IDO1 and pancreatic neoplasm: The results showed that IDO1 expression levels in pancreatic cancers were related to CD4+ memory T cells (r, 0.61), M1-like macrophages (r, 0.46), and CD8+ T cells (r, 0.19) but not other immunosuppressive cells, consistent with our immunostaining results (Supplementary Fig. S3d).