of NMIBC and enable us to identify drivers of treatment resistance and new therapeutic targets.

IL-15 synergizes with CD40 agonist antibodies to induce durable immunity against bladder cancer

CD40 is a central costimulatory receptor implicated in productive antitumor immune responses across multiple cancers, including bladder cancer. Despite strong preclinical rationale, systemic administration of therapeutic agonistic antibodies targeting the CD40 pathway has demonstrated dose-limiting toxicities with minimal clinical activity, emphasizing an important need for optimized CD40-targeted approaches, including rational combination therapy strategies. Here, we describe a role for the endogenous IL-15 pathway in contributing to the therapeutic activity of CD40 agonism in orthotopic bladder tumors, with upregulation of transpresented IL-15/IL-15Rα surface complexes, particularly by cross-presenting conventional type 1 DCs (Dendritic Cells), and associated enrichment of activated CD8 T cells. In bladder cancer patient samples, we identify DCs as the primary source of IL-15, although they lack high levels of IL-15Rα at baseline. Using humanized immunocompetent orthotopic bladder tumor models, we demonstrate the ability to therapeutically augment this interaction through combined treatment with anti-CD40 agonist antibodies and exogenous IL-15, including the fully-human Fc-optimized antibody 2141-V11 currently in clinical development for the treatment of bladder cancer. Collectively, these data reveal an important role for IL-15 in mediating antitumor CD40 agonist responses in bladder cancer and provide key proof-of-concept for combined use of Fc-optimized anti-CD40 agonist antibodies and agents targeting the IL-15 pathway. These data support expansion of ongoing clinical studies evaluating anti-CD40 agonist antibodies and IL-15-based approaches to develop combinations of these promising therapeutics for the treatment of patients with bladder cancer.

Bacteria-based immunotherapy for cancer: a systematic review of preclinical studies

Immunotherapy has been emerging as a powerful strategy for cancer management. Recently, accumulating evidence has demonstrated that bacteria-based immunotherapy including naive bacteria, bacterial components, and bacterial derivatives, can modulate immune response via various cellular and molecular pathways. The key mechanisms of bacterial antitumor immunity include inducing immune cells to kill tumor cells directly or reverse the immunosuppressive microenvironment. Currently, bacterial antigens synthesized as vaccine candidates by bioengineering technology are novel antitumor immunotherapy. Especially the combination therapy of bacterial vaccine with conventional therapies may further achieve enhanced therapeutic benefits against cancers. However, the clinical translation of bacteria-based immunotherapy is limited for biosafety concerns and non-uniform production standards. In this review, we aim to summarize immunotherapy strategies based on advanced bacterial therapeutics and discuss their potential for cancer management, we will also propose approaches for optimizing bacteria-based immunotherapy for facilitating clinical translation.

Interventional hydrogel microsphere vaccine as an immune amplifier for activated antitumour immunity after ablation therapy

The response rate of pancreatic cancer to chemotherapy or immunotherapy pancreatic cancer is low. Although minimally invasive irreversible electroporation (IRE) ablation is a promising option for irresectable pancreatic cancers, the immunosuppressive tumour microenvironment that characterizes this tumour type enables tumour recurrence. Thus, strengthening endogenous adaptive antitumour immunity is critical for improving the outcome of ablation therapy and post-ablation immune therapy. Here we present a hydrogel microsphere vaccine that amplifies post-ablation anti-cancer immune response via releasing its cargo of FLT3L and CD40L at the relatively lower pH of the tumour bed. The vaccine facilitates migration of the tumour-resident type 1 conventional dendritic cells (cDC1) to the tumour-draining lymph nodes (TdLN), thus initiating the cDC1-mediated antigen cross-presentation cascade, resulting in enhanced endogenous CD8+ T cell response. We show in an orthotopic pancreatic cancer model in male mice that the hydrogel microsphere vaccine transforms the immunologically cold tumour microenvironment into hot in a safe and efficient manner, thus significantly increasing survival and inhibiting the growth of distant metastases.

Heterogeneity of CD40 Expression in Different Types of High-Risk Endometrial Cancer Affects Discordant Prognostic Outcomes

Background

The role of immune checkpoint inhibitors in endometrial cancer is limited. At present, the anti-programmed cell death protein 1 (anti-PD-1) antibody is only used in patients with recurrence or metastasis. CD40 is an important immune checkpoint, which is expressed in tumor cells and immune cells, but its distribution characteristics in endometrial carcinoma have not been explored.

Methods

Sixty-eight cases of primary endometrial carcinoma treated in Peking University People's Hospital from January 2010 to December 2020 were collected, including 28 cases of poorly differentiated endometrioid adenocarcinoma, 23 cases of serous carcinoma and 17 cases of clear cell carcinoma. The relationship of CD40 expression and PD-L1 expression with their prognosis was analyzed by immunohistochemistry.

Results

We found that CD40 had higher expression in non-endometrioid endometrial carcinoma, which lead to the worse prognosis. The effect of high expression of CD40 on the prognosis of endometrioid adenocarcinoma was not significantly different, and most patients with good prognosis. We found that the proportion of CD40 distribution in tumor cells and immune cells may be associated with this heterogeneity.

Conclusion

The expression of CD40 in different endometrial cancers may indicate the difference prognosis, which may become a potential target for drug treatment of non-endometrioid endometrial carcinoma.

The Antitumor Activities of Anti-CD47 Antibodies Require Fc-FcγR interactions

While anti-CD47 antibodies hold promise for cancer immunotherapy, early phase clinical trials have shown limited signs of clinical benefit, suggesting that blockade of CD47 alone may not be sufficient for effective tumor control. Here, we investigate the contributions of the Fc domain of anti-CD47 antibodies required for optimal in vivo antitumor activity across multiple species-matched models, providing new insights into the mechanisms underlying the efficacy of this emerging class of therapeutic antibodies. Using a novel mouse model humanized for CD47, SIRPα and FcγRs, we demonstrate that local administration of an Fc-engineered anti-CD47 antibody with enhanced binding to activating FcγRs modulates myeloid and T-cell subsets in the tumor microenvironment, resulting in improved long-term systemic antitumor immunity and minimal on-target off-tumor toxicity. Our results highlight the importance of Fc optimization in the development of effective anti-CD47 therapies and provide a novel approach for enhancing the antitumor activity of this promising immunotherapy.

Signaling pathways involved in the biological functions of dendritic cells and their implications for disease treatment

The ability of dendritic cells (DCs) to initiate and regulate adaptive immune responses is fundamental for maintaining immune homeostasis upon exposure to self or foreign antigens. The immune regulatory function of DCs is strictly controlled by their distribution as well as by cytokines, chemokines, and transcriptional programming. These factors work in conjunction to determine whether DCs exert an immunosuppressive or immune-activating function. Therefore, understanding the molecular signals involved in DC-dependent immunoregulation is crucial in providing insight into the generation of organismal immunity and revealing potential clinical applications of DCs. Considering the many breakthroughs in DC research in recent years, in this review we focused on three basic lines of research directly related to the biological functions of DCs and summarized new immunotherapeutic strategies involving DCs. First, we reviewed recent findings on DC subsets and identified lineage-restricted transcription factors that guide the development of different DC subsets. Second, we discussed the recognition and processing of antigens by DCs through pattern recognition receptors, endogenous/exogenous pathways, and the presentation of antigens through peptide/major histocompatibility complexes. Third, we reviewed how interactions between DCs and T cells coordinate immune homeostasis in vivo via multiple pathways. Finally, we summarized the application of DC-based immunotherapy for autoimmune diseases and tumors and highlighted potential research prospects for immunotherapy that targets DCs. This review provides a useful resource to better understand the immunomodulatory signals involved in different subsets of DCs and the manipulation of these immune signals can facilitate DC-based immunotherapy.

Non-Invasive Imaging Modalities in Intravesical Murine Models of Bladder Cancer

Bladder cancer (BCa) is the sixth most prevalent cancer in men and seventeenth most prevalent cancer in women worldwide. Current treatment paradigms have limited therapeutic impact, suggesting an urgent need for the investigation of novel therapies. To best emulate the progression of human BCa, a pre-clinical intravesical murine model is required in conjunction with existing non-invasive imaging modalities to detect and evaluate cancer progression. Non-invasive imaging modalities reduce the number of required experimental models while allowing for longitudinal studies of novel therapies to investigate long-term efficacy. In this review, we discuss the individual and multi-modal use of non-invasive imaging modalities; bioluminescence imaging (BLI), micro-ultrasound imaging (MUI), magnetic resonance imaging (MRI), and positron emission tomography (PET) in BCa evaluation. We also provide an update on the potential and the future directions of imaging modalities in relation to intravesical murine models of BCa.

Novel strategies for cancer immunotherapy: counter-immunoediting therapy

The advent of immunotherapy has made an indelible mark on the field of cancer therapy, especially the application of immune checkpoint inhibitors in clinical practice. Although immunotherapy has proven its efficacy and safety in some tumors, many patients still have innate or acquired resistance to immunotherapy. The emergence of this phenomenon is closely related to the highly heterogeneous immune microenvironment formed by tumor cells after undergoing cancer immunoediting. The process of cancer immunoediting refers to the cooperative interaction between tumor cells and the immune system that involves three phases: elimination, equilibrium, and escape. During these phases, conflicting interactions between the immune system and tumor cells result in the formation of a complex immune microenvironment, which contributes to the acquisition of different levels of immunotherapy resistance in tumor cells. In this review, we summarize the characteristics of different phases of cancer immunoediting and the corresponding therapeutic tools, and we propose normalized therapeutic strategies based on immunophenotyping. The process of cancer immunoediting is retrograded through targeted interventions in different phases of cancer immunoediting, making immunotherapy in the context of precision therapy the most promising therapy to cure cancer.

Long-Term Retention Microbubbles with Three-Layer Structure for Floating Intravesical Instillation Delivery

Intravesical instillation is an effective treatment for bladder cancer. However, clinical anticancer agents always suffer rapid excretion by periodic urination, leading to low therapeutic efficacy. Prolonging the retention time of drugs in the bladder is the key challenge for intravesical instillation treatment. Herein, a facile and powerful surface cross-linking-freeze drying strategy is proposed to generate ultra-stable albumin bovine air microbubbles (BSA-MBs) that can float and adhere to the bladder wall to overcome the excretion of urination and exhibit a remarkable property of long-term retention in the bladder. More noteworthy, BSA-MBs are endowed with a specific three-layer structure, namely, the outer membrane, middle drug loading layer and inner air core, which makes them have a low density to easily float and possess a high drug loading capacity. Based on their unique superiorities, the therapeutic potential of doxorubicin (DOX)-loaded BSA-MBs (DOX-MBs) is exemplified by intravesical instillation for bladder cancer. After injection into the bladder, DOX-MBs can remain in the bladder for a long time and sustain the release of DOX in urine, exhibiting potent anticancer efficacy. Consequently, the prolonged retention of BSA-MBs in the bladder renders them as an effective floating drug delivery system for intravesical instillation therapy.

Immunotoxin-αCD40 therapy activates innate and adaptive immunity and generates a durable antitumor response in glioblastoma models

D2C7-immunotoxin (IT), a dual-specific IT targeting wild-type epidermal growth factor receptor (EGFR) and mutant EGFR variant III (EGFRvIII) proteins, demonstrates encouraging survival outcomes in a subset of patients with glioblastoma. We hypothesized that immunosuppression in glioblastoma limits D2C7-IT efficacy. To improve the response rate and reverse immunosuppression, we combined D2C7-IT tumor cell killing with αCD40 costimulation of antigen-presenting cells. In murine glioma models, a single intratumoral injection of D2C7-IT+αCD40 treatment activated a proinflammatory phenotype in microglia and macrophages, promoted long-term tumor-specific CD8+ T cell immunity, and generated cures. D2C7-IT+αCD40 treatment increased intratumoral Slamf6+CD8+ T cells with a progenitor phenotype and decreased terminally exhausted CD8+ T cells. D2C7-IT+αCD40 treatment stimulated intratumoral CD8+ T cell proliferation and generated cures in glioma-bearing mice despite FTY720-induced peripheral T cell sequestration. Tumor transcriptome profiling established CD40 up-regulation, pattern recognition receptor, cell senescence, and immune response pathway activation as the drivers of D2C7-IT+αCD40 antitumor responses. To determine potential translation, immunohistochemistry staining confirmed CD40 expression in human GBM tissue sections. These promising preclinical data allowed us to initiate a phase 1 study with D2C7-IT+αhCD40 in patients with malignant glioma (NCT04547777) to further evaluate this treatment in humans.

IL-15 synergizes with CD40 agonist antibodies to induce durable immunity against bladder cancer

CD40 is a central co-stimulatory receptor implicated in the development of productive anti-tumor immune responses across multiple cancers, including bladder cancer. Despite strong preclinical rationale, systemic administration of therapeutic agonistic antibodies targeting the CD40 pathway have demonstrated dose limiting toxicities with minimal clinical activity to date, emphasizing an important need for optimized CD40-targeted approaches, including rational combination therapy strategies. Here, we describe an important role for the endogenous IL-15 pathway in contributing to the therapeutic activity of CD40 agonism in orthotopic bladder tumors, with upregulation of trans-presented IL-15/IL-15Rα surface complexes, particularly by cross-presenting cDC1s, and associated enrichment of activated CD8 T cells within the bladder tumor microenvironment. In bladder cancer patient samples, we identify DCs as the primary source of IL-15, however, they lack high levels of IL-15Rα at baseline. Using humanized immunocompetent orthotopic bladder tumor models, we demonstrate the ability to therapeutically augment this interaction through combined treatment with anti-CD40 agonist antibodies and exogenous IL-15, including the fully-human Fc-optimized antibody 2141-V11 currently in clinical development for the treatment of bladder cancer. Combination therapy enhances the crosstalk between Batf3-dependent cDC1s and CD8 T cells, driving robust primary anti-tumor activity and further stimulating long-term systemic anti-tumor memory responses associated with circulating memory-phenotype T and NK cell populations. Collectively, these data reveal an important role for IL-15 in mediating anti-tumor CD40 agonist responses in bladder cancer and provide key proof-of-concept for combined use of Fc-optimized anti-CD40 agonist antibodies and agents targeting the IL-15 pathway. These data support expansion of ongoing clinical studies evaluating anti-CD40 agonist antibodies and IL-15-based approaches to evaluate combinations of these promising therapeutics for the treatment of patients with bladder cancer.

Mature dendritic cells enriched in immunoregulatory molecules (mregDCs): A novel population in the tumour microenvironment and immunotherapy target

BACKGROUND

Dendritic cells (DCs) mediate divergent immune effects by activating T cells or negatively regulating the immune response to promote immune tolerance. They perform specific functions determined by their tissue distribution and maturation state. Traditionally, immature and semimature DCs were described to have immunosuppressive effects, leading to immune tolerance. Nonetheless, recent research has demonstrated that mature DCs can also suppress the immune response under certain circumstances.

MAIN BODY

Mature DCs enriched in immunoregulatory molecules (mregDCs) have emerged as a regulatory module across species and tumour types. Indeed, the distinct roles of mregDCs in tumour immunotherapy have sparked the interest of researchers in the field of single-cell omics. In particular, these regulatory cells were found to be associated with a positive response to immunotherapy and a favourable prognosis.

CONCLUSION

Here, we provide a general overview of the latest and most notable advances and recent findings regarding the basic features and complex roles of mregDCs in nonmalignant diseases and the tumour microenvironment. We also emphasise the important clinical implications of mregDCs in tumours.

Clinical value of M1 macrophage-related genes identification in bladder urothelial carcinoma and in vitro validation

Background: Tumor microenvironment (TME) takes a non-negligible role in the progression and metastasis of bladder urothelial carcinoma (BLCA) and tumor development could be inhibited by macrophage M1 in TME. The role of macrophage M1-related genes in BLCA adjuvant therapy has not been studied well. Methods: CIBERSOR algorithm was applied for identification tumor-infiltrating immune cells (TICs) subtypes of subjects from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) data sets. We identified potential modules of M1 macrophages by weighted gene co-expression network analysis (WGCNA). Nomogram was determined by one-way Cox regression and lasso regression analysis for M1 macrophage genes. The data from GEO are taken to verify the models externally. Kaplan-Meier and receiver operating characteristic (ROC) curves validated prognostic value of M1 macrophage genes. Finally, we divided patients into the low-risk group (LRG) and the high-risk group (HRG) based on the median risk score (RS), and the predictive value of RS in patients with BLCA immunotherapy and chemotherapy was investigated. Bladder cancer (T24, 5637, and BIU-87) and bladder uroepithelial cell line (SV-HUC-1) were used for in vitro validation. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was employed to validate the associated genes mRNA level. Results: 111 macrophage M1-related genes were identified using WGCNA. RS model containing three prognostically significant M1 macrophage-associated genes (FBXO6, OAS1, and TMEM229B) was formed by multiple Cox analysis, and a polygenic risk model and a comprehensive prognostic line plot was developed. The calibration curve clarified RS was a good predictor of prognosis. Patients in the LRG were more suitable for programmed cell death protein 1 (PD1) and cytotoxic T lymphocyte associate protein-4 (CTLA4) combination immunotherapy. Finally, chemotherapeutic drug models showed patients in the LRG were more sensitive to gemcitabine and mitomycin. RT-qPCR result elucidated the upregulation of FBXO6, TMEM229B, and downregulation of OAS1 in BLCA cell lines. Conclusion: A predictive model based on M1 macrophage-related genes can help guide us in the treatment of BLCA.

FcγRs and Their Relevance for the Activity of Anti-CD40 Antibodies

Inhibitory targeting of the CD40L-CD40 system is a promising therapeutic option in the field of organ transplantation and is also attractive in the treatment of autoimmune diseases. After early complex results with neutralizing CD40L antibodies, it turned out that lack of Fcγ receptor (FcγR)-binding is the crucial factor for the development of safe inhibitory antibodies targeting CD40L or CD40. Indeed, in recent years, blocking CD40 antibodies not interacting with FcγRs, has proven to be well tolerated in clinical studies and has shown initial clinical efficacy. Stimulation of CD40 is also of considerable therapeutic interest, especially in cancer immunotherapy. CD40 can be robustly activated by genetically engineered variants of soluble CD40L but also by anti-CD40 antibodies. However, the development of CD40L-based agonists is biotechnologically and pharmacokinetically challenging, and anti-CD40 antibodies typically display only strong agonism in complex with FcγRs or upon secondary crosslinking. The latter, however, typically results in poorly developable mixtures of molecule species of varying stoichiometry and FcγR-binding by anti-CD40 antibodies can elicit unwanted side effects such as antibody-dependent cellular cytotoxicity (ADCC) or antibody-dependent cellular phagocytosis (ADCP) of CD40 expressing immune cells. Here, we summarize and compare strategies to overcome the unwanted target cell-destroying activity of anti-CD40-FcγR complexes, especially the use of FcγR type-specific mutants and the FcγR-independent cell surface anchoring of bispecific anti-CD40 fusion proteins. Especially, we discuss the therapeutic potential of these strategies in view of the emerging evidence for the dose-limiting activities of systemic CD40 engagement.

Efficacy of CD40 Agonists Is Mediated by Distinct cDC Subsets and Subverted by Suppressive Macrophages

Agonistic αCD40 therapy has been shown to inhibit cancer progression in only a fraction of patients. Understanding the cancer cell-intrinsic and microenvironmental determinants of αCD40 therapy response is therefore crucial to identify responsive patient populations and to design efficient combinatorial treatments. Here, we show that the therapeutic efficacy of αCD40 in subcutaneous melanoma relies on preexisting, type 1 classical dendritic cell (cDC1)-primed CD8+ T cells. However, after administration of αCD40, cDC1s were dispensable for antitumor efficacy. Instead, the abundance of activated cDCs, potentially derived from cDC2 cells, increased and further activated antitumor CD8+ T cells. Hence, distinct cDC subsets contributed to the induction of αCD40 responses. In contrast, lung carcinomas, characterized by a high abundance of macrophages, were resistant to αCD40 therapy. Combining αCD40 therapy with macrophage depletion led to tumor growth inhibition only in the presence of strong neoantigens. Accordingly, treatment with immunogenic cell death-inducing chemotherapy sensitized lung tumors to αCD40 therapy in subcutaneous and orthotopic settings. These insights into the microenvironmental regulators of response to αCD40 suggest that different tumor types would benefit from different combinations of therapies to optimize the clinical application of CD40 agonists.

SIGNIFICANCE

This work highlights the temporal roles of different dendritic cell subsets in promoting CD8+ T-cell-driven responses to CD40 agonist therapy in cancer.

Next Generation CD40 Agonistic Antibodies for Cancer Immunotherapy

The clinical use of anti-CD40 agonist monoclonal antibodies (mAbs) is aimed at recruiting the immune system to fight the tumor cells. This approach has been demonstrated to be effective in various preclinical models. However, human CD40 Abs displayed only modest antitumor activity in cancer patients, characterized by low efficacy and dose-limiting toxicity. While recent studies highlight the importance of engineering the Fc region of human CD40 mAbs to optimize their agonistic potency, toxicity remains the main limiting factor, restricting clinical application to suboptimal doses. Here, we discuss the current challenges in realizing the full potential of CD40 mAbs in clinical practice, and describe novel approaches designed to circumvent the systemic toxicity associated with CD40 agonism.

Novel intravesical bacterial immunotherapy induces rejection of BCG-unresponsive established bladder tumors

Background

Intravesical BCG is the gold-standard therapy for non-muscle invasive bladder cancer (NMIBC); however, it still fails in a significant proportion of patients, so improved treatment options are urgently needed.

Methods

Here, we compared BCG antitumoral efficacy with another live attenuated mycobacteria, MTBVAC, in an orthotopic mouse model of bladder cancer (BC). We aimed to identify both bacterial and host immunological factors to understand the antitumoral mechanisms behind effective bacterial immunotherapy for BC.

Results

We found that the expression of the BCG-absent proteins ESAT6/CFP10 by MTBVAC was determinant in mediating bladder colonization by the bacteria, which correlated with augmented antitumoral efficacy. We further analyzed the mechanism of action of bacterial immunotherapy and found that it critically relied on the adaptive cytotoxic response. MTBVAC enhanced both tumor antigen-specific CD4⁺ and CD8⁺ T-cell responses, in a process dependent on stimulation of type 1 conventional dendritic cells. Importantly, improved intravesical bacterial immunotherapy using MBTVAC induced eradication of fully established bladder tumors, both as a monotherapy and specially in combination with the immune checkpoint inhibitor antiprogrammed cell death ligand 1 (anti PD-L1).

Conclusion

These results contribute to the understanding of the mechanisms behind successful bacterial immunotherapy against BC and characterize a novel therapeutic approach for BCG-unresponsive NMIBC cases.

A Polyvalent Peptide CD40 Nanoagonist for Targeted Modulation of Dendritic Cells and Amplified Cancer Immunotherapy

Targeted immunomodulation through biomolecule-based nanostructures, especially to dendritic cells (DCs), holds great promise for effective cancer therapy. However, construction of high-performance agonist by mimicking natural ligand to activate immune cell signaling is a great challenge so far. Here, a peptide-based nanoagonist toward CD40 (PVA-CD40) with preorganized interfacial topological structure that activates lymph node DCs efficiently and persistently, achieving amplified immune therapeutic efficacy is described. The on-site fabrication of PVA-CD40 is realized through the click conjugation of two functional peptides including the "CD40 anchoring arm" and the "assembly-driving motor." The resultant polyvalent interface rapidly triggers the receptor oligomerization and downstream signaling. Strikingly, one shot administration of PVA-CD40 elicits maturation period of DCs up to 2.3-fold comparing to that of CD40 antibody. Finally, combining the PVA-CD40 with anti-PD-1 antibody results in subsequent inhibition of tumor growth in both B16F10 and 4T1 mice tumor models with survival rate up to 37%, while none of the mice survives in the clinically relevant CD40 mAb and anti-PD-1 combination-treated group. It is envisioned that the fabrication of antibody-like superstructures in vivo provides an efficient platform for modulating the duration of immune response to achieve optimal therapeutic efficacy.

In Situ Constructed Nano-Drug Depots through Intracellular Hydrolytic Condensation for Chemotherapy of Bladder Cancer

Intravesical administration of first-line drugs has shown failure in the treatment of bladder cancer owing to the poor tumor retention time of chemotherapeutics. Herein, we report an intracellular hydrolytic condensation (IHC) system to construct long-term retentive nano-drug depots in situ, wherein sustained drug release results in highly efficient suppression of bladder cancer. Briefly, the designed doxorubicin (Dox)-silane conjugates self-assemble into silane-based prodrug nanoparticles, which condense into silicon particle-based nano-drug depots inside tumor cells. Significantly, we demonstrate that the IHC system possesses highly potent antitumor efficacy, which leads to the regression and eradication of large established tumors and simultaneously extends the overall survival of air pouch bladder cancer mice compared with that of mice treated with Dox. The concept of intracellular hydrolytic condensation can be extended via conjugating other chemotherapeutic drugs, which may facilitate rational design of novel nanomedicines for augmentation of chemotherapy.

Clinical relevance of tumour-associated macrophages

In the past decade, substantial advances have been made in understanding the biology of tumour-associated macrophages (TAMs), and their clinical relevance is emerging. A particular aspect that is becoming increasingly clear is that the interaction of TAMs with cancer cells and stromal cells in the tumour microenvironment enables and sustains most of the hallmarks of cancer. Therefore, manipulation of TAMs could enable improved disease control in a substantial fraction of patients across a large number of cancer types. In this Review, we examine the diversity of TAMs in various cancer indications and how this heterogeneity is being revisited with the advent of single-cell technologies, and then explore the current knowledge on the functional roles of different TAM states and the prognostic and predictive value of TAM-related signatures. We also review agents targeting TAMs that are currently being or will soon be tested in clinical trials, and how manipulations of TAMs can improve existing anticancer treatments. Finally, we discuss how TAM-targeting approaches could be further integrated into routine clinical practice, considering a precision oncology approach and viewing TAMs as a dynamic population that can evolve under treatment pressure.

A novel mouse strain optimized for chronic human antibody administration

Species differences in IgG Fc–Fcγ receptor (FcγR) interactions have made humanized mouse models an attractive strategy to evaluate the efficacy and toxicity of human antibodies. We previously published a humanized FcγR mouse model that fully recapitulates the expression and function of these receptors in vivo. However, the immunogenicity of exogenous human IgG has made long-term assessment of antibody function challenging, since endogenous mouse anti-human IgG responses limit the duration and success of these studies. Here, we present a mouse strain that expresses human IgG1 and FcγRs, thereby conferring tolerance to chronic administration of human IgG and enabling functional assessment of antibodies. Because this strain is appropriate for chronic disease models, we expect that researchers will benefit from its use.

Therapeutic human IgG antibodies are routinely tested in mouse models of oncologic, infectious, and autoimmune diseases. However, assessing the efficacy and safety of long-term administration of these agents has been limited by endogenous anti-human IgG immune responses that act to clear human IgG from serum and relevant tissues, thereby reducing their efficacy and contributing to immune complex–mediated pathologies, confounding evaluation of potential toxicity. For this reason, human antibody treatment in mice is generally limited in duration and dosing, thus failing to recapitulate the potential clinical applications of these therapeutics. Here, we report the development of a mouse model that is tolerant of chronic human antibody administration. This model combines both a human IgG1 heavy chain knock-in and a full recapitulation of human Fc receptor (FcγR) expression, providing a unique platform for in vivo testing of human monoclonal antibodies with relevant receptors beyond the short term. Compared to controls, hIgG1 knock-in mice mount minimal anti-human IgG responses, allowing for the persistence of therapeutically active circulating human IgG even in the late stages of treatment in chronic models of immune thrombocytopenic purpura and metastatic melanoma.

Strategy and clinical application of up-regulating cross presentation by DCs in anti-tumor therapy

The cross presentation of exogenous antigen (Ag) by dendritic cells (DCs) facilitates a diversified mode of T-cell activation, orchestrates specific humoral and cellular immunity, and contributes to an efficient anti-tumor immune response. DCs-mediated cross presentation is subject to both intrinsic and extrinsic factors, including the homing and phenotype of DCs, the spatiotemporal trafficking and degradation kinetics of Ag, and multiple microenvironmental clues, with many details largely unexplored. Here, we systemically review the current mechanistic understanding and regulation strategies of cross presentation by heterogeneous DC populations. We also provide insights into the future exploitation of DCs cross presentation for a better clinical efficacy in anti-tumor therapy.

Archetypes of checkpoint-responsive immunity

Responsiveness to immune checkpoint blockade (ICB) therapy in cancer is currently predicted by disparate individual measures - with varying degrees of accuracy - including tumor mutation burden, tumor-infiltrating T cell densities, dendritic cell frequencies, and the expression of checkpoint ligands. We propose that many of these individual parameters are linked, forming two distinct 'reactive' immune archetypes - collections of cells and gene expression - in ICB-responsive patients. We hypothesize that these are 'seeds' of antitumor immunity and are supported by specific elements of the tumor microenvironment (TME) and by actions of the microbiome. Although removing 'immunosuppressive' factors in the TME is important, understanding and parsing reactive immunity is crucial for optimal prognosis and for engaging this biology with candidate therapies to increase tumor cure rates.

Tumor-Associated Macrophages in Bladder Cancer: Biological Role, Impact on Therapeutic Response and Perspectives for Immunotherapy

Tumor-associated macrophages (TAMs) are one of the most abundant infiltrating immune cells of solid tumors. Despite their possible dual role, i.e., pro- or anti-tumoral, there is considerable evidence showing that the accumulation of TAMs promotes tumor progression rather than slowing it. Several strategies are being developed and clinically tested to target these cells. Bladder cancer (BCa) is one of the most common cancers, and despite heavy treatments, including immune checkpoint inhibitors (ICIs), the overall patient survival for advanced BCa is still poor. TAMs are present in bladder tumors and play a significant role in BCa development. However, few investigations have analyzed the effect of targeting TAMs in BCa. In this review, we focus on the importance of TAMs in a cancerous bladder, their association with patient outcome and treatment efficiency as well as on how current BCa treatments impact these cells. We also report different strategies used in other cancer types to develop new immunotherapeutic strategies with the aim of improving BCa management through TAMs targeting.