How to Select Patients for Trastuzumab Deruxtecan

Sara Tolaney, MD, MPH, Dana-Farber Cancer Institute, Boston, Massachusetts, discussed best strategies for selecting patients with HER2 low breast cancer for treatment with trastuzumab deruxtecan.

Dr Tolaney touched on biomarker data from the Destiny-Breast04 trial and the correlation between tumor characteristics and efficacy of trastuzumab deruxtecan among patients with metastatic HER2 low breast cancer.

Transcript

My name is Sara Tolaney. I'm a breast medical oncologist at Dana-Farber Cancer Institute. One of the big questions that we have is how do we select patients for trastuzumab deruxtecan?

We've seen data from DESTINY-Breast04 suggesting that when trastuzumab deruxtecan was compared to standard chemotherapy in patients with metastatic HER2 low breast cancer, that in fact trastuzumab deruxtecan resulted in a doubling of progression-free survival and a significant improvement in overall survival. Here at the San Antonio Breast Cancer Symposium, we can see the biomarker data from DESTINY-Breast04, where they looked at tumor characteristics for the patients who had to have central confirmation of HER2 low for eligibility. They looked at the tumor samples that were sent in for central confirmation and looked at the correlation with efficacy. They saw that trastuzumab deruxtecan was superior to standard chemotherapy irrespective of tumor characteristics. Whether the tissue was off a primary tumor or a metastatic tumor, whether the sample was an old sample or a more recent sample, the benefit was the same.

I think this is important information because we struggle a lot clinically to understand how to best select patients for HER2-low status. Does it need to be, for example, off the most recent biopsy prior to initiation of trastuzumab deruxtecan? I think the data doesn't show how maybe trastuzumab deruxtecan could benefit someone whose HER2 low status changed over time. At least it tells us that if you tested a primary tumor, it still was predictive of benefit for trastuzumab deruxtecan in the metastatic setting. I think it was very helpful information for us to have.