Abstract A053: The effects of chemotherapy on B cells and T cells in blood and tumor tissue in patients with pancreatic cancer – from diagnosis to terminal disease

Abstract

Abstract Pancreatic cancer (PC) is a devastating disease and is almost always synonymous with a poor outcome. Chemotherapy is the standard treatment and is administered in either an adjuvant or palliative setting. However, nearly all patients, regardless of treatment intent, eventually develop chemoresistance. Little is known about the events causing chemoresistance, but increased knowledge is essential for improving patient outcomes. The aim of this study was to increase the knowledge of how the immune system, locally and systemically, is affected by chemotherapy and how this influences patient outcomes. Hence, immunohistochemical analysis of T and B cell prevalence in post-mortem tumor tissue was performed and combined with flow cytometric analysis of the dynamics of circulating T and B cell subsets during chemotherapy in nine PC patients enrolled in a clinical study. Despite the small number of patients included in this study, some interesting results were found. A high number of tertiary lymphoid-like structures (TLLSs) in the primary tumor was associated with shorter survival, which is contradictory to previous findings and possibly indicates a negative effect of chemotherapy on TLLSs. Certain subpopulations of T and B cells exhibited variations during treatment, possibly in response to chemotherapy. The frequency of T cells in blood also tended to correlate inversely with the frequency in primary tumor and liver metastases. Overall, this exploratory study provides insights into how the immune system in PC is affected by chemotherapy. Further study is warranted to shed more light on the intrinsic chemoresistance of PC and to identify new therapeutic strategies. Citation Format: Hedda Jacobsen. The effects of chemotherapy on B cells and T cells in blood and tumor tissue in patients with pancreatic cancer – from diagnosis to terminal disease [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr A053.