Inclusion Criteria:

          -  Diagnosis of Urothelial carcinoma (UC) of the bladder, with histologic confirmation of
             primary UC pathology; indication for Radical cystectomy (RC); ineligibility for
             platinum-based neoadjuvant chemotherapy

          -  ECOG Performance Status (PS) 0 or 1.

          -  Ability to provide informed consent.

          -  Willingness to comply with all required protocol procedures including providing
             biologic specimens and returning to the clinical study site for follow up visits.

          -  Performance status sufficient to undergo RC (in the opinion of the enrolling
             urologist) including adequate hematological, liver and kidney function

          -  Must be willing to implement contraception throughout study and for 30 days following
             RC.

        Exclusion Criteria:

          -  Variant UC pathology including but not limited to micropapillary, signet
             ring,sarcomatoid, and clear cell variants.

          -  Patients with any other prior malignancy are not allowed except for the following:
             History of or concurrent non-invasive UC involving a portion of urinary tract outside
             of the bladder; Adequately treated basal cell or squamous cell skin cancer; In situ
             cervical cancer; Adequately treated Stage I or II cancer from which the patient is
             currently incomplete remission or other cancer from which the patient has been
             disease-free for 2 years.

          -  Prior treatment with an anti-PD-1, anti-PD-L1, anti-PD-L2, anti-CTLA-4 antibody, or
             any other antibody or drug specifically targeting T-cell co-stimulation or immune
             checkpoint pathways.

          -  Any of the following prior therapy: Chemotherapy ≤ 3 weeks prior to registration.
             Biologic therapy ≤ 4 weeks prior to registration. Radiation therapy ≤ 3 weeks prior to
             registration

          -  Other concurrent investigational therapy (utilized for a non-FDA-approved indication
             and in the context of a research investigation).

          -  Pregnant women.

          -  Nursing women.

          -  Men or women of childbearing potential who are unwilling to employ adequate
             contraception during treatment and 8 weeks following the completion of study drug
             treatment.

          -  Allergy to measles vaccine or history of severe reaction to prior measles vaccination.

          -  History of organ transplantation.