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

Abstract

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 FcRnmediated 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 ''monomericEpo'' 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.

The conserved histidine 166 residue of the human neonatal Fc receptor heavy chain is critical for the pH‐dependent binding to albumin

“…The calculated affinities were derived to be approximately 8.5 AE 1.9 Â 10 -6 nM for the high-affinity and 156 AE 136 Â 10 -6 nM for the low-affinity population, respectively ( Table 2). The values obtained from the hIgG1-shFcRnWT-GST experiment agree well with those determined by others [19,23], and confirm that the immobilized GST-fused shFcRn format retained its functional binding activity and is useful for surface plasmon resonance analyses. Furthermore, the two mutants were investigated, and representative sensorgrams are shown in Fig.…”

Cross-species Binding Analyses of Mouse and Human Neonatal Fc Receptor Show Dramatic Differences in Immunoglobulin G and Albumin Binding

“…The SPR data were fitted to the heterogeneous ligand binding model. This model has been used extensively to evaluate the FcRn-IgG interaction when FcRn is immobilized (12,37,42,43). The K D values obtained were 8.5 Ϯ 0.5 ϫ 10 Ϫ9 M (K D1 ) and 450.0 Ϯ 65.0 ϫ 10 Ϫ9 M (K D2 ).…”

“…Knowledge of FcRn-IgG biology explains the prolonged halflife of IgG Fc-fused therapeutics (1,4,12,13). Understanding of the FcRn-IgG interaction at the atomic level has prompted the development of novel IgG-based therapeutics with point muta-tions in their Fc part that modulate serum half-life (14 -19).…”

In vivo animal models for drug delivery across the lung mucosal barrier☆

“…Ligands that specifically trigger an active uptake process in the alveolar cells may be preferable from a safety perspective to generalized permeation enhancement that allows the non-specific passage of other particles across the airways. [11,43].…”