Adstiladrin (Nadofaragene Firadenovec) for BCG-Unresponsive NMIBC: Current Evidence
Dosing and Administration
Adstiladrin is administered as 75 mL intravesical instillations (3 × 10¹¹ viral particles/mL) once every 3 months for up to 12 months (4 total doses), with the option to continue treatment every 3 months beyond 12 months in patients without high-grade recurrence. 1
The medication must be retained in the bladder for 1 hour, with patients repositioning approximately every 15 minutes to maximize bladder surface exposure. 1
Efficacy Outcomes
Complete Response Rates
The pivotal phase 3 trial (CS-003) demonstrated the following results in 98 evaluable patients with BCG-unresponsive NMIBC with carcinoma in situ (CIS) ± papillary tumors: 1, 2
- Complete response (CR) rate at 3 months: 51% (95% CI: 41-61%) 1
- Of those achieving CR, 46% maintained response ≥12 months 1
- Median duration of response: 9.7 months (range 3-52+ months) 1
Long-Term Outcomes (5-Year Follow-Up)
The most recent 5-year follow-up data from the phase 3 trial provides critical long-term efficacy information: 3
- High-grade recurrence-free survival at 57 months: 13% (95% CI: 6.9-21.5%) for CIS cohort 3
- Cystectomy-free survival at 60 months: 49% overall (43% for CIS cohort, 59% for Ta/T1 cohort) 3
- Overall survival at 60 months: 80% (76% for CIS, 86% for Ta/T1) 3
- Only 5 patients (3.3%) experienced clinical progression to muscle-invasive disease 3
These data demonstrate that nearly half of patients avoided cystectomy at 5 years, which is clinically meaningful for quality of life and morbidity reduction. 3
Treatment Duration
- Median number of instillations: 2 (range 1-5) 1
- 27% of patients received ≥5 instillations 3
- 7.6% received treatment for ≥57 months 3
Guideline Recommendations
AUA/SUO Guidelines (2024)
The AUA/SUO guidelines state that nadofaragene firadenovec received FDA approval in December 2022 for patients with high-risk BCG-unresponsive NMIBC with CIS with or without papillary tumors. 4 The guidelines report a 53.4% complete response rate at 3 months and note that 45.5% of complete responders maintained response at 12 months. 4
NCCN Guidelines (2024)
NCCN considers nadofaragene firadenovec as an option for select patients with BCG-unresponsive or BCG-intolerant, high-risk NMIBC. 4 Specifically:
- Category 2A recommendation for BCG-unresponsive NMIBC with CIS (with or without papillary tumors) 4
- The 24-month data showed 19.4% of patients remained free of high-grade recurrence, with cystectomy-free survival of 64.6% and overall survival of 94.4% 4
Safety Profile
Common Adverse Reactions (>10%)
The most frequent adverse reactions from the phase 3 trial include: 1, 2
- Instillation site discharge (33%)
- Fatigue (24%)
- Bladder spasm (20-21%)
- Micturition urgency (19%)
- Hematuria (17%)
- Dysuria (16%)
- Chills (15%)
- Pyrexia (16%)
Serious Adverse Events
- Serious adverse reactions occurred in 11% of patients 1
- Only 1.9% discontinued treatment due to adverse reactions 1
- Micturition urgency was the most common grade 3-4 drug-related event (1% of patients) 1, 5
- No treatment-related deaths occurred 5
Management of Bladder Spasms
Recent evidence suggests rectal diazepam (10 mg) pretreatment significantly reduces bladder spasms and improves medication retention. 6 This intervention resulted in:
- 25% absolute risk reduction in retention failure (4% vs 29%) 6
- 24% absolute reduction in bladder spasm incidence (32% vs 56%) 6
- Patients without medication leakage had lower 3-month recurrence rates (18% vs 38%) 6
Critical Safety Warnings
Risk of Delayed Cystectomy
The FDA label includes a boxed warning that delaying cystectomy in patients with BCG-unresponsive CIS could lead to muscle-invasive or metastatic bladder cancer, which can be lethal. 1 Key data:
- 14% of patients who underwent subsequent cystectomy had muscle-invasive (T2 or greater) disease 1
- Median time from CIS persistence/recurrence to cystectomy was 235 days (range 38-582 days) 1
- If patients do not achieve complete response after 3 months or if CIS recurs, cystectomy should be considered 1
Immunocompromised Patients
Immunocompromised persons should not come into contact with Adstiladrin due to risk of disseminated adenovirus infection. 1
Predictive Biomarkers
Anti-Adenovirus Antibodies
Post-treatment anti-adenovirus antibody levels can predict treatment durability: 7
- Peak post-treatment titers >800 were found in 89% of responders vs 59% of nonresponders (p=0.001) 7
- Combination of peak titers >800 and fold change >8 had 82% specificity and 73% positive predictive value 7
- Baseline titers did not predict response 7
Urinary Tumor DNA (utDNA)
Minimal residual disease detection using utDNA profiling at 3 months post-treatment provides prognostic information: 8
- Negative MRD at 3 months: 100% recurrence-free survival 8
- Positive MRD at 3 months: 38% recurrence-free survival (p=0.038) 8
Clinical Context and Positioning
Adstiladrin represents the first FDA-approved adenoviral vector-based gene therapy and the first approved gene therapy for bladder cancer. 2 It provides a bladder-sparing alternative for patients with BCG-unresponsive NMIBC who are ineligible for or decline cystectomy. 4, 9
The AUA/SUO guidelines emphasize that optimal management for BCG-unresponsive disease remains to be established, and enrollment in clinical trials should be prioritized. 4 However, nadofaragene firadenovec now represents a standard treatment option based on FDA approval and guideline endorsement. 4
Key Clinical Pearls
- The quarterly dosing schedule (every 3 months) is critical and differs from traditional weekly BCG schedules 1
- Consider rectal diazepam pretreatment to optimize medication retention and reduce bladder spasms 6
- Monitor closely for treatment failure at 3 months; persistent or recurrent CIS warrants cystectomy discussion 1
- The 5-year data showing 49% cystectomy-free survival and only 3.3% progression to muscle-invasive disease supports this as a viable bladder-preservation strategy 3