The U.S. Food and Drug Administration or the FDA has finally approved the use of the drug tucatinib, also known as Tukysa in order to treat adults with advanced forms of HER2-positive breast cancer. The drug combined with chemotherapy can help those with breast cancers that can't be removed with surgery or has spread to other parts of the body, including the brain.
According to the director of the FDA's Oncology Center of Excellence, Dr. Richard Pazdur, the clinical trial supporting this approval enrolled and specifically studied patients with active brain metastases in addition to the overall population enrolled, which also demonstrated benefit in the subgroup.
The FDA granted the distribution of Tukysa to Seattle Genetics, Inc. The said drug is approved for those who have received one or more treatments in the past for their cancer.
What is HER2-positive breast cancer?
HER2-positive breast cancer makes up one-fifth of breast cancers. Having too much of a protein called human epidermal growth factor receptor 2 or HER2 promotes the growth of cancer cells in the breast. According to the CDC, more than 25% of women with metastatic HER2-positive breast cancer will develop brain metastases.
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Pazdur stated that the approval of Tukysa represents an additional targeted treatment option for patients with HER2-positive breast cancer. The FDA knows that cancer patients are considered high-risk for contracting the coronavirus disease, this inspired the FDA to expedite oncology product development. Tukysa was approved around four months before the FDA goal date.
Studying tucatinib for breast cancer
A previous study recorded 612 patients diagnosed with advanced HER2-positive metastatic breast cancer. The study was published in the New England Journal of Medicine in December 2019 and found that adding tucatinib to a chemotherapy session that consists of drugs capecitabine and trastuzumab could help improve survival for cancer patients.
The 612 patients in the study were assigned randomly to either receive tucatinib or a placebo, the patients also received chemotherapy with the drugs capecitabine and trastuzumab.
The researchers of the study found that in the first year of the patient's treatment, 33.1% of those in the tucatinib group did not see any signs of cancer progression compared with 12.3% of patients in the placebo group. The chances of survival also increased, as the group who took tucatinib for two years had a survival chance of 44.9% while those in the placebo group only had 26.6%.
However, there are side effects from taking tucatinib that need to be noted, it includes the risks of diarrhea and elevated levels of an enzyme in the body called aminotransferase. According to the FDA, health care professionals should advise patients to notify their health care provider and start antidiarrheals as clinically indicated if ever diarrhea occurs.
If the patient experiences severe diarrhea, the use of Tukysa should be reduced or discontinued. The said drug can also cause severe hepatotoxicity. Health care professionals should also monitor liver tests in patients who are taking Tukysa and it should be done every three weeks while the patient is on treatment or it should be done as clinically indicated.
The FDA also added that women who are pregnant and those who are breastfeeding should not take Tukysa because it may cause harm to their baby.
