An Exploratory Phase 2, Randomised, Double-blind, Placebo-controlled Study to Evaluate the Treatment Effect of Pentosan Polysulfate Sodium Compared with Placebo on Synovial Fluid Biomarkers in Participants with Knee Osteoarthritis Pain

Knee osteoarthritis is an extremely common condition — the gradual breakdown of the cartilage in the knee joint, causing pain, stiffness, and reduced function. Inflammation within the joint fluid (synovial fluid) is a key driver of both pain and disease progression. Current treatments manage symptoms but do not slow the underlying joint damage. This Phase 2 trial is evaluating Pentosan Polysulfate Sodium (PPS), a drug originally developed for a bladder condition, which appears to have both anti-inflammatory and cartilage-protecting properties. The study specifically examines changes in biomarkers (biological signals) found in the knee's joint fluid before and after treatment, to better understand how PPS works and whether it reduces inflammation and cartilage breakdown at a biological level. Adults aged 18 or older with a clinical and radiological diagnosis of knee osteoarthritis, BMI between 18 and 35, and at least 6 months of knee pain are potentially eligible. A range of blood-clotting conditions, active stomach ulcers, or prior use of PPS may disqualify participation. Additional inclusion and exclusion criteria apply. The study involves knee joint fluid sampling (aspiration) at the start and end of the treatment period.