Trial of Retifanlimab With Trastuzumab and Pertuzumab Combination in HER2-Addicted Breast Cancer

The goal of this Clinical Trial is to find out how well 3 medicines (retifanlimab, trastuzumab and pertuzumab) work at treating HER2-positive breast cancer in Male and female patients, 18 or older. The main question aims to determine the pathologic response rate \[residual cancer burden (RCB)- 0\] in the breast and lymph nodes after 6 cycles of retifanlimab, trastuzumab and pertuzumab in patients with HER2-addicted breast cancer. Participants will will have at least 6 cycles of the study drug, assuming the participant is responding to and tolerating the treatment well. Every cycle will last about 21 days.