A new treatment might soon be available for advanced breast cancer patients. Researchers are examining the cancer-fighting drug trastuzumab rezetecan for those with ERBB2-low metastatic breast cancer, characterized by low HER2 protein levels.
Clinical Trial Findings
The HORIZON-Breast06 phase 3 clinical trial compared the effectiveness of this drug to standard chemotherapy. Researchers conducted the study with 551 female patients in 73 Chinese hospitals. Patients either received the drug intravenously every three weeks or doctors chose a chemotherapy option. The study spanned from June 2023 to August 2025.
Results showed the drug significantly delayed cancer progression compared to chemotherapy. The median progress-free survival with the drug was 16.4 months, while chemotherapy offered 6.8 months.
Impact on Survival Rates
Patients taking trastuzumab rezetecan were 73% less likely to experience worsened cancer or death during the study. At the 12-month mark, 90.6% of drug recipients were alive compared to 81.4% among chemotherapy patients.
Response from the Medical Community
The results published in JAMA indicate substantial benefits for patients with both hormone receptor-positive and hormone receptor-negative breast cancer. Dr. Loren Rourke, a breast surgical oncologist, recognized the findings as encouraging, noting it offers patients more time and potential quality of life improvements. Rourke emphasized the importance of understanding side effects, pointing out that they can significantly affect patients’ quality of life.
Considerations and Side Effects
While less serious lung issues were noted compared to other treatments, side effects like anemia and blood-related issues were associated with trastuzumab rezetecan. Serious side effects occurred in over 84% of these patients, compared to nearly 68% with chemotherapy. The need to balance the benefits of delayed cancer progression with potential side effects remains critical.
Researchers acknowledged the higher toxicity rates, typically requiring dose modifications. They considered these effects generally manageable but stressed the need for more research to fully understand the treatment’s impact.
Future Research Directions
Further investigation is needed to determine if the drug extends life expectancy. Dr. Rourke highlighted the importance of celebrating these advancements while addressing unanswered questions about long-term outcomes.
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