Intranasal Multiepitope PD-L1-siRNA-Based Nanovaccine: The Next-Gen COVID-19 Immunotherapy.

The first approved vaccines for human use against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are nanotechnology-based. Although they are modular, rapidly produced, and can reduce disease severity, the currently available vaccines are restricted in preventing infection, stressing the global demand for novel preventive vaccine technologies. Bearing this in mind, we set out to develop a flexible nanovaccine platform for nasal administration to induce mucosal immunity, which is fundamental for optimal protection against respiratory virus infection. The next-generation multiepitope nanovaccines co-deliver immunogenic peptides, selected by an immunoinformatic workflow, along with adjuvants and regulators of the PD-L1 expression. As a case study, we focused on SARS-CoV-2 peptides as relevant antigens to validate the approach. This platform can evoke both local and systemic cellular- and humoral-specific responses against SARS-CoV-2. This led to the secretion of immunoglobulin A (IgA), capable of neutralizing SARS-CoV-2, including variants of concern, following a heterologous immunization strategy. Considering the limitations of the required cold chain distribution for current nanotechnology-based vaccines, it is shown that the lyophilized nanovaccine is stable for long-term at room temperature and retains its in vivo efficacy upon reconstitution. This makes it particularly relevant for developing countries and offers a modular system adaptable to future viral threats.

Dual PI3K/mTOR Inhibitor BEZ235 combined with BMS-1166 Promoting Apoptosis in Colorectal Cancer.

Background: BMS-1166, a PD-1/PD-L1 inhibitor, inhibits the binding of PD-L1 to PD-1, restores T cell function, and enhances tumor immune response. However, mutations in the tumor suppressor or impaired cellular signaling pathways may also lead to cellular transformation. In this study, the SW480 and SW480R cell lines were used as the model to elucidate the treatment with BMS-1166, BEZ235, and their combination. Methods: MTT and colony-formation assays were used to evaluate cell proliferation. Wound-healing assay was used to assess cell migration. Cell cycle and apoptosis were analyzed by flow cytometry. The phosphorylation level of the key kinases in the PI3K/Akt/mTOR and MAPK pathways, PD-L1, and the protein levels related to the proliferation, migration, and apoptosis were assessed using western blotting. Results: BEZ235 enhanced BMS-1166-mediated cell proliferation and migration inhibition in SW480 and SW480R cells and promoted apoptosis. Interestingly, the downregulation of the negative regulator PTEN raised the PD-L1 level, which was abolished by the inhibition of Akt. BMS-1166 promoted PI3K, Akt, mTOR, and Erk phosphorylation. However, the combination of BEZ235 with BMS-1166 suppressed the expression of PI3K, p-Akt, p-mTOR, and p-Erk in SW480 and SW480R cells compared to BMS-1166 or BEZ235 single treatment by inhibiting the binding of PD1 to PD-L1. Conclusions: PD-1 binds to PD-L1 and activates the PI3K/mTOR and MAPK pathways, which might be the molecular mechanism of acquired resistance of CRC to BMS-1166. The combination of the two drugs inhibited the phosphorylation of PI3K, Akt, and Erk in the PI3K/mTOR and MAPK pathway, i.e., BEZ235 enhanced the BMS-1166 treatment effect by blocking the PI3K/mTOR pathway and interfering with the crosstalk of the MAPK pathway. Therefore, these findings provide a theoretical basis for BMS-1166 combined with BEZ235 in the trial treatment of colorectal cancer.

Immune checkpoint inhibitors targeting PD-1/PD-L1 in the treatment of human lymphomas.

Non-Hodgkin lymphomas (NHLs) encompass a diverse group of malignancies arising from B cells, T cells, and natural killer (NK) cells at various stages of differentiation. Conversely, classical Hodgkin lymphomas (cHLs) primarily feature Reed-Sternberg cells (RSCs) amid a background of reactive immune cells. Immunomodulatory pathways, notably the PD-1/PD-L1 axis, play pivotal roles in tumor immune evasion across both NHLs and cHLs. Elevated expression of PD-1 and PD-L1 is observed in a spectrum of lymphomas, influencing prognosis and treatment response. Therapeutically, immune checkpoint inhibitors (ICIs) targeting PD-1/PD-L1 have revolutionized lymphoma management, particularly in relapsed/refractory cases. Nivolumab and pembrolizumab, among others, have demonstrated efficacy in various B-cell lymphomas, with promising outcomes in cHL. Combination strategies incorporating ICIs with conventional chemotherapy or targeted agents show enhanced efficacy and are being explored extensively. In this review we discuss the most important features of the tumor microenvironment of NHLs and cHLs, address the therapeutic approaches with ICIs and try to outline future perspectives.

Pretreatment pulmonary tumor necrosis is a promising prognostic imaging biomarker for first-line anti-PD-1/PD-L1 therapy in advanced lung squamous cell carcinoma: a multi-institutional, propensity score-matching cohort analysis.

Background: Tumor necrosis (TN) is a common feature in lung squamous cell carcinoma (LSCC), which could provide useful predictive and prognostic information. Objectives: This study aimed to investigate the effect of pretreatment pulmonary TN (PTN) on the prognosis of first-line anti-programmed cell death 1 (PD-1)/PD ligand 1 (PD-L1) inhibitor in advanced LSCC. Design: We conducted a retrospective study to analyze the association between the presence of PTN and clinical outcomes in advanced LSCC patients treated with anti-PD-1/PD-L1 inhibitors. Methods: Data from 240 eligible patients were collected from 27 hospitals across China between 2016 and 2020. The presence of PTN was assessed using contrast-enhanced chest computed tomography (CT) imaging at baseline. We utilized the Cox proportional-hazards regression model to analyze the association between PTN and clinical outcomes. In addition, to account for potential confounding factors and ensure comparability between groups, we employed propensity score-matching (PSM) analysis. Results: In the overall patient cohort, the presence of PTN was 39.6%. The median follow-up duration was 20.3 months. The positive PTN group exhibited a notably inferior median progression-free survival (PFS; 6.5 months vs 8.6 months, p = 0.012) compared to the negative PTN group. Within the Cox proportional-hazards regression model, PTN emerged as an independent predictor of unfavorable PFS (hazard ratio (HR) = 1.354, 95% confidence interval (CI): 1.002-1.830, p = 0.049). After PSM, the median PFS for the positive PTN group (6.5 months vs 8.0 months, p = 0.027) remained worse than that of the negative PTN group. Multivariate analyses also further underscored that the presence of PTN independently posed a risk for shorter PFS (HR = 1.494, 95% CI: 1.056-2.112, p = 0.023). However, no statistically significant difference in overall survival was observed between the two groups. Conclusion: Our study suggests that the presence of PTN on baseline contrast-enhanced chest CT is a potential negative prognostic imaging biomarker for the outcome of anti-PD-1/PD-L1 inhibitor therapy in advanced LSCC. Further studies are warranted to validate these findings and explore the underlying mechanisms.

Predicting anti-PD-1/PD-L1 inhibitor treatment outcomes: pulmonary tumor necrosis in lung squamous cell carcinoma Our study focused on lung squamous cell carcinoma (LSCC) patients receiving first-line anti-PD-1/PD-L1 therapy. We explored the impact of a feature called pretreatment pulmonary tumor necrosis (PTN) on their prognosis. PTN was identified in 39.6% of patients using baseline chest CT scans. Results revealed that patients with PTN had a shorter time without disease progression (median PFS of 6.5 months compared to 8.6 months) and a higher risk of unfavorable outcomes. This suggests that PTN may serve as a negative prognostic imaging marker for anti-PD-1/PD-L1 therapy in advanced LSCC. Further research is needed to confirm and understand these findings better.

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.

Mechanism research of non-coding RNA in immune checkpoint inhibitors therapy.

Immune checkpoint inhibitor (ICI) therapies for tumors of different systems have attained significant achievements and have changed the current situation of tumor treatment due to their therapeutic characteristics of high specificity and low side effects. The immune checkpoint Programmed death 1/Programmed cell death-Ligand 1 (PD-1/PD-L1) axis exerts a vital role in the immune escape of tumor cells. As a result, it has become a key target for tumor immunotherapy. Therefore, to perfect research into potential regulatory factors for the PD-1/PD-L1 axis, in order to understand and illustrate tumor ICI therapy mechanisms, is a significant goal. Moreover, ncRNA has been verified to regulate the PD-1/PD-L1 axis in the tumor immune microenvironment to regulate tumor genesis and development. ncRNAs can improve or decrease the efficacy of ICI therapy by modulating PD-L1 expression. This review aimed to investigate the mechanisms of action of ncRNA in regulating the PD-1/PD-L1 axis in ICI therapy, to provide more efficient immunotherapy for tumors of different systems.

Effectiveness and safety of anlotinib plus anti-programmed cell death 1/ligand 1 (anti-PD-1/PD-L1) antibodies as maintenance therapy after first-line chemotherapy combined with anti-PD-1/PD-L1 antibodies in extensive-stage small cell lung cancer: a real-world study.

Background: Currently, chemotherapy plus immunotherapy followed by maintenance therapy with immune monotherapy is the preferred first-line treatment option for extensive-stage small cell lung cancer (ES-SCLC), but with limited overall survival (OS) and progression-free survival (PFS) benefits. The combination of anti-angiogenic drugs with immunotherapy has shown encouraging anti-tumor activity and tolerability, with some degree of overcoming immune resistance. This study aimed to evaluate the effectiveness and safety of anlotinib plus anti-programmed cell death 1/ligand 1 (anti-PD-1/PD-L1) antibodies as maintenance therapy after first-line chemotherapy combined with immunotherapy in ES-SCLC. Methods: Between June 2020 and December 2021, 12 patients with newly diagnosed ES-SCLC in the First Affiliated Hospital of Army Medical University were retrospectively analyzed. All patients without disease progression after 4-6 cycles of first-line platinum-containing chemotherapy plus anti-PD-1/PD-L1 antibodies received anlotinib (12 mg oral/day, days 1-14, followed by 1 week off, every 3 weeks per cycle) plus anti-PD-1/PD-L1 antibodies as maintenance therapy. Several patients underwent chest radiotherapy (intensity-modulated radiotherapy using a 6 MV X-ray) without disease progression before maintenance therapy. The effectiveness and safety of anlotinib plus anti-PD-1/PD-L1 antibodies as maintenance therapy after first-line chemotherapy combined with immunotherapy in ES-SCLC were evaluated. Results: The median follow-up time was 31.1 months. During first-line treatment (including maintenance therapy), one patient achieved a complete response, eight patients achieved a partial response (PR), and three patients had stable disease, with an objective response rate of 75.0% and a disease control rate of 100.0%. During maintenance therapy with anlotinib plus anti-PD-1/PD-L1 antibodies, 50.0% of patients achieved further lesion remission on the basis of the prior initial treatment, of which one patient achieved a PR. The median PFS was 13.6 [95% confidence interval (CI): 11.2-15.6] months, and the median OS was 19.5 (95% CI: 14.5-24.5) months. Treatment-related any grade and grade 3-4 adverse events (AEs) were reported in 100.0% and 58.3% of patients, respectively. No life-threatening AEs were observed. Grade 3-4 AEs included leukocytopenia (58.3%, 7/12), thrombocytopenia (33.3%, 4/12), nausea (33.3%, 4/12), anemia (16.7%, 2/12), and fatigue (8.3%, 1/12). All AEs during maintenance therapy were tolerated and were regarded as grade 1-2, with the majority being fatigue, nausea, rash, and hemoptysis. Conclusions: The combination of anlotinib with anti-PD-1/PD-L1 antibodies demonstrated encouraging effectiveness and safety in treating patients with ES-SCLC, suggesting that it may be a preferred option for maintenance therapy after first-line chemotherapy combined with immunotherapy.

[Expression and Significance of PD-1/PD-L1 in MDS Blast Cells, T Lymphocyte Cell Subsets and Treg Cells].

OBJECTIVE: To investigate the expression and significance of PD-1/PD-L1 in MDS blast cells, T lymphocyte cell subsets and Treg cells. METHODS: Eighty-eight MDS patients and 19 AML patients were collectd as the study subjects, and Iron deficiency anemia and healthy bone marrow donors were used as control group. The expression of PD-1/PD-L1 in MDS/AML blast cells, T lymphocyte cell subsets and Treg cells was detected by flow cytometry, and the expression level of Th1/Th2/Th17-related cytokines in peripheral serum was detected. RESULTS: The expression of PD-1/PD-L1 in blast cells, T lymphocyte cell subsets and Treg cells in low risk MDS group were lower than that in control group, medium and high risk MDS group and AML group（all P < 0.01）, and Th1/Th17 type cytokines were dominant. The expression of PD-1/PD-L1 in blast cells, T lymphocyte cell subsets and Treg cells of intermediate and high risk MDS group and AML group were higher than that of control group and low risk MDS group (all P < 0.01), and Th2 type and Treg type (IL-10、TGF-ß) cytokines were dominant. After treatment, the differences of PD-1/PD-L1 expression were not statisticatly significant in blast cells, T lymphocyte cell subsets and Treg cells between the MDS remission group and the control group (all P >0.05). The expression of PD-1/PD-L1 in blast cells, T lymphocyte cell subsets and Treg cells in MDS non-remission group were significantly higher than that in remission group and control group (all P < 0.01). CONCLUSION: The high expression of PD-1/PD-L1, dominance of Treg (IL-10、TGF-ß) and Th2-related cytokines and inhibition of effector T lymphocyte cells in patients with MDS is conducive to tumor cell proliferation and immune escape, which may promote the progression of MDS disease.

A two-stage ensemble learning based prediction and grading model for PD-1/PD-L1 inhibitor-related cardiac adverse events: A multicenter retrospective study.

BACKGROUND: Immune-related cardiac adverse events (ircAEs) caused by programmed cell death protein-1 (PD-1) and programmed death-ligand-1 (PD-L1) inhibitors can lead to fulminant and even fatal consequences. This study aims to develop a prediction and grading model for ircAEs, enabling graded management of patients. METHODS: This study utilized medical record systems from two medical institutions to develop a prediction and grading model for ircAEs using ten machine learning algorithms and two variable screening methods. The model was developed based on a two-stage ensemble learning framework. In the first stage, the ircAEs and non-ircAEs cases were classified. In the second stage, ircAEs cases were grouped into grades 1-2 and 3-5. The experiments were evaluated using five-fold cross-validation. The model's prediction performance was assessed using accuracy, precision, recall, F1 value, Brier score, receiver operating characteristic curve area (AUC), and area under the precision-recall curve (AUPR). RESULTS: 615 patients were included in the study. 147 experienced ircAEs, and 44 experienced grade 3-5 ircAEs. The soft voting classifier trained using the variables screened by feature importance ranking performed better than other classifiers in both stages. The average AUC for the first and second stages is 84.18 % and 85.13 %, respectively. In the first stage, the three most important variables are N-terminal B-type natriuretic peptide (NT-proBNP), interleukin-2 (IL-2), and C-reactive protein (CRP). In the second stage, the patient's age, NT-proBNP, and left ventricular ejection fraction (LVEF) are the three most critical variables. CONCLUSIONS: The prediction and grading model of ircAEs based on two-stage ensemble learning established in this study has good performance and potential clinical application.

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.

Development of bioassay platforms for biopharmaceuticals using Jurkat-CAR cells by AICD.

The assessment of bioactivity for therapeutic antibody release assay poses challenges, particularly when targeting immune checkpoints. An in vitro bioassay platform was developed using the chimeric antigen receptor on Jurkat cells (Jurkat-CAR) to analyze antibodies targeting immune checkpoints, such as CD47/SIRPα, VEGF/VEGFR1, PD-1/PD-L1, and CD70/CD27. For CD47/SIRPα, the platform involved a Jurkat-CAR cell line expressing the chimeric SIRPα receptor (CarSIRPα). CarSIRPα was created by sequentially fusing the SIRPα extracellular region with the CD8α hinge region, the transmembrane (TM) and intracellular (IC) domains of CD28, and the intracellular signaling domain of CD3ζ. The resulting Jurkat-CarSIRPα cells can undergo "activation-induced cell death (AICD)" upon incubation with purified or cellular CD47, as evidenced by the upregulation of CD69, IL-2, and IFN-γ. Similar results also appeared in Jurkat CarVEGFR1, Jurkat CarPD1 and Jurkat CARCD27 cells. These cells are perfectly utilized for the bioactivity analysis of therapeutic antibody. Our study indicates that the established in vitro assay platform based on Jurkat-CAR has been confirmed repeatedly and has shown robust reproducibility; thus, this platform can be used for screening or for release assays of given antibody drugs targeting immune checkpoints.

Computational Approach for the Development of pH-Selective PD-1/PD-L1 Signaling Pathway Inhibition in Fight with Cancer.

Immunotherapy, particularly targeting the PD-1/PD-L1 pathway, holds promise in cancer treatment by regulating the immune response and preventing cancer cells from evading immune destruction. Nonetheless, this approach poses a risk of unwanted immune system activation against healthy cells. To minimize this risk, our study proposes a strategy based on selective targeting of the PD-L1 pathway within the acidic microenvironment of tumors. We employed in silico methods, such as virtual screening, molecular mechanics, and molecular dynamics simulations, analyzing approximately 10,000 natural compounds from the MolPort database to find potential hits with the desired properties. The simulations were conducted under two pH conditions (pH = 7.4 and 5.5) to mimic the environments of healthy and cancerous cells. The compound MolPort-001-742-690 emerged as a promising pH-selective inhibitor, showing a significant affinity for PD-L1 in acidic conditions and lower toxicity compared to known inhibitors like BMS-202 and LP23. A detailed 1000 ns molecular dynamics simulation confirmed the stability of the inhibitor-PD-L1 complex under acidic conditions. This research highlights the potential of using in silico techniques to discover novel pH-selective inhibitors, which, after experimental validation, may enhance the precision and reduce the toxicity of immunotherapies, offering a transformative approach to cancer treatment.

A novel bispecific peptide targeting PD-1 and PD-L1 with combined antitumor activity of T-cells derived from the patients with TSCC.

Programmed death-1 (PD-1) and programmed death ligand-1 (PD-L1) are key immune checkpoints (ICs) that critically influence immunotherapy. Tumor resistance to single IC-targeting drugs has increased interest in dual-target drugs, which have shown feasibility for cancer treatment. In this study, we aimed to develop dual-target peptide drugs targeting the PD-1/PD-L1 pathway and to evaluate their efficacy compared to functional antibodies in enhancing the cytotoxicity of human T cells against tongue squamous carcinoma cell lines. Through sequence analysis and peptide truncation, we modified a pre-existing peptide named nABPD-1 targeting PD-1. Subsequently, we obtained two novel peptides named nABPD-2 and nABPD-3, with nABPD-2 showing an enhanced affinity for human PD-1 protein compared to nABPD-1. Importantly, nABPD-2 exhibited dual-targeting capability, possessing a high affinity for both PD-L1 and PD-1. Furthermore, nABPD-2 effectively promoted the cytotoxicity of human T cells against tongue squamous carcinoma cell lines, surpassing the efficacy of anti-PD-1 or anti-PD-L1 functional antibodies alone. Considering that nABPD-2 has lower production costs and dose requirements, it can potentially be used in therapeutic applications.

The Role of Programmed Cell Death 1/Programmed Death Ligand 1 (PD-1/PD-L1) Axis in Sepsis-Induced Apoptosis.

Background and Objectives: Sepsis involves a dysregulated host response, characterized by simultaneous immunosuppression and hyperinflammation. Initially, there is the release of pro-inflammatory factors and immune system dysfunction, followed by persistent immune paralysis leading to apoptosis. This study investigates sepsis-induced apoptosis and its pathways, by assessing changes in PD-1 and PD-L1 serum levels, CD4+ and CD8+ T cells, and Sequential Organ Failure Assessment (SOFA) and Acute Physiology and Chronic Health Evaluation (APACHE II) severity scores. Materials and Methods: This prospective, observational, single-centre study enrolled 87 sepsis patients admitted to the intensive care unit at the County Emergency Clinical Hospital in Târgu Mureș, Romania. We monitored the parameters on day 1 (the day sepsis or septic shock was diagnosed as per the Sepsis-3 Consensus) and day 5. Results: Our study found a statistically significant variation in the SOFA score for the entirety of the patients between the studied days (p = 0.001), as well as for the studied patient groups: sepsis, septic shock, survivors, and non-survivors (p = 0.001, p = 0.003, p = 0.01, p = 0.03). On day 1, we found statistically significant correlations between CD8+ cells and PD-1 (p = 0.02) and PD-L1 (p = 0.04), CD4+ and CD8+ cells (p < 0.0001), SOFA and APACHE II scores (p < 0.0001), and SOFA and APACHE II scores and PD-L1 (p = 0.001 and p = 0.01). On day 5, we found statistically significant correlations between CD4+ and CD8+ cells and PD-L1 (p = 0.03 and p = 0.0099), CD4+ and CD8+ cells (p < 0.0001), and SOFA and APACHE II scores (p < 0.0001). Conclusions: The reduction in Th CD4+ and Tc CD8+ lymphocyte subpopulations were evident from day 1, indicating that apoptosis is a crucial factor in the progression of sepsis and septic shock. The increased expression of the PD-1/PD-L1 axis impairs costimulatory signalling, leading to diminished T cell responses and lymphopenia, thereby increasing the susceptibility to nosocomial infections.

Design, synthesis, pharmacological evaluation, and computational study of benzo[d] isothiazol-based small molecule inhibitors targeting PD-1/PD-l1 interaction.

Blockade of the programmed cell death-1 (PD-1)/programmed cell death ligand 1 (PD-L1) pathway is an attractive strategy for immunotherapy, but the clinical application of small molecule PD-1/PD-L1 inhibitors remains unclear. In this work, based on BMS-202 and our previous work YLW-106, a series of compounds with benzo[d]isothiazol structure as scaffold were designed and synthesized. Their inhibitory activity against PD-1/PD-L1 interaction was evaluated by a homogeneous time-resolved fluorescence (HTRF) assay. Among them, LLW-018 (27c) exhibited the most potent inhibitory activity with an IC50 value of 2.61 nM. The cellular level assays demonstrated that LLW-018 exhibited low cytotoxicity against Jurkat T and MDA-MB-231. Further cell-based PD-1/PD-L1 blockade bioassays based on PD-1 NFAT-Luc Jurkat cells and PD-L1 TCR Activator CHO cells indicated that LLW-018 could interrupt PD-1/PD-L1 interaction with an IC50 value of 0.88 µM. Multi-computational methods, including molecular docking, molecular dynamics, MM/GBSA, MM/PBSA, Metadynamics, and QM/MM MD were utilized on PD-L1 dimer complexes, which revealed the binding modes and dissociation process of LLW-018 and C2-symmetric small molecule inhibitor LCH1307. These results suggested that LLW-018 exhibited promising potency as a PD-1/PD-L1 inhibitor for further investigation.

Isolation and Total Synthesis of PM170453, a New Cyclic Depsipeptide Isolated from Lyngbya sp.

In our continuing search for biologically active new chemical entities from marine organisms, we have isolated a new cyclic depsipeptide, PM170453 (1), from a cyanobacterium of the genus Lyngbya sp., collected in the Indo-Pacific Ocean. Structure elucidation of the isolated compound was determined by spectroscopic methods including MS, 1H, 13C and 2D-NMR. To solve the supply problem for 1 and progress pharmaceutical development, the total synthesis of 1 that involves a total of 20 chemical steps in a convergent process was carried out. Its in vitro cytotoxic activity against four human tumor cell lines, as well as the inhibition of the interaction between the programmed cell death protein 1 PD-1 and its ligand PD-L1 were also evaluated.

Tumor-associated macrophages in anti-PD-1/PD-L1 immunotherapy for hepatocellular carcinoma: recent research progress.

Hepatocellular carcinoma (HCC) is one of the cancers that seriously threaten human health. Immunotherapy serves as the mainstay of treatment for HCC patients by targeting the programmed cell death protein 1/programmed cell death 1 ligand 1 (PD-1/PD-L1) axis. However, the effectiveness of anti-PD-1/PD-L1 treatment is limited when HCC becomes drug-resistant. Tumor-associated macrophages (TAMs) are an important factor in the negative regulation of PD-1 antibody targeted therapy in the tumor microenvironment (TME). Therefore, as an emerging direction in cancer immunotherapy research for the treatment of HCC, it is crucial to elucidate the correlations and mechanisms between TAMs and PD-1/PD-L1-mediated immune tolerance. This paper summarizes the effects of TAMs on the pathogenesis and progression of HCC and their impact on HCC anti-PD-1/PD-L1 immunotherapy, and further explores current potential therapeutic strategies that target TAMs in HCC, including eliminating TAMs in the TME, inhibiting TAMs recruitment to tumors and functionally repolarizing M2-TAMs (tumor-supportive) to M1-TAMs (antitumor type).

Design, synthesis, and evaluation of antitumor activity of 2-arylmethoxy-4-(2-fluoromethyl-biphenyl-3-ylmethoxy) benzylamine derivatives as PD-1/PD-l1 inhibitors.

A series of novel 2-arylmethoxy-4-(2-fluoromethyl-biphenyl-3-ylmethoxy) benzylamine derivatives was designed, synthesized, and evaluated for their antitumor effects as PD-1/PD-L1 inhibitors both in vitro and in vivo. Firstly, the ability of these compounds to block the PD-1/PD-L1 immune checkpoint was assessed using the homogeneous time-resolved fluorescence (HTRF) assay. Two of the compounds can strongly block the PD-1/PD-L1 interaction, with IC50 values of less than 10 nM, notably, compound HD10 exhibited significant clinical potential by inhibiting the PD-1/PD-L1 interaction with an IC50 value of 3.1 nM. Further microscale thermophoresis (MST) analysis demonstrated that HD10 had strong interaction with PD-L1 protein. Co-crystal structure (2.7 Å) analysis of HD10 in complex with the PD-L1 protein revealed a strong affinity between the compound and the target PD-L1 dimer. This provides a solid theoretical basis for further in vitro and in vivo studies. Next, a typical cell-based experiment demonstrated that HD10 could remarkably prevent the interaction of hPD-1 293 T cells from human recombinant PD-L1 protein, effectively restoring T cell function, and promoting IFN-γ secretion in a dose-dependent manner. Moreover, HD10 was effective in suppressing tumor growth (TGI = 57.31 %) in a PD-1/PD-L1 humanized mouse model without obvious toxicity. Flow cytometry, qPCR, and immunohistochemistry data suggested that HD10 inhibits tumor growth by activating the immune system in vivo. Based on these results, it seems likely that HD10 is a promising clinical candidate that should be further investigated.

The gut microbiota improves the efficacy of immune-checkpoint inhibitor immunotherapy against tumors: From association to cause and effect.

Immune-checkpoint inhibitors (ICIs), including anti-PD-1/PD-L1 therapeutic antibodies, have markedly enhanced survival across numerous cancer types. However, the limited number of patients with durable benefits creates an urgent need to identify response biomarkers and to develop novel strategies so as to improve response. It is widely recognized that the gut microbiome is a key mediator in shaping immunity. Additionally, the gut microbiome shows significant potential in predicting the response to and enhancing the efficacy of ICI immunotherapy against cancer. Recent studies encompassing mechanistic analyses and clinical trials of microbiome-based therapy have shown a cause-and-effect relationship between the gut microbiome and the modulation of the ICI immunotherapeutic response, greatly contributing to the establishment of novel strategies that will improve response and overcome resistance to ICI treatment. In this review, we outline the current state of research advances and discuss the future directions of utilizing the gut microbiome to enhance the efficacy of ICI immunotherapy against tumors.

Peptide Blockers of PD-1-PD-L1 Interaction Reinvigorate PD-1-Suppressed T Cells and Curb Tumor Growth in Mice.

The programmed cell death protein 1 (PD-1) plays a critical role in cancer immune evasion. Blocking the PD-1-PD-L1 interaction by monoclonal antibodies has shown remarkable clinical efficacy in treating certain types of cancer. However, antibodies are costly to produce, and antibody-based therapies can cause immune-related adverse events. To address the limitations associated with current PD-1/PD-L1 blockade immunotherapy, we aimed to develop peptide-based inhibitors of the PD-1/PD-L1 interaction as an alternative means to PD-1/PD-L1 blockade antibodies for anti-cancer immunotherapy. Through the functional screening of peptide arrays encompassing the ectodomains of PD-1 and PD-L1, followed by the optimization of the hit peptides for solubility and stability, we have identified a 16-mer peptide, named mL7N, with a remarkable efficacy in blocking the PD-1/PD-L1 interaction both in vitro and in vivo. The mL7N peptide effectively rejuvenated PD-1-suppressed T cells in multiple cellular systems designed to recapitulate the PD-1/PD-L1 interaction in the context of T-cell receptor signaling. Furthermore, PA-mL7N, a chimera of the mL7N peptide coupled to albumin-binding palmitic acid (PA), significantly promoted breast cancer cell killing by peripheral blood mononuclear cells ex vivo and significantly curbed tumor growth in a syngeneic mouse model of breast cancer. Our work raises the prospect that mL7N may serve as a prototype for the development of a new line of peptide-based immunomodulators targeting the PD-1/PD-L1 immune checkpoint with potential applications in cancer treatment.