Revisiting the F3 Peptide: In Vitro Investigations of C- and N-Terminally Modified Peptide Conjugates for Radiotracer Development

: A standardized in vitro protocol for evaluating F3 peptide conjugates on cancer cells was established, revealing that the C-terminus is the preferred site for modification. Because the cellular uptake of the radiotracer was shown to likely not be sufficient for radiotracer development, further studies on the optimization of the F3 peptide conjugates, including structural modifications, are required.