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Background: The long-term outcomes following surgical resection for pancreatic ductal adenocarcinoma (PDAC) remains poor, with only 20% of patients surviving 5 years after pancreatectomy. Patient selection for surgery remains sub-optimal largely due to the absence of consideration of aggressive tumor biology. Objective: The aim of this study was to evaluate traditional staging criteria for PDAC in the setting of molecular subtypes. Methods: Clinicopathological data were obtained for 5 independent cohorts of consecutive unselected patients, totaling n = 1298, including n = 442 that underwent molecular subtyping. The main outcome measure was disease-specific survival following surgical resection for PDAC stratified according to the American Joint Commission for Cancer (TNM) staging criteria, margin status, and molecular subtype. Results: TNM staging criteria and margin status confers prognostic value only in tumors with classical pancreatic subtype. Patients with tumors that are of squamous subtype, have a poor outcome irrespective of favorable traditional pathological staging [hazard ratio (HR) 1.54, 95% confidence interval (CI) 1.04–2.28, P = 0.032]. Margin status has no impact on survival in the squamous subtype (16.0 vs 12.1 months, P = 0.374). There were no differences in molecular subtype or gene expression of tumors with positive resection margin status. Conclusions: Aggressive tumor biology as measured by molecular subtype predicts poor outcome following pancreatectomy for PDAC and should be utilized to inform patient selection for surgery.

FOLFIRINOX, a combination of chemotherapy drugs (Fluorouracil, Oxaliplatin, Irinotecan -FOI), provides the best clinical benefit in pancreatic ductal adenocarcinoma (PDAC) patients. In this study we explore the role of miRNAs (MIR) as modulators of chemosensitivity to identify potential biomarkers of response. We find that 41 and 84 microRNA inhibitors enhance the sensitivity of Capan1 and MiaPaCa2 PDAC cells respectively. These include a MIR1307-inhibitor that we validate in further PDAC cell lines. Chemotherapy-induced apoptosis and DNA damage accumulation are higher in MIR1307 knock-out (MIR1307KO) versus control PDAC cells, while re-expression of MIR1307 in MIR1307KO cells rescues these effects. We identify binding of MIR1307 to CLIC5 mRNA through covalent ligation of endogenous Argonaute-bound RNAs cross-linking immunoprecipitation assay. We validate these findings in an in vivo model with MIR1307 disruption. In a pilot cohort of PDAC patients undergoing FOLFIRONX chemotherapy, circulating MIR1307 correlates with clinical outcome., Understanding which patients will respond to FOLFIRINOX therapy is important for clinical outcome. Here, the authors show that the MIR1307 is increased pancreatic cancer cell lines and inhibition of the microRNA sensitises cells to treatment.’ stratifying patients to achieve the best clinical outcome. Here, the authors show that the MIR1307 is increased in a subgroup of human pancreatic cancers and inhibition of the microRNA in in vitro and in vivo models of pancreatic cancer sensitises cells to treatment.

Immunotherapy for the treatment of Pancreatic Ductal Adenocarcinoma (PDAC) has shown limited efficacy. Poor CD8 T-cell infiltration, low neoantigen load and a highly immunosuppressive tumor microenvironment are key factors that contribute to this lack of response. Here, we identify a novel role for Focal Adhesion Kinase (FAK) in regulating type-II interferon signalling in human and murine PDAC cells and tumors, leading to suppression of antigen processing and presentation pathways critical for T-cell tumor recognition. We find that FAK loss promotes expression of the immunoproteasome and MHC-I, resulting in a significant increase in the diversity of antigens presented by FAK-/- PDAC cells. We show that regulation of the immunoproteasome subunit Psmb8 (β5i) is a critical determinant of this response, optimising the physicochemical properties of the peptide repertoire for high-affinity binding to MHC-I. Expression of the immunoproteasome and MHC-I can be further amplified in a STAT1-dependent manner via co-depletion of FAK and STAT3, leading to extensive CD8 T-cell infiltration into PDAC tumors and further restraint of tumor growth. Regulation of antigen processing and presentation by FAK preferentially occurs in human and murine PDAC cells and tumors of the classical/progenitor molecular subtype, further suggesting that precision medicine approaches based on molecular subtyping should be integrated into current and future clinical testing of FAK targeted therapies for the treatment of pancreatic cancer. Citation Format: Marta Canel, Aleksandra Slawinska, David W. Lonergan, Ashwin A. Kallor, Rosie Upstill-Goddard, Catherine Davidson, Alex von Kriegsheim, Andrew V. Biankin, Adam Bryron, Javier Alfaro, Alan Serrels. FAK suppresses antigen processing and presentation to promote immune evasion in pancreatic cancer [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 C019.

Background & Aims Continuing recalcitrance to therapy cements pancreatic cancer (PC) as the most lethal malignancy, which is set to become the second leading cause of cancer death in our society. The study aim was to investigate the association between DNA damage response (DDR), replication stress, and novel therapeutic response in PC to develop a biomarker-driven therapeutic strategy targeting DDR and replication stress in PC. Methods We interrogated the transcriptome, genome, proteome, and functional characteristics of 61 novel PC patient–derived cell lines to define novel therapeutic strategies targeting DDR and replication stress. Validation was done in patient-derived xenografts and human PC organoids. Results Patient-derived cell lines faithfully recapitulate the epithelial component of pancreatic tumors, including previously described molecular subtypes. Biomarkers of DDR deficiency, including a novel signature of homologous recombination deficiency, cosegregates with response to platinum (P < .001) and PARP inhibitor therapy (P < .001) in vitro and in vivo. We generated a novel signature of replication stress that predicts response to ATR (P < .018) and WEE1 inhibitor (P < .029) treatment in both cell lines and human PC organoids. Replication stress was enriched in the squamous subtype of PC (P < .001) but was not associated with DDR deficiency. Conclusions Replication stress and DDR deficiency are independent of each other, creating opportunities for therapy in DDR-proficient PC and after platinum therapy., Graphical abstract

Ovarian carcinosarcoma (OCS) is an aggressive and rare tumour type with limited treatment options. OCS is hypothesised to develop via the combination theory from a single progenitor, resulting in carcinomatous and sarcomatous components, or alternatively via the conversion theory, with the sarcomatous component developing from the carcinomatous component through epithelial-to-mesenchymal transition (EMT). We show OCS from 18 women to be monoclonal through analysis of DNA variants from isolated carcinoma and sarcoma components. RNA sequencing indicated the carcinoma components were more mesenchymal when compared with pure ovarian carcinomas, supporting the conversion theory. We used pre-clinical OCS models to test the efficacy of microtubule-targeting drugs, including eribulin, which has been shown to reverse EMT characteristics. We demonstrated that microtubule inhibitors, vinorelbine and eribulin, were more effective than standard-of-care platinum-based chemotherapy. Eribulin reduced mesenchymal characteristics, N-MYC expression and cholesterol biosynthesis. Finally, eribulin induced a strong immune response, supporting immunotherapy combinations in the clinic.

Summary Disrupted chromatin regulatory processes contribute to the development of cancer, in particular pancreatic ductal adenocarcinoma. The assay for transposase accessible chromatin with high-throughput sequencing (ATAC-seq) is typically used to study chromatin organization. Here, we present a revised ATAC-seq protocol to study chromatin accessibility in adherent patient-derived cell lines. We provide details on how to calculate the library molarity using Agilent’s Bioanalyzer and an analysis pipeline for peak calling and transcription factor mapping. For complete details on the use and execution of this protocol, please refer to Brunton et al. (2020)., Graphical Abstract, Highlights • ATAC-seq protocol to measure chromatin accessibility in patient-derived cell lines • Includes detailed size selection library clean-up step • Instructions on how to calculate the library molarity using Agilent Bioanalyzer • A comprehensive data analysis pipeline is provided, Disrupted chromatin regulatory processes contribute to the development of cancer, in particular pancreatic ductal adenocarcinoma. The assay for transposase accessible chromatin with high-throughput sequencing (ATAC-seq) is typically used to study chromatin organization. Here, we present a revised ATAC-seq protocol to study chromatin accessibility in adherent patient-derived cell lines. We provide details on how to calculate the library molarity using Agilent’s Bioanalyzer and an analysis pipeline for peak calling and transcription factor mapping.

Pancreatic ductal adenocarcinoma (PDAC) can be divided into transcriptomic subtypes with two broad lineages referred to as classical (pancreatic) and squamous. We find that these two subtypes are driven by distinct metabolic phenotypes. Loss of genes that drive endodermal lineage specification, HNF4A and GATA6, switch metabolic profiles from classical (pancreatic) to predominantly squamous, with glycogen synthase kinase 3 beta (GSK3β) a key regulator of glycolysis. Pharmacological inhibition of GSK3β results in selective sensitivity in the squamous subtype; however, a subset of these squamous patient-derived cell lines (PDCLs) acquires rapid drug tolerance. Using chromatin accessibility maps, we demonstrate that the squamous subtype can be further classified using chromatin accessibility to predict responsiveness and tolerance to GSK3β inhibitors. Our findings demonstrate that distinct patterns of chromatin accessibility can be used to identify patient subgroups that are indistinguishable by gene expression profiles, highlighting the utility of chromatin-based biomarkers for patient selection in the treatment of PDAC.

Continuing recalcitrance to therapy cements pancreatic cancer (PC) as the most lethal malignancy, which is set to become the second leading cause of cancer death in our society. We interrogated the transcriptome, genome, proteome and functional characteristics of 61 novel PC patient-derived cell lines to define novel therapeutic strategies targeting the DNA damage response (DDR) and replication stress. We show that patient-derived cell lines faithfully recapitulate the epithelial component of pancreatic tumors including previously described molecular subtypes. Biomarkers of DDR deficiency, including a novel signature of homologous recombination deficiency, co-segregates with response to platinum and PARP inhibitor therapy in vitro and in vivo. We generated a novel signature of replication stress with potential clinical utility in predicting response to ATR and WEE1 inhibitor treatment. Replication stress and DDR deficiency are independent of each other, creating opportunities for therapy in DDR proficient PC, and post-platinum therapy.Abstract FigureSTATEMENT OF SIGNIFICANCEWe define therapeutic strategies that target subgroups of PC using novel signatures of DNA damage response deficiency and replication stress. This potentially offers patients with DNA repair defects therapeutic options outside standard of care platinum chemotherapy and is being tested in clinical trials on the Precision-Panc platform.

The identification of molecularly defined subgroups of Pancreatic ductal Adenocarcinoma (PDAC) has the potential to transform clinical practice. There is now a growing consensus that PDAC can be divided into transcriptomic subtypes with 2 broad linages referred to as Classical (Pancreatic) and Squamous. We find that these two subtypes are driven by distinct metabolic phenotypes. Loss of genes that drive endodermal linage specification, HNF4A and GATA6, switch metabolic profiles from Classical (Pancreatic) to predominantly Squamous, with GSK3B a key regulator of glycolysis. Pharmacological inhibition of GSK3B results in selective sensitivity in the Squamous subtype, however a subset of these Squamous PDCLs acquired rapid drug tolerance. Using chromatin accessibility maps, we identify subtype specific chromatin landscapes and unique promoter usage between subpopulations of Squamous PDCLs can affect drug tolerance. Our findings demonstrate that a chromatin-based framework can be used to identify subtypes of PDAC that are indistinguishable by gene expression profiles which could refine patient selection for precision medicine.

285 Background: Integrated multi-omic analyses revealed 24% of pancreatic cancer (PC) harbor defects in DNA damage response (DDR) and a subgroup demonstrate upregulation in replication stress pathways. DDR defective tumors preferentially respond to DNA damaging agents, and clinical responses to cell cycle inhibitors are seen in undefined subgroups, representing novel therapeutic strategies for PC. The aim of this study is to define and refine therapeutic segments for agents targeting DDR and replication stress in PC. Methods: We performed whole genome and RNA sequencing (RNAseq) on 48 patient-derived cell lines (PDCL) generated and characterized as part of the International Cancer Genome Initiative (ICGC). This identified increased replication stress in a sub-group of tumours, correlating with previously defined molecular subtypes of PC, irrespective of DDR status. Cytotoxic viability assays were performed using agents targeting the DDR pathway and cell cycle checkpoints, including Cisplatin, and inhibitors of PARP, ATR, WEE1, CHK1, CDK4/6 and PLK4. Subcutaneous patient derived xenografts (PDX) were generated to test therapeutic regimens in vivo. Results: DDR defective models, as defined by signatures of homologous recombination deficiency (HRD) were highly sensitive to Cisplatin and PARP inhibitors. Replication stress predicted differential responses to cell cycle inhibitors of WEE1, CHK1, CDK4/6 and PLK4. A novel mRNA signature of ATR inhibitor sensitivity was generated and correlated with response. Response to cell cycle checkpoint inhibitors were independent of DDR status, but strongly associated with replication stress. Conclusions: This proof of concept data demonstrates DDR deficiency and increased Replication Stress to be attractive targets in PC. Therapeutic vulnerabilities extend beyond platinum chemotherapy and can be targeted with novel small molecule inhibitors, with independent biomarkers predicting response to agents targeting either DDR or cell cycle checkpoints. This has led to the design and development of several personalized medicine trials via the Precision Panc platform targeting DDR and Replication stress, and will allow clinical testing of signatures of HRD and replication stress.

Individuals from three families ascertained in Bogota, Colombia, showing syndromic phenotypes, including cleft lip and/or palate, were exome-sequenced. In each case, sequencing revealed the underlying causal variation confirming or establishing diagnoses. The findings include very rare and novel variants providing insights into genotype and phenotype relationships. These include the molecular diagnosis of an individual with Nager syndrome and a family exhibiting an atypical incontinentia pigmenti phenotype with a missense mutation in IKBKG. IKBKG mutations are typically associated with preterm male death, but this variant is associated with survival for 8-15 days. The third family exhibits unusual phenotypic features and the proband received a provisional diagnosis of Pierre Robin sequence (PRS). Affected individuals share a novel deleterious mutation in IRF6. Mutations in IRF6 cause Van der Woude and popliteal pterygium syndrome and contribute to nonsyndromic cleft lip phenotypes but have not previously been associated with a PRS phenotype. Exome sequencing followed by in silico screening to identify candidate causal variant(s), and functional assay in some cases offers a powerful route to establishing molecular diagnoses. This approach is invaluable for conditions showing phenotypic and/or genetic heterogeneity including cleft lip and/or palate phenotypes where many underlying causal genes have not been identified.