The specificity of the tracer was further validated by comparing the uptake of a non-binding variant of the peptide in the uPAR-positive U87MG xenograft and by performing a blocking experiment using excessive pre-dose of non-labeled peptide resulting in reduced tumor uptake, thus illustrating the specificity of 64Cu-DOTA-AE105 for non-invasive PET imaging of uPAR [35]. Here, PLAUR is linked to neoplasm.