A Phase 1b Study to Assess Sitravatinib in Combination With Tislelizumab in Participants With Advanced Solid Tumors

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. Participants 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. 7. 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 8. Known history of human immunodeficiency virus (HIV) infection 9. Participants with active hepatitis C infection 10. Any major surgical procedure requiring general anesthesia ≤ 28 days before first dose of study drugs 11. Prior allogeneic stem cell transplantation or organ transplantation 12. Hypersensitivity to tislelizumab or sitravatinib, to any ingredient in the formulation, or to any component of the container 13. Bleeding or thrombotic disorders or use of anticoagulants such as warfarin or similar agents requiring therapeutic international normalized ratio (INR) monitoring within 6 months before first dose of study drugs 14. Concurrent participation in another therapeutic clinical trial