Hervé Tiriac

Pancreatic stellate cells (PSCs) differentiate into cancer-associated fibroblasts (CAFs) that produce desmoplastic stroma, thereby modulating disease progression and therapeutic response in pancreatic ductal adenocarcinoma (PDA). However, it is unknown whether CAFs uniformly carry out these tasks or if subtypes of CAFs with distinct phenotypes in PDA exist. We identified a CAF subpopulation with elevated expression of α-smooth muscle actin (αSMA) located immediately adjacent to neoplastic cells in mouse and human PDA tissue. We recapitulated this finding in co-cultures of murine PSCs and PDA organoids, and demonstrated that organoid-activated CAFs produced desmoplastic stroma. The co-cultures showed cooperative interactions and revealed another distinct subpopulation of CAFs, located more distantly from neoplastic cells, which lacked elevated αSMA expression and instead secreted IL6 and additional inflammatory mediators. These findings were corroborated in mouse and human PDA tissue, providing direct evidence for CAF heterogeneity in PDA tumor biology with implications for disease etiology and therapeutic development.

Pancreatic cancer is one of the most lethal malignancies due to its late diagnosis and limited response to treatment. Tractable methods to identify and interrogate pathways involved in pancreatic tumorigenesis are urgently needed. We established organoid models from normal and neoplastic murine and human pancreas tissues. Pancreatic organoids can be rapidly generated from resected tumors and biopsies, survive cryopreservation, and exhibit ductal- and disease-stage-specific characteristics. Orthotopically transplanted neoplastic organoids recapitulate the full spectrum of tumor development by forming early-grade neoplasms that progress to locally invasive and metastatic carcinomas. Due to their ability to be genetically manipulated, organoids are a platform to probe genetic cooperation. Comprehensive transcriptional and proteomic analyses of murine pancreatic organoids revealed genes and pathways altered during disease progression. The confirmation of many of these protein changes in human tissues demonstrates that organoids are a facile model system to discover characteristics of this deadly malignancy.

The poor clinical outcome in pancreatic ductal adenocarcinoma (PDA) is attributed to intrinsic chemoresistance and a growth-permissive tumor microenvironment. Conversion of quiescent to activated pancreatic stellate cells (PSCs) drives the severe stromal reaction that characterizes PDA. Here, we reveal that the vitamin D receptor (VDR) is expressed in stroma from human pancreatic tumors and that treatment with the VDR ligand calcipotriol markedly reduced markers of inflammation and fibrosis in pancreatitis and human tumor stroma. We show that VDR acts as a master transcriptional regulator of PSCs to reprise the quiescent state, resulting in induced stromal remodeling, increased intratumoral gemcitabine, reduced tumor volume, and a 57% increase in survival compared to chemotherapy alone. This work describes a molecular strategy through which transcriptional reprogramming of tumor stroma enables chemotherapeutic response and suggests vitamin D priming as an adjunct in PDA therapy. PAPERFLICK:

Abstract Pancreatic cancer is the most lethal common solid malignancy. Systemic therapies are often ineffective, and predictive biomarkers to guide treatment are urgently needed. We generated a pancreatic cancer patient–derived organoid (PDO) library that recapitulates the mutational spectrum and transcriptional subtypes of primary pancreatic cancer. New driver oncogenes were nominated and transcriptomic analyses revealed unique clusters. PDOs exhibited heterogeneous responses to standard-of-care chemotherapeutics and investigational agents. In a case study manner, we found that PDO therapeutic profiles paralleled patient outcomes and that PDOs enabled longitudinal assessment of chemosensitivity and evaluation of synchronous metastases. We derived organoid-based gene expression signatures of chemosensitivity that predicted improved responses for many patients to chemotherapy in both the adjuvant and advanced disease settings. Finally, we nominated alternative treatment strategies for chemorefractory PDOs using targeted agent therapeutic profiling. We propose that combined molecular and therapeutic profiling of PDOs may predict clinical response and enable prospective therapeutic selection. Significance: New approaches to prioritize treatment strategies are urgently needed to improve survival and quality of life for patients with pancreatic cancer. Combined genomic, transcriptomic, and therapeutic profiling of PDOs can identify molecular and functional subtypes of pancreatic cancer, predict therapeutic responses, and facilitate precision medicine for patients with pancreatic cancer. Cancer Discov; 8(9); 1112–29. ©2018 AACR. See related commentary by Collisson, p. 1062. This article is highlighted in the In This Issue feature, p. 1047

Abscisic acid (ABA) signal transduction has been proposed to utilize cytosolic Ca(2+) in guard cell ion channel regulation. However, genetic mutants in Ca(2+) sensors that impair guard cell or plant ion channel signaling responses have not been identified, and whether Ca(2+)-independent ABA signaling mechanisms suffice for a full response remains unclear. Calcium-dependent protein kinases (CDPKs) have been proposed to contribute to central signal transduction responses in plants. However, no Arabidopsis CDPK gene disruption mutant phenotype has been reported to date, likely due to overlapping redundancies in CDPKs. Two Arabidopsis guard cell-expressed CDPK genes, CPK3 and CPK6, showed gene disruption phenotypes. ABA and Ca(2+) activation of slow-type anion channels and, interestingly, ABA activation of plasma membrane Ca(2+)-permeable channels were impaired in independent alleles of single and double cpk3cpk6 mutant guard cells. Furthermore, ABA- and Ca(2+)-induced stomatal closing were partially impaired in these cpk3cpk6 mutant alleles. However, rapid-type anion channel current activity was not affected, consistent with the partial stomatal closing response in double mutants via a proposed branched signaling network. Imposed Ca(2+) oscillation experiments revealed that Ca(2+)-reactive stomatal closure was reduced in CDPK double mutant plants. However, long-lasting Ca(2+)-programmed stomatal closure was not impaired, providing genetic evidence for a functional separation of these two modes of Ca(2+)-induced stomatal closing. Our findings show important functions of the CPK6 and CPK3 CDPKs in guard cell ion channel regulation and provide genetic evidence for calcium sensors that transduce stomatal ABA signaling.

Pancreatic adenocarcinoma presents as a spectrum of a highly aggressive disease in patients. The basis of this disease heterogeneity has proved difficult to resolve due to poor tumor cellularity and extensive genomic instability. To address this, a dataset of whole genomes and transcriptomes was generated from purified epithelium of primary and metastatic tumors. Transcriptome analysis demonstrated that molecular subtypes are a product of a gene expression continuum driven by a mixture of intratumoral subpopulations, which was confirmed by single-cell analysis. Integrated whole-genome analysis uncovered that molecular subtypes are linked to specific copy number aberrations in genes such as mutant KRAS and GATA6. By mapping tumor genetic histories, tetraploidization emerged as a key mutational process behind these events. Taken together, these data support the premise that the constellation of genomic aberrations in the tumor gives rise to the molecular subtype, and that disease heterogeneity is due to ongoing genomic instability during progression. Whole-genome sequencing, transcriptome sequencing and single-cell analysis of primary and metastatic pancreatic adenocarcinoma identify molecular subtypes and intratumor heterogeneity.

Pancreatic ductal adenocarcinoma (PDA) is one of the most lethal human malignancies, owing in part to its propensity for metastasis. Here, we used an organoid culture system to investigate how transcription and the enhancer landscape become altered during discrete stages of disease progression in a PDA mouse model. This approach revealed that the metastatic transition is accompanied by massive and recurrent alterations in enhancer activity. We implicate the pioneer factor FOXA1 as a driver of enhancer activation in this system, a mechanism that renders PDA cells more invasive and less anchorage-dependent for growth in vitro, as well as more metastatic in vivo. In this context, FOXA1-dependent enhancer reprogramming activates a transcriptional program of embryonic foregut endoderm. Collectively, our study implicates enhancer reprogramming, FOXA1 upregulation, and a retrograde developmental transition in PDA metastasis.

Pancreatic cancer is a deadly malignancy that lacks effective therapeutics. We previously reported that oncogenic Kras induced the redox master regulator Nfe2l2/Nrf2 to stimulate pancreatic and lung cancer initiation. Here, we show that NRF2 is necessary to maintain pancreatic cancer proliferation by regulating mRNA translation. Specifically, loss of NRF2 led to defects in autocrine epidermal growth factor receptor (EGFR) signaling and oxidation of specific translational regulatory proteins, resulting in impaired cap-dependent and cap-independent mRNA translation in pancreatic cancer cells. Combined targeting of the EGFR effector AKT and the glutathione antioxidant pathway mimicked Nrf2 ablation to potently inhibit pancreatic cancer ex vivo and in vivo, representing a promising synthetic lethal strategy for treating the disease.

PDA is an extremely aggressive and lethal malignancy. There is an urgent need for research advances that could lead to improved outcomes and earlier diagnoses for PDA. While the mainstays of PDA research have traditionally been genetically engineered mouse models, as well as PDA cell lines cultured as monolayers and patient-derived xenografts, each of these model systems suffers from limitations. Organotypic culture methods, in which cells are cultured in 3D under conditions intended to mimic those in the body, have emerged as powerful new systems to circumvent some of the limitations of other models. Recently, four different methods for modeling PDA as organotypic, organoid cultures have been reported. These methods allow researchers to rapidly make new discoveries about pancreatic tumorigenesis that are highly relevant to human patients. Pancreatic ductal adenocarcinoma (PDA) is a highly lethal malignancy for which new treatment and diagnostic approaches are urgently needed. For such breakthroughs to be discovered, researchers require systems that accurately model the development and biology of PDA. While cell lines, genetically engineered murine models, and xenografts have all led to valuable clinical insights, organotypic culture models have emerged as tractable systems to recapitulate the complex 3D organization of PDA. Recently, multiple methods for modeling PDA using organoids have been reported. This review aims to summarize these organoid methods in the context of other PDA models. While each model system has unique benefits and drawbacks, ultimately, organoids hold special promise for the development of personalized medicine approaches. Pancreatic ductal adenocarcinoma (PDA) is a highly lethal malignancy for which new treatment and diagnostic approaches are urgently needed. For such breakthroughs to be discovered, researchers require systems that accurately model the development and biology of PDA. While cell lines, genetically engineered murine models, and xenografts have all led to valuable clinical insights, organotypic culture models have emerged as tractable systems to recapitulate the complex 3D organization of PDA. Recently, multiple methods for modeling PDA using organoids have been reported. This review aims to summarize these organoid methods in the context of other PDA models. While each model system has unique benefits and drawbacks, ultimately, organoids hold special promise for the development of personalized medicine approaches.

Sweet bystander becomes a villain Patients with pancreatic cancer often have elevated blood levels of CA19-9, a carbohydrate antigen present on many proteins. CA19-9 is thus commonly used as a biomarker for diagnosing and monitoring disease progression. In a study of mice, Engle et al. found that CA19-9 may be more than an innocent bystander that marks the presence of pancreatic disease; it may play a causal role in disease (see the Perspective by Halbrook and Crawford). Transgenic mice expressing the human enzymes that add CA19-9 to proteins developed severe pancreatitis that could be reversed by treatment with CA19-9 antibodies. When the transgenic mice also harbored a Kras oncogene, they went on to develop pancreatic cancer. These unexpected observations suggest new avenues for the treatment of pancreatic disease. Science , this issue p. 1156 ; see also p. 1132

The aberrant expression of squamous lineage markers in pancreatic ductal adenocarcinoma (PDA) has been correlated with poor clinical outcomes. However, the functional role of this putative transdifferentiation event in PDA pathogenesis remains unclear. Here, we show that expression of the transcription factor TP63 (ΔNp63) is sufficient to install and sustain the enhancer landscape and transcriptional signature of the squamous lineage in human PDA cells. We also demonstrate that TP63-driven enhancer reprogramming promotes aggressive tumor phenotypes, including enhanced cell motility and invasion, and an accelerated growth of primary PDA tumors and metastases in vivo. This process ultimately leads to a powerful addiction of squamous PDA cells to continuous TP63 expression. Our study demonstrates the functional significance of squamous transdifferentiation in PDA and reveals TP63-based reprogramming as an experimental tool for investigating mechanisms and vulnerabilities linked to this aberrant cell fate transition.

Pancreatic cancer organoids are tumor models of individualized human pancreatic ductal adenocarcinoma (PDA), created from surgical specimens and used for personalized treatment strategies. Unfortunately, most patients with PDA are not operative candidates. Creation of human PDA organoids at the time of initial tumor diagnosis is therefore critical. Our aim was to assess the feasibility of creating human PDA organoids by EUS fine-needle biopsy (EUS-FNB) sampling in patients with PDA.In this prospective clinical trial in patients referred to evaluate a pancreatic mass, EUS-FNA was performed for initial onsite diagnosis. Two additional needle passes were performed with a 22-gauge FNB needle for organoid creation. Primary outcome was successful isolation of organoids within 2 weeks of EUS-FNB sampling (P0, no passages), confirmed by organoid morphology and positive genotyping.Thirty-seven patients with 38 PDA tumors were enrolled. Successful isolation of organoids (P0) was achieved in 33 of 38 tumors (87%). Establishment of PDA organoid lines for ≥5 passages of growth (P5, five passages) was reached in 25 of 38 tumors (66%). In the single patient with successful P5 FNB sampling-derived and P5 surgically derived organoids, there was identical matching of specimens. There were no serious adverse events. Two patients developed bleeding at the EUS-FNB puncture site requiring hemostasis clips.Pancreatic cancer organoids can be successfully and rapidly created by means of EUS-FNB sampling using a 22-gauge needle at the time of initial diagnosis. Successful organoid generation is essential for precision medicine in patients with pancreatic cancer in whom most are not surgically resectable. (Clinical trial registration number: NCT03140592.).

Traditional high-throughput drug screening in oncology routinely relies on two-dimensional (2D) cell models, which inadequately recapitulate the physiologic context of cancer. Three-dimensional (3D) cell models are thought to better mimic the complexity of in vivo tumors. Numerous methods to culture 3D organoids have been described, but most are nonhomogeneous and expensive, and hence impractical for high-throughput screening (HTS) purposes. Here we describe an HTS-compatible method that enables the consistent production of organoids in standard flat-bottom 384- and 1536-well plates by combining the use of a cell-repellent surface with a bioprinting technology incorporating magnetic force. We validated this homogeneous process by evaluating the effects of well-characterized anticancer agents against four patient-derived pancreatic cancer KRAS mutant-associated primary cells, including cancer-associated fibroblasts. This technology was tested for its compatibility with HTS automation by completing a cytotoxicity pilot screen of ~3300 approved drugs. To highlight the benefits of the 3D format, we performed this pilot screen in parallel in both the 2D and 3D assays. These data indicate that this technique can be readily applied to support large-scale drug screening relying on clinically relevant, ex vivo 3D tumor models directly harvested from patients, an important milestone toward personalized medicine.

Abstract Background The prognosis of patients with different gastrointestinal cancers varies widely. Despite advances in treatment strategies, such as extensive resections and the addition of new drugs to chemotherapy regimens, conventional treatment strategies have failed to improve survival for many tumours. Although promising, the clinical application of molecularly guided personalized treatment has proven to be challenging. This narrative review focuses on the personalization of cancer therapy using patient-derived three-dimensional ‘organoid’ models. Methods A PubMed search was conducted to identify relevant articles. An overview of the literature and published protocols is presented, and the implications of these models for patients with cancer, surgeons and oncologists are explained. Results Organoid culture methods have been established for healthy and diseased tissues from oesophagus, stomach, intestine, pancreas, bile duct and liver. Because organoids can be generated with high efficiency and speed from fine-needle aspirations, biopsies or resection specimens, they can serve as a personal cancer model. Personalized treatment could become a more standard practice by using these cell cultures for extensive molecular diagnosis and drug screening. Drug sensitivity assays can give a clinically actionable sensitivity profile of a patient's tumour. However, the predictive capability of organoid drug screening has not been evaluated in prospective clinical trials. Conclusion High-throughput drug screening on organoids, combined with next-generation sequencing, proteomic analysis and other state-of-the-art molecular diagnostic methods, can shape cancer treatment to become more effective with fewer side-effects.

Pancreatic ductal adenocarcinoma (PDAC) is the most lethal common malignancy, with little improvement in patient outcomes over the past decades. Recently, subtypes of pancreatic cancer with different prognoses have been elaborated; however, the inability to model these subtypes has precluded mechanistic investigation of their origins. Here, we present a xenotransplantation model of PDAC in which neoplasms originate from patient-derived organoids injected directly into murine pancreatic ducts. Our model enables distinction of the two main PDAC subtypes: intraepithelial neoplasms from this model progress in an indolent or invasive manner representing the classical or basal-like subtypes of PDAC, respectively. Parameters that influence PDAC subtype specification in this intraductal model include cell plasticity and hyperactivation of the RAS pathway. Finally, through intratumoral dissection and the direct manipulation of RAS gene dosage, we identify a suite of RAS-regulated secreted and membrane-bound proteins that may represent potential candidates for therapeutic intervention in patients with PDAC. SIGNIFICANCE: Accurate modeling of the molecular subtypes of pancreatic cancer is crucial to facilitate the generation of effective therapies. We report the development of an intraductal organoid transplantation model of pancreatic cancer that models the progressive switching of subtypes, and identify stochastic and RAS-driven mechanisms that determine subtype specification.See related commentary by Pickering and Morton, p. 1448.This article is highlighted in the In This Issue feature, p. 1426.

Abstract Pancreatic ductal adenocarcinoma (PDAC) is a lethal cancer with a low survival rate. Recently, new drugs that target KRASG12D, a common mutation in PDAC, have been developed. We studied one of these compounds, MRTX1133, and found it was specific and effective at low nanomolar concentrations in patient-derived organoid models and cell lines harboring KRASG12D mutations. Treatment with MRTX1133 upregulated the expression and phosphorylation of EGFR and HER2, indicating that inhibition of ERBB signaling may potentiate MRTX1133 antitumor activity. Indeed, the irreversible pan-ERBB inhibitor, afatinib, potently synergized with MRTX1133 in vitro, and cancer cells with acquired resistance to MRTX1133 in vitro remained sensitive to this combination therapy. Finally, the combination of MRTX1133 and afatinib led to tumor regression and longer survival in orthotopic PDAC mouse models. These results suggest that dual inhibition of ERBB and KRAS signaling may be synergistic and circumvent the rapid development of acquired resistance in patients with KRAS mutant pancreatic cancer. Significance: KRAS-mutant pancreatic cancer models, including KRAS inhibitor–resistant models, show exquisite sensitivity to combined pan-ERBB and KRAS targeting, which provides the rationale for testing this drug combination in clinical trials.

Despite recent advances in the treatment of cancer, pancreatic ductal adenocarcinoma (PDAC) still retains the worst survival rate of common malignancies. Late diagnosis and lack of curative therapeutic options are the most pressing clinical problems for this disease. Therefore, there is a need for patient models and biomarkers that can be applied in the clinic to identify the most effective therapy for a patient. Pancreatic ductal organoids are ex-vivo models of PDAC that can be established from very small biopsies, enabling the study of localized, advanced, and metastatic patients. Organoids models have been applied to pancreatic cancer research and offer a promising platform for precision medicine approaches.

Abstract Purpose: KRAS is mutated in the majority of pancreatic ductal adenocarcinoma. MAPK and PI3K-AKT are primary KRAS effector pathways, but combined MAPK and PI3K inhibition has not been demonstrated to be clinically effective to date. We explore the resistance mechanisms uniquely employed by malignant cells. Experimental Design: We evaluated the expression and activation of receptor tyrosine kinases in response to combined MEK and AKT inhibition in KPC mice and pancreatic ductal organoids. In addition, we sought to determine the therapeutic efficacy of targeting resistance pathways induced by MEK and AKT inhibition in order to identify malignant-specific vulnerabilities. Results: Combined MEK and AKT inhibition modestly extended the survival of KPC mice and increased Egfr and ErbB2 phosphorylation levels. Tumor organoids, but not their normal counterparts, exhibited elevated phosphorylation of ERBB2 and ERBB3 after MEK and AKT blockade. A pan-ERBB inhibitor synergized with MEK and AKT blockade in human PDA organoids, whereas this was not observed for the EGFR inhibitor erlotinib. Combined MEK and ERBB inhibitor treatment of human organoid orthotopic xenografts was sufficient to cause tumor regression in short-term intervention studies. Conclusions: Analyses of normal and tumor pancreatic organoids revealed the importance of ERBB activation during MEK and AKT blockade primarily in the malignant cultures. The lack of ERBB hyperactivation in normal organoids suggests a larger therapeutic index. In our models, pan-ERBB inhibition was synergistic with dual inhibition of MEK and AKT, and the combination of a pan-ERBB inhibitor with MEK antagonists showed the highest activity both in vitro and in vivo.

While great interest in health effects of natural product (NP) including dietary supplements and foods persists, promising preclinical NP research is not consistently translating into actionable clinical trial (CT) outcomes. Generally considered the gold standard for assessing safety and efficacy, CTs, especially phase III CTs, are costly and require rigorous planning to optimize the value of the information obtained. More effective bridging from NP research to CT was the goal of a September, 2018 transdisciplinary workshop. Participants emphasized that replicability and likelihood of successful translation depend on rigor in experimental design, interpretation, and reporting across the continuum of NP research. Discussions spanned good practices for NP characterization and quality control; use and interpretation of models (computational through in vivo) with strong clinical predictive validity; controls for experimental artefacts, especially for in vitro interrogation of bioactivity and mechanisms of action; rigorous assessment and interpretation of prior research; transparency in all reporting; and prioritization of research questions. Natural product clinical trials prioritized based on rigorous, convergent supporting data and current public health needs are most likely to be informative and ultimately affect public health. Thoughtful, coordinated implementation of these practices should enhance the knowledge gained from future NP research.

Recent technological advances have enabled 3D tissue culture models for fast and affordable HTS. We are no longer bound to 2D models for anti-cancer agent discovery, and it is clear that 3D tumor models provide more predictive data for translation of preclinical studies. In a previous study, we validated a microplate 3D spheroid-based technology for its compatibility with HTS automation. Small-scale screens using approved drugs have demonstrated that drug responses tend to differ between 2D and 3D cancer cell proliferation models. Here, we applied this 3D technology to the first ever large-scale screening effort completing HTS on over 150K molecules against primary pancreatic cancer cells. It is the first demonstration that a screening campaign of this magnitude using clinically relevant, ex-vivo 3D pancreatic tumor models established directly from biopsy, can be readily achieved in a fashion like traditional drug screen using 2D cell models. We identified four unique series of compounds with sub micromolar and even low nanomolar potency against a panel of patient derived pancreatic organoids. We also applied the 3D technology to test lead efficacy in autologous cancer associated fibroblasts and found a favorable profile for better efficacy in the cancer over wild type primary cells, an important milestone towards better leads. Importantly, the initial leads have been further validated in across multiple institutes with concordant outcomes. The work presented here represents the genesis of new small molecule leads found using 3D models of primary pancreas tumor cells.

Background Pancreatic cancer (PC) has a poor prognosis, and most patients present with either locally advanced or distant metastatic disease. Irreversible electroporation (IRE) is a non-thermal method of ablation used clinically in locally advanced PC, but most patients eventually develop distant recurrence. We have previously shown that IRE alone is capable of generating protective, neoantigen-specific immunity. Here, we aim to generate meaningful therapeutic immune effects by combining IRE with local (intratumoral) delivery of a CD40 agonistic antibody (CD40Ab). Methods KPC46 organoids were generated from a tumor-bearing male KrasLSL-G12D-p53LSL-R172H-Pdx-1-Cre (KPC) mouse. Orthotopic tumors were established in the pancreatic tail of B6/129 F1J mice via laparotomy. Mice were randomized to treatment with either sham laparotomy, IRE alone, CD40Ab alone, or IRE followed immediately by CD40Ab injection. Metastatic disease and immune infiltration in the liver were analyzed 14 days postprocedure using flow cytometry and multiplex immunofluorescence imaging with spatial analysis. Candidate neoantigens were identified by mutanome profiling of tumor tissue for ex vivo functional analyses. Results The combination of IRE+CD40 Ab improved median survival to greater than 35 days, significantly longer than IRE (21 days) or CD40Ab (24 days) alone (p<0.01). CD40Ab decreased metastatic disease burden, with less disease in the combination group than in the sham group or IRE alone. Immunohistochemistry of liver metastases revealed a more than twofold higher infiltration of CD8+T cells in the IRE+CD40 Ab group than in any other group (p<0.01). Multiplex immunofluorescence imaging revealed a 4–6 fold increase in the density of CD80+CD11c+ activated dendritic cells (p<0.05), which were spatially distributed throughout the tumor unlike the sham group, where they were restricted to the periphery. In contrast, CD4+FoxP3+ T-regulatory cells (p<0.05) and Ly6G+myeloid derived cells (p<0.01) were reduced and restricted to the tumor periphery in the IRE+CD40 Ab group. T-cells from the IRE+CD40 Ab group recognized significantly more peptides representing candidate neoantigens than did T-cells from the IRE or untreated control groups. Conclusions IRE can induce local tumor regression and neoantigen-specific immune responses. Addition of CD40Ab to IRE improved dendritic cell activation and neoantigen recognition, while generating a strong systemic antitumor T-cell response that inhibited metastatic disease progression.

Pancreatic cancer is an aggressive disease associated with a poor 5-year overall survival. Most patients are ineligible for surgery due to late diagnosis and are treated primarily with chemotherapy with very limited success. Pancreatic cancer is relatively insensitive to chemotherapy due to multiple factors, including reduced bioavailability of drugs to tumor cells. One strategy to improve drug efficacy with reduced toxicity is the development of antibody-drug conjugates (ADC), which have now been used successfully to treat both solid and liquid tumors. Here, we evaluate the efficacy of TR1801-ADC, a newly developed ADC composed of a MET antibody conjugated to the highly potent pyrrolobenzodiazepine toxin-linker, tesirine.We first evaluated MET expression and subcellular localization in pancreatic cancer cell lines, human tumors, and patient-derived xenografts (PDX). We then tested TR1801-ADC efficacy in vitro in pancreatic cancer cell lines. Preclinical evaluation of TR1801-ADC efficacy was conducted on PDXs selected on the basis of their MET expression level.We show that MET is highly expressed and located at the plasma membrane of pancreatic cancer cells. We found that TR1801-ADC induces a specific cytotoxicity in pancreatic cancer cell lines and a profound tumor growth inhibition, even in a gemcitabine-resistant tumor. We also noted synergism between TR1801-ADC and gemcitabine in vitro and an improved response to the combination in vivo.Together, these results suggest the promise of agents such as TR1801-ADC as a novel approach to the treatment of pancreatic cancer.

Pancreatic ductal adenocarcinoma (PDAC) has one of the poorest prognoses of all malignancies, with a 5-year survival rate <8%.1Hidalgo M. Pancreatic cancer.N Engl J Med. 2010; 362: 1605-1617Crossref PubMed Scopus (2195) Google Scholar,2Stathis A. Moore M.J. Advanced pancreatic carcinoma: current treatment and future challenges.Nat Rev Clin Oncol. 2010; 7: 163-172Crossref PubMed Scopus (640) Google Scholar Suspicious lesions are typically diagnosed via endoscopic ultrasound–guided fine-needle aspiration or endoscopic ultrasound–guided fine-needle biopsy (EUS-FNB).3Karadsheh Z. Al-Haddad M. Endoscopic ultrasound guided fine needle tissue acquisition: where we stand in 2013?.World J Gastroenterol. 2014; 20: 2176-2185Crossref PubMed Scopus (16) Google Scholar Fewer needle passes decreases the risk of postprocedure complications, including pancreatitis and hemorrhage, while allowing additional needle passes to be used for adjuvant tissue testing, such as organoid creation and DNA sequencing. We have previously shown PDAC organoids can be successfully created by means of EUS-FNB.4Tiriac H. Bucobo J.C. Tzimas D. et al.Successful creation of pancreatic cancer organoids by means of EUS-guided fine-needle biopsy sampling for personalized cancer treatment.Gastrointest Endosc. 2018; 87: 1474-1480Abstract Full Text Full Text PDF PubMed Scopus (79) Google Scholar In order to limit the number of EUS-FNB passes, the aim of this study was to measure success rates of PDAC organoid isolation (P0) and establishment (P5) in cell culture from a single FNB pass, compared with 2-pass FNB specimens. P0 was assessed by proliferation within 2 weeks of initial dissociation and culturing of the EUS-FNB specimen. P5 was determined by the ability of organoids to propagate through ≥5 passages in culture. This prospective trial (NCT03140592) was approved by the institutional review boards at Stony Brook University and Cold Spring Harbor Laboratory. Subject recruitment and study design were previously described.4Tiriac H. Bucobo J.C. Tzimas D. et al.Successful creation of pancreatic cancer organoids by means of EUS-guided fine-needle biopsy sampling for personalized cancer treatment.Gastrointest Endosc. 2018; 87: 1474-1480Abstract Full Text Full Text PDF PubMed Scopus (79) Google Scholar Informed consent was obtained in all patients. Either 1 or 2 additional EUS-FNB passes with a 22-gauge FNB needle were obtained from the tumor after preliminary diagnosis by on-site cytopathology. After January 2019, all subjects enrolled were restricted to a single pass for organoid creation. The FNB specimens were procured by the Gastrointestinal Clinical Resource Core at Stony Brook University Hospital and delivered to Cold Spring Harbor Laboratory for isolation and organoid establishment within 24 hours. Genotyping for hallmark pancreatic mutations (KRAS, TP53, CDKN2A, SMAD4) confirmed organoids were indeed PDAC.5Tiriac H. Belleau P. Engle D.D. et al.Organoid profiling identifies common responders to chemotherapy in pancreatic cancer.Cancer Discov. 2018; 8: 1112-1129Crossref PubMed Scopus (400) Google Scholar All adverse events were documented and reported to the study’s Safety Monitoring Committee. All data were combined with data from our previously published paper4Tiriac H. Bucobo J.C. Tzimas D. et al.Successful creation of pancreatic cancer organoids by means of EUS-guided fine-needle biopsy sampling for personalized cancer treatment.Gastrointest Endosc. 2018; 87: 1474-1480Abstract Full Text Full Text PDF PubMed Scopus (79) Google Scholar to analyze the organoid success rate of single-pass vs 2-pass specimens. Research biopsies from 67 of the 106 initially screened subjects were analyzed for organoid establishment. The excluded 39 subjects either refused consent or had a contraindication to additional research biopsies, or the final pathology of the mass was not PDAC. There were 25 subjects in the single-pass group and 42 subjects in the 2-pass group. Demographic characteristics were similar between the 2 cohorts (Table 1). The number of passes required for initial clinical diagnosis in single-pass subjects was greater than that required for 2-pass subjects (P = .0127). All other disease features were similar (Table 1).Table 1Patient Demographic of Single-Pass vs 2-Pass EUS-FNB PatientsSingle-Pass (n = 25)2-Pass (n = 42)P valueAge, y73 (53–92)68 (51–93).1819Sex.8008 Male14 (56)21 (50) Female11 (44)21 (50)Race.2819 Black/African American0 (0)3 (7) Asian/Pacific Islander0 (0)1 (2) White/Caucasian25 (100)38 (91)Ethnicity1.0000 Hispanic0 (0)1 (2) Non-Hispanic25 (100)41 (98)Tobacco.9754 Current4 (16)6 (14) Ex-smoker9 (36)16 (38) Never smoker12 (48)20 (48)Alcohol consumption.5902 Daily8 (32)7 (17) Weekly3 (12)7 (17) Monthly1 (4)5 (12) Socially/rarely3 (12)3 (7) Quit1 (4)3 (7) Never9 (36)17 (40)BMI, kg/m227.8 (20.3–41.6)27.5 (15–48.6).8075Diabetes mellitus, type 212 (48)15 (36).4404Chronic pancreatitis4 (16)2 (5).1858History of any previous cancer7 (28)8 (19).5455First-degree relative with PDAC.8781 Yes3 (12)4 (10) No21 (84)37 (88) Unknown1 (4)1 (2)Tumor characteristicsAnatomical location.7965 Head/neck17 (68)27 (64) Body/tail8 (32)15 (36)Largest dimension, cm2.8 (1.8–5.0)3.0 (1.5–4.9).1458Clinical passes for diagnosis3 (2–5)2 (1–4).0127Grossly visible core of specimen at time of sampling25 (100)42 (100)1.0000Concomitant ERCP after EUS-FNB11 (44)16 (38).7972CA19-9 at time of EUS-FNB, units/mL2454 (71.2–122,716)277 (1.7–10,830).0964NOTE. Values are median (range) or n (%).BMI, body mass index; CA, carbohydrate antigen; ERCP, endoscopic retrograde cholangiopancreatography; endoscopic ultrasound–guided fine-needle biopsy; PDAC, pancreatic ductal adenocarcinoma. Open table in a new tab NOTE. Values are median (range) or n (%). BMI, body mass index; CA, carbohydrate antigen; ERCP, endoscopic retrograde cholangiopancreatography; endoscopic ultrasound–guided fine-needle biopsy; PDAC, pancreatic ductal adenocarcinoma. A total of 88% (n = 22 of 25) of single-pass biopsies and 81% (n = 34 of 42) of 2-pass specimens yielded organoid isolates in culture (P0). Biopsy pass number had no effect on P0 success (P = .5175). Proliferation from P0 to ≥P5 was observed in 76% (n = 19 of 25) of all single-pass biopsies, compared with 60% (n = 25 of 42) of all 2-pass biopsies. There was no difference between pass number and successful organoid establishment at P5 (P = .3287). No deaths occurred as a result of the EUS-FNB procedure or related postprocedure complications. In the 2-pass cohort, 2 subjects developed acute pancreatitis after the EUS-FNB procedure. endoscopic retrograde cholangiopancreatography was simultaneously performed in these patients. Two other subjects in the 2-pass group experienced bleeding at the FNB site requiring hemostasis clips. No blood transfusions or hospitalizations were required. Organoids are an exciting development for translational research and precision medicine in pancreatic cancer. In this study, we achieved similar rates of P0 isolation of organoids and subsequent proliferation to P5 with single-pass EUS-FNB specimens as compared with 2-pass EUS-FNB specimens. There was a trend towards improved organoid isolation with the single-pass technique. This study was not powered to detect superiority of one technique over another. A possible explanation may be a learning curve effect with organoid creation in the laboratory, as the single-pass specimens were obtained further along within our study protocol. In addition, there appears to be consistent decline in success rates from P0 to P5 in both groups. This failure to reach P5 in all specimens (irrespective of single-pass vs 2-pass) is likely due to a high number of epithelial cells present, as this forces an arrest of proliferation because of the lack of growth factors in the organoid medium, thus enabling normal pancreatic epithelium to proliferate. In summary, FNB-derived organoids with 1 needle pass appears safe and feasible and would allow for subsequent needle passes to be used for additional forms of tumor tissue testing (e.g. DNA mutational analysis). Safe, simple, and effective organoid creation by means of EUS-FNB is essential for broadening the role of precision medicine in patients with pancreatic cancer.

The recent development of human organoids as patient-specific models of pancreatic ductal adenocarcinoma (PDA) has helped set the stage for a new era of personalized medicine. Organoids can be generated from a resected PDA tumor in as little as 2–4 weeks, and are amenable to therapeutic screening as well as genetic and biochemical perturbation. Moreover, because these models promote the propagation of the neoplastic PDA cells at the expense of the stromal cells, transcriptome and genome-wide sequencing of organoids offers an unprecedented view of the genetic and expression changes occurring in the neoplastic cells of individual tumors. Here, we describe methods to generate PDA organoid cultures from resected human tumor specimens. We also describe how to propagate, cryopreserve, and thaw human PDA organoid cultures.

Cancer-selective drug delivery is an important concept in improving treatment while minimizing off-site toxicities, and sigma-2 receptors, which are overexpressed in solid tumors, represent attractive pharmacologic targets. Select sigma-2 ligands have been shown to be rapidly internalized selectively into cancer cells while retaining the capacity to deliver small molecules as drug cargoes. We utilized the sigma-2-based drug delivery concept to convert Erastin, a clinically underperforming drug, into a potent pancreatic cancer therapeutic. The Erastin derivative des-methyl Erastin (dm-Erastin) was chemically linked to sigma-2 ligand SV119 to create SW V-49. Conjugation increased the killing capacity of dm-Erastin by nearly 35-fold in vitro and reduced the size of established tumors and doubled the median survival in syngeneic and patient-derived xenograft models when compared to non-targeted dm-Erastin. Mechanistic analyses demonstrated that cell death was associated with robust reactive oxygen species production and could be efficiently antagonized with antioxidants. Mass spectrometry was employed to demonstrate selective uptake into pancreatic cancer cells. Thus, targeted delivery of dm-Erastin via conjugation to the sigma-2 ligand SV119 produced efficient tumor control and prolonged animal survival with minimal off-target toxicities, and SW V-49 represents a promising new therapeutic with the potential to advance the fight against pancreatic cancer.

Pancreatic ductal adenocarcinoma (PDAC) is a lethal malignancy in need of new therapeutic options. Using unbiased analyses of super-enhancers (SEs) as sentinels of core genes involved in cell-specific function, here we uncover a druggable SE-mediated RNA-binding protein (RBP) cascade that supports PDAC growth through enhanced mRNA translation. This cascade is driven by a SE associated with the RBP heterogeneous nuclear ribonucleoprotein F, which stabilizes protein arginine methyltransferase 1 (PRMT1) to, in turn, control the translational mediator ubiquitin-associated protein 2-like. All three of these genes and the regulatory SE are essential for PDAC growth and coordinately regulated by the Myc oncogene. In line with this, modulation of the RBP network by PRMT1 inhibition reveals a unique vulnerability in Myc-high PDAC patient organoids and markedly reduces tumor growth in male mice. Our study highlights a functional link between epigenetic regulation and mRNA translation and identifies components that comprise unexpected therapeutic targets for PDAC.

This manuscript follows a single patient with pancreatic adenocarcinoma for a five year period, detailing the clinical record, pathology, the dynamic evolution of molecular and cellular alterations as well as the responses to treatments with chemotherapies, targeted therapies and immunotherapies. DNA and RNA samples from biopsies and blood identified a dynamic set of changes in allelic imbalances and copy number variations in response to therapies. Organoid cultures established from biopsies over time were employed for extensive drug testing to determine if this approach was feasible for treatments. When an unusual drug response was detected, an extensive RNA sequencing analysis was employed to establish novel mechanisms of action of this drug. Organoid cell cultures were employed to identify possible antigens associated with the tumor and the patient's T-cells were expanded against one of these antigens. Similar and identical T-cell receptor sequences were observed in the initial biopsy and the expanded T-cell population. Immunotherapy treatment failed to shrink the tumor, which had undergone an epithelial to mesenchymal transition prior to therapy. A warm autopsy of the metastatic lung tumor permitted an extensive analysis of tumor heterogeneity over five years of treatment and surgery. This detailed analysis of the clinical descriptions, imaging, pathology, molecular and cellular evolution of the tumors, treatments, and responses to chemotherapy, targeted therapies, and immunotherapies, as well as attempts at the development of personalized medical treatments for a single patient should provide a valuable guide to future directions in cancer treatment.

Abstract Cytotoxic T lymphocyte (CTL)-based cancer immunotherapies have shown great promise for inducing clinical regressions by targeting tumor-associated antigens (TAA). To expand the TAA landscape of pancreatic ductal adenocarcinoma (PDAC), we performed tandem mass spectrometry analysis of HLA class I-bound peptides from 35 PDAC patient tumors. This identified a shared HLA-A*0101 restricted peptide derived from co-transcriptional activator Vestigial-like 1 (VGLL1) as a putative TAA demonstrating overexpression in multiple tumor types and low or absent expression in essential normal tissues. Here we show that VGLL1-specific CTLs expanded from the blood of a PDAC patient could recognize and kill in an antigen-specific manner a majority of HLA-A*0101 allogeneic tumor cell lines derived not only from PDAC, but also bladder, ovarian, gastric, lung, and basal-like breast cancers. Gene expression profiling reveals VGLL1 as a member of a unique group of cancer-placenta antigens (CPA) that may constitute immunotherapeutic targets for patients with multiple cancer types.

Perineural invasion (PNI) is the phenomenon whereby cancer cells invade the space surrounding nerves. PNI occurs frequently in epithelial malignancies, but is especially characteristic of pancreatic ductal adenocarcinoma (PDAC). The presence of PNI portends an increased incidence of local recurrence, metastasis and poorer overall survival. While interactions between tumor cells and nerves have been investigated, the etiology and initiating cues for PNI development is not well understood. Here, we used digital spatial profiling to reveal changes in the transcriptome and to allow for a functional analysis of neural-supportive cell types present within the tumor-nerve microenvironment of PDAC during PNI. We found that hypertrophic tumor-associated nerves within PDAC express transcriptomic signals of nerve damage including programmed cell death, Schwann cell proliferation signaling pathways, as well as macrophage clearance of apoptotic cell debris by phagocytosis. Moreover, we identified that neural hypertrophic regions have increased local neuroglial cell proliferation which was tracked using EdU tumor labeling in KPC mice, as well as frequent TUNEL positivity, suggestive of a high turnover rate. Functional calcium imaging studies using human PDAC organotypic slices confirmed nerve bundles had neuronal activity, as well as contained NGFR+ cells with high sustained calcium levels, which are indicative of apoptosis. This study reveals a common gene expression pattern that characterizes solid tumor-induced damage to local nerves. These data provide new insights into the pathobiology of the tumor-nerve microenvironment during PDAC as well as other gastrointestinal cancers.

Abstract Engrailed-1 (EN1) is a critical homeodomain transcription factor (TF) required for neuronal survival, and EN1 expression has been shown to promote aggressive forms of triple negative breast cancer. Here, we report that EN1 is aberrantly expressed in a subset of pancreatic ductal adenocarcinoma (PDA) patients with poor outcomes. EN1 predominantly repressed its target genes through direct binding to gene enhancers and promoters, implicating a role in the acquisition of mesenchymal cell properties. Gain- and loss-of-function experiments demonstrated that EN1 promoted PDA transformation and metastasis in vitro and in vivo. Our findings nominate the targeting of EN1 and downstream pathways in aggressive PDA. Citation Format: Jihao Xu, Jae-Seok Roe, EunJung Lee, Claudia Tonelli, Tim Somervile, Melissa Yao, Joseph Milazzo, Herve Tiriac, Anna Kolarzyk, Esak Lee, Jeam Grem, Audrey Lazenby, James Grunkemeyer, Michael Hollingsworth, Paul Grandgenett, Alexander Borowsky, Youngkyu Park, Christopher Vakoc, David Tuveson, Chang-il Hwang. Engrailed-1 promotes pancreatic cancer metastasis [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr C114.

Abstract Pancreatic ductal adenocarcinoma (PDA) is a lethal malignancy with a low survival rate. A lack of durable responses to chemotherapy renders its treatment particularly challenging and largely contributes to the devastating prognosis. Gemcitabine, a pyrimidine anti-metabolite, is a cornerstone in PDA therapy, but resistance remains a major hurdle in clinical care. Multiple mechanisms of chemoresistance have been attributed to rewired metabolic pathways in PDA cells. Accordingly, we hypothesized that altered metabolism in gemcitabine resistance represents a therapeutic vulnerability that can be targeted to improve response to treatment. To investigate metabolic vulnerabilities in gemcitabine resistance, we generated gemcitabine resistant murine PDA cell lines and assembled patient-derived gemcitabine high versus low responder organoids. Transcriptomic profiling revealed a downregulation of the mevalonate biosynthesis pathway and its rate-limiting enzyme, HMG-CoA reductase, upon the acquisition of gemcitabine resistance. Upregulation of this pathway has been proposed as a primary resistance mechanism to statins, HMG-CoA reductase inhibitors that are frequently prescribed to treat patients with hyperlipidemia. Accordingly, we postulated that statins would be more potent in gemcitabine resistant PDA cells than in their sensitive counterparts. Indeed, resistant cells were exquisitely susceptible to inhibition of the mevalonate pathway, an observation consistent across multiple clinically available statins. Downstream rescue experiments suggested that the main impact of blocking the mevalonate biosynthesis pathway is through lowered levels of geranylgeranyl pyrophosphate and reduced protein geranylation. To validate our findings in vivo, we implanted gemcitabine resistant murine PDA cells into syngeneic mice that were fed with a modified diet precluding geranylgeraniol. Here, the treatment combination gemcitabine and pitavastatin inhibited tumor growth of resistant allografts. Collectively, these data suggest that targeting the HMG-CoA reductase is a metabolic vulnerability that is gained in PDA cells upon the acquisition of gemcitabine resistance. The combination therapy gemcitabine and pitavastatin, two widely used compounds in patients, has potential to translate into a clinical benefit and improve survival in this deadly disease. Citation Format: Alica K. Beutel, Sabrina Calderon, Ethan Nghiem, Rima Singh, Cecily Anaraki, Kevin Gulay, Herve Tiriac, Alexander Kleger, Thomas Seufferlein, Alexander Muir, Cholsoon Jang, Dennis Juarez, David Fruman, Christopher Halbrook. Targeting the mevalonate biosynthesis pathway in gemcitabine resistant pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr A056.

Abstract Introduction: Pancreatic cancer is characterized by desmoplastic, fibroinflammatory stroma. The crosstalk between cancer cells and their surrounding tumor microenvironment (TME) promotes disease progression, metastasis, and chemoresistance. We identified MICAL2 as a super-enhancer-associated gene in pancreatic cancer. MICAL2 (molecule interacting with Cas-L) proteins are flavin monooxygenases that promote actin depolymerization and indirectly regulate SRF transcription. In other work, we have found that MICAL2 promotes pancreatic cancer growth and progression. This study evaluated how MICAL2 pancreatic cancer cell expression modulates the PDAC tumor microenvironment. Methods: RNA-Seq analysis performed on human pancreas cancer cells (AsPC-1) before and after MICAL2 KD revealed differential regulation of IL-1α. We validated the expression of IL-1α in multiple human and mouse pancreas cancer cell lines by q-PCR. We next exposed human (h) and mouse (m) PSCs to conditioned media (CM) from cancer cells before and after MICAL2 KD and checked the expression of a-SMA, fibronectin, and Col1A and IL-6 genes by qPCR. KrasG12D/+; Trp53R172H/+; Pdx1-cre (KPC) cells with and without MICAL2 were orthotopically injected to assess the in vivo tumor growth and metastasis. Sc-RNA seq and Immunophenotyping were performed on Shcontrol (ShCNT) and MICAL2 (M2KD) KD tumors. CD8+ T cell depletion was done using an antibody-mediated approach. The adoptive transfer of CD8+ T cells extracted from MICAL2 KD tumors was done by tail vein injection. Results: MICAL2 KD resulted in the downregulation of the IL-1α gene in both human and mouse pancreas cancer cell lines (50% reduction, p&amp;lt;0.05). Human and mouse pancreatic stellate cells (hPSCs and mPSCs) co-cultured with cancer cells CM showed significant downregulation of a-SMA, fibronectin, Col1A, and IL-6 upon MICAL2 KD as compared to hPSCs and mPSCs co-cultured with ShCNT cells. Orthotopic injections of KPC MICAL2 KD cells led to decreased tumor growth as compared to ShCNT (0.26 gm vs. 1 gm, p = 0.008). Immunofluorescence (IF) revealed less α-SMA, PDGF-α, and IL-6 expression and reduced deposition of collagen and fibronectin in MICAL2 KD tumors. Single-cell RNA seq and flow cytometry studies of tumors harvested from both groups showed significantly increased infiltration of activated cytotoxic CD8+ T cells in MICAL2 KD tumors which was further confirmed by IF. Antibody-mediated depletion of CD8+ T cells in MICAL2 KD tumors abrogated their reduced tumor growth in both immune-hot and immune-cold KPC cell lines. Adoptive transfer of CD8+ T cells extracted from M2KD tumors significantly reduced ShCNT flank tumor growth. Conclusion: These data reveal that MICAL2 expression mediates tumor-stromal crosstalk through IL1A and creates an immunosuppressive environment in PDAC and suggests MICAL2 may be an attractive immunomodulatory target for pancreatic cancer therapy. Ongoing work is focused on dissecting the role of MICAL2 in priming the metastatic niche through the remodeling of the TME. Citation Format: Bharti Garg, EvanGeline Mose, Edgar Esparza, Jay Patel, Sarah Sass, Alexei Martsinkovskiy, Dawn Jacquish, Herve Tiriac, Andrew M. Lowy. Silencing MICAL2 expression in pancreatic cancer cells reduces IL-1A expression and inhibits tumor growth through a CD8+ T cell dependent mechanism [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr A039.

Abstract Background: Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive cancer with dismal patient outcomes. Acquired resistance to chemotherapeutics is a major barrier to successful pancreatic cancer treatment. MRTX-1133 is a potent, selective KRAS G12D inhibitor that is in early-phase clinical trials. While initially effective, clinical experience with KRAS G12C inhibitors has shown tumors rapidly acquire therapeutic resistance. The tumor microenvironment (TME) plays a pivotal role in resistance development by activating prosurvival pathways, promoting epithelial-mesenchymal transition (EMT) and stemness, and inhibiting apoptosis. In this study, we sought to understand changes in the PDAC TME associated with acquired resistance to KRAS G12D inhibition. Methods: In order to investigate resistance to KRAS G12D inhibition in PDAC, we developed various mouse and human MRTX-1133 resistant (MRTXR) cell models (FC1199, FC1242, FC1245, and SUIT2). Intriguingly, these models also displayed resistance to several pan-RAS(ON) inhibitors. We utilized flow cytometry analysis to investigate the dynamic changes occurring in the TME following resistance to MRTX-1133, and we employed cytokine array and RNA-seq analyses to elucidate the impact of cancer cells on gene and protein expression of TME cells. Results: A comparative analysis between parental PDAC cells and MRTXR tumors revealed significant alterations within the TME. We found a significant decrease (p=0.013, p=0.045, respectively) in the number of inactivated and naïve CD8 T cells (CD8+/CD69+ and CD44-/CD62L+ cells) in MRTXR tumors. We also observed an upregulation of CXCL1, CCL20, and CXCL2 secretion in MRTXR cells compared to parental cells. Conclusions: Pancreatic cancer cells with acquired resistance to KRAS inhibitors modulate their tumor microenvironment uniquely. Ongoing studies aim to identify the critical pathways responsible for these alterations and to develop alternative treatment strategies for KRAS therapy-resistant tumors. Citation Format: Kevin Christian Montecillo Gulay, Jay Patel, Isabella Ng, Tatiana Hurtado de Mendoza, Herve Tiriac, Andrew Lowy. Acquired resistance to KRAS inhibition modulates the pancreatic cancer tumor microenvironment [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr B096.

Cancer selective apoptosis remains a therapeutic challenge and off-target toxicity has limited enthusiasm for this target clinically. Sigma-2 ligands (S2) have been shown to enhance the cancer selectivity of small molecule drug candidates by improving internalization. Here, we report the synthesis of a novel drug conjugate, which was created by linking a clinically underperforming SMAC mimetic (second mitochondria-derived activator of caspases; LCL161), an inhibitor (antagonist) of inhibitor of apoptosis proteins (IAPinh) with the sigma-2 ligand SW43, resulting in the new chemical entity S2/IAPinh. Drug potency was assessed via cell viability assays across several pancreatic and ovarian cancer cell lines in comparison with the individual components (S2 and IAPinh) as well as their equimolar mixtures (S2 + IAPinh) both in vitro and in preclinical models of pancreatic and ovarian cancer. Mechanistic studies of S2/IAPinh-mediated cell death were investigated in vitro and in vivo using syngeneic and xenograft mouse models of murine pancreatic and human ovarian cancer, respectively. S2/IAPinh demonstrated markedly improved pharmacological activity in cancer cell lines and primary organoid cultures when compared to the controls. In vivo testing demonstrated a marked reduction in tumor growth rates and increased survival rates when compared to the respective control groups. The predicted mechanism of action of S2/IAPinh was confirmed through assessment of apoptosis pathways and demonstrated strong target degradation (cellular inhibitor of apoptosis proteins-1 [cIAP-1]) and activation of caspases 3 and 8. Taken together, S2/IAPinh demonstrated efficacy in models of pancreatic and ovarian cancer, two challenging malignancies in need of novel treatment concepts. Our data support an in-depth investigation into utilizing S2/IAPinh for the treatment of cancer.

Abstract Background: Pancreatic ductal adenocarcinoma (PDAC) remains one of the most lethal malignancies, largely due to acquired chemotherapy resistance. MRTX-1133, a promising KRAS-G12D inhibitor, has demonstrated initial efficacy; however, resistance analogous to that seen with KRAS-G12C inhibitors is an emerging challenge. The tumor microenvironment (TME) is increasingly recognized as a contributor to resistance, often fostering tumor survival and immune evasion. Methods: To elucidate the resistance mechanisms to KRAS-G12D inhibition, we established resistant mouse and human PDAC cell lines derived from mouse and human models. These models were analyzed using flow cytometry and single cell RNA sequencing to define TME dynamics as resistant is acquired and after is has been established. We also analyzed cytokines released by resistant tumor cells using protein arrays and RNA sequencing. Results: Our investigation revealed significant TME alterations associated with acquired resistance. Notably, there was a marked increase in the population CD4+ Tregs and neutrophil while activated CD8+ T cells are decreased in the resistant tumors. Concurrently, an increased secretion of chemokines such as CXCL1 and CXCL2 was observed in resistant tumor cells relative to their parental counterparts. Conclusions: The adaptation of PDAC to circumvent KRAS inhibition involves a distinct reprogramming of the TME, attenuating immune surveillance and potentially facilitating tumor progression. Current efforts are directed towards delineating the key pathways implicated in these TME modifications to pioneer new therapeutic approaches for managing KRAS inhibitor resistant PDAC. Citation Format: Herve Tiriac. Resistance to RAS inhibition promotes remodeling of the immunosuppressive microenvironment of pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1948.

Abstract Concomitant mutations in KRAS and GNAS have been linked to mucinous histology in gastrointestinal neoplasms of the appendix, colon, and pancreas (IPMN). Upon progression, these tumors are characterized by metastasis which favors the peritoneal surface, resulting in mucinous carcinomatosis peritonei (MCP). Recently we have described a novel technique which allows for long term culture and drug intervention of human MCP tumors ex-vivo. With evidence of durable clinical benefit of CDK4-6 inhibition in a single patient with chemo refractory MCP of appendiceal origin, we sought to further investigate anti-tumor responses using CDK4-6 inhibition in ex-vivo tumor slices, in order to identify candidates for a personalized clinical therapy trial. Here, in a comparison of ex-vivo patient tumor slices from 18 individual donors, treatment using CDK4-6 inhibitors revealed a significant reduction in cancer cell specific proliferation in mucinous GNAS-mut tumors compared to non-mucinous cancers. Anti-tumor responses of CDK4-6 were determined to be tumor-cell intrinsic, as CDK4-6 inhibition blocked proliferation of stromal cells in the TME independently of patient tumor mutational and mucin status. Based on these finding a personalized clinical trial was conducted where we report that 13 of 16 patients (81%) enrolled with MCP treated with palbociclib had at least a 10% decrease in CEA, as compared to historical chemotherapy responses rates reported from 14-30%. These results indicate that CDK4/6 inhibition is a novel and efficacious treatment for patients with MCP. Citation Format: Jonathan Weitz, Daisuke Nishizaki, Jay Patel, Isabella Ng, Siming Sun, Dana Ramms, Jingjing Zou, Joel Baumgartner, Kaitlyn Kelly, Hitendra Patel, Rebekah White, Jula Veerapong, Peter Vu, Silvio Gutkind, Herve Tiriac, Shumei Kato, Andrew Lowy. An ex-vivo organotypic culture platform of mucinous carcinomatosis peritonei identifies CDK4-6 inhibition as a novel treatment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6777.

Organotypic tissue slices prepared from patient tumors are a semi-intact ex vivo preparation that recapitulates many aspects of the tumor microenvironment (TME). While connections to the vasculature and nervous system are severed, the integral functional elements of the tumor remain intact for many days during the slice culture. During this window of time, the slice platforms offer a suite of molecular, biomechanical and functional tools to investigate PDAC biology. In this review, we first briefly discuss the development of pancreatic tissue slices as a model system. Next, we touch upon using slices as an orthogonal approach to study the TME as compared to other established 3D models, such as organoids. Distinct from most other models, the pancreatic slices contain autologous immune and other stromal cells. Taking advantage of the existing immune cells within the slices, we will discuss the breakthrough studies which investigate the immune compartment in the pancreas slices. These studies will provide an important framework for future investigations seeking to exploit or reprogram the TME for cancer therapy.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Epithelial neoplasms of the appendix are difficult to study preclinically given their low incidence, frequent mucinous histology, and absence of a comparable organ in mice for disease modeling. Although surgery is an effective treatment for localized disease, metastatic disease has a poor prognosis as existing therapeutics borrowed from colorectal cancer have limited efficacy. Recent studies reveal that appendiceal cancer has a genomic landscape distinct from colorectal cancer and thus preclinical models to study this disease are a significant unmet need.We adopted an ex vivo slice model that permits the study of cellular interactions within the tumor microenvironment. Mucinous carcinomatosis peritonei specimens obtained at surgical resection were cutoff using a vibratome to make 150-μm slices cultured in media.Slice cultures were viable and maintained their cellular composition regarding the proportion of epithelial, immune cells, and fibroblasts over 7 days. Within donor specimens, we identified a prominent and diverse immune landscape and calcium imaging confirmed that immune cells were functional for 7 days. Given the diverse immune landscape, we treated slices with TAK981, an inhibitor of SUMOylation with known immunomodulatory functions, in early-phase clinical trials. In 5 of 6 donor samples, TAK981-treated slices cultures had reduced viability, and regulatory T cells (Treg). These data were consistent with TAK981 activity in purified Tregs using an in vitro murine model.This study demonstrates an approach to study appendiceal cancer therapeutics and pathobiology in a preclinical setting. These methods may be broadly applicable to the study of other malignancies.

Increasingly, patient models of disease are being utilized to facilitate precision medicine approaches through molecular characterization or direct chemotherapeutic testing. Organoids, 3-dimensional (3D) cultures of neoplastic cells derived from primary tumor specimens, represent an ideal platform for these types of studies because benchtop protocols previously developed for 2-dimensional cell lines can be adapted for use. These protocols include directly testing the survival of these organoid cultures when exposed to clinically relevant chemotherapeutic agents, a process we have called pharmacotyping. In this protocol, established tumor-derived organoid cultures are dissociated into single cells, plated in a 3D gel matrix, and exposed to pharmacologic agents. While our protocol has been developed for use with patient-derived pancreatic ductal adenocarcinoma organoids, with minor modifications to the dissociation and medium conditions, this protocol could be adapted for use with a wide range of organoid cultures. We further describe our standard ATP-based assay to determine cellular survival. This protocol can be scaled for use in high-throughput assays.

The use of patient-derived organoids (PDOs) to characterize therapeutic sensitivity and resistance is a promising precision medicine approach, and its potential to inform clinical decisions is now being tested in several large multiinstitutional clinical trials. PDOs are cultivated in the extracellular matrix from basement membrane extracts (BMEs) that are most commonly acquired commercially. Each clinical site utilizes distinct BME lots and may be restricted due to the availability of commercial BME sources. However, the effect of different sources of BMEs on organoid drug response is unknown. Here, we tested the effect of BME source on proliferation, drug response, and gene expression in mouse and human pancreatic ductal adenocarcinoma (PDA) organoids. Both human and mouse organoids displayed increased proliferation in Matrigel compared with Cultrex and UltiMatrix. However, we observed no substantial effect on drug response when organoids were cultured in Matrigel, Cultrex, or UltiMatrix. We also did not observe major shifts in gene expression across the different BME sources, and PDOs maintained their classical or basal-like designation. Overall, we found that the BME source (Matrigel, Cultrex, UltiMatrix) does not shift PDO dose-response curves or drug testing results, indicating that PDO pharmacotyping is a robust approach for precision medicine.

Abstract Engrailed‐1 (EN1) is a critical homeodomain transcription factor (TF) required for neuronal survival, and EN1 expression has been shown to promote aggressive forms of triple negative breast cancer. Here, it is reported that EN1 is aberrantly expressed in a subset of pancreatic ductal adenocarcinoma (PDA) patients with poor outcomes. EN1 predominantly repressed its target genes through direct binding to gene enhancers and promoters, implicating roles in the activation of MAPK pathways and the acquisition of mesenchymal cell properties. Gain‐ and loss‐of‐function experiments demonstrated that EN1 promoted PDA transformation and metastasis in vitro and in vivo. The findings nominate the targeting of EN1 and downstream pathways in aggressive PDA.

Abstract Pancreatic cancer is the most lethal common solid malignancy. Systemic therapies are often ineffective and predictive biomarkers to guide treatment are urgently needed. We generated a pancreatic cancer patient-derived organoid (PDO) library that recapitulates the mutational spectrum and transcriptional subtypes of primary pancreatic cancer. New driver oncogenes were nominated and transcriptomic analyses revealed unique clusters. PDOs exhibited heterogeneous responses to standard-of-care chemotherapeutics and investigational agents. In a case study manner, we find that PDO therapeutic profiles paralleled patient outcomes and that PDOs enable longitudinal assessment of chemosensitivity and evaluation of synchronous metastases. We derived organoid-based gene expression signatures of chemosensitivity that predicted improved responses for many patients to chemotherapy in both the adjuvant and advanced disease settings. Finally, we nominated alternative treatment strategies for chemorefractory PDOs using targeted agent therapeutic profiling. We propose that combined molecular and therapeutic profiling of PDOs may predict clinical response and enable prospective therapeutic selection. Citation Format: Herve Tiriac, Pascal Belleau, Dannielle Engle, Dennis Plenker, Astrid Deschenes, Tim Somerville, Fieke Froeling, Richard Moffitt, Jennifer Knox, Alexander Krasnitz, Steven Gallinger, David Tuveson. Organoid profiling identifies common responders to chemotherapy in pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2019 Sept 6-9; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2019;79(24 Suppl):Abstract nr C57.

The vast majority of patients with pancreatic ductal adenocarcinoma (PDA) are not candidates for curative resection. Overall survival rates in this group of patients remain exceptionally low. Pancreatic cancer organoids are tumor models of individualized human PDA that can be rapidly generated from surgically resected tumors. Organoids simulate the full spectrum of a patient’s tumor, including stromal elements believed to be responsible for chemotherapy resistance. Hence, they can be used for testing personalized treatment strategies. For surgically unresectable patients, creation of human PDA organoids at the time of tissue diagnosis could allow this group of patients to benefit from precision medicine with personalized treatment.

Perineural invasion (PNI) is the phenomenon whereby cancer cells invade the space surrounding nerves. PNI occurs frequently in epithelial malignancies, but is especially characteristic of pancreatic ductal adenocarcinoma (PDAC). The presence of PNI portends an increased incidence of local recurrence, metastasis and poorer overall survival. While interactions between tumor cells and nerves have been investigated, the etiology and initiating cues for PNI development is not well understood. Here, we used digital spatial profiling to reveal changes in the transcriptome and to allow for a functional analysis of neural-supportive cell types present within the tumor-nerve microenvironment of PDAC during PNI. We found that hypertrophic tumor-associated nerves within PDAC express transcriptomic signals of nerve damage including programmed cell death, Schwann cell proliferation signaling pathways, as well as macrophage clearance of apoptotic cell debris by phagocytosis. Moreover, we identified that neural hypertrophic regions have increased local neuroglial cell proliferation which was tracked using EdU tumor labeling in KPC mice. This study reveals a common gene expression pattern that characterizes solid tumor-induced damage to local nerves. These data provide new insights into the pathobiology of the tumor-nerve microenvironment during PDAC as well as other gastrointestinal cancers.

&lt;p&gt;Dose dependent anti-proliferative effect of TR1801-ADC&lt;/p&gt;

&lt;p&gt;MET expression in pancreatic cancer&lt;/p&gt;

&lt;div&gt;AbstractPurpose:&lt;p&gt;Pancreatic cancer is an aggressive disease associated with a poor 5-year overall survival. Most patients are ineligible for surgery due to late diagnosis and are treated primarily with chemotherapy with very limited success. Pancreatic cancer is relatively insensitive to chemotherapy due to multiple factors, including reduced bioavailability of drugs to tumor cells. One strategy to improve drug efficacy with reduced toxicity is the development of antibody–drug conjugates (ADC), which have now been used successfully to treat both solid and liquid tumors. Here, we evaluate the efficacy of TR1801-ADC, a newly developed ADC composed of a MET antibody conjugated to the highly potent pyrrolobenzodiazepine toxin-linker, tesirine.&lt;/p&gt;Experimental Design:&lt;p&gt;We first evaluated MET expression and subcellular localization in pancreatic cancer cell lines, human tumors, and patient-derived xenografts (PDX). We then tested TR1801-ADC efficacy &lt;i&gt;in vitro&lt;/i&gt; in pancreatic cancer cell lines. Preclinical evaluation of TR1801-ADC efficacy was conducted on PDXs selected on the basis of their MET expression level.&lt;/p&gt;Results:&lt;p&gt;We show that MET is highly expressed and located at the plasma membrane of pancreatic cancer cells. We found that TR1801-ADC induces a specific cytotoxicity in pancreatic cancer cell lines and a profound tumor growth inhibition, even in a gemcitabine-resistant tumor. We also noted synergism between TR1801-ADC and gemcitabine &lt;i&gt;in vitro&lt;/i&gt; and an improved response to the combination &lt;i&gt;in vivo&lt;/i&gt;.&lt;/p&gt;Conclusions:&lt;p&gt;Together, these results suggest the promise of agents such as TR1801-ADC as a novel approach to the treatment of pancreatic cancer.&lt;/p&gt;&lt;/div&gt;

&lt;p&gt;Post-treatment tumor volumes of PDX1342 grafted tumors&lt;/p&gt;

&lt;p&gt;Dose dependent anti-proliferative effect of TR1801-ADC&lt;/p&gt;

&lt;p&gt;Post-treatment tumor volumes of PDX1342 grafted tumors&lt;/p&gt;

&lt;p&gt;Post-treatment tumor volumes of PDX1342 grafted tumors treated with TR1801-ADC and gemcitabine&lt;/p&gt;

&lt;p&gt;Post-treatment tumor volumes of PDX1334 grafted tumors&lt;/p&gt;

&lt;p&gt;MET expression in pancreatic cancer&lt;/p&gt;

&lt;p&gt;Post-treatment tumor volumes of PDX1342 grafted tumors treated with TR1801-ADC and gemcitabine&lt;/p&gt;

&lt;div&gt;AbstractPurpose:&lt;p&gt;Pancreatic cancer is an aggressive disease associated with a poor 5-year overall survival. Most patients are ineligible for surgery due to late diagnosis and are treated primarily with chemotherapy with very limited success. Pancreatic cancer is relatively insensitive to chemotherapy due to multiple factors, including reduced bioavailability of drugs to tumor cells. One strategy to improve drug efficacy with reduced toxicity is the development of antibody–drug conjugates (ADC), which have now been used successfully to treat both solid and liquid tumors. Here, we evaluate the efficacy of TR1801-ADC, a newly developed ADC composed of a MET antibody conjugated to the highly potent pyrrolobenzodiazepine toxin-linker, tesirine.&lt;/p&gt;Experimental Design:&lt;p&gt;We first evaluated MET expression and subcellular localization in pancreatic cancer cell lines, human tumors, and patient-derived xenografts (PDX). We then tested TR1801-ADC efficacy &lt;i&gt;in vitro&lt;/i&gt; in pancreatic cancer cell lines. Preclinical evaluation of TR1801-ADC efficacy was conducted on PDXs selected on the basis of their MET expression level.&lt;/p&gt;Results:&lt;p&gt;We show that MET is highly expressed and located at the plasma membrane of pancreatic cancer cells. We found that TR1801-ADC induces a specific cytotoxicity in pancreatic cancer cell lines and a profound tumor growth inhibition, even in a gemcitabine-resistant tumor. We also noted synergism between TR1801-ADC and gemcitabine &lt;i&gt;in vitro&lt;/i&gt; and an improved response to the combination &lt;i&gt;in vivo&lt;/i&gt;.&lt;/p&gt;Conclusions:&lt;p&gt;Together, these results suggest the promise of agents such as TR1801-ADC as a novel approach to the treatment of pancreatic cancer.&lt;/p&gt;&lt;/div&gt;

&lt;p&gt;Post-treatment tumor volumes of PDX1334 grafted tumors&lt;/p&gt;

&lt;p&gt;Supplementary Figures 1-3&lt;/p&gt;

&lt;p&gt;Supplementary Figures 1-3&lt;/p&gt;

Supplementary Figure from An &lt;i&gt;Ex Vivo&lt;/i&gt; Organotypic Culture Platform for Functional Interrogation of Human Appendiceal Cancer Reveals a Prominent and Heterogenous Immunological Landscape

Supplementary Table from An &lt;i&gt;Ex Vivo&lt;/i&gt; Organotypic Culture Platform for Functional Interrogation of Human Appendiceal Cancer Reveals a Prominent and Heterogenous Immunological Landscape

Supplementary Data from An &lt;i&gt;Ex Vivo&lt;/i&gt; Organotypic Culture Platform for Functional Interrogation of Human Appendiceal Cancer Reveals a Prominent and Heterogenous Immunological Landscape

Supplementary Data from An &lt;i&gt;Ex Vivo&lt;/i&gt; Organotypic Culture Platform for Functional Interrogation of Human Appendiceal Cancer Reveals a Prominent and Heterogenous Immunological Landscape

Supplementary Figure from An &lt;i&gt;Ex Vivo&lt;/i&gt; Organotypic Culture Platform for Functional Interrogation of Human Appendiceal Cancer Reveals a Prominent and Heterogenous Immunological Landscape

Supplementary Figure from An &lt;i&gt;Ex Vivo&lt;/i&gt; Organotypic Culture Platform for Functional Interrogation of Human Appendiceal Cancer Reveals a Prominent and Heterogenous Immunological Landscape

Supplementary Figure from An &lt;i&gt;Ex Vivo&lt;/i&gt; Organotypic Culture Platform for Functional Interrogation of Human Appendiceal Cancer Reveals a Prominent and Heterogenous Immunological Landscape

Supplementary Figure from An &lt;i&gt;Ex Vivo&lt;/i&gt; Organotypic Culture Platform for Functional Interrogation of Human Appendiceal Cancer Reveals a Prominent and Heterogenous Immunological Landscape

Supplementary Figure from An &lt;i&gt;Ex Vivo&lt;/i&gt; Organotypic Culture Platform for Functional Interrogation of Human Appendiceal Cancer Reveals a Prominent and Heterogenous Immunological Landscape

&lt;div&gt;AbstractPurpose:&lt;p&gt;&lt;i&gt;KRAS&lt;/i&gt; is mutated in the majority of pancreatic ductal adenocarcinoma. MAPK and PI3K-AKT are primary KRAS effector pathways, but combined MAPK and PI3K inhibition has not been demonstrated to be clinically effective to date. We explore the resistance mechanisms uniquely employed by malignant cells.&lt;/p&gt;Experimental Design:&lt;p&gt;We evaluated the expression and activation of receptor tyrosine kinases in response to combined MEK and AKT inhibition in KPC mice and pancreatic ductal organoids. In addition, we sought to determine the therapeutic efficacy of targeting resistance pathways induced by MEK and AKT inhibition in order to identify malignant-specific vulnerabilities.&lt;/p&gt;Results:&lt;p&gt;Combined MEK and AKT inhibition modestly extended the survival of KPC mice and increased Egfr and ErbB2 phosphorylation levels. Tumor organoids, but not their normal counterparts, exhibited elevated phosphorylation of ERBB2 and ERBB3 after MEK and AKT blockade. A pan-ERBB inhibitor synergized with MEK and AKT blockade in human PDA organoids, whereas this was not observed for the EGFR inhibitor erlotinib. Combined MEK and ERBB inhibitor treatment of human organoid orthotopic xenografts was sufficient to cause tumor regression in short-term intervention studies.&lt;/p&gt;Conclusions:&lt;p&gt;Analyses of normal and tumor pancreatic organoids revealed the importance of ERBB activation during MEK and AKT blockade primarily in the malignant cultures. The lack of ERBB hyperactivation in normal organoids suggests a larger therapeutic index. In our models, pan-ERBB inhibition was synergistic with dual inhibition of MEK and AKT, and the combination of a pan-ERBB inhibitor with MEK antagonists showed the highest activity both &lt;i&gt;in vitro&lt;/i&gt; and &lt;i&gt;in vivo&lt;/i&gt;.&lt;/p&gt;&lt;/div&gt;

&lt;div&gt;AbstractPurpose:&lt;p&gt;Epithelial neoplasms of the appendix are difficult to study preclinically given their low incidence, frequent mucinous histology, and absence of a comparable organ in mice for disease modeling. Although surgery is an effective treatment for localized disease, metastatic disease has a poor prognosis as existing therapeutics borrowed from colorectal cancer have limited efficacy. Recent studies reveal that appendiceal cancer has a genomic landscape distinct from colorectal cancer and thus preclinical models to study this disease are a significant unmet need.&lt;/p&gt;Experimental Design:&lt;p&gt;We adopted an &lt;i&gt;ex vivo&lt;/i&gt; slice model that permits the study of cellular interactions within the tumor microenvironment. Mucinous carcinomatosis peritonei specimens obtained at surgical resection were cutoff using a vibratome to make 150-μm slices cultured in media.&lt;/p&gt;Results:&lt;p&gt;Slice cultures were viable and maintained their cellular composition regarding the proportion of epithelial, immune cells, and fibroblasts over 7 days. Within donor specimens, we identified a prominent and diverse immune landscape and calcium imaging confirmed that immune cells were functional for 7 days. Given the diverse immune landscape, we treated slices with TAK981, an inhibitor of SUMOylation with known immunomodulatory functions, in early-phase clinical trials. In 5 of 6 donor samples, TAK981-treated slices cultures had reduced viability, and regulatory T cells (Treg). These data were consistent with TAK981 activity in purified Tregs using an &lt;i&gt;in vitro&lt;/i&gt; murine model.&lt;/p&gt;Conclusions:&lt;p&gt;This study demonstrates an approach to study appendiceal cancer therapeutics and pathobiology in a preclinical setting. These methods may be broadly applicable to the study of other malignancies.&lt;/p&gt;&lt;/div&gt;

&lt;div&gt;AbstractPurpose:&lt;p&gt;Epithelial neoplasms of the appendix are difficult to study preclinically given their low incidence, frequent mucinous histology, and absence of a comparable organ in mice for disease modeling. Although surgery is an effective treatment for localized disease, metastatic disease has a poor prognosis as existing therapeutics borrowed from colorectal cancer have limited efficacy. Recent studies reveal that appendiceal cancer has a genomic landscape distinct from colorectal cancer and thus preclinical models to study this disease are a significant unmet need.&lt;/p&gt;Experimental Design:&lt;p&gt;We adopted an &lt;i&gt;ex vivo&lt;/i&gt; slice model that permits the study of cellular interactions within the tumor microenvironment. Mucinous carcinomatosis peritonei specimens obtained at surgical resection were cutoff using a vibratome to make 150-μm slices cultured in media.&lt;/p&gt;Results:&lt;p&gt;Slice cultures were viable and maintained their cellular composition regarding the proportion of epithelial, immune cells, and fibroblasts over 7 days. Within donor specimens, we identified a prominent and diverse immune landscape and calcium imaging confirmed that immune cells were functional for 7 days. Given the diverse immune landscape, we treated slices with TAK981, an inhibitor of SUMOylation with known immunomodulatory functions, in early-phase clinical trials. In 5 of 6 donor samples, TAK981-treated slices cultures had reduced viability, and regulatory T cells (Treg). These data were consistent with TAK981 activity in purified Tregs using an &lt;i&gt;in vitro&lt;/i&gt; murine model.&lt;/p&gt;Conclusions:&lt;p&gt;This study demonstrates an approach to study appendiceal cancer therapeutics and pathobiology in a preclinical setting. These methods may be broadly applicable to the study of other malignancies.&lt;/p&gt;&lt;/div&gt;

&lt;div&gt;AbstractPurpose:&lt;p&gt;&lt;i&gt;KRAS&lt;/i&gt; is mutated in the majority of pancreatic ductal adenocarcinoma. MAPK and PI3K-AKT are primary KRAS effector pathways, but combined MAPK and PI3K inhibition has not been demonstrated to be clinically effective to date. We explore the resistance mechanisms uniquely employed by malignant cells.&lt;/p&gt;Experimental Design:&lt;p&gt;We evaluated the expression and activation of receptor tyrosine kinases in response to combined MEK and AKT inhibition in KPC mice and pancreatic ductal organoids. In addition, we sought to determine the therapeutic efficacy of targeting resistance pathways induced by MEK and AKT inhibition in order to identify malignant-specific vulnerabilities.&lt;/p&gt;Results:&lt;p&gt;Combined MEK and AKT inhibition modestly extended the survival of KPC mice and increased Egfr and ErbB2 phosphorylation levels. Tumor organoids, but not their normal counterparts, exhibited elevated phosphorylation of ERBB2 and ERBB3 after MEK and AKT blockade. A pan-ERBB inhibitor synergized with MEK and AKT blockade in human PDA organoids, whereas this was not observed for the EGFR inhibitor erlotinib. Combined MEK and ERBB inhibitor treatment of human organoid orthotopic xenografts was sufficient to cause tumor regression in short-term intervention studies.&lt;/p&gt;Conclusions:&lt;p&gt;Analyses of normal and tumor pancreatic organoids revealed the importance of ERBB activation during MEK and AKT blockade primarily in the malignant cultures. The lack of ERBB hyperactivation in normal organoids suggests a larger therapeutic index. In our models, pan-ERBB inhibition was synergistic with dual inhibition of MEK and AKT, and the combination of a pan-ERBB inhibitor with MEK antagonists showed the highest activity both &lt;i&gt;in vitro&lt;/i&gt; and &lt;i&gt;in vivo&lt;/i&gt;.&lt;/p&gt;&lt;/div&gt;

Supplementary Data from An &lt;i&gt;Ex Vivo&lt;/i&gt; Organotypic Culture Platform for Functional Interrogation of Human Appendiceal Cancer Reveals a Prominent and Heterogenous Immunological Landscape

Supplementary Figure from An &lt;i&gt;Ex Vivo&lt;/i&gt; Organotypic Culture Platform for Functional Interrogation of Human Appendiceal Cancer Reveals a Prominent and Heterogenous Immunological Landscape

Supplementary Figure from An &lt;i&gt;Ex Vivo&lt;/i&gt; Organotypic Culture Platform for Functional Interrogation of Human Appendiceal Cancer Reveals a Prominent and Heterogenous Immunological Landscape

Supplementary Figure from An &lt;i&gt;Ex Vivo&lt;/i&gt; Organotypic Culture Platform for Functional Interrogation of Human Appendiceal Cancer Reveals a Prominent and Heterogenous Immunological Landscape

Supplementary Figure from An &lt;i&gt;Ex Vivo&lt;/i&gt; Organotypic Culture Platform for Functional Interrogation of Human Appendiceal Cancer Reveals a Prominent and Heterogenous Immunological Landscape

Supplementary Data from An &lt;i&gt;Ex Vivo&lt;/i&gt; Organotypic Culture Platform for Functional Interrogation of Human Appendiceal Cancer Reveals a Prominent and Heterogenous Immunological Landscape

Supplementary Figure from An &lt;i&gt;Ex Vivo&lt;/i&gt; Organotypic Culture Platform for Functional Interrogation of Human Appendiceal Cancer Reveals a Prominent and Heterogenous Immunological Landscape

Supplementary Figure from An &lt;i&gt;Ex Vivo&lt;/i&gt; Organotypic Culture Platform for Functional Interrogation of Human Appendiceal Cancer Reveals a Prominent and Heterogenous Immunological Landscape

Supplementary Table from An &lt;i&gt;Ex Vivo&lt;/i&gt; Organotypic Culture Platform for Functional Interrogation of Human Appendiceal Cancer Reveals a Prominent and Heterogenous Immunological Landscape

&lt;div&gt;Abstract&lt;p&gt;Pancreatic ductal adenocarcinoma (PDAC) is the most lethal common malignancy, with little improvement in patient outcomes over the past decades. Recently, subtypes of pancreatic cancer with different prognoses have been elaborated; however, the inability to model these subtypes has precluded mechanistic investigation of their origins. Here, we present a xenotransplantation model of PDAC in which neoplasms originate from patient-derived organoids injected directly into murine pancreatic ducts. Our model enables distinction of the two main PDAC subtypes: intraepithelial neoplasms from this model progress in an indolent or invasive manner representing the classical or basal-like subtypes of PDAC, respectively. Parameters that influence PDAC subtype specification in this intraductal model include cell plasticity and hyperactivation of the RAS pathway. Finally, through intratumoral dissection and the direct manipulation of &lt;i&gt;RAS&lt;/i&gt; gene dosage, we identify a suite of &lt;i&gt;RAS&lt;/i&gt;-regulated secreted and membrane-bound proteins that may represent potential candidates for therapeutic intervention in patients with PDAC.&lt;/p&gt;Significance:&lt;p&gt;Accurate modeling of the molecular subtypes of pancreatic cancer is crucial to facilitate the generation of effective therapies. We report the development of an intraductal organoid transplantation model of pancreatic cancer that models the progressive switching of subtypes, and identify stochastic and RAS-driven mechanisms that determine subtype specification.&lt;/p&gt;&lt;p&gt;&lt;i&gt;See related commentary by Pickering and Morton, p. 1448&lt;/i&gt;.&lt;/p&gt;&lt;p&gt;&lt;i&gt;This article is highlighted in the In This Issue feature, p. 1426&lt;/i&gt;&lt;/p&gt;&lt;/div&gt;

&lt;p&gt;Confocal z-stack imaging of immunofluorescent (IF) images of mStrawberry-hT3 grafts 4 weeks after IGO transplantation&lt;/p&gt;

&lt;p&gt;Confocal z-stack imaging of immunofluorescent (IF) images of mStrawberry-hT3 grafts 4 weeks after IGO transplantation&lt;/p&gt;

&lt;p&gt;Confocal z-stack imaging of immunofluorescent (IF) images of mStrawberry-hM1A grafts 4 weeks after IGO transplantation&lt;/p&gt;

&lt;p&gt;Confocal z-stack imaging of immunofluorescent (IF) images of mStrawberry-hM1A grafts 4 weeks after IGO transplantation&lt;/p&gt;

&lt;p&gt;Supplemental Figures&lt;/p&gt;

&lt;p&gt;Supplemental Table Legends&lt;/p&gt;

&lt;p&gt;Supplemental Figure Legends&lt;/p&gt;

&lt;p&gt;Table S1&lt;/p&gt;

&lt;p&gt;Table S2&lt;/p&gt;

&lt;p&gt;Table S4&lt;/p&gt;

&lt;p&gt;Table S5&lt;/p&gt;

&lt;p&gt;Table S3&lt;/p&gt;

&lt;p&gt;Confocal z-stack imaging of immunofluorescent (IF) images of mStrawberry-hM1A grafts 2 weeks after IGO transplantation&lt;/p&gt;

&lt;p&gt;Supplementary Table S1 Survival times of IGO and OGO mice Supplementary Table S2 Characteristics of patient-derived organoids, including KRAS, TP53, SMAD4, CDKN2A mutation status and patient stage Supplementary Table S3 Summary of Survival Data, including engraftment rate, mean survival, metastatic frequency Supplementary Table S4 Primers for quantitative PCR&lt;/p&gt;

&lt;p&gt;Comparison of IGO- and OGO-derived lesions&lt;/p&gt;