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.