Orthotopic Pancreatic Cancer Model Research Articles

Abstract 3323: Novel Pan-RAS inhibitor ADT-007: A unique mechanism of antitumor selectivity in pancreatic and colorectal carcinoma models

Abstract Multiple types of RAS mutations activate RAS isoforms, HRAS, NRAS, or KRAS, that drive oncogenic signaling leading to uncontrolled cell proliferation and tumor development. RAS mutations occur de novo in approximately one-third of all human cancers, and are especially prevalent in pancreatic, colorectal, and lung tumors. Where RAS mutations are less frequent in other cancers, such as breast cancer, RAS can be pathologically activated by growth factor receptors that engage numerous downstream effectors. The currently FDA-approved KRAS-targeted drugs are designed to covalently inactivate only G12C KRAS mutants, however, this mutation is only prevalent in lung cancer. The most common mutations in pancreatic ductal adenocarcinoma (PDAC) are KRAS-G12D, KRAS-G12V, and KRAS-G12R. Our novel class of pan-RAS inhibitors, exemplified by ADT-007, addresses the urgent need for pan-RAS inhibitors with antitumor activity in cancers harboring these common mutations. These pan-RAS inhibitors have unique pharmacological properties that allow for selective killing of cancer cells harboring RAS mutations. ADT-007 inhibited growth of an array of carcinoma tumor cell lines in vitro with single digit nM IC50 values regardless of RAS mutant allele, and inhibited RAS activation and MAPK/AKT signaling. Because it is a pan-RAS inhibitor, ADT-007 may not be susceptible to commonly reported mechanisms of resistance to covalent KRAS inhibitors, such as activation of wild type (WT) alleles or secondary RAS mutations. Differentiated normal epithelial or hepatic cells, and tumor cells with WT RAS were insensitive to ADT-007 due to enzymatic detoxification of ADT-007 via glucuronidation, representing a novel mechanism of tumor selectivity. An orally bioavailable prodrug of ADT-007 (ADT-1004) is well tolerated in vivo, and produced sustained concentrations of ADT-007 well above IC50 values in plasma and even higher levels in tumors. Daily oral administration of ADT-1004 significantly inhibited RAS signaling and tumor growth in orthotopic and PDX mouse models of pancreatic cancer. Citation Format: Junwei Wang, Adam B. Keeton, Sindhu Ramesh, Peyton Johnson, Yulia Y. Maxuitenko, Jeremy B. Foote, Chung-Hui Huang, Kristy L. Berry, Khalda Fadlalla, Bandi D. Reddy, Ganji P. Nagaraju, Elmar Nurmemmedov, Ivan Babic, Vadim Gaponenko, Xi Chen, Bassel F. El-Rayes, Donald J. Buchsbaum, Gary A. Piazza. Novel Pan-RAS inhibitor ADT-007: A unique mechanism of antitumor selectivity in pancreatic and colorectal carcinoma models [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 3323.

Abstract 1598: Individualized longitudinal assessment reveals therapy-induced tumor and microenvironment dynamics in preclinical pancreatic cancer models

Abstract Background & Aim: Progression and therapeutic resistance in pancreatic cancer depends on the ability of cancer cells to adopt specific cell states. These phenotypes largely depend on environmental tissue niches. Here, we investigated therapy-induced tumor dynamics in vivo at single-cell spatial and temporal resolution in different subtypes of PDAC using several genetically engineered mouse models, which reflect distinct human PDAC ecosystems. Methods & Results: We established orthotopic tumor models of pancreatic cancer with distinct tumor microenvironment (TME) formation (reactive vs deserted stroma), which were monitored for tumor growth to define tumor response patterns under MAPK inhibition. Serial ultrasound-guided biopsy sampling was performed to collect tissues from the same tumors at pre-treatment, responsive and recurrence periods.Transcriptomic analysis of biopsies using the Mfuzz algorithm delineated highly dynamic gene and pathway activities during treatment. Reactive, but not deserted, TME showed an upregulation of immune-related pathways (antigen presentation, T cell receptor, NK cytotoxicity) immediately after MAPK inhibition in regressed tumors that dropped dramatically during recurrence of tumors, in which upregulation of TGF-b signaling was observed. In the deserted stroma model, on the other hand, an enrichment in drug metabolic pathways during recurrence was observed.CAF cluster deconvolution analysis revealed an increase in a LRRC15+ CAF cluster, which was TGF-b-driven and immunosuppressive, during recurrence period only in the reactive model. The dynamic changes of immune cells and CAFs were validated at protein level by multiplex immunofluorescent imaging. Cmputational spatial analysis revealed a tumor-encapsulating and CD8+ cytotoxic T cell-repelling pattern exhibited by LRRC15+FAP+ CAFs, implying a potential role of this CAF subset in T cell suppression during recurrence in reactive subtype. Using spectral cell sorting with CellView image technology, specific CAF subsets, tumor cells as well as immune cell subsets based on 30+ markers and cell morphology were isolated, characterized and assessed by ex vivo functional assays to confirm the immunosuppressive and tumor protective mechanism mediated by CAFs. Conclusion: Longitudinal in vivo assessment of distinct PDAC subtypes provides deep mechanistic insights to accurately unlock specific response patterns of tumors with heterogeneous TME dynamics upon therapeutic perturbation, leveraging identification of key nodes for intervention. Citation Format: Jens T. Siveke, Rui Fang, Phyllis Fung-Yi Cheung, Jiajin Yang, Juanfei Peng, Kristina Althoff, Konstantinos Savvatakis. Individualized longitudinal assessment reveals therapy-induced tumor and microenvironment dynamics in preclinical pancreatic cancer models [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 1598.

Abstract 2367: STING agonist ADU-S100 improves the antitumor response of CLDN18.2/CD3 BiTEs by enhancing stem-like tumor-reactive CD8+ T cells in pancreatic adenocarcinoma

Abstract Background: Immunotherapy with CLDN18.2/CD3 BiTEs (bispecific T-cell engagers) has shown clinical activity in pancreatic adenocarcinoma. However, only few patients benefit from the treatment, and most responders develop acquired resistance. STING agonists may promote the development of stem-like central memory CD8+ T cells and enhance antitumor responses. This study aimed to investigate the synergistic effect and related mechanism of STING agonist plus CLDN18.2/CD3 BiTEs regimen. Methods: Single-cell RNA sequencing and flow cytometry were used to examine the tumor immune landscape in humanized PDX mouse models. By qPCR, western blot and flow cytometry, an orthotopic transplantation mouse model of pancreatic cancer and an in vitro tumor-PBMC coculture system were established to reveal the potential molecular mechanism of STING agonist ADU-S100 in optimizing the effects of CLDN18.2/CD3 BiTEs (IBI389). Results: In PDAC organoids, IBI389 induced potent, specific cytotoxicity, the CLDN18.2 BiTEs significantly engaged human CD3+ T cells with tumor cells in an organoid-PBMC coculture system in vitro, resulting in the formation of the immunological synapse (IS). IBI389 monotherapy significantly suppressed tumor growth and improved survival in vivo in hCD3e C57BL/6 and humanized hCD34+ PDX mouse models. Further, single-cell RNA sequencing and flow cytometry analysis revealed that the intertumoral TCF1+PD-1+ stem-like T cells and STING signaling activity of T cells were enriched in the early stage of tumor development and sharply decreased in the late stage during CLDN18.2 BiTEs administration. Furthermore, we discovered that the STING agonist ADU-S100 could significantly induce the enrichment of TCF1+PD-1+ stem-like CD8+ T cells in vitro and in vivo, increasing IBI389’s therapeutic effects. Furthermore, humanized PDX mice that were given the combination of IBI389 and ADU-S100 and survived after complete tumor rejection were rechallenged with PDX tumors. Humanized PDX tumors and hCD3e KPC orthotopic tumors from mice treated with the combination contained increased numbers of TCF1+PD-1+ stem-like CD8+ T cells, CD4+CD127+ memory T cells, CD8+CD127+ memory T cells, and fewer numbers of CD4+PD-1+Tim-3+ exhausted T cells, CD8+PD-1+Tim-3+ exhausted T cells and CD4+CD25+ Treg cells. Conclusions: Pancreatic tumors appear to evade immune response by inducing immune-suppressive tumor microenvironment development. In mice, the combination of STING agonist ADU-S100 and CLDN18.2 BiTEs increased the proportion of memory and stem-like CD4+ and CD8+ T cells while decreasing the proportion of regulatory and exhausted T cells in pancreatic tumors, eradicating all detectable tumors. This data may be utilized to formulate immune-based combination therapies for PDAC. Citation Format: Tianxing Zhou, Jingrui Yan, Bin Wang, Yongjie Xie, Chao Yang, Jun Yu, Jihui Hao. STING agonist ADU-S100 improves the antitumor response of CLDN18.2/CD3 BiTEs by enhancing stem-like tumor-reactive CD8+ T cells in pancreatic adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2367.

Efficient Assessment of Tumor Vascular Shutdown by Photodynamic Therapy on Orthotopic Pancreatic Cancer Using High-Speed Wide-Field Waterproof Galvanometer Scanner Photoacoustic Microscopy.

To identify the vascular alteration by photodynamic therapy (PDT), the utilization of high-resolution, high-speed, and wide-field photoacoustic microscopy (PAM) has gained enormous interest. The rapid changes in vasculature during PDT treatment and monitoring of tumor tissue activation in the orthotopic pancreatic cancer model have received limited attention in previous studies. Here, a fully two-axes waterproof galvanometer scanner-based photoacoustic microscopy (WGS-PAM) system was developed for in vivo monitoring of dynamic variations in micro blood vessels due to PDT in an orthotopic pancreatic cancer mouse model. The photosensitizer (PS), Chlorin e6 (Ce6), was utilized to activate antitumor reactions in response to the irradiation of a 660 nm light source. Microvasculatures of angiogenesis tissue were visualized on a 40 mm2 area using the WGS-PAM system at 30 min intervals for 3 h after the PDT treatment. The decline in vascular intensity was observed at 24.5% along with a 32.4% reduction of the vascular density at 3 h post-PDT by the analysis of PAM images. The anti-vascularization effect was also identified with fluorescent imaging. Moreover, Ce6-PDT increased apoptotic and necrotic markers while decreasing vascular endothelial growth factor (VEGF) expression in MIA PaCa-2 and BxPC-3 pancreatic cancer cell lines. The approach of the WGS-PAM system shows the potential to investigate PDT effects on the mechanism of angiographic dynamics with high-resolution wide-field imaging modalities.

Biodistribution and therapeutic efficacy of a gold nanoparticle-based targeted drug delivery system against pancreatic cancer

Pancreatic cancer is characterized by desmoplasia; crosstalk between pancreatic cancer cells (PCCs) and pancreatic stellate cells (PSCs) leads to the deposition of extracellular matrix proteins in the tumor environment resulting in poor vascularity. Targeting either PCCs or PSCs individually has produced mixed results, and there is currently no effective strategy to target both cell types simultaneously. Previously, we demonstrated, through in vitro cell culture experiments, that a specific gold nanoparticle-based nanoformulation containing the anti-EGFR antibody cetuximab (C225) as a targeting agent and gemcitabine as a chemotherapeutic agent effectively targets both PCCs and PSCs simultaneously. Herein, we extend our studies to test the ability of these in vitro tested nano formulations to inhibit tumor growth in an orthotopic co-implantation model of pancreatic cancer in vivo. Orthotopic tumors were established by co-implantation of equal numbers of PCCs and PSCs in the mouse pancreas. Among the various formulations tested, 5 nm gold nanoparticles coated with gemcitabine, cetuximab and poly-ethylene glycol (PEG) of molecular weight 1000 Da, which we named ACGP441000, demonstrated optimal efficacy in inhibiting tumor growth. The current study reveals an opportunity to target PCCs and PSCs simultaneously, by exploiting their overexpression of EGFR as a target, in order to inhibit pancreatic cancer growth.

Roflumilast inhibits tumor growth and migration in STK11/LKB1 deficient pancreatic cancer

Pancreatic cancer is a malignant tumor of the digestive system. It is highly aggressive, easily metastasizes, and extremely difficult to treat. This study aimed to analyze the genes that might regulate pancreatic cancer migration to provide an essential basis for the prognostic assessment of pancreatic cancer and individualized treatment. A CRISPR knockout library directed against 915 murine genes was transfected into TB 32047 cell line to screen which gene loss promoted cell migration. Next-generation sequencing and PinAPL.py- analysis was performed to identify candidate genes. We then assessed the effect of serine/threonine kinase 11 (STK11) knockout on pancreatic cancer by wound-healing assay, chick agnosia (CAM) assay, and orthotopic mouse pancreatic cancer model. We performed RNA sequence and Western blotting for mechanistic studies to identify and verify the pathways. After accelerated Transwell migration screening, STK11 was identified as one of the top candidate genes. Further experiments showed that targeted knockout of STK11 promoted the cell migration and increased liver metastasis in mice. Mechanistic analyses revealed that STK11 knockout influences blood vessel morphogenesis and is closely associated with the enhanced expression of phosphodiesterases (PDEs), especially PDE4D, PDE4B, and PDE10A. PDE4 inhibitor Roflumilast inhibited STK11-KO cell migration and tumor size, further demonstrating that PDEs are essential for STK11-deficient cell migration. Our findings support the adoption of therapeutic strategies, including Roflumilast, for patients with STK11-mutated pancreatic cancer in order to improve treatment efficacy and ultimately prolong survival.

Abstract C062: Lipocalin 2 slows myoblast growth and contributes to pancreatic cancer-associated muscle wasting

Abstract Background: Patients with pancreatic cancer (PC) often experience cachexia, a multifactorial syndrome that includes weight loss, malnutrition, appetite suppression, and tissue wasting. Unfortunately, the factors secreted from the pancreas or other tissues that drive cachexia are still poorly defined. Lipocalin 2 (LCN2) is a cytokine involved in innate immunity that we have previously shown to be increased in the pancreas and circulation of patients with PC and mouse models of PC. Recent studies suggest that LCN2 contributes to appetite suppression in cancer cachexia in orthotopic models of PC. However, a reduction in muscle regeneration is also commonly seen in cachexia that is not repaired by increased nutrient intake. In a non-cancer setting, LCN2 has been implicated as an important factor in mediating skeletal muscle repair. Therefore, we hypothesized that elevated LCN2 in PC contributes to cachexia by inhibiting muscle progenitor cell proliferation and differentiation into new muscle fibers. Methods: Muscles from a syngeneic orthotopic mouse model of PC were assessed for muscle RING-finger protein-1 (MuRF1, an E3 ubiquitin ligase highly expressed in muscle during wasting) and LCN2 by qPCR. C2C12 mouse muscle myoblasts were cultured in proliferation or differentiation media with recombinant mouse LCN2. Proliferation across 3 days was assessed by MTS assay. Differentiation was assessed by imaging myotubes and western blotting for myosin heavy chain (MyHC) expression which increases during differentiation. PC genetically engineered mice ± a whole body LCN2 were assessed for pancreatic tumor and gastroc muscle size. One-way and Two-way ANOVAs were used to determine statistical significance. Results: LCN2 and MuRF1 expression are elevated in muscles of mice with PC. C2C12 cells treated with LCN2 decreased proliferation in a dose-dependent manner up to concentrations of LCN2 commonly observed in PC. LCN2 treatments at a physiologic concentration observed in PC delayed differentiation of C2C12 cells into myotubes by reducing myotube diameter and delaying MyHC expression. Deleting LCN2 in a PC genetic mouse model prevented body weight and gastroc weight loss but did not affect pancreas weight. Conclusions: Here, we show a relationship between muscle wasting and LCN2 expression during PC. Elevated circulating LCN2 may be contributing to decreased muscle regeneration observed in PC-associated cachexia by directly inhibiting muscle progenitor cell proliferation and differentiation. Targeting LCN2 in PC may be a viable method of slowing or preventing muscle wasting in PC to improve patient outcomes. Citation Format: Kristyn Gumpper-Fedus, Valentina Pita Grisanti, Ericka Velez Bonet, Martha A. Belury, Christopher Coss, Zobeida Cruz-Monserrate. Lipocalin 2 slows myoblast growth and contributes to pancreatic cancer-associated muscle wasting [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr C062.

Abstract C034: Genome-wide CRISPR screen identifies novel immunotherapeutic targets in pancreatic cancer

Abstract Background: Cancer-cell-intrinsic properties dictate the immune contexture of tumors, impacting the outcome of immunotherapy. Despite the increasing value of CRISPR/Cas9-based loss-of-function (LOF) genetic screens for systematically assessing gene knockout phenotype in tumor cells, it still present challenges, particularly when it comes to genomic editing in the context of large scale experiments and the identification of immunomodulatory genes in in vivo application. To address this, we have established an AsCpf1 (Cas12a)-based screen platform to enable comprehensive whole genome in vivo LOF screening and uncover novel immunotherapeutic targets for pancreatic cancer, which is notoriously resistant to current immunotherapies. Methods: We designed and constructed the optimized minimal CRISPR/AsCpf1 library that targets the entire mouse genome and is only one-fourth the size of the existing genome-wide Cas9-based library. To identify novel immune-related gene vulnerabilities in pancreatic cancer, we infected cell cultures derived from the classic p48-Cre KrasLSL-G12D/+ p53+/- genetically engineered pancreatic cancer mouse model with our AsCpf1 library for in vivo LOF screen in immune-competent and -incompetent mice. Next generation sequencing analysis was performed with the resulting tumors. The potential immunomodulatory hits were called out through BAGEL analysis, using a false discovery rate (FDR) < 0.05, and by comparing between the two mouse groups. Results: Our AsCpf1-based screen identified highly confident hits with potential immunomodulation properties. Notably, we observed depletions of various components of the MHC complex, including H13, specifically in the immune-competent background, implicating their requirement for the regulation of anti-tumor immunity. Depletion of H13 with CRISPR/Cas9 system significantly suppressed pancreatic tumor growth in T-cell dependent manner. Further immune profiling revealed that the loss of H13 triggered potent immune response which was featured by a substantial increase in effective CD8+ T cells and reduction in immunosuppressive macrophages in both subcutaneous and orthotopic models of pancreatic cancer. These findings are in accordance with our clinically relevant analysis showing that low expression of H13 is correlated with improved patient survival in pancreatic cancer and augmented responsiveness to immune checkpoint therapies in several cancer types. Conclusions: Our AsCpf1-based LOF screening platform enables unbiased exploration of in vivo functional players at whole-genome level, which can be applied to diverse disease context and models. In our lead screen, we have identified H13 as a promising immunomodulatory target for patients with pancreatic cancer. Citation Format: Xiaofei Wang, Jintan Liu, Giulio Draetta, Haoqiang Ying, Wantong Yao. Genome-wide CRISPR screen identifies novel immunotherapeutic targets in pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr C034.

Drug-repurposing by virtual and experimental screening of PFKFB3 inhibitors for pancreatic cancer therapy

Pancreatic cancer (PC) is the most frequently occurring cancer, with few effective treatments and a 5-year survival rate of only about 11%. It is characterized by stiff interstitium and pressure on blood vessels, leading to an increased glycolytic metabolism. PFKFB3 plays an important role in glycolysis, and its products (fructose-2,6-bisphosphate), which are allosteric PFK1 activators, limit the glycolytic rate. In this study, 14 PFKFB3 inhibitors were obtained by virtually screening the FDA-approved compound library. Subsequently, the in-vitro investigations confirmed that Lomitapide and Cabozantinib S-malate exhibit the excellent potential to inhibit PFKFB3. The combined administration of Lomitapide and Gemcitabine at a certain molar ratio indicated an enhanced anti-tumor effect in Orthotopic Pancreatic Cancer (OPC) models. This investigation provides a new treatment strategy for PC therapy.

Photo-Triggered Cascade Therapy: A NIR-II AIE Luminogen Collaborating with Nitric Oxide Facilitates Efficient Collagen Depletion for Boosting Pancreatic Cancer Phototheranostics.

The dense extracellular matrix (ECM) in the pancreatic cancer severely hampers the penetration of nanodrugs, which causes inferior therapeutic efficacy. To address this issue, a multifunctional liposome, namely, Lip-DTI/NO, integrating a type-I photosensitizer DTITBT with glutathione (GSH) or heat-responsive nitric oxide (NO) donor S-nitroso-N-acetyl-D-penicillamine (SNAP) is constructed to deplete the tumor ECM, leading to enhanced drug delivery and consequently improved phototherapy. The loaded DTITBT possesses multiple functions including NIR-II fluorescence imaging, efficient superoxide radical (O2 •-) generation and excellent photothermal conversion efficiency, making it feasible for precisely pinpointing the tumor in the phototherapy process. Responding to the intracellular overexpressed glutathione or heat produced by photothermal effect of DTITBT, NO can be released from SNAP. Upon 808nm laser irradiation, Lip-DTI/NO could selectively induce in situ generation of peroxynitrite anion (ONOO-) in tumor after cascade processes including O2 •- production, GSH or heat-triggered NO release, and rapid reaction between O2 •- and NO. The generated ONOO- could activate the expression of endogenous matrix metalloproteinases which could efficiently digest collagen of tumor ECM, thus facilitating enhanced penetration and accumulation of Lip-DTI/NO in tumor. In vivo evaluation demonstrates the notable therapeutic efficacy via ONOO--potentiated synergistic photodynamic-photothermal therapies on both subcutaneous and orthotopic pancreatic cancer model.

Precise Non-invasive Imaging Mouse Model of Pancreatic Cancer: Very Narrow Band-width Laser Fluorescence Excitation of Green Fluorescent Protein Provides Ultra-bright Tumor Images With no Skin Autofluorescence.

Pancreatic cancer is a recalcitrant disease with 5-year survival of only 12%. Improved mouse models of pancreatic cancer are critical for discovery of effective therapeutics. Orthotopic mouse nude-mouse models of pancreatic cancer were established with the human pancreatic-cancer cell line Panc-1 expressing green fluorescent protein (GFP) by transplanting tumor fragments into the pancreas, using the procedure of surgical orthotopic implantation (SOI). Four weeks after establishment of the orthotopic models, the mice were imaged with the Analytik Jena UVP Biospectrum Advanced with a very-narrow-band-width excitation at 487 nm and peak emission at 513 nm. Non-invasive fluorescence imaging of the mice implanted with Panc-1-GFP showed a very bright tumor in the area of the pancreas and peritoneal cavity. The skin background autofluorescence was absent. When a laparotomy was performed on the mouse for open imaging, the tumor on the pancreas was clearly imaged. There was very clear concordance of the non-invasive image and the image obtained during laparotomy. A precise orthotopic mouse model of pancreatic cancer was developed in which there was high concordance between non-invasive and invasive fluorescence imaging due to the ultra-bright signal and ultra-low background using very-narrow-band-width laser fluorescence excitation. This model can be used for high-throughput in vivo screening for improved therapeutics for pancreatic cancer.

99mTc]Tc-labeled cyc-DX600-HYNIC as a SPECT probe for ACE2-specific pancreatic cancer imaging.

As a regulator in renin-angiotensin-aldosterone system, angiotensin-converting enzyme 2 (ACE2) closely correlated with tumor progression of pancreatic cancer, meantime, was easily affected by a variety of factors. [99mTc]Tc-cyc-DX600 SPECT was established as an ACE2-specific imaging protocol to figure out the ACE2 status in pancreatic tumor. BALB/C-NU mice were used to prepare the subcutaneous cell derived xenograft (CDX) models with HEK-293T or HEK-293T/hACE2 cells to validate ACE2 specificity of [99mTc]Tc-cyc-DX600 SPECT and establish SPECT imaging protocol. On the basis of [99mTc]Tc-cyc-DX600 SPECT and [18F]F-FDG PET/CT, ACE2-dependence on tumor size and tumor metabolism were further verified on orthotopic pancreatic cancer model with KPC cells. Immunohistochemical analysis was used to demonstrate the findings on ACE2 SPECT. [99mTc]Tc-cyc-DX600 was of superior tumor uptake in HEK-293T/hACE2 CDX than wild type (6.74 ± 0.31 %ID/mL vs 1.83 ± 0.26 %ID/mL at 1.5 h post injection (p.i.); 3.14 ± 0.31 %ID/mL vs 1.16 ± 0.15 %ID/mL at 4.5 h p.i.). For the CDX models with PANC-1 cells, a significant negative correlation between the slope of tumor volume and tumor uptake was observed (r = -0.382 for the 1-4th day; r = -0.146 for the 1-5th day; r = -0.114 for the 1-6th day; r = -0.152 for the 1-7th day; but P > 0.05 for all). For orthotopic pancreatic cancer model, the linear correlation between FDG PET and ACE2 SPECT of the pancreatic lesions was negative (r = -0.878), the quantitative values of ACE2 SPCET was positively correlated with the volume of primary lesions (r = 0.752) and also positively correlated with the quantitative values of ACE2 immunohistochemical analysis (r = 0.991). Conclusively, [99mTc]Tc-cyc-DX600 SPECT is an ACE2-specific imaging protocol with clinical translational potential, adding multidimensional information on the disease progression of pancreatic cancer.

Neural Wiskott-Aldrich syndrome protein (N-WASP) promotes distant metastasis in pancreatic ductal adenocarcinoma via activation of LOXL2.

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive solid malignancies. A specific mechanism of its metastasis has not been established. In this study, we investigated whether Neural Wiskott-Aldrich syndrome protein (N-WASP) plays a role in distant metastasis of PDAC. We found that N-WASP is markedly expressed in clinical patients with PDAC. Clinical analysis showed a notably more distant metastatic pattern in the N-WASP-high group compared to the N-WASP-low group. N-WASP was noted to be a novel mediator of epithelial-mesenchymal transition (EMT) via gene expression profile studies. Knockdown of N-WASP in pancreatic cancer cells significantly inhibited cell invasion, migration, and EMT. We also observed positive association of lysyl oxidase-like 2 (LOXL2) and focal adhesion kinase (FAK) with the N-WASP-mediated response, wherein EMT and invadopodia function were modulated. Both N-WASP and LOXL2 depletion significantly reduced the incidence of liver and lung metastatic lesions in orthotopic mouse models of pancreatic cancer. These results elucidate a novel role for N-WASP signaling associated with LOXL2 in EMT and invadopodia function, with respect to regulation of intercellular communication in tumor cells for promoting pancreatic cancer metastasis. These findings may aid in the development of therapeutic strategies against pancreatic cancer.

Clinically relevant orthotopic pancreatic cancer models for adoptive T cell transfer therapy.

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive tumor. Prognosis is poor and survival is low in patients diagnosed with this disease, with a survival rate of ~12% at 5 years. Immunotherapy, including adoptive T cell transfer therapy, has not impacted the outcomes in patients with PDAC, due in part to the hostile tumor microenvironment (TME) which limits T cell trafficking and persistence. We posit that murine models serve as useful tools to study the fate of T cell therapy. Currently, genetically engineered mouse models (GEMMs) for PDAC are considered a "gold-standard" as they recapitulate many aspects of human disease. However, these models have limitations, including marked tumor variability across individual mice and the cost of colony maintenance. Using flow cytometry and immunohistochemistry, we characterized the immunological features and trafficking patterns of adoptively transferred T cells in orthotopic PDAC (C57BL/6) models using two mouse cell lines, KPC-Luc and MT-5, isolated from C57BL/6 KPC-GEMM (KrasLSL-G12D/+p53-/- and KrasLSL-G12D/+p53LSL-R172H/+, respectively). The MT-5 orthotopic model best recapitulates the cellular and stromal features of the TME in the PDAC GEMM. In contrast, far more host immune cells infiltrate the KPC-Luc tumors, which have less stroma, although CD4+ and CD8+ T cells were similarly detected in the MT-5 tumors compared with KPC-GEMM in mice. Interestingly, we found that chimeric antigen receptor (CAR) T cells redirected to recognize mesothelin on these tumors that signal via CD3ζ and 41BB (Meso-41BBζ-CAR T cells) infiltrated the tumors of mice bearing stroma-devoid KPC-Luc orthotopic tumors, but not MT-5 tumors. Our data establish for the first time a reproducible and realistic clinical system useful for modeling stroma-rich and stroma-devoid PDAC tumors. These models shall serve an indepth study of how to overcome barriers that limit antitumor activity of adoptively transferred T cells.

53P Integrin-αvβ6 targeted CAR T cells in an immunocompetent orthotopic model of pancreatic cancer

53P Integrin-αvβ6 targeted CAR T cells in an immunocompetent orthotopic model of pancreatic cancer

Prognostic value of RRM1 and its effect on chemoresistance in pancreatic cancer.

Pancreatic cancer (PC) remains a lethal disease, and gemcitabine resistance is prevalent. However, the biomarkers suggestive of gemcitabine resistance remain unclear. Bioinformatic tools identified ribonucleotide reductase catalytic subunit M1 (RRM1) in gemcitabine-related datasets. A cox regression model revealed the predictive value of RRM1 with clinical features. An external clinical cohort confirmed the prognostic value of RRM1. RRM1 expression was validated in gemcitabine-resistant cells in vitro and in orthotopic PC model. CCK8, flow cytometry, transwell migration, and invasion assays were used to explore the effect of RRM1 on gemcitabine-resistant cells. The CIBERSORT algorithm investigated the impact of RRM1 on immune infiltration. The constructed nomogram based on RRM1 effectively predicted prognosis and was further validated. Moreover, patients with higher RRM1 had shorter overall survival. RRM1 expression was significantly higher in PC tissue and gemcitabine-resistant cells in vitro and in vivo. RRM1 knockdown reversed gemcitabine resistance, inhibited migration and invasion. The infiltration levels of CD4 + T cells, CD8 + T cells, neutrophils, and plasma cells correlated markedly with RRM1 expression, and communication between tumor and immune cells probably depends on NF-κB/mTOR signaling. RRM1 may be a potential marker for prognosis and a target marker for gemcitabine resistance in PC.

Micelle-Formulated Juglone Effectively Targets Pancreatic Cancer and Remodels the Tumor Microenvironment.

Pancreatic cancer remains a formidable challenge due to limited treatment options and its aggressive nature. In recent years, the naturally occurring anticancer compound juglone has emerged as a potential therapeutic candidate, showing promising results in inhibiting tumor growth and inducing cancer cell apoptosis. However, concerns over its toxicity have hampered juglone's clinical application. To address this issue, we have explored the use of polymeric micelles as a delivery system for juglone in pancreatic cancer treatment. These micelles, formulated using Poloxamer 407 and D-α-Tocopherol polyethylene glycol 1000 succinate, offer an innovative solution to enhance juglone's therapeutic potential while minimizing toxicity. In-vitro studies have demonstrated that micelle-formulated juglone (JM) effectively decreases proliferation and migration and increases apoptosis in pancreatic cancer cell lines. Importantly, in-vivo, JM exhibited no toxicity, allowing for increased dosing frequency compared to free drug administration. In mice, JM significantly reduced tumor growth in subcutaneous xenograft and orthotopic pancreatic cancer models. Beyond its direct antitumor effects, JM treatment also influenced the tumor microenvironment. In immunocompetent mice, JM increased immune cell infiltration and decreased stromal deposition and activation markers, suggesting an immunomodulatory role. To understand JM's mechanism of action, we conducted RNA sequencing and subsequent differential expression analysis on tumors that were treated with JM. The administration of JM treatment reduced the expression levels of the oncogenic protein MYC, thereby emphasizing its potential as a focused, therapeutic intervention. In conclusion, the polymeric micelles-mediated delivery of juglone holds excellent promise in pancreatic cancer therapy. This approach offers improved drug delivery, reduced toxicity, and enhanced therapeutic efficacy.

The Tautomerase Activity of Tumor Exosomal MIF Promotes Pancreatic Cancer Progression by Modulating MDSC Differentiation.

Pancreatic cancer is a deadly disease that is largely resistant to immunotherapy, in part because of the accumulation of immunosuppressive cells in the tumor microenvironment (TME). Much evidence suggests that tumor-derived exosomes (TDE) contribute to the immunosuppressive activity mediated by myeloid-derived suppressor cells (MDSC) within the pancreatic cancer TME. However, the underlying mechanisms remain elusive. Herein, we report that macrophage migration inhibitory factor (MIF) in TDEs has a key role in inducing MDSC formation in pancreatic cancer. We identified MIF in both human and murine pancreatic cancer-derived exosomes. Upon specific shRNA-mediated knockdown of MIF, the ability of pancreatic cancer-derived exosomes to promote MDSC differentiation was abrogated. This phenotype was rescued by reexpression of the wild-type form of MIF rather than a tautomerase-null mutant or a thiol-protein oxidoreductase-null mutant, indicating that both MIF enzyme activity sites play a role in exosome-induced MDSC formation in pancreatic cancer. RNA sequencing data indicated that MIF tautomerase regulated the expression of genes required for MDSC differentiation, recruitment, and activation. We therefore developed a MIF tautomerase inhibitor, IPG1576. The inhibitor effectively inhibited exosome-induced MDSC differentiation in vitro and reduced tumor growth in an orthotopic pancreatic cancer model, which was associated with decreased numbers of MDSCs and increased infiltration of CD8+ T cells in the TME. Collectively, our findings highlight a pivotal role for MIF in exosome-induced MDSC differentiation in pancreatic cancer and underscore the potential of MIF tautomerase inhibitors to reverse the immunosuppressive pancreatic cancer microenvironment, thereby augmenting anticancer immune responses.

Successful In Situ Targeting of Pancreatic Tumors in a Novel Orthotopic Porcine Model Using Histotripsy.

New therapeutic strategies and paradigms are direly needed to treat pancreatic cancer. The absence of a suitable pre-clinical animal model of pancreatic cancer is a major limitation to biomedical device and therapeutic development. Traditionally, pigs have proven to be ideal models, especially in the context of designing human-sized instruments, perfecting surgical techniques and optimizing clinical procedures for use in humans. However, pig studies have typically focused on healthy tissue assessments and are limited to general safety evaluations because of the inability to effectively model human tumors. Here, we establish an orthotopic porcine model of human pancreatic cancer using RAG2/IL2RG double-knockout immunocompromised pigs and treat the tumors ex vivo and in vivo with histotripsy. Using these animals, we describe the successful engraftment of Panc-1 human pancreatic cancer cell line tumors and characterize their development. To illustrate the utility of these animals for therapeutic development, we determine for the first time, the successful targeting of in situ pancreatic tumors using histotripsy. Treatment with histotripsy resulted in partial ablation in vivo and reduction in collagen content in both in vivo tumor in pig pancreas and ex vivo patient tumor. This study presents a first step toward establishing histotripsy as a non-invasive treatment method for pancreatic cancer and exposes some of the challenges of ultrasound guidance for histotripsy ablation in the pancreas. Simultaneously, we introduce a highly robust model of pancreatic cancer in a large mammal model that could be used to evaluate a variety biomedical devices and therapeutic strategies.

Impact of ultrasonic inertial cavitation on the pancreatic tumor stiffness in mice

Pancreatic ductal adenocarcinoma (PDAC) is among the fastest-growing cancers and is predicted to become the second leading cause of cancer-related deaths worldwide by 2030. Ultrasound-induced inertial cavitation (IC) is an emerging therapeutic strategy with promise for treating patients with unresectable tumors. However, the physical impact of IC on tumors remains unclear. In this study, we used orthotopic murine models of pancreatic cancer and employed passive elastography to measure elasticity before and after applying IC to the whole tumor volume. The IC was generated using two focused confocal transducers (center frequency, 1.1 MHz). The output level was adjusted with a real-time feedback loop based on broadband signal acquired with a passive cavitation detector. Cavitation clouds were visualized during treatment using an imaging probe. The results from eight treated mice showed a 24% decrease (p < 0.05) in tumor stiffness after the IC treatment, indicating that the chosen IC sequence can soften the tumor environment. After sacrifice, we utilized second-harmonic imaging microscopy to visualize the collagen network within the tumor, a known contributor to tissue stiffness, and correlated various features of this network (length, width, curvature) with the measured elasticity.