Insights on Tucatinib Regimens in HER2+ Breast Cancer Treatment

Sarah Sammons, MD, medical oncologist, clinical investigator in the Breast Oncology Center, associate director of the Metastatic Breast Cancer Program, Dana-Farber Cancer Institute, discusses some of the challenges seen with different regimens for HER2-positive metastatic breast cancer treatment

The treatment landscape for HER2-positive metastatic breast cancer has significantly improved in recent years, with the introduction of 2 highly effective regimens: trastuzumab deruxtecan (Enhertu; T-DXd) and the combination of tucatinib (Tukysa), capecitabine, and trastuzumab (Herceptin). Both regimens offer distinct advantages and potential adverse effects (AEs).

According to Sammons, trastuzumab deruxtecan has shown impressive efficacy but carries a risk of pneumonitis and hair loss. The tucatinib-containing regimen offers a less invasive treatment option with a lower risk of hair loss. However, it can lead to AEs such as diarrhea, nausea, fatigue, and liver enzyme elevations.

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0:09| There are challenges with any regimen that we use in metastatic breast cancer. All therapies have [adverse] effects. With trastuzumab deruxtecan, that is a regimen that is given [intravenously] once every 3 weeks. There is about a 15% risk of pneumonitis, which is inflammation of the lungs. There is hair loss for the majority of patients, and so that is the real risk. Then there has been nausea, and we manage that with antiemetics.

0:45 | For the tucatinib, capecitabine, trastuzumab regimen, 2 of the drugs are oral, and trastuzumab is given either by injection or intravenously. There is not any hair loss which is nice, but there are a lot of pills, there is still a risk of diarrhea, still a bit of a risk of nausea, fatigue, and we have to monitor liver enzymes as well. With the capecitabine, sometimes people can get a rash on their hands and feet, but most breast oncologists are becoming pretty familiar with managing both regimens at this point. I think most of our patients with HER2-positive metastatic breast cancer will receive both of those therapies, both T-DXd and the tucatinib-containing regimen. It is nice to have 2 good options for these patients that we did not have a couple of years ago.