On April 17, 2020, the FDA approved Tukysa (tucatinib; from Seattle Genetics), a kinase inhibitor, for use with chemotherapy (trastuzumab and capecitabine) for the treatment of adults with unresectable (cannot be removed by surgery) advanced or metastatic (spreading) HER2-positive breast cancer, after 1 or more previous treatments. Tukysa blocks the kinase enzyme, thereby blocking the growth of cancer cells.
“We recognize that patients with cancer constitute a vulnerable population at risk of contracting the coronavirus disease,” said Richard Pazdur, MD, Director of the FDA’s Oncology Center of Excellence. “In this critical time, we remain steadfast in our commitment to patients with cancer.”
Dr. Pazdur added, “This approval represents an additional targeted treatment option for patients with HER2-positive breast cancer. The clinical trial supporting this approval enrolled and specifically studied patients with active brain metastases…which also demonstrated benefit in this subgroup.” About 20% of patients with breast cancer have the HER2 biomarker, which promotes the growth of cancer cells. In more than 25% of women with metastatic HER2-positive breast cancer, the cancer spreads to the brain.
The clinical trial that was the basis for the FDA approval of Tukysa included 612 patients with HER2-positive unresectable or metastatic breast cancer, and almost half (48%) of them had brain metastases at the start of the study. The main goal of the study was to evaluate the effectiveness of Tukysa in extending overall survival or the time that the cancer does not progress.
In patients who received the combination of Tukysa plus chemotherapy, the average time without disease progression was 7.8 months compared with 5.6 months in patients who received placebo plus chemotherapy.
The average overall survival in patients who received Tukysa plus chemotherapy was 21.9 months versus 17.4 months in those who received placebo plus chemotherapy.
Among patients who had brain metastases at the start of the study, the time without tumor progression was 7.6 months in those who received Tukysa plus chemotherapy versus 5.4 months in patients who received placebo plus chemotherapy.
The common side effects seen with Tukysa were diarrhea, burning or tingling in the hands and feet, nausea, fatigue, liver damage, vomiting, mouth inflammation, decreased appetite, abdominal pain, headache, anemia, and rash. Tukysa can also cause serious side effects, including severe diarrhea that leads to dehydration and severe kidney damage that can lead to death.