Enhertu Beats Chemotherapy for HER2-Low and -Ultralow Metastatic Breast Cancer
People diagnosed with pretreated metastatic hormone receptor-positive breast cancer with low and ultralow levels of HER2 receptors lived longer without the cancer growing when they received Enhertu (chemical name: fam-trastuzumab deruxtecan-nxki) instead of chemotherapy. These results from the DESTINY-Breast06 study were presented at the 2024 American Society for Clinical Oncology (ASCO) Annual Meeting.
Key takeaways
People with metastatic HER2-low and -ultralow breast cancer who received Enhertu lived about 13 months without the cancer growing (also called progression-free survival). People who received chemotherapy lived about 8 months before the cancer grew.
Only people with metastatic, hormone receptor-positive breast cancer that grew while being treated with hormonal therapy were included in the study.
People who received Enhertu were able to stay on the medicine longer, for about 11 months compared to about six months for people who received chemotherapy.
An estimated 85% of people with metastatic, hormone receptor-positive breast cancer could benefit from receiving Enhertu.
The researchers recommended that Enhertu should be the standard of care for hormone receptor-positive, HER2-low and -ultralow breast cancer that has grown after treatment.
What the results mean for you
If you’ve been diagnosed with metastatic, hormone receptor-positive breast cancer with any levels of HER2 that has grown during treatment with hormonal therapy, you may want to ask your doctor if Enhertu rather than chemotherapy should be the next treatment.
Both Enhertu and chemotherapy can cause side effects, some of them severe. Overall, about 20% of people receiving Enhertu and about 16% of people receiving chemotherapy in this study had a serious side effect.
Enhertu is approved by the U.S. Food and Drug Administration (FDA) to treat metastatic, HER2-low breast cancer, but not HER2-ultralow. Because it’s not FDA-approved for this use, it’s unclear if insurance will cover Enhertu for HER2-ultralow disease.
About the study
The study included 866 people diagnosed with metastatic, hormone receptor-positive breast cancer that was HER2-low or -ultralow. All the cancers had grown while being treated with hormonal therapy and none of the people had received chemotherapy for metastatic breast cancer.
The researchers defined a cancer as being HER2-ultralow if it had an IHC HER2 score of 0, with faint staining of the membranes of up to 10% of the cancer cells. The study participants included:
713 with HER2-low breast cancer
153 with HER2-ultralow breast cancer
The group was split in half: one group received Enhertu and the other received their doctors’ choice of chemotherapy. The chemotherapy medicines used were:
Xeloda (chemical name: capecitabine)
Abraxane (chemical name: albumin-bound or nab-paclitaxel)
Taxol (chemical name: paclitaxel)
Detailed results
After about 18 months of follow-up, progression-free survival was:
about 13 months for Enhertu
about 8 months for chemotherapy
These results were the same for both people with HER2-low and -ultralow disease.
The results were statistically significant, which means that the difference in progression-free survival was likely due to the difference in treatments and not just because of chance.
Among people receiving Enhertu:
14.3% stopped treatment because of side effects
48.4% had a dose interruption because of side effects
24.7% received a lower dose because of side effects
Among people receiving chemotherapy
9.4% stopped treatment because of side effects
38.4% had a dose interruption because of side effects
38.6% received a lower dose because of side effects
In the study, 11.3% of the people receiving Enhertu developed interstitial lung disease or pneumonia. Interstitial lung disease is a general term for conditions that cause inflammation and scarring in the lungs. Severe lung problems, including pneumonia and interstitial lung disease, are a known side effect of Enhertu.
“DESTINY-Breast06 establishes trastuzumab-deruxtecan as an effective new treatment option for patients with hormone-receptor-positive, HER2-low and HER2-ultralow metastatic breast cancer following one or more endocrine-based therapies,” concluded Giuseppe Curigliano, MD, PhD, professor of medical oncology at the University of Milan and chief of the Clinical Division of Early Drug Development at the European Institute of Oncology, who presented the research.
Curigliano, G. et al. Trastuzumab deruxtecan (T-DXd) vs physician’s choice of chemotherapy (TPC) in patients (pts) with hormone receptor-positive (HR+), human epidermal growth factor receptor 2 (HER2)-low or HER2-ultralow metastatic breast cancer (mBC) with prior endocrine therapy (ET): Primary results from DESTINY-Breast06 (DB-06). ASCO 2024. Abstract LBA 1000.
Updated on December 12, 2024
This content made possible, in part, by a grant from Lilly.