Automated Assay for HER-2/neu in Serum

Abstract

Background: The extracellular domain of the HER-2/neu oncogene product is increased in sera of some patients with epithelial cancers. Our aim was to develop an automated serum assay for the extracellular domain of the HER-2/neu protein. Methods: We used a monoclonal antibody labeled with fluorescein for capture and a monoclonal Fab′ fragment labeled with alkaline phosphatase for detection. Separation of bound and free detection conjugate was performed with magnetizable particles coated with monoclonal antibody to fluorescein. Alkaline phosphatase activity was measured kinetically at 405 or 450 nm. Results: The assay was linear from 0.1 to 250 μg/L. No hook effect was evident up to 10 000 μg/L. Within-run imprecision (CV) was 0.8–1.2%, and total imprecision was 1.1–1.7%. Cross-reactivity with human epidermal growth factor receptor, which has extensive homology with HER-2/neu extracellular domain, was <0.6%. Human anti-mouse antibodies, heterophilic antibodies, and rheumatoid factor did not interfere, nor did the therapeutic monoclonal antibody Herceptin®. In 51 healthy females, the mean value was 9.3 μg/L with a range of 6.4–14.0 μg/L. No reagent lot-to-lot variability was detected over four lots of reagents tested. Conclusion: The Bayer Immuno 1TM assay for HER-2/neu was precise and resistant to interferences, characteristics that are essential for longitudinal monitoring of cancer patients.

Serological and immunohistochemical HER-2/neu statuses do not correlate and lack prognostic value for ovarian cancer patients

“…In contrast to immunohistochemistry, serological HER-2/neu detection presented 23% of patients with serum concentrations exceeding the cut-off level of 15 ng/mL in the present study. The HER-2/neu Kit used in this study for serum diagnostics is tested in several studies and is accepted to be sensitive and specific, as well as to provide reproducible results (Payne et al 2000;Cook et al 2001;Carney et al 2003). HER-2/neu serum overexpression in ovarian cancer patients varies from 9% to 33% (Meden et al 1998;Cheung et al 1999;Bookman et al 2003).…”

Soluble human epidermal growth factor receptor 2 (HER2) levels in patients with HER2‐positive breast cancer receiving chemotherapy with or without trastuzumab: Results from North Central Cancer Treatment Group adjuvant trial N9831

“…Payne et al have demonstrated that trastuzumab does not interfere with this serum HER2 assay. 16 The cutoff for this assay for normal and high sHER2 levels was 15 ng/mL according to the US Food and Drug Administration-approved ADVIA Centaur HER-2/neu assay recommendation. Of the total 3505 patients enrolled in the trial, baseline samples were available for 2318 patients participating in treatment arms A (n 5 795), B (n 5 814), and C (n 5 709).…”

Pretreatment serum level of HER2/nue as a prognostic factor in metastatic prostate cancer patients about to undergo endocrine therapy

“…The Bayer Immuno 1 HER2/neu assay is a magnetic particle separation immunoassay designed for the random access automated Bayer Immuno 1 immunochemistry analyzer (Bayer Diagnostics, Tarrytown, NY, USA). 17 Briefly, the assay uses a monoclonal antibody labeled with fluorescein for capture and a monoclonal Fab′ fragment labeled with alkaline phosphatase for detection. Separation of bound and free detection conjugate was performed with magnetizable particles coated with monoclonal antibody to fluorescein.…”