These findings align with those of previous studies, wherein patients treated with 2 mg/kg RC48 in the C001&C003 pooled analysis achieved a median PFS of 6 months, while those in the HER2-low-expression subgroup attained a median PFS of 5.7 months.31,32 Furthermore, noteworthy responsiveness was observed in patients with HER2-low-expression BC in our study, exemplified by a sixth-line patient treated with RC48 in combination with anti-angiogenic therapy, achieving CR and a remarkable PFS of 15.1 months. This evidence concerns the gene ERBB2 and breast cancer.