The insulin-like growth factor 1 receptor may offer a much-needed therapeutic target for triple-negative breast cancer, which can be notoriously difficult to treat.
High levels of insulin-like growth factor 1 receptor (IGF1-R) expression appears 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 during a press briefing Sept. 28 sponsored by the American Association for Cancer Research (AACR).
Unlike hormone receptor–positive or HER2-positive breast cancers, triple-negative breast cancer has lacked a drug target and is managed with conventional chemotherapy. 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 and an investigator on the study.
The researchers evaluated tissue from 99 women with triple-negative breast cancer. They stained the samples with anti-IGF1R antibody (Ventana Medical Systems Inc.), and scored IGF1-R protein expression according to standardized criteria originally developed to assess HER 2 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 IGF1-R 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 IGF1-R expression.
IGF1-R belongs to the large class of tyrosine kinase receptors that appear to control proliferation and apoptosis in tumors, and may play a role in resistance to chemotherapy. Importantly, a number of drugs targeting IGF1-R are currently under investigation in clinical trials.
The study was presented in Denver as a poster at the AACR’s International Conference on Molecular Diagnostics in Cancer Therapeutic Development.
Disclosures: One of the coauthors is employed by Ventana Medical Systems, which makes an anti-IGF1-R antibody and is developing an IGF1-R probe.