1740PDDifferential expression of B7-H4, VISTA, B7-H6, HHLA2, IDO-1, PD-L1 and CD8 in EGFR mutant and wild-type lung adenocarcinoma

Abstract Background The aim of this study was to describe the expression profiles of newly discovered B7 family (B7-H4, VISTA, B7-H6, HHLA2), IDO-1, PD-L1 and CD8 in resected lung adenocarcinoma tumor tissues and try to find potential immune target for lung cancer with EGFR mutation. Methods A total of 372 adenocarcinoma lung cancer patients who underwent lung cancer resection were selected in the discovery cohort. The validation cohort contains another 231 adenocarcinoma lung cancer patients. Expression of B7-H4, VISTA, B7-H6, HHLA2, IDO-1, PD-L1 and CD8 was determined by immunohistochemical staining. Results In the discovery cohort, 44.9% (167/372) of B7H4, 75.8% (282/372) of VISTA, 84.7% (315/372) of B7H6, 61.0% (227/372) of IDO-1 was positively stained in lung adenocarcinoma tissues. In the validation cohort, majority of cases was positive for B7H4 (41.6%, 96/231), VISTA (74.5%, 172/231), B7H6 (86.4%, 200/231) and IDO-1 (57.1%, 132/231), which was similar to the initial cohort. The positive expression rate of B7H4 in EGFR mutation group was significantly higher than that in wild type group in both cohort (P  Conclusions Aberrant expressions of B7-H4 and HHLA2 were more obvious in EGFR mutation lung cancer. High co-expression of CD8 and IDO-1 in EGFR wild type patients reveals a potential good clinical efficacy of anti-IDO-1 therapy in patients with EGFR wild type. Legal entity responsible for the study Jifeng Feng. Funding The National Natural Science Foundation of China. Disclosure All authors have declared no conflicts of interest.