FDA Approves TUKYSA (tucatinib) Combination as a New Maintenance Treatment Option for HER2-Positive Metastatic Breast Cancer
What people with HER2-positive metastatic breast cancer should know about TUKYSA, Herceptin, and Perjeta.
SurvivingBreastCancer.org Editorial EDUCATION | HER2+
Key Takeaways
The FDA approval of TUKYSA (tucatinib) with Herceptin (trastuzumab) and Perjeta (pertuzumab) gives some adults with HER2-positive metastatic breast cancer a new chemotherapy-free maintenance treatment option after initial therapy.
In the HER2CLIMB-05 trial, this combination helped people go longer before their cancer grew or spread compared with Herceptin and Perjeta alone.
This treatment will not be right for everyone, but it may be an important option to discuss with your oncology team.
The U.S. Food and Drug Administration has approved a new use for TUKYSA (tucatinib) in combination with trastuzumab (Herceptin) and pertuzumab (Perjeta) for people living with HER2-positive metastatic breast cancer (MBC) or unresectable locally advanced HER2-positive breast cancer after initial treatment.
In plain language, this means that some people with HER2-positive metastatic breast cancer may now have a new chemotherapy-free maintenance treatment option after their first phase of treatment.
This approval is important because it may help some people living with metastatic breast cancer go longer before their cancer grows or spreads.
Let’s start with the basics:
What is HER2-positive breast cancer?
HER2 is a protein that helps cells grow. In some breast cancers, the cancer cells make too much HER2, which can cause the cancer to grow and spread more quickly. This is called HER2-positive breast cancer.
HER2-positive breast cancer is often treated with medicines that specifically target HER2. These include drugs such as:
trastuzumab (Herceptin)
pertuzumab (Perjeta)
tucatinib (TUKYSA)
These are called HER2-targeted therapies because they are designed to interfere with the HER2 signals that help cancer cells grow.
What was approved?
The FDA approved TUKYSA (tucatinib) to be used with Herceptin (trastuzumab) and Perjeta (pertuzumab) as a maintenance treatment for people living with HER2-positive metastatic or unresectable locally advanced breast cancer after initial treatment.
This approval applies after a person has already received initial treatment with:
Herceptin (trastuzumab)
Perjeta (pertuzumab)
a taxane chemotherapy, such as paclitaxel (Taxol) or docetaxel (Taxotere)
and their cancer has grown or progressed during that first phase of treatment.
What does “maintenance treatment” mean?
Maintenance treatment is treatment given after an initial treatment has helped control the cancer.
We can think of it this way: The first phase of treatment is often used to get the cancer under control. If the cancer is shrinking, stable or responding to the treatment, maintenance treatment may be used to help keep the cancer controlled for as long as possible.
For HER2-positive metastatic breast cancer, maintenance treatment often includes Herceptin (trastuzumab) and Perjeta (pertuzumab). This new approval adds TUKYSA (tucatinib) to that maintenance approach for eligible patients.
Why is this approval important?
In the Phase 3 HER2CLIMB-05 clinical trial, people who received TUKYSA (tucatinib) with Herceptin (trastuzumab) and Perjeta (pertuzumab) went longer before their cancer grew or spread compared with people who received Herceptin and Perjeta without TUKYSA.
The study found:
People receiving the TUKYSA combination had a median of 24.9 months before the cancer grew or spread.
People receiving Herceptin and Perjeta without TUKYSA had a median of 16.3 months before the cancer grew or spread.
This means the TUKYSA combination added a median of 8.6 more months without disease progression.
The treatment reduced the risk of cancer progression by about 36% in the study.
What does “progression-free survival” mean?
You may see the phrase progression-free survival, often shortened to PFS.
Progression-free survival means the amount of time during and after treatment that the cancer does not grow or spread.
It does not mean the cancer is cured. It means the treatment helped keep the cancer controlled for a period of time.
In this trial, the TUKYSA combination helped people go longer before the cancer grew or spread.
Is TUKYSA (tucatinib) chemotherapy?
TUKYSA is not traditional chemotherapy.
TUKYSA is an oral targeted therapy. It is a pill that targets HER2, a protein involved in the growth of some breast cancer cells. Pfizer describes TUKYSA as an oral HER2 tyrosine kinase inhibitor.
Herceptin and Perjeta are also HER2-targeted treatments, but they are given differently. They may be given through an IV or as part of a fixed-dose injection option, depending on the treatment plan.
This approval is being described as a chemotherapy-free maintenance option because it may allow eligible patients to continue HER2-targeted treatment after initial chemotherapy without staying on traditional chemotherapy during the maintenance phase.
Who might this apply to?
This approval may apply to people with:
HER2-positive metastatic breast cancer
HER2-positive unresectable locally advanced breast cancer
no cancer progression after initial treatment with Herceptin, Perjeta, and a taxane chemotherapy
Your oncology team can help determine whether this treatment is appropriate based on your diagnosis, prior treatment, cancer behavior, side effects, other health conditions, and personal goals.
What side effects should patients know about?
Pfizer reported that the most common side effects in the HER2CLIMB-05 trial included diarrhea, muscle and joint pain, liver-related lab abnormalities or liver toxicity, nausea, fatigue, rash, and vomiting.
What should I ask my oncology team?
If you are taking or considering TUKYSA, ask your care team:
Am I currently in the induction or maintenance phase of treatment?
What does maintenance therapy mean in my treatment plan?
Would TUKYSA be an option for me?
What are the possible benefits of adding TUKYSA?
How will my liver function be monitored?
What should I do if I develop diarrhea?
What side effects should I report right away?
How will we know if the treatment is working?
How often will I need bloodwork?
Could this interact with any other medicines I take?
Are there reasons this treatment may not be right for me?
How does this option fit with my goals and quality of life?
At SurvivingBreastCancer.org, we believe patients and families deserve clear, evidence-based information that helps them ask informed questions and feel more confident in conversations with their medical team.
Disclaimer: This article is for educational purposes only and is not medical advice. Treatment decisions are personal and should be made in partnership with your oncology team.
