Importance of the field: Heterodimerization of human EGF receptor (HER) 2 and HER3, a co-receptor of HER2, plays an important and dominant role in the functionality and transformation of HER-mediated pathways. Understanding the role of HER3 in oncogenesis as well as its place as a target for anticancer therapy is an ongoing area of research. Determination of biomarkers for clinical benefit from agents targeting HER3 is an essential component of translating basic science into real-world effective anticancer therapies, with the aim of ensuring the patients most likely to benefit from such treatments can be identified.
Areas covered in this review: This review focuses on the targeting of HER2 and HER3 by monoclonal antibodies and the potential for HER3 mRNA levels to predict treatment outcome in ovarian cancer.
What the reader will gain: An understanding of the value of biomarkers for clinical benefit to anticancer therapy and the current status of HER3 mRNA as a biomarker for clinical benefit of the HER2-HER3 dimerization inhibitor pertuzumab.
Take home message: HER3 mRNA levels may be a biomarker for active ligand-induced HER2-HER3 signaling, with low HER3 mRNA levels correlated with clinical benefit from the HER2-HER3 dimerization inhibitor pertuzumab.