LRRC15 and pancreatic ductal adenocarcinoma: A population of TGFβ-converted CAFs with an elevated leucine-rich repeat containing 15 (LRRC15) protein signature surrounding tumor islets, identified using single-cell transcriptomics in the process of charting pancreatic ductal adenocarcinoma progression, correlates with poor response to anti-PD-L1 immunotherapy across clinical trials comprising more than 600 patients in six cancer types [68].