JAMA October 2026 Trastuzumab Rezetecan in ERBB2-Low Advanced Breast Cancer The HORIZON-Breast06 Randomized Clinical Trial

The HORIZON-Breast06 clinical trial investigated the effectiveness of trastuzumab rezetecan compared to standard chemotherapy for individuals suffering from ERBB2-low advanced breast cancer. Conducted across numerous medical centers in China, the multi-center study randomly divided 551 eligible participants into two distinct treatment groups. The primary focus of the research was to measure progression-free survival rates among both chemotherapy-naive patients and the broader participant pool. Findings revealed that the novel drug substantially extended progression-free survival compared to traditional chemotherapy options, showing consistent advantages across various patient subgroups. Ultimately, the therapy established its potential as a promising alternative treatment, despite noting a higher frequency of severe adverse events primarily related to lowered neutrophil counts.