Acambis PLC Initiates Pre-Clinical Testing with Herpes Vaccine from Harvard Medical School

Cambridge, UK and Cambridge, Massachusetts – 25 February 2008 – Acambis plc (Acambis) (LSE: ACM) announces that it has initiated pre-clinical trials with a herpes vaccine, licensed from Harvard University through its Office of Technology Development, with a view to submitting an Investigational New Drug (IND) application in 2009.

Herpes is caused by the herpes simplex virus (HSV), which is found in two forms, HSV-1 and HSV-2, that cause oral and genital ulcers, respectively. HSV infections are life-long as the virus becomes latent and causes recurrent disease. Genital herpes is one of the most widespread sexually transmitted infections (STIs) in the world(1). The World Health Organization (WHO) estimates that 40 to 60 million Americans are infected already,(2) making the disease one of the most common STIs in the US.

The dl5-29 HSV-2 vaccine was developed by a Harvard Medical School team led by Dr David M. Knipe, Higgins Professor of Microbiology and Molecular Genetics and Chair, Harvard Virology Program. The vaccine is an HSV-2 strain from which two genes have been deleted, making the virus incapable of replication or of establishing latent infection. Acambis holds an exclusive worldwide licence under Harvard’s patent rights to manufacture and sell the vaccine. Pre-clinical studies with dl5-29 conducted by Dr Knipe’s team at Harvard Medical School have previously shown that the replication defective vaccine:

• induces strong HSV-2-specific antibody and T-cell responses; • can protect against challenge with a wild-type HSV-2 virus; • greatly reduces the severity of recurrent disease; • provides cross-protection against HSV-1; and • is unable to revert to a virulent state or to become latent.

To date, there are no licensed HSV vaccines. Infections are treated currently with anti-viral medication, which suppresses herpes symptoms without curing the infection. The cost of herpes infections to the US healthcare system was an estimated $1.8bn in 2000, which is projected to rise to $2.5bn by 2015(3). Ian Garland, CEO of Acambis, said: “This is an exciting addition to Acambis’ increasingly broad pipeline and is part of our strategy to deliver one IND submission a year. This is a very attractive programme for a major vaccine market with limited competition and we are delighted to have licensed this Harvard Medical School technology.”

Michael Watson, Acambis’ Executive Vice President, Research & Development, added: “The dl5-29 approach offers many potential improvements on approaches to herpes vaccination that are currently being explored. The existing pre-clinical data are very encouraging and we look forward to progressing this vaccine candidate into the clinic.”

Enquiries: Acambis plc Ian Garland, Chief Executive Officer Elizabeth Jones, Chief Financial Officer Lyndsay Wright, VP, Communications and IR Tel: +44 (0) 1223 275 300

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