ERBB2 and breast cancer: N‐2‐(4‐[18F]fluoro‐benzamido)ethyl]maleimide ([18F]FBEM, Scheme 2) is also an effective reagent for tagging thiol groups that has been used to develop a HER2‐binding cysteine rich affibody molecule.35 The presence of cysteine in the C‐terminus of the HER2 affibody molecule ZHER2:2891 has been exploited for labelling by three methods: silicon‐fluoride acceptor approach [18F]SiFA, [18F]AlF‐NOTA, and 4‐[18F]fluorobenzaldehyde ([18F]FBA); [18F]FBA was the favoured candidate for further development and characterisation in mouse models of breast cancer.36, 37