Evaluation of TQB3616 Capsules in a Phase II Clinical Trial for Recurrent/Metastatic Breast Cancer

Inclusion Criteria: * Subjects voluntarily join the study, sign the informed consent form, and have good compliance * Aged 18 to 75 years, with an Eastern Cooperative Oncology Group Performance Status (ECOG PS) score of 0\~1; expected survival time of more than 3 months. * Postmenopausal or premenopausal/perimenopausal female patients * Progressed after prior treatment with CDK4/6 inhibitors * At least one measurable lesion according to Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 criteria * Good major organ function * Women of childbearing potential must agree to use contraception during the study and for 6 months after its completion. Exclusion Criteria: * Subjects with a previous pathological diagnosis of HER2-positive breast cancer. * Subjects with inflammatory breast cancer or occult breast cancer. * Subjects who have had or currently have other malignant tumors within 5 years prior to randomization. * Subjects with unresolved toxicity (greater than Common Terminology Criteria for Adverse Events (CTCAE) Grade 1) from prior treatment, excluding alopecia. * Subjects who have undergone major surgical procedures, incisional biopsies, or significant traumatic injuries within 28 days prior to the first dose. * Subjects with non-tumor-related unresolved wounds, ulcers, or fractures. * Subjects with multiple factors affecting oral medication intake and absorption. * Subjects with arterial or deep vein thrombotic events within 6 months prior to the first dose. * S…