ERBB2 and breast cancer: In the phase II eribulin–HP (trastuzumab–pertuzumab) trial (ClinicalTrials.gov identifier NCT01912963; n = 32), patients with metastatic, unresectable, locally advanced, or locally recurrent HER2-positive breast cancer, after the run-in period, the study expanded to two cohorts: Cohort A (n = 19) included patients who had no prior pertuzumab exposure, while Cohort B (n = 6) included patients who had received pertuzumab.