Kaplan‒Meier analyses of overall survival (OS) in patients receiving ICIs revealed that the S100A1low group achieved a longer OS than did the S100A1high group across multiple immunotherapy cohorts, including melanoma,14 bladder cancer (BLCA),16 and metastatic urothelial carcinoma (mUC)17 cohorts (all log-rank p < 0.01) (Fig. 1d–f), suggesting the potential of S100A1 in determining immunotherapy efficacy. Here, S100A1 is linked to bladder transitional cell carcinoma.