A Study of Atezolizumab in Participants With Locally Advanced or Metastatic Urothelial Bladder Cancer (Cohort 2)

Inclusion Criteria:

   - Histologically or cytologically documented locally advanced or metastatic transitional
   cell carcinoma of the urothelium (including renal pelvis, ureters, urinary bladder,
   urethra)

   - Representative tumor specimens as specified by the protocol

   - Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1

   - Life expectancy greater than or equal to (>=) 12 weeks

   - Measurable disease, as defined by RECIST v1.1

   - Adequate hematologic and end organ function

Cohort 2-Specific Inclusion Criteria

   - Disease progression during or following treatment with at least one
   platinum-containing regimen (e.g., gemcitabine and cisplatin [GC], methotrexate,
   vinblastine, doxorubicin, and cisplatin [MVAC], CarboGem, etc.) for inoperable locally
   advanced or metastatic urothelial carcinoma or disease recurrence.

   - A regimen was defined as participants receiving at least two cycles of a
   platinum-containing regimen. Participants who had received one cycle of a
   platinum-containing regimen but discontinued due to Grade 4 hematologic toxicity or
   Grade 3 or 4 non-hematologic toxicity could also be eligible.

   - Participants who received prior adjuvant/neoadjuvant chemotherapy and progressed
   within 12 months of treatment with a platinum-containing adjuvant/neoadjuvant regimen
   were considered as second-line participants.

Exclusion Criteria:

   - Any approved anti-cancer therapy within 3 weeks prior to initiation of study treatment

   - Treatment with any other investigational agent or participation in another clinical
   trial with therapeutic intent within 28 days prior to enrollment

   - Active or untreated central nervous system (CNS) metastases as determined by computed
   tomography (CT) or magnetic resonance imaging (MRI) evaluation during screening and
   prior radiographic assessments

   - Leptomeningeal disease

   - Uncontrolled tumor-related pain

   - Uncontrolled pleural effusion, pericardial effusion, or ascites requiring recurrent
   drainage procedures (once monthly or more frequently)

   - Uncontrolled hypercalcemia (greater than [>] 1.5 millimoles per liter [mmol/L] ionized
   calcium or Ca > 12 milligrams per deciliter [mg/dL] or corrected serum calcium > upper
   limits of normal [ULN]) or symptomatic hypercalcemia requiring continued use of
   bisphosphonate therapy or denosumab

   - Malignancies other than urothelial bladder cancer within 5 years prior to Cycle 1, Day
   1, with the exception of those with a negligible risk of metastasis or death treated
   with expected curative outcome or incidental prostate cancer

   - Pregnant and lactating women

   - History of autoimmune disease

   - History of idiopathic pulmonary fibrosis, organizing pneumonia, drug-induced
   pneumonitis, idiopathic pneumonitis, or evidence of active pneumonitis on screening
   chest CT scan

   - Serum albumin less than (<) 2.5 grams per deciliter (g/dL)

   - Positive test for human immunodeficiency virus (HIV) and/or active hepatitis B or
   hepatitis C or tuberculosis

   - Severe infections within 4 weeks prior to Cycle 1, Day 1

   - Significant cardiovascular disease

   - Major surgical procedure other than for diagnosis within 28 days prior to Cycle 1, Day
   1

   - Prior allogeneic stem cell or solid organ transplant

   - Administration of a live, attenuated vaccine within 4 weeks before Cycle 1, Day 1

   - Any other diseases, metabolic dysfunction, physical examination finding, or clinical
   laboratory finding giving reasonable suspicion of a disease or condition that
   contraindicates the use of an investigational drug or that may affect the
   interpretation of the results or render the patient at high risk from treatment
   complications

   - Prior treatment with CD137 agonists or immune checkpoint blockade therapies, including
   anti-cytotoxic T lymphocyte-associated antigen 4 (anti-CTLA-4), anti-programmed
   death-1 receptor (anti-PD-1), and anti-programmed death-ligand 1 (anti-PD-L1)
   therapeutic antibodies