• Histologically confirmed non muscle invasive bladder cancer (NMIBC), defined as noninvasive papillary carcinoma (Ta), carcinoma in situ (CIS) or carcinoma invading the subepithelial connective tissue (T1), determined via transurethral resection of bladder tumor (TURBT) within 3 months of enrollment

• Participant must have Bacillus Calmette Guerin (BCG)-unresponsive NMIBC or intolerance of treatment with BCG. BCG-unresponsive disease is defined as being at least one of the following:

‣ 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

⁃ Recurrent high-grade Ta/T1 disease within 12 months of completion of adequate BCG therapy

⁃ T1 high-grade disease at the first evaluation following an induction BCG course. In this context, adequate BCG therapy is defined as at least one of the following:

• At least five of six doses of an initial induction course plus at least two of three doses of maintenance therapy

∙ At least five of six doses of an initial induction course plus at least two of six doses of a second induction course

• Refuse or intolerant of a radical cystectomy recommended by the treating urologist as the standard next therapy per American Urological Association (AUA) guideline

• Age ≥ 18 years at time of consent

• Performance status: Eastern Cooperative Oncology Group (ECOG) performance status of 0, 1, or 2

• Patient with life expectancy greater than 24 months

• No concurrent radiotherapy, chemotherapy, or other immunotherapy for bladder cancer. No BCG or other intravesical treatment within 4 weeks

• No scheduled radiotherapy, chemotherapy, other immunotherapy, or surgery before the scheduled response evaluation

• Recovery from prior treatment side effects that might interfere with the study treatment, in the judgment of the investigator

• Absolute neutrophil count (absolute granulocyte count \[AGC\]/absolute neutrophil count \[ANC\]) ≥ 1,500/µL

• Platelets ≥ 100,000/µL (Patients may be transfused to meet this requirement)

• Hemoglobin ≥ 8 g/dL (Patients may be transfused to meet this requirement)

• Calculated glomerular filtration rate (GFR) ≥ 30 mL/min

• Total bilirubin ≤ 2.0 × institutional upper limit of normal (ULN) (\< 3 × ULN for patients with Gilbert's syndrome)

• Aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP) ≤ 3.0 × institutional ULN

• Adequate pulmonary function by clinical assessment with no clinical signs of severe pulmonary dysfunction

• Participants of childbearing potential must agree to using adequate contraception (e.g., hormonal or barrier method of birth control; abstinence, an intrauterine device) for the duration of study participation (including dosing interruptions) and up to 3 months after last study treatment; or be surgically sterilized (e.g., hysterectomy, tubal ligation, or vasectomy)

• Ability to understand and willingness to sign an informed consent form

• Ability and willingness to adhere to the study visit schedule and other protocol requirements