LONDON - Oxxon Pharmaccines Ltd. has raised #1.1 million (US$1.6 million) in its first funding round and says it will start clinical trials of hepatitis B and melanoma vaccines within the next few months.

CEO David Phillips told BioWorld International the money raised would last until 2001, but he is looking to raise more money later this year. "With two vaccines in clinical trials and two other programs, we will be looking for a large new injection of cash to support the clinical program."

Oxxon is developing a platform technology, Prime-Boost, which is a means of boosting the immune response to weakly immunogenic antigens. It involves administering the antigen with a DNA plasmid vector, followed by a booster in which the antigen is delivered by a modified vaccinia virus. In animal trials, including primates, this system provokes an unusually high level of cytotoxic T-lymphocyte activity.

The initial investment came from MVM Ltd. and Neomed Management. The company has spun out of Oxford University, which has an equity share. Other shareholders include Catalyst Biomedica Ltd., the venture arm of the charity the Wellcome Trust, and the government-funded Medical Research Council.

Manufacturing already is in place to produce vaccines for the clinical trials. In the hepatitis B trial, Prime-Boost will deliver a non-proprietary antigen. In melanoma, Oxxon is negotiating with a partner that has a proprietary melanoma antigen.

"We have chosen melanoma because it is well understood. If we can get a therapeutic effect in melanoma we can go on to work on other cancers," Phillips said.

Two Phase I trials in which Prime-Boost is being used to deliver malaria and AIDS antigens already are in progress at Oxford University. While it is not clear if these programs will be licensed to Oxxon, Phillips noted they will be important in confirming that Prime-Boost is an effective platform technology.

The company, based in Oxford, also hopes to set up further partnerships. "There is a huge amount of interest in Prime-Boost, and we have had lots of approaches from companies with epitopes that want to combine them with this delivery system," Phillips said. The system also could have applications in the treatment of allergies.

Joerg Schneider, director of research and one of the inventors of Prime-Boost, told BioWorld International it was a "chance observation" that led to the discovery that using the plasmid DNA and vaccinia virus vectors in sequence induced a significant cellular immune response. "We were testing many different vectors, trying to increase the response in a mouse malaria model."

He speculated that the system works because the plasmid DNA plus antigen provokes a modest but focused response. "If you then boost using the same antigen presented in a different context, that is, in the presence of other viral proteins, there is a danger signal from the virus, and the pre-primed T cells react very quickly."