The Pharmaceutical Journal
Vol 273 No 7320 p531
9 October 2004

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Delivery is key to developing gene therapy products for patient use

The 2004 British Pharmaceutical Conference and Exhibition “Medicines: from cell to society” took place at Manchester International Convention Centre from 27–29 September

BPC 2004 summary

Delivering sufficient DNA to the nuclei of the appropriate cells and having it stay there long enough to achieve protein expression remains a big challenge when developing gene therapy products. This was one of the main messages from the presentations of Tony Phillips, of Phillips Consulting, and Len Seymour, of the University of Oxford, who gave their perspectives on the issues that need to be overcome when developing gene therapy products, from an industrial and academic stand point, respectively.

Various delivery methods are being looked at, including coating DNA onto gold particles and firing it into the skin. Once in the epidermis, the particles are taken up by antigen presenting cells, eliminating many barriers traditionally associated with delivery to the immune system, Dr Phillips said.

Challenges other than delivery include those relating to manufacturing and quality control and product safety. Products using non-viral vectors are generally manufactured using Escherichia coli fermentation techniques and so there is a need to limit endotoxin content and the amount of bacterial DNA and RNA present. It is also important to make sure that a minimum amount of the therapeutic DNA is in the supercoiled form, since this is more prone to strand breakage. For viral vectors, yield is an issue, particularly when retroviruses are used, Dr Phillips said.

Another challenge is the expense of research and development. “The costs of getting products into clinics are prohibitive for academia,” Dr Seymour added.