A77 1726, also known as teriflunomide, is the active metabolite of leflunomide. This compound has demonstrated antiinflammatory, antiproliferative, and immunosuppressive effects. A77 1726 has been shown to inhibit the proliferation of multiple mammalian cell lines in vitro, has demonstrated inhibition of Cox-2, dendritic cell function, DHODH (dihydroorotate dehydrogenase), and blocks TNF-dependent nuclear factor-κ B activation and gene expression. DHODH is an enzyme involved in the de novo synthesis of pyrimidine nucleotides, and its inhibition is thoμght to result in the antiproliferative effects on rapidly dividing cells, such as T-cells, observed by this compound. A77 1726, also known as teriflunomide, is the active metabolite of leflunomide. This compound has demonstrated antiinflammatory, antiproliferative, and immunosuppressive effects. A77 1726 has been shown to inhibit the proliferation of multiple mammalian cell lines in vitro, has demonstrated inhibition of Cox-2, dendritic cell function, DHODH (dihydroorotate dehydrogenase), and blocks TNF-dependent nuclear factor-κ B activation and gene expression. DHODH is an enzyme involved in the de novo synthesis of pyrimidine nucleotides, and its inhibition is thought to result in the antiproliferative effects on rapidly dividing cells, such as T-cells, observed by this compound.