Trastuzumab Rezetecan Significantly Reduces Progression Risk in HER2-Low Advanced Breast Cancer

The HORIZON-Breast06 randomized clinical trial, published in JAMA, demonstrated that trastuzumab rezetecan reduced the risk of progression by 73% in patients with HER2-low advanced breast cancer. This efficacy was observed across both hormone receptor-positive and HR-negative HER2-low disease, indicating that HER2-low breast cancer has become a therapeutically actionable phenotype.