What Is It, and Why Does It Matter?
The FDA has approved Tukysa (tucatinib) to help treat adults with a specific type of advanced breast cancer. This treatment is for cancer that is HER2-positive and has spread to nearby tissue or other parts of the body. It is used as a maintenance treatment after patients have already finished initial therapy with targeted medicines and chemotherapy without their cancer getting worse.
HER2-positive breast cancer has higher levels of a protein called HER2 that helps cancer cells grow. Tukysa is a targeted medicine that blocks this protein to help slow down or stop cancer cells from growing. For maintenance care, Tukysa is taken along with two other targeted medicines, trastuzumab and pertuzumab. This offers a chemotherapy-free option to help keep the cancer under control for longer.
Why Was It Approved?
The approval was based on a clinical trial called HER2CLIMB-05, which included 654 adult patients with HER2-positive advanced breast cancer. All patients in the study had completed four to eight cycles of initial treatment using trastuzumab, pertuzumab, and chemotherapy without their cancer growing. Half of the patients received Tukysa along with trastuzumab and pertuzumab, while the other half received a placebo along with the same two medicines.
The main outcome showed that adding Tukysa helped keep the cancer from growing or spreading for a longer time. On average, patients taking the Tukysa combination lived for 24.9 months without their disease worsening, compared to 16.3 months for those taking the placebo combination. The most common side effects included diarrhea, muscle or joint pain, liver problems, nausea, tiredness, a rash, and vomiting.
What Do I Need to Know?
Tukysa is taken as a pill by mouth twice a day, about 12 hours apart, with or without food. You should swallow the tablets whole and never chew, crush, or split them. Always take Tukysa exactly as your healthcare provider tells you to and continue taking it alongside your other prescribed maintenance treatments.
Tukysa can cause serious liver problems, which can sometimes be severe or life-threatening. Your healthcare provider will order blood tests to check your liver before you start treatment and regularly while you are taking the medicine. Tell your healthcare provider right away if you notice signs of liver problems, such as yellowing of your skin or eyes, dark urine, severe fatigue, or pain on the upper right side of your stomach area.
Tukysa can also cause severe diarrhea, which can lead to dehydration or kidney problems. Contact your healthcare provider right away if you have a change in your bowel habits or severe diarrhea so they can prescribe medicines to help. Tukysa may also harm a fetus or pass into breast milk, so you should use effective birth control during treatment and for a week after your last dose and avoid breastfeeding while taking the drug.