Efficacy and Safety of Intravesical Instillation of KRP-116D (50% Dimethyl Sulfoxide Solution) for Interstitial Cystitis/bladder Pain Syndrome in Japanese Patients: A Multicenter, Randomized, Double-blind, Placebo-controlled, Clinical Study

Objective: To evaluate the efficacy and safety of intravesical KRP-116D, 50% dimethyl sulfoxide solution compared with placebo, in interstitial cystitis/bladder pain syndrome patients.

Methods: Japanese interstitial cystitis/bladder pain syndrome patients with an O'Leary-Sant Interstitial Cystitis Symptom Index score of ≥9, who exhibited the bladder-centric phenotype of interstitial cystitis/bladder pain syndrome diagnosed by cystoscopy and bladder-derived pain, were enrolled. Patients were allocated to receive either KRP-116D (n = 49) or placebo (n = 47). The study drug was intravesically administered every 2 weeks for 12 weeks.

Results: For the primary endpoint, the change in the mean O'Leary-Sant Interstitial Cystitis Symptom Index score from baseline to week 12 was -5.2 in the KRP-116D group and -3.4 in the placebo group. The estimated difference between the KRP-116D and placebo groups was -1.8 (95% confidence interval -3.3, -0.3; P = 0.0188). Statistically significant improvements for KRP-116D were also observed in the secondary endpoints including O'Leary-Sant Interstitial Cystitis Problem Index score, micturition episodes/24 h, voided volume/micturition, maximum voided volume/micturition, numerical rating scale score for bladder pain, and global response assessment score. The adverse drug reactions were mild to moderate, and manageable.

Conclusions: This first randomized, double-blind, placebo-controlled trial shows that KRP-116D improves symptoms, voiding parameters, and global response assessment, compared with placebo, and has a well-tolerated safety profile in interstitial cystitis/bladder pain syndrome patients with the bladder-centric phenotype.