Overcoming primary and acquired resistance to anti-PD-L1 therapy by induction and activation of tumor-residing cDC1s

Novel insights into immune cells modulation of tumor resistance

Tumor resistance poses a significant challenge to effective cancer treatment, making it imperative to explore new therapeutic strategies. Recent studies have highlighted the profound involvement of immune cells in the development of tumor resistance. Within the tumor microenvironment, macrophages undergo polarization into the M2 phenotype, thus promoting the emergence of drug-resistant tumors. Neutrophils contribute to tumor resistance by forming extracellular traps. While T cells and natural killer (NK) cells exert their impact through direct cytotoxicity against tumor cells. Additionally, dendritic cells (DCs) have been implicated in preventing tumor drug resistance by stimulating T cell activation. In this review, we provide a comprehensive summary of the current knowledge regarding immune cell-mediated modulation of tumor resistance at the molecular level, with a particular focus on macrophages, neutrophils, DCs, T cells, and NK cells. The targeting of immune cell modulation exhibits considerable potential for addressing drug resistance, and an in-depth understanding of the molecular interactions between immune cells and tumor cells holds promise for the development of innovative therapies. Furthermore, we explore the clinical implications of these immune cells in the treatment of drug-resistant tumors. This review emphasizes the exploration of novel approaches that harness the functional capabilities of immune cells to effectively overcome drug-resistant tumors.

Antigen presenting cells in cancer immunity and mediation of immune checkpoint blockade

Antigen-presenting cells (APCs) are pivotal mediators of immune responses. Their role has increasingly been spotlighted in the realm of cancer immunology, particularly as our understanding of immunotherapy continues to evolve and improve. There is growing evidence that these cells play a non-trivial role in cancer immunity and have roles dependent on surface markers, growth factors, transcription factors, and their surrounding environment. The main dendritic cell (DC) subsets found in cancer are conventional DCs (cDC1 and cDC2), monocyte-derived DCs (moDC), plasmacytoid DCs (pDC), and mature and regulatory DCs (mregDC). The notable subsets of monocytes and macrophages include classical and non-classical monocytes, macrophages, which demonstrate a continuum from a pro-inflammatory (M1) phenotype to an anti-inflammatory (M2) phenotype, and tumor-associated macrophages (TAMs). Despite their classification in the same cell type, each subset may take on an immune-activating or immunosuppressive phenotype, shaped by factors in the tumor microenvironment (TME). In this review, we introduce the role of DCs, monocytes, and macrophages and recent studies investigating them in the cancer immunity context. Additionally, we review how certain characteristics such as abundance, surface markers, and indirect or direct signaling pathways of DCs and macrophages may influence tumor response to immune checkpoint blockade (ICB) therapy. We also highlight existing knowledge gaps regarding the precise contributions of different myeloid cell subsets in influencing the response to ICB therapy. These findings provide a summary of our current understanding of myeloid cells in mediating cancer immunity and ICB and offer insight into alternative or combination therapies that may enhance the success of ICB in cancers.

Membrane Fusion Liposomes Deliver Antifibrotic and Chemotherapeutic Drugs Sequentially to Enhance Tumor Treatment Efficacy by Reshaping Tumor Microenvironment

The intricate tumor microenvironment in triple-negative breast cancer (TNBC) hampers chemotherapy and immunotherapy efficacy due to dense extracellular matrix (ECM) by tumor-associated fibroblasts (TAFs). Nanoparticle-based therapies, especially "all-in-one" nanoparticles, have shown great potential in combined drug delivery strategies to reshape the tumor microenvironment and enhance therapeutic efficiency. However, these "all-in-one" nanoparticles suffer from limitations in targeting different target cells, uncontrollable dosing ratio, and disregarding the impact of delivery schedules. This study prepared cell membrane fusion liposomes (TAFsomes and CCMsomes) to load FDA-approved antifibrotic drug pirfenidone (PFD/TAFsomes) and antitumor drug doxorubicin (DOX/CCMsomes). These liposomes can specifically target TAFs cells and tumor cells, and combined administration can effectively inhibit TAFs activity, reshape the tumor microenvironment (TME), and significantly enhance the tumor chemotherapy efficacy. Combined drug delivery defeats "all-in-one" liposomes (DOX/PFD/Liposomes, DOX/PFD/TAFsomes, and DOX/PFD/CCMsomes) by flexibly adjusting the drug delivery ratio. Moreover, an asynchronous delivery strategy that optimizes the administration schedule not only further improves the therapeutic effect, but also amplifies the effectiveness of α-PD-L1 immunotherapy by modulating the tumor immune microenvironment. This delivery strategy provides a personalized treatment approach with clinical translation potential, providing new ideas for enhancing the therapeutic effect against solid tumors such as TNBC.

Mapping the genetic landscape establishing a tumor immune microenvironment favorable for anti-PD-1 response in mice and humans

Identifying host genetic factors modulating immune checkpoint inhibitor (ICI) efficacy has been experimentally challenging because of variations in both host and tumor genomes, differences in the microbiome, and patient life exposures. Utilizing the Collaborative Cross (CC) multi-parent mouse genetic resource population, we developed an approach that fixes the tumor genomic configuration while varying host genetics. With this approach, we discovered that response to anti-PD-1 (aPD1) immunotherapy was significantly heritable in four distinct murine tumor models (H2 between 0.18-0.40). For the MC38 colorectal carcinoma system (H2 = 0.40), we mapped four significant ICI response quantitative trait loci (QTL) localized to mouse chromosomes (mChr) 5, 9, 15 and 17, and identified significant epistatic interactions between specific QTL pairs. Differentially expressed genes within these QTL were highly enriched for immune genes and pathways mediating allograft rejection and graft vs host disease. Using a cross species analytical approach, we found a core network of 48 genes within the four QTLs that showed significant prognostic value for overall survival in aPD1 treated human cohorts that outperformed all other existing validated immunotherapy biomarkers, especially in human tumors of the previously defined immune subtype 4. Functional blockade of two top candidate immune targets within the 48 gene network, GM-CSF and high affinity IL-2/IL-15 signaling, completely abrogated the MC38 tumor transcriptional response to aPD1 therapy in vivo. Thus, we have established a powerful cross species in vivo platform capable of uncovering host genetic factors that establish the tumor immune microenvironment configuration propitious for ICI response.

Phase I Study of GS-3583, an FMS-like Tyrosine Kinase 3 Agonist Fc Fusion Protein, in Patients with Advanced Solid Tumors

PURPOSE

GS-3583, an FMS-like tyrosine kinase 3 (FLT3) agonist Fc fusion protein, expanded conventional dendritic cells (cDC) in the periphery of healthy volunteers, suggesting potential for GS-3583 to increase cDCs in the tumor microenvironment and promote T cell-mediated antitumor activity in cancer patients. This phase Ib open-label study assessed GS-3583 in adults with advanced solid tumors.

PATIENTS AND METHODS

Multiple escalating doses of GS-3583 (standard 3+3 design) were administered intravenously on days 1 and 15 of cycle 1 and day 1 of each subsequent 28-day cycle for up to 52 weeks. Dose-limiting toxicity (DLT) was evaluated during the first 28 days of GS-3583 at each dose level.

RESULTS

Thirteen participants enrolled in four dose-escalation cohorts, after which the study was terminated following safety review. Median (range) age was 71 (44-79), and 7 (54%) participants were male. There were no DLTs. Seven participants had grade ≥3 AEs; 2 participants had grade 5 AEs, including a second primary malignancy (acute myeloid leukemia) considered treatment-related. Dose-dependent increase in GS-3583 serum exposure was observed in the dose range of 2-20 mg with GS-3583 accumulation at higher dose levels. Expansions of cDCs occurred at all four doses with a dose-dependent trend in the durability of the cDC expansion.

CONCLUSIONS

GS-3583 was relatively well tolerated and induced dose-dependent expansion of cDCs in the periphery of patients with advanced solid tumors. However, development of a second primary malignancy provides a cautionary tale for the FLT3 agonist mechanism. See related commentary by Raeder and Drazer, p. 2857.

Generation, Transcriptomic States, and Clinical Relevance of CX3CR1+ CD8 T Cells in Melanoma

Recent progress in single-cell profiling technologies has revealed significant phenotypic and transcriptional heterogeneity in tumor-infiltrating CD8+ T cells. However, the transition between the different states of intratumoral antigen-specific CD8+ T cells remains elusive. Here, we sought to examine the generation, transcriptomic states, and the clinical relevance of melanoma-infiltrating CD8+ T cells expressing a chemokine receptor and T-cell differentiation marker, CX3C chemokine receptor 1 (CX3CR1). Analysis of single-cell datasets revealed distinct human melanoma-infiltrating CD8+ T-cell clusters expressing genes associated with effector T-cell function but with distinguishing expression of CX3CR1 or PDCD1. No obvious impact of CX3CR1 expression in melanoma on the response to immune checkpoint inhibitor therapy was observed while increased pretreatment and on-treatment frequency of a CD8+ T-cell cluster expressing high levels of exhaustion markers was associated with poor response to the treatment. Adoptively transferred antigen-specific CX3CR1- CD8+ T cells differentiated into the CX3CR1+ subset in mice treated with FTY720, which inhibits lymphocyte egress from secondary lymphoid tissues, suggesting the intratumoral generation of CX3CR1+ CD8+ T cells rather than their trafficking from secondary lymphoid organs. Furthermore, analysis of adoptively transferred antigen-specific CD8+ T cells, in which the Cx3cr1 gene was replaced with a marker gene confirmed that CX3CR1+ CD8+ T cells could directly differentiate from the intratumoral CX3CR1- subset. These findings highlight that tumor antigen-specific CX3CR1- CD8+ T cells can fully differentiate outside the secondary lymphoid organs and generate CX3CR1+ CD8+ T cells in the tumor microenvironment, which are distinct from CD8+ T cells that express markers of exhaustion.

SIGNIFICANCE

Intratumoral T cells are composed of heterogeneous subpopulations with various phenotypic and transcriptional states. This study illustrates the intratumoral generation of antigen-specific CX3CR1+ CD8+ T cells that exhibit distinct transcriptomic signatures and clinical relevance from CD8+ T cells expressing markers of exhaustion.

Mobilization and activation of tumor-infiltrating dendritic cells inhibits lymph node metastasis in intrahepatic cholangiocarcinoma

Lymph node metastasis (LNM) facilitates distant tumor colonization and leads to the high mortality in patients with intrahepatic cholangiocarcinoma (ICC). However, it remains elusive how ICC cells subvert immune surveillance within the primary tumor immune microenvironment (TIME) and subsequently metastasize to lymph nodes (LNs). In this study, scRNA-seq and bulk RNA-seq analyses identified decreased infiltration of dendritic cells (DCs) into primary tumor sites of ICC with LNM, which was further validated via dual-color immunofluorescence staining of 219 surgically resected ICC samples. Tumor-infiltrating DCs correlated with increased CD8+ T cell infiltration and better prognoses in ICC patients. Mechanistically, β-catenin-mediated CXCL12 suppression accounted for the impaired DC recruitment in ICC with LNM. Two mouse ICC cell lines MuCCA1 and mIC-23 cells were established from AKT/NICD or AKT/YAP-induced murine ICCs respectively and were utilized to construct the footpad tumor LNM model. We found that expansion and activation of conventional DCs (cDCs) by combined Flt3L and poly(I:C) (FL-pIC) therapy markedly suppressed the metastasis of mIC-23 cells to popliteal LNs. Moreover, β-catenin inhibition restored the defective DC infiltration into primary tumor sites and reduced the incidence of LNM in ICC. Collectively, our findings identify tumor cell intrinsic β-catenin activation as a key mechanism for subverting DC-mediated anti-tumor immunity in ICC with LNM. FL-pIC therapy or β-catenin inhibitor could merit exploration as a potential regimen for mitigating ICC cell metastasis to LNs and achieving effective tumor immune control.

Dendritic cell subsets and implications for cancer immunotherapy

Dendritic cells (DCs) play a central role in the orchestration of effective T cell responses against tumors. However, their functional behavior is context-dependent. DC type, transcriptional program, location, intratumoral factors, and inflammatory milieu all impact DCs with regard to promoting or inhibiting tumor immunity. The following review introduces important facets of DC function, and how subset and phenotype can affect the interplay of DCs with other factors in the tumor microenvironment. It will also discuss how current cancer treatment relies on DC function, and survey the myriad ways with which immune therapy can more directly harness DCs to enact antitumor cytotoxicity.

d-mannose targets PD-1 to lysosomal degradation and enhances T cell-mediated anti-tumor immunity

High expression of programmed cell death protein 1 (PD-1), a typical immune checkpoint, results in dysfunction of T cells in tumor microenvironment. Antibodies and inhibitors against PD-1 or its ligand (PD-L1) have been widely used in various malignant tumors. However, the mechanisms by which PD-1 is regulated are not fully understood. Here, we report a mechanism of PD-1 degradation triggered by d-mannose and the universality of this mechanism in anti-tumor immunity. We show that d-mannose inactivates GSK3β via promoting phosphorylation of GSK3β at Ser9, thereby leading to TFE3 translocation to nucleus and subsequent PD-1 proteolysis induced by enhanced lysosome biogenesis. Notably, combination of d-mannose and PD-1 blockade exhibits remarkable tumor growth suppression attributed to elevated cytotoxicity activity of T cells in vivo. Furthermore, d-mannose treatment dramatically improves the therapeutic efficacy of MEK inhibitor (MEKi) trametinib in vivo. Our findings unveil a universally unrecognized anti-tumor mechanism of d-mannose by destabilizing PD-1 and provide strategies to enhance the efficacy of both immune checkpoint blockade (ICB) and MEKi -based therapies.

A Minimal PBPK/PD Model with Expansion-Enhanced Target-Mediated Drug Disposition to Support a First-in-Human Clinical Study Design for a FLT3L-Fc Molecule

FLT3L-Fc is a half-life extended, effectorless Fc-fusion of the native human FLT3-ligand. In cynomolgus monkeys, treatment with FLT3L-Fc leads to a complex pharmacokinetic/pharmacodynamic (PK/PD) relationship, with observed nonlinear PK and expansion of different immune cell types across different dose levels. A minimal physiologically based PK/PD model with expansion-enhanced target-mediated drug disposition (TMDD) was developed to integrate the molecule's mechanism of action, as well as the complex preclinical and clinical PK/PD data, to support the preclinical-to-clinical translation of FLT3L-Fc. In addition to the preclinical PK data of FLT3L-Fc in cynomolgus monkeys, clinical PK and PD data from other FLT3-agonist molecules (GS-3583 and CDX-301) were used to inform the model and project the expansion profiles of conventional DC1s (cDC1s) and total DCs in peripheral blood. This work constitutes an essential part of our model-informed drug development (MIDD) strategy for clinical development of FLT3L-Fc by projecting PK/PD in healthy volunteers, determining the first-in-human (FIH) dose, and informing the efficacious dose in clinical settings. Model-generated results were incorporated in regulatory filings to support the rationale for the FIH dose selection.

Targeting Dendritic Cell Dysfunction to Circumvent Anti-PD1 Resistance in Head and Neck Cancer

PURPOSE

Neoadjuvant anti-PD1 (aPD1) therapies are being explored in surgically resectable head and neck squamous cell carcinoma (HNSCC). Encouraging responses have been observed, but further insights into the mechanisms underlying resistance and approaches to improve responses are needed.

EXPERIMENTAL DESIGN

We integrated data from syngeneic mouse oral carcinoma (MOC) models and neoadjuvant pembrolizumab HNSCC patient tumor RNA-sequencing data to explore the mechanism of aPD1 resistance. Tumors and tumor-draining lymph nodes (DLN) from MOC models were analyzed for antigen-specific priming. CCL5 expression was enforced in an aPD1-resistant model.

RESULTS

An aPD1-resistant mouse model showed poor priming in the tumor DLN due to type 1 conventional dendritic cell (cDC1) dysfunction, which correlated with exhausted and poorly responsive antigen-specific T cells. Tumor microenvironment analysis also showed decreased cDC1 in aPD1-resistant tumors compared with sensitive tumors. Following neoadjuvant aPD1 therapy, pathologic responses in patients also positively correlated with baseline transcriptomic cDC1 signatures. In an aPD1-resistant model, intratumoral cDC1 vaccine was sufficient to restore aPD1 response by enhancing T-cell infiltration and increasing antigen-specific responses with improved tumor control. Mechanistically, CCL5 expression significantly correlated with neoadjuvant aPD1 response and enforced expression of CCL5 in an aPD1-resistant model, enhanced cDC1 tumor infiltration, restored antigen-specific responses, and recovered sensitivity to aPD1 treatment.

CONCLUSIONS

These data highlight the contribution of tumor-infiltrating cDC1 in HNSCC aPD1 response and approaches to enhance cDC1 infiltration and function that may circumvent aPD1 resistance in patients with HNSCC.

Comprehensive pan-cancer analysis of YBX family reveals YBX2 as a potential biomarker in liver cancer

Background

The Y-box-binding proteins (YBX) act as a multifunctional role in tumor progression, metastasis, drug resistance by regulating the transcription and translation process. Nevertheless, their functions in a pan-cancer setting remain unclear.

Methods

This study examined the clinical features expression, prognostic value, mutations, along with methylation patterns of three genes from the YBX family (YBX1, YBX2, and YBX3) in 28 different types of cancer. Data used for analysis were obtained from Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) databases. A novel YBXs score was created using the ssGSEA algorithm for the single sample gene set enrichment analysis. Additionally, we explored the YBXs score's association with the tumor microenvironment (TME), response to various treatments, and drug resistance.

Results

Our analysis revealed that YBX family genes contribute to tumor progression and are indicative of prognosis in diverse cancer types. We determined that the YBXs score correlates significantly with numerous malignant pathways in pan-cancer. Moreover, this score is also linked with multiple immune-related characteristics. The YBXs score proved to be an effective predictor for the efficacy of a range of treatments in various cancers, particularly immunotherapy. To summarize, the involvement of YBX family genes is vital in pan-cancer and exhibits a significant association with TME. An elevated YBXs score indicates an immune-activated TME and responsiveness to diverse therapies, highlighting its potential as a biomarker in individuals with tumors. Finally, experimental validations were conducted to explore that YBX2 might be a potential biomarker in liver cancer.

Conclusion

The creation of YBXs score in our study offered new insights into further studies. Besides, YBX2 was found as a potential therapeutic target, significantly contributing to the improvement of HCC diagnosis and treatment strategies.

Dendritic cells as orchestrators of anticancer immunity and immunotherapy

Dendritic cells (DCs) are a heterogeneous group of antigen-presenting innate immune cells that regulate adaptive immunity, including against cancer. Therefore, understanding the precise activities of DCs in tumours and patients with cancer is important. The classification of DC subsets has historically been based on ontogeny; however, single-cell analyses are now additionally revealing a diversity of functional states of DCs in cancer. DCs can promote the activation of potent antitumour T cells and immune responses via numerous mechanisms, although they can also be hijacked by tumour-mediated factors to contribute to immune tolerance and cancer progression. Consequently, DC activities are often key determinants of the efficacy of immunotherapies, including immune-checkpoint inhibitors. Potentiating the antitumour functions of DCs or using them as tools to orchestrate short-term and long-term anticancer immunity has immense but as-yet underexploited therapeutic potential. In this Review, we outline the nature and emerging complexity of DC states as well as their functions in regulating adaptive immunity across different cancer types. We also describe how DCs are required for the success of current immunotherapies and explore the inherent potential of targeting DCs for cancer therapy. We focus on novel insights on DCs derived from patients with different cancers, single-cell studies of DCs and their relevance to therapeutic strategies.

Dendritic cell-targeted therapy expands CD8 T cell responses to bona-fide neoantigens in lung tumors

Cross-presentation by type 1 DCs (cDC1) is critical to induce and sustain antitumoral CD8 T cell responses to model antigens, in various tumor settings. However, the impact of cross-presenting cDC1 and the potential of DC-based therapies in tumors carrying varied levels of bona-fide neoantigens (neoAgs) remain unclear. Here we develop a hypermutated model of non-small cell lung cancer in female mice, encoding genuine MHC-I neoepitopes to study neoAgs-specific CD8 T cell responses in spontaneous settings and upon Flt3L + αCD40 (DC-therapy). We find that cDC1 are required to generate broad CD8 responses against a range of diverse neoAgs. DC-therapy promotes immunogenicity of weaker neoAgs and strongly inhibits the growth of high tumor-mutational burden (TMB) tumors. In contrast, low TMB tumors respond poorly to DC-therapy, generating mild CD8 T cell responses that are not sufficient to block progression. scRNA transcriptional analysis, immune profiling and functional assays unveil the changes induced by DC-therapy in lung tissues, which comprise accumulation of cDC1 with increased immunostimulatory properties and less exhausted effector CD8 T cells. We conclude that boosting cDC1 activity is critical to broaden the diversity of anti-tumoral CD8 T cell responses and to leverage neoAgs content for therapeutic advantage.

Gel-mediated recruitment of conventional type 1 dendritic cells potentiates the therapeutic effects of radiotherapy

The efficacy of radiotherapy has not yet achieved optimal results, partially due to insufficient priming and infiltration of effector immune cells within the tumor microenvironment (TME), which often exhibits suppressive phenotypes. In particular, the infiltration of X-C motif chemokine receptor 1 (XCR1)-expressing conventional type-1 dendritic cells (cDC1s), which are critical in priming CD8+ cytotoxic T cells, within the TME is noticeably restricted. Hence, we present a facile methodology for the efficient fabrication of a calcium phosphate hydrogel loaded with X-C motif chemokine ligand 1 (XCL1) to selectively recruit cDC1s. Manganese phosphate microparticles were also loaded into this hydrogel to reprogram the TME via cGAS-STING activation, thereby facilitating the priming of cDC1s propelled specific CD8+ T cells. They also polarize tumor-associated macrophages towards the M1 phenotype and reduce the proportion of regulatory cells, effectively reversing the immunosuppressive TME into an immune-active one. The yielded XCL1@CaMnP gel exhibits significant efficacy in enhancing the therapeutic outcomes of radiotherapy, particularly when concurrently administered with postoperative radiotherapy, resulting in an impressive 60 % complete response rate. Such XCL1@CaMnP gel, which recruits cDC1s to present tumor antigens generated in situ, holds great potential as a versatile platform for enhanced cancer treatment through modulating the immunosuppressive TME.

Nonclinical pharmacokinetics, pharmacodynamics and safety assessment of a FLT3L-Fc molecule for cancer immunotherapy

FLT3L-Fc is a cytokine-Fc fusion agonizing receptor-type tyrosine-protein kinase FLT3 (fms-related tyrosine kinase 3; CD135). FLT3 is expressed on dendritic cells (DCs) as well as myeloid and lymphoid progenitors. Nonclinical pharmacokinetics, pharmacodynamics and safety of FLT3L-Fc were investigated in rats and cynomolgus monkeys. FLT3L-Fc induced robust pharmacodynamic responses, evidenced by marked expansion of peripheral blood cDC1s, cDC2s, and pDCs (up to 301-fold in rats and 378-fold in monkeys), peaking at 8-10 days after the first dose. FLT3L-Fc was well tolerated with no adverse findings at doses up to 10 mg/kg administered intravenously twice three weeks apart. In both species, major clinical pathology findings consisted of expansion of white blood cell (WBC) populations including lymphocytes, monocytes, neutrophils, basophils, and large unstained cells, which were pronounced after the first dose. The WBC findings were associated microscopically with histiocytic and mononuclear cell infiltrates in multiple organs. Tissue immunohistochemistry in monkeys showed that the leukocyte infiltrates consisted of hematopoietic progenitor cells and histiocytes with a reactive morphology and were associated with a slight stimulation of regional T and B cell populations. Additional FLT3L-Fc-associated changes included decreases in red blood cell (RBC) mass, increases in RBC distribution width, variable changes in reticulocytes, and transient alterations in platelet counts (rats only). The RBC and WBC findings were associated microscopically with increased hematopoietic cellularity of the bone marrow in both species and increased splenic megakaryocytic extramedullary hematopoiesis in rats. The totality of nonclinical safety data support the clinical development of FLT3L-Fc.

Antigen cross-presentation by dendritic cells: A critical axis in cancer immunotherapy

Dendritic cells (DCs) are professional antigen-presenting cells that play a key role in shaping adaptive immunity. DCs have a unique ability to sample their environment, capture and process exogenous antigens into peptides that are then loaded onto major histocompatibility complex class I molecules for presentation to CD8+ T cells. This process, called cross-presentation, is essential for initiating and regulating CD8+ T cell responses against tumors and intracellular pathogens. In this review, we will discuss the role of DCs in cancer immunity, the molecular mechanisms underlying antigen cross-presentation by DCs, the immunosuppressive factors that limit the efficiency of this process in cancer, and approaches to overcome DC dysfunction and therapeutically promote antitumoral immunity.

Clinical and immunological relevance of SLAMF6 expression in the tumor microenvironment of breast cancer and melanoma

Compelling evidence shows that the frequency of T cells in the tumor microenvironment correlates with prognosis as well as response to immunotherapy. However, considerable heterogeneity exists within tumor-infiltrating T cells, and significance of their genomic and transcriptomic landscape on clinical outcomes remains to be elucidated. Signaling lymphocyte activation molecule 6 (SLAMF6) is expressed on intra-tumoral progenitor-exhausted T cells, which exhibit the capacity to proliferate, self-renew and produce terminally-exhausted T cells in pre-clinical models and patients. Here, we investigated the impact of SLAMF6 expression on prognosis in two immunologically different tumor types using publicly available databases. Our findings demonstrate that high SLAMF6 expression is associated with better prognosis, expression of TCF7 (encoding T-cell factor 1), and increased gene signatures associated with conventional type 1 dendritic cells and effector function of T cells in melanoma and breast cancer. Single-cell profiling of breast cancer tumor microenvironment reveals SLAMF6 expression overlaps CD8 T cells with a T-effector signature, which includes subsets expressing TCF7, memory and effector-related genes, analogous to progenitor-exhausted T cells. These findings illustrate the significance of SLAMF6 in the tumor as a marker for better effector responses, and provide insights into the predictive and prognostic determinants for cancer patients.

TG468: a text graph convolutional network for predicting clinical response to immune checkpoint inhibitor therapy

Enhancing cancer treatment efficacy remains a significant challenge in human health. Immunotherapy has witnessed considerable success in recent years as a treatment for tumors. However, due to the heterogeneity of diseases, only a fraction of patients exhibit a positive response to immune checkpoint inhibitor (ICI) therapy. Various single-gene-based biomarkers and tumor mutational burden (TMB) have been proposed for predicting clinical responses to ICI; however, their predictive ability is limited. We propose the utilization of the Text Graph Convolutional Network (GCN) method to comprehensively assess the impact of multiple genes, aiming to improve the predictive capability for ICI response. We developed TG468, a Text GCN model framing drug response prediction as a text classification task. By combining natural language processing (NLP) and graph neural network techniques, TG468 effectively handles sparse and high-dimensional exome sequencing data. As a result, TG468 can distinguish survival time for patients who received ICI therapy and outperforms single gene biomarkers, TMB and some classical machine learning models. Additionally, TG468's prediction results facilitate the identification of immune status differences among specific patient types in the Cancer Genome Atlas dataset, providing a rationale for the model's predictions. Our approach represents a pioneering use of a GCN model to analyze exome data in patients undergoing ICI therapy and offers inspiration for future research using NLP technology to analyze exome sequencing data.

Antagonism of regulatory ISGs enhances the anti-melanoma efficacy of STING agonists

Background

Stimulator of Interferon Genes (STING) is a dsDNA sensor that triggers type I inflammatory responses. Recent data from our group and others support the therapeutic efficacy of STING agonists applied intratumorally or systemically in a range of murine tumor models, with treatment benefits associated with tumor vascular normalization and improved immune cell recruitment and function within the tumor microenvironment (TME). However, such interventions are rarely curative and STING agonism coordinately upregulates expression of immunoregulatory interferon-stimulated genes (ISGs) including Arg2, Cox2, Isg15, Nos2, and Pdl1 that may limit treatment benefits. We hypothesized that combined treatment of melanoma-bearing mice with STING agonist ADU-S100 together with antagonists of regulatory ISGs would result in improved control of tumor growth vs. treatment with ADU-S100 alone.

Methods

Mice bearing either B16 (BRAFWTPTENWT) or BPR20 (BRAFV600EPTEN-/-) melanomas were treated with STING agonist ADU-S100 plus various inhibitors of ARG2, COX2, NOS2, PD-L1, or ISG15. Tumor growth control and changes in the TME were evaluated for combination treatment vs ADU-S100 monotherapy by tumor area measurements and flow cytometry/transcriptional profiling, respectively.

Results

In the B16 melanoma model, we noted improved antitumor efficacy only when ADU-S100 was combined with neutralizing/blocking antibodies against PD-L1 or ISG15, but not inhibitors of ARG2, COX2, or NOS2. Conversely, in the BPR20 melanoma model, improved tumor growth control vs. ADU-S100 monotherapy was only observed when combining ADU-S100 with ARG2i, COX2i, and NOS2i, but not anti-PD-L1 or anti-ISG15. Immune changes in the TME associated with improved treatment outcomes were subtle but included increases in proinflammatory innate immune cells and activated CD8+CD69+ T cells and varied between the two tumor models.

Conclusions

These data suggest contextual differences in the relative contributions of individual regulatory ISGs that serve to operationally limit the anti-tumor efficacy of STING agonists which should be considered in future design of novel combination protocols for optimal treatment benefit.

Eribulin promotes proliferation of CD8+ T cells and potentiates T cell-mediated anti-tumor activity against triple-negative breast cancer cells

PURPOSE

Chemotherapeutic agents exert immunomodulatory effects on triple-negative breast cancer (TNBC) cells and immune cells. Eribulin favorably affects the immunological status of patients with breast cancer. However, the effects of eribulin on the immune cells remain unexplored. The aim of this study was to investigate the effects of eribulin on immune cells.

METHODS

Peripheral blood mononuclear cells (PBMCs) from healthy donors and mouse splenocytes were stimulated with anti-CD3 and anti-CD28 antibodies. The effects of eribulin and paclitaxel on cell proliferation and differentiation status were analyzed using flow cytometry. RNA sequencing was performed to assess alterations in gene expression in CD8+ T cells following eribulin and paclitaxel treatment. Using TNBC cell lines (MDA-MB-231, Hs578T, and MDA-MB-157), the anti-tumor activity of CD3/CD28-stimulated T cells combined with eribulin or paclitaxel was evaluated.

RESULTS

Eribulin did not affect CD3/CD28-stimulated PBMCs proliferation. However, eribulin significantly decreased the CD4/CD8 ratio in T cells, indicating that eribulin facilitates CD8+ T cell proliferation. Furthermore, eribulin significantly increased the frequency of less differentiated CD45RA+, CCR7+, and TCF1+ subsets of CD8+ T cells. RNA sequencing revealed that eribulin enhanced the expression of gene sets related to cell proliferation and immune responses. Moreover, eribulin augmented the anti-tumor effects of CD3/CD28-stimulated T cells against TNBC cells. These results were not observed in experiments using paclitaxel.

CONCLUSIONS

Eribulin promoted CD8+ T cell proliferation, repressed effector T cell differentiation, and harnessed T cell-mediated anti-tumor effects. These mechanisms may be one of the cues that eribulin can improve the immunological status of tumor-bearing hosts.

PD-1 and PD-L1: architects of immune symphony and immunotherapy breakthroughs in cancer treatment

PD-1 (Programmed Cell Death Protein-1) and PD-L1 (Programmed Cell Death Ligand-1) play a crucial role in regulating the immune system and preventing autoimmunity. Cancer cells can manipulate this system, allowing them to escape immune detection and promote tumor growth. Therapies targeting the PD-1/PD-L1 pathway have transformed cancer treatment and have demonstrated significant effectiveness against various cancer types. This study delves into the structure and signaling dynamics of PD-1 and its ligands PD-L1/PD-L2, the diverse PD-1/PD-L1 inhibitors and their efficacy, and the resistance observed in some patients. Furthermore, this study explored the challenges associated with the PD-1/PD-L1 inhibitor treatment approach. Recent advancements in the combination of immunotherapy with chemotherapy, radiation, and surgical procedures to enhance patient outcomes have also been highlighted. Overall, this study offers an in-depth overview of the significance of PD-1/PD-L1 in cancer immunotherapy and its future implications in oncology.

OMIP-095: 40-Color spectral flow cytometry delineates all major leukocyte populations in murine lymphoid tissues

High-dimensional immunoprofiling is essential for studying host response to immunotherapy, infection, and disease in murine model systems. However, the difficulty of multiparameter panel design combined with a lack of existing murine tools has prevented the comprehensive study of all major leukocyte phenotypes in a single assay. Herein, we present a 40-color flow cytometry panel for deep immunophenotyping of murine lymphoid tissues, including the spleen, blood, Peyer's patches, inguinal lymph nodes, bone marrow, and thymus. This panel uses a robust set of surface markers capable of differentiating leukocyte subsets without the use of intracellular staining, thus allowing for the use of cells in downstream functional experiments or multiomic analyses. Our panel classifies T cells, B cells, natural killer cells, innate lymphoid cells, monocytes, macrophages, dendritic cells, basophils, neutrophils, eosinophils, progenitors, and their functional subsets by using a series of co-stimulatory, checkpoint, activation, migration, and maturation markers. This tool has a multitude of systems immunology applications ranging from serial monitoring of circulating blood signatures to complex endpoint analysis, especially in pre-clinical settings where treatments can modulate leukocyte abundance and/or function. Ultimately, this 40-color panel resolves a diverse array of immune cells on the axes of time, tissue, and treatment, filling the niche for a modern tool dedicated to murine immunophenotyping.

Antigen-loaded Monocyte Administration and Flt3 Ligand Augment the Antitumor Efficacy of Immune Checkpoint Blockade in a Murine Melanoma Model

Undifferentiated monocytes can be loaded with tumor antigens (Ag) and administered intravenously to induce antitumor cytotoxic T lymphocyte (CTL) responses. This vaccination strategy exploits an endogenous Ag cross-presentation pathway, where Ag-loaded monocytes (monocyte vaccines) transfer their Ag to resident splenic dendritic cells (DC), which then stimulate robust CD8 + CTL responses. In this study, we investigated whether monocyte vaccination in combination with CDX-301, a DC-expanding cytokine Fms-like tyrosine kinase 3 ligand (Flt3L), could improve the antitumor efficacy of anti-programmed cell death (anti-PD-1) immune checkpoint blockade. We found that Flt3L expanded splenic DC over 40-fold in vivo and doubled the number of circulating Ag-specific T cells when administered before monocyte vaccination in C57BL/6 mice. In addition, OVA-monocyte vaccination combined with either anti-PD-1, anti-programmed cell death ligand 1 (anti-PD-L1), or anti-cytotoxic T lymphocyte antigen-4 (anti-CTLA-4) suppressed subcutaneous B16/F10-OVA tumor growth to a greater extent than checkpoint blockade alone. When administered together, OVA-monocyte vaccination improved the antitumor efficacy of Flt3L and anti-PD-1 in terms of circulating Ag-specific CD8 + T cell frequency and inhibition of subcutaneous B16/F10-OVA tumor growth. To our knowledge, this is the first demonstration that a cancer vaccine strategy and Flt3L can improve the antitumor efficacy of anti-PD-1. The findings presented here warrant further study of how monocyte vaccines can improve Flt3L and immune checkpoint blockade as they enter clinical trials.

Targeting innate immune pathways for cancer immunotherapy

The innate immune system is critical for inducing durable and protective T cell responses to infection and has been increasingly recognized as a target for cancer immunotherapy. In this review, we present a framework wherein distinct innate immune signaling pathways activate five key dendritic cell activities that are important for T cell-mediated immunity. We discuss molecular pathways that can agonize these activities and highlight that no single pathway can agonize all activities needed for durable immunity. The immunological distinctions between innate immunotherapy administration to the tumor microenvironment versus administration via vaccination are examined, with particular focus on the strategies that enhance dendritic cell migration, interferon expression, and interleukin-1 family cytokine production. In this context, we argue for the importance of appreciating necessity vs. sufficiency when considering the impact of innate immune signaling in inflammation and protective immunity and offer a conceptual guideline for the development of efficacious cancer immunotherapies.

LncTUG1 promotes hepatocellular carcinoma immune evasion via upregulating PD-L1 expression

HCC is one of the most common malignant tumors worldwide. Although traditional treatment methods have been improved in recent years, the survival rate of HCC patients has not been significantly improved. Immunotherapy has shown extremely high clinical value in a variety of tumors. In this study, we found that TUG1 could regulate the expression of PD-L1 through JAK2/STAT3 to mediate immunosuppression. Here, The expression of TUG1 and PD-L1 in HCC tissues was evaluated through analysis of databases and verified in HCC tissue and HCC cancer cells by qRT-PCR. The effect of TUG1 on tumor immune escape was detected by coculture, and cell viability was detected with a CCK8 assay. The results demonstrated that TUG1 was closely associated with anticancer immunity. TUG1 and PD-L1 were highly expressed in HCC tissues and HCC cancer cells, and high expression of TUG1 and PD-L1 was related to the poor prognosis of HCC patients. In addition, knocking down TUG1 expression could reduce PD-L1 expression and enhance the cancer cell-killing capability of T cells. Downregulating TUG1 expression could also decrease the mRNA and protein expression of JAK2 and STAT3. To sum up, TUG1 and PD-L1 are overexpressed in patients with liver cancer and are related to the poor prognosis of these patients. Silencing TUG1 expression reduced the mRNA and protein expression of PD-L1 by affecting the JAK2/STAT3 pathway.

NSUN2 is a glucose sensor suppressing cGAS/STING to maintain tumorigenesis and immunotherapy resistance

Glucose metabolism is known to orchestrate oncogenesis. Whether glucose serves as a signaling molecule directly regulating oncoprotein activity for tumorigenesis remains elusive. Here, we report that glucose is a cofactor binding to methyltransferase NSUN2 at amino acid 1-28 to promote NSUN2 oligomerization and activation. NSUN2 activation maintains global m5C RNA methylation, including TREX2, and stabilizes TREX2 to restrict cytosolic dsDNA accumulation and cGAS/STING activation for promoting tumorigenesis and anti-PD-L1 immunotherapy resistance. An NSUN2 mutant defective in glucose binding or disrupting glucose/NSUN2 interaction abolishes NSUN2 activity and TREX2 induction leading to cGAS/STING activation for oncogenic suppression. Strikingly, genetic deletion of the glucose/NSUN2/TREX2 axis suppresses tumorigenesis and overcomes anti-PD-L1 immunotherapy resistance in those cold tumors through cGAS/STING activation to facilitate apoptosis and CD8+ T cell infiltration. Our study identifies NSUN2 as a direct glucose sensor whose activation by glucose drives tumorigenesis and immunotherapy resistance by maintaining TREX2 expression for cGAS/STING inactivation.

Targeting the pericyte antigen DLK1 with an alpha type-1 polarized dendritic cell vaccine results in tumor vascular modulation and protection against colon cancer progression

Despite the availability of various treatment options, colorectal cancer (CRC) remains a significant contributor to cancer-related mortality. Current standard-of-care interventions, including surgery, chemotherapy, and targeted agents like immune checkpoint blockade and anti-angiogenic therapies, have improved short-term patient outcomes depending on disease stage, but survival rates with metastasis remain low. A promising strategy to enhance the clinical experience with CRC involves the use of dendritic cell (DC) vaccines that incite immunity against tumor-derived blood vessels, which are necessary for CRC growth and progression. In this report, we target tumor-derived pericytes expressing DLK1 with a clinically-relevant alpha type-1 polarized DC vaccine (αDC1) in a syngeneic mouse model of colorectal cancer. Our pre-clinical data demonstrate the αDC1 vaccine's ability to induce anti-tumor effects by facilitating cytotoxic T lymphocyte activity and ablating the tumor vasculature. This work, overall, provides a foundation to further interrogate immune-mediated mechanisms of protection in order to help devise efficacious αDC1-based strategies for patients with CRC.

A target map of clinical combination therapies in oncology: an analysis of clinicaltrials.gov

Combination therapies have taken center stage for cancer treatment, however, there is a lack of a comprehensive portrait to quantitatively map the current clinical combination progress. This study aims to capture clinical combination therapies of the validated FDA-approved new oncology drugs by a macro data analysis and to summarize combination mechanisms and strategies in the context of the existing literature. A total of 72 new molecular entities or new therapeutic biological products for cancer treatment approved by the FDA from 2017 to 2021 were identified, and the data on their related 3334 trials were retrieved from the database of ClinicalTrials.gov. Moreover, these sampled clinical trials were refined by activity status and combination relevance and labeled with the relevant clinical arms and drug combinations, as well as drug targets and target pairs. Combination therapies are increasingly prevalent in clinical trials of new oncology drugs. From retrospective work, existing clinical combination therapies in oncology are driven by different patterns (i.e., rational design and industry trends). The former can be represented by mechanism-based or structure-based combinations, such as targeting different domains of HER2 protein or in-series co-targeting in RAF plus MEK inhibitors. The latter is an empirically driven strategy, including redundant combinations in hot targets, such as PD-1/PD-L1, PI3K, CDK4/6, and PARP. Because of an explosion in the number of clinical trials and the resultant shortage of available patients, it is essential to rationally design drug combinations.

Insight into Cancer Immunity: MHCs, Immune Cells and Commensal Microbiota

Cancer cells circumvent immune surveillance via diverse strategies. In accordance, a large number of complex studies of the immune system focusing on tumor cell recognition have revealed new insights and strategies developed, largely through major histocompatibility complexes (MHCs). As one of them, tumor-specific MHC-II expression (tsMHC-II) can facilitate immune surveillance to detect tumor antigens, and thereby has been used in immunotherapy, including superior cancer prognosis, clinical sensitivity to immune checkpoint inhibition (ICI) therapy and tumor-bearing rejection in mice. NK cells play a unique role in enhancing innate immune responses, accounting for part of the response including immunosurveillance and immunoregulation. NK cells are also capable of initiating the response of the adaptive immune system to cancer immunotherapy independent of cytotoxic T cells, clearly demonstrating a link between NK cell function and the efficacy of cancer immunotherapies. Eosinophils were shown to feature pleiotropic activities against a variety of solid tumor types, including direct interactions with tumor cells, and accessorily affect immunotherapeutic response through intricating cross-talk with lymphocytes. Additionally, microbial sequencing and reconstitution revealed that commensal microbiota might be involved in the modulation of cancer progression, including positive and negative regulatory bacteria. They may play functional roles in not only mucosal modulation, but also systemic immune responses. Here, we present a panorama of the cancer immune network mediated by MHCI/II molecules, immune cells and commensal microbiota and a discussion of prospective relevant intervening mechanisms involved in cancer immunotherapies.

The impact of hypoxia on tumor-mediated bypassing anti-PD-(L)1 therapy

Extending the durability of response is the current focus in cancer immunotherapy with immune checkpoint inhibitors (ICIs). However, factors like non-immunogenic tumor microenvironment (TME) along with aberrant angiogenesis and dysregulated metabolic systems are negative contributors. Hypoxia is a key TME condition and a critical promoter of tumor hallmarks. It acts on immune and non-immune cells within TME in order for promoting immune evasion and therapy resistance. Extreme hypoxia is a major promoter of resistance to the programmed death-1 (PD-1)/programmed death-ligand 1 (PD-L1) inhibitor therapy. Hypoxia inducible factor-1 (HIF-1) acts as a key mediator of hypoxia and a critical promoter of resistance to the anti-PD-(L)1. Targeting hypoxia or HIF-1 can thus be an effective strategy for reinvigoration of cellular immunity against cancer. Among various strategies presented so far, the key focus is over vascular normalization, which is an approach highly effective for reducing the rate of hypoxia, increasing drug delivery into the tumor area, and boosting the efficacy of anti-PD-(L)1.

Association between CD8+ tumor-infiltrating lymphocytes and prognosis of non-small cell lung cancer patients treated with PD-1/PD-L1 inhibitors: a systematic review and meta-analysis

BACKGROUND

A meta-analysis method was used to investigate the prognostic value of CD8+ tumor-infiltrating lymphocytes (TILs) in non-small cell lung cancer (NSCLC) patients treated with PD-1/PD-L1 inhibitors.

METHODS

A database search of PubMed, Embase, Web of Science and Cochrane Library up until February 7th, 2023. A clinical study on the relationship between CD8+ TILs and PD-1/PD-L1 inhibitors in the therapeutics of NSCLC. RevMan 5.3 and StataMP 17.0 software were used for meta-analysis. The outcome indicators incorporated overall survival (OS), progression-free survival (PFS) and objective response rate (ORR).

RESULTS

Nineteen articles with 1488 patients were included. The analysis results showed that high CD8+ TILs were associated with better OS (HR=0.60, 95% CI: 0.46-0.77; P<0.0001), PFS (HR=0.68, 95% CI: 0.53-0.88; P=0.003) and ORR (OR=2.26, 95% CI: 1.52-3.36; P<0.0001) in NSCLC patients treated with PD-1/PD-L1 inhibitors. Subgroup analysis indicated that patients with high CD8+ TILs had good clinical prognostic benefits whether the location of CD8+ TILs was intratumoral or stromal, and compared with East Asian, high CD8+ TILs in Caucasians showed a better prognosis. High CD8+ TILs in peripheral blood did not improve OS (HR=0.83, 95% CI: 0.69-1.01; P=0.06) and PFS (HR=0.93, 95% CI: 0.61-1.14; P=0.76) in NSCLC patients receiving PD-1/PD-L1 inhibitors.

CONCLUSION

In spite of the location of CD8+ TILs, high densities of CD8+ TILs were predictive of treatment outcomes in NSCLC patients treated with PD-1/PD-L1 inhibitors. However, high CD8+ TILs in peripheral blood had no predictive effect.

Dendritic Cell Subsets in Melanoma: Pathophysiology, Clinical Prognosis and Therapeutic Exploitation

Evasion from immunity is a hallmark of cancer development. Dendritic cells (DCs) are strategic immune cells shaping anti-tumor immune responses, but tumor cells exploit DC versatility to subvert their functions. Unveiling the puzzling role of DCs in the control of tumor development and mechanisms of tumor-induced DC hijacking is critical to optimize current therapies and to design future efficient immunotherapies for melanoma. Dendritic cells, crucially positioned at the center of anti-tumor immunity, represent attractive targets to develop new therapeutic approaches. Harnessing the potencies of each DC subset to trigger appropriate immune responses while avoiding their subversion is a challenging yet promising step to achieve tumor immune control. This review focuses on advances regarding the diversity of DC subsets, their pathophysiology and impact on clinical outcome in melanoma patients. We provide insights into the regulation mechanisms of DCs by the tumor, and overview DC-based therapeutic developments for melanoma. Further insights into DCs' diversity, features, networking, regulation and shaping by the tumor microenvironment will allow designing novel effective cancer therapies. The DCs deserve to be positioned in the current melanoma immunotherapeutic landscape. Recent discoveries strongly motivate exploitation of the exceptional potential of DCs to drive robust anti-tumor immunity, offering promising tracks for clinical successes.

Predictive and Prognostic Implications of Circulating CX3CR1+ CD8+ T Cells in Non-Small Cell Lung Cancer Patients Treated with Chemo-Immunotherapy

Lack of reliable predictive biomarkers is a major limitation of combination therapy with chemotherapy and anti-programmed cell death protein 1/programmed death-ligand 1 (anti-PD-1/PD-L1) therapy (chemo-immunotherapy). We previously observed that the increase of peripheral blood CD8+ T cells expressing CX3CR1, a marker of differentiation, correlates with response to anti-PD-1 therapy; however, the predictive and prognostic value of T-cell CX3CR1 expression during chemo-immunotherapy is unknown. Here, we evaluated the utility of circulating CX3CR1+CD8+ T cells as a predictive correlate of response to chemo-immunotherapy in patients with non-small cell lung cancer (NSCLC). At least 10% increase of the CX3CR1+ subset in circulating CD8+ T cells from baseline (CX3CR1 score) was associated with response to chemo-immunotherapy as early as 4 weeks with 85.7% overall accuracy of predicting response at 6 weeks. Furthermore, at least 10% increase of the CX3CR1 score correlated with substantially better progression-free (P = 0.0051) and overall survival (P = 0.0138) on Kaplan-Meier analysis. Combined single-cell RNA/T-cell receptor (TCR) sequencing of circulating T cells from longitudinally obtained blood samples and TCR sequencing of tumor tissue from the same patient who received a long-term benefit from the treatment demonstrated remarkable changes in genomic and transcriptomic signatures of T cells as well as evolution of TCR clonotypes in peripheral blood containing highly frequent tumor-infiltrating lymphocyte repertoires overexpressing CX3CR1 early after initiation of the treatment despite stable findings of the imaging study. Collectively, these findings highlight the potential utility of T-cell CX3CR1 expression as a dynamic blood-based biomarker during the early course of chemo-immunotherapy and a marker to identify frequent circulating tumor-infiltrating lymphocyte repertoires.

Significance

Current approaches to combined chemotherapy and anti-PD-1/PD-L1 therapy (chemo-immunotherapy) for patients with NSCLC are limited by the lack of reliable predictive biomarkers. This study shows the utility of T-cell differentiation marker, CX3CR1, as an early on-treatment predictor of response and changes in genomic/transcriptomic signatures of circulating tumor-infiltrating lymphocyte repertoires in patients with NSCLC undergoing chemo-immunotherapy.

XCR1+ DCs are critical for T cell-mediated immunotherapy of chronic viral infections

The contribution of cross-presenting XCR1+ dendritic cells (DCs) and SIRPα+ DCs in maintaining T cell function during exhaustion and immunotherapeutic interventions of chronic infections remains poorly characterized. Using the mouse model of chronic LCMV infection, we found that XCR1+ DCs are more resistant to infection and highly activated compared with SIRPα+ DCs. Exploiting XCR1+ DCs via Flt3L-mediated expansion or XCR1-targeted vaccination notably reinvigorates CD8+ T cells and improves virus control. Upon PD-L1 blockade, XCR1+ DCs are not required for the proliferative burst of progenitor exhausted CD8+ T (TPEX) cells but are indispensable to sustain the functionality of exhausted CD8+ T (TEX) cells. Combining anti-PD-L1 therapy with increased frequency of XCR1+ DCs improves functionality of TPEX and TEX subsets, while increase of SIRPα+ DCs dampened their proliferation. Together, this demonstrates that XCR1+ DCs are crucial for the success of checkpoint inhibitor-based therapies through differential activation of exhausted CD8+ T cell subsets.

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.

Engineered Lactococcus lactis secreting Flt3L and OX40 ligand for in situ vaccination-based cancer immunotherapy

In situ vaccination is a promising strategy to convert the immunosuppressive tumor microenvironment into an immunostimulatory one with limited systemic exposure and side effect. However, sustained clinical benefits require long-term and multidimensional immune activation including innate and adaptive immunity. Here, we develop a probiotic food-grade Lactococcus lactis-based in situ vaccination (FOLactis) expressing a fusion protein of Fms-like tyrosine kinase 3 ligand and co-stimulator OX40 ligand. Intratumoural delivery of FOLactis contributes to local retention and sustained release of therapeutics to thoroughly modulate key components of the antitumour immune response, such as activation of natural killer cells, cytotoxic T lymphocytes, and conventional-type-1-dendritic cells in the tumors and tumor-draining lymph nodes. In addition, intratumoural administration of FOLactis induces a more robust tumor antigen-specific immune response and superior systemic antitumour efficacy in multiple poorly immune cell-infiltrated and anti-PD1-resistant tumors. Specific depletion of different immune cells reveals that CD8⁺ T and natural killer cells are crucial to the in situ vaccine-elicited tumor regression. Our results confirm that FOLactis displays an enhanced antitumour immunity and successfully converts the 'cold' tumors to 'hot' tumors.

In situ vaccination with cowpea mosaic virus elicits systemic antitumor immunity and potentiates immune checkpoint blockade

BACKGROUND

In situ vaccination (ISV) is a cancer immunotherapy strategy in which immunostimulatory reagents are introduced directly into a tumor to stimulate antitumor immunity both against the treated tumor and systemically against untreated tumors. Recently, we showed that cowpea mosaic virus (CPMV) is a potent multi-toll-like receptor (TLR) agonist with potent efficacy for treating tumors in mice and dogs by ISV. However, ISV with CPMV alone does not uniformly treat all mouse tumor models tested, however this can be overcome through strategic combinations. More insight is needed to delineate potency and mechanism of systemic antitumor immunity and abscopal effect.

METHOD

We investigated the systemic efficacy (abscopal effect) of CPMV ISV with a two-tumor mouse model using murine tumor lines B16F10, 4T1, CT26 and MC38. Flow cytometry identified changes in cell populations responsible for systemic efficacy of CPMV. Transgenic knockout mice and depleting antibodies validated the role of relevant candidate cell populations and cytokines. We evaluated these findings and engineered a multicomponent combination therapy to specifically target the candidate cell population and investigated its systemic efficacy, acquired resistance and immunological memory in mouse models.

RESULTS

ISV with CPMV induces systemic antitumor T-cell-mediated immunity that inhibits growth of untreated tumors and requires conventional type-1 dendritic cells (cDC1s). Furthermore, using multiple tumor mouse models resistant to anti-programmed death 1 (PD-1) therapy, we tested the hypothesis that CPMV along with local activation of antigen-presenting cells with agonistic anti-CD40 can synergize and strengthen antitumor efficacy. Indeed, this combination ISV strategy induces an influx of CD8+ T cells, triggers regression in both treated local and untreated distant tumors and potentiates tumor responses to anti-PD-1 therapy. Moreover, serial ISV overcomes resistance to anti-PD-1 therapy and establishes tumor-specific immunological memory.

CONCLUSIONS

These findings provide new insights into in situ TLR activation and cDC1 recruitment as effective strategies to overcome resistance to immunotherapy in treated and untreated tumors.

Astragalus polysaccharide (APS) attenuated PD-L1-mediated immunosuppression via the miR-133a-3p/MSN axis in HCC

CONTEXT

Astragalus polysaccharide (APS) is a new tumour therapeutic drug, that has an inhibitory effect on a variety of solid tumours. Tumour cell immunosuppression is related to the up-regulation of programmed death ligand 1 (PD-L1). However, whether APS exerts its antitumor effect by regulating PD-L1 remains unclear.

OBJECTIVE

To explore whether APS exerts its antineoplastic effect via regulating PD-L1-mediated immunosuppression in hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

SMMC-7721 cells were subcutaneous injected into BALB/C mice for HCC model establishment. Mice were intraperitoneally injected with 100, 200 and 400 mg/kg APS for 12 days. Immunohistochemistry (IHC) was performed to assess CD8⁺ T cells' rate and PD-L1 level in HCC tissues. HCC cells were pre-treated with 0.1, 0.5 and 1 mg/mL APS for 4 h, then were treated with 10 ng/mL IFN-γ 24 h. PD-L1 level and cell apoptosis was detected by flow cytometry. PD-L1 and Moesin (MSN) proteins were measured by western blot. MiR-133a-3p and MSN mRNA levels were assessed by qRT-PCR. The targets of miR-133a-3p were predicted by starBase, and which was verified by dual-luciferase reporter assay.

RESULTS

Our findings illustrated that APS dose-dependently inhibited HCC growth tested with IC₅₀ values of 4.2 mg/mL, and IFN-γ-induced PD-L1 expression and attenuated PD-L1-mediated immunosuppression in HCC cells. APS attenuated PD-L1-mediated immunosuppression via miR-133a-3p in HCC cells. Besides, miR-133a-3p targeted to MSN, and MSN inhibited the antitumor effect of APS by maintaining the stability of PD-L1. Moreover, APS attenuated PD-L1-mediated immunosuppression via the miR-133a-3p/MSN axis.

CONCLUSIONS

APS attenuated PD-L1-mediated immunosuppression via miR-133a-3p/MSN axis to develop an antitumor effect. APS may be an effective drug for HCC treatment.

A photodynamically sensitized dendritic cell vaccine that promotes the anti-tumor effects of anti-PD-L1 monoclonal antibody in a murine model of head and neck squamous cell carcinoma

BACKGROUND

Immune checkpoint inhibitors are promising tools in combating several cancers, including head and neck squamous cell carcinoma (HNSCC). However, a substantial portion of HNSCC patients do not respond to PD-L1 antibody. Here we describe a photodynamic therapeutic (PDT) approach to enhance anti-tumor effects of the anti-PD-L1 antibody.

METHODS

Phototoxicity of PDT was confirmed using fluorescence microscopy, Cell Counting Kit-8 (CCK-8), Enzyme Linked Immunosorbent Assay (ELISA) and flow cytometry analyses. Phenotypic and functional maturation of immature DCs (imDCs) induced by PDT were measured using flow cytometry and ELISA. A mouse model was established using the HNSCC line, SCC7, and was used to evaluate therapeutic effects of PDT-DC vaccine in facilitating anti-tumor immunity of PD-L1 antibody.

RESULTS

Immunogenic cell death (ICD) of SCC7 cells was induced by PDT with 0.5 µM of m-THPC and the 5 J/cm² of light dose. ICD of SCC7 cells stimulated imDCs maturation. In vivo assays suggested that PDT-DC vaccine and anti-PD-L1 mAb synergistically induced anti-tumor immunity and suppressed tumor progression.

CONCLUSION

PDT-DC vaccine enhances therapeutic effects of PD-L1 antibody, which might provide a novel approach for HNSCC immunotherapy.

Localized ablative immunotherapy drives de novo CD8+ T-cell responses to poorly immunogenic tumors

BACKGROUND

Localized ablative immunotherapies hold great promise in stimulating antitumor immunity to treat metastatic and poorly immunogenic tumors. Tumor ablation is well known to release tumor antigens and danger-associated molecular patterns to stimulate T-cell immunity, but its immune stimulating effect is limited, particularly against metastatic tumors.

METHODS

In this study, we combined photothermal therapy with a potent immune stimulant, N-dihydrogalactochitosan, to create a local ablative immunotherapy which we refer to as laser immunotherapy (LIT). Mice bearing B16-F10 tumors were treated with LIT when the tumors reached 0.5 cm3 and were monitored for survival, T-cell activation, and the ability to resist tumor rechallenge.

RESULTS

We found that LIT stimulated a stronger and more consistent antitumor T-cell response to the immunologically 'cold' B16-F10 melanoma tumors and conferred a long-term antitumor memory on tumor rechallenge. Furthermore, we discovered that LIT generated de novo CD8+ T-cell responses that strongly correlated with animal survival and tumor rejection.

CONCLUSION

In summary, our findings demonstrate that LIT enhances the activation of T cells and drives de novo antitumor T-cell responses. The data presented herein suggests that localized ablative immunotherapies have great potential to synergize with immune checkpoint therapies to enhance its efficacy, resulting in improved antitumor immunity.

Restoration of p53 activity via intracellular protein delivery sensitizes triple negative breast cancer to anti-PD-1 immunotherapy

Background

Although immune checkpoint inhibitors (ICIs) have been shown to yield promising therapeutic outcomes in a small subset of patients with triple negative breast cancer (TNBC), the majority of patients either do not respond or subsequently develop resistance. Recent studies have revealed the critical role of TP53 gene in cancer immunology. Loss or mutation of p53 in cancer cells has been found to promote their immune escape. Given the high mutation frequency of TP53 in TNBC cells, restoration of p53 function could be a potential strategy to overcome their resistance to anti-programmed cell death protein 1 (PD-1)/programmed cell death ligand 1 (PD-L1) therapy. Herein, we have assessed the use of Pos3Aa crystal-based platform to mediate the intracellular delivery of p53 protein to restore p53 activity in p53 null tumors and consequently augment anti-PD-1 activity.

Methods

The efficiency of Pos3Aa-p53 crystals in delivering p53 protein was evaluated using confocal imaging, immunofluorescence staining, flow cytometry and RNA-seq. The ability of Pos3Aa-p53 crystals to remodel tumor microenvironment was investigated by examining the markers of immunogenic cell death (ICD) and the expression of PD-L1, indoleamine 2,3-dioxygenase 1, tryptophan 2,3-dioxygenase 2 and type I interferon (IFN). Finally, both unilateral and bilateral 4T1 tumor mouse models were utilized to assess the efficacy of Pos3Aa-p53 crystal-mediated p53 restoration in enhancing the antitumor activity of ICIs. T cells in tumor tissues and spleens were analyzed, and the in vivo biosafety of the Pos3Aa-p53 crystal/anti-PD-1 antibody combination was also evaluated.

Results

Delivery of p53 protein into p53-null TNBC 4T1 cells via Pos3Aa-p53 crystals restored the p53 activity, and therefore led to the induction of ICD, activation of type I IFN signaling and upregulation of PD-L1 expression. Pos3Aa-p53 crystals significantly enhanced T cell infiltration and activation in 4T1 tumors, thereby sensitizing them to anti-PD-1 therapy. The combination of Pos3Aa-p53 crystals with anti-PD-1 antibody also induced a systemic antitumor immunity resulting in the inhibition of distal tumor growth with minimal toxicity.

Conclusion

This study validates that p53 restoration can be an effective approach to overcome ICI resistance and demonstrates that intracellular delivery of p53 protein can be an efficient, safe and potentially universal strategy to restore p53 activity in tumors carrying TP53 mutation.

Combination immunotherapy for pancreatic cancer: challenges and future considerations

INTRODUCTION

: Immune checkpoint inhibitors (ICI) have not yielded significant efficacy in pancreatic ductal adenocarcinoma (PDA), despite the role of the innate and adaptive immune systems on progression and survival. However, recently identified pathways have identified new targets and generated promising clinical investigations into promoting an effective immune-mediated antitumor response in PDA.

AREAS COVERED

: We review biological mechanisms associated with immunotherapy resistance and outline strategies for therapeutic combinations with established and novel therapies in PDA.

EXPERT OPINION

: Pancreatic cancers rarely benefits from treatment with ICI due to an immunosuppressive tumor microenvironment (TME). New understandings of factors associated with the suppressive TME, include low and poor quality neoantigens, constrained effector T cells infiltration, and the presence of a dense, suppressive myeloid cell population. These findings have been translated into new clinical investigations evaluating novel therapies in combination with ICI and/or standard systemic chemotherapy and radiotherapy. The epithelial, immune, and stromal compartments are intricately related in PDA, and the framework for successful targeting of this disease requires a comprehensive and personalized approach.

Emerging strategies in targeting tumor-resident myeloid cells for cancer immunotherapy

Immune checkpoint inhibitors targeting programmed cell death protein 1, programmed death-ligand 1, and cytotoxic T-lymphocyte-associated protein 4 provide deep and durable treatment responses which have revolutionized oncology. However, despite over 40% of cancer patients being eligible to receive immunotherapy, only 12% of patients gain benefit. A key to understanding what differentiates treatment response from non-response is better defining the role of the innate immune system in anti-tumor immunity and immune tolerance. Teleologically, myeloid cells, including macrophages, dendritic cells, monocytes, and neutrophils, initiate a response to invading pathogens and tissue repair after pathogen clearance is successfully accomplished. However, in the tumor microenvironment (TME), these innate cells are hijacked by the tumor cells and are imprinted to furthering tumor propagation and dissemination. Major advancements have been made in the field, especially related to the heterogeneity of myeloid cells and their function in the TME at the single cell level, a topic that has been highlighted by several recent international meetings including the 2021 China Cancer Immunotherapy workshop in Beijing. Here, we provide an up-to-date summary of the mechanisms by which major myeloid cells in the TME facilitate immunosuppression, enable tumor growth, foster tumor plasticity, and confer therapeutic resistance. We discuss ongoing strategies targeting the myeloid compartment in the preclinical and clinical settings which include: (1) altering myeloid cell composition within the TME; (2) functional blockade of immune-suppressive myeloid cells; (3) reprogramming myeloid cells to acquire pro-inflammatory properties; (4) modulating myeloid cells via cytokines; (5) myeloid cell therapies; and (6) emerging targets such as Siglec-15, TREM2, MARCO, LILRB2, and CLEVER-1. There is a significant promise that myeloid cell-based immunotherapy will help advance immuno-oncology in years to come.

Live Biotherapeutic Lactococcus lactis GEN3013 Enhances Antitumor Efficacy of Cancer Treatment via Modulation of Cancer Progression and Immune System

Simple Summary

Recent studies, which have revealed the strong relationship between gut microbiota and tumor progression, have driven the clinical application of microbiome-based treatments to increase the efficacy of anticancer therapies. In particular, the genome-editing Lactococcus lactis, which activates the host immune system by expressing immune-boosting cytokines or metabolites, is a candidate for microbiome treatment. While Lactococcus lactis has so far been studied in terms of its recombinant forms, we investigated the anticancer effects of the strain-specific Lactococcus lactis GEN3013 itself. In vitro cytotoxicity tests showed that L. lactis GEN3013 inhibited the cell growth of various human and murine cancer cell lines. Consistent with the in vitro results, L. lactis GEN3013 showed antitumor effects and enhanced the therapeutic efficacy of both chemotherapy and immunotherapy in syngeneic mice. In addition, the host immune system was activated both locally and systemically by the combinatorial treatment of L. lactis GEN3013 with chemotherapy and immunotherapy. For these reasons, we suggest that L. lactis GEN3013 could be utilized as a novel biotherapeutic agent for cancer treatment.

Abstract

The gut microbiota is responsible for differential anticancer drug efficacies by modulating the host immune system and the tumor microenvironment. Interestingly, this differential effect is highly strain-specific. For example, certain strains can directly suppress tumor growth and enhance antitumor immunity; however, others do not have such an effect or even promote tumor growth. Identifying effective strains that possess antitumor effects is key for developing live biotherapeutic anticancer products. Here, we found that Lactococcus lactis GEN3013 inhibits tumor growth by regulating tumor angiogenesis and directly inducing cancer cell death. Moreover, L. lactis GEN3013 enhanced the therapeutic effects of oxaliplatin and the PD-1 blockade. Comprehensive immune profiling showed that L. lactis GEN3013 augmented cytotoxic immune cell populations, such as CD4⁺ T cells, CD8⁺ effector T cells, and NK cells in the tumor microenvironment. Our results indicate that L. lactis GEN3013 is a promising candidate for potentiating cancer treatment in combination with current standard therapy.

Stromal remodeling regulates dendritic cell abundance and activity in the tumor microenvironment

Stimulatory type 1 conventional dendritic cells (cDC1s) engage in productive interactions with CD8⁺ effectors along tumor-stroma boundaries. The paradoxical accumulation of “poised” cDC1s within stromal sheets is unlikely to simply reflect passive exclusion from tumor cores. Drawing parallels with embryonic morphogenesis, we hypothesized that invasive margin stromal remodeling generates developmentally conserved cell fate cues that regulate cDC1 behavior. We find that, in human T cell-inflamed tumors, CD8⁺ T cells penetrate tumor nests, whereas cDC1s are confined within adjacent stroma that recurrently displays site-specific proteolysis of the matrix proteoglycan versican (VCAN), an essential organ-sculpting modification in development. VCAN is necessary, and its proteolytic fragment (matrikine) versikine is sufficient for cDC1 accumulation. Versikine does not influence tumor-seeding pre-DC differentiation; rather, it orchestrates a distinctive cDC1 activation program conferring exquisite sensitivity to DNA sensing, supported by atypical innate lymphoid cells. Thus, peritumoral stroma mimicking embryonic provisional matrix remodeling regulates cDC1 abundance and activity to elicit T cell-inflamed tumor microenvironments.

T cell-inflamed tumor microenvironments are a prerequisite for immunotherapy efficacy; however, why some tumors are inflamed and others not remains poorly understood. Papadas et al. link stromal reaction dynamics with T cell-induced inflammation. Peritumoral stroma emulating embryonic provisional matrix remodeling regulates cDC1-NK-CD8⁺ crosstalk to promote T cell repriming and penetration into tumor nests.

Tumor-targeted interleukin-12 synergizes with entinostat to overcome PD-1/PD-L1 blockade-resistant tumors harboring MHC-I and APM deficiencies

Background

Immune checkpoint blockade (ICB) has achieved unprecedented success in treating multiple cancer types. However, clinical benefit remains modest for most patients with solid malignancies due to primary or acquired resistance. Tumor-intrinsic loss of major histocompatibility complex class I (MHC-I) and aberrations in antigen processing machinery (APM) and interferon gamma (IFN-γ) pathways have been shown to play an important role in ICB resistance. While a plethora of combination treatments are being investigated to overcome ICB resistance, there are few identified preclinical models of solid tumors harboring these deficiencies to explore therapeutic interventions that can bypass ICB resistance. Here, we investigated the combination of the epigenetic modulator entinostat and the tumor-targeted immunocytokine NHS-IL12 in three different murine tumor models resistant to αPD-1/αPD-L1 (anti-programmed cell death protein 1/anti-programmed death ligand 1) and harboring MHC-I, APM, and IFN-γ response deficiencies and differing tumor mutational burden (TMB).

Methods

Entinostat and NHS-IL12 were administered to mice bearing TC-1/a9 (lung, HPV16 E6/E7⁺), CMT.64 lung, or RVP3 sarcoma tumors. Antitumor efficacy and survival were monitored. Comprehensive tumor microenvironment (TME) and spleen analysis of immune cells, cytokines, and chemokines was performed. Additionally, whole transcriptomic analysis was carried out on TC-1/a9 tumors. Cancer Genome Atlas (TCGA) datasets were analyzed for translational relevance.

Results

We demonstrate that the combination of entinostat and NHS-IL12 therapy elicits potent antitumor activity and survival benefit through prolonged activation and tumor infiltration of cytotoxic CD8⁺ T cells, across αPD-1/αPD-L1 refractory tumors irrespective of TMB, including in the IFN-γ signaling-impaired RVP3 tumor model. The combination therapy promoted M1-like macrophages and activated antigen-presenting cells while decreasing M2-like macrophages and regulatory T cells in a tumor-dependent manner. This was associated with increased levels of IFN-γ, IL-12, chemokine (C-X-C motif) ligand 9 (CXCL9), and CXCL13 in the TME. Further, the combination therapy synergized to promote MHC-I and APM upregulation, and enrichment of JAK/STAT (janus kinase/signal transducers and activators of transcription), IFN-γ-response and antigen processing-associated pathways. A biomarker signature of the mechanism involved in these studies is associated with patients’ overall survival across multiple tumor types.

Conclusions

Our findings provide a rationale for combining the tumor-targeting NHS-IL12 with the histone deacetylase inhibitor entinostat in the clinical setting for patients unresponsive to αPD-1/αPD-L1 and/or with innate deficiencies in tumor MHC-I, APM expression, and IFN-γ signaling.

The paradox of radiation and T cells in tumors

In this review we consider what appears to be a paradox in immunotherapies based around radiation therapy. The paradox is based on three main points. 1. That T cells are needed for radiation's efficacy; 2. That tumor-specific T cells are enriched in the field of treatment; and 3. That radiation kills T cells in the treatment field. We discuss evidence of the effect of radiation on T cells in the field given their ongoing movement in and out of tissues and the tumor, and how the movement of T cells impacts the treated primary tumor and untreated distant metastases. Given this evidence, we revisit the paradox to understand how the extraordinary efficacy of radiation and immunity in preclinical models is dependent on this radiation sensitive cell.