Research Progress on the Regulation of PD-L1 Expression and Its Role in Tumor Immunity

The PD-1/PD-L1 signaling axis serves as a primary mechanism of tumor immunoevasion, wherein the binding of tumor-expressed PD-L1 to its receptor on T cells triggers cellular exhaustion and programmed death. While the clinical introduction of checkpoint inhibitors targeting this pathway has transformed the oncological landscape, the inconsistency of patient response rates highlights a profound need to deconstruct the upstream regulatory networks governing PD-L1 synthesis. By examining the interplay between immune suppression and protein expression, this review aims to identify the specific drivers of tumor escape and evaluate emerging therapeutic strategies designed to optimize the blockade of this critical checkpoint for superior clinical outcomes.