Key clinical point: In patients with advanced human epidermal growth factor receptor 2-positive (HER2+ or ERBB2+) breast cancer (BC) treated with trastuzumab emtansine, the pre-established levels of ERBB2 mRNA expression according to the HER2DX standardized assay served as an important prognostic biomarker in predicting survival outcomes.
Major finding: High, medium, and low levels of ERBB2 mRNA expression were associated with overall response rates of 56%, 29%, and 0%, respectively, with high ERBB2 mRNA expression being associated with both better progression-free survival (P < .001) and overall survival (P = .007) outcomes.
Study details: Findings are from a study including 87 patients with HER2+ advanced BC who received treatment with trastuzumab emtansine.
Disclosures: This study was funded by Hospital Clinic, Dipartimento di Scienze Chirurgiche, Oncologiche e Gastroenterologiche, University of Padova, Italy, and other sources. The authors declared serving as consultants; receiving advisory, lecture, or consulting fees; or having other ties with several sources.
Source: Brasó-Maristany F et al. HER2DX ERBB2 mRNA expression in advanced HER2-positive breast cancer treated with T-DM1. J Natl Cancer Inst. 2022 (Dec 28). Doi: 10.1093/jnci/djac227