Grades 3-4 adverse reactions in the novel anti-HER2 ADCs group were mainly neutropenia (20.5%), nausea (12.3%), and vomiting (11.0%), while grades 3-4 adverse reactions in the T-DM1 group were mainly thrombocytopenia (28.1%). The gene discussed is ERBB2; the disease is Decreased total neutrophil count.