Overview
The main purpose of this study is to evaluate the efficacy and safety of GB491 combined with Letrozole versus placebo combined with Letrozole in the treatment of HR+/HER2- locally advanced or metastatic breast cancer without prior systemic antitumor therapy
Eligibility
Inclusion Criteria:
- 1. Age: 18-75 years old;
- Have a pathologically-confirmed diagnosis of hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) breast cancer;
- No previous systematic antitumor therapy for locally advanced or metastatic breast cancer;
- Eastern Cooperative Oncology Group [ECOG] 0-1;
- Have adequate organ and marrow function;
- Agree to sign the informed consent;
Exclusion Criteria:
- Systematic treatment with any other CDK4/6 inhibitor；
- Subjects with known allergy to GB491 or any component of Letrozole；
- Confirmed diagnosis of HER2 positive disease;
- Known uncontrolled, or symptomatic central nervous system metastases;
- Had major surgery (or is expected to require major surgery during the study period), chemotherapy, radiation, any investigational drug, or other antitumor therapy within 4 weeks prior to randomization;
- Have previously received chemotherapy for locoregionally recurrent or metastatic breast cancer;
- Clinically significant cardiovascular and cerebrovascular diseases, including but not limited to severe acute myocardial infarction within 6 months before enrollment, unstable or severe angina, Congestive heart failure, or ventricular arrhythmia which need medical intervention；
- Known history of HIV infection or HIV seropositivity (including HIV antibody positive at the time of screening)