A promising new treatment has shown remarkable results in slowing the progression of HER2-positive metastatic breast cancer, offering new hope for patients facing this aggressive form of the disease.
Presented at the annual meeting of the American Society for Clinical Oncology on June 2, the study revealed that a drug combination involving trastuzumab deruxtecan (T-DXd) and pertuzumab reduced the risk of disease progression or death by 44% compared to the current standard therapy.
HER2-positive breast cancer, which accounts for about 15–20% of all breast cancer cases, is driven by an overactive HER2 gene that accelerates tumor growth. For patients whose cancer has spread to other parts of the body, average survival is roughly five years. Until now, few advances had significantly improved first-line treatment options.
Dr. Sara Tolaney, chief of the breast oncology division at Dana-Farber Cancer Institute and the trial’s lead investigator, described the findings as “really impressive.”
“We were taking a standard and almost doubling how long patients could have their cancer controlled for,” Tolaney told AFP. She added that the drug’s mechanism acts like a “smart bomb,” delivering chemotherapy directly into cancer cells with greater precision and fewer off-target effects.
In the global trial, nearly 400 patients were treated with the new T-DXd and pertuzumab combination, while another group received the traditional THP regimen—a chemotherapy and antibody blend. At 2.5 years of follow-up, the median progression-free survival for the new therapy reached 40.7 months, far surpassing the 26.9 months seen with the standard care.
Complete response rates were also higher, with 15% of patients in the T-DXd group showing total cancer disappearance, compared to 8.5% in the THP group.
While some side effects like nausea, diarrhea, and reduced white blood cell counts were reported, Tolaney emphasized the importance of ongoing research to optimize treatment duration, especially for patients showing full remission.
Dr. Rebecca Dent, a breast cancer expert from the National Cancer Center Singapore who was not involved in the research, said the breakthrough “represents a new first-line standard treatment option for HER2-positive metastatic breast cancer.”
The study’s results are set to be submitted to global regulatory bodies, including the U.S. Food and Drug Administration, possibly paving the way for a major shift in how this form of breast cancer is treated.
