To assess the capacity for intracellular release of the drug payload, the in vitro cytotoxic activity of the antibody-drug conjugate bound to the nanoparticles (ADC-PEG-AuNP) was evaluated in two HER2 amplified cell lines: (1) SKBR-3 and (2) SKOV-3 (ovarian adenocarcinoma). Here, ERBB2 is linked to ovarian adenocarcinoma.