A quantitative score of immune cell infiltration predicts the prognosis in pancreatic ductal adenocarcinoma

•Our analysis of the ICI patterns of 876 PDAC patients revealed two ICI phenotypes.•We used a novel quantitative scoring method to construct the ICIscore.•ICIscore effectively predicted the prognosis and chemotherapy benefit of PDAC patients in the discovery and validation cohorts.•ICIscore’s good performance in predicting OS for immunotherapy treated pan-cancers could provide a reference for future PDAC immunotherapy decisions.