To explore the clinical relevance of plasma biomarker dynamics during ICI treatment, associations between absolute plasma concentrations of sPD-L1, sPD-1, and WFDC2 at each time point (pre-ICI, after two cycles, and after four cycles) and clinical outcomes—including OS, PFS, and changes in tumor size—were analyzed using Spearman’s rank correlation. This evidence concerns the gene HOXD13 and neoplasm.