Approach For Pancreatic Ductal Adenocarcinoma Research Articles

What is the optimal surgical approach for ductal adenocarcinoma of the pancreatic neck? - a retrospective cohort study.

The appropriate surgical approach for pancreatic ductal adenocarcinoma (PDAC) is determined by the tumor's relation to the porto-mesenteric axis. Although the extent and location of lymphadenectomy is dependent on the type of resection, a pancreatoduodenectomy (PD), distal pancreatectomy (DP), or total pancreatectomy (TP) are considered equivalent oncologic operations for pancreatic neck tumors. Therefore, we aimed to assess differences in histopathological and oncological outcomes for surgical approaches in the treatment of pancreatic neck tumors. Patients with resected PDAC located in the pancreatic neck were identified from the National Cancer Database (2004-2020). Patients with metastatic disease were excluded. Furthermore, patients with 90-day mortality and R2-resections were excluded from the multivariable Cox-regression analysis. Among 846 patients, 58% underwent PD, 25% DP, and 17% TP with similar R0-resection rates (p = 0.722). Significant differences were observed in nodal positivity (PD:44%, DP:34%, TP:57%, p < 0.001) and mean-number of examined lymph nodes (PD:17.2 ± 10.4, DP:14.7 ± 10.5, TP:21.2 ± 11.0, p < 0.001). Furthermore, inadequate lymphadenectomy (< 12 nodes) was observed in 30%, 44%, and 19% of patients undergoing PD, DP, and TP, respectively (p < 0.001). Multivariable analysis yielded similar overall survival after DP (HR:0.83, 95%CI:0.63-1.11), while TP was associated with worse survival (HR:1.43, 95%CI:1.08-1.89) compared to PD. While R0-rates are similar amongst all approaches, DP is associated with inadequate lymphadenectomy which may result in understaging disease. However, this had no negative influence on survival. In the premise that an oncological resection of the pancreatic neck tumor is feasible with a partial pancreatectomy, no benefit is observed by performing a TP.

Immuno-PET and Targeted α-Therapy Using Anti-Glypican-1 Antibody Labeled with 89Zr or 211At: A Theranostic Approach for Pancreatic Ductal Adenocarcinoma.

Glypican-1 (GPC1) is overexpressed in several solid cancers and is associated with tumor progression, whereas its expression is low in normal tissues. This study aimed to evaluate the potential of an anti-GPC1 monoclonal antibody (GPC1 mAb) labeled with 89Zr or 211At as a theranostic target in pancreatic ductal adenocarcinoma. Methods: GPC1 mAb clone 01a033 was labeled with 89Zr or 211At with a deferoxamine or decaborane linker, respectively. The internalization ability of GPC1 mAb was evaluated by fluorescence conjugation using a confocal microscope. PANC-1 xenograft mice (n = 6) were intravenously administered [89Zr]GPC1 mAb (0.91 ± 0.10 MBq), and PET/CT scanning was performed for 7 d. Uptake specificity was confirmed through a comparative study using GPC1-positive (BxPC-3) and GPC1-negative (BxPC-3 GPC1-knockout) xenografts (each n = 3) and a blocking study. DNA double-strand breaks were evaluated using the γH2AX antibody. The antitumor effect was evaluated by administering [211At]GPC1 mAb (∼100 kBq) to PANC-1 xenograft mice (n = 10). Results: GPC1 mAb clone 01a033 showed increased internalization ratios over time. One day after administration, a high accumulation of [89Zr]GPC1 mAb was observed in the PANC-1 xenograft (SUVmax, 3.85 ± 0.10), which gradually decreased until day 7 (SUVmax, 2.16 ± 0.30). The uptake in the BxPC-3 xenograft was significantly higher than in the BxPC-3 GPC1-knockout xenograft (SUVmax, 4.66 ± 0.40 and 2.36 ± 0.36, respectively; P = 0.05). The uptake was significantly inhibited in the blocking group compared with the nonblocking group (percentage injected dose per gram, 7.3 ± 1.3 and 12.4 ± 3.0, respectively; P = 0.05). DNA double-strand breaks were observed by adding 150 kBq of [211At]GPC1 and were significantly suppressed by the internalization inhibitor (dynasore), suggesting a substantial contribution of the internalization ability to the antitumor effect. Tumor growth suppression was observed in PANC-1 mice after the administration of [211At]GPC1 mAb. Internalization inhibitors (prochlorperazine) significantly inhibited the therapeutic effect of [211At]GPC1 mAb, suggesting an essential role in targeted α-therapy. Conclusion: [89Zr]GPC1 mAb PET showed high tumoral uptake in the early phase after administration, and targeted α-therapy using [211At]GPC1 mAb showed tumor growth suppression. GPC1 is a promising target for future applications for the precise diagnosis of pancreatic ductal adenocarcinoma and GPC1-targeted theranostics.

Cancer cell membrane-coated upconversion nanoparticles/ZnxMn1-xS core-shell nanoparticles for targeted photodynamic and chemodynamic therapy of pancreatic cancer.

Oxidative stress induced by reactive oxygen species (ROS) is promising treatment approach for pancreatic ductal adenocarcinoma (PDAC), which is typically insensitive to conventional chemotherapy. In this study, BxPC-3 pancreatic cancer cell membrane-coated upconversion nanoparticles/ZnxMn1-xS core-shell nanoparticles (abbreviated as BUC@ZMS) were developed for tumor-targeted cancer therapy via synergistically oxidative stress and overcoming glutathione (GSH) overexpression. Using a combination of photodynamic therapy (PDT) and chemodynamic therapy (CDT), the BUC@ZMS core-shell nanoparticles were able to elicit the death of pancreatic cancer cells through the high production of ROS. Additionally, the BUC@ZMS core-shell nanoparticles could deplete intracellular GSH and increase the sensitivity of tumor cells to oxidative stress. The in vivo results indicated that BUC@ZMS nanoparticles can accumulate specifically in tumor locations and suppress PDAC without generating obvious toxicity. Thus, it was determined that the as-prepared core-shell nanoparticles would be a viable treatment option for solid malignancies.

Targeting FGFR signalling as a therapeutic approach in pancreatic ductal adenocarcinoma

Targeting FGFR signalling as a therapeutic approach in pancreatic ductal adenocarcinoma

RBFOX2 modulates a metastatic signature of alternative splicing in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDA) is characterized by aggressive local invasion and metastatic spread, leading to high lethality. Although driver gene mutations during PDA progression are conserved, no specific mutation is correlated with the dissemination of metastases1–3. Here we analysed RNA splicing data of a large cohort of primary and metastatic PDA tumours to identify differentially spliced events that correlate with PDA progression. De novo motif analysis of these events detected enrichment of motifs with high similarity to the RBFOX2 motif. Overexpression of RBFOX2 in a patient-derived xenograft (PDX) metastatic PDA cell line drastically reduced the metastatic potential of these cells in vitro and in vivo, whereas depletion of RBFOX2 in primary pancreatic tumour cell lines increased the metastatic potential of these cells. These findings support the role of RBFOX2 as a potent metastatic suppressor in PDA. RNA-sequencing and splicing analysis of RBFOX2 target genes revealed enrichment of genes in the RHO GTPase pathways, suggesting a role of RBFOX2 splicing activity in cytoskeletal organization and focal adhesion formation. Modulation of RBFOX2-regulated splicing events, such as via myosin phosphatase RHO-interacting protein (MPRIP), is associated with PDA metastases, altered cytoskeletal organization and the induction of focal adhesion formation. Our results implicate the splicing-regulatory function of RBFOX2 as a tumour suppressor in PDA and suggest a therapeutic approach for metastatic PDA.

Management of Pancreatic Cancer and Its Microenvironment: Potential Impact of Nano-Targeting.

Simple SummaryThe poor prognosis and survival rates associated with pancreatic cancer show that there is a clear unmet need for better disease management. The heterogeneity of the tumor and its microenvironment, including stroma and fibrosis, creates a challenge for current therapy. The pathogenesis of pancreatic cancer is mediated by several factors, such as severed communication between pancreatic stellate cells and stroma and the consequences of hypoxia-inducible factors that aid in the survival of the pancreatic tumor. Given the multiple limitations of molecular targeting, multiple functional nano-targeting offers a breakthrough in pancreatic cancer treatment through its ability to overcome the physical challenges posed by the tumor microenvironment, amongst many others.Pancreatic ductal adenocarcinoma (PDAC) is rare and difficult to treat, making it a complicated diagnosis for every patient. These patients have a low survival rate along with a poor quality of life under current pancreatic cancer therapies that adversely affect healthy cells due to the lack of precise drug targeting. Additionally, chemoresistance and radioresistance are other key challenges in PDAC, which might be due in part to the lack of tumor-targeted delivery of sufficient levels of different chemotherapies because of their low therapeutic index. Thus, instead of leaving a trail of off-target damage when killing these cancer cells, it is best to find a way that targets them directly. More seriously, metastatic relapse often occurs after surgery, and therefore, achieving improved outcomes in the management of PDAC in the absence of strategies preventing metastasis is likely to be impossible. Nano-targeting of the tumor and its microenvironment has shown promise for treating various cancers, which might be a promising approach for PDAC. This review updates the advancements in treatment modalities for pancreatic cancer and highlights future directions that warrant further investigation to increase pancreatic patients’ overall survival.

Evaluating the learning curve of robotic radical antegrade modular pancreatosplenectomy: A retrospective cohort study

BackgroundRadical antegrade modular pancreatosplenectomy (RAMPS), a new surgical approach for pancreatic ductal adenocarcinoma of the body and tail, has become increasingly accepted and performed in recent years. Robotic surgery has advantages over open and laparoscopic surgeries in terms of surgical vision and instrument flexibility. However, the lack of comprehension of the learning curve has limited its generalization. This study aimed to evaluate the learning curve of robotic posterior RAMPS. MethodsPatients who underwent robotic posterior RAMPS between February 2017 and April 2021 at our institution were included in this study. Data on patient characteristics, perioperative outcomes, and pathological outcomes were summarized and analyzed. The cumulative sum (CUSUM) method was used to assess the learning curve and inflection points based on operation time and estimated blood loss. ResultsOne hundred consecutive patients who underwent robotic posterior RAMPS were enrolled. The median operation time was 235.0 (interquartile range [IQR], 210.0–270.0) min, and the estimated blood loss was 210.0 (IQR, 165.0–245.0) mL. The grade 3/4 Clavien–Dindo complication rate was 8% (8/100). According to the CUSUM plot, the inflection points of the learning curve were 25 and 65 cases, dividing the case series into the learning (1–25 cases), plateau (26–65 cases), and maturation (66–100 cases) phases. The operation time was relatively high in the learning phase, reached a plateau between 25 and 65 cases (270.0 min vs. 220.0 min, p < 0.01), and decreased significantly in the maturation phase (p < 0.01). Estimated blood loss improved in the maturation phase compared to the learning phase (150.0 vs. 245.0 mL, p < 0.01). No significant differences in conversion rate, complications, or mortality were observed among the three phases. ConclusionThe inflection points of the learning and plateau phases were the 25th and 65th cases, respectively. Robotic RAMPS is safe and feasible even in the learning phase.

Tackling DNA damage repair mechanisms—a promising molecular informed therapeutic approach in pancreatic ductal adenocarcinoma

Molecular targeted therapies in pancreatic ductal adenocarcinoma (PDAC) lag behind treatment options in other tumor entities. The POLO trial has provided promising preliminary data for targeting gBRCA in PDAC by the poly(ADP-ribose) polymerase inhibitor (PARPi) olaparib. This review tries to show further potential approaches to exploit faulty DNA repair mechanisms beyond gBRCA and olaparib.

Long-term oncologic outcomes of robotic and open pancreatectomy in a national cohort of pancreatic adenocarcinoma.

Robotic pancreatectomy is gaining momentum; however, limited data exist on the long-term survival of this approach for pancreatic ductal adenocarcinoma (PDAC). The objective of this study is to compare the long-term oncologic outcomes of robotic pancreaticoduodenectomy (RPD) and robotic distal pancreatectomy (RDP) to open surgery in patients with PDAC. Robotic and open pancreatectomy for stages I-III PDAC were obtained from the 2010 to 2016 National Cancer Database. We identified 17 831 pancreaticoduodenectomies and 2718 distal pancreatectomies of which 626 (4%) and 332 (12%) were robotic, respectively. There was no difference in median overall survival between RPD (22.0 months) and open pancreatoduodenectomy (21.8 months; logrank P = .755). The adjusted hazard ratio [HR] was 1.014 (95% confidence interval [CI]: 0.903-1.139). The median overall survival for RDP (35.3 months) was higher than open distal pancreatectomy (ODP) (24.9 months; logrank P = .001). The adjusted HR suggests a benefit to RDP compared to ODP (HR, 0.744; 95% CI: 0.632-0.868) CONCLUSION: In a national cohort of resected pancreatic adenocarcinoma, the robotic platform was associated with similar long-term survival for pancreaticoduodenectomy, but improved survival for distal pancreatectomy.

A novel therapeutic opportunity for the most aggressive sub‐type of pancreatic cancer: Targeting keratin 17 dependency on nuclear export

Introduction and hypothesesThe purpose of this study was to uncover a novel targeted therapeutic approach for pancreatic ductal adenocarcinoma (PDAC). We previously discovered that keratin 17 (K17) is an independent negative prognostic biomarker for PDAC, where high K17 expression is associated with decreased patient survival. In our pre‐clinical mouse model, PDACs that overexpress K17 were four times more likely than controls to result in fatality within 7 weeks, suggesting that K17 drives tumor aggression. We determined that K17 functions as an oncoprotein by translocating into the nucleus of PDAC cells and enhances XPO‐1‐ mediated nuclear export and degradation of tumor suppressor proteins (TSPs).Here, we hypothesized that 1) K17 depends on nuclear export to drive tumor aggression and is highly sensitive to nuclear inhibition, compared to K17‐negative PDACs, and 2) blocking K17 enhanced XPO‐1‐mediated nuclear export causes enhanced apoptosis and cell cycle arrest.Methods and resultsTo test the hypothesis that K17 depends on nuclear export to drive tumor aggression and is more sensitive to nuclear inhibition than K17‐negative PDACs, we performed pre‐clinical studies in mouse models and orthotopically implanted isogenic murine PDAC cells (LSL‐KrasG12D, LSL‐Trp53R172HPdx‐1‐Cre, KPC) that expressed human K17 (KPC‐K17) or not (KPC‐EV) in immunocompetent animals. After animal randomization, mice were treated three times weekly via oral gavage with selinexor, an inhibitor of the nuclear exporter, XPO‐1, that is currently in phase 2 clinical trials. We found that selinexor inhibited the growth of K17‐positive PDACs in mice, compared to K17‐negative PDACs, suggesting that K17sensitizes PDACs to selinexor treatment. To determine if this decreased tumor growth was due to a tumor‐cell nuclear export blockage, we performed in vitro studies and found that KPC‐K17 cells elicited a four‐fold increase in cell death and a two‐fold increase in G1/S cell cycle arrest compared to KPC‐EV cells. In addition, selinexor treatment led to nuclear retention of K17. To test the dependency of KPC‐K17 cells to K17‐mediated nuclear export, we challenged the cells to chemotherapeutic and targeted therapeutic agents that induce nuclear import inhibition (ivermectin), G1/S transition inhibition (palbociclib), and DNA‐damage (oxaliplatin). In contrast to selinexor treatment, there were no differences in cell death or cell cycle arrest between KPC‐K17 and KPC‐EV cells upon treatment with these compounds.ConclusionsOur results suggest that K17‐positive tumors are specifically vulnerable to inhibition of nuclear export. Given that K17 expression is a biomarker that drives tumor aggression in PDACs, our results suggest that treatment with selinexor is a novel therapeutic opportunity for the most aggressive sub‐type of pancreatic cancer.Support or Funding InformationPancreatic Cancer Action Network

Abstract 4264: Lysosome inhibition sensitizes pancreatic cancer to replication stress by aspartate depletion

Abstract Objective: Functional lysosomes are required for autophagy and macropinocytosis, the intra- and extracellular scavenging pathways cancer cells engage for nutrient acquisition. Pancreatic ductal adenocarcinoma (PDAC) tumors exhibit high basal lysosomal activity, and genetic or pharmacologic inhibition of lysosome function suppresses PDAC cell proliferation and tumor growth. However, the codependencies induced by lysosomal inhibition in PDAC have not been systematically explored. We hypothesized that identification and targeting the lysosomal inhibition-induced codependencies in PDAC cells would be an effective therapeutic strategy. Methods: A comprehensive pharmacological inhibition screen of the protein kinome was performed to identified lysosomal inhibition-induced codependency. LC-MS/MS-MRM and LC-MS methods were used to examine nucleotide biosynthesis and amino acid levels, respectively, to understand the mechanism of the identified codependency. A broad panel of PDAC cell lines, primary PDAC culture models, two- and three-dimentional culture models, a PDAC cell/stroma spheroid coculture model, and xenograft and syngeneic PDAC animal models were used to evaluate the treatment efficacy. Results: We found that replication stress response (RSR) inhibitors were synthetically lethal with chloroquine (CQ) and other lysosomal inhibitors in PDAC cells. CQ treatment reduced de novo nucleotide biosynthesis and induced replication stress. We found that CQ treatment caused mitochondrial dysfunction and depletion of aspartate, an essential precursor for de novo nucleotide synthesis, as an underlying mechanism. Supplementation with aspartate in PDAC cell culture and overexpression of the aspartate transporter SLC1A3 in xenograft PDAC tumors partially rescued the phenotypes induced by CQ. The synergy of CQ and the RSR inhibitor VE-822 was comprehensively validated in a broad panel of PDAC cell lines and primary PDAC cultures, in two- and three-dimentional PDAC cultures, in heterotypic spheroid culture with cancer-associated fibroblasts, and in in vivo xenograft and syngeneic PDAC mouse models. Conclusion: We discovered a codependency on functional lysosomes and an intact RSR pathway in PDAC, and developed the combination of CQ and RSR inhibitors as a translational therapeutic approach for PDAC. Citation Format: Shili Xu, Irmina A. Elliott, Amanda M. Dann, Stephanie S. Kim, Evan R. Abe, Woosuk Kim, Soumya Poddar, Alexandra Moore, Lei Zhou, Jennifer L. Williams, Joseph R. Capri, Razmik Ghukasyan, Cynthia Matsumura, D. Andrew Tucker, Wesley R. Armstrong, Anthony E. Cabebe, Nanping Wu, Luyi Li, Thuc M. Le, Caius G. Radu, Timothy R. Donahue. Lysosome inhibition sensitizes pancreatic cancer to replication stress by aspartate depletion [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 4264.

Liquid Biopsy Approach for Pancreatic Ductal Adenocarcinoma.

Pancreatic cancer is a public health problem because of its increasing incidence, the absence of early diagnostic tools, and its aggressiveness. Despite recent progress in chemotherapy, the 5-year survival rate remains below 5%. Liquid biopsies are of particular interest from a clinical point of view because they are non-invasive biomarkers released by primary tumours and metastases, remotely reflecting disease burden. Pilot studies have been conducted in pancreatic cancer patients evaluating the detection of circulating tumour cells, cell-free circulating tumour DNA, exosomes, and tumour-educated platelets. There is heterogeneity between the methods used to isolate circulating tumour elements as well as the targets used for their identification. Performances for the diagnosis of pancreatic cancer vary depending of the technique but also the stage of the disease: 30–50% of resectable tumours are positive and 50–100% are positive in locally advanced and/or metastatic cases. A significant prognostic value is demonstrated in 50–70% of clinical studies, irrespective of the type of liquid biopsy. Large prospective studies of homogeneous cohorts of patients are lacking. One way to improve diagnostic and prognostic performances would be to use a combined technological approach for the detection of circulating tumour cells, exosomes, and DNA.

High expression of Annexin A2 is associated with DNA repair, metabolic alteration, and worse survival in pancreatic ductal adenocarcinoma

BackgroundAnnexin A2 (ANXA2) is a known driver of cancer progression. We investigated what mechanism associates with ANXA2 high expression and its survival impact using a bioinformatic approach in pancreatic ductal adenocarcinoma. MethodsPrimary pancreatic tumor (n = 185) cohort in The Cancer Genome Atlas and Gene set enrichment analysis were used. ResultsThere were no significant associations between ANXA2 expression and clinicopathologic features of the patients investigated. The ANXA2 high tumors enriched some of the known downstream signaling, such as NF-κB (P = .028) and tumor necrosis factor (P = .044) pathways, whereas others, such as angiogenesis or epithelial-mesenchymal transition, were not associated. ANXA2 high expression tumors enriched DNA repair–related gene sets (DNA repair; P = .011, p53 pathway; P = .036) and cell proliferation–related gene sets (MYC targets; P = .041). In addition, new association with metabolism related gene sets, such as glycolysis (P = .016), nucleic acid metabolism (P = .001), and pyrimidine metabolism (P = .004) were identified in the ANXA2 high group. Patients with high ANXA2 expression demonstrated significantly worse disease-free survival (P = .001) and overall survival (P = .014), with high ANXA2 being an independent risk factor. ConclusionHigh ANXA2 expression was associated with NF-κB and tumor necrosis factor signaling, DNA repair, cell proliferation, and metabolic alteration and worse prognosis in pancreatic ductal adenocarcinoma.

Inhibition of endoplasmic-reticulum-stress-mediated autophagy enhances the effectiveness of chemotherapeutics on pancreatic cancer

BackgroundEndoplasmic reticulum (ER) stress and its consequent unfolded protein response (UPR) are believed to be associated with progression, survival and chemoresistance of a variety of tumor cells through multiple cellular processes, including autophagy. Therefore, the ER stress-autophagy pathway presents a potential molecular target for therapeutic intervention. The objective of this study was to evaluate the therapeutic efficacy of ER stress and autophagy modulators in the context of pancreatic ductal adenocarcinoma (PDAC).MethodsWe first targeted IRE1α, an important regulator of the UPR, through STF-083010 treatment in PDAC cell lines in vitro. Chloroquine was then used to target autophagy and an optimal combination treatment was developed using chloroquine, sunitinib and gemcitabine. Apoptosis was analyzed using TUNEL assay, autophagy was estimated using lysotracker staining and electron microscopy, and UPR was analyzed using anti-GRP78 immunostaining and XBP1 splicing. Transplantation of PDAC derived KPCP1 and Panc02 cells in mouse pancreas were performed to study treatment efficacy in vivo.ResultsSuppression of the IRE1α by STF-083010 alone resulted in increased lysosomes and reduced viability of PDAC cells. Chloroquine treatment alone inhibited downstream autophagy but was insufficient in reducing PDAC cell growth. However, combining STF-083010 and chloroquine had additive anti-tumor efficacy when used with gemcitabine. Sunitinib alone caused abnormal maturation of the autolysosomes with increased intracellular multivesicular bodies and increased apoptosis evident in PDAC cells. Sunitinib showed a synergistic effect with chloroquine in reducing in vitro PDAC cell viability and significantly increased the efficacy of gemcitabine in human and murine PDAC cell lines. The anti-proliferative effect of gemcitabine was significantly increased when used in combination with sunitinib and/or chloroquine in both in vitro and in vivo PDAC models. The addition of sunitinib and/or chloroquine to gemcitabine, resulted in a significantly increased survival of the animals without noticeably increased toxicity. Sunitinib, gemcitabine and chloroquine treated mice showed a significant reduction of GRP78 expression, reduced cell proliferation and increased apoptosis in pancreas, compatible with a tumor response.ConclusionsSunitinib combined with chloroquine reduces tumor growth through suppression of autophagy and increased apoptosis. Co-administration of modulators of ER stress-mediated autophagy with chemotherapy presents a novel therapeutic approach in PDAC.

Therapeutic activity of retroviral replicating vector-mediated prodrug activator gene therapy for pancreatic cancer.

Toca 511, a retroviral replicating vector (RRV) encoding the yeast cytosine deaminase (yCD) prodrug activator gene, which mediates conversion of the prodrug 5-fluorocytosine (5-FC) to the anticancer drug 5-fluorouracil (5-FU), is currently being evaluated in Phase II/III clinical trials for glioma, and showing highly promising evidence of therapeutic activity. Here we evaluated RRV-mediated prodrug activator gene therapy as a new therapeutic approach for pancreatic ductal adenocarcinoma (PDAC). RRV spread rapidly and conferred significant cytotoxicity with prodrug in a panel of PDAC cells. Efficient intratumoral replication and complete inhibition of tumor growth upon 5-FC administration were observed in both immunodeficient and immunocompetent subcutaneous PDAC models. Biodistribution of RRV was highly restricted in normal tissues, especially in immunocompetent hosts. Tumor growth inhibition by Toca 511 followed by 5-FC was also confirmed in the orthotopic PDAC model. This study provides the first proof-of-concept for application of Toca 511 and Toca FC (extended release 5-FC) to the treatment of human PDAC, and provided support for inclusion of PDAC in a Phase I study evaluating Toca 511 in various systemic malignancies, (NCT02576665), which has recently been initiated.

Abstract 1135: DRD2 is critical for pancreatic cancer and promises pharmacological therapy by already established antagonists

Abstract Introduction and aims: Although the overall five-year survival of all patients with cancer stands at 63%, for pancreatic cancer patients, it is a disheartening 8% - a number that remains largely unchanged for three decades. Of the patients diagnosed with pancreatic cancer, about 85% exhibit pancreatic ductal adenocarcinoma (PDAC). Most of these patients die within 4 to 6 months after diagnosis. The poor prognosis is caused by the detection at only late stages, and lack of effective options for chemotherapy. The widely used chemotherapeutic agent gemcitabine, confers a median survival advantage of only 6 months, and resistance to therapy develops in the vast majority of patients. Given this poor prognosis of patients with PDAC, there is an urgent need to find more effective therapies. Experimental procedures: Microarrays were used to perform global gene expression profiling in 195 PDAC and 41 normal pancreatic tissue samples. Using these profiling data, we undertook an extensive analysis of PDAC transcriptome by superimposing the pathway context and interaction networks of aberrantly expressed genes to identify factors with central roles in PDAC pathways. Next, tissue microarray analysis (TMA) were used to verify the expression of the candidate target in independent set of 152 samples comprising 40 normal pancreatic tissues, 49 chronic pancreatitis sections (CP) and 63 PDAC samples. We further validated the functional relevance of the candidate molecule through RNA interference (RNAi) and pharmacological inhibition in vitro and in vivo. Results: We identified dopamine receptor D2 (DRD2) as a key modulator of cancer pathways in PDAC. DRD2 up-regulation at the protein level was validated in a large independent sample cohort. Most importantly, we found that blockade of DRD2, through RNAi or pharmacological inhibition using FDA-approved antagonists hampers the proliferative and invasive capacities of pancreatic cancer cells while modulating cAMP and endoplasmic reticulum stress pathways. Also, we observed a potent effect of DRD2 antagonists on inhibition of cancer cell proliferation using different model of primary and metastatic tumor cells derived from spontaneous pancreatic cancer mouse models and patient-derived pancreatic adenocarcinoma mouse xenograft (PDX) models. Conclusions: Our findings demonstrate that inhibiting DRD2 represents a novel therapeutic approach for PDAC. Since DRD2 inhibitors are already in the clinic for the management of schizophrenia, our results from this study could support a drug repurposing strategy to expedite clinical evaluation of these agents as novel therapy against pancreatic cancer. Citation Format: Pouria Jandaghi, Hamed S. Najafabadi, Andrea Bauer, Andreas I. Papadakis, Matteo Fassan, Anita Hall, Anie Monast, Maryam Safisamghabadi, Magnus von Knebel Doeberitz, John P. Neoptolemos, Eithne Costello, William Greenhalf, Aldo Scarpa, Bence Sipos, Daniel Auld, Mark Lathrop, Morag Park, Markus W. Büchler, Oliver Strobel, Thilo Hackert, Nathalia Giese, George Zogopoulos, Veena Sangwan, Sidong Huang, Jörg D. Hoheisel, Yaser Riazalhosseini. DRD2 is critical for pancreatic cancer and promises pharmacological therapy by already established antagonists [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 1135. doi:10.1158/1538-7445.AM2017-1135

Functional heterogeneity in tumor-derived human pancreatic stellate cells: Differential expression of HGF and implications for mitogenic signaling and migration in pancreatic cancer cells.

The pancreatic stellate cell (PSC) is the principal cell type of the desmoplastic stroma of pancreatic ductal adenocarcinoma (PDAC). PSCs interact with cancer cells and influence the progression of the disease through a complex network of signaling molecules including hepatocyte growth factor (HGF). Functional heterogeneity of PSCs within a tumor might conceivably influence tumor progression. We investigated PSC populations isolated from different human PDACs and examined the effects of PSC-conditioned medium on BxPC-3 and AsPC-1 pancreatic cancer cells. The different PSC populations exhibited a wide range of variation (120−3,000 pg/ml) in their ability to secrete HGF. Media from high-HGF-producing PSCs stimulated phosphorylation of Met, Gab1, and ERK in the cancer cells and induced increases in DNA synthesis and migration which were blocked by the Met inhibitor SU11274, indicating a role of HGF as a mediator. HGF levels produced by PSCs and the effects of PSC media on the cancer cells were increased by IL-1α and inhibited by TGFβ. The functional heterogeneity of PSCs in terms of HGF-mediated tumor-stroma interactions suggests that inhibition of the HGF pathway as a novel treatment approach in PDAC might have different effects in different subsets of patients.

Overcoming erlotinib resistance with STAT3 inhibition in pancreatic cancer.

304 Background: Pancreatic ductal adenocarcinoma (PDAC) remains a major therapeutic challenge. Cytotoxic chemotherapy remains the standard approach in PDAC, but results in minimal survival benefit for patients, highlighting a desperate need for novel treatment strategies. Epidermal growth factor receptor (EGFR) is overexpressed in 25-90% of PDACs and has been shown to be an adverse prognostic marker for survival, making it a rational target. To date, the combination of the EGFR tyrosine kinase inhibitor, erlotinib, with gemcitabine remains the only approved targeted therapy based on a significant, yet modest, improved overall survival when compared to gemcitabine alone in a phase III clinical trial. We have previously shown that constitutively activated signal transducer and activator of transcription 3 (STAT3) signaling is a biomarker of resistance to both gemcitabine and erlotinib. Therefore, we hypothesized that combined STAT3 and EGFR inhibition would overcome resistance to erlotinib and gemcitabine in PDAC. Methods: Human pancreatic cancer cell lines MiaPaca2 ( KRASG12C ; TP53mut ; EGFRwt) or BxPC-3 ( KRASwt ; TP53mut ; EGFRwt) were treated in a dose dependent manner with erlotinib in the presence or absence of gemcitabine. PDAC cells were additionally treated with EC50doses of a STAT3 inhibitor (AZD1480), erlotinib, and/or gemcitabine. Lysates were then collected and western blot analysis was performed to detect total and phosphorylated extracellular signal regulated kinase (ERK) or STAT3. Results: EGFR inhibition with erlotinib, with or without gemcitabine, results in decreased ERK activation, however, causes an increased activation of STAT3 signaling in both MiaPaca2 and BxPC-3 cells. Combined STAT3 and EGFR inhibition results in sustained attenuation of both phosphorylated ERK and STAT3 levels. Conclusions: Our study demonstrates that activated STAT3 signaling appears to be a mechanism of resistance to erlotinib and gemicitabine treatment in PDAC. Combining STAT3 inhibition with EGFR inhibition overcomes this resistance.

Abstract B27: Interdicting the cytokine-mediated paracrine communication between pancreatic cancer and stellate cells as a new treatment approach for pancreatic ductal adenocarcinoma

Abstract Cell-cell interactions within the tumor microenvironment play critical roles in tumor progression and its response to various therapies. Specifically in the case of pancreatic cancer, pancreatic cancer cells (PCCs) act on pancreatic stellate cells (PSCs), a major stromal cell type within the pancreatic tumor microenvironment, to provoke their transformation into and sustain an activated state, while activated PSCs interact with PCCs to promote tumor progression and confer a favorable environment for PCC resistance to immunosuppression and therapeutic treatment, setting up a vicious cycle. Therefore, effectively attacking the stromal PSCs alone or together with tumor cells may offer a new therapeutic route for pancreatic ductal adenocarcinoma (PDA) treatment. To identify key signaling molecules or pathways activated as a result of PSC-PCC interactions that might be targeted in pancreatic cancer as novel therapies, we developed unbiased quantitative mass spectrometry (MS)-based proteomics strategies to perform systemic analysis. Our comprehensive molecular and cellular analysis of in vitro PSC and PSC co-culture unraveled many interesting secreted proteins, either known or unknown previously, involved in the paracrine PCC-PSC crosstalk. We mainly focused on an intriguing signaling loop, in which PCCs secrete PDGFs that act on PSCs to promote the production of inflammatory cytokines by PSCs, including IL-6 family members, and especially LIF. These cytokines then act on PCCs to stimulate STAT3 activation, a known critical event for PDA initiation and progression. Significantly increased production of the cytokines and expression of corresponding receptors in both mouse and human PDA tumor contexts at both mRNA and protein levels were confirmed using various techniques. To further evaluate the functional significance of LIF in paracrine regulation of PDA progression in vivo, we exploited therapeutic blockage of the signaling using neutralizing mAbs and specific small molecule inhibitors in the classical KPC mouse PDA model. Our preclinical studies revealed significant efficacy of an anti-LIF mAb in increasing sensitivity to the standard-of-care chemotherapeutic gemcitabine, reducing tumor progression and prolonging survival of KPC mice. Currently, the molecular mechanisms underlying this sensitization are being investigated. Genetic studies using LIF receptor conditional knockout mice were also performed and showed significant beneficial effects. Furthermore, potential correlations between tissue or serum LIF and IL-6 cytokine levels and overall survival of human patients are also being evaluated. Citation Format: Yu Shi, Ruijun Tian, Tony Hunter.{Authors}. Interdicting the cytokine-mediated paracrine communication between pancreatic cancer and stellate cells as a new treatment approach for pancreatic ductal adenocarcinoma. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2016 May 12-15; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2016;76(24 Suppl):Abstract nr B27.

Abstract B66: BET inhibition remodels tumor stroma and suppresses progression of human pancreatic cancer

Abstract Background and Aims: Pancreatic ductal adenocarcinoma (PDAC) is well characterized by dense fibrotic stroma with abundant cancer-associated fibroblasts (CAFs). As CAFs are activated during tumorigenesis and acquire tumor-promoting properties, activated CAFs have been implicated in PDAC progression; however, the precise mechanisms of their activation remain largely unknown. The bromodomain and extraterminal (BET) domain proteins are epigenetic reader proteins that recognize acetylated amino acid residues on histone tails and facilitate gene transcription. Recent studies have demonstrated therapeutic efficacy of BET inhibitors on various cancers including PDAC, mainly through suppression of c-myc transcription; however, how BET inhibitors suppress PDAC growth and their effects on CAFs remains largely unknown. Using patient-derived tumor xenografts (PDX) and primary CAFs, we investigated the therapeutic efficacy and dissected the underlying mechanisms of a BET inhibitor, JQ1, on human PDAC and CAFs. Methods: We established PDX lines and primary CAFs from surgically resected human PDAC specimen. For in vivo analyses, mice bearing subcutaneous tumor were treated with vehicle or JQ1. For in vitro analyses, patient-derived PDAC cells and CAFs were treated with vehicle or JQ1 and analyzed separately. To explore the pro-tumorigenic role of secretion from CAFs, PDAC cells were cultured with conditioned medium (CM) that was collected from DMSO- or JQ1- treated CAFs. Chromatin immunoprecipitation (ChIP) assay was performed to assess the binding of transcription factors and histone modifications which are associated with altered gene expression in CAFs by JQ1 treatment. Results: In vivo experiments revealed that volumes and weights of subcutaneous PDX tumors were significantly smaller in JQ1-treated mice than vehicle-treated mice. Unexpectedly, however, JQ1 exerted only minimal effects to the proliferation of PDAC cells that were isolated from PDX tumors and cultured in vitro, suggesting the involvement of cell-extrinsic mechanisms in the JQ1-mediated suppression of tumor growth in vivo. Of note, histopathological analysis of PDX tumors revealed that JQ1 treatment dramatically ameliorated desmoplastic change, with reduction in extracellular matrix (ECM) deposition and α-SMA expressing CAFs. As α-SMA expression and ECM production is a hallmark of activated CAFs, we hypothesized that JQ1 might inactivate CAFs, thereby reducing their tumor-promoting properties. To test this hypothesis, qPCR was performed to analyze gene expression in primary CAFs cultured in vitro and also in stromal cells in PDX tumors in vivo. As expectedly, JQ1 suppressed the expression of genes implicated in the properties of activated CAF, including ECM, cytokines and growth factors both in vitro and in vivo. Furthermore, when PDAC cells were cultured with CM from DMSO–treated CAFs, proliferation of PDAC cells were promoted along with activation of MAPK, AKT, and STAT3 pathways, which was abrogated when cultured with CM from JQ1-treated CAFs. Consistently, immunoblotting and immunohistochemistry of PDX tumors demonstrated that JQ1 reduced phosphorylation of ERK, AKT, and STAT3 in PDAC cells in vivo. Mechanistically, we found that JQ1 suppressed hedgehog and TGF-β/SMAD3 pathways, both of which play central roles in CAF activation, through disruption of BRD4 recruitment to the promoter regions of their target genes. Conclusions: BET proteins are critical regulators of CAF-activation in PDAC. Inactivation of CAFs by BET inhibition offers a novel therapeutic approach for PDAC. Citation Format: Keisuke Yamamoto, Keisuke Tateishi, Yotaro Kudo, Mayumi Hoshikawa, Mariko Tanaka, Takuma Nakatsuka, Hiroaki Fujiwara, Koji Miyabayashi, Ryota Takahashi, Yasuo Tanaka, Hideaki Ijichi, Yousuke Nakai, Hiroyuki Isayama, Yasuyuki Morishita, Taku Aoki, Yoshihiro Sakamoto, Kiyoshi Hasegawa, Norihiro Kokudo, Masashi Fukayama, Kazuhiko Koike.{Authors}. BET inhibition remodels tumor stroma and suppresses progression of human pancreatic cancer. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2016 May 12-15; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2016;76(24 Suppl):Abstract nr B66.