ERBB2 and breast carcinoma: The levels of TGFβ1 in EVs are correlated with patients’ response to HER2‐targeted drugs in breast cancer.[66] In addition, the level of circulating exosomal TRPC5 (cirExo‐TRPC5) is associated with that in breast cancer tissues and increased cirExo‐TRPC5 level after chemotherapy precedes progressive disease and strongly predicts acquired chemoresistance.[210] Ciravolo et al. show that around 3/4 of advanced breast cancer patients have HER2+ EVs in the blood, which effectively sequesters trastuzumab monoclonal antibodies, thus impairing its therapeutic efficacy.