A Phase II Clinical Study to Assess the Efficacy and Safety of IBI310 or Placebo Combined With Sintilimab for Advanced Cervical Cancer Subjects Who Have Failed or Cannot Tolerate First-line or Above Platinum-based Chemotherapy

Inclusion Criteria: 1. The subject must sign the written informed consent form, and can comply with the visits and related procedures specified in the protocol. 2. Aged ≥18 years and ≤75 years. 3. Diagnosed with cervical cancer by histology/cytology. 4. Patients with relapsed or metastatic cervical cancer who have had progressed or relapsed after receiving at least first-line of platinum-based chemotherapy (if a patient has progressed or relapsed during or within 6 months after receiving platinum-based neoadjuvant or adjuvant chemotherapy, she will be deemed to have received first-line treatment). 5. The subject's previous systemic treatment must have ended ≥4 weeks before the first study administration, and the treatment-related AEs have recovered to Common Terminology Criteria for Adverse Events (CTCAE) V5.0 grade ≤1 (except for alopecia and fatigue). Exclusion Criteria: 1. Diagnosis of other malignant tumors within 5 years before the first administration, excluding radically cured skin basal cell carcinoma, skin squamous cell carcinoma, radically resected carcinoma in situ and/or thyroid papillary carcinoma. 2. Pleural effusion, ascites, and pericardial effusion with clinical symptoms or requiring drainage (patients with effusion that does not require drainage or patients with no significant increase in the effusion within 3 days after stopping drainage can be selected). 3. Patients who are planning to undergo or have previously received organ or bone marrow transplantation. 4. Patients with acute or chronic active hepatitis B or C infection, hepatitis B virus (HBV) DNA\> 200 IU/ml or 103 copies/ml; hepatitis C virus (HCV) antibody positive and HCV-RNA level higher than the lower limit of detection. Patients with acute or chronic active hepatitis B or C infection who have received nucleotide antiviral therapy and are below the above standards can be selected. 5. Meningeal metastases or symptomatic central nervous system (CNS) metastases. Patients with asymptomatic brain metastases who do not need treatment with glucocorticoids, anticonvulsants or mannitol after radiotherapy can be enrolled.