Immune checkpoint inhibitors (ICIs) targeting programmed cell death-1 (PD-1) and programmed cell death-ligand 1 (PD-L1) have markedly improved the prognosis of many patients with advanced non-small cell lung cancer (NSCLC). However, the relationship between the patient's nutritional/immunologic status and the outcomes of ICI treatment remains unclear. In previous retrospective studies, we reported that the controlling nutritional status (CONUT) score, skeletal muscle area, and neutrophil-to-lymphocyte ratio were independent predictors of the response of NSCLC patients to anti-PD-1 drugs. The aim of this prospective multi-center study is to investigate the clinical impact of pre-treatment nutritional/immunologic indices and early post-treatment changes in the indices on treatment outcomes in advanced NSCLC. The main inclusion criteria are: (1) stage IV NSCLC, or stage III NSCLC not applicable for definitive chemoradiotherapy; (2) treatment with ICIs (monotherapy or combined with chemotherapy) as first-line therapy; and (3) available data on PD-L1 expression on tumor cells. A total of 300 patients will be enrolled prospectively. Enrollment will begin in 2020 and the final analyses will be completed by 2025.