GRPR and neoplasm: Thus, in an interesting study, the GRPR antagonist AR (H-PEG4-JMV594) carrying four different radiometal chelates on its N-terminus ([111In]In-DOTA, [99mTc]Tc-N4, [68Ga]Ga-NODAGA, and [64Cu]Cu-CB-TE2A), confirmed the superiority of positively charged conjugates ([99mTc]Tc-N4-AR and [64Cu]Cu-CB-TE2A-AR) in terms of GRPR affinity and tumor uptake and retention.