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Omeros’ Lead MASP-3 Inhibitor OMS906 Demonstrates Efficacy in Paroxysmal Nocturnal Hemoglobinuria Model


Omeros Corporation (OMER) today announced results from its OMS906 complement program. OMS906 is Omeros’ lead antibody targeting mannan-binding lectin-associated serine protease-3 (MASP-3). In a well-established animal model associated with paroxysmal nocturnal hemoglobinuria (PNH), OMS906 significantly improved the survival of red blood cells when compared to control-treated animals and to animals treated with a complement component 5 (C5) inhibitor.

Paroxysmal nocturnal hemoglobinuria is a rare, acquired, life-threatening disease of the blood. The hallmarks of PNH are defective red blood cells that result in their premature destruction by the complement system (part of a person’s own immune system), repeated blood clots and bone marrow dysfunction. The only drug approved by the U.S. Food and Drug Administration and corresponding international regulatory agencies for the treatment of PNH is eculizumab, a C5 inhibitor. Paroxysmal nocturnal hemoglobinuria is driven by the alternative pathway of complement (APC), and MASP-3 is essential for the activation of the APC.

OMS906, a MASP-3 inhibitor, has been demonstrated to block the activation of the APC. In a well-established animal model associated with PNH, OMS906 protected PNH-like red blood cells (RBCs) significantly better than did C5 inhibition. In the group treated with a potent C5 inhibitor, 80-percent destruction of PNH-like RBCs occurred at less than one day but was delayed until approximately 8 days in the OMS906-treated group (p = 0.008). In addition, overall in vivo survival of PNH-like RBCs, determined by area-under-the-curve analysis, was approximately 4-fold greater in the OMS906-treated group than that treated with the C5 inhibitor (p = 0.029).

“These data further demonstrate that MASP-3 inhibition, and specifically OMS906, blocks activation of the complement system’s alternative pathway,” said Sir Peter Lachmann, ScD FRCP FRCPath FRS FMedSci, Emeritus Sheila Joan Smith Professor of Immunology, University of Cambridge. “Paroxysmal nocturnal hemoglobinuria is one of many diseases and disorders involving the alternative pathway, and this study showed that OMS906 provided a profound improvement over C5 inhibition in survival of red blood cells. This is likely due to the ability of OMS906...