Pancreatic Ductal Adenocarcinoma Immunotherapy Research Articles

Pancreatic ductal adenocarcinoma: Treatment hurdles, tumor microenvironment and immunotherapy.

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal diseases, with an average 5-year survival rate of less than 10%. Unfortunately, the majority of patients have unresectable, locally advanced, or metastatic disease at the time of diagnosis. Moreover, traditional treatments such as chemotherapy, surgery, and radiation have not been shown to significantly improve survival. Recently, there has been a swift increase in cancer treatments that incorporate immunotherapy-based strategies to target all the stepwise events required for tumor initiation and progression. The results in melanoma, non-small-cell lung cancer and renal cell carcinoma are very encouraging. Unfortunately, the application of checkpoint inhibitors, including anti-CTLA4, anti-PD-1, and anti-PD-L1 antibodies, in pancreatic cancer has been disappointing. Many studies have revealed that the PDAC microenvironment supports tumor growth, promotes metastasis and consists of a physical barrier to drug delivery. Combination therapies hold great promise for enhancing immune responses to achieve a better therapeutic effect. In this review, we provide an outline of why pancreatic cancer is so lethal and of the treatment hurdles that exist. Particular emphasis is given to the role of the tumor microenvironment, and some of the latest and most promising studies on immunotherapy in PDAC are also presented.

BxPC-3-Derived Exosomes Induce FOXP3+ Treg Through ATM-AMPK-Sirtuins Mediated FOXOs Nuclear Translocations

Immunotherapy in pancreatic ductal adenocarcinoma (PDAC) treatment faces serious challenges, due particularly to the poor immunogenicity of PDAC. Cancer cell-derived exosomes play important roles in damaging the immune system. However, the effects of pancreatic cancer-derived exosomes on T lymphocytes are unknown. Here we investigated changes in phenotypes and signal transduction pathways in exosomes-treated T lymphocytes. We identified the overexpression of immune checkpoint proteins PD-1, PD-L1, CTLA4, and Tim-3, and the enrichment of FOXP3 + Treg cluster in exosomes-treated T lymphocytes by CyTOF. RNA-sequencing and Gene Set Enrichment Analysis revealed that DNA damage response and metabolic pathways might be involved in exosomes-induced Tregs. ATM, AMPK, SIRT1, SIRT2, and SIRT6 were activated sequentially in exosomes-treated T lymphocytes and essential for exosomes-upregulated expressions of FOXO1A, FOXO3A and FOXP3. Our study reveals the impact and mechanism of pancreatic cancer cell-derived exosomes on T lymphocytes and may provide insights into developing immunotherapy strategies for PDAC treatment.

Overexpression of Mesothelin in Pancreatic Ductal Adenocarcinoma (PDAC)

Purpose: Pancreatic ductal adenocarcinoma (PDAC) with difficulty in early diagnosis does not respond well to conventional treatments and has not occurred significant improvement in the overall 5-year survival rates. Mesothelin (MSLN) is a tumor differentiation antigen expressed in several solid neoplasms and a limited number of healthy tissues. Its selective expression on malignant cells makes it an interesting candidate for investigation as a diagnostic and prognostic biomarker and as a therapeutic target. In this study, we detected the expression of MSLN in PDAC and analyzed the correlation between the expression of MSLN and clinicopathological data, so as to provide more theoretical basis for the role of MSLN in the diagnosis and treatment of PDAC.Patients and methods: Cancer and para-cancer tissues of 24 cases with PDAC were assessed by standardized immunohistochemical (IHC) detection with two kinds of anti-MSLN antibodies (EPR4509 and EPR19025-42) to detect their positive expression rates and study the correlation between the expression of MSLN and the clinicopathological data.Results: The two anti-MSLN antibodies of cancer tissues showed positive expression with tan yellow or tan brown granules diffusely distributed on the cell membrane in 22 of 24 cases with PDAC (positive rate of 91.67%), and the positive expression of the two antibodies EPR4509 and EPR19025-42 was completely consistent in all tissue samples. No expression of the two anti-MSLN antibodies was found in para-cancer tissues and the difference was statistically significant (χ2=40.615, p=0.000, p<0.05) when compared with PDAC tissues. There was no significant correlation between MSLN expression and clinicopathological data, such as gender, tumor size, location, pathological stage, differentiation degree and lymph node metastasis (p>0.05).Conclusion: MSLN was highly expressed in PDAC tissues, but not in paracancerous tissues. There was no significant correlation between MSLN expression and clinicopathological factors. The overexpression of MSLN may have promising prospects in diagnosis, targeted therapy and immunotherapy of PDAC.

CXCL5 overexpression predicts a poor prognosis in pancreatic ductal adenocarcinoma and is correlated with immune cell infiltration.

Background: C-X-C motif chemokine 5 (CXCL5) is an important attractant for immune cell accumulation in tumor tissues. Recent evidence has shown that CXCL5 could promote carcinogenesis and cancer progression in a variety of cancer types. However, the relationships between CXCL5, immune cell infiltration and pancreatic ductal adenocarcinoma (PDAC) remain largely unknown. This study aimed to explore the role and regulative mechanism of CXCL5 in PDAC carcinogenesis.Materials and Methods: The expression of CXCL5 in PDAC was analyzed based on online databases and tissue microarray staining, and Western blotting of CXCL5 in PDAC cell lines and patient samples. The correlation between CXCL5 expression and clinicopathological features, prognosis and immune cell infiltration in tumor tissues was analyzed.Results: High expression of CXCL5 was observed both in PDAC tumor tissue and PDAC cell lines, compared to normal pancreas tissues and normal ductal epithelium cells. High CXCL5 expression in tumor tissues was positively correlated with an advanced T stage (p=0.036), a positive tumor lymph node metastasis (p=0.014), a poor differentiation status (p=0.003) and a poor prognosis (p=0.001). Combination of CA242 and CXCL5 expression (p<0.0001) served as a better prognostic factor than CA242 alone (p=0.006). In addition, PDAC patients with high CXCL5 expression had more intratumoral M2 polarized macrophages (p=0.0248), neutrophils (p=0.0068) and IgG+ plasma cells (p=0.0133) than patients with low CXCL5 expression.Conclusions: The expression of CXCL5 is elevated in pancreatic cancer cells. High CXCL5 expression is positively correlated with poor survival and the increased infiltration of several types of immune suppressive cells. Thus, CXCL5 could be a promising therapeutic target for PDAC immunotherapy.

Cold Atmospheric Plasma-Treated PBS Eliminates Immunosuppressive Pancreatic Stellate Cells and Induces Immunogenic Cell Death of Pancreatic Cancer Cells.

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive cancers with a low response to treatment and a five-year survival rate below 5%. The ineffectiveness of treatment is partly because of an immunosuppressive tumor microenvironment, which comprises tumor-supportive pancreatic stellate cells (PSCs). Therefore, new therapeutic strategies are needed to tackle both the immunosuppressive PSC and pancreatic cancer cells (PCCs). Recently, physical cold atmospheric plasma consisting of reactive oxygen and nitrogen species has emerged as a novel treatment option for cancer. In this study, we investigated the cytotoxicity of plasma-treated phosphate-buffered saline (pPBS) using three PSC lines and four PCC lines and examined the immunogenicity of the induced cell death. We observed a decrease in the viability of PSC and PCC after pPBS treatment, with a higher efficacy in the latter. Two PCC lines expressed and released damage-associated molecular patterns characteristic of the induction of immunogenic cell death (ICD). In addition, pPBS-treated PCC were highly phagocytosed by dendritic cells (DCs), resulting in the maturation of DC. This indicates the high potential of pPBS to trigger ICD. In contrast, pPBS induced no ICD in PSC. In general, pPBS treatment of PCCs and PSCs created a more immunostimulatory secretion profile (higher TNF-α and IFN-γ, lower TGF-β) in coculture with DC. Altogether, these data show that plasma treatment via pPBS has the potential to induce ICD in PCCs and to reduce the immunosuppressive tumor microenvironment created by PSCs. Therefore, these data provide a strong experimental basis for further in vivo validation, which might potentially open the way for more successful combination strategies with immunotherapy for PDAC.

IL-15/B7-H3 TriKEs-Based Immunotherapy for Pancreatic Ductal Adenocarcinoma

Kontos, Filippos MD; Kurokawa, Tomohiro MD, PhD; Vallera, Daniel A. PhD; Ferrone, Soldano MD, PhD; Ferrone, Cristina R. MD, FACS Author Information

Exosomes and the Future of Immunotherapy in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is a devastating disease, associated with a late diagnosis and a five-year survival rate of 8%. Currently available treatments fall short in improving the survival and quality of life of PDAC patients. The only possible curative option is still the surgical resection of the tumor. Exosomes are extracellular vesicles secreted by cells that transport proteins, lipids, and nucleic acids to other cells, triggering phenotypic changes in the recipient cells. Tumor cells often secrete increased amounts of exosomes. Tumor exosomes are now accepted as important players in the remodeling of PDAC tumor stroma, particularly in the establishment of an immunosuppressive microenvironment. This has sparked the interest in their usefulness as mediators of immunomodulatory effects for the treatment of PDAC. In fact, exosomes are now under study to understand their potential as nanocarriers to stimulate an immune response against cancer. This review highlights the latest findings regarding the function of exosomes in tumor-driven immunomodulation, and the challenges and advantages associated with the use of these vesicles to potentiate immunotherapy in PDAC.

Broadening the Impact of Immunotherapy to Pancreatic Cancer: Challenges and Opportunities

Pancreatic ductal adenocarcinoma (PDAC) is projected to become the second deadliest cancer in the United States by 2025, with 5-year survival at less than 10%. In other recalcitrant cancers, immunotherapy has shown unprecedented response rates, including durable remissions after drug discontinuation. However, responses to immunotherapy in PDAC are rare. Accumulating evidence in mice and humans suggests that this remarkable resistance is linked to the complex, dueling role of the immune system in simultaneously promoting and restraining PDAC. In this review, we highlight the rationale that supports pursuing immunotherapy in PDAC, outline the key barriers that limit immunotherapy efficacy, and summarize the primary preclinical and clinical efforts to sensitize PDAC to immunotherapy.

Combination immunotherapy and radiation therapy strategies for pancreatic cancer-targeting multiple steps in the cancer immunity cycle.

Pancreatic ductal adenocarcinoma (PDAC) is a deadly disease, with its mortality rate approaching its incidence rate every year. Accordingly, much interest has been generated in harnessing the immune system in order to improve survival outcomes for these patients. Pancreatic cancer is not thought to be as immunogenic as other cancers that have seen promising results with immune checkpoint inhibitors alone, therefore likely several targets within the cancer-immunity cycle will need to be employed for successful treatment. We sought to investigate both the current state of the field in immunotherapy in PDAC with a special emphasis on combined approaches with radiation therapy (RT). We also summarized ongoing clinical trials that are examining the use of radiotherapy with other immune-stimulating agents in the treatment of PDAC. A PubMed and clinicaltrials.gov search was conducted using the following search terms, either alone or in combination: "pancreatic cancer", "immunotherapy", and "abscopal effect". Open clinical trials were reviewed and included if they involved both RT and other immune-stimulating agents. Pancreatic cancers tend to reside within immune-suppressive tumor microenvironments (TME), express PD-L1, and secrete several immuno-suppressive agents, such as TGF-B, IL-10, indoleamine 2,3-dioxygenase, galectin-1. Whole-cell vaccine therapies, peptide and protein vaccines, dendritic cell vaccines, and vaccines with micro-organisms have been investigated by themselves with promising results. Open clinical trials are currently investigating the use of these vaccines, which increase antigen presentation, with treatments that stimulate release of tumor antigens including RT. There are currently at least 21 open clinical trials investigating the combination of RT with other immune-stimulating agents. The combination of RT and immunotherapy may be a promising avenue for PDAC treatment and deserves further research.

Pancreatic Cancer and Immunotherapy: Resistance Mechanisms and Proposed Solutions.

Pancreatic ductal adenocarcinoma (PDAC) continues to be one of the most aggressive and lethal diseases in the world. The success of immunotherapy in other types of malignancy has led to further trials to understand better the role of immunotherapy in PDAC. However, initial studies with immunotherapy, namely, the checkpoint inhibitors, in PDAC have not been met with the same outcomes. The purpose of this review is to identify and discuss the various resistance mechanisms of PDAC to immunotherapy (pancreatic stroma, genetic predisposition/epigenetics, and the immune inhibitory cells, cytokines, soluble factors, and enzymes that comprise the tumor microenvironment) and the solutions currently being studied to overcome them. Various preclinical and early clinical studies have shown that immunotherapy, especially checkpoint inhibitors, in PDAC may be efficacious as part of a multi-modal treatment, in combination with other therapies that target these resistance mechanisms. Several clinical trials are ongoing to explore this concept further.

Abstract 1005: Combination T cell receptor immunosequencing and multiplex immunohistochemistry reveal novel insights into the immune response to human pancreatic cancer

Abstract Background: Despite advancements in therapy, pancreatic ductal adenocarcinoma (PDA) remains an aggressive cancer with high mortality. It is characterized by dense inflammation, including many T cells; however, it is unclear whether these T cells signify true anti-tumor response. In the setting of disappointing results of immunotherapy in PDA, we sought to gain a deeper understanding of the intratumoral T cell response. Methods: With IRB approval, we obtained archival resected PDA tumors in paraffin embedded blocks from 54 patients and performed T cell receptor (TCR) immunosequencing on extracted DNA. Productive clonality was defined as 1-Pielou's evenness; TCR fraction was calculated from number of observed templates versus housekeeping genes. Multiplex immunohistochemistry (IHC) was performed on slides immediately adjacent to blocks sent for TCR sequencing using the PerkinElmer Vectra system. False H&amp;E images generated from autofluorescence signatures were analyzed by a pathologist to categorize peritumoral stroma versus lymphoid tissue. Image analysis was performed using FlowJo10, turning object fluorescence data into cytometric outputs. Correlation analysis between multiplex and TCR data was performed using Pearson's correlation. Results: Mean TCR fraction was 0.27, and mean clonality was 0.15 (typical peripheral blood clonality is 0.08). TCR fraction was positively correlated with clonality (R2=0.23, p=0.007), but there was no survival difference between high or low TCR fraction or clonality. 3.1 million individual cells within the peritumoral stroma were phenotyped in total using multiplex IHC; within the stroma, CD4 T cells, CD8 T cells, and macrophages made up on average 4.6%, 6.8%, and 2.0% of all cells analyzed. 35.6% of CD8 T cells were positive for PD-1, while 20.8% of CD4 cells were FOXP3+ regulatory T cells (Treg). TCR fraction correlated positively with infiltration of CD8+ (R2=0.28, p=0.03) and CD68+ (R2=0.27, p=0.03) cells, but not CD4 cells. Only CD8 cells which were PD-1- correlated positively with clonality (R2=0.26, p=0.04). The presence of Treg correlated very strongly with CD8+PD-1+ cells (R2=0.44, p=0.0004). Conclusion: Here we demonstrate a novel approach to describe the varying immunophenotypic landscape of human PDA depending on the clonal expansion of intratumoral T cells. T cell infiltration appear to be correlated mostly with CD8 T cells as well as the presence of macrophages. Patients with more clonal expansion also had more CD8 cells that lacked the exhaustion marker PD-1, and the presence of regulatory T cells accompanied environments where CD8 cells were positive for PD-1. These data suggest that cytotoxic T cell exhaustion is a phenomenon which may be regulated by Treg and have a negative impact on clonal expansion of intratumoral T cells in human PDA. Citation Format: Yongwoo David Seo, Florencia Jalikis, Xiuyun Jiang, Kevin M. Sullivan, Marissa Vignali, Harlan Robins, Venu G. Pillarisetty. Combination T cell receptor immunosequencing and multiplex immunohistochemistry reveal novel insights into the immune response to human pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1005.

Abstract 732: A practical strategy to pancreatic cancer immunotherapy using resected human tumor lysate vaccines remodeled to express α-gal epitopes

Abstract Cancer immunotherapy is a potential treatment for pancreatic ductal adenocarcinoma (PDAC) patients. As the predominant natural Ab found in humans, anti-Gal accounts for approximately 1% of immunoglobulins. The ligand of anti-Gal, “α-gal epitope (Galα1-3Galβ1-4GlcNAc-R),” is a major carbohydrate antigen, expressed by non-primate mammals, New World monkeys. One useful application of anti-Gal abundance is the enhancement of the immunogenicity of tumor-associated antigens (TAAs) that promote effective uptake by antigen-presenting cells (APCs). To develop an effective vaccine-based immunotherapy for PDAC, we hypothesized that resected tumor tissue lysates from patients might be an attractive source of PDAC-associated TAAs vaccination. This study presents a novel immunotherapy expressing α-gal epitopes using freshly obtained human PDAC tumor tissue homogenates from patients. Tumor and normal pancreatic tissue specimens were obtained from 10 patients at the time of surgical exploration for primary PDAC. To synthesize α-gal epitopes on either tumor membranes or normal pancreatic tissue membranes, we employed recombinant α1,3 galactosyltransferase (α1,3GT). PDAC membranes or normal pancreatic tissues were homogenized, and were incubated with UDP-Gal and α1,3GT. α1,3GT KO mice were immunized with pig tissues to produce anti-Gal Ab. The high anti-Gal KO mice were vaccinated by i.p. injection with unprocessed or processed PDAC tumor lysate (α-gal(-) PDAC-ly or α-gal(+) PDAC-ly). The high anti-Gal KO mice were also vaccinated with unprocessed normal or processed normal pancreatic tissue lysate (α-gal(-) N-ly or α-gal(+) N-ly). Effective synthesis of α-gal epitopes was demonstrated after processing of PDAC tumor lysates in Western blot analysis. α-gal(+) PDAC-ly vaccines elicited significant antibody production against multiple TAAs, assessed by ELISPOT (anti-MUC1; α-gal(-) PDAC-ly vs. α-gal(+) PDAC-ly=28.7 vs. 151.8 spots [P=0.0008], anti-mesothelin; α-gal(-) PDAC-ly vs. α-gal(+) PDAC-ly=36.5 vs. 97.2 spots [P=0.029]) and activated multiple tumor-specific T cells, assessed by ELISPOT (MUC1; α-gal(-) PDAC-ly vs. α-gal(+) PDAC-ly=146.0 vs. 828.0 spots [P=0.0009], mesothelin; α-gal(-) PDAC-ly vs. α-gal(+) PDAC-ly= 250.7 vs. 988.0 spots [P=0.021], α-gal(-) N-ly and α-gal(+) N-ly groups did not display significant spots.). To demonstrate in vivo effectiveness, splenocytes from vaccinated KO mice were prepared, and these isolated cells were transferred by i.p. injection into NOD/SCID mice. Then, live PANC1 cells were challenged with s.c. injection. The survival time of NOD/SCID mice received from α-gal(+) PDAC-ly groups was significantly extended (95.0 days) compared with α-gal(-) PDAC-ly groups (45 days, p&amp;lt;0.01). We conclude that α-gal(+) PDAC-ly vaccination may be a practical and effective new immunotherapeutic approach for treating PDAC. Citation Format: Masahiro Tanemura, Kenta Furukawa, Eiji Miyoshi, Hidetoshi Eguchi, Hiroaki Nagano, Katsuyoshi Matsunami, Satoshi Nagaoka, Manabu Mikamori, Kentaro Kishi, Hiroki Akamatsu, Masaki Mori, Yuichiro Doki. A practical strategy to pancreatic cancer immunotherapy using resected human tumor lysate vaccines remodeled to express α-gal epitopes [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 732.

Pancreatic Ductal Adenocarcinoma: A Strong Imbalance of Good and Bad Immunological Cops in the Tumor Microenvironment.

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive and lethal cancers with very few available treatments. For many decades, gemcitabine was the only treatment for patients with PDAC. A recent attempt to improve patient survival by combining this chemotherapy with FOLFIRINOX and nab-paclitaxel failed and instead resulted in increased toxicity. Novel therapies are urgently required to improve PDAC patient survival. New treatments in other cancers such as melanoma, non-small-cell lung cancer, and renal cancer have emerged, based on immunotherapy targeting the immune checkpoints cytotoxic T-lymphocyte-associated antigen 4 or programmed death 1 ligand. However, the first clinical trials using such immune checkpoint inhibitors in PDAC have had limited success. Resistance to immunotherapy in PDAC remains unclear but could be due to tissue components (cancer-associated fibroblasts, desmoplasia, hypoxia) and to the imbalance between immunosuppressive and effector immune populations in the tumor microenvironment. In this review, we analyzed the presence of “good and bad immunological cops” in PDAC and discussed the significance of changes in their balance.

Analyzing the efficacy and safety of immunotherapy in pancreatic ductal adenocarcinoma (PDA): A systematic review and meta-analysis.

512 Background: The tumor microenvironment in PDA is heterogeneous and immunosuppressive given the presence of regulatory T cells and exhausted effector T cells. Despite the upsurge of effective immunotherapeutic agents (IA) in other tumor types, the role in PDA remains unknown. We conducted a meta-analysis of IA in PDA. Methods: Following PRISMA guidelines, we searched PubMed/MEDLINE, Elsevier/Embase, Wiley/Cochrane Library and ClinicalTrials.gov. Articles were selected per the following criteria: (1) Study participants had a diagnosis of PDA; (2) An IA was used in the trial. Titles, abstracts and full text articles were reviewed by 2 independent reviewers; disagreements were resolved by a third. Data extraction and analysis were performed by 3 independent reviewers. Descriptive analysis, mean, median, confidence interval and forest plots were used for statistical analysis. Results: We found 20,792 studies through the database, 16,105 remained after duplicates were removed and 15,889 were excluded due to irrelevance. Strict inclusion criteria were applied to the full text of 216 articles. The most common reason for exclusion were conference abstracts (44%) and ongoing trials (16%). Fifty-four trials (39 metastatic (met), 12 adjuvant (Ad) and 3 neoadjuvant (nAd) met criteria for further analysis. Age range was 27-86 (median 61) and 52.3% were males. IA included cytokine therapy (33%), peptide vaccines (22%), dendritic cell vaccine (13%), oncolytic viruses (9%), CTLA-4 inhibitors (2%) and others. IA in met-PDA had a median overall survival (mOS) of 8.1 months (ms) and a disease control rate (DCR) of 55.4% (95% CI, 51.85-58.95). There was no statistical difference in DCR among IA subtypes (range 49-60%) (p = 0.22). The mOS of Ad-PDA trials was 25 ms (historically comparable to gemcitabine, p = 0.75) and 18 ms for nAd-PDA. The most common Gr1/2 toxicities were skin reactions, fever, and chills and Gr3/4 were cytopenias, diarrhea, and mucositis. One death occurred due to neutropenic sepsis. Conclusions: IA demonstrates modest efficacy in the treatment of met-PDA albeit exhibits a favorable toxicity profile. Many trial results are available only in abstract format and some are ongoing.

CTLA-4/CD80 pathway regulates T cell infiltration into pancreatic cancer.

The ability of some tumors to exclude effector T cells represents a major challenge to immunotherapy. T cell exclusion is particularly evident in pancreatic ductal adenocarcinoma (PDAC), a disease where blockade of the immune checkpoint molecule CTLA-4 has not produced significant clinical activity. In PDAC, effector T cells are often scarce within tumor tissue and confined to peritumoral lymph nodes and lymphoid aggregates. We hypothesized that CTLA-4 blockade, despite a lack of clinical efficacy seen thus far in PDAC, might still alter T cell immunobiology, which would have therapeutic implications. Using clinically relevant genetic models of PDAC, we found that regulatory T cells (Tregs), which constitutively express CTLA-4, accumulate early during tumor development but are largely confined to peritumoral lymph nodes during disease progression. Tregs were observed to regulate CD4+, but not CD8+, T cell infiltration into tumors through a CTLA-4/CD80 dependent mechanism. Disrupting CTLA-4 interaction with CD80 was sufficient to induce CD4 T cell infiltration into tumors. These data have important implications for T cell immunotherapy in PDAC and demonstrate a novel role for CTLA-4/CD80 interactions in regulating T cell exclusion. In addition, our findings suggest distinct mechanisms govern CD4+ and CD8+ T cell infiltration in PDAC.

Abstract 2957: T-cell receptor immunosequencing reveals novel insights into the immune response to human pancreatic cancer

Abstract Introduction Despite advancements in therapy, pancreatic ductal adenocarcinoma (PDA) remains an aggressive cancer with high mortality. It is characterized by dense inflammation, including many T cells; however, it is unclear whether these T cells signify a true antitumor response. In the setting of disappointing early results of immunotherapy in PDA, we sought to gain a deeper understanding of the tumor-associated T-cell response. Methods With IRB approval, we obtained archival resected PDA tumors in paraffin-embedded blocks from 54 patients. We performed histopathology to identify blocks containing lymph nodes (LN) and performed T-cell receptor (TCR) immunosequencing on DNA extracted from immediately adjacent tissue. To address possible intratumoral heterogeneity, we analyzed duplicate samples from separate blocks for 10 patients. Productive clonality was defined as 1-Pielou’s evenness for TCR rearrangements encoding a functional protein; TCR fraction was calculated from number of observed templates and the amount of input DNA. Two-tailed t-tests were used to compare subgroups. TCR sequence overlap between each of the 10 pairs of duplicate samples were calculated at the amino acid level. Results Among samples that did not contain LN, mean TCR fraction was 0.27, and mean clonality was 0.15 (typical peripheral blood mononuclear cell clonality is 0.08). TCR fraction was positively correlated with clonality (R2=0.23, p=0.007), though this correlation was only significant in patients who received neoadjuvant chemotherapy (R2=0.19, p=0.03). TCR fraction was higher in patients with positive nodal status (0.32 vs. 0.23, p=0.02), but lower in patients who received neoadjuvant therapy (0.22 vs. 0.33, p=0.02). There was no survival difference between high or low TCR fraction or clonality. Samples containing LN (not included in previous analyses) had higher TCR fraction (0.49 vs. 0.27, p&amp;lt;0.0001) but lower clonality (0.09 vs. 0.15, p=0.0002); this relationship was maintained regardless of nodal status. Among 10 pairs of duplicate samples, there was 53% mean overlap of TCR amino acid sequences, compared to 0.1% for pairs of unmatched samples (p&amp;lt;0.0001). Conclusion Here we demonstrate evidence of clonal expansion of T cells in the human PDA microenvironment. Extensive overlap of TCR sequences between two distinct samples for each of 10 pairs analyzed further suggests that the clonal expansion may be specific to tumor antigens. Neoadjuvant therapy may also influence clonal expansion, as only treated patients had a positive correlation between TCR fraction and clonality. Finally, the presence of a lymph node appears to skew TCR sequencing data toward a less clonal but more numerous population. This suggests that the most rigorous analysis of TCRs in a solid tumor microenvironment needs to exclude blocks that contain lymph nodes in order to characterize the true intratumoral population of T cells. Citation Format: Yongwoo D. Seo, Florencia G. Jalikis, Xiuyun Jiang, Marissa Vignali, Harlan Robins, Venu G. Pillarisetty. T-cell receptor immunosequencing reveals novel insights into the immune response to human pancreatic cancer [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 2957. doi:10.1158/1538-7445.AM2017-2957

Rational combinations of immunotherapy for pancreatic ductal adenocarcinoma.

The complex interaction between the immune system, the tumor and the microenvironment in pancreatic ductal adenocarcinoma (PDA) leads to the resistance of PDA to immunotherapy. To overcome this resistance, combination immunotherapy is being proposed. However, rational combinations that target multiple aspects of the complex anti-tumor immune response are warranted. Novel clinical trials will investigate and optimize the combination immunotherapy for PDA.

Deploying Immunotherapy in Pancreatic Cancer: Defining Mechanisms of Response and Resistance.

The immune reaction to pancreatic ductal adenocarcinoma (PDAC) is a strong prognostic determinant of clinical outcomes and may be a promising therapeutic target. We use multiplex immunohistochemistry to illustrate distinct patterns of T-cell and myeloid cell infiltration seen in PDAC that have therapeutic implications and discuss the current state of immunotherapy in this disease. Based on collective findings from clinical and preclinical studies, two conceptual models have emerged for applying immunotherapy in PDAC that involve (1) restoring elements of T-cell immunosurveillance and (2) redirecting myeloid cells to condition tumors with increased sensitivity to cytotoxic therapies. Overall, the success of immunotherapy in PDAC will most likely rely on strategic combinations of therapies that are informed by well-designed correlative analyses that consider the spatial heterogeneity of immune responses detected in malignant tissues.

Advances in immunotherapy of pancreatic ductal adenocarcinoma

The morbidity of pancreatic ductal adenocarcinoma (PDAC) has been increasing over years, while the treatment efficacy and prognosis of PDAC remain far from satisfying. The newly-ermerged tumor immunotherapy has not only made lots of breakthroughs in various malignancies, but also brought an opportunity to the treatment of pancreatic cancer.PDAC immunotherapies, mainly including vaccine therapy, adoptive T cell thanfer therapy, checkpoint blockade therapy, have achieved a certain effect, however, the clinical outcomes have not been satisfactory. Therefore, the combination of immunotherapies based on different theoretical views is important and is likely to be the trend in the future. Carcinoma associated fibroblast (CAF) is the most common cell in pancreatic cancer stromal component. It will be helpful to develop more potential therapeutic targets by further exploring CAF and the mechanism of fibrosis mediated immunosuppression.

Abstract A08: Dectin-1 signaling drives pancreatic oncogenesis by promoting adaptive immune suppression

Abstract Progression of pancreatic oncogenesis requires immune-suppressive inflammation in cooperation with oncogenic mutations. However, the drivers of intra-tumoral immune tolerance are uncertain. Dectin-1 is an innate immune receptor critical in anti-fungal immunity, but its role in sterile inflammation and oncogenesis is not well-defined. Further, non-pathogen-derived ligands for Dectin-1 have not been characterized. We found that Dectin-1 is highly expressed on myeloid cells in pancreatic ductal adenocarcinoma (PDA). Moreover, Dectin-1 ligation accelerates PDA, whereas Dectin-1 deletion, or blockade of its downstream signaling, was highly protective. We show that Dectin-1 ligates the lectin Galectin-9 in the PDA tumor microenvironment (TME) leading to macrophage-induced adaptive immune suppression. Upon interruption of the Dectin-1–Galectin-9 axis, CD4+ and CD8+ T cells – which are dispensable to PDA progression in hosts with an intact signaling axis – become reprogrammed into indispensable mediators of anti-tumor immunity. These data suggest that Dectin-1 and Galectin-9 are novel and attractive targets for PDA immunotherapy. Citation Format: Donnele Daley, Neha Akkad, Navyatha Mohan, Atsuo Ochi, Gregor Werba, Vishnu Mani, Rocky Barilla, Constantinos Zambirinis, Mautin Hundeyin, Ki Buom Lee, Steven Chang, Ding Wang, Lawrence Gardener, Beatrix Ueberheide, George Miller. Dectin-1 signaling drives pancreatic oncogenesis by promoting adaptive immune suppression. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2016 Oct 20-23; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2017;5(3 Suppl):Abstract nr A08.