Fujita K, Yao T. Discordance of positive immunohistochemical results among different primary HER2 antibodies used in breast cancer: A comparison between Histofine® HER2 Kit (MONO) SV2-61γ antibody and Ventana I-VIEW PATHWAY™ HER2 4B5 antibody.
REVISTA ESPANOLA DE PATOLOGIA : PUBLICACION OFICIAL DE LA SOCIEDAD ESPANOLA DE ANATOMIA PATOLOGICA Y DE LA SOCIEDAD ESPANOLA DE CITOLOGIA 2022;
55:222-229. [PMID:
36154727 DOI:
10.1016/j.patol.2022.04.002]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 03/25/2022] [Accepted: 04/01/2022] [Indexed: 06/16/2023]
Abstract
INTRODUCTION
Immunohistochemical (IHC) testing for human epidermal growth factor receptor 2 (HER2) expression status renders variable scores among different primary antibodies.
MATERIALS AND METHODS
We assessed HER2 expression status by IHC score using two types of kits, i.e., Roche Ventana I-VIEW PATHWAY™ HER2 using the 4B5 antibody that recognizes the intracellular domain (ICD) and Nichirei Biosciences Histofine® HER2 Kit (MONO) using the SV2-61γ antibody that recognizes the extracellular domain (ECD). In addition, we determined the presence or absence of the ECD in samples by Western blotting (WB) and examined its relationship with the IHC score.
RESULTS
Of 101 samples, 44 and 9 samples received a score of 2+/3+ by IHC with 4B5 and SV2-61γ, respectively. A verification by WB in samples with a discrepancy of IHC scores found that samples with the score of 2+/3+ with SV2-61γ showed a significantly higher protein intensity of p185HER2 with the ECD, whereas samples with a score of 2+/3+ with 4B5 but as 0/1+ with SV2-61γ showed a significantly higher protein intensity of p95HER2 without the ECD.
CONCLUSION
The nature of primary antibodies used for IHC and the presence or absence of the ECD in samples may contribute to different positive rates between 4B5 and SV2-61γ.
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