To determine whether T cell populations in blood reflected those within tumors of patients with muscle-invasive bladder cancer, CD4+ and CD8+ T cells were flow sorted from PBMCs from patients from whom tumor and NAT sequencing was previously obtained (7) (Figure 1A and Supplemental Dataset 1; supplemental material available online with this article; https://doi.org/10.1172/jci.insight.177373DS1). The gene discussed is CD8A; the disease is urinary bladder cancer.