TRastuzumab in HER2-negative Early Breast Cancer as Adjuvant Treatment for Circulating Tumor Cells (CTC) ("TREAT CTC" Trial)

This is a randomized phase II trial for patients with HER2 negative primary BC who after completing (neo) adjuvant chemotherapy and surgery have detectable CTC(s) in peripheral blood (see eligibility criteria for details). Eligible patients will be randomized in 1:1 ratio to either the trastuzumab arm or the observation arm. Patients randomized to the trastuzumab arm will receive a total of 6 intravenous (IV) administrations every 3 weeks (loading dose 8 mg/kg IV and 5 cycles at 6 mg/kg every 3 weeks). Patients randomized to observation arm shall be observed for 18 weeks. Left ventricular ejection fraction (LVEF) assessment (MUGA and/or ECHO) will be done at baseline for all patients to be randomized. The next LVEF assessments of weeks 9 and week 18 will be done only in patients randomized to trastuzumab arm. Patient registered but with CTC negative result will not be followed-up.