PD-L1 Expression in Triple-Negative Breast Cancer

TLDR: Using tissue microarrays containing 105 triple-negative breast cancer specimens, Mittendorf and colleagues show that 20% of the TNBC specimens express PD-L1, half have lost PTEN, and inhibitors of PI3K pathway decrease PD- l1 expression, providing a rationale for therapeutic targeting of PD- L1 for TNBC.

Abstract: Early-phase trials targeting the T-cell inhibitory molecule programmed cell death ligand 1 (PD-L1) have shown clinical efficacy in cancer. This study was undertaken to determine whether PD-L1 is overexpressed in triple-negative breast cancer (TNBC) and to investigate the loss of PTEN as a mechanism of PD-L1 regulation. The Cancer Genome Atlas (TCGA) RNA sequencing data showed significantly greater expression of the PD-L1 gene in TNBC ( n = 120) compared with non-TNBC ( n = 716; P + tumors had greater CD8 + T-cell infiltrate than PD-L1 − tumors (688 cells/mm vs. 263 cells/mm; P Cancer Immunol Res; 2(4); 361–70. ©2014 AACR .