The Virus Hunters

Using viruses to fight disease is not a new idea. The vaccines that fend off smallpox and polio, for example, are derived from diluted versions of the viruses that cause those dreaded diseases.

But genetic engineering techniques may offer even more novel ways to enlist infectious agents in medicine's armory of therapies and vaccines. British biotech company BioVex (www.biovex.com) is using a genetically-altered version of the herpes simplex virus (HSV) to develop two products that may help beat a variety of cancers.

Its main product, OncoVEX has been engineered to rapidly replicate itself within a tumor, killing the malignant cells but leaving healthy tissue unmolested. Moreover, it further treats any cancer that has spread to other areas of the body, then acts as a vaccine to stop the disease from recurring. Initially, OncoVex will be used against breast, head and neck cancers, as well as malignant melanoma, or skin cancer. Clinical trials of OncoVEX begin in three months, which means it will likely take at least seven years before it could be marketed, if it is approved. A rival American company, Onyx Pharmaceuticals, is already well into its clinical trials with a therapy based on the cold virus. But Philip Astley-Sparke, chief financial officer of BioVex, says their HSV-based product will be a much more potent remedy.

BioVex's second product is ImmunoVex, which is also derived from HSV. Unlike, say, the polio vaccine that's a prophylactic vaccine given to the general public, ImmunoVex is a therapeutic vaccine that's given to patients to help supercharge their immune systems to battle chronic cancer. It does this by loading dendritic cells, which regulate the immune system, with therapeutic antigens. These cells are easily infected by HSV, but are not activated by the virus. But BioVex has identified and removed the genes and proteins that stop the virus from stimulating the dendritic cells. "We are the only ones who can do that," Astley-Sparke says. ImmunoVex's clinical trials should begin in a year. Initially, ImmunoVex will target malignant melanomas. But Astley-Sparke calls both products "broad-based platforms" that eventually could be used against many cancers as well as infectious diseases, including hepatitis B and C, and genital herpes.

BioVex was launched in 1999 by Professor David Latchman and Dr. Robert Coffin, both herpes experts, with $20 million in funding. It has since formed partnerships with the drug companies Aventis and AstraZeneca. And in July 2001, it received $14 million in second-round funding. Astley-Sparke says it will seek about $22 million in additional funds late this year. While the majority of products fail clinical trials, Astley-Sparke says the company is confident because the "scientific rationale behind these products is exceptionally strong." Still, he adds, success remains "a big if" at this early stage. Should these remedies win approval, the financial rewards would be great. Both products could have market values worth billions of dollars. While that would give BioVex's investors something to cheer about, it would give countless cancer patients something much more valuable — hope.