Purity >98% by HPLC. Physiologically active metabolite of the immunomodulatory agent Leflunomide. It inhibits dihydroorotate dehydrogenase (Ki = 2.7 μM) and has antiproliferative activity. It also blocks the de novo synthesis of Pyrimidines, thus preventing the proliferation of activated T cells. A77 1726 inhibits anti-CD3/CD28-induced Cytokine production in PBMC cells (IC50 = 21-27 μg/ml). It is investigated as a medication for multiple sclerosis (MS).