An analysis of PIK3CA hotspot mutations and response to neoadjuvant therapy in breast cancer patients from four prospective clinical trials

The PI3K signaling pathway is frequently dysregulated in breast cancer (BC), and mutations in PIK3CA, are relevant for therapy resistance in HER2pos BC. Mutations in exons 9 or exon 20 may have different impact on response to neoadjuvant chemotherapy-based treatment regimens.