Spearman’s Rank Correlation Test indicated positive correlations between the relative abundance median values of bacteria (at the genus level) in the Ig-bound and total stool microbiota in all advanced melanoma patients undergoing anti-PD-1 therapy (Figure 8A,B), in the subgroups with favorable clinical outcomes, i.e., in the CB (Figure 8C,D) and R subgroups (Figure S3A,B), and those with unfavorable ones, i.e., the NB (Figure 8E,F) and NR subgroups (Figure S3C,D) at T0 and T1, respectively (p-value ≤ 0.05). The gene discussed is PDCD1; the disease is melanoma.