Three Distinct Stroma Types in Human Pancreatic Cancer Identified by Image Analysis of Fibroblast Subpopulations and Collagen—Response Available to Purchase

We thank Bouzid and colleagues for their interest in our article describing pancreatic cancer stromal types identified by image analyses of two distinct fibroblast subpopulations, ACTA2 (α smooth muscle actin)–dominant fibroblasts and FAP (fibroblast activation protein α)–dominant fibroblasts, intratumoral collagen, and CD8⁺ cells using whole tissue slides from 215 patients with pancreatic ductal adenocarcinomas (1).

Bouzid and colleagues have confirmed our previous findings that CD8⁺ cell density is generally lower in the tumor center than in the tumor margin (1), suggesting that T-cell exclusion is a hallmark of the immunosuppressive nature of pancreatic cancers. Then, their letter addresses the association between FAP expression and CD8⁺ cell exclusion. In our analysis on a relatively large series of cases, the proportion of FAP–dominant fibroblasts (but not for ACTA–dominant fibroblasts or collagen) showed an inverse correlation with the ratios of CD8⁺ cell density in the...