Resectable Pancreatic Cancer Research Articles

Trajectory Analysis of Healthcare Use Before and After Gastrointestinal Cancer Surgery.

Frailty correlates with worse post-operative outcomes and higher surgical costs, but the long-term impact on healthcare utilization remains ill-defined. We sought to evaluate patterns of healthcare utilization pre- and post-surgery among patients with gastrointestinal cancer and characterize the association with frailty. Data on patients who underwent surgical resection for liver, biliary, pancreatic, colon and rectal cancer were obtained from the 2005-2020 SEER-Medicare database. Frailty was assessed using the claims-based frailty index. Group-based trajectory modelling identified clusters of patients with discrete patterns of healthcare utilization. Multivariable regression was performed to predict cluster membership based on preoperative factors, including frailty. Among 66,684 beneficiaries, four distinct utilization trajectories based on data from 12 months before and after surgery were identified. Following a surge in utilization during the month of surgery, most patients reverted to pre-surgery baseline utilization (low: n=6588, 9.9%; moderate: n=17,627, 26.4%; high: n=29,850, 44.8%). However, a notable trajectory involving 12,619 (18.9%) patients was identified, wherein surgery precipitated a transition from a "low" pre-surgery utilization state to a "high" utilization state post-surgery. Frail patients were more likely to be among those individuals who transitioned to high utilizers (low: 4.2% vs. vs. transition: 12.6% vs. high: 7.5%; p<0.001). On multivariable analysis incorporating preoperative variables, frailty was associated with high group trajectory membership (ref: least and moderate; highest: OR 4.90, 95%CI 4.49-5.35; p<0.001). Patients with gastrointestinal cancer demonstrated distinct clusters of healthcare utilization after surgical resection. Preoperative predictive models may help differentiate different health care utilization trajectories to help tailor care for patients in the postoperative period.

Clinical usefulness of C-reactive protein-albumin-lymphocyte (CALLY) index as a prognostic biomarker in patients undergoing surgical resection of pancreatic cancer.

The C-reactive protein-albumin-lymphocyte (CALLY) index, which simultaneously evaluates the nutritional, immunological, and inflammatory statuses, is a new prognostic biomarker in patients with various cancers; however, no study has reported the clinical significance of the CALLY index in patients with pancreatic cancer. This study aimed to investigate whether the preoperative CALLY index is a prognostic biomarker in patients undergoing surgical resection of pancreatic cancer. We retrospectively enrolled 461 patients with pancreatic cancer who underwent surgical resection between January 2013 and December 2022. The overall survival (OS) and relapse-free survival (RFS) rates were calculated using the Kaplan-Meier method. Univariate and multivariate analyses were performed using Cox proportional hazards regression models. The optimal cut-off value for the preoperative CALLY index was 1.9. In the low CALLY group, patients were older (p = 0.012), more patients underwent pancreaticoduodenectomy (p = 0.002), the median tumor size was larger (p < 0.001), more patients had pathologically confirmed metastatic lymph nodes (p = 0.015) and worse pathological stage (p = 0.015), and fewer patients received adjuvant chemotherapy (p = 0.003). A low CALLY index was associated with decreased OS (22.1 vs. 37.9months) and RFS (12.4 vs. 16.4months). Univariate and multivariate analyses showed that the preoperative CALLY index was an independent prognostic factor for OS (p < 0.001) and RFS (p = 0.045). The preoperative CALLY index is a prognostic biomarker for both OS and RFS in patients undergoing surgery for pancreatic cancer.

Increased Proportion of the Squamous Cell Carcinoma Components Is Associated with Aggressive Behavior and a Worse Prognosis in Resected Pancreatic Adenosquamous Carcinoma.

Pancreatic adenosquamous carcinoma (PASC) is a subtype of pancreatic cancer with a poorer prognosis than pancreatic ductal carcinoma (PDAC). The pathogenesis of this histological subtype has not been fully explained due to its rarity. Of the 245 patients who underwent pancreatic resection for pancreatic cancer, six (2.3%) were diagnosed with PASC. They were retrospectively allocated to Group A (≥ 50% adenocarcinoma components) or Group S (≥ 50% squamous cell carcinoma components). The six patients with PASC were all males between the ages of 63 and 77years, with tumors of 12 to 52mm in diameter. Tumors were located in the pancreatic head (n = 2) and the pancreatic tail (n = 4). Relative to Group A, all three patients in Group S had larger tumors diameters, ≥ 40mm with invasion to other organs. Cancer-specific survival of Group S was worse than that of the PDAC group (median survival, 1.5years vs. 4.1years). All patients in Group A were alive at the end of follow-up. Recurrence-free survival of Group S was inferior to that of the PDAC group (median survival, 0.2years vs. 1.8years; Group A, not defined). Immunohistochemistry revealed the MIB-1 positivity rate in squamous cell carcinoma regions was 1.8 times higher than that in adenocarcinoma regions in the same specimens. In PASC patients, an increased proportion of squamous cell carcinoma components was associated with aggressive behavior and a worse prognosis. This was due to the high MIB-1 positivity rate of squamous cell carcinoma components.

Targeting Human Pancreatic Cancer with a Fluorophore-Conjugated Mucin 4 (MUC4) Antibody: Initial Characterization in Orthotopic Cell Line Mouse Models.

Background/Objectives: Pancreatic cancer is the third leading cause of death related to cancer. The only possible cure presently is complete surgical resection; however, this is limited by difficulty in clearly defining tumor margins. Enhancement of the visualization of pancreatic ductal adenocarcinoma (PDAC) tumor margins using near-infrared dye-conjugated tumor-specific antibodies was pioneered by using anti-CEA, anti-CA19.9, and anti-MUC5AC in orthotopic mouse models of pancreatic cancer. Recently, an antibody to Mucin 4 (MUC4) conjugated to a fluorescent probe has shown promise in targeting colon tumors in orthotopic mouse models. Methods: In the present study, we targeted pancreatic cancer using an anti-MUC4 antibody conjugated to IRDye800 (anti-MUC4-IR800) in orthotopic mouse models. Two pancreatic cancer human cell lines were used, SW1990 and CD18/HPAF. Results: Anti-MUC4-IR800 targeted the two pancreatic cancer cell line tumors in orthotopic mouse models with high tumor-to-pancreas ratios and high tumor-to-liver ratios, with greater targeting seen in SW1990. Conclusions: The present results suggest anti-MUC4-IR800's potential to be used in fluorescence-guided surgical resection of pancreatic cancer.

Assessing Influence of Mismatch Repair Mutations on Survival in Patients After Resection of Pancreatic Ductal and Periampullary Adenocarcinoma.

Background: Pancreatic ductal adenocarcinoma (PDAC) is the third leading cause of cancer-related deaths in the United States. Previous studies have indicated that microsatellite instability and deficient mismatch repair (MMR) may be associated with improved survival in patients with pancreatic cancer. Here, we aim to investigate the impact of deficient MMR (dMMR) status on oncologic outcomes in patients after resection of PDAC and periampullary adenocarcinoma. Methods: This is a single-institution, retrospective study based on a prospectively maintained database. Pancreatic ductal adenocarcinoma (N = 342) and periampullary adenocarcinoma patients (N = 76) who underwent pancreatic resection surgery between 2016 and 2021 were included. Immunohistochemistry staining results of MMR proteins and next-generation sequencing data were recorded. Cancer-type dependent Cox regression analyses were performed to assess overall and disease-free survival, which was complemented with a 1:2 propensity-score matching for each of the cancer types in order to compare oncologic outcomes. Results: A total of 418 pancreatic cancer patients were included in the analysis. Fifteen patients (3.5%) were diagnosed as dMMR (PDAC N = 7 and periampullary adenocarcinoma N = 8). Cox regression modeling of dMMR status interaction with TNM staging and cancer type revealed that dMMR status strongly improves overall survival (p < 0.05). After propensity-score matching, Cox regression identified dMMR status as a significant marker of improved overall survival (HR = 0.27, 95%CI 0.09-0.88, p = 0.029). Conclusions: Overall, our findings suggest that dMMR status is associated with markedly improved survival outcomes in patients after resection of pancreatic and periampullary cancer. Future large-scale studies are needed to further validate this finding.

Oncological Outcomes of Open Versus Minimally Invasive Surgery for Ductal Adenocarcinomas of Pancreatic Head: A Propensity Score Matching Analysis.

Minimally invasive pancreatic resections (MIPRs) have been shown to be safe and feasible, but there is still a lack of high-level evidence on oncological outcomes for cephalic pancreatic ductal adenocarcinoma (PDAC). The aim of this study was to compare the oncological outcomes of patients undergoing MIPR and open pancreatic resection (OPR) for pancreatic head cancer in a single high-volume center. Data from a prospectively collected database of patients who underwent radical-intent surgery for resectable and borderline resectable PDAC of the head at our institution between January 2013 and May 2023 were retrieved and analyzed, comparing the surgical and oncological outcomes of MIPR and OPR, using a propensity score matching analysis. In the study period, 220 patients were selected. After matching, a total of 81 MIPRs and 81 OPRs were compared. No difference was found regarding R0 rate (OPR 83.9% vs. MIPR 74.1%, p = 0.122). Median overall survival (24 and 31 months for the OPR and MIPR groups, respectively; log rank p = 0.665) and disease-free survival (12 and 21 months for the OPR and MIPR groups, respectively; log rank p = 0.118) did not differ between the groups. The MIPR group was associated with a greater number of harvested lymph nodes (22 vs. 16, p = 0.0008), longer operative time (565 vs. 420 min, p < 0.0001), and shorter length of stay (12 vs. 18 days; p = 0.0001). No differences between the groups were found regarding all other postoperative and pathological outcomes. Regarding oncological outcomes, MIPR appeared to be comparable to OPR for treating patients with PDAC of the head. Despite an increased operative time, MIPR was associated with a greater number of LNs harvested and a shorter length of stay.

The diagnostic value of combining preoperative serum CA19-9, ALBI score, and 18F-FDG PET/CT imaging in preoperative resectability of pancreatic cancer.

Pancreatic cancer is an increasing cause of cancer-related mortality, with persistently low survival rates. We investigated the clinical diagnostic value of the combination of preoperative serum carbohydrate antigen 19-9 (CA19-9), albumin-bilirubin (ALBI) score, and 18F-fluoro-2-deoxy-d-glucose PET integrated with computed tomography (18F-FDG PET/CT) imaging in pancreatic cancer preoperative resectability. This study included 143 pancreatic cancer patients, including 68 preoperative resectable and 75 preoperative unresectable pancreatic cancer patients. Meanwhile, 67 patients with non-pancreatic cancer were included as the control group. The clinical data were collected. Serum CA19-9 level was measured by ELISA. The levels of total bilirubin and albumin were determined using a biochemical analyzer, with the ALBI score calculated. All patients underwent 18F-FDG PET/CT imaging. The consistency of the diagnosis was evaluated by the Kappa test. Logistic univariate and multivariate regression analyses were performed. The diagnostic efficacy of these parameters was evaluated using receiver operating characteristic (ROC) curves, and the optimal ROC curve thresholds were obtained using the Youden index. The preoperative serum CA19-9 and ALBI score of patients with preoperative resectable pancreatic cancer were increased, which helped diagnose preoperative resectable pancreatic cancer. 18F-FDG PET/CT imaging had diagnostic value for preoperative resectable pancreatic cancer. Preoperative serum CA19-9, ALBI score, and 18F-FDG PET/CT imaging were independent influencing factors for pancreatic cancer preoperative resectability, and their combination had higher diagnostic value for preoperative resectable pancreatic cancer than any single of these indexes. The combination of preoperative serum CA19-9, ALBI score, and 18F-FDG PET/CT imaging had high diagnostic value for pancreatic cancer preoperative resectability.

Current evidence for neoadjuvant therapy in resectable pancreatic cancer

Current evidence for neoadjuvant therapy in resectable pancreatic cancer

P61-1 Prognostic value of metabolic tumor volume in patients with resectable pancreatic cancer: a meta-analysis

P61-1 Prognostic value of metabolic tumor volume in patients with resectable pancreatic cancer: a meta-analysis

Progress in the diagnosis and treatment of pancreatic cancer with acute pancreatitis as the initial symptom

Pancreatic cancer patients often have complaints such as upper abdominal pain and obstructive jaundice when seeking diagnosis and treatment. However, acute pancreatitis as a rare initial clinical manifestation of pancreatic cancer is often overlooked in clinical practice. This oversight often leads to a delayed diagnosis of pancreatic cancer, uncertainty in treatment strategies, and significantly affects patients' quality of life and prognosis. Therefore, early diagnosis and treatment, and active follow-up are crucial for patients with acute pancreatitis as an initial symptom of pancreatic cancer. Upon admission to such patients, common causes such as gallstones, alcohol abuse, and hyperlipidemia should be initially ruled out. Evaluation with tumor markers, CT and MRI, and endoscopic ultrasound are essential to confirm the diagnosis of pancreatic cancer. For patients with mild pancreatitis, managing peripancreatic inflammation first before radical resection of pancreatic cancer could reduce postoperative complications. Moreover, pancreatitis serves as a high-risk factor for pancreatic cancer, so it is crucial to closely follow up patients with pancreatitis to detect pancreatic cancer early.

Should we resect distant metastases?—reconsidering radical resection of pancreatic cancer with liver metastases

Should we resect distant metastases?—reconsidering radical resection of pancreatic cancer with liver metastases

Robot-Assisted Pancreaticoduodenectomy Using the Anterior Superior Mesenteric Artery-First Approach for Pancreatic Cancer.

The superior mesenteric artery (SMA)-first approach for pancreatic cancer (PC) is common surgical technique in pancreaticoduodenectomy. To date, few studies have reported SMA-first approach in robot-assisted pancreaticoduodenectomy (RPD). Herein, we present the anterior SMA-first approach for PC during RPD. A 75-year-old man with resectable PC underwent RPD after neoadjuvant chemotherapy. As pancreatic head tumor contacted with the superior mesenteric vein (SMV), the anterior SMA approach was applied. After the mesenteric Kocher maneuver, the jejunum was divided and the left side of the SMA was dissected. Subsequently, the anterior plane of the SMA was dissected. Following the division of branches from the mesenteric vessels, the SMA was taped, and the circumferential dissection around the SMA was performed to detach the pancreatic neck from the SMA completely. Finally, the dissection between the SMV and the tumor was performed under vascular control to remove the specimen. The anterior SMA-first approach can be optional in patients with PC undergoing RPD. This unique approach allows for the circumferential dissection around the SMA during RPD.

Intraoperative guidance of pancreatic cancer resection using a toll like receptor 2 targeted fluorescence molecular imaging agent.

To increase the achievement of negative R0 surgical margins and increase the low survival rates of pancreatic cancer, improvements in assessing tumor margins during surgical resections are needed. This can be accomplished by using pancreatic cancer-targeted fluorescence molecular imaging agents to intraoperatively detect tumor margins in real-time. Since toll like receptor 2 (TLR2) is broadly expressed among many cancer types including pancreatic adenocarcinomas, a high-affinity TLR2-targeted fluorescence molecular imaging agent (TLR2L-800) was developed. We investigate the potential for increased survival by employing real-time intraoperative tumor detection in a preclinical orthotopic human pancreatic xenograft tumor model using TLR2L-800. Three cohorts of nude mice bearing orthotopic human pancreatic xenograft tumors were intravenously injected with TLR2L-800. At 24 h postinjection, one cohort underwent in vivo fluorescence-guided surgical removal of tumors using a real-time fluorescence imaging platform, a second cohort underwent visible light surgery, and a third cohort did not undergo surgery. A fourth, non-tumor-bearing cohort was administered TLR2L-800 with no surgery. At 41 d post-surgery, the survival rates were 53% for the fluorescence-guided surgery group and 0% for both the visible light surgery group and the tumor-bearing no surgery group. The overall 200 d survival rate of 35% for the fluorescence-guided surgery group was significant compared to 0% for the visible light surgery group (p-value=0.0018). This study demonstrates the potential of increasing disease-free survival for patients with pancreatic cancer by increasing the attainment of R0 margins using a novel tumor-targeted lipopeptide ligand-based fluorescence molecular imaging agent, TLR2L-800, during real-time fluorescence-guided surgery.

Comparative Efficacy of 21 Treatment Strategies for Resectable Pancreatic Cancer: A Network Meta-Analysis.

The primary treatment for operable pancreatic cancer (PC) involves surgery followed by adjuvant therapy. Nevertheless, perioperative or neoadjuvant chemotherapy (CT) may be used to mitigate the likelihood of recurrence and mortality. This network meta-analysis (NMA) assesses the comparative efficacy of various treatment approaches for resectable PC. A thorough search was carried out on January 31, 2023, encompassing PubMed/MEDLINE, Cochrane Library, and Embase databases. We incorporated randomized clinical trials (RCTs) that compared surgical interventions with or without (neo)adjuvant or perioperative therapies for operable PC. We conducted a fixed-effects Bayesian NMA. We presented the effect sizes in terms of hazard ratios (HRs) for overall survival (OS) along with 95% credible intervals (95% CrIs). The treatment was deemed statistically superior when the 95% credible interval (CrI) did not encompass a null value (hazard ratio < 1). Treatment rankings were established based on the surface under the cumulative ranking curve (SUCRA). A total of 24 studies were incorporated, comparing 21 treatments with surgery in isolation. Eleven treatments showed superior efficacy compared to surgery alone, with HRs ranging from 0.38 for perioperative treatments to 0.73 for adjuvant 5-fluorouracil. After the exclusion of studies conducted in Asia, it was found that the perioperative regimen of gemcitabine combined with nab-paclitaxel was the most effective regimen (SUCRA, p = 0.99). The findings endorse the utilization of perioperative CT, especially multi-agent CT, as the favored intervention for operable PC in Western nations.

Values of apparent diffusion coefficient in pancreatic cancer patients receiving neoadjuvant therapy

BackgroundTo investigate the values of apparent diffusion coefficient (ADC) for the treatment response evaluation in pancreatic cancer (PC) patients receiving neoadjuvant therapy (NAT).MethodsThis study included 103 NAT patients with histologically proven PC. ADC maps were generated using monoexponential diffusion-weighted imaging (b values: 50, 800 s/mm2). Tumors’ minimum, maximum, and mean ADCs were measured and compared pre- and post-NAT. Variations in ADC values measured between pre- and post-NAT completion for NAT methods (chemotherapy, chemoradiotherapy), tumor locations (head/neck, body/tail), tumor regression grade (TRG) levels (0–2, 3), N stages (N0, N1/N2) and tumor resection margin status (R0, R1), were further analyzed.ResultsThe minimum, maximum, and mean ADC values all increased dramatically after NAT, rising from 23.4 to 25.4% (all p < 0.001): mean (average: 1.626 × 10− 3 mm2/s vs. 1.315 × 10− 3 mm2/s), minimum (median: 1.274 × 10− 3 mm2/s vs. 1.034 × 10− 3 mm2/s), and maximum (average: 1.981 × 10− 3 mm2/s vs. 1.580 × 10− 3 mm2/s). The ADCs between the subgroups of all the criteria under investigation did not differ significantly for the minimum, maximum, or mean values pre- or post-NAT (P = 0.08 to 1.00). In the patients with borderline resectable PC (n = 47), the rate of tumor size changes after NAT was correlated with the pre-NAT mean ADC values (Spearman’s coefficient: 0.288, P = 0.049).ConclusionsThe ADC values of PC increased significantly following NAT; however, the percentage increases failed to provide any predictive value for the resection margin status or TRG levels.

Abstract A053: Interrogating the spatial biology of pancreatic cancer-associated fibroblasts in resected human pancreatic cancer

Abstract Introduction Cancer-associated fibroblasts (CAFs) are key players in the fibrotic tumour microenvironment (TME) of pancreatic cancer. Recent evidence has demonstrated the existence of multiple CAF subtypes, however there is relatively little evidence validating and corroborating these CAF subtypes in resected human pancreatic cancer. Furthermore, the spatial interactions between CAF subtypes and the epithelial and immune compartments of the pancreatic cancer TME is not well understood. Methods We designed and optimised a bespoke 8-plex immunofluorescence panel for the purposes of CAF subtype profiling and elucidation of CAF spatial biology: panCK, FAP, SMA, CTGF, S100A4, IL6, LIF, PDGFR. This was applied to a cohort of n=215 resected pancreatic cancer, well characterised with highly granular clinico-pathological and transcriptomic data through the Australian Pancreatic Cancer Genome Initiative. Spatial analysis was performed with novel computational biology techniques. Results We demonstrate seven CAF subtypes which cluster to form distinct, highly prognostic “enrichment profiles” (EPs). The cold EP represents quiescent CAFs in close proximity to immune cells (multivariate HR 0.45, 95% CI 0.30-0.68, p&amp;lt;0.001), and the fibrotic EP represents activated CAFs in close proximity to epithelial cells (multivariate HR 2.22, 95% CI 1.48-3.35, p&amp;lt;0.001). We also demonstrate the prognostic power of high spatial entropy (loss of tissue architecture, correlating with the fibrotic EP) vs low spatial entropy (preservation of tissue architecture, correlating with the cold EP) (HR 2.22, 95% CI 1.47-3.35, p&amp;lt;0.001). Conclusion We begin to unravel the elusive spatial biology of pancreatic CAFs in a large resected human cohort. We see changes in immune cell infiltrate, modulation of cellular relationships, and greater tissue disorganisation as a result of CAF activation. These features are highly prognostic and we hypothesise they are driven by changes in crosstalk between TME compartments. Current work focuses on application of these techniques to a large resected neoadjuvantly-treated cohort, allowing further interrogation of the notorious fibrotic post-neoadjuvant pancreatic cancer TME. If accepted for presentation we look forward to presenting both cohorts simultaneously. Citation Format: Adam Bryce, Stephan Dreyer, Fieke Froeling, Silvia Martinelli, Rachel Pennie, Leah Officer-Jones, John Le Quesne, David Chang. Interrogating the spatial biology of pancreatic cancer-associated fibroblasts in resected human 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 A053.

Abstract B013: Host phenotype profiling predicts progression to resection in neoadjuvant pancreatic cancer

Abstract Introduction Neoadjuvant chemotherapy offers a modest survival benefit in pancreatic cancer. Current methods for assessing response to chemotherapy are limited to CA19-9 and post- treatment imaging. However, these methods are not without caveats and focus heavily on tumour biology and staging the tumour, without consideration of host biology or staging the host. We sought to explore the relationship between host biology and outcomes in neoadjuvantly- treated pancreatic cancer, and determine the utility of host phenotype profiling as a tool for predicting chemotherapy response and subsequent progression to resection. Methods Host phenotype profiling was performed by measuring body composition (BC) pre- and post- neoadjuvant chemotherapy in a large international pancreatic cancer cohort (n = 301). Patients with resectable or borderline resectable disease were included if they received chemotherapy with neoadjuvant intent. BC was determined with contrast-enhanced CT scans by measuring single-slice L3 cross-sectional area. Results There were significant differences in BC change from baseline to post-treatment between resected (n = 174) and non-resected patients (n = 127). Patients who did not progress to resection exhibited greater loss in all BC compartments vs those who progressed to resection (muscle area -3.4 vs -0.7, visceral fat -10.1 vs -2.1, subcutaneous fat -12.0 vs -1.4, all p &amp;lt; 0.001, median percentage change per 100 days). We used these values to define a adverse and favourable host phenotypes, which significantly correlated with progression to resection (58.8% adverse phenotype, 74.3% favourable phenotype, p &amp;lt; 0.001). The independence of this effect was confirmed in a logistic regression model with well-established clinico-pathological variables including CA19-19 rise (adverse phenotype OR of non-resection 4.57, 95% CI 1.55-13.48, p = 0.006). Conclusion Host phenotype profiling represents a useful addition to an otherwise limited toolbox of methods for assessing treatment response and selecting for surgery in neoadjuvant pancreatic cancer. Clinicians will be familiar with the subjective “gut feeling” of identifying patients in the clinic who are unlikely to be candidates for surgery, and we demonstrate an objective measurement of this. Early identification of patients on an adverse trajectory may highlight those who would benefit from early intervention such as prehabilitation, salvage change of chemotherapy regimen, or nutritional optimization to switch the phenotype from adverse to favourable and reverse adverse host biology. Citation Format: Adam Bryce, Stephan Dreyer, Ross Dolan, Fieke Froeling, Dario Solinas, Alice Cattelani, Antonio Pea, David Chang. Host phenotype profiling predicts progression to resection in neoadjuvant 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 B013.

Abstract B078: A comprehensive spatial atlas of neoadjuvant chemoradiation therapy in resected pancreatic cancer identifies cellular &amp; microenvironmental determinants of persister populations

Abstract Background The molecular pathways involved in the response to radiation therapy (RT) in pancreatic ductal adenocarcinoma (PDAC) remain poorly understood. Despite extensive molecular stratification efforts, improvements in molecularly informed RT-based therapeutic strategies in the neoadjuvant setting have been limited. This study aims to elucidate the adaptive mechanisms and interactions within PDAC to identify new combinatorial therapeutic targets with RT. MethodsWe constructed a high-resolution molecular landscape of the cellular subtypes and spatial communities that constitute PDAC. Single-cell RNA sequencing (scRNA- seq) was performed on 16 PDAC biopsies of matched pre- and post-treatment samples from a Phase I/II dose-escalation clinical trial of pancreatic stereotactic body radiation therapy (SBRT). Additionally, Visium spatial transcriptomics (ST) was conducted on biopsies from primary PDAC patients collected at the time of surgery. These patients received either no neoadjuvant therapy (n = 8) or neoadjuvant chemoradiation (chemoRT) (n = 20). Cell type profiles were determined from scRNA-seq to compare changes in cell type proportions and signatures before and after RT. From these profiles, we employed robust cell type decomposition to analyze cell type signatures in our ST dataset. ResultsChemoRT induced several significant effects compared to controls within the tumor microenvironment, including an increase in the proportion of myofibroblasts, specifically senescent cancer-associated fibroblasts (CAFs), with signatures consistent with immune cell dysfunction. We observed an increase in CD8 and CD4 effector memory cells with RT; however, this occurred alongside a rise in immunosuppressive alternatively activated tumor-associated macrophages. Additionally, RT upregulated pathways related to HIF, cytokine production, B cell proliferation, and negative regulation of lymphocytes. Patients with increased infiltration of NK, memory B, and CD8 effector memory cells demonstrated improved overall survival outcomes. Inference of copy number variations enabled us to identify cancer subclones as either responsive or resistant in matched pre and post RT biopsies. Resistance was characterized by augmented hypoxia, KRAS activation, epithelial- mesenchymal transition, and interferon-gamma response signaling. Conversely, responders exhibited increased oxidative phosphorylation signaling and pathway enrichment associated with cell proliferation and cell cycle progression. Interestingly, RT induced a decrease in cancer cells characterized as harboring a chemoresistant basal-like molecular subtype. ConclusionThrough both longitudinal and therapy stratified tumor biopsies, we were able to observe significant selection pressures on stromal and cancer cells following RT. This includes upregulation of innate and adaptive immune pathways with a compensatory immunosuppressive response driven by myeloid cells and CAFs. This may provide opportunities for development of clinical trials to therapeutically target specific cellular phenotypes and their interactions. Citation Format: Vincent Bernard, Galia Jacobson, Kimal Rajapakshe, Jimin Min, Guangsheng Pei, Daniel Lin, Ayush Suresh, Dadi Jiang, Ching-Wei Tzeng, Manoop S Bhutani, Linghua Wang, Paola A Guerrero, Ethan B Ludmir, Albert C Koong, Anirban Maitra, Cullen M Taniguchi, Eugene J Koay. A comprehensive spatial atlas of neoadjuvant chemoradiation therapy in resected pancreatic cancer identifies cellular &amp; microenvironmental determinants of persister populations [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 B078.

Abstract B040: B cells facilitate lymph node colonization in pancreatic ductal adenocarcinoma

Abstract Pancreatic ductal adenocarcinoma (PDAC) carries a low survival rate. Several factors contribute to its dismal prognosis, including resistance to available therapies and high invasiveness. Lymph nodes act as an early systemic source of circulating malignant cells, allowing their dissemination to other organs early in disease progression. Lymphatic colonization is linked to worse prognosis, and a better understanding of mechanisms regulating lymph node metastasis is clinically needed. To study each step in the metastatic cascade to the lymph nodes, we have developed a mouse co-clinical model of resectable pancreatic cancer. This model mimics the frequency of human PDAC metastatic recurrence, on a similar time scale relative to the lifespans of mice and humans and allows us to investigate very early events in the metastatic cascade. In contrast to the established anti-tumor role of T cells, the role of B cells in cancer immunology is more complex. B cells are a predominant immune population in lymph nodes, but their role in relation to lymph node colonization has never been fully addressed. Using our model of PDAC spontaneous metastasis and a mouse model of B cell depletion, we showed that lymph node metastasis does not form in the absence of B cells. We demonstrated that B cells, but not secreted antibodies, are required for successful lymph node colonization. We also gained evidence that B cells are orchestrating a complex interplay between disseminated cancer cells and other immune cells in the draining lymph node. Particularly, T cells seem to be involved in preventing cancer cell from growing into macro-metastasis only in the absence of B cells. We are now investigating the mechanisms employed by B cells to facilitate this cellular network to facilitate lymph node colonization in PDAC. The ultimate outcome of our work will be the design of effective immune strategies to prevent and treat lymph node dissemination of such a deadly disease. Citation Format: Alice Bertocchi, Megan T Hoffman, Li Qiang, Massiel Morell, Lauren L Hsu, Michael L Dougan, Judith Agudo, Stephanie K Dougan. B cells facilitate lymph node colonization in pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr B040.

Abstract PR-12: The circadian rhythm gene Dec2 regulates multiple components of the antigen presentation pathway to promote pancreatic cancer dormancy by immune evasion

Abstract Metastatic recurrence following curative-intent pancreatic surgery is a major clinical problem as nearly all die of this at both early and latent periods following surgery. While latent recurrences are due to the reactivation of disseminated dormant tumor cells, the mechanisms that regulate dormancy remain unclear. Using a novel model of early-stage resectable pancreatic cancer that mimics early and latent outcomes in patients, we identified Dec2 (bhlh41) a transcriptional repressor and circadian regulator, as upregulated in dormant tumor cells harvested from the liver. Disseminated tumor cells harvest from the livers of latent recurrent mice were Dec2 hi/Ki67lo indicating that these cells are dormant. We confirmed the relationship of Dec2 and Ki67 in human pancreatic cancer using liver tissue specimens from patients with metastatic disease whereby small clusters of metastatic cells were Dec2hi/Ki67lo and larger metastatic tumors were Dec2lo/Ki67hi. To understand the mechanism of Dec2 in dormancy we deleted Dec2 from the tumor cells evaluated them in the resection model and observed a substantial increase in survival after resection due to an immune mediated mechanism as the survival benefit was abrogated in immunodeficient conditions indicating that Dec2 promotes tumor progression through immune mediated mechanism. Dec2 promotes immune evasion by downregulating multiple components of the antigen presentation pathway including proteosome and immunoproteosome genes, MHCI and MHCI chaperones. As Dec2 is a circadian regulator, we evaluated several components of the antigen presentation pathway including proteosome and surface MHCI and found these to display oscillation that was not only anti-phase with Dec2 but resulted in differential T-cell mediated tumor cell killing depending on the time of day. These studies elucidate a new mechanism by which Dec2 regulates cancer dormancy through immune evasion and identifies several novel therapeutic strategies to restore anti-tumor immunity. They also provide the first evidence that antigen presentation is under circadian regulation in pancreatic cancer. Citation Format: Chris Harris, Crissy Dudgeon, Lan Wang, Orjola Prela, Juliana Cazarin de Menezes, Brian Altman, Brian Haab, Chongfeng Gao, Zachary Klamer, Anna Repesh, Subhajyoti De, Darren R Carpizo. The circadian rhythm gene Dec2 regulates multiple components of the antigen presentation pathway to promote pancreatic cancer dormancy by immune evasion [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr PR-12.