Liudahl SM, Betts CB, Sivagnanam S, et al. - This study sought to evaluate leukocyte heterogeneity in pancreatic ductal adenocarcinoma. Researchers quantitatively assessed leukocyte contexture in 135 human pancreatic ductal adenocarcinoma (PDAC) at single-cell resolution by profiling density and spatial distribution of myeloid and lymphoid cells within histopathologically characterized regions of surgical resections from treatment-naive and presurgically (neoadjuvant)–treated patients and biopsy specimens from metastatic PDAC. They give a phenotypic and spatial immune atlas of human PDAC distinguishing leukocyte composition at steady state and following standard neoadjuvant therapies. These outcomes have broad usefulness as a resource that can inform on leukocyte responses to emerging therapies where baseline tissues were not acquired.