CD274 and neoplasm: Radioligand [64Cu]Cu-4 showed a small blocking effect (after 500/1000 nmol unlabeled 4) on SUVmax in the PD-L1-expressing tumor (0–2h: −57%, 4–5 h: −12% and 24–25 h: −45%).However, this effect was also observed in the mock tumor to a certainextent, primarily at 24–25 h, again pointing to nonspecificor metabolite accumulation.