April 28, 2005 04:59 ET

Acambis announces significant progress on its MVA smallpox vaccine programme with publication of Phase I trial results

Cambridge, UK -- (MARKET WIRE) -- April 28, 2005 --Cambridge, UK and Cambridge, Massachusetts - 28 April 2005 - Acambis plc (Acambis) (LSE: ACM, NASDAQ: ACAM) announces an update on its programme to develop and manufacture its Modified Vaccinia Ankara ("MVA") attenuated smallpox vaccine, MVA3000, with results from a Phase I clinical trial of MVA3000. Acambis is co-developing the MVA3000 vaccine with Baxter Healthcare SA ("Baxter"), which is providing process development and manufacturing services.

MVA3000 is a weakened form of smallpox vaccine that is being developed for use in people for whom the traditional smallpox vaccine is contraindicated, such as patients with disorders of the immune system or skin conditions such as eczema. Acambis was awarded contracts by the US National Institute of Allergy and Infectious Disease ("NIAID"), part of the US National Institutes of Health, in February 2003 and September 2004 for the manufacture of MVA3000 and a series of Phase I and Phase II clinical trials.

In the randomised, double-blind Phase I trial, Acambis investigated MVA3000's safety and immunogenicity profile in 88 healthy adults who had not previously been vaccinated against smallpox. In addition, a comparator group of 22 subjects received a placebo.

In subjects vaccinated at the highest dose level, 97% seroconverted to vaccinia virus-specific antibodies (determined by enzyme-linked immunosorbent assay) and 82% seroconverted to vaccinia neutralising antibodies (determined by plaque-reduction neutralisation testing) after two doses. No subjects experienced unexpected or serious adverse events.

Dr Thomas Monath, Chief Scientific Officer of Acambis, commented:

"These clinical trial results were exactly in line with our expectations, based on the long history of MVA and the pre-clinical testing profile of MVA3000. These results give us a clearer picture of the candidate vaccine's clinical profile that increases our confidence for the upcoming trials. We will start a Phase II safety and immunogenicity trial in healthy adults as planned in the coming weeks and are on schedule to commence additional Phase I trials in target population subjects with HIV and atopic dermatitis later this year."

The US Government has indicated its intention to procure a stockpile of an attenuated smallpox vaccine, such as MVA3000, as part of its defence against the threat of smallpox virus being used as a bioterrorist weapon, for which Acambis and Baxter plan to tender in due course.

Chief Executive Officer Gordon Cameron added:

"We have successfully completed all planned activities to date and have met every milestone and deadline since being awarded the NIAID contract in September 2004. These trial results have confirmed our expectations of MVA3000's clinical profile and, together with our strong track record in delivering on government contracts and ability to manufacture to commercial scale through our partnership with Baxter, reinforce our competitive edge in the MVA field. We are confident we are in prime position to bid for supply of the US Government's MVA stockpiling requirements."

All studies are being funded under the NIAID contracts. The MVA3000 programme has been designated as a "fast track" development programme by the US Food and Drug Administration.



Gordon Cameron, Chief Executive Officer
Tel: +1 (617) 761 4200

David Lawrence, Chief Financial Officer
Lyndsay Wright, VP, Communications and Investor Relations 
Tel: +44 (0) 1223 275 300

Financial Dynamics:
David Yates/Lucy Briggs
Tel: +44 (0) 20 7831 3113

About Acambis

Acambis is a leading developer of vaccines to prevent and treat infectious diseases. Recognised internationally as the leading producer of smallpox vaccines, Acambis is developing an investigational smallpox vaccine and is manufacturing emergency-use stockpiles of this investigational vaccine for the US Government and other governments around the world. Acambis is establishing a travel vaccines franchise through its US-based subsidiary Berna Products Corporation, which markets Vivotif®, the world's only licensed oral typhoid vaccine, in North America. Acambis has other potential travel vaccines in development and is also developing an investigational vaccine against the West Nile virus, which has spread to 47 US States in the last six years.

Acambis is based in Cambridge, UK and Cambridge, Massachusetts, US. Its primary listing is on the London Stock Exchange (ACM) and its shares are listed in the form of American Depositary Receipts on NASDAQ (ACAM). More information is available at

About Acambis' NIAID contracts

Acambis has been awarded two contracts by the NIAID for the manufacture and development of its MVA smallpox vaccine, MVA3000. The first contract, awarded in February 2003, was for $9.2m. The second, awarded in September 2004, is potentially worth up to $131m, with a $76m core component requiring clinical testing and manufacture of 500,000 doses of MVA3000, and an optional element worth $55m for the manufacture of a further 2.5 million doses of MVA3000.

"Safe Harbor' statement under the Private Securities Litigation Reform Act of 1995:

The statements in this news release that are not historical facts are forward-looking statements that involve risks and uncertainties, including the timing and results of clinical trials, product development, manufacturing and commercialisation risks, the risks of satisfying the regulatory approval process in a timely manner, the need for and the availability of additional capital. For a discussion of these and other risks and uncertainties see "Risk management" in the Company's 2004 Annual Report and 2003 Form 20-F, in addition to those detailed on the Company's website and in the Company's filings made with the Securities and Exchange Commission from time to time. These forward-looking statements are based on estimates and assumptions made by the management of Acambis and are believed to be reasonable, though are inherently uncertain and difficult to predict. Actual results or experience could differ materially from the forward-looking statements.

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