Isatoribine : Anti-hepatitis C virus drug TLR7 receptor agonist

Current therapeutic intervention for hepatitis C virus (HCV) infection is unsatisfactory, and due to the virus's high genetic heterogeneity, it is important that new therapies target a broad range of viral genotypes. A novel immunomodulator, isatoribine, is currently undergoing phase Ib development for HCV. This toll-like receptor 7 (TLR7) agonist has demonstrated potent immunogenicity in vitro and in vivo, providing significant protection against a broad spectrum of viral challenges. Interim clinical data in patients with chronic HCV have indicated that daily i.v. doses of 800 mg significantly reduce plasma HCV RNA levels, modulate interferon-responsive genes and are effective against genotypes 1 and 3. The outcome of further studies using oral prodrugs of isatoribine, namely ANA-975 and ANA-971, will also be discussed. These novel candidates for HCV represent promising new therapeutic strategies.