Abstract B014: Histopathological assessment of irreversible electroporation in ex vivo perfused human pancreatic cancer

Abstract Background: Irreversible electroporation (IRE) is a non-thermal ablation technique that creates nanoscale pores in the plasma membrane, inducing apoptosis while sparing surrounding connective tissue. While IRE is being increasingly explored in pancreatic ductal adenocarcinoma (PDAC), most data come from animal models or retrospective human studies with limited histological correlation. There is little published evidence describing real-time histological changes in human pancreatic cancer following IRE, particularly in freshly resected perfused tissue. Objective: This study aimed to evaluate the immediate histological response of human PDAC to IRE using a perfused ex vivo organ model, quantifying both apoptosis and necrosis across time and voltage parameters. Methods: Freshly resected human PDAC specimens from patients undergoing surgery were perfused with matched red blood cells and ablated using clinical-grade NanoKnife IRE equipment at voltages of 1400, 1800, and 2000 V/cm. Biopsies were collected from ablated and non-ablated zones at baseline and at 5, 10, 15, 20, 25, and 30 minutes post-IRE. Tissues were fixed in 10% neutral-buffered formalin and paraffin-embedded for histological analysis. Apoptosis was quantified using cleaved caspase-3 staining and reported as an apoptotic index (AI). Necrosis was evaluated using a necrotic area fraction (NAF), calculated from H&E-stained sections with ImageJ. Heatmaps were generated to visualise temporal and spatial changes. Results: Ablated samples demonstrated a consistent increase in both AI and NAF across all voltages. At 2000 V/cm, AI increased from 0.85% at baseline to 15.62% by 30 minutes. In contrast, non-ablated regions showed only marginal increases (from 0.47% to 2.74%). Similarly, NAF in ablated tissue reached a peak of 32.7% at 30 minutes post-ablation, while non-ablated regions remained under 6%. Higher voltages were associated with earlier and more pronounced histological changes. Inter-sample variability was evident, likely reflecting tumour heterogeneity and prior neoadjuvant therapy. Controls showed limited apoptotic or necrotic activity. Conclusion: This study provides the first systematic characterisation of early histological changes following IRE in perfused human PDAC. Quantitative image-based analysis of AI and NAF revealed time- and voltage-dependent increases in cell death. These findings support the feasibility of ex vivo perfusion as a platform for mechanistic interrogation of ablative therapies and underscore the need for further studies optimising treatment parameters for clinical translation. Citation Format: Zainab L. Rai, Morenike Magbagbeola, Agostino Stilli, Danail Stoyanov, Brian R. Davidson. Histopathological assessment of irreversible electroporation in ex vivo perfused human pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research—Emerging Science Driving Transformative Solutions; Boston, MA; 2025 Sep 28-Oct 1; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2025;85(18_Suppl_3):Abstract nr B014.