Among all functional immune subsets elevated in ARID1A-MUT tumors, however, only type 17 T helper cells (Th17) correlated with improved OS in GC patients with chemotherapy (Supplementary Figure S4A, univariate HR: 0.46, P = 0.014; multivariate HR: 0.43, P = 0.014). This evidence concerns the gene ARID1A and gastric cancer.