[Consistency of PD-L1 immunohistochemical detection platforms in biopsy samples with advanced lung adenocarcinoma: a multicenter study].

Objective: To analyze the expression of programmed death ligand 1 (PD-L1) in patients with advanced lung adenocarcinoma and the consistency of four PD-L1 immunohistochemical detection platforms, with an aim of establishing baseline information to predict and select patients for programmed death 1 (PD-1)/PD-L1 immune inhibitor therapy. Methods: This was a multi-center retrospective study, collecting totally 57 advanced lung adenocarcinoma biopsy specimens from four centers from August 2017 to December 2017.The mean age of 57 patients was 59 (range 34-81) years, and 29 cases were male, 28 cases were female. Four PD-L1 immunohistochemical stains were done for each case, including 22C3 (Dako), 28-8 (Abcam), SP263 (Ventana), and SP142 (Ventana). Among them, 22C3 staining was done using Dako autostainer, and for the other three antibodies, Ventana Ultraview detection system and autostainer was used. The immunohistochemical slides were read by two trained histopathologists in a double-blinded way, and the percentage of PD-L1 positive tumor cells was assessed as <1%, 1%-24%, 25%-49% and more than 50%. Results: The Dako 22C3 was used as the standard. There were eight cases in which the PD-L1 staining was more than 50% (14.0%, 8/57). The staining consistency of tumor cells was higher in 22C3, 28-8 and SP263 (ρ=0.729-0.809). The two scoring doctors had a high degree of concordance in PD-L1 positive tumor cells (ρ=0.707-0.896), and this was most noticeable in 22C3 and SP263. Conclusions: 22C3, 28-8 and SP263 show high consistency in tumor cell staining. The study can provide an effective basis for screening for potential patient population that may benefit from immunotherapy.