An Exploratory Study of Surufatinib Combined With Chidamide and Fulvestrant in HR Positive Unresectable Metastatic Breast Cancer

This is a prospective, single center, single arm phase II study. In the safety lead-in stage, 6 subjects will be recruited and administered with surufatinib 250 mg/d, QD PO; Fulvestrant 500mg, im, Q4W; Chidamide 30mg, PO, BIW, with four weeks as a cycle. DLTs of the 6 subjects will be evaluated in the first cycle to determine the recommended dosage of combinational therapy. Then 57 subjects will be recruited and administered with the triplet regimen to explore the efficacy and safety of combinational treatment.