LONDON ¿ Polymasc Pharmaceuticals plc, of London, has signed a license agreement with Onyx Pharmaceuticals Inc., following a successful research collaboration between the two companies.

Under the deal, which triggers a milestone payment to Polymasc, Onyx will license Polymasc¿s ViraMASC technology for the further development of its genetically modified adenoviruses. Further milestone payments and royalties on sales are payable on each product developed.

Onyx¿s lead product, ONYX-015, in Phase II, is a genetically modified adenovirus that replicates in and kills tumor cells deficient in p53 tumor suppressor function, commonly found in the majority of cancers. In the previous research collaboration the two partners demonstrated that ONYX-015, coated with Polymasc¿s ViraMASC polymer coating for viruses, was able to evade circulating antibodies and showed enhanced tumor localization after intravenous injection in animal models.

Most patients are already immune to adenoviruses and have circulating antibodies, which would rapidly eliminate ONYX-015 from the blood stream if it were delivered intravenously. Gillian Francis, CEO of Polymasc, which specializes in polymer-based drug delivery systems, believes that ViraMASC coatings could maintain the infectivity of ONYX-015 and other types of gene therapy vectors, allowing them to deliver genes to tumors or other sites of action.

In biodistribution studies, a small amount of uncoated ONYX-015 did reach the tumor, but between two and seven days post-injection, there was far more coated virus in the tumor. The differential varied with time, with levels of ViraMASC-coated virus being around 25 times higher at two hours, and up to 400 times higher after seven days. n