A Study of SHR-1501 Combination With BCG Versus Placebo Combined With BCG in Subjects With Papillary-Only NMIBC

1. Aged at least 18 years, gender is not limited;
2. Eastern Cooperative Oncology Group (ECOG) performance status of ≤ 2;
3. Histologic confirmation of high-riskpapillary-only non-muscle invasive bladder cancer (high-grade Ta and/or any T1, no carcinoma in situ);
4. No previous BCG therapy;
5. Cystoscopy within 6 weeks before the randomization shows that the lesion has been completely removed; for T1 stage lesions, pathological results must show the presence of bladder muscle tissue;
6. Sufficient hematology and organ function;

Exclusion Criteria:

1. Previous histopathological diagnosis was muscle-invasive, locally advanced or metastatic urothelial carcinoma (T2 or T3 or T4 or N+ or M+).
2. Received surgery such as TURBT or radiotherapy for bladder lesions within 2 weeks before the randomization; Major surgery was performed within 28 days before randomization;
3. Those who have previously received immunostimulant therapy or immune checkpoint inhibitors;
4. Those who have previously received intravesical instillation of cytotoxic chemotherapy and have not experienced disease recurrence or progression before enrolment as assessed by investigator;
5. Those who plan to undergo radical (partial) cystectomy during the study;
6. Upper urinary tract tumor detected by CTU or MRU during screening period, urethral prostate tumor detected by cystoscopy, or other concomitant malignant tumors within 5 years before the first administration;
7. Previous medical history or examination suggests active tuberculosis within 1 year prior to the randomization;