Disitamab Vedotin (RC48) in Hormone Receptor Positive, HER2-low Metastatic Breast Cancer (the Rosy Trial)

Hormone receptor positive, HER2-low expression metastatic breast cancer is the main type of breast cancer, accounting for about 50% - 60%. However, this type of patients lack ideal therapeutic drugs after the failure of first-line standard endocrine therapy, and the median overall survival time is only 30 months. Therefore, finding more efficient and safe therapeutic drugs for these patients has become a big clinical challenge at present. Disitamab Vedotin (DV), as a new class I Antibody-Drug Conjugates drug, can achieve high efficiency and precise tumor killing effect with low toxicity. According to previous study with same sample size, DV also showed good efficacy in metastatic breast cancer with Hormone receptor positive and HER2- low expression as a posterior line treatment.Therefore, we intend to explore the efficacy and safety of DV in the treatment of HER2-low expressioin /Hormone receptor positive metastatic breast cancer patients with endocrine resistance through a scientifically designed, randomized, phase III clinical study.