In 15 USC cell lines established from fresh tumor biopsy samples, 2.5 μg/mL of T-DM1 and trastuzumab induced potent ADCC in all HER2-overexpressing USC primary cells (mean cytotoxicity ±SEM, 61.6% ± 5.3% vs. 58.4% ± 5.74% (T-DM1 vs. trastuzumab). The gene discussed is ERBB2; the disease is neoplasm.