Key Inclusion Criteria:

          -  Eastern Cooperative Oncology Group (ECOG) performance status 0 to 2

          -  Have pathologically confirmed World Health Organization (WHO) grading system employed
             for tumor grading) high-risk NMIBC unresponsive to prior BCG therapy defined as:

        Persistent or recurrent CIS alone or with recurrent Ta/T1 (noninvasive papillary
        disease/tumor invades the subepithelial connective tissue) disease within 12 months of
        completion of adequate BCG therapy

          -  Received prior adequate BCG therapy as defined as at least one of the following ("5+2"
             minimum exposure):

               1. At least five of six doses of an initial induction course (adequate induction)
                  plus at least two of three doses of maintenance therapy, OR

               2. At least five of six doses of an initial induction course (adequate induction)
                  plus at least two of six doses of a second induction course.

          -  Ineligible for radical cystectomy or refusal of radical cystectomy

          -  Adequate organ function

        Key Exclusion Criteria:

          -  Muscle invasive (T2 or higher stage) or locally advanced (T3/T4, any N) or metastatic
             bladder cancer

          -  Has known upper tract or prostatic urethra malignancy

          -  Has systemic anti-cancer therapy, including investigational agents, within 4 weeks of
             Baseline

          -  Immuno-deficient due to chronic steroid or other immunosuppressant use, HIV, or prior
             organ transplant

          -  Prior treatment with adenovirus-based cancer therapy

          -  Clinically significant or active cardiac disease

          -  Active autoimmune disease