ERBB2 and breast cancer: The single-arm phase III PERUSE trial (NCT01572038; planned N = 1500) is evaluating the safety of first-line pertuzumab combined with trastuzumab and a taxane of the investigator’s choice, as its primary endpoint, in patients with metastatic or locally recurrent HER2-positive breast cancer [https://clinicaltrials.gov/ct2/show/NCT01572038].