The study is comprised of two parts: Phase Ia and Phase Ib. Phase Ia includes dose-escalating stage and dose expansion stageof SIM0270 monotherapy to determine the MTD/ RP2D and the preliminary safety and efficacy of SIM0270; Phase Ib includes 2 arms, armA: dose escalation and dose expansion of SIM0270 in combination with palbociclib; armB: dose escalation and dose expansion of SIM0270 in combination with palbociclib everolimus; phase Ib is designed to determine the MTD/RP2D and the preliminary safety and efficacy of SIM0270 in combination with palbociclib or everolimus.
This study is a multi-center, open-label, Phase 1 clinical study to evaluate the safety, pharmacokinetic (PK) and anti-tumor efficacy of SIM0270 and SIM0270 in combination with palbociclib or everolimus in subjects with estrogen receptor (ER) -positive, human epidermal growth factor receptor (HER-2) -negative locally advanced or metastatic breast cancer.