Evaluating the safety and potential activity of URO‐902 (hMaxi‐K) gene transfer by intravesical instillation or direct injection into the bladder wall in female participants with idiopathic (non‐neurogenic) overactive bladder syndrome and detrusor overactivity from two double‐blind, imbalanced, placebo‐controlled randomized phase 1 trials

AIMS: Two phase 1 trials were performed in healthy women with the overactive bladder (OAB) syndrome and urodynamically demonstrated detrusor overactivity (DO), with the aim to demonstrate the safety and potential efficacy of URO-902, which comprises a gene therapy plasmid vector expressing the human big potassium channel alpha subunit. METHODS: ION-02 (intravesical instillation) and ION-03 (direct injection) were double-blind, placebo-controlled, multicenter studies without overlap in enrollment between studies. Active doses were administered and evaluated sequentially (lowest dose first) for safety. ION-02 participants received either 5000 microg or 10 000 microg URO-902, or placebo. ION-03 participants received either 16 000 or 24 000 microg URO-902, or placebo, injected directly into the bladder wall using cystoscopy. Primary outcome variables were safety parameters occurring subsequent to URO-902 administration; secondary efficacy variables also were evaluated. RESULTS: Among the safety outcomes, there were no dose-limiting toxicities or significant adverse events (AEs) preventing dose escalation during either trial, and no participants withdrew due to AEs. For efficacy, in ION-02 (N = 21), involuntary detrusor contractions on urodynamics at 24 weeks in patients receiving URO-902 (P < .0508 vs placebo) and mean urgency incontinence episodes in the 5000 microg group (P = .0812 vs placebo) each showed a downward trend. In ION-03 (N = 13), significant reduction versus placebo in urgency episodes (16 000 microg, P = .036; 24 000 microg, P = .046) and number of voids (16 000 microg, -2.16, P = .044; 24 000 microg, -2.73, P = .047) were observed 1 week after injection. CONCLUSION: Promising safety and efficacy results in these preliminary phase 1 studies suggest gene transfer may be a promising therapy for OAB/DO, warranting further investigation.