Investigational ErbB-2 tyrosine kinase inhibitors for the treatment of breast cancer

Introduction: ErbB2 overexpression and/or gene amplification is present in 20% of all breast cancers and characterizes an aggressive form of this disease. Despite the availability of several active drugs that have yielded substantial survival improvements, most patients with ErbB2-positive metastatic disease will develop tumor progression, either because of primary or acquired resistance. Therefore, research has focused on drugs that can more efficiently interfere with ErbB2 and with other members of the epidermal growth factor receptor family. Areas covered: This review focuses on those investigational drugs that inhibit ErbB2 tyrosine kinase activity (TKIs) for treating breast cancer. Expert opinion: ErbB-targeting TKIs show encouraging activity in patients with ErbB-positive tumors that are resistant to conventional ErbB-therapies (mostly trastuzumab), confirming pre-clinical observations. Efficient interference with the ErbB-network signaling implies also a potential use in ErbB2-normal tumors, where the phenotype is sustained by ErbB-aberrant signaling. Finally, early data suggests that ErbB-targeting TKIs could be active in treating patients with activating ErbB2 mutations. Ongoing and future research efforts should elucidate what is, according to the peculiarities of these compounds, their positioning in the treatment of women with breast cancer.