A study has found that treating newly diagnosed HER2-positive, metastatic breast cancer with a combination of a taxane chemotherapy medicine and Herceptin (chemical name: trastuzumab) offers more benefits than Tykerb (chemical name: lapatinib) and a taxane as a first treatment.
The study was published online on March 16, 2015 by the Journal of Clinical Oncology. Read the abstract of “Lapatinib or Trastuzumab Plus Taxane Therapy for Human Epidermal Growth Factor Receptor 2-Positive Advanced Breast Cancer: Final Results of NCIC CTG MA.31.”
HER2-positive cancers have too many copies of the HER2 gene, which make too much of the HER2 protein. The HER2 protein sits on the surface of cancer cells and receives signals that encourage the cancer to grow and spread. About one out of every four breast cancers is HER2-positive.
Herceptin works by attaching to the HER2 protein and blocking it from receiving growth signals. Herceptin, which is given intravenously, is approved by the U.S. Food and Drug Administration (FDA) to:
- treat advanced-stage HER2-positive breast cancers
- lower the risk of recurrence of early-stage HER2-positive breast cancers with a high risk of recurrence
A newer form of Herceptin, Herceptin Hylecta (chemical name: trastuzumab and hyaluronidase-oysk), can be given as an injection.
Like Herceptin, Tykerb works against cancers that are HER2-positive. Tykerb works by blocking the HER2 protein’s ability inside the cell to make HER2-positive breast cancers grow. Tykerb is approved by the FDA to:
- be given in combination with Xeloda (chemical name: capecitabine), a type of chemotherapy, to treat HER2-positive, metastatic breast cancer that has stopped responding to anthracyclines, taxanes, and Herceptin
- be given in combination with Femara (chemical name: letrozole), a type of hormonal therapy, to treat postmenopausal women diagnosed with hormone-receptor-positive, HER2-positive, metastatic breast cancer
Taxol (chemical name: paclitaxel) and Taxotere (docetaxel) were the two taxanes used in this study. Taxanes work by interfering with the ability of cancer cells to divide.
Taxol, Taxotere, and Herceptin are given intravenously. Tykerb is a pill taken by mouth.
In this study, called the MA.31 trial, researchers wanted to know which targeted therapy worked better with chemotherapy as a first treatment for metastatic HER2-positive breast cancer: Herceptin or Tykerb.
The researchers randomly assigned 537 women newly diagnosed with metastatic HER-positive breast cancer to one of two treatments:
- 24 weeks of Herceptin plus Taxol or Taxotere; after the 24 weeks of treatment was completed, the women received Herceptin alone until the cancer grew
- 24 weeks of Tykerb plus Taxol or Taxotere; after the 24 weeks of treatment was completed, the women received Tykerb alone until the cancer grew
The women in the study were from 21 countries and were followed for nearly 2 years. The women’s doctors made the decision about which chemotherapy medicine the women got.
The researchers found that progression-free survival was better in women treated with Herceptin and chemotherapy compared to women treated with Tykerb and chemotherapy. Progression-free survival is how long the women lived without the cancer growing.
Progression-free survival was:
- 11.3 months for women treated with Herceptin and chemotherapy
- 9.0 months for women treated with Tykerb and chemotherapy
This difference in progression-free survival was statistically significant, which means that it was likely due to the difference in medicines and not just because of chance.
Herceptin, Tykerb, and Taxol/Taxotere all may cause side effects.
The most common side effects of Tykerb are diarrhea, redness and tingling in the hands and feet, and a rash.
The most common side effects of Taxol/Taxotere are a low white blood cell count, allergic reactions, hair loss, numbness in the fingers and toes (neuropathy), diarrhea, vomiting, and mouth sores.
The most common side effects of Herceptin are high blood pressure, joint and back pain, hot flashes, headache, and diarrhea. Some women getting Herceptin will have decreased heart function during treatment. In rare cases, heart failure can develop. Other studies have shown that heart problems caused by Herceptin are more likely to happen in older women, women with diabetes, and women with preexisting risk factors such as high blood pressure, high cholesterol, and obesity. Heart function can recover when Herceptin treatment stops.
In this study:
- 8% of the women who got Tykerb had a severe rash compared to 0% of the women who got Herceptin
- 19% of the women who got Tykerb had severe diarrhea compared to 1% of the women who got Herceptin
- 2.3% of the women who got Herceptin had decreased heart function compared to 0% of the women who got Tykerb
If you’re newly diagnosed with HER2-positive, metastatic breast cancer, you and your doctor will consider a number of treatment options. If you’re trying to decide between Herceptin and chemotherapy and Tykerb and chemotherapy, you may want to talk to your doctor about this study.
It’s important to remember that while there are many standard regimens to treat metastatic breast cancer, each person’s treatment plan will be unique because each cancer is unique. Besides the characteristics of the cancer, your doctor also will take into account other health issues you may have, including heart problems, high blood pressure, and diabetes. These and other conditions can affect which medicines your doctor recommends for you.
Editor’s Note: This article was updated with information about Herceptin Hylecta, which the FDA approved on Feb. 28, 2019.
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