GenVec's Colorectal Cancer Gene Trial

Us company GenVec has initiated an 18-patient clinical study of Ad(GV)CD.10, a new gene-based treatment for liver metastases of colorectal cancer, one of the leading causes of cancer deaths in the USA. The first phase of the trial will seek to evaluate the product's safety and antitumor effects.

GenVec's trial involves use of an adenovirus vector modified to carry the cytosine deaminase gene. Once administered directly into a hepatic tumor, the gene expresses an enzyme that converts 5-fluorocytosine, an orally administered antifungal, into a potent antitumor agent, 5-fluorouracil. The conversion will occur only at the site of gene expression, says GenVec, so that the 5-FU will be restricted to the transfected cells and nearby malignant cells. The company says that Ad(GV)CD.10 affords a "prodrug" approach, which may allow clinicians to apply a drug's active tumor effects in a very localized tissue area while greatly minimizing its system toxicity.