Breast cancer is the second most common cancer and one of the major causes of cancer related deaths worldwide. Globally, there will be more than 2 million breast cancer patients and more than 665000 deaths in 2020. At the annual meeting of the American Society of Clinical Oncology (ASCO annual meeting) held from May 31 to June 4 local time, the positive results of the DESTINY-Break06 phase III trial of a unique design of antibody coupling drug (ADC), which was jointly developed and commercialized by AstraZeneca and First Three, released by Detrutuzumab, an antibody targeting HER2, showed that in patients with HR positive, HER2 low expression (IHC 1+or 2+/ISH -) metastatic breast cancer, the progression free survival period had a statistically and clinically significant improvement compared with standard chemotherapy. The preliminary analysis results of the DESTINY-Break06 trial showed that, measured by blinded independent central review (BICR), trastuzumab reduced disease progression or mortality by 38% compared to chemotherapy in patients with HER2 low expression. Compared to the median progression free survival of 8.1 months in chemotherapy, the median progression free survival of trastuzumab reached 13.2 months. Professor Giuseppe Curigliano, MD, Medical School of Milan University, Italy, director of the early drug development department of the European Cancer Research Institute, and the main researcher of this clinical trial, pointed out that "endocrine therapy is widely used in the early treatment of HR positive metastatic breast cancer, but after first-line or multi line treatment, patients often have limited efficacy from further endocrine therapy. The median progression free survival period of DESTINY-Break06 is more than one year, which shows that Detriazumab can become a new treatment standard after HER2 low expression and HER2 ultra low secretion therapy in patients with metastatic tumors. (Lai Xin She)