The research study procedures include screening for eligibility and study treatment including laboratory evaluations, physical exams, questionnaires, and follow up visits.~Participants will receive HER2-directed treatment for 1 year and hormonal therapy for approximately 5 years.~It is expected that about 375 people will take part in this research study.~This research study is a Phase II clinical trial. Phase II clinical trials test the safety and effectiveness of an investigational drug combination to learn whether the drug works in treating a specific disease. Investigational means that the drug combination is being studied.~The drugs trastuzumab and pertuzumab are both monoclonal antibodies, which are disease-fighting proteins made by cloned immune cells. The U.S. Food and Drug Administration (FDA) has approved trastuzumab, pertuzumab, and trastuzumab + pertuzumab subcutaneous fixed dose combination (PHESGO) as treatment for HER2 positive breast cancer. The FDA has also approved hormonal therapies as treatment for hormone receptor positive breast cancer.~.
This research study is studying a combination of HER2-directed therapies (trastuzumab and pertuzumab) and hormonal therapy as a treatment after surgery for hormone receptor positive breast cancer.~The study drugs involved in this study are:~A combination of trastuzumab and pertuzumab given as an injection under the skin (PHESGO)~Hormonal (endocrine) Treatment