e20679 Background: Nivolumab (Nivo) is applicable for all metastatic or unresectable non-small cell lung cancer (NSCLC), however only some patients benefit from it. Therefore, identifying biomarkers predicting efficacy is a crucial topic in the “real world’’ setting. We conducted a retrospective study to analyze the impact of metastatic status on the effect of Nivo in NSCLC patients. Methods: This is a retrospective multicenter study conducted by the three medical centers in Japan. All patients treated with Nivo from January 2016 to July 2016 in these centers were retrospectively reviewed. We collected clinical data including age, sex, smoking history, performance status (PS), and metastatic cites (lymph nodes: lym, liver, brain, bone, pleural effusion, and intrapulmonary metastasis: lung) at the time of starting Nivo treatment. We investigated relationship between metastatic sites and progression free survival (PFS) of Nivo. Patients were followed-up until 30th September 2016. Results: Two hundred and one patients treated with Nivo were enrolled. At the time of administration of Nivo, median age was 68 years old, 137 patients were male, 155 patients had history of smoking status, 152 patients were PS 0 or 1, and 46 patients had squamous cell carcinoma (SQ). For all participants, median PFS was 2.5 months. In univariate analysis, female (hazard ratio (HR): 1.43, 95% confidence interval (CI): 1.02-2.00; p = 0.036), never-smoker (HR: 1.51 , 95% CI: 1.05 – 2.17; p = 0. 0262), PS 2 or more (HR: 1.68, 95% CI: 1.17-2.41; p = 0.0045), metastasis to liver (HR: 2.02, 95% CI: 1.30-3.15; p = 0.0015), brain (HR: 1.42, 95% CI: 0.99-2.03; p = 0.0574), bone (HR: 1.42, 95% CI: 1.01-1.98; p = 0.0642), lung (HR: 1.57, 95% CI: 1.13-2.20; p = 0.0076), and malignant pleural effusion (HR: 1.47, 95% CI: 1.06-2.04; p = 0.0195) had significantly correlated with poor PFS. In multivariate analysis, liver metastasis (HR: 1.59, 95% CI: 0.97-2.61; p = 0.0642) and malignant pleural effusion (HR: 1.47, 95%CI: 1.04–2.07; p = 0.0294) had significantly correlated with poor PFS. Conclusions: Liver metastasis and malignant pleural effusion were independent poor prognostic factors of Nivo treatment in NSCLC patients. (UMIN-ID: UMIN000025908)