What Are Fc Fusion Proteins?

Fc fusion proteins are biologically engineered molecules that combine the Fc (fragment crystallizable) region of an antibody with a functional protein—such as a cytokine, receptor, or ligand trap. This fusion improves the drug's stability and half-life in the human body, enabling longer dosing intervals and enhanced therapeutic action.

The Fc portion allows the molecule to interact with the neonatal Fc receptor (FcRn), which recycles the drug and reduces its degradation, thereby maintaining activity for extended periods. The result is a class of biologics that is not only potent but also more convenient for patients.