The results of their experiments showed that the new ADC (trastuzumab‐MC‐Val‐Cit‐PABC‐MMAE) and parental mAb had similar affinity on HER2-positive cells, while the ADC can significantly induce the death of HER2+ tumor cells, but no response to HER2‐ cells in vitro. The gene discussed is ERBB2; the disease is neoplasm.