title: In situ tumor PD-L1 mRNA expression is associated with increased TILs and better outcome in breast carcinomas.
abstract: OBJECTIVE
  Blockade of the PD-1/PD-L1 axis emerged as a promising new therapeutic option for cancer that has resulted in lasting responses in metastatic renal, lung carcinomas, and melanomas. Tumor PD-L1 protein expression may predict response to drugs targeting this pathway. Measurement of PD-L1 protein is limited by the lack of standardized immunohistochemical methods and variable performance of antibodies. Our goal was to correlate PD-L1 mRNA expression with clinical variables in primary breast carcinomas.
  
  
  METHODS
  The fluorescent RNAscope paired-primer assay was used to quantify in situ PD-L1 mRNA levels in 636 stage I-III breast carcinomas on two sets of tissue microarrays [YTMA128 (n = 238) and YTMA201 (n = 398)]. Tumor-infiltrating lymphocytes (TIL) were assessed by hematoxylin/eosin stain and quantitative fluorescence.
  
  
  RESULTS
  On YTMA128 and YTMA201, 55.7% and 59.5% of cases showed PD-L1 mRNA expression, respectively. Higher PD-L1 mRNA expression was significantly associated with increased TILs (P = 0.04) but not with other clinical variables. Elevated TILs (scores 2 and 3+) occurred in 16.5% on YTMA128 and 14.8% on YTMA201 and was associated with estrogen receptor-negative status (P = 0.01 on YTMA128 and 0.0001 on YTMA201). PD-L1 mRNA expression was associated with longer recurrence-free survival (log-rank P = 0.01), which remained significant in multivariate analysis including age, tumor size, histologic grade, nodal metastasis, hormone receptor, HER2 status, and the extent of TILs (HR, 0.268; CI, 0.099-0.721; P = 0.009).
  
  
  CONCLUSIONS
  PD-L1 mRNA expression is identified in nearly 60% of breast tumors and it is associated with increased TILs and improved recurrence-free survival. These observations support the evaluation of PD-1/PD-L1-targeted therapies in breast cancer.
authors.affiliation: Authors' Affiliations: Departments of Pathology and Medical Oncology, Yale School of Medicine, New Haven, Connecticut; and Department of Solid Tumor Oncology, Cleveland Clinic, Cleveland, Ohio kurt.schalper@yale.edu.
authors.forename: Kurt A
authors.initials: KA
authors.lastname: Schalper
authors.affiliation: Authors' Affiliations: Departments of Pathology and Medical Oncology, Yale School of Medicine, New Haven, Connecticut; and Department of Solid Tumor Oncology, Cleveland Clinic, Cleveland, Ohio.
authors.forename: Vamsidhar
authors.initials: V
authors.lastname: Velcheti
authors.affiliation: Authors' Affiliations: Departments of Pathology and Medical Oncology, Yale School of Medicine, New Haven, Connecticut; and Department of Solid Tumor Oncology, Cleveland Clinic, Cleveland, Ohio.
authors.forename: Daniel
authors.initials: D
authors.lastname: Carvajal
authors.affiliation: Authors' Affiliations: Departments of Pathology and Medical Oncology, Yale School of Medicine, New Haven, Connecticut; and Department of Solid Tumor Oncology, Cleveland Clinic, Cleveland, Ohio.
authors.forename: Hallie
authors.initials: H
authors.lastname: Wimberly
authors.affiliation: Authors' Affiliations: Departments of Pathology and Medical Oncology, Yale School of Medicine, New Haven, Connecticut; and Department of Solid Tumor Oncology, Cleveland Clinic, Cleveland, Ohio.
authors.forename: Jason
authors.initials: J
authors.lastname: Brown
authors.affiliation: Authors' Affiliations: Departments of Pathology and Medical Oncology, Yale School of Medicine, New Haven, Connecticut; and Department of Solid Tumor Oncology, Cleveland Clinic, Cleveland, Ohio.
authors.forename: Lajos
authors.initials: L
authors.lastname: Pusztai
authors.affiliation: Authors' Affiliations: Departments of Pathology and Medical Oncology, Yale School of Medicine, New Haven, Connecticut; and Department of Solid Tumor Oncology, Cleveland Clinic, Cleveland, Ohio.
authors.forename: David L
authors.initials: DL
authors.lastname: Rimm
mesh_terms: D060890:B7-H1 Antigen / Q000235:genetics* / Q000378:metabolism; D001943:Breast Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D005260:Female; D005455:Fluorescent Antibody Technique / Q000379:methods; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D017403:In Situ Hybridization; D053208:Kaplan-Meier Estimate; D008207:Lymphatic Metastasis; D016246:Lymphocytes, Tumor-Infiltrating / Q000378:metabolism* / Q000473:pathology; D008875:Middle Aged; D015999:Multivariate Analysis; D009364:Neoplasm Recurrence, Local; D011379:Prognosis; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism; D011960:Receptors, Estrogen / Q000378:metabolism; D046888:Tissue Array Analysis
chemical_list: D060890:B7-H1 Antigen; D012333:RNA, Messenger; D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; C423236:CD274 protein, human