Nomacopan inhibits both terminal complement activation and leukotriene B4, or LTB4.
It inhibits terminal complement activation by tightly binding to C5 and preventing its cleavage and activation by complement. It inhibits LTB4 by capturing the fatty acid within the body of the nomacopan protein. By preventing C5 activation of complement nomacopan can stop formation of the anaphylatoxin C5a which activates cells, including granulocytes and T and B cells, via two G protein coupled receptors, or GPCRs, and also prevents formation of the membrane attack complex, or MAC which activates cells including endothelial cells. C5a and the MAC cause and maintain a proinflammatory and prothrombotic state. LTB4 also activates cells via two separate GPCRs and can independently cause and maintain a proinflammatory state.
The importance of nomacopan’s dual inhibitory action is therefore twofold. First, it can prevent inflammatory and prothrombotic activities of two key pathways, and second, the pathways can be independently activated, for example terminal complement activation can be induced by IgG, IgM, carbohydrates and damage associated molecular patterns and LTB4 synthesis can be induced by engagement of Fc gamma receptors, cytokines, toll-like receptors, C5a and MAC.
Synchronous C5 and LTB4 Inhibition are believed to be involved in a wide range of indications.