How effective is tucatinib (Tukysa) for breast cancer?

Tukysa (tucatinib) has been shown in studies to help reduce the risk of breast cancer growing or spreading and has helped those with advanced or metastatic HER2 positive breast cancer live longer, including people whose cancer has spread to their brain. HER2 is a protein that contributes to cancer cell growth.

HER2CLIMB Study: Overview

• In the HER2CLIMB study, 612 patients received either Tukysa 300 mg orally twice daily plus trastuzumab and capecitabine or a placebo pill (with no active ingredient) plus trastuzumab and capecitabine.
• Patients were treated until disease progression or the patient had unacceptable toxicity (side effects). The median duration of treatment was 5.8 months (ranging from 3 days to 2.9 years) for the Tukysa arm.
• The major efficacy outcome measure was progression-free survival (PFS).

Patients who received Tukysa with trastuzumab (Herceptin) and capecitabine (Xeloda) had a significant 46% reduction in the risk of cancer progression (cancer growing or spreading) or death (progression-free survival) compared to a group who received trastuzumab and capecitabine plus placebo.

The median time without disease progression was 7.8 months with Tukysa compared to 5.6 months with the placebo combination group.

In addition, the risk of cancer progression or death was also significantly reduced by 52% in patients with brain metastases (cancer that had spread to the brain).

Tukysa helped people live longer with a median overall survival of 21.9 months (range of 18.3 to 31 months) with Tukysa vs 17.4 months (range of 13.6 to 19.9 months) with trastuzumab and capecitabine + placebo. Median overall survival means that half the people taking Tykysa lived longer than 21.9 months the other half lived less than 21.9 months.

The addition of Tukysa reduced the risk of death (overall survival) by a significant 34% compared to trastuzumab and capecitabine + placebo.

The median duration of response was 8.3 months (ranging from 6.2 to 9.7 months) for the Tukysa group and 6.3 months (ranging from 5.8 to 9.8 months) for those who received trastuzumab and capecitabine + placebo.

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When was Tukysa approved by the FDA?

In April 2020, the FDA approved Tukysa (tucatinib), an oral HER2 tyrosine kinase inhibitor to be used in combination with trastuzumab and capecitabine for adults with advanced forms of HER2 positive breast cancer who have received one or more prior anti-HER2-based regimens in the metastatic setting. The patient's breast cancer is either unresectable (cannot be surgically removed) or metastatic (cancer has spread to other parts of the body). This new approval also included patients with breast cancer that had spread to the brain.

Tukysa is manufactured by Seattle Genetics.

What side effects can I expect to see?

Tukysa can be associated with many different side effects. You may not experience all of these adverse reactions.

In studies, common side effects occurring in at least 20% of patients included:

• diarrhea
• hand-foot syndrome (redness, swelling, pain or blisters on the palms of the hands or soles of the feet)
• nausea
• fatigue
• liver toxicity
• vomiting
• stomatitis (mouth sores, redness)
• decreased appetite
• abdominal (stomach area) pain
• headache
• anemia (low levels of red blood cells)
• rash

Serious adverse reactions occurred in 26% of patients who received Tukysa and included diarrhea (4%), vomiting (2.5%), nausea, abdominal (stomach area) pain, and seizures (2% each).

This is not all the information you need to know about Tukysa (tucatinib) for safe and effective use and does not take the place of talking to your doctor about your treatment. Review the full product information here, and discuss this information and any questions you have with your doctor or other health care provider.