‣ BCG-unresponsive Patients:

• BCG-unresponsive NMIBC with carcinoma in situ (CIS) with or without coexisting papillary Ta/T1 tumors who are ineligible for or have elected not to undergo cystectomy, and have experienced CIS disease within 12 months of treatment where: adequate BCG regimen consists of at least 2 courses of BCG where the first course (induction) must have included at least 5 or 6 doses and the second course may have included a re-induction (at least 2 treatments) or maintenance (at least 2 doses), and Cis must be documented or indicated by pathology

• Phase 2 Only:

• BCG-Naïve or BCG-incompletely treated Patients with CIS or BCG-unresponsive, HG Ta/T1 papillary disease without CIS:

⁃ NMIBC with current Cis of the bladder, with or without coexisting papillary Ta/T1 NMIBC tumor(s), who are ineligible for or have elected not to undergo cystectomy, where: either: cohort 2a) no treatment with BCG but may have previously been treated with at least 1 dose of intravesical chemotherapy following transurethral resection of bladder tumor (TURBT) and Cis must be documented or cohort 2b) indicated by pathology incomplete BCG treatment (at least 1 dose and less than the 5+2 doses required for adequate dosing per Cohort 1) or cohort 3) patients who are BCG-unresponsive following adequate treatment, with HG Ta/T1 papillary disease without CIS.

• All Patients:

• Patients who have previously been treated with a checkpoint inhibitor and failed treatment are eligible for inclusion 30 days post-treatment (Phase 1) or 3 months post-treatment (Phase 2).

• Male or non-pregnant, non-lactating female, 18 years or older.

• Women of childbearing potential must have a negative pregnancy test at Screening.

• Female patients of childbearing potential must be willing to consent to using highly effective birth control methods; Male patients are required to utilize a condom for the duration of the study treatment through 3 months post-dose.

• In Phase 2, for patients with T1 lesions may be eligible after repeat TURBT if pathology shows non-invasive (Ta or less) or no disease.

• Performance Status: Eastern Cooperative Oncology Group 0, 1, and 2.

• Hematologic inclusion: a. Absolute neutrophil count \>1,500/mm3. b. Hemoglobin \>9.0 g/dL. c. Platelet count \>100,000/mm3.

⁃ Hepatic inclusion: a. Total bilirubin must be ≤1.5 x the upper limit of normal (ULN). b. Aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase ≤2.5 x ULN.

⁃ Adequate renal function with creatinine clearance \>30 mL/min

⁃ Prothrombin time and partial thromboplastin time ≤1.25 x ULN or within the therapeutic range if on anticoagulation therapy.

⁃ Must have satisfactory bladder function with ability to retain study drug for 60 minutes.