Complement Factor B (CFB) mRNA

Class

Small interfering RNA (siRNA) therapeutic — gene-silencing agent

Pathway

Complement system, alternative pathway

Complement Factor B (CFB) is a plasma protein that is a required component of the alternative pathway of the complement system, an innate-immune surveillance network that tags pathogens and damaged tissue for destruction. Once cleaved by another enzyme, CFB forms part of C3 convertase, the molecular machine that amplifies complement activity, generates inflammatory fragments, and can seed the membrane attack complex that lyses cells. In several diseases, this amplification loop becomes chronically or excessively active, driving inflammation and tissue injury in the eye (as in degenerative retinal disease), the kidney (in glomerular disorders), and in blood disorders marked by destruction of red blood cells. Because CFB sits early in the amplification loop and is required for pathway function, reducing its abundance dampens the entire alternative pathway rather than blocking a single downstream effector. Small interfering RNA (siRNA) achieves this by binding the messenger RNA that encodes CFB and directing its degradation, lowering new protein synthesis at its source rather than neutralizing existing protein. This upstream strategy can produce sustained pathway suppression from infrequent dosing, offering an alternative to antibody or small-molecule approaches that must continuously engage circulating or tissue protein.