ERBB2 and breast carcinoma: However, pCR is uncommon after neoadjuvant systemic therapy for HR-positive/HER2-negative disease—occurring in only about 10% or less of this patient population.6 Thus, downstaging to allow for BCS or deem matted axillary nodes operable may be more attainable endpoints after neoadjuvant treatment of HR-positive/HER2-negative breast cancers.