Adding Tukysa (chemical name: tucatinib) to the standard of care of Herceptin (chemical name: trastuzumab) and Xeloda (chemical name: capecitabine) continued to improve both progression-free survival and overall survival in people diagnosed with either metastatic or unresectable locally advanced 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), according to the latest results from the HER2CLIMB trial.
The research was presented at the 2021 American Society of Clinical Oncology (ASCO) Annual Meeting. Read the abstract of “Updated results of tucatinib versus placebo added to trastuzumab and capecitabine for patients with pretreated HER2+ metastatic breast cancer with and without brain metastases (HER2CLIMB).”
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.
Unresectable means the breast cancer can’t be removed with surgery.
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, the cells can grow uncontrollably. Tukysa — a pill taken by mouth — blocks a specific area of the HER2 gene in cancer cells, which stops the cells from growing and spreading.
About the HER2CLIMB study
Results from the HER2CLIMB (Study of Tucatinib vs. Placebo in Combination With Capecitabine and Trastuzumab in Patients With Advanced HER2+ Breast Cancer) study presented at the 2019 San Antonio Breast Cancer Symposium led to approval of Tukysa by the U.S. Food and Drug Administration (FDA) in April 2020.
Those results showed that after about 14 months of follow-up, adding Tukysa to Herceptin and Xeloda improved both overall survival and progression-free survival in people diagnosed with metastatic HER2-positive breast cancer that had been previously treated with Herceptin, Perjeta, and Kadcyla.
The HER2CLIMB trial included 612 people diagnosed with metastatic HER2-positive breast cancer. About 99% of the people in the study were women, and everyone in the study had been previously treated with Herceptin, Perjeta, and Kadcyla for metastatic breast cancer; the average was four prior treatment regimens.
The people joined the study between February 2016 and May 2019.
The people were randomly assigned to one of two treatment regimens:
- Tukysa in combination with Herceptin and Xeloda (410 people)
- placebo (a pill that looked just like Tukysa but contained no medicine) in combination with Herceptin and Xeloda (202 people)
About 48% of the people in the study had brain metastases.
Because of the good results, the researchers unblinded the study, which means people in the placebo group could switch to being treated with Tukysa if they wanted to do so. Twenty-six people switched from the placebo group to the Tukysa group.
About the latest analysis
The latest analysis came after 15.6 more months of follow-up, for a total of 29.6 months. The researchers looked at progression-free and overall survival in the two treatment groups.
Progression-free survival was:
- 7.6 months for people treated with Tukysa, Herceptin, and Xeloda
- 4.9 months for people treated with only Herceptin and Xeloda
Overall survival was:
- 24.7 months for people treated with Tukysa, Herceptin, and Xeloda
- 19.2 months for people treated with only Herceptin and Xeloda
In people with brain metastases, Tukysa reduced the risk of death and the risk of the cancer growing by 40%.
In people with visceral metastases (cancer that has spread to the lungs, liver, or other soft internal organs), Tukysa reduced the risk of death and the risk of the cancer growing by 30%.
“Tucatinib in combination with trastuzumab and capecitabine continues to improve progression-free and overall survival in patients with HER2-positive breast cancer,” Giuseppe Curigliano, M.D., Ph.D., associate professor of medical oncology at the University of Milano, said during his presentation on the results. “This combination has the potential to become a new standard of care in this patient population.”
What this means for you
Many doctors agree with the study’s presenters: Adding Tukysa to Herceptin and Xeloda will become the new standard of care for people diagnosed with metastatic HER2-positive breast cancer that has been previously treated with one or more anti-HER2 medicines.
These new results are encouraging and show that Tukysa continues to improve progression-free and overall survival.
If you’ve been diagnosed with HER2-positive breast cancer that is either metastatic or locally advanced and can’t be removed with surgery, and have received at least one anti-HER2 medicine and are now considering which treatments to try next, it makes sense 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
Reviewed by: Brian Wojciechowski, M.D., medical adviser
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