title: PD-L1 expression and CD274 gene alteration in triple-negative breast cancer: implication for prognostic biomarker.
abstract: OBJECTIVE
  To estimate the therapeutic potential of PD-L1 inhibition in breast cancer, we evaluated the prevalence and significance of PD-L1 protein expression with a validated antibody and CD274 gene alternation in a large cohort of triple negative breast cancer (TNBC) and correlated with clinicopathological data and patients overall survival.
  
  
  METHODS
  Immunohistochemistry and in situ mRNA hybridization was used to detect PD-L1 protein and mRNA expression in tumor tissues from 183 TNBC patients respectively. Fluorescence in situ hybridization analysis was performed on PD-L1 strong expression samples to assess copy number on chromosome 9p24.1 of CD274 gene.
  
  
  RESULTS
  Expression of PD-L1 by immune cells was observed in 4.9 % of TNBC, while expression by tumor cells accounted for 8.7 %. There was a high concordance in PD-L1 protein expression and PDL1 mRNA expression. Samples with PD-L1 strong expression were found to have a CD274 gene copy number gain. PD-L1 expression was correlated with higher tumor grade, but was independent of menopausal status, lymph nodes metastasis, histological subtype and tumor size. In addition, we used precise stratification of PD-L1 expression on tumor or immune cells of certain breast cancer subtype and suggested that patients with PD-L1 expression in basal-like tumors by immune cells or with CD274 gene copy number gain had a longer disease-specific overall survival.
  
  
  CONCLUSIONS
  Our findings may promote the more precise analysis of PD-L1 expression in breast cancer and aid the selection of patients who may benefit from immune therapy.
authors.affiliation: Department of Pathology, National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Panjiayuan Nanli 17#, Beijing, 100021 China.
authors.forename: Lei
authors.initials: L
authors.lastname: Guo
authors.affiliation: Department of Pathology, National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Panjiayuan Nanli 17#, Beijing, 100021 China.
authors.forename: Wenbin
authors.initials: W
authors.lastname: Li
authors.affiliation: Department of Obstetrics and Gynecology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100730 China.
authors.forename: Xinxin
authors.initials: X
authors.lastname: Zhu
authors.affiliation: Department of Pathology, National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Panjiayuan Nanli 17#, Beijing, 100021 China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Ling
authors.affiliation: Department of Pathology, National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Panjiayuan Nanli 17#, Beijing, 100021 China.
authors.forename: Tian
authors.initials: T
authors.lastname: Qiu
authors.affiliation: Department of Pathology, National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Panjiayuan Nanli 17#, Beijing, 100021 China.
authors.forename: Lin
authors.initials: L
authors.lastname: Dong
authors.affiliation: Department of Breast Surgical Oncology, National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100021 China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Fang
authors.affiliation: Department of Pathology, National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Panjiayuan Nanli 17#, Beijing, 100021 China.
authors.forename: Hongying
authors.initials: H
authors.lastname: Yang
authors.affiliation: Department of Pathology, National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Panjiayuan Nanli 17#, Beijing, 100021 China.
authors.forename: Jianming
authors.initials: J
authors.lastname: Ying
keywords: CD274 gene alternation; Immunohistochemistry; PD-L1; Prognosis; TNBC