Novel routes for targeting Siglec–sialic-acid interactions were reviewed by Daly et al. in 2019,50 including Bertozzi’s approach to target and de-sialylate cancer cells using a sialidase (from Vibrio cholera) conjugated to the HER2-targeting antibody Trastuzumab.196 The antibody–sialidase conjugate exhibited enhanced tumour cell killing in HER2-positive breast cancer cells compared with the antibody alone. Here, ERBB2 is linked to breast cancer.