Abstract
BACKGROUND: A comprehensive analysis of peripheral immune cell phenotypes and tumor immune-gene expression profiles in locally advanced pancreatic cancer patients treated with neoadjuvant chemotherapy in a phase II clinical trial was carried out. METHODS: Patients were treated with neoadjuvant modified folinic acid, fluorouracil, irinotecan hydrochloride, oxaliplatin (mFOLFIRINOX) followed by surgery and adjuvant gemcitabine at the Asan Medical Center. Correlations between survival outcomes and baseline peripheral immune cells and their changes during preoperative chemotherapy were analyzed. Patients who had surgery were divided into two groups according to achievement of disease-free survival >10 months (achieved versus failed). Differential expression and pathway analysis of immune-related genes were carried out using the Nanostring platform, and immune cells within the tumor microenvironment were compared by immunohistochemistry. RESULTS: Forty-four patients were treated in the phase II clinical trial. Higher baseline CD14+CD11c+HLA-DR+ monocytes (P = 0.044) and lower Foxp3+CD4+ T cells (P = 0.02) were associated with poor progression-free survival of neoadjuvant mFOLFIRINOX. During the preoperative chemotherapy, PD-1 T cells significantly decreased (P = 0.0110). Differential expression and pathway analysis of immune-genes from the resected tumor after neoadjuvant treatment revealed transforming growth factor-β pathway enrichment and higher expression of MARCO (adjusted P < 0.05) associated with early recurrence. Enrichment of the Th1 pathway and higher peritumoral CD8+ T cells (P = 0.0103) were associated with durable disease-free survival from surgery (>10 months) following neoadjuvant mFOLFIRINOX. CONCLUSIONS: Our results identify potential immune biomarkers for locally advanced pancreatic cancer and provide insights into pancreatic cancer immunity.