The role of neratinib in HER2-driven breast cancer.

Up to 25% of patients with early-stage HER2+ breast cancer relapse despite adjuvant trastuzumab-based regimens and virtually all patients with metastatic disease eventually die from resistance to existing treatment options. In addition, recent studies indicate that activating HER2 mutations without gene amplification could drive tumor growth in a subset of HER2-negative breast cancer that is not currently eligible for HER2-targeted agents. Neratinib is an irreversible HER kinase inhibitor with activity as extended adjuvant therapy following standard trastuzumab-based adjuvant treatment in a Phase III trial. Phase II trials of neratinib demonstrate promising activity in combination with cytotoxic agents in trastuzumab resistant metastatic HER2+ breast cancer, and either as monotherapy or in combination with fulvestrant for HER2-mutated breast cancers. We anticipate a potential role for neratinib in the therapy of these patient populations.