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.

The objective of this study is to assess the overall response rate, evaluate the antitumor activity, and characterize the safety and tolerability of BGB-A445 alone or in combination with tislelizumab in participants With Advanced or Metastatic Urothelial Carcinoma (UC), Renal Cell Carcinoma (RCC), or Melanoma

Inclusion Criteria:Participants described in the following cohorts, who have received at least 1 but no more than 3 lines of prior systemic therapy for histologically or cytologically confirmed advanced and/or metastatic UC, RCC or melanoma Participants must not have received prior therapy targeting OX40 or any other T-cell agonistsHas at least 1 measurable lesion as defined per RECIST v1.1.Participants must be able to provide an archived formalin-fixed paraffin embedded (FFPE) tumor tissue sampleECOG PS ≤ 1 (Participants with UC could have an ECOG PS ≤ 2) and a life expectancy of≥ 3 monthsAdequate organ function as indicated by the laboratory values up to the first dose of study drug(s)Exclusion Criteria:Active leptomeningeal disease or uncontrolled brain metastasisActive autoimmune diseases or history of autoimmune diseases that may relapse or history of life-threatening toxicity related to prior immune therapyAny active malignancy ≤ 2 years before the first dose of study drug(s) except for the specific cancer under investigation in this study and any locally recurring cancer that has been treated with curative intentAny condition that required systemic treatment with either corticosteroids (> 10 mg daily of prednisone or equivalent) or other immunosuppressive medication ≤ 14 days before the first dose of study drug(s), with the following exceptions:Adrenal replacement steroid (dose ≤ 10 mg daily of prednisone or equivalent)Topical, ocular, intra-articular, intranasal, or inhalational corticosteroid with minimal systemic absorptionShort course (≤ 7 days) of corticosteroid prescribed prophylactically (eg, for contrast dye allergy) or for the treatment of a nonautoimmune condition (eg, delayed-type hypersensitivity reaction caused by contact allergen)With uncontrolled diabetes, or > Grade 1 laboratory test abnormalities in potassium, sodium, or corrected calcium despite standard medical management, or ≥ Grade 3 hypoalbuminemia occurring ≤ 14 days before the first dose of study drug(s)Note: Other protocol defined Inclusion/Exclusion criteria may apply