Application for Clinical Practice and System Implementation
The results of the current studies show a longer progression-free survival with trastuzumab deruxtecan in both HER2-low expressing metastatic breast cancer and HER2-positive metastatic breast cancer following taxane and trastuzumab-based therapy. These results are clearly practice changing and represent a new standard of care in these patient populations. It is incumbent upon treating oncologists to work with our pathology colleagues to assess HER2 IHC thoroughly in order to identify all potential patients who may benefit from trastuzumab deruxtecan in the metastatic setting. The continued advancement of anti-HER2 therapy will undoubtedly have a significant impact on patient outcomes going forward.
Practice Points
- With a hazard ratio of 0.28 for disease progression or death, the efficacy of trastuzumab deruxtecan highlighted in the DESTINY-Breast03 trial clearly makes this the standard of care in the second-line setting for patients with metastatic HER2-positive breast cancer.
- In the DESTINY-Breast04 trial, a significant and clinically meaningful improvement in both progression-free survival and overall survival compared with chemotherapy was seen in patients with metastatic breast cancer with low expression of HER2, including both the estrogen receptor–positive cohort as well as the entire population, including those with pre-treated triple-negative disease.
—Daniel Isaac, DO, MS