title: Retrospective Molecular Epidemiology Study of PD-L1 Expression in Patients withEGFR-Mutant Non-small Cell Lung Cancer.
abstract: OBJECTIVE
  Data are limited on programmed death ligand 1 (PD-L1) expression in epidermal growth factor receptor (EGFR)-mutant non-small cell lung cancer (NSCLC).
  
  
  METHODS
  We retrospectively evaluated the relationship between PD-L1 expression and recurrence-free survival (RFS) and overall survival in 319 patients withEGFR-mutant NSCLC who were treated at Samsung Medical Center from 2006 to 2014. Membranous PD-L1 expression on tumor cells was measured using the PD-L1 IHC 22C3 pharmDx antibody and reported as tumor proportion score (TPS). Kaplan-Meier methods, log-rank test, and Cox proportional hazards models were used for survival analysis.
  
  
  RESULTS
  All patients had ≥1EGFRmutation-54% in exon 19 and 39% in exon 21. Overall, 51% of patients had PD-L1-positive tumors. The prevalence of PD-L1 positivity was higher among patients with stages II-IV versus stage I disease (64% vs. 44%) and among patients with otherEGFRmutations (75%) than with L858R mutation (39%) or exon 19 deletion (52%). PD-L1 positivity was associated with shorter RFS, with an adjusted hazard ratio of 1.52 (95% confidence interval [CI], 0.81 to 2.84; median, 18 months) for the PD-L1 TPS ≥ 50% group, 1.51 (95% CI, 1.02 to 2.21; median, 31 months) for the PD-L1 TPS 1%-49% group, and 1.51 (95% CI, 1.05 to 2.18) for the combined PD-L1-positive groups (TPS ≥ 1%) compared with the PD-L1-negative group (median, 35 months).
  
  
  CONCLUSIONS
  PD-L1 expression is associated with disease stage and type ofEGFRmutation. PD-L1 positivity might be associated with worse RFS among patients with surgically treatedEGFR-mutant NSCLC.
authors.affiliation: Department of Thoracic Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Jong Ho
authors.initials: JH
authors.lastname: Cho
authors.affiliation: Merck & Co., Inc., Kenilworth, NJ, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhou
authors.affiliation: Department of Pathology and Translational Genomics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Yoon-La
authors.initials: YL
authors.lastname: Choi
authors.affiliation: Division of Hematology-Oncology, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Jong-Mu
authors.initials: JM
authors.lastname: Sun
authors.affiliation: Department of Thoracic Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Hyejoo
authors.initials: H
authors.lastname: Choi
authors.affiliation: Department of Thoracic Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Tae-Eun
authors.initials: TE
authors.lastname: Kim
authors.affiliation: Merck & Co., Inc., Kenilworth, NJ, USA.
authors.forename: Marisa
authors.initials: M
authors.lastname: Dolled-Filhart
authors.affiliation: Merck & Co., Inc., Kenilworth, NJ, USA.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Emancipator
authors.affiliation: Merck & Co., Inc., Kenilworth, NJ, USA.
authors.forename: Mary Anne
authors.initials: MA
authors.lastname: Rutkowski
authors.affiliation: Department of Thoracic Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Jhingook
authors.initials: J
authors.lastname: Kim
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D060890:B7-H1 Antigen / Q000096:biosynthesis* / Q000235:genetics; D002289:Carcinoma, Non-Small-Cell Lung / Q000453:epidemiology / Q000235:genetics / Q000378:metabolism* / Q000601:surgery; D066246:ErbB Receptors / Q000235:genetics* / Q000378:metabolism; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008175:Lung Neoplasms / Q000453:epidemiology / Q000235:genetics / Q000378:metabolism* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D017720:Molecular Epidemiology; D012189:Retrospective Studies
chemical_list: D060890:B7-H1 Antigen; C423236:CD274 protein, human; C512478:EGFR protein, human; D066246:ErbB Receptors
keywords: Epidermal growth factor receptor; Non-small cell lung carcinoma; Programmed cell death 1 protein