Latest Trial Results Move British Company Ahead in the Race to Develop New Oral Vaccine to Protect Against Travelers' Diarrhea

LONDON -- A clinical trial undertaken by the UK

Biotechnology company Microscience at the St George's Vaccine Institute at St

George's Hospital Medical School in London has demonstrated the safety and

immunogenicity of their new oral vaccine which is intended to protect against

the infectious enterotoxigenic E. coli disease (ETEC), the commonest cause of

travelers' diarrhea.

This illness affects international business and leisure travelers

resulting in missed meetings, at high cost to company budgets, and ruined

holidays. The need also to protect the health of key peace keeping personnel,

as well as the armed forces serving abroad, is also driving the development of

this pioneering oral vaccine.

The trial at St George's was a dose escalating open label study involving

36 volunteers. The primary aim of the study was to assess the safety and

determine the serum antibody and mucosal responses raised by this novel

vaccine. The results showed that the vaccine had an excellent safety profile

and was highly immunogenic. After a single dose, 50 percent of the volunteers mounted

high levels of immune responses against a known protective antigen of ETEC.

After two doses, the response rate rose to 70 percent.

"The results exceeded our expectations," said chief scientific officer Dr

Steve Chatfield "and pave the way for the development of a whole new

generation of oral vaccines which are safe, easy to administer and effective".

Dr David Lewis, the clinical investigator for the study said, "The results

of this first study with spi-VEC are exciting and these are the best results

achieved to date in humans using this type of oral delivery system".

Having successfully proven both the immunogenicity and safety of this oral

ETEC vaccine Microscience is now moving onto a Phase II program. This will

include trials to demonstrate protection against the disease and to develop an

optimal dosing regimen that will be administered over a few days in order to

ensure that recipients of the vaccine gain rapid immunity.

Spi-VEC vaccines are live vaccines from which genes involved in the

infection process have been removed, rendering them unable to cause disease.

The trial has shown that these harmless vaccines are still recognized by the

human immune system as a threat and a robust and rapid immune response is

mounted against them. The vaccine consists of harmless Salmonella bacteria

that have been modified to carry an ETEC antigen. The Salmonella bacteria then

act as a vehicle to deliver this directly to cells of the immune system

resulting in efficient antigen presentation and strong immune responses.

The company is also harnessing the spi-VEC platform technology to develop

other new oral vaccines to protect against typhoid and anthrax. A product is

also in clinical development for the treatment of chronic hepatitis B. There

is now a major interest in other therapeutic treatment approaches for

bacterial and viral diseases including cancer.

Microscience is a private biotechnology company based in the UK near

London. The company has a clinical development portfolio of five unpartnered

human vaccines which include oral vaccines to protect against Typhoid (Phase

II), Travelers Diarrhea (Phase I) and a therapeutic vaccine for Hepatitis B

(Phase I). Clinical trials for two injectable vaccines to protect against

Meningitis B and neonatal Group B Streptococcus (Phase I) infections are due

to report in this year.

Source: Microscience Ltd