New research presented at the American Society of Clinical Oncology (ASCO) annual meeting in Chicago, led by Dr. William J. Gradishar of Northwestern Medicine, highlighted significant treatment advances for metastatic breast cancer. The focus was on the drug Enhertu (trastuzumab deruxtecan), which has altered the therapeutic approach for patients diagnosed with HER2-low metastatic breast cancer.
The DESTINY-Breast04 clinical trial demonstrated that Enhertu significantly improved outcomes for these patients compared to conventional chemotherapy. Patients treated with Enhertu achieved a median progression-free survival of 9.9 months, compared to 6.8 months for those on chemotherapy. Furthermore, Enhertu extended the median overall survival to 23.4 months, versus 16.8 months with chemotherapy, indicating a notable improvement in both disease progression and lifespan.
Approximately 50% of all breast cancers are classified as HER2-low, defined by an immunohistochemistry (IHC) score of 1+ or 2+ and negative in situ hybridization (ISH). This group of patients previously lacked targeted treatment options and was typically treated as HER2-negative. The success of Enhertu in this trial provides a new, effective targeted therapy for a substantial population of patients with metastatic breast cancer who previously had limited choices.
