HER2-positive breast cancer

A recent study reports promising results for combination tucatinib, trastuzumab, and capecitabine treatment for HER2-positive metastatic breast cancer.

HER2 positive breast cancer tends to be more aggressive than other types of breast cancer.  Tucatinib is an oral tyrosine kinase inhibitor that is highly selective for a specific part of the HER2 protein.

In a study published in the New England Journal of Medicine, researchers attempted to see how tucatinib, in combination with trastuzumab and capecitabine, enhances progression-free survival in HER2-positive metastatic breast cancer patients.  They compared the tucatinib combination group with a placebo group in a randomized, double-blind trial.  Over 600 patients were randomly selected in a 2:1 ratio and either given 300mg of tucatinib twice a day or a placebo.  In the tucatinib combination group, there were 410 patients and 202 patients in the placebo group.  A CT scan or MRI was performed every six weeks for 24 weeks.  Laboratory tests were performed every three weeks and disease response and progression were evaluated.

The risk of disease progression or death was 46% lower in the tucatinib combination group than the placebo group

After one year, the progression-free survival was 33.1% in the group that received tucatinib, trastuzumab, and capecitabine.  For the placebo group, it was 12.3%  The median length of progression-free survival was 7.8 months in the tucatinib combination group and 5.6 months in the placebo group.  The researchers also found that the risk of disease progression or death was 46% lower in the group that received tucatinib, trastuzumab, and capecitabine than in the placebo group.  At two years overall survival was 44.9% in the tucatinib combination group and 26.6% in the placebo group.  The median duration of survival was 21.9 months for the tucatinib combination group and 17.4 months in the placebo group.  The risk of death was 34% lower in the tucatinib combination group than in the placebo group.

The most common adverse effects in the tucatinib combination group were diarrhea, nausea, fatigue, and vomiting, in addition to increased levels of alanine aminotransferase and aspartate aminotransferase.  These adverse events are the reason 5.7% of the patients discontinued taking tucatinib while 3% of patients discontinued taking placebo.  Serum creatinine levels were 13.9% in the tucatinib combination group and 1.5% in the placebo group.

The results of the study suggest that tucatinib is a safe, easy to take oral drug for HER2 positive breast cancer, which is demonstrating positive results.

Written by Katrina F. Zafer, BSc

References

  1. Murthy, R. K., Loi, S., Okines, A., Paplomata, E. (2019). Tucatinib, Trastuzumab, and Capecitabine for HER2-Positive Metastatic Breast Cancer. The New England Journal of Medicine.  https://www.nejm.org/doi/full/10.1056/NEJMoa1914609
  2. Mayo Clinic – https://www.mayoclinic.org/breast-cancer/expert-answers/faq-20058066

Image by marijana1 from Pixabay

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