Patients with extensive transurethrally unresectable very-high-risk non-muscle-invasive bladder cancer (NMIBC) may achieve a tumor-free status after systemic immunotherapy-based bladder-sparing treatment combined with transurethral resection of bladder tumor (TURBT). However, the optimal duration of systemic immunotherapy after achieving a tumor-free status remains uncertain. Prolonged treatment may increase toxicity, treatment burden, and cost, while some patients may maintain durable disease control without continued therapy.

This randomized study aims to evaluate whether active surveillance after achieving tumor-free status is a feasible alternative to continued systemic immunotherapy in patients with extensive transurethrally unresectable very-high-risk NMIBC.

Patients will initially receive systemic immunotherapy-based treatment followed by disease evaluation using cystoscopy with biopsy and/or TURBT, urine cytology, urinary tumor DNA (utDNA), and imaging assessments. Patients who achieve tumor-free status after treatment and complete resection of visible disease will be randomized to either active surveillance or continued systemic immunotherapy.

The study will evaluate recurrence outcomes, bladder preservation, progression, safety, and patient management strategies following achievement of tumor-free status. The trial also aims to explore the role of urinary tumor DNA in identifying patients who may safely undergo treatment de-escalation and active surveillance.

Inclusion Criteria

• Has histologically confirmed very-high-risk non-muscle-invasive urothelial carcinoma of the bladder.

• Has transurethrally unresectable bladder tumor, defined as visually incomplete TURBT and/or extensive high-volume disease considered unsuitable for complete and oncologically adequate transurethral resection.

• Has undergone cystoscopy and TURBT evaluation before study enrollment.

• Has received systemic PD-1/PD-L1 inhibitor-based bladder-sparing therapy before randomization.

• Has achieved tumor-free status before randomization, defined as:

  1. No visible bladder tumor on cystoscopy;
  2. Negative bladder biopsy and/or TURBT pathology;
  3. Negative urine cytology;
  4. Negative urinary tumor DNA (utDNA);
  5. No radiographic evidence of progression or metastasis.

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

• Has adequate organ function.

• Has provided written informed consent.

Cohort A Only

• Achieved tumor-free status at the initial response evaluation after induction systemic therapy.
• Maintained tumor-free status after additional systemic therapy before randomization.

Cohort B Only

• Did not achieve tumor-free status at the initial response evaluation because of residual non-muscle-invasive disease.
• Subsequently underwent complete TURBT/resection of residual disease followed by additional systemic therapy.
• Achieved tumor-free status at the second response evaluation before randomization.

Exclusion Criteria

• Has muscle-invasive bladder cancer (≥T2), locally advanced unresectable disease, nodal disease, or distant metastasis.
• Has concurrent upper tract urothelial carcinoma.
• Has persistent visible tumor, positive bladder pathology, positive urine cytology, or positive utDNA before randomization.
• Has received prior systemic immunotherapy for metastatic urothelial carcinoma.
• Has active autoimmune disease requiring systemic treatment.
• Is receiving systemic immunosuppressive therapy.
• Has uncontrolled infection requiring systemic therapy.
• Has another active malignancy requiring systemic treatment.
• Has known active hepatitis B, hepatitis C, human immunodeficiency virus infection, or active tuberculosis.
• Has pregnancy or breastfeeding.
• Has any medical or psychiatric condition that, in the investigator's judgment, would interfere with study participation or interpretation of results.