title: PD-L1 Expression and Survival among Patients with Advanced Non-Small Cell Lung Cancer Treated with Chemotherapy.
abstract: BACKGROUND
  Recent clinical trial results have suggested that programmed cell death ligand 1 (PD-L1) expression measured by immunohistochemistry may predict response to anti-programmed cell death 1 (PD-1) therapy. Results on the association between PD-L1 expression and survival among patients with advanced non-small cell lung cancer (NSCLC) treated with chemotherapy are inconsistent.
  
  
  METHODS
  We evaluated the relationship between PD-L1 expression and overall survival (OS) among 204 patients with advanced NSCLC treated at Aarhus University Hospital, Aarhus, Denmark, from 2007 to 2012. PD-L1 expression was measured using a prototype immunohistochemistry assay with the anti-PD-L1 22C3 antibody (Merck). PD-L1 strong positivity and weak positivity were defined to be traceable to the clinical trial version of the assay.
  
  
  RESULTS
  Twenty-five percent of patients had PD-L1 strong-positive tumors, and 50% had PD-L1 weak-positive tumors. No statistically significant association was found between PD-L1 expression and survival; adjusted hazard ratio of 1.34 (95% confidence interval, 0.88-2.03; median OS, 9.0 months) for the PD-L1 strong-positive group and 1.07 (0.74-1.55; median OS, 9.8 months) for the PD-L1 weak-positive group compared with the PD-L1-negative group (median OS, 7.5 months). No association was seen between PD-L1 expression and OS when PD-L1 expression levels were stratified by median or tertiles.
  
  
  CONCLUSIONS
  In concordance with previous studies, we found PD-L1 measured by immunohistochemistry to be frequently expressed in patients with advanced NSCLC. However, PD-L1 expression is not a strong prognostic marker in patients with advanced NSCLC treated with chemotherapy.
authors.affiliation: Department of Oncology, Aarhus University Hospital, Norrebrogade 44, DK-8000 Aarhus C, Denmark. Electronic address: stefsoer@rm.dk.
authors.forename: Steffen Filskov
authors.initials: SF
authors.lastname: Sorensen
authors.affiliation: Merck & Co., Inc., 2000 Galloping Hill Rd, Kenilworth, NJ, USA. Electronic address: wei.zhou2@merck.com.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhou
authors.affiliation: Merck & Co., Inc., 2000 Galloping Hill Rd, Kenilworth, NJ, USA. Electronic address: marisa.dolled-filhart@merck.com.
authors.forename: Marisa
authors.initials: M
authors.lastname: Dolled-Filhart
authors.affiliation: Department of Pathology, Aarhus University Hospital, Norrebrogade 44, DK-8000 Aarhus C, Denmark. Electronic address: jeanette.georgsen@aarhus.rm.dk.
authors.forename: Jeanette Baehr
authors.initials: JB
authors.lastname: Georgsen
authors.affiliation: MSD China, 20/F Park Place, 1601 Nanjing Road West, Jin'an District, Shanghai 20040, China. Electronic address: zhen.wang4@merck.com.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Merck & Co., Inc., 2000 Galloping Hill Rd, Kenilworth, NJ, USA. Electronic address: kenneth.emancipator@merck.com.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Emancipator
authors.affiliation: Formerly of Merck & Co., Inc., 2000 Galloping Hill Rd, Kenilworth, NJ, USA. Electronic address: luna.immuno@gmail.com.
authors.forename: Dianna
authors.initials: D
authors.lastname: Wu
authors.affiliation: MSD Denmark, Lautrupbjerg 4, 2750 Ballerup, Denmark. Electronic address: michael.buschsorensen@merck.com.
authors.forename: Michael
authors.initials: M
authors.lastname: Busch-Sørensen
authors.affiliation: Department of Oncology, Aarhus University Hospital, Norrebrogade 44, DK-8000 Aarhus C, Denmark. Electronic address: petemeld@rm.dk.
authors.forename: Peter
authors.initials: P
authors.lastname: Meldgaard
authors.affiliation: Department of Pathology, Aarhus University Hospital, Norrebrogade 44, DK-8000 Aarhus C, Denmark. Electronic address: henrikhager@me.com.
authors.forename: Henrik
authors.initials: H
authors.lastname: Hager