Post-treatment neutrophil-to-lymphocyte ratio at week 6 is prognostic in patients with advanced non-small cell lung cancers treated with anti-PD-1 antibody.

We investigated inflammatory markers such as the neutrophil-to-lymphocyte ratio (NLR) that may predict the response to anti-PD-1 (programmed cell death protein 1) antibody therapy. Data from 54 patients with non-small cell lung cancer (NSCLC) treated with anti-PD-1 antibodies were retrospectively analyzed. The NLR was assessed at baseline and 6 weeks after the start of treatment (post-treatment). Eighteen of 54 patients (33.3%) had objective responses to treatment. Older age, absence of brain metastasis, low post-treatment NLR (< 5), and immune-related adverse events were significantly associated with response. Patients with a high post-treatment NLR (≥ 5) had significantly shorter progression-free survival (PFS) than those with a low post-treatment NLR (median, 1.3 vs. 6.1 months, p < 0.001). Multivariate analysis demonstrated that high post-treatment NLR [hazard ratio (HR) 15.1, 95% confidence interval (CI) 1.5-50.1, p < 0.001], liver metastasis (HR 4.9, 95% CI 1.9-12.4, p = 0.001), and brain metastasis (HR 3.2, 95% CI 1.3-8.2, p = 0.013) were independent prognostic factors of shorter PFS. Overall survival (OS) was significantly different in patients with high and low post-treatment NLRs (median, 2.1 vs. 14.0 months, p < 0.001). A high post-treatment NLR remained an independent prognostic factor for OS in multivariate analysis (HR 3.9, 95% CI 1.6-9.2, p = 0.003). The NLR at 6 weeks after treatment initiation was a prognostic marker in patients with advanced NSCLC treated with anti-PD-1 antibody. Further studies are warranted to evaluate the role of the 6-week NLR as a predictor in anti-PD-1 antibody treatment.