EX-527 is an inhibitor of sirtuin 1 (SIRT1); sirtuins are considered class III histone deacetylases (HDACs). EX-527 binds the NAD+ site of sirtuin 1, stabilizing a closed conformation. EX-527 exhibits immunostimulatory and anti-inflammatory activities. In animal models of autoimmune colitis and inflammatory bowel disease, EX-527 increases the number of Foxp3+ Treg cells and prevents weight loss. In animal models of polycystic kidney disease, this compound delays renal cyst formation and growth. Additionally, EX-527 improves myocardial histology and increases the number of Foxp3+ Treg cells in animal models of transplant surgery, prolonging allograft survival.