SAN ANTONIO – Phosphor Integrated Dot (PID) fluorescent nanoparticles represent a novel strategy for quantifying HER2 protein expression in breast cancer, according to a study presented at the 2016 San Antonio Breast Cancer Symposium (SABCS).1
HER2 plays a key role in the regulation of normal cell growth and differentiation, but overexpression of this protein impacts outcome and prognosis in approximately one-fifth of patients with invasive breast cancers. Targeting HER2 overexpression has substantially improved outcomes for these patients, with testing of tumor samples to assess the HER2 status of a patient’s breast cancer being required; however, these tests have limitations.
“Clinical assays to assess the HER2 status in patients being considered for targeted therapy include immunohistochemistry (IHC), which detects protein over-expression, or fluorescence in situ hybridization (FISH), which detects gene amplification,” explained David G. Hicks, MD, director of Surgical Pathology at University of Rochester Medical Center in Rochester, New York. “Given that the target of the currently approved drugs is the receptor protein, novel detections systems that could more accurately and quantitatively detect HER2 protein in clinical samples over a broad dynamic range would be advantageous and may be clinically helpful.”
Therefore, researchers in Japan developed a novel detection technology using streptavidin-coated PID fluorescent nanoparticles that pathologists can use to visualize and quantify protein in clinical samples using computer assisted image analysis.
In this study, investigators used PID fluorescent nanoparticles to analyze HER2 protein expression in breast cancer cell lines and tumor samples and compared the results to those with HER2 IHC and HER2 FISH analysis.
Using these methods on 120 breast cancer samples, researchers found that PID nanoparticles better quantified the level of HER2 expression compared with HER2 IHC membrane intensity measure by Aperio image analysis.
“PID nanoparticles demonstrate great potential for the quantitative measurement of protein of clinical interest in routine clinical samples with morphologic confirmation of the tissue being studied,” said Dr Hicks. “Further studies looking for PID-score thresholds for HER2 gene amplification and correlations with clinical outcome data are warranted and ongoing.”
1. Hicks DG, Goda H, Zhai H, et al. HER2 expression in clinical breast cancer samples: A novel detection methodology for HER2 protein quantitation using fluorescent nanoparticles. Poster presented at: 2016 San Antonio Breast Cancer Symposium; December 6-10, 2016; San Antonio, TX.