Single Dose Oral Typhoid Vaccine Shown in US Multi-Centre Trial to be Safe and Immunogenic

UK, February 27th, 2003 – Microscience has announced the results of a multi-centre clinical trial which shows that their new generation single dose oral typhoid vaccine is safe, well-tolerated and highly immunogenic. The study was carried out using a freeze-dried product suitable for commercialisation. These results confirm the finding of an earlier trial in the UK.

UK, February 27th, 2003 – Microscience has announced the results of a multi-centre clinical trial which shows that their new generation single dose oral typhoid vaccine is safe, well-tolerated and highly immunogenic. The study was carried out using a freeze-dried product suitable for commercialisation. These results confirm the finding of an earlier trial in the UK.

The multi-centre outpatient trial involved 60 healthy adult volunteers and was carried out under a Microscience sponsored IND at the University of Vermont with Fletcher Allen Healthcare, Burlington VT and the Johns Hopkins University Bloomberg School of Public Health, Baltimore MD.

These latest most promising results move our oral typhoid vaccine centre stage" said Research and Development Director Dr Steven Chatfield today given that the freeze dried product used for this randomised, double-blind, dose escalation placebo controlled trial is that proposed for the final commercial vaccine. The fact that we already have a manufacturing process in place suitable for commercialising the product is of major strategic importance. This will result in savings, both time and money as we move this vaccine quickly through the Phase II programme"

Microscience are developing this live attenuated vaccine principally to provide travellers with an effective single dose vaccine, which can be taken by mouth to protect against typhoid fever. It will be a convenient new alternative to current multi-dose oral and single dose injected vaccines.

A significant number of cases of typhoid are reported in both US and Europe most of which are contracted while abroad with an estimated global incidence of 30 million cases and 600,000 mortalities, worldwide every year.

In the trial the vaccine was found to have an excellent safety profile at all three dose levels. These were 5 x 107 and 5 x 108 and 5 x 109 live attenuated bacteria. It was well tolerated with no bacteraemias attributable to the vaccine at any dose level. The incidence of adverse events was not statistically different from that detected in subjects receiving placebo.

All volunteers who received the highest dose of the vaccine mounted an excellent immune response, demonstrated by measuring mucosal and systemic responses. This important result proves the vaccines effectiveness in priming both the mucosal immune system – the bodys first line of defence – as well as the systemic immune system, essential for a successful single dose approach. Injected vaccines elicit a systemic response but a poor mucosal immune response.

Commenting on the result, investigators Dr Beth Kirkpatrick and Professor Lou Bourgeois said We think this oral, single dose freeze-dried vaccine - which was simple to administer – is showing great promise providing an excellent basis on which to advance further clinical development."

Microscience has used its patented Signature Tagged Mutagenesis (STM) functional genomics technology - which allows the development of safe live attenuated vaccines – to develop this new vaccine.

The results of this clinical study further validate the approach of using the oral typhoid vaccine to orally deliver other vaccine antigens for delivery to the immune system.

The company has already developed two further vaccines using this approach. Known as
spi-VEC vaccines, they are both scheduled to enter clinical trials this year. One is a vaccine to protect against a common form of travellers diarrhoea (ETEC) and the other is a therapeutic vaccine to treat chronic Hepatitis B carriers.

Other conditions that could be prevented, or treated, are also being investigated and include bacterial and viral diseases, allergies and cancer.

Microscience is a privately owned biotechnology company with a development portfolio of five vaccines. As well as three oral vaccines, Microscience is planning clinical trials for two injectable vaccines to protect against Meningitis B and neonatal Group B Streptococcus infections. Microsciences headquarters, research and development facility is near Reading, Berkshire, UK. Further information is available at www.microscience.com.

Media enquiries - Jean Garon PR - +44 1628 483040, email jean@garonpr.demon.co.uk.

Information in this press release may include forward-looking statements which embrace risk and uncertainties. However all information included in this text is based on information available to our client at the time of issue. These statements are not guarantees of future performance and actual results could differ materially from current expectations