The study is being conducted to evaluate the efficacy and safety of HRS-8080 combined with dalpiciclib versus fulvestrant combined with dalpiciclib in patients with locally advanced/metastatic breast cancer who had developed drug resistance to prior adjuvant endocrine therapy.
Women aged 18 - 75 years old;
Eastern Cooperative Oncology Group performance status (ECOG-PS) of 0 to 1;
Patients with histologically confirmed locally advanced or metastatic breast cancer;
Patients with prior adjuvant endocrine resistance following curative-intent surgery;
Patients with rapidly progressing disease, as judged by the investigator to be unsuitable for endocrine therapy;
Patients who have previously received fulvestrant or other novel SERMs (excluding tamoxifen and toremifene);
Patients with uncontrolled brain metastases, carcinomatous meningitis, or spinal cord compression;
Patients with a history of clinically significant cardiovascular disease;