Systemic Immune-Inflammation Index in Patients Treated With First-Line Immune Combinations for Metastatic Renal Cell Carcinoma: Insights From the ARON-1 Study

Background: Systemic treatment with immune combinations is the gold standard for metastatic renal cell carcinoma (mRCC) worldwide. The systemic immune-inflammation index (SII) is a prognostic marker for several types of malignant neoplasms, including mRCC, in the era of tyrosine kinase inhibitor (TKI) treatment. Data regarding the prognostic value of the SII in patients with mRCC treated with immunotherapy are scarce and controversial.  METHODS: We retrospectively collected the data of patients with mRCC from 56 centers in 18 countries. SII (Platelet × Neutrophil/Lymphocyte count) was calculated prior to the first systemic treatment and cut-off was defined by a survival receiver operating characteristic (ROC) analysis. The primary objective of our retrospective study was to assess the outcomes of patients treated with first-line immunotherapy.  RESULTS: Data from 1034 mRCC patients was collected and included in this analysis. The SII cut-off value was 1265. After a follow-up of 26.7 months, and the overall survival (OS) and progression-free survival (PFS) were 39.8 and 15.7 months, respectively. According to SII (low vs. high), patients with low-SII had longer OS (55.7 vs. 22.2 months, P < .001), better PFS (20.8 vs. 8.5 months, P < .001), and higher overall response rate (52 vs. 37%, P = .033). Conclusion: A high SII is associated with poor oncological outcomes in patients with mRCC. SII could be an easily accessible prognostic indicator for use in clinical practice.