Omeros Corporation, a clinical-stage biopharmaceutical company, has received orphan drug designation for its OMS721, lead human monoclonal antibody targeting mannan-binding lectin-associated serine protease-2 (MASP-2), from the US Food and Drug Administration (FDA) for prevention of complement-mediated thrombotic microangiopathies (TMAs).

TMAs, including atypical hemolytic uremic syndrome and thrombotic thrombocytopenic purpura, are a family of rare, debilitating and life-threatening disorders characterized by multiple thrombi (clots) in the microcirculation of the body's organs, most commonly the kidney and brain. The lectin pathway, one of the principal complement activation pathways in the immune system, is thought to play a central role in the development of TMAs. By targeting MASP-2, OMS721 specifically blocks the lectin pathway. Omeros controls the worldwide rights to MASP-2 and all therapeutics targeting MASP-2.

Omeros is completing a phase I study to assess the safety and pharmacokinetics of OMS721. As previously announced, at the highest subcutaneous dose administered to date in this study, OMS721 achieved serum concentrations that resulted in a high degree of inhibition of lectin pathway activation. The serum concentrations seen in the phase I subjects are similar to those associated with efficacy in animal models of diseases, including TMA, linked to the lectin pathway. Omeros expects to report additional phase I clinical data in early 2014. The phase I clinical programme evaluating OMS721 for the prevention of complement-mediated TMAs is expected to begin in the first quarter of 2014.

"We are pleased that the FDA has granted orphan drug designation for OMS721. The designation should accelerate the development of OMS721 and, given the limitations of current treatments for TMAs, we look forward to initiating our phase II clinical program next quarter," stated Gregory A Demopulos, MD, chairman and chief executive officer of Omeros. "The remainder of this year and the first part of 2014 promise to be exciting times across other Omeros programs as well. This month we will initiate our OMS824 phase II clinical programme in Huntington's disease – earlier granted orphan drug designation by the FDA – and could also report phase IIa data for OMS824 in schizophrenia. We then look to the potential marketing approval of Omidria, its launch completing our transition to a commercial company."

Omeros controls the worldwide rights to MASP-2 and all therapeutics targeting MASP-2, a novel pro-inflammatory protein target involved in activation of the complement system, which is an important component of the immune system. The complement system plays a role in the inflammatory response and becomes activated as a result of tissue damage or microbial infection. MASP-2 appears to be unique to, and required for the function of, one of the principal complement activation pathways, known as the lectin pathway. Importantly, inhibition of MASP-2 does not appear to interfere with the antibody-dependent classical complement activation pathway, which is a critical component of the acquired immune response to infection, and its abnormal function is associated with a wide range of autoimmune disorders.

MASP-2 is generated by the liver and is then released into the circulation. Adult humans who are genetically deficient in one of the proteins that activate MASP-2 do not appear to be detrimentally affected by the deficiency. Therefore, Omeros believes that it may be possible to deliver MASP-2 antibodies systemically and OMS721, its lead MASP-2 antibody, is designed to be self-administered by subcutaneous injection.

Omeros also believes that it has identified the proteins that activate the complement system's alternative pathway in humans, which is linked to a wide range of immune-related disorders. In addition to its lectin pathway inhibitors, the Company is advancing the development of antibodies that would block activation of the alternative pathway alone or in combination with the lectin pathway.

Omeros is committed to discovering, developing and commercializing small-molecule and protein therapeutics targeting inflammation, coagulopathies and disorders of the central nervous system.