Omeros receives exclusive license for new series of antifibrinolytic agents

Omeros Corporation (Nasdaq: OMER) today announced that it has obtained an exclusive license from The Regents of the University of California to a new series of antifibrinolytic agents. These optimized agents represent a significant potential advance in the control of surgical and traumatic bleeding.

"This is a good opportunity for Omeros and represents a potential life-saving treatment for patients. With the withdrawal of Trasylol® from the market in 2008, there is an immediate need for a safe and effective antifibrinolytic," stated Gregory A. Demopulos, M.D., chairman and chief executive officer of Omeros. "The ex vivo human and in vivo animal efficacy data look strong, and the regulatory pathway is well-defined. We have begun IND-enabling activities and are working to advance the program quickly to the clinic."

Excessive bleeding during cardiac surgery is known to increase overall morbidity and mortality. In an attempt to control this bleeding, patients undergoing cardiac and other extensive surgery often receive antifibrinolytic compounds. Until its permanent withdrawal from the market in 2008, the antifibrinolytic Trasylol® (aprotinin) had been shown in a number of studies to be more effective at reducing blood loss than the other two commonly used agents, tranexamic acid (TXA) and epsilon aminocaproic acid (EACA). Though effective, Trasylol® had a number of limitations. It was a bovine protein that was associated with anaphylactic reactions. Further, Trasylol® was non-selective and inhibited many proteins in addition to plasmin, including Factor XIa and kallikrein, important regulators of the coagulation cascade. Trasylol® was permanently withdrawn from the market after its use was found to be associated with increased mortality. While the specific cause of this increase remains unknown, an often-cited explanation is lack of specificity of Trasylol®.

TXA and EACA are lysine analogs that function as competitive inhibitors of plasminogen activation and, at much higher concentrations, noncompetitive inhibitors of plasmin.  These agents are considered to be safer but less effective than Trasylol®. While TXA is approximately 10 times more potent than EACA, it is associated with a fourfold increase over EACA in the risk of seizures.  Further, a study demonstrated that patients administered TXA required more transfusion product than patients who were administered Trasylol®, resulting in significantly higher overall transfusion-related costs for patients treated with the less expensive, generic agent TXA.  

Omeros' proprietary antifibrinolytic agents are highly selective inhibitors of plasmin, the enzyme responsible for fibrinolysis and dissolving blood clots, while avoiding significant inhibition of Factor XIa and kallikrein. This selectivity could provide more effective bleeding control with fewer side effects. Additionally, as a human protein derivative, these agents are expected to reduce the potential for immunological side effects.

Omeros is developing a series of novel antifibrinolytic agents for the control of blood loss during surgery or resulting from trauma. Omeros' agents are designed to selectively inhibit plasmin, the enzyme responsible for fibrinolysis and dissolving blood clots, while avoiding significant inhibition of Factor XIa and kallikrein, important regulators of the coagulation cascade. These agents could provide a superior replacement for the antifibrinolytic agents Trasylol® (aprotinin), tranexamic acid and epsilon aminocaproic acid. The selectivity of Omeros' agents may provide more effective bleeding control with fewer side effects. Additionally, as a human protein derivative, these agents are expected to reduce the potential for immunological side effects. Worldwide revenues for Trasylol® (aprotinin), which was permanently withdrawn in 2008 after its use was found to be associated with increased mortality, peaked at $285 million in 2005.