Abstract 1807: Tumor-infilitrating lymphocytes derived from pancreatic adenocarcinoma exhibit an activated, pro-inflammatory phenotype

Abstract

Abstract Contrary to current dogma, which maintains that pancreatic adenocarcinoma (PA) is infiltrated by predominantly inhibitory, regulatory CD4+ T cells (Treg), we demonstrate expansion of activated, pro-inflammatory tumor-infiltrating lymphocytes (TILs) from PA that could be used for adoptive cell therapy. TILs were grown in vitro in high-dose IL-2 from fragments of primary or metastatic PA. Pancreatic TILs were successfully expanded in 9 of 10 tumors and were phenotyped by flow cytometry. CD3+ TILs were predominantly CD4+ (mean frequency 76%, range 37-97%). CD4+ TILs were assessed for Treg frequency by CD25 and FoxP3 co-expression as a percent of total CD3+ TILs. Tregs were found to comprise the minority of CD3+ TILs (mean=3.1%, range=0.36-6.6%). We assessed CD4+ TIL expression of CD69, a known marker of T cell activation, and found a relatively high percentage of CD4+ TILs expressed CD69 (mean=25%, range=9-46%), which was significantly higher than the mean percent of Treg (p=0.0006). To confirm pro-inflammatory function, bulk TILs were stimulated in vitro by PMA/ionomycin, and expression of the pro-inflammatory cytokine IFNγ and the cytolytic marker CD107a was assessed. CD4+ TILs demonstrated a relatively high level of expression of IFNγ (mean=35%, range=20-47%) and CD107a (mean=19%, range=10-26%). Despite a low relative frequency, CD8+ TILs (mean=17%, range=1.8-41%) also expressed CD69 (mean=46%, range=17-83%) and exhibited a pro-inflammatory function upon stimulation as demonstrated by IFNγ (mean=43%, range=31-61%) and CD107a (mean=42%, range=22-69%) expression. After CD4 depletion, CD8-enriched TILs were effectively expanded with α-CD3 and maintained an activated, pro-inflammatory phenotype. This is the first report demonstrating that CD4+ TILs derived from PA have a predominantly pro-inflammatory phenotype. CD8+ TILs, though in the minority, also displayed an activated phenotype and preserved this phenotype throughout selective expansion. Further work is ongoing to support a phase I clinical trial involving adoptive TIL therapy in PA. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1807. doi:10.1158/1538-7445.AM2011-1807