title: In vitro and in vivo evaluation of a non-carbohydrate targeting platform for lysosomal proteins.
abstract: Lysosomal storage diseases arise from a genetic loss-of-function defect in enzymes mediating key catabolic steps resulting in accumulation of substrate within the lysosome. Treatment of several of these disorders has been achieved by enzyme replacement therapy (ERT), in which a recombinant version of the defective enzyme is expressed in vitro and administered by infusion. However, in many cases the biodistribution of the administered protein does not match that of the accumulated substrate due to the glycosylation-mediated clearance of the enzymes from circulation, resulting in poor or absent substrate clearance from some tissues. To overcome this limitation, we have evaluated several peptide-based targeting motifs to redirect recombinant human alpha-galactosidase (rhalphaGal) to specific receptors. A reversible thiol-based PEGylation chemistry was developed to achieve multivalent peptide display with lysosomal release. In vitro, cell uptake was peptide dependent and independent of the normal mannose-6-phosphate receptor mediated pathway. Surprisingly, despite increased plasma half-life and decreased liver uptake, none of the peptide conjugates showed significantly altered biodistribution in alphaGal-knockout mice. This suggests that these peptide-based targeting motifs are unlikely to provide substantial therapeutic benefit likely due to the complexity of factors affecting PK and biodistribution.
authors.affiliation: Department of Therapeutic Protein Research, Genzyme Corporation, Framingham, MA 01701, USA. jstefano@genzyme.com
authors.forename: James E
authors.initials: JE
authors.lastname: Stefano
authors.forename: Lihui
authors.initials: L
authors.lastname: Hou
authors.forename: Denise
authors.initials: D
authors.lastname: Honey
authors.forename: Josephine
authors.initials: J
authors.lastname: Kyazike
authors.forename: Anna
authors.initials: A
authors.lastname: Park
authors.forename: Qun
authors.initials: Q
authors.lastname: Zhou
authors.forename: Clark Q
authors.initials: CQ
authors.lastname: Pan
authors.forename: Tim
authors.initials: T
authors.lastname: Edmunds
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D045744:Cell Line, Tumor; D019281:Dimerization; D000795:Fabry Disease / Q000628:therapy; D005260:Female; D006207:Half-Life; D006801:Humans; D007700:Kinetics; D008099:Liver / Q000378:metabolism; D008247:Lysosomes / Q000378:metabolism*; D008297:Male; D008358:Mannose / Q000737:chemistry; D051379:Mice; D018345:Mice, Knockout; D009844:Oligosaccharides / Q000737:chemistry; D010455:Peptides / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry; D011506:Proteins / Q000378:metabolism*; D051381:Rats; D017527:Receptor, IGF Type 2 / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D014018:Tissue Distribution; D000519:alpha-Galactosidase / Q000235:genetics / Q000378:metabolism*
chemical_list: D009844:Oligosaccharides; D010455:Peptides; D011506:Proteins; D017527:Receptor, IGF Type 2; D011994:Recombinant Proteins; C018589:lysosomal proteins; D011092:Polyethylene Glycols; D000519:alpha-Galactosidase; D008358:Mannose