Pulmonary delivery of an erythropoietin Fc fusion protein in non-human primates through an immunoglobulin transport pathway

Proc Natl Acad Sci U S A. 2004 Jun 29;101(26):9763-8. doi: 10.1073/pnas.0403235101. Epub 2004 Jun 21.


Administration of therapeutic proteins by methods other than injection is limited, in part, by inefficient penetration of epithelial barriers. Therefore, unique approaches to breaching these barriers are needed. The neonatal constant region fragment (Fc) receptor (FcRn), which is responsible for IgG transport across the intestinal epithelium in newborn rodents, is expressed in epithelial cells in adult humans and non-human primates. Here we show that FcRn-mediated transport is functional in the lung of non-human primates and that this transport system can be used to deliver erythropoietin (Epo) when it is conjugated to the Fc domain of IgG1. FcRn-dependent absorption was more efficient when the EpoFc fusion protein was deposited predominantly in the upper and central airways of the lung, where epithelial expression of FcRn was most prominently detected. To optimize fusion protein absorption in the lung, we created a recombinant "monomeric-Epo" Fc fusion protein comprised of a single molecule of Epo conjugated to a dimeric Fc. This fusion protein exhibited enhanced pharmacokinetic and pharmacodynamic properties. The bioavailability of the EpoFc monomer when delivered through the lung was approximately equal to that reported for unconjugated Epo delivered s.c. in humans. These studies show that FcRn can be harnessed to noninvasively deliver bioactive proteins into the systemic circulation in therapeutic quantities.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Absorption
  • Animals
  • Dimerization
  • Drug Delivery Systems
  • Erythropoietin / chemistry
  • Erythropoietin / genetics
  • Erythropoietin / metabolism*
  • Erythropoietin / pharmacokinetics*
  • Humans
  • Immunoglobulin Fc Fragments / chemistry
  • Immunoglobulin Fc Fragments / genetics
  • Immunoglobulin Fc Fragments / metabolism*
  • Immunoglobulin G / chemistry
  • Immunoglobulin G / genetics
  • Immunoglobulin G / metabolism
  • Lung / cytology
  • Lung / metabolism*
  • Macaca fascicularis / metabolism*
  • Protein Binding
  • Protein Transport
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism*
  • Recombinant Fusion Proteins / pharmacokinetics*
  • Respiration
  • Solubility


  • Immunoglobulin Fc Fragments
  • Immunoglobulin G
  • Recombinant Fusion Proteins
  • Erythropoietin