Objective: To assess the safety and effectiveness of AD32, a doxorubicin analogue with little systemic exposure when administered intravesically, in patients with recurrent or refractory superficial urothelial carcinoma (formerly called transitional cell carcinoma [TCC]), or carcinoma in situ (CIS), who have failed prior BCG-based immunotherapy.
Methods: Eligible patients received six weekly doses (800 mg) of intravesical AD32 and were evaluated at 12-week intervals for 24 months or until date of worsening disease. Primary analysis was the proportion of all patients recurrence-free at 12 months. Treatment-related and GU-specific toxicities were also examined. All participating institutions submitted the protocol for Institutional Review Board (IRB) approval.
Results: The study was halted due to unavailability of study drug after accrual of 48 of a planned 64 patients; 42 were included in the analysis. Of these, 28 (67%) were still alive after median follow-up of 61.1 months. Of 21 TCC patients, 18 (85.7%) experienced disease recurrence (median time to recurrence, 5.3 months). Of the 5 CIS patients with complete response (CR), 3 (60%) experienced disease recurrence; (median time to recurrence, 37.3 months). Recurrence-free rates at 12 and 24 months were 20% (90% CI, 7.8%, 36.1%) and 15% (90 CI, 4.9%, 30.2%), respectively, for patients with TCC and 80% (90% CI, 31.4%, 95.8%) at both intervals for CIS patients with CR. Infection was the most common treatment-related toxicity; no grade 4 or higher toxicity was observed. The most common GU-specific toxicity was increased frequency/urgency.
Conclusions: AD32 is safe and active for treatment of recurrent or refractory superficial bladder carcinoma. The agent awaits more complete characterization when drug production problems can be solved.