Inclusion Criteria:

          1. Able to provide written informed consent and can understand and agree to comply with
             the requirements of the study and the Schedule of Assessments

          2. Age ≥ 18 years on the day of signing the informed consent form (or the legal age of
             consent in the jurisdiction in which the study is taking place)

          3. At least 1 measurable lesion as defined by RECIST v1.1

          4. Provide archival tumor tissue (formalin-fixed paraffin-embedded block [FFPE] with
             tumor tissue or unstained slides), if available.

          5. Eastern Cooperative Oncology Group (ECOG) Performance Status ≤ 1

          6. Adequate hematologic and end-organ function

          7. Patients with inactive/asymptomatic carrier, chronic, or active hepatitis B virus
             (HBV) must have HBV deoxyribonucleic acid (DNA) < 500 IU/mL (or 2500 copies/mL) at
             Screening

          8. Females of childbearing potential must be willing to use a highly effective method of
             birth control for the duration of the study, and ≥ 120 days after the last dose of
             study drugs and have a negative serum pregnancy test ≤ 7 days of first dose of study
             drugs

          9. Non-sterile males must be willing to use a highly effective method of birth control
             for the duration of the study and for ≥ 120 days after the last dose of study drugs

        Exclusion Criteria:

          1. Unacceptable toxicity on prior anti-PD-1/PD-L1 treatment.

          2. Active leptomeningeal disease or uncontrolled brain metastasis.

          3. Active autoimmune diseases or history of autoimmune diseases that may relapse.

          4. Any active malignancy ≤ 2 years

          5. Any condition that required systemic treatment with either corticosteroids (> 10 mg
             daily of prednisone or equivalent) or other immunosuppressive medication ≤ 14 days
             before first dose of study drugs

          6. History of interstitial lung disease, noninfectious pneumonitis or uncontrolled
             diseases, including pulmonary fibrosis, acute lung diseases, etc.

        8. Severe chronic or active infections (including tuberculosis infection, etc.) requiring
        systemic antibacterial, antifungal or antiviral therapy, within 14 days prior to first dose
        of study drugs

        9. Known history of HIV infection

        10. Patients with active hepatitis C infection.

        11. Any major surgical procedure requiring general anesthesia ≤ 28 days before first dose
        of study drugs

        12. Prior allogeneic stem cell transplantation or organ transplantation

        13. Hypersensitivity to tislelizumab or sitravatinib, to any ingredient in the formulation,
        or to any component of the container

        14. Bleeding or thrombotic disorders or use of anticoagulants such as warfarin or similar
        agents requiring therapeutic INR monitoring within 6 months before first dose of study
        drugs

        15. Concurrent participation in another therapeutic clinical trial