[181] A New Rabbit Monoclonal E-Cadherin Antibody Shows Higher Sensitivity Than Mouse Monoclonal E-Cadherin [HECD-1] Antibody in Infiltrating Ductal Cell Carcinomas

Laura Hoang, Ryan Bremer, Ping Tang, David G Hicks, Thomas Haas, David Tacha. Biocare Medical, LLC, Concord, CA; University of Rochester Medical Center, Rochester, NY; Mercy Health System, Janesville, WI

Background: The loss of E-cadherin expression has been observed in breast cancer and is associated with a poor prognosis. Immunohistochemical studies have shown E-cadherin to be expressed in breast ductal carcinoma with loss of expression in lobular carcinoma. As a result, mouse monoclonal anti-E-cadherin [HECD-1] has been used by pathologists to differentiate between ductal and lobular carcinomas of the breast, with currently published sensitivity and specificity of approximately 90%. Rabbit monoclonal antibodies may combine the best properties of both mouse monoclonal antibodies and rabbit antisera. This study compared the staining sensitivity of a new rabbit monoclonal E-cadherin vs. mouse monoclonal clone HECD-1. The two E-cadherin antibodies were further applied in the discrimination of ductal from lobular carcinomas, in combination with a p120 catenin antibody.
Design: Rabbit monoclonal E-cadherin and HECD-1 were tittered and optimized for immunohistochemical staining in infiltrating ductal breast cancers using an HRP-polymer detection system and visualization with DAB. 31 cases of infiltrating ductal cell carcinoma and 29 cases of lobular carcinoma were evaluated. A semi-quantitative scoring system for intensity of membrane staining with E-cadherin was applied: 0=negative, 1=weak to medium, 2=medium to strong, 3=strong and intensely strong.
Results: The rabbit monoclonal anti-E-cadherin antibody showed much sharper staining and increased sensitivity (30/31, 97%) compared to mouse monoclonal HECD-1 (27/31, 87%) [Table 1]. No staining was observed in any of the lobular carcinomas evaluated. All lobular carcinomas were confirmed by the absence of E-cadherin and the diffuse cytoplasmic expression of p120 catenin.

Table 1: Rabbit Monoclonal E-cadherin and Mouse Monoclonal Clone HECD-1 in breast ductal carcinoma
AntibodyScore 0Score 1Score 2Score 3Average scorePositive (n=31)% Positive
Rabbit E-cadherin117222.63097%
Mouse E-cadherin (HECD-1)4101521.52787%

Conclusions: The high affinity rabbit antibody against E-cadherin was more sensitive than clone HECD-1 for immunohistochemical evaluation of ductal carcinomas, and was negative in all lobular carcinomas; thus making it a reliable alternative for the distinction of infiltrating ductal cell vs. lobular carcinomas.
Category: Breast

Wednesday, March 6, 2013 1:00 PM

Poster Session VI # 5, Wednesday Afternoon


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