Abstract 2153: Preliminary analysis of immune cell profiling to neoadjuvant chemotherapy response in pancreatic cancer patients

Abstract Background: Neoadjuvant chemotherapy (NAT) is used in the clinical setting to improve the chance of surgery for pancreatic cancer (PC) patients. Immune profiling shows great promise for improved prediction of response to chemotherapy, But the role of the immune system of PC remain unclear. This study aimed to identify immune biomarkers for improved prediction of response to chemotherapy. Materials and Methods: Blood samples were collected from 23 pancreatic cancer patients undergoing neoadjuvant chemotherapy (NAT) before (pre, n=23) and during the 2-month follow-up after treatment (post 2M, n=15). Peripheral blood mononuclear cells (PBMC) were isolated from whole blood samples using Ficoll buffer and flow cytometry analyzed using 18 colors-LSRFortessa for immune cell profile. The following fluorescent-labeled antibodies were used: Fixable viability stain 700, Fluorescein isothiocyanate anti-CD3, Brilliant violet (BV) 605 anti CD14, BV510 anti-HLA-DR, BV655 anti-CD123, BV421 anti-CD11c, Brilliant ultraviolet (BUV) anti-CD4, and BV711 anti-CD8. The immune cell profiling in peripheral blood mononuclear cells were analyzed by flow cytometry. Patients were classified as responders (compete response, partial response) or non-responders (stable disease, progressive disease) base on their response to NAT, and their immune cell profiles were compared. Results: The baseline characteristics of the two groups were similar. The median number of NAT cycles was 8 (range, 4-9) in responders and 8 (4-12) cycles in non-responders, respectively. Among various immune cell types, the myeloid dendritic cells (mDC) levels were significantly increased in responder of the NAT group (P = 0.025); however, the levels of CD4, CD8, monocyte, overall DC, and plasmacytoid DC were not significantly different. After NAT 2-month, a decrease in mDC levels was frequently observed in the non-responder group (75% vs. 43%), but the difference was not significant. Conclusion: Our study suggests that mDC in blood may be a useful biomarker for predicting NAT response and improving treatment responses in pancreatic cancer patients. Further research is required to fully assess the role of mDC in predicting NAT response.Funding: This work was supported in part by the National Cancer Center, Korea (No. 2410680). Citation Format: Byeong-Gon Kim, Sung Jun Kim, Gyuryang Park, Tae Young Kim, Sung-Sik Han, Sang-Jae Park, Woo Jun Lee, Sun-Young Kong, Yun-Hee Kim, Jung Won Chun, Sang Myung Woo. Preliminary analysis of immune cell profiling to neoadjuvant chemotherapy response in pancreatic cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 2153.