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
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