Onyvax Publishes Results Of Phase II Prostate Cancer Vaccine Showing Significant Steps Towards Delaying Disease Progression

[Published in Clinical Cancer Research, June 15th edition]

London, UK, 17 June 2005: Onyvax Limited, the biotechnology company developing novel cancer therapies, today announced that a paper published recently in Clinical Cancer Research [Vol. 11, 4469-4478], confirms results of the first cohort in a Phase II trial of Onyvax-P, the company’s investigational immunotherapy, showing that it may delay progression in hormone resistant prostate cancer (HRPC) patients. If the effects are repeated in forthcoming randomized trials, the safety and efficacy of this immunotherapy would make it a compelling treatment option for men at this stage of the disease.

Prostate cancer is the most common cancer in the United States. Local therapy (radiotherapy and/or surgery) is potentially curative, however a large number of men develop recurrent disease which is treated with hormone therapy. A rising level of PSA (a blood marker for prostate cancer) during hormone therapy indicates the disease has developed resistance and it was patients at this stage who were recruited to the Onyvax clinical trial. According to the Atlas of Clinical Urology, HRPC patients develop asymptomatic bone metastases 26 weeks after a rising PSA, symptomatic bone metastases 17 weeks after that, followed by death 52 weeks later. The goal of this clinical trial was to delay the onset of metastatic disease.

The results showed that 42% of the treated patients showed statistically significant, prolonged decreases in their PSA velocity (PSAV) without experiencing significant toxicity and this is believed to be the first time this effect has been seen. Onyvax’s vaccination approach resulted in an extended median time to disease progression (TTP) of 58 weeks, a large improvement to historical experience which suggests a median TTP of 26-29 weeks.

Data from the second cohort of patients who had asymptomatic bone metastases were recently published at the American Society of Clinical Oncology on 15th May 2005.

Artificial Neural Network (ANN) analysis was used to show that certain cytokine profiles could predict clinical outcome with a high degree of accuracy. ANN’s have previously not been used to associate complex immunological parameters with clinical responses. If the ANN data is validated then this methodology will prove useful in the future management of HRPC patients.

Onyvax plans to start Phase IIb/III pivotal clinical trials of Onyvax-P this year.

For further information, please contact:

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

Financial Dynamics
Julia Philips / Lucy Briggs
+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 tumour 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 tumour targets. Onyvax-P, a Cell Vaccine for prostate cancer, is due to enter Phase IIb/III clinical trials in 2005. 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. The Phase II trial for Onyvax-P was conducted by the Department of Oncology at St George’s Hospital Medical School, London, UK.

Onyvax is committed to the commercialisation 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