p53 Missense Mutation is Associated with Immune Cell PD-L1 Expression in Triple-negative Breast Cancer

Background: Immunotherapy is an important treatment for triple-negative breast cancer (TNBC). The programmed death ligand 1 (PD-L1) is a pivotal biomarker in TNBC, and its expression is closely related to immunotherapy response. Therefore, the association of p53 expression and mutation and PD-L1 expression was explored. Methods and Results PD-L1 expression and p53 mutation and expression were evaluated by immunohistochemistry. PD-L1 expression and expression levels between p53 mutation (missense and nonsense) and wild type; no-expression/loss vs. expression; and missense vs. nonsense groups were compared. PD-L1 expression was found mainly in tumor-infiltrating immune cells (ICs) in TNBC. Positive PD-L1 expression was associated with a high Ki67 index. There was a significant association between p53 mutation, especially missense mutation and higher histological grade, and PD-L1 expression in ICs. Compared with p53 nonsense mutation, cases with missense mutations tended to display more PD-L1 positive ICs. However, PD-L1 expression in ICs was not significantly different between the p53 mutation and expression groups. Conclusionsp53 missense mutation is partially involved in the regulatory expression of PD-L1. Both p53 missense mutation and PD-L1 expression may be potential targets for improving immunotherapy response in TNBC.