To gain insight into the genetic landscape of tumors that are responsive or resistant to ICIs, we integrated the published bulk RNA-seq data of a melanoma immunotherapy cohort (GSE91061)14 and a single-cell RNA sequencing (scRNA-seq) dataset of patients with breast cancer receiving anti-PD-1 treatment (EGAS00001004809).15 We first compared the transcriptomes of paired pretreatment versus on-treatment samples and nonresponders versus responders in GSE91061; we also compared the transcriptomes of pretreatment versus on-treatment tumor cells in EGAS00001004809. Here, PDCD1 is linked to breast cancer.