PD-L1 expression is a promising predictor of survival in patients with advanced lung adenocarcinoma undergoing pemetrexed maintenance therapy

This study aimed to identify potential predictive factors for the survival of advanced lung adenocarcinoma patients undergoing pemetrexed maintenance therapy. 122 advanced lung adenocarcinoma patients who received pemetrexed maintenance therapy were retrospectively analyzed. Kaplan–Meier method with Log-rank test was used for survival analysis. Univariate and multivariate Cox regression were performed to evaluate prognostic factors for overall survival (OS) and progression-free survival (PFS). Bivariate correlation analysis was used for exploratory purpose. For the whole cohort of 122 patients, median PFS was 11.97 months (95% CI 10.611–13.329) and estimated median OS was 45.07 months (95% CI 31.690–58.450). The mPFS of ALK-positive patients was superior to negative patients (18.27 vs. 11.90 months; P = 0.039). Patients with ECOG PS 0 (14.4 vs. 11.1 months; p = 0.040) and patients with single-organ metastasis (19.0 vs. 11.0 months; p = 0.014) had prolonged median PFS. Compared with the low PD-L1 expression group, PFS of high PD-L1 expression group were improved (13.6 vs. 11.1 months, p = 0.104, at 1% cut-off; 17.5 vs. 11.1 months, p = 0.009, at 10% cut-off; and 27.5 vs. 11.4 months, p = 0.005, at 50% cut-off). No differences were found between EGFR positive and negative patients. PD-L1 expression was an independent prognostic factor for both PFS and OS times (PFS: HR, 0.175; P = 0.001; OS: HR, 0.107; P = 0.036). Bivariate correlation showed a significant positive correlation between PD-L1 expression and PFS (correlation coefficient R = 0.485, P