Tumor Microenvironment Of Pancreatic Adenocarcinoma Research Articles

Abstract B014: Immuno-modulation of the tumor microenvironment of pancreatic adenocarcinoma following isotoxic high-dose stereotactic body radiotherapy (iHD-SBRT)

Abstract INTRODUCTION: Pancreatic ductal adenocarcinoma (PDAC) remains one of the deadliest tumors. Unlike other tumors, the progress of systemic therapies has been very slow, mainly due to the peculiar and resistant tumor microenvironment (TME) of PDAC. The addition of ablative stereotactic body radiation therapy (SBRT) in a total neoadjuvant strategy is promising for the treatment of localized PDAC and is currently being explored in several clinical trials. However, if radiation therapy possesses the ability to modulate the TME, the impact of high-dose SBRT is still poorly known in PDAC. Here, we aim to characterize by immunohistochemistry (IHC) and RNA sequencing (RNAseq) analysis the immuno-modulations of the TME following isotoxic high-dose stereotactic body radiotherapy (iHD-SBRT). MATERIAL: Paraffin-embedded residual tumoral tissues of 50 localized PDAC resected between 2011 and 2020 were used: seventeen patients had surgery first, seventeen received an induction chemotherapy with FOLFIRINOX (FFX) only and sixteen with FFX followed by an iHD-SBRT designed to individually maximize the dose prescribed to the tumor and vessels interfaces up to Dmax(0.5cc)<53Gy in 5 fractions. RESULTS: We found that although collagen deposition increases significantly after iHD-SBRT (COL1: 83.27 vs 78.60 vs 68.04%, p<0.001 for iHD-SBRT, FFX and treatment naïve cohort respectively), the intra-tumoral lymphocyte infiltration is globally not altered, including for cytotoxic CD8+ lymphocytes. Only the IHC expression of CD4+ T helper population is significantly decreased after iHD-SBRT. Using gene set enrichment analysis (GSEA) of the KEGG pathway, the IL-17 signaling pathway related to the T17 cells is particularly significantly increased after iHD-SBRT compared to FFX only. After iHD-SBRT, the IHC expression levels of FOXP3+ cells and PD-L1 are significantly increased. No difference is observed for CD68+ expression however, cell type enrichment analysis from our RNA-seq data using xCell algorithm shows that the M2-polarized CD68+ cells are increased after iHD-SBRT compared to FFX alone. PD-1 expression is significantly decreased after iHD-SBRT. Furthermore, RNAseq data revealed that iHD-SBRT is associated with significant enrichment in basaloid cells (p<0.0024), a subtype of basal–like cells associated with immunomodulatory stroma and better clinical outcomes. GSEA canonical pathway analysis further revealed metabolism-related pathways such as oxidative phosphorylation and gluthathione metabolism significantly enriched in iHD-SBRT treated group, suggesting the potential of mitochondrial inhibitors as candidates for combination therapy. CONCLUSIONS: iHD-SBRT is able to durably immuno-modulate the TME of PDAC. If the overall T-cell infiltration is preserved, we have identified some increased pro-tumoral cells and pathways after iHD-SBRT that could improve the development of better-oriented combination trials involving high-dose SBRT. Citation Format: Christelle Bouchart, Oier Azurmendi Senar, Julie Navez, Laurine Verset, Anaïs Boisson, Matthieu Hein, Nicky D’Haene, Dirk Van Gestel, Luigi Moretti, Pieter Demetter, Jean-Baptiste Bachet, Karen Willard-Gallo, Rémy Nicolle, Tatjana Arsenijevic, Jean-Luc Van Laethem. Immuno-modulation of the tumor microenvironment of pancreatic adenocarcinoma following isotoxic high-dose stereotactic body radiotherapy (iHD-SBRT) [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 B014.

Analysis and validation of the potential of the MYO1E gene in pancreatic adenocarcinoma based on a bioinformatics approach.

Pancreatic adenocarcinoma (PAAD) is a common digestive cancer, and its prognosis is poor. Myosin 1E (MYO1E) is a class I myosin family member whose expression and function have not been reported in PAAD. In the present study, bioinformatics analysis was used to explore the expression levels of MYO1E in PAAD and its prognostic value, and the immunological role of MYO1E in PAAD was analyzed. The study revealed that a variety of malignancies have substantially increased MYO1E expression. Further investigation demonstrated that PAAD tissues exhibited greater levels of MYO1E mRNA and protein expression than normal tissues. High MYO1E expression is associated with poor prognosis in patients with PAAD. MYO1E expression was also associated with pathological stage in patients with PAAD. Functional enrichment analysis demonstrated that MYO1E was linked to multiple tumor-related mechanisms in PAAD. The pancreatic adenocarcinoma tumor microenvironment (TME) was analyzed and it was revealed that MYO1E expression was positively associated with tumor immune cell infiltration. In addition, MYO1E was closely associated with some tumor chemokines/receptors and immune checkpoints. In vitro experiments revealed that the suppression of MYO1E expression could inhibit pancreatic adenocarcinoma cell proliferation, invasion and migration. Through preliminary analysis, the present study evaluated the potential function of MYO1E in PAAD and its function in TME, and MYO1E may become a potential biomarker for PAAD.

Comprehensive Analysis of PPMs in Pancreatic Adenocarcinoma Indicates the Value of PPM1K in the Tumor Microenvironment.

Early metastasis and resistance to traditional therapy are responsible for the poor prognosis of pancreatic adenocarcinoma patients. Metal-dependent protein phosphatases (PPMs) have been proven to play a crucial role in the initiation and progression of various tumors. Nevertheless, the expression and function of distinct PPMs in pancreatic adenocarcinoma have not been fully elucidated. In this study, we investigated the mRNA expression level, prognostic value, and the relationship between the expression of PPMs and the tumor microenvironment in pancreatic adenocarcinoma using Oncomine, TCGA and GTEx, GEO, Kaplan-Meier plotter, STRING, GeneMANIA, and HPA databases and R packages. GO and KEGG analysis revealed that PPMs and their differential co-expression genes are attributed to cell-cell adhesion and immune cell infiltration. Among these, PPM1K was downregulated in the tissue and peripheral blood of PAAD patients, whose expression level was negatively related to poor prognosis. Further to this, PPM1K was found to play a role in the epithelial-mesenchymal transition and immune infiltration. ROC curves showed that PPM1K had a good predictive value for pancreatic adenocarcinoma. The knockdown of PPM1K markedly promoted the proliferation and migration of pancreatic cancer cells, confirming its role in tumor suppressor activity in PAAD. This study demonstrates the potential clinical utility of PPM1K in tumor immunotherapy and brings about novel insights into the prognostic value of PPM1K in pancreatic adenocarcinoma.

Multi-omic analyses of changes in the tumor microenvironment of pancreatic adenocarcinoma following neoadjuvant treatment with anti-PD-1 therapy.

Successful pancreatic ductal adenocarcinoma (PDAC) immunotherapy necessitates optimization and maintenance of activated effector Tcells (Teff). We prospectively collected and applied multi-omic analyses to paired pre- and post-treatment PDAC specimens collected in a platform neoadjuvant study of granulocyte-macrophage colony-stimulating factor-secreting allogeneic PDAC vaccine (GVAX) vaccine± nivolumab (anti-programmed cell death protein 1 [PD-1]) to uncover sensitivity and resistance mechanisms. We show that GVAX-induced tertiary lymphoid aggregates become immune-regulatory sites in response to GVAX+ nivolumab. Higher densities of tumor-associated neutrophils (TANs) following GVAX+ nivolumab portend poorer overall survival (OS). Increased Tcells expressing CD137 associated with cytotoxic Teff signatures and correlated with increased OS. Bulk and single-cell RNA sequencing found that nivolumab alters CD4+ Tcell chemotaxis signaling in association with CD11b+ neutrophil degranulation, and CD8+ Tcell expression of CD137 was required for optimal Tcell activation. These findings provide insights into PD-1-regulated immune pathways in PDAC that should inform more effective therapeutic combinations that include TAN regulators and Tcell activators.

Expression, oncological and immunological characterizations of BZW1/2 in pancreatic adenocarcinoma.

Background: Despite the progress in early diagnosis and treatment, prognosis of pancreatic adenocarcinoma (PAAD) is still poor. Basic leucine zipper and W2 domain-containing protein 1 (BZW1) and protein 2 (BZW2) are attached to the basic leucine zipper (bZIP) superfamily. Recently, BZW1 was identified as an important role in glycolysis of PAAD. However, the comprehensive reports about BZW1/2 in PAAD are not sufficient. Methods: RNA-seq data in the Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases were retrospectively analyzed. We explored the expression of BZW1/2 in PAAD tissues and the associations between BZW1/2 and prognosis. In addition, the potential roles of BZW1/2 in tumor microenvironment (TME) of PAAD were analyzed. Finally, clinicopathological data of 49 patients with PAAD in our institution were collected. Immunohistochemistry was used to determine the expression of BZW1/2 in PAAD samples. Results: BZW1 and BZW2 were upregulated in PAAD tissues compared to normal tissues (p < 0.05). The expression of BZW1/2 were not significantly correlated with gender, grade and stage of PAAD (p > 0.05). High expression of BZW2 was an independent predictor for poor prognosis of PAAD (HR 1.834, 95%CI 1.303–2.581, p = 0.001). And a nomogram to predict overall survival (OS) of PAAD was established with a C-index of 0.685. BZW1 and BZW2 expression were positively associated with T cell mediated immune response to tumor cell and Th2 cells in xCell database. Tumor Immune Single-Cell Hub (TISCH) analyses indicated that BZW1 and BZW2 were mainly expressed in B cells and malignant cells. External cohort furtherly validated that high expression of BZW1 and BZW2 were predictors for poor prognosis of PAAD. Conclusion: We found that BZW1 and BZW2 are highly expressed in malignant cells and B cells in the TME of PAAD. BZW2 is an independent predictor for OS of PAAD. BZW1 and BZW2 expression are positively associated with T cell mediated immune response to tumor cell and Th2 cells in PAAD.

Multi-Omics Analyses of Changes in the Tumor Microenvironment of Pancreatic Adenocarcinoma Following Neoadjuvant Treatment With Anti-PD-1 Antibody

Multi-Omics Analyses of Changes in the Tumor Microenvironment of Pancreatic Adenocarcinoma Following Neoadjuvant Treatment With Anti-PD-1 Antibody

The heterogeneity of CAFs and immune cell populations in the tumor microenvironment of pancreatic adenocarcinoma

Over the past decade, researchers have identified and characterized the diverse cell populations within the tumor microenvironment of pancreatic cancer. The interplay between these cells in the TME either promotes or inhibits the malignant behavior of pancreatic cancer cells. Cancer-associated fibroblasts, previously thought to be one main subset, can now be broadly subclassified into three main types: inflammatory, myofibroblastic, and antigen-presenting, with the former and the latter two exerting pro-tumoral and anti-tumoral functions, respectively. Myeloid cells include myeloid-derived suppressor cells and tumor-associated macrophages. Myeloid-derived suppressor cells can be further divided into polymorphonuclear and monocytic and exhibit pro-tumoral activities. Tumor-associated macrophages exhibit M1 (anti-tumoral) or M2 (pro-tumoral) phenotypes, which are present in a dynamic fashion between the two phenotypes. Other constituents of the immune make-up of the tumor microenvironment include T and B cells and less described subsets which include natural killer cells, γδ T cells, and group 2 innate lymphoid cells. This review provides an overview of the studies that lead to the discovery of those cellular populations and highlights the recent efforts to utilize them as therapeutic targets in pancreatic cancer.

High Matrix Metalloproteinase 28 Expression is Associated with Poor Prognosis in Pancreatic Adenocarcinoma

PurposePancreatic adenocarcinoma (PAAD) is a devastating disease with high mortality and morbidity. Matrix metalloproteinase 28 (MMP28) has been associated with carcinogenesis of many human cancers. However, little is known about the potential prognostic value and underlying regulatory mechanisms of MMP28 in PAAD.MethodsThe relationship between MMP28 expression level and various clinicopathological parameters was analyzed in TCGA-PAAD cohorts. MMP28-correlated genes in the TCGA-PAAD cohort were identified and enrichment analysis according to the Gene Ontology and Kyoto Encyclopedia of Genes and Genomes was conducted using LinkedOmics. Protein–protein interaction and transcription factors-miRNA co-regulatory networks were constructed with the use of NetworkAnalyst. Then, the distribution of immune cells related to MMP28 expression in blood was analyzed using the Human Protein Atlas, and the tumor microenvironment of PAAD was analyzed by the TIMER 2.0 database. To investigate the biological function of MMP28 in PAAD, siRNA was constructed to knock down the MMP28 gene in vitro.ResultsHigh MMP28 expression is associated with poor overall survival and disease-free survival in PAAD patients. The expression of MMP28 in PAAD is most significantly correlated with KRT19, IL1RN, and ANXA2 genes. Network analysis revealed that MIR-181 family, TAFs, and CDC6 are potential regulators of MMP28. Furthermore, naive CD4+ T cell, naive CD8+ T cell, and mucosal-associated invariant T cell enrichment in blood were correlated with MMP28 expression. Furthermore, high MMP28 expression was correlated with a decrease in B cell, naive CD4+ T cell, naive CD8+ T cell, and endothelial cell presence in the tumor microenvironment in PAAD. Finally, genetic knockdown of MMP28 could restrain the proliferation, migration, and invasion of PAAD cells.ConclusionOur findings indicate that high MMP28 expression in PAAD is associated with cancer progression, invasion, and metastasis. Hence, MMP28 might serve as an independent prognostic biomarker and a prospective therapeutic target for PAAD.

Anti-tumor effect of statin on pancreatic adenocarcinoma: From concept to precision medicine.

A statin is a cholesterol-lowering agent, which inhibits HMG-CoA (3-hydroxy-3-methylglutaryl-coenzyme A) reductase and subsequently reduces the cholesterol precursor, and was first used commercially in 1987. The concept of cholesterol restriction leading to cancer cell dysfunction was proposed in 1992. The interruption of different signaling pathways has been proved in preclinical experiments to elucidate the anti-tumor mechanism of statins in pancreatic adenocarcinoma. Observational studies have shown that the clinical use of statins is beneficial in patients with pancreatic adenocarcinoma, including a chemoprevention effect, post-surgical resection follow-up and therapeutic prognosis of advanced cancer stage. Arrest of the cancer cell cycle by the combined use of gemcitabine and statin was observed in a cell line study. The effect of microbiota on the tumor microenvironment of pancreatic adenocarcinoma is a new therapeutic approach as statins can modulate the gut microbiota. Hence, further randomized trials of statins in pancreatic adenocarcinoma treatment will be warranted with application of precision medicine from microbiota-derived, cell cycle-based and signaling pathway-targeted research.

Isolation of Proximal Fluids to Investigate the Tumor Microenvironment of Pancreatic Adenocarcinoma

Isolation of Proximal Fluids to Investigate the Tumor Microenvironment of Pancreatic Adenocarcinoma

Isolation of Proximal Fluids to Investigate the Tumor Microenvironment of Pancreatic Adenocarcinoma.

Pancreatic adenocarcinoma (PDAC) is the fourth leading cause of cancer-related death, and soon to become the second. There is an urgent need of variables associated to specific pancreatic pathologies to help preoperative differential diagnosis and patient profiling. Pancreatic juice is a relatively unexplored body fluid, which, due to its close proximity to the tumor site, reflects changes in the surrounding tissue. Here we describe in detail the intraoperative collection procedure. Unfortunately, translating pancreatic juice collection to murine models of PDAC, to perform mechanistic studies, is technically very challenging. Tumor interstitial fluid (TIF) is the extracellular fluid, outside blood and plasma, which bathes tumor and stromal cells. Similarly to pancreatic juice, for its property to collect and concentrate molecules that are found diluted in plasma, TIF can be exploited as an indicator of microenvironmental alterations and as a valuable source of disease-associated biomarkers. Since TIF is not readily accessible, various techniques have been proposed for its isolation. We describe here two simple and technically undemanding methods for its isolation: tissue centrifugation and tissue elution.

The tumor microenvironment of pancreatic adenocarcinoma and immune checkpoint inhibitor resistance: a perplex relationship.

Pancreatic cancer is one of the most aggressive cancers with a high mortality rate even among patients with early-stage disease. Although recent studies with novel therapeutic approaches have led to modest improvement in survival outcomes, limited progress is achieved for the use of immunotherapeutics in this challenging cancer. Immune checkpoint inhibitors, thus far, single-agent or in combination, have not yielded significant improvement in survival outcomes except in mismatch repair-deficient pancreatic cancer. The tumor microenvironment of pancreatic cancer has been considered as an attractive target for over a decade based on preclinical studies that suggested it may adversely affect drug delivery and antitumor immunity. In this review article, we elaborate on the biology of pancreatic cancer microenvironment, its highly complicated interaction with cancer cells, and the immune system. We also discuss plausible explanations that led to the failure of immune checkpoint inhibitors as therapeutic agents and the potential impacts of pancreatic cancer stroma on these negative studies.

Abstract 136: Modeling of prognostication and immune profiling, based on genomic analysis in the tumor microenvironment of pancreatic adenocarcinoma via machine learning

Abstract The extensive tumor microenvironment (TME) in pancreatic adenocarcinoma (PAD) modulates cancer progression and impact prognosis. Although gene analysis has enhanced understanding of cancer biology, few models exist to model prognosis in association with mRNA expression in the TME. Clinical outcomes data and mRNA-seq of 156 and 64 patients (pts) were obtained from TCGA and Bailey at el. [1] for testing and validation, respectively. Expressivity of 191 genes enriched in cellular and structural elements of TME and clinical data were analyzed by multivariate nonlinear regression aided by machine learning for confined optimization with model-data error minimization. Statistics including Kaplan-Meier (KM), Cox Hazard (CH), and correlation analysis was used. Most pts (85.89% and 85.94%, respectively) were in stage II, and pts in stage I/III/IV were excluded. Prognostication was modeled with higher risk score (RS) representing worse prognosis: RS = -7.6526 x (Age-5.5679) + 0.0813 x (P/G0.3677) + 0.7069, where P/G is a ratio of genes associated with poor to good prognosis (Table 1). Based on RS, pts were clustered into 2 groups (high and low RS) with 2 KM curves showing p&amp;lt;0.0001 and p=0.014 in test and validation sets. Immune profiling of high and low RS groups in both test and validation sets shows that in low RS group, genes related to both immune activation (IA) and inhibition (II) (Table 2) are highly co-expressed, implying that co-expression of IA and II contributes to PAD’s poor prognosis even in pts with immune system activation. In high RS group, genes related to cancer stem cells (CD44 and EPCAM) significantly contributed to poor prognosis. Machine learning-assisted modeling of RS and gene analysis suggest that IA genes are suppressed by co-expression of high degree of II, contributing to poor prognosis in PAD. RS enables prognostication of pts encountered in the clinic when genomic profiles are provided. [1] Nature 531, 47-52 (2016). Table 1genes associated with good and poor prognosis out of 191 genes (identification via KM and CH with p&amp;lt;0.05)Good prognosisFCRL3, LILRA4, IL3RA, IL10, CCL22, DOK3, CXCR4, PDGFA, ICOSLG, TNFRSF4Poor prognosisTNFSF10, CD44 Table 2gene groups of immune activation (IA) and immune inhibition (II)IA gene groupscytotoxic T, B, NK, T-helper 1 cells, IFN, cytolytic activity, T cell co-stimulation, and antigen presentationII gene groupsregulatory T cells, desmoplasia, immunosuppressive chemokines, immune checkpoints, angiogenesis, cancer stem cells, epithelial-mesenchymal transition, and neutrophils Note: This abstract was not presented at the meeting. Citation Format: Sunyoung S. Lee, Seok Joon Kwon, Ahmed Elkhanany, Andrew Baird, Seongwon Lee, Jillian Dolan, Stuart Baird, Shinyoung Park, Renuka Iyer. Modeling of prognostication and immune profiling, based on genomic analysis in the tumor microenvironment of pancreatic adenocarcinoma via machine learning [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 136.

Multiplex immunophenotyping reveals unique characteristics of pancreatic neoplasms

Introduction: The tumor microenvironment of pancreatic adenocarcinoma (PDA) is characterized by a dense stroma and infiltration with primarily immunosuppressive cells. While much is known about the immune cellular changes occurring during tumorigenesis in murine models of PDA, data in humans is lacking. We sought to identify difference in the immune microenvironment of neoplastic and pre-neoplastic lesions using multiplex immunohistochemistry. Method: Operative pancreatic tissue was collected from 289 patients undergoing pancreatectomy at the University of Michigan. Slides were prepared from formalin-fixed, paraffin embedded tissue which were subjected to serial rounds of primary and secondary antibody staining followed by tyramide signal amplification. Result: Analysis was performed on tissue from patients with normal pancreata (n=42), mucinous cystic neoplasms (MCN;n=22), intraductal papillary mucinous neoplasms (IPMN;n=80), pancreatic intraepithelial neoplasia (PanIN;n=37) and PDA (n=108). IPMNs and normal pancreata had significantly more epithelial cells when compared to MCN and PDA. In IPMNs, these cells were more frequently positive for the checkpoint inhibitor PD-L1 (mean = 16.4%; p<0.0001). Mucinous lesions (MCN and IPMN) had significantly more antigen presenting cells than other lesion types (mean = 4.6% and 3.2%, respectively; p=0.0048). While there were no differences in relative infiltration of cytotoxic T lymphocytes, PDA had a far greater overall and relative number of regulatory T lymphocytes (Treg) (mean = 17%; p<0.0001). The accumulation of Tregs paralleled progression of neoplasia with increasing infiltration in normal pancreata, PanIN and PDA (1%, 3%, 17%, respectively; p<0.0001). Conclusion: A better understanding of the immune microenvironment of PDA is needed for the development of novel immunotherapeutic approaches. These data demonstrate an accumulation of Tregs as tumors progress from preinvasive to invasive cancer, suggesting a potential avenue for intervention.

Automation of quantifying and mapping of stromal and malignant cells in pancreatic adenocarcinoma using deep learning.

266 Background: The characteristic histological feature of pancreatic adenocarcinoma (PAD) is extensive desmoplasia alongside leukocytes and cancer-associated fibroblasts. Desmoplasia is a known barrier to the absorption and penetration of therapeutic drugs. Stromal cells are key elements for a clinical response to chemotherapy and immunotherapy, but few models exist to analyze the spatial and architectural elements that compose the complex tumor microenvironment in PAD. Methods: We created a deep learning algorithm to analyze images and quantify cells and fibrotic tissue. Histopathology slides of PAD patients (pts) were then used to automate the recognition and mapping of adenocarcinoma cells, leukocytes, fibroblasts, and degree of desmoplasia, defined as the ratio of the area of fibrosis to that of the tumor gland. This information was correlated with mutational burden, defined as mutations (mts) per megabase (mb) of each pt. Results: The histopathology slides (H&amp;E stain) of 126 pts were obtained from The Cancer Genome Atlas (TCGA) and analyzed with the deep learning model. Pt with the largest mutational burden (733 mts/mb, n = 1 pt) showed the largest number of leukocytes (585/mm2). Those with the smallest mutational burden (0 mts/mb, n = 16 pts) showed the fewest leukocytes (median, 14/mm2). Mutational burden was linearly proportional to the number of leukocytes (R2 of 0.7772). The pt with a mutational burden of 733 was excluded as an outlier. No statistically significant difference in the number of fibroblasts, degree of desmoplasia, or thickness of the first fibrotic layer (the smooth muscle actin-rich layer outside of the tumor gland), was found among pts of varying mutational burden. The median distance from a tumor gland to a leukocyte was inversely proportional to the number of leukocytes in a box of 1 mm2 with a tumor gland at the center. Conclusions: A deep learning model enabled automated quantification and mapping of desmoplasia, stromal and malignant cells, revealing the spatial and architectural relationship of these cells in PAD pts with varying mutational burdens. Further biomarker driven studies in the context of immunotherapy and anti-fibrosis are warranted.

Abstract 4941: Lysophosphatidic acid receptor signaling and pancreatic adenocarcinoma tumor microenvironment

Abstract Introduction: Changes in lipid biosynthesis has attracted significant attention in the study of cancer. Its value in our understanding of pancreatic cancer has not yet been realized. This study examined lysophosphatidic acid (LPA) variant biosynthesis in patients with stage II-III pancreatic ductal adenocarcinoma (PDAC), evaluating serum, bile, and tissue levels of LPA, its receptors, and downstream metabolites. LPA, a product of phospholipase D activity of the enzyme autotaxin (ATX) is a potent mitogenic agent. Data suggests that changes in lipid biosynthesis contribute to the tumor microenvironment in PDAC. Methods: PDAC, matched adjacent non-malignant tissues, gall bladder bile and serum samples were collected from patients with Stage II-III pancreatic cancer at the time of surgery. Control bile and serum were collected from patients undergoing cholecystectomy for benign disease and living renal donors respectively. Results: Serum and biliary LPA levels were increased in patients with PDAC when compared to controls. ATX activity, and LPA receptors, LPAR1, LPAR2, and LPAR5 were greater in PDAC adjacent pancreatic tissue when compared to PDAC tissue. In contrast, TNFα receptors TNFα1 and TNFα2 and LPA receptor LPAR3 receptor expression was greater in PDAC lesions when compared to adjacent tissue. Conclusion: PDAC patients display a modified LPA biosynthesis profile, when compared to non-PDAC patients, potentially providing a paracrine-signaling cascade to promote pancreatic tumorigenesis through increased expression of mitogenic cytokines and growth factors. Citation Format: Nicholas J. Skill, Mary A. Maluccio. Lysophosphatidic acid receptor signaling and pancreatic adenocarcinoma tumor microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4941. doi:10.1158/1538-7445.AM2017-4941

Shifting paradigm of developing biologics for the treatment of pancreatic adenocarcinoma.

Pancreatic adenocarcinoma is still widely considered as a deadly disease even though there are substantial therapeutic developments in the past decade. Using combinational chemotherapy regimens, represented by gemcitabine plus nab-paclitaxel and FOLFIRINOX, was able to improve overall survival in patients with advanced disease to a limited extent. It has been a challenge to develop targeted therapies that are focused on the neoplasm cells of pancreatic adenocarcinoma. Recently, targeting the stroma and immune compartments of pancreatic adenocarcinoma has shown promising results. The paradigm of biologics drug development therefore has been shifted by extending to these exciting areas. Although some of the preclinical and clinical researches in targeting the tumor microenvironment of pancreatic adenocarcinoma have shown promising results, others have resulted in controversial findings. Both comprehensive and in-depth researches on the basic science of the tumor microenvironment of pancreatic adenocarcinoma are thus warranted for the development of effective biologics that target the tumor microenvironment. Moreover, an ideal treatment for pancreatic adenocarcinoma shall be a combination of targeting both neoplastic cells and the tumor microenvironment.

Ibrutinib + durvalumab (MEDI4736) in patients (pts) with relapsed or refractory (R/R) pancreatic adenocarcinoma (PAC): A phase Ib/II multicenter study.

TPS484 Background: PAC is an aggressive disease characterized by poor prognosis and is inadequately treated with available therapies. Ibrutinib is a first-in-class, oral inhibitor of Bruton’s tyrosine kinase (BTK) that was shown to inhibit mast cell degranulation in the PAC tumor microenvironment with subsequent inhibition of tumor cell proliferation, angiogenesis, and collagen deposition (Chang, 2011; Masso-Valles, 2015). Durvalumab, a human IgG1 monoclonal antibody (mAb), binds PD-L1 with high affinity and prevents interaction with PD-1 and CD80 (IC50values of 0.1 nM and 0.04 nM, respectively), facilitating antitumor T-cell responses (Stewart, 2015). Ibrutinib + anti-PD-L1 mAbs inhibited tumor cell growth and led to enhanced anti-tumor immune responses in mouse models (Sagiv-Barfi, 2015). This trial (PCYC-1135; NCT02403271) evaluates the safety and efficacy of ibrutinib + durvalumab in pts with PAC, breast cancer, and non-small cell lung cancer. Study details presented here focus on the cohort of pts with PAC. Methods: Key inclusion criteria include pathologically confirmed PAC, R/R disease (failed ≥ 1 prior systemic therapy), stage III-IV disease, ≥ 1 measurable lesion by RECIST 1.1 criteria, and adequate hematologic, renal, hepatic function. Key exclusion criteria include any history of central nervous system involvement; prior treatment with ibrutinib/BTK inhibitor or treatment with antibodies targeting PD-1, PD-L1, PD-L2, CD137, or CTLA-4; history of allogeneic organ transplant; or treatment with a strong cytochrome P450 3A inhibitor. Primary objectives are safety, tolerability, and efficacy of the combination; secondary objectives include pharmacokinetics and pharmacodynamic assessments of the combination. The phase 1b portion will assess the dose-limiting toxicities (DLTs) and determine the recommended phase 2 dose (RP2D). Ibrutinib will be administered at the standard dose with the potential for dose level reductions if DLTs occur in combination with durvalumab. After RP2D determination, enrollment in phase 2 will occur until a total of 130-160 pts (across all 3 disease cohorts) are treated. Enrollment for phase 1b began in March 2015. Clinical trial information: NCT02403271.

Role of the tumor microenvironment in pancreatic adenocarcinoma

Pancreatic cancer is a devastating disease with proclivity for early metastasis, which accounts for its poor prognosis. The clinical problem of pancreatic cancer is its resistance to conventional therapies, such as chemotherapy or radiation. Based upon these challenges, the focus of research on pancreatic cancer has shifted gradually towards the tumor microenvironment. The cancer microenvironment consists of various components, including fibroblasts, endothelial cells, immune cells, and endocrine cells, that interact with each other, and with the cancer cells in a complex fashion. Evidence is accumulating that the cancer microenvironment plays an active role in disease progression, and efforts are being made to target this interplay between cancer cells and host cells, to improve the prognosis of the disease. In the present review, we describe the cellular microenvironment of pancreatic ductal adenocarcinoma (PDA), the major type of pancreatic cancer. Our hope is that a better understanding of the cellular microenvironment of PDA will eventually lead to better treatments for this disease.

Novel aspects of preoperative chemoradiation therapy improving anti‐tumor immunity in pancreatic cancer

Pancreatic cancer is an aggressive cancer with poor prognosis. Little is known about the immune response in the tumor microenvironment after chemotherapy for initially unresectable tumor. The purpose of this study was to investigate the immunological effects of chemoradiation therapy in the tumor microenvironment of pancreatic adenocarcinoma. Seventeen patients with pancreatic adenocarcinoma with and without preoperative chemoradiation therapy were retrospectively analyzed using immunohistochemical methods for HLA class I heavy chain, CD4(+), CD8(+), CD45RO(+) and Foxp3(+) T cell infiltrations. Seven of the 17 study patients received preoperative chemoradiation therapy. There were no statistically significant differences in the number of CD4(+) and CD8(+) T cell infiltrations in the tumor microenvironment. However, the number of Foxp3(+) T cell infiltrations was significantly lower in the neoadjuvant chemoradiation therapy group. The HLA class I expression status was the same between the two groups. In conclusion, preoperative chemoradiation therapy in pancreatic adenocarcinoma is useful for reducing regulatory T cell levels in combination with its direct cytotoxic effects.