Triple-Negative Breast Cancer Seems to Have Abnormal Genes That May Be Treatment Targets

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Triple-negative breast cancer is:

  • estrogen-receptor-negative
  • progesterone-receptor-negative
  • HER2-negative

The growth of triple-negative breast cancer isn’t supported by the hormones estrogen and progesterone, or by the presence of too many HER2 receptors. This means that triple-negative breast cancer doesn’t respond to hormonal therapy (such as tamoxifen or the aromatase inhibitors) or therapies that target HER2 receptors, such as Herceptin (chemical name: trastuzumab) or Tykerb (chemical name: lapatinib).

About 10-20% of breast cancers – more than one out of every 10 – are triple-negative. Triple-negative breast cancer tends to be more aggressive than other types of breast cancer.

Triple-negative breast cancer usually is treated with a combination of surgery, radiation therapy, and chemotherapy. Researchers are constantly working to find new medicines to treat triple-negative breast cancer.

A small genetic study has found that many triple-negative breast cancers have abnormal genes and many of these abnormal genes could be targeted by medicines already on the market or being developed.

The study, “Profiling of triple-negative breast cancers after neoadjuvant chemotherapy identifies targetable molecular alterations in the treatment-refractory residual disease,” was presented at the 2012 San Antonio Breast Cancer Symposium.

Many of the abnormal genes fell into five groups:

  • the P13K/mTOR pathway, which is involved in cell death and communication between cells; Afinitor (chemical name: everolimus), an mTOR inhibitor, was approved by the U.S. Food and Drug Administration in July 2012
  • DNA repair genes, such as the PARP (poly ADP-ribose polymerase) enzyme; the experimental medicines inparib and olaparib, are PARP inhibitors
  • the Ras/MAPK pathway, which is involved in cell growth, cell differentiation, and cell death
  • cell cycle genes, which are involved in cell division and duplication
  • growth factor receptors, such as EGFR (epidermal growth factor receptor); the experimental medicine Erbitux (chemical name: cetuximab) blocks the function of EGFR genes

While these results are early results, they give researchers the beginnings of a blueprint to create new targeted therapies to treat triple-negative breast cancer. Unlike traditional therapies such as chemotherapy and radiation, which can’t tell the difference between healthy cells and cancer cells, targeted therapies target specific characteristics of cancer cells, such as a protein that allows the cancer cells to grow in a very fast or abnormal way. Targeted therapies are generally less likely than chemotherapy to harm normal, healthy cells.

If you’ve been diagnosed with triple-negative breast cancer, you and your doctor may be considering a number of options, especially if the cancer has stopped responding to standard treatments. Treatment with an experimental regimen that includes a PARP inhibitor or other targeted therapy medicine may be an option if you’re willing to participate in a clinical trial. Ask your doctor if there are any clinical trials that might be a good fit for you and your unique situation. Visit the Breastcancer.org Clinical Trials pages for more information.

And stay tuned to Breastcancer.org for the latest information on new treatments for triple-negative disease.

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