Insights from a 30-year journey: function, regulation and therapeutic modulation of PD1

Discovery of Dual PD-L1/HDAC3 Inhibitors for Tumor Immunotherapy

Targeting programmed cell death protein-1 (PD-1)/programmed cell death-ligand 1 (PD-L1) pathway has been considered as one of the most promising strategies for tumor immunotherapy. However, single-target PD-1/PD-L1 inhibitors frequently exhibit limited efficacy, highlighting the urgent need for new therapies. Herein, a series of dual PD-L1/HDAC3 inhibitors were developed through a pharmacophore fusion strategy for the first time. Among them, compound PH3 was identified as the most promising dual PD-L1/HDAC3 inhibitor, with potent PD-1/PD-L1 inhibitory activity (IC50 = 89.4 nM) and selective HDAC3 inhibitory activity (IC50 = 107 nM). Moreover, PH3 exhibited superior in vitro antitumor activities and in vitro immune activation effects. Additionally, PH3 showed potent and dose-dependent antitumor efficacy in the B16-F10 melanoma mouse model without obvious toxicity. Furthermore, PH3 increased the infiltration of CD3+CD8+ and CD3+CD4+ cells in the tumor microenvironment. Collectively, PH3 represented a novel dual PD-L1/HDAC3 inhibitor deserving further investigation as a tumor immunotherapy agent.

Advancements in the application of ablative therapy and its combination with immunotherapy in anti-cancer therapy

Cancer is a significant health issue impacting humans. Currently, systemic therapies such as chemotherapy have significantly increased the life expectancy of cancer patients. However, some patients are unable to endure systemic treatment due to its significant adverse effects, leading to an increased focus on local therapies including radiation and ablation therapy. Ablation therapy is a precise, low-toxicity, and minimally invasive localized therapy that is increasingly acknowledged by clinicians and cancer patients. Many cancer patients have benefited from it, with some achieving full recovery. Currently, numerous studies have shown that ablation therapy is effective due to its ability to kill cancer cells efficiently and activate the body's anti-cancer immunity. It can also convert "cold cancers" into "hot cancers" and enhance the effectiveness of immunotherapy when used in combination. In this article, we categorize ablation therapy into thermal ablation, cryoablation, photodynamic therapy (PDT), irreversible electroporation (IRE), etc. Thermal ablation is further divided into Radiofrequency ablation (RFA), microwave ablation (WMA), high-frequency focused ultrasound (HIFU), photothermal therapy (PTT), magnetic heat therapy (MHT), etc. We systematically review the most recent advancements in these ablation therapies that are either currently used in clinic or are anticipated to be used in clinic. Then, we also review the latest development of various ablative therapies combined with immunotherapy, and its future development. CLINICAL RELEVANCE STATEMENT: Ablation therapy, an invasive localized treatment, offers an alternative to systemic therapies for cancer patients who cannot tolerate their adverse effects. Its ability to kill cancer cells efficiently and activate anti-cancer immunity. This article reviews recent advancements in ablation therapies, including thermal, cryoablation, PDT, and IRE, and their potential clinical applications, both standalone and in combination with immunotherapy.

Recent Advances in Aging and Immunosenescence: Mechanisms and Therapeutic Strategies

Cellular senescence is an irreversible state of cell cycle arrest. Senescent cells (SCs) accumulate in the body with age and secrete harmful substances known as the senescence-associated secretory phenotype (SASP), causing chronic inflammation; at the same time, chronic inflammation leads to a decrease in immune system function, known as immunosenescence, which further accelerates the aging process. Cellular senescence and immunosenescence are closely related to a variety of chronic diseases, including cardiovascular diseases, metabolic disorders, autoimmune diseases, and neurodegenerative diseases. Studying the mechanisms of cellular senescence and immunosenescence and developing targeted interventions are crucial for improving the immune function and quality of life of elderly people. Here, we review a series of recent studies focusing on the molecular mechanisms of cellular senescence and immunosenescence, the regulation of aging by the immune system, and the latest advances in basic and clinical research on senolytics. We summarize the cellular and animal models related to aging research, as well as the mechanisms, strategies, and future directions of aging interventions from an immunological perspective, with the hope of laying the foundation for developing novel and practical anti-aging therapies.

Oxygen-delivery nanoparticles enhanced immunotherapy efficacy monitored by granzyme B PET imaging in malignant tumors

Limited treatment response and inadequate monitoring methods stand firmly before successful immunotherapy. Recruiting and activating immune cells in the hypoxic tumor microenvironment is the key to reversing immune suppression and improving immunotherapy efficacy. In this study, biomimetic oxygen-delivering nanoparticles (CmPF) are engineered for homologous targeting and hypoxia alleviation within the tumor environment. CmPF targets the tumor microenvironment and delivers oxygen to reduce hypoxia, thereby promoting immune cell activity at the tumor site. In addition, granzyme B-targeted positron emission tomography (PET) imaging is employed to monitor immune cell activity changes in response to immunotherapy efficacy in vivo. The combination of CmPF with carboplatin and PD-1 inhibitors significantly suppresses tumor growth by 2.4-fold, exhibiting the potential of CmPF to enhance the efficacy of immunotherapy. Immunohistochemistry further confirms increased expression of key immune markers, highlighting the reprogramming of the tumor microenvironment. This study demonstrates that hypoxia alleviation enhances tumor immunotherapy efficacy and introduces a non-invasive PET imaging method for dynamic, real-time assessment of therapeutic response.

Targeting Immune Checkpoint Inhibitors for Non-Small-Cell Lung Cancer: Beyond PD-1/PD-L1 Monoclonal Antibodies

Non-small-cell lung cancer (NSCLC) remains a leading cause of cancer-related mortality worldwide. Immunotherapy targeting the PD-1/PD-L1 axis has revolutionized treatment, providing durable responses in a subset of patients. However, with fewer than 50% of patients achieving significant benefits, there is a critical need to expand therapeutic strategies. This review explores emerging targets in immune checkpoint inhibition beyond PD-1/PD-L1, including CTLA-4, TIGIT, LAG-3, TIM-3, NKG2A, and CD39/CD73. We highlight the biological basis of CD8 T cell exhaustion in shaping the antitumor immune response. Novel therapeutic approaches targeting additional inhibitory receptors (IR) are discussed, with a focus on their distinct mechanisms of action and combinatory potential with existing therapies. Despite significant advancements, challenges remain in overcoming resistance mechanisms and optimizing patient selection. This review underscores the importance of dual checkpoint blockade and innovative bispecific antibody engineering to maximize therapeutic outcomes for NSCLC patients.

Harnessing extracellular vesicle-mediated crosstalk between T cells and cancer cells for therapeutic applications

Small extracellular vesicles (EVs) are a diverse group of lipid-based particles that are ≤200 nm in diameter and contain an aqueous core. EVs have been shown to mediate intercellular communications between a wide array of immune cells; the downstream effects are diverse and have potential implications for the development of novel immunotherapeutic treatments. Despite a high volume of studies addressing the role EVs play in the immune system, our understanding of the crosstalk between T cells and cancer cells remains limited. Here, we discuss how EVs derived from cancer cells modulate T cell functions and conversely, how T cell derived EVs are crucial in modulating adaptive immune functions. In the context of cancer, tumor derived EVs (TD-EVs) halt T cell-mediated immunity by interfering with effector functions and enhancing regulatory T cell (Treg) functions. In contrast, EVs derived from effector T cells can serve to stimulate anticancer immunity, curbing metastasis and tumor growth. These findings highlight important aspects of how EVs can both mediate the therapeutic effects of T cells as well as impair T cell-mediated immunity. This calls for a deeper understanding of EV-mediated effects in order to advance them as next-generation therapeutics and nanocarriers.

Peripheral blood PD-1+ T lymphocytes as biomarkers in liquid biopsies for solid tumors: Clinical significance and prognostic applications

A shift toward a T cell exhaustion phenotype is associated with the upregulation of expression of programmed cell death protein 1 (PD-1) on T lymphocytes in patients with malignant solid tumors. The interaction between PD-1 and programmed death-ligand 1 (PD-L1) inhibits PD-1+ T lymphocyte function, impacting their anti-tumor immune activity. Immune checkpoint inhibitors targeting PD-1/PD-L1 have revolutionized the treatment of various solid malignancies, improving therapeutic efficacy and survival outcomes. Peripheral blood analysis of liquid biopsies is being increasingly used to identify populations most likely to benefit from various treatment modalities. PD-1+ T lymphocytes represent the primary cell population responsive to immunotherapeutic interventions for patients with solid malignancies, as evidenced by the altered PD-1 expression levels and proportion of cells comprising the overall population of immunocytes. PD-1+ T cells in peripheral blood exert an associative and reciprocal predictive effect on homologous intratumoral cells. Distinct subpopulations of PD-1+ T cells exhibit differential ability to proliferate in the periphery and can be characterized by tumor antigen-specific and exhaustion phenotypes. These characteristics have prognostic implications, aiding in the prediction of the efficacy of antitumor therapy and predicting survival outcomes. We highlight distinct subpopulations of PD-1+ T cells, their exhaustion and antigen-specific phenotypes, and their dynamic changes over treatment, providing insights into their utility for tailoring personalized therapies. For the first time, this review discusses the role of peripheral PD-1+ T lymphocytes as prognostic biomarkers in liquid biopsies, focusing on their clinical significance, predictive value during therapy, and future research directions.

Apatinib Degrades PD-L1 and Reconstitutes Colon Cancer Microenvironment via the Regulation of Myoferlin

BACKGROUND

For most colorectal cancer (CRC) patients, expanding the benefits of immunotherapy, particularly through blocking programmed cell death-1 (PD-1) and its ligand (PD-L1), is crucial, especially in cases with limited response to neoadjuvant therapy. This study investigates the role of Myoferlin (MYOF) as a novel target in CRC immunotherapy.

METHODS

Human CRC cell lines (RKO, HCT116), normal intestinal epithelial cells (HIEC-6), and the murine CRC cell line MC38 were used to study the effects of apatinib and MYOF in CRC cells. RNA sequencing, the CPTAC and TCGA databases, and other molecular and cellular methods were applied to disclose the mechanisms involved. A series of mouse models were established to assess the effects of apatinib and MYOF knockdown on tumor progression, immune cell infiltration, and immune checkpoint protein response.

RESULTS

We found that MYOF is overexpressed in CRC and linked to immune cell infiltration and checkpoint expression. Suppression of MYOF expression significantly inhibited CRC cell proliferation and migration, as well as reduced PD-L1 protein levels. Integrative analysis showed that apatinib modulates MYOF expression via VEGFR2, resulting in decreased PD-L1 expression, increased CD8+ T cell infiltration, and reduced pro-tumor M2 macrophages. Animal experiments further revealed that apatinib treatment or MYOF knockdown enhanced the efficacy of immune checkpoint blockade (ICB) in CRC.

CONCLUSIONS

These findings highlight novel antitumor mechanisms of MYOF and suggest that combining apatinib with ICB therapy may improve CRC treatment outcomes, offering a promising strategy to enhance immune responses.

Targeting the PD-1/PD-L1 Signaling Pathway for Cancer Therapy: Focus on Biomarkers

The PD1/PD-L1 axis plays an important immunosuppressive role during the T-cell-mediated immune response, which is essential for the physiological homeostasis of the immune system. The biology of the immunological microenvironment is extremely complex and crucial for the development of treatment strategies for immunotherapy. Characterization of the immunological, genomic or transcriptomic landscape of cancer patients could allow discrimination between responders and non-responders to anti-PD-1/PD-L1 therapy. Immune checkpoint inhibitor (ICI) therapy has shown remarkable efficacy in a variety of malignancies in landmark trials and has fundamentally changed cancer therapy. Current research focuses on strategies to maximize patient selection for therapy, clarify mechanisms of resistance, improve existing biomarkers, including PD-L1 expression and tumor mutational burden (TMB), and discover new biomarkers. In this review, we focus on the function of the PD-1/PD-L1 signaling pathway and discuss the immunological, genomic, epigenetic and transcriptomic landscape in cancer patients receiving anti-PD-1/PD-L1 therapy. Finally, we provide an overview of the clinical trials testing the efficacy of antibodies against PD-1/PD-L1.

Timing Anti-PD-L1 Checkpoint Blockade Immunotherapy to Enhance Tumor Irradiation

Background: The ability of radiotherapy (RT) to drive anti-tumor immunity is limited by adaptive resistance. While RT induces inflammation and recruits activated tumor-infiltrating lymphocytes (TILs), including cytotoxic T lymphocytes (CTLs), the resulting radiation- and IFNγ-dependent PD-L1 expression restores an immunosuppressed tumor microenvironment. Unleashing an effective anti-tumor response may require the precise sequencing of RT and checkpoint blockade immunotherapy (CBI) to block PD-L1 signaling before it can mediate its suppressive effects. Methods: Flank tumors formed in BALB/c mice with syngeneic CT26 colon or 4T1 mammary carcinoma cells were treated with otherwise ineffective doses of ionizing radiation (10 Gy) followed by CBI (0.2 mg anti-PD-L1, i.v.) after 0, 1, 3, 5, or 7 days, comparing tumor response. Anti-PD-L1 delivery was measured by fluorescence, TILs by flow cytometry and immunofluorescence, PD-L1 expression by immunohistochemistry, and tumor size by calipers. Results: In both CT26 and 4T1 tumors, 10 Gy alone resulted in a transient growth delay associated with infiltrating CTLs peaking at 3 days and PD-L1 at 5 days. CTLs returned to baseline after 7 days, consistent with adaptive resistance. Anti-PD-L1 failed to potentiate radiation except when injected 5 days after 10 Gy, which prevented CTL depletion and led to tumor elimination. Potentially contributing to compound effects, anti-PD-L1 penetrated tumors and bound PD-L1 more efficiently after irradiation. Conclusions: Optimal timing to exploit radiation-induced permeability to enhance CBI delivery and interrupt adaptive resistance by blocking PD-L1 as it peaks may offer a general strategy to enhance external beam radiotherapy by protecting activated TILs and potentiating anti-tumor immune response.

Current status and future prospects of molecular imaging in targeting the tumor immune microenvironment

Molecular imaging technologies have significantly transformed cancer research and clinical practice, offering valuable tools for visualizing and understanding the complex tumor immune microenvironment. These technologies allow for the non-invasive examination of key components within the tumor immune microenvironment, including immune cells, cytokines, and stromal cells, providing crucial insights into tumor biology and treatment responses. This paper reviews the latest advancements in molecular imaging, with a focus on its applications in assessing interactions within the tumor immune microenvironment. Additionally, the challenges faced by molecular imaging technologies are discussed, such as the need for highly sensitive and specific imaging agents, issues with data integration, and difficulties in clinical translation. The future outlook emphasizes the potential of molecular imaging to enhance personalized cancer treatment through the integration of artificial intelligence and the development of novel imaging probes. Addressing these challenges is essential to fully realizing the potential of molecular imaging in improving cancer diagnosis, treatment, and patient outcomes.

Emerging roles of checkpoint molecules on B cells

Immune checkpoint molecules, including both co-inhibitory molecules and co-stimulatory molecules, are known to play critical roles in regulating T-cell responses. During the last decades, immunotherapies targeting these molecules (such as programmed cell death 1 (PD-1), and lymphocyte activation gene 3 (LAG-3)) have provided clinical benefits in many cancers. It is becoming apparent that not only T cells, but also B cells have a capacity to express some checkpoint molecules. These were originally thought to be only the markers for regulatory B cells which produce IL-10, but recent studies suggest that these molecules (especially T-cell immunoglobulin and mucin domain 1 (TIM-1), T cell immunoreceptor with Ig and ITIM domains (TIGIT), and PD-1) can regulate intrinsic B-cell activation and functions. Here, we focus on these molecules and summarize their characteristics, ligands, and functions on B cells.

The prognostic and immunomodulatory role of the MMR system in patients with stomach adenocarcinoma

The mismatch repair (MMR) system plays a crucial role in the maintenance of DNA replication fidelity and genomic stability. The clinical value of the MMR molecular marker as an immunotherapy for advanced solid tumors has been documented. However, this therapy is not effective in some patients. This study aimed to develop an MMR-related molecular prognostic model for identifying appropriate populations of stomach adenocarcinoma (STAD) for better treatment outcome. The MMR genes expression data were downloaded from TCGA and CCLE databases. The expression of four MMR genes, construction of a prognostic risk model, and assessment of immune infiltration in STAD were performed using Xiantao online tool. GEPIA2 was used to explore the association of MMR genes expression with clinical stage and overall survival. The frequency and prognostic value of MMR genes in STAD were conducted on the cBioPortal. The MLH1 co-expression network was established based on the LinkedOmics database. This study found that the expression of MSH2, MSH6 and PMS2 was up-regulated in STAD tissues. Moreover, differential MMR genetic expression levels were not significantly correlated with the clinical stages of STAD. Besides, no significant difference in PFS or OS was observed in STAD patients with or without MMR genetic alteration. Moreover, MLH1 and MSH2 were used to establish a prognostic risk model. The immune infiltration levels of most immune cells were upregulated in the high-risk group with elevated expression of PDCD1 and low TMB score. Finally, we found that MLH1 was an independent predictor of STAD prognosis among the four MMR genes. An MMR-related prognostic model for STAD was constructed based on genes. This model provides a new therapeutic concept for the diagnosis and treatment of STAD.

Amelioration of experimental autoimmune encephalomyelitis by exogenous soluble PD-L1 is associated with restraining dendritic cell maturation and CCR7-mediated migration

Dendritic cells (DCs) orchestrate both immune activation and immune tolerance in multiple sclerosis (MS). Manipulating the phenotypes and functions of DCs to boost their tolerogenic potential is an appealing strategy for treating MS and its animal model experimental autoimmune encephalomyelitis (EAE). Programmed cell death 1 (PD-1) delivers the immunoinhibitory signals by interacting with PD-1 ligand 1 (PD-L1), which plays a critical role in maintaining immune tolerance. So far, the effects of PD-1/PD-L1 signalling activation on DCs in EAE are poorly understood. Here, the administration of soluble PD-L1 (sPD-L1) protein significantly alleviated the clinical symptoms of myelin oligodendrocyte glycoprotein (MOG)-induced EAE, and inhibited the expression of cluster of differentiation (CD)86, C-C motif chemokine receptor 7 (CCR7) as well as CCR7-mediated trafficking of splenic DCs, accompanied by enhancing their phagocytosis. The impact of sPD-L1 on the surface morphology and mechanical properties of DCs was investigated at the nanoscale, using scanning electron microscope and atomic force microscope. The treatment of sPD-L1 was found to mitigate morphological maturation and biomechanical alterations, specifically in terms of adhesion and elasticity, in bone marrow-derived DCs from EAE. Taken together, our findings suggest that application of exogenous sPD-L1 has a marked suppressive effect on the maturation and migration of DCs in EAE. PD-L1 administration may be a promising therapy for EAE and for MS in the future.

Optimal timing of anti-PD-1 antibody combined with chemotherapy administration in patients with NSCLC

BACKGROUND

Anti-programmed cell death 1 (PD-1) antibody combined with chemotherapy simultaneously is regarded as the standard treatment for patients with advanced non-small cell lung cancer (NSCLC) by current clinical guidelines. Different immune statuses induced by chemotherapy considerably affect the synergistic effects of the chemo-anti-PD-1 combination. Therefore, it is necessary to determine the optimal timing of combination treatment administration.

METHODS

The dynamic immune status induced by chemotherapy was observed in paired peripheral blood samples of patients with NSCLC using flow cytometry and RNA sequencing. Ex vivo studies and metastatic lung carcinoma mouse models were used to evaluate immune activity and explore the optimal combination timing. A multicenter prospective clinical study of 170 patients with advanced NSCLC was performed to assess clinical responses, and systemic immunity was assessed using omics approaches.

RESULTS

PD-1 expression on CD8+ T cells was downregulated on day 1 (D1) and D2, but recovered on D3 after chemotherapy administration, which is regulated by the calcium influx-P65 signaling pathway. Programmed cell death 1 ligand 1 expression in myeloid-derived suppressor cells was markedly reduced on D3. RNA sequencing analysis showed that T-cell function began to gradually recover on D3 rather than on D1. In addition, ex vivo and in vivo studies have shown that anti-PD-1 treatment on D3 after chemotherapy may enhance the antitumor response and considerably inhibit tumor growth. Finally, in clinical practice, a 3-day-delay sequential combination enhanced the objective response rate (ORR, 68%) and disease control rate (DCR, 98%) compared with the simultaneous combination (ORR=37%; DCR=81%), and prolonged progression-free survival to a greater extent than the simultaneous combination. The new T-cell receptor clones were effectively expanded, and CD8+ T-cell activity was similarly recovered.

CONCLUSIONS

A 3-day-delay sequential combination might increase antitumor responses and clinical benefits compared with the simultaneous combination.

Programmable Circular Multispecific Aptamer-Drug Engager to Broadly Boost Antitumor Immunity

Safely and effectively harnessing innate immunity to boost cancer immunotherapy is promising yet challenging. Hence, we have developed a series of programmable aptamer-based multispecific engagers by encoding various artificial aptamer-drug codons with DNA-templated polymerization, aiming to broadly boost innate and adaptive immunity for antitumor therapy. All circular single-stranded multivalent aptamer-drug conjugates (os-mvApDCs) had a dendritic structure, precise size, and excellent stability, enabling prolonged blood circulation, targeted tumor accumulation, and rapid multireceptor-mediated endocytosis. A trispecific engager (Sl/Pd/Mjos-mvApDCsSMT), targeting PD-1 on CD8+ T cells and PD-L1/c-Met on tumor cells, recruited large amounts of immune cells into the tumor and released cytotoxic MMAE and immunomodulators, inducing severe cell death and broad activation of innate immunity. When combined with the αPD-1 blockade, there was a significant increase in the number of CD8+ T cells (10-fold increase versus untreated control) engaged and expanded in the tumor, exhibiting potent function (IFN-γ+/GzmB+) and low exhaustion (PD-1+TIM-3+). The orchestrated innate and adaptive immunity effectively eliminated immunosuppressive MDSCs, Tregs, and M2-like macrophages in tumors and promoted the maturation of dendritic cells (DCs) in the draining lymph nodes, resulting in robust and durable systemic antitumor efficacy, with 7 out of 8 mice surviving over 60 days. Our programmable DNA-templated printing technology enables the rational design of multispecific therapeutics with modular composition and function but minimal production issues, providing a versatile tool for the development of multifunctional personalized medicine.

Case report: Non-invasive cyto-salivary sampling and biomarker detection via ELISA versus histopathology for diagnosing oral potentially malignant disorders - Insights from a case-control study

Oral leukoplakia is classified among oral potentially malignant disorders (OPMDs) by the World Health Organization (WHO). The visual oral examination (VOE) is the most used method for identifying lesions in their early stages. Given that the diagnosis of oral cancer is often late, there is an urgent need for early detection and examination of oral lesions. Surgical biopsy represents the gold standard as a diagnostic method, but because it is invasive, it cannot be repeated for periodic checks. We report the case of a lesion on the buccal mucosa of a 65-year-old male patient with a malignant appearance. The patient underwent a novel non-invasive cyto-salivary sampling and ELISA immunoassay for tumor biomarker detection and biopsy with histopathological analysis. The rapid ELISA test results excluded signs of malignancy, providing valuable insights into the lesion's immunophenotypic profile, which were consistent with the histopathological examination findings. This case report highlights the clinical and histopathological characteristics of a lesion with the aspect of Proliferative Verrucous Leukoplakia (PVL), emphasizing its challenging diagnosis and management. The integration of non-invasive cytobrush sampling with biomarker analysis proved valuable in detecting specific tumor biomarkers, potentially indicating ongoing tumor transformation. Monitoring these markers over time could enhance early detection and management strategies, thereby improving patient outcomes. This approach underscores the utility of non-invasive techniques in phenotyping oral lesions and supporting clinical decision-making in oral medicine.

Staphyloccocus aureus biofilm, in absence of planktonic bacteria, produces factors that activate counterbalancing inflammatory and immune-suppressive genes in human monocytes

Staphyloccocus aureus (S. aureus) is a major bacterial pathogen in orthopedic periprosthetic joint infection (PJI). S. aureus forms biofilms that promote persistent infection by shielding bacteria from immune cells and inducing an antibiotic-tolerant metabolic state. We developed an in vitro system to study S. aureus biofilm interactions with primary human monocytes in the absence of planktonic bacteria. In line with previous in vivo data, S. aureus biofilm induced expression of inflammatory genes such as TNF and IL1B, and their anti-inflammatory counter-regulator IL10. S. aureus biofilm also activated expression of PD-1 ligands, and IL-1RA, molecules that have the potential to suppress T cell function or differentiation of protective Th17 cells. Gene induction did not require monocyte:biofilm contact and was mediated by a soluble factor(s) produced by biofilm-encased bacteria that was heat resistant and >3 kD in size. Activation of suppressive genes by biofilm was sensitive to suppression by Jak kinase inhibition. These results support an evolving paradigm that biofilm plays an active role in modulating immune responses, and suggest this occurs via production of a soluble vita-pathogen-associated molecular pattern, a molecule that signals microbial viability. Induction of T cell suppressive genes by S. aureus biofilm provides insights into mechanisms that can suppress T cell immunity in PJI.

Pharmacokinetics, Safety, and Immunogenicity of a Biosimilar of Nivolumab (LY01015): A Randomized, Double-Blind, Parallel-Controlled Phase I Clinical Trial in Healthy Chinese Male Subjects

BACKGROUND

Nivolumab (Opdivo®) is the first anti-PD-1 antibody approved in the world. LY01015 is a potential biosimilar of nivolumab.

OBJECTIVES

This phase I study aimed to establish the pharmacokinetic equivalence between LY01015 and the original investigational nivolumab (Opdivo®) in healthy Chinese male subjects. Additionally, safety and immunogenicity were assessed.

PATIENTS AND METHODS

A randomized, double-blind, parallel-controlled, phase I trial was conducted with 176 healthy male adults receiving a single intravenous infusion of LY01015 or nivolumab at 0.3 mg/kg. Pharmacokinetics, safety, and immunogenicity were evaluated over a 99-day period. The primary pharmacokinetics endpoint was AUC0-∞, and the secondary pharmacokinetic endpoints included AUC0-t and Cmax. Pharmacokinetic bioequivalence was confirmed using standard equivalence margins of 80.00-125.00%.

RESULTS

This study is the first to report on the pharmacokinetics, safety, and immunogenicity of Opdivo® in healthy individuals. The pharmacokinetics profiles of LY01015 and Opdivo® were found to be comparable. The geometric mean ratios (90% confidence intervals) for the AUC0-∞, AUC0-t, and Cmax of LY01015 to Opdivo® were 94.49% (90.29-98.88%), 94.92% (88.73-101.54%), and 96.55% (93.32-99.90%), respectively, falling within the conventional bioequivalence criteria of 80.00-125.00%. The safety and immunogenicity were also comparable between the two groups.

CONCLUSIONS

LY01015 demonstrated highly similar pharmacokinetics to nivolumab in healthy Chinese male subjects. Both drugs exhibited comparable safety and immunogenicity profiles.

TRIAL REGISTRATION

This trial is registered at the Chinese Clinical Trial Registry website ( https://www.chictr.org.cn/ #ChiCTR2200064771).

Collagen extracellular matrix promotes gastric cancer immune evasion by activating IL4I1-AHR signaling

BACKGROUND

Gastric cancer (GC) remains a significant global health challenge with poor prognosis, partly due to its ability to evade the immune system. The extracellular matrix (ECM), particularly collagen, plays a crucial role in tumor immune evasion, but the underlying mechanisms are not fully understood. This study investigates the role of collagen ECM in promoting immune evasion in gastric cancer by activating the IL4I1-AHR signaling pathway.

METHODS

We cultured gastric cancer cells in 3D collagen gels and assessed their immune evasion capabilities by co-culturing with HER2-specific CAR-T cells. The expression of IL4I1 and its metabolites was analyzed, and the role of integrin αvβ1 in mediating the effects of collagen was explored. Additionally, the impact of IL4I1-induced AHR activation on CAR-T cell exhaustion was evaluated, both in vitro and in vivo.

RESULTS

We found that gastric cancer cells cultured on collagen exhibited increased resistance to CAR-T cell cytotoxicity, which was associated with upregulated immune checkpoint molecules and downregulated effector cytokines on CAR-T cells. This was linked to increased IL4I1 expression, which was further induced by integrin αvβ1 signaling within the 3D collagen environment. IL4I1 metabolites, particularly KynA, promoted CAR-T cell exhaustion by activating the AHR pathway, leading to decreased cytotoxicity and tumor growth inhibition.

CONCLUSIONS

Our study reveals a novel mechanism by which the collagen ECM facilitates immune evasion in gastric cancer through the activation of IL4I1-AHR signaling, contributing to CAR-T cell exhaustion. Targeting this pathway could potentially enhance the efficacy of CAR-T cell therapy in gastric cancer.

Influencing immunity: role of extracellular vesicles in tumor immune checkpoint dynamics

Immune checkpoint proteins (ICPs) serve as critical regulators of the immune system, ensuring protection against damage due to overly activated immune responses. However, within the tumor environment, excessive ICP activation weakens antitumor immunity. Despite the development of numerous immune checkpoint blockade (ICB) drugs in recent years, their broad application has been inhibited by uncertainties about their clinical efficacy. A thorough understanding of ICP regulation in the tumor microenvironment is essential for advancing the development of more effective and safer ICB therapies. Extracellular vesicles (EVs), which are pivotal mediators of cell-cell communication, have been extensively studied and found to play key roles in the functionality of ICPs. Nonetheless, a comprehensive review summarizing the current knowledge about the crosstalk between EVs and ICPs in the tumor environment is lacking. In this review, we summarize the interactions between EVs and several widely studied ICPs as well as their potential clinical implications, providing a theoretical basis for further investigation of EV-related ICB therapeutic approaches.

PD-1 immunology in the kidneys: a growing relationship

In recent years, knowledge regarding immune regulation has expanded rapidly, and major advancements have been made in immunotherapy for immune-associated disorders, particularly cancer. The programmed cell death 1 (PD-1) pathway is a cornerstone in immune regulation. It comprises PD-1 and its ligands mediating immune tolerance mechanisms and immune homeostasis. Accumulating evidence demonstrates that the PD-1 axis has a crucial immunosuppressive role in the tumor microenvironment and autoimmune diseases. PD-1 receptors and ligands on immune cells and renal parenchymal cells aid in maintaining immunological homeostasis in the kidneys. Here, we present a comprehensive review of PD-1 immunology in various kidney disorders, including renal cell carcinoma, glomerulonephritis, kidney transplantation, renal aging, and renal immune-related adverse events secondary to PD-1 immunotherapy.

Landscape of epithelial cell subpopulations in the human esophageal squamous cell carcinoma microenvironment

Aims

We sought to reveal the landscape of epithelial cell subpopulations in the human esophageal squamous cell carcinoma microenvironment and investigate their parts on esophageal squamous carcinoma (ESCC) development.

Background

Epithelial cells play an important role in the occurrence and development of ESCC through multiple mechanisms. While the landscape of epithelial cell subpopulations in ESCC, remains unclear.

Objective

Exploring the role of epithelial cell subpopulations in ESCC progression.

Methods

Seurat R package was used for single-cell RNA sequencing (scRNA-seq) data filtering, dimensionality reduction, clustering and differentially expressed genes analysis. Cellmarker database was adopted for cell cluster annotation. Functional enrichment analysis was carried out by Gene Ontology (GO) analysis. InferCNV package was conducted for copy number variation (CNV) of epithelial cell subpopulations in all chromosomal regions. Pseudotime trajectory analysis was implemented for exploring differentiation trajectory of epithelial cells subgroups during the cancer progression. CellChat analysis was used for probing the interactions between epithelial cells and NK/T cells. cellular experiments were performed using Quantitative Real-Time Polymerase Chain Reaction (RT-qPCR), Wound-Healing Assay and transwell.

Results

11 major cell subpopulations were identified in ESCC and adjunct tissues. Further reclassification of epithelial cells uncovered 4 subpopulations. Enrichment analysis revealed that highly expressed genes in 4 epithelial cell subpopulations were related to cell proliferation, immune response and angiogenesis. CNV analysis found that UBD + epithelial cells and GAS2L3+ epithelial cells had a higher proportion of CNV. Cell differentiation trajectories disclosed that KRT6C+ and GSTA1+ epithelial cells were in an intermediate state of differentiation, while UBD+ and GAS2L3+ epithelial cells are in an end state of differentiation during ESCC progression. Finally, we found that four epithelial cell subpopulations all inhibited NK/T cells through NECTIN2-TIGIT and CLEC2B-KLRB1. Low ATF3 and DDIT3 mRNA expression inhibited ESCC cell migration and invasion.

Conclusion

Here, we obtained a through epithelial cell atlas of ESCC at single-cell resolution, explored the role of epithelial cell in ESCC progression, and unveiled immunosuppressive signals to NK/T cells in promoting ESCC. Our findings expand the comprehension of epithelial cells and offer a theoretical guidance for future anti-epithelial cell treatment of ESCC.

Reshaping the tumor microenvironment by degrading glycoimmune checkpoints Siglec-7 and -9

Cancer treatment has been rapidly transformed by the development of immune checkpoint inhibitors targeting CTLA-4 and PD-1/PD-L1. However, many patients fail to respond, especially those with an immunosuppressive tumor microenvironment (TME), suggesting the existence of additional immune checkpoints that act through orthogonal mechanisms. Sialic acid-binding immunoglobulin-like lectin (Siglec)-7 and -9 are newly designated glycoimmune checkpoints that are abundantly expressed by tumor-infiltrating myeloid cells. We discovered that T cells express only basal levels of Siglec transcripts; instead, they acquire Siglec-7 and -9 from interacting myeloid cells in the TME via trogocytosis, which impairs their activation and effector function. Mechanistically, Siglec-7 and -9 suppress T cell activity by dephosphorylating T cell receptor (TCR)-related signaling cascades. Using sulfur fluoride exchange (SuFEx) click chemistry, we developed a ligand that binds to Siglec-7 and -9 with high-affinity and exclusive specificity. Using this ligand, we constructed a Siglec-7/9 degrader that targets membrane Siglec-7 and -9 to the lysosome for degradation. Administration of this degrader induced efficient Siglec degradation in both T cells and myeloid cells in the TME. We found that Siglec-7/9 degradation has a negligible effect on macrophage phagocytosis, but significantly enhances T cell anti-tumor immunity. The degrader, particularly when combined with anti-CTLA-4, enhanced macrophage antigen presentation, reshaped the TME, and resulted in long-lasting T cell memory and excellent tumor control in multiple murine tumor models. These findings underscore the need to consider exogenous checkpoints acquired by T cells in the TME when selecting specific checkpoint blockade therapy to enhance T cell immunity.

Mapping spatial organization and genetic cell-state regulators to target immune evasion in ovarian cancer

The drivers of immune evasion are not entirely clear, limiting the success of cancer immunotherapies. Here we applied single-cell spatial and perturbational transcriptomics to delineate immune evasion in high-grade serous tubo-ovarian cancer. To this end, we first mapped the spatial organization of high-grade serous tubo-ovarian cancer by profiling more than 2.5 million cells in situ in 130 tumors from 94 patients. This revealed a malignant cell state that reflects tumor genetics and is predictive of T cell and natural killer cell infiltration levels and response to immune checkpoint blockade. We then performed Perturb-seq screens and identified genetic perturbations-including knockout of PTPN1 and ACTR8-that trigger this malignant cell state. Finally, we show that these perturbations, as well as a PTPN1/PTPN2 inhibitor, sensitize ovarian cancer cells to T cell and natural killer cell cytotoxicity, as predicted. This study thus identifies ways to study and target immune evasion by linking genetic variation, cell-state regulators and spatial biology.

Targeting PD-1/PD-L1 in tumor immunotherapy: Mechanisms and interactions with host growth regulatory pathways

Tumor immunotherapy has garnered considerable attention, emerging as a new standard of care in cancer treatment. The conventional targets, such as VEGF and EGFR, have been extended to others including BRAF and PD-1/PD-L1, which have shown significant potential in recent cancer treatments. This review aims to succinctly overview the impact and mechanisms of therapies that modulate PD-1/PD-L1 expression by targeting VEGF, EGFR, LAG-3, CTLA-4 and BRAF. We investigated how modulation of PD-1/PD-L1 expression impacts growth factor signaling, shedding light on the interplay between immunomodulatory pathways and growth factor networks within the tumor microenvironment. By elucidating these interactions, we aim to provide insights into novel potential synergistic therapeutic strategies for cancer immunotherapy.

Discovery and Evaluation of TLR-Targeted Immune Agonists

Toll-like receptor (TLR) activation converts immunologically inactive tumors into immunologically active tumors by activating tumor residing antigen-presenting cells and recruitment of cytotoxic T lymphocytes. Targeted immune agonists (TIAs) are antibody drug conjugates with small-molecule TLR agonist payloads. The mechanism of action of TIAs involves tumor antigen recognition, Fcγ-receptor-dependent phagocytosis, and TLR-mediated activation to drive tumor killing by myeloid cells. Several new low DAR anti-HER2 TIAs conjugated with novel TLR7 or dual-TLR7/8 agonists with cleavable and noncleavable linkers were synthesized and profiled. In vitro studies demonstrated that these TIAs activate myeloid cells only in the presence of antigen-expressing cancer cells. Evaluation in ELISpot-based assays confirmed the low immunogenicity of these constructs. Systemic administration of the novel TIAs in tumor-bearing mice resulted in tumor reduction at low doses. These results provide a strong rationale for further development of the TIAs as a novel class of immunotherapeutics.

Cryoablation Does Not Significantly Contribute to Systemic Effector Immune Responses in a Poorly Immunogenic B16F10 Melanoma Model

PURPOSE

Cryoablation is a minimally invasive procedure implemented to destroy solid tumors. It also results in the release of tumor antigens into the systemic circulation. Preclinical studies using immunogenic tumor models have shown that cryoablation evokes antitumor immune responses. The mechanisms by which cryoablation impacts immune responses in poorly immunogenic tumors have not been sufficiently explored.

EXPERIMENTAL DESIGN

We used a bilateral B16F10 melanoma model devoid of strong immunogenic antigens. Cryoablation-induced effector immune responses were investigated, also in combination with a peritumoral STING agonist and systemic anti-PD-1. Selective immune cell depletion, T-cell migration arrest, in vivo T-cell transplantation, and cryoablation versus surgical removal techniques were used to determine the contribution of cryoablation and immunotherapies to systemic antitumor effector immune responses.

RESULTS

Treatment of a tumor with cryoablation + STING agonist + anti-PD-1 resulted in the rejection of unablated, contralateral tumors. Depletion studies demonstrated that tumor rejection is essentially dependent on CD8+ T cells. T-cell arrest in the lymph nodes had no effect on the rejection process. Splenic CD8+ T cells isolated from cryoablation-treated mice with B16F10 melanoma, upon transplantation into melanoma-bearing recipients, did not impact the recipient's tumor growth. Finally, comparison of cryoablation + STING agonist + anti-PD-1 versus surgery + STING agonist + anti-PD-1 in the bilateral tumor model showed no difference in the rejection of contralateral tumors.

CONCLUSIONS

Cryoablation does not significantly contribute to systemic antitumor effector immune responses in a B16F10 melanoma model. Cryoablation primarily performs tumor debulking, and immunotherapy functions independently of cryoablation in eliciting antitumor effector immune responses.

SHISA3 Reprograms Tumor-Associated Macrophages Toward an Antitumoral Phenotype and Enhances Cancer Immunotherapy

The main challenge for immune checkpoint blockade (ICB) therapy lies in immunosuppressive tumor microenvironment (TME). Repolarizing M2-like tumor-associated macrophages (TAMs) into inflammatory M1 phenotype is a promising strategy for cancer immunotherapy. Here, this study shows that the tumor suppressive protein SHISA3 regulates the antitumor functions of TAMs. Local delivery of mRNA encoding Shisa3 enables cancer immunotherapy by reprogramming TAMs toward an antitumoral phenotype, thus enhancing the efficacy of programmed cell death 1 (PD-1) antibody. Enforced expression of Shisa3 in TAMs increases their phagocytosis and antigen presentation abilities and promotes CD8+ T cell-mediated antitumor immunity. The expression of SHISA3 is induced by damage/pathogen-associated molecular patterns (DAMPs/PAMPs) in macrophages via nuclear factor-κB (NF-κB) transcription factors. Reciprocally, SHISA3 forms a complex with heat shock protein family A member 8 (HSPA8) to activate NF-κB signaling thus maintaining M1 polarization of macrophages. Knockout Shisa3 largely abolishes the antitumor efficacy of combination immunotherapy with Toll-like receptor 4 (TLR4) agonist monophosphoryl lipid A (MPLA) and PD-1 antibody. It further found that higher expression of SHISA3 in antitumoral TAMs is associated with better overall survival in lung cancer patients. Taken together, the findings describe the role of SHISA3 in reprogramming TAMs that ameliorate cancer immunotherapy.

Non-cell-autonomous suppression of tumor growth by RECK in immunocompetent mice

RECK is a candidate tumor suppressor gene isolated as a gene that induces flat reversion in a cell line transformed by the KRAS oncogene. Since RECK knockout mice die in utero, they are not suitable for studying the effects of RECK on tumor formation. In this study, we found an increased incidence of spontaneous pulmonary adenomas in mice with reduced RECK expression (RECK-Hypo mice). To evaluate the effects of RECK expressed by either tumor cells or host cells on tumor growth, we established a tumorigenic cell line (MKER) from the kidney of a C57BL/6 mouse and performed syngeneic transplantation experiments. Our results indicate that when RECK expression is low in host cells, transplanted MKER cells grow faster and kill the animal more rapidly. Since RECK is required for the formation of proper fibrillin fibers that serve as a tissue reservoir for precursors of TGFβ-family cytokines, we assessed the levels of TGFβ1 in the peripheral blood. We found a significant increase in TGFβ1 in RECK-Hypo mice compared to wild-type mice. We also found that the proportion of FOXP3-positive regulatory T (Treg) cells among splenocytes was higher in RECK-Hypo mice compared to the control mice. Furthermore, the number of FOXP3-positive cells in spontaneous hematopoietic neoplasms in the lungs as well as tumors that formed after MKER transplantation was significantly higher in RECK-Hypo mice compared to the control mice. These findings indicate that RECK-mediated tumor suppression involves a non-cell-autonomous mechanism and that possible roles of TGFβ1 and Treg cells in such a mechanism warrant further study.

Nuclear HMGB1 is critical for CD8 T cell IFN-γ production and anti-tumor immunity

HMGB1 (high-mobility group box-1) has been extensively studied as a damage-associated molecular pattern, with secreted cytokine function. However, its regulation on T cells, especially the function in the nucleus, has not been elucidated. Here, we use conditional knockout (HMGB1-f/f; CD2-cre) mice and find that HMGB1 potentiates the proliferation and interferon gamma (IFN-γ) expression of CD8 T cells rather than CD4 T cells. Notably, nuclear, but not secreted, HMGB1 supports the expression of IFN-γ in CD8 T cells via directly regulating the activity of Eomes, the transcription factor for IFN-γ. Functional study shows that HMGB1 promotes the anti-tumor ability of CD8 T cells in vitro and in vivo. Finally, tumor environmental interleukin-7 promotes HMGB1 and IFN-γ production via fatty acid oxidation in CD8 T cells. Overall, we identify the role of nuclear HMGB1 in CD8 T cell differentiation and demonstrate that it plays an important role in the anti-tumor programs of CD8 T cells.

Resident memory T cells and cancer

Tissue-resident memory T (TRM) cells positively correlate with cancer survival, but the anti-tumor mechanisms underlying this relationship are not understood. This review reconciles these observations, summarizing concepts of T cell immunosurveillance, fundamental TRM cell biology, and clinical observations on the role of TRM cells in cancer and immunotherapy outcomes. We also discuss emerging strategies that utilize TRM-phenotype cells for patient diagnostics, staging, and therapy. Current challenges are highlighted, including a lack of standardized T cell nomenclature and our limited understanding of relationships between T cell markers and underlying tumor biology. Existing findings are integrated into a summary of the field while emphasizing opportunities for future research.

Mapping the single cell spatial immune landscapes of the melanoma microenvironment

Melanoma is a highly immunogenic malignancy with an elevated mutational burden, diffuse lymphocytic infiltration, and one of the highest response rates to immune checkpoint inhibitors (ICIs). However, over half of all late-stage patients treated with ICIs will either not respond or develop progressive disease. Spatial imaging technologies are being increasingly used to study the melanoma tumor microenvironment (TME). The goal of such studies is to understand the complex interplay between the stroma, melanoma cells, and immune cell-types as well as their association with treatment response. Investigators seeking a better understanding of the role of cell location within the TME and the importance of spatial expression of biomarkers are increasingly turning to highly multiplexed imaging approaches to more accurately measure immune infiltration as well as to quantify receptor-ligand interactions (such as PD-1 and PD-L1) and cell-cell contacts. CyTOF-IMC (Cytometry by Time of Flight - Imaging Mass Cytometry) has enabled high-dimensional profiling of melanomas, allowing researchers to identify complex cellular subpopulations and immune cell interactions with unprecedented resolution. Other spatial imaging technologies, such as multiplexed immunofluorescence and spatial transcriptomics, have revealed distinct patterns of immune cell infiltration, highlighting the importance of spatial relationships, and their impact in modulating immunotherapy responses. Overall, spatial imaging technologies are just beginning to transform our understanding of melanoma biology, providing new avenues for biomarker discovery and therapeutic development. These technologies hold great promise for advancing personalized medicine to improve patient outcomes in melanoma and other solid malignancies.

PD1/PD-L1 blockade in clear cell renal cell carcinoma: mechanistic insights, clinical efficacy, and future perspectives

The advent of PD1/PD-L1 inhibitors has significantly transformed the therapeutic landscape for clear cell renal cell carcinoma (ccRCC). This review provides an in-depth analysis of the biological functions and regulatory mechanisms of PD1 and PD-L1 in ccRCC, emphasizing their role in tumor immune evasion. We comprehensively evaluate the clinical efficacy and safety profiles of PD1/PD-L1 inhibitors, such as Nivolumab and Pembrolizumab, through a critical examination of recent clinical trial data. Furthermore, we discuss the challenges posed by resistance mechanisms to these therapies and potential strategies to overcome them. We also explores the synergistic potential of combination therapies, integrating PD1/PD-L1 inhibitors with other immunotherapies, targeted therapies, and conventional modalities such as chemotherapy and radiotherapy. In addition, we examine emerging predictive biomarkers for response to PD1/PD-L1 blockade and biomarkers indicative of resistance, providing a foundation for personalized therapeutic approaches. Finally, we outline future research directions, highlighting the need for novel therapeutic strategies, deeper mechanistic insights, and the development of individualized treatment regimens. Our work summarizes the latest knowledge and progress in this field, aiming to provide a valuable reference for improving clinical efficacy and guiding future research on the application of PD1/PD-L1 inhibitors in ccRCC.

Multiple myeloma: signaling pathways and targeted therapy

Multiple myeloma (MM) is the second most common hematological malignancy of plasma cells, characterized by osteolytic bone lesions, anemia, hypercalcemia, renal failure, and the accumulation of malignant plasma cells. The pathogenesis of MM involves the interaction between MM cells and the bone marrow microenvironment through soluble cytokines and cell adhesion molecules, which activate various signaling pathways such as PI3K/AKT/mTOR, RAS/MAPK, JAK/STAT, Wnt/β-catenin, and NF-κB pathways. Aberrant activation of these pathways contributes to the proliferation, survival, migration, and drug resistance of myeloma cells, making them attractive targets for therapeutic intervention. Currently, approved drugs targeting these signaling pathways in MM are limited, with many inhibitors and inducers still in preclinical or clinical research stages. Therapeutic options for MM include non-targeted drugs like alkylating agents, corticosteroids, immunomodulatory drugs, proteasome inhibitors, and histone deacetylase inhibitors. Additionally, targeted drugs such as monoclonal antibodies, chimeric antigen receptor T cells, bispecific T-cell engagers, and bispecific antibodies are being used in MM treatment. Despite significant advancements in MM treatment, the disease remains incurable, emphasizing the need for the development of novel or combined targeted therapies based on emerging theoretical knowledge, technologies, and platforms. In this review, we highlight the key role of signaling pathways in the malignant progression and treatment of MM, exploring advances in targeted therapy and potential treatments to offer further insights for improving MM management and outcomes.

Upregulation of PD-1 and its ligands and expansion of T peripheral helper cells in the nephritic kidneys of lupus-prone BXSB-Yaa mice

OBJECTIVE

This study aimed to investigate the role of the programmed cell death protein 1 (PD-1) pathway and T peripheral helper (Tph) cells in the pathogenesis of lupus nephritis using lupus-prone BXSB-Yaa mice.

METHODS

Male BXSB-Yaa mice and age-matched male C57BL/6 mice were used. The expression of PD-1 and its ligands (programmed cell death 1 ligand-1, PD-L1 and programmed cell death 1 ligand-2, PD-L2) and the phenotypes of kidney-derived cells and splenocytes expressing these molecules were analyzed by immunofluorescence and flow cytometry.

RESULTS

Nephritis spontaneously developed in 16-week-old but not in 8-week-old BXSB-Yaa or C57BL/6 mice. PD-1 was expressed on CD4+ mononuclear cells (MNCs) that infiltrated the glomeruli of 16-week-old BXSB-Yaa mice. The frequency of CD4+PD-1+CXCR5-ICOS+ kidney-derived Tph cells was higher in 16-week-old than in 8-week-old BXSB-Yaa and C57BL/6 mice, whereas the frequency of CD4+PD-1+CXCR5+ICOS+ kidney-derived T follicular helper (Tfh) cells was not significantly different between the mice. PD-L1 was constitutively expressed in the renal tubules. PD-L2 was expressed in the glomeruli of 16-week-old BXSB-Yaa mice. The frequency of PD-L1highCD11c+CD3-CD19- and PD-L2+CD11c+CD3-CD19- kidney-derived MNCs in 16-week-old BXSB-Yaa mice was significantly higher than that of the control mice. The percentage of kidney-derived Tph cells but not Tfh cells was correlated with the urinary protein levels in the nephritic mice.

CONCLUSION

The results of this study suggest that kidney-infiltrating PD-1+ Tph cells expanded concomitantly with the upregulation of PD-L1 and PD-L2 in the kidneys and the progression of lupus nephritis.

JAKing up immunity

Janus kinase (JAK) inhibitors improve antitumor responses.

Immuno-protective vesicle-crosslinked hydrogel for allogenic transplantation

The longevity of grafts remains a major challenge in allogeneic transplantation due to immune rejection. Systemic immunosuppression can impair graft function and can also cause severe adverse effects. Here, we report a local immuno-protective strategy to enhance post-transplant persistence of allografts using a mesenchymal stem cell membrane-derived vesicle (MMV)-crosslinked hydrogel (MMV-Gel). MMVs are engineered to upregulate expression of Fas ligand (FasL) and programmed death ligand 1 (PD-L1). The MMVs are retained within the hydrogel by crosslinking. The immuno-protective microenvironment of the hydrogel protects allografts by presenting FasL and PD-L1. The binding of these ligands to T effector cells, the dominant contributors to graft destruction and rejection, results in apoptosis of T effector cells and generation of regulatory T cells. We demonstrate that implantation with MMV-Gel prolongs the survival and function of grafts in mouse models of allogeneic pancreatic islet cells and skin transplantation.

Nonsymmetrically Substituted 1,1'-Biphenyl-Based Small Molecule Inhibitors of the PD-1/PD-L1 Interaction

Therapeutic antibodies directed against either programmed cell death-1 protein (PD-1) or its ligand PD-L1 have demonstrated efficacy in the treatment of various cancers. In contrast with antibodies, small molecules have the potential for increased tissue penetration; better pharmacology; and therefore, improved antitumor activity. A series of nonsymmetric C2 inhibitors were synthesized and evaluated for PD-1/PD-L1 interaction inhibition. These compounds induced PD-L1 dimerization and effectively blocked PD-L1/PD-1 interaction in a homogeneous time-resolved fluorescence (HTRF) assay with most inhibitors exhibiting IC50 values in the single-digit nM range and below. Their high inhibitory potency was also demonstrated in a cell-based coculture PD-1 signaling assay where 2 exhibited an EC50 inhibitory activity of 21.8 nM, which approached that of the PD-L1 antibody durvalumab (EC50 = 0.3-1.8 nM). Structural insight into how these inhibitors interact with PD-L1 was gained by using NMR and X-ray cocrystal structure studies. These data support further preclinical evaluation of these compounds as antibody alternatives.

PD1 inhibits PKCθ-dependent phosphorylation of cytoskeleton-related proteins and immune synapse formation

ABSTRACT

The inhibitory surface receptor programmed cell death protein 1 (PD1) is a major target for antibody-based cancer immunotherapies. Nevertheless, a substantial number of patients fail to respond to the treatment or experience adverse effects. An improved understanding of intracellular pathways targeted by PD1 is thus needed to develop better predictive and prognostic biomarkers. Here, via unbiased phosphoproteome analysis of primary human T cells, we demonstrate that PD1 triggering inhibited the phosphorylation and physical association with protein kinase Cθ (PKCθ) of a variety of cytoskeleton-related proteins. PD1 blocked activation and recruitment of PKCθ to the forming immune synapse (IS) in a Src homology-2 domain-containing phosphatase-1/2 (SHP1/SHP2)-dependent manner. Consequently, PD1 engagement led to impaired synaptic phosphorylation of cytoskeleton-related proteins and formation of smaller IS. T-cell receptor induced phosphorylation of the PKCθ substrate and binding partner vimentin was long-lasting and it could be durably inhibited by PD1 triggering. Vimentin phosphorylation in intratumoral T cells also inversely correlated with the levels of the PD1 ligand, PDL1, in human lung carcinoma. Thus, PKCθ and its substrate vimentin represent important targets of PD1-mediated T-cell inhibition, and low levels of vimentin phosphorylation may serve as a biomarker for the activation of the PD1 pathway.

Metabolic regulator LKB1 controls adipose tissue ILC2 PD-1 expression and mitochondrial homeostasis to prevent insulin resistance

Adipose tissue group 2 innate lymphoid cells (ILC2s) help maintain metabolic homeostasis by sustaining type 2 immunity and promoting adipose beiging. Although impairment of the ILC2 compartment contributes to obesity-associated insulin resistance, the underlying mechanisms have not been elucidated. Here, we found that ILC2s in obese mice and humans exhibited impaired liver kinase B1 (LKB1) activation. Genetic ablation of LKB1 disrupted ILC2 mitochondrial metabolism and suppressed ILC2 responses, resulting in exacerbated insulin resistance. Mechanistically, LKB1 deficiency induced aberrant PD-1 expression through activation of NFAT, which in turn enhanced mitophagy by suppressing Bcl-xL expression. Blockade of PD-1 restored the normal functions of ILC2s and reversed obesity-induced insulin resistance in mice. Collectively, these data present the LKB1-PD-1 axis as a promising therapeutic target for the treatment of metabolic disease.

Cancer therapy with antibodies

The greatest challenge in cancer therapy is to eradicate cancer cells with minimal damage to normal cells. Targeted therapy has been developed to meet that challenge, showing a substantially increased therapeutic index compared with conventional cancer therapies. Antibodies are important members of the family of targeted therapeutic agents because of their extraordinarily high specificity to the target antigens. Therapeutic antibodies use a range of mechanisms that directly or indirectly kill the cancer cells. Early antibodies were developed to directly antagonize targets on cancer cells. This was followed by advancements in linker technologies that allowed the production of antibody-drug conjugates (ADCs) that guide cytotoxic payloads to the cancer cells. Improvement in our understanding of the biology of T cells led to the production of immune checkpoint-inhibiting antibodies that indirectly kill the cancer cells through activation of the T cells. Even more recently, bispecific antibodies were synthetically designed to redirect the T cells of a patient to kill the cancer cells. In this Review, we summarize the different approaches used by therapeutic antibodies to target cancer cells. We discuss their mechanisms of action, the structural basis for target specificity, clinical applications and the ongoing research to improve efficacy and reduce toxicity.

Unveiling the promise of PD1/PD-L1: A new dawn in immunotherapy for cholangiocarcinoma

Cholangiocarcinoma (CCA), a rare yet notably aggressive cancer, has experienced a surge in incidence in recent years. Presently, surgical resection remains the most effective curative strategy for CCA. Nevertheless, a majority of patients with CCA are ineligible for surgical removal at the time of diagnosis. For advanced stages of CCA, the combination of gemcitabine and cisplatin is established as the standard chemotherapy regimen. Despite this, treatment efficacy is often hindered by the development of resistance. In recent times, immune checkpoint inhibitors, particularly those that block programmed death 1 and its ligand (PD1/PD-L1), have emerged as promising strategies against a variety of cancers and are being increasingly integrated into the therapeutic landscape of CCA. A growing body of research supports that the use of PD1/PD-L1 monoclonal antibodies in conjunction with chemotherapy may significantly improve patient outcomes. This article seeks to meticulously review the latest studies on PD1/PD-L1 involvement in CCA, delving into their expression profiles, prognostic significance, contribution to oncogenic processes, and their potential clinical utility.

A T-Cell Inspired Sonoporation System Enhances Low-Dose X-Ray-Mediated Pyroptosis and Radioimmunotherapy Efficacy by Restoring Gasdermin-E Expression

Genome editing has the potential to improve the unsatisfactory therapeutic effect of antitumor immunotherapy. However, the cell plasma membrane prevents the entry of almost all free genome-manipulation agents. Therefore, a system can be spatiotemporally controlled and can instantly open the cellular membrane to allow the entry of genome-editing agents into target cells is needed. Here, inspired by the ability of T cells to deliver cytotoxins to cancer cells by perforation, an ultrasound (US)-controlled perforation system (UPS) is established to enhance the delivery of free genome-manipulating agents. The UPS can perforate the tumor cell membrane while maintaining cell viability via a controllable lipid peroxidation reaction. In vitro, transmembrane-incapable plasmids can enter cells and perform genome editing with the assistance of UPS, achieving an efficiency of up to 90%. In vivo, the UPS is biodegradable, nonimmunogenic, and tumor-targeting, enabling the puncturing of tumor cells under US. With the application of UPS-assisted genome editing, gasdermin-E expression in 4T1 tumor-bearing mice is successfully restored, which leads to pyroptosis-mediated antitumor immunotherapy via low-dose X-ray irradiation. This study provides new insights for designing a sonoporation system for genome editing. Moreover, the results demonstrate that restoring gasdermin expression by genome editing significantly improves the efficacy of radioimmunotherapy.

Doxorubicin induces deglycosylation of cancer cell-intrinsic PD-1 by NGLY1

Tumor cells can express the immune checkpoint protein programmed death-1 (PD-1), but how cancer cell-intrinsic PD-1 is regulated in response to cellular stresses remains largely unknown. Here, we uncover a unique mechanism by which the chemotherapy drug doxorubicin (Dox) regulates cancer cell-intrinsic PD-1. Dox upregulates PD-1 mRNA while reducing PD-1 protein levels in tumor cells. Although Dox shortens the PD-1 half-life, it fails to directly induce PD-1 degradation. Instead, we observe that Dox promotes the interaction between peptide-N(4)-(N-acetyl-beta-glucosaminyl)asparagine amidase (NGLY1) and PD-1, facilitating NGLY1-mediated PD-1 deglycosylation and destabilization. The maintenance of PD-1 sensitizes tumor cells to Dox-mediated antiproliferative effects. Our study unveils a regulatory mechanism of PD-1 in response to Dox and highlights a potential role of cancer cell-intrinsic PD-1 in Dox-mediated antitumor effects.

Tracking in situ checkpoint inhibitor-bound target T cells in patients with checkpoint-induced colitis

The success of checkpoint inhibitors (CPIs) for cancer has been tempered by immune-related adverse effects including colitis. CPI-induced colitis is hallmarked by expansion of resident mucosal IFNγ cytotoxic CD8+ T cells, but how these arise is unclear. Here, we track CPI-bound T cells in intestinal tissue using multimodal single-cell and subcellular spatial transcriptomics (ST). Target occupancy was increased in inflamed tissue, with drug-bound T cells located in distinct microdomains distinguished by specific intercellular signaling and transcriptional gradients. CPI-bound cells were largely CD4+ T cells, including enrichment in CPI-bound peripheral helper, follicular helper, and regulatory T cells. IFNγ CD8+ T cells emerged from both tissue-resident memory (TRM) and peripheral populations, displayed more restricted target occupancy profiles, and co-localized with damaged epithelial microdomains lacking effective regulatory cues. Our multimodal analysis identifies causal pathways and constitutes a resource to inform novel preventive strategies.

Cuproptosis: unveiling a new frontier in cancer biology and therapeutics

Copper plays vital roles in numerous cellular processes and its imbalance can lead to oxidative stress and dysfunction. Recent research has unveiled a unique form of copper-induced cell death, termed cuproptosis, which differs from known cell death mechanisms. This process involves the interaction of copper with lipoylated tricarboxylic acid cycle enzymes, causing protein aggregation and cell death. Recently, a growing number of studies have explored the link between cuproptosis and cancer development. This review comprehensively examines the systemic and cellular metabolism of copper, including tumor-related signaling pathways influenced by copper. It delves into the discovery and mechanisms of cuproptosis and its connection to various cancers. Additionally, the review suggests potential cancer treatments using copper ionophores that induce cuproptosis, in combination with small molecule drugs, for precision therapy in specific cancer types.

Immune checkpoints in autoimmune vasculitis

Giant cell arteritis (GCA) is a prototypic autoimmune disease with a highly selective tissue tropism for medium and large arteries. Extravascular GCA manifests with intense systemic inflammation and polymyalgia rheumatica; vascular GCA results in vessel wall damage and stenosis, causing tissue ischemia. Typical granulomatous infiltrates in affected arteries are composed of CD4+ T cells and hyperactivated macrophages, signifying the involvement of the innate and adaptive immune system. Lesional CD4+ T cells undergo antigen-dependent clonal expansion, but antigen-nonspecific pathways ultimately control the intensity and duration of pathogenic immunity. Patient-derived CD4+ T cells receive strong co-stimulatory signals through the NOTCH1 receptor and the CD28/CD80-CD86 pathway. In parallel, co-inhibitory signals, designed to dampen overshooting T cell immunity, are defective, leaving CD4+ T cells unopposed and capable of supporting long-lasting and inappropriate immune responses. Based on recent data, two inhibitory checkpoints are defective in GCA: the Programmed death-1 (PD-1)/Programmed cell death ligand 1 (PD-L1) checkpoint and the CD96/CD155 checkpoint, giving rise to the "lost inhibition concept". Subcellular and molecular analysis has demonstrated trapping of the checkpoint ligands in the endoplasmic reticulum, creating PD-L1low CD155low antigen-presenting cells. Uninhibited CD4+ T cells expand, release copious amounts of the cytokine Interleukin (IL)-9, and differentiate into long-lived effector memory cells. These data place GCA and cancer on opposite ends of the co-inhibition spectrum, with cancer patients developing immune paralysis due to excessive inhibitory checkpoints and GCA patients developing autoimmunity due to nonfunctional inhibitory checkpoints.