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, which has completed Phase II clinical trial. The company is also developing ACH-4471, a complement factor D inhibitor that is in Phase I clinical trial to treat patients with paroxysmal nocturnal hemoglobinuria and one additional systemic ultra-rare disease; and other factor D inhibitors. It has a license and development agreement with Ora, Inc. for the development and commercialization of ACH-702, an antibacterial drug candidate that is delivered topically or locally; and license 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.