Development Of Cancer Immunotherapy Research Articles

Organelle-based immunotherapy strategies for fighting against cancer.

Destruction of subcellular organelles can cause dysfunction and even death of cells to elicit immune responses. In this review, the characteristics and functions of important organelles are mainly summarized. Then, the intelligent immunotherapeutic strategies and suggestions based on influencing the organelles are further highlighted. This review will provide ideas for developing novel and effective immunotherapy strategies and advance the development of cancer immunotherapy.

Eosinophil-Activating Semiconducting Polymer Nanoparticles for Cancer Photo-Immunotherapy.

Eosinophils are important immune effector cells that affect T cell-mediated antitumor immunity. However, the low frequency and restrained activity of eosinophils restricted the outcome of cancer immunotherapies. We herein report an eosinophil-activating semiconducting polymer nanoparticle (SPNe) to improve photodynamic tumor immunogenicity, modulate eosinophil chemotaxis, and reinvigorate T-cell immunity for activated cancer photo-immunotherapy. SPNe comprises an amphiphilic semiconducting polymer and a dipeptidyl peptidase 4 (DPP4) inhibitor sitagliptin via a 1O2-cleavable thioketal linker. Upon localized NIR photoirradiation, SPNe generates 1O2 to elicit immunogenic cell death of tumors and induce specific activation of sitagliptin. The subsequent inhibition of DPP4 increases intratumoral CCL11 levels to promote eosinophil chemotaxis and activation. SPNe-mediated photo-immunotherapy synergized with immune checkpoint blockade greatly promotes tumor infiltration and activation of both eosinophils and T cells, effectively inhibiting tumor growth and metastasis. Thus, this study presents a generic polymeric nanoplatform to modulate specific immune cells for precision cancer immunotherapy.

Discovery of highly potent PARP7 inhibitors for cancer immunotherapy

PARP7 has been proven to play an important role in immunity. Substantial upregulation of PARP7 is observed in numerous cancerous cell types, consequently resulting in the inhibition of type Ⅰ interferon signaling pathways. Therefore, inhibiting the activity of PARP7 can enhance type Ⅰ interferon signaling to exert an anti-tumor immune response. In this study, we reported the identification of a newly found PARP7 inhibitor (XLY-1) with higher inhibitory activity (IC50 = 0.6 nM) than that of RBN-2397 (IC50 = 6.0 nM). Additionally, XYL-1 displayed weak inhibitory activity on PARP1 (IC50 > 1.0 μM). Mechanism studies showed that XYL-1 could enhance the type Ⅰ interferon signaling in vitro. Pharmacodynamic experiments showed that 50 mg/kg XYL-1 could significantly inhibit tumor growth (TGI: 76.5 %) and related experiments showed that XYL-1 could restore type Ⅰ interferon signaling and promote T cell infiltration in tumor tissues. Taken together, XYL-1 shows promise as a potential candidate for developing cancer immunotherapy agents.

Emerging Innate Immune Cells in Cancer Immunotherapy: Promises and Challenges.

Immune checkpoint inhibitor (ICI)-based therapy has made an unprecedented impact on survival benefit for a subset of cancer patients; however, only a subset of cancer patients is benefiting from ICI therapy if all cancer types are considered. With the advanced understanding of interactions of immune effector cell types and tumors, cell-based therapies are emerging as alternatives to patients who could not benefit from ICI therapy. Pioneering work of chimeric antigen receptor T (CAR-T) therapy for hematological malignancies has brought encouragement to a broad range of development for cellular-based cancer immunotherapy, both innate immune cell-based therapies and T-cell-based therapies. Innate immune cells are important cell types due to their rapid response, versatile function, superior safety profiles being demonstrated in early clinical development, and being able to utilize multiple allogeneic cell sources. Efforts on engineering innate immune cells and exploring their therapeutic potential are rapidly emerging. Some of the therapies, such as CD19 CAR natural killer (CAR-NK) cell-based therapy, have demonstrated comparable early efficacy with CD19 CAR-T cells. These studies underscore the significance of developing innate immune cells for cancer therapy. In this review, we focus on the current development of emerging NK cells, γδ T cells, and macrophages. We also present our views on potential challenges and perspectives to overcome these challenges.

PET Imaging for Monitoring Cellular and Immunotherapy of Cancer.

Cancer immunotherapy, including checkpoint blockade and cellular therapy, has become a cornerstone in cancer treatment. However, understanding the factors driving patient response or resistance to these therapies remains challenging. The dynamic interplay between the immune system and tumors requires new approaches for characterization. Biopsies and blood tests provide valuable information, but their limitations have led to increased interest in positron emission tomography (PET)/computed tomography imaging to complement these strategies. The noninvasive nature of PET imaging makes it ideal for monitoring the dynamic tumor immune microenvironment. This review discusses various PET imaging approaches, including immune cell lineage markers, immune functional markers, immune cell metabolism, direct cell labeling, and reporter genes, highlighting their potential in targeted immunotherapies and cell-based approaches. Although PET imaging has limitations, its integration into diagnostic strategies holds promise for improving patient outcomes and accelerating drug development in cancer immunotherapy.

VitTCR: A deep learning method for peptide recognition prediction

This study introduces VitTCR, a predictive model based on the vision transformer (ViT) architecture, aimed at identifying interactions between Tcell receptors (TCRs) and peptides, crucial for developing cancer immunotherapies and vaccines. VitTCR converts TCR-peptide interactions into numerical AtchleyMaps using Atchley factors for prediction, achieving AUROC (0.6485) and AUPR (0.6295) values. Benchmark analysis indicates VitTCR's performance is comparable to other models, with further comparative studies suggested to understand its effectiveness in varied contexts. Additionally, integrating a positional bias weight matrix (PBWM), derived from amino acid contact probabilities in structurally resolved pMHC-TCR complexes, slightly improves VitTCR's accuracy. The model's predictions show weak yet statistically significant correlations with immunological factors like Tcell clonal expansion and activation percentages, underscoring the biological relevance of VitTCR's predictive capabilities. VitTCR emerges as a valuable computational tool for predicting TCR-peptide interactions, offering insights for immunotherapy and vaccine development.

Efficacy of LCMV-based cancer immunotherapies is unleashed by intratumoral injections of polyI:C

BackgroundLymphocytic choriomeningitis virus (LCMV) belongs to the Arenavirus family known for inducing strong cytotoxic T-cell responses in both mice and humans. LCMV has been engineered for the development of cancer...

Tetracyclines enhance antitumor T-cell immunity via the Zap70 signaling pathway

BackgroundCancer immunotherapy including immune checkpoint inhibitors is only effective for a limited population of patients with cancer. Therefore, the development of novel cancer immunotherapy is anticipated. In preliminary studies, we...

Integrative analysis revealed a correlation of PIAS family genes expression with prognosis, immunomodulation and chemotherapy

BackgroundProtein inhibitor of activated STATs (PIAS) has pleiotropic biological effects, such as protein post-translational modification, transcriptional coregulation and gene editing. It is reported that PIAS family genes are also correlated with immune cells infiltration in cancers that highlights their unnoticed biological role in tumor progression. However, the relationship of their expression with prognosis, immune cell infiltration, tumor microenvironment, and immunotherapy in pan-cancer has been rarely reported.MethodsThe multi-omics data were used to investigate the expression level of PIAS family members in pan-cancer, and the prognostic value of their expression in different tumors was analyzed by univariate Cox regression and Kaplan–Meier. Correlation analysis was used to investigate the relationship of PIAS gene expression with tumor microenvironment, immune infiltrating subtypes, stemness score and drug sensitivity. In addition, we also used wound healing and transwell assays to verify the biological effects of PIAS family gene expression on invasion and metastasis of HCC cells.ResultsWe found that PIAS family genes expression is significantly heterogeneous in tumors by multi-genomic analysis, and associated with poor prognosis in patients with multiple types of cancer. Furthermore, we also found that genetic alterations of PIAS family genes were not only common in different types of human tumors, but were also significantly associated with disease-free survival (DFS) across pan-cancer. Single-cell analysis revealed that PIAS family genes were mainly distributed in monocytes/macrophages. Additionally, we also found that their expression was associated with tumor microenvironment (including stromal cells and immune cells) and stemness score (DNAss and RNAss). Drug sensitivity analysis showed that PIAS family genes were able to predict the response to chemotherapy and immunotherapy. PIAS family genes expression is closely related to tumor metastasis, especially PIAS3. High PIAS3 expression significantly promotes the migration and invasion of liver cancer cell lines (HCC-LM3 and MHCC97-H).ConclusionsTaking together, these findings contribute to determine whether the PIAS family genes are a potential oncogenic target gene, which have important contribution for the development of cancer immunotherapy.

Abstract 2082: Identification of nonsense-mediated decay inhibitors that alter the tumor immune landscape

Abstract Despite exciting developments in cancer immunotherapy, its broad application is limited by the paucity of targetable antigens on the tumor cell surface. As an intrinsic cellular pathway, nonsense-mediated decay (NMD) conceals neoantigens through the destruction of the RNA products from genes harboring truncating mutations. We developed and conducted a high throughput screen, based on the ratiometric analysis of transcripts, to identify critical mediators of NMD. This screen revealed disruption of kinase SMG1’s phosphorylation of UPF1 as a potent disruptor of NMD. This led us to design a novel SMG1 inhibitor, KVS0001, that elevates the expression of transcripts and proteins resulting from truncating mutations in vivo and in vitro. Most importantly, KVS0001 concomitantly increased the presentation of immune-targetable HLA class I-associated peptides from NMD-downregulated proteins on the surface of cancer cells. KVS0001 provides new opportunities for studying NMD and the diseases in which NMD plays a role, including cancer and inherited diseases. Citation Format: Ashley L. Cook, ojit Sur, Laura Dobbyn, Evangeline Watson, Joshua D. Cohen, Blair Ptak, Bum Seok Lee, Suman Paul, Emily Hsiue, Maria Popoli, Bert Vogelstein, Nickolas Papadopoulos, Chetan Bettegowda, Kathy Gabrielson, Shibin Zhou, Kenneth Kinzler, Nicolas Wyhs. Identification of nonsense-mediated decay inhibitors that alter the tumor immune 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 2082.

Abstract 4256: Autologous organoids and T cell co-cultures as a powerful personalized platform for immunotherapy development

Abstract Recent advances in cancer immunotherapy have had a positive impact on the life expectancy of patients for an extensive range of clinical indications. With new treatment strategies and druggable targets being identified at an increasing pace, the number of patients eligible for cancer immunotherapy is expected to expand steadily. However, promising therapeutic developments face hurdles in translating preclinical findings into therapy since conventional 2D cancer models hold low clinical predictive value. We developed an innovative alternative, building on the discovery that adult stem cells proliferate and organize into three-dimensional organotypic structures when they are embedded into extracellular matrix. Patient-derived organoids are generated from normal and malignant tissues and stored as high-quality biobanks that yield highly reproducible results. HUB Organoids® recapitulate complex characteristics of the parental tissue, including molecular heterogeneity, as well as morphological and functional traits. Since cancer progression and response to immunotherapy are governed by immune cell interactions in the tumor microenvironment, we developed an assay in which colorectal (CRC) and non-small cell lung cancer (NSCLC) tumor organoids are co-cultured with paired tumor infiltrating lymphocytes (TIL) that are simultaneously expanded as a source of tumor reactive cells. Paired resources allow for the screening of immune-modulatory therapies under physiologic conditions, not depending on peptide-pulsing and alloreactivity. We quantify tumor organoid killing and TILs reactivity by combining imaging-based analysis of apoptotic cells with flow cytometry to measure cytokine release by cytotoxic TILs. Here, we show that our system is robust and reproducible with an establishment rate of 75%, allowing for expansion of TILs that preserve T cell receptor repertoires. First line expansion of both PDO and TIL components can be used to effectively build coculture models and probe the tumor and immune components, respectively. Our system offers a powerful tool for the development and validation of cancer immunotherapy and can help to stratify cancer patients for susceptibility to various types of immunotherapies. We certify that the research use of each of the HBS marked above was conducted according to the expectations of each institution. Citation Format: Claudia Beaurivage, BanuPriya Sridharan, Sumeyra Mucuk, Kimberly Nadwodny, Derek Poore, Anna Schepers, Farzin Pourfarzad, Sylvia F. Boj. Autologous organoids and T cell co-cultures as a powerful personalized platform for immunotherapy development [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 4256.

Abstract 7251: Surface-engineered extracellular vesicles to modulate antigen-specific T cell expansion for cancer immunotherapy

Abstract Tumor immunotherapy, including immune checkpoint therapy, CAR T cell therapy, and TCR-T cell therapy, has made significant progress in the treatment of cancer. Recently, newly developed nanomaterials have also been applied to anti-tumor immunotherapy. Among them, extracellular vesicles (EVs) have been well-engineered in recent years due to their low immunogenicity, high stability, and wide distribution in biological fluids. Despite the recent development of several EVs-based cancer immunotherapies, their clinical efficacy remains limited. In this study, we have developed engineered EVs designed to mimic the function of antigen-presenting cells, which can co-deliver multiple immune-activation signals to tumor-associated T cells. We named these vesicles Antigen-presenting Extracellular Vesicles (AP-EVs). AP-EVs express a high level of MHC I-peptide complexes, costimulatory molecules, and surface-bound cytokines, allowing for the simultaneous presentation of multiple immune modulators to antigen-specific CD8+ T cells. AP-EVs promote the clonal expansion and differentiation of antigen-specific cytotoxic T lymphocytes, resulting in potent anticancer immune responses. Notably, our findings indicate that combination therapy involving AP-EVs and anti-PD-1 yields superior anticancer immunity against established tumors compared to anti-PD-1 monotherapy. This synergistic effect underscores the potential of our engineered EVs as a novel and highly effective strategy for cancer immunotherapy. Citation Format: Xiabing Lyu, Tomoyoshi Yamano, Shota Imai, Toan Van Le, Rikinari Hanayama. Surface-engineered extracellular vesicles to modulate antigen-specific T cell expansion for cancer immunotherapy [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 7251.

Abstract 2831: Development and application of the NCG-hIL2 mouse model: A humanized platform for enhanced NK cell evaluation in ADCC efficacy testing

Abstract Natural Killer (NK) cells play a pivotal role in immune surveillance and antitumor responses, making them valuable targets in cancer immunotherapy. The assessment of therapeutic antibodies' efficacy, particularly in the context of Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC), necessitates models that faithfully recapitulate human NK cell responses. Here, we introduce the NCG-hIL2 mouse model, designed to address these requirements and advance our understanding of NK cell development. The NCG-hIL2 mouse model was engineered to express human Interleukin-2 (IL2) cytokine, a critical factor in NK cell development and activation. This humanized platform allows for the robust reconstitution of human NK cells through the transplantation of peripheral blood mononuclear cells (PBMCs) or hematopoietic stem cells (HSCs). In this study, we validate the NCG-hIL2 model's exceptional capability in supporting the reconstitution of human NK cells, highlighting the indispensable role of IL2 in NK cell development. Moreover, we demonstrate its utility in the evaluation of therapeutic antibodies, specifically Trastuzumab and the ADCC-enhanced Margetuximab, in the context of ADCC efficacy testing. Our findings reveal that the NCG-hIL2 model provides a unique advantage for assessing the impact of IL2 on NK cell development, thus facilitating a deeper understanding of the complex interplay between NK cells and therapeutic antibodies. The NCG-hIL2 mouse model serves as a valuable tool for studying NK cell development and evaluating the efficacy of immunotherapies, particularly in ADCC. By reconstituting human NK cells and leveraging the role of IL2, this model offers an enhanced platform for preclinical evaluation of therapeutic antibodies, ultimately advancing our ability to harness NK cell-mediated antitumor responses. It is poised to contribute significantly to the field of cancer immunotherapy and drug development. Citation Format: Yuan Fang, Hongyan Sun, Huiyi Wang, Jun Xing, Jialu Fan, Jing Zhao, Xiang Gao, Cunxiang Ju. Development and application of the NCG-hIL2 mouse model: A humanized platform for enhanced NK cell evaluation in ADCC efficacy testing [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 2831.

Abstract 1171: Estimating sensitivity of exploratory cellular biomarkers in oncology clinical trials

Abstract Background: In the prolonged and complex process of assessing immunotherapeutic oncology drug candidates, flow cytometry plays an essential role. In oncology studies, biomarker measurement requires robust and reliable flow cytometric assays. A crucial element of these assays is to understand the lower limits of measurable surface biomarkers. Methods: We incorporated into the development and validation of flow cytometry assays the measurement of the lower limit of quantitation (LLOQ). The LLOQ is the lowest number of a reportable parameter in a blood or bone marrow study sample that can be quantitatively determined with acceptable precision and accuracy. Two steps are necessary to determine the LLOQ. First in these assessments a measurable range of lower limits of a particular cell type or receptor is estimated. That is, in validating an assay LLOQ, there are three options to select cells expressing target surface biomarkers of interest: using cultured or bioengineered cells, using samples of known high expression of a biomarker, or using pre-titered positive samples. Then decreasing concentrations of the target cell or receptor may be used to precisely determine the LLOQ of a specific assay reportable parameter. Results: By acquiring at least ten negative control sample results, the limit of the blank (LOB) and limit of detection (LOD) of a biomarker is determined. LOB is calculated as mean +1.645 SD, and LOD as mean +3 SD. The negative control samples either lack the fluorescent monoclonal antibodies against the markers of interest or lack the target cell population. Different reportable parameters, detected by one or more biomarkers have varying LLOQ. The LLOQ for a reportable parameter is a precise measurement of a parameter above or equal to the LOD. We found that typical LLOQ values are from 4 to 145 positive cells, with a frequency of 0.01 to 0.1% among a parent population. For example, in the case of tetramer assays, flow cytometry can reliably detect as few as 25 CD8+ antigen-specific cells among three million lymphocytes. Conclusions: LLOQ determinations for exploratory flow cytometry biomarkers are required for clinical research in cancer immunotherapy and cancer vaccine development. This valuable information allows for interpretation of data at the low end of a measurable range. Citation Format: Chengsen Xue, Christina D. Swenson, Thomas W. Mc Closkey. Estimating sensitivity of exploratory cellular biomarkers in oncology clinical trials [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 1171.

Abstract 4475: Discovery of an oral tricyclic STING agonist with superior pharmacokinetic properties and potent in vivo efficacy

Abstract Stimulator of interferon genes (STING) plays a pivotal role in regulating immune microenvironment for cancer immunotherapy. However, the use of most STING agonists has been hindered by the necessity for intra-tumoral or intravenous administration, underscoring the challenge in developing an orally bioavailable STING agonist with favorable pharmacokinetic (PK) properties. In this study, we discovered oral STING agonists featuring a novel tricyclic benzo[4,5]thieno[2,3-c]pyrrole-1,3-dione scaffold, thus achieving both superior PK properties and potent in vivo efficacy. Our lead compound, ZSA-51, exhibited nanomolar cellular STING activation activity (EC50 = 100 nM) in THP1 cells, surpassing the reported oral STING agonist MSA-2 by 32-fold (EC50 = 3200 nM). Furthermore, ZSA-51 demonstrated superior PK properties with an oral bioavailability of 49%, and robust in vivo antitumor activity both in colon and pancreatic cancers model upon oral administration. Notably, ZSA-51 displayed preferential distribution to the lymph nodes and spleen, enhancing its systemic immune-stimulating effects. The specificity of ZSA-51 was further confirmed by a comparison with a negative control compound (ZSA-52NC2) that was unable to stimulate in vitro and in vivo STING activity. Molecular docking and MD simulation confirmed that the active form of ZSA-51 stably bound to STING dimer with validated hydrogen bond network. Taken together, our findings suggest ZSA-51 as a promising oral STING agonist characterized by superior PK properties and potent in vivo efficacy, holding potential for future development for cancer immunotherapy. Citation Format: Hong-Yi Zhao, Zhongwei Liu, Shuai Mao, Miao He, Meilin Wang, Bo Wen, Wei Gao, Duxin Sun. Discovery of an oral tricyclic STING agonist with superior pharmacokinetic properties and potent in vivo efficacy [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 4475.

Eosinophils exhibit a unique transcriptional signature and increased sensitivity to IL-3-induced activation in response to colorectal cancer cells.

Eosinophils have been mainly studied in allergic diseases and parasitic infections. Nonetheless, eosinophils accumulate in a variety of solid tumors, including colorectal cancer, where their presence is associated with improved prognosis. Eosinophils can promote anti-tumor immunity through various mechanisms, including direct cytotoxicity towards tumor cells and promoting T cell activation. However, the mechanisms by which tumor cells regulate eosinophil activities are largely unknown. Herein, we characterized the potential interactions between eosinophils and colorectal cancer cells using an unbiased transcriptomic and proteomic analyses approach. Human eosinophils were stimulated with colorectal cancer cell-conditioned media, containing tumor cell-secreted factors from multiple cancer cell lines. RNA sequencing analysis identified a "core" signature consisting of 101 genes that characterize a baseline transcriptional program for the response of human eosinophils to colorectal cancer cells. Among these, the increased expression of IL-3Rα and its βc chain was identified and validated at the protein level. Secreted factors from tumor cells potentiated IL-3-induced expression of the adhesion molecule CD11a in eosinophils. Combining proteomics analysis of tumor cell-secreted factors with RNA sequencing revealed potential ligand-receptor pairs between tumor cells and eosinophils and the potential involvement of the adhesion molecule CD18 and F2RL3/PAR4. Subsequent functional analyses demonstrated that F2RL3/PAR4 suppresses eosinophil migration in response tumor cell-secreted factors. These findings add to the growing body of evidence that eosinophils are conditioned by their local microenvironment. Identifying mechanisms by which eosinophils interact with tumor cells could lead to the development of new immunotherapies for colorectal cancer and other solid tumors.

Discovery of Pyrido[2,3-d]pyrimidin-7-one Derivatives as Highly Potent and Efficacious Ectonucleotide Pyrophosphatase/Phosphodiesterase 1 (ENPP1) Inhibitors for Cancer Treatment.

Ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) is an extracellular enzyme responsible for hydrolyzing cyclic guanosine monophosphate-adenosine monophosphate (cGAMP), the endogenous agonist for the stimulator of interferon genes (STING) pathway. Inhibition of ENPP1 can trigger STING and promote antitumor immunity, offering an attractive therapeutic target for cancer immunotherapy. Despite progress in the discovery of ENPP1 inhibitors, the diversity in chemical structures and the efficacy of the agents are far from desirable, emphasizing the demand for novel inhibitors. Herein, we describe the design, synthesis, and biological evaluation of a series of ENPP1 inhibitors based on the pyrido[2,3-d]pyrimidin-7-one scaffold. Optimization efforts led to compound 31 with significant potency in both ENPP1 inhibition and STING pathway stimulation in vitro. Notably, 31 demonstrated in vivo efficacy in a syngeneic 4T1 mouse triple negative breast cancer model. These findings provide a promising lead compound with a novel scaffold for further drug development in cancer immunotherapy.

Structure-Guided Discovery of PD-1/PD-L1 Interaction Inhibitors: Peptide Design, Screening, and Optimization via Computation-Aided Phage Display Engineering.

Cancer immunotherapy harnesses the immune system to combat tumors and has emerged as a major cancer treatment modality. The PD-1/PD-L1 immune checkpoint modulates interactions between tumor cells and T cells and has been extensively targeted in cancer immunotherapy. However, the monoclonal antibodies known to target this immune checkpoint have considerable side effects, and novel PD-1/PD-L1 inhibitors are therefore required. Herein, a peptide inhibitor to disrupt PD-1/PD-L1 interactions was designed through structure-driven phage display engineering coupled to computational modification and optimization. BetaPb, a novel peptide library constructed by using the known structure of PD-1/PD-L, was used to develop inhibitors against the immune checkpoint, and specific peptides with high affinity toward PD-1 were screened through enzyme-linked immunosorbent assays, homogeneous time-resolved fluorescence, and biolayer interferometry. A potential inhibitor, B8, was preliminarily screened through biopanning. The binding affinity of B8 toward PD-1 was confirmed through computation-aided optimization. Assessment of B8 variants (B8.1, B8.2, B8.3, B8.4, and B8.5) demonstrated their attenuation of PD-1/PD-L1 interactions. B8.4 exhibited the strongest attenuation efficiency at a half-maximal effective concentration of 0.1 μM and the strongest binding affinity to PD-1 (equilibrium dissociation constant = 0.1 μM). B8.4 outperformed the known PD-1/PD-L1 interaction inhibitor PL120131 in disrupting PD-1/PD-L1 interactions, revealing that B8.4 has remarkable potential for modification to yield an antitumor agent. This study provides valuable information for the future development of peptide-based drugs, therapeutics, and immunotherapies for cancer.

Abstract B046: Exploring the potential of commensal polyomavirus as a promising approach for breast cancer treatment

Abstract Cancer is a leading cause of mortality worldwide, accounting for nearly one in six deaths. Our understanding of the immune system role in cancer control has increased dramatically in recent decades, facilitating the recent development of effective cancer immunotherapies, which have significantly improved the survival of cancer patients. However, current immunotherapies can induce overactive immune responses with severe even fatal outcomes. Moreover, immunotherapy may not work in every scenario, especially in ‘cold’ tumors that lack immune cell infiltration. Thus, more effective immunotherapies with fewer side effects are under active investigation. Viruses are one of the most abundant biological entities in the world; about 12% to 20% of human cancers are associated with viral infections. Viral antigens can increase tumor immunogenicity, triggering T cell immunity against tumor cells. Polyomaviruses are small, nonenveloped double-stranded DNA viruses that are widespread. In immunocompetent hosts, polyomaviruses remain at a low persistent level in the host after the primary infection, which appears to cause little or no symptoms. Previous studies have shown high polyomavirus seroprevalence and the frequent presence of polyomavirus-specific T cells in healthy adult blood donors. In the elderly population, Merkel cell polyomavirus (MCPyV) infection is linked to Merkel cell carcinoma (MCC), a rare, aggressive skin cancer associated with immunosuppression. MCPyV integration into the genome is the primary oncogenic event in ~80% of MCC cases, and the remaining virus-negative MCC cases are associated with ultraviolet (UV) radiation. MCPyV-induced MCCs are associated with more intratumor immune cells and better responses to cancer therapy. Moreover, BK and JC polyomavirus positive lymphoma patients showed a trend toward significantly better overall survival. These clinical data suggest that polyomavirus in tumors may increase tumor immunogenicity. Thus, polyomavirus presents an intriguing opportunity to develop a novel strategy to enhance cancer immunogenicity. We utilized mouse polyomavirus (MPyV) to colonize typically ‘cold’ breast tumor cell line E0771 breast cancer cells in mice. MPyV infection blocked the growth of tumors in immunocompetent mice and promoted immune cell infiltration when intratumorally delivered to the tumor. The tumor rejection activity of polyomavirus is depend on CD4 and CD8 T cells. Unlike conventional oncolytic viruses which directly lyse the infected cells and trigger a nonspecific inflammatory response, polyomavirus does not lyse the colonized cells, and it induces a relatively low level of inflammation. Instead, polyomavirus stimulates viral antigen expression in tumors that boosts T cell response leading to epitope spreading to tumor-associated antigens. The outcomes of this research will establish the utility of commensal polyomavirus as a novel agent for cancer immunotherapy. Citation Format: YUN XIA. Exploring the potential of commensal polyomavirus as a promising approach for breast cancer treatment [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Breast Cancer Research; 2023 Oct 19-22; San Diego, California. Philadelphia (PA): AACR; Cancer Res 2024;84(3 Suppl_1):Abstract nr B046.

A Comprehensive Review on Exosome: Recent Progress and Outlook.

Exosomes are intrinsic membrane-based vesicles that play a key role in both normal and pathological processes. Since their discovery, exosomes have been investigated as viable drug delivery systems and clinical indicators because of their magnitude and effectiveness in delivering biological components to targeted cells. Exosome characteristics are biocompatible, prefer tumor recruitment, have tunable targeting efficiency, and are stable, making them outstanding and eye-catching medication delivery systems for cancer and other disorders. There is great interest in using cell-released tiny vesicles that activate the immune system in the age of the fast development of cancer immunotherapy. Exosomes, which are cell-derived nanovesicles, have a lot of potential for application in cancer immunotherapy due to their immunogenicity and molecular transfer function. More significantly, exosomes can transfer their cargo to specified cells and so affect the phenotypic and immune-regulation capabilities of those cells. In this article, we summarize exosomes' biogenesis, isolation techniques, drug delivery, applications, and recent clinical updates. The use of exosomes as drug-delivery systems for small compounds, macromolecules, and nucleotides has recently advanced. We have tried to give holistic and exhaustive pieces of information showcasing current progress and clinical updates of exosomes.