Achillion Pharmaceuticals, Inc., a biopharmaceutical company, discovers, develops, and commercializes small molecule drug therapies for infectious diseases and immune system disorders in the United States and internationally. Its drug candidates for treating chronic hepatitis C virus (HCV) infection comprise Odalasvir, a NS5A inhibitor, which has completed Phase IIa clinical trials; ACH-3422, a NS5B nucleotide polymerase inhibitor; and Sovaprevir, a NS3 protease inhibitor that has completed Phase II clinical trial. The company is also developing ACH-4471, a complement factor D inhibitor, which is in Phase I clinical trial to treat patients with paroxysmal nocturnal hemoglobinuria and C3G, a disease resulting from alternative pathway over-activation; and other factor D inhibitors. It has a license and development agreement with Ora, Inc. for the development and commercialization of ACH-702, a drug candidate that is delivered topically or locally; and collaboration arrangement with Janssen Pharmaceuticals Inc. to develop and commercialize antiviral drug candidates for treating HCV infection. The company was founded in 1998 and is headquartered in New Haven, Connecticut.