This is a prospective, single-arm, phase II study of 32 evaluable patients treated with NEOADjuvant Aromatase inhibitor and Pertuzumab/Trastuzumab (NEOADAPT) without chemotherapy for hormone receptor positive (HR+), [i.e. Estrogen Receptor positive (ER+) and/or Progesterone Receptor positive (PR+)] HER2+ localized, non-metastatic stage I - IIb breast cancer.