Acambis receives broad patent for passive vaccination against C. difficile.

Acambis plc (Cambridge, England; 44-1223-275-300) has been issued with a broad patent in the US for its passive vaccine to treat Clostridium difficile ("C. difficile") associated diarrhea ("CDAD").

C. difficile is an antibiotic-resistant bacterium to which hospital patients and the elderly are particularly vulnerable. CDAD principally arises through the use of antibiotics when bacteria that normally occur in the gastro-intestinal tract are eliminated, rendering the patient- more susceptible to infection by C. difficile.

The patent covers Acambis' passive immunization strategy, which uses hyperimmune globulin to combat CDAD. The passive vaccine uses purified hyperimmune globulin drawn from plasma donors who have been vaccinated with Acambis' active vaccine against C. difficile. The passive vaccine would provide patients who are already suffering from CDAD with a rapid, effective immune response that their own immune systems may not otherwise be able to generate.

A Phase I/II trial of Acambis' active vaccine demonstrated that the vaccine is safe, well-tolerated and highly immunogenic at all the dose levels studied. During 2001, Acambis will produce clinical trial supplies of hyperimmune globulin from accredited donors for a Phase II efficacy trial. The trial to test the safety and efficacy of the passive vaccine is scheduled to commence in the first half of 2002.

It is estimated that, in the US alone, there are some 300,000 cases of CDAD per annum. Some 60,000 patients suffer from the severe form of CDAD which can extend the patient's hospital stay by around 21 days and increase the cost of treatment by an average of $10,000. The potential worldwide market for Acambis' passive vaccine is estimated to be worth $500m a year.

Dr. John Brown, Chief Executive Officer of Acambis, commented:

"This broad patent is a significant additional to our intellectual property portfolio. C. difficile infection is an increasing problem, and our strategy of passive vaccination is an important approach in the treatment of C. difficile."

Acambis, formerly Peptide Therapeutics/OraVax, is a biopharmaceutical company researching, manufacturing and developing vaccines to prevent and treat infectious diseases. It has operations in Cambridge, UK, and in Cambridge and Canton, Massachusetts, USA. It has a broad portfolio of vaccine product candidates undergoing clinical trials and technology platforms that provide the basis for further vaccine product candidates.