A Study to Investigate the Antitumor Activity, Safety, Tolerability, and Pharmacokinetics of BGB-A445 in Combination With Tislelizumab in Participants With Select Advanced Solid Tumors.

Key Inclusion Criteria:

1. Participants who were histologically or cytologically confirmed advanced and/ormetastatic cancer. UC participants (Cohort A and B), RCC patients (Cohort C and D)or melanoma participants (Cohort E and F) who have received at least 1 but no morethan 3 lines of prior systemic therapy. Cisplatin ineligible UC participants (CohortG) who have received no prior systemic therapy and have PD-L1 CPS ≥ 10. Melanomapatients (Cohort H) with non-mucosal melanoma who have no previous systemictreatment. Melanoma participants (Cohort I) with non-mucosal melanoma who were CPIpretreated and have 1 or 2 lines of prior systemic therapy. Participants must nothave received prior therapy targeting OX40 or any other T-cell agonists.

2. Has at least 1 measurable lesion as defined per RECIST v1.1.

3. Participants must be able to provide an archived formalin-fixed paraffin embedded (FFPE) tumor tissue sample

4. ECOG PS ≤ 1 (Participants with UC could have an ECOG PS ≤ 2) and a life expectancyof≥ 3 months

5. Adequate organ function as indicated by the laboratory values up to the first doseof study drug(s)

Key Exclusion Criteria:

1. Active leptomeningeal disease or uncontrolled brain metastasis

2. Active autoimmune diseases or history of autoimmune diseases that may relapse orhistory of life-threatening toxicity related to prior immune therapy

3. Any active malignancy ≤ 2 years before the first dose of study drug(s) except forthe specific cancer under investigation in this study and any locally recurringcancer that has been treated with curative intent

4. Any condition that required systemic treatment with either corticosteroids (> 10 mgdaily of prednisone or equivalent) or other immunosuppressive medication ≤ 14 daysbefore the first dose of study drug(s), with the following exceptions:

5. Adrenal replacement steroid (dose ≤ 10 mg daily of prednisone or equivalent)

6. Topical, ocular, intra-articular, intranasal, or inhalational corticosteroidwith minimal systemic absorption

7. Short course (≤ 7 days) of corticosteroid prescribed prophylactically (eg, forcontrast dye allergy) or for the treatment of a nonautoimmune condition (eg,delayed-type hypersensitivity reaction caused by contact allergen)

8. With uncontrolled diabetes, or > Grade 1 laboratory test abnormalities in potassium,sodium, or corrected calcium despite standard medical management, or ≥ Grade 3hypoalbuminemia occurring ≤ 14 days before the first dose of study drug(s)

Note: Other protocol defined Inclusion/Exclusion criteria may apply