PolyXen®
PolyXen® is an enabling technology for protein drug delivery. It uses the natural polymer polysialic acid (PSA) to prolong the active life and improve the stability of therapeutic peptides and proteins. It can also be used for small molecule drugs.
A model of the molecular structure of a polysiaylated peptide
Proof-of-concept preclinical studies have shown that the key benefits of PolyXen® for protein drug delivery include:
- Preservation of functionality on conjugation
- Improved stability in vivo
- Prolonged pharmacological action
- Prolonged active life of the drug in the blood circulation
- Preservation of biological activity of the protein drug
- Reduced frequency and amount of dosage
- Reduced immunogenicity and antigenicity
What is polysialic acid?
PSA is a polymer of sialic acid (a sugar). When used for protein and therapeutic peptide drug delivery, polysialic acid provides a protective microenvironment on conjugation. This increases the active life of the therapeutic protein in the circulation and prevents it from being recognized by the immune system.
The PSA polymer is naturally found in the human body. It was adopted by certain bacteria which evolved over millions of years to coat their walls with it. These naturally polysialylated bacteria were then able, by virtue of molecular mimicry, to foil the body’s defence system. PSA,is nature's ultimate stealth technology it can be easily produced from such bacteria in large quantities and with predetermined physical characteristics. Bacterial PSA is completely non-immunogenic, even when coupled to proteins, as it is chemically identical to PSA in the human body.
The use of PSA therefore makes PolyXen® a particularly effective form of protein drug delivery. PSA is a naturally occurring polymer, and it is biodegradable, non-immunogenic and non-toxic. This is particularly important where a polymer is to be used to deliver therapeutics chronically or in large dosages
How does PolyXen® technology use polysialic acid?
PolyXen® uses proprietary techniques to conjugate polysialic acid molecules of appropriate length to specific sites of the therapeutic, away from its active site. These molecules form a glycocalyx around the therapeutic. This makes the therapeutic less visible, which reduces the risk of its recognition by the body’s immune system.