CTLA4 and neoplasm: In this section, we focus on the use of immuno-PET/CT imaging to characterize clinically relevant molecular targets, including general T-cell markers (such as CD3, CD4, and CD8) and immune checkpoints (such as PD-1, PD-L1, and CTLA-4).268,269 We also present the chemical structures of clinically evaluated radiopharmaceuticals involving tumour immune-related targets (Fig. 7).