A Study to Evaluate Safety, Pharmacokinetics, & Activity of RO7496353 in Combination With a Checkpoint Inhibitor With or Without Standard-of-care Chemotherapy in Participants With Locally Advanced or Metastatic Solid Tumors; Urothelial Carcinoma Substudy in Association With RO7496353 Study GO44010

• Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1
• Life expectancy of at least 3 months
• Adequate hematologic and end-organ function
• Histologically confirmed locally advanced, recurrent, or metastatic incurable solid tumor malignancy
• Measurable disease according to RECIST v1.1 on computed tomography (CT) or magnetic resonance imaging (MRI) images within 28 days prior to enrollment
• Availability of representative tumor specimens in formalin-fixed, paraffin-embedded (FFPE) blocks or at least 15 unstained slides

• Any anti-cancer therapy, whether investigational or approved, including chemotherapy, hormonal therapy, and/or radiotherapy, within 3 weeks prior to initiation of study treatment
• Symptomatic, untreated, or actively progressing central nervous system (CNS) metastases
• Significant cardiovascular disease (such as New York Heart Association Class II or greater cardiac disease, myocardial infarction, or cerebrovascular accident) within 3 months prior to initiation of study treatment, unstable arrhythmia, or unstable angina
• History of leptomeningeal disease
• Uncontrolled tumor-related pain
• Positive test for human immunodeficiency virus (HIV) infection
• Positive hepatitis B surface antigen (HbsAg) test, and/or positive total hepatitis B core antibody (HbcAb) test at screening
• Positive hepatitis C virus (HCV) antibody test at screening
• Known allergy or hypersensitivity to any component of the RO7496353 formulation or any of the study drugs or their excipients

Other protocol-defined inclusion/exclusion criteria may apply.