PD-L1 Checkpoint Inhibitors Research Articles

LAG-3 Expression, γδ-T cell/MHC-I Interactions and Prognosis in Merkel Cell Carcinoma

Merkel Cell Carcinoma (MCC) is an aggressive cutaneous malignancy with a poor prognosis. One of the major mechanisms of immune evasion in MCC involves downregulation of MHC-I. Anti-PD-1/PD-L1 checkpoint inhibitors (CKIs) have revolutionized treatment for MCC, producing objective responses in ∼50% of patients, and are now standard of care; however, a substantial proportion of patients either fail to respond or develop resistance to CKIs. Given these recent successes, identification of other targetable immune checkpoints in the MCC tumor microenvironment (TME) is of great interest. Additionally, γ-delta (γδ) T cells may play critical roles in the response to MHC-I deficient cancers; therefore, evaluating γδ-T cells as a prognostic biomarker is warranted. We characterized the expression of PD-L1, PD-1, CD3, CD8, LAG-3, MHC-I, and γδ-T cells by IHC in a pre-immunotherapy retrospective cohort of 54 cases of MCC, and quantified expression levels and marker density via HALO. The increased density of LAG-3 and γδ-T cells correlated with other markers of an inflamed TME, with significant positive associations across all six markers (p<.002). Reflective of their putative role in the response to MHC-I suppressed cancers, cases with low HLA-I density showed a trend towards a higher ratio of γδ-T cells:CD3+ T cells (Spearman's r=-0.1582, p=0.21). Importantly, high CD3 density (HR=0.23, p=0.002), LAG-3 density (HR=0.47, p=0.037), γδ-T cell density (HR=0.26, p=0.02), and CD8 density (HR=0.27, p=0.03) showed associations with improved progression-free survival. Conditional tree analysis demonstrated that high CD8 and TCRδ expression were non-significant predictors of improved PFS and OS. Overall, LAG-3 is expressed in MCC infiltrates and is prognostic in pre-immunotherapy MCC, suggesting a potential role for LAG-3 inhibition in MCC. Additionally, CD8 and γδ-T cells may play a critical role in the response to MCC, and γδ-T cell density may represent a novel biomarker in MCC.

Efficacy and safety of PD-1/PD-L1 and CTLA-4 immune checkpoint inhibitors in the treatment of advanced colorectal cancer: a systematic review and meta-analysis

Efficacy and safety of PD-1/PD-L1 and CTLA-4 immune checkpoint inhibitors in the treatment of advanced colorectal cancer: a systematic review and meta-analysis

Immunotherapeutic Potential of Mutated NPM1 for the Treatment of Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is a malignant disease of the blood and bone marrow that is characterized by uncontrolled clonal proliferation of abnormal myeloid progenitor cells. Nucleophosmin 1 (NPM1) gene mutations are the most common genetic abnormality in AML, detectable in blast cells from about one-third of adults with AML. AML NPM1mut is recognized as a separate entity in the World Health Organization classification of AML. Clinical and survival data suggest that patients with this form of AML often have a more favorable prognosis, which may be due to the immunogenicity created by the mutations in the NPM1 protein. Consequently, AML with NPM1mut can be considered an immunogenic subtype of AML. However, the underlying mechanisms of this immunogenicity and associated favorable survival outcomes need to be further investigated. Immune checkpoint molecules, such as the programmed cell death-1 (PD-1) protein and its ligand, PD-L1, play important roles in leukemogenesis through their maintenance of an immunosuppressive tumor microenvironment. Preclinical trials have shown that the use of PD-1/PD-L1 checkpoint inhibitors in solid tumors and lymphoma work best in novel therapy combinations. Patients with AML NPM1mut may be better suited to immunogenic strategies that are based on the inhibition of the PD-1 immune checkpoint pathway than patients without this mutation, suggesting the genetic landscape of patients may also inform best practice for the use of PD-1 inhibitors.

Recombinant human adenovirus type 5 promotes anti-tumor immunity via inducing pyroptosis in tumor endothelial cells.

Recombinant human type 5 adenovirus (H101) is an oncolytic virus used to treat nasopharyngeal carcinoma. Owing to the deletion of the E1B-55kD and E3 regions, H101 is believed to selectively inhibit nasopharyngeal carcinoma. Whether H101 inhibits other type of tumors via different mechanisms remains unclear. In this study we investigated the effects of H101 on melanomas. We established B16F10 melanoma xenograft mouse model, and treated the mice with H101 (1 × 108 TCID50) via intratumoral injection for five consecutive days. We found that H101 treatment significantly inhibited B16F10 melanoma growth in the mice. H101 treatment significantly increased the infiltration of CD8+ T cells and reduced the proportion of M2-type macrophages. We demonstrated that H101 exhibited low cytotoxicity against B16F10 cells, but the endothelial cells were more sensitive to H101 treatment. H101 induced endothelial cell pyroptosis in a caspase-1/GSDMD-dependent manner. Furthermore, we showed that the combination of H101 with the immune checkpoint inhibitor PD-L1 antibody (10 mg/kg, i.p., every three days for three times) exerted synergic suppression on B16F10 tumor growth in the mice. This study demonstrates that, in addition to oncolysis, H101 inhibits melanoma growth by promoting anti-tumor immunity and inducing pyroptosis of vascular endothelial cells.

Adverse Events of PD-1, PD-L1, CTLA-4, and LAG-3 Immune Checkpoint Inhibitors: An Analysis of the FDA Adverse Events Database.

This study aimed to identify the 25 most prevalent adverse events (AEs) associated with FDA-approved immune checkpoint inhibitors (ICIs)-specifically, PD-1, PD-L1, CTLA-4, and LAG-3 inhibitors-using data from the FDA Adverse Events Reporting System (FAERS), a publicly available repository of reported drug adverse events, and AERSMine, an open-access pharmacovigilance tool, to investigate these adverse events. For PD-1 inhibitors, the most common AEs were diarrhea, fatigue, and pyrexia, with notable instances of neutropenia and hypothyroidism, particularly with toripalimab and dostarlimab. PD-L1 inhibitors also frequently caused pyrexia, diarrhea, and fatigue, with interstitial lung disease and hypothyroidism showing a class effect, and drug-specific AEs such as hepatotoxicity and chills. CTLA-4 inhibitors predominantly resulted in diarrhea and colitis, with ipilimumab frequently causing pyrexia and rash, while tremelimumab exhibited unique AEs such as biliary tract infection. The LAG-3 inhibitor relatlimab reported fewer AEs, including pyrexia and pneumonia. Rare but significant AEs across all inhibitors included myocarditis and myasthenia gravis. This study provides a detailed overview of the 25 most common AEs associated with ICIs, offering valuable insights for clinical decision-making and AE management. Further research is necessary to elucidate the mechanisms underlying these AEs and to develop targeted interventions to enhance the safety and efficacy of ICI therapy in patients with cancer.

Retrospective cohort study characterizing PD-1/PD-L1 checkpoint inhibition associated Stevens-Johnson syndrome and toxic epidermal necrolysis

Retrospective cohort study characterizing PD-1/PD-L1 checkpoint inhibition associated Stevens-Johnson syndrome and toxic epidermal necrolysis

The immunomodulatory ballet of tumour-derived extracellular vesicles and neutrophils orchestrating the dynamic CD73/PD-L1 pathway in cancer.

Head and neck squamous cell carcinoma (HNSCC) is a global cancer burden with a 5-year overall survival rate of around 50%, stagnant for decades. A tumour-induced immunosuppressive microenvironment contributes to HNSCC progression, with the adenosine (ADO) pathway and an upregulated expression of inhibitory immune checkpoint regulators playing a key role in this context. The correlation between high neutrophil-to-lymphocyte ratio (NLR) with advanced tumour staging suggests involvement of neutrophils (NØ) in cancer progression. Interestingly, we associated a high NLR with an increased intracellular PD-L1 localization in primary HNSCC samples, potentially mediating more aggressive tumour characteristics and therefore synergistically favouring tumour progression. Still, further research is needed to harness this knowledge for effective treatments and overcome resistance. Since it is hypothesized that the tumour microenvironment (TME) may be influenced by small extracellular vesicles (sEVs) secreted by tumours (TEX), this study aims to investigate the impact of HNSCC-derived TEX on NØ and blockade of ADO receptors as a potential strategy to reverse the pro-tumour phenotype of NØ. UMSCC47-TEX exhibited CD73 enzymatic activity involved in ADO signalling, as well as the immune checkpoint inhibitor PD-L1. Data revealed that TEX induce chemotaxis of NØ and the sustained interaction promotes a shift into a pro-tumour phenotype, dependent on ADO receptors (P1R), increasing CD170high subpopulation, CD73 and PD-L1 expression, followed by an immunosuppressive secretome. Blocking A3R reduced CD73 and PD-L1 expression. Co-culture experiments with HNSCC cells demonstrated that TEX-modulated NØ increase the CD73/PD-L1 axis, through Cyclin D-CDK4/6 signalling. To support these findings, the CAM model with primary tumour was treated with NØ supernatant. Moreover, these NØ promoted an increase in migration, invasion, and reduced cell death. Targeting P1R on NØ, particularly A3R, exhibited potential therapeutic strategy to counteract immunosuppression in HNSCC. Understanding the TEX-mediated crosstalk between tumours and NØ offers insights into immunomodulation for improving cancer therapies.

Virtual clinical trials via a QSP immuno-oncology model to simulate the response to a conditionally activated PD-L1 targeting antibody in NSCLC

AbstractRecently, immunotherapies for antitumoral response have adopted conditionally activated molecules with the objective of reducing systemic toxicity. Amongst these are conditionally activated antibodies, such as PROBODY® activatable therapeutics (Pb-Tx), engineered to be proteolytically activated by proteases found locally in the tumor microenvironment (TME). These PROBODY® therapeutics molecules have shown potential as PD-L1 checkpoint inhibitors in several cancer types, including both effectiveness and locality of action of the molecule as shown by several clinical trials and imaging studies. Here, we perform an exploratory study using our recently published quantitative systems pharmacology model, previously validated for triple-negative breast cancer (TNBC), to computationally predict the effectiveness and targeting specificity of a PROBODY® therapeutics drug compared to the non-modified antibody. We begin with the analysis of anti-PD-L1 immunotherapy in non-small cell lung cancer (NSCLC). As a first contribution, we have improved previous virtual patient selection methods using the omics data provided by the iAtlas database portal compared to methods previously published in literature. Furthermore, our results suggest that masking an antibody maintains its efficacy while improving the localization of active therapeutic in the TME. Additionally, we generalize the model by evaluating the dependence of the response to the tumor mutational burden, independently of cancer type, as well as to other key biomarkers, such as CD8/Treg Tcell and M1/M2 macrophage ratio. While our results are obtained from simulations on NSCLC, our findings are generalizable to other cancer types and suggest that an effective and highly selective conditionally activated PROBODY® therapeutics molecule is a feasible option.

Cognitive symptoms in patients with cancer receiving PD-1/PD-L1 checkpoint inhibitors: Insights from a cross-sectional pilot study.

12094 Background: Cancer-related cognitive impairment is common with traditional therapeutic modalities, affecting memory, psychomotor speed, attention, and executive function of up to 75% of adults with cancer. Over the past decade, immune checkpoint inhibitors (ICIs) have emerged as novel and efficacious treatments due to their ability to penetrate the blood-brain barrier and improve survival rates. However, they come with significant short- and long-term complications, including neurological toxicities. Despite their benefits, the impact of ICIs on cognitive function is not well understood. This study aims to examine the frequency and severity of cognitive impairment and the factors correlated among adults with cancer receiving ICIs. Methods: We collected questionnaire data on cognitive function using the Functional Assessment of Cancer Therapy-Cognitive Function (FACT-Cog) and other concurrent symptoms, as well as saliva samples of a subset of inflammatory cytokines from patients treated with PD-1/PD-L1 checkpoint inhibitors between 2022 and 2023. Sample characteristics were described using mean, frequency, and percentage. To analyze the relationship among symptoms and demographics, we used Pearson’s correlation and the Mann-Whitney U test. Saliva cytokines were analyzed using ELISA assays. This study is IRB approved. Results: Twenty-three patients (male: n=11, female: n=12) have received ICIs for an average of eight months, with a mean age of 70.87±11.63 years. 78.3% had melanoma/skin cancer, 8.7% had head and neck cancer, and 13% had other malignancies. Pembrolizumab was administered to 47.8%, and Nivolumab to 26.1%. The mean scores of FACT-Cog for perceived cognitive impairment (PCI) and perceived cognitive abilities (PCA) were 60.87±13.06 (maximum: 72) and 22.30±6.70 (maximum: 28), respectively. 26.1% of participants (n=6) reported lower scores than the cut-off in both PCI (cut-off: ≤55.1) and PCA (cut-off: ≤19.5). Lower FACT-Cog PCI scores were significantly correlated with older age ( r=-.511, p&lt;.05), greater fatigue ( r=-.483, p&lt;.05) and pain ( r=-.558, p&lt;.01). Participants with PCA and PCI scores below the cut-off showed higher mean concentrations of IL-1β (mean±SE: 188.22±133.72 vs. 80.99±14.73pg/mL), CRP (6659.47±3027.58 vs. 3910.71±1022.41pg/mL), and IL-6 (109.24±56.07 vs. 30.22±6.26pg/mL) compared to those with scores above the cut-off, although the results were not significant. This suggests that increased inflammatory cytokines may be associated with cognitive impairment. Conclusions: This preliminary study suggests that some patients may experience cognitive impairment during ICI treatment. As cancer patients are more at risk for cognitive impairment before treatment, a longitudinal study is warranted to confirm cognitive function both pre- and post-immunotherapy, along with objective measures of cognitive performance.

PD-1 checkpoint inhibitors related immune-mediated hepatitis in colon cancer: A systematic review and meta-analysis.

e14615 Background: Immune checkpoint inhibitors have revolutionized the management of advanced colon cancers by targeting programmed death-1 (PD-1) proteins. Along with PD-1, other checkpoint inhibitors PDL-1 and CTL4 have been approved for the treatment of various type of cancers since a decade. However, many immune-related side effects have been associated with them. There is limited data in the literature on PD-1 related hepatotoxicity, mainly immune mediated hepatitis. This systematic review and meta-analysis aim to study the impact of PD-1 checkpoint inhibitors on immune-mediated hepatitis in the context of colon cancer, its incidence among different immunotherapies, risk factors associated with it and exploring treatment modalities. Methods: The study was conducted in accordance with PRISMA guidelines. Multiple databases such as PubMed, EMBASE, Scopus, Cochrane Library and Web of Science from past 10 years were searched up to November 2023. Studies from cohort studies, randomized control trials and case series that have reported on immune-mediated hepatitis in colon cancer patients treated with PD-1 inhibitors were included. Results: Overall pooled incidence of immune mediated hepatitis was between 1% -5% with an average of 4.1% (95% CI, 2.8-5.8) among patients with advanced colon cancer treated with PD-1 inhibitors. Among different inhibitors, incidence was lowest with Pembrolizumab, around 1.4%; and highest with Cemiplimab with 5.1%. This is crucial in optimizing treatment for advanced colon cancers. The meta-analysis also found risk factors of male gender, older age and pre-existing liver-conditions (Hepatitis B and C), contributing to the development of hepatitis. Subgroup analysis will be performed to explore potential differences in incidence rates based on patient characteristics, dosages of medications, duration of treatment and concomitant medications. Other objectives include determining the timeline and grades of toxicity. Conclusions: By incorporating data from other studies and understating safety profiles, the findings will highlight the need for close surveillance for toxicity monitoring. This would also provide insight for clinical providers to make informed decisions regarding treatment selection. Toxicities are noted to be under-reported; hence we urge clinicians to report such immune toxicities. Further research is needed to elucidate underlying mechanisms to develop strategies for mitigating adverse events.

SWOG S2012: Randomized phase II/III trial of first line platinum (P)/etoposide (E) with or without atezolizumab (NSC #783608) in patients with advanced or metastatic poorly differentiated extrapulmonary neuroendocrine carcinomas (NEC).

TPS4201 Background: Poorly differentiated, extrapulmonary NEC are rare cancers with median overall survival (OS) &lt;1 year. Treatment is extrapolated from small cell lung cancer (SCLC) with use of P (cisplatin or carboplatin) + E. More effective treatment regimens and predictive biomarkers are needed to improve outcomes. In SCLC, induction therapy with combination of P/E + PD-L1 checkpoint inhibitor atezolizumab and maintenance atezolizumab improved OS (12.3 months vs 10.3 months; HR 0.70, 95% CI 0.54 – 0.91, P=0.007) vs P/E alone (1). No study to date has compared PD-1/PD-L1 inhibition during induction only vs during induction and maintenance therapy. In SCLC, distinct molecular subtypes can be identified by the presence of specific transcription factors (e.g., ASCL1, NEUROD1, POU2F3) or an inflamed gene signature (SCLC-I), with SCLC-I pts more likely to benefit clinically from the addition of immunotherapy (2). In this study we plan to test the benefit of adding atezolizumab to induction P/E as well as the role of adding maintenance atezolizumab after induction P/E plus atezolizumab. We also plan to correlate tumor- and blood-based subtype biomarkers with response to therapy. Methods: Eligible pts ≥18 years old have evaluable, histologically confirmed extrapulmonary NEC, Zubrod PS ≤2, and are allowed to have up to 1 cycle of P/E prior to enrollment. P (cisplatin 75 mg/m2 or carboplatin AUC 5, iv) on day 1, E 100 mg/m2 iv on days 1-3, and atezolizumab 1200 mg iv on day 1 of q21 day cycles. Pts are randomized to 1 of 3 arms: A) Induction P/E + atezolizumab -&gt; maintenance atezolizumab B) Induction P/E + atezolizumab -&gt; observation C) Induction P/E -&gt; observation. The primary objective is to compare the overall survival (OS, from randomization) between arms in a fixed sequence: A vs C -&gt; B vs C -&gt; A vs B. Secondary objectives include comparing OS (from start of maintenance/observation), progression free survival, response rate, duration of response, and safety/tolerability across arms. Tumor and blood samples will be banked for future biomarker analyses, including immunohistochemistry of transcription factors on tissue and whole exome sequencing on tumor and circulating tumor DNA. With 189 pts (168 eligible), the study has 84% power to detect an improvement in 12-months OS from 35% to 57.5% (HR 0.53). This study was activated December 2021 with 3 pts enrolled over 1 year due to restricting enrollment of NEC of small cell histology only. The protocol was amended in January 2023 to broaden eligibility to all NEC subtypes (small cell, large cell, and undefined histology with Ki-67 ≥55%). As of January 2024, 35 patients have been enrolled. A protocol amendment is planned to remove the need for Ki-67 index for NEC of genitourinary origin to improve accrual. 1. Horn L, et al. N Engl J Med 2018. 2. Gay CM, et al. Cancer Cell 2021. Clinical trial information: NCT05058651 .

Advances in Hodgkin Lymphoma Treatment: From Molecular Biology to Clinical Practice.

Classical Hodgkin Lymphoma (cHL) is a highly curable disease, but around 20% of patients experience progression or relapse after standard frontline chemotherapy regimens. Salvage regimens followed by autologous stem cell transplants represent the historical treatment approach for these cases. In the last decade, with the increasing understanding of cHL biology and tumor microenvironment role in disease course, novel molecules have been introduced in clinical practice, improving outcomes in the relapsed/refractory setting. The anti-CD30 antibody-drug conjugated brentuximab vedotin and PD-1/PD-L1 checkpoint inhibitors represent nowadays curative options for chemorefractory patients, and randomized trials recently demonstrated their efficacy in frontline immune-chemo-combined modalities. Several drugs able to modulate the patients' T-lymphocytes and NK cell activity are under development, as well as many anti-CD30 chimeric antigen receptor T-cell products. Multiple tumor aberrant epigenetic mechanisms are being investigated as targets for antineoplastic compounds such as histone deacetylase inhibitors and hypomethylating agents. Moreover, JAK2 inhibition combined with anti-PD1 blockade revealed a potential complementary therapeutic pathway in cHL. In this review, we will summarize recent findings on cHL biology and novel treatment options clinically available, as well as promising future perspectives in the field.

Nanoparticle-enhanced PD-1/PD-L1 targeted combination therapy for triple negative breast cancer.

Breast cancer with triple-negative subtype (TNBC) presents significant challenges with limited treatment options and a poorer prognosis than others. While PD-1/PD-L1 checkpoint inhibitors have shown promise, their efficacy in TNBC remains constrained. In recent years, nanoparticle (NP) technologies offer a novel approach to enhance cancer therapy by optimizing the tumor microenvironment and augmenting chemo- and immunotherapy effects in various preclinical and clinical settings. This review discusses recent investigations in NP strategies for improving PD-1/PD-L1 blockade-based combination therapy for TNBC. Those include single or multi-therapeutic NPs designed to enhance immunogenicity of the tumor, induce immunogenic cell death, and target immunosuppressive elements within the tumor microenvironment. The investigations also include NPs co-loaded with PD-L1 inhibitors and other therapeutic agents, leveraging targeted delivery and synergistic effects to maximize efficacy while minimizing systemic toxicity. Overall, NP approaches represent a promising avenue for enhancing PD-1/PD-L1 checkpoint blockade-based combination therapy in TNBC and encourage further developmental studies.

A multiplex UPLC-MS/MS method for the quantification of three PD-L1 checkpoint inhibitors, atezolizumab, avelumab, and durvalumab, in human serum

Background and aimTo support pharmacokinetic studies, a multiplex UPLC-MS/MS assay was developed and validated to quantify PD-L1 checkpoint inhibitors atezolizumab, avelumab, and durvalumab in serum. MethodsA bottom-up sample pre-treatment procedure was developed to determine atezolizumab, avelumab, and durvalumab in serum. This procedure consisted of (1) precipitation of the monoclonal antibody with ammonium sulfate, (2) reduction with dithiothreitol, (3) denaturation with methanol, and (4) tryptic digestion of the protein. The unique signature peptides resulting after sample pre-treatment of the antibodies were measured using UPLC-MS/MS with a total run time of 11 minutes. The clinical application was evaluated by analyzing 114 atezolizumab patient samples. ResultsThe developed method was found to be accurate and precise for all three analytes over a concentration range of 3.00–150 µg/mL. No endogenous interference was present in serum samples. Cross-interference experiments showed no cross-analyte interference and acceptable cross-internal standard interference. In addition, no substantial carry-over was observed. The stable isotopically labeled signature peptides were most effective in compensating for matrix effects. Recovery based on back-calculated concentrations of calibration standards and quality control samples was found to be high. The analytes were stable for at least three freeze-thaw cycles, for 42 hours at processing conditions, for at least two days at 2–8°C in the final extract, for five days before re-injection analysis at 4°C, and long-term for at least 11 months at −70°C. The assay was tested for its applicability in clinical practice. For this purpose, 114 atezolizumab patient samples were measured. ConclusionA multiplex UPLC-MS/MS assay was developed and validated to quantify atezolizumab, avelumab, and durvalumab in human serum. The applicability of this method was demonstrated by the analysis of clinical atezolizumab samples. The method is suitable to support clinical pharmacokinetic studies involving atezolizumab, avelumab, or durvalumab.

Depth-dependent PD-L1 sampling of head and neck squamous cell carcinoma (HNSCC) – implications for PD-1/PD-L1 checkpoint inhibitor immunotherapy

At present, PD-L1 scoring is the gold standard in evaluating a cancer patient's suitability for receiving PD-1/PD-L1 checkpoint inhibitor immunotherapy (CIT). Either tumor proportion score (TPS) or combined positive score (CPS) can be used to select head and neck squamous cell carcinoma (HNSCC) patients for immunotherapy. However, the current clinical workflow only uses one histological section for PD-L1 scoring. The considerable under-sampling of a patient's tissue may lead to an inaccurate PD-L1 score, potentially affecting treatment outcomes. In this study, we selected formalin-fixed, paraffin-embedded (FFPE) tissue blocks from five HNSCC patients. The thickness of each of these tissue blocks allowed us to determine the tumor proportion score (TPS) and combined positive score (CPS) at five depths with adjacent layers separated by 500 μm. We found that although there are variations of scores among different tissue sections, the scores are generally consistent across the tissue block from each patient. We also compared TPS and CPS values at different sampling frequencies with a single section and sections separated by 1000, 1500, and 2000 μm. We found that in all cases, the values all fall within one standard deviation of the average values of all five depths. Considering the different threshold values of TPS and CPS for treatment decisions, our results suggest that in cases where the patients' scores are close to that of the threshold values, scoring of two histological sections separated by 2000 μm should be considered.

Abstract A040: Assessing the ability of Fc3TSR to remodel the tumor microenvironment and enhance efficacy of immunotherapies and chemotherapy in a murine model of pancreatic ductal adenocarcinoma

Abstract Introduction: Pancreatic Ductal Adenocarcinoma (PDAC) has a poor survival rate due to late diagnosis where metastasis has often occurred. Angiogenesis, the process by which new vessels form from pre-existing vasculature, is crucial for tumor growth and metastasis. Tumors aggressively upregulate expression of pro-angiogenic factors, stimulating rapid vessel formation. These vessels often lack pericyte coverage and have dysfunctional morphology, leading to high interstitial fluid pressure (IFP). Impaired perfusion and high IFP impede therapy uptake. Fc3TSR is a novel fusion protein derived from the potent angiogenic inhibitor thrombospondin 1, which we have shown to normalize vasculature in ovarian cancer, significantly decreasing tumor size and improving uptake of many therapies. In this study, we evaluated Fc3TSR’s ability to remodel the tumor microenvironment to induce tumor regression and to enhance efficacy of other therapies. Methods: We developed an orthotopic syngeneic murine model of PDAC, whereby we surgically injected 2.5 × 104 murine PDAC cells (KPC) into the tail of the pancreas of C57BL/6 mice. Tumors were allowed to progress for 14 days before intraperitoneal (IP) administration of Fc3TSR (0.158mg/kg) or PBS (control) on day 14 and 21. Gemcitabine (GEM) chemotherapy treated mice received either daily, metronomic dosages of GEM, or weekly, maximum tolerated dosages GEM starting on day 23. Checkpoint inhibitor mice received either PD-L1 (25ug) or CTLA4 (25ug) checkpoint inhibitors on day 23 and 26. Mice were euthanized on day 30 and tumors and the draining lymph nodes were collected and weighed. 1 hour before euthanasia, Fc3TSR and PBS mice were IP injected with Hypoxyprobe (Pimonidazole Hydrochloride) and tumors were immunostained for markers of blood vessels and tumor hypoxia. Results: Fc3TSR induced tumor regression when compared to PBS, but GEM at either dosage did not further enhance this effect. Following Fc3TSR, PD-L1, but not CTLA-4 checkpoint inhibitors significantly reduced tumor size when compared to mice pre-treated with PBS. Fc3TSR treatment also reduced the area of tumor hypoxia. Tumor vasculature is currently being imaged and analyzed for Fc3TSR’s effect on vessel morphology. Conclusion: Our data suggests that normalizing the tumor microenvironment can enhance the uptake and efficacy of combination therapies. Enhanced perfusion could facilitate the migration of activated immune cells and may enhance immune responses in PDAC patients. Here we demonstrate a novel approach to optimize therapeutic efficacy in advanced stage PDAC. Citation Format: Bianca Garlisi, Caroline Aitken, Sylvia Lauks, Julia Stewart, Duncan Petrik, Jack Lawler, Jim Petrik. Assessing the ability of Fc3TSR to remodel the tumor microenvironment and enhance efficacy of immunotherapies and chemotherapy in a murine model of pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr A040.

Integrin αvβ6 mediates the immune escape through regulation of PD-L1 and serves as a novel marker for immunotherapy of colon carcinoma.

The immune escape of colon cancer and its role in the response to immunotherapies such as PD-1/PD-L1 checkpoint inhibitors have long been of great interest. The positive outcomes of immunotherapy are limited by the immunosuppressive nature of the tumor microenvironment. Integrin αvβ6, which can regulate the progression of colon cancer, was recently reported to be involved in the immune suppression of colon cancer. In the present study, we explored the correlation between αvβ6 and PD-L1 expression by immunohistochemistry of colon cancer tissues. Then, the regulation of PD-L1 signaling by αvβ6 in colon cancer cells was demonstrated. We constructed an in vivo model and performed immunophenotyping experiments to analyze further the regulation of the immune response by αvβ6. The role of αvβ6 in the response to anti-PD-1 therapy in colon cancer was also verified. αvβ6-positive tissues exhibited increased PD-L1 expression. Inhibition of αvβ6 not only downregulated constitutive PD-L1 expression but also decreased IFN-γ-induced PD-L1 expression. In addition, αvβ6-induced PD-L1 expression was suppressed by the ERK inhibitor PD98059, and knockdown of the β6-ERK2 binding site had the equivalent effect. αvβ6 decreased CD8+ T cell infiltration and granzyme B expression in CD8+ T cells in colon cancer patients. Furthermore, mice engrafted with αvβ6-expressing colon cancer cells exhibited an unsatisfactory response to anti-PD-1 therapy, and anti-PD-1-induced increases in CD4+ and CD8+ T cell infiltration could be inhibited by αvβ6. These results indicate that αvβ6 mediates immune escape in colon cancer by upregulating PD-L1 through the ERK/MAPK pathway. Moreover, αvβ6 could serve as a marker for the efficacy of anti-PD-1 therapy in colon cancer.

Allograft Rejection Following Immune Checkpoint Inhibition After Renal Transplantation: An In-Depth Analysis of PD-1, PDL-1, and CTLA-4 Checkpoint Inhibitors

Allograft Rejection Following Immune Checkpoint Inhibition After Renal Transplantation: An In-Depth Analysis of PD-1, PDL-1, and CTLA-4 Checkpoint Inhibitors

Efficacy and safety of pembrolizumab in advanced neuroendocrine tumors (NETs): A meta-analysis of clinical trials.

165 Background: Patients with recurrent or metastatic neuroendocrine tumors (NETs) have limited treatment options and a poor prognoses. Programmed death–ligand 1 (PD-L1) has been associated with the pathogenesis, progression, and prognosis of NETs. This article analyzes the efficacy and safety profile of PDL1 inhibitor Pembrolizumab in advanced NETs. Our objective is to identify all the clinical trials in which Pembrolizumab has been assessed in treating NETs and to evaluate the efficacy and safety profile in this patient population with high power. Methods: Systemic searches of PubMed, the Cochrane Library, and ClinicalTrials.gov were conducted with prespecified terms. The outcomes studied in our analysis were objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS), overall survival (OS), and serious adverse events (AEs). We calculated the pooled ORR for these studies using weighted pooled ORR = Σ (ORR_i * weight_i). We calculated the standard error using the formula SE = √(Σ (wi x (1 - ORRi) x ORRi) / Σ (wi x ni)) and the 95% confidence interval using the formula CI = ORR ± (1.96 x SE). This statistical method was also used to calculate our study's pooled DCR, PFS, OS, and serious AEs. However, it is essential to note that the pooled data is only as reliable as the individual data estimates from each study and may be subject to bias or confounding factors. Results: Five clinical trials met the inclusion criteria, including patients with gastrointestinal, pancreatic, lung, and lower genital tract NETs. Outcome data were available for all five studies, comprising 177 patients with NETs who received Pembrolizumab as part of the treatment regimen (Table). The pooled ORR and DCR were 5.27% (95% CI 2.23-8.31) and 5.4% (95% CI 3-7.8), respectively. The pooled weighted PFS was 4.4 months, and pooled weighted OS was 23.3 months. These findings suggest that Pembrolizumab has a promising ORR, DCR, PFS, and OS. Safety was a secondary endpoint, and the pooled serious AEs were noted in 20.9% of patients. Conclusions: Pembrolizumab demonstrated statistically significant efficacy and safety profile in a subset of patients with NETs and was overall well-tolerated. In recent years, the combination strategy of tyrosine kinase inhibitors (TKI) with PDL-1 checkpoint inhibitors has shown promising clinical benefits in patients with various solid tumors. Further studies are needed to analyze the efficacy and safety of TKI with PD-L1 inhibitors in NETs. [Table: see text]

Probing the origins of programmed death ligand-1 inhibition by implementing machine learning-assisted sequential virtual screening techniques.

PD-L1 is a key immunotarget involved in binding to its receptor PD-1. PD-L1/PD-1 interface blocking using antibodies (or small molecules) is the central area of interest for tumor suppression in various cancers. Blocking the PD-L1/PD-1 pathway in the tumor cells results in its immune activation and destruction, and thereby restoring the T-cell proliferation and cytokine production. The active binding site interface residues of PD-L1/PD-1 were experimentally known and proven by structural biology and site-directed mutagenesis studies. Structure-based molecular design technique was employed to identify the inhibitors for blocking the PD-L1/PD-1 interface. Nine hits to leads were identified from the SPECS small molecule database by machine learning, molecular docking, and molecular dynamics simulation techniques. Following this, a machine learning-assisted QSAR modeling approach was implemented using ChEMBL database to gain insights into the inhibitory potential of PD-L1 inhibitors and predict the activity of our previously screened nine hit molecules. The best leads identified in the present study bind strongly with the active sites of PD-L1/PD-1 interface residues, which include A121, M115, I116, S117, I54, Y56, D122, and Y123. These computational leads are considered promising molecules for furtherin vitroandin vivoanalysis to be developed as potential PD-L1 checkpoint inhibitors to cure different types of cancers.