On April 17, 2020, the U.S. Food and Drug Administration (FDA) approved Tukysa (chemical name: tucatinib) in combination with Herceptin (chemical name: trastuzumab) and Xeloda (chemical name: capecitabine) to treat metastatic HER2-positive breast cancer or locally advanced HER2-positive disease that can’t be completely removed with surgery, after the cancer has been treated with at least one anti-HER2 medicine.
Locally advanced breast cancer is breast cancer that has spread to tissue near the breast, but not to parts of the body away from the breast. Metastatic breast cancer is breast cancer that has spread to parts of the body away from the breast, such as the bones or liver.
Doctors call cancer that can’t be completely removed with surgery “unresectable.”
Tukysa is a tyrosine kinase inhibitor. Tyrosine kinases are enzymes that help control how cells grow and divide, among other functions. If the enzyme is too active or if a cell has too much of the enzyme, it can make cells grow uncontrollably. Tukysa blocks a specific area of the HER2 gene in cancer cells, which stops the cells from growing and spreading.
Tukysa is a pill taken by mouth.
The FDA’s approval of Tukysa is based on results from the HER2CLIMB trial, which showed that adding Tukysa to Herceptin and Xeloda improved both progression-free survival and overall survival in people diagnosed with metastatic HER2-positive breast cancer that had been previously treated with Herceptin, Perjeta (chemical name: pertuzumab), and Kadcyla (chemical name: T-DM1 or ado-trastuzumab emtansine).
The results showed that Tukysa reduced the risk of the cancer growing by 46% and also reduced the risk of a person dying from breast cancer by 46%.
Specifically, for people with brain metastases, adding Tukysa to Herceptin and Xeloda increased overall survival, reducing the risk of death by 34%, and increased progression-free survival by 52%.
Progression-free survival is how long a person lives without the cancer growing. Overall survival is how long a person lives, whether or not the cancer grows.
“With highly significant and clinically important results for overall and progression-free survival, the addition of Tukysa to trastuzumab and capecitabine has the potential to become a standard of care for people with HER2-positive metastatic breast cancer after having received one or more previous anti-HER2 therapies in the metastatic setting,” said Eric Winer, M.D., chief of the Division of Breast Oncology, Susan F. Smith Center for Women's Cancers at Dana-Farber, and member of the Breastcancer.org Professional Advisory Board. “Cancer spreads to the brain in up to half of patients with HER2-positive metastatic breast cancer; and this approval is based on a unique clinical trial that included patients with active brain metastases, either untreated or progressing. Tukysa is well tolerated by patients and is a valuable addition to the agents we have for HER2-positive metastatic breast cancer.”
Tukysa side effects
Like most medicines used to treat cancer, Tukysa can cause side effects, some of them severe.
In the HER2CLIMB trial, the most common side effects in people treated with tucatinib were:
- hand-foot syndrome
The most common severe side effects (grade 3 or higher) in people treated with Tukysa were:
- hand-foot syndrome
- elevated liver enzymes
Overall, 5.7% of people treated with Tukysa, Herceptin, and Xeloda stopped treatment compared to 3% of people treated with only Herceptin and Xeloda.
What this means for you
If you have been diagnosed with locally advanced HER2-positive breast cancer that can’t be removed with surgery or metastatic HER2-positive breast cancer and have received at least one anti-HER2 treatment regimen and are considering which treatments to try next, you may want to talk to your doctor about Tukysa. Together, you can decide if Tukysa is right for you and your unique situation.
Written by: Jamie DePolo, senior editor
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