SEATTLE, April 17, 2013 /PRNewswire/ -- Omeros Corporation (NASDAQ: OMER) today announced that it has filed an Application for Orphan Drug Designation with the U.S. Food and Drug Administration (FDA) for OMS721, the lead human monoclonal antibody in Omeros' mannan-binding lectin-associated serine protease-2 (MASP‑2) program, for use in the treatment of atypical hemolytic uremic syndrome (aHUS). As Omeros previously announced, based on positive preclinical data in thrombotic microangiopathy (TMA), the first indication planned for OMS721 clinical trials is aHUS, a rare but life-threatening form of TMA. Orphan drug designation is granted to treatments that are expected to provide significant therapeutic advantage over existing treatments and that target conditions affecting 200,000 or fewer U.S. patients per year. Orphan-designated drugs are eligible for incentives such as a faster approval process and additional market exclusivity. Omeros controls the worldwide rights to MASP-2 and all therapeutics targeting MASP-2, a novel pro-inflammatory protein involved in activation of the complement system – an important component of the immune system. The complement system plays a role in the inflammatory response to tissue damage or microbial infection. OMS721 selectively inhibits MASP-2, blocking the lectin pathway of the complement system while leaving intact the classical pathway, which represents the acquired immune response to infection. Soliris ® (eculizumab), which received orphan drug status for aHUS and is the only currently approved therapy for that indication, inhibits microbial killing by the classical pathway, increasing the risk of infection for the patient. By targeting only the lectin pathway and leaving the classical pathway intact, OMS721 should not have this increased infection risk. In addition, Soliris requires a 20-minute to two-hour intravenous infusion in a medical facility, while OMS721 is designed to be self-administered by subcutaneous injection, which would be more convenient for patients. "We believe that OMS721 meets the criteria for orphan drug designation, representing a significant therapeutic advance over currently available treatments for aHUS," stated Gregory A. Demopulos, M.D., chairman and chief executive officer of Omeros. "We plan to file for the same designation in Europe, and we remain on track to begin clinical trials early this summer. The potential indications for OMS721 span a wide range of attractive markets in both orphan and highly prevalent diseases, and we are excited to evaluate its efficacy in patients." About Orphan Drug Status Orphan drug designation is granted by the FDA's Office of Orphan Products Development for treatments that are expected to provide significant therapeutic advantage over existing treatments and that target conditions affecting 200,000 or fewer U.S. patients per year. Orphan drug designation qualifies a company for several benefits under the Orphan Drug Act of 1983. The benefits apply across all stages of drug development and include accelerated approval process; seven years of market exclusivity following marketing approval; tax credits on U.S. clinical trials; eligibility for orphan drug grants; and waiver of certain administrative fees.