The insulinlike growth factor I receptor may offer a much-needed therapeutic target for triple-negative breast cancer.
High levels of IGF-IR expression appear to confer a survival benefit for a subset of patients with this type of cancer, based on the results of a small study.
“In triple-negative breast cancer patients younger than 55, high expression is associated with longer survival,” Dr. Agneiszka W. Witkiewicz said at a press briefing sponsored by the American Association for Cancer Research.
Unlike hormone receptor–positive or HER2-positive breast cancers, triple-negative breast cancer has lacked a therapeutic drug target. While triple-negative breast cancer accounts for only 15%-20% of breast cancer cases, it results in half of all breast cancer deaths, said Dr. Witkiewicz, a pathologist at Thomas Jefferson University in Philadelphia.
The researchers evaluated tissue from 99 women with triple-negative breast cancer. They stained the samples with anti-IGF-IR antibody (Ventana Medical Systems Inc.), and scored IGF-IR protein expression. Patients were stratified as high expression (a score of 3) or low expression (scores 0-2). More than a quarter of patients (29%) had high IGF-IR expression – and this was significantly correlated with negative lymph nodes. Among patients older than 55 years, there was no survival difference between those with low and high IGF-IR expression.
The study was presented in Denver at the AACR's International Conference on Molecular Diagnostics in Cancer Therapeutic Development. One of the coauthors is employed by Ventana.