Abstract PO-056: Targeting of cancer associated fibroblast-specific MEK1 and STAT3 to overcome immunosuppressive microenvironment in Pancreatic Ductal Adenocarcinoma (PDAC)

Author(s):  
Siddharth Mehra ◽  
Xizi Dai ◽  
Anna Bianchi ◽  
Austin Dosch ◽  
Iago de Castro Silva ◽  
...  
2021 ◽  
Vol 11 (1) ◽  
Author(s):  
J. I. Alexander ◽  
D. B. Vendramini-Costa ◽  
R. Francescone ◽  
T. Luong ◽  
J. Franco-Barraza ◽  
...  

AbstractPancreatic Ductal Adenocarcinoma (PDAC) has a five-year survival under 10%. Treatment is compromised due to a fibrotic-like stromal remodeling process, known as desmoplasia, which limits therapeutic perfusion, supports tumor progression, and establishes an immunosuppressive microenvironment. These processes are driven by cancer-associated fibroblasts (CAFs), functionally activated through transforming growth factor beta1 (TGFβ1). CAFs produce a topographically aligned extracellular matrix (ECM) that correlates with reduced overall survival. Paradoxically, ablation of CAF populations results in a more aggressive disease, suggesting CAFs can also restrain PDAC progression. Thus, unraveling the mechanism(s) underlying CAF functions could lead to therapies that reinstate the tumor-suppressive features of the pancreatic stroma. CAF activation involves the f-actin organizing protein palladin. CAFs express two palladin isoforms (iso3 and iso4) which are up-regulated in response to TGFβ1. However, the roles of iso3 and iso4 in CAF functions remain elusive. Using a CAF-derived ECM model, we uncovered that iso3/iso4 are required to sustain TGFβ1-dependent CAF activation, secrete immunosuppressive cytokines, and produce a pro-tumoral ECM. Findings demonstrate a novel role for CAF palladin and suggest that iso3/iso4 regulate both redundant and specific tumor-supportive desmoplastic functions. This study highlights the therapeutic potential of targeting CAFs to restore fibroblastic anti-tumor activity in the pancreatic microenvironment.


Author(s):  
Xuefei Liu ◽  
Ziwei Luo ◽  
Xuechen Ren ◽  
Zhihang Chen ◽  
Xiaoqiong Bao ◽  
...  

Background: Pancreatic ductal adenocarcinoma (PDAC) is dominated by an immunosuppressive microenvironment, which makes immune checkpoint blockade (ICB) often non-responsive. Understanding the mechanisms by which PDAC forms an immunosuppressive microenvironment is important for the development of new effective immunotherapy strategies.Methods: This study comprehensively evaluated the cell-cell communications between malignant cells and immune cells by integrative analyses of single-cell RNA sequencing data and bulk RNA sequencing data of PDAC. A Malignant-Immune cell crosstalk (MIT) score was constructed to predict survival and therapy response in PDAC patients. Immunological characteristics, enriched pathways, and mutations were evaluated in high- and low MIT groups.Results: We found that PDAC had high level of immune cell infiltrations, mainly were tumor-promoting immune cells. Frequent communication between malignant cells and tumor-promoting immune cells were observed. 15 ligand-receptor pairs between malignant cells and tumor-promoting immune cells were identified. We selected genes highly expressed on malignant cells to construct a Malignant-Immune Crosstalk (MIT) score. MIT score was positively correlated with tumor-promoting immune infiltrations. PDAC patients with high MIT score usually had a worse response to immune checkpoint blockade (ICB) immunotherapy.Conclusion: The ligand-receptor pairs identified in this study may provide potential targets for the development of new immunotherapy strategy. MIT score was established to measure tumor-promoting immunocyte infiltration. It can serve as a prognostic indicator for long-term survival of PDAC, and a predictor to ICB immunotherapy response.


2019 ◽  
Author(s):  
Zhikai Wang ◽  
Ran Yan ◽  
Jiayun Li ◽  
Ya Gao ◽  
Philip Moresco ◽  
...  

AbstractHow pancreatic ductal adenocarcinoma (PDA) cells stimulate CXCR4 to exclude T cells and resist T cell checkpoint inhibitors is not known. Here, we find that CXCL12, the ligand for CXCR4 that is produced by the cancer-associated fibroblast, “coats” human PDA and colorectal cancer cells as covalent heterodimers with keratin 19 (KRT19). Modeling the formation of the heterodimer with three proteins shows that KRT19 binds CXCL12 and transglutaminase-2 (TGM2), and that TGM2 converts the reversible KRT19-CXCL12 complex into a covalent heterodimer. We validate this model by showing that cancer cells in mouse PDA tumors must express KRT19 and TGM2 to become coated with CXCL12, exclude T cells, and resist immunotherapy with anti-PD-1 antibody. Thus, PDA cells have a cell-autonomous means by which they capture CXCL12 to mediate immune suppression, which is potentially amenable to therapy.One Sentence SummaryCancer cells in pancreatic ductal adenocarcinoma use transglutaminase-2 to assemble a coating comprised of covalent CXCL12-keratin 19 heterodimers that excludes T cells and mediates resistance to inhibition of the PD-1 T cell checkpoint.


Author(s):  
Marlene Geyer ◽  
Karla Queiroz

Pancreatic Ductal Adenocarcinoma (PDAC), the most common pancreatic cancer type, is believed to become the second leading cause of cancer-related deaths by 2030 with mortality rates of up to 93%. It is often detected at a late stage due to lacking symptoms, and therefore surgical removal of the tumor is the only treatment option for patients. Only 20% of the tumors are resectable, mainly due to early metastasis. Therefore, for 80% of cases chemotherapeutic treatment is the leading therapy for patients. PDAC is characterized by high-density stroma which induces hypoxic conditions and high interstitial pressure. These factors impact carcinogenesis and progression of PDAC and support the formation of an immunosuppressive microenvironment that renders this tumor type refractory to immunotherapies. Most in vitro PDAC models have limited translational relevance, as these fail to recapitulate relevant aspects of PDAC complexity. Altogether, there is an urgent need for novel and innovative PDAC modeling platforms. Here, we discuss the relevance of microfluidic and organoid technologies as platforms for modeling bio- and physicochemical features of PDAC and as translational models that enable high-throughput phenotypic drug screenings, while also allowing for the development of novel personalized models used to identify treatment responsive patient subsets.


2021 ◽  
pp. molcanther.MCT-20-0144-E.2020
Author(s):  
Masakazu Hashimoto ◽  
John David Konda ◽  
Stephanie Perrino ◽  
Maria Celia Fernandez ◽  
Andrew M Lowy ◽  
...  

2020 ◽  
Vol 21 (9) ◽  
pp. 3345
Author(s):  
Michael Karl Melzer ◽  
Frank Arnold ◽  
Katja Stifter ◽  
Friedemann Zengerling ◽  
Ninel Azoitei ◽  
...  

Pancreatic ductal adenocarcinoma (PDAC) has still a dismal prognosis. Different factors such as mutational landscape, intra- and intertumoral heterogeneity, stroma, and immune cells impact carcinogenesis of PDAC associated with an immunosuppressive microenvironment. Different cell types with partly opposing roles contribute to this milieu. In recent years, immunotherapeutic approaches, including checkpoint inhibitors, were favored to treat cancers, albeit not every cancer entity exhibited benefits in a similar way. Indeed, immunotherapies rendered little success in pancreatic cancer. In this review, we describe the communication between the immune system and pancreatic cancer cells and propose some rationale why immunotherapies may fail in the context of pancreatic cancer. Moreover, we delineate putative strategies to sensitize PDAC towards immunological therapeutics and highlight the potential of targeting neoantigens.


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