EA1181 (CompassHER2-pCR): Preoperative THP and postoperative HP in patients who achieve a pathologic complete response Part 1 Component of:The CompassHER2 Trials (COMprehensive use of Pathologic response Assessment to optimize therapy in HER2-positive breast cancer).
Primary Objective To determine if 3-year recurrence-free survival (RFS) is greater than 92% among clinical stages II or IIIa patients with HER2-positive breast cancer who achieve pCR (ypT0/is ypN0) after preoperative therapy with 12 weeks of a taxane, trastuzumab (or FDA approved biosimilar) and pertuzumab (THP x 12). Post-operatively, patients will receive standard of care adjuvant locoregional therapy, plus completion of 12 months of HER2-targeted therapy (and standard adjuvant endocrine therapy as appropriate).
Secondary Clinical Objectives To determine 3-year IDFS (invasive disease-free survival), DDFS (distant disease-free survival), DRFS (distant relapse-free survival), RFI (recurrence-free interval), OS (overall survival) and Breast Cancer-Specific Survival in patients who achieve pCR (and by pretreatment clinical stage).
To determine 3-year EFS (event-free survival) in all patients from time of study registration.
To evaluate safety and tolerability for all patients during the pre-operative phase and for patients who attain pCR and de-escalate therapy (Arm A) until the completion of post- surgery protocol assigned therapy (i.e. until the end of HP therapy).