Single Dose Oral Typhoid Vaccine Shown in U.S. Multi-center Trial to be Safe and Immunogenic

Wokingham, United Kingdom -- Microscience has announced the results of a multi-center 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 commercialization. These results confirm the finding of an earlier trial in the UK.

The multi-center 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 center stage," said research and development director Dr Steven Chatfield, "given that the freeze dried product used for this randomized, 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 commercializing 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 program."

Microscience are developing this live attenuated vaccine principally to provide travelers 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 the U.S. and in 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 10 to the power of 7 and 5 x 10 to the power of 8 and 5 x 10 to the power of 9 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 vaccine's effectiveness in priming both the mucosal immune system - the body's first line of defense -- 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, investigator's 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 other 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 traveller's 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.

Source: Microscience Ltd