Inclusion Criteria:

          -  Patients with histologically confirmed urothelial cancer.

          -  ECOG Performance status score of 0 or 1.

          -  Cohort 1: Have had progression or recurrence of urothelial cancer following receipt of
             platinum-containing regimen (cisplatin or carboplatin):

               1. Received a first-line platinum-containing regimen in the metastatic setting or
                  for inoperable locally advanced disease;

               2. Or received neo/adjuvant platinum-containing therapy for localized
                  muscle-invasive urothelial cancer, with recurrence/progression ≤12 months
                  following completion of therapy.

          -  Cohort 1: In addition to above criterion, have had progression or recurrence of
             urothelial cancer following receipt of an anti-PD-1 /PD-L1 therapy.

          -  Cohort 2: Were ineligible for platinum-based therapy for first line metastatic disease
             and have had progression or recurrence of urothelial cancer after a first-line therapy
             for metastatic disease with anti-PD-1/PD-L1 therapy. Subject may not have received any
             platinum for treatment of recurrent, metastatic or advanced disease.

          -  Cohort 3: Progression or recurrence of UC following a platinum containing regimen in
             the metastatic setting, or progression or recurrence of UC within 12 months of
             completion of platinum-based therapy as neoadjuvant or adjuvant therapy.

        Cohort 4 and 5: Subject has not received any platinum-based chemotherapy in the metastatic
        or unresectable locally advanced setting.

        Cohort 4 and 5: Creatinine clearance of at least 50 mL/min calculated by Cockcroft-Gault
        formula or another validated tool. For subjects receiving cisplatin at 70 mg/m2 on Day 1 of
        every 21-day cycle, a creatinine clearance of least 60 mL/min calculated by Cockcroft
        -Gault formula or another validated tool is required. Subjects with creatinine clearance
        between 50 to 59 mL/min are to receive a split dose of cisplatin (35 mg/m2 Day 1 and Day 8
        of every 21-day cycle).

          -  Adequate renal and hepatic function.

          -  Adequate hematologic parameters without transfusional support.

          -  Creatinine clearance ≥30mL/min as calculated by the Cockroft-Gault formula.

          -  Subjects must have a 3-month life expectancy.

          -  Have measurable disease by CT or MRI as per RECIST 1.1 criteria.

        Exclusion Criteria:

          -  Women who are pregnant or lactating.

          -  Has had a prior anti-cancer monoclonal antibody (mAb) within 4 weeks prior to study
             Day 1 or who has not recovered (i.e., ≤ Grade 1 or at baseline) from adverse events
             due to agents administered more than 4 weeks earlier.

          -  Has had prior chemotherapy, targeted small molecule therapy, or radiation therapy
             within 2 weeks prior to study Day 1 or who has not recovered (i.e., ≤ Grade 1 or at
             baseline) from adverse events due to a previously administered agent.

          -  Requires concomitant medication interfering with ABCA1 transporter or UGT1A1

          -  Has an active second malignancy.

          -  Has known active central nervous system (CNS) metastases and/or carcinomatous
             meningitis.

          -  Has known active Hepatitis B or Hepatitis C

          -  Has other concurrent medical or psychiatric conditions

          -  Cohort 3: Has active autoimmune disease requiring systemic treatment with steroids or
             other immunosuppressive agent or any condition that in the Investigator's judgment
             precludes treatment with pembrolizumab

          -  Cohort 3: Has received a live vaccine within 30 days prior to the first dose of study
             drug(s)

          -  Cohort 3: Has history or evidence of interstitial lung disease (ILD) or non-infectious
             pneumonitis

          -  Cohort 3: Has received anti-PD-1/PD-L1 therapy previously

        Cohort 4 and 5: Refractory to platinum (i.e., relapsed ≤12 months after completion of
        chemotherapy) in the neoadjuvant/adjuvant setting.