In brain tumors, Nagle et al. developed a 64Cu-labeled NOTA-anti-CD8 minibody tracer to image CD8-positive T-cells.28 In humanized mice bearing orthotopic glioblastoma xenografts, the tracer specifically accumulated in the spleen, lymph nodes, and tumor regions with dense CD8-positive T-cell infiltrates, surpassing background uptake in normal brain. The gene discussed is CD8A; the disease is neoplasm.