An elevated systemic inflammation index is related to an inferior response to pomalidomide and dexamethasone treatment in patients with relapsed and refractory multiple myeloma

Introduction: The systemic inflam-mation index (SII) might serve as an indicator of the equilibrium between the inflammatory and immune re-sponses. The aim of the study was to determine the clinical value and prog-nostic significance of SII in the cohort of multiple myeloma (MM) patients treated with a regimen of pomalido-mide and dexamethasone (Pd).Material and methods: This retro-spective, real-life study included pa-tients who received a Pd regimen in our centre between November 2018 and July 2022. The systemic inflam-mation index was calculated from pe-ripheral blood counts of platelets, neu-trophils, and lymphocytes collected shortly before commencement of Pd treatment using the equation: SII = N x P/L, where N, P, and L are the respective counts per litre of pe-ripheral blood for neutrophils, plate-lets, and lymphocytes.Results: The study group consisted of 54 patients. Most patients received Pd as the third (38.9%) or fourth (37.0%) line of treatment. The medi-an number of completed treatment cycles was 5 (IQR: 1-12). The median progression-free survival (PFS) was 6.8 months and overall survival (OS) 14.8 months. High SII (> 374) was an independent prognostic factor for PFS (HR = 3.0, 95% CI: 1.4-6.3, p < 0.01) and OS (HR = 2.2, 95% CI: 1.0-4.6, p = 0.04). In the low SII group, the re-spective median PFS and OS values were 9.6 and 21.7 months, compared to 2.6 (p = 0.018) and 5.5 months (p = 0.035) in the high SII group.Conclusions: The systemic inflamma-tion index has prognostic significance in MM patients treated with Pd. A high SII predicts a poorer outcome in pre-treated MM patients undergoing Pd treatment evaluation. As such, it may well be a key factor for guiding subse-quent treatment decisions.