Zimberelimab Plus Metformin for Recurrent Ovarian Clear Cell Carcinoma

Inclusion Criteria: * Age ≥ 18 years to ≤ 75 years * Pathologic confirmed ovarian clear cell carcinoma * Patients with recurrent or persistent ovarian clear cell carcinoma must have at least one-line pretreated platinum-containing chemotherapy * According to the definition of RECIST1.1, the patient must have measurable lesions * PD-L1 Combined Positive Score ≥ 1 * ECOG performance status of 0 to 2 * Adequate bone marrow, liver, and renal function to receive combined immunotherapy * Written informed consent Exclusion Criteria: * Histological evidence of non-ovarian clear cell carcinoma * Lack of tumor samples (archived and/or recently obtained) * Previous administration of immunotherapy * Patients have been vaccinated with the live vaccine or received anti-tumor treatment within 4 weeks before the first administration * An active autoimmune disease that requires systemic treatment (such as the use of disease-relieving drugs, glucocorticoids, or immunosuppressive agents) within 2 years before the first administration * Synchronous or metachronous (within 5 years) malignancy other than carcinoma in situ or breast cancer (without any signs of relapse or activity) Symptomatic or uncontrolled visceral metastases that require simultaneous treatment * Patients are known to be allergic to the active ingredients or excipients of zimberelimab or metformin * Known human immunodeficiency virus (HIV) infection history (HIV 1/2 antibody positive). * Untreated active hepatitis B (defined as HBsAg positive and the number of copies of HBV-DNA detected at the same time is greater than the upper limit of the normal value of the laboratory department of the research center) * Contraindications to metformin: kidney dysfunction or abnormal creatinine from any cause; acute or metabolic acidosis