Tukysa Plus Standard Care Improves Survival in People With HER2-Positive Brain Mets

Adding Tukysa (chemical name: tucatinib) to the standard of care — Herceptin (chemical name: trastuzumab) and Xeloda (chemical name: capecitabine) — improved overall survival and reduced the risk of new brain lesions in people diagnosed with previously treated, metastatic, HER2-positive breast cancer that had spread to the brain, according to a study.

The research was published in the Feb. 17, 2023, issue of the journal JAMA Oncology. Read “Tucatinib vs Placebo, Both in Combination With Trastuzumab and Capecitabine, for Previously Treated ERBB2 (HER2)-Positive Metastatic Breast Cancer in Patients With Brain Metastases: Updated Exploratory Analysis of the HER2CLIMB Randomized Clinical Trial.”

Overall survival is how long a person lives, whether or not the cancer comes back or grows.

Metastatic breast cancer is cancer that has spread to parts of the body away from the breast, such as the bones, liver, or brain.

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. 

The U.S. Food and Drug Administration (FDA) approved Tukysa in April 2020 after the 2019 results of the HER2CLIMB (Tucatinib vs. Placebo in Combination With Capecitabine and Trastuzumab in Patients With Advanced HER2+ Breast Cancer) study.

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 (chemical name: pertuzumab), and Kadcyla (chemical name: T-DM1 or ado-trastuzumab emtansine).

HER2CLIMB included 612 people. At the beginning of the study, 291 of the people (47.5%) had brain metastases. Of these people, 289 were women and two were men.

In this latest analysis, the researchers looked specifically at people who had brain metastases. 

Half the people were followed for longer than 29.6 months and half were followed for shorter periods of time.

Overall survival was:

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  21.6 months for people who received Tukysa, Herceptin, and Xeloda

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  12.5 months for people who received only Herceptin and Xeloda

The researchers estimated that one-year overall survival rates would be:

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  70% for people who received Tukysa, Herceptin, and Xeloda

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  50.6% for people who received only Herceptin and Xeloda

Two-year overall survival rates would be:

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  48.5% for people who received Tukysa, Herceptin, and Xeloda

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  25.1% for people who received only Herceptin and Xeloda

This means adding Tukysa to the standard of care reduced people’s risk of dying by 40%.

The results also showed that adding Tukysa to Herceptin and Xeloda reduced the risk of new brain lesions by 45.1%.

“This exploratory subgroup analysis showed that tucatinib in combination with trastuzumab and capecitabine provides survival benefits for patients with [brain metastases], has a manageable safety profile, and may delay development of new brain lesions for all patients,” the researchers wrote. “Tucatinib in combination with trastuzumab and capecitabine is an important treatment option for patients with previously treated ERBB2-positive [metastatic breast cancer], including those with brain metastases.”

The HER2CLIMB study continues to be important because it is one of very few studies that allowed people with brain metastases to enroll. Finding new treatments for HER2-positive breast cancer that has spread to the brain continues to be an important unmet need.

If you’ve been diagnosed with metastatic, HER2-positive breast cancer and have brain metastases, the results of this study offer some encouraging news. Adding Tukysa to Herceptin and Xeloda not only improved survival, but also decreased the risk of new brain lesions.

Reports from people who have received Tukysa show that the medicine is relatively well tolerated. People said the treatment had minimal effect on their quality of life and reduced the risk of their quality of life deteriorating from brain metastases by nearly 50%.

If you’ve 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.