Sensitivity of HER-2/neu Antibodies in Archival Tissue Samples of Invasive Breast Carcinomas

Abstract

Overexpression and amplification of the HER-2 oncogene in patients with breast cancer has correlated with early onset of metastasis, resistance to hormonal therapy and some forms of chemotherapy, and shortened survival. Therefore, evaluation of this putative prognostic or predictive factor seems critical. Because different antibodies are used for the detection of the 185-kd HER-2 oncoprotein, we studied the sensitivity of 3 frequently used antibodies. Immunohistochemistry results were correlated with gene amplification level as assessed by fluorescence in situ hybridization. Protein overexpression was found in 17.2% and 12.5% of cases using antibodies against the external (TAB250) and internal (CB11) domains of the protein, respectively, and in 38.0% of cases using a rabbit polyclonal antibody. Fluorescence in situ hybridization was successful in all 160 tumors, and amplification was found in 37 tumors (23.1%). The monoclonal antibody TAB250 had the lowest misclassification rate, 9.6% (sensitivity, 67%; specificity, 97.5%).

Determination of HER2 Gene Amplification by Chromogenic In Situ Hybridization (CISH) in Archival Breast Carcinoma

“…We do not think that 2-4 HER2 gene copies per nucleus can even be due to gene amplification. In the invasive breast cancers we studied, chromosome 17 polysomy was frequent (31%), which is similar to the results reported by others (13,24,31) and even more frequent (67%) in the invasive breast cancers with HER2 amplification.…”

“…It is relatively easy to perform and has rapid turnaround time, and relatively low cost (1,4). However, commercially available antibodies have demonstrated wide variation in sensitivity and specificity for FFPE tissue samples, and the effect of the tissue fixative and pretreatment have a substantial effect on HER2 IHC staining (1,(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21), although antigen retrieval and immunodetection system currently used have improved sensitivity of antibodies. In addition, the lack of universal scoring system and interobserver differences in interpretation of HER2 IHC result are also important issues (1,15,17,18,22,23).…”

Reliability of chromogenic in situ hybridization for detecting HER-2 gene status in breast cancer: comparison with fluorescence in situ hybridization and assessment of interobserver reproducibility

“…The cutoff number for determining oncogene amplification by CISH was empirically defined as six copies per cell based on the observation that most cases with polysomy of chromosome 17 fall into three to five signals per nucleus. 12,17 However, aneusomy of chromosome 17 is common in breast cancer 12,18,[21][22][23][24] and polysomy with 45 copies of chromosome 17 per nucleus is not rare. 17 These cases would be scored erroneously as low amplification while there is no actual amplification present.…”

Evaluation of the predictive value of Her-2/neu gene expression on osteosarcoma therapy in laser-microdissected paraffin-embedded tissue

“…34,35 In addition, sensitivity and specificity of immunohistochemical Her-2/neu detection depends crucially on the antibody used. 24,36 The goal of this study was the modification of current protocols to optimize RNA yield, efficiency of cDNA synthesis and PCR sensitivity according to the requirements of decalcified osteosarcoma tissue in order to analyze Her-2/neu gene expression. The isolation of sufficient DNA-free RNA was achieved by extensive proteinase K digestion of the samples in combination with a DNase treatment during RNA extraction.…”