Triple-negative Breast Cancers May Have Unique Therapeutic Target
• Some patients with triple-negative breast cancer overexpressed IGF-1R.
• Expression of IGF-1R is associated with longer survival.
• Data provides potential target for new drugs.
DENVER — Patients with triple-negative breast cancer, one of the hardest subtypes to treat, may have a unique biomarker that would enable them to receive more targeted therapy, according to data presented at the Fourth AACR International Conference on Molecular Diagnostics in Cancer Therapeutic Development.
Triple-negative breast cancers are breast cancers that have tested negative for estrogen receptors, progesterone receptors and HER2. Because of this biology, these cancers do not respond to endocrine therapies or trastuzumab.
“In other subsets of breast cancer, you can use these drugs with some success. However, triple-negative breast cancers currently lack therapeutic targets and are managed with conventional chemotherapy,” said Agnieszka K. Witkiewicz, M.D., an associate professor of pathology at Thomas Jefferson University Hospital in Philadelphia.
Witkiewicz examined 97 patients with triple-negative breast cancer, of whom 73 were white and 24 were African-American. Insulin-like growth factor 1 receptor (IGF-1R) protein expression was evaluated by immunohistochemistry and IGF-1R gene copy number was assessed by chromogenic in situ hybridization.
They found that IGF-1R was overexpressed in 25 percent of the cases. The IGF-1R protein overexpression correlated with gene amplification.
Moreover, low expression of the receptor was associated with greater risk of lymph node metastasis and high expression showed borderline association with lower tumor size. Among patients younger than 55 years, IGF-1R overexpression was associated with longer survival.
Since IGF-1R blockade has been a successful therapeutic approach in sarcomas, Witkiewicz suggested that there may be potential to target this receptor in this breast cancer subtype as well.
“For now, we know that it is there and we know it is a marker of better prognosis,” said Witkiewicz. “The next step is to learn if triple-negative breast cancer patients benefit from targeting IGF-1R.
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The mission of the American Association for Cancer Research is to prevent and cure cancer. Founded in 1907, the AACR is the world’s oldest and largest professional organization dedicated to advancing cancer research. The membership includes 32,000 basic, translational and clinical researchers; health care professionals; and cancer survivors and advocates in the United States and more than 90 other countries. The AACR marshals the full spectrum of expertise from the cancer community to accelerate progress in the prevention, diagnosis and treatment of cancer through high-quality scientific and educational programs. It funds innovative, meritorious research grants, research fellowships and career development awards. The AACR Annual Meeting attracts more than 18,000 participants who share the latest discoveries and developments in the field. Special Conferences throughout the year present novel data across a wide variety of topics in cancer research, treatment and patient care. The AACR publishes six major peer-reviewed journals: Cancer Research; Clinical Cancer Research; Molecular Cancer Therapeutics; Molecular Cancer Research; Cancer Epidemiology, Biomarkers & Prevention; and Cancer Prevention Research. The AACR also publishes CR, a magazine for cancer survivors and their families, patient advocates, physicians and scientists, providing a forum for sharing essential, evidence-based information and perspectives on progress in cancer research, survivorship and advocacy.
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