HER2 Expression in Peritoneal Dissemination of High-Grade Serous Ovarian Carcinoma: A Comparative Study of Immunohistochemical Reactivity Using Four HER2 Antibodies

Abstract

Most high-grade serous ovarian carcinomas (HGSOCs) involving the peritoneum are aggressive. Epidermal growth factor receptor 2 (HER2) is aberrantly activated in a variety of solid cancers. The HER2 status of a tumor is based on cytoplasmic membrane staining of an intracellular domain (ICD)-specific HER2 antibody. We compared four anti-HER2 antibodies in an immunohistochemical study of HGSOC with peritoneal dissemination. HER2 expression was assessed in peritoneal disseminated HGSOC specimens from 38 patients by immunohistochemistry using four different anti-HER2 antibodies (an ICD antibody (clone A0485), an extracellular domain (ECD) antibody (clone SP3), and two antibodies recognizing HER2 phosphorylated at tyrosine 877 or 1248 (pHER2Y877 and pHER2Y1248)). HER2 gene amplification was accessed by chromogenic in situ hybridization (CISH). The antibodies showed HER2 positivity as follows: 31.6% of cases (12/38) with A0485, 26.3% (10/38) with SP3, 7.9% (3/38) with pHER2Y877, and 21.1% (8/38) with pHER2Y1248. Fifteen out of thirty-eight (39.5%) cases were positive for at least one of the four HER2 antibodies. HER2 gene amplification was detected in 3/19 cases. All four HER2 antibodies could be used for patient selection for anti-HER2 therapies. These findings raise the possibility of anti-HER2 therapeutic strategies for HGSOC with peritoneal dissemination.

Increased CD16a (FcγRIIIA) Expression in The Tumor Microenvironment of Atypical Neurofibromatous Neoplasms of Uncertain Biologic Potential May Be Associated with Progression from Neurofibromas to Atypical Neurofibromas

“…The primary antibodies used in this experiment were a rabbit monoclonal anti-human CD16a antibody (clone SP175, 1:100, ab183354; Abcam, Cambridge, UK), a mouse monoclonal anti-human CD16b antibody (clone 07, 1:100, GTX0207; GeneTex, Irvine, CA, USA), a mouse monoclonal anti-human Galectin-3 antibody (clone 9C4, ready to use, Cat#760-4256; Cell Marque, Rocklin, CA, USA), a mouse monoclonal anti-human CD68 antibody (clone PG-M1, 1:100, M0876; Dako, Glostrup, Denmark), a rabbit polyclonal anti-human TREM2 antibody (1:100, Catalog # PA5-87933; Invitrogen, Waltham, MA, USA), mouse monoclonal S-100 antibody (clone 4C4.9, ready to use, Cat# 7990-2914; Ventana, Tucson, AZ, USA), and a rabbit monoclonal anti-human SOX10 antibody (clone SP267, ready to use, Cat# 760-4968; Cell Marque, Rocklin, CA, USA). Dual immunohistochemical staining was performed using a Dako Omnis automated staining instrument with the Envision FLEX HRP MAGENTA and DAB IHC Detection Kit (Dako, Glostrup, Denmark) [11].…”