(145) evaluated the level of several cytokines in the baseline serum of patients with SCLC receiving chemotherapy alone (n = 47) or combined with Ipilimumab (n = 37) and found that mOS of patients with high baseline IL-2 expression (≥ 1.65 pg/mL) (n = 15) was significantly longer than patients with low-expression (n = 20) (30.5 vs. 8 months, P = 0.015) in the ICI-combo cohort but not the chemotherapy cohort (12.2 vs. 12.6 months, P = 0.273), suggesting that the baseline IL-2 level in patients with SCLC can predict the benefit of ICI-combo. This evidence concerns the gene IL2 and small cell lung carcinoma.