Programmed Cell Death Ligand 1 Pathway Research Articles

Discovery of Benzo[d]oxazoles as Novel Dual Small-Molecule Inhibitors Targeting PD-1/PD-L1 and VISTA Pathway.

The blockers of programmed cell death-1 (PD-1)/programmed cell death-ligand 1 (PD-L1) pathway have achieved great clinical success. However, the limited efficacy and low tumor response rate of anti-PD-1/PD-L1 monotherapy limit the clinical application of PD-1/PD-L1 inhibitors. V-domain immunoglobulin suppressor of T-cell activation (VISTA), a novel checkpoint regulator, exhibits potential synergy with PD-1/PD-L1 in enhancing antitumor immunity. Herein, we report the discovery of benzo[d]oxazole B3 as novel dual small-molecule inhibitors targeting PD-1/PD-L1 and VISTA with high PD-1/PD-L1 inhibitory activity and VISTA binding affinity. B3 rescues the immunosuppression of T-cells mediated by PD-L1 and VISTA and activates antitumor immunity effectively. Moreover, B3 could induce degradation of PD-L1 and VISTA in tumor cell. Furthermore, B3 displays significant in vivo antitumor efficacy in a CT26 mouse model. Our results discover B3 as a promising dual PD-1/PD-L1 and VISTA inhibitor, providing a novel therapeutic strategy to overcome the limitations of current anti-PD-1/PD-L1 therapy.

Towards novel small-molecule inhibitors blocking PD-1/PD-L1 pathway: From explainable machine learning models to molecular dynamics simulation

Molecular design of small-molecule inhibitors targeting programmed cell death-1 (PD-1)/programmed cell death ligand-1 (PD-L1) pathway has been recognized as an active research area by the clinical success of cancer immunotherapy. In recent years, using machine learning (ML) methods to accelerate drug design have been confirmed. However, the black box character of ML methods makes model interpretation and ligands optimization obscured. Herein, five explainable ML models were constructed by integrating five ML models with the SHAP method, where these ML models were pretrained with >4000 molecules and their R2 ranged from 0.835 to 0.86 on test set. Subsequently, the explainable ML models were employed to identify the relationship between fragments and bio-activity of a small molecule inhibitor BMS-1166, leading to the modification of BMS-1166 into 60 novel compounds. After consensus docking and ADMET test, 3 small molecules (C27, C52 and C54) with better docking scores and lower toxicity than BMS-1166 were screened out further. Finally, the improved binding affinity of C27, C52 to the PD-L1 dimer was validated by the MD simulation. Overall, this work proposed an efficient protocol on the basis of explainable ML models for designing small-molecule inhibitors targeting PD-1/PD-L1 pathway in a rational way.

Exogenous PD-L1 binds to PD-1 to alleviate and prevent autism-like behaviors in maternal immune activation-induced male offspring mice

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder caused by the interaction of multiple pathogenic factors. Epidemiological studies and animal experiments indicate that maternal immune activation (MIA) is closely related to the development of ASD in offspring. A large number of pro-inflammatory cytokines are transferred from the placenta to the fetal brain during MIA, which impedes fetal neurodevelopment and is accompanied by activation of immune cells and microglia. Programmed cell death protein 1 (PD-1) can be highly expressed on the surface of various activated immune cells, when combined with programmed cell death-ligand 1 (PD-L1), it can activate the PD-1/PD-L1 pathway and exert powerful immunosuppressive effects, suggesting that this immune checkpoint may have the potential to treat MIA-induced ASD. This study combined bioinformatics analysis and experimental validation to explore the efficacy of Fc-fused PD-L1 (PD-L1-Fc) in treating MIA-induced ASD. Bioinformatics analysis results showed that in human placental inflammation, IL-6 was upregulated, T cells proliferated significantly, and the PD-1/PD-L1 pathway was significantly enriched. The experimental results showed that intraperitoneal injection of poly(I:C) induced MIA in pregnant mice resulted in significant expression of IL-6 in their serum, placenta, and fetal brain. At the same time, the expression of PD-1 and PD-L1 in the placenta and fetal brain increased, CD4+ T cells in the spleen were significantly activated, and PD-1 expression increased. Their offspring mice exhibited typical ASD-like behaviors. In vitro experiments on primary microglia of offspring mice have confirmed that the expression of IL-6, PD-1, and PD-L1 is significantly increased, and PD-L1-Fc effectively reduced their expression levels. In the prefrontal cortex of MIA offspring mice, there was an increase in the expression of IL-6, PD-1, and PD-L1; activation of microglial cells, and colocalization with PD-1. Then we administered brain stereotaxic injections of PD-L1-Fc to MIA offspring mice and intraperitoneal injections to MIA pregnant mice. The results indicated that PD-L1-Fc effectively suppressed neuroinflammation in the frontal cortex of offspring mice and partially ameliorated ASD-like behaviors; MIA in pregnant mice was significantly alleviated, and the offspring mice they produced did not exhibit neuroinflammation or ASD-like behaviors. In summary, we have demonstrated the therapeutic ability of PD-L1-Fc for MIA-induced ASD, aiming to provide new strategies and insights for the treatment of ASD.

AML cell-derived exosomes suppress the activation and cytotoxicity of NK cells in AML via PD-1/PD-L1 pathway.

Exosomes are bilayer lipid bodies and contain a variety of bioactive molecules such as proteins, lipids, and nucleic acids, and so forth. Exosomes derived from solid tumors may play critical roles in tumor development and immune evasion. However, the underlying effects of tumor-derived exosomes on immune function in modulating intercellular crosstalk within the bone marrow niche during acute myeloid leukemia (AML) development and immune evasion remain largely elusive. In this study, we aimed to explore the role of AML-exos in AML immune evasion. First, we isolated tumor-derived exosomes from AML cells (AML-exos) and revealed the presence of programmed cell death ligand-1 (PD-L1) protein in AML-exos. Next, we demonstrated that AML-exos can directly suppress the activation of natural killer (NK) cells and inhibit the cytotoxicity of NK cells, probably through activating the programmed cell death-1 (PD-1)/PD-L1 pathway. Furthermore, the inhibitory effect of AML-exos on NK cells could be alleviated by either PD-L1 inhibitor or antagonist. In summary, we demonstrated that AML-exos possess a PD-L1-dependent tumor-promoting effect which may contribute to immune tolerance in antitumor therapy, but blocking the PD-1/PD-L1 pathway may alleviate the tumor immunosuppression induced by AML-exos. Our findings in this study may offer a new immunotherapy strategy to cure AML.

PD-1/PD-L1 Provides Protective Role in Hypoxia-Induced Pulmonary Vascular Remodeling.

Hypoxia-induced pulmonary hypertension (HPH) is a T helper 17 cell response-driven disease, and PD-1 (programmed cell death 1)/PD-L1 (programmed cell death-ligand 1) inhibitor-associated pulmonary hypertension has been reported recently. This study is designed to explore whether the PD-1/PD-L1 pathway participates in HPH via regulating endothelial dysfunction and T helper 17 cell response. Lung tissue samples were obtained from eligible patients. Western blotting, immunohistochemistry, and immunofluorescence techniques were used to assess protein expression, while immunoprecipitation was utilized to detect ubiquitination. HPH models were established in C57BL/6 WT (wild-type) and PD-1-/- mice, followed by treatment with PD-L1 recombinant protein. Adeno-associated virus vector delivery was used to upregulate PD-L1 in the endothelial cells. Endothelial cell function was assessed through assays for cell angiogenesis and adhesion. Expression of the PD-1/PD-L1 pathway was downregulated in patients with HPH and mouse models, with a notable decrease in PD-L1 expression in endothelial cells compared with the normoxia group. In comparison to WT mice, PD-1-/- mice exhibited a more severe HPH phenotype following exposure to hypoxia, However, administration of PD-L1 recombinant protein and overexpression of PD-L1 in lung endothelial cells mitigated HPH. In vitro, blockade of PD-L1 with a neutralizing antibody promoted endothelial cell angiogenesis, adhesion, and pyroptosis. Mechanistically, hypoxia downregulated PD-L1 protein expression through ubiquitination. Additionally, both in vivo and in vitro, PD-L1 inhibited T helper 17 cell response through the PI3K (phosphoinositide 3-kinase)/AKT (protein kinase B)/mTOR (mammalian target of rapamycin) pathway in HPH. PD-1/PD-L1 plays a role in ameliorating HPH development by inhibiting T helper 17 cell response through the PI3K/AKT/mTOR pathway and improving endothelial dysfunction, suggesting a novel therapeutic indication for PD-1/PD-L1-based immunomodulatory therapies in the treatment of HPH.

PD-1/PD-L1 pathway: Current research in breast cancer.

Immunotherapy has shown encouraging outcomes in breast cancer (BC) treatment in recent years. The programmed cell death ligand 1 (PD-L1) transmembrane protein is suggested to function as a co-inhibitory factor in the immune response, where it collaborates with programmed cell death protein 1 (PD-1) to stimulate apoptosis, suppress cytokine release from PD-1 positive cells, and limit the growth of PD-1 positive cells. Furthermore, in many malignancies, PD-L1 reduces the immune system's response to neoplastic cells. These observations suggest that the PD-1/PD-L1 axis plays a vital role in cancer therapy and the regulation of cancer immune escape mechanisms. This review aimed to provide an overview of the functions of PD-1 and PD-L1 in BC cancer therapy. This research design is a literature review. The style is a traditional review on topics or variables relating to the PD-1/PD-L1 pathway. A literature search was carried out using three online databases. The search using the keywords yielded a total of 248 studies. Each result was filtered again according to the inclusion and exclusion criteria, resulting in a final total of 4 studies to be included in the literature review. The combination of PD-1/PD-L1 is essential for many malignancies. According to the evidence presented, this combination presents both an opportunity and a challenge in cancer treatment. Since many solid cancers, especially BC, express high levels of PD-1/PD-L1, cancer treatment mainly involves targeted therapies.

Reducing PD-L1 Expression by Degraders and Downregulators as a Novel Strategy to Target the PD-1/PD-L1 Pathway.

Targeting the programmed cell death protein-1 (PD-1)/programmed cell death-ligand 1 (PD-L1) pathway has evolved into one of the most promising strategies for tumor immunotherapy. Thus far, multiple monoclonal antibody drugs have been approved for treating a variety of tumors, while the development of small-molecule PD-1/PD-L1 inhibitors has lagged far behind, with only a few small-molecule inhibitors entering clinical trials. In addition to antibody drugs and small-molecule inhibitors, reducing the expression levels of PD-L1 has attracted extensive research interest as another promising strategy to target the PD-1/PD-L1 pathway. Herein, we analyze the structures and mechanisms of molecules that reduce PD-L1 expression and classify them as degraders and downregulators according to whether they directly bind to PD-L1. Moreover, we discuss the potential prospects for developing PD-L1-targeting drugs based on these molecules. It is hoped that this perspective will provide profound insights into the discovery of potent antitumor immunity drugs.

New advances in the treatment of chondrosarcoma under the PD-1/PD-L1 pathway.

Bone sarcomas encompass a group of spontaneous mesenchymal malignancies, among which osteosarcoma, Ewing sarcoma, chondrosarcoma, and chordoma are the most common subtypes. Chondrosarcoma, a relatively prevalent malignant bone tumor that originates from chondrocytes, is characterized by endogenous cartilage ossification within the tumor tissue. Despite the use of aggressive treatment approaches involving extensive surgical resection, chemotherapy, and radiotherapy for patients with osteosarcoma, chondrosarcoma, and chordoma, limited improvements in patient outcomes have been observed. Furthermore, resistance to chemotherapy and radiation therapy has been observed in chondrosarcoma and chordoma cases. Consequently, novel therapeutic approaches for bone sarcomas, including chondrosarcoma, need to be uncovered. Recently, the emergence of immunotherapy and immune checkpoint inhibitors has garnered attention given their clinical success in various diverse types of cancer, thereby prompting investigations into their potential for managing chondrosarcoma. Considering that circumvention of immune surveillance is considered a key factor in the malignant progression of tumors and that immune checkpoints play an important role in modulating antitumor immune effects, blockers or inhibitors targeting these immune checkpoints have become effective therapeutic tools for patients with tumors. One such checkpoint receptor implicated in this process is programmed cell death protein-1 (PD-1). The association between PD-1 and programmed cell death ligand-1 (PD-L1) and cancer progression in humans has been extensively studied, highlighting their remarkable potential as biomarkers for cancer treatment. This review comprehensively examines available studies on current chondrosarcoma treatments and advancements in anti-PD-1/PD-L1 blockade therapy for chondrosarcoma.

Abstract 5146: Clinical significance of inter-assay discrepancy in PD-L1 expression evaluation for the efficacy of pembrolizumab in advanced NSCLC patients with high PD-L1 expression

Abstract Introduction: The expression of programmed cell death ligand-1 (PD-L1) is a predictive biomarker for the efficacy of pembrolizumab in advanced non-small cell lung cancer (NSCLC). While several assays have been approved for evaluating PD-L1 expression status, the inter-assay discordances are observed. The clinical significance of these discrepancies is still unclear. Methods: We retrospectively reviewed treatment-naïve NSCLC patients with available PD-L1 expression status by both 22C3 and SP142 assays. Among these patients, efficacy analysis was performed in those with PD-L1 tumor proportion score (TPS) ≥ 50% (22C3) who received the first-line pembrolizumab monotherapy. Additionally, we conducted RNA-sequence analysis in the patients with TPS ≥ 50% to investigate the distinct immune profiles with the inter-assay discordance. Results: A total of 611 patients were evaluated for PD-L1 expression status by both assays. Of 198 patients with TPS ≥ 50%, 91 (46%) had TC score ≤ 1 (SP142, i.e., inter-assay discrepancy). In 52 patients who received the first-line pembrolizumab monotherapy, the efficacy in patients with the inter-assay discrepancy was significantly lower than those without the discrepancy (shown in Table). While there was no difference in tumor microenvironments such as the tumor-infiltrating lymphocytes, the transcriptome analysis revealed significantly more CD274 splicing variants with aberrant 3’-terminal sequences in tumors with the inter-assay discrepancy than those without discrepancy, leading to the suppressed PD-1/PD-L1 pathway in those with the discrepancy. Conclusion: The inter-assay discrepancy in the PD-L1 expression status on tumor cells between the 22C3 and SP142 assays, reflecting an imbalance of the CD274 splicing variants, could be a primary-resistance mechanism to the pembrolizumab monotherapy in highly PD-L1-expressing NSCLCs. PD-L1(22C3) Discrepancy Pts. ORR(%) p value Median PFS(months) 95%CI p value TPS ≥ 50% yes 17 18 < 0.001 3.2 0.8–5.5 < 0.001 no 35 83 8.3 5.7–24.2 Citation Format: Jun Miyakoshi, Jumpei Kashima, Masayuki Shirasawa, Masahiro Torasawa, Yuji Matsumoto, Ken Masuda, Yuki Shinno, Yusuke Okuma, Tatsuya Yoshida, Yasushi Goto, Hidehito Horinouchi, Kouya Shiraishi, Takashi Kohno, Noboru Yamamoto, Yasushi Yatabe, Yuichiro Ohe. Clinical significance of inter-assay discrepancy in PD-L1 expression evaluation for the efficacy of pembrolizumab in advanced NSCLC patients with high PD-L1 expression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5146.

Abstract 4044: Potentiated antitumor activity of poly-γ-glutamic acid combined with anti PD-L1 blockade on murine models of colorectal cancer

Abstract Objective: Immune checkpoint inhibitors(ICIs) have been shown to be key role in cancer therapy. Especially, antibodies targeting programmed cell death ligand1(PD-L1) promoted T cells to activate immune response against cancer cells. However, the current ICIs still have insignificant to motivate effective antitumor immunity by blocking PD-1/PD-L1 pathway and the regulatory network of PD-L1 by cytokines in the tumor microenvironment remains to be uncovered. Previously, we have reported the anti-cancer effects of combination treatment with a natural product, poly-γ-glutamic acid(γ-PGA), and PD-1 blockade. Now, we show that combination therapy with anti PD-L1 and γ-PGA can overcome the limits of ICIs and enhance anticancer effect in murine colorectal cancer. Design: In vivo efficacy studies were performed by intraperitoneal injection of antibody targeting PD-L1 and oral administration of γ-PGA in C57BL/6 model transplanted with mouse tumor cell lines. Systemic changes in immunophenotype was measured by tumor volume size and body weight. The splenocyte was isolated from mice and the populations of myeloid-driven suppressor cells(MDSCs) and CD4/CD8 T cells were analyzed by FACS. Also, the significant cytokines activated by T- cell, IFN-γ and IL-2, were measured by ELISA. Results and Conclusions: In murine model of colorectal cancer, γ-PGA and anti PD-L1 blockade combination therapy significantly improved anti-tumor activity compared with single agents. In addition, tumoral infiltration of CD8+ T cells and IFN-γ productions were increased by γ-PGA, and its antitumoral activity was attenuated by antibody-mediated depletion of these cells, indicating that g-PGA suppressed tumor growth in a CD8 T cell-dependent manner. Therefore, our results suggest that γ-PGA promote ICI-mediated antitumor responses by the transformation of "cold tumors" into “hot tumors” Citation Format: Jae-Pyung Jang, Chan-Hee Yoo, Kyung-Soo Hahm, Do Young Lee, Young-Chul Park, Jae Chul Choi. Potentiated antitumor activity of poly-γ-glutamic acid combined with anti PD-L1 blockade on murine models of colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4044.

Inhibition of SFTSV replication in humanized mice by a subcutaneously administered anti-PD1 nanobody

Severe fever with thrombocytopenia syndrome (SFTS) is a life-threatening disease caused by a novel bunyavirus (SFTSV), mainly transmitted by ticks. With no effective therapies or vaccines available, understanding the disease’s mechanisms is crucial. Recent studies found increased expression of programmed cell death-1 (PD-1) on dysfunctional T cells in SFTS patients. However, the role of the PD-1/programmed cell death-ligand 1 (PD-L1) pathway in SFTS progression remains unclear. We investigated PD-1 blockade as a potential therapeutic strategy against SFTSV replication. Our study analyzed clinical samples and performed in vitro experiments, revealing elevated PD-1/PD-L1 expression in various immune cells following SFTSV infection. An anti-PD-1 nanobody, NbP45, effectively inhibited SFTSV infection in peripheral blood mononuclear cells (PBMCs), potentially achieved through the mitigation of apoptosis and the augmentation of T lymphocyte proliferation. Intriguingly, subcutaneous administration of NbP45 showed superior efficacy compared to a licensed anti-PD-1 antibody in an SFTSV-infected humanized mouse model. These findings highlight the involvement of the PD-1/PD-L1 pathway during acute SFTSV infection and suggest its potential as a host target for immunotherapy interventions against SFTSV infection.

T lymphocyte-derived immunogenic hybrid nanovesicles for immunosuppression reversion and boosted photothermal immunotherapy

Photothermal therapy (PTT) can mediate the immunogenic cell death (ICD) of tumors through photothermal transformation, thus releasing tumor-associated antigens (TAAs) and damage-associated molecular patterns (DAMPs) to stimulate the maturation of dendritic cells (DCs) and elicit the immune response against tumors. However, PTT-mediated upregulation of the immune checkpoint molecule programmed cell death ligand 1 (PD-L1) will cause the immune evasion of tumor cells and thus increases the immunosuppression of cytotoxic T lymphocytes (CTLs), resulting in restricted photothermal immune activation. Taking advantage of the high expression of programmed cell death protein 1 (PD-1) in T lymphocytes, we develop an immunogenic photothermal hybrid nanovesicle to reverse immunosuppression and enhance PTT-induced ICD. The hybrid vesicle (TMVL-I) is constructed by phospholipid bilayer fusion of T cell-derived membrane vesicle (TMV) with high PD-1 expression and the indocyanine green (ICG)-loaded thermosensitive liposome (L-I). TMVL-Is bind to the tumor cells with PTT-induced upregulation of PD-L1, effectively blocking the PD-1/PD-L1 pathway between CTLs and tumor cells, thus reversing PD-L1-mediated tumor immunosuppression and intensifying photothermal-induced ICD effects. These processes significantly induce the maturation of DCs and enhance the infiltration of CTLs into both primary and distal tumors and the activation of spleen CTLs, strongly inhibiting the growth of B16 xenograft tumors and greatly improving the survival rate of B16 xenograft mice. This work provides a feasible strategy for immunosuppressive microenvironment reprogramming-based combination therapy.

Beyond inhibition against the PD-1/PD-L1 pathway: development of PD-L1 inhibitors targeting internalization and degradation of PD-L1.

Tumor cells hijack the programmed cell death protein-1 (PD-1)/programmed cell death ligand-1 (PD-L1) pathway to suppress the immune response through overexpressing PD-L1 to interact with PD-1 of T cells. With in-depth ongoing research, tumor-intrinsic PD-L1 is found to play important roles in tumor progression without interaction with PD-1 expressed on T cells, which provides an additional important target and therapeutic approach for development of PD-L1 inhibitors. Existing monoclonal antibody (mAb) drugs against the PD-1/PD-L1 pathway generally behave by conformationally blocking the interactions of PD-1 with PD-L1 on the cell surface. Beyond general inhibition of the protein-protein interaction (PPI), inhibitors targeting PD-L1 currently focus on the functional inhibition of the interaction between PD-1/PD-L1 and degradation of tumor-intrinsic PD-L1. This perspective will clarify the evolution of PD-L1 inhibitors and provide insights into the current development of PD-L1 inhibitors, especially targeting internalization and degradation of PD-L1.

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

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

Programmed Cell Death Protein 1 (PD-1) in Relation to PANoptosis: Immune Pharmacological Targets for Management of Breast Adenocarcinoma.

Programmed cell death protein 1 or Programmed death-1 (PD-1) and Programmed Cell Death Ligand 1 (PD-L1) research have tremendously been taken into great consideration in the field of cancer immune pharmacology. Cancer immunotherapy has been convoyed by a capable outcome over the past few years. PD-1 and PD-L1 play a pivotal role in attenuating immune involvement, modulating the activity of T-cells, and promoting different types of programmed cell death. Participation of antigen-specific T cells and regulatory T cells and their acute mutations during cancer cell invasion and migration may lead to challenges for three programmed cell death methods, namely, pyroptosis, apoptosis, and necroptosis called "PANoptosis". This review aimed to explore the correlation between the PD-1/PD-L1 pathway in "PANoptosis" using available recently published literature with several schematic representations. Hopefully, the review will facilitate the biomedical scientist targeting cancer immune pharmacological aspect for the management of Breast Adenocarcinoma shortly.

Salidroside suppresses the multiple oncogenic activates and immune escape of lung adenocarcinoma through the circ_0009624-mediated PD-L1 pathway.

Lung adenocarcinoma (LUAD) is a fatal malignancy all over the world. Salidroside (SAL) is an active component extracted from Rhodiola rosea that has been reported to exert antitumor activity against several human cancers, containing lung adenocarcinoma (LUAD). The purpose of this study was to explore the effect and underlying mechanism of SAL in LUAD. Cell viability, proliferation, migration, and invasion were measured using cell counting kit-8 (CCK-8), 5-ethynyl-2'-deoxyuridine (EdU), and transwell assays. Effects of LUAD cells on the cytotoxicity, percentage, and death of CD8+ cells were detected using lactate dehydrogenase (LDH) and flow cytometry assays. Programmed cell death ligand 1 (PD-L1) protein level was examined using western blot. Circ_0009624, enolase 1 (ENO1), and PD-L1 levels were determined using real-time quantitative polymerase chain reaction (RT-qPCR). The biological role of SAL on LUAD tumor growth was assessed using the xenograft tumor model in vivo. SAL restrained LUAD cell proliferation, migration, invasion, and immune escape in vitro via modulating PD-L1. Circ_0009624 expression was increased in LUAD. Applying SAL repressed circ_0009624 and PD-L1 expression in LUAD cells. SAL treatment hindered suppressed various oncogenic activates and immune escape of LUAD cells by regulating the circ_0009624/PD-L1 pathway. SAL blocked LUAD xenograft growth in vivo. Applying SAL might constrain malignant phenotypes and immune escape of LUAD cells partially through the circ_0009624-mediated PD-L1 pathway, providing a novel insight for LUAD treatment.

Abstract 6353: Combination of poly-γ-glutamic acid with anti PD-L1 blockade leads to improved anti-tumor activity in murine models

Abstract Immune checkpoint inhibitors(ICIs) have been shown to be key role in cancer therapy. Especially, antibodies targeting programmed cell death ligand1(PD-L1) promoted T cells to activate immune response against cancer cells. However, the current ICIs still have insignificant to motivate effective antitumor immunity by blocking PD-1/PD-L1 pathway and the regulatory network of PD-L1 by cytokines in the tumor microenvironment remains to be uncovered. Previously, we have reported the anti-cancer effects of combination treatment with a natural product, poly-γ-glutamic acid(γ-PGA), and PD-1 blockade. Now, we showed that combination therapy with anti PD-L1 and γ-PGA overcome the limits of ICIs and enhance anticancer effect in murine melanoma(B16F10). In vivo efficacy studies were performed by intraperitoneal injection of antibody targeting PD-L1 and oral administration of γ-PGA in C57BL/6 model transplanted with B16F10 melanoma cell. Systemic changes in immunophenotype were measured by tumor volume size and survival rate. The splenocytes were isolated from mice and the populations of myeloid-driven suppressor cells(MDSCs) and CD4/CD8 T cells were analyzed by FACS. Combination therapy with γ-PGA and anti PD-L1 blockade showed dramatically more suppressive tumor growth and enhanced long-term survival rate than other monotherapic treatment. In addition, γ-PGA was shown to play a role in the immune modulation of tumor microenvironment by activation of T cells and inhibition of MDSCs so as to prevent tumors from immune escape. Therefore, we suggest that γ-PGA can promote ICI-mediated antitumor responses by the transformation of "cold tumors" into “hot tumors” Citation Format: Jae-Pyung Jang, Jae Chul Choi, Kyung-Soo Hahm, Do Young Lee, Young-Chul Park. Combination of poly-γ-glutamic acid with anti PD-L1 blockade leads to improved anti-tumor activity in murine models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6353.

Forsythiaside A prevents zymosan A-induced cell migration in neutrophil-differentiated HL-60 cells via PD-1/PD-L1 pathway

Neutrophils, which account for more than 80% of leukocyte, play an important role in resolution of inflammation. Immune checkpoint molecules could be potential biomarkers in immunosuppression. Forsythiaside A (FTA), a main constituent of Forsythia suspensa (Thunb.) Vahl, provides a very significant anti-inflammatory activity. Here we defined the immunological mechanisms of FTA by taking programmed cell death-1 (PD-1)/programmed cell death-Ligand 1 (PD-L1) pathway into consideration. FTA could inhibited cell migration in HL-60-derived neutrophils in vitro, and this action appeared to be mediated via PD-1/PD-L1 depended JNK and p38 MAPK pathways. In vivo, FTA prevented PD-L1+ neutrophils infiltration and reduced the levels of tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1) and interferon-gamma (IFN-γ) after zymosan A-induced peritonitis. PD-1/PD-L1 inhibitor could abolish the suppression of FTA. The expression of inflammatory cytokines and chemokines were positively correlated with PD-L1. Molecular docking showed that FTA could bind to PD-L1. Taken together, FTA might prevent neutrophils infiltration to exert inflammation resolution through PD-1/PD-L1 pathway.

Immunology of Giant Cell Arteritis.

Giant cell arteritis is an autoimmune disease of medium and large arteries, characterized by granulomatous inflammation of the three-layered vessel wall that results in vaso-occlusion, wall dissection, and aneurysm formation. The immunopathogenesis of giant cell arteritis is an accumulative process in which a prolonged asymptomatic period is followed by uncontrolled innate immunity, a breakdown in self-tolerance, the transition of autoimmunity from the periphery into the vessel wall and, eventually, the progressive evolution of vessel wall inflammation. Each of the steps in pathogenesis corresponds to specific immuno-phenotypes that provide mechanistic insights into how the immune system attacks and damages blood vessels. Clinically evident disease begins with inappropriate activation of myeloid cells triggering the release of hepatic acute phase proteins and inducing extravascular manifestations, such as muscle pains and stiffness diagnosed as polymyalgia rheumatica. Loss of self-tolerance in the adaptive immune system is linked to aberrant signaling in the NOTCH pathway, leading to expansion of NOTCH1+CD4+ T cells and the functional decline of NOTCH4+ T regulatory cells (Checkpoint 1). A defect in the endothelial cell barrier of adventitial vasa vasorum networks marks Checkpoint 2; the invasion of monocytes, macrophages and T cells into the arterial wall. Due to the failure of the immuno-inhibitory PD-1 (programmed cell death protein 1)/PD-L1 (programmed cell death ligand 1) pathway, wall-infiltrating immune cells arrive in a permissive tissues microenvironment, where multiple T cell effector lineages thrive, shift toward high glycolytic activity, and support the development of tissue-damaging macrophages, including multinucleated giant cells (Checkpoint 3). Eventually, the vascular lesions are occupied by self-renewing T cells that provide autonomy to the disease process and limit the therapeutic effectiveness of currently used immunosuppressants. The multi-step process deviating protective to pathogenic immunity offers an array of interception points that provide opportunities for the prevention and therapeutic management of this devastating autoimmune disease.

Expression of PD-L1 through evolution phase from pre-invasive to invasive lung adenocarcinoma

BackgroundThis study evaluated programmed cell death-ligand 1 (PD-L1) expression from pre-invasive adenocarcinoma to invasive lung adenocarcinoma, aimed to investigate the potential association of PD-L1 pathway with lung adenocarcinoma early evolution.MethodsWe evaluated PD-L1 expression in 1123 resected lung specimens of adenocarcinoma in situ (AIS), minimally invasive adenocarcinoma (MIA) and invasive adenocarcinoma (IAC) of stage IA1–IA3. PD-L1 expression was defined based on the proportion of stained tumor cells using the tumor proportion score: < 1% (negative), ≥ 1% (positive) and ≥ 50% (strongly positive). Correlations between PD-L1 expression and T stage, pathological subtype, adenocarcinoma grade, spread through air space (STAS), vascular invasion, lymphatic invasion and driven genes were analyzed.ResultsThere was almost no PD-L1 expression in AIS or MIA. However, PD-L1 expression was correlated with invasiveness of lung adenocarcinoma. The percentages of PD-L1 positive in IA1–IA3 were 7.22%, 11.29%, and 14.20%, respectively. The strongly positive rates of PD-L1 were 0.38%, 1.64%, and 3.70% in IA1–IA3, respectively. PD-L1 expression and positive rate were also associated with poor pathological subtype and poor biological behavior, such as adenocarcinoma Grade 3, micropapillary or solid dominant subtype, STAS and vascular invasion. Finally, PD-L1 positive rate seems also corrected with driven gene ALK, ROS-1 and KRAS.ConclusionsPD-L1 expression was positively correlated with the emergence of invasiveness and poor pathological subtype or biological behavior of early-stage lung adenocarcinoma. PD-L1 pathway may be involved in the early evolution of lung adenocarcinoma from AIS to IAC.