Strategy For Pancreatic Ductal Adenocarcinoma Research Articles

Fibrinogen to pre-albumin ratio is an independent prognostic index for patients with pancreatic ductal adenocarcinoma after radical resection

BackgroundThis study aims to elucidate the significance of the preoperative fibrinogen to pre-albumin ratio (FPR) in predicting the prognosis of pancreatic ductal adenocarcinoma (PDAC), a correlation not extensively explored previously.MethodsA cohort of 563 patients diagnosed with PDAC and subjected to radical surgical resection was examined. We meticulously documented a range of inflammatory markers, clinical-pathological features, and oncological outcomes. The prognostic value of preoperative FPR was assessed using Kaplan–Meier survival analysis and Cox proportional hazards regression modeling. Furthermore, the predictive accuracy of FPR was evaluated through time-dependent receiver operating characteristic (ROC) curves and decision curve analyses (DCA).ResultsThe determined optimal threshold for FPR was 14.77, which facilitated the stratification of patients into groups with low and high FPR levels. Notably, patients in the high FPR cohort exhibited significantly reduced recurrence-free survival (RFS) and overall survival (OS) rates compared to their low FPR counterparts. Multivariate Cox regression analysis underscored FPR as an independent prognostic indicator for both RFS and OS. In comparison to the neutrophil-to-lymphocyte ratio (NLR), FPR demonstrated superior prognostic accuracy and clinical utility.ConclusionThe preoperative fibrinogen to pre-albumin ratio serves as an independent prognostic marker for RFS and OS among PDAC patients undergoing radical resection. Our findings suggest that FPR could be a valuable addition to the current prognostic models, potentially guiding therapeutic decision-making and patient management strategies in PDAC.

Abstract A011: Enhanced Radiosensitivity of Pancreatic Cancer Achieved through Inhibition of Cyclin-Dependent Kinase 1

Abstract Introduction: One of the major challenges in treating Pancreatic Ductal Adenocarcinoma (PDAC) is overcoming radioresistance. This study investigates the targeting of Cyclin-dependent kinase-1 (CDK1) through both genetic and pharmaceutical inhibition as a strategy to increase the radiosensitivity of PDAC cells. Methods: We conducted mass spectrometry and phosphoproteomics analyses to compare engineered radiation-resistant PDAC cell lines (MIA PaCa-2 and PANC-1) with their parental controls. Additionally, we examined the TCGA PDAC database to correlate clinical outcomes, such as overall survival (OS), with CDK1 mRNA expression levels in PDAC patients. Furthermore, we developed a microRNA-based TET-on inducible shRNA to specifically inhibit CDK1 expression in PDAC cell lines. In an orthotopic PDAC model, we evaluated the radiation sensitivity of PDAC tumors with or without doxycycline treatment. We also employed a selective CDK1 inhibitor, RO-3306, to target CDK1 activation, followed by in vitro experiments using immunoblotting, immunocytochemistry, and clonogenic assays. Results: Our phosphoproteomics analysis revealed a significant increase in phospho-CDK1 (Tyr15) levels in the radiation-resistant cell lines. High CDK1 expression was associated with poorer OS in PDAC patients. Additionally, we observed heightened CDK1 phosphorylation at the threonine tyrosine 14 (Tyr14) residue following radiation exposure. Through our in vivo and in vitro experiments, we demonstrated that CDK1 inhibition, in conjunction with radiation therapy, delayed tumor growth and enhanced radiosensitivity in PDAC cells. Treatment with RO-3306 caused a substantial shift of cells into the G2/M phase and disrupted DNA repair post-radiation exposure, further enhancing radiosensitivity. Conclusion: Our findings underscore the critical role of CDK1 in PDAC radioresistance. Targeting CDK1 in combination with radiotherapy shows promise for future exploration as a potential treatment strategy in PDAC. Citation Format: Stetson Van Matre, Saaimatul Huq, Lokesh Akana, Oscar Zuniga, Henrique Rodrigues, Adam Wolfe. Enhanced Radiosensitivity of Pancreatic Cancer Achieved through Inhibition of Cyclin-Dependent Kinase 1 [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 A011.

Abstract C032: De novo pyrimidine biosynthesis inhibition synergizes with BCL-XL targeting in pancreatic cancer

Abstract Oncogenic KRAS, the genetic driver of 90% of PDAC, induces a metabolic rewiring characterized, in part, by dependency on de novo pyrimidine biosynthesis. Dihydroorotate dehydrogenase (DHODH) is the enzymatic ‘chokepoint’ of the de novo pyrimidine biosynthesis pathway and an in vivo metabolic liability in pancreatic ductal adenocarcinoma (PDAC). Targeting enzymes in the de novo pyrimidine synthesis pathway such as dihydroorotate dehydrogenase (DHODH) with clinically available inhibitor brequinar (BQ) starved the tumor of nucleotide synthesis and restrained growth of PDAC cells in vitro. However, therapeutic resistance limited BQ long-term effects in PDAC xenografts, which suggests compensatory pathways and that combinatorial strategies are required for enhanced efficacy. Here, we integrated a mass spectrometry (MS)-based quantitative temporal proteomics workflow, LC/MS- based metabolomics and in vitro and in vivo drug-anchored CRISPR/Cas9 genetic screens to identify compensatory pathways to DHODH inhibition (DHODHi) and targets for combination strategies. We demonstrate that DHODHi alters the apoptotic regulatory proteome thereby enhancing sensitivity to inhibitors of the anti-apoptotic BCL2L1 (BCL-XL) protein. Combinatorial regimens with DHODH and BCL-XL inhibition synergistically induce apoptosis in PDAC cell lines and patient-derived PDAC organoids. In vivo DHODH inhibition with Brequinar and BCL-XL degradation with DT2216, a proteolysis targeting chimera (PROTAC), significantly inhibits the growth of PDAC tumors. Our data defines mechanisms of adaptation to DHODH inhibition and identifies a combination therapy strategy in PDAC. Citation Format: huan zhang, Qijia yu, Naiara Santana-Codina, Clara Poupault, Claudia Campos, Xingping Qin, Aparna Padhye, Nicole Sindoni, Miljan Kuljanin, Junning Wang, Matthew J. Dorman, Andrew J. Aguirre, Stephanie K. Dougan, Kristopher A. Sarosiek, Joseph D. Mancias. De novo pyrimidine biosynthesis inhibition synergizes with BCL-XL targeting in 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 C032.

Abstract IA-01: Targeting autophagy in pancreatic cancer

Abstract Pancreatic ductal adenocarcinoma (PDAC) is one of the most vexing problems in cancer with 5-year overall survival rates of 13%, thus there is a need for new therapeutic targets. PDAC have a distinct dependence on autophagy, a conserved eukaryotic catabolic pathway that serves to degrade proteins, other macromolecules, and organelles via the lysosome as part of a recycling process to maintain cellular homeostasis during basal and stress conditions. The unique importance of autophagy in PDAC suggests that there may be a subset of proteins that are specifically targeted by autophagy for degradation, which would promote proliferation and survival, and that these may represent new targets for therapy. Using a quantitative PDAC cellular autophagosomal proteomics approach, we identified NCOA4 as the autophagy receptor for ferritin, the cellular iron storage complex, and demonstrated that ferritin autophagy (ferritinophagy) is a highly regulated process and plays a central role in the larger context of cellular and organismal iron homeostasis. Given the reliance of PDAC, on both high levels of autophagy as well as iron, we studied the role of NCOA4 and ferritinophagy in PDAC thereby identifying NCOA4-mediated ferritinophagy and more broadly lysosomal iron metabolism as a PDAC dependency and therapeutic target. We recently determined the cryo-EM structure of the NCOA4-Ferritin complex for future drug design. To identify the role of autophagy and the lysosome in PDAC metastatic progression, we co-developed an in vivo capable lysosomal enrichment that enables capture and proteomic profiling of lysosomes at different stages of tumor evolution, including early stage, late stage, and metastatic disease. Employing this strategy, we successfully captured lysosomal proteins from primary tumors (pancreas), as well as lung and liver metastases. Our preliminary analysis revealed an enrichment of resident lysosomal membrane and luminal proteins in the datasets, confirming successful isolation of intact lysosomes from these complex tissues. Additionally, we identified non-resident lysosomal proteins (termed cargo) that are enriched and co-evolve with advancing tumor stages. Notably, our results reveal distinct differences in the lysosomal proteome of tumor cells across different tissues. These findings emphasize the critical role of lysosomal function in tumor progression and suggest that targeting lysosomal components could be a promising therapeutic strategy for treating metastatic PDAC. Finally, given the challenging pharmacokinetic and pharmacodynamic properties and limited clinical efficacy of hydroxychloroquine as an autophagy/lysosomal inhibition strategy, we are now exploring novel autophagy inhibition strategies in PDAC to effectively target this pathway for clinical benefit. Citation Format: Joseph D. Mancias. Targeting autophagy in 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 IA-01.

Synergistic Efficacy of CDK4/6 Inhibitor Abemaciclib and HDAC Inhibitor Panobinostat in Pancreatic Cancer Cells.

The current 5-year survival rate of pancreatic cancer is about 12%, making it one of the deadliest malignancies. The rapid metastasis, acquired drug resistance, and poor patient prognosis necessitate better therapeutic strategies for pancreatic ductal adenocarcinoma (PDAC). Multiple studies show that combining chemotherapeutics for solid tumors has been successful. Targeting two distinct emerging hallmarks, such as non-mutational epigenetic changes by panobinostat (Pan) and delayed cell cycle progression by abemaciclib (Abe), inhibits pancreatic cancer growth. HDAC and CDK4/6 inhibitors are effective but are prone to drug resistance and failure as single agents. Therefore, we hypothesized that combining Abe and Pan could synergistically and lethally affect PDAC survival and proliferation. Multiple cell-based assays, enzymatic activity experiments, and flow cytometry experiments were performed to determine the effects of Abe, Pan, and their combination on PDAC cells and human dermal fibroblasts. Western blotting was used to determine the expression of cell cycle, epigenetic, and apoptosis markers. The Abe-Pan combination exhibited excellent efficacy and produced synergistic effects, altering the expression of cell cycle proteins and epigenetic markers. Pan, alone and in combination with Abe, caused apoptosis in pancreatic cancer cells. Abe-Pan co-treatment showed relative safety in normal human dermal fibroblasts. Our novel combination treatment of Abe and Pan shows synergistic effects on PDAC cells. The combination induces apoptosis, shows relative safety, and merits further investigation due to its therapeutic potential in the treatment of PDAC.

Abstract 3300: Dual inhibition of PIKfyve and KRAS/MAPK as a potential for therapeutic strategy for pancreatic ductal adenocarcinoma

Abstract Background: PIKfyve is a lipid kinase that serves as the single source for PI(3,5)P2, a critical molecule for lysosome functions, including autophagy. Pancreatic Ductal Adenocarcinoma (PDAC) is known to utilize autophagy as well as other lysosome functions to survive in its harsh microenvironment. Considering the role of PIKfyve in autophagy, we hypothesized that PIKfyve is important for PDAC pathophysiology. Indeed, we screened multiple cell lines of different cancer lineages and found that PDAC cell lines were highly sensitive to PIKfyve inhibitors apilimod and ESK981. Given these results, we aimed to establish PIKfyve inhibition as a therapeutic strategy for PDAC. Importantly, this idea is rapidly translatable as both apilimod and ESK981 have both cleared phase-1 clinical trials. Additionally, PDAC nearly ubiquitously harbors a mutation in KRAS, leading to the overactivation of the KRAS-RAF-MEK-ERK pathway, which is known to be the driver of PDAC. Recent reports showed that inhibition of this pathway results in induction of autophagic flux as a protective mechanism in PDAC. Thus, we aimed to investigate the therapeutic potential of PIKfyve inhibition in blocking protective autophagy induced by KRAS/MAPK inhibition. Methods and results: In order to determine the potential of PIKfyve inhibition as a therapeutic for PDAC treatment, we first established that PIKfyve inhibition disrupts the autophagic flux in cells. Specifically, we used PIKfyve inhibitors ESK981 and apilimod as well as CRISPRi-mediated knockdown and saw a decrease in autophagic flux through western blot and GFP-LC3-RFP-LC3∆G-based autophagic flux probe analyses. Finally, PIKfyve inhibition decreased cell viability with IC50s in the nanomolar range.To evaluate the potential of combined inhibition of KRAS/MAPK and PIKfyve, we first confirmed that genetic or pharmacological KRAS/MAPK perturbation indeed increases autophagic flux utilizing the autophagic flux probe. Importantly, we found that PIKfyve inhibition attenuates the autophagic flux induced by KRAS/MAPK inhibition. Moreover, we determined that dual inhibition of PIKfyve and KRAS/MAPK resulted in synergistic growth inhibition employing CellTiter-Glo-based synergy assays. Further, to investigate the in vivo potential of this combination, we utilized a syngeneic orthotopic model of PDAC. Surprisingly, most mice were cured when treated with both ESK981 and trametinib while each individual treatment only modestly decreased tumor burden. Additionally, we established a patient-derived xenograft model where mice treated with a combination of ESK981 and trametinib (MEK inhibitor) or ESK981 and MRTX-1133 (KRASG12D inhibitor) displayed substantial tumor regression in comparison to single treatment or control groups. Taken together, the dual inhibition of PIKfyve and KRAS holds promise as a therapeutic strategy for PDAC treatment. Citation Format: Jasmine P. Wisniewski, Caleb Cheng, Bailey Jackson, Ahmet Korkaya, Sydney Peters, Yuanyuan Qiao, Costas A. Lyssiotis, Arul M. Chinnaiyan. Dual inhibition of PIKfyve and KRAS/MAPK as a potential for therapeutic strategy for pancreatic ductal adenocarcinoma [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 3300.

Tumor immune microenvironment of KRAS G12C mutated pancreatic cancer as compared to other mutations and non-cancer pancreata.

704 Background: KRAS G12C mutation occurs in approximately 1% of pancreatic ductal adenocarcinoma (PDA). KRAS G12C inhibitors have a reported response rate of 21-33% in patients with previously treated advanced PDA. KRAS is a known modulator of the tumor immune microenvironment (TME) and a greater understanding of the TME in KRAS G12C as compared to other mutations is crucial for developing rational therapeutic combination strategies in PDA. Methods: We performed multiplex fluorescent immunohistochemistry (mfIHC) on tissue obtained from patients with histologically confirmed PDA (KRAS G12C n=8; other mutations n=108) and normal pancreas (n=38). Serial staining was performed using antibodies against CD3, CD8, CD163, FoxP3 and PanCK for simple and complex phenotyping as well as spatial analyses in the TME. After tyramide based signal amplification, the slides were imaged at 20x magnification using the Mantra Quantitative Pathology workstation. Images were analyzed using inForm Cell Analysis software (Akoya Biosciences). All statistical analyses were performed using JMP Pro 13.2.0. Differences in phenotype, distances, and engagement were evaluated by 2-tailed Student’s t test or ANOVA. Results: Patients with KRAS G12C mutation had a median age of 70 (45-73) years of which majority (n=5, 62.5%) were men with advanced stage at diagnosis (n=6; 75%). The median overall survival is not yet reached (n=5, alive) after a median follow-up time of 14.4 months through reverse censoring methodology. When examining cellular infiltration, CD8+ cytotoxic T lymphocyte cells were significantly more abundant in the G12C TME compared to the cancer and non-cancer controls (p <0.01). Additionally, the relative frequency of CD4+ and Tregs (CD3+/CD8-/FoxP3+) were also significantly higher in G12C (p<0.01). The percentage of CD163+ antigen presenting cells (APCs) out of all cells was significantly higher in G12C (p<0.01) while the percentage of non-functional APCs (PDL1+/CD163+) of all APCs was significantly higher in G12C than cancer and non-cancer controls (p=0.03). In comparison, the PDL1+ epithelial cells were much lower in G12C TME (p<0.01). The cellular engagement and interaction data from the spatial analysis in the TME will be presented at the meeting. Conclusions: We identified increased infiltration of cytotoxic T lymphocytes and APCs in PDA patients with KRAS G12C mutations relative to other mutations and non-cancerous pancreata. Furthermore, while all PDAs had elevated PD-L1 expression on APCs, KRAS G12C tumors had minimal expression on epithelial cells suggesting a mutation specific impact and a potential role of immune checkpoint inhibitors in combination with G12C inhibitors.

Abstract C047: Improving the efficacy of dual ERK-MAPK and autophagy inhibition as a therapeutic strategy for pancreatic ductal adenocarcinoma

Abstract Pancreatic ductal adenocarcinoma (PDAC) is characterized by KRAS- and autophagy-dependent growth. We and others recently demonstrated that inhibition of KRAS signaling through targeting the RAF-MEK-ERK kinase cascade resulted in further reliance on autophagy. We found that targeting this increased reliance on autophagy with the autophagy inhibitor hydroxychloroquine (HCQ)/chloroquine (CQ) together with MEK or ERK inhibition (MEKi, ERKi) synergistically blocked PDAC growth. These findings provided rationale for our initiation of Phase I/II clinical trials evaluating the combination of MEKi (binimetinib; NCT04132505) or ERKi (LY3214996; NCT04386057) with HCQ in PDAC. However, a limitation of this approach is that HCQ/CQ are not specific or potent autophagy inhibitors. Thus, we sought to identify a more efficacious autophagy inhibition strategy. To this end, we performed a CRISPR-Cas9 mediated genetic loss-of-function screen in PDAC cells to identify other targetable mediators of autophagy. We identified PIKfyve, a lipid kinase critical for the recycling dynamics of lysosomes, as an essential autophagy-related gene in PDAC cells. PIKfyve inhibition by the clinical candidate inhibitor apilimod resulted in potent reduction of autophagic flux and growth. Additionally, PIKfyve inhibition induced intracellular vacuolization. These PIKfyve-regulated vacuoles stained positive for the lysosomal marker, LAMP1, and exhibited reduced acidity and impaired cargo degradation. Importantly, PIKfyve inhibition prevented the increased autophagic flux we observed when we inhibited MEK with the clinical stage MEKi, mirdametinib. As a result, co-targeting MEK and PIKfyve led to synergistic impairment of PDAC cell proliferation. Similar results were observed following dual inhibition of KRAS and PIKfyve. We found the synergistic growth inhibition was due in part to a substantial induction of apoptosis unique to combination treatment. We then tested the combination of MEKi and PIKfyvei in a panel of patient derived PDAC organoids and observed a robust synergistic reduction in viability, suggesting this may be an efficacious therapeutic strategy for PDAC treatment. Future work includes in vivo studies, currently underway, to determine the efficacy of single agent PIKfyve inhibition, as well as efficacy studies assessing combined MEKi and PIKfyvei in orthotopic mouse models of PDAC. Taken together, these findings implicate PIKfyve as an effective anti-autophagy target when paired with RAS or ERK-MAPK pathway inhibition in pre-clinical models of pancreatic cancer. Citation Format: Jonathan M. DeLiberty, Mallory K. Roach, Noah L. Pieper, Kristina Drizyte-Miller, Elyse G. Schechter, Runying Yang, Channing J. Der, Adrienne D. Cox, Clint A. Stalnecker, Kirsten L. Bryant. Improving the efficacy of dual ERK-MAPK and autophagy inhibition as a therapeutic strategy for pancreatic ductal adenocarcinoma [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 C047.

An Update on Gemcitabine-Based Chemosensitization Strategies in Pancreatic Ductal Adenocarcinoma.

Pancreatic cancer is the seventh leading cause of cancer-related deaths, and chemotherapy is one of the most important treatments for pancreatic cancer. Unfortunately, pancreatic cancer cells can block chemotherapy drugs from entering the tumor. This is owing to interactions between the tumor's environment and the cancer cells. Here, we review the latest research on the mechanisms by which pancreatic cancer cells block the chemotherapy drug, gemcitabine. The results of our review can help identify potential therapeutic targets for the blocking of gemcitabine by pancreatic cancer cells and may provide new strategies to help chemotherapy drugs penetrate tumors.

Inhibiting CDK4/6 in pancreatic ductal adenocarcinoma via microRNA-21

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive malignancies, with a 5-year survival rate of 5–10 %. The high mortality rate is due to the asymptomatic progression of clinical features in metastatic stages of the disease, which renders standard therapeutic options futile. PDAC is characterised by alterations in several genes that drive carcinogenesis and limit therapeutic response. The two most common genetic aberrations in PDAC are the mutational activation of KRAS and loss of the tumour suppressor CDK inhibitor 2A (CDKN2A), which culminate the activation of the cyclin-dependent kinase 4 and 6 (CDK4/6), that promote G1 cell cycle progression. Therapeutic strategies focusing on the CDK4/6 inhibitors such as palbociclib (PD-0332991) may potentially improve outcomes in this malignancy. MicroRNAs (miRs/miRNAs) are small endogenous non-coding RNA molecules associated with cellular proliferation, invasion, apoptosis, and cell cycle. Primarily, miR-21 promotes cell proliferation and a higher proportion of PDAC cells in the S phase, while knockdown of miR-21 has been linked to cell cycle arrest at the G2/M phase and inhibition of cell proliferation. In this study, using a CRISPR/Cas9 loss-of-function screen, we individually silenced the expression of miR-21 in two PDAC cell lines and in combination with PD-0332991 treatment, we examined the synergetic mechanisms of CDK4/6 inhibitors and miR-21 knockouts (KOs) on cell survival and death. This combination reduced cell proliferation, cell viability, increased apoptosis and G1 arrest in vitro. We further analysed the mitochondrial respiration and glycolysis of PDAC cells; then assessed the protein content of these cells and revealed numerous Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways associated with PD-0332991 treatment and miR-21 knocking out. Our results demonstrate that combined targeting of CDK4/6 and silencing of miR-21 represents a novel therapeutic strategy in PDAC.

Clinical benefit of subsequent chemotherapy after drug-induced interstitial lung disease in pancreatic cancer patients: a multicenter retrospective study from Japan

PurposeDrug-induced interstitial lung disease (ILD) is not a rare adverse event in the current chemotherapy strategy for pancreatic ductal adenocarcinoma (PDAC). Thus, we aimed to find the optimal management for PDAC patients with a history of ILD induced by a gemcitabine-based regimen.Methods We conducted a multicenter retrospective study. The primary endpoint was the overall survival (OS) of patients who underwent either S-1 monotherapy or FOLFOX after the onset of ILD. Toxicity data was also analyzed in the 2 groups.ResultsTwenty-four patients were diagnosed with ILD and 17 patients who received subsequent chemotherapy were enrolled in the study. Among 17 patients who were managed with subsequent chemotherapy after recovering from ILD, we did not observe significant difference in OS between S-1 and FOLFOX (290.0 days vs. undefined, p = 0.39). Relapse of drug-induced ILD was not observed in all cases during the course. Overall, severe adverse events (CTCAE Grade 3 or 4) were observed in 3 patients (23.1%) in S-1 treatment group and 1 patient (25.0%) in FOLFOX treatment group (p = 0.93).ConclusionsS-1 monotherapy and FOLFOX are comparable as the subsequent chemotherapy after gemcitabine-based chemotherapy-induced ILD in unresectable PDAC.

Abstract 4851: Improving the efficacy of dual ERK-MAPK and autophagy inhibition as a therapeutic strategy for pancreatic ductal adenocarcinoma

Abstract Pancreatic ductal adenocarcinoma (PDAC) is characterized by KRAS- and autophagy-dependent growth. We and others recently demonstrated that inhibition of the RAF-MEK-ERK pathway resulted in upregulated autophagy, and that dual treatment with the autophagy inhibitor hydroxychloroquine (HCQ)/chloroquine (CQ) and MEK or ERK inhibitors (MEKi, ERKi) synergistically blocked PDAC growth. These findings provided rationale for our initiation of Phase I/II clinical trials evaluating the combination of MEKi (binimetinib; NCT04132505) or ERKi (LY3214996; NCT04386057) with HCQ in PDAC. However, HCQ/CQ are not specific or potent autophagy inhibitors. Thus, we sought to identify a more efficacious autophagy inhibition strategy. To this end, we performed a CRISPR-Cas9 mediated genetic loss-of-function screen with a library encompassing cancer signaling pathways in the presence or absence of CQ. In the absence of CQ, we identified PIKfyve, a lipid kinase critical for the recycling dynamics of lysosomes, as an essential autophagy-related gene in PDAC cells. PIKfyve inhibition, by the clinical candidate inhibitor apilimod, resulted in potent reduction of autophagic flux and growth. Additionally, PIKfyve inhibition resulted in robust intracellular vacuolization. Vacuoles stained positive for the lysosomal marker, LAMP1, and exhibited reduced acidity and impaired cargo degradation. Importantly, when we inhibited MEK, with the clinical stage MEKi mirdametinib, and PIKfyve (with apilimod) together, we observed decreased MEKi-induced autophagic flux and synergistic impairment of PDAC cell proliferation. Growth inhibition was due in part to an induction of apoptosis unique to combination treatment. Synergistic growth suppression was maintained in a panel of patient derived PDAC organoids, suggesting this may be an efficacious therapeutic strategy for PDAC treatment. In the presence of CQ, our CRISPR-Cas9 screen showed that loss of upstream autophagy-related genes sensitized PDAC cells to CQ treatment. Validation indicated that vertical inhibition (dual inhibition of distinct nodes of a linear pathway) of the autophagy pathway further reduced autophagic flux relative to inhibition of any single node and synergistically reduced PDAC cell growth. Furthermore, combining ERK-MAPK inhibition with vertical inhibition of autophagy improves the in vitro efficacy of this treatment strategy. Ongoing studies are aimed at delineating the mechanism underlying the synergy observed with anti-autophagy inhibitor combinations and further validation in more advanced preclinical models of PDAC. Citation Format: Jonathan M. DeLiberty, Clint A. Stalnecker, Kristina Drizyte-Miller, Elyse G. Schechter, Noah L. Pieper, Runying Yang, Channing J. Der, Adrienne D. Cox, Kirsten L. Bryant. Improving the efficacy of dual ERK-MAPK and autophagy inhibition as a therapeutic strategy for pancreatic ductal adenocarcinoma. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4851.

Prevalence and Risk Factors of Germline Pathogenic Variants in Pancreatic Ductal Adenocarcinoma.

The genetic attribution for pancreatic ductal adenocarcinoma (PDAC) has been reported as 5%-10%. However, the incidence of germline pathogenic variants (PVs) in Korean PDAC patients has not been thoroughly investigated. Therefore, we studied to identify the risk factors and prevalence of PV for future treatment strategies in PDAC. Total of 300 (155 male) patients with a median age of 65 years (range, 33 to 90 years) were enrolled in National Cancer Center in Korea. Cancer predisposition genes, clinicopathologic characteristics, and family history of cancer were analyzed. PVs were detected in 20 patients (6.7%, median age 65) in ATM (n=7, 31.8%), BRCA1 (n=3, 13.6%), BRCA2 (n=3), and RAD51D (n=3). Each one patient showed TP53, PALB2, PMS2, RAD50, MSH3, and SPINK1 PV. Among them, two likely PVs were in ATM and RAD51D, respectively. Family history of various types of cancer including pancreatic cancer (n=4) were found in 12 patients. Three patients with ATM PVs and a patient with three germline PVs (BRCA2, MSH3, and RAD51D) had first-degree relatives with pancreatic cancer. Familial pancreatic cancer history and PVs detection had a significant association (4/20, 20% vs. 16/264, 5.7%; p=0.035). Our study demonstrated that germline PVs in ATM, BRCA1, BRCA2, and RAD51D are most frequent in Korean PDAC patients and it is comparable to those of different ethnic groups. Although this study did not show guidelines for germline predisposition gene testing in patients with PDAC in Korea, it would be emphasized the need for germline testing for all PDAC patients.

Spatially restricted tumour-associated and host-associated immune drivers correlate with the recurrence sites of pancreatic cancer

ObjectiveMost patients with pancreatic ductal adenocarcinoma (PDAC) will experience recurrence after resection. Here, we investigate spatially organised immune determinants of PDAC recurrence.DesignPDACs (n=284; discovery cohort) were classified according to recurrence...

Combined Targeting of the Glutathione and Thioredoxin Antioxidant Systems in Pancreatic Cancer.

Pancreatic ductal adenocarcinoma is characterized by increased generation of reactive oxygen species that can cause lethal oxidative stress. Here, we evaluated the combined inhibition of the glutathione and thioredoxin antioxidant systems in preclinical models of pancreatic ductal adenocarcinoma, using buthionine sulfoximine (BSO) that targets glutathione synthesis, and auranofin that targets thioredoxin recycling. BSO potentiated the cytotoxicity of auranofin and induced lethal oxidative stress in primary pancreatic cancer cells. As assessed by the cellular thermal shift assay, auranofin engaged with thioredoxin reductase 1 in primary cells at concentrations known to induce cell death. Moreover, we used imaging mass cytometry to map the biodistribution of atomic gold in patient-derived xenografts treated with auranofin, and the drug was readily detectable throughout the epithelial and stromal compartments after treatment with a clinically relevant dose. In conclusion, combinatorial treatment with BSO and auranofin could serve as a potential therapeutic strategy in pancreatic ductal adenocarcinoma.

A ketogenic diet in combination with gemcitabine increases survival in pancreatic cancer KPC mice.

Pancreatic ductal adenocarcinoma (PDAC) continues to be a major health problem. A ketogenic diet (KD), characterized by a very low carbohydrate and high fat composition, has gained attention for its anti-tumor potential. We evaluated the effect and mechanisms of feeding a strict KD alone or in combination with gemcitabine in the autochthonous LSL-KrasG12D/+; LSL-Trp53 R172H/+; Pdx1-Cre (KPC) mouse model. For this purpose, both male and female pancreatic tumor-bearing KPC mice were allocated to a control diet (CD; %kcal: 70% carb, 14% protein, 16% fat), a KD (%kcal: 14% protein, 1% carb, 85% fat), a CD + gemcitabine (CG), or a KD + gemcitabine (KG) group. Mice fed a KD alone or in combination with gemcitabine showed significantly increased blood β-hydroxybutyrate levels compared to mice fed a CD or CG. KPC mice fed a KG had a significant increase in overall median survival compared to KPC mice fed a CD (increased overall median survival by 42%). Interestingly, when the data was disaggregated by sex, the effect of a KG was significant in female KPC mice (60% increase in median overall survival), but not in male KPC mice (28% increase in median overall survival). Mechanistically, the enhanced survival response to a KD combined with gemcitabine was multifactorial, including inhibition of ERK and AKT pathways, regulation of fatty acid metabolism and the modulation of the gut microbiota. In summary, a KD in combination with gemcitabine appears beneficial as a treatment strategy in PDAC in KPC mice, deserving further clinical evaluation.

The Proteoglycan Glypican-1 as a Possible Candidate for Innovative Targeted Therapeutic Strategies for Pancreatic Ductal Adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) accounts for 90% of all pancreatic cancers, with a 5-year survival rate of 7% and 80% of patients diagnosed with advanced or metastatic malignancies. Despite recent advances in diagnostic testing, surgical techniques, and systemic therapies, there remain limited options for the effective treatment of PDAC. There is an urgent need to develop targeted therapies that are able to differentiate between cancerous and non-cancerous cells to reduce side effects and better inhibit tumor growth. Antibody-targeted strategies are a potentially effective option for introducing innovative therapies. Antibody-based immunotherapies and antibody-conjugated nanoparticle-based targeted therapies with antibodies targeting specific tumor-associated antigens (TAA) can be proposed. In this context, glypican-1 (GPC1), which is highly expressed in PDAC and not expressed or expressed at very low levels in non-malignant lesions and healthy pancreatic tissues, is a useful TAA that can be achieved by a specific antibody-based immunotherapy and antibody-conjugated nanoparticle-based targeted therapy. In this review, we describe the main clinical features of PDAC. We propose the proteoglycan GPC1 as a useful TAA for PDAC-targeted therapies. We also provide a digression on the main developed approaches of antibody-based immunotherapy and antibody-conjugated nanoparticle-based targeted therapy, which can be used to target GPC1.

Clinico-genomic Characterization of ATM and HRD in Pancreas Cancer: Application for Practice.

Characterizing germline and somatic ATM variants (gATMm, sATMm) zygosity and their contribution to homologous recombination deficiency (HRD) is important for therapeutic strategy in pancreatic ductal adenocarcinoma (PDAC). Clinico-genomic data for patients with PDAC and other cancers with ATM variants were abstracted. Genomic instability scores (GIS) were derived from ATM-mutant cancers and overall survival (OS) was evaluated. Forty-six patients had PDAC and pathogenic ATM variants including 24 (52%) stage III/IV: gATMm (N = 24), and sATMm (N = 22). Twenty-seven (59%) had biallelic, 15 (33%) monoallelic, and 4 indeterminate (8%) variants. Median OS for advanced-stage cohort at diagnosis (N = 24) was 19.7 months [95% confidence interval (CI): 12.3-not reached (NR)], 27.1 months (95% CI: 22.7-NR) for gATMm (n = 11), and 12.3 months for sATMm (n = 13; 95% CI: 11.9-NR; P = 0.025). GIS was computed for 33 patients with PDAC and compared with other ATM-mutant cancers enriched for HRD. The median was lower (median, 11; range, 2-29) relative to breast (18, 3-55) or ovarian (25, 3-56) ATM-mutant cancers (P < 0.001 and P = 0.003, respectively). Interestingly, biallelic pathogenic ATM variants were mutually exclusive with TP53. Other canonical driver gene (KRAS, CDKN2A, SMAD4) variants were less frequent in ATM-mutant PDAC. ATM variants in PDAC represent a distinct biologic group and appear to have favorable OS. Nonetheless, pathogenic ATM variants do not confer an HRD signature in PDAC and ATM should be considered as a non-core HR gene in this disease.

Systemic therapy and perioperative management improve the prognosis of pancreatic ductal adenocarcinoma: A retrospective cohort study of 2000 consecutive cases

ObjectiveThis study aimed to explore patterns of the treatment strategies of pancreatic ductal adenocarcinoma based on 2000 consecutive cases of a prospective database since 2012 to obtain new insights for future directions. MethodsAmong 2000 patients enrolled in this study, 210 patients were excluded, and 710, 521, and 559 patients were treated between 2012 and 2015 (group 1), between 2016 and 2017 (group 2), and between 2018 and 2019 (group 3), respectively. Patient clinicopathologic and biological factors, and perioperative outcomes were used to assess the prognostic factors. ResultsThe median survival for all patients with pancreatic ductal adenocarcinoma was 21.7 months (1-year survival, 75.0%; 2-year survival, 43.7%; 5-year survival, 19.7%). Group 3 had a better survival outcome than groups 1 and 2 (median survival time: 23 versus 20.5 and 21.1 months). The proportion of patients younger than 65 gradually increased over time, as did the use of systemic chemotherapy and postoperative adjuvant radiotherapy. The tendency for early diagnosis (lower CA19-9 and CEA levels, smaller size, and earlier N stage), use of chemotherapy and radiotherapy, early recovery (lesser hospital stay and Clavien-Dindo grade <3), absence of abdominal pain, younger age, length of operation ≤3 h, and pathological factors (absence of lymphovascular invasion, peripancreatic fat infiltration and neural invasion, higher differentiation) were related to patients' survival. Multivariable analysis for prognosis revealed that tumor biological factors (increased preoperative serum CA19-9 level, tumor size, tumor differentiation, N stage, and presence of lymphovascular invasion and neural invasion), chemotherapy, radiotherapy, abdomen pain, operation period, length of stay, and length of operation correlated with patients’ survival. ConclusionsSystemic therapy, including chemotherapy and radiotherapy, has gradually improved the prognosis after operative resection for pancreatic ductal adenocarcinoma. Neoadjuvant therapy is also beneficial to improve the prognosis to a certain extent. The enhanced recovery after surgery (ERAS) policies and the specific assessment of postoperative pancreatic fistula (POPF) risk may be related to reduced hospital stays and the reduction of serious complications. These advancements show that the concept of systemic therapy has been accepted and actively applied by Chinese medical institutions.

Abstract 3546: DFMO based improvement in survival of pancreatic cancer-bearing mice is associated with modulation of immune suppression in the tumor microenvironment

Abstract Existing therapeutics have failed to improve pancreatic ductal adenocarcinoma (PDAC) patient outcomes, in part due to tumor associated immune suppression and upregulation of compensatory mechanisms. KRAS and c-MYC are important oncogenes in PDAC linked to tumor immune suppression. We describe the use of difluoromethylornithine (DFMO) and a c-RAF inhibitor (GW5074) to indirectly target c-MYC and KRAS, respectively. DFMO in combination with GW5074 was tested for ability to improve pancreatic cancer outcomes. Pancreatic cancer cells showed decreased cell viability and increased apoptosis in response to a combination of DFMO + GW5074. In vivo orthotopic models of pancreatic tumors had decreased tumor weight in DFMO + GW5074 treated mice, when compared to control group. However, only treatment with single agent DFMO resulted in improved survival of immunocompetent pancreatic tumor bearing mice with respect to control, in contrast to treatment with GW5074 alone or DFMO + GW5074. To understand why the in vivo data was contrary to in vitro results, immunohistochemical analysis of immune cells in the tumor microenvironment was used to reveal increased expression of markers associated with anti-tumor effects such as CD86, CD3, CD4 and CD8 in DFMO treated tumors. Tumors treated with DFMO also displayed decreased expression of MYC, suggesting that DFMO-associated MYC suppression could be linked to decreased immune suppression in the tumor microenvironment and improved survival. In contrast, GW5074 treatment maintained MYC expression in tumors. Overall, the present study points to DFMO being an immunomodulatory agent, and a need for further understanding of DFMO-based therapeutic strategies in PDAC. Citation Format: Sai Preethi Nakkina, Sarah B. Gitto, Jordan M. Beardsley, Veethika Pandey, Michael M. Rohr, Jignesh Parikh, Otto Phanstiel, Deborah A. Altomare. DFMO based improvement in survival of pancreatic cancer-bearing mice is associated with modulation of immune suppression in the tumor microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3546.