Background: The neutrophil to lymphocyte ratio (NLR) is known to be prognostic for patients with advanced cancers treated with immune checkpoint inhibitors (ICI), but has generally been evaluated as a single threshold value at baseline. We evaluated NLR at baseline and within first month during treatment in patients who received ICI for advanced cancer to evaluate the prognostic value of baseline and of changes from baseline to on-treatment NLR.
Methods: A retrospective review of patients with advanced cancer treated with ICI from 2011 to 2017 at the Ohio State University was performed. NLR was calculated at the initiation of ICI and repeated at median of 21 days. Overall survival (OS) was calculated from the initiation of ICI to date of death or censored at last follow-up. Significance of Cox proportional hazards models were evaluated by log-rank test. Calculations were performed using the survival and survminer packages in R, and SPSS.
Results: 509 patients were identified and included in the analysis. Patients with baseline and on-treatment NLR < 5 had significantly longer OS (P < 0.001). The change in NLR overtime was a predictor of OS and was observed to be non-linear in nature. This property remained statistically significant with P < 0.05 after adjusting for age, body mass index, sex, cancer type, performance status, and days to repeat NLR measurement. Patients with a moderate decrease in NLR from baseline had the longest OS of 27.8 months (95% CI 21.8-33.8). Patients with significant NLR decrease had OS of 11.4 months (95% CI 6.1-16.7). Patients with a significant increase in NLR had the shortest OS of 5.0 months (95% CI 0.9-9.1).
Conclusions: We confirmed the prognostic value of NLR in patients with advanced cancer treated with ICIs. We found that change in NLR over time is a non-linear predictor of patient outcomes. Patients who had moderate decrease in NLR during treatment with ICI were found to have the longest survival, whereas a significant decrease or increase in NLR was associated with shorter survival. To our knowledge, this is the first study to demonstrate a non-linear change in NLR over time that correlates with survival.
Keywords: Immune checkpoint inhibitor; Immunotherapy; NLR; Neutrophil to lymphocyte ratio; Prognosis.