Study of Cretostimogene Given in Patients With Non-Muscle Invasive Bladder Cancer ,Unresponsive to Bacillus-Calmette-Guerin

Inclusion Criteria: In order to be eligible for participation in this trial, the patient must: 1. Be ≥18 years of age on day of signing informed consent. \- Patients must have pathologically confirmed BCG-unresponsive non-muscle-invasive bladder cancer (NMIBC) with carcinoma in situ (CIS), with or without concomitant Ta/T1 papillary disease. 2. Have Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 2. 3. Have all Ta and/or T1 disease resected and all CIS resected or fulgurated, as feasible, prior to study treatment. 4. Demonstrate adequate organ function. 5. Patients must be willing to comply with study mandated cystoscopies, urine cytology, urograms, biopsies, and other procedures (including TURBT or other resection for all Ta/T1 disease) for the duration of the study. Patients who withdraw consent for these procedures will be withdrawn from the trial. 6. Ineligible to receive radical cystectomy or refusal of radical cystectomy according to Investigator assessment. Exclusion Criteria: 1. Has current or past history of muscle invasive (T2 or higher stage) or locally advanced (T3/T4, any N) or metastatic bladder cancer. 2. History of urothelial carcinoma in the upper genitourinary tract (kidney, renal collecting system, ureter) or in the prostatic urethra, including urethral CIS, within 24 months prior to enrollment. 3. Has received systemic anti-cancer therapy, including investigational agents. 4. Has had prior systemic treatment (with the exception of checkpoint inhibitor therapy), radiation therapy, or surgery for bladder cancer other than TURBT or bladder biopsies. 5. Has any of the following within the 6 months prior to starting study treatment: myocardial infarction, severe/unstable angina, coronary/peripheral artery bypass graft, cerebrovascular accident, pulmonary embolus, uncontrolled hypertension, or uncontrolled congestive heart failure. 6. Cannot tolerate study-related biopsies, IVE administration, or 1-hour bladder hold of Cretostimogene.