Discordance between IHC and ERBB2 mRNA to Determine HER2 Low Status for Breast Cancer

Novel HER2-directed antibody-drug conjugates (ADC) have demonstrated efficacy in HER2-low expressing breast cancers, which are currently defined as those with IHC scores of 1+ or 2+ with a negative ISH assay. However, current HER2 testing methods are designed to identify HER2 amplified tumors with “high” expression levels. The true definition of “HER2-low” expressing breast cancers remains controversial. Using quantitative molecular analysis of breast cancers based on RNA expression, the dynamic range of HER2 expression exceeds that detected by in situ IHC approaches.

Source: Journal of Molecular Diagnostics - May 5, 2022 Category: Pathology Authors: Keying Xu, Jane Bayani, Elizabeth Mallon, Gregory R. Pond, Tammy Piper, Annette Hasenburg, Christos J. Markopoulos, Luc Dirix, Caroline M. Seynaeve, Cornelis J.H. van de Velde, Daniel W. Rea, John MS. Bartlett Tags: Regular Article Source Type: research