Onyvax Raises £8 Million to Advance Development of Prostate Cancer Vaccine

London, UK, 8 May 2006: Onyvax Ltd, the biotechnology company developing novel cancer therapies, today announces that it has raised £8 million in a Series C fundraising. The round was co-led by 3i and SR One with additional funds from Barrie Haigh, Merlin Biosciences, MB Venture Capital Fund 1 NV, Alta Berkeley Venture Partners and Alberville Ltd.

The funds raised will be used to advance the development of Onyvax-P, Onyvax's lead product for the treatment of prostate cancer, in a controlled, multi-centre Phase IIb study to commence in the summer.

Onyvax-P consists of a combination of three cell lines that contain numerous prostate cancer markers that are expressed at different stages of the disease. By raising a powerful immune response against a comprehensive set of tumour antigens, the risk of the tumour being able to mutate and become resistant to the therapy is reduced. The Phase IIa trial for Onyvax-P demonstrated:
• a favorable safety profile;
• 40% patients showed statistically significant reductions of PSA velocity (a blood marker for prostate cancer); and
• median progression free survival of 58 weeks versus historical controls of 29-30 weeks.

A rising cancer incidence combined with the limitations of conventional therapies, mean that Onyvax's approach to cancer treatment is addressing significant markets and major unmet medical needs. 467,000 new cases of prostate cancer are diagnosed per year in the US, Europe and Pacific Rim1. Cases of prostate cancer in the UK increased 25% between 1995–2002. There are no treatments currently available that have been shown to prolong life for men with hormone resistant prostate cancer who have not yet developed metastatic disease.

Commenting on the fundraising, Dr Anthony Walker, Chief Executive of Onyvax, said:

"The participation of all of our existing shareholders in this financing sends a strong signal of support. The data generated from the Phase IIa clinical trial is compelling and if a similar magnitude of effect is generated in a randomized trial it would be considered a major advance in the treatment of prostate cancer. The successful completion of randomized Phase IIb trials will generate significant value and will provide the statistical basis for pivotal trials.”

1 American Cancer Society (2003) and International Agency for Research on Cancer (WHO), GLOBOCAN 2000
2 UK Association of Cancer Registries.

For further information, please contact:

Onyvax
Dr Anthony Walker / Robert Johnson
+44 (0)208 682 9494

Financial Dynamics
Julia Philips
+44 (0)20 7831 3113

Notes to editors

Onyvax Ltd is a biotechnology company developing novel cancer therapies that harness the selective power of the immune system to seek and destroy tumor cells.

Founded in 1998, Onyvax is developing products that use the power of the immune system to treat of prostate and other cancers. Onyvax’s lead products are based on combinations of inactivated cell lines that induce immune responses to a broad spectrum of tumor targets. Onyvax-P, a Cell Vaccine for prostate cancer, will enter Phase IIb clinical trials in 2006. For each cancer type, Onyvax generates banks of proprietary cell lines representative of different stages of the disease. The vaccines are manufactured in bulk under standardized conditions.

Onyvax is also developing Onyvax-105, an antibody based therapy designed to target CD55. The product has shown promising results in early clinical trials in colorectal cancer and osteosarcoma. The company is intending to develop the antibody further, initially in prostate cancer.

Onyvax is committed to the commercialization of new therapies that significantly prolong survival while maintaining a high quality of life for cancer patients. The Company is based in London and has collaborations with leading institutions in Europe and the US. Further information on Onyvax can be found at www.onyvax.com