LONDON - BioVex Ltd., a gene delivery company specialising in the herpes simplex virus, has begun preclinical development of OncoVEX, a modified herpes simplex virus for treating solid tumors.

OncoVEX has a single gene deletion that renders the virus non-pathogenic to non-tumor cells, while still being capable of growing in and killing tumor cells. The product has shown effectiveness in killing prostate, melanoma and brain cancer tumor cell lines.

CEO Gareth Beynon told BioWorld International that engineering herpes simplex to have inherent oncolytic capabilities would enhance the efficacy of replicating virus therapy in solid tumors. "As well as having a direct oncolytic effect, OncoVEX can be used as a vector for specific antitumor genes. The pharmaceutical industry is interested in putting proprietary suicide genes such as p53 into such vectors."

BioVex, of London, plans to arm OncoVEX with a suicide gene, and is aiming to start Phase I trials by 2002. It is in discussions with pharmaceutical partners to license the vector.

BioVex was set up 18 months ago with venture capital backing from the Merlin Fund. In addition to OncoVEX, the company has two other platform technologies: NeuroVEX, a disabled herpes simplex virus specialized for delivery to nerve cells, and ImmunoVEX, in which the virus has been engineered to deliver genes to dendritic cells without impairing their ability to elicit an immune response.

BioVex also is focusing on central nervous system diseases. "Herpes has a unique advantage over other delivery mechanisms in CNS because it can traffic along neurons, allowing us to deliver genes to the spinal cord and the brain," Beynon said. This could be significant in treating chronic pain, spinal injury and motor neuron disease.

All three platforms also are being used for functional genomics.

"A lot of people have worked for a long time to delete genes from herpes. We are building on a broad base of unique, proprietary gene deletions," Beynon said. BioVex has also modified herpes to prevent it from going inert after three to four weeks. "We have found a unique way to keep it active long term, allowing for months and months of expression, which is of course extremely significant in treating chronic diseases."

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