Abstract
Over-expression of the HER2/neu receptor occurs in 20 to 30 percent of breast tumors and is linked to poorer prognosis. The HER2/neu expression status determines whether or not patient will receive trastuzumab-based treatment. In clinical practice, over-expression of HER2/neu is routinely identified using Immunohistochemistry (IHC) or Fluorescence in Situ Hybridization (FISH), both of which are invasive approaches requiring tissue samples. Serum assays for the Extra Cellular Domain of HER2/neu receptor (HER2 ECD) have been reported but the use is very limited due to serum interference factors (e.g. human anti-animal immunoglobulin antibodies) that lead to false test results and inconsistency with tissue Her2 status. We have developed an ELISA based approach using an MBB buffer to eliminate false results and to obtain more accurate assessment of HER2 ECD levels. Using this refined assay we retroactively measured HER2/neu levels from breast cancer patients and controls. Abnormal HER2 ECD levels were detected in about 32% of invasive breast cancer patients but not in controls or patients with benign diseases. In addition, we also showed that patients with elevated serum HER2 levels appeared to have worse survival regardless of treatments. In a small group of 12 Ductal Carcinoma in situ (DCIS) patients who received HER2/neu peptide vaccination and surgery, only one patient showed constantly rising HER2 levels after treatment and this patient had recurrence of HER2 positive tumor within 5 years. Our studies indicate that once the serum interference issue is resolved, serum HER2 ECD can have potential clinical utility to supplement the tissue based tests.
Highlights
Over-expression of the human her2/neu gene, the homologue of the oncogene neu, is one of the predominant transformation-activating mechanism and achieves the same effect as the oncogenic mutations observed in the neu oncogene [1]
One problem associated with the serum test in sandwich ELISA (Enzyme-Linked Immunosorbent Assay) is the serum interference, which ismostly caused by the Human Anti- Animal Immunoglobulin Antibody (HAIA) or more commonly known as the Human AntiMouse Antibody (HAMA) [12]
We have developed the MBB buffer [13], which was designed to prevent the weak interactions between capture/detection antibodies and HAIA but to spare the strong interaction with specific antigens
Summary
Over-expression of the human her2/neu gene, the homologue of the oncogene neu, is one of the predominant transformation-activating mechanism and achieves the same effect as the oncogenic mutations observed in the neu oncogene [1]. An association between the extent of her2/neu amplification and the presence of tumor in lymph nodes was observed [2]. One problem associated with the serum test in sandwich ELISA (Enzyme-Linked Immunosorbent Assay) is the serum interference, which ismostly caused by the Human Anti- Animal Immunoglobulin Antibody (HAIA) or more commonly known as the Human AntiMouse Antibody (HAMA) [12]. To eliminate this problem, we have developed the MBB buffer [13], which was designed to prevent the weak interactions between capture/detection antibodies and HAIA but to spare the strong interaction with specific antigens. J Mol Biomark Diagn 4: 151. doi:10.4172/2155-9929.1000151
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