Targeted Drug Trastuzumab Deruxtecan Slows Growth of Metastatic Breast Cancer

Trastuzumab deruxtecan (Enhertu) is an example of targeted therapy for breast cancer. A new study of this targeted drug showed that in people with metastatic HR+ and HER2-low and ultra-low breast cancer,  it can prevent the cancer from growing for a longer period of time when compared to chemotherapy.

Breast cancer is a very common cancer in women in the United States. About 1 in 3 of all new female cancers each year are breast cancer.  Treatment of breast cancer is based on many factors. One of these is which receptors are found on the cancer cells. If a breast cancer is hormone receptor-positive (HR+), endocrine therapy may be offered as part of the treatment plan. If the breast cancer is human epidermal growth factor receptor 2 positive (HER2+), HER2-targeted therapy may be offered.

The HER2-targeted therapy drug trastuzumab deruxtecan is an antibody-drug conjugate (ADC). It’s made up of a lab-made antibody that targets the HER2 protein, which is linked to a chemotherapy drug. The antibody acts like a homing signal by attaching to the HER2 protein on cancer cells, bringing the chemo directly to them. Enhertu is given as an intravenous (IV) infusion.

Prior to this study, referred to as the DESTINY-Breast06 trial, trastuzumab deruxtecan was typically only offered to this patient population after they received chemotherapy. The patients in the study, however, had received endocrine therapy but not chemotherapy. The data shows that trastuzumab deruxtecan stopped cancer growth for about 13 months in the patients who received it. This was 5 months longer than the patients who received chemotherapy.

“The DESTINY-Breast06 trial results are very exciting because they show that more patients than before may have the opportunity to undergo treatment with trastuzumab deruxtecan,” said American Society of Clinical Oncology (ASCO) expert Norah Lynn Henry, MD, PhD, FASCO, medical oncologist and interim Division Chief of Hematology/Oncology at the University of Michigan.

Trastuzumab deruxtecan side effects

This drug can cause low blood cell counts, which can increase a person’s risk of infections and bleeding. Other common trastuzumab deruxtecan side effects can include nausea, vomiting, diarrhea or constipation, loss of appetite, fever, feeling tired, and hair loss.

This drug can cause serious lung disease in some people, which might even be life threatening. It’s very important to let your doctor or nurse know right away if you’re having symptoms such as coughing, wheezing, trouble breathing, or fever.

This drug can also rarely cause heart damage. Before starting treatment with this drug, your doctor may test your heart function with an echocardiogram or a MUGA scan.

Talking about your treatment options with your cancer care team

If you have metastatic breast cancer, it is important to talk with your care team about treatment options. Consider asking:  

• What type and stage of breast cancer do I have?
• What treatment plan do you recommend?
• What are the potential side effects of the recommended treatment?
• What can be done to prevent or relieve these side effects?
• Are there clinical trials that may be an option for me based on my diagnosis?

Read a patient-friendly summary of this research.