Bartlett EK, Flynn JR, Panageas KS, et al. - Whether the neutrophil-to-lymphocyte ratio (NLR) can serve as a biomarker of treatment results in patients with melanoma managed with PD-1 inhibition, was investigated. Participants were people (n = 224) having stage IV melanoma and receiving initial treatment with PD-1 inhibitor monotherapy at a single center from 2012 to 2015. A significant link of baseline NLR with Eastern Cooperative Oncology Group performance status and the number of involved metastatic sites was revealed. A median follow-up of 39 months was performed in survivors, demonstrating an independent link of a baseline NLR ≥ 5 with shorter overall survival (OS) and time to treatment failure (TTF). Worse OS, as well as a trend toward shorter TTF, was observed in relation to an NLR rise ≥ 30% during the first 2 cycles of therapy. A small cohort having markedly shortened OS and TTF was detected by a combined baseline NLR ≥ 5 and an NLR increase ≥ 30%. These findings indicate a prognostic role of high baseline NLR and an increased NLR early during treatment for TTF and OS in patients with melanoma treated with PD-1 inhibitor monotherapy. A wide risk-stratification of patients for treatment failure and survival can be done with the combined use of these biomarkers.