Oxxon Therapeutics Inc. HI-8(TM) HBV Therapeutic Vaccine Proves Safe And Efficacious In Treating Chronic Hepatitis B

Published: Apr 27, 2006

OXFORD, April 27 /PRNewswire/ -- Oxxon Therapeutics today presented efficacy data from the recently completed Phase IIa clinical study of its novel Hi-8(TM) HBV therapeutic vaccine treatment for patients with chronic hepatitis B at the 41st Annual Meeting of the European Association for the Study of the Liver (EASL), held in Vienna, Austria (April 26-30, 2006). The poster will be available at www.oxti.com from April 28, 2006.

The clinical data show that that Oxxon's Hi-8(TM) HBV therapeutic vaccine is well tolerated and is capable of inducing HBeAg seroconversion (an accepted measure of disease reduction) followed by a viral load decrease in a significant proportion of patients with chronic hepatitis B. These data support further evaluation of the Hi-8(TM) HBV therapeutic vaccine in a larger Phase IIb trial.

John Berriman, Executive Deputy Chairman of Oxxon, said, "This efficacy data for our Hi-8(TM) HBV therapy is a very important milestone for Oxxon: not only does it validate our unique Hi-8(TM) PrimeBoost(TM) proprietary platform, but also it is some of the clearest evidence yet of the potential of therapeutic vaccines to treat serious disease. We will now finalise the Phase IIa clinical data package and seek a development and marketing partner to take the hepatitis B programme forward towards commercialisation."

Dr Joerg Schneider, Vice President and Director of Research at Oxxon, said, "A significant benefit of our Hi-8(TM) HBV therapy is that it induces sustained HBeAg seroconversion and HBeAg loss followed by reduction of viral load after only four injections over nine weeks. The efficacy of Hi-8(TM) HBV appears comparable to current treatments. Existing HBV treatments are suboptimal; Interferon has significant side effects and antivirals such as lamivudine or adefovir have to be taken daily to maintain virus suppression and can lead to virus resistance. These data suggest that Oxxon's Hi-8(TM) HBV offers the potential to be the first well-tolerated therapeutic vaccine for this devastating disease and supports the continued development of this product."

The Study Design and Results

Oxxon's Hi-8(TM) HBV treatment is designed to induce the immune system to mount a targeted and potent immune response against the hepatitis B virus. Previous Phase I studies demonstrated the safety and tolerability of Hi-8(TM) HBV in this indication.

The Phase IIa 52-week study involved 54 patients with chronic hepatitis B who were randomized to receive either therapeutic vaccine alone, therapeutic vaccine plus lamivudine or lamivudine alone. The vaccine, given at three-week intervals over nine weeks, comprised two DNA plasmid "primes" (2mg) and two modified vaccinia virus Ankara (MVA) "boosts" (5 x108pfu), both vectors expressing the same HBV surface antigen. Lamivudine was given 100mg daily for 14 weeks. T-cell responses were assessed using Interferon gamma (IFN-gamma) ELISPOT assays.

By 52 weeks, HBeAg clearance in 24% (5/21) and HBeAg seroconversion in 19% (4/21) of patients receiving the Hi-8(TM) HBV therapeutic vaccine alone was seen. In patients that seroconverted a viral load decrease of up to 3 logs was observed. No synergy in terms of increased efficacy was seen in the group that received therapeutic vaccine plus lamivudine. Preliminary work aimed at detecting HBV-specific T-cell responses has shown a trend towards both higher responses and a higher number of responders following therapeutic vaccination.

The study concluded that this novel disease-specific therapeutic vaccine was well tolerated and appears capable of inducing HBeAg seroconversion and reducing the HBV viral load in HBeAg seroconverters. These data support further evaluation of Hi-8(TM) HBV in a larger Phase IIb trial.

The trial was conducted at 11 outpatient study centres in Poland, and Serbia & Montenegro.

About Oxxon Therapeutics

Oxxon Therapeutics (Oxxon), based in Oxford, UK, is advancing the next generation of innovative immunotherapeutics to treat patients with chronic infectious diseases and cancer. To date the Company has built a pipeline through its proprietary Hi-8(TM) PrimeBoost(TM) platform, an approach that allows rapid development of products to selectively stimulate and enhance a potent cellular response. The Company has development programmes in hepatitis, melanoma and HIV, two of which have just completed early Phase II clinical trials. In addition, Oxxon is leveraging its enabling platform through partnerships with a number of external collaborators.

For more information, please visit www.oxti.com

Oxxon Therapeutics

CONTACT: For further information, please contact: John Berriman, ExecutiveDeputy Chairman, Dr Joerg Schneider, Vice President / Director of Research,+44-(0)1865-398100, info@oxti.com, Mark Swallow PhD, Citigate DeweRogerson, +44-(0)20-7638-9571, mark.swallow@citigatedr.co.uk

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