Systemic Immune Inflammation Index As a Key Marker of Survival and Immune-related Adverse Events in Immune Checkpoint Inhibitor Therapy.

OBJECTIVE:To evaluate the prognostic significance of the new index designed by formulating neutrophil, lymphocyte, and platelet counts in patients with metastatic disease receiving immune checkpoint inhibitors (ICI) and its effect on the immune-related adverse events (irAEs).STUDY DESIGN:Cohort study.PLACE AND DURATION OF STUDY:Department of Medical Oncology, University of Manisa Celal Bayar, University of Aydin Adnan Menderes, and University of Ege, and Izmir Kent Hospital, Turkey, from January 2016 to April 2020.METHODOLOGY:Patients with metastatic disease receiving ICI sufficient follow-up data were included. Patients, who had received treatment for a minimum of 3 months, were evaluated for the response. Systemic immune-inflammation index (SII) was calculated as neutrophil (/L) × (lymphocyte (/L) / platelet (/L). The cut-off value was determined by examining the area under the receiver operating characteristic (ROC) curve for the SII value. The endpoints of this study included overall survival (OS) and progression-free survival (PFS).RESULTS:A total of 168, patients who received ICI in the metastatic stage, were evaluated. The OS of the patients with low SII scores was 110.8 months (95% CI, 88.2-133.5), while patients with high SII scores were 36.0 months (95% CI, 28.4-43.6) and reached statistical significance (p <0.001). The results of univariate (HR=3.376, 95% CI, 1.986-5.739, p<0.001 and multivariate (HR=2.792, 95% CI, 1.495-5.215, p=0.011) analyses were statistically significant as well.CONCLUSION:The SII score in patients with metastatic disease receiving ICI was closely related to the prognosis. Patients with a high SII score are associated with a worse prognosis, these patients develop fewer irAEs.KEY WORDS:Systemic immune inflammation index, Overall survival, Progression-free survival, İmmune checkpoint inhibitor, Pembrolizumab, Nivolumab.