Similarly, the TGF-β signaling-driven LRRC15+ CAF subpopulation in PDAC also forms a physical barrier by enhancing ECM deposition, restricting T cell infiltration into the tumor parenchyma, leading to an “immune exclusion” phenotype, and is directly associated with anti-PD-L1 therapy resistance [103]. This evidence concerns the gene TGFB1 and neoplasm.