Safety and Efficacy of FE 999326 Administered Intravesically to Japanese Subjects With High-grade, BCG Unresponsive, Non-muscle Invasive Bladder Cancer (NMIBC)

Inclusion Criteria: * Have at entry, confirmed by a pathology report: 1. Carcinoma in situ (CIS) only 2. Ta/T1 high-grade disease with concomitant CIS or 3. Ta/T1 high-grade disease without concomitant CIS * Subjects who did not respond to BCG treatment and have a persistent high-grade recurrence within 12 months after BCG was initiated, and those who despite an initial complete response to BCG, relapse with CIS within 12 months of their last intravesical treatment with BCG or relapse with high-grade Ta/T1 NMIBC within 6 months of their last intravesical treatment with BCG. * Life expectancy \>2 years, in the opinion of the investigator * Eastern Cooperative Oncology Group (ECOG) status 2 or less * Absence of concomitant upper tract urothelial carcinoma or urothelial carcinoma within the prostatic urethra * Subjects with prostate cancer on active surveillance at low risk for progression, defined as prostate-specific antigen (PSA) \<10 ng/dL Exclusion Criteria: * Current or previous evidence of muscle invasive (muscularis propria) or metastatic disease presented at the screening visit. * Current systemic therapy for bladder cancer * Current or prior investigational treatment for BCG unresponsive NMIBC or any other investigational drug within 1 month prior to screening * Current or prior pelvic external beam radiotherapy within 5 years of entry * Use of other adenovirus vector medications, including COVID-19 vaccines, within 2 weeks before and after instillation * History of malignancy of other organ system within past 5 years, except treated basal cell carcinoma or squamous cell carcinoma of the skin and ≤pT2 upper tract urothelial carcinoma at least 24 months after nephroureterectomy. * Subjects who cannot hold instillation for 1 hour * Subjects who cannot tolerate intravesical dosing or intravesical surgical manipulation * Intravesical therapy within 8 weeks prior to beginning trial treatment, with the exception of: * Cytotoxic agents when administered as a single instillation immediately following a TURBT procedure * Previous intravesical BCG therapy * Systemic immunosuppressive therapy within 3 months prior to screening