For people diagnosed with metastatic HER2-positive breast cancer that has spread to the brain, adding Tukysa (chemical name: tucatinib) to the standard treatment regimen of Herceptin (chemical name: trastuzumab) and Xeloda (chemical name: capecitabine) reduced the risk that the brain lesions would grow and also improved survival, according to an exploratory analysis of results from the HER2CLIMB trial.
The research is part of the virtual program for the 2020 American Society of Clinical Oncology (ASCO) Annual Meeting and was published online on May 29, 2020, by the Journal of Clinical Oncology.
- Read the ASCO annual meeting abstract of “Tucatinib versus placebo added to trastuzumab and capecitabine for patients with previously treated HER2+ metastatic breast cancer with brain metastases (HER2CLIMB).”
- Read the Journal of Clinical Oncology abstract of “Intracranial Efficacy and Survival With Tucatinib Plus Trastuzumab and Capecitabine for Previously Treated HER2-Positive Breast Cancer With Brain Metastases in the HER2CLIMB Trial.”
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.
About brain metastases
Metastatic breast cancer is breast cancer that has spread to areas away from the breast, such as the bones, liver, or brain.
Up to half of people diagnosed with metastatic HER2-positive breast cancer have brain metastases. There are limited treatment options for brain metastases because most drugs can’t cross the blood-brain barrier. Many clinical trials studying new treatments for metastatic breast cancer exclude people with brain metastases for this reason.
About this study
Called the HER2CLIMB trial, results from this study presented at the 2019 San Antonio Breast Cancer Symposium led to approval of Tukysa by the U.S. Food and Drug Administration in April 2020.
The results 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%.
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.
This new analysis looked specifically at the 291 people in the HER2CLIMB trial with brain metastases:
- 198 people were treated with Tukysa, Herceptin, and Xeloda
- 93 were treated with Herceptin, Xeloda, and a placebo pill that looked just like Tukysa but contained no medicine
Adding Tukysa to Herceptin and Xeloda increased overall survival, reducing the risk of death by 42%, and also reduced the risk that the brain lesions would grow by about 40%.
Overall, adding Tukysa to Herceptin and Xeloda reduced the risk of brain metastases growth or death by 68%.
“To our knowledge, this is the first regimen to demonstrate improved antitumor activity against [brain metastases] in patients with HER2-positive breast cancer in a randomized, controlled trial,” the researchers concluded.
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 Tukysa 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
Many doctors believe that 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.
The results of this exploratory analysis are especially encouraging if you’ve been diagnosed with metastatic HER2-positive disease that has spread to the brain.
If you have HER2-positive breast cancer that has spread to the brain, have received at least one anti-HER2 medicine, and now are 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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