Stromal PD L1 Expression Is Associated With Better Disease Free Survival in Triple Negative Breast Cancer.
OBJECTIVES Triple negative breast cancer (TNBC) is an aggressive subtype of breast cancer, and there is no approved targeted therapy. We studied the expression of programmed cell death protein 1 (PD 1) and its ligand (PD L1) in TNBC. METHODS Full face sections from 136 TNBC cases without neoadjuvant therapy between 2004 and 2013 were stained and evaluated for immune cell PD 1 staining and stromal or tumoral PD L1 staining using the H score (staining percentage x intensity) Nottingham histologic grade, lymphovascular invasion (LVI) mitotic count, and tumor infiltrating lymphocytes (TILs) were evaluated. Tumor size, lymph node status, Ki 67 score, metastasis, overall survival (OS) and disease free survival (DFS) were retrieved from medical records. RESULTS Of the 136 TNBC cases, 69 (51% had any PD L1 staining and 35 (26% had PD L1 staining with an H score of 5 or more; 117 (86% had any PD 1 staining and 68 (50% had PD 1 staining with an H score of 5 or more. Tumor size and LVI were significantly associated with worse OS and DFS, and TILs and LVI were significantly associated with metastasis in univariate analysis. Stromal PD L1 expression was significantly associated with better DFS in multivariate analysis. PD 1 expression was not associated with DFS, OS, or metastasis. CONCLUSIONS PD L1 expression is seen in a high proportion of TNBCs and associated with better DFS.
American journal of clinical pathology