This study evaluates the effects of two doses of oral AQX-1125 on bladder pain and other urinary symptoms in subjects with interstitial cystitis/bladder pain syndrome. Participants will receive either 100 mg AQX-1125, 200 mg AQX-1125 or placebo for the first 12 weeks of the study. After 12 weeks, all participants will receive either 100 mg or 200 mg AQX-1125 for 52 weeks.

This multi-center Phase 3 trial includes a randomized, double-blind, placebo-controlled, parallel-group, treatment phase to evaluate the efficacy and safety of 2 doses of oral AQX-1125 in up to 600 subjects with interstitial cystitis/bladder pain syndrome.

The primary objective of this study is to evaluate the effect of 12 weeks of treatment of AQX-1125 (100 mg or 200 mg) administered once daily compared to placebo on the change from Baseline to Week 12 in maximum daily bladder pain using a standardized 11-point numerical rating scale pain score recorded daily by electronic diary (e-diary).

The 12-week Treatment Period is followed by an Extension Period of 52 weeks. Randomization and start of dosing occurs at Baseline and is followed by visits at Week 6 and Week 12. At the end of Week 12, subjects will be randomized into the 52-week Extension Period. Subjects on active treatment during the Treatment Period will continue on that same dose for the Extension Period, while subjects receiving placebo during the Treatment Period will be randomized to one of the active doses of 100 mg or 200 mg AQX-1125 for 52 weeks.

Inclusion Criteria:

• Be male or female, ≥18 and ≤80 years of age who have had symptoms of bladder pain in addition to urinary urgency and/or urinary frequency for more than 6 months
• Have had a clinical diagnosis, or history consistent with the diagnosis, of interstitial cystitis/bladder pain syndrome for >3 months but ≤20 years
• Must be capable of voiding independently
• Have undergone a cystoscopy within the last 36 months prior to Baseline
• Women of child bearing potential must have a negative pregnancy test, be non-lactating and agree to avoid pregnancy and use a highly effective method of contraception with one additional barrier method of contraception from screening until at least 28 days after the last dose of study drug has been taken
• Men must use a condom for sexual intercourse from screening until at least 90 days after last dose of study drug has been taken, unless they have been surgically sterilized (vasectomy)

Exclusion Criteria

• Have had a urinary tract infection (UTI) including bacterial cystitis within the past 30 days
• Microscopic hematuria that has not been adequately evaluated as per local standard of care
• Have a history of chronic substance abuse, dependency or abuse of opiates, or other narcotics within the last 2 years
• History of previous procedure(s) (augmentation cystoplasty, cystectomy, cytolysis, botulinum toxin or bladder catheterization) that has significantly affected bladder function
• History of cyclophosphamide or chemical cystitis, urinary tuberculosis or radiation cystitis
• Women: History of bladder tumors; uterine, cervical, vaginal or urethral cancer
• Men: History of prostate surgery (transurethral resection of the prostate [TURP], transurethral resection tumor [TURT], transurethral incision of the prostate [TUIP], transurethral needle ablation [TUNA] etc.), a history of prostate cancer or currently being treated for chronic bacterial prostatitis
• Major surgery within 3 months prior to Screening