ERBB2 and breast cancer: Furthermore, similar to EGFR/HER2, FGFR3 exhibits robust receptor internalization upon antibody binding, a feature that facilitates efficient intracellular delivery of the cytotoxic payload and enhances the antitumor activity of ADCs.[35] After validating FGFR3 as a BC‐specific target for ADC therapy, we employed a humanized IgG1 antibody as the drug carrier to confer an extended plasma half‐life, thereby facilitating adequate tumor penetration of the ADC.