Advanced Pancreatic Ductal Adenocarcinoma Research Articles

TRIANGLE operation, combined with adequate adjuvant chemotherapy, can improve the prognosis of pancreatic head cancer: A retrospective study.

The TRIANGLE operation involves the removal of all tissues within the triangle bounded by the portal vein-superior mesenteric vein, celiac axis-common hepatic artery, and superior mesenteric artery to improve patient prognosis. Although previously promising in patients with locally advanced pancreatic ductal adenocarcinoma (PDAC), data are limited regarding the long-term oncological outcomes of the TRIANGLE operation among resectable PDAC patients undergoing pancreaticoduodenectomy (PD). To evaluate the safety of the TRIANGLE operation during PD and the prognosis in patients with resectable PDAC. This retrospective cohort study included patients who underwent PD for pancreatic head cancer between January 2017 and April 2023, with or without the TRIANGLE operation. Patients were divided into the PDTRIANGLE and PDnon-TRIANGLE groups. Surgical and survival outcomes were compared between the two groups. Adequate adjuvant chemotherapy was defined as adjuvant chemotherapy ≥ 6 months. The PDTRIANGLE and PDnon-TRIANGLE groups included 52 and 55 patients, respectively. There were no significant differences in the baseline characteristics or perioperative indexes between the two groups. Furthermore, the recurrence rate was lower in the PDTRIANGLE group than in the PDnon-TRIANGLE group (48.1% vs 81.8%, P < 0.001), and the local recurrence rate of PDAC decreased from 37.8% to 16.0%. Multivariate Cox regression analysis revealed that PDTRIANGLE (HR = 0.424; 95%CI: 0.256-0.702; P = 0.001), adequate adjuvant chemotherapy ≥ 6 months (HR = 0.370; 95%CI: 0.222-0.618; P < 0.001) and margin status (HR = 2.255; 95%CI: 1.252-4.064; P = 0.007) were found to be independent factors for the recurrence rate. The TRIANGLE operation is safe for PDAC patients undergoing PD. Moreover, it reduces the local recurrence rate of PDAC and may improve survival in patients who receive adequate adjuvant chemotherapy.

Morbidity and mortality in patients with stage IV pancreatic adenocarcinoma and acute cholangitis: Outcomes and risk prognostication

BackgroundAcute cholangitis (AC) is a common complication of pancreatic ductal adenocarcinoma (PDAC). Herein, we evaluated outcomes after the first AC episode and predictors of mortality and AC recurrence in patients with stage IV PDAC. MethodsWe conducted a single-center, retrospective observational study using institutional databases. Clinical data and outcomes for patients with stage IV PDAC and at least one documented episode of AC, were assessed. Overall survival (OS) was estimated using the Kaplan-Meier method, and Cox regression model was employed to identify predictors of AC recurrence and mortality. ResultsOne hundred and twenty-four patients with stage IV PDAC and AC identified between January 01, 2014 and October 31, 2020 were included. Median OS after first episode of AC was 4.1 months (95 % CI, 4.0–5.5), and 30-day, 6, and 12-month survival was 86.2 % (95 % CI, 80.3–92.5), 37 % (95 % CI, 29.3–46.6 %) and 18.9 % (95 % CI, 13.1–27.3 %), respectively. Primary tumor in pancreatic body/tail (HR 2.29, 95 % CI: 1.26 to 4.18, p = 0.011), concomitant metastases to liver and other sites (HR 1.96, 95 % CI: 1.16 to 3.31, p = 0.003) and grade 3 AC (HR 2.26, 95 % CI: 1.45 to 3.52, p < 0.001), predicted worse outcomes. Intensive care unit admission, sepsis, systemic therapy, treatment regimen, and time to intervention did not predict survival or risk of recurrence of AC. ConclusionsAC confers significant morbidity and mortality in advanced PDAC. Worse outcomes are associated with higher grade AC, primary tumor location in pancreatic body/tail, and metastases to liver and other sites.

The Role of Pretreatment Serum Interleukin 6 in Predicting Short-Term Mortality in Patients with Advanced Pancreatic Cancer.

Pancreatic ductal adenocarcinoma (PDAC) is notorious for its aggressive progression and dismal survival rates, with this study highlighting elevated interleukin 6 (IL-6) levels in patients as a key marker of increased disease severity and a potential prognostic indicator. Analyzing pre-treatment serum from 77 advanced PDAC patients via ELISA, the research determined optimal cutoff values for IL-6 and the IL-6:sIL-6Rα ratio using receiver operating characteristic curve analysis, which then facilitated the division of patients into low and high IL-6 groups, showing significantly different survival outcomes. Notably, high IL-6 levels correlated with adverse features such as poorly differentiated histology, higher tumor burden, and low albumin levels, indicating a stronger likelihood of poorer prognosis. With a median follow-up of 9.28 months, patients with lower IL-6 levels experienced markedly better median overall survival and progression-free survival than those with higher levels, underscoring IL-6's role in predicting disease prognosis. Multivariate analysis further confirmed IL-6 levels, alongside older age, and elevated neutrophil-to-lymphocyte ratio, as predictors of worse outcomes, suggesting that IL-6 could be a critical biomarker for tailoring treatment strategies in advanced PDAC, warranting further investigation into its role in systemic inflammation and the tumor microenvironment.

Rintatolimod in Advanced Pancreatic Cancer enhances Anti-Tumor Immunity through Dendritic Cell-Mediated T Cell Responses.

Amid the need for new approaches to improve survival in pancreatic ductal adenocarcinoma (PDAC), immune-based therapies have garnered interest. Rintatolimod, a toll-like receptor 3 (TLR-3) agonist, is a potential candidate due to its dual impact on restraining PDAC cell functions and boosting the anti-tumor immune response. This study investigates the effect of TLR-3 activation through rintatolimod on the peripheral immune landscape of advanced PDAC patients. Paired blood samples of 30 patients with advanced PDAC, collected at baseline and after 12 rintatolimod intravenous infusions, underwent comprehensive transcriptomic NanoString and proteomic flow cytometry profiling. The impact of rintatolimod and immunological factors on survival outcomes was assessed through univariate Cox proportional hazards models. Rintatolimod treatment enhances peripheral immune activity at the transcriptomic and proteomic levels, particularly involving type 1 conventional dendritic cells (cDC1s) and T cells. Post-rintatolimod, the increased peripheral abundance of BTLA+XCR1+ cDC1s and CD4+SELL+ T cells correlated with improved clinical outcomes. Patients with stable disease exhibited pronounced DC and T cell activation gene overexpression. Notably, the expression of immune checkpoints PD-L1 and PD-L2 decreased post-rintatolimod across all patients. However, those with progressive disease showed increased expression of genes encoding IDO1 and PD-1. This study presents compelling evidence of the immune-stimulatory properties linked to TLR-3 activation through rintatolimod. Rintatolimod may break immunological tolerance by enhancing anti-tumor immunity through DC-mediated Th-cell responses. Furthermore, our findings lay the groundwork for investigating the potential synergy between TLR-3 activation and immune checkpoint inhibitor therapy to improve therapeutic outcomes.

Abstract CT016: Immunomodulation of the tumor microenvironment of pancreatic ductal adenocarcinoma with histone deacetylase inhibition: Results of a phase 2 clinical trial of entinostat in combination with nivolumab

Abstract Background The tumor microenvironment (TME) of pancreatic ductal adenocarcinoma (PDA) is characterized by a paucity of cytotoxic tumor-infiltrating lymphocytes, an abundance of immune-suppressive cell populations, and a general resistance to immune checkpoint inhibitor (ICI) therapy. In preclinical models of PDA, the HDAC inhibitor entinostat modulated the transcriptional programming of myeloid cells, reducing their capacity for immunosuppression and sensitizing tumors to ICI therapy. Methods We conducted a single-center, open-label, Simon two-stage, phase II study of entinostat in combination with the PD1 inhibitor nivolumab in patients with advanced PDA. Patients received oral entinostat 5 mg once a week. After a 14-day lead-in with entinostat monotherapy, patients concurrently receive entinostat 5 mg orally once a week plus nivolumab 240 mg intravenously every 2 weeks. After 4 months, therapy was continued with entinostat 5 mg weekly plus nivolumab at a dose of 480 mg fixed dose every 4 weeks until the time of progression or unacceptable toxicities. The primary endpoint was the objective response rate by Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1. Peripheral immune profiles at baseline and on treatment were assessed by high-dimensional mass cytometry by time of flight (CyTOF) and by Luminex of chemokines in the plasma, and changes in the TME were performed on paired baseline and on treatment biopsies by multiplexed immunohistochemistry (mIHC), image cytometry-based quantification, and bulk RNA-seq analysis. Results From November 2017 to November 2020, 27 evaluable patients were enrolled. Three patients had a partial response (PR) by RECIST v1.1 criteria (objective response rate (ORR)) of 11%, 95% CI, 0.024-0.292), with a median duration of response of 10.2 months. Grade ≥3 treatment-related adverse events (TRAEs) were observed in 19 (63%) patients. The most common grade ≥3 TRAEs were decreased lymphocyte count, anemia hypoalbuminemia, and hyponatremia. Dendritic cell (DC) activation, maturation, migration, antigen processing, and presentation were increased in the periphery after entinostat treatment, consistent with HDAC inhibitor mediated myeloid reprogramming. Gene expression analysis of paired baseline and on treatment tumors demonstrated an enrichment in inflammatory response signaling pathways with combination treatment. Conclusions Entinostat and nivolumab demonstrated durable radiological responses in a subset of patients with PDA. Paired tissue and peripheral analysis showed immunomodulation of myeloid cell populations, consistent with the preclinical hypothesis supporting the trial. This study creates a roadmap for this strategy with future combinatorial therapeutic approaches to enhance the clinical benefit in PDA patients further. Citation Format: Marina Baretti, Ludmila Danilova, Jennifer N. Durham, Courtney B. Betts, Leslie Cope, Dimitrios N. Sidiropoulos, Joseph A. Tandurella, Soren Charmsaz, Nicole Gross, Alexei Hernandez, Won J. HO, Chris Thoburn, Rosalind Walker, James Leatherman Leatherman, Sarah Mitchell, Brian Christmas, Daria A. Gaykalova, Srinivasan Yegnasubramanian, Elana J. Fertig, Lisa M. Coussens, Mark Yarchoan, Elizabeth Jaffee, Nilofer S. Azad. Immunomodulation of the tumor microenvironment of pancreatic ductal adenocarcinoma with histone deacetylase inhibition: Results of a phase 2 clinical trial of entinostat in combination with nivolumab [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT016.

Abstract CT134: Safety and immunologic impact of neoadjuvant/adjuvant GM-CSF-secreting allogenic pancreatic tumor cell vaccine (GVAX) combined with cyclophosphamide, pembrolizumab, and macrophage-targeting CSF1R inhibitor IMC-CS4 in pancreatic adenocarcinoma

Abstract Background: Strategies are needed to improve effectiveness of immunotherapy in pancreatic ductal adenocarcinoma (PDA). Our recently published study (NCT02648282) showed that increased M1/M2 ratio and decreased PDL1+ M2-like tumor associated macrophages (TAM) in locally advanced PDA is associated with longer overall survival (OS) following combination of stereotactic body radiotherapy, GVAX and anti-PD1 antibody pembrolizumab (Pem). We hypothesized targeting M2-like macrophages, regulated by the colony stimulating factor-1 (CSF1) pathway, would improve outcomes. In this pilot study we investigated the safety and intratumoral immune response of neoadjuvant/adjuvant triplet immunotherapy: GVAX/cyclophosphamide (CY), Pem, and CSF1 receptor blockade (IMC-CS4) in patients with resectable or borderline resectable PDA. Methods: After completing chemotherapy and radiation patients received two 3-week cycles of neoadjuvant triplet immunotherapy. Following surgery, patients received 4 additional cycles followed by booster Pem every 3 weeks and GVAX/CY every 6 months, for one year. Co-primary endpoints were safety, assessed by NCI Common Terminology Criteria for Adverse Events (AEs), and immune response (increased CD8+ T-cell density in surgical specimen as compared to pre-treatment core). Secondary endpoints included disease free survival (DFS), OS, surgical resectability, and pathologic response (PR). Results: Nine patients were enrolled. Two immune related grade 3/4 AEs (diarrhea and rash) were reported. Median DFS was 12.6 months (95% CI: 7.3, NR) and median OS was 20.4 months (95% CI: 17.5, NR). All patients underwent surgery with major PR rate of 78% (defined as &amp;lt;10% residual viable tumor), including one complete PR. Comparing paired biopsies, the study met its primary immunologic endpoint showing 6/8 patients (75%) had a &amp;gt;80% increase of CD8+ T cells; the increase was at least 1.8 times the baseline median absolute deviation following triple therapy (p=0.012). There was a significant increase of Granzyme B+ CD8+ T cells among all patients (p=0.045). No significant change in myeloid cell density, including TAM, was observed, suggesting IMC-CS4 did not deplete macrophages, but potentially reprogrammed them. The 4 patients with greatest drop in CD66b+ granulocyte levels had major PR (grade 0 or 1). Conclusion: The triplet was safe and significantly increased activated CD8+ T cells suggesting the combination can induce an effector T cell response. Decreased granulocyte levels correlated with PR. Citation Format: Arielle Urman, Yingjun Ding, Hao Wang, Richard A. Burkhart, Jin He, Elizabeth M. Jaffee, Amol K. Narang, Dung Le, Daniel A. Laheru, Lei Zheng, Ana De Jesus-Acosta. Safety and immunologic impact of neoadjuvant/adjuvant GM-CSF-secreting allogenic pancreatic tumor cell vaccine (GVAX) combined with cyclophosphamide, pembrolizumab, and macrophage-targeting CSF1R inhibitor IMC-CS4 in pancreatic adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT134.

Albumin-myosteatosis gauge as a prognostic factor in patients with advanced pancreatic cancer undergoing first-line chemotherapy.

Sarcopenia and myosteatosis have been associated with a poor prognosis for several cancers. The albumin-myosteatosis gauge (AMG) is a novel integrated measure proposed to assess myosteatosis along with serum albumin level as a surrogate of systemic inflammation and malnutrition. The aim of this study was to investigate the prognostic value of AMG in patients with advanced pancreatic ductal adenocarcinoma (PDAC). Patients with advanced PDAC treated with chemotherapy between 2013 and 2022 were evaluated. Skeletal muscle radiodensity (SMD) and skeletal muscle index (SMI) were calculated using computed tomography at the level of the L3 vertebra. The AMG was defined as albumin x SMD and expressed as an arbitrary unit (AU). Patients were first categorized by sex-specific quartiles and then dichotomized at the sex-specific median value of the AMG. A total of 196 patients were included. The median age (interquartile range) was 62 (54-67), and 128 (65.3%) were male. With regard to AMG, 142.86 and 114.15 AU were identified as cutoff values for males and females, respectively. In multivariable analyses, lower AMG values (G1-G2 vs. G3-G4) (HR: 1.61, 95% CI 1.17-2.21, p = 0.003), higher ECOG performance score (> 0 vs. 0) (HR: 1.51, 95% CI 1.10-2.06, p = 0.009) and metastatic disease (vs. locally advanced) (HR: 1.88, 95% CI 1.27-2.79, p = 0.001) were associated with OS. The study findings suggest the prognostic value of AMG in patients with advanced PDAC undergoing first-line chemotherapy. Further studies are warranted to validate these findings and assess potential predictive role of AMG in guiding treatment selection.

LOAd703, an oncolytic virus-based immunostimulatory gene therapy, combined with chemotherapy for unresectable or metastatic pancreatic cancer (LOKON001): results from arm 1 of a non-randomised, single-centre, phase 1/2 study

Pancreatic ductal adenocarcinoma is characterised by low immunogenicity and an immunosuppressive tumour microenvironment. LOAd703, an oncolytic adenovirus with transgenes encoding TMZ-CD40L and 4-1BBL, lyses cancer cells selectively, activates cytotoxic T cells, and induces tumour regression in preclinical models. The aim of this study was to evaluate the safety and feasibility of combining LOAd703 with chemotherapy for advanced pancreatic ductal adenocarcinoma. LOKON001 was a non-randomised, phase 1/2 study conducted at the Dan L Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, TX, USA, and consisted of two arms conducted sequentially; the results of arm 1 are presented here. In arm 1, patients 18 years or older with previously treated or treatment-naive unresectable or metastatic pancreatic ductal adenocarcinoma were treated with standard 28-day cycles of intravenous nab-paclitaxel 125 mg/m2 plus gemcitabine 1000 mg/m2 (up to 12 cycles) and intratumoural injections of LOAd703 every 2 weeks. Patients were assigned using Bayesian optimal interval design to receive 500 μL of LOAd703 at 5 × 1010 (dose 1), 1 × 1011 (dose 2), or 5 × 1011 (dose 3) viral particles per injection, injected endoscopically or percutaneously into the pancreatic tumour or a metastasis for six injections. The primary endpoints were safety and treatment-emergent immune response in patients who received at least one dose of LOAd703, and antitumour activity was a secondary endpoint. This study was registered with ClinicalTrials.gov, NCT02705196, arm 2 is ongoing and open to new participants. Between Dec 2, 2016, and Oct 17, 2019, 23 patients were assessed for eligibility, leading to 22 patients being enrolled. One patient withdrew consent, resulting in 21 patients (13 [62%] men and eight [38%] women) assigned to a dose group (three to dose 1, four to dose 2, and 14 to dose 3). 21 patients were evaluable for safety. Median follow-up time was 6 months (IQR 4-10), and data cutoff was Jan 5, 2023. The most common treatment-emergent adverse events overall were anaemia (96 [8%] of 1237 events), lymphopenia (86 [7%] events), hyperglycaemia (70 [6%] events), leukopenia (63 [5%] events), hypertension (62 [5%] events), and hypoalbuminaemia (61 [5%] events). The most common adverse events attributed to LOAd703 were fever (14 [67%] of 21 patients), fatigue (eight [38%]), chills (seven [33%]), and elevated liver enzymes (alanine aminotransferase in five [24%], alkaline phosphatase in four [19%], and aspartate aminotransferase in four [19%]), all of which were grade 1-2, except for a transient grade 3 aminotransferase elevation occurring at dose 3. A maximum tolerated dose was not reached, thereby establishing dose 3 as the highest-evaluated safe dose when combined with nab-paclitaxel plus gemcitabine. Proportions of CD8+ effector memory cells and adenovirus-specific T cells increased after LOAd703 injections in 15 (94%) of 16 patients for whom T-cell assays could be performed. Eight (44%, 95% CI 25-66) of 18 patients evaluable for activity had an objective response. Combining LOAd703 with nab-paclitaxel plus gemcitabine in patients with advanced pancreatic ductal adenocarcinoma was feasible and safe. To build upon this novel chemoimmunotherapeutic approach, arm 2 of LOKON001, which combines LOAd703, nab-paclitaxel plus gemcitabine, and atezolizumab, is ongoing. Lokon Pharma, the Swedish Cancer Society, and the Swedish Research Council.

Comparison of prognosis and postoperative morbidities between standard pancreaticoduodenectomy and the TRIANGLE technique for resectable pancreatic ductal adenocarcinoma.

Radical surgery combined with systemic chemotherapy offers the possibility of long-term survival or even cure for patients with pancreatic ductal adenocarcinoma (PDAC), although tumor recurrence, especially locally, still inhibits the treatment efficacy. The TRIANGLE technique was introduced as an extended dissection procedure to improve the R0 resection rate of borderline resectable or locally advanced PDAC. However, there was a lack of studies concerning postoperative complications and long-term outcomes of this procedure on patients with resectable PDAC. To compare the prognosis and postoperative morbidities between standard pancreaticoduodenectomy (PD) and the TRIANGLE technique for resectable PDAC. Patients with resectable PDAC eligible for PD from our hospital between June 2018 and December 2021 were enrolled in this retrospective cohort study. All the patients were divided into PDstandard and PDTRIANGLE groups according to the surgical procedure. Baseline characteristics, surgical data, and postoperative morbidities were recorded. All of the patients were followed up, and the date and location of tumor recurrence, and death were recorded. The Kaplan-Meier method and log-rank test were used for the survival analysis. There were 93 patients included in the study and 37 underwent the TRIANGLE technique. Duration of operation was longer in the PDTRIANGLE group compared with the PDstandard group [440 (410-480) min vs 320 (265-427) min] (P = 0.001). Intraoperative blood loss [700 (500-1200) mL vs 500 (300-800) mL] (P = 0.009) and blood transfusion [975 (0-1250) mL vs 400 (0-800) mL] (P = 0.009) were higher in the PDTRIANGLE group. There was a higher incidence of surgical site infection (43.2% vs 12.5%) (P = 0.001) and postoperative diarrhea (54.1% vs 12.5%) (P = 0.001) in the PDTRIANGLE group. The rates of R0 resection and local recurrence, overall survival, and disease-free survival did not differ significantly between the two groups. The TRIANGLE technique is safe, with acceptable postoperative morbidities compared with standardized PD, but it does not improve prognosis for patients with resectable PDAC.

Plasma miR-379 can predict treatment response to FOLFIRINOX and gemcitabine-nab-paclitaxel in advanced pancreatic cancer

BackgroundNovel biomarkers, such as plasma microRNAs (miRs), are needed to help guide clinical decision-making for the type of chemotherapy to use in patients with advanced pancreatic ductal adenocarcinoma (PDAC). This study assessed the ability of plasma miRs to predict optimal treatment response from FOLFIRINOX or gemcitabine-nab-paclitaxel in these patients. MethodsNext-generation sequencing (NGS) was performed for biomarker discovery in pre-treatment plasma samples from advanced PDAC patients subsequently treated with FOLFIRINOX (n = 12) or gemcitabine-nab-paclitaxel (n = 12). Selected candidate biomarkers were validated in 40 patients with advanced PDAC using RT-qPCR. Cox regression was then used to assess the predictive value of plasma miRs for either FOLFIRINOX or gemcitabine-nab-paclitaxel. ResultsIn the validation cohort, high plasma miR-379 expression was strongly predictive of treatment response (Pinteraction = 0.0004). Overall survival (OS) was significantly better with FOLFIRINOX vs. gemcitabine-nab-paclitaxel in those patients with lower plasma miR-379 expression (hazard ratio, 0.32 [95% confidence interval, 0.08 to 0.98]; P = 0.046). However, gemcitabine-nab-paclitaxel was associated with superior OS in patients with higher plasma miR-379 (hazard ratio, 0.28 [0.10 to 0.86]; P = 0.027). In contrast, miR-127, miR-155, and miR-200 showed no predictive value for treatment response for either chemotherapy regimen (Pinteraction = 0.12, Pinteraction = 0.83 and Pinteraction = 0.12, respectively). ConclusionsPlasma miR-379 appears clinically useful as a predictive biomarker to identify which patients with advanced PDAC benefit most from treatment with FOLFIRINOX or gemcitabine-nab-paclitaxel. Further validation in larger studies and clinical trials is now warranted.

Abstract 4162: Peptide-targeted probe identifies pancreatic cancer using optoacoustic imaging

Abstract Introduction: Advanced pancreatic ductal adenocarcinoma (PDAC) suffers from inadequate early detection, inoperability, and poor outcomes. While tumor identication in an intraoperative setting largely utilize ultrasound, ultrasound suffers from insufficient resolution and lacks the ability to identify molecular features to differentiate tumor from non-tumor. To overcome these limitations, we utilized optoacoustic imaging combined with a pH-sensitive peptide-based probe, V3, to identify pancreatic cancer in orthotopic mouse models. Methods: The V3 peptide was synthesized using microwave chemistry which resulted in a peptide of &amp;gt;90% purity. The V3 peptide was conjugated to a fluorescent dye and dialyzed to make the V3-750 probe. S2VP10 cancer cell line was plated in a 6-well plate and acclimated to 7.4, 6.8, and 6.6 pH media to mimic a healthy microenvironment and the acidic tumor microenvironment found in pancreas cancer. Cells were treated with 1 micromolar of V3-750 probe for 1 hour, then imaged on the near-infrared fluorescence imager. Treated cells were loaded into tissue mimicking phantoms and imaged using multispectral optoacoustic tomography. Athymic mice were orthotopically implanted with S2VP10 cells and tumor grew to 3 mm. V3-750 was intraveneously injected and mice were imaged 3h after injection with MSOT. Results: Signal values for the samples displayed a trend that the V3-750 probe has higher signal values in the 6.8 and 6.6 pH as compared to the 7.4 pH. MSOT data supported this trend, with the signal values from the 6.8 and 6.6 pH being greater than the 7.4 pH by 10-fold (p&amp;lt;0.05). Biodistribution demonstrates peak tumor-specific uptake at 3h post injection (3.1 a.u., 0.003 a.u. liver, 0.002 a.u. kidney). Conclusion: The heightened signal values for the acidic pH’s from the fluorescence imaging and the MSOT suggest that the V3-750 probe can contrast acidic cancer cells from healthy cells because it targets the acidic cancer microenvironment. Citation Format: Emma Sanderson, Tereza Husarova, Lacey McNally. Peptide-targeted probe identifies pancreatic cancer using optoacoustic imaging [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 4162.

Abstract 2542: Real-world validation of the PurIST classifier demonstrates enhanced therapy selection for pancreatic ductal adenocarcinoma (PDAC) patients

Abstract Background: PDAC is a particularly fatal condition lacking established biomarkers for the choice of first-line treatment (1L). The PurIST algorithm is a gene signature (Rashid et al. Clin. Cancer Res., 2020) that categorizes PDAC tumors into basal or classical molecular subtypes and has been previously validated in a patient cohort of advanced PDAC (N=258). In this post-hoc analysis study, we examine whether the PurIST subtypes can distinguish patients likely to respond to FOLFIRINOX (FFX) versus Gemcitabine + nab-paclitaxel (GnP). Methods: A cohort of de-identified PDAC patients was selected from the Tempus Oncology Database following an IRB-approved protocol. Inclusion criteria required no prior systemic treatment, a surgically unresectable/metastatic status, available RNA-sequencing data from primary or metastatic tissue, and the use of FFX or GnP as 1L systemic therapy with documented outcomes. RNA-sequencing was generated by the CAP/CLIA validated Tempus xR assay. The PurIST gene signature was applied to normalized gene expression values to classify samples into basal or classical subtypes. Univariate and multivariate Cox PH analyzes comparing overall survival (OS) with adjustment for delayed entry, between two common 1L treatment regimens, FFX and GnP, were performed for classical patients with an ECOG performance status of 0 or 1. Results: Application of the PurIST model to the PDAC cohort (N=258) resulted in 67% (N=173) labeled as classical, 23% (N=59) as basal, and the remainder as no-call. Amongst classical patients, 35% (N=61) had a known ECOG score of 0 or 1 and were retained for subsequent analysis. Within this subset, 37 were treated with FFX and 24 with GnP as 1L, with an overall median OS of 11.4 months (95% CI: 9.5-16.5) and a 12-month survival rate of 47.2%. A univariate Cox PH analysis showed that classical patients treated with FFX had a significantly longer OS time (HR (95% CI) = 2.32 (1.29-4.17)). This result remained significant in a multivariate Cox PH, adjusting for age and ECOG, (HR=2.5 (1.15-5.44)). Conclusion: In this real-world cohort of advanced PDAC patients, we showed that classical patients with low ECOG scores had superior OS with 1L FFX treatment compared to 1L GnP. These findings demonstrate the potential for PurIST to aid in optimal treatment selection for patients with advanced PDAC. Citation Format: Stephane Wenric, James M. Davison, John Guittar, Gregory M. Mayhew, Kirk Beebe, Alia Zander, Seung Won Hyun, Kyle Beauchamp, Michael V. Milburn, Vincent Chung, Tanios S. Bekaii-Saab, Charles M. Perou. Real-world validation of the PurIST classifier demonstrates enhanced therapy selection for pancreatic ductal adenocarcinoma (PDAC) patients [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 2542.

Abstract 4737: The combination of the BET inhibitor JQ1 and gemcitabine induces regressions in gemcitabine resistant patient-derived xenograft models of pancreatic cancer

Abstract Efforts to develop targeted therapies for drug resistant tumors have been relatively unsuccessful. The 5-year survival for patients with advanced pancreatic cancer is ~3%. Gemcitabine is usually combined with nab-paclitaxel as a standard of care for treatment of locally advanced or metastatic pancreatic ductal adenocarcinoma (PDAC). However, no chemotherapeutic regimens thus far evaluated have been curative. We developed the first PDAC patient-derived xenograft (PDX) models in which resistance against gemcitabine was acquired in vivo. We used RNA-seq and ingenuity pathway analysis to compare expression profiles of paired parent vs gemcitabine resistant PDX models. This comparison suggested a previously unreported mechanism for gemcitabine resistance, involving aberrations of cholesterol biosynthesis and lipid metabolism pathways. We also made the unexpected observation that gemcitabine-resistant PDAC models derived from primary tumors have high levels of 3-hydroxy-3-methylglutaryl-CoA synthase 2 (HMGCS2), an enzyme essential to cholesterol biosynthesis and rate limiting in ketogenesis. Notably, the BET bromodomain inhibitor JQ1 decreases HMGCS2 levels; and BET inhibitors + gemcitabine exert synergistic cytotoxicity in gemcitabine-resistant PDAC cells. We determined that the BET bromodomain inhibitor JQ1 + gemcitabine induces regressions of two in vivo gemcitabine-resistant tumor models which we developed directly from primary human tumor tissue. These mechanism-based studies suggest that inhibiting HMGCS2 represents a novel approach to therapy for PDAC. We propose that combining gemcitabine with agents that decrease levels of HMGCS2 comprises effective treatment for patients with drug resistant PDAC. Citation Format: Aubrey L. Miller, Samuel C. Fehling, Eric Josh Brown, Eric O. Heard, Tracy L. Gamblin, Rebecca B. Vance, Karina J. Yoon. The combination of the BET inhibitor JQ1 and gemcitabine induces regressions in gemcitabine resistant patient-derived xenograft models of pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4737.

Abstract 1262: Comparative analysis of TP53 alleles in pancreatic ductal adenocarcinoma

Abstract The transcription factor p53 is a tumor suppressor capable of inducing cell cycle arrest, senescence, and apoptosis. Both truncating loss-of-function mutations and point mutations of the TP53 gene (mouse gene Trp53), which encodes for the p53 protein, are frequently observed across human cancers. While point mutations in p53 result in loss of canonical tumor suppressor function, recent studies suggest that these mutated proteins acquire pro-tumorigenic gain-of-function properties. For example, Trp53R172H mutations (the murine homolog of TP53R175H, the most common human TP53 variant) enhance metastatic spread relative to deletion mutations in mouse models of advanced pancreatic ductal adenocarcinoma (PDAC). To further explore the differential functions of p53 point and deletion mutants in cancer progression, we performed a rigorous comparative analysis of Trp53 alleles in vivo using Mosaic Analysis with Double Markers (MADM) in mice. MADM uses stochastic mitotic recombination to induce two genotypically distinct daughter cells - created at 1-to-1 ratios - expressing different Trp53 variants dependent on the genotype of the mouse (+/+ vs. -/-, R172H/R172H vs. +/+, R172H/R172H vs. -/-) and simultaneously label them with unique genetically encoded fluorescent markers (TdTomato vs. GFP). We integrated MADM into a faithful Kras-driven model of pancreatic tumorigenesis and used fluorescence microscopy to trace subclonal populations with various p53 alleles within the same mouse. By analyzing the ratio of TdTomato+ to GFP+ cells, we studied the functional differences between alleles in driving pancreatic cancer at various stages of progression. We found that Trp53−/− cells exhibited greater tumor initiation of preinvasive pancreatic intraepithelial neoplasia (PanINs) and early PanIN cell expansion compared to Trp53+/+ cells. Surprisingly, Trp53R172H/R172H cells were comparable in number to Trp53+/+ cells in early PanINs but were outcompeted by Trp53−/− cells.In contrast, both Trp53R172H/R172H and Trp53−/− cells were capable of facilitating the transition to advanced PDAC with comparable survival times. These phenotypic differences imply that p53R172H retains tumor suppressive properties in early pancreatic tumorigenesis, but similar to the loss of p53, it is incapable of constraining progression to advanced disease, arguing that p53R172H is a separation of function mutation in vivo. Ongoing studies examining the molecular differences between Trp53 alleles by fluorescence-activated cell sorting and RNA-sequencing will shed further light onto the underlying mechanisms that explain these phenotypic differences. Citation Format: Andy Tang, Sherry Agabiti, Hannah Chung, Mandar Deepak Muzumdar. Comparative analysis of TP53 alleles in 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 1262.

Abstract 4980: Genomic and clinical characteristics of advanced pancreatobiliary cancer, stratified by KRAS mutation status

Abstract Mutations in KRAS are common in pancreatobiliary cancer, occurring in 90% of advanced pancreatic ductal adenocarcinomas (PDAC) and 20% of advanced cholangiocarcinomas (CCA). We analyzed clinico-genomic databases to evaluate the hypothesis that KRAS mutation status defines subsets of PDAC and CCA with similar genomic characteristics and clinical behavior. Using the genomic data of PDAC and CCA from AACR Project GENIE Cohort version 14.0-public, we analyzed the genomic landscape of four cohorts of pancreatobiliary cancer: KRAS mutated PDAC, KRAS wild-type PDAC, KRAS mutated CCA, and KRAS wild-type CCA. Excluding KRAS mutations, there were 53 gene alterations observed in &amp;gt;2.5% of cases in at least one of the four cohorts. The three most common gene alterations in each cohort were; TP53, SMAD4, and CDKN2A mutations (KRAS mutated PDAC), TP53, ARID1A, and SMAD4 mutations (KRAS wild-type PDAC), TP53 mutation, CDKN2A deletion and SMAD4 mutation (KRAS mutated CCA), and TP53, ARID1D and IDH1 mutations. (KRAS wild-type CCA) The similarity of gene alteration patterns was evaluated by principal component analysis (PCA) 3D plot and calculation of average Euclidean distance. The PCA plot suggested heterogeneous genomic profiles in KRAS wild-type CCA in contrast to relatively monotonous profiles in KRAS mutated PDAC. The average Euclidean distance between KRAS mutated CCA and KRAS wild-type CCA was significantly longer than that between KRAS mutated CCA and KRAS mutated PDAC (2.00 vs. 1.89, p &amp;lt; 0.001), suggesting that KRAS mutated CCA is more genomically related to KRAS mutated PDAC than KRAS wild-type CCA. The average Euclidean distance between KRAS mutated PDAC and KRAS wild-type PDAC was significantly shorter than that between KRAS wild-type CCA and KRAS wild-type PDAC. To compare the clinical characteristics of the four cohorts, we evaluated the data of patients with stage IV pancreatobiliary cancer, using cBioPortal. The number of cases in each cohort was 1544 (KRAS mutated PDAC), 121 (KRAS wild-type PDAC), 91 (KRAS mutated CCA), and 459 (KRAS wild-type CCA). Median overall survival (OS) was 14.7, 21.5, 10.7, and 15.4 months, respectively. Compared to KRAS wild-type CCA, KRAS mutated CCA had a significantly shorter OS (hazard ratio [HR] = 1.45, 95% confidence interval [CI] = 1.12 - 1.89). The OS of KRAS mutated CCA was shorter than KRAS mutated PDAC (HR 1.32, 95% CI 1.03 - 1.68). KRAS wild-type PDAC had a significantly longer OS compared to KRAS mutated PDAC. (HR 0.72, 95% CI 0.57 - 0.92) In conclusion, KRAS mutated CCA has a poor OS and a genomic landscape distinct from KRAS wild-type CCA; it is genomically more similar to KRAS mutated PDAC. KRAS wild-type PDAC has a better OS than KRAS mutated PDAC, though it was not genomically similar to KRAS wild-type CCA. Therapeutic approaches stratified by KRAS mutation status should be considered for pancreaticobiliary cancers. Citation Format: Hirotaka Miyashita, Parth S. Shah, Gabriel A. Brooks. Genomic and clinical characteristics of advanced pancreatobiliary cancer, stratified by KRAS mutation status [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 4980.

Abstract 2079: Tumor-derived fibrinogen promotes pancreatic ductal adenocarcinoma progression

Abstract Background: Hypercoagulability is a common clinical manifestation in patients with cancers, especially in pancreatic ductal adenocarcinoma (PDAC). Over 20% of PDAC patients with advanced-stage and worse prognosis undergo a venous thromboembolism (VTE) incidence. Fibrinogen (FG) may contribute to VTE due to its high expression in advanced PDAC tumors. Here, we set to determine the biological roles of tumor-derived FG in PDAC. In addition, our previous study showed that Von Willebrand Factor (VWF) A2 domain can effectively bind to FG and reduce platelet clot formation. Therefore, the functional roles of A2 on FG in PDAC were also studied. Methods: The correlation between survival rate and FG expression in PDAC was analyzed using RNAseq profiles of 149 PDAC patient samples from the TCGA database. PDAC subtyping of Baylor College of Medicine (BCM) PDAC patient-derived xenograft (PDX) cohort was performed using RNAseq data according to Moffitt’s criteria. The FG (three chains FGA, FGB, FGG) overexpression (OE) and knock-out (KO) PDAC cell lines were established. The gene expression and biological functions of FG were performed in PDX and cell lines using IHC and immunoblot assays. The FG effect on PDAC progression in vivo was studied in mouse models. Results: TCGA analysis showed that elevated tumor-derived FG gene expression is significantly correlated with worse overall survival and disease-free survival rates in PDAC patients. PDX lines RNAseq analysis clearly separated BCM PDAC PDXs into two subtypes: basal-like and classical PDACs. Basal-like PDXs showed significantly stronger FG staining than that in classical ones. Compared to the classical subtype, the basal-like subtype showed significantly upregulated genes that are associated with the epithelial-mesenchymal transition (EMT), IL6/JAK/STAT3, and TNFα signaling pathways. Accordingly, basal-like subtype PDAC exposed to IL6 or TNFα significantly increased FG and FG receptor expression with activated STAT3 and AKT pathways and elevated EMT markers, whereas classical subtype cells have minimal changes. In addition, we found that the FG-OE cells exhibit enhanced cell proliferation and migration properties whereas FG-KO cells reduced the effects. Consistent with in vitro data, FG-OE PDAC showed significantly higher tumor burdens than that of control PDAC in both orthotopic and subcutaneous PDAC mouse models. Furthermore, A2 protein treatment can effectively block the FG function and dramatically inactivate the FG-induced EMT process and AKT signaling pathway. Conclusions: Tumor-derived fibrinogen is upregulated in a basal-like subtype of PDAC cells and may contribute to tumor growth and metastasis by activating aberrant signaling pathways and promoting EMT. Our findings imply that elevated fibrinogen in PDAC could contribute to tumor progression and the A2 protein which target to fibrinogen may be a promising therapy for basal-like subtype PDAC. Citation Format: Dongliang Liu, Lisa Brubaker, Yichi Niu, Emily LaPlante, George Van Buren, Aleksandar Milosavljevic, Changyi Chen, Chenghang Zong, Miguel Cruz, Qizhi Yao. Tumor-derived fibrinogen promotes pancreatic ductal adenocarcinoma progression [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 2079.

Abstract 6649: Tumor treating fields (TTFields) induce an anti-tumor immune response in a pancreatic cancer mouse model

Abstract Background: Pancreatic ductal adenocarcinoma (PDAC) is a deadly malignancy with few therapeutic options. Tumor Treating Fields (TTFields) are low-intensity electric fields that disrupt cellular processes critical for cancer cell division and tumor progression and are approved for the treatment of glioblastoma and pleural mesothelioma. A phase 3 clinical trial is in progress to test the efficacy and safety of TTFields concomitant with standard-of-care gemcitabine and nab-paclitaxel (GnP) as front-line treatment of locally advanced PDAC. TTFields have been shown to induce immunogenic cell death (ICD) in cancer cells and elicit a systemic anti-cancer immune response. Accordingly, the benefit of applying TTFields together with immune checkpoint inhibitors (ICI) was demonstrated in a phase 3 study in patients with non-small cell lung carcinoma. This preclinical study investigated TTFields-induced immune responses in PDAC. Methods: An orthotopic PDAC tumor model was established by inoculating 4 × 105 Panc02 pancreatic cancer cells with stable luciferase expression into the pancreas tail of immune-competent C57BL/6 mice. The mice were randomized into four groups following bioluminescence detection of tumor volume: control, TTFields (150 kHz, 10 days), GnP (50 mg/kg for each drug, i.p. injected once a week for a total of two administrations), and GnP + TTFields. At the end of treatment, tumor volume was measured using caliper, and blood was collected for spectral flow cytometry-based immunophenotyping and ELISA testing for the ICD marker HMGB-1. In vitro, Panc02 cells were treated for 72h with TTFields (150 kHz, 1.62 V/cm RMS) and examined by flow cytometry for apoptosis and ATP secretion (using quinacrine staining) and surface exposure of calreticulin. Results: TTFields markedly reduced the tumor size in Panc02 tumor-bearing mice compared to control mice. Analysis of peripheral blood effector (CD62L-CD44+) and central (CD62L+CD44+) memory T cells demonstrated the induction of circulating effector-memory cytotoxic CD8+ T cells. Additionally, serum HMGB-1 concentrations were significantly elevated in mice treated with TTFields compared to control mice, implying the involvement of ICD in the response to TTFields. In vitro, TTFields application induced apoptosis of Panc02 cells and increased ICD, as indicated by increased surface exposure of calreticulin and ATP depletion. When TTFields were used in Panc02 tumor bearing mice concomitantly with GnP, a substantial reduction in tumor size was detected, and a complete tumor regression was observed in a number of mice. Conclusions: Our results suggest that TTFields may enhance the effects of standard-of-care chemotherapy for the treatment of PDAC. Furthermore, TTFields were shown to induce ICD and activate an antitumor immune response in PDAC, supporting future studies evaluating the efficacy of TTFields together with ICI in PDAC. Citation Format: Tal Kan, Tharwat Haj Khalil, Yiftah Barsheshet, Tali Voloshin, Avital Vorontsov, Boris Brant, Lilach Koren, Roni Blatt, Shay Cahal, Efrat Zemer-Tov, Rom Paz, Anat Klein-Goldberg, Catherine Tempel Brami, Sara Jacobovitch, Alexandra Volodin, Bella Koltun, Cfir David, Adi Haber, Moshe Giladi, Uri Weinberg, Yoram Palti. Tumor treating fields (TTFields) induce an anti-tumor immune response in a pancreatic cancer mouse model [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 6649.

Abstract 3181: Immune modulatory activity of radio-sensitizing gold nanoparticle

Abstract Radiation therapy (RT) is frequently used in the neoadjuvant setting in borderline resectable and some resectable pancreatic ductal adenocarcinoma (PDAC) and in the definitive setting in locally advanced PDACs which is third leading cause of cancer associated death. Higher doses of RT improve overall treatment outcomes but increasing the dose significantly above 50Gy in standard 2Gy fractions risks profound gastrointestinal (GI) toxicity. Additionally, genotoxic stress such as RT, can induce CXCL12 secretion by cancer associated fibroblast (CAFs) and overexpression of CXC motif chemokine receptor 4 (CXCR4) in cancer cells. CXCL12-CXCR4 downstream signaling results in immune suppression and consequent enhanced tumor growth and metastasis and poor prognosis in PDAC. To overcome these clinical challenges, we have developed multimodal gold nanoparticle constructs (GNPs) by functionalizing the CXCR4 antagonists to (i) bind to CXCR4 and mediate GNP internalization, (ii) abolish the feedback immune inhibitory signals mediated by CXCR4 overexpression, and (iii) enhance therapeutic benefit of radiation. To achieve these multimodal activities, we have covalently attached the CXCR4 antagonist, AMD070, to thiol-terminated polyethylene glycol (PEG) to synthesize AMD-PEG which was then conjugated with GNPs to produce AMD-PEG-GNP. In our experiment AMD-PEG-GNP has successfully inhibited CXCL12-CXCR4 downstream signalling such as reduction of ERK phosphorylation in PDAC cells. To analyze the radiosensitization role of GNP nanoconjugates, PDAC cells were incubated with AMD-PEG, PEG-GNP and AMD-PEG-GNPs for 4 hours and then treated with increasing doses of radiated, from 1-4Gy. AMD-PEG-GNP demonstrated a systematic enhancement on reactive oxygen species (ROS) production and downregulation of a colony formation. Collectively, the results from in vitro study with PDAC cells confirm that the nanoconjugate with AMD070 enhances radio-cytotoxicity and impair CXCL12-CXCR4 downstream signaling. Hence AMD-PEG-GNP has strong merit to enhance radiation dose locally and simultaneously restrict RT induced immunosuppression in PDAC. Citation Format: Tanmay Kulkarni, Shamit Dutta, Hazel Parent, Karington Perry, Yuri Mackeyev, Santanu Bhattacharya. Immune modulatory activity of radio-sensitizing gold nanoparticle [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 3181.

Abstract 7506: Comprehensive mutational profile of true single circulating tumor cells compared with CtDNA in advanced pancreatic adenocarcinoma

Abstract Introduction: Pancreatic ductal adenocarcinoma (PDAC) is aggressive malignancy characterized by 5-year survival rate of &amp;lt;10%. Comprehending PDAC's mutational landscape through NGS-based assays, acquiring representative tumor tissue biopsies remains arduous. Single circulating tumor cell (sCTC) genomics could provide clinically relevant personalized diagnostics. Here we demonstrate comparative analysis of sCTCs genomics and ctDNA outcomes in paired advanced PDAC patients. Methods: Retrospectively, 25 live sCTCs and sCTC clusters were isolated from 10 advanced PDAC patients' blood using OncoRadar platform consisting glass beads conjugated with antiEPCam antibodies, tuned for releasing CTCs, without cell fixing, an assay in 96 well plate. Whole genomes from sCTCs were amplified using random degenerate primer-based PCR. Amplified genomes and paired ctDNA were subjected to CGP using clinical assay OncoIndx® to identify patient-specific genomic alterations in sCTC and paired ctDNA samples. The raw sequence alignment and variant calling was performed using iCare software®. Results: Live 25 sCTCs and 8 CTC clusters were isolated (≥2 CTCs). Mutational profiling revealed multiple pathogenic (P) and likely pathogenic (LP) variants. sCTCs exhibited at least twice as many P variants compared to paired ctDNA samples, with CHD4, FGFR2, and HNF1α being the most common. The mutational profile of sCTCs showed concordance with at least one variant in paired ctDNA, and was enriched in dysregulated cytoskeleton and cell migration machinery. Specifically, COL7A, KIF5B, and RHOA mutations were prevalent in almost all sCTCs, with exclusive mutations (KIF5B and RHOA) in some cases. KRAS P variants were exclusive to 50% of ctDNA samples, paired sCTCs exhibited NRAS P variants. RAS isoforms were observed in 70% of sCTCs. Gene amplification occurred in CCND1/2, FGFR2, and ERBB2 in 90% of sCTCs, with CCND1 amplification more prevalent in sCTC clusters. Mutations in epigenetic repressors (HDAC1, KDM2B) were ubiquitous in sCTCs, co-occurring with DDR pathway mutations (F test, P 0.003, OR 11). Loss-of-function BRCA mutations were detected in 60% of sCTCs, and were absent in paired ctDNA. Additionally, 70% of sCTCs exhibited therapy-resistant variants (NF1, STK11, ARID1A, and PIK3CA), contrasting with a 10% frequency in paired ctDNA. Conclusions: Genomic profile of sCTCs in advanced PDAC patients revealed a complex mutational landscape, providing additional clinically relevant insights that complemented ctDNA findings. sCTCs exhibited greater tumor mutational heterogeneity compared to paired ctDNA samples, and detected additional actionable pathogenic variants. Results suggest that sCTCs may offer therapeutically relevant molecular information for advanced PDAC patients for whom tissue is unavailable and ctDNA fails to provide actionable therapy options. Citation Format: Jayant Khandare, Atul Bharde, Ganesh Khutale, Saloni Andhari, Richa Deshpande, Kanchan Hariramani, Madhura Basavalingegowda, Vikas Jadhav, Mohan Uttarwar, Gowhar Shafi. Comprehensive mutational profile of true single circulating tumor cells compared with CtDNA in advanced pancreatic 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 7506.

Assessing Endoscopic Ultrasound-Guided Radiofrequency Ablation in Unresectable Pancreatic Ductal Adenocarcinoma: A Single-Center Historic Cohort Study.

/aims: Endoscopic ultrasound-guided radiofrequency ablation (EUS-RFA) has emerged as an alternative for the local treatment of unresectable pancreatic ductal adenocarcinoma (PDAC). We aim to assess the feasibility and safety of EUS-RFA in patients with unresectable PDAC. The following was a historic cohort compounded by locally advanced (LA) and metastatic (m) PDAC naïve patients, who underwent EUS-RFA between October 2019 to March 2022. EUS-RFA was performed with a 19-g needle electrode with a 10 mm active tip for energy delivery. Study primary endpoints were feasibility, safety, and clinical follow-up; secondary endpoints were performance status (PS), local control (LC) and overall survival (OS). Twenty-six patients were selected: 15/26 LA-PDAC and 11/26 mPDAC. Technical success was achieved in all patients with no major adverse events. Six months after EUS-RFA, OS was 11/26 (42.3%), with significant PS improvement (P=.03). LC was achieved, with tumor reduction from 39.5 to 26 mm (P=.04). Post-treatment hypodense necrotic area was observed at six-month follow-up in 11/11 alive cases. Metastatic disease was a significant factor for OS worsening (HR 5.021; IC 95% 1.589 - 15.87; P=.004) CONCLUSIONS: EUS-RFA of pancreatic adenocarcinoma is a minimally invasive and safe technique that may have an important role as targeted therapy for local treatment of unresectable cases, as well as an alternative for poor surgical candidates. Also, RFA may play a role in downstaging cancer with potential OS increase in non-metastatic cases. Large prospective cohorts are required to evaluate this technique in clinical practice.