Tumor PD-L1 mRNA Expression Associated With Improved Outcome in Breast Cancer

Get Permission

Inhibition of the PD-1/PD-ligand1 (PD-L1) axis has shown considerable therapeutic promise in several cancers. Tumor PD-L1 protein expression may predict response to drugs targeting this pathway, but its measurement has been limited by the lack of standardized immunohistochemical methods and variable antibody performance.

In a study reported in Clinical Cancer Research, Schalper and colleagues observed consistent measurements of in situ PD-L1 mRNA levels in 636 stage I to III breast carcinomas using two different sets of tissue microarrays and found that increased PD-L1 mRNA expression was associated with increased numbers of tumor-infiltrating lymphocytes and prolonged recurrence-free survival. The two microarrays showed PD-L1 mRNA expression in 55.7% and 59.5% of cases, with higher PD-L1 mRNA expression being significantly associated with increased tumor-infiltrating lymphocytes (P = .04) but not with other clinical variables.

Elevated tumor-infiltrating lymphocytes were found in 16.5% and 14.8% of samples with the two microarrays and were associated with estrogen receptor–negative status (P = .01 and P = .0001). PD-L1 mRNA expression was significantly associated with longer recurrence-free survival (P = .01), with the significant association persisting on multivariate analysis including age, tumor size, histologic grade, nodal metastasis, hormone receptor status, HER2 status, and extent of tumor-infiltrating lymphocytes (hazard ratio = 0.268, P = .009).

The investigators concluded, “PD-L1 mRNA expression is identified in nearly 60% of breast tumors and it is associated with increased [tumor-infiltrating lymphocytes] and improved recurrence-free survival. These observations support the evaluation of PD-1/PD-L1-targeted therapies in breast cancer.” ■

Schalper KA, et al: Clin Cancer Res 20:1-10, 2014.




By continuing to browse this site you permit us and our partners to place identification cookies on your browser and agree to our use of cookies to identify you for marketing. Read our Privacy Policy to learn more.