Pancreatic Ductal Adenocarcinoma Cases Research Articles

Abstract PR012: KRAS mutation-specific effects on the tumor immune microenvironment drive tumor progression in pancreatic cancer

Abstract Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive malignancy with abysmal survival rates. The highly immunosuppressive microenvironment of PDAC poses a major barrier to effective therapy. KRAS mutations are near-ubiquitous in PDAC, and studies indicate clinical outcomes vary depending on the specific KRAS genotype. Given that tumor genotype can shape the immune cell composition of tumors, we examined the immune cell composition of pancreatic tumors with specific KRAS mutations, focusing on KRASG12D mutations (representing 40% of PDAC cases which have the worst prognosis) and KRASG12R mutations (which make up 20% of PDAC cases and have a better prognosis). Orthotopically implanted Kras G12R/+ ;Trp53 KO mouse pancreatic tumors have a distinct immune profile in comparison to Kras G12D/+ ;Trp53 KO tumors, characterized by an influx of intratumoral CD3+ T cells and mature dendritic cells. Selective depletion of CD4+ T cells induces a rapid progression in KRASG12R, but not KRASG12D mouse tumors. RNA sequencing of KRASG12R tumor cells revealed enrichment of Type I interferon (IFN) pathways accompanied by related chemokines, CXCL9 and CXCL10 in comparison to KRASG12D tumors. Analysis of publicly available and real-world human PDAC datasets and enrichment of dendritic cells and other immune related cell types in KRASG12R tumors. Collectively, these data link the KRASG12R mutation to a unique immunogenic role. Citation Format: Andrew Wenger, Tal Baron, Erika Hissong, Rohit Chandiwani, Lukas Dow, Despina Siolas, Katherine Bacchi, Huanhuan Sun, Erika Hissong, Adrian Vega, Whitney Sisso, and Kawther Abdilleh. KRAS mutation-specific effects on the tumor immune microenvironment drive tumor progression in pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr PR012.

Construction of a combined prognostic model for pancreatic ductal adenocarcinoma based on deep learning and digital pathology images

BackgroundDeep learning has made significant advancements in the field of digital pathology, and the integration of multiple models has further improved accuracy. In this study, we aimed to construct a combined prognostic model using deep learning-extracted features from digital pathology images of pancreatic ductal adenocarcinoma (PDAC) alongside clinical predictive indicators and to explore its prognostic value.MethodsA retrospective analysis was conducted on 142 postoperative pathologically confirmed PDAC cases. These cases were divided into training (n = 114) and testing sets (n = 28) at an 8:2 ratio. Tumor whole-slide imaging features were extracted and screened to construct a pathological risk model based on a pre-trained deep learning model. Clinical and pathological data from the training set were used to select independent predictive factors for PDAC and establish a clinical risk model using LASSO, univariate, and multivariate Cox regression analyses. Based on the pathological and clinical risk models, a combined model was developed. The Harrell concordance index (C-index) was computed to assess the predictive performance of each model for PDAC survival prognosis.ResultsFor the training and testing sets, the C-index values for the clinical risk model were 0.76 and 0.75, respectively; for the pathological risk model, they were 0.82 and 0.73, respectively; and for the combined model, they were 0.86 and 0.77, respectively. The combined model exhibited appropriate calibration at 1-, 3-, and 5-year time points, as well as a superior area under the curve of the receiver operating characteristic curve and clinical net benefit compared to the single models.ConclusionsIntegrating the pathological and clinical risk models may provide a higher predictive value for survival prognosis.

HOXA9 and CD163 potentiate pancreatic ductal adenocarcinoma progression

BackgroundThe role of HOXA9 requires investigations in pancreatic ductal adenocarcinoma (PDAC) as HOXA9 inhibitors are being developed. HOXA9 might attract CD163 expressed tumor associated macrophages (TAM) and could affect PDAC prognosis. This work aims to study the expression and relevance of HOXA9 and CD163 in PDAC progression.Materials and methodsSelected 98 PDAC and 98 adjacent non tumor tissues as a control group were immunostained with HOXA9 and CD163 antibodies.ResultsPDAC displayed highly significant higher HOXA9 staining intensity, percent and H score values than control group. HOXA9 staining of PDAC cases showed significant associations with poor prognostic indicators including larger tumor size, higher grade and advanced stage. PDAC showed highly significant differences regarding CD163 macrophage-specific staining intensity, percent and H score values than control group. CD163 showed significant higher expressions with larger tumor size, higher histological grade and advanced stage group. HOXA9 staining in PDAC showed highly significant direct correlations with CD163 positive macrophages. Follow up of PDAC cases revealed that high median H score of HOXA9 and CD163 were significantly associated with worse overall survival. CD163 was an independent prognostic marker of worse survival.ConclusionsIn conclusion, HOXA9 could potentiate PDAC progression by stimulating CD163 expressed TAM attraction in tumors. HOXA9 and CD163 could participate in PDAC therapy. HOXA9 and CD163 could be predictors of worse prognosis and shorter survival in PDAC.

Abstract A032: KRAS mutations have distinct effects on the tumor immune microenvironment in pancreatic cancer

Abstract Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive malignancy with abysmal survival rates. The highly immunosuppressive microenvironment of PDAC poses a major barrier to effective therapy. KRAS mutations are near-ubiquitous in PDAC, and studies indicate clinical outcomes vary depending on the specific KRAS genotype. Given that tumor genotype can shape the immune cell composition of tumors, we examined the immune cell composition of pancreatic tumors with specific KRAS mutations, focusing on KRASG12D mutations (representing 40% of PDAC cases which have the worst prognosis) and KRASG12R mutations (which make up 20% of PDAC cases and have a better prognosis). Orthotopically implanted Kras G12R/+ ;Trp53 KO mouse pancreatic tumors have a distinct immune profile in comparison to Kras G12D/+ ;Trp53 KO tumors, characterized by an influx of intratumoral CD3+ T cells and mature dendritic cells. Selective depletion of CD4+ T cells induces a rapid progression in KRASG12R, but not KRASG12D mouse tumors. RNA sequencing of KRASG12R tumor cells revealed enrichment of Type I interferon (IFN) pathways accompanied by related chemokines, CXCL9 and CXCL10 in comparison to KRASG12D tumors. Analysis of publicly available human PDAC cohorts revealed enrichment of genes in inflammatory pathways in KRASG12R tumors. Collectively, these data link the KRASG12R mutation to an immunogenic role that is distinct from KRASG12D tumors. Citation Format: Andrew Wenger, Tal Baron, Adrian Vega-Perez, Whitney Sisso, Maria Paz Zafra, Lukas Dow, Despina Siolas. KRAS mutations have distinct effects on the tumor immune microenvironment in pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2024 Oct 18-21; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2024;12(10 Suppl):Abstract nr A032.

Assessment of Glucose and HbA1c Monitoring in a Pancreatic Cancer Surveillance Program for High-Risk Individuals.

Several studies suggest that new-onset diabetes mellitus is an early manifestation of pancreatic ductal adenocarcinoma (PDAC). Therefore, the International Cancer of the Pancreas Screening Consortium recommends glucose and hemoglobin A1c (HbA1c) monitoring in high-risk individuals (HRIs) undergoing surveillance. However, evidence that such monitoring improves PDAC detection is lacking. Our aim was to investigate the association between serum glucose and HbA1c values and the development of PDAC in HRIs undergoing surveillance. Participants were recruited from the familial pancreatic cancer surveillance cohort, which follows hereditary predisposed HRIs yearly by magnetic resonance imaging and/or endoscopic ultrasound and blood sampling. Those who underwent fasting glucose and/or HbA1c monitoring at least once were eligible candidates. Four hundred four HRIs met the inclusion criteria. During a median follow-up of 41 months (range 14-120), 9 individuals developed PDAC and 4 (without PDAC) were diagnosed with new-onset diabetes mellitus. Glucose levels ranged from 3.4 to 10.7 mmol/L (mean 5.6 ± 0.7) and HbA1c levels from 25 to 68 mmol/mol (mean 37.7 ± 4.1). The mean values did not differ significantly between PDAC cases and controls. The percentage of individuals with at least one elevated value were comparable between PDAC cases and controls for glucose (33% and 27%, P = 0.707) and HbA1c (22% and 14%, P = 0.623). No consistent glucose or HbA1c trends over time suggested a correlation with PDAC development. In this HRI surveillance cohort, measuring glucose and HbA1c values did not contribute to PDAC detection. Larger and longer-term studies are needed to determine the final role of glucose and HbA1c monitoring in PDAC surveillance.

Vascular Resection for Pancreas Cancer - 10-year Experience from a Single High Volume-center.

Combined pancreatic and vascular resections are increasingly performed for pancreatic ductal adenocarcinoma (PDAC). We evaluated the outcomes after pancreatectomy with non-vascular resection (NVR), venous resection (VR), and arterial resection (AR). Retrospective review (2011-2023) of 715 PDAC patients treated with curative-intent surgery. Associations among clinicopathological data, perioperative therapy, time to recurrence (TTR), and overall survival (OS) were evaluated. Initial staging revealed 533 resectable, 98 borderline, and 84 locally advanced PDAC cases. Pancreaticoduodenectomy was the most common procedure (n=467). NVR was performed in 351 (58.2%) patients, VR in 181 (30.0%), and AR in 70 (11.8%). The median TTR and OS did not significantly differ according to the initial staging or type of pancreas resection. Median TTR and OS were significantly shorter for VR (14.5 and 22.7mo) compared to NVR (18.6 and 30.5mo, P<0.001) and AR (20.6 and 30.9mo, P=0.004 and P=0.017). Chemotherapy or chemoradiation significantly prolonged TTR (20.1 vs. 10.2mo, P<0.001 and 25.3 vs. 16.4mo, P<0.001) and OS (31.5 vs. 17.2mo, P<0.001 and 35.5 vs. 27.5mo, P=0.030). AR was associated with higher 90-day mortality rates. In the multivariable analysis, vascular resection was not associated with OS. Perioperative therapy, pathological N0 status, and absence of perineural invasion were the key predictors of longer TTR and OS. Pancreatectomy with AR was not associated with worse oncological outcomes when controlling for perioperative therapy. However, AR was associated with higher 90-day mortality rates. Patient selection is crucial when performing AR in patients with PDAC.

Exploring Molecular Signatures in Early-Stage Pancreatic Ductal Adenocarcinoma: Implications for Patient Management and Therapeutic Strategies

Abstract Introduction/Objective Pancreatic ductal adenocarcinoma (PDAC) poses significant challenges to patient survival, predominantly due to its tendency for late-stage diagnosis and high rates of post-surgical cancer recurrence. Therefore, a comprehensive understanding of the molecular characteristics associated with the early stages of PDAC is imperative. This understanding holds the potential to improve patient treatment strategies by enabling targeted interventions and personalized therapies. Methods/Case Report Initially, RNA-seq datasets of early-stage PDAC cases (stages IA, IB, IIA, and IIB, all without distant metastasis; M0) were extracted from the GEO database. Subsequently, the datasets were analyzed in four distinct groups, and differentially expressed genes were identified within each group. Group 1 compared T1T2 cases with T3 cases (T: primary tumor), irrespective of N status (N: regional lymph nodes), while group 2 compared N0 cases with N1 cases, regardless of T status. Group 3 included comparisons between T1T2N0 cases and T3N0 cases, and group 4 compared T1T2N1 cases with T3N1 cases. Utilizing a Venn diagram, commonalities between gene expression profiles were isolated. Afterward, gene ontology and signaling pathways were determined using KEGG and Enrichr. Finally, a protein network was constructed, and the proteins were evaluated using the GEPIA and TCGA clinical databases. Results (if a Case Study enter NA) The study encompassed a total of 43 cases, with 25 (58.1%) being male and 18 (41.9%) female. The mean age of the participants was 64.4 years. In group 1, the expression levels of MUC5AC, AKAP13, and SPG7 were significantly upregulated in T3 cases. In group 2, STAB1, PDLIM1, and MTUS1 emerged as the top upregulated genes in N1 cases. Group 3 exhibited notable upregulation of CCNL2, CEACAM6, and TSPAN3 in T3N0 cases, while group 4 demonstrated marked upregulation of LTBR, AKAP12, and BOP1 in T3N1 cases. These genes exhibited diverse functions in PDAC progression. They contributed to the regulation of gene expression and cell cycle progression, modulating cell proliferation, inhibiting tumor growth, regulating cell signaling, and were involved in cytoskeletal organization. Conclusion The upregulated genes in cases with the T3 and/or N1 staging components may shed light on the potential mechanisms of progression from stage IA/B to stage IIA/B in PDAC cases. Furthermore, the identified genetic alterations may hold potential therapeutic and prognostic applications for future use in the early stages of PDAC.

Racial Inequities in Receiving Neoadjuvant Treatment in Patients With Pancreatic Cancer Are Associated With Worse Outcomes in Louisiana.

Pancreatic ductal adenocarcinoma (PDAC) is the third leading cause of cancer-related deaths. In recent years, the approach to managing this malignancy has evolved toward embracing neoadjuvant treatment (NAT), backed by studies reporting its survival benefit. This study aimed to identify factors that contribute to disparities in NAT utilization and their impact on outcomes in patients with PDAC who underwent resection in Louisiana. Data on diagnosed PDAC cases were obtained from the Louisiana Tumor Registry between 2000 and 2020. We conducted multivariable logistic regression to adjust for potential confounding factors in assessing the covariate relationships with NAT use. Multivariate Cox regression analysis was performed to determine which factors were associated with survival. Chained multiple imputation was performed on covariates with missing data in multivariable regressions. The study encompassed 2121 patients who underwent resection for PDAC. Upon controlling for potential confounding variables, Black patients were on average 5.7% less likely to receive NAT than their White counterparts (ATE = 5.7, aOR= 0.56, 95% CI = 0.40-0.80, p = 0.001). After adjustment for confounding factors, there was a significant decrease in the risk of overall death for patients who received NAT (aHR = 0.82, 95% CI = 0.71-0.94, p = 0.006). There was no significant interaction between race and NAT for the risk of death. Black patients with PDAC were less likely to receive NAT before resection in Louisiana. Overall survival improved in patients who underwent NAT. These differences were independent of insurance status and poverty zip codes, and future investigations should identify modifiable barriers to access and receipt of NAT in patients with PDAC.

68Ga-DOTATATE Uptake in Pancreatic Ductal Adenocarcinoma.

We present a case of pancreatic ductal adenocarcinoma showing increased 68Ga-DOTATATE uptake mimicking neuroendocrine tumor on PET/CT. Immunohistochemical analyses of the resected tumor showed the tumor cells were negative for somatostatin receptor subtype 2. The nonneoplastic islets scattered throughout the tumor were positive for somatostatin receptor subtype 2, which may be responsible for the increased 68Ga-DOTATATE uptake. This case indicates that pancreatic ductal adenocarcinoma should be included in the differential diagnosis of the pancreatic lesions showing increased 68Ga-DOTATATE uptake.

KRAS-Driven Tumorigenesis and KRAS-Driven Therapy in Pancreatic Adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) is associated with significant morbidity and mortality and is projected to be the second leading cause of cancer-related deaths by 2030. Mutations in KRAS are found in the vast majority of PDAC cases and plays an important role in the development of the disease. KRAS drives tumor cell proliferation and survival through activating the MAPK pathway to drive cell cycle progression and to lead to MYC-driven cellular programs. Moreover, activated KRAS promotes a protumorigenic microenvironment through forming a desmoplastic stroma and by impairing antitumor immunity. Secretion of granulocyte-macrophage colony-stimulating factor and recruitment of myeloid-derived suppressor cells and protumorigenic macrophages results in an immunosuppressive environment while secretion of secrete sonic hedgehog and TGFβ drive fibroblastic features characteristic of PDAC. Recent development of several small molecules to directly target KRAS marks an important milestone in precision medicine. Many molecules show promise in preclinical models of PDAC and in early phase clinical trials. In this review, we discuss the underlying cell intrinsic and extrinsic roles of KRAS in PDAC tumorigenesis, the pharmacologic development of KRAS inhibition, and therapeutic strategies to target KRAS in PDAC.

Sulindac (K-80003) with nab-paclitaxel and gemcitabine overcomes drug-resistant pancreatic cancer

The Nab-paclitaxel combined with gemcitabine (AG) regimen is the main chemotherapy regimen for pancreatic cancer, but drug resistance often occurs. Currently, the ability to promote sensitization in drug-resistant cases is an important clinical issue, and the strategy of repurposing conventional drugs is a promising strategy. This study aimed to identify a classic drug that targets chemotherapy resistance’s core signaling pathways and combine it with the AG regimen to enhance chemosensitivity. We also aimed to find reliable predictive biomarkers of drug combination sensitivity. Using RNA sequencing, we found that abnormal PI3K/Akt pathway activation plays a central role in mediating resistance to the AG regimen. Subsequently, through internal and external verification of randomly selected AG-resistant patient-derived organoid (PDO) and PDO xenograft models, we discovered for the first time that the classic anti-inflammatory drug sulindac K-80003, an inhibitor of the PI3K/Akt pathway that we focused on, promoted sensitization in half (14/28) of AG-resistant pancreatic ductal adenocarcinoma cases. Through RNA-sequencing, multiplex immunofluorescent staining, and immunohistochemistry experiments, we identified cFAM124A as a novel biomarker through which sulindac K-80003 promotes AG sensitization. Its role as a sensitization marker is explained via the following mechanism: cFAM124A enhances both the mRNA expression of cathepsin L and the activity of the cathepsin L enzyme. This dual effect stimulates the cleavage of RXRα, leading to large amounts of truncated RXRα, which serves as a direct target of K-80003. Consequently, this process results in the pathological activation of the PI3K/Akt pathway. In summary, our study provides a new treatment strategy and novel biological target for patients with drug-resistant pancreatic cancer.

Polymorphisms within autophagy-related genes as susceptibility biomarkers for pancreatic cancer: A meta-analysis of three large European cohorts and functional characterization.

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers with patients having unresectable or metastatic disease at diagnosis, with poor prognosis and very short survival. Given that genetic variation within autophagy-related genes influences autophagic flux and susceptibility to solid cancers, we decided to investigate whether 55,583 single nucleotide polymorphisms (SNPs) within 234 autophagy-related genes could influence the risk of developing PDAC in three large independent cohorts of European ancestry including 12,754 PDAC cases and 324,926 controls. The meta-analysis of these populations identified, for the first time, the association of the BIDrs9604789 variant with an increased risk of developing the disease (ORMeta = 1.31, p = 9.67 × 10-6). We also confirmed the association of TP63rs1515496 and TP63rs35389543 variants with PDAC risk (OR = 0.89, p = 6.27 × 10-8 and OR = 1.16, p = 2.74 × 10-5). Although it is known that BID induces autophagy and TP63 promotes cell growth, cell motility and invasion, we also found that carriers of the TP63rs1515496G allele had increased numbers of FOXP3+ Helios+ T regulatory cells and CD45RA+ T regulatory cells (p = 7.67 × 10-4 and p = 1.56 × 10-3), but also decreased levels of CD4+ T regulatory cells (p = 7.86 × 10-4). These results were in agreement with research suggesting that the TP63rs1515496 variant alters binding sites for FOXA1 and CTCF, which are transcription factors involved in modulating specific subsets of regulatory T cells. In conclusion, this study identifies BID as new susceptibility locus for PDAC and confirms previous studies suggesting that the TP63 gene is involved in the development of PDAC. This study also suggests new pathogenic mechanisms of the TP63 locus in PDAC.

Abstract B025: Surveillance outcome in individuals at high risk of pancreatic cancer

Abstract INTRODUCTION: Pancreatic ductal adenocarcinoma (PDAC) has a poor 5-year survival rate. PDAC surveillance is recommended in high-risk individuals (HRIs) with strong PDAC family history or a pathogenic germline variant (PGV) in a PDAC susceptibility gene. We aimed to explore a potential correlation between genetic status, extent of family history, pancreatic findings, and surveillance implications in heterogeneous PDAC HRIs. METHODS: from January 2015 up to date, a total of 340 HRIs from 291 families visited our pancreatic cancer high-risk clinic. Surveillance included annual clinic visits, EUS/MRI imaging, genetic and laboratory blood testing. Participants completed a questionnaire that included personal and familial medical history, dietary habits, daily activities with emphasis on smoking habits, alcohol use, and physical activity. RESULTS: Our cohort was divided into 3 groups: familial pancreatic cancer that include individuals with family history of 2 or more first degree family (FDR) with PDAC (FPC; 96 individuals), familial non-FPC, families with at least 2 biological relatives with PDAC and not meeting FPC criteria, (119 individuals), and hereditary pancreatic cancer (PC), individuals with PGV in a PC susceptibility gene and a family member with PDAC carrying the same PGV (124 individuals). The cohort average age at first visit was 54 years with 44% male and 56% female ratio. Seventy percent of the cohort was of Jewish Ashkenazi decent. Genetic testing was performed in several steps, first BRCA1/2 founder mutations was performed in all individuals followed by genetic panels and whole exome sequencing (WES). PGVs were detected in 36.4% of all families. There was no significant difference in the genetic finding between the FPC and non-FPC groups (11% and 9.6% respectively). Of the study cohort 35% were screened by EUS and 8% by MRI/MRCP. Pancreatic lesions detected included 11 cases of new PDAC (3.2%), 69 cystic lesions (20.3%), 43 cases early chronic pancreatitis (12.6%) and 11 cases of main pancreatic duct dilation (3.2%). To better understand the risk of PDAC development in HRIs we recently added a novel cell-free chromatin blood test for early cancer detection (in collaboration with SENSEERA, Israel) and compared it to EUS imaging results. The test provides multidimensional epigenetic information that sheds light on the identity and the transcriptional state of the cells that are dying in the body of the patient. Our preliminary results show nice separation between the healthy control and PC groups. PC HRIs show slight increase in score compared to the general population while individuals with worrisome features show substantial increase compared to HRIs with no EUS findings. DISCUSSION: Surveillance seems effective for detection of early-stage PDAC and precursor lesions. However, screening strategy can be improved by adding newer modalities like chromatin-based tests that might help to further define the risk of cancer development in HRIs. Citation Format: Merav Ben Yehoyada, Erez Scapa, Oren Shibolet, Guy Rosner. Surveillance outcome in individuals at high risk of pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr B025.

Abstract C010: Single-cell profiling unleashes KRAS-driven redrafting of the tumor microenvironment before cancer onset

Abstract Pancreatic cancer is a highly lethal and aggressive disease, commonly characterized by a unique tumor microenvironment, where mutant KRAS signaling plays a pivotal role in its pathophysiology. To deepen our understanding of KRAS-dependent signaling in earliest tumor development, oncogenic KRAS (KRASG12D) expression was induced in human stem cell-derived pancreatic ductal-like organoids (PDLOs), followed by time-resolved single-cell RNA and bulk ATAC sequencing. This unique precancerous state model facilitated a comprehensive characterization of early oncogenic events at cellular resolution. Furthermore, a machine learning approach was applied to accurately predict KRAS-dependent cell identities. Within seven days, mutated KRAS triggers distinct gene signature programs related to extracellular matrix remodeling and inflammation. Although derived from dysplastic yet non-cancerous states, these gene signatures negatively correlated with overall survival in PDAC (pancreatic ductal adenocarcinoma) patients. The KRAS-dependent signatures retrieved with the machine learning approach allowed the grouping of 24 published PDAC cases, showing differences in niche composition and communication patterns. Various co-culture systems demonstrated that KRASG12D-expressing PDLOs could activate pancreatic stellate cells, inducing a cancer- associated fibroblast (CAF)-like state. Simultaneously, these KRAS-activated organoids were protected from T cell infiltration in vitro. Furthermore, in silico approaches were employed to reconstruct a virtual pancreatic cancer space, demonstrating that our PDLOs transcriptionally bridge healthy and malignant ductal states. This also revealed potential KRAS-driven pathways mediating CAF activation and T cell shielding preceding cancer onset. In summary, our human PDLO model enables us to explore the transition from normal to cancerous states, addressing gaps in our understanding of tumor development and tumor niche preparation. Citation Format: Chantal Allgoewer, Markus Breunig, Meike Hohwieler, Medhanie Mulaw, Alexander Kleger. Single-cell profiling unleashes KRAS-driven redrafting of the tumor microenvironment before cancer onset [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr C010.

Abstract C030: Evolutionary and epistatic analyses reveal genic interactions with KRAS during malignant progression of pancreatic ductal adenocarcinoma

Abstract Pancreatic ductal adenocarcinoma (PDAC) patients face poor prognoses attributable to delayed disease detection, resulting in distant metastases and thereby reducing treatment efficacy. The challenge of detecting PDAC lesions during early stages emanates from an inauspicious trifecta of clinical factors: early-stage malignancies are often asymptomatic, existing biomarkers are insufficiently sensitive, and the physical location of the pancreas stymies reliable screening. A promising strategy towards improving outcomes is the resection of high-risk, pre-malignant lesions deemed likely to progress into carcinomas. Intraductal papillary mucinous neoplasms (IPMNs) are both large enough to be detected during abdominal imaging and can originate PDAC lesions. However, a patient may have many IPMN cysts, many of which will never progress. As pancreatic resection carries with it a high risk of morbidity, distinguishing the the evolutionary trajectories of IPMNs that will and will not progress could inform treatment strategies. Additionally, these trajectories may serve as disruptable targets to manage pre- neoplastic lesions, preventing their progression to PDAC. The vast majority PDAC cases contain mutations in KRAS and GNAS with secondary driver mutations in TP53, SMAD4, CDKN2A, and RNF43. Recent work has compared the frequency of these mutations in PDAC with low-grade and high-grade IPMN lesions, finding that they more common in high than low- grade lesions. Interestingly, unlike KRAS or GNAS, KLF4 mutations are prevalent in low-grade IPMNs, rare in high-grade IPMNs, and almost never observed in full-fledged carcinoma, suggesting distinct evolutionary trajectories possibly mediated by epistatic interactions between KLF4 and KRAS. However, the prevalence of a mutation is not dispositive as to its importance in tumorgenesis. Mutations in TTN, for instance, are frequently observed in PDAC and other cancers, but are widely considered to play a modest role, if any, in these cancers. To understand the contribution of a mutation to the evolution of cancer, we must instead deconvolve selection from baseline mutation rate across genomic sites and among patients to distinguish truly oncogenic mutations from mutations that occur frequently merely due to high underlying mutational rates. Here, we quantify the evolutionary and epistatic interplay between KRAS, KLF4, and other frequent mutations in IPMNs and PDAC during malignant transition. First, we report the cancer effect sizes of single-nucleotide variants in IPMNs at varying dysplastic stages. Then, we infer the synergistic and antagonistic interactions between driver mutations, providing insight into the order in which driver mutations occur. We then corroborate this epistasis-inferred ordering with the ordering of mutations recovered from ancestral state reconstruction derived from time-calibrated phylogenies. Lastly, we probe the mutational processes most responsible for conferring highly oncogenic mutations in IPMNs and PDACs to identify potentially actionable or preventable pathways of disease progression. Metabolism Citation Format: Nic Fisk, Derek Song, Margaret Moore, Cole G Jensen, Vincent L. Cannataro, Mofeed Nagib, Jeffrey D Mandell, Luisa Escobar-Hoyos, John W Kunstman, Jeffrey P Townsend. Evolutionary and epistatic analyses reveal genic interactions with KRAS during malignant progression of pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr C030.

Abstract C012: Overcoming Cell Subtype-Specific Adaptive Resistance to KRAS G12D Inhibition in KRAS G12D-Mutant Pancreatic Cancer

Abstract Background: Pancreatic ductal adenocarcinoma (PDAC) has a 5-year survival rate of only 12%, with limited treatment options. Oncogenic KRAS mutations drive PDAC tumor progression, which occur in the majority of PDAC tumors. KRAS G12D is the most common KRAS mutation, found in 36% of PDAC cases, which is associated with the worst clinical outcomes. Mutant-selective KRAS G12D inhibitors (KRASi G12D), such as MRTX1133, have recently demonstrated initial responses in KRAS G12D-mutant preclinical models. However, mechanisms of adaptive resistance to KRAS G12D inhibition are largely under-investigated and novel therapeutic strategies to overcome drug resistance are urgently needed. Results: Adaptive RAS signaling reactivation was found to dampen KRAS G12D inhibition in a library of KRAS G12D PDAC cell lines, thereby minimizing drug efficacy. Quantitative downstream analyses of drug combination screening using a KRAS G12D cell line library further identified this adaption to KRAS inhibition was cell subtype specific. Fibroblast growth factor receptor (FGFRs) drove adaptive RAS reactivation specifically in mesenchymal PDAC cells, which are aggressive, and intrinsically resistant to KRASi. In contrast, epithelial growth factor receptor (EGFR) reactivated RAS G12D signaling in epithelial cells, which are sensitive to KRASi G12D. Genetic and pharmacological inhibition of FGFR1 or FGFR2 improved drug efficacy by decreasing FGFR-mediated RAS reactivation specifically in mesenchymal PDAC lines. Pharmacological blockade of EGFR enhanced drug efficacy by inhibiting EGFR-mediated RAS reactivation specifically in epithelial PDAC lines. Furthermore, low-concentration of a novel pan- RAS inhibitor, which inhibits both wild-type and mutant RAS, completely abrogated MAPK signaling and significantly improved efficacy, when combined with KRASi G12D, suggesting a pro-survival dependency on wild-type RAS as a compensatory mechanism in response to KRAS G12D inhibition. Conclusion: Upstream RTK-mediated adaptive RAS signaling re-activation in response to KRAS inhibition in PDAC is cell subtype specific. Complete inhibition of RAS signaling by overcoming adaptive RAS rebound improves efficacy of KRASi G12D. Citation Format: Qingxiang (Nick) Lin, Alvin Morales, Haley Barnes, Ryan Bruce Corcoran. Overcoming Cell Subtype-Specific Adaptive Resistance to KRAS G12D Inhibition in KRAS G12D-Mutant Pancreatic Cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr C012.

Abstract C027: Efficacy advantages of a novel pan-RAS inhibitor, ADT-1004, over mutant- specific KRAS inhibitors for suppressing pancreatic tumor growth in murine models

Abstract Background/Objective: Prognosis remains grim for localized or metastasized pancreatic ductal adenocarcinoma (PDAC) with 5-year survival rates of 3-16%. More than 90% of PDAC cases harbor KRAS mutations. KRASG12C inhibitors recently developed have limited use for PDAC because only 3% of cases express this mutation. We developed a novel pan-RAS inhibitor, ADT-1004 and evaluated antitumor activity in tumor models established from murine or human PDAC cell lines or patient-derived xenografts (PDX). ADT-1004 is an orally bioavailable prodrug of ADT-007, a highly potent and selective pan-RAS inhibitor (doi.org/10.1101/2023.05.17.541233). Methods: Murine PDAC cells harboring the KRASG12D mutation (KPC-Luc or 2838C3-Luc) were orthotopically implanted into the pancreas of C57BL/6J mice. Four PDX PDAC tumors harboring KRAS mutations were implanted orthotopically in NSG mice. To assess potential to overcome RAS inhibitor resistance, parental KRASG12C MIA PaCa-2 PDAC cells and a resistant derivative of MIA PaCa-2 cells were implanted subcutaneously. To assess selectivity, mice were implanted with RASWT BxPC-3 cells SC. Mice were treated orally with ADT-1004 (40mg/kg) 5x/week for 4 weeks. Sotorasib and adagrasib KRASG12C inhibitors were administered at the same dose, route, and schedule as ADT-1004. Results: ADT-007 potently and selectively inhibited the growth of human and mouse PDAC cell lines in vitro. For example, the IC50 value of ADT-007 for KRASG12C MIA PaCa-2 PDAC cells was 2 nM compared to 2500 nM for RASWT BxPC-3 PDAC cells. Growth inhibition by ADT-007 was dependent on activated RAS and associated with reduced GTP-RAS levels and MAPK/AKT signaling. ADT-1004 was well tolerated in mice at doses up to 175 mg/kg bid orally with sustained plasma levels of ADT-007 exceeding growth IC50 values. ADT-1004 displayed robust antitumor activity in mouse tumor models using human- or mouse-derived PDAC cell lines with G12D, G12V, G12C, or G13Q KRAS mutations, causing selective inhibitory effects on ERK phosphorylation in tumors but not in normal tissues. ADT-1004 also inhibited growth of KRASG12C mutant MIA PaCa-2 tumors to a comparable extent as sotorasib and adagrasib. Sotorasib and adagrasib were ineffective against xenografted tumors of resistant cells derived from MIA PaCa-2 cells, while ADT-1004 strongly inhibited tumor growth. Target selectivity of ADT-1004 was confirmed in vivo, as ADT-1004 did not affect the growth of RASWT BxPC-3 tumors. Conclusions: ADT-1004 inhibited tumor growth of KRAS mutant PDAC tumors by blocking activated RAS to disrupt downstream MAPK/AKT signaling. Side-by-side comparisons reveal antitumor efficacy advantages of ADT-1004 over mutant-specific KRAS inhibitors. These results highlight the promise of ADT-1004 for treatment of PDAC and other RAS-driven cancers by addressing the complex genetic landscape of many cancers and limitations from resistance to mutant specific KRAS inhibitions. Citation Format: Dhana Sekhar Reddy Bandi, Ganji P Nagaraju, Jeremy B Foote, Adam B Keeton, Xi Chen, Kristy L Berry, Yulia Y Maxuitenko, Upender Manne, Donald J Buchsbaum, Gary A Piazza, Bassel F El-Rayes. Efficacy advantages of a novel pan-RAS inhibitor, ADT-1004, over mutant- specific KRAS inhibitors for suppressing pancreatic tumor growth in murine models [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr C027.

Abstract PR-11: Altered mRNA splicing mimics chromosome loss and drives pancreatic cancer

Abstract Aiming to identify novel driver mutations that cause pancreatic ductal adenocarcinoma (PDAC), besides p53 mutations, we performed a genetic interaction analysis based on the concept of mutually exclusive mutations, which suggests that mutations exclusive to one another function within the same pathway. Using our unbiased quantitative methods to evaluate the effects of somatic mutations on cancer, we analyzed 3900 human PDAC cases to prioritize mutations among hundreds that appear at low frequencies (5-10%) and are mutually exclusive with p53 mutations. Mutations in RNA splicing factors SF3B1 and RBM10 (∼15% of cases) were among the most significant and mutually exclusive to mutant p53. Thus, we hypothesized that aberrant RNA splicing promoted by mutant SF3B1K700E and truncated RBM10 (RBM10 loss) lead to tumorigenesis and therapy resistance. Through the generation of engineered mouse models to co-express KrasG12D with either Sf3b1K700E or Rbm10 loss in pancreatic cells, we observed that mice harboring KrasG12D and Sf3b1 K700E or Rbm10 loss—like mutant p53—caused PDAC in mice. To identify the RNA splicing mechanism that leads to PDAC formation, we performed deep RNA sequencing and unbiased transcriptome-wide splicing analyses in isolated PDAC cells bearing wild-type SF3B1K700E and RBM10 loss derived from murine and patient PDACs. We established that SF3B1 and RBM10 mutations induce wide splicing changes, primarily affecting exon selection. Since two-thirds of these changes may lead to nonsense-mediated decay (NMD), a mechanism that eliminates aberrant mRNA, we tested whether these changes could trigger this response. Using cycloheximide-dependent NMD inhibition, we confirmed that these mutations cause NMD, resulting in post-transcriptional gene expression loss in mouse chromosomes 2, 7, 11, and 17, also conserved in human models. Intriguingly, recent studies in Nature (2022) have shown that in murine PDACs with loss-of-function p53 mutations, genetic loss of chromosomes 11 and 7 is necessary for PDAC development. These results suggest that mutations in SF3B1 and RBM10, and p53 loss, affect the same chromosomal loci, albeit through different mechanisms, to promote PDAC, supporting the mutual exclusivity findings from patient samples. To determine a personalized therapy for patients with mutant splicing-factor tumors, we found that PDACs with these mutations are more sensitive to Gemcitabine, a component of a PDAC standard-of-care therapy. Moreover, these mutations sensitize cells to small-molecule splicing inhibitor H3B-8800— currently in phase 2 trial for hematologic malignancies. Lastly, we found that combining Gemcitabine and H3B-8800 synergizes to kill mutant splicing cells selectively in vitro and in vivo. We are starting a phase 2 trial for Gemcitabine/Abraxane with escalating doses of H3B-8800 for tumors that have either SF3B1K700E, RBM10 loss, or neomorphic p53, all of which have aberrant RNA splicing. This work has determined novel drivers and mechanisms of PDAC development and a precision therapeutic strategy for treating PDAC patients. Citation Format: Natasha Pinto Medici, Diana Martinez-Saucedo, Danny Lee, Tianyi Chu, Robert Tseng, Vincent Cannataro, Jeffrey Townsend, Christine Iacobuzio-Donahue, Marie Robert, Omar Abdel-Wahab, Steven D. Leach, Luisa Escobar-Hoyos. Altered mRNA splicing mimics chromosome loss and drives pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr PR-11.

The impact of HRD mutation on survival in patients with KRAS-mutated advanced pancreatic cancer: A real-world database study.

221 Background: Advanced pancreatic ductal adenocarcinoma (PDAC) is associated with a poor prognosis. Prior studies indicate that homologous repair deficient (HRD+ve) PDAC patients (pts) have improved survival and greater response to platinum agents, but the optimal treatment for these population is still unclear. Here, we evaluate the survival impact of HRD mutations in KRAS-mutated PDAC, which represent 90% of cases, in a real-world setting. Methods: We retrospectively reviewed all pts diagnosed with KRAS-mutated PDAC from Jun 2019 to Dec 2021, who were registered in the Center for Cancer Genomics and Advanced Therapeutics (C-CAT), the cancer registry with comprehensive genomic profiling (CGP) data. Pts were stratified with the presence or absence of HRD mutations identified through Foundation One, including ATM, ATR, BRCA1, BRCA2, BRIP1, CHEK2, FANCA, PALB2, and RAD51. We analyzed the prevalence of co-alterations and the impact of HRD status on survival. Pts with a history of systemic therapy for curative intent were excluded from the survival analysis. Results: In 2251 PDAC cases (HRD+ve 232pts, HRD-ve 2019pts) enrolled, we found that HRD+ve PDAC had a significantly lower incidence of TP53 mutation (p&lt;0.001), CDKN2A mutation (p&lt;0.046), and CDKN2A loss (p&lt;0.046). Survival analysis was performed in 823 pts (HRD+ve 92pts, HRD-ve 731pts). HRD+ve pts had significantly longer overall survival (OS, 28.8m vs 23.5m, P=0.030). In the first line setting, HRD+ve pts had exhibited a markedly extended time-to-treatment failure (TTF; [HRD+ve, 19pts vs. HRD-ve, 177pts]; 7.6m vs. 5.4m; p=0.026) and OS ([HRD+ve, 30pts vs. HRD-ve, 239pts]; 28.8m vs. 23.5m; p=0.019) when treated with mFOLFIRINOX (mFFX), but not when treated with gemcitabine plus nab-paclitaxel (GA; [HRD+ve, 34pts vs. HRD-ve 276pts]; OS, 29.3m vs 26.3m; p=0.34; TTF, 5.2m vs. 5.2m; p=0.80). In the second line setting, there were no differences in TTF between HRD+ve and HRD-ve irrespective of these regimens. Among HRD+ve PDAC pts, pts who having received mFFX tend to have better survival compared to those who did not (46pts vs. 46pts; OS, 31.7m vs 26.3m; p=0.09). Conclusions: Our analysis has identified a unique profile in HRD+ve PDAC, underscoring the importance of platinum-based chemotherapy in the initial treatment to enhance survival, which highlights the practical clinical benefits of routine CGP for pts with KRAS-mutated PDAC.

A potent and selective pan-RAS inhibitor, ADT-1004, targeting complex KRAS mutations for pancreatic cancer.

90 Background: Pancreatic ductal adenocarcinoma (PDAC) is a challenging cancer with a 5-year survival rate of under 12%. More than 90% of PDAC cases involve KRAS mutations. KRASG12C inhibitors recently developed have limited use because only 3% of PDAC express this mutation, highlighting the urgent need for pan-RAS inhibitors to address the complex mutation landscape in PDAC while avoiding resistance mechanisms. We synthesized and evaluated a novel pan-RAS inhibitor, ADT-1004, in mouse tumor models transplanted with mouse PDAC cell lines or patient-derived xenografts. ADT-1004 is an orally bioavailable prodrug of ADT-007, a highly potent and selective pan-RAS inhibitor (doi.org/10.1101/2023.05.17.541233). Methods: Human and mouse PDAC cell lines were utilized to evaluate in vitro growth inhibitory potency and selectivity of ADT-007. For in vivo experiments, KPC-Luc (1 × 105) and 2838C3-Luc (1.5 × 105) PDAC cells harboring the KRASG12D mutation were injected into the pancreas of C57BL/6J mice. After one week, the mice were randomly divided into treatment groups (n = 7 per group) and received oral ADT-1004 at a dose of 40mg/kg body weight five times a week for 4 weeks. Tumor burden was assessed weekly by monitoring bioluminescence signals using the IVIS Xenogen imaging system. Four patient-derived xenografts from PDAC patients with KRASG12C, KRASG12D, KRASG12V, KRASG13Q mutations were subcutaneously implanted in NSG mice by a small incision in the right flank. A week later, when the tumors reached a size of 100mm3 mice were randomized (n=7 per group) and treated orally with 40mg/kg of ADT-1004 five times a week for 6 weeks. Body weight and tumor size were measured twice weekly. Results: ADT-007 potently and selectively inhibited the growth of human and mouse PDAC cell lines. For example, the IC50 value pf ADT-007 for KRASG12C MIA PaCA-2 PDAC cells was as low as 2 nM compared to 2500 nM for RASWT BxPC3 PDAC cells. Growth inhibition was dependent on activated RAS and associated with reduced GTP-RAS levels and MAPK/AKT signaling. ADT-1004 was well tolerated in mice at a dose up to 175 mg/kg bid orally with sustained plasma levels of ADT-007 far exceeding growth IC50 values. When administered orally at 40 mg/kg body weight, ADT-1004 displayed robust antitumor activity in mouse tumor models using patient or mouse derived PDAC cell lines with G12D, G12V, G12C, or G13Q KRAS mutations, causing significant inhibitory effects on ERK phosphorylation. Conclusions: ADT-1004 inhibited tumor growth of KRAS mutant PDA tumors by targeting activated RAS to disrupt downstream MAPK/AKT signaling. The results highlight the promise of ADT-1004 as a novel pan-RAS inhibitor and open new strategies for addressing the complex genetic landscape of PDAC and other RAS driven cancers.