Single chain Fc-dimer-human growth hormone fusion protein for improved drug delivery.

Fc fusion protein technology has been successfully used to generate long-acting forms of several protein therapeutics. In this study, a novel Fc-based drug carrier, single chain Fc-dimer (sc(Fc)2), was designed to contain two Fc domains recombinantly linked via a flexible linker. Since the Fc dimeric structure is maintained through the flexible linker, the hinge region was omitted to further stabilize it against proteolysis and reduce FcγR-related effector functions. The resultant sc(Fc)2 candidate preserved the neonatal Fc receptor (FcRn) binding. sc(Fc)2-mediated delivery was then evaluated using a therapeutic protein with a short plasma half-life, human growth hormone (hGH), as the protein drug cargo. This novel carrier protein showed a prolonged in vivo half-life and increased hGH-mediated bioactivity compared to the traditional Fc-based drug carrier. sc(Fc)2 technology has the potential to greatly advance and expand the use of Fc-technology for improving the pharmacokinetics and bioactivity of protein therapeutics.