Neoadjuvant With Trastuzumab, Pyrotinib Plus Palbociclib and Fulvestrant in HER2-positive, ER-positive Breast Cancer

ER+HER2+ breast cancer have low response to single endocrine therapy, however the efficacy was improved when treated with endocrine therapy combined with anti-HER2 target therapy. Palbociclib, to be a CDK4/6 inhibitor, has synergistic with tamoxifen and trastuzumab in ER+/HER2+ cells. In China, there is nearly 40000 new patients with ER+/HER2+ breast cancer every year. The encouraging results in NA-PHER2 study suggested the triple targeting of ER, HER2, and RB1 could be an effective chemotherapy-free treatment strategy in neoadjuvant therapy. However, pertuzumab is very expensive. The investigators plan to replace pertuzumab with pyrotinib. Pyrotinib, a new irreversible pan-Her inhibitor in China pharmaceutical company. The objective is to evaluate the efficacy and safety of Neoadjuvant treatment with trastuzumab and pyrotinib plus palbociclib and fulvestrant (TPPF) in this target population. 37 patients will enter the single-arm treatment group. The participants will receive an association of drugs (trastuzumab, pyrotinib, palbociclib plus Fulvestrant, TPPF) as neoadjuvant therapy. Surgery will be performed not earlier than 14 days and not later than 28 days after the last dose of any of the drugs in the combination. The primary endpoint is the rate of pathological complete response (pCR) defined as ypT0-ypTis ypN0 at surgery. The secondary endpoint include the change in Ki67 expression from baseline and at C2D15 of treatment and at surgery, objective response rate and safety.