Pancreatic Ductal Adenocarcinoma Microenvironment Research Articles

Abstract 3627: Inhibition of tumor cell-autonomous p38 MAPK suppresses IL1α-mediated inflammatory tumor-stromal crosstalk in pancreatic adenocarcinoma

Abstract Introduction: Pancreatic ductal adenocarcinoma (PDAC) continues to face major therapeutic challenges due to its innate and acquired chemoresistance. Oncogenic, activating KRAS mutations facilitate extensive cytokine-mediated crosstalk between tumor cells and the fibrotic stroma, producing a pro-inflammatory and immunosuppressive tumor microenvironment (TME). We have identified interleukin-1α (IL1α), downstream of KRAS, as a critical mediator of the inflammatory response due to its pleiotropic effects on cancer-associated fibroblast (CAF) activation and immune evasion. However, the regulatory mechanisms of IL1α expression remain incompletely understood. We identified p38 stress-associated MAPK α (p38α) as a central, KRAS-driven regulatory pathway involved in IL1α production within PDAC tumor cells. Methods: Differential gene expression analyses were performed on patient data from The Cancer Genome Atlas (TCGA) was queried for overactive pathways downstream KRAS in “high-IL1A” PDAC cases. Inhibition of p38α was achieved pharmacologically with pexmetinib and genetically with an shRNA lentiviral system in human and murine PDAC cell lines. ChIP-qPCR and co-immunoprecipitation were performed on a human PDAC cell line with and without p38α inhibition. Single-cell RNA sequencing (scRNA-seq) and flow cytometry were performed on tumors from a PDAC murine model, Ptf1aCre/+; LSL-KrasG12D/+; Tgfbr2flox/flox (PKT), treated with or without pexmetinib. PKT mice were treated daily with pexmetinib, gemcitabine and paclitaxel chemotherapy, or combination therapy for downstream analysis and survival studies. Results: Both pharmacologic and genetic inhibition of p38α significantly reduced IL1A transcription and protein levels in human and murine PDAC tumor cell lines. Furthermore, p38α inhibition reduced binding of Sp1 and NF-κB to the IL1A promoter and prevented IL1α-mediated polarization of inflammatory CAFs in vitro. In PKT mice, p38α inhibition reduced tumor cell-specific Il1a and inflammatory CAF gene signatures by scRNA-seq, and favorably altered the infiltrating immune populations by flow cytometry. Lastly, pexmetinib with chemotherapy significantly reduced tumor burden and improved overall survival in a PDAC murine model. Conclusions: These findings provide a new therapeutic opportunity to target the p38α MAPK pathway for suppression of IL1α-mediated stromal activation and combination with chemotherapy to overcome therapeutic resistance by modulating the stromal and immune microenvironment in PDAC. Citation Format: Samara Singh, Austin R. Dosch, Siddharth Mehra, Iago de Castro Silva, Anna Bianchi, Vanessa Tonin Garrido, Zhiqun Zhou, Haleh Amirian, Edmond W. Box, Jashodeep Datta, Nagaraj Nagathihalli, Nipun B. Merchant. Inhibition of tumor cell-autonomous p38 MAPK suppresses IL1α-mediated inflammatory tumor-stromal crosstalk in pancreatic 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 3627.

Abstract 2871: Spatial landscape of the tumor microenvironment in pancreatic ductal adenocarcinoma using multiplexed imaging and AI based analysis

Abstract Pancreatic tumors are highly heterogenous, often with more aggressive regions that are responsible for invasion and metastasis. These aggressive pancreatic ductal adenocarcinoma (PDAC) cells undergo epithelial to mesenchymal transition and create subregions in the tumor that evade treatments and provide a critical support niche for continued tumor growth and metastasis. Conventional chemotherapy plus radiation, or in advanced disease chemotherapy plus targeted drug therapy can lengthen patient survival. However, even in patients with local disease, the 5-year survival rate remains at around 40%, demonstrating that there is need for improved conventional and immune therapies for all pancreatic cancer patients. In this study, dozens of biomarkers have been used to probe tumor heterogeneity in pancreatic ductal adenocarcinoma (PDAC) tissue. We rely on the published finding that hypoxia gene expression is consistent in PDAC, regardless of tumor location, whether primary tumor or metastasis. With the spatial biology solution, Cell DIVETM and proprietary Spatial AI analytics software, dozens of biomarkers can be used to computationally reduce tumor heterogeneity, and to spatially define cells in the microenvironment within hypoxic and normoxic regions of PDAC, and in normal pancreas. We found that these hypoxic PDAC regions are devoid of immune cells in general, with the appearance of spatially co-localized populations of cell types consistent with tumor desmoplasia and inflammation. Taken together, multiplexed whole slide imaging and analysis enables spatially resolved whole tissue analysis of the tumor microenvironment, including new insights into spatial biology in the hypoxic PDAC environment. Citation Format: Michael J. Smith, Chi-Chou Huang, Tuan H. Phan, Hideki Sasaki, Katie O. White, Richard A. Heil-Chapdelaine, Melinda Angus-Hill. Spatial landscape of the tumor microenvironment in pancreatic ductal adenocarcinoma using multiplexed imaging and AI based analysis [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 2871.

Ubiquitin-Specific Protease 43 Impacts Pancreatic Ductal Adenocarcinoma Prognosis by Altering Its Proliferation and Infiltration of Surrounding Immune Cells.

Pancreatic ductal adenocarcinoma (PDAC) is a devastating cancer, and the therapy options for PDAC remain restricted. The distinctive tumor immunological microenvironment (TIME) of PDAC, comprising a high number of stromal cells and a limited infiltration of cytotoxic T lymphocytes (CTLs), rendered immunotherapy ineffective. The protein level of ubiquitin-specific protease 43 (USP43) was a prognostic predictor in numerous cancers; however, its function in PDAC is limited. This article focuses on the influence of USP43 expression on PDAC prognosis and TIME alteration. Based on TCGA database and tissue microarray staining, the expression of USP43 in PDAC was evaluated. The association between USP43 and prognosis was then investigated using tissue samples and online databases. In PDAC tumor tissues, the correlation between USP43 expression and clinicopathological characteristics, immune cell infiltration, and prognosis was investigated. The expression of USP43 in PDAC cell lines was evaluated using quantitative polymerase chain reaction. Using a cell counting kit-8 (CCK-8) and a cell colony formation test, the viability of the cells was determined. On the basis of online databases and tissue samples, the link between USP43 and immune cell infiltration around PDAC was also examined. For statistical analyses, the software GraphPad, R, and SPSS 26.0 were utilized. The expression of USP43 was considerably higher in PDAC compared to normal pancreatic tissue in both the TCGA database and the tissue microarrays of PDAC patients (P < 0.001). High USP43 expression was associated with poor overall survival in both the TCGA database and the tissue microarray of PDAC patients (P = 0.046 and 0.021, respectively). USP43 overexpression promoted PANC-1 cell proliferation (P = 0.0018), but USP43 knockdown decreased PANC02 cell proliferation (P < 0.001). According to the TCGA database, USP43 is associated with T cell activation and inhibits CD8+ T cell activation in PDAC, as proven by a study of cell lines. Moreover, in both TCGA and PDAC cell lines, USP43 expression was negatively linked with the chemokine signaling pathway. Overexpression of USP43 is a potential prognostic indicator for PDAC patients. USP43 is a potential biomarker associated with T cell activation, suppression of CD8+ T cell enrichment, and the cytokine signal pathway. Future multicenter studies are needed to confirm our findings and their potential application in the treatment of PDAC patients.

Pancreatic Ductal Adenocarcinoma and Immune Checkpoint Inhibitors: The Gray Curtain of Immunotherapy and Spikes of Lights

Pancreatic ductal adenocarcinoma (PDAC) is a dismal disease with a poor 5-year overall survival rate (~10%). The revolution of immunotherapy in clinical oncology has not substantially changed clinical outcome for patients with PDAC. Despite outstanding efforts, neither immune checkpoint inhibitors (ICIs) alone, nor in combination with chemotherapy or targeted therapies have shown encouraging results. This failure mirrors the lack of knowledge about the real key players of immune system senescence and the complexity of the tumor microenvironment in PDAC. However, some hope can be derived from PARP-inhibitor combinations, vaccines, and CAR-T-cells therapy. In this review, we comprehensively summarize the latest updates about the use of ICIs in PDAC, focusing on clinical evidence and ongoing studies highlighting explanations for the failure of immunotherapy and possible solutions.

Development of a novel co-culture system using human pancreatic cancer cells and human iPSC-derived stellate cells to mimic the characteristics of pancreatic ductal adenocarcinoma in vitro

Pancreatic ductal adenocarcinoma (PDAC) is a serious disease with poor prognosis and prone to chemotherapy resistance. It is speculated that the tumor microenvironment (TME) of PDAC contributes to these characteristics. However, the detailed mechanisms of interactions between pancreatic cancer cells and stroma in the TME are unclear. Therefore, the aim of this study was to establish a co-culture system that mimics the TME, using cancer cells derived from PDAC patient specimens and stellate cells from human induced pluripotent stem cells as stromal cells. We succeeded in observing the interaction between cancer cells and stellate cells and reproduced some features of PDAC in vitro using our co-culture systems. In addition, we demonstrated the applicability of our co-culture system for drug treatment in vitro. To conclude, we propose our co-culture system as a novel method to analyze cell-cell interactions, especially in the TME of PDAC.

Pancreatic cancer: Emerging field of regulatory B-cell-targeted immunotherapies.

Pancreatic ductal adenocarcinoma (PDAC), the most common type of pancreatic cancer, is characterized by a high mortality rate and poor prognosis. Current treatments for PDAC, are ineffective due to a prominent immunosuppressive PDAC tumor microenvironment (TME). Although B lymphocytes are highly infiltrated into PDAC, the importance of B lymphocytes in tumorigenesis is largely neglected. B cells play a dual role in the PDAC tumor microenvironment, acting as either anti-tumorigenic or pro-tumorigenic depending on where they are localized. Tumor-infiltrating B cells, which reside in ectopic lymph nodes, namely tertiary lymphoid structures (TLS), produce anti-tumor antibodies and present tumor antigens to T cells to contribute to cancer immunosurveillance. Alternatively, regulatory B cells (Bregs), dispersed inside the TME, contribute to the dampening of anti-tumor immune responses by secreting anti-inflammatory cytokines (IL-10 and IL-35), which promote tumor growth and metastasis. Determining the role of Bregs in the PDAC microenvironment is thus becoming increasingly attractive for developing novel immunotherapeutic approaches. In this minireview, we shed light on the emerging role of B cells in PDAC development and progression, with an emphasis on regulatory B cells (Bregs). Furthermore, we discussed the potential link of Bregs to immunotherapies in PDAC. These current findings will help us in understanding the full potential of B cells in immunotherapy.

Pseudotime dynamics of T cells in pancreatic ductal adenocarcinoma inform distinct functional states within the regulatory and cytotoxic T cells

Pancreatic ductal adenocarcinoma (PDAC) is among the deadliest types of cancer and has a 5-year survival of less than 8% owing to its complex biology. As PDAC is refractory to immunotherapy, we need to understand the functional dynamics of Tcells in the PDAC microenvironment to develop alternative therapeutic strategies. In this study, we performed RNA velocity-based pseudotime analysis on a scRNA-seq dataset from surgically resected human PDAC specimens to gain insight into temporal gene expression patterns that best characterize the cell fates. The tumor microenvironment was seen to encompass a range of terminal states for the Tcell trajectories with suppressive and non-tumor-responsive Tcells dominating them. However, the results also reveal the existence of a functional branch of the Tcell population that was not transitioning to exhausted and senescent states. These findings reveal various microenvironmental signals driving Tcell patterns which can be useful in identifying new therapeutic avenues.

Dysregulated miRNAs modulate tumor microenvironment associated signaling networks in pancreatic ductal adenocarcinoma.

The desmoplastic and complex tumor microenvironment of pancreatic ductal adenocarcinoma (PDAC) has presented tremendous challenges for developing effective therapeutic strategies. Strategies targeting tumor stroma, albeit with great potential, have met with limited success due to the lack of knowledge on the molecular dynamics within the tumor microenvironment (TME). In pursuit of a better understanding of the influence of miRNAs on TME reprogramming and to explore circulating miRNAs as diagnostic and prognostic biomarkers for PDAC, using RNA-seq, miRNA-seq, and single-cell RNA-seq (scRNA-seq), we investigated the dysregulated signaling pathways in PDAC TME modulated by miRNAs from plasma and tumor tissue. Our bulk RNA-seq in PDAC tumor tissue identified 1445 significantly differentially expressed genes with extracellular matrix and structure organization as the top enriched pathways. Our miRNA-seq identified 322 and 49 abnormally expressed miRNAs in PDAC patient plasma and tumor tissue, respectively. We found many of the TME signaling pathways were targeted by those dysregulated miRNAs in PDAC plasma. Combined with scRNA-seq from patient PDAC tumor, our results revealed that these dysregulated miRNAs were closely associated with extracellular matrix (ECM) remodeling, cell-ECM communication, epithelial-mesenchymal transition, as well as immunosuppression orchestrated by different cellular components of TME. The findings of this study could assist the development of miRNA-based stromal targeting biomarkers or therapy for PDAC patients.

Tissue-resident CXCR4+ macrophage as a poor prognosis signature promotes pancreatic ductal adenocarcinoma progression.

Macrophage is an essential part of the tumor immune microenvironment of pancreatic ductal adenocarcinoma. In our study, we explored the CXCR4+ macrophages subset on its prognosis value, immune profile and distinct function in pancreatic cancer progression. Specimens from 102 postoperative pancreatic patients were analyzed by flow cytometry or immune-fluorescence, and the prognostic value of CXCR4+ macrophages infiltration was further determined by Cox regression. In silico analysis on TCGA, ICGC database and single-cell sequencing of pancreatic ductal adenocarcinoma further validated our findings. We found that high CXCR4+ macrophages infiltration was associated with poor overall survival (P < .01) and disease-free survival (P < .05) as an independent factor. CXCR4+ macrophages exhibited an M2 protumor phenotype with high expression of CD206. The function of CXCR4+ macrophages was further analyzed in the murine orthotopic PDAC model with its tumor promotion effect and inhibition of CD8+ T cells. Mechanistic and RNA-seq analysis showed that CXCR4+ macrophages participated in extracellular matrix remodeling procedures and especially secreted SPARC through CXCR4/PI3K/Akt pathway promoting tumor proliferation and migration. Our study reveals that CXCR4+ macrophages infiltration is an indicator of poor prognosis of PDAC and targeting these cells was potentially crucial in immunotherapy of PDAC.

Targeted therapy for pancreatic ductal adenocarcinoma: Mechanisms and clinical study.

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive and lethal malignancy with a high rate of recurrence and a dismal 5-year survival rate. Contributing to the poor prognosis of PDAC is the lack of early detection, a complex network of signaling pathways and molecular mechanisms, a dense and desmoplastic stroma, and an immunosuppressive tumor microenvironment. A recent shift toward a neoadjuvant approach to treating PDAC has been sparked by the numerous benefits neoadjuvant therapy (NAT) has to offer compared with upfront surgery. However, certain aspects of NAT against PDAC, including the optimal regimen, the use of radiotherapy, and the selection of patients that would benefit from NAT, have yet to be fully elucidated. This review describes the major signaling pathways and molecular mechanisms involved in PDAC initiation and progression in addition to the immunosuppressive tumor microenvironment of PDAC. We then review current guidelines, ongoing research, and future research directions on the use of NAT based on randomized clinical trials and other studies. Finally, the current use of and research regarding targeted therapy for PDAC are examined. This review bridges the molecular understanding of PDAC with its clinical significance, development of novel therapies, and shifting directions in treatment paradigm.

Effects of losartan and vitamin D on outcomes in metastatic pancreatic adenocarcinoma.

723 Background: Active modification of surrounding stroma is a critical mechanism of tumor cell growth in pancreatic ductal adenocarcinoma (PDAC). There is some early translational evidence that losartan (L) and vitamin D (D) may affect the tumor microenvironment and supportive stroma in PDAC to help restore a physically and biologically tumor-suppressive stroma. These effects of potentially stroma-modifying drugs have not been established in the clinical management of metastatic PDAC (mPDAC), where there have been limited advances in treatment and prognosis remains poor. Methods: This is a single center, retrospective analysis of patients with mPDAC treated at Fox Chase Cancer Center from 2010 to 2019. All data including L and D use were extracted from the medical record. Patient characteristics were compared across subgroups using Chi-square tests, Fisher’s exact tests, and Wilcoxon rank sum tests. The primary outcome was overall survival (OS) from the time of metastatic diagnosis. Kaplan-Meier curves and log-rank tests were used to compare unadjusted OS across subgroups. Cox proportional hazards models were used to characterize OS adjusted for age at metastatic diagnosis, sex, initial stage at diagnosis, performance status, Charlson Comorbidity Index (CCI), hypertension, and renal disease. Results: 518 patients were included; a majority were male (54.1%), White (82.4%), and diagnosed with de novo mPDAC (54.6%). About half of patients had hypertension (53.5%) and few had renal dysfunction (5.6%). 153 (29.5%) patients were taking D and 41 (8%) patients were taking L. Women were more likely to take D than men (p &lt; 0.001) and White patients were more likely to take L than other races/ethnicities (p = 0.006). Median OS since metastatic diagnosis for patients taking L was 11.4 months compared to 9.6 months for patients not taking L (p = 0.07). Median OS for patients taking D was 11.3 months compared to 8.7 months for those not taking D (p = 0.10). A Cox proportional hazards model adjusting for confounders, however, showed that both L (HR 0.66, p = 0.02) and D (HR 0.81, p = 0.04) were significantly associated with improved OS from time of metastatic diagnosis. Conclusions: This large retrospective study demonstrates potential clinical and survival benefit of L and D in conjunction with mPDAC treatment. L and D are safe, well tolerated, and widely used in general medical practice. These results support further investigation of the stroma-modifying potential of L and D, as well as conducting prospective trials with these agents to further validate these findings.

Fungal mycobiome-mediated immune response: a non-negligible promoter in pancreatic oncogenesis and chemoresistance.

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers in humans due to late diagnosis and poor response to treatments. The tumor microenvironment (TME) of PDAC is characterized by a distinctive, suppressive immune profile, which inhibits the protective functions of anti-tumor immunity and thereby contributes to PDAC progression. Recently, the study of Alam et al. discovered for the first time that the intratumoral fungal mycobiome could contribute to the recruitment and activation of type 2 immune cells in the TME of PDAC via enhancing the secretion of a chemoattractant, interleukin (IL-) 33. In this article, we reviewed the important findings of this study. Together with our findings, we synthetically discussed the role of the fungal mycobiome in orchestrating the immune response and thereby modulating tumor progression.

Assessment of biological effect of nab-paclitaxel combined with gemcitabine, using contrast enhanced ultrasonography and elastography, in advanced pancreatic ductal carcinoma: A single-center pilot study.

EUS associated with contrast-enhanced harmonic EUS (CH-EUS) and EUS elastography (EUS-E) are used in clinical practice to assess pancreatic tumor at the diagnosis. In case of pancreatic ductal adenocarcinoma (PDAC) with liver metastasis, nab-paclitaxel combined with gemcitabine is a first-line treatment option. We aimed to assess the modification of PDAC microenvironment induced by the combination of nab-paclitaxel with gemcitabine, by endoscopic ultrasonography techinics. This single center phase III study conducted between February 2015 and June 2016 included patients with pancreatic adenocarcinoma with mesurable liver metastasis and no prior cancer treatment fit for two cycles of nab-paclitaxel combined with gemcitabine. We aimed to perform EUS with CH-EUS and EUS-E of the pancreatic tumor, CT scan and contrast enhanced ultrasonogram (CE-US) of a reference liver metastasis, before and after the two cylces of chemotherapy. Primary end point was modification of vascularizaion of primary tumor and a reference liver metastasis. Secondary end points were modification of stromal content, safety profile of drug combination and tumor response rate. Sixteen patients were analyzed, but only 13 received two cycled of chemotherapy (CT) (toxicity [n = 1] or death [n = 2]). There was no statistical modification induced by CT concering vascularity of primary tumor (time to maximum intensity P = 0.24, value of maximum intensity P = 0.71, hypoechogenic aspect generated by injection of contrast enhancing agent), vascularity of a reference liver metastasis (time to maximum intensity P = 0.99, value of maximum intensity P = 0.71) and tumor elasticity (P = 0.22). Eleven patients had tumor response assessement, 6/11 (54%) had measurable disease response 4/11 (36%) with partial responses and 2/11 (18%) with stable disease. All other patients showed disease progression. No serious side effects occurred, 6/11 patients had a dose adjustment. We did not show significant modification of vascularity and elasticity but these results should be taken with caution because of important limitations.

Metastatic phenotype and immunosuppressive tumour microenvironment in pancreatic ductal adenocarcinoma: Key role of the urokinase plasminogen activator (PLAU).

Previous studies have revealed the role of dysregulated urokinase plasminogen activator (encoded by PLAU) expression and activity in several pathways associated with cancer progression. However, systematic investigation into the association of PLAU expression with factors that modulate PDAC (pancreatic ductal adenocarcinoma) progression is lacking, such as those affecting stromal (pancreatic stellate cell, PSC)-cancer cell interactions, tumour immunity, PDAC subtypes and clinical outcomes from potential PLAU inhibition. This study used an integrated bioinformatics approach to identify prognostic markers correlated with PLAU expression using different transcriptomics, proteomics, and clinical data sets. We then determined the association of dysregulated PLAU and correlated signatures with oncogenic pathways, metastatic phenotypes, stroma, immunosuppressive tumour microenvironment (TME) and clinical outcome. Finally, using an in vivo orthotopic model of pancreatic cancer, we confirmed the predicted effect of inhibiting PLAU on tumour growth and metastasis. Our analyses revealed that PLAU upregulation is not only associated with numerous other prognostic markers but also associated with the activation of various oncogenic signalling pathways, aggressive phenotypes relevant to PDAC growth and metastasis, such as proliferation, epithelial-mesenchymal transition (EMT), stemness, hypoxia, extracellular cell matrix (ECM) degradation, upregulation of stromal signatures, and immune suppression in the tumour microenvironment (TME). Moreover, the upregulation of PLAU was directly connected with signalling pathways known to mediate PSC-cancer cell interactions. Furthermore, PLAU upregulation was associated with the aggressive basal/squamous phenotype of PDAC and significantly reduced overall survival, indicating that this subset of patients may benefit from therapeutic interventions to inhibit PLAU activity. Our studies with a clinically relevant orthotopic pancreatic model showed that even short-term PLAU inhibition is sufficient to significantly halt tumour growth and, importantly, eliminate visible metastasis. Elevated PLAU correlates with increased aggressive phenotypes, stromal score, and immune suppression in PDAC. PLAU upregulation is also closely associated with the basal subtype type of PDAC; patients with this subtype are at high risk of mortality from the disease and may benefit from therapeutic targeting of PLAU.

IGFBP2 Drives Regulatory T Cell Differentiation through STAT3/IDO Signaling Pathway in Pancreatic Cancer.

Pancreatic ductal adenocarcinoma (PDAC) represents one of the deadliest malignancies. Elevated regulatory T cell (Treg) infiltration has a potent immunosuppressive function in tumor biology, which contributes to low survival in PDAC. Nonetheless, the crosstalk between malignant cells and tumor-infiltrating Tregs in PDAC is not well understood. Here, clinical data demonstrates that the insulin-like growth factor binding protein 2 (IGFBP2) is associated with Treg accumulation in the microenvironment of PDAC in humans. Additionally, IGFBP2 increases Treg infiltration in the tumor microenvironment and promotes disease progression in mouse PDAC. Bioinformatic analysis and mechanistic assessment reveals IGFBP2 upregulated indoleamine 2, 3-dioxygenase (IDO) by activating signal transducer and activator of transcription 3 (STAT3) signaling in PDAC cells, thus inducing Treg differentiation and an immunosuppressive tumor microenvironment. These findings provide mechanistic insights into an important molecular pathway that promotes an immunosuppressive microenvironment, which suggests the IGFBP2 axis as a potential target for improved immune response in PDAC.

Diabetes mellitus impacts on expression of DNA mismatch repair protein PMS2 and tumor microenvironment in pancreatic ductal adenocarcinoma.

The mismatch repair (MMR) protein recognizes DNA replication errors and plays an important role in tumorigenesis, including pancreatic ductal adenocarcinoma (PDAC). Although PMS2, a MMR protein, is degraded under oxidative stress, the effects of diabetes are still unclear. Herein, we focused on whether diabetes affected MMR protein expression in PDAC. Tissues from 61 surgically resected PDAC subjects were clinicopathologically analyzed. Immunohistochemical analysis was performed for MMR protein expression, oxidative stress, and immune cell infiltration. The change of MMR protein expression was assessed in PDAC cell lines under stimulation with 25 mM glucose and 500 μM palmitic acid. Survival curves were analyzed by the Kaplan-Meier method with the log-rank test. Diabetes complicated with dyslipidemia significantly decreased the expression of PMS2 in PDAC tissues with an inverse correlation with the degree of oxidative stress. Palmitic acid combined with high glucose induced degradation of PMS2 protein, enhancing oxidative stress invitro. CD8+ T-cell infiltration was associated with a short duration of type 2 diabetes (≤4 years) and a low expression of PMS2 in PDAC tissues, while CD163+ tumor-associated macrophage infiltration was increased with a long duration of diabetes (>4 years). A short duration of diabetes exhibited a better prognosis than nondiabetic subjects with PDAC (P< 0.05), while a long duration of diabetes had a worse prognosis (P< 0.05). The different phases of diabetes have a major impact on PDAC by altering PMS2 expression and the tumor immune microenvironment, which can be targeted by an immune checkpoint inhibitor.

37P Synthetic tumour-infiltrating interleukin (IL)-12 for targeted and tolerable immunotherapy reduces metastasis in pancreatic cancer

Metastatic Pancreatic Ductal Adenocarcinoma (PDAC) is a root cause of lethality in patients. The metastasis is promoted by abundant proteases in the PDAC microenvironment. Synthetic immuno-oncology opens new avenues towards overcoming limitations of standard immunotherapy agents, previously unsuccessful in PDAC. Anti-tumour cytokines such as IL-12 poorly infiltrate the stroma of solid tumours and trigger toxicity. Here, by exploiting the abundant proteases in PDACs, a targeted and tolerable masked Collagen-Binding Domain CBD-Il12 (mCBD-Il12) was produced by fusing the mask to the p35 subunit of Il-12 through a cleavable linker.

Pancreatic ductal adenocarcinoma holds unique features to form an immunosuppressive microenvironment: a narrative review

Pancreatic ductal adenocarcinoma (PDAC) is the most common type and composes about 90% of pancreatic cancer featured with high intra-tumoral heterogeneity and poor prognosis, which has been considered the least immunogenic cancer for decades. However, this characterization might be over-simplistic, and more sophisticated approaches are needed to develop effective treatment strategies. In this review, we aim to summarize studies involving PDAC immunity in different aspects to provide a multidimensional recognition and comprehensively understanding of the mechanisms underlying the tumor microenvironment (TME) of PDAC. A database search of peer-reviewed articles published in English between 2003 and 2022 in PubMed and the Web of Science was performed. Original articles and review articles relevant to the topic were selected. We emphasized the importance of investigating tumor-infiltrating lymphocytes (TILs) in pancreatic cancer, especially focusing on CD8+ T cells, along with indicating potential therapeutic strategies to turn the immune-cold PDACs into the immune-hot ones.

Abstract A017: Phase 1b Study of 2nd line vactosertib plus oxaliplatin with 5FU/LV (FOLFOX) in patients with metastatic pancreatic ductal adenocarcinoma (PDAC) who have failed first-line gemcitabine with nab-paclitaxel

Abstract Background: Despite of recent advances in chemotherapies, PDAC remains aggressive malignancies and the leading cause of cancer-related death in the world. TGF-β is strongly involved in the tumor microenvironment in PDAC, and dysregulation of TGF-β signaling is a frequent molecular disturbance in progression and metastasis. Vactosertib is an orally bioavailable TGF-β signaling inhibitor that targets the TGF-β type I receptor kinase. In in vivo studies, vactosertib in combination with FOLFOX improves pancreatic cancer survival by suppressing cell migration, invasion, and EMT, highlighting a potential clinical application of this approach for PDAC patients. Based on this preclinical study, we develop a phase 1b study to determine the RP2D and to evaluate the safety of vactosertib in combination with FOLFOX in patients with metastatic PDAC who have failed first-line gemcitabine with nab-paclitaxel. Methods: Eligible patients have histologically confirmed PDAC who have failed first-line gemcitabine/nab-paclitaxel with adequate organ function and performance status. This study is composed of two parts; dose escalation and dose expansion. In the dose escalation part, different dose levels of vactosertib (50 mg bid, 100 mg bid, and 200 mg bid) for escalation were tested, starting with dose level 0 (DL 0, 100 mg bid) with 3 to 6 subjects recruited in each cohort. DL -1 was only planned to test when DL 0 was unacceptable. In the dose expansion part, an additional backfill cohort was planned to open for determination of the final RP2D. Patients in each cohort were planned to receive vactosertib 50-200 mg orally twice per day 1-5 &amp; day 8-12 with oxaliplatin 85 mg/m2 on day 1, LV 200mg/m2 IV on day 1, 5FU 200mg/m2 bolus on day 1 and continuous 5-FU 2400mg/m2 infusion over 48 hours every 2 weeks. The primary endpoints were to determine RP2D and to evaluate safety of this combination. The key secondary endpoints were progression free survival (PFS), overall response rate (ORR), disease control rate (DCR) based on RECIST 1.1 and overall survival. Results: A total of 16 patients were enrolled, 3 in DL 0, 4 in DL 1 and 9 in DL 1 backfill cohort. No dose limiting toxicities (DLTs) were observed and the RP2D was established as vactosertib 200 mg orally twice per day 1-5 &amp; day 8-12 with FOLFOX. The vactosertib related adverse events (AEs) of any grade included fatigue, nausea, vomiting and anorexia. Three of 13 patients (23.1%) had partial response and 5 (38.5%) stable disease as best response, with clinical benefit rate of 61.5 % in DL 1, while there were no PR or SD in DL 0. Median PFS was 4.2 months [95% confidence interval (CI), 1.3–7.1] and median OS was 9.3 months [95% confidence interval (CI), 4.86–13.7]. Conclusion: In this phase Ib study, we demonstrated the feasibility and safety of adding vactosertib to FOLFOX in 2nd line setting, which needs to be further investigated. Updated results, including PK analyses, safety profiles, and clinical outcomes will be presented. This study was prospectively registered on ClinicalTrials.gov, NCT03666832. Citation Format: Joon Oh Park, Seung Tae Kim, Eunji Hong, Jung Yong Hong, Young Suk Park, Seong-Jin Kim. Phase 1b Study of 2nd line vactosertib plus oxaliplatin with 5FU/LV (FOLFOX) in patients with metastatic pancreatic ductal adenocarcinoma (PDAC) who have failed first-line gemcitabine with nab-paclitaxel [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr A017.

Abstract C071: Keratin 17 excludes CD8-positive T cells and recruits CD163-positive macrophages in pancreatic ductal adenocarcinoma

Abstract Background: Keratin 17 (K17) is a negative prognostic biomarker, overexpressed in the biologically most aggressive forms of pancreatic ductal adenocarcinoma (PDAC). In other anatomic sites and disease processes, K17 expression also correlates with immune cell infiltrates and could block T-cell infiltration. Thus, we hypothesized that K17 expression correlates with the inflammatory microenvironment in PDAC. In this study, we aimed to determine the relationship between the stromal immune cell infiltrates and K17 expression, using multiplexed immunohistochemistry (mIHC) and our suite of deep learning tools to quantitatively evaluate the expression of four biomarkers of T-cells and macrophages in PDAC. Methods: mIHC was performed on representative sections of 201 primary PDACs from Stony Brook University Hospital, Thomas Jefferson University Hospital, Cedars Sinai Medical Center, and from a national cohort (KYT, Pancreatic Cancer Action Network, and Perthera). Antibodies for CD4 (helper T-cells), CD8 (cytotoxic T-cells), CD16 (pan-macrophage), CD163 (M2 macrophages), pancytokeratin, and K17 were provided by Roche Diagnostics Corporation through a sponsored research agreement. mIHC was performed on a Discovery Ultra Autostainer (Roche), using horseradish peroxidase (HRP) and alkaline phosphatase (AP)-based protocols with multiple chromogens (Red: CD4, Purple: CD8, Yellow: CD16, Green: CD163, Teal: pancytokeratin, and Brown: K17) to enable multispectral imaging of diverse immune cell populations within the cancer microenvironment. A deep learning analysis workflow was used to detect and classify stromal inflammatory cells, in whole slide images (WSIs), generated using an Olympus VS120 digital microscope (Olympus, Tokyo, Japan). Pixel-wise predictions from a color auto-encoder (ColorAE) union UNET anchor UNET model were combined to create multi-class masks that were further analyzed to perform detection and classification. Results: The analysis of the inflammatory microenvironment focused on defining immune cell infiltrates located within 25 microns of the closest K17-positive versus K17-negative tumor cell in each representative section. Across the sum of K17-positive and negative zones/section, CD4 cell counts ranged from 0-10,617 (mean 2,709), CD8 cell counts ranged from 63-28,596 (mean 6,745), CD16 cell counts ranged from 4-7,797 (mean 3,024), and CD163 cell counts ranged from 35-34,696 (mean 14,968). CD4 T-helper cells, CD8 cytotoxic T cells, and CD16 macrophages were more numerous (respectively, p=0.0012; p=&amp;lt;0.0001; p=&amp;lt;0.0001) in K17-negative tumor zones compared to K17-positive zones. By contrast, the number of CD163 (M2) tumor-promoting macrophages was greater in K17 positive zones (p=0.0019). Conclusion: K17 expression by tumor cells impacts the chronic inflammatory microenvironment, shielding tumor cells from immune cell mediated cytotoxic responses, while recruiting tumor-promoting M2 macrophages, indicating that K17 impacts the immune response as a fundamental hallmark of aggression in PDAC. Citation Format: Lyanne Oblein, Michael Horowitz, Mahmudul Hasan, Sruthi Babu, Mariana Torrente-Goncalves, Lucia Roa, Jaymie Oentoro, Jason Harper, Xin Yao Zheng, Wei Jiang, Andrew Hendifar, Natalie Moshayedi, Brent Larson, Veronica Placencio-Hickok, Edik Blais, Emmanuel Petricoin, Joel Saltz, Natalia D. Marchenko, Luisa F. Escobar-Hoyos, Kenneth Shroyer. Keratin 17 excludes CD8-positive T cells and recruits CD163-positive macrophages in pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr C071.