PIK3CA alterations and benefit with neratinib after trastuzumab-based adjuvant therapy in early- stage HER2+ breast cancer: Correlative analyses of the phase III ExteNET trial

One year of neratinib treatment after trastuzumab- based adjuvant therapy significantly improves iDFS after 5 years in patients with early-stage HER2+ breast cancer. From this modest-sized exploratory cohort, it appears that PIK3CA may be a biomarker for differential sensitivity to neratinib after 1 year of trastuzumab in the adjuvant setting.These exploratory results should be validated in a larger subset.