A Study of Apatinib Combined With Letrozole With or Without Fluzoparib in Estrogen Receptor-Positive, Platinum-Sensitive Recurrent Ovarian Cancer Previously Treated With First-Line PARP Inhibitor

Inclusion Criteria: * Age ≥ 18 years; * ECOG Performance Status score of 0 or 1; * Epithelial ovarian cancer with platinum-sensitive recurrence (no restriction on histological type); * Patients who have received first-line maintenance treatment with olaparib or niraparib (including but not limited to) and achieved complete response (CR) or partial response (PR) to second-line platinum-based chemotherapy; * Availability of genetic testing results (BRCA1/2) and estrogen receptor (ER) testing results (ER positivity is defined as ≥ 1% of tumor cells staining positive for ER); * Estimated survival of ≥ 6 months; * Good function of major organs in the subject, with relevant test results meeting the following requirements within 7 days prior to enrollment: Hematological tests (no blood transfusion or use of hematopoietic growth factors within 7 days prior to screening): Hemoglobin (Hb) ≥ 90 g/L; Absolute neutrophil count (ANC) ≥ 1.5×10⁹/L; Platelet count (PLT) ≥ 100×10⁹/L; White blood cell count (WBC) ≥ 3.0×10⁹/L and ≤ 15×10⁹/L; Biochemical tests (no blood transfusion or albumin within 7 days prior to screening): Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤ 2.5 times the upper limit of normal (ULN); Alkaline phosphatase (ALP) ≤ 2.5 ULN; Total bilirubin (TBIL) ≤ 1.5 ULN; Serum creatinine (Cr) ≤ 1.5 ULN, with creatinine clearance (CrCL) ≥ 60 mL/min (Cockcroft-Gault formula); Prothrombin time (PT) and activated partial thromboplastin time (APTT) ≤ 1.5 ULN,…