The growth of mPEG technology

The biopharmaceutical market is growing rapidly and is expected to continue on this upward track.¹ Seven of the top 10 best-selling drugs in 2013 were biologics.² Pharmaceutical innovators are investing more in the development of biopharmaceuticals because biologics have certain advantages over more traditional small molecule therapies. Biologic medicines such as proteins, antibodies, siRNA and other natural products have higher specificity compared with small molecule drugs. This means they are more targeted and therefore induce fewer side effects, which can increase patient compliance.

Targeted therapies are useful in the treatment of diseases such as cancer because the molecules can be directed specifically to the tumour and can avoid attacking normal healthy cells.³ One of the major limitations of some biologic medicines is their short half-life in the body. They can also be attacked by the immune system or degraded by proteolytic enzymes, all of which can reduce the bioavailability of the biologic entity.

The addition of an mPEG can reduce the activity of the drug but this is compensated for by the increased bioavailability of the molecule

At present, the gold standard solution for increasing the half-life of biologics is the use of methoxy polyethylene glycol (mPEG) chains. These can be attached to the biological molecule via a process known as PEGylation. This has the effect of increasing the hydrodynamic radius of the biologic, thus reducing the renal clearance in the kidneys. It also shields it from attack by the immune system and degradation enzymes, which has the overall effect of increasing the bioavailability of the compound. The addition of an mPEG can, however, reduce the activity of the drug but this is compensated for by the increased bioavailability of the molecule.