P1.05-005 Programmed Death-Ligand 1 (PD-L1) in Resected Lung Adenocarcinomas (LA) in a University Hospital

Abstract

The role of monoclonal antibodies inhibiting of the Programmed Death-1 and its ligand (PD-1/ PD-L1) pathway have been described in advanced disease. The knowledge of the role of this pathway in early stages of lung cancer is still limited. We assessed the incidence of PD-L1 expression in tumor cells of samples of resected lung adenocarcinomas and its prognostic role. A retrospective analysis of patients (p) with lung adenocarcinomas radically resected at our Institution between 2004 and 2011 has been conducted. PD-L1 was determined by Immunohistochemistry (SP263, Ventana® assay). A cut-off value of 5% of positive tumor cell was chosen. 112 tumors from 107 p were included. Median age was 62 years. 81% were male, 88% had exposure smoking, baseline performance status was 0 – I – II (62,5% - 26,8% - 10,7%) and pathological stage was I – II – III – IV (49,1% - 26,8% - 23,2% - 0,9%). Fourteen p (12%) expressed PD-L1>5%. They were mostly male (71%), smokers (93%), baseline performance status was 0 – 1 – 2 (64% - 29% - 7%), the most common histological subtype was poorly differentiated adenocarcinoma (64%) and pathological stage was I – II – III (28% - 21% - 50%). One p (7,7%) harbored EGFR mutation, none (0%) were ALK positive and 6 p (46,2%) had a K-RAS mutation. With a follow-up of 52 months median disease free survival (DFS) was 49 months and overall survival (OS) 58 months. Median DFS was shorter in p with expression of PD-L1 (27 months) that in negative tumors (49 months) (p=0,45). Median OS showed a similar pattern (32 vs 66 months respectively) also favoring PD-L1 negative p (p=0,05). In our series, patients with resected adenocarcinomas expressing PD-L1 in >5% of cells showed a worse disease free and overall survival than patients without such expression.