The use of plasmid DNA for therapeutic use is an over-twenty-year-old concept. Early approaches, both in the therapeutic and vaccine area, whilst initially promising in the lab, could not be repeated in the clinic and interest in the area dwindled. However, over the last 2-3 years there has been a very marked increase in interest in the use of plasmid DNA. Firstly, as a therapeutic in its own right, with a number of companies achieving positive clinical outcomes in the oncology and cardiovascular fields and more recently the successful UK trial in cystic fibrosis.
Alongside this has been the use of plasmid DNA as a starting material for the production of viral vectors and for the production of AAV and Lentiviral vectors for use in gene therapy, including a number of immuno-therapy approaches. These products require 3 or 4 different plasmids to construct each vector. More speculatively, we also see an emerging interest in the potential use of plasmid DNA for the use of transient protein production, where companies are looking to accelerate the development of antibody programmes by generating material for early stage clinical evaluation through transient rather than stable cell line production.
These demands are now bringing their own challenges for manufacturing organisations to develop innovative forward thinking approaches in order to meet the requirements of the different markets in terms of production scales, timelines and quality systems. We are now entering a fascinating time as these products start to progress from the clinic to the market place, which will create opportunities and challenges alike for those of us working in the field.