Mouse Model Of Pancreatic Cancer Research Articles

Multimodal Imaging of Pancreatic Cancer Microenvironment in Response to an Antiglycolytic Drug.

Lipid metabolism and glycolysis play crucial roles in the progression and metastasis of cancer, and the use of 3-bromopyruvate (3-BP) as an antiglycolytic agent has shown promise in killing pancreatic cancer cells. However, developing an effective strategy to avoid chemoresistance requires the ability to probe the interaction of cancer drugs with complex tumor-associated microenvironments (TAMs). Unfortunately, no robust and multiplexed molecular imaging technology is currently available to analyze TAMs. In this study, the simultaneous profiling of three protein biomarkers using SERS nanotags and antibody-functionalized nanoparticles in a syngeneic mouse model of pancreatic cancer (PC) is demonstrated. This allows for comprehensive information about biomarkers and TAM alterations before and after treatment. These multimodal imaging techniques include surface-enhanced Raman spectroscopy (SERS), immunohistochemistry (IHC), polarized light microscopy, second harmonic generation (SHG) microscopy, fluorescence lifetime imaging microscopy (FLIM), and untargeted liquid chromatography and mass spectrometry (LC-MS) analysis. The study reveals the efficacy of 3-BP in treating pancreatic cancer and identifies drug treatment-induced lipid species remodeling and associated pathways through bioinformatics analysis.

Metabolic Reprogramming via ACOD1 depletion enhances function of human induced pluripotent stem cell-derived CAR-macrophages in solid tumors

The pro-inflammatory state of macrophages, underpinned by their metabolic condition, is essentially affecting their capacity of combating tumor cells. Here we find, via a pooled metabolic gene knockout CRISPR screen that KEAP1 and ACOD1 are strong regulators of the pro-inflammatory state in macrophages. We show that ACOD1 knockout macrophages, generated in our induced pluripotent stem cell-derived CAR-macrophage (CAR-iMAC) platform, are strongly and persistently polarized toward the pro-inflammatory state, which manifests in increased reactive oxygen species (ROS) production, more potent phagocytosis and enhanced cytotoxic functions against cancer cells in vitro. In ovarian or pancreatic cancer mouse models, ACOD1-depleted CAR-iMACs exhibit enhanced capacity in repressing tumors, leading to increased survival. In addition, combining ACOD1-depleted CAR-iMACs with immune checkpoint inhibitors (ICI), such as anti-CD47 or anti-PD1 antibodies, result in even stronger tumor suppressing effect. Mechanistically, the depletion of ACOD1 reduces levels of the immuno-metabolite itaconate, allowing KEAP1 to prevent NRF2 from entering the nucleus to activate an anti-inflammatory program. This study thus lays down the proof of principle for targeting ACOD1 in myeloid cells for cancer immunotherapy and introduces metabolically engineered human iPSC-derived CAR-iMACs cells with enhanced polarization and anti-tumor functions in adoptive cell transfer therapies.

Commensal bacterial hybrid nanovesicles improve immune checkpoint therapy in pancreatic cancer through immune and metabolic reprogramming

Harnessing the immunomodulatory ability of the microbiota, such as fecal microbiota transplantation (FMT), has emerged as a promising strategy to improve cancer immunotherapy. However, the lack of standardization in fecal material formulation and safety concerns have hindered clinical application. To overcome these limitations, we developed a high-yielding method by hybridizing bacteria protoplast-derived membrane nanovesicles (PDNVs) from three colon bacteria strains that have been associated with favorable responses to immune checkpoint therapy, including Akkermansia muciniphila, Bifidobacterium longum, and Bifidobacterium breve. The resulting hybrid nanovesicles (HNVs) are composed mainly of cytoplasmic membrane proteins inherited from the originating bacteria but lack pyrogens such as lipopolysaccharide and lipoteichoic acid. Our study demonstrated that HNVs have superior targeting abilities to tumors and peripheral lymphoid organs, leading to greater capability in inducing innate immune activation, dendritic cell maturation and antigen presentation, as well as tumor microenvironment reprogramming. Combined with αPD-1 blockade therapy, HNVs efficiently inhibited the tumor growth in multiple pancreatic cancer mouse models, including Panc02 subcutaneous and liver metastatic models, and orthotopic KPC-Luc pancreatic cancer model. Mechanically, HNVs simultaneously activated the innate arm of immunity and inhibited tumor oxidative phosphorylation (OXPHOS) to reshape the tumor immune microenvironment for improved αPD-1 blockade therapy. Notably, HNVs administration gave rise to similar tumor regression rates to oral transfer of a mixture of live or inactivated bacteria during αPD-1 blockade therapy, but with fewer adverse effects such as diarrhea and colon-intestinal inflammation. Our findings present a stable, cost-effective, and safe alternative to live bacteria for regulating tumor microenvironment for improved cancer immunotherapy.

Recombinant oncolytic adenovirus armed with CCL5, IL-12, and IFN-γ promotes CAR-T infiltration and proliferation in vivo to eradicate local and distal tumors

The efficacy of chimeric antigen receptor T (CAR-T) cells for solid tumors remains unsatisfactory due to the limited tumor infiltration and immunosuppressive microenvironment. To overcome these limitations, the genetically engineered recombinant oncolytic adenoviruses (OAVs) that conditionally replicate in tumor cells were developed to modify the tumor microenvironment (TME) to facilitate CAR-T-mediated tumor eradication. Here in the present study, a novel recombinant OAV carrying CCL5, IL12, and IFN-γ controlled by Ki67 promoter was constructed (named AdKi67-C3). The antitumor activity of AdKi67-C3 was tested in vitro and in vivo by using mono administration or combing with CAR-T cells targeting B7H3. It proved that CCL5 expressed by AdKi67-C3 indeed induced more CAR-T migration in vitro and CAR-T infiltration in tumor mass in vivo. Meanwhile, cytokines of IFN-γ and IL12 secreted by AdKi67-C3-infected tumor cells significantly promoted proliferation and persistence of CAR-T cells in vitro and in vivo. In tumor-bearing xenograft mouse models of kidney, prostate or pancreatic cancer, local pretreatment with AdKi67-C3 dramatically enhanced CAR-T cell efficacy and eliminated local and distant tumors. More importantly, mice achieving complete tumor regression resisted to re-challenge with the same tumor cells, suggesting establishment of long-term antitumor immune response. Therefore, OAVs armored with cytokines could be developed as a bioenhancer to defeat the immunosuppressive microenvironment and improve therapeutic efficacy of CAR-T in solid tumors.

A TGF-β/KLF10 signaling axis regulates atrophy-associated genes to induce muscle wasting in pancreatic cancer

Cancer cachexia, and its associated complications, represent a large and currently untreatable roadblock to effective cancer management. Many potential therapies have been proposed and tested-including appetite stimulants, targeted cytokine blockers, and nutritional supplementation-yet highly effective therapies are lacking. Innovative approaches to treating cancer cachexia are needed. Members of the Kruppel-like factor (KLF) family play wide-ranging and important roles in the development, maintenance, and metabolism of skeletal muscle. Within the KLF family, we identified KLF10 upregulation in a multitude of wasting contexts-including in pancreatic, lung, and colon cancer mouse models as well as in human patients. We subsequently interrogated loss-of-function of KLF10 as a potential strategy to mitigate cancer associated muscle wasting. In vivo studies leveraging orthotopic implantation of pancreas cancer cells into wild-type and KLF10 KO mice revealed significant preservation of lean mass and robust suppression of pro-atrophy muscle-specific ubiquitin ligases Trim63 and Fbxo32, as well as other factors implicated in atrophy, calcium signaling, and autophagy. Bioinformatics analyses identified Transforming growth factor beta (TGF-β), a known inducer of KLF10 and cachexia promoting factor, as a key upstream regulator of KLF10. We provide direct in vivo evidence that KLF10 KO mice are resistant to the atrophic effects of TGF-β. ChIP-based binding studies demonstrated direct binding to Trim63, a known wasting-associated atrogene. Taken together, we report a critical role for the TGF-β/KLF10 axis in the etiology of pancreatic cancer-associated muscle wasting and highlight the utility of targeting KLF10 as a strategy to prevent muscle wasting and limit cancer-associated cachexia.

TAp73 Inhibits EMT and Cell Migration in Pancreatic Cancer Cells through Promoting SMAD4 Expression and SMAD4-Dependent Inhibition of ERK Activation.

Pancreatic ductal adenocarcinoma (PDAC) is a fatal disease due to early metastatic spread, late diagnosis and the lack of efficient therapies. A major driver of cancer progression and hurdle to successful treatment is transforming growth factor (TGF)-β. Recent data from pancreatic cancer mouse models showed that transcriptionally active p73 (TAp73), a p53 family member, inhibits tumor progression through promoting tumor suppressive canonical TGF-β/Smad signaling, while preventing non-canonical TGF-β signaling through extracellular signal-regulated kinases (ERK)1/2. Here, we studied whether this mechanism also operates in human PDAC. Using the PDAC-derived tumor cell lines PANC-1, HPAFII and L3.6pl, we showed that TAp73 induces the expression of the epithelial marker and invasion suppressor E-cadherin and the common-mediator Smad, SMAD4, while at the same time suppressing expression of the EMT master regulator SNAIL and basal and TGF-β1-induced activation of ERK1 and ERK2. Using dominant-negative and RNA interference-based inhibition of SMAD4 function, we went on to show that inhibition of ERK activation by TAp73 is mediated through SMAD4. Intriguingly, both SMAD4 and the α isoform of TAp73-but not the β isoform-interfered with cell migration, as shown by xCELLigence technology. Our findings highlighted the role of TAp73-SMAD4 signaling in tumor suppression of human PDAC and identified direct inhibition of basal and TGF-β-stimulated pro-invasive ERK activation as an underlying mechanism.

Targeted Reprogramming of Vitamin B3 Metabolism as a Nanotherapeutic Strategy towards Chemoresistant Cancers.

Cancer-associated fibroblasts (CAFs) promote cancer stem cell (CSC)-mediated chemoresistance and immunosuppressive tumor microenvironment. However, direct depletion of CAFs may increase cancer invasiveness and metastasis. As a generalized strategy against chemoresistant cancers, Gemini-like homotypic targeting nanoparticles (NPs) are designed for two-pronged CAF transformation and cancer cell elimination. The CAF-targeted NPs couple vitamin B3 metabolic reprogramming to epigenetic modulation of secreted pro-stemness and immunosuppressive factors, thereby diminishing CSC and suppressive immune cell populations to enhance cancer cell drug susceptibility and cytotoxic T cell infiltration. In mouse models of breast, liver, pancreatic and colorectal cancers that are resistant to their respective first-line chemotherapeutics, a single dose of hydrogel co-delivering the Gemini-like NPs can rehabilitate chemosensitivity, induce immune activation, and achieve tumor regression. Moreover, it stimulates robust T cell memory for long-term protection against tumor rechallenge. This study thus represents an innovative approach with broad applicability for overcoming cancer chemoresistance.

Integrin αvβ3 and EGFR dual-targeted [64Cu]Cu-NOTA-RGD-GE11 heterodimer for PET imaging in pancreatic cancer mouse model

PurposeRadiolabeled heterodimeric peptide has emerged as a highly promising targeting strategy for PET imaging due to their superior properties. RGD and GE11 are two peptides binding to receptor integrin αvβ3 and EGFR, respectively, which both overexpress in many different types of tumors. This study focuses on the synthesis and evaluation of a RGD and GE11-containing heterodimeric radiotracer [64Cu]Cu-NOTA-RGD-GE11 for PET imaging of tumors that simultaneously overexpress integrin αvβ3 and EGFR. Procedures[64Cu]Cu-NOTA-RGD-GE11 was prepared by the conjugation of RGD-PEG4-NOTA-N3 and GE11-PEG4-BCN via metal-free click chemistry, followed by radiolabeling with 64Cu. Cell uptake and efflux studies, saturation binding assay, the animal PET/CT and biodistribution studies were conducted to characterize the biological properties of [64Cu]Cu-NOTA-RGD-GE11. Results[64Cu]Cu-NOTA-RGD-GE11 was synthesized with a radiochemical purity of >97 % and molar activity of 23 GBq/μmol at the end of synthesis. [64Cu]Cu-NOTA-RGD-GE11 showed moderate hydrophilicity, good stability in mouse serum and high specific uptake by the human pancreatic cancer cell line (BxPC3) in the in vitro studies. Compared to the two monomeric counterparts [64Cu]Cu-NOTA-RGD and [64Cu]Cu-NOTA-GE11, [64Cu]Cu-NOTA-RGD-GE11 demonstrated significantly improved tumor uptakes (e.g. 4.63 ± 0.25 %ID/g vs 1.24 ± 0.18 %ID/g and 0.77 ± 0.13 %ID/g, 2 h after injection, p < 0.05) in the subsequent in vivo evaluation in mice bearing BxPC3 xenograft. Tumor uptake could be blocked in the presence of both non-radioactive c(RGDyK) and GE11 peptides, indicating good tumor specificity of [64Cu]Cu-NOTA-RGD-GE11 in vivo. ConclusionThe results suggested that the as-developed [64Cu]Cu-NOTA-RGD-GE11 could serve as a potential PET tracer for the noninvasive imaging of integrin αvβ3 and EGFR expression in tumors.

Intratumor Fusobacterium nucleatum promotes the progression of pancreatic cancer via the CXCL1-CXCR2 axis.

Intratumor bacteria modify the tumor immune microenvironment and influence outcomes of various tumors. Periodontal pathogen Fusobacterium nucleatum has been detected in pancreatic cancer tissues and is associated with poor prognosis. However, it remains unclear how F. nucleatum affects pancreatic cancer. Here, we compared clinical features with F. nucleatum colonization in pancreatic cancer tissues. F. nucleatum was detected in 15.5% (13/84) of pancreatic cancer patients. The tumor size was significantly larger in the F. nucleatum-positive group than in the negative group. To clarify the biological effect of intratumor F. nucleatum on pancreatic cancer progression, we performed migration/invasion assays and cytokine array analysis of cancer cells cocultured with F. nucleatum. F. nucleatum promoted CXCL1 secretion from pancreatic cancer cells, leading to cancer progression through autocrine signaling. Intratumor F. nucleatum suppressed tumor-infiltrating CD8+ T cells by recruiting myeloid-derived suppressor cells (MDSCs) to the tumor in an F. nucleatum-injected subcutaneous pancreatic cancer mouse model, resulting in tumor progression. Furthermore, tumor growth accelerated by F. nucleatum was suppressed by MDSC depletion or cytokine inhibitors. Intratumor F. nucleatum promoted pancreatic cancer progression through autocrine and paracrine mechanisms of the CXCL1-CXCR2 axis. Blockade of the CXCL1-CXCR2 axis may be a novel therapeutic approach for patients with intratumor F. nucleatum-positive pancreatic cancer.

Quantitative intravital imaging for real-time monitoring of pancreatic tumor cell hypoxia and stroma in an orthotopic mouse model.

Pancreatic cancer is a lethal disease with few successful treatment options. Recent evidence demonstrates that tumor hypoxia promotes pancreatic tumor invasion, metastasis, and therapy resistance. However, little is known about the complex relationship between hypoxia and the pancreatic tumor microenvironment (TME). In this study, we developed a novel intravital fluorescence microscopy platform with an orthotopic mouse model of pancreatic cancer to study tumor cell hypoxia within the TME in vivo, at cellular resolution, over time. Using a fluorescent BxPC3-DsRed tumor cell line with a hypoxia-response element (HRE)/green fluorescent protein (GFP) reporter, we showed that HRE/GFP is a reliable biomarker of pancreatic tumor hypoxia, responding dynamically and reversibly to changing oxygen concentrations within the TME. We also characterized the spatial relationships between tumor hypoxia, microvasculature, and tumor-associated collagen structures using in vivo second harmonic generation microscopy. This quantitative multimodal imaging platform enables the unprecedented study of hypoxia within the pancreatic TME in vivo.

The effect of adding a selective FAK inhibitor AMP945 to FOLFIRINOX in a model of pancreatic cancer.

e15128 Background: Pancreatic Cancer (PC) is a one of the leading causes of cancer-related death in the world, with a five-year survival rate of ~11%. The majority of patients present with advanced metastatic disease and are treated with chemotherapy. FOLFIRINOX is the standard-of-care treatment for patients in many countries and has been shown to result in a median overall survival of 11.1 months. Focal Adhesion Kinase (FAK) is a non-receptor tyrosine kinase which transduces signaling from integrin receptors, activated through interactions with the extracellular matrix, to regulate cell survival, proliferation and migration, and is often highly expressed in PC. Inhibition of FAK in preclinical models of PC has been shown to sensitize cells to radiotherapy, immunotherapy and chemotherapy. AMP945 is a potent and selective FAK inhibitor currently undergoing a Phase Ib/IIa trial in PC in combination with gemcitabine and nab-paclitaxel (NCT05355298). We now demonstrate that AMP945, in combination with FOLFIRINOX, can significantly improve survival in mouse models of PC, providing strong rationale for clinical testing of this novel treatment combination. Methods: Patient Derived Xenograft (PDX) models of PC in NOGIL2 mice using TKCC10lo patient derived cells were conducted in both subcutaneous and orthotopic formats. Once the tumor was palpable, AMP945 (10 mg/kg, b.i.d.) was administered for four days. On day 8 oxaliplatin (5 mg/kg) and irinotecan (25 mg/kg) were administered, with leucovorin calcium (100 mg/kg) and fluorouracil (25 mg/kg) being dosed on day 9. The mice were monitored until day 12 and the treatment regimen was repeated for up to 20 cycles, or until the experimental endpoint was reached. At the experimental endpoint the mice were sacrificed, the tumor harvested and analyzed. Results: In the subcutaneous model the combination of AMP945 and FOLFIRINOX increased survival by ~35% compared to FOLFIRINOX alone. In the orthotopic model, median survival was extended by ~30% when using the AMP945/FOLFIRINOX combination, compared to FOLFIRINOX alone. In both models there was a significant reduction in tumor size and clear evidence of on-target FAK inhibition in tumors (reduction in pY397FAK levels) in the combination therapy groups. Notably, a significant increase in cleaved caspase-3, a marker of apoptosis, was also apparent in the combination therapy groups. Conclusions: The FAK inhibitor AMP945, given in a pulsed-dosing regimen in combination with FOLFIRINOX, significantly enhances survival in a mouse model of pancreatic cancer by increasing apoptosis and reducing tumor burden, highlighting the potential of this combination in clinical treatment of PC. A clinical study of the combination of AMP945 with FOLFIRINOX is now in planning.

A pilot study of liposomal irinotecan plus 5-FU/LV combined with paricalcitol in patients with advanced pancreatic cancer whose disease progressed on gemcitabine-based therapy.

e16263 Background: 5-FU-based chemotherapy is the standard of care for patients with advanced pancreatic cancer progressed on gemcitabine-based therapy. Based on the NAPOLI-1 study, 5-FU/LV/liposomal irinotecan is currently an FDA-approved regimen in the second-line setting with median progression free survival (mPFS) 3.1 months, median overall survival (mOS) 6.1 months and objective response rate (ORR) 16%. In pancreatic cancer mouse models, vitamin D was shown to remodel the desmoplastic stroma and when combined with chemotherapy significantly improved animal survival. Methods: We conducted a pilot study in patients with advanced pancreatic cancer progressed on gemcitabine-based therapy treated with 5-FU (2,400mg/m2)/LV (400mg/m2)/liposomal irinotecan (70mg/m2) with paricalcitol in two dose level cohorts: paricalcitol 75mcg IV on day 1 weekly (N=10, dose level 1) or 7mcg/kg IV on day 1 weekly (N=10, dose level 2). The primary endpoint was safety and toxicity. Dose-limiting toxicities (DLT) were assessed during cycle 1. Secondary endpoints include ORR, PFS and OS. Results: Between 8/29/2019 to 5/6/2021, a total of 20 patients were enrolled in the study. No DLTs or grade 4 adverse events were observed in either paricalcitol cohort. The most common toxicities were gastrointestinal (nausea, diarrhea), fatigue and anemia and were similar in both cohorts. Only one grade 3 adverse event was possibly due to paricalcitol (spinal fracture, dose level 1). 2/17 (12%) evaluable patients experienced an objective response (both in dose level 2), one of which was confirmed. Disease control rate (DCR) was 65%. Median follow up was 6.15 months. At the time of analysis, mPFS of all patients is 3.57 months (95% CI 1.28 – 8.12) and mOS is 6.14 months (95% CI 2.43 – 11.77). The mPFS is 3.55 months (0.79-6.21) for dose level 1 and 4.83 months (0.62-9.96) for dose level 2. The mOS is 6.15 months (0.79-8.12) for dose level 1 and 6.66 months (1.78-14.53) for dose level 2. Correlative analysis shows increased tumor vascularity (via CD31) and a trend toward decreased stromal fibrosis (via Sirius Red) in dose level 2. Conclusions: Administration of paricalcitol in combination with liposomal irinotecan and 5-FU/LV is well tolerated in patients with advanced pancreatic cancer and survival outcomes were comparable to liposomal irinotecan plus 5-FU/ LV. Clinical trial information: NCT03883919 .

Impact of Arterial Input Function and Pharmacokinetic Models on DCE-MRI Biomarkers for Detection of Vascular Effect Induced by Stroma-Directed Drug in an Orthotopic Mouse Model of Pancreatic Cancer.

We demonstrated earlier in mouse models of pancreatic ductal adenocarcinoma (PDA) that Ktrans derived from dynamic contrast-enhanced (DCE) MRI detected microvascular effect induced by PEGPH20, a hyaluronidase which removes stromal hyaluronan, leading to reduced interstitial fluid pressure in the tumor (Clinical Cancer Res (2019) 25: 2314-2322). How the choice of pharmacokinetic (PK) model and arterial input function (AIF) may impact DCE-derived markers for detecting such an effect is not known. Retrospective analyses of the DCE-MRI of the orthotopic PDA model are performed to examine the impact of individual versus group AIF combined with Tofts model (TM), extended-Tofts model (ETM), or shutter-speed model (SSM) on the ability to detect the microvascular changes induced by PEGPH20 treatment. Individual AIF exhibit a marked difference in peak gadolinium concentration. However, across all three PK models, kep values show a significant correlation between individual versus group-AIF (p < 0.01). Regardless individual or group AIF, when kep is obtained from fitting the DCE-MRI data using the SSM, kep shows a significant increase after PEGPH20 treatment (p < 0.05 compared to the baseline); %change of kep from baseline to post-treatment is also significantly different between PEGPH20 versus vehicle group (p < 0.05). In comparison, when kep is derived from the TM, only the use of individual AIF leads to a significant increase of kep after PEGPH20 treatment, whereas the %change of kep is not different between PEGPH20 versus vehicle group. Group AIF but not individual AIF allows detection of a significant increase of Vp (derived from the ETM) in PEGPH20 versus vehicle group (p < 0.05). Increase of Vp is consistent with a large increase of mean capillary lumen area estimated from immunostaining. Our results suggest that kep derived from SSM and Vp from ETM, both using group AIF, are optimal for the detection of microvascular changes induced by stroma-directed drug PEGPH20. These analyses provide insights in the choice of PK model and AIF for optimal DCE protocol design in mouse pancreatic cancer models.

Abstract IA19: Oncogenic KRAS and the regulation of the pancreatic cancer microenvironment.

Abstract Pancreatic ductal adenocarcinoma, the most common form of pancreatic cancer, is characterized by almost universal presence of oncogenic KRAS. A key characteristic of pancreatic cancer is the abundant accumulation of tumor microenvironment, rich in infiltrating immune cells and an extensive fibroblast population. Pancreatic cancer is preceded by precursor lesions known as Pancreatic Intraepithelial Neoplasia (PanIN); PanIN formation is accompanied by the formation of a pre-TME. Analysis of donor pancreas from healthy individual revealed that PanIN is common in human samples, and accompanied by pre-TME accumulation in human samples. We sought to determine whether oncogenic KRAS drives accumulation and maintenance of the pre-TME. For this purpose, we utilized the iKRAS mouse model of pancreatic cancer, which allows tissue-specific, inducible and reversible activation of KRASG12D, the most common mutant form in human pancreatic cancer. Activation of oncogenic KRAS in iKRAS mice leads to PanIN formation. We observed that fibroblast activation occurs upon KRAS activation and precedes the formation of overt lesions. Further, epithelial oncogenic KRAS is required to maintain fibroblast reprogramming in PanIN. To comprehensively understand changes in fibroblasts, we used single cell RNA sequencing, and observed that the fibroblast transcriptional program is extrinsically regulated by epithelial oncogenic KRAS. The reprogramming process can be modeled in vivo using conditioned media from pancreatic cancer cells expressing oncogenic KRAS, and is mediated by JAK/STAT3 signaling in fibroblasts. We then sought to determine whether the extrinsic effects of oncogenic KRAS induced reprogramming of fibroblasts at distal sites. We chose to study the lung, which is a common site of metastasis for pancreatic cancer. Our data show that lung fibroblasts are activated following expression of oncogenic KRAS in the pancreas; fibroblast activation is accompanied by phospho-Stat3 signaling, a readout of the JAK/Stat3 pathway, and precedes metastasis outgrowth in the pancreas. Thus, oncogenic KRAS extrinsically reprograms the local and systemic environments, possibly facilitating metastatic spread of pancreatic cancer. Citation Format: Marina Pasca di Magliano. Oncogenic KRAS and the regulation of the pancreatic cancer microenvironment. [abstract]. In: Proceedings of the AACR Special Conference: Targeting RAS; 2023 Mar 5-8; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Res 2023;21(5_Suppl):Abstract nr IA19.

BRD4 and BET proteins regulate CD8 T cell exhaustion in mouse models of cancer

Abstract Harnessing the cytotoxic capacity of CD8 T cells is central to the efficacy of immunotherapy and has revolutionized the fight against cancer. However, despite encouraging success for select indications, immunotherapies still fail to achieve durable and effective outcomes for certain cancer types and in many patients. Failure of immunotherapies often results from CD8 T cells differentiating into an epigenetically controlled and reinforced state known as T cell exhaustion. Therefore, resolving the molecular programs governing T cell differentiation within the tumor microenvironment (TME) is critical to enhancing treatment. Using mouse models of breast cancer and pancreatic cancer, we investigated the role of the bromodomain and extraterminal (BET) family of proteins in mediating T cell differentiation and exhaustion. Depletion of BRD2, BRD3, and BRD4 in CD8 T cells differentially affected CD8 T cell accumulation and the exhausted phenotype within the tumor microenvironment. Further, small molecule inhibition of the BET family similarly impacted CD8 T cell differentiation and exhaustion in vivo. Our findings may inform new strategies to circumvent CD8 T cell exhaustion during infection. supported by a training grant from the UNC Pharmacology Department (5T32GM135095-02)

Regulation of immune-recognition molecules following delivery of plasmid backbone

Abstract Local intratumor delivery with electroporation of low levels of plasmids encoding molecules, such as IL-12, IL-15, induces an antitumor effect without causing systemic toxicity. However, previous studies have predominately focused on the function of the delivered molecule encoded within the plasmid, and ignored the plasmid backbone. In this study, we found backbones pUMVC3 and pVax1 induced up-regulation of MHC class I (MHC-I), PD-L1, CD95 (Fas) and CD155 on tumor cell surface. These molecules participate in a considerable number of immunoregulatory functions through their interactions with activating and inhibitory immune cell receptors. MHC molecules are well-known for their role in antigen (cross-) presentation, thereby functioning as key players in the communication between immune cells and tumor cells. Increased PD-L1 expression on tumor cells is an important monitor of tumor growth and effectiveness of immune inhibitor therapy. During cancer progression CD95 is frequently downregulated, raising the possibility that loss of CD95 is part of a mechanism for tumor evasion. Due to its prominent endogenous and immune functions, CD155 has been gaining interest as a therapeutic target in the field of tumor immunology. Results from flow cytometry confirmed increased expression of MHC-I and PDL-1 on B16F10, 4T1 and KPC tumor cell lines. Preliminary animal data from tumor-bearing models, B16F10 melanoma, 4T1 breast cancer and KPC pancreatic cancer mouse models showed that tumor growth was attenuated after pUMVC3 intratumoral electroporation. Our data also documented pSTAT1-NF-κB signaling pathway might be associated with plasmid backbones’ function of up-regulating MHC-I, PD-L1, CD95 (Fas) and CD155 on tumor cells. R01 CA186730

Design and selection of optimal ErbB-targeting bispecific antibodies in pancreatic cancer.

The ErbB family of receptor tyrosine kinases is a primary target for small molecules and antibodies for pancreatic cancer treatment. Nonetheless, the current treatments for this tumor are not optimal due to lack of efficacy, resistance, or toxicity. Here, using the novel BiXAb™ tetravalent format platform, we generated bispecific antibodies against EGFR, HER2, or HER3 by considering rational epitope combinations. We then screened these bispecific antibodies and compared them with the parental single antibodies and antibody pair combinations. The screen readouts included measuring binding to the cognate receptors (mono and bispecificity), intracellular phosphorylation signaling, cell proliferation, apoptosis and receptor expression, and also immune system engagement assays (antibody-dependent cell-mediated cytotoxicity and complement-dependent cytotoxicity). Among the 30 BiXAbs™ tested, we selected 3Patri-1Cetu-Fc, 3Patri-1Matu-Fc and 3Patri-2Trastu-Fc as lead candidates. The in vivo testing of these three highly efficient bispecific antibodies against EGFR and HER2 or HER3 in pre-clinical mouse models of pancreatic cancer showed deep antibody penetration in these dense tumors and robust tumor growth reduction. Application of such semi-rational/semi-empirical approach, which includes various immunological assays to compare pre-selected antibodies and their combinations with bispecific antibodies, represents the first attempt to identify potent bispecific antibodies against ErbB family members in pancreatic cancer.

Chronic effects of pulsed high intensity focused ultrasound aided delivery of gemcitabine in a mouse model of pancreatic cancer

Pulsed high intensity focused ultrasound (pHIFU) is a non-invasive method that allows to permeabilize pancreatic tumors through inertial cavitation and thereby increase the concentration of systemically administered drug. In this study the tolerability of weekly pHIFU-aided administrations of gemcitabine (gem) and their influence on tumor progression and immune microenvironment were investigated in genetically engineered KrasLSL.G12D/þ; p53R172H/þ; PdxCretg/þ (KPC) mouse model of spontaneously occurring pancreatic tumors. KPC mice were enrolled in the study when the tumor size reached 4–6 mm and treated once a week with either ultrasound-guided pHIFU (1.5 MHz transducer, 1 ms pulses, 1% duty cycle, peak negative pressure 16.5 MPa) followed by administration of gem (n = 9), gem only (n = 5) or no treatment (n = 8). Tumor progression was followed by ultrasound imaging until the study endpoint (tumor size reaching 1 cm), whereupon the excised tumors were analyzed by histology, immunohistochemistry (IHC) and gene expression profiling (Nanostring PanCancer Immune Profiling panel). The pHIFU + gem treatments were well tolerated; the pHIFU-treated region of the tumor turned hypoechoic immediately following treatment in all mice, and this effect persisted throughout the observation period (2–5 weeks) and corresponded to areas of cell death, according to histology and IHC. Enhanced labeling by Granzyme-B was observed within and adjacent to the pHIFU treated area, but not in the non-treated tumor tissue; no difference in CD8 + staining was observed between the treatment groups. Gene expression analysis showed that the pHIFU + gem combination treatment lead to significant downregulation of 162 genes related to immunosuppression, tumorigenesis, and chemoresistance vs gem only treatment.

RETRACTED ARTICLE: Palmitoyl transferases act as novel drug targets for pancreatic cancer

BackgroundPancreatic adenocarcinoma (PAAD) is one of the most leading causes of cancer-related death across the world with the limited efficiency and response rate of immunotherapy. Protein S-palmitoylation, a powerful post-translational lipid modification, is well-known to regulate the stability and cellular distribution of cancer-related proteins, which is mediated by a family of 23 palmitoyl transferases, namely zinc finger Asp-His-His-Cys-type (ZDHHC). However, whether palmitoyl transferases can determine tumor progression and the efficacy of immunotherapy in PAAD remains unknown.MethodsBioinformatics methods were used to identify differential ZDHHCs expression in PAAD. A systematic pan-cancer analysis was conducted to assess the immunological role of ZDHHC3 using RNA sequencing data from The Cancer Genome Atlas database. In vivo Panc 02 subcutaneous tumor model validated the anti-tumor effect of knockdown of ZDHHC3 or intraperitoneal injection of 2-bromopalmitate (2-BP), a typical broad-spectrum palmitoyl transferases inhibitor. Furthermore, we explored therapeutic strategies with combinations of 2-BP with PD-1/PD-L1-targeted immunotherapy in C57BL/6 mice bearing syngeneic Panc 02 pancreatic tumors.ResultsZDHHC enzymes were associated with distinct prognostic values of pancreatic cancer. We identified that ZDHHC3 expression promotes an immunosuppressive tumor microenvironment in PAAD. 2-BP suppressed pancreatic-tumor cell viability and tumor sphere-forming activities, as well as increased cell apoptosis in vitro, without affecting normal human pancreatic ductal epithelial cells. Furthermore, genetic inactivation of ZDHHC3 or intraperitoneal injection of 2-BP impeded tumor progression in Panc 02 pancreatic tumors with enhanced anti-tumor immunity. 2-BP treatment significantly enhanced the therapeutic efficacy of PD-1/PD-L1 inhibitors in Panc 02 pancreatic tumors.ConclusionThis study revealed some ZDHHC enzyme genes for predicting the prognosis of pancreatic cancer, and demonstrated that ZDHHC3 plays a critical oncogenic role in pancreatic cancer progression, highlighting its potential as an immunotherapeutic target of pancreatic cancer. In addition, combination therapy of 2-BP and PD-1/PD-L1 achieved synergic therapy effects in a mouse model of pancreatic cancer.

Abstract 3641: Loss of Smad4 induces SPP1 secretion and immunosuppressive myeloid cell formation in pancreatic ductal adenocarcinoma

Abstract Up to 50% of pancreatic ductal adenocarcinomas (PDA) harbor mutations in canonical TGFß pathway genes such as SMAD4 and TGFBR2. SMAD4 mutations have been shown to drive resistance to chemotherapy, metastasis, and margin positivity following surgical resection. To characterize the unique tumor microenvironment of SMAD4 mutant PDA, we developed isogenic, orthotopic mouse models using CRISPR mediated knockout of Smad4 in a cell line derived from KPfC (KrasLSL-G12D;Trp53fl/fl;Pdx1Cre) mice, a genetically engineered mouse model of pancreatic cancer. To characterize the alteration of the secretome caused by the loss of Smad4, we performed proteomic analysis with conditioned media collected from Smad4 wildtype and mutant cancer cell clones. Interestingly, the loss of Smad4 resulted in the production of neuroendocrine related factors. In addition, gene ontology analysis with the secretome suggested that these factors were associated with neuronal processes. These data indicate that loss of Smad4 in PDA cancer cells may lead to a neuroendocrine signature change. In particular, we found one of the most up-regulated secreted factors in the mutant cells was SPP1, which has been shown to promote tumor progression by affecting cancer cell stemness and macrophage polarization. To validate the proteomic results, we established orthotopic models with Smad4 wildtype and mutant clones. We found that loss of Smad4 resulted in larger tumor growth. Moreover, immunohistochemistry showed a significant up-regulation of SPP1 in the cancer cells of Smad4 mutant tumors. To further profile the alteration of immune landscape, we stained for markers of myeloid cells and lymphocytes. We found that Smad4 mutant tumors had an immunosuppressive microenvironment characterized by increased M2 macrophage, neutrophil and MDSC infiltration. Altogether, our study suggests that loss of SMAD4 in PDA may induce a neuroendocrine signature with increased SPP1 secretion in cancer cells. The production of this unique cancer cell secretome may result in a microenvironment marked by immunosuppressive myeloid cells. Citation Format: Gilbert Z. Murimwa, Francesca Rossi, Henry K. Fleming, Zeynep Yazgan, Dina Alzhanova, Huocong Huang, Rolf A. Brekken. Loss of Smad4 induces SPP1 secretion and immunosuppressive myeloid cell formation in pancreatic ductal adenocarcinoma. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3641.