title: Simultaneous targeting of estrogen receptor and HER2 in breast cancer.
abstract: Approximately 50% of HER2-positive breast cancers express estrogen receptor (ER) and these tumors are characterized by short-lived responses to hormonal agents. Preclinical models have shown that dual targeting of ER and HER2 could reverse and delay the development of drug resistance. Two studies (TAnDEM & EGF3008) have recently been published addressing the combined use of an aromatase inhibitor (AI) and an anti-HER2-targeted agent. Both studies showed that the combined approach is associated with improvement in response rate and progression-free survival compared with an AI alone with an acceptable toxicity profile. These results would indeed extend the treatment options for patients with ER/HER2-positive metastatic breast cancer. In this article, we discuss how the improved understanding of the complex cross-talk between ER and HER2 has resulted in better clinical outcomes. We analyze clinical evidence regarding the combined use of AIs and anti-HER2-targeted agents. We also touch on possible mechanisms of resistance and ways to improve research in this field.
authors.affiliation: Jules Bordet Institute, Department of Medical Oncology, Boulevard Waterloo, 121,1000 Brussels, Belgium.
authors.forename: Hatem A
authors.initials: HA
authors.lastname: Azim
authors.forename: Martine J
authors.initials: MJ
authors.lastname: Piccart
mesh_terms: D000818:Animals; D018931:Antineoplastic Agents, Hormonal / Q000008:administration & dosage / Q000378:metabolism*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism*; D016503:Drug Delivery Systems / Q000379:methods*; D019008:Drug Resistance, Neoplasm; D005260:Female; D006801:Humans; D020239:Receptor Cross-Talk / Q000187:drug effects / Q000502:physiology; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011960:Receptors, Estrogen / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D018931:Antineoplastic Agents, Hormonal; D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen