Syngeneic Murine Model Research Articles

CCK Receptor Inhibition Reduces Pancreatic Tumor Fibrosis and Promotes Nanoparticle Delivery.

The poor prognosis for pancreatic ductal adenocarcinoma (PDAC) patients is due in part to the highly fibrotic nature of the tumors that impedes delivery of therapeutics, including nanoparticles (NPs). Our prior studies demonstrated that proglumide, a cholecystokinin receptor (CCKR) antagonist, reduced fibrosis pervading PanIN lesions in mice. Here, we further detail how the reduced fibrosis elicited by proglumide achieves the normalization of the desmoplastic tumor microenvironment (TME) and improves nanoparticle uptake. One week following the orthotopic injection of PDAC cells, mice were randomized to normal or proglumide-treated water for 3-6 weeks. Tumors were analyzed ex vivo for fibrosis, vascularity, stellate cell activation, vascular patency, and nanoparticle distribution. The histological staining and three-dimensional imaging of tumors each indicated a reduction in stromal collagen in proglumide-treated mice. Proglumide treatment increased tumor vascularity and decreased the activation of cancer-associated fibroblasts (CAFs). Additionally, PANC-1 cells with the shRNA-mediated knockdown of the CCK2 receptor showed an even greater reduction in collagen, indicating the CCK2 receptors on tumor cells contribute to the desmoplastic TME. Proglumide-mediated reduction in fibrosis also led to functional changes in the TME as evidenced by the enhanced intra-tumoral distribution of small (<12 nm) Rhodamine-loaded nanoparticles. The documented in vivo, tumor cell-intrinsic anti-fibrotic effects of CCK2R blockade in both an immunocompetent syngeneic murine PDAC model as well as a human PDAC xenograft model demonstrates that CCK2R antagonists, such as proglumide, can improve the delivery of nano-encapsulated therapeutics or imaging agents to pancreatic tumors.

Evaluation of the EMulate Therapeutics Voyager’s ultra-low radiofrequency energy in murine model of glioblastoma

BackgroundGlioblastoma (GBM) presents as an aggressive brain cancer, notorious for its recurrence and resistance to conventional treatments. This study aimed to assess the efficacy of the EMulate Therapeutics Voyager®, a non-invasive, non-thermal, non-ionizing, battery-operated, portable experimental medical device, in treating GBM. Using ultra-low radiofrequency energy (ulRFE) to modulate intracellular activity, previous preliminary results in patients have been encouraging. Now, with a focus on murine models, our investigation seeks to elucidate the device's mechanistic impacts, further optimizing its therapeutic potential and understanding its limitations.MethodsThe device employs a silicone over molded coil to deliver oscillating magnetic fields, which are believed to interact with and disrupt cellular targets. These fields are derived from the magnetic fluctuations of solvated molecules. Xenograft and syngeneic murine models were chosen for the study. Mice were injected with U-87 MG or GL261 glioma cells in their flanks and were subsequently treated with one of two ulRFE cognates: A1A, inspired by paclitaxel, or A2, based on murine siRNA targeting CTLA4 + PD1. A separate group of untreated mice was maintained as controls.ResultsMice that underwent treatments with either A1A or A2 exhibited significantly reduced tumor sizes when compared to the untreated cohort.ConclusionThe EMulate Therapeutics Voyager® demonstrates promising potential in inhibiting glioma cells in vivo through its unique ulRFE technology and should be further studied in terms of biological effects in vitro and in vivo.

An AI-based approach for modeling the synergy between radiotherapy and immunotherapy

Personalized, ultra-fractionated stereotactic adaptive radiotherapy (PULSAR) is designed to administer tumoricidal doses in a pulsed mode with extended intervals, spanning weeks or months. This approach leverages longer intervals to adapt the treatment plan based on tumor changes and enhance immune-modulated effects. In this investigation, we seek to elucidate the potential synergy between combined PULSAR and PD-L1 blockade immunotherapy using experimental data from a Lewis Lung Carcinoma (LLC) syngeneic murine cancer model. Employing a long short-term memory (LSTM) recurrent neural network (RNN) model, we simulated the treatment response by treating irradiation and anti-PD-L1 as external stimuli occurring in a temporal sequence. Our findings demonstrate that: (1) The model can simulate tumor growth by integrating various parameters such as timing and dose, and (2) The model provides mechanistic interpretations of a “causal relationship” in combined treatment, offering a completely novel perspective. The model can be utilized for in-silico modeling, facilitating exploration of innovative treatment combinations to optimize therapeutic outcomes. Advanced modeling techniques, coupled with additional efforts in biomarker identification, may deepen our understanding of the biological mechanisms underlying the combined treatment.

IL-18-secreting multiantigen targeting CAR T cells eliminate antigen-low myeloma in an immunocompetent mouse model

AbstractMultiple myeloma is a plasma cell malignancy that is currently incurable with conventional therapies. Following the success of CD19-targeted chimeric antigen receptor (CAR) T cells in leukemia and lymphoma, CAR T cells targeting B-cell maturation antigen (BCMA) more recently demonstrated impressive activity in relapsed and refractory myeloma patients. However, BCMA-directed therapy can fail due to weak expression of BCMA on myeloma cells, suggesting that novel approaches to better address this antigen-low disease may improve patient outcomes. We hypothesized that engineered secretion of the proinflammatory cytokine interleukin-18 (IL-18) and multiantigen targeting could improve CAR T-cell activity against BCMA-low myeloma. In a syngeneic murine model of myeloma, CAR T cells targeting the myeloma-associated antigens BCMA and B-cell activating factor receptor (BAFF-R) failed to eliminate myeloma when these antigens were weakly expressed, whereas IL-18–secreting CAR T cells targeting these antigens promoted myeloma clearance. IL-18-secreting CAR T cells developed an effector-like T-cell phenotype, promoted interferon-gamma production, reprogrammed the myeloma bone marrow microenvironment through type-I/II interferon signaling, and activated macrophages to mediate antimyeloma activity. Simultaneous targeting of weakly-expressed BCMA and BAFF-R with dual-CAR T cells enhanced T-cell:target-cell avidity, increased overall CAR signal strength, and stimulated antimyeloma activity. Dual-antigen targeting augmented CAR T-cell secretion of engineered IL-18 and facilitated elimination of larger myeloma burdens in vivo. Our results demonstrate that combination of engineered IL-18 secretion and multiantigen targeting can eliminate myeloma with weak antigen expression through distinct mechanisms.

Abstract LB075: Small molecule procaspase activating compound 1 (PAC-1) enhances CAR-T immunotherapy for solid tumors in syngeneic murine models

Abstract Chimeric antigen receptor (CAR)-T cell therapy has been shown to effectively treat solid tumors in syngeneic murine models, but antigen loss and T cell trafficking into the tumors pose major obstacles to its long-term efficacy. Here we explored a combination therapy against advanced stages of colorectal and ovarian syngeneic murine tumor models using a tumor-specific small molecule (PAC-1) that triggers the engagement of the host immune system and synergizes with a Tn-specific adoptively transferred 237 CAR-T immunotherapy. PAC-1 has been shown to induce apoptosis in tumor cells with high expression of procaspase 3, via chelation of inhibitory zinc and release of active executioner caspase 3. PAC-1 also recently completed a phase I trial (NCT02355535) and was shown to be well-tolerated in late-stage cancer patients. RNA sequencing of CT26 colorectal cells stimulated with PAC-1 for 24 hours revealed that PAC-1 induced global changes at the transcriptome level, up-regulating genes involved in immune activation and apoptosis, and down-regulating genes involved in DNA repair, cell cycle regulation, and myc-driven proliferation. Validation of RNAseq data was performed using a combination of RT-qPCR, Western blot, flow cytometry, and co-culture studies. A combination of transcriptome and exome sequencing analyses in murine colorectal cell line CT26 revealed that the PAC-1-mediated down-regulation of DNA repair machinery led to somatic alterations in the genome and a higher mutational load in tumor cells, subsequently presented as neo-antigens by antigen-presenting cells. As a result, host CD8+ cytotoxic T cells were able to infiltrate tumors and reduce the tumor burden. Tn-dependent CARs have been used recently to demonstrate the proof of concept in the targeting of cancer-specific Tn-antigens such as the Tn-MUC1 antigen in humans, and an analogous Tn-OTS8 target in mice. In our murine ID8 ovarian tumor model, untreated mice with disseminated tumors have a median survival of 71 days. As a single agent administered intraperitoneally, PAC-1 extended the median survival to 90 days (p&amp;lt;0.0001), while 237 CAR-T treated mice have a median survival of 103 days (p&amp;lt;0.0001). A combination of the two treatment modalities (PAC-1 administered before 237 CAR-T) further extended the median survival to 145 days (p=0.048). Administering PAC-1 after 237 CAR-T also modestly extended the median survival to 132 days (p=0.06). Taken altogether, our results demonstrate that PAC-1 engages the immune system to treat cancer by inducing expression of pro-inflammatory cytokines in tumor cells allowing the recruitment of CD8+ effector T cells to the tumor microenvironment. Combination strategies that boost T cell trafficking shows great promise to enhance the anti-tumor efficacy and feasibility of adoptive CAR-T therapy against solid tumors. Citation Format: Diana R. Ranoa, Yifei Kang, Jenny Drnevich, Gloria Rendon, Christopher J. Fields, Keith Bailey, Edward J. Roy, Timothy M. Fan, David M. Kranz, Paul J. Hergenrother. Small molecule procaspase activating compound 1 (PAC-1) enhances CAR-T immunotherapy for solid tumors in syngeneic murine models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB075.

Abstract LB218: Advanced ex vivo platform for drug response analysis: Evaluating the potent effects of NMC-521 mAb on mouse-and patient-derived organotypic tumor spheroids

Abstract In response to the high failure rate of new drugs in clinical trials, we have developed an innovative organotypic tumor spheroids platform, designed to mitigate the risks associated with advancing drugs to clinical stages. Utilizing patient-derived organotypic tumor spheroids (PDOTS), this platform uniquely captures both the phenotype and genotype of individual patient tumor microenvironments. This approach not only enhances the precision of preclinical models but also bridges the gap between laboratory research and clinical applicability. In this study, we assess the effectiveness of the first-in-class monoclonal antibody NMC-521 (NomoCan Pharmaceuticals, NY) using our ex vivo platform. Targeting the novel cancer-specific antigen NMC-1, NMC-521 exhibited significant growth inhibition of CT-26 tumors in syngeneic BALB/c mice, reducing tumor size by approximately 55% compared to the control. Similarly, in ex vivo settings with freshly excised CT-26 tumors (n=18), NMC-521 demonstrated a dose-dependent cytotoxic effect, achieving about a 65% reduction in tumor viability with an effective dose (ED50) of 10 µg/ml. Further insights were gained into NMC-521's mechanism of action using our ex vivo platform. The drug’s ability to induce tumor cell death in CT26 ex vivo was significantly reversed (p&amp;lt;0.01) when co-treated with α-NKG2D but not α-CD8, indicating a critical role for natural killer (NK) cells in its therapeutic effect. Complementing these findings, our analyses on freshly excised patient tumors (n=15) corroborated the cytotoxic effects of this drug on colorectal cancer but not to the same magnitude as in the CT-26 model. Furthermore, unlike the syngeneic murine tumor model, the response rate was (8 of 15 responsive patient tumors. Gene expression profiling indicated that NK cell-associated RNAs were elevated in NMC-521 treated PDOTS. Additionally, combination therapy studies using NMC-521 and nivolumab within our platform mirrored murine in vivo results, enhancing our understanding of the drug's potential in clinical settings. Intriguingly, an observed elevation in IL-15 levels in patient tumors treated with NMC-521 suggests an increased presence of NK cell activity when compared to treatments with nivolumab. This research underscores the potential of our organotypic tumor spheroids platform as a transformative tool in cancer drug development, offering an accurate and patient-specific method to evaluate new therapies, thereby increasing the likelihood of successful translation from the laboratory to patient care. Citation Format: Amir Aref, Alyssa Martin, Hamidreza Aboulkheyr Es, Patryk Krzesaj, Victor Adler, Kirti Khardenavis, Ehsan Sarafraz-Yazdi, Michael A. Perricone. Advanced ex vivo platform for drug response analysis: Evaluating the potent effects of NMC-521 mAb on mouse-and patient-derived organotypic tumor spheroids [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB218.

235 IL-4/13 Blocking Peptide (KROS-401) Inhibits M2 Macrophage Polarization in vitro and Demonstrates Anti-tumor Activity in a Murine Model of Glioblastoma

INTRODUCTION: Glioblastoma (GBM) is the most aggressive primary brain malignancy with a median survival of 14 months. Tumor-associated macrophages (TAMs) comprise up to 40% of the GBM tumor mass and are significant enablers of an immunosuppressive tumor microenvironment (TME), limiting immunotherapeutic efficacy. TAMs are generally classified as M2 macrophages that demonstrate a pro-tumor phenotype and increased CD206 surface marker expression. Reducing the M2 macrophage population in tumors has shown benefit in preclinical studies across various cancers. Interleukins (IL)-4 and -13 both play a role in polarizing macrophages to an M2 state. We developed a peptide inhibitor (KROS-401) that targets the shared IL-4Ra subunit of the IL-4 and -13 receptor complex to inhibit macrophage polarization to an M2 phenotype and reprogram the immunosuppressive TME. METHODS: Human peripheral blood mononuclear cell (PBMC)-derived macrophages were isolated and treated with KROS-401 in the presence of IL-4 and IL-13 cytokines. M2 (CD206) surface markers were assessed by flow cytometry. The efficacy of KROS-401 peptide was examined using an intracranially implanted syngeneic murine model with luciferase-expressing GL261, a glioma cell line. Mice were inspected daily for survival and tumor growth was tracked by non-invasive in vivo bioluminescent imaging (BLI). RESULTS: Human PBMC-derived macrophages treated with KROS-401 displayed a dose-dependent decrease in M2 (CD206) cell surface markers. KROS-401 peptide inhibitor demonstrated anti-tumor activity in GL261 glioma-bearing mice with a significantly increased probability of survival compared to control (p = 0.0046) with a median survival of &gt;40 days versus 27 days, respectively. CONCLUSIONS: KROS-401 inhibits M2 polarization of human macrophages in vitro and tumor growth in vivo. These findings highlight this IL-4/IL-13 peptide inhibitor as a potential immunomodulator of the TME for the treatment of GBM.

Focused ultrasound-mediated blood–brain barrier opening is safe and feasible with moderately hypofractionated radiotherapy for brainstem diffuse midline glioma

BackgroundDiffuse midline glioma (DMG) is a pediatric tumor with dismal prognosis. Systemic strategies have been unsuccessful and radiotherapy (RT) remains the standard-of-care. A central impediment to treatment is the blood–brain barrier (BBB), which precludes drug delivery to the central nervous system (CNS). Focused ultrasound (FUS) with microbubbles can transiently and non-invasively disrupt the BBB to enhance drug delivery. This study aimed to determine the feasibility of brainstem FUS in combination with clinical doses of RT. We hypothesized that FUS-mediated BBB-opening (BBBO) is safe and feasible with 39 Gy RT.MethodsTo establish a safety timeline, we administered FUS to the brainstem of non-tumor bearing mice concurrent with or adjuvant to RT; our findings were validated in a syngeneic brainstem murine model of DMG receiving repeated sonication concurrent with RT. The brainstems of male B6 (Cg)-Tyrc-2J/J albino mice were intracranially injected with mouse DMG cells (PDGFB+, H3.3K27M, p53−/−). A clinical RT dose of 39 Gy in 13 fractions (39 Gy/13fx) was delivered using the Small Animal Radiation Research Platform (SARRP) or XRAD-320 irradiator. FUS was administered via a 0.5 MHz transducer, with BBBO and tumor volume monitored by magnetic resonance imaging (MRI).ResultsFUS-mediated BBBO did not affect cardiorespiratory rate, motor function, or tissue integrity in non-tumor bearing mice receiving RT. Tumor-bearing mice tolerated repeated brainstem BBBO concurrent with RT. 39 Gy/13fx offered local control, though disease progression occurred 3–4 weeks post-RT.ConclusionRepeated FUS-mediated BBBO is safe and feasible concurrent with RT. In our syngeneic DMG murine model, progression occurs, serving as an ideal model for future combination testing with RT and FUS-mediated drug delivery.

Abstract 1831: Reduction of PMN-MDSC level/activity following the consumption of white button mushroom in prostate cancer murine models and patients: A translational study to mitigate cancer progression

Abstract Frequent consumption of edible mushrooms, such as white button mushrooms (WBM), has been associated with a lower risk of prostate cancer [1]. Our laboratory at City of Hope has over 20 years of collective experience in defining the anticancer mechanisms of WBM [2, 3]. Previous studies have indicated that WBM consumption has anti-androgenic activities in prostate cancers in both preclinical models [4] and clinical trials [5]. In our first-in-human phase 1 trial on prostate cancer patients, we ensured the safety of consuming WBM in humans. In addition to observing a therapeutic-responsive decline in prostate-specific antigen (PSA), the levels of myeloid-derived suppressor cells (MDSCs) reduced in responders to WBM treatments [5]. These observations led us to hypothesize that WBM may mitigate the progression of prostate cancer in part by modulating the immune response. In the current study, we conducted translational research in syngeneic murine models and in prostate cancer patients from an ongoing phase 2 trial, aiming to define the immunomodulatory activity and mechanisms of WBM. We confirmed that WBM consumption in mouse models altered the number and function of immunosuppressive cells (MDSCs) and anti-tumor immune cells (T &amp; NK cells), ultimately enhancing the intratumor and systemic immune responses. At a bulk-transcriptional level, we observed the elevated expression of programmed cell death protein 1 (PD-1) in xenograft tumors. In our single immune cell profiling of patients’ blood specimens following 3 months of WBM consumption in freeze-dried tablets form, we investigated the transcriptional landscape of circulating immune cells in response to WBM interventions. The level of circulating neutrophil-associated PMN-MDSCs decreased, and the remaining cells showed transcriptional profiles associated with "neutrophil chemotaxis", "leukocyte aggregation", and "regulation of inflammatory response", as functions associated with enhanced anti-tumor activity. Lastly, we also showed in a mouse model that WBM consumption synergistically enhances the anticancer activity of anti-PD1 drugs, indicating that WBM may be used as adjuvant therapy with immune checkpoint inhibitors. In summary, our results from prostate cancer patients and murine models show the immunomodulatory effects of WBM consumption and provide a scientific foundation for the application of WBM in alleviating prostate cancer progression. References 1, Zhang S., et al. Int. J. Cancer. 2019; 146:2712-2720. 2, Chen S., et al. Cancer Res. 2006; 66:12026-12034. 3, Adams L.S., et al. Nutr. Cancer. 2008; 60:744-756. 4, Wang X., et al. J. Nutr. Biochem. 2021; 89:108580.5, Twardowski P., et al. Cancer. 2015; 121:2942-2950. Citation Format: Xiaoqiang Wang, Shoubao Ma, Przemyslaw Twardowski, Clayton Lau, Yin Chan, Kelly Wong, Jinhui Wang, Xiwei Wu, Paul Frankel, Timothy G. Wilson, Timothy W. Synold, Cary Presant, Jianhua Yu, Shiuan Chen. Reduction of PMN-MDSC level/activity following the consumption of white button mushroom in prostate cancer murine models and patients: A translational study to mitigate cancer progression [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 1831.

Abstract 4273: Genetically engineered mesenchymal stromal cells degrade hyaluronic acid to disrupt the ECM and enhance cancer therapy outcomes

Abstract The extracellular matrix (ECM) is a vital component of cancer pathophysiology. However, little is known about how to modulate the ECM for therapeutic benefit effectively. Hyaluronic acid (HA) is a polysaccharide component of the ECM with increased deposition during tissue injury or inflammation. HA in the tumor microenvironment (TME) has been linked to aggressive cancer progression. We have found enhanced ECM remodeling behavior linked to pre-metastatic niche formation and metastatic progression. To remodel this ECM-enriched microenvironment, we developed HA-targeting genetically engineered mesenchymal stromal cells (GEMesys) expressing hyaluronidase (Hyal), the enzyme responsible for HA degradation. We examined the impact of Hyal-GEMesys in osteosarcoma (F42010), rhabdomyosarcoma (M-3-9M), and pancreatic cancer (Panc02) syngeneic murine models. Hyal-GEMesys delivered to tumor-bearing mice homed to primary tumor sites and successfully degraded HA in the TME. The degradation of HA also resulted in a significant remodeling of collagen. T cells in Hyal-GEMesy treated tumors display an activated CD4+CD44+ phenotype with a reduction of LAG3+PD1+ exhaustion markers. Additionally, Hyal-GEMesy treatment results in a significant decrease in hypoxic regions within tumors and reorganization of the tumor vasculature to a more normalized phenotype, marked by diminished CD31 expression. Hyal-GEMesy treatment reduces tumor volumes in osteosarcoma, rhabdomyosarcoma, and pancreatic cancer models and enhances chemotherapeutic efficacy. These findings suggest that reorganizing the tumor ECM with Hyal-GEMesys holds the potential to dismantle the protective stroma of the tumor, which often shields malignant cells from therapeutic reach, and combining anti-cancer and anti-stroma agents can enhance anti-tumor efficacy and patient outcomes. Citation Format: Alice T. Browne, Miranda Clements, Wei Ju, Rosandra Kaplan. Genetically engineered mesenchymal stromal cells degrade hyaluronic acid to disrupt the ECM and enhance cancer therapy outcomes [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 4273.

Abstract 5368: Targeting tumor-intrinsic S100A1 augments antitumour immunity and potentiates anti-PD-1 efficacy

Abstract Immune-checkpoint blockade (ICB) has revolutionized cancer treatment. However, only a minority of patients achieve the long-term, durable response to ICB, and the response rates in most advanced tumors is limited to 10%-25%. The unsatisfactory overall response to ICB and the great variation in response among individuals highlight the necessity for developing predictive biomarkers and overcoming ICB resistance. A potential mode of resistance is tumor-mediated immunosuppression leading to inhibition of T cell-mediated infiltration and immunity. Here, combining single-cell and bulk transcriptomic analysis with liquid biopsy of tumor patients, we showed that S100 calcium binding protein A1 (S100A1) was closely related to ICB response, and that detecting plasma S100A1 level could help predicting the response to ICB, implying that tumor-intrinsic S100A1 may contribute to immunosuppressive tumor microenvironment (TME) and resistance to ICB. Importantly, endogenous S100a1 knockdown (S100a1KD) promoted anti-tumor immunity, conferred tumor regression, and sensitized tumors to anti-PD-1 immunotherapy in multiple syngeneic murine models. By characterizing the immune landscape of S100a1KD syngeneic murine tumor models and non-small cell lung cancer (NSCLC) clinical samples, we demonstrated a negative relationship between tumor-intrinsic S100A1 expression and infiltration of M1-like macrophage and CD8+ T cells. Single cell and spatial transcriptomic analyses, together with functional studies, have revealed that ablation of tumor-intrinsic S100A1 exerts profound impacts on the M1-like polarization of macrophages and cytotoxicity of CD8+ T cells. Moreover, the conditioned medium from S100a1KD tumor cells promoted M1 polarization of both bone marrow-derived macrophages (BMDMs) and Raw264.7 cells, which in turn reinvigorated tumor-specific T cell immunity both in vitro and in vivo. Of note, as a secreted protein, introducing recombinant S100A1 into the medium from S100a1KD tumor cells could not reverse the effects on T cells and macrophages, suggesting that these effects were independent of extracelluar S100A1 secretion and that S100A1 may act as an intracellular signaling molecule. Mechanistically, S100A1 affects deubiquitination of NF-κB through interacting with the ubiquitin-like (Ubl) domains of ubiquitin specific protease 7 (USP7), leading to upregulated granulocyte-macrophage colony-stimulating factor (GM-CSF) expression. Collectively, these data identified the S100A1/USP7/p65/GM-CSF inhibitory axis as a critical immune suppressor on M1-like macrophage polarization and T cell immunity for the promotion of tumor progression and resistance to ICB. Our findings demonstrated the potential of plasma S100A1 expression in predicting the response to ICB, and provide a rationale for combining GM-CSF and anti-PD-1 immunotherapy in tumors with high S100A1 expression. Citation Format: Yufeng Guo, Hua Bai, Jie Wang. Targeting tumor-intrinsic S100A1 augments antitumour immunity and potentiates anti-PD-1 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 5368.

Abstract 6748: Intramuscular delivery of tumor associated antigen DNA vaccines elicits strong cellular immune response, delays tumor growth and prolongs survival

Abstract The development of effective cancer vaccines that can trigger strong and enduring memory T cell responses against specific tumor associated antigens (TAAs) is crucial for advancing immunotherapy. DNA-based cancer vaccines have shown promise in generating precise and long-lasting immune responses. In particular DNA vaccines are capable of inducing both humoral and cellular immune responses. In this study, we aimed to investigate the effectiveness of DNA vaccines targeting the mouse Tyrosine-related protein-2 (Trp2) and human New York esophageal squamous cell carcinoma 1 (NY-ESO-1) TAAs in mouse melanoma model. These DNA vaccines were formulated with a functionalized polymer designed to protect DNA from degradation and improve its bioavailability. DNA vaccines targeting both mouse Trp2 (pVACTR) and human NYESO-1 (pVACNY) were constructed. A mouse melanoma cell line (B16F10-NY) overexpressing human NYESO-1 was also generated and demonstrated to induce tumors in C57BL/6 mice. Female C57BL/6 mice received two doses of intramuscular (i.m.) injection of formulated pVACTR or pVACNY or a combination thereof, formulated with the synthetic functionalized polymer, with a 3-week interval. The DNA vaccination induced a potent T cell response, as evidenced by ELISPOT assays showing strong IFN-γ secreting T cells against NYESO-1 and Trp2. Flow cytometry analysis of spleenocytes showed strong IFN-γ and TNF-α secreting CD4 T cells against NYESO-1. We further evaluated the prophylactic and therapeutic efficacy of DNA vaccines targeting both Trp2 and NYESO-1 using a murine syngeneic model. Animals were challenged with a lethal dose of B16F10-NY two weeks after the second immunization exhibited a significant (p&amp;lt;0.0001) delay in tumor progression and a substantial increase in survival compared to the mock control group. In the therapeutic testing, animals challenged with B16F10-NY and subsequently vaccinated at 4, 11, and 25 days also demonstrated delayed tumor growth and prolonged survival. These findings indicate that formulated DNA vaccine delivered via i.m. triggers robust T cell responses and exhibit both prophylactic and therapeutic efficacy, leading to significantly prolonged survival and delayed tumor growth. A DNA-based vaccine independent of viral vector or device has potential to elicit potent anti-tumor responses with better safety and compliance. Citation Format: Kempaiah Rayavara, John Henderson, Meredyth Kinsella, Jessica Kim, Majed Matar, Subeena Sood, Olivia Signer, Chelsey Bellmon, Corinne Le Goff, Khursheed Anwer, Jean Boyer. Intramuscular delivery of tumor associated antigen DNA vaccines elicits strong cellular immune response, delays tumor growth and prolongs survival [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 6748.

Abstract 2: T cells selected from lymph node acquisition for adoptive cell therapyin NSCLC

Abstract Background: A primary limitation of PD-1 inhibitors in non-small cell lung cancer (NSCLC) arises from their inability to act on 'cold' tumors without tumor-reactive T cells, necessitating alternative approaches. Adoptive cell therapy (ACT) using (CAR)-engineered cells, strives to enhance antitumor immunity but faces several challenges such as identifying safe antigens, tumor heterogeneity, antigen escape, cell trafficking, and T cell persistence. To address these issues, we explored a new source of T cells from the benign tumor draining lymph nodes (tdLNs) of NSCLC patients. Our initial results have shown that tdLNs is a reservoir for of tumor-relevant 'stem-like' T cells. We posit that employing these pluripotent T cells for ACT could achieve significant tumor rejection in NSCLC. Methods: Resected tumors, tdLN, non-draining (ndLN), and blood from NSCLC patients, as well as a syngeneic murine lung cancer model (344SQ), underwent analysis. T cells were profiled using flow cytometry, cytotoxicity and proliferation assays. TCR and single cell (sc)RNA sequencing assessed clonal expansion, diversity, and transcriptional profiles of tumor-relevant T cells. T cells were then transduced with an ICAM-1 targeting CAR, in vivo efficacy was evaluated in an A549 murine lung cancer model. Results: T cell subsets with stem-cell memory characteristics, as indicated by PD-1+, TCF1hi, CXCR5+, and CD8+ expression, which were not significantly found in the tumor or PB. These T cells exhibited progenitor-like transcriptional signatures, enhanced SELL and TCF-1 expression, fewer exhaustion markers, and superior in vitro proliferation compared to TILs from both a murine lung cancer model and patient-derived tissues. scRNA sequencing, coupled with TCR "tumor matching" (TM) techniques, exposed a rich clonal diversity of tumor-relevant clones within tdLNs, which showcased a broader transcriptional memory profile and distinct CD4+ and CD8+ phenotypes. Upon analyzing the top 100 expanded (n&amp;gt;3) TM clones, 47 featured the presence of tdLN-derived T cells, covering progenitor, stem cell-like, and central memory clusters. T cell subsets were then transduced with a CAR targeting ICAM-1—a cell surface protein frequently overexpressed in NSCLC tumors. Manufacturing protocol yielded high transduction efficiency and T cell expansion within two weeks in 6/6 patients, consistent with PB-derived CAR T cells and on par with the optimal dosing requirements of an ICAM-1 CAR Phase I trial (NCT04420754). tdLN-CAR T cells showed potent antitumor efficacy compared to the control in an aggressive NSCLC murine model (Median survival 103d vs 66d; respectively; p=0.006). Conclusions: This represents the first reported use of T cells from tdLN for genetically engineered ACT. The data indicate that modifying antigen-experienced, stem-like T cells from tdLN with CAR is a promising and efficient method in a NSCLC murine model, warranting further research. Citation Format: Tatiana Delgado Cruz, Yanping Yang, Rachel Honigsberg, Geoffrey Markowitz, Nasser K Altorki, Vivek Mittal, Moonsoo M. Jin, Jonathan Villena-Vargas. T cells selected from lymph node acquisition for adoptive cell therapyin 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 2.

Abstract 5935: Non-allosteric inhibition of enolase 1 sensitizes triple-negative breast cancer for checkpoint inhibitors

Abstract Background: Triple-negative breast cancer (TNBC) is an aggressive type of breast cancer that commonly returns and spreads. Currently, very few options are available for TNBC treatment. Cancer cells exploit glycolytic machinery for the Warburg effect and aerobic glycolysis. Enolase 1 (ENO1) is the glycolytic enzyme expressed in most tissues, and many cancer cells have higher expression. Apart from the glycolytic role in the cytosol, ENO1 also plays different roles in cancer cells, including as a surface receptor. Method: non-allosteric chemical inhibition was developed and tested in vitro for its efficacy and target validation. Subsequently, in vivo examinations were conducted on emerging small molecules in syngeneic and patient-derived murine models of breast cancer to unveil their anti-tumor efficacy. Results: Our non-allosteric small molecule inhibitor, SU212, binds to ENO1 and restricts its movement within cells. SU212 treatment leads to the accumulation of ENO1 in the nucleus where it restrains the activity of c-Myc. The treatment causes the production of truncated ENO1 called myc promoter-binding protein 1 (MBP-1), which limits the activity of c-Myc. Stand-alone treatment of SU212 restrains the tumor progression and metastasis in orthotopic syngeneic and PDX mouse models. Combining SU212 and Anti-PD1 significantly inhibits tumor growth and metastasis in mouse models. C-Myc is linked to protein transcription that aids immune resistance and tumor evasion of immune surveillance. Suppression of c-Myc activity via SU212 treatment sensitizes the TNBC tumors for anti-PD1 therapy. Conclusions: This study provides compelling preclinical data for further development of SU0212 as an immune therapy sensitizer for the treatment of TNBC. Citation Format: Dhanir Tailor, Fernando Jose Garcia-Marques, Abel Bermudez, Wenqi Li, Arpit Dheeraj, Sharon J. Pitteri, Sanjay V. Malhotra. Non-allosteric inhibition of enolase 1 sensitizes triple-negative breast cancer for checkpoint inhibitors [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 5935.

Abstract 3967: ISM9182A, a novel HPK1 inhibitor, exhibits immune modulatory activity and robust monotherapy anti-tumor effects in preclinical studies

Abstract The hematopoietic progenitor kinase 1 (HPK1 or MAP4K1) is a member of the Ste20 serine/threonine kinase super family that negatively regulates immune cells, including T cells, B cells and dendritic cells (DCs). Thus HPK1 is an attractive immuno-oncology target in many tumor types. Here, we report ISM9182A as a novel, potent, and selective inhibitor of HPK1.ISM9182A demonstrated nanomolar enzymatic potency against HPK1 with &amp;gt;100-fold selectivity against other MAP4K family kinases. ISM9182A inhibited the phosphorylation of SLP-76 at Ser376 dose-dependently with an IC50 of 30nM in human peripheral blood mononuclear cells. Moreover, ISM9182A enhanced IL-2 and IFNγ secretion upon CD3/CD28 co-stimulation in a dose-dependent manner without affecting T cell proliferation. Treatment of human pan T cells with ISM9182A also significantly reversed PGE2-mediated immunosuppression of human pan T cell activation and further boosted IL-2 and IFNγ secretion compared to CD3/CD28 co-stimulation. In monocyte-derived DCs stimulated with TNF-α/IL-1β/PGE-2, ISM9182A significantly upregulated CD80, CD86, and CD83 expression, demonstrating its potency to promote DC maturation. ISM9182A showed no obvious toxicity towards human T cell, B cells, and monocytes without CD3/CD28 co-stimulation. In vivo PK data revealed favorable ADME properties and good oral bioavailability of ISM9182A across different species. In a CT-26 murine syngeneic mouse model, oral administration of ISM9182A exhibited potent antitumor effects with p-SLP76 inhibition in both murine spleen and tumor, without body weight loss. In summary, ISM9182A is a potent and selective HPK1 inhibitor and a promising immuno-oncology agent. Citation Format: Celia X.-J. Chen, Congying Pu, Jingjing Peng, Xiaoyu Ding, Hongfu Lu, Xiao Ding, Man Zhang, Supriya Bavadekar, Sujata Rao, Feng Ren, Alex Zhavoronkov. ISM9182A, a novel HPK1 inhibitor, exhibits immune modulatory activity and robust monotherapy anti-tumor effects in preclinical studies [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 3967.

Abstract 1350: KD6001: A promising new anti-CTLA-4 human monoclonal antibody for cancer therapy

Abstract Cytotoxic T lymphocyte antigen-4 (CTLA-4) is a crucial immune checkpoint that negatively regulates T cell activation. Inhibiting this negative regulation through CTLA-4 blockade has emerged as a promising therapeutic strategy against cancer. Herein, we present the preclinical pharmacology study of KD6001, a novel anti-CTLA-4 IgG1 kappa human monoclonal antibody with superior properties compared to ipilimumab, a currently approved anti-CTLA-4 mAb. Surface plasmon resonance (SPR) analysis revealed that KD6001 exhibits a higher affinity for CTLA-4 compared to ipilimumab (KD = 0.57 nM vs 1.20 nM). Competition ELISA experiments demonstrated that KD6001 is significantly more potent than ipilimumab in disrupting CTLA-4 interactions with CD80 (IC50 = 16 ng/mL vs 93 ng/mL) and CD86. Further, amino acid point mutation analysis indicated that two specific residues following the CD80/CD86 binding site (99MYPPPY104) are critical for ipilimumab binding, whereas mutation of the two residues had minimal impact on KD6001's CTLA-4 binding activity. These findings suggest that KD6001 and ipilimumab bind distinct epitopes on CTLA-4. In vitro experiments demonstrated that KD6001 enhances the production of IL-2 and IFNγ in PHA-activated human lymphocytes and exhibits synergistic anti-tumor effects when combined with anti-PD-1/L1 antibodies. Moreover, in vivo studies utilizing syngeneic murine tumor models established in human CTLA-4 gene knock-in mice revealed that KD6001 effectively inhibits or delays tumor growth in colon cancer MC38, melanoma B16, and hepatocellular carcinoma Hepa1-6 models. Additionally, KD6001 demonstrated synergistic anti-tumor effects when combined with a mouse anti-PD-1 antibody or ibuprofen. Toxicity evaluation in cynomolgus monkeys revealed that KD6001 was generally well-tolerated at doses ranging from 1 mg/kg to 10 mg/kg administered intravenously once weekly for four weeks. The primary pathological changes observed were lymphocyte/monocyte infiltration or increased lymphocyte/monocyte infiltration in several organs, consistent with KD6001's mechanism of action. Notably, the similar affinity of KD6001 for human and cynomolgus monkey CTLA-4 suggests that the toxicity profile observed in monkeys accurately reflects the dose-toxicity relationship in human. The promising preclinical data presented herein support the further clinical development of KD6001 as a potential therapeutic agent for cancer treatment. Currently, clinical trials evaluating KD6001 in patients with advanced melanoma are ongoing. Citation Format: Yi Chen, Peng Li, Guobo Fang, Heng Wu, Chi Zhang, Zeling Cai. KD6001: A promising new anti-CTLA-4 human monoclonal antibody for cancer therapy [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 1350.

Abstract 5562: Altered tumor microenvironment in animal model of concomitant GBM and Alzheimer's pathology

Abstract Glioblastoma (GBM) and Alzheimer’s disease (AD) are two devastating central nervous system diagnoses with no known cure. Both diseases are associated with advanced age. The majority of GBM tumors form in the frontal and temporal lobes, two of the brain regions most impacted by amyloid and tau pathology in AD. Females have a higher risk of AD, while males have a higher risk of GBM. Several large case series have established epidemiological evidence that the two diseases are inversely correlated. Nevertheless, it remains unknown whether presence of subclinical amyloid or tau pathology antagonizes the establishment or progression of GBM. The present study sought to characterize GBM growth, progression, and immune response in the setting of concomitant AD pathology using the syngeneic murine GL261 tumor model. To further understand the tumor cell changes that occur in the presence or absence of AD pathology, we engineered GL261 with a dual-tagged vector consisting of RiboTag (to allow for full-length mRNA profiling) and TurboID (to allow for proteomic profiling). GL261 cells were injected intracranially into APPNL-G-F/NL-G-F - MAPThuman/human, APPNL-G-F/+ - MAPThuman/+, and wildtype C57BL/6J mice. Tumors in both wildtype and AD conditions contained ~50% intratumoral myeloid cells (Iba+, P2RY12-). Differential activation of intratumoral myeloid cells will be assessed with immunohistochemistry. Microgliosis (IBA1, P2RY12) and astrogliosis (GFAP) around the tumor in the setting of Alzheimer’s pathology versus normal conditions will be compared. Invasiveness, proliferation, DNA damage (pH2AX), and apoptosis (cleaved PARP, cleaved Caspase 3) will be compared. Tumor cell-specific changes unique to tumors in the AD microenvironment will be assessed transcriptionally with RiboTag profiling as well as proteomically with TurboID purifications. Our preliminary data suggests that the presence of concomitant AD pathology affects GBM growth and progression as well as the immune response to the tumor, and warrants further investigation. Citation Format: David Nascari, Ryan Eghlimi, Angad Beniwal, Drake Alton, John Fryer, Nhan L. Tran. Altered tumor microenvironment in animal model of concomitant GBM and Alzheimer's pathology [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 5562.

Abstract 4069: IL12-expressing genetically engineered myeloid cells remodel the stromal dense and T cell poor tumor microenvironment and premetastatic niche of F42010 murine osteosarcoma

Abstract Treatment options for patients with metastatic and recurrent osteosarcoma are poor. The development of immunotherapies for osteosarcoma has been hindered by the lack of immunocompetent preclinical models that recapitulate the stromal dense, myeloid-rich, T cell poor, and overall immunosuppressive microenvironment of human osteosarcoma. We hypothesized that the syngeneic murine osteosarcoma model F42010 may serve as a useful immunocompetent preclinical model of osteosarcoma suitable for developing novel immunotherapies for osteosarcoma. To test this, we used flow cytommetry, bulk RNA sequencing, and immunohistochemistry to characterize the stromal and immune compartments of this model. We found that the F42010 osteosarcoma model recapitulates the ECM-rich and immunosuppressive nature of human osteosarcoma primary tumor and pre-metastatic microenvironments, characterized by increased myeloid infiltrate expressing suppressive markers and lymphocyte exhaustion. Finally, we used this model to test the utility of a myeloid immunotherapy for osteosarcoma, IL-12 secreting genetically engineered myeloid cells (IL12-GEMys) that can reverse immune suppression in the pre-metastatic niche and tumor microenvironment. IL12-GEMy treatment augmented immune activation and significantly extended survival by delaying tumor growth. Our findings highlight that the F42010 osteosarcoma model effectively replicates key features of the osteosarcoma tumor microenvironment and is a valuable model for developing novel tumor microenvironment and pre-metastatic niche modulating immunotherapies for osteosarcoma. Citation Format: Kailey Jackett, Alice Browne, Sabina Kaczanowska, Miranda Clements, Rosandra Kaplan, Kristin Wessel, Brendan Ball, James Cronk. IL12-expressing genetically engineered myeloid cells remodel the stromal dense and T cell poor tumor microenvironment and premetastatic niche of F42010 murine osteosarcoma [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 4069.

Abstract 3971: Progesterone impacts regulatory T cell activity to promote immunosuppression in the mammary gland

Abstract Estrogen and progesterone signaling together drive hormone-receptor positive breast cancer growth and progression. However, there have been limited studies on the independent role that progesterone and its receptor, the progesterone receptor (PR), play in the development of breast cancer. Studies in the Hagan lab have shown that progesterone signaling promotes mammary tumor growth and changes the immune landscape of the mammary gland towards immunosuppression. Regulatory T-cells (Tregs) are immune cells known to promote immunosuppression in the tumor microenvironment. The data from our lab shows that among hormone receptor positive breast cancers, higher levels of PR expression correlates to higher levels of Tregs in the tumor microenvironment. To determine if progesterone signaling increases the number of Tregs in the tumor-bearing mammary gland, we used a syngeneic orthotopic murine tumor model, E0771 cells, engineered to express mouse PR or control empty vector. Mice were treated with progesterone or placebo for 7 days before implantation of the modified E0771 cells. The results of this study show that progesterone promoted tumor growth, and flow cytometry analysis at tumor endpoint showed that PR-positive tumors treated with progesterone harbored more Tregs than mice treated with placebo. Additionally, initial studies using flow cytometry and RNA-seq indicate increased Treg activity following progesterone treatment in PR+ tumor-bearing mice. As progesterone treatment promoted tumor growth and Treg recruitment in progesterone receptor-positive tumors, these data imply that progesterone treatment may promote the release of secreted factors impacting the immune cells in the mammary microenvironment. To determine if progesterone treatment results in cytokine or chemokine changes that may affect Treg recruitment, cytokine arrays and enzyme-linked immunosorbent assays (ELISAs) were performed using cell culture supernatant from murine mammary tumor cells expressing progesterone receptor (E0771-PR) treated with progesterone (0-72 hours). E0771-PR cells treated with progesterone showed higher levels of cytokines and chemokines that have been linked to Treg recruitment and differentiation, such as MCSF. Our findings demonstrate that progesterone signaling promotes an immune suppressed microenvironment in the mammary gland through an increase in Tregs. This evidence provides rationale to investigate the use of anti-progestins as a mechanism to overcome the immune-cold tumor microenvironment seen in progesterone receptor positive breast tumors. Citation Format: Eilidh I. Chowanec, Lauryn R. Werner, Christy R. Hagan. Progesterone impacts regulatory T cell activity to promote immunosuppression in the mammary gland [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 3971.

Abstract 6592: Deciphering the effects of age on T cell immunity and immunotherapy

Abstract Aging induces profound alterations in host biology and correlates with unfavorable clinical outcomes in age-related diseases such as cancer. While the pivotal role of the immune system in regulating tumor progression is well-acknowledged, the precise mechanisms through which aging influences anti-tumor T cell immunity and responsiveness to immune checkpoint blockade (ICB) remain elusive. In this study, we employed syngeneic murine tumor models (B16, MC38, and E0771) in young (2-4 months) and aged (20-24 months) cohorts to elucidate the early impacts of aging on tumor development and T cell responses. Our findings demonstrate that aged mice exhibit accelerated tumor growth across various models. In-depth analysis of tumor-infiltrating lymphocytes (TILs) uncovered distinct alterations in the CD8+ T cell population, characterized by decreased activation status and diminished tumor specificity in aged mice. Correspondingly, aged mice exhibited resistance to anti-PD-1 immunotherapy. To unravel the underlying environmental factors contributing to compromised anti-tumor T cell responses and ICB resistance, we characterized the immune and metabolic landscapes of the aged tumor-draining lymph nodes and tumors. Furthermore, we established a genetically engineered mouse model of lung adenocarcinoma in both young and aged mice, unveiling novel functions and mechanisms associated with age-related T cells actively impeding effective tumor control. In the context of increasing average life expectancy, comprehending the intricate interplay between age-related T cell dysfunction and cancer assumes paramount importance. Such insights hold the key to the development of innovative therapeutic strategies tailored for the growing population of older patients. Citation Format: SeongJun Han, Peter Georgiev, Jaime Schneider, Amy Huang, Zhanel Nugmanova, Thao H. Nguyen, Conghui Yao, Sheila Johnson, Shakchhi Joshi, Ishita Dhiman, Jefte M. Drijvers, Megan Fung, Jared H. Rowe, Brian C. Miller, Gordon J. Freeman, Alison E. Ringel, Marcia C. Haigis, Arlene H. Sharpe. Deciphering the effects of age on T cell immunity and 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 6592.