On 26 July 2018, Omeros Corporation announced that the European Medicines Agency's (EMA's) Committee for Orphan Medicinal Products (COMP) have positively recommended the lead human monoclonal antibody named OMS721 for stem cell transplantation therapy.  

This antibody targets the effector enzyme named mannan-binding lectin-associated serine protease-2 (MASP-2). Around three OMS721 phase 3 clinical programs are continuing across immunoglobulin A (IgA) nephropathy, hematopoietic stem cell transplant-associated thrombotic microangiopathy (TMA), and atypical hemolytic uremic syndrome (aHUS).

This positive declaration will soon be adopted by the European Commission in August. The Orphan Drug Designation in Europe will be made available to the companies in order to treat chronically debilitating conditions. This designation allows for regulatory and financial incentives including 10 years of marketing exclusivity in the European Union after product approval, lessened EMA advisory, inspection and filing fees pre- and post-approval, and guaranteed access to centralized marketing authorization valid in EU member states and European Economic Area countries.

At first, the U.S. Food and Drug Administration granted orphan designation to OMS721 in order to prevent complement-mediated TMA and finally granted therapeutic designation to OMS721 for the stem cell transplant therapy. Still, the discussions are going on with U.S. and European regulators regarding OMS721 approval for "high-risk" stem cell transplant-associated TMA treatment.