• Subjects were fully informed about the study and voluntarily signed an informed consent form and were willing to complete the trial in accordance with the protocol process.

• Male or female, ≥18 years of age at time of informed consent.

• First TURBT completed within 12 weeks prior to the first dose, histologically confirmed diagnosis of non-muscle invasive bladder cancer and classified as high risk according to the European Association of Urology 2020 version of the Non-Muscle Invasive Bladder Cancer Guidelines.

• Patients who had failed intravesical administration of BCG prior to enrolment and were not candidates for or refused radical cystectomy.BCG failures included BCG refractory, recurrence after BCG, BCG non-responsive, and BCG intolerant;

• After TURBT, it is confirmed that the tumour has been completely removed from the bladder. A second TURBT is required for the following: confirmed or suspected incomplete resection of the tumour by TURBT; absence of muscularis propria tissue in the first resection of the tumour specimen, except for TaLG/G1 tumours or primary carcinoma in situ; and stage T1 bladder tumours. A second TURBT is recommended 2 to 6 weeks after the initial TURBT.

• Eastern Cooperative Oncology Group (ECOG) score 0 to 1.

• Expected survival ≥ 6 months.

• The major organs are functioning well, i.e. the following criteria are met:

‣ Bone marrow function: hemoglobin (HGB) ≥80 g/L, platelet count (PLT) ≥100×109/L, absolute neutrophil count (ANC) ≥1.5×109/L.

⁃ Liver function: serum total bilirubin ≤ 1.25 x upper limit of normal (ULN) (or 2.5 × ULN in case of constitutional hepatic dysfunction jaundice \[Gilbert's syndrome\]), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤ 2.5× ULN.

⁃ Renal function: creatinine clearance ≥30 mL/min (Cockcroft-Gault formula) or serum creatinine ≤2.0 mg/dL.