PD-1 Protein Research Articles

Engineered Nanoparticles for Enhanced Antitumoral Synergy Between Macrophages and T Cells in the Tumor Microenvironment.

T cells and macrophages have the potential to collaborate to eliminate tumor cells efficiently. Macrophages can eliminate tumor cells through phagocytosis and subsequently activate T cells by presenting tumor antigens. The activated T cells, in turn, can kill tumor cells and redirect tumor-associated macrophages toward an antitumoral M1 phenotype. However, checkpoint molecules expressed on tumor cells impede the collaborative action of these immune cells. Meanwhile, monotherapy with a single immune checkpoint inhibitor (ICI) for either macrophages or T cells yields suboptimal efficacy in cancer patients. To address this challenge, here a nanoparticle capable of efficiently delivering dual ICIs to tumors for both macrophages and T cells is developed. These programmed cell death protein 1 (PD-1)-transfected macrophage membrane-derived nanoparticles (PMMNPs) can target tumors and provide signal-regulatory protein alpha and PD-1 to block CD47 and programmed cell death-ligand 1 (PD-L1), respectively, on tumor cells. PMMNPs enhance macrophage-mediated cancer cell phagocytosis and antigen presentation, promote T cell activation, and induce the reprogramming of macrophages toward an antitumoral phenotype. In syngeneic tumor-bearing mice, PMMNPs demonstrate superior therapeutic efficacy compared to nanoparticles delivering single ICIs and non-targeted delivery of anti-CD47 and anti-PD-L1 antibodies. PMMNPs capable of augmenting the antitumoral interplay between macrophages and T cells may offer a promising avenue for cancer immunotherapy.

450. TISSUE RESIDENT MEMORY CELLS: CORRELATING THE PHENOTYPIC AND FUNCTIONAL CAPABILITIES OF A POTENTIAL TUMOUR REACTIVE CELL POPULATION IN OESOPHAGEAL ADENOCARCINOMA

Abstract Background Oesophageal adenocarcinoma (OAC) is a disease with a high mortality and morbidity rate. Immunotherapy has recently demonstrated progress in the treatment of OAC but its impact on long term survival is currently uncertain. Tissue resident memory (TRM) T cells are a subset of lymphocytes within the tumour/tissue infiltrating lymphocyte (TIL) milieu that has attracted considerable interest within cancer immunology. Although TRM cells have been associated with better outcomes in multiple cancer types there is a lack of knowledge of their role in OAC. This study aims to critically correlate the phenotype of TRM with their functional capacity in this disease. Methods 33 patients undergoing surgical resection for OAC were recruited and consented for collection of fresh tumour (T), adjacent normal tissue (AN), and peripheral blood. Peripheral blood mononuclear cell (PBMC) from blood and infiltrating lymphocytes from T and AN were isolated using standard density gradient and enzymatic digestion protocols. Multiparametric flow cytometry was performed on 12 patients using matched PBMC, T and AN infiltrating lymphocytes for phenotypic analysis and 21 patients for functional analysis following cell stimulation assay. BD FACSymphony was used for data acquisition and data analysed on FlowJo version 10.10. Statistical analysis was carried out using GraphPad Prism. Results TRM (CD103+CD69+) dominated the CD8+ T cell population of T and AN TIL. Expression of checkpoint proteins PD1+ and CD39+, a marker of tumour reactivity, was identified on CD8+ TRM and CD8+ non TRM in TIL. The differentiation status of TRM within memory lineages demonstrated that TRM express a higher proportion of effector memory cells (CCR7-CD45RA) compared to those in blood. TRM cells also showed lower expression of the transcription factors EOMES, TBET and TCF compared to CD8+ cells within PBMC. Moreover, tumour CD8+ TRM populations had reduced ability to produce IL-2 following stimulation compared to adjacent normal TRM populations. Conclusion TRM make up a large proportion of CD8+ T cell within the tumour microenvironment (TME) of OAC. TRM generation is associated with the downregulation of T-Box transcription factors EOMES and TBET and expression of an effector memory phenotype with reduction of the stem-like transcription factor, TCF. High levels of CD39+ indicate a strong level of activation but the increased PD1 expression and reduced capability to produce IL2 indicate functional impairment suppressed within the TME. An opportunity may exist to reverse this with novel immunotherapeutic agents.

A study on the efficacy and Safety Evaluation of a novel PD-1/CTLA-4 bispecific antibody

Tumors constitute a significant health concern for humans, and PD-1 and CTLA-4 monoclonal antibodies have been proven effective in cancer treatment. Some researchers have identified that the combination of PD-1 and CTLA-4 dual blockade demonstrates superior therapeutic efficacy. However, the development of PD-1/CTLA-4 bispecific antibodies faces challenges in terms of both safety and efficacy. The present study discloses a novel PD-1/CTLA-4 bispecific antibody, designated as SH010. Experimental validation through surface plasmon resonance (SPR) confirmed that SH010 exhibits favorable binding activity with both PD-1 and CTLA-4. Flow cytometry analysis demonstrated stable binding of SH010 antibody to CHOK1 cells overexpressing human or cynomolgus monkey PD-1 protein and to 293F cells overexpressing human or cynomolgus monkey CTLA-4 protein. Moreover, it exhibited excellent blocking capabilities in protein binding between human PD-1 and PD-L1, as well as human CTLA-4 and CD80/CD86. Simultaneously, in vitro experiments indicate that SH010 exerts a significant activating effect on hPBMCs. In murine transplant models of human prostate cancer (22RV1) and small cell lung cancer (NCI-H69), administration of varying concentrations of the bispecific antibody significantly inhibits tumor growth. MSD analysis revealed that stimulation of hPBMCs from three different donors with SH010 did not induce the production of cytokine release syndrome. Furthermore, Single or repeated intravenous administrations of SH010 in cynomolgus monkeys show favorable systemic exposure without noticeable drug accumulation or apparent toxicity. In conclusion, SH010 represents a novel cancer therapeutic drug poised to enter clinical trials and obtain market approval.

Process Design of CDMO Aseptic Formulation Workshop for PD-1 Antibody and Protein Products

Process Design of CDMO Aseptic Formulation Workshop for PD-1 Antibody and Protein Products

Function-first discovery of high affinity monoclonal antibodies using Nanovial-based plasma B cell screening.

Antibody discovery technologies, essential for research and therapeutic applications, have evolved significantly since the development of hybridoma technology. Various in vitro (display) and in vivo (animal immunization and B cell-sequencing) workflows have led to the discovery of antibodies against diverse antigens. Despite this success, standard display and B-cell sequencing-based technologies are limited to targets that can be produced in a soluble form. This limitation inhibits the screening of function-inducing antibodies, which require the target to be expressed in cells to monitor function or signaling, and antibodies targeting proteins that maintain their physiological structure only when expressed on cell membranes, such as G-protein coupled receptors (GPCRs). A high-throughput two-cell screening workflow, which localizes an antibody-secreting cell (ASC) and a cell expressing the target protein in a microenvironment, can overcome these challenges. To make function-first plasma cell-based antibody discovery accessible and scalable, we developed hydrogel Nanovials that can capture single plasma cells, target-expressing cells, and plasma cell secretions (antibodies). The detection and isolation of Nanovials harboring the antigen-specific plasma cells are then carried out using a flow cytometry cell sorter - an instrument that is available in most academic centers and biopharmaceutical companies. The antibody discovery workflow employing Nanovials was first validated in the context of two different cell membrane-associated antigens produced in recombinant form. We analyzed over 40,000 plasma cells over two campaigns and were able to identify a diversity of binders that i) exhibited high affinity (picomolar) binding, ii) targeted multiple non-overlapping epitopes and iii) demonstrated high developability scores. A campaign using the two-cell assay targeting the immune checkpoint membrane protein PD-1 yielded cell binders with similar EC50s to clinically used Pembrolizumab and Nivolumab. The highest selectivity for binders was observed for sorted events corresponding with the highest signal bound to target cells on Nanovials. Overall, Nanovials can provide a strong foundation for function-first antibody discovery, yielding direct cell binding information and quantitative data on prioritization of hits with flexibility for additional functional readouts in the future.

TIGIT expression in renal cell carcinoma infiltrating T cells is variable and inversely correlated with PD-1 and LAG3

PurposeImmune checkpoint inhibitors have revolutionized the treatment of renal cell carcinoma (RCC), but many patients do not respond to therapy and the majority develop resistant disease over time. Thus, there is increasing need for alternative immunomodulating agents. The co-inhibitory molecule T-cell immunoglobulin and ITIM domain (TIGIT) may play a role in resistance to approved immune checkpoint inhibitors and is being investigated as a potential therapeutic target. The purpose of this study was to quantify TIGIT positivity in tumor-infiltrating T cells in RCC.MethodsWe employed tissue microarrays containing specimens from primary RCC tumors, adjacent normal renal tissue, and RCC metastases to quantify TIGIT within tumor-infiltrating CD3+ T cells using quantitative immunofluorescent analysis. We also compared these results to TIGIT+ CD3+ levels in four other tumor types (melanoma, non-small cell lung, cervical, and head and neck cancers).ResultsWe did not observe significant differences in TIGIT positivity between primary RCC tumors and patient-matched metastatic samples. We found that the degree of TIGIT positivity in RCC is comparable to that in lung cancer but lower than that in melanoma, cervical, and head and neck cancers. Correlation analysis comparing TIGIT positivity to previously published, patient-matched spatial proteomic data by our group revealed a negative association between TIGIT and the checkpoint proteins PD-1 and LAG3.ConclusionOur findings support careful evaluation of TIGIT expression on T cells in primary or metastatic RCC specimens for patients who may be treated with TIGIT-targeting antibodies, as increased TIGIT positivity might be associated with a greater likelihood of response to therapy.

Comparison of Nivolumab with Docetaxel in the Treatment of Advanced Squamous Cell Non-small Cell Lung Cancer

Lung squamous-cell carcinoma poses a significant global health challenge with limited treatment options available. Immune checkpoint inhibitors, particularly nivolumab, have revolutionized cancer therapy, especially in non-small cell lung cancer (NSCLC). Nivolumab, targeting the PD-1 protein, exhibits promise in treating advanced squamous-cell NSCLC. This article critically examines nivolumab’s development and compares its efficacy with docetaxel in this context. Nivolumab’s effectiveness lies in its ability to block the PD-1/PD-L1 immune checkpoint pathway, reinvigorating the immune response against cancer cells. Clinical trials reveal higher overall survival rates and fewer adverse events (AEs) with nivolumab compared to docetaxel, alongside improvements in patient-reported outcomes and mental well-being. However, limitations exist, primarily stemming from clinical trial data’s potential mismatch with real-world scenarios. Short trial durations hinder long-term outcome analysis and delay AE evaluations. Furthermore, the comparison is restricted to nivolumab and docetaxel, overlooking other Food and Drug Administration-approved monoclonal antibodies. Addressing these limitations are crucial for enhancing the utility of these evaluations in clinical decision-making and guiding future research in advanced squamous-cell NSCLC management. Nivolumab emerges as a promising treatment option, offering superior efficacy and safety over traditional chemotherapy, yet its real-world efficacy warrants further exploration.

Type I Interferon Activates PD-1 Expression through Activation of the STAT1-IRF2 Pathway in Myeloid Cells.

PD-1 (Programmed cell death protein 1) regulates the metabolic reprogramming of myeloid-derived suppressor cells and myeloid cell differentiation, as well as the type I interferon (IFN-I) signaling pathway in myeloid cells in the tumor microenvironment. PD-1, therefore, is a key inhibitory receptor in myeloid cells. However, the regulation of PD-1 expression in myeloid cells is unknown. We report that the expression level of PDCD1, the gene that encodes the PD-1 protein, is positively correlated with the levels of IFNB1 and IFNAR1 in myeloid cells in human colorectal cancer. Treatment of mouse myeloid cell lines with recombinant IFNβ protein elevated PD-1 expression in myeloid cells in vitro. Knocking out IFNAR1, the gene that encodes the IFN-I-specific receptor, diminished the inductive effect of IFNβ on PD-1 expression in myeloid cells in vitro. Treatment of tumor-bearing mice with a lipid nanoparticle-encapsulated IFNβ-encoding plasmid (IFNBCOL01) increased IFNβ expression, resulting in elevated PD-1 expression in tumor-infiltrating myeloid cells. At the molecular level, we determined that IFNβ activates STAT1 (signal transducer and activator of transcription 1) and IRFs (interferon regulatory factors) in myeloid cells. Analysis of the cd279 promoter identified IRF2-binding consensus sequence elements. ChIP (chromatin immunoprecipitation) analysis determined that the pSTAT1 directly binds to the irf2 promoter and that IRF2 directly binds to the cd279 promoter in myeloid cells in vitro and in vivo. In colon cancer patients, the expression levels of STAT1, IRF2 and PDCD1 are positively correlated in tumor-infiltrating myeloid cells. Our findings determine that IFNβ activates PD-1 expression at least in part by an autocrine mechanism via the stimulation of the pSTAT1-IRF2 axis in myeloid cells.

Targeted protein editing technique in living mammalian cells by peptide-fused PNGase

Various precise gene editing techniques at the DNA/RNA level, driven by clustered regularly interspaced short palindrome repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) technology, have gained significant prominence. Yet, research on targeted protein editing techniques remains limited. Only a few attempts have been made, including the use of specific proteases and de-O-glycosylating enzymes as editing enzymes. Here, we propose direct editing of N-glycosylated proteins using de-N-glycosylating enzymes to modify N-glycosylation and simultaneously alter the relevant asparagine residue to aspartate in living cells. Selective protein deglycosylation editors were developed by fusing high-affinity protein-targeting peptides with active peptide:N-glycanases (PNGases). Three crucial cell membrane proteins, PD-1, PD-L1, and severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) spike protein, were chosen to be tested as a proof of concept. N-linked glycans were removed, and the relevant sites were converted from Asn to Asp in living mammalian cells, destabilizing target proteins and accelerating their degradation. Further investigation focused on SARS-CoV-2 spike protein deglycosylation editing. The collaboration of LCB1-PNGase F (PNGF) effectively reduced syncytia formation, inhibited pseudovirus packaging, and significantly hindered virus entry into host cells, which provides insights for coronavirus disease 2019 (COVID-19) treatment. This tool enables editing protein sequences post-de-N-glycosylation in living human cells, shedding light on protein N-glycosylation functions, and Asn to Asp editing in organisms. It also offers the potential for developing protein degradation technologies.

SCARB2 associates with tumor-infiltrating neutrophils and predicts poor prognosis in breast cancer.

The tumor microenvironment (TME) plays a crucial role in various aspects of breast cancer development and metastasis. Nevertheless, the expression, prognostic significance, and correlation with clinical features of SCARB2 in breast cancer, as well as the infiltrative characteristics of TME, remain largely unknown. We analyzed the differential presentation of SCARB2 mRNA in breast cancer tissues and nontumorous breast tissues and prognosis by The Cancer Genome Atlas (TCGA) and the Genotype-Tissue Expression (GTEx) databases. Additionally, the Tumor Immunity Estimation Resource (TIMER) was taken to evaluate the correlation between SCARB2 mRNA presence and tumor-infiltrating immune cells and immune checkpoints in the TME in breast cancer. We performed multiple immunohistochemical staining to verify the SCARB2 protein expression in breast cancer tissues and its relationship to immune cells and checkpoints and clinicopathological features. We identified elevated SCARB2 expression in breast cancer tissues, and high SCARB2 protein presentation was associated with advanced clinical stage and unfavorable prognosis. In addition, enhanced SCARB2 protein presence was closely correlated with up-regulation CD66b+ neutrophils infiltration in tumor tissues (r = 0.210, P < 0.05) and CD68 + CD163+ M2 macrophages in the interstitium (r = 0.233, P < 0.05), as well as the immune checkpoints, including PD-1 (r = 0.314, P < 0.01) protein expression. SCARB2 holds promise for predicting the clinical outcome of breast cancer patients and could serve as a potential therapeutic target.

Dose escalation of KY-0118, PD-1, and IL-2v due-target fusion protein in patients with advanced renal clear cell carcinoma, urothelial carcinoma, and malignant melanoma.

e14505 Background: KY-0118 is an anti-PD1 and IL-2v(variant) fusion protein for advanced solid tumors. The non-α biased design reduces the binding to IL2-Raβγ and enhanced binding to PD-1 &amp; IL2-Rβγ positive TILs to drive increased proliferation and activation of NK and CD8+ T cells without unwanted expansion of Tregs. KY-0118 adopts specific single design, only 67kDa MW thus obtains excellent tumor penetration activity. The preclinical data shows higher antitumor activity in several CDX models compared with nivolumab and IL2wt. KY-0118 monotherapy is currently in Phase I escalation. Methods: The phase I dose escalation is a traditional 3+3 design, KY-0118 on Days 1, 8 and 15, 21-day treatment cycle, 9 dose levels (0.3μg/kg-64μg/kg) or higher doses of 3 to 6 patients are planned. The dose expansion cohort is currently enrolling. The primary endpoint was to evaluate the safety, tolerability, and determine the DLT, MTD, RP2D of KY 0118 when given alone. Secondary objectives are PK/PD characteristics and preliminary evidence of efficacy via ORR per RECIST v1.1 and iRECIST. Results: Up to Jan 31, 2024, 21 patients have been treated, the median number of prior lines of systemic therapy was 2. The dose level 8 (48µg/kg) of DLT observation period is ongoing, no DLT was observed in the administered dose groups. Most of TEAEs are transient grade 1-2, no TEAE led to withdrawal from this study. The most common nonhematologic TRAEs were pyrexia, flu-like symptoms, nausea, fatigue. 2 patients had grade 3 hematologic toxicity. Treatment-related sAEs were observed in one patient (include nausea, vomiting, and pulmonary embolism, now recovered and continuing treatment). No patients experienced complete or partial response, but several showed evidence of antitumor activity, at the dose of 36 ug/kg, 21% shrinkage of target lesions in a patient with RCC, the DCR for the 12, 24, and 36μg/kg dose levels are 33%, 75%, and 67%, respectively. Conclusions: These preliminary data suggest that KY-0118 demonstrated a manageable safety profile and encouraging early evidence of activity has been observed in locally advanced and/or metastatic solid tumors. Enrollment is ongoing, further results are forthcoming. Pts: 21; AEs: 399; TEAEs: 289 (100%); AESI: 13; sAEs: 8. Clinical trial information: NCT06175780 .

Programmed Cell Death Protein-1 Regulation in Response to SARS-CoV-2 in Paediatric Multisystem Inflammatory Syndrome Temporally Associated with SARS-CoV-2: A Prospective Cohort Study.

The role of programmed death cell protein 1 (PD-1) has already been described in a range of various diseases, including COVID-19. This study provides new, innovative data, related to the expression of PD-1 and the risk of Paediatric Inflammatory Multisystem Syndrome, temporally associated with SARS-CoV-2 infection (PIMS-TS)-a rare, but potentially life-threatening complication of COVID-19. In this study, we evaluated the expression of PD-1 protein in patients with PIMS. Blood samples were taken from patients at the time of diagnosis (n = 33), after 6 weeks (n = 33), 3 months (n = 24), 6 months (n = 24) and 12 months (n = 8). The immunophenotypes were evaluated in flow cytometry. The control group consisted of 35 healthy children with negative SARS-CoV-2 antigen/PCR test, who were asymptomatic and had no history of allergic, autoimmune or oncological diseases. The associations between immunophenotypes, biochemical findings and clinical data were analysed. Significant increases in the expression of PD-1 for CD4+ and CD8+ T cells, compared to the control group, were observed in the day of admission, with a gradual decrease during the first weeks from initiation of treatment. This study sheds new light on the pathogenesis of PIMS-TS, emphasizing the role of PD-1 protein. Future research is essential for early risk prediction in SARS-CoV-2 patients and for devising effective clinical prevention and management strategies.

Surface PD-1 expression in T cells is suppressed by HNRNPK through an exonic splicing silencer on exon 3.

Immunotherapy targeting programmed cell death 1 (PDCD1 or PD-1) and its ligands has shown remarkable promise and the regulation mechanism of PD-1 expression has received arising attention in recent years. PDCD1 exon 3 encodes the transmembrane domain and the deletion of exon 3 produces a soluble protein isoform of PD-1 (sPD-1), which can enhance immune response by competing with full-length PD-1 protein (flPD-1 or surface PD-1) on T cell surface. However, the mechanism of PDCD1 exon 3 skipping is unclear. The online SpliceAid program and minigene expression system were used to analyze potential splicing factors involved in the splicing event of PDCD1 exon 3. The potential binding motifs of heterogeneous nuclear ribonucleoprotein K (HNRNPK) on exon 3 predicted by SpliceAid were mutated by site-directed mutagenesis technology, which were further verified by pulldown assay. Antisense oligonucleotides (ASOs) targeting the exonic splicing silencer (ESS) on PDCD1 exon 3 were synthesized and screened to suppress the skipping of exon 3. The alternative splicing of PDCD1 exon 3 was analyzed by semiquantitative reverse transcription PCR. Western blot and flow cytometry were performed to detect the surface PD-1 expression in T cells. HNRNPK was screened as a key splicing factor that promoted PDCD1 exon 3 skipping, causing a decrease in flPD-1 expression on T cell membrane and an increase in sPD-1 expression. Mechanically, a key ESS has been identified on exon 3 and can be bound by HNRNPK protein to promote exon 3 skipping. Blocking the interaction between ESS and HNRNPK with an ASO significantly reduced exon 3 skipping. Importantly, HNRNPK can promote exon 3 skipping of mouse Pdcd1 gene as well. Our study revealed a novel evolutionarily conserved regulatory mechanism of PD-1 expression. The splicing factor HNRNPK markedly promoted PDCD1 exon 3 skipping by binding to the ESS on PDCD1 exon 3, resulting in decreased expression of flPD-1 and increased expression of sPD-1 in T cells.

Immune checkpoint markers and tumour mutation burden in Wilms tumour: a study of 59 cases

Wilms tumour (WT) is the most common renal tumour in children, and studies of immune checkpoint inhibitors (ICIs) treatment and markers are limited in number. In this study we investigated the ICIs' related immune landscape by examining the expression of PD-L1, PD-1, CD8 and DNA mismatch repair (MMR) proteins by immunohistochemistry (IHC), tumour mutation burden (TMB), and correlations with histology and clinical outcome. Positive PD-L1 (SP263) expression was defined as modified combined positive score (CPS) ≥1. A total of 59 WTs (from 2000 to 2017), including eight (14.0%) with anaplasia, from 46 patients were analysed (45 primary and 14 metastatic). Thirteen WTs (13/59, 22%) were positive for PD-L1 (8 primary, 5 metastatic; CPS 1.11-3.42). Positive PD-L1 expression was associated with diffuse anaplasia (p<0.05) and significantly shorter progression-free survival (p<0.05) among WTs with favourable histology (n=39). CD8+ lymphocytes were present in all analysed WTs. A subset of CD8+ cells co-expressed PD-1, which was associated with favourable histology and treatment. MMR IHC stains identified two (2/18, 11%) WTs with isolated PMS2 loss. All six WTs analysed for TMB showed low mutation burden. We found CD8+ lymphocytes in all analysed WTs and identified a fraction of WT (17.8% of primary and 35.8% of metastatic) with positive PD-L1 CPS, suggesting potential response to ICIs in some patients.

Serum Concentrations of TIM-3, LAG-3, and PD-1 in Patients with Hemorrhagic Fever with Renal Syndrome.

Hemorrhagic fever with renal syndrome (HFRS) is a rodent-borne disease widespread in Europe and Asia. HFRS is caused by negative-sensed single-stranded RNA orthohantaviruses transmitted to humans through inhaling aerosolized excreta of infected rodents. Symptoms of HFRS include acute kidney injury, thrombocytopenia, hemorrhages, and hypotension. The immune response raised against viral antigens plays an important role in the pathogenesis of HFRS. Inhibitory co-receptors are essential in regulating immune responses, mitigating immunopathogenesis, and reducing tissue damage. Our research showed an increased soluble form of inhibitory co-receptors TIM-3, LAG-3, and PD-1 in HFRS patients associated with disease severity. Our study aimed to investigate the impact of HFRS on the concentrations of soluble forms of inhibitory receptors TIM-3, LAG-3, and PD-1 in the patient's serum and the potential correlation with key clinical parameters. Our study aimed to investigate the impact of HFRS on the concentrations of soluble forms of inhibitory receptors TIM-3, LAG-3, and PD-1 in the patient's serum and their possible association with relevant clinical parameters. Using multiplex immunoassay, we found elevated levels of TIM-3, LAG-3, and PD-1 proteins in the serum of HFRS patients. Furthermore, increased levels were associated with creatinine, urea, lactate dehydrogenase concentrations, and platelet count. These findings suggest that these proteins play a role in regulating the immune response and disease progression.

Correlation between PD-1/PD-L1 and RANKL/OPG in chronic apical periodontitis model of Sprague-Dawley rats.

Chronic apical periodontitis (CAP) is characterized by inflammation and destruction of the apical periodontium that is of pulpal origin, appearing as an apical radiolucent area, and does not produce clinical symptoms. Little is known about whether the PD-1/PD-L1 ratio is associated with the balance between RANKL and OPG in CAP. The relationship between PD-1/PD-L1 and RANKL/OPG in CAP is investigated in this study. A CAP rat model was established using Sprague-Dawley rats. The pulp chambers were exposed to the oral cavity to allow bacterial contamination. The apical tissues of the bilateral mandibular first molars were analyzed for histological morphology using hematoxylin and eosin (H&E) staining. Immunohistochemistry and qRT-PCR were used to determine the expression of PD-1, PD-L1, OPG, and RANKL mRNA and proteins in periapical tissues and mandibular samples, respectively. The radiological images indicated a poorly defined low-density shadow and alveolar bone resorption after periodontitis induction. Histological analysis revealed an infiltration of inflammatory cells and alveolar bone resorption in the periapical tissues. Mandibular mRNA and periapical protein expression of PD-1, PD-L1, and RANKL was upregulated 7-28days after periodontitis induction, while the expression of OPG was downregulated. No significant relationship was observed between PD-1/PD-L1 and RANKL/OPG at either mRNA or protein levels in CAP. There is an increased expression of PD-1, PD-L1, and RANKL and a decreased expression of OPG, indicating progression of CAP.

Abstract 74: Exploring the expression of cancer-intrinsic PD1 in osteosarcoma cells: A comprehensive proteomic analysis of its functional landscape

Abstract Cancer treatment was revolutionized by immune checkpoint inhibitors (ICIs) targeting the PD1/PDL1 axis - a brake to the immune system. Despite remarkable success, some patients do not respond to therapy or rapidly deteriorate due to an unclear mechanism. As reported for several types of tumors, PD1 receptor is not solely expressed on immune cells but also on cancer cells. Depending on the tumor type, it may act either as a suppressor or a tumor promoter. The limited response to ICIs was also reported in osteosarcoma (OSA), the most common type of bone cancer, mostly affecting children and young adults. With no significant improvement in therapy over the past 30 years, there is an urgent need for therapeutic advancement. This study aimed to determine if PD1 protein is expressed in OSA and whether it has a functional role, potentially affecting the response to ICIs. Strikingly, our results revealed both surface and intracellular PD1 expression in U2OS osteosarcoma cells, confirmed by Western Blot, flow cytometry and immunofluorescence analyses. siRNA-mediated PDCD1 gene silencing significantly increased cell migration and viability in scratch and viability assays. LC-MS-based global proteomics showed that PDCD1 knockdown markedly affects U2OS cells’ proteomic landscape compared to the control. To dissect PD1 receptor downstream signaling effects, we subjected the identified proteins to GO and GSEA large-scale data interpretation tools. The results strongly suggested that PDCD1 silencing leads to the enrichment of proteins involved in cell growth, migration and motility, corresponding to the cellular effects we initially observed. Importantly, the analysis clearly indicated positive regulation of MAPK cascade in cells with perturbed PD1 expression, aligning with PD1 mediated MAPK regulation in T cells. To reveal the mechanism underlying PD1 signaling, we focused on proteins with significantly changed expression in response to the knockdown. Using the STRING database, we created their interacting network, revealing that numerous proteins are closely related, and the majority of them are phosphoproteins, indicating significance in cellular signaling. Remarkably, many of the STRING-analyzed proteins belong to intersecting pathways, such as AKT1S1 and LAMTOR proteins, the critical components for mTORC1 signaling, or selected members of the Src family kinases along with their negative regulator CSK. In summary, we report previously undiscovered functional expression of PD1 in OSA cells, providing insights into the landscape of PD1 downstream signaling. Our studies indicate the role of PD1 in regulating cell growth, proliferation, and motility, suggesting osteosarcoma-expressed PD1 as a tumor suppressor. Further studies are urgently needed to investigate its therapeutic significance and explore if we could make ICIs more effective to treat osteosarcoma. Citation Format: Katarzyna Joanna Dziubek, Jakub Faktor, Ted Hupp, Maciej Parys, Sachin Kote. Exploring the expression of cancer-intrinsic PD1 in osteosarcoma cells: A comprehensive proteomic analysis of its functional landscape [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 74.

Abstract 1372: BTN1A1 regulates T cell-mediated cancer immunotherapy by interacting with Galectin-9, PD-1, and TIM3

Abstract Butyrophilin 1A1 (BTN1A1) is a novel immune checkpoint protein belonging to the butyrophilin family and is expressed on immune cells such as macrophages, B cells, or activated CD8 T cells and in human tumors. Our results indicate that BTN1A1 and PD-L1 expression are mutually exclusive in various human solid tumors. Furthermore, it was observed that BTN1A1 had a significantly higher detection level than PD-L1 in cancer patient samples. We have reported that BTN1A1 plays an immunomodulatory role in T cell activation and proliferation. BTN1A1 inhibited the proliferation of T cells that are activated by anti-CD3 and anti-CD28 antibodies in vitro. Overexpression of BTN1A1 in PC3 cells also inhibits T cell-mediated killing of cancer cells. BTN1A1 is a bona fide immune checkpoint inhibitor and has anti-tumor activity in a human immune setting. BTN1A1 represents a novel cancer immunotherapy target that goes beyond the low expression levels of PD-1/PD-L1 in tumors. BNT1A1 is an immune checkpoint and cell membrane protein that, together with its binding partners, serves as a starting point for signaling pathways. The BNT1A1 complex, which has various abilities by combining with a specific partner, plays a vital role as an immune checkpoint. In this study, we identified binding partners of BTN1A that regulate immune activity in a mutually interaction relationship with BTN1A1 in various ways. We identified binding partners for the extracellular domain of human BTN1A1 using cell microarrays from Retrogenix (Whaley Bridge, UK). Through this screening approach, we found that BTN1A1 binds to galectin-1 (Gal1), galectin-9 (Gal9), and neuropilin 2 (NRP2). These three putative binding partners could specifically bind to wild-type BTN1A1 but not to this protein's unglycosylated (2NQ) form. Of these three targets, immunoprecipitation and Biacore binding assays revealed that Gal9 exhibited the greatest affinity for human BTN1A1. Since Gal9 is a known PD-1 and TIM3 binding protein, we predicted the potential formation of a BTN1A1/Gal9/PD-1 or BTN1A1/Gal9/TIM3 complex. Indeed, it reveals that immunoprecipitation and confocal microscopy assays performed using cells expressing Myc-tagged versions of these four proteins demonstrated the formation of BTN1A1/Gal9, PD-1/Gal9, TIM3/Gal9, BTN1A1/Gal9/TIM3, and BTN1A1/Gal9/PD-1 complexes. In T cell activation assay using these complexes, when present BTN1A1 alongside the complex inhibits activated T cells. As high Gal9 expression levels are correlated with poor prognosis in multiple cancers, our results highlight this BTN1A1-Gal9-PD-1 or BTN1A1-Gal9-TIM3 axis as a novel therapeutic target for immunotherapeutic drug development. Citation Format: Seung Hoon Lee, Young-Seung Kim, Chunai Wu, Andrew H Park, Stephen S. Yoo. BTN1A1 regulates T cell-mediated cancer immunotherapy by interacting with Galectin-9, PD-1, and TIM3 [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 1372.

Abstract 1582: Cabozantinib changes the tumor microenvironment to increase the efficacy of immunotherapy in refractory metastatic pancreatic ductal adenocarcinoma

Abstract Background: Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal malignancies. Tumors evade immune surveillance by expressing PD-L1 that interacts with the T cell protein PD-1, subsequently inhibiting CD8+ cytotoxic T lymphocyte proliferation and effector function. A plausible reason for this observation may be that other, redundant, immune suppressive mechanisms are at play. Our research team has shown that elevated infiltration of polymorphonuclear (PMN)-MDSCs within the PDAC tumor microenvironment (TME) inhibit T cell effector function, regardless of PD-1/PD-L1 inhibition (Holokai et al., 2020). Objective: A Phase II clinical trial was developed to identify the potential therapeutic benefit of combinatorial anit-PD-L1/PD-1 and cabozantinib (cabo) treatment in therapy-resistant (refractory and metastatic) PDAC patients. Methods: NanoString CosMx™ spatial molecular transcriptomic imaging (CosMx™ SMI) was performed using FFPE sections collected from a liver or lung metastatic target lesions at visit 1 (pretreatment) and visit 2 (9 weeks on combinatorial treatment) from individual patients. FFPE sections were prepared from the same target lesion, and fields of view were chosen on the H&amp;E in consultation with GI pathologist. Seurat V 4.0 was used for the analysis and visualization by spatial mapping of each FOV showing identified cell population indicated by color coding in visit 1 and visit 2 within the same patient. Multiplex immunofluorescence (MxIF) of patient FFPE tissues and single cell RNA sequencing (scRNAseq) of PDAC organoids (PDOs) generated from the core biopsies collected at visit 1 and matched visit 2 from each patient were used to validate the CosMx™ SMI data. Results: A uniform manifold approximation and projection showed loss of tumor cell populations within the PDAC TME in response to combinatorial treatment compared to pretreatment visit 1. Comparison between spatial maps of visit 1 to visit 2 demonstrated a shift in cell populations within defined NICHES (local cellular TME) whereby there was 1) a loss of tumor cell populations, 2) increase in CTL infiltration, 3) increase in endothelial cells, 4) decrease immunosuppressive MDSCs, 5) decrease in antigen presenting CAFs, and 6) change in myCAFs to an inflammatory CAF phenotype. Within the iCAF population IL-6, CXCL1, LIFR, ACTA2 and FAK were expressed; correlating with an increase in CD8 perforin and granzyme B positive cells in response to cabo and checkpoint inhibition. MxIF, spectral flow cytometry and scRNAseq analyses of the matched in vitro PDO model showed tumor cell death that correlated with decreased MDSC viability, increased CTL proliferation and a shift in CAF phenotypes. Conclusion: These findings suggest that cabo induces a TME conducive to increased response to immunotherapy in PDAC patients with refractory metastatic disease. Citation Format: Jayati Chakrabarti, Pritha Adhikary, Jiang Wang, Davendra Sohal, Syed A. Ahmad, Junaid Arshad, Aaron J. Scott, Rachna T. Shroff, Yana Zavros. Cabozantinib changes the tumor microenvironment to increase the efficacy of immunotherapy in refractory metastatic pancreatic ductal adenocarcinoma [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 1582.

Biomimetic Responsive Nanoconverters with Immune Checkpoint Blockade Plus Antiangiogenesis for Advanced Hepatocellular Carcinoma Treatment.

The first-line treatment for advanced hepatocellular carcinoma (HCC) combines immune checkpoint inhibitors and antiangiogenesis agents to prolong patient survival. Nonetheless, this approach has several limitations, including stringent inclusion criteria and suboptimal response rates that stem from the severe off-tumor side effects and the unfavorable pharmacodynamics and pharmacokinetics of different drugs delivered systemically. Herein, we propose a single-agent smart nanomedicine-based approach that mimics the therapeutic schedule in a targeted and biocompatible manner to elicit robust antitumor immunity in advanced HCC. Our strategy employed pH-responsive carriers, poly(ethylene glycol)-poly(β-amino esters) amphiphilic block copolymer (PEG-PAEs), for delivering apatinib (an angiogenesis inhibitor), that were surface-coated with plasma membrane derived from engineered cells overexpressing PD-1 proteins (an immune checkpoint inhibitor to block PD-L1). In an advanced HCC mouse model with metastasis, these biomimetic responsive nanoconverters induced significant tumor regression (5/9), liver function recovery, and complete suppression of lung metastasis. Examination of the tumor microenvironment revealed an increased infiltration of immune effector cells (CD8+ and CD4+ T cells) and reduced immunosuppressive cells (myeloid-derived suppressor cells and T regulatory cells) in treated tumors. Importantly, our nanomedicine selectively accumulated in both small and large HCC occupying >50% of the liver volume to exert therapeutic effects with minimal systemic side effects. Overall, these findings highlight the potential of such multifunctional nanoconverters to effectively reshape the tumor microenvironment for advanced HCC treatment.