Exquisite antitumour response to trastuzumab in a patient with no evidence of Ras–Raf–MAPK and PI3K–Akt pathways activation

We report on the case of a patient with a diagnosis of a HER2-overexpressing metastatic breast cancer which was refractory to a combination of a Raf kinase inhibitor and docetaxel, but highly sensitive to trastuzumab, a HER2-targeted monoclonal antibody. Interestingly, there was no evidence of Ras–Raf–MAPK or PI3K–Akt pathways activation.