Identification and validation of a negative association between cancer cell stemness and ICI outcomes. A, C t-Distributed Stochastic Neighbor Embedding (tSNE) plot of malignant cells from SKCM or BCC. Top tSNE plots depicting the distribution of CytoTRACE scores among malignant cells. Dark-green indicates lower scores (low stemness) while dark-red indicates higher scores (high stemness). Bottom tSNE plots label the malignant cells by response phenotype. B, D raincloud plot of CytoTRACE scores by response phenotype (NR vs. TN) in SKCM cohort or by response phenotype (NR vs. R) in BCC cohort. The center of the box plot are median values, the bounds of the box are 25% and 75% quantiles (Wilcoxon test; *** P < 0.001). Abbreviation: NR, non-responders; R, responders; TN, treatment naïve patients.