Pyrotinib, Dalpiciclib(SHR6390) and Endocrine Therapy in Subjects With Dual-receptor Positive(ER+/HER2+) Advanced Breast Cancer

This is a single-center, single arm, open-label, run-in phase Ib / roll-over phase II study of endocrine therapy in combination with novel human epidermal growth factor receptor-2(HER2)-targeted tyrosine kinase Inhibitor pyrotinib and cyclin-dependent kinase 4/6(CDK4/6) Inhibitor dalpiciclib(SHR6390) in subjects with hormone receptor(HR)+/HER2+ relapsed or metastatic breast cancer. The study will enroll natural postmenopausal women, or women who have undergone bilateral oophorectomy.The phase Ib part of the study will determine safety and tolerability of the combination of endocrine therapy, pyrotinib and dalpiciclib to define that appropriate dose of dalpiciclib for phase II.Data from phase Ib showed the triplet of pyrotinib, dalpiciclib, andendocrine therapy had an acceptable safety profile and encouraging efficacy, potentially offering a chemotherapy-sparing treatment option for patients with HER2-positive/HR-positive MBC.Once the recommended regimen has been identified, subjects with the selected tumor type will be enrolled into expansion cohorts for the purpose of assessing efficacy and safety of the combination treatment.