Baseline neutrophil-to-lymphocyte ratio is associated with outcome of ipilimumab-treated metastatic melanoma patients

Background: Ipilimumab improves the survival of metastatic melanoma patients. Despite documented, durable objective responses, a significant number of patients fails to benefit from treatment. The aim of this study was to identify an upfront marker for treatment benefit. Methods: A total of 187 metastatic melanoma patients treated in three Italian Institutions with 3 mg kg-1 ipilimumab, and 27 patients treated with 10 mg kg-1 ipilimumab, were evaluated. Neutrophil-to-lymphocyte ratio (NLR) was calculated from pre-therapy full blood counts. Progression-free survival (PFS) and overall survival (OS) were assessed using the Kaplan-Meier method, and multivariate Cox models were applied, adjusting for confounders and other prognostic factors. Results: In the training cohort of 69 patients treated at European Institute of Oncology, pre-therapy NLR was identified as the strongest and independent marker for treatment benefit in multivariate analyses. Patients with baseline NLR<5 had a significantly improved PFS (HR=0.38; 95% CI: 0.22-0.66; P=0.0006) and OS (HR=0.24; 95% CI: 0.13-0.46; P<0.0001) compared with those with a NLR≥5. Associations of low NLR with improved survival were confirmed in three validation cohorts of patients. Conclusion: Our findings show that baseline NLR is strongly and independently associated with outcome of patients treated with ipilimumab, and may serve to identify patients most likely to benefit from this therapy.