Synthesis and Characterization of Heparosan-Granulocyte-Colony Stimulating Factor Conjugates: a natural sugar-based drug delivery system to treat neutropenia

Research output: Contribution to journalArticlepeer-review

  • Authors:
  • Wei Jing
  • Jonathan Roberts
  • Dixy E. Green
  • Andrew Almond
  • Paul L. DeAngelis


Many injectable drugs require delivery strategies for enhancing their pharmacokinetics due to rapid loss via renal filtration if possess low molecular weight (<60-70 kDa) and/or clearance by the body‟s components (e.g., proteases, antibodies, high-efficiency receptors) in their native form. FDA-approved polyethylene glycol [PEG] is a vehicle for improving therapeutics, but artificial polymers have potential biocompatibility and immunogenicity liabilities. Here we utilized a natural vertebrate carbohydrate, heparosan [HEP], the biosynthetic precursor of heparan sulfate and heparin, to enhance performance of a biologic drug. The heparosan polysaccharide was stable with a long half-life (~8 days for 99-kDa chain) in the non-human primate bloodstream, but was efficiently degraded to very short oligosaccharides when internalized by cells, and then excreted into urine and feces. Several heparosanmodified human granulocyte-colony stimulating factor [G-CSF] conjugates were synthesized with defined quasi-monodisperse HEP polysaccharide chains. Single dosing of 55- or 99-kDa HEP-G-CSF in rats increased blood neutrophil levels comparable to PEG-G-CSF conjugates. Repeated dosing of HEP-G-CSF or heparosan alone for 2 weeks did not cause heparosan-specific toxic effects in rats. Heparosan did not possess the anticoagulant behavior of its daughter, heparin, based on testing in rats or clinical diagnostic assays with human plasma. Neither anti-heparosan IgG nor IgM antibodies were detected in a long-term (9 doses over 7 months) immunogenicity study of the HEP-drug conjugate with rats. These proof-of-concept experiments with HEP-GCSF indicate that it is a valid drug candidate for neutropenia and suggest the potential of this HEP-based platform as a safe alternative delivery vehicle for other therapeutics.

Bibliographical metadata

Original languageEnglish
Pages (from-to)1052-1061
Number of pages10
Issue number11
Early online date8 Sep 2017
Publication statusPublished - Nov 2017

Related information


View all