B7-H1 maintains the polyclonal T cell response by protecting dendritic cells from cytotoxic T lymphocyte destruction

Therapeutic vaccine targeting dual immune checkpoints induces potent multifunctional CD8+ T cell anti-tumor immunity

BACKGROUND

Vaccines targeting immune checkpoints represent a promising immunotherapeutic approach for solid tumors. However, the therapeutic efficacy of dual targeting immune checkpoints is still unclear in renal carcinoma.

METHODS

An adenovirus (Ad) vaccine targeting B7H1 and B7H3 was developed and evaluated for its therapeutic efficacy in subcutaneous, lung metastasis or orthotopic renal carcinoma mouse and humanized models using flow cytometry, Enzyme-linked immunosorbent spot (ELISPOT), cytotoxic T lymphocyte (CTL) killing, cell deletion, hematoxylin and eosin (HE) staining, and immunohistochemistry (IHC) assays.

RESULTS

The Ad-B7H1/B7H3 immunization effectively inhibited tumor growth and increased the induction and percentages of CD8+ T cells in subcutaneous tumor models. The vaccine enhanced the induction and maturation of CD11c+ or CD8+CD11c+ cells, promoting tumor-specific CD8+ T cell immune responses. This was evidenced by increased proliferation of CD8+ T cells and enhanced CTL killing activity. Deletion of CD8+ T cells in vivo abolished the anti-tumor effect of the Ad-B7H1/B7H3 vaccine, highlighting the pivotal role of functional CD8+ T cell immune responses. Moreover, significant therapeutic efficacy of the Ad-B7H1/B7H3 vaccine was observed in lung metastasis, orthotopic, and humanized tumor models through multifunctional CD8+ T cell immune responses.

CONCLUSIONS

The Ad vaccine targeting dual immune checkpoints B7H1 and B7H3 exerts a potent therapeutic effect for renal carcinoma and holds promise for solid tumor treatment.

Neoantigen architectures define immunogenicity and drive immune evasion of tumors with heterogenous neoantigen expression

BACKGROUND

Intratumoral heterogeneity (ITH) and subclonal antigen expression blunt antitumor immunity and are associated with poor responses to immune-checkpoint blockade immunotherapy (ICB) in patients with cancer. The underlying mechanisms however thus far remained elusive, preventing the design of novel treatment approaches for patients with high ITH tumors.

METHODS

We developed a mouse model of lung adenocarcinoma with defined expression of different neoantigens (NeoAg), enabling us to analyze how these impact antitumor T-cell immunity and to study underlying mechanisms. Data from a large cancer patient cohort was used to study whether NeoAg architecture characteristics found to define tumor immunogenicity in our mouse models are linked to ICB responses in patients with cancer.

RESULTS

We demonstrate that concurrent expression and clonality define NeoAg architectures which determine the immunogenicity of individual NeoAg and drive immune evasion of tumors with heterogenous NeoAg expression. Mechanistically, we identified concerted interplays between concurrent T-cell responses induced by cross-presenting dendritic cells (cDC1) mirroring the tumor NeoAg architecture during T-cell priming in the lymph node. Depending on the characteristics and clonality of respective NeoAg, this interplay mutually benefited concurrent T-cell responses or led to competition between T-cell responses to different NeoAg. In tumors with heterogenous NeoAg expression, NeoAg architecture-induced suppression of T-cell responses against branches of the tumor drove immune evasion and caused resistance to ICB. Therapeutic RNA-based vaccination targeting immune-suppressed T-cell responses synergized with ICB to enable control of tumors with subclonal NeoAg expression. A pan-cancer clinical data analysis indicated that competition and synergy between T-cell responses define responsiveness to ICB in patients with cancer.

CONCLUSIONS

NeoAg architectures modulate the immunogenicity of NeoAg and tumors by dictating the interplay between concurrent T-cell responses mediated by cDC1. Impaired induction of T-cell responses supports immune evasion in tumors with heterogenous NeoAg expression but is amenable to NeoAg architecture-informed vaccination, which in combination with ICB portrays a promising treatment approach for patients with tumors exhibiting high ITH.

Expression, regulation, and function of PD-L1 on non-tumor cells in the tumor microenvironment

Antiprogrammed death ligand 1 (PD-L1) therapy is a leading immunotherapy, but only some patients with solid cancers benefit. Overwhelming evidence has revealed that PD-L1 is expressed on various immune cells in the tumor microenvironment (TME), including macrophages, dendritic cells, and regulatory T cells, modulating tumor immunity and influencing tumor progression. PD-L1 can also be located on tumor cell membranes as well as in exosomes and cytoplasm. Accordingly, the dynamic expression and various forms of PD-L1 might explain the therapy's limited efficacy and resistance. Herein a systematic summary of the expression of PD-L1 on different immune cells and their regulatory mechanisms is provided to offer a solid foundation for future studies.

Stat5b/Ezh2 axis governs high PD-L1 expressing tolerogenic dendritic cell subset in autoimmune diabetes

Dendritic cells (DCs) are specialized antigen-presenting cells that play an important role in inducing and maintaining immune tolerance. The altered distribution and/or function of DCs contributes to defective tolerance in autoimmune diseases such as type 1 diabetes (T1D). In human T1D and in NOD mouse models, DCs share some defects and are often described as less tolerogenic and excessively immunogenic. In the NOD mouse model, the autoimmune response is associated with a defect in the Stat5b signaling pathway. We have reported that expressing a constitutively active form of Stat5b in DCs of transgenic NOD mice (NOD.Stat5b-CA), re-established their tolerogenic function, restored autoimmune tolerance and conferred protection from diabetes. However, the role and molecular mechanisms of Stat5b signaling in regulating splenic conventional DCs tolerogenic signature remained unclear. In this study, we reported that, compared to immunogenic splenic DCs of NOD, splenic DCs of NOD.Stat5b-CA mice exhibited a tolerogenic profile marked by elevated PD-L1 and PD-L2 expression, reduced pro-inflammatory cytokine production, increased frequency of the cDC2 subset and decreased frequency of the cDC1 subset. This tolerogenic profile was associated with increased Ezh2 and IRF4 but decreased IRF8 expression. We also found an upregulation of PD-L1 in the cDC1 subset and high PD-L1 and PD-L2 expression in cDC2 of NOD.Stat5b-CA mice. Mechanistically, we demonstrated that Ezh2 plays an important role in the maintenance of high PD-L1 expression in cDC1 and cDC2 subsets and that Ezh2 inhibition resulted in PD-L1 but not PD-L2 downregulation which was more drastic in the cDC2 subset. Additionally, Ezh2 inhibition severely reduced the cDC2 subset and increased the cDC1 subset and Stat5b-CA.DC pro-inflammatory cytokine production. Together our data suggest that the Stat5b-Ezh2 axis is critical for the maintenance of tolerogenic high PD-L1-expressing cDC2 and autoimmune tolerance in NOD.Stat5b-CA mice.

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.

CD80-Fc fusion protein as a potential cancer immunotherapy strategy

The activation of T lymphocytes is a crucial component of the immune response, and the presence of CD80, a membrane antigen, is necessary for T-cell activation. CD80 is usually expressed on antigen-presenting cells (APCs), which can interact with cluster of differentiation 28 (CD28) or programmed cell death ligand 1 (PD-L1) to promote T-cell proliferation, differentiation and function by activating costimulatory signal or blocking inhibitory signal. Simultaneously, CD80 on the APCs also interacts with cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) on the surface of T cells to suppress the response of specific effector T cells, particularly in the context of persistent antigenic stimulation. Due to the pivotal role of CD80 in the immune response, the CD80-Fc fusion protein has emerged as a promising approach for cancer immunotherapy. This review primarily focused on the crucial role of CD80 in the cancer immunotherapy. We also reviewed the current advancements in the research of CD80-Fc fusion proteins. Finally, we deliberated on the challenges encountered by CD80-Fc fusion proteins and proposed the potential strategies that could yield the benefits for patients.

Metformin induces tolerogenicity of dendritic cells by promoting metabolic reprogramming

Dendritic cells (DCs) can mediate immune responses or immune tolerance depending on their immunophenotype and functional status. Remodeling of DCs' immune functions can develop proper therapeutic regimens for different immune-mediated diseases. In the immunopathology of autoimmune diseases (ADs), activated DCs notably promote effector T-cell polarization and exacerbate the disease. Recent evidence indicates that metformin can attenuate the clinical symptoms of ADs due to its anti-inflammatory properties. Whether and how the therapeutic effects of metformin on ADs are associated with DCs remain unknown. In this study, metformin was added to a culture system of LPS-induced DC maturation. The results revealed that metformin shifted DC into a tolerant phenotype, resulting in reduced surface expression of MHC-II, costimulatory molecules and CCR7, decreased levels of proinflammatory cytokines (TNF-α and IFN-γ), increased level of IL-10, upregulated immunomodulatory molecules (ICOSL and PD-L) and an enhanced capacity to promote regulatory T-cell (Treg) differentiation. Further results demonstrated that the anti-inflammatory effects of metformin in vivo were closely related to remodeling the immunophenotype of DCs. Mechanistically, metformin could mediate the metabolic reprogramming of DCs through FoxO3a signaling pathways, including disturbing the balance of fatty acid synthesis (FAS) and fatty acid oxidation (FAO), increasing glycolysis but inhibiting the tricarboxylic acid cycle (TAC) and pentose phosphate pathway (PPP), which resulted in the accumulation of fatty acids (FAs) and lactic acid, as well as low anabolism in DCs. Our findings indicated that metformin could induce tolerance in DCs by reprogramming their metabolic patterns and play anti-inflammatory roles in vitro and in vivo.

Reversing immune evasion using a DNA nano-orchestrator for pancreatic cancer immunotherapy

Immune evasion caused by the paucity of MHCI is a prominent characteristic of pancreatic adenocarcinoma (PAAD), which is thought to underlie dysfunctional even absent adaptive T cell immunity and is responsible for ineffective immunotherapy. Here, we report a ROS-responsive DNA nano-orchestrator to cascade reverse MHC I-associated immune evasion and boost anti-tumor T cell stimulation, stimulating the activation of tumoricidal immunity against PAAD. Chloroquine phosphate (CQP) as an autophagy inhibitor was first encapsulated with ferritin, and via DNA modular self-assembly technology, the generated ferritin nanocores (FNC) were then caged into ROS-responsive CpG-DNA nanoframe. After systemic injection, the FNC-laden DNA nanoframe (FNC@NF) was passively enriched in tumor tissues in which the DNA nanoframe was cleaved upon the ROS stimulation. Oligodeoxynucleotide (ODN) with CpG motifs was detached and functioned as a TLR9 agonist. The liberated FNC was then endocytosed in an actively targeted manner by binding to transferrin receptor 1. In the lysosome, CQP was burst released from FNC due to acid-triggering. Through CQP-mediated autophagy abrogation, MHC-I molecules were preserved. We demonstrated that cascade inhibiting autophagy and boosting TLR9 stimulation via our proposed DNA-based hybrid nanosystem restored MHC I on the tumor cell surface and reshaped the antigen presentation of DCs, and ultimately reversed immune evasion and synergistically reinforced the activation of cytotoxic T cells against PAAD cells. In sum, our work provides an alternative strategy for cascade reversing immune evasion and boosting anti-tumor T cell stimulation and holds great potential for pancreatic cancer immunotherapy. STATEMENT OF SIGNIFICANCE: A DNA nano-orchestrator was created by sequentially assembling chloroquine phosphate-laden ferritin nanocores with ROS-responsive CpG-DNA nanoframe. Through cascade inhibiting autophagy and boosting TLR9 stimulation, the nano-orchestrator efficiently reversed MHC I-associated immune evasion and augmented anti-tumor T cell stimulation, which ultimately activated tumoricidal immunity against pancreatic adenocarcinoma.

Modern treatment approaches to adult acute T-lymphoblastic and myeloid/T-lymphoblastic leukemia: from current standards to precision medicine

PURPOSE OF REVIEW

To review the most recent advancements in the management of adult T-cell acute lymphoblastic leukemia (T-ALL), we summarize insights into molecular diagnostics, immunotherapy, targeted therapy and new techniques of drug sensitivity profiling that may support further therapeutic progress in T-ALL subsets.

RECENT FINDINGS

With current induction/consolidation chemotherapy and/or risk-oriented allogeneic stem cell transplantation programs up to 95% adult T-ALL patients achieve a remission and >50% (up to 80% in adolescents and young adults) are cured. The group of patients who fail upfront therapy, between 25% and 40%, is enriched in high-risk characteristics (unfavorable genetics, persistent minimal residual disease) and represents the ideal setting for the study of molecular mechanisms of disease resistance, and consequently explore novel ways of restoration of drug sensitivity and assess patient/subset-specific patterns of drug vulnerability to targeting agents, immunotherapy and cell therapy.

SUMMARY

The emerging evidence supports the contention that precision medicine may soon allow valuable therapeutic chances to adult patients with high-risk T-ALL. The ongoing challenge is to identify the best way to integrate all these new data into the therapeutic path of newly diagnosed patients, with a view to optimize the individual treatment plan and increase the cure rate.

What Happens to the Immune Microenvironment After PD-1 Inhibitor Therapy?

The fruitful results of tumor immunotherapy establish its indispensable status in the regulation of the tumorous immune context. It seems that the treatment of programmed cell death receptor 1 (PD-1) blockade is one of the most promising approaches for cancer control. The significant efficacy of PD-1 inhibitor therapy has been made in several cancer types, such as breast cancer, lung cancer, and multiple myeloma. Even so, the mechanisms of how anti-PD-1 therapy takes effect by impacting the immune microenvironment and how partial patients acquire the resistance to PD-1 blockade have yet to be studied. In this review, we discuss the cross talk between immune cells and how they promote PD-1 blockade efficacy. In addition, we also depict factors that may underlie tumor resistance to PD-1 blockade and feasible solutions in combination with it.

Robust rank aggregation and cibersort algorithm applied to the identification of key genes in head and neck squamous cell cancer

OBJECTIVE

Although multiple hub genes have been identified in head and neck squamous cell cancer (HNSCC) in recent years, because of the limited sample size and inconsistent bioinformatics analysis methods, the results are not reliable. Therefore, it is urgent to use reliable algorithms to find new prognostic markers of HNSCC.

METHOD

The Robust Rank Aggregation (RRA) method was used to integrate 8 microarray datasets of HNSCC downloaded from the Gene Expression Omnibus (GEO) database to screen differentially expressed genes (DEGs). Later, Gene Ontology (GO) functional annotation together with Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis was carried out to discover functions of those discovered DEGs. According to the KEGG results, those discovered DEGs showed tight association with the occurrence and development of HNSCC. Then cibersort algorithm was used to analyze the infiltration of immune cells of HNSCC and we found that the main infiltrated immune cells were B cells, dendritic cells and macrophages. A protein-protein interaction (PPI) network was established; moreover, key modules were also constructed to select 5 hub genes from the whole network using cytoHubba. 3 hub genes showed significant relationship with prognosis for TCGA-derived HNSCC patients.

RESULT

The potent DEGs along with hub genes were selected by the combined bioinformatic approach. AURKA, BIRC5 and UBE2C genes may be the potential prognostic biomarker and therapeutic targets of HNSCC.

CONCLUSIONS

The Robust Rank Aggregation method and cibersort algorithm method can accurately predict the potential prognostic biomarker and therapeutic targets of HNSCC through multiple GEO datasets.

Serum alanine aminotransferase as an early marker of outcomes in patients receiving anti-PD-1 or anti-CTLA-4 antibody

Immune-oncology (IO) drug therapy is effective against various types of cancer. Although several, potential, clinical predictive markers have been identified, none so far have proven reliable. Herein we evaluated changes in serum alanine aminotransferase (ALT), which is upregulated by the accumulation of activated CD8+T cells in the liver, as a potentially reliable predictive marker. We retrospectively analyzed 265 patients with advanced malignancies at three institutions between 2016 and 2019. The patients received IO drug therapy. We defined the ALT ratio (ALR) as the serum ALT value at baseline / the highest serum ALT during IO drug therapy, then determined whether the ALR correlated with the objective response rate or progression-free survival. The median follow-up was 3.1 months. We observed objective responses in 65 patients. The ALR ranged from 0.19 to 32.2 (median 1.5), and a significant ALR increase was observed in responders (p < 0.001). In receiver operating characteristic analysis, ALR = 1.55 had the highest sensitivity and specificity. The patients with ALR < 1.55 had a significantly poorer PFS than those with ALR ≥ 1.55. A high ALR was associated with a tumor response and good PFS in patients with advanced malignancies. The ALR based on activated cytotoxic T lymphocyte dynamics is therefore a reliable predictive marker.

Synergistic anti-tumor effect of anti-PD-L1 antibody cationic microbubbles for delivery of the miR-34a gene combined with ultrasound on cervical carcinoma

This study explored the synergistic effect of anti-PD-L1 antibody cationic microbubbles (MBs) for delivery of the miR-34a gene combined with ultrasound in inhibiting the cervical cancer. H&E stain, TUNEL, immunohistochemistry and RT-PCR were used to detect the change of apoptosis regulatory factors, and immunofluorescence, Flow cytometry and LDH assays were applied to evaluate the changing of immunomodulatory. In this experiment the PD-L1 Ab/miR-34a-MBs were prepared successfully. The cell targeting assay showed that U14 cells were surrounded by the PD-L1 Ab/miR-34a-MBs and microbubbles had well contrast imaging capability in vivo. With the irradiation power was 1 W/cm2 and the irradiation time was 25 s, the gene transfection efficiency was the highest using EGFP plasmid lorded microbubbles. In vivo anti-tumor assays, the PD-L1 Ab/miR-34a-MBs showed a great potential in inhibiting tumor growth with a TGI of >50%. PD-L1 Ab/miR-34a-MBs treatment enhanced the anti-tumor effect compared with that induced by PD-L1 Ab or miR-34a alone. Firstly, PD-L1 Ab/miR-34a-MBs could gather miR-34a with high-concentration aggregation and releasing around the cervical cancer, which takes a significant role in promoting apoptosis by downregulated Bcl-2 and upregulated Bax. Furthermore, combination therapy was found to augment the activation of T lymphocytes proliferation and increase CD8+ T cells infiltration, to enhance antitumor immune killing effect. The anti-PD-L1 antibody microbubbles for delivery miR-34a gene with ultrasound were considered to be a promising combination therapy regimen via initiating apoptotic mechanism of the tumor and anti-tumor immune regulation.

Combination of vasculature targeting, hypofractionated radiotherapy, and immune checkpoint inhibitor elicits potent antitumor immune response and blocks tumor progression

Background

Tumor endothelial marker 1 (TEM1) is a protein expressed in the tumor-associated endothelium and/or stroma of various types of cancer. We previously demonstrated that immunization with a plasmid-DNA vaccine targeting TEM1 reduced tumor progression in three murine cancer models. Radiation therapy (RT) is an established cancer modality used in more than 50% of patients with solid tumors. RT can induce tumor-associated vasculature injury, triggering immunogenic cell death and inhibition of the irradiated tumor and distant non-irradiated tumor growth (abscopal effect). Combination treatment of RT with TEM1 immunotherapy may complement and augment established immune checkpoint blockade.

Methods

Mice bearing bilateral subcutaneous CT26 colorectal or TC1 lung tumors were treated with a novel heterologous TEM1-based vaccine, in combination with RT, and anti-programmed death-ligand 1 (PD-L1) antibody or combinations of these therapies, tumor growth of irradiated and abscopal tumors was subsequently assessed. Analysis of tumor blood perfusion was evaluated by CD31 staining and Doppler ultrasound imaging. Immunophenotyping of peripheral and tumor-infiltrating immune cells as well as functional analysis was analyzed by flow cytometry, ELISpot assay and adoptive cell transfer (ACT) experiments.

Results

We demonstrate that addition of RT to heterologous TEM1 vaccination reduces progression of CT26 and TC1 irradiated and abscopal distant tumors as compared with either single treatment. Mechanistically, RT increased major histocompatibility complex class I molecule (MHCI) expression on endothelial cells and improved immune recognition of the endothelium by anti-TEM1 T cells with subsequent severe vascular damage as measured by reduced microvascular density and tumor blood perfusion. Heterologous TEM1 vaccine and RT combination therapy boosted tumor-associated antigen (TAA) cross-priming (ie, anti-gp70) and augmented programmed cell death protein 1 (PD-1)/PD-L1 signaling within CT26 tumor. Blocking the PD-1/PD-L1 axis in combination with dual therapy further increased the antitumor effect and gp70-specific immune responses. ACT experiments show that anti-gp70 T cells are required for the antitumor effects of the combination therapy.

Conclusion

Our findings describe novel cooperative mechanisms between heterologous TEM1 vaccination and RT, highlighting the pivotal role that TAA cross-priming plays for an effective antitumor strategy. Furthermore, we provide rationale for using heterologous TEM1 vaccination and RT as an add-on to immune checkpoint blockade as triple combination therapy into early-phase clinical trials.

MAL2 drives immune evasion in breast cancer by suppressing tumor antigen presentation

Immune evasion is a pivotal event in tumor progression. To eliminate human cancer cells, current immune checkpoint therapy is set to boost CD8+ T cell-mediated cytotoxicity. However, this action is eventually dependent on the efficient recognition of tumor-specific antigens via T cell receptors. One primary mechanism by which tumor cells evade immune surveillance is to downregulate their antigen presentation. Little progress has been made toward harnessing potential therapeutic targets for enhancing antigen presentation on the tumor cell. Here, we identified MAL2 as a key player that determines the turnover of the antigen-loaded MHC-I complex and reduces the antigen presentation on tumor cells. MAL2 promotes the endocytosis of tumor antigens via direct interaction with the MHC-I complex and endosome-associated RAB proteins. In preclinical models, depletion of MAL2 in breast tumor cells profoundly enhanced the cytotoxicity of tumor-infiltrating CD8+ T cells and suppressed breast tumor growth, suggesting that MAL2 is a potential therapeutic target for breast cancer immunotherapy.

Immune Co-inhibitory Receptors PD-1, CTLA-4, TIM-3, LAG-3, and TIGIT in Medullary Thyroid Cancers: A Large Cohort Study

CONTEXT

Programmed cell death protein-1 (PD-1), cytotoxic T-lymphocyte antigen 4 (CTLA-4), T-cell immunoglobulin and mucin-domain containing-3 (TIM-3), lymphocyte activation gene-3 (LAG-3), and T-cell immunoglobulin and ITIM domain (TIGIT) are considered major immune co-inhibitory receptors (CIRs) and the most promising immunotherapeutic targets in cancer treatment, but they are largely unexplored in medullary thyroid carcinoma (MTC).

OBJECTIVE

We aimed to provide the first evidence regarding the expression profiles and clinical significance of CIRs in a large cohort of MTC patients.

DESIGN AND PATIENTS

In total, 200 MTC patients who received initial surgery in our hospital were included. Immunohistochemistry was performed to evaluate CIR expressions in tissue microarrays (TMAs). Combined with the results of our previous programmed cell death ligand-1 (PD-L1) study, clinicopathologic and prognostic correlations of these proteins were retrospectively analyzed.

RESULTS

TIM-3, PD-1, CTLA-4, LAG-3, and TIGIT positivity was detected in 96 (48.0%), 27 (13.5%), 25 (12.5%), 6 (3.0%), and 6 (3.0%) patients, respectively, in whom TIM-3, PD-1, and CTLA-4 expressions were positively correlated. Log-rank tests and multivariate Cox analyses both indicated that TIM-3, CTLA-4 expression, and PD-1/PD-L1 coexpression were associated with worse structural recurrence-free survival. In addition, among 20 patients who developed advanced disease during follow-up, 12 (60%) showed TIM-3 positivity, among whom 6 cases also had concurrent moderate to strong PD-1, PD-L1, or CTLA-4 expression.

CONCLUSIONS

Using the currently largest TMA cohort of this rare cancer, we delineated the CIR expression profiles in MTC, and identified TIM-3, CTLA-4 expression, and PD-1/PD-L1 coexpression as promising biomarkers for tumor recurrence. Furthermore, a subset of advanced MTCs are probably immunogenic, for which single or combined immunotherapy including TIM-3, PD-1, PD-L1, or CTLA-4 blockade may be potential therapeutic approaches in the future.

PD-L1 on dendritic cells attenuates T cell activation and regulates response to immune checkpoint blockade

Immune checkpoint blockade therapies have shown clinical promise in a variety of cancers, but how tumor-infiltrating T cells are activated remains unclear. In this study, we explore the functions of PD-L1 on dendritic cells (DCs), which highly express PD-L1. We observe that PD-L1 on DC plays a critical role in limiting T cell responses. Type 1 conventional DCs are essential for PD-L1 blockade and they upregulate PD-L1 upon antigen uptake. Upregulation of PD-L1 on DC is mediated by type II interferon. While DCs are the major antigen presenting cells for cross-presenting tumor antigens to T cells, subsequent PD-L1 upregulation protects them from killing by cytotoxic T lymphocytes, yet dampens the antitumor responses. Blocking PD-L1 in established tumors promotes re-activation of tumor-infiltrating T cells for tumor control. Our study identifies a critical and dynamic role of PD-L1 on DC, which needs to be harnessed for better invigoration of antitumor immune responses.

The Risk Ratio of Immune-Related Colitis, Hepatitis, and Pancreatitis in Patients With Solid Tumors Caused by PD-1/PD-L1 Inhibitors: A Systematic Review and Meta-Analysis

Purpose: The meta-analysis was put into practice in evaluating the risk ratio of immune-related digestive system inflammation in patients with solid tumors caused by PD-1/PD-L1 inhibitors. Method: The process of the meta-analysis was performed by us according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. Results: After screening and eligibility assessment, a total of 26 clinical trials involving 16,409 patients were selected for the final quantitative synthesis. Immune-related digestive system inflammations, including colitis, hepatitis, pancreatitis, were evaluated separately. Compared with chemotherapy, PD-1/PD-L1 inhibitors led to an increase in the incidence risk of all grade colitis (RR = 2.43, 95% CI: [1.23, 4.82], P = 0.01). Similar incidence trend could also be seen when PD-1/PD-L1 inhibitors were combined with chemotherapy (RR = 2.62, 95% CI: [1.25, 5.48], P = 0.01). Whether compared with Nivolumab plus Ipilimumab or Ipilimumab alone, the incidence risk of colitis in the Nivolumab group was significantly lower than that of the control group. Similar analysis results could also be seen in the incidence risk of hepatitis. We did not find a statistically significant effect on the incidence of immune-related pancreatitis after the use of PD-1/PD-L1 inhibitors. Conclusion: The use of PD-1/PD-L1 inhibitors increased the incidence risk of immune-related colitis and hepatitis, but this potential to increase the incidence risk of the disease was weaker than Ipilimumab.

Histone deacetylase inhibition up-regulates MHC class I to facilitate cytotoxic T lymphocyte-mediated tumor cell killing in glioma cells

Background: Immune cells recognize tumor antigens presented on major histocompatibility complex class I (MHC-I) molecule. Increase of MHC-I molecular expression makes tumor cells more susceptible to lysis by immune cells.

Methods: Tumor lysate vaccine was prepared to damage glioma cells including cell lines and primary cultured cells from surgical samples. The enhanced effect of histone deacetylase inhibitors (HDACi) to tumor lysate vaccine was observed. The expressions of MHC-I pathway molecules were detected by flow cytometry and western blot after HDACi treatment. Cell apoptosis and cell lysis were measured following blocking cytotoxic T lymphocyte (CTL) pathway. Tumor size and mice survival were analyzed in combinative treatment with HDACi and tumor lysate.

Results: HDACi up-regulated the expressions of MHC-I pathway molecules, and enhanced the recognition and killing of immune cells, which was activated by tumor lysate. Activated antigen specific immune responses regulated CTL activity, and HDACi promoted immune response through cytotoxic effect of CTL. Anti-tumor effect of tumor lysate pulse immunogenicity in vivo was elevated by HDACi due to up-regulation of antigen presentation.

Conclusions: Our study showed that HDACi enhanced recognition of glioma cell by immune cells and sensitivity of tumor immunotherapy, and improved the anti-tumor effect of tumor lysate vaccine through activating CTL immune response. These pharmacological molecular mechanisms of increasing immune recognition suggest that epigenetic modulation is a promising strategy for sensitizing immunotherapy for glioma treatment.

A Paradigm Shift in Cancer Immunotherapy: From Enhancement to Normalization

Harnessing an antitumor immune response has been a fundamental strategy in cancer immunotherapy. For over a century, efforts have primarily focused on amplifying immune activation mechanisms that are employed by humans to eliminate invaders such as viruses and bacteria. This "immune enhancement" strategy often results in rare objective responses and frequent immune-related adverse events (irAEs). However, in the last decade, cancer immunotherapies targeting the B7-H1/PD-1 pathway (anti-PD therapy), have achieved higher objective response rates in patients with much fewer irAEs. This more beneficial tumor response-to-toxicity profile stems from distinct mechanisms of action that restore tumor-induced immune deficiency selectively in the tumor microenvironment, here termed "immune normalization," which has led to its FDA approval in more than 10 cancer indications and facilitated its combination with different therapies. In this article, we wish to highlight the principles of immune normalization and learn from it, with the ultimate goal to guide better designs for future cancer immunotherapies.

Metastatic renal cell carcinoma regains sensitivity to tyrosine kinase inhibitor after nivolumab treatment: A case report

Sequential therapy using tyrosine kinase inhibitors (TKIs) and mammalian target of rapamycin inhibitors is the mainstay of treatment for metastatic renal cell carcinoma. Recently, anti-programmed death-1 (PD-1) antibody, a type of immune checkpoint inhibitor, was approved for use against metastatic renal cell carcinoma. In the present report, two cases of TKI-refractory metastatic renal cell carcinoma which regained sensitivity to TKI after immunotherapy with nivolumab were described. In one case, a third challenge with axitinib after nivolumab treatment resulted in tumor shrinkage, although the second challenge with axitinib immediately before nivolumab treatment had no effect. In another case, a second challenge with pazopanib after nivolumab slightly reduced lung metastasis, which was refractory to pazopanib before nivolumab treatment. These cases suggest that nivolumab can influence the response to subsequent TKI treatment.

PD-1/PD-L1 co-inhibition shapes anticancer T cell immunodominance: facing the consequences of an immunological ménage à trois

PD-1- and PD-L1-blocking monoclonal antibodies have shown significant promise in clinical settings and rekindled the hope for successful cancer immunotherapy. We recently demonstrated that interfering with PD-1/PD-L1 signaling selectively augments CD8+ T cell (TCD8) responses to subdominant determinants (SDDs) of a model tumor antigen. This was likely due to decreased lysis of SDD-specific TCD8 by neighboring immunodominant clones co-engaging the same antigen-presenting cells (APCs). We therefore proposed that PD-1-based checkpoint inhibitors widen the range of tumor determinants that can be effectively targeted by TCD8. Subsequently and using different tumor models, Chen et al. reported, in Proceedings of the National Academy of Sciences of the United States of America, that PD-L1 protects APCs from the lytic function of immunodominant TCD8 and that PD-L1 blockade narrows, rather than broadens, the overall anticancer T cell response. Here, we briefly compare and contrast the experimental systems employed by the two groups, which may account, at least partially, for the opposing conclusions drawn. We argue that the pathway(s) of tumor antigen presentation, direct presentation versus cross-presentation, and the intensity of PD-1 expression by immunodominant and subdominant TCD8 must be taken into consideration in rational design of anti-PD-1/PD-L1-adjuvanted tumor vaccines and therapies.