Phase 1 clinical trial evaluating safety, bioavailability, and gut microbiome with a combination of curcumin and ursolic acid in lipid enhanced capsules.

As screening strategies employ better biomarkers and genetics to identify individuals at an increased risk of prostate cancer, there are currently no chemotherapeutic prevention strategies. With any chemoprevention strategy, the population will be younger and healthier; therefore, they will be less tolerant of side effects. This study translated findings from screening a natural product library and pre-clinical evaluation of curcumin (CURC) in combination with ursolic acid (UA) in prostate cancer models. After manufacturing capsules for each compound, 18 subjects were enrolled. The study used a 3 × 3 phase 1 clinical trial to evaluate CURC (1200 mg/day) and UA (300 mg/day) alone and in combination over a 2-week period with endpoints of safety, bioavailability, and microbiome alterations. After enrolling six subjects in each arm, we found no grade 3 or 4 events and only minor changes in the safety laboratory values. In the pooled analysis of groups, we noted a statistically significant difference between median serum levels of UA when administered alone vs administered in the combination (2.7 ng/mL vs 43.8 ng/mL, p = 0.03). Individuals receiving the combination also had a favorable impact on gut microbiome status and a reduction in "microbiome score" predictive of prostate cancer risk.