SEATTLE, March 10, 2014 /PRNewswire/ -- Omeros Corporation (NASDAQ: OMER) today announced positive data using OMS721, the lead human monoclonal antibody in Omeros' mannan-binding lectin-associated serine protease-2 (MASP-2) program, in ex vivo studies of endothelial activation relevant to the pathophysiology of human atypical hemolytic uremic syndrome (aHUS), a form of thrombotic microangiopathy (TMA). TMAs 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. In February, Omeros reported positive results from its OMS721 Phase 1 clinical trial and, earlier this month, announced submission of an investigational new drug application to the U.S. Food and Drug Administration (FDA) to initiate a Phase 2 clinical trial in patients with TMA, including patients with aHUS. The data announced today resulted from studies conducted in support of the clinical evaluation of OMS721 by Prof. Giuseppe Remuzzi and colleagues Marina Noris and Miriam Galbusera at the Mario Negri Institute for Pharmacological Research in Bergamo, Italy, and the Clinical Research Center for Rare Diseases "Aldo e Cele Daccò" of the same Institute, a European center for collecting and studying TMA samples. The experimental model is based on the finding that serum samples from aHUS patients cause complement deposition and thrombus formation when incubated with human microvascular endothelial cells. The data reported today showed that OMS721 significantly inhibited complement deposition in the model using serum samples from aHUS patients obtained during the acute phase of disease (p<0.01) and during remission (p<0.001) compared to untreated controls. Experiments evaluating the effects of OMS721 on thrombus formation are planned. Prof. Remuzzi's laboratories have previously shown in this same model system that treatment with agents that block the complement factor C5 has a similar inhibitory effect on complement deposition. Eculizumab (Soliris ®) is an anti-C5 monoclonal antibody that is approved by the FDA and the European Medicines Agency to treat patients with aHUS. "The OMS721 data in serum samples from aHUS patients are of great interest even in relation to disease pathophysiology," stated Prof. Remuzzi, MD, FRCP, Research Coordinator at the Institute and international expert in the study of kidney disease who has contributed major advances to the understanding of the pathophysiology of hemolytic uremic syndrome.