[Lani]

1: Arch Pathol Lab Med. 2008 Oct;132(10):1635-47.

Comparison of quantitative immunofluorescence with conventional methods for HER2/neu testing with respect to response to trastuzumab therapy in metastatic breast cancer.

Giltnane JM, Molinaro A, Cheng H, Robinson A, Turbin D, Gelmon K, Huntsman D, Rimm DL.
Departments of Pathology, Yale University School of Medicine, New Haven, Connecticut 06520-8023 , USA.
CONTEXT: Selection for trastuzumab therapy depends on a companion diagnostic assessment of HER2 by either immunohistochemistry (IHC) for protein overexpression or fluorescence in situ hybridization (FISH) to detect gene amplification. Although many studies have compared IHC to FISH, few have compared the tests to the true gold standard, tumor response. OBJECTIVE: To compare HER2 testing by FISH and IHC along with a third immunofluorescence-based assay (automated quantitative analysis-tissue microarray [AQUA-TMA]) and to assess the value of each test for prediction of response to trastuzumab. DESIGN: Immunohistochemistry and FISH assays were done on both whole slides (IHC-WS and FISH-WS) and on TMAs (IHC-TMA and FISH-TMA). AQUA was only done on TMAs (AQUA-TMA). Response was assessed according to modified Response Evaluation Criteria in Solid Tumors. RESULTS: AQUA-TMA scores showed a significant linear relationship to both the FISH signal ratio and IHC scores on whole sections and TMAs. Assay assessment by outcome showed no association between response and FISH-WS ratio (P = .96), FISH-TMA (P = .55), IHC-WS (P = .75), or IHC-TMA (P = .06), but a significant relationship between AQUA score and categoric response was observed (P = .01). Assessed as a function of outcome using models of logistic regression, both AQUA-TMA and IHC-TMA were equally significant (P = .01). FISH-WS was the most sensitive assay, with a significantly higher true-positive fraction than all other tests except AQUA-TMA, although it was the least specific. IHC-TMA was the most specific assay. The lowest misclassification rate was achieved using AQUA-TMA (0.30). CONCLUSIONS: Both AQUA-TMA and IHC-TMA were substantially more predictive than the FISH or IHC-WS tests. Although these results are derived from a small retrospective series, they suggest that accurate measurement of protein expression and unbiased selection of tissue for measurement may be key factors in prediction of response.

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Delineation of HER2 Gene Status in Breast Carcinoma by Silver in Situ Hybridization is Reproducible among Laboratories and Pathologists.

Carbone A, Botti G, Gloghini A, Simone G, Truini M, Curcio MP, Gasparini P, Mangia A, Perin T, Salvi S, Testi A, Verderio P.
From the Department of Pathology,* National Cancer Institute of Milan, Milan, Italy; Department of Pathology, National Cancer Institute "G. Pascale" of Naples, Naples, Italy; Diagnostic Immunohistochemistry and Molecular Pathology, Division of Pathology, Centro di Riferimento Oncologico, Aviano, Italy; Department of Pathology, Ospedale Oncologico, Bari, Italy; Department of Diagnostic Technologies, National Cancer Institute of Genoa, Genoa, Italy; and Medical Statistics and Biometry,** National Cancer Institute of Milan, Milan, Italy.
An automated enzyme metallographic silver in situ hybridization method (SISH) has been reported to successfully determine human epidermal growth factor receptor 2 (HER2) gene amplification. We evaluated the staining and interpretative reproducibility of the HER2 SISH assay at five laboratories and compared SISH results with other in situ hybridization (ISH) methods. The HER2 gene status of 89 breast carcinomas was analyzed in parallel using manual dual-color fluorescence ISH, manual chromogenic ISH, and bright-field automated SISH. A total of 1098 SISH-stained slides were evaluated. For comparison, all specimens were stained by 4B5 immunohistochemistry for HER2 protein expression. Interpretation was performed by pathologists at five different laboratories using the algorithms provided by the manufacturers and the guidelines of American Society of Clinical Oncology/College of American Pathologists. Staining and interpretative reproducibility were measured through the computation of weighted kappa statistics. Following the optimization of SISH staining, 1077/1098 (98%) of slides were evaluable. Excellent reproducibility and efficacy of HER2 SISH staining, and interobserver interpretation (Kw = 0.91), were observed among five sites. For the 89 invasive breast cancer cases, the overall rate of concordance between consensus 4B5 and consensus SISH, fluorescence ISH, and chromogenic ISH was 96.6% (86/89), 97.8% (87/89), and 96.6% (86/89), respectively. Overall concordance between positive and negative SISH and fluorescence ISH results, as well as between individual and consensus positive and negative SISH results, was excellent (P < 0.001).
PMID: 18832456 [PubMed - as supplied by publisher