Primary Pancreatic Tumors Research Articles

Genomic analysis of paired primary and metastatic pancreatic ductal adenocarcinoma tumors.

758 Background: The genomics of pancreatic ductal adenocarcinoma (PDAC) have been increasingly understood allowing for improvements in treatment, yet the clinical relevance of PDAC evolution is less well studied. The aim of this study is to evaluate genomic differences and clinical correlations between primary pancreatic tumors and paired metastases using a targeted sequencing panel. Methods: Patients who underwent surgical resection for PDAC with recurrent disease who had targeted genomic sequencing of both the primary tumor and a metastasis were included. Genomic alterations were determined using a panel of cancer-related genes (MSK-IMPACT). OncoKB was used to annotate driver alterations. MATH scores were used to quantify intratumoral heterogeneity. Comparison between paired samples was performed and association with clinical variables was assessed. Results: There were 55 patients included; 20% (n=11) received neoadjuvant therapy, 91% (n=50) had adjuvant therapy and 36% (n=20) had adjuvant radiation. The most common sites of metastasis sequenced were lung (36%, n=20), liver (35%, n=19) and local (13%, n=7). There was concordance between the first site of recurrence and site sequenced in 93% (n=51) of cases with a median time between resection and biopsy of recurrence of 25 months. The most commonly altered genes are KRAS (96%), TP53 (83%), CDKN2A (40%), SMAD4 (25%) and RNF43 (13%). The majority of alterations are shared between the primary tumor and metastasis. Clonal mutations were defined as cancer cell fraction (CCF) >0.8. The majority of shared mutations are clonal; 52% of mutations are clonal in both the primary and metastasis, and clonality is preserved in 76% of shared mutations in metastases. The most commonly shared alterations are in driver genes and the majority are clonal- TP53 (80%), KRAS (78%), CDKN2A (77%) and SMAD4 (64%). The proportion of clonal mutations among drivers is higher than variants of unknown significance (p=0.005). There are 31 mutations private to the metastasis in 19 patients, 12 of which are clonal (39%). Mutations private to the metastasis are more common in patients who received adjuvant systemic therapy (p=0.035); however this was not seen when comparing patients who received adjuvant radiation to those who did not (p=0.38). MATH scores are higher in the metastasis as compared to the primary in all patients (p=0.0096), including those who received adjuvant treatment (p=0.002), indicating increased intratumoral heterogeneity in metastases. Conclusions: A targeted sequencing panel demonstrates that the majority of driver mutations are clonal and preserved between the primary tumor and metastasis. Additional private mutations and increased intratumoral heterogeneity are noted in metastasis, and our data suggests that this may be associated with exposure to systemic therapy.

Comparison of mutational landscape in primary and metastatic pancreatic tumors.

781 Background: Genomic profiling has brought to the forefront the clinical relevance of intratumoral heterogeneity. Oncogenic KRAS mutation is the most common driver event in pancreatic ductal adenocarcinoma (PDAC), but little is known about how KRAS alteration may cooperate with other genetic lesions to support dissemination and growth of metastatic disease. Therefore, an improved understanding of molecular events affecting the clinical course of KRAS -altered PDAC is needed to identify biomarkers of early disease and expand the repertoire of targeted therapies. Methods: We retrospectively analyzed tissue samples from PDAC patients using the OncoExTra tumor-normal whole exome and whole transcriptome test between April 2018 and May 2024. The prevalence of actionable somatic alterations was determined overall and by specimen location (primary vs. metastatic). Fisher’s exact test with FDR-based correction for multiple testing was used to identify co-alterations with KRAS and 19 DNA damage response (DDR) gene alterations. Results: PDAC samples from 434 patients (51.2% female; mean age 65.4±10.9 years) were analyzed. KRAS alterations were detected in 369 (85.0%) samples: 198 (45.6%) primary and 239 (55.1%) metastatic. KRAS G12D (32.7%) and KRAS G12V (29.5%) were the most common KRAS mutations. The frequency of KRAS alterations was 85.9% and 84.5% in primary and metastatic samples, respectively. TP53 alterations occurred in 68.2% samples overall and in 64.6% and 71.1% of primary and metastatic samples, respectively. Examination of co-alterations in KRAS -altered versus KRAS -WT samples uncovered enrichment of TP53 alterations in KRAS -altered (277 samples, 75.1%) compared to KRAS -WT samples (19 samples, 29.2%) ( p <0.001). Also, BRAF mutations and SND1:BRAF fusions exclusively occurred in metastatic KRAS -WT samples, although the number of events was small ( n =4 and n =2, respectively). We also found that MTAP was significantly co-altered in metastatic KRAS -WT samples (n=6, 16.2%) compared to KRAS -altered samples (6 samples, 3.0%) ( p =0.004). A total of 21.9% of all PDAC samples had an alteration in at least 1 DDR gene. No associations were observed between KRAS alteration status and alteration in DDR genes. However, TP53 alterations were more frequent in non-DDR-altered samples ( p <0.001), while CDKN2B alterations were enriched in DDR-altered samples ( p =0.025). Conclusions: We observed expected rates of alterations in known PDAC driver genes and uncovered higher co-occurrence of KRAS and TP53 alteration in metastatic samples. Additionally, TP53 alterations were less frequent in DDR-altered samples. Our findings suggest that a number of therapy approaches including BRAF, WEE1, PARP, and KRAS inhibitors as well as epigenetic modulators, alone or in combination, could improve clinical outcomes in PDACs with specific mutational profiles.

Percutaneous Ultrasound-Guided Radiofrequency Ablation as a Therapeutic Approach for the Management of Insulinomas and Associated Metastases in Dogs.

Insulinomas are the most common neoplasms of the endocrine pancreas in dogs, leading to persistent hypoglycemia due to inappropriate insulin secretion. The standard treatment is surgical resection, but it carries significant risks, including pancreatitis and diabetes mellitus. This study investigates the efficacy and safety of percutaneous ultrasound-guided radiofrequency ablation (RFA) as an alternative to surgery. A total of 29 dogs diagnosed with insulinoma were treated with RFA, targeting both primary pancreatic tumors and metastases in regional lymph nodes or the liver. Blood glucose levels and tumor size were monitored before and after the procedure. RFA led to a significant increase in blood glucose levels and a reduction in tumor size in all patients, with minimal postoperative complications. The results suggest that RFA is a feasible and effective treatment option for insulinomas in dogs.

Abstract A020: LncTransformer: Identifying novel prognostic long-noncoding RNA biomarkers for pancreatic cancer using deep learning

Abstract Pancreatic cancer remains a formidable challenge due to high mortality rates and limited therapeutic options due to late detection of the cancer. Recent literature has focused on investigating the potential of long noncoding RNAs (lncRNAs) as biomarkers in several cancers. To identify significantly altered expression of lncRNA in pancreatic cancer, I collected information from the Cancer Genome Atlas (TCGA) and extracted RNA- sequencing (RNA-seq) transcriptomic profiles of pancreatic carcinomas. Out of 60,660 gene transcripts shared between 151 pancreatic cancer patients, 38 lncRNAs were identified to be significantly differentially expressed. To find the lncRNAs related to metastatic progression of pancreatic cancer, different machine learning algorithms, including logistic regression (LR), support vector machine (SVM), random forest classifier (RFC), and a custom autoencoder model were trained to identify potential prognostic biomarkers. The custom deep learning model predicted metastatic prognostic biomarkers with a 92% accuracy, with the second-best accuracies coming from the SVM and RFC models, having an accuracy of 76%. Using the deep learning model, the following novel lncRNA and gene biomarkers were identified: LINC01300, SERPINB13, AC010789.1, TMPRSS15, DUSP5- DT, AL513128.3, MIR205HG, LINC00486, RF00019, LINC01115, and AC133530.1. Further investigating these results, specifically the identified lncRNA, the LINC01300 was identified to be potentially circulating in the blood. If further analysis proves this hypothesis correct then LINC01300 along with other identified genes could serve as biomarkers in a liquid biopsy. The identified biomarkers would be especially helpful in rural areas with lower accessibility to healthcare as it would allow for an easier, more efficient, and cost-effective method of pancreatic cancer detection. Based on these findings, further investigations of this gene panel in vitro and in vivo will be conducted, as they could be targeted for improved outcomes in pancreatic cancer patients and assist in the diagnosis of metastatic progression based on RNA-seq data of primary pancreatic tumors or the development of a liquid biopsy. Citation Format: Shivali Singh. LncTransformer: Identifying novel prognostic long-noncoding RNA biomarkers for pancreatic cancer using deep learning [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: RNAs as Drivers, Targets, and Therapeutics in Cancer; 2024 Nov 14-17; Bellevue, Washington. Philadelphia (PA): AACR; Mol Cancer Ther 2024;23(11_Suppl):Abstract nr A020.

Implementation of structured radiology reporting and its associated accuracy in comparison to pancreas multi-disciplinary clinic expert radiology review.

To evaluate the feasibility of implementation of structured reporting in the setting of a high-volume pancreatic multidisciplinary clinic (PMDC) and to assess its value by comparing the accuracy of structured reports with expert imaging reviews. A single institutional prospective cohort study was conducted during March 2022 to May 2024 to understand the feasibility of implementation of structured reporting (SR) for all patients who were seen in our weekly PMDC. Descriptive and regression analyses were performed to find an association between SR and difference in vascular involvement of the primary pancreatic tumor between the radiology report and expert radiologist review (gold standard) during PMDC. Among 466 patients seen in the PMDC, 426 (91.4%) had reports generated prior to PMDC. Of this, 294 reports met the inclusion criteria. The usage of SR increased from 58.3% in Mar 2022 to 87.8% in June 2024. Majority of the reports that used SR (n = 226, 76.9%), were performed for initial staging (n = 197, 67.0%) of PC. The median years of experience of reading radiologists that used non-SR was 14 (IQR: 8-27) years, while it was 9 (IQR -9-15) years for those who used SR (p = 0.030). Of note, as compared to the radiology report, increased vascular involvement was noted in PMDC review 62.5% (20 out of 32) of the time with non-SRs, whereas increased vascular involvement during PMDC review was noted in only 36.6% (48 out of 132) of the time with SRs. On multivariable analysis, using SR lowered the odds of increase in vascular involvement during PMDC review by 0.29 times (95CIs 0.11-0.79; p = 0.015). SR is feasible and superior to the free-text reporting with respect to the accuracy of peri-pancreatic vascular involvement. While its use cannot replace the PMDC radiology review, it can nonetheless be an indispensable tool in clinical management, particularly in a non-PMDC setting.

Morbidity and Mortality Following Surgery for Pancreatic Cancer in Low- and Middle-Income Countries: A Systematic Review and Meta-Analysis.

Measuring postoperative outcomes after complex cancer operations such as pancreatectomy is vital to improve cancer surgery in low- and middle-income countries (LMICs); however, such data is often limited. This study aimed to review existing research and obtain baseline estimates for postoperative mortality and morbidity after pancreatic cancer surgery in LMICs. PubMed, Embase, Web of Science Core Collection, and Global Index Medicus were systematically searched for original articles published between January 2005 and May 2022. LMICs based studies reporting postoperative mortality, morbidity, and/or length of stay of patients with primary pancreatic tumors undergoing pancreaticoduodenectomy and/or distal pancreatectomy were included. Of 18 344 unique titles and abstracts retrieved, 114 studies met the inclusion criteria. Of these, 51 "good" quality studies comprising 7528 patients were included in the meta-analyses. Pooled estimates for pancreatic fistula were 16.6% (95% CI 14.0-19.7, p < 0.001); 16.0% (95% CI 11.1-22.5, p < 0.001) for Clavien-Dindo grade 3 and 4 complications; 13.4% (95% CI 9.8-17.9, p < 0.001) for wound infection; and 4.4% (95% CI 3.3-5.7, p < 0.001) for postoperative mortality. This is the first systematic review and meta-analysis examining surgical complications after pancreatic surgery in LMICs. We highlight a lack of data and the need to further evaluate surgical outcomes in LMICs.

Predictive genomic and transcriptomic analysis on endoscopic ultrasound-guided fine needle aspiration materials from primary pancreatic adenocarcinoma: a prospective multicentre study

We apply endoscopic ultrasound-guided fine needle aspiration biopsy to cytopathologically diagnose and sample nucleic acids from primary tumours regardless of the disease stage. 397 patients with proven pancreatic adenocarcinoma were included and followed up in a multicentre prospective study. DNA and mRNA were extracted from materials of primary tumours obtained by endoscopic ultrasound-guided fine needle aspiration biopsy and analysed using targeted deep sequencing and RNAseq respectively. The variant allele frequency of the KRAS mutation was used to evaluate the tumour cellularity, ranging from 15 to 20% in all cells, regardless of the tumour stage. The molecular profile of metastatic primary tumours significantly differed from other types of tumours, more frequently having TP53 mutations (p=0.0002), less frequently having RNF43 mutations, and possessing more basal-like mRNA component (p=0.001). Molecular markers associated with improved overall survival were: mutations in homologous recombination deficiency genes in patients who received first-line platinum-based chemotherapy (p=0.025) and wild-type TP53 gene in patients with locally advanced tumours who received radio-chemotherapy (p=0.01). The GemPred transcriptomic profile was associated with a significantly better overall survival in patients with locally advanced or metastatic pancreatic cancer who received a gemcitabine-based first-line treatment (p=0.019). The combination of genomic and transcriptomic analyses of primary pancreatic tumours enables us to distinguish metastatic tumours from other tumour types. Our molecular strategy may assist in predicting overall survival outcomes for platinum or gemcitabine-based chemotherapies, as well as radio-chemotherapy. Institut National Du Cancer (BCB INCa_7294), CHU of Toulouse, Inserm and Ligue Nationale Contre le Cancer (CIT program).

7940 Insulinoma as a Rare Manifestation of MEN4

Abstract Disclosure: H. Han: None. J. Moalem: None. A.R. Shih: None. B.J. Gigliotti: None. Background/Objective: Multiple endocrine neoplasia 4 (MEN4) is a rare syndrome that is caused by germline mutations in CKDN1B. Its phenotypic expression is similar to multiple endocrine neoplasia 1 (MEN1). Manifestations include primary hyperparathyroidism (PHPT), pituitary adenomas, and pancreatic neuroendocrine tumors (NET). Prevalence of MEN4 is less than one per million. Case Report: A 55-year-old female with history of hypercalcemia presented with symptomatic hypoglycemia. She had a fasting plasma glucose of 41mg/dL, proinsulin of 84.3 pmol/L, insulin level of 24 uIU/mL, c-peptide of 5.2 ng/mL, and beta hydroxybutyrate level of 0.34 mmol/L, consistent with endogenous hyperinsulinism. She was incidentally noted to have PHPT. CT abdomen showed a 1.5 x 1.1 x 1.0 cm pancreatic lesion consistent with an insulinoma. Pathology from subsequent Whipple surgery showed that it was a well-differentiated neuroendocrine tumor with no metastasis. She became normoglycemic after surgery. Germline testing revealed a variant of unknown significance in CDKN1B (p.R93W). Discussion: Increasing evidence suggests that MEN4 exhibits subtle differences in penetrance and natural history compared to MEN1. A recent systemic review of MEN4 cases showed that most gastrointestinal NETs in MEN4 are non-functional NETs and gastrinomas; to date, no insulinomas have been reported. PHPT in MEN4 may exhibit a lower risk of recurrence after parathyroidectomy. This case highlights the importance of germline genetic testing when a patient presents with clinical manifestations of MEN1. Conclusion: This is the first reported case of insulinoma in MEN4. Presentation: 6/3/2024

Spatial mapping of primary and metastatic pancreatic tumor ecosystems.

Spatial mapping of primary and metastatic pancreatic tumor ecosystems.

Trichorhinophalangeal syndrome 1 expression in breast and nonbreast metastases from Müllerian, lung, gastrointestinal tract, and pancreatic primary tumors by immunohistochemistry with cytology cell block specimens.

Trichorhinophalangeal syndrome 1 (TRPS1) expression in primary breast and other solid tumors has been investigated but its role as a marker in metastatic tumors is unclear. The objective of this study was to evaluate the sensitivity and specificity of TRPS1 as a breast cancer immunomarker in metastatic tumors that originated from breast, Müllerian, lung, gastrointestinal (GI), and pancreatic primary tumors with cell blocks from fine-needle aspiration (FNA) and effusion specimens. Cell blocks were immunostained with anti-TRPS1 monoclonal antibody (clone EPR16171). Histochemical scores (H scores) (proportion × intensity; range, 0-300) were assigned; H scores of ≥10 were considered positive. Overall, 160 specimens were examined, including 127 FNAs (35 breast, 25 Müllerian, 36 lung, and 31 GI and pancreatic carcinomas) and 33 effusion specimens (18 breast, 12 Müllerian, one lung, and two GI carcinomas). TRPS1 was positive in 51 of 53 (96%) metastatic breast carcinomas and in 28 of 107 (26.2%) nonbreast metastatic tumors. Metastatic breast carcinoma showed the highest mean H score of 247.35, compared to 45.36 in Müllerian, 8.4 in lung, and 5.88 in GI tumors. The sensitivity and specificity of TRPS1 for identifying a breast origin in metastatic tumors was 96.22% and 72.89%, respectively. Despite high overall sensitivity, TRPS1 showed lower specificity as a breast immunomarker because of its expression in nonbreast tumors. The mean H score in nonbreast tumors was significantly lower than in metastatic breast tumors. It is important to recognize the broad range of expression of TRPS1 in metastatic breast and nonbreast tumors to avoid an incorrect determination of a metastatic tumor's organ of origin.

Metástasis cerebral múltiple de adenocarcinoma pancreático. Reporte de caso

Introduction: Brain metastases are the most common malignant lesions in the central nervous system. Brain metastases from pancreatic cancer are very rare, with poor prognosis. The present paper aims to describe a rare pathology and the work carried out for the patient's care. Case report: 49-year-old man with personality changes, depression, and apathy. Five days before admission, he presented dysarthria, added left hemiparesis, and disorientation that progressed to sudden neurological deterioration that required advanced airway management. A computed tomography study was seen with cerebral cystic lesions. A decompressive craniectomy and drainage of the larger lesión was performed, with subsequent resection. The study protocol with immunohistochemistry reports CK 19, compatible with pancreatic adenocarcinoma. Conclusions: A rare case of multiple brain metastases and suspected lung metastasis, both secondary to primary pancreatic adenocarcinoma was presented. The patient began with symptoms associated with brain lesions. The incidence of brain metastases with a primary pancreatic tumor is very low, and this is an exceptional case when presenting with neurological symptoms. Surgical resection of the brain lesion had a limited role in the clinical improvement of the patient since the progression of the disease was rapid. Still, it was useful to establish a diagnosis by immunohistochemistry. Since there are no screening tests for pancreatic tumors, it is difficult to identify them in early stages and without gastrointestinal symptoms. Keywords: Pancreatic adenocarcinoma; brain tumors; brain metastases; cytokeratin 19; immunohistochemistry.

Cancer tissue of origin constrains the growth and metabolism of metastases.

Metastases arise from subsets of cancer cells that disseminate from the primary tumour1,2. The ability of cancer cells to thrive in a new tissue site is influenced by genetic and epigenetic changes that are important for disease initiation and progression, but these factors alone do not predict if and where cancers metastasize3,4. Specific cancer types metastasize to consistent subsets of tissues, suggesting that primary tumour-associated factors influence where cancers can grow. We find primary and metastatic pancreatic tumours have metabolic similarities and that the tumour-initiating capacity and proliferation of both primary-derived and metastasis-derived cells is favoured in the primary site relative to the metastatic site. Moreover, propagating cells as tumours in the lung or the liver does not enhance their relative ability to form large tumours in those sites, change their preference to grow in the primary site, nor stably alter aspects of their metabolism relative to primary tumours. Primary liver and lung cancer cells also exhibit a preference to grow in their primary site relative to metastatic sites. These data suggest cancer tissue of origin influences both primary and metastatic tumour metabolism and may impact where cancer cells can metastasize.

Comments and illustrations of the European Federation of Societies for Ultrasound in Medicine contrast-enhanced ultrasound guidelines: Multiparametric imaging and EUS-guided sampling in rare pancreatic tumors. Benign mesenchymal pancreatic tumors.

The focus of the review is on primary benign mesenchymal pancreatic tumors and their imaging appearance. These tumors are extremely rare. Usually, they are not diagnosed until postoperative histology is available, and so even benign tumors have undergone extensive pancreatic resection. The very limited data on abdominal and EUS findings including contrast-enhanced techniques of these pancreatic lesions are summarized here. Case reports will be presented for some of these rare tumors with application of modern ultrasound and endosonographic techniques.

FDG PET/CT in Staging of α-Fetoprotein-Producing Hepatoid Adenocarcinoma of the Pancreas.

Hepatoid adenocarcinoma of the pancreas is a rare aggressive tumor with poor prognosis. We describe contrast-enhanced CT and FDG PET/CT findings in a case of pancreatic hepatoid adenocarcinoma with significantly elevated α-fetoprotein level presenting as acute pancreatitis. The primary pancreatic tumor diffusely involved the pancreas and showed heterogeneous enhancement mimicking acute necrotizing pancreatitis on contrast-enhanced CT. FDG PET/CT showed intense FDG uptake (SUV max , 24.5) of the left supraclavicular and retroperitoneal lymph node metastases, suggesting FDG PET/CT may be useful for staging of this aggressive tumor.

Andrographolide suppresses the malignancy of pancreatic cancer via alleviating DNMT3B-dependent repression of tumor suppressor gene ZNF382

BackgroundPancreatic ductal adenocarcinoma (PDAC) is a highly aggressive cancer type that urgently requires effective therapeutic strategies. Andrographolide, a labdane diterpenoid compound abundant in Andrographis paniculata, has anticancer effects against various cancer types, but its anticancer activity and mechanism against PDAC remain largely uncharacterized. PurposeThis study explores novel drug target(s) and underlying molecular mechanism of andrographolide against PDAC. Study design and methodsThe malignant phenotypes of PDAC cells, PANC-1 and MIA PaCa-2 cells, were measured using MTT, clonogenic assays, and Transwell migration assays. A PDAC xenograft animal model was used to evaluate tumor growth in vivo. Western blot, immunofluorescence and immunohistochemistry were used for measuring protein expression. The TCGA database was analyzed to evaluate promoter methylation status, gene expression, and their relationship with patient survival rates. RT-qPCR was used for detecting mRNA expression. Reporter assays were used for detecting signal transduction pathways. Promoter DNA methylation was determined by sodium bisulfite treatment and methylation-specific PCR (MSP). The biological function and role of specific genes involved in drug effects were measured through gene overexpression. ResultsAndrographolide treatment suppressed the proliferation and migration of PDAC cells and impaired tumor growth in vivo. Furthermore, andrographolide induced the mRNA and protein expression of zinc finger protein 382 (ZNF382) in PDAC cells. Overexpression of ZNF382 inhibited malignant phenotypes and cancer-associated signaling pathways (AP-1, NF-κB and β-catenin) and oncogenes (ZEB-1, STAT-3, STAT-5, and HIF-1α). Overexpression of ZNF382 delayed growth of PANC-1 cells in vivo. ZNF382 mRNA and protein expression was lower in tumor tissues than in adjacent normal tissues of pancreatic cancer patients. Analysis of the TCGA database found the ZNF382 promoter is hypermethylated in primary pancreatic tumors which correlates with its low expression. Furthermore, andrographolide inhibited the expression of DNA methyltransferase 3 beta (DNMT3B) and increased the demethylation of the ZNF382 promoter in PDAC cells. Overexpression of DNMT3B attenuated the andrographolide-suppressed proliferation and migration of PDAC cells. ConclusionOur finding revealed that ZNF382 acts as a tumor suppressor gene in pancreatic cancer and andrographolide restores ZNF382 expression to suppress pancreatic cancer, providing a novel molecular target and a promising therapeutic approach for treating pancreatic cancer.

A cross-species transcriptomic analysis reveals a novel 2-dimensional classification system explaining the invasiveness heterogeneity of pancreatic neuroendocrine tumor

Pancreatic neuroendocrine tumors (PanNETs), the second most common type of primary pancreatic tumors, display notable heterogeneity in invasiveness. Current knowledge regarding genomic alterations, including DAXX/ATRX, MEN1 mutations, and copy number variations (CNVs), provides some insights into tumor invasiveness. However, the underlying reasons for the significant variation in invasiveness between insulinoma and other types of PanNETs remain unclear. To construct a comprehensive model for the stratification of prognosis, we employed analysis of both the well-established Rip1-Tag 2 (RT2) mouse model of PanNETs and human PanNETs with various functional types. Firstly, by applying single-cell and bulk RNA sequencing in PanNETs from different ages and strains of RT2 mice and human PanNETs, we introduced a 2-dimensional (2D) classification system. Based on the 2D classification system, human PanNETs were mainly classified as benign insulinomas or non-insulinomas subclusters. Non-insulinomas subtypes mainly included gastrinomas, glucagonomas, VIPomas, and NF-PanNETs, which all exhibited potential invasiveness. In addition, we discovered an enrichment of specific CNV patterns and mutations in corresponding human PanNET subclusters. Then we denoted somatic DAXX/ATRX as the ‘second hit’ and confounding factors for invasiveness. Finally, by combining the 2D system, DAXX/ATRX mutation status, and tumor diameter, a group of indolent PanNETs with minimal recurrence risk was identified. In conclusion, our current work constructed a comprehensive model to elucidate the heterogeneity of invasiveness in PanNETs and improve prognostic stratification.

The Role of Endoscopic Ultrasonography (EUS) in Metastatic Tumors in the Pancreas: 10 Years of Experience from a Single High-Volume Center.

Metastatic pancreatic lesions (MPLs) are relatively uncommon, constituting 2 to 5% of all pancreatic tumors. They often manifest as solitary lesions without distinct clinical symptoms, usually identified incidentally during radiologic imaging for the surveillance of prior malignancies. Differentiating these lesions from primary pancreatic tumors presents a significant challenge due to their nonspecific presentation. We aimed to prospectively assess the effectiveness of endoscopic ultrasound (EUS) and EUS-guided fine needle aspiration/biopsy (EUS-FNA/B) in diagnosing MPLs in a carefully selected cohort of patients presenting with pancreatic masses. Additionally, we sought to examine the relevance of specific EUS findings in supporting the initial diagnosis of MPLs and their agreement with the definitive cytological diagnosis. This study retrospectively analyzed data from 41 patients diagnosed with MPLs between 2013 and 2023, focusing on their clinical and pathological characteristics, the echogenic features of the pancreatic lesions, and the techniques used for tissue acquisition. The incidence of MPLs in our cohort was 3.53%, with the most frequent primary tumors originating in the kidney (43.90%), colorectum (9.76%), lung (9.76%), lymphoma (9.76%), and breast (4.88%). MPLs typically presented as hypoechoic, oval-shaped lesions with well-defined borders and were predominantly hypervascular. Interestingly, 68.29% of the cases were discovered incidentally during follow-up of the primary tumors, while the involvement of the common bile duct was uncommon (19.51%). EUS and EUS-FNA/B have been validated as valuable diagnostic tools for identifying MPLs. While our findings are promising, further multicenter studies are necessary to corroborate these results and elucidate the predictive value of specific EUS characteristics in determining the metastatic origin of pancreatic lesions.

Abstract 244: Patient-derived organoids: A pre-clinical model to assess infection and killing capacity of viral vectors for cancer therapy

Abstract HUB’s patient-derived organoids (PDOs) are in vitro models that preserve tissue morphology and original cellular complexity. Additionally, PDOs are compatible with (high) throughput screening methods, enabling informed decision-making early in the drug development pipeline and significantly improving the odds of positive outcomes in clinical trials. Akamis Bio has developed experimental viral vector-based tumour gene therapies that have the potential to treat a variety of solid tumours by driving the expression of immunologically active biomolecules and therapeutic proteins hampering tumour immune evasion. These vectors are based on a replication competent, chimeric group B adenovirus backbone that selectively replicates and expresses transgene payloads in tumor cells, and additionally exerts oncolytic activity. To evaluate the efficacy of such a virus-based gene delivery strategy, HUB set up a proof-of-concept study to assess the propagation capability of Akamis Bio’s viral vectors in tumour PDOs. Intact PDOs from primary pancreatic tumours were infected with several viral loads, ranging from 0.1 viral particles per cell (PPC) to 100 PPC. The viral vector encoded a GFP reporter gene to identify infected cells using fluorescence imaging. The cultures were imaged daily for 14 days, allowing the assessment of cytotoxicity and infection efficiency and dynamics. Independently of PPC, infections always started in the exterior of PDOs in a few GFP-positive cells. The gradual increase over time in GFP-signal toward the interior of PDOs suggests the high likelihood of secondary infection events. Crucially, GFP intensity was correlated with cell death in PDOs, as evidenced by morphological features detected in brightfield images. Moreover, the infection dynamics were dose-dependent, as the GFP intensity peak arose later with decreasing PPC. These results show the capacity of HUB PDOs to study the infection dynamics of Akamis viral vectors. This pre-clinical platform permits rapid and efficient screening and dose evaluation for oncolytic virotherapies. Unique access to extensive tumour PDO biobanks with characterized genomic landscapes allows best-in-class stratification of treatment response based on tumour type and genetic heterogeneity. Citation Format: Francisco Morales-Rodriguez, Maria Stella Sasso, Taya Bezhaeva, Samantha Bailey-Bucktrout, Ka Wai Lai, Foteini Gkogkou, Sylvia Boj. Patient-derived organoids: A pre-clinical model to assess infection and killing capacity of viral vectors for cancer therapy [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 244.

Abstract 6631: Aging influences the pancreatic ductal adenocarcinoma tumor immune microenvironment to promote features of immunosuppression

Abstract Advancing age is the strongest independent risk factor for the development of pancreatic ductal adenocarcinoma (PDAC) and a negative prognostic factor. PDACs are typically immunologically “cold” tumors and do not often respond to currently approved immunotherapy treatment approaches. How aging may alter non-malignant cells, such as fibroblasts and immune cell populations, in the PDAC tumor microenvironment (TME) to decrease anti-tumor immune responses is not understood. We identified that aged microenvironments significantly alter the growth and progression of PDAC tumors. Orthotopic KPC and Panc02 mouse PDAC cell line injections into the pancreata of aged (&amp;gt;64-week-old) compared to young (6-8-week-old) C57BL/6 mice result in more rapid tumor growth and increased frequency of liver metastases in vivo. Tumors from aged mice have high expression of the TGFβ family member GDF-15 and hyperactivation of AKT signaling driven by the release of secreted factors from aged pancreatic fibroblasts. We found that in aged microenvironments there is a marked reduction in the number of CD8+ T cells and an increase in FoxP3+ regulatory T cells in primary orthotopic pancreatic tumors using the KPC and Panc02 models. In addition, we performed portal vein injections to establish liver metastases to study the differences in immune cell infiltration in metastases from young vs. aged microenvironments. Aged mice form more and larger liver metastases compared to young mice, and metastatic lesions in aged mice have decreased CD8+ T cell infiltration when compared to young mice. Since tumors in aged microenvironments have increased AKT activation compared to young microenvironments, we next tested if AKT signaling was sufficient to alter immune cell infiltration in PDAC tumors. In young mice, treatment with recombinant GDF-15, which activates AKT signaling, reduced CD8+ T cell infiltration into tumors. Conversely, in KPC tumors grown in aged mice treated with the AKT inhibitor MK-2206, there was a trend toward increased CD8+ T cell infiltration and a significant reduction in immunosuppressive FoxP3+ Tregs. Together, these data highlight age-dependent differences in the immune infiltration in PDAC tumors. They suggest that activation of AKT signaling can drive features of immunosuppression in PDAC, providing the rationale for targeting AKT signaling to improve antitumor immune responses in PDAC. Citation Format: Emma Kartalia, James M. Leatherman, Jae W. Lee, Elizabeth M. Jaffee, Ashani T. Weeraratna, Daniel J. Zabransky. Aging influences the pancreatic ductal adenocarcinoma tumor immune microenvironment to promote features of immunosuppression [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 6631.

Abstract 5373: Decoding the role of intrinsic pancreatic cellular signaling in shaping the immunosuppressive tumor microenvironment

Abstract Background: Pancreatic ductal adenocarcinoma (PDAC) has the highest mortality rate among major cancers, with over 50% of patients having liver metastases at diagnosis. Conventional T-cell-based immunotherapies are ineffective against PDAC liver metastases due to the intricate hepatic tumor microenvironment (TME) that hinders effective immune responses. Thus, it is vital to promote the influx of cytotoxic lymphocytes and prime antitumor immunity. PDAC cells exhibit plasticity and intrinsic cellular heterogeneity, leading to varying immune cell infiltrates and immune responses. Concurrently, early metastases to the liver create an immunosuppressive environment. Our study employs multiple PDAC models, originating from a congenic array of distinct PDAC cell clone tumors with varying degrees of T cell infiltration to delineate the signaling pathways that lead to immunosuppression in the pancreas and liver. Methods: The compendium of congenic PDAC murine cell clones mirrors immune heterogeneity observed in tumors, spanning from low to high T cell infiltration. To overcome a scarcity of tumor-specific neoepitopes in PDAC, we engineered PDAC cell clones expressing chicken ovalbumin (OVA) for antigen-specific T and B cell responses. By subcutaneous and intraportal vein injection of PDAC cell clones into mice, we induce primary pancreatic and metastatic liver tumors to explore immune phenotypes and assess anti-tumor adaptive immune responses, including myeloid and lymphoid cell subsets. Results: In vivo engraftment of PDAC clones showed varied CD4+/CD8+ T cells and polymorphonuclear myeloid-derived suppressor cells, accentuated with immunogenic OVA antigen expression. While all OVA+ PDAC lines elicited antigen-specific immune responses, only ‘TIL high’ tumors were eradicated, while ‘TIL low’ clones persisted in vivo. Additionally, ‘TIL low’ clones formed liver metastases upon intraportal injection, despite OVA expression. RNAseq unveiled differential expression in IL-1 family cytokines and receptors, chemokine-like factor gene superfamily, parathyroid hormone relevant function and metabolism. Current investigations include altering these pathways to re-program the tumor microenvironment and induce local immune suppression. Conclusion: Using diverse PDAC models, we created tumors with immune heterogeneity and altered transcriptional profiles. We identified validated differentially expressed immune altering cytokines, such as CXCL1 and CSF3, and potential novel IL-1 family genes and parathyroid signaling genes. The altered TME conferred protection against tumor antigen-specific immunity in certain clones, both in subcutaneous and liver metastasis models. Ongoing studies will assess the impact of these genes in the distinct environments, offering avenues for immunotherapeutic strategies targeting pancreatic cancer liver metastasis. Citation Format: Bushangqing Liu, Ethan Agritelley, Daniel Nussbaum, Junping Wei, Gangjun Lei, Melissa Gajda, Zachary Hartman. Decoding the role of intrinsic pancreatic cellular signaling in shaping the immunosuppressive tumor microenvironment [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 5373.