Activation Of Immune Effector Cells Research Articles

The role of calcium homeostasis in modulating the immune response in cancer and infectious diseases

Calcium homeostasis is a pivotal determinant of physiological processes, particularly in cellular signaling and immune system regulation. This balance is crucial for modulating immune responses in the context of both infectious and oncological diseases. Disruptions in calcium homeostasis have been shown to influence disease progression, immune efficacy, and treatment outcomes. Our study investigates the critical role of calcium homeostasis in shaping the immune response to cancer and infectious diseases through a comprehensive literature review. The electronic databases Scopus, Google Scholar, and PubMed were utilized to gather relevant studies, identified using key terms such as "calcium homeostasis," "immune response," "cancer," and "infectious diseases." Emerging evidence underscores that calcium levels directly impact immune cell function, including the activation of immune effector cells, cytokine production, and the orchestration of the overall immune response. These processes are critical to the body's ability to combat infections and malignancies. Aberrant calcium signaling may lead to compromised immune defense mechanisms, negatively affecting the outcomes of therapeutic interventions. In cancer, for example, altered calcium homeostasis can suppress immune surveillance, while in infectious diseases, it can hinder the immune system's capacity to clear pathogens. Our review highlights that the pathophysiology of both cancer and infectious diseases is tightly interwoven with calcium regulation, suggesting a promising avenue for therapeutic targeting. Modulating calcium homeostasis may enhance immune functionality, thereby improving treatment efficacy. By restoring calcium balance, novel therapeutic approaches could be developed to optimize immune responses and bolster clinical outcomes across a range of diseases. Further research is warranted to elucidate the precise molecular mechanisms linking calcium homeostasis and immune regulation, with the goal of refining future therapeutic strategies. Maintaining calcium equilibrium is thus essential for the advancement of effective treatments in both cancer and infectious disease contexts.

Engineered cytokine/antibody fusion proteins improve IL-2 delivery to pro-inflammatory cells and promote antitumor activity.

Progress in cytokine engineering is driving therapeutic translation by overcoming these proteins' limitations as drugs. The IL-2 cytokine is a promising immune stimulant for cancer treatment but is limited by its concurrent activation of both pro-inflammatory immune effector cells and antiinflammatory regulatory T cells, toxicity at high doses, and short serum half-life. One approach to improve the selectivity, safety, and longevity of IL-2 is complexing with anti-IL-2 antibodies that bias the cytokine toward immune effector cell activation. Although this strategy shows potential in preclinical models, clinical translation of a cytokine/antibody complex is complicated by challenges in formulating a multiprotein drug and concerns regarding complex stability. Here, we introduced a versatile approach to designing intramolecularly assembled single-agent fusion proteins (immunocytokines, ICs) comprising IL-2 and a biasing anti-IL-2 antibody that directs the cytokine toward immune effector cells. We optimized IC construction and engineered the cytokine/antibody affinity to improve immune bias. We demonstrated that our IC preferentially activates and expands immune effector cells, leading to superior antitumor activity compared with natural IL-2, both alone and combined with immune checkpoint inhibitors. Moreover, therapeutic efficacy was observed without inducing toxicity. This work presents a roadmap for the design and translation of cytokine/antibody fusion proteins.

Abstract B045: Sensitizing the PDAC tumor microenvironment to immune checkpoint therapies: characterization of a PDAC 3D model to decipher immune infiltration

Abstract Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal solid tumor with an unfavorable prognosis, often resistant to conventional treatments due to its dense stroma rich in Cancer- Associated Fibroblasts (CAFs). Limited T cell infiltration and prevalence of immunosuppressive cells within the tumor hinder the efficacy of immune checkpoint inhibitors (ICIs). The objective of our project is to modify immune landscape of PDAC tumor microenvironment (TME) to induce ICIs sensitization. We thus develop novel therapeutic strategies combining an immunomodulatory cytokine Interleukine-15 (IL15), with conventional chemotherapies (Gemcitabine or Folfirinox). To accurately replicate the complex cancer-stroma interactions within the pancreatic tumor microenvironment, we constructed a three-dimensional in vitro heterospheroid model composed of xenograft-derived tumor cells from PDAC patients, both primary or immortalized CAFs, and peripheral blood mononuclear cells (PBMCs) from healthy donors. Human 3D models were first set up and characterized by cytometry, imaging mass spectrometry and immunohistochemistry. We showed that, CAFs produce components of the extracellular matrix, promote tumor cell growth, improve resistance to chemotherapy and are able to down-regulate immune cell infiltration and modulate the nature of infiltrated immune cells. Spatial analysis of spheroids using imaging mass cytometry show that CAF influences the distribution of immune cells in our models. Interestingly, Interleukine 15 treatment prompted robust infiltration of PBMCs into heterospheroids. Immunophenotyping experiments revealed a substantial shift in the nature of immune infiltration, marked by a pronounced increase in CD4+ and CD8+ T lymphocytes, gDelta T cell and NK cell populations. When combined with Gemcitabine and IL15, immune effector cell infiltration is remarkably increased, resulting in antitumoral effects and control of tumor cell growth. Moreover, therapeutic combinations induce activation of infiltrated immune effector cells with an increase of activation, degranulation and cytotoxic markers, such as IFNγ, CD107a, and Granzyme B respectively. Thus, the heterotypic spheroids described in our study are a suitable in vitro model to both characterize the influence of CAF on therapeutic effects and the mechanisms that drives immune suppressive microenvironment. Moving forward, the next steps will consist to conduct in vivo experiments using a syngeneic PDAC orthotopic model to assess whether this combined therapeutic approach sensitize the PDAC microenvironment to anti-PD1 therapies. Citation Format: Thomas Bessede, Clara Freixinos, Jennifer Barrat, Véronique Garambois, Nadia Vie, Henri-Alexandre Michaud, Julien Faget, Nathalie Bonnefoy, Céline Gongora, Bruno Robert, Laurent Gros, Christel Larbouret. Sensitizing the PDAC tumor microenvironment to immune checkpoint therapies: characterization of a PDAC 3D model to decipher immune infiltration [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr B045.

Abstract B046: Sensitizing the PDAC tumor microenvironment to immune checkpoint therapies: characterization of a PDAC 3D model to decipher immune infiltration

Abstract Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal solid tumor with an unfavorable prognosis, often resistant to conventional treatments due to its dense stroma rich in Cancer- Associated Fibroblasts (CAFs). Limited T cell infiltration and prevalence of immunosuppressive cells within the tumor hinder the efficacy of immune checkpoint inhibitors (ICIs). The objective of our project is to modify immune landscape of PDAC tumor microenvironment (TME) to induce ICIs sensitization. We thus develop novel therapeutic strategies combining an immunomodulatory cytokine Interleukine-15 (IL15), with conventional chemotherapies (Gemcitabine or Folfirinox). To accurately replicate the complex cancer-stroma interactions within the pancreatic tumor microenvironment, we constructed a three-dimensional in vitro heterospheroid model composed of xenograft-derived tumor cells from PDAC patients, both primary or immortalized CAFs, and peripheral blood mononuclear cells (PBMCs) from healthy donors. Human 3D models were first set up and characterized by cytometry, imaging mass spectrometry and immunohistochemistry. We showed that, CAFs produce components of the extracellular matrix, promote tumor cell growth, improve resistance to chemotherapy and are able to down-regulate immune cell infiltration and modulate the nature of infiltrated immune cells. Spatial analysis of spheroids using imaging mass cytometry show that CAF influences the distribution of immune cells in our models. Interestingly, Interleukine 15 treatment prompted robust infiltration of PBMCs into heterospheroids. Immunophenotyping experiments revealed a substantial shift in the nature of immune infiltration, marked by a pronounced increase in CD4+ and CD8+ T lymphocytes, gDelta T cell and NK cell populations. When combined with Gemcitabine and IL15, immune effector cell infiltration is remarkably increased, resulting in antitumoral effects and control of tumor cell growth. Moreover, therapeutic combinations induce activation of infiltrated immune effector cells with an increase of activation, degranulation and cytotoxic markers, such as IFNγ, CD107a, and Granzyme B respectively. Thus, the heterotypic spheroids described in our study are a suitable in vitro model to both characterize the influence of CAF on therapeutic effects and the mechanisms that drives immune suppressive microenvironment. Moving forward, the next steps will consist to conduct in vivo experiments using a syngeneic PDAC orthotopic model to assess whether this combined therapeutic approach sensitize the PDAC microenvironment to anti-PD1 therapies. Citation Format: Thomas Bessede, Clara Freixinos, Jennifer Barrat, Véronique Garambois, Nadia Vie, Henri-Alexandre Michaud, Julien Faget, Nathalie Bonnefoy, Céline Gongora, Bruno Robert, Laurent Gros, Christel Larbouret. Sensitizing the PDAC tumor microenvironment to immune checkpoint therapies: characterization of a PDAC 3D model to decipher immune infiltration [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr B046.

Biomarker analysis of zanzalintinib in clear cell renal cell carcinoma from STELLAR-001.

4545 Background: Zanzalintinib (zanza) is a novel oral multi-targeted TKI that inhibits several receptors, including VEGFR, MET, and TAM kinases. In an expansion cohort of previously treated patients (pts) with clear cell renal cell carcinoma (ccRCC) from the phase 1b STELLAR-001 study (NCT03845166), single-agent zanza showed encouraging activity (ORR, 38%; disease control rate, 88%), with responses seen in VEGFR TKI–pretreated pts, and a manageable safety profile (Pal, IKCS NA 2023:Abs 1). Here, we investigate biomarkers associated with zanza from the STELLAR-001 ccRCC expansion cohort. Methods: Adult pts (N=32) with advanced ccRCC, ECOG ≤1, and 1–3 prior systemic anticancer therapies received zanza 100 mg once daily until unacceptable toxicity or no longer deriving clinical benefit. Circulating plasma biomarkers and immune cell populations in blood were assessed at baseline and on-study. IHC for AXL, c-Met, phosphorylated Met, and VEGFR2 was performed on archival tissue. Associations between response to zanza and biomarker levels (at baseline and treatment-related changes) were investigated by comparing zanza responders (CR/PR; n=10) and non-responders (SD/PD; n=19). The relation between baseline biomarker levels and prior exposure to VEGFR TKI was also evaluated. P values were determined using a Wilcoxon test ( P<0.05 considered significant). Results: Zanza elicited significant changes in soluble biomarkers related to angiogenesis, tumor growth and metastasis, and immune modulation, including an increase in the circulating ligands VEGF ( P<0.001) and GAS6 ( P<0.001); decreases in ANG-1 ( P<0.001) and ANG-2 ( P<0.001), and the soluble angiogenic receptors, VEGFR2 ( P<0.001) and TIE-2 ( P<0.001). A decrease in levels of the chemokine, RANTES ( P<0.001), and an increase in IFNγ ( P=0.039) and the pro-apoptotic protein, granzyme B ( P<0.001) were also observed. An analysis of immune cell subsets showed that zanza raised activated cytotoxic T cell numbers ( P=0.002). Reductions in monocytes ( P=0.001), along with immunosuppressive subsets (total MDSCs [ P=0.013] and granulocytic MDSCs [ P=0.014]) were also observed. Response to zanza was associated with lower baseline levels of plasma biomarkers including CRP ( P=0.025) and HGF ( P=0.017), but not with any tissue biomarkers or zanza-mediated changes in immune cells or plasma biomarkers tested. Lower baseline levels of VEGFR2 were observed in pts with prior VEGFR TKI exposure ( P=0.042). Conclusions: Zanza in pts with advanced ccRCC leads to modulation of plasma biomarkers associated with angiogenesis and peripheral immune cell subsets consistent with its expected mechanism of action. The reduction in immunosuppressive immune cells and activation of effector immune cells by zanza support the rationale for combining zanza with immune checkpoint inhibitors. Given the small sample sizes, further investigation in larger studies is warranted. Clinical trial information: NCT03845166 .

Exploring the possible link between the spike protein immunoglobulin G4 antibodies and cancer progression

Repeated inoculation with messenger RNA (mRNA) vaccines elicits immunoglobulin G4 (IgG4) antibody production. Such an increase in the concentration of specific and non-specific IgG4 antibodies allows the growth of some types of cancer by blocking the activation of effector immune cells. This work proposes the hypothesis that cancer growth may be indirectly promoted by increased concentrations of non-specific IgG4 antibodies by the following mechanisms: 1) IgG4 antibodies can bind to anti-tumor IgG1 antibodies and block their interaction with receptors located on effector cells, thus preventing the destruction of cancer cells, 2) IgG4 can interact with fragment crystallizable gamma receptor IIb (FcγRIIB) inhibitory receptors, thus reducing effector functions of innate immune cells, and 3) targeting of specific epitopes by IgG4 could be oncogenic by inducing the production of a microenvironment that can promote cancer development. This article reviews the supporting literature and suggests several experimental protocols to evaluate this hypothesis in the context of repeated inoculation with mRNA vaccines. Additionally, this work proposes some management options aimed at reducing the unfavorable molecular consequences that could mediate cancer development when encountering high concentrations of IgG4 antibodies.

Bispecific antibodies for the treatment of relapsed/refractory multiple myeloma: updates and future perspectives.

Patients with relapsed/refractory multiple myeloma (RRMM) that are refractory to the five most active anti-MM drugs, so-called penta-refractory MM, have historically had dismal outcomes with subsequent therapies. Progressive immune dysfunction, particularly of the T-cell repertoire, is implicated in the development of disease progression and refractory disease. However, the advent of novel immunotherapies such as bispecific antibodies are rapidly changing the treatment landscape and improving the survival outcomes of patients with RRMM. Bispecific antibodies are antibodies that are engineered to simultaneously engage cytotoxic immune effector cells (T cells or NK cells) and malignant plasma cells via binding to immune effector cell antigens and extracellular plasma cell antigens leading to immune effector cell activation and malignant plasma cell destruction. Currently, bispecific antibodies that bind CD3 on T cells and plasma cell epitopes such as B-cell maturation antigen (BCMA), G-protein coupled receptor family C group 5 member D (GPRC5d), and Fc receptor homologue 5 (FcRH5) are the most advanced in clinical development and are showing unprecedented response rates in patients with RRMM, including patients with penta-refractory disease. In this review article, we explore the available clinical data of bispecific antibodies in RRMM and summarize the efficacy, safety, toxicity, clinical outcomes, mechanisms of resistance, and future directions of these therapies in patients with RRMM.

Abstract 6659: Oncolytic herpes simplex virus expressing XCL1 and FLT3L modulate the intratumoral immune response and improve the anti-tumor efficacy in a metastatic breast tumor model

Abstract Patients with metastatic breast cancer (MBC) have a dismal prognosis, with a 5-year survival rate of only 26%. The inadequate infiltration of immune cells targeting the tumor microenvironment (TME) is a key factor contributing to this low survival rate. Immune effector cells, including CD8+ cytotoxic T cells, NKT cells, and NK cells, play a crucial role in targeting tumor cells. The activation of immune effector cells relies on the presence of conventional type I dendritic cells (cDC1), which present tumor-specific antigenic peptides on their surface. Recent studies have identified the chemokine XCL1 and growth factor FLT3L as critical factors involved in the intratumoral recruitment and expansion of dendritic cells. To enhance the activity of cDC1 in the TME we designed an oncolytic herpes simplex virus (oHSV) expressing XCL1 and FLT3L. The recombinant oHSV, rQ1-XF, was generated by incorporating LoxP sites into the viral genome through recombination with a carrier plasmid carrying the polycistronic cassette. To enhance the intratumoral penetration of oHSV injected intravenously in primary tumors and MBC lesions in the lung, we employed the cancer drug ganetespib, which can increase the permeability of tumor blood vessels. In comparison to untreated mice, ganetespib combined with rQ1-XF reduced the size of primary tumors and induced a short but significant increase in the survival of mice. Additionally, compared to the ganetespib alone treatment, ganetespib combined with rQ1-XF reduced MBC burden in the lung. The flow cytometry analysis of immune cells revealed an increased infiltration of CD11c+CD11b- dendritic cells in primary tumors treated with oHSV combination therapy compared to the ganetespib only control. A similar trend was also observed in CD4 T cells and CD8 T cells in primary tumors. As expected, there was a negative correlation between tumor burden and the infiltration of CD4+ T cells and CD8+ T cells in primary tumors. Ganetespib combined with oHSV also reduced the infiltration of CD4+ regulatory T cells (Tregs) in primary tumors, however the number of Tregs increased with primary tumor size as well as tumor burden in the lung. This could potentially lead to reduced efficacy of tumor-infiltrating dendritic cells in activating effector T cells in tumors treated with ganetespib and rQ1-XF. Moreover, the combination therapy did not yield significant alterations in the populations of DCs, CD4+ T cells, and CD8+ T cells in lungs with metastatic lesions. Further studies are underway to investigate whether the depletion of Treg cells in combination with rQ1-XF enhances effector T cell activation against metastatic breast tumor cells. The findings of this study will provide valuable insights into the effectiveness of using XCL1 and FLT3L-armed oncolytic viruses in patients with MBC. Citation Format: Himanshu Soni, Liqun Gu, Sylvie Roberge, Heena Kumra, Hiroshi Nakashima, E. Antonio Chiocca, Yves Boucher. Oncolytic herpes simplex virus expressing XCL1 and FLT3L modulate the intratumoral immune response and improve the anti-tumor efficacy in a metastatic breast tumor model [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 6659.

Abstract 4005: HER2 TKIs enhance the anti-tumor activity of HER2-targeting CAR-T and CAR-NK cells against NSCLC

Abstract Approximately 3% of non-small cell lung cancer (NSCLC) cases harbor ERBB2/HER2 mutations. Notably, the majority of actionable HER2 mutations in NSCLC are in-frame insertions in exon 20. Current HER2-targeting approaches, including antibody-drug conjugates (ADCs) such as trastuzumab deruxtecan, have shown promising response rates. To explore novel strategies for targeting HER2-positive NSCLC, we investigated chimeric antigen receptor (CAR)-based therapies to enhance the anti-tumor activity of immune effector cells. We engineered a series of HER2 CAR constructs utilizing scFvs derived from trastuzumab, pertuzumab, and FRP5, recognizing distinct domains of HER2. These scFvs were integrated into second-generation BB3z (with 4-1BB and CD3z intracellular domains) and third-generation 28BB3z (with CD28, 4-1BB, and CD3z intracellular domains) CAR backbones, which were subsequently transduced into activated T and natural killer (NK) cells to generate CAR-T and CAR-NK cells, respectively. High transduction efficiencies were achieved, with over 80% in CAR-T cells and over 50% in CAR-NK cells. We next evaluated their activity against a panel of NSCLC cell lines expressing varying levels of HER2 in vitro using firefly luciferase assays. All HER2 CAR-T cells demonstrated more than 90% killing against H2170 (HER2 high) and H322 (HER2 medium) at an effector:target (E:T) ratio of 10:1, whereas HER2 CAR-T cells yielded a killing effect of 35% against A549 (HER2 low) cells. HER2-targeting CAR-NK cells also displayed potent cytotoxicity against HER2-expressing NSCLC cells. Moreover, we observed that treatment of HER2 mutant and HER2 amplified NSCLC cells with low doses of HER2 tyrosine kinase inhibitors (TKIs) such as poziotinib enhanced the expression of HER2 on the cell surface. This upregulation resulted in enhanced activation of HER2 CAR-T and CAR-NK cells in coculture experiments as measured by CD107a expression on effector cells. Additionally, treatment with the HER2 TKI poziotinib potentiated the killing activity mediated by HER2 CAR-T and CAR-NK cells. Using a HER2 YVMA duplication patient-derived xenograft (PDX) NSCLC model, we observed that the in vivo combination of poziotinib with HER2 CAR-NK cells exhibited superior anti-tumor activity as compared to poziotinib treatment alone. In conclusion, HER2 CAR-T and CAR-NK cells effectively target HER2-mutant and HER2-positive NSCLC, and their combination with HER2 TKIs enhances vulnerability to HER2-targeting strategies. Citation Format: Yan Yang, Monique B. Nilsson, Alissa Poteete, Junqin He, Qian Huang, John V. Heymach. HER2 TKIs enhance the anti-tumor activity of HER2-targeting CAR-T and CAR-NK cells against NSCLC [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 4005.

Abstract 1281: Antibiotics aerosolization shrinks intratumoral Tregs and impairs lung tumor growth by perturbing the taxonomic structure of tumor-associated microbiota

Abstract The lung has been traditionally regarded as a sterile environment. Emerging evidence has overturned this belief unveiling the existence of a specific lung microbiota that plays a pivotal role in modulating lung immune tolerance. Recent research also sheds light on how the tissue microbiota is significantly altered by the presence of a growing tumor. Here, we investigated the compositional changes in lung-colonizing bacterial populations associated with the growth of LLC1 lung carcinoma cells in C57BL/6 mice, by analyzing the lung 16S rRNA profiling. While overall microbial diversity and structure were similar in tumor-bearing and healthy lungs, abundance analysis of amplicon sequence variants (ASVs) revealed that 48 ASVs were differentially modulated at significant level (FDR ≤ 0.05). Notably, local treatment with aerosolized vancomycin/neomycin antibiotics starting 4 days after tumor injection caused a different representation of 47 ASVs (FDR ≤ 0.05), mostly reducing those ASVs specifically emerging in the lung by the tumor growth, belonging to Bacterioidales, Clostridiales, Lactobacillales and Enterobacteriales. A different microbial composition was also suggested by the results of Partial Least Squares Discriminant Analysis (PLS-DA) that clustered lung tumor samples as saline or antibiotic-aerosolized. Based on the reported ability of some bacteria belonging to these orders to induce immunosuppressive cells in the gut, we examined the impact of antibiotic aerosol on tumor-associated Tregs in the lung. The presence of the tumor promoted the appearance of Tregs expressing CD69 and PD-1 activation markers, but vancomycin/neomycin aerosol treatment strongly dropped Treg frequency in tumor-bearing lungs, compared to saline. In a therapeutic setting, aerosolization of antibiotics starting 4 days after LLC1 tumor intravenous injection significantly reduced the number of lung metastases (p=0.0116). This effect was associated with an increased cytotoxic activity of immune infiltrating effector cells suggesting that the modulation of the lung microbiota impairs tumor growth and enhances antitumor immune response. Some cultivable bacterial strains, that were in agreement with metataxonomic profile results, were isolated from tumor-bearing lungs, but not from healthy lungs. Ongoing experiments suggest an effect of their in vivo transfer in the lung by aerosol on tumor growth and the ability to induce Treg expansion in vitro. Overall, this study unveils that the growth of the murine LLC1 tumor shapes the lung microbial composition by favoring the expansion of microbes with potential immunosuppressive activity eventually affecting the tumor progression. Moreover, our findings unravel the therapeutic potential of localized antibiotics to revert the immunosuppressive microenvironment by targeting tumor-associated bacteria. Citation Format: Giancarla Bernardo, Valentino Le Noci, Elena Montanari, Emerenziana Ottaviano, Giorgio Gargari, Elisa Borghi, Simone Guglielmetti, Federico Ambrogi, Tiziana Triulzi, Elda Tagliabue, Serenella M. Pupa, Michele Sommariva, Lucia Sfondrini. Antibiotics aerosolization shrinks intratumoral Tregs and impairs lung tumor growth by perturbing the taxonomic structure of tumor-associated microbiota [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 1281.

Tumor-derived extracellular vesicles in the immune microenvironment of head and neck squamous cell carcinoma: Foe or future?

Head and neck squamous cell carcinoma (HNSCC) is considered a “cold tumor” due to its suppressive immune microenvironment, and is associated with a poor prognosis. Tumor-derived extracellular vesicles (EVs) play an essential role in the tumor microenvironment and mediate intercellular communications. EVs have been proven to be key immune regulators involved in antitumor immune responses and escape from immune surveillance. Tumor-derived EVs favor the formation of an immunosuppressive tumor microenvironment by regulating the differentiation, proliferation and activation of innate and adaptive immune effector cells, as well as myeloid cells, acting as a “foe” in the microenvironment. However, EVs are also valuable for predicting and improving the prognosis of HNSCC, and represent hope for future treatments. In this review, we summarize the impact of HNSCC-derived EVs on the immune microenvironment, describe their roles as biomarkers and for drug delivery in disease monitoring and treatment. We provide insights into important areas for future research and identify potential therapeutic targets for HNSCC treatment.

Abstract A071: Pancreas organoid immune co-culture system identifies immunomodulators in pancreas adenocarcinoma

Abstract Background Metastatic pancreas adenocarcinoma (PDAC) is highly lethal and minimally responsive to immunotherapy. Gamma delta T cells (gDTs) are a unique T cell subset found within the PDAC microenvironment. Animal models have shown that gDTs promote oncogenic progression and ablating gDT delays cancer progression and improves survival. Understanding the activity of immune effector cells against cancer organoids provides a scalable platform to understand the impact of activation and small molecule modulation to redirect gDT killing in PDAC. Methods Patient-derived organoids (PDOs) were generated from fresh tissue sampling and exapanded using a defined, serum-free media. Upon passaging, media was collected from PDAC PDOs. Allogeneic gDTs isolated from healthy donors were cultured in PDAC PDO conditioned media from 3 separate PDOs, in 3 separate biological replicates, and then subjected to bulk RNAseq. Allogeneic gDTs were isolated and cultured with PDAC PDOs at ratio of 5:1 (gDTs:PDAC PDOs) for 48 hours. After 48 hours, staining was performed for induction of apoptosis (cleaved caspase-3/7FITC). Images were acquired by high content imaging (Cytation 5, BioTek) and quantified for response across organoid populations. Based on RNAseq nominated candidates, low density lipoprotein (LDL) was added (10 ug/mL) as well as a small molecule inverse agonist of the Liver X Receptor (LXR) beta transcription factor (SR9243) to assess the ability of these factors to modulate gDT mediated PDAC killing. Results Exposure of gDTs to PDAC PDO secreted factors results in differential regulation of cholesterol handling, including upregulation of cholesterol efflux, and downregulation of cholesterol uptake and biosynthesis related genes in conditioned T cell populations. gDTs cause marked apoptosis in PDAC PDOs, including 40% staining of % organoid area versus negligible staining in control populations of 1.9% organoid area (effect size = 9.5, p<0.001). This response was directly compared to standard chemotherapy at the time of clinical resistance to FOLFIRINOX which conferred only 2% staining of mean organoid area (effect size = 0.11, NS). Given RNAseq data demonstrating cholesterol handling changes after exposure to PDAC secreted factors, we investigated LDL supplementation in our model. Supplementation of LDL significantly improves gDT mediated killing, with induction of apoptosis seen in 52% of the PDAC PDO area (p=0.003). This effect is mimicked by the small molecule SR9243 (an LXR inverse agonist), with 56% of PDAC PDO demonstrating apoptotic induction at 48 hours. Conclusions A PDAC PDO model system can be used to investigate gDT mediated PDAC killing when applied in low-volume medium throughput screening applications. Modulation of LXR activity and microenvironment LDL results in substantially increased immune-mediated killing of PDAC. This screening platform identifies potentially clinically actionable modulators of immune response to PDAC, and suggests potential future immunologically relevant targets that may improve the efficacy of immunotherapy. Citation Format: Johnathan D Ebben, David Turicek, Md Shahadat Hossan, Austin Stram, Ethan Lin, Nicholas Hess, Zachary Mayhew, Melissa A Kinney, Devin Burpee, Anikait Patel, Christian M Capitini, Jeremy D Kratz. Pancreas organoid immune co-culture system identifies immunomodulators in pancreas adenocarcinoma [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr A071.

Cold to Hot: Tumor Immunotherapy by Promoting Vascular Normalization Based on PDGFB Nanocomposites.

Immunotherapy is a promising cancer therapeutic strategy. However, the "cold" tumor immune microenvironment (TIME), characterized by insufficient immune cell infiltration and immunosuppressive status, limits the efficacy of immunotherapy. Tumor vascular abnormalities due to defective pericyte coverage aregradually recognized as a profound determinant in "cold" TIME establishment by hindering immune cell trafficking. Recently, several vascular normalization strategies by improving pericyte coverage have been reported, whereas have unsatisfactory efficacy and high rates of resistance. Herein, a combinatorial strategy to induce tumor vasculature-targeted pericyte recruitment and zinc ion-mediated immune activation with aplatelet-derived growth factor B (PDGFB)-loaded, cyclo (Arg-Gly-Asp-D-Phe-Lys)-modified zeolitic imidazolate framework 8 (PDGFB@ZIF8-RGD) nanoplatform is proposed. PDGFB@ZIF8-RGD effectively induced tumor vascular normalization, which facilitated trafficking and infiltration of immune effector cells, including natural killer (NK) cells, M1-like macrophages and CD8+ T cells, into tumor microenvironment. Simultaneously, vascular normalization promoted the accumulation of zinc ions inside tumors to trigger effector cell immune activation and effector molecule production. The synergy between these two effects endowed PDGFB@ZIF8-RGD with superior capabilities in reprogramming the "cold" TIME to a "hot" TIME, thereby initiating robust antitumor immunity and suppressing tumor growth. This combinatorial strategy for improving immune effector cell infiltration and activation is a promising paradigm for solid tumor immunotherapy.

The Role of Human Endogenous Retrovirus (HERV)-K119 env in THP-1 Monocytic Cell Differentiation.

Human endogenous retrovirus (HERV)-K was reportedly inserted into the human genome millions of years ago and is closely related to various diseases, including cancer and immune regulation. In our previous studies, CRISPR-Cas9-enabled knockout (KO) of the HERV-K env gene was found to potentially reduce cell proliferation, cell migration, and invasion in colorectal and ovarian cancer cell lines. The immune response involves the migration and invasion of cells and is similar to cancer; however, in certain ways, it is completely unlike cancer. Therefore, we induced HERV-K119 env gene KO in THP-1, a monocytic cell that can be differentiated into a macrophage, to investigate the role of HERV-K119 env in immune regulation. Cell migration and invasion were noted to be significantly increased in HERV-K119 env KO THP-1 cells than in MOCK, and these results were contrary to those of cancer cells. To identify the underlying mechanism of HERV-K119 env KO in THP-1 cells, transcriptome analysis and cytokine array analysis were conducted. Semaphorin7A (SEMA7A), which induces the production of cytokines in macrophages and monocytic cells and plays an important role in immune effector cell activation during an inflammatory immune response, was significantly increased in HERV-K119 env KO THP-1 cells. We also found that HERV-K119 env KO THP-1 cells expressed various macrophage-specific surface markers, suggesting that KO of HERV-K119 env triggers the differentiation of THP-1 cells from monocytic cells into macrophages. In addition, analysis of the expression of M1 and M2 macrophage markers showed that M1 macrophage marker cluster of differentiation 32 (CD32) was significantly increased in HERV-K119 env KO cells. These results suggest that HERV-K119 env is implicated in the differentiation of monocytic cells into M1 macrophages and plays important roles in the immune response.

Rapamycin nanoparticles increase the therapeutic window of engineered interleukin-2 and drive expansion of antigen-specific regulatory T cells for protection against autoimmune disease

Interleukin-2 (IL-2) therapies targeting the high affinity IL-2 receptor expressed on regulatory T cells (Tregs) have shown promising therapeutic benefit in autoimmune diseases through nonselective expansion of pre-existing Treg populations, but are potentially limited by the inability to induce antigen-specific Tregs, as well as by dose-limiting activation of effector immune cells in settings of inflammation. We recently developed biodegradable nanoparticles encapsulating rapamycin, called ImmTOR, which induce selective immune tolerance to co-administered antigens but do not increase total Treg numbers. Here we demonstrate that the combination of ImmTOR and an engineered Treg-selective IL-2 variant (termed IL-2 mutein) increases the number and durability of total Tregs, as well as inducing a profound synergistic increase in antigen-specific Tregs when combined with a target antigen. We demonstrate that the combination of ImmTOR and an IL-2 mutein leads to durable inhibition of antibody responses to co-administered AAV gene therapy capsid, even at sub-optimal doses of ImmTOR, and provides protection in autoimmune models of type 1 diabetes and primary biliary cholangitis. Importantly, ImmTOR also increases the therapeutic window of engineered IL-2 molecules by mitigating effector immune cell expansion and preventing exacerbation of disease in a model of graft-versus-host-disease. At the same time, IL-2 mutein shows potential for dose-sparing of ImmTOR. Overall, these results establish that the combination of ImmTOR and an IL-2 mutein show synergistic benefit on both safety and efficacy to provide durable antigen-specific immune tolerance to mitigate drug immunogenicity and to treat autoimmune diseases.

Irradiated Extramedullary Acute Myeloid Leukemia Increases Survival in a Leukemic Mouse Model

The systemic nature of AML likely limits their immunogenicity because antigen presentation is primarily mediated by splenic dendritic cells, which induces immune tolerance. Since antigen presentation in tissue draining lymph nodes can induce anti-tumor immune responses, we hypothesized that local irradiation of cutaneous, extramedullary leukemias will increase immunogenic cell death, dendritic cell maturation and improved survival. A murine AML cell line C1498 was assessed for immunogenic markers calreticulin (CALR), HMGB1 and cGAS-STING pathway using fluorescence cytometry and qRT-PCR. Syngeneic mice were injected with C1498 subcutaneously to model extramedullary lesions and intravenously to model systemic leukemias. Cells and subcutaneous tumor were focally irradiated with 2 Gy or 8 Gy. Two-way ANOVA and Student's t-test were used for paired-wise comparisons. Survival was estimated by Kaplan-Meier plot and groups were compared using log-rank test. C1498 cells or tumors irradiated with 2 Gy or 8 Gy showed increased CALR and HMGB1 as well as (cGAS/Md21b1; 5-fold; p<0.001) and interferon alpha (Ifna; 3-fold; p<0.001) after 48h (18- and 4-fold, respectively; p<0.05) compared to not treated controls (NTC). Irradiated C1498 subcutaneous tumors displayed increased CD11b-positive cells (9-fold; p<0.001), CD11c (6-fold; p<0.001), and MHCII-positive CD11c cells (4-fold; p<0.01) in irradiated tumors compared to NTC. Irradiation of subcutaneous C1498 tumors increased median survival in mice also injected with C1498 cells intravenously compared to non-irradiated mice bearing systemic leukemias (46 vs. 25 days; p<0.01). Irradiation of C1498 tumors combined with anti-PDL1 treatment further increased median survival in our leukemia model compared to untreated controls (>50 vs. <30 days; p<0.001). Irradiated extramedullary AML increased immunogenic markers and activation of immune effector cells that correlated with increased survival in mice also bearing systemic leukemia. These results suggest focal irradiation of extramedullary AML may facilitate eradiation of systemic leukemias.

A novel [89Zr]-anti-PD-1-PET-CT to assess response to PD-1/PD-L1 blockade in lung cancer.

Harnessing the anti-tumor immune system response by targeting the program cell death protein (PD-1) and program cell death ligand protein (PD-L1) axis has been a major breakthrough in non-small cell lung cancer (NSCLC) therapy. Nonetheless, conventional imaging tools cannot accurately assess response in immunotherapy-treated patients. Using a lung cancer syngeneic mouse model responder to immunotherapy, we aimed to demonstrate that [89Zr]-anti-PD-1 immuno-PET is a safe and feasible imaging modality to assess the response to PD-1/PD-L1 blockade in NSCLC. A syngeneic mouse model responder to anti-PD-1 therapy was used. Tumor growth and response to PD-1 blockade were monitored by conventional 2-deoxy-2-[18F]fluoro-D-glucose ([18F]-FDG) PET scans. Additionally, tumor lymphocyte infiltration was analyzed by the use of an [89Zr]-labeled anti-PD-1 antibody and measured as 89Zr tumor uptake. Conventional [18F]-FDG-PET scans failed to detect the antitumor activity exerted by anti-PD-1 therapy. However, [89Zr]-anti-PD-1 uptake was substantially higher in mice that responded to PD-1 blockade. The analysis of tumor-infiltrating immune cell populations and interleukins demonstrated an increased anti-tumor effect elicited by activation of effector immune cells in PD-1-responder mice. Interestingly, a positive correlation between [89Zr]-anti-PD-1 uptake and the proportion of tumor-infiltrating lymphocytes (TILs) was found (Cor = 0.8; p = 0.001). Our data may support the clinical implementation of immuno-PET as a promising novel imaging tool to predict and assess the response of PD-1/PD-L1 inhibitors in patients with NSCLC.

Aminobisphosphonates reactivate the latent reservoir in people living with HIV-1.

Antiretroviral therapy (ART) is not curative due to the existence of cellular reservoirs of latent HIV-1 that persist during therapy. Current research efforts to cure HIV-1 infection include "shock and kill" strategies to disrupt latency using small molecules or latency-reversing agents (LRAs) to induce expression of HIV-1 enabling cytotoxic immune cells to eliminate infected cells. The modest success of current LRAs urges the field to identify novel drugs with increased clinical efficacy. Aminobisphosphonates (N-BPs) that include pamidronate, zoledronate, or alendronate, are the first-line treatment of bone-related diseases including osteoporosis and bone malignancies. Here, we show the use of N-BPs as a novel class of LRA: we found in ex vivo assays using primary cells from ART-suppressed people living with HIV-1 that N-BPs induce HIV-1 from latency to levels that are comparable to the T cell activator phytohemagglutinin (PHA). RNA sequencing and mechanistic data suggested that reactivation may occur through activation of the activator protein 1 signaling pathway. Stored samples from a prior clinical trial aimed at analyzing the effect of alendronate on bone mineral density, provided further evidence of alendronate-mediated latency reversal and activation of immune effector cells. Decay of the reservoir measured by IPDA was however not detected. Our results demonstrate the novel use of N-BPs to reverse HIV-1 latency while inducing immune effector functions. This preliminary evidence merits further investigation in a controlled clinical setting possibly in combination with therapeutic vaccination.

Biosynthesized gold nanoparticles that activate Toll-like receptors and elicit localized light-converting hyperthermia for pleiotropic tumor immunoregulation

Manipulating the tumor immune contexture towards a more active state can result in better therapeutic outcomes. Here we describe an easily accessible bacterial biomineralization-generated immunomodulator, which we name Ausome (Au + [exo]some). Ausome comprises a gold nanoparticle core covered by bacterial components; the former affords an inducible hyperthermia effect, while the latter mobilizes diverse immune responses. Multiple pattern recognition receptors actively participate in Ausome-initiated immune responses, which lead to the release of a broad spectrum of pro-inflammatory cytokines and the activation of effector immune cells. Upon laser irradiation, tumor-accumulated Ausome elicits a hyperthermic response, which improves tissue blood perfusion and contributes to enhanced infiltration of immunostimulatory modules, including cytokines and effector lymphocytes. This immune-modulating strategy mediated by Ausome ultimately brings about a comprehensive immune reaction and selectively amplifies the effects of local antitumor immunity, enhancing the efficacy of well-established chemo- or immuno-therapies in preclinical cancer models in female mice.

A Novel Bispecific Antibody for EpCAM-Directed Inhibition of the CD73/Adenosine Immune Checkpoint in Ovarian Cancer.

PD-1/PD-L1-inhibiting antibodies have shown disappointing efficacy in patients with refractory ovarian cancer (OC). Apparently, OC cells exploit nonoverlapping immunosuppressive mechanisms to evade the immune system. In this respect, the CD73-adenosine inhibitory immune checkpoint is of particular interest, as it rapidly converts pro-inflammatory ATP released from cancer cells to immunosuppressive adenosine (ADO). Moreover, cancer-cell-produced ADO is known to form a highly immunosuppressive extra-tumoral 'halo' that chronically inhibits the anticancer activity of various immune effector cells. Thus far, conventional CD73-blocking antibodies such as oleclumab show limited clinical efficacy, probably due to the fact that it indiscriminately binds to and blocks CD73 on a massive surplus of normal cells. To address this issue, we constructed a novel bispecific antibody (bsAb) CD73xEpCAM that inhibits CD73 expressed on the OC cell surface in an EpCAM-directed manner. Importantly, bsAb CD73xEpCAM showed potent capacity to inhibit the CD73 enzyme activity in an EpCAM-directed manner and restore the cytotoxic activity of ADO-suppressed anticancer T cells. Additionally, treatment with bsAb CD73xEpCAM potently inhibited the proliferative capacity of OC cells and enhanced their sensitivity to cisplatin, doxorubicin, 5FU, and ionizing radiation. BsAb CD73xEpCAM may be useful in the development of tumor-directed immunotherapeutic approaches to overcome the CD73-mediated immunosuppression in patients with refractory OC.