Impact of PD-L1 overexpression on immune checkpoint inhibitor efficacy in triple-negative breast cancer using a 4T1 murine model.

Bulk RNA sequencing was performed to investigate transcriptomic changes in 4T1 tumors treated with anti-PD-L1 therapy. Tumors were derived from 4T1 control and PD-L1-overexpressing cells injected into mice, followed by IgG or anti-PD-L1 treatment. Gene expression analysis revealed distinct immune-related pathway alterations, with reduced immune activation in PD-L1-overexpressing tumors. Differentially expressed genes suggested an immunosuppressive tumor microenvironment, potentially contributing to resistance to anti-PD-L1 therapy. These findings provide insights into the molecular mechanisms underlying immune checkpoint inhibitor response in triple-negative breast cancer.