A Study of Two Dosing Schedules of Atezolizumab in Combination With Gemcitabine and Cisplatin as First-Line Treatment for Metastatic Bladder Cancer

Inclusion Criteria: * Histologically confirmed urothelial carcinoma of the bladder, ureter, urethra, or renal pelvis by the enrolling institution. Patients with mixed histologies are required to have a predominant urothelial component as reviewed by the pathologist at the enrolling institution. * Locally advanced (T4b, any N: any T, N2-3) or metastatic (M1) disease as determined by the treating investigator. * Age ≥18 years * Life expectancy ≥ 12 weeks * The patient must have measurable disease according to RECIST v1.1 and must have one site amenable to biopsy that, in the opinion of the investigator and/or interventional radiologist, is likely to yield acceptable tumor sample for a core biopsy per the below pathology criteria. * Subject must agree to undergo two research-directed biopsies during treatment. * Patients must have adequate tumor tissue available for PD-L1 testing. Adequate tumor tissue is defined as: * For core-needle biopsy specimens, at least three cores should be submitted for evaluation if feasible. Acceptable samples include core-needle biopsies for deep tumor tissue (minimum of three cores) or excisional, incisional, punch, or forceps biopsies for cutaneous, subcutaneous, or mucosal lesions. Samples collected from fine-needle aspiration, brushing, cell pellet from pleural effusion, bone metastases without a soft tissue component, and lavage are not acceptable. * For pre-treatment archival tissue, representative urothelial carcinoma FFPE tumor specime…