BioWorld International Correspondent

LONDON - Acambis plc laid out a claim-by-claim rebuttal against charges of patent infringement and the theft of trade secrets by Bavarian Nordic A/S, saying it was confident of defending the freedom to operate.

Gordon Cameron, CEO, said the charges concerning its Modified Vaccinia Ankara (MVA) smallpox vaccine, MVA3000, are "without foundation" as he outlined Acambis’ response at an analysts’ meeting in London last week.

"We have always believed and continue to believe that any patents awarded or pending do not restrict our freedom to operate in the field of MVA," Cameron said.

Cameron further charged that Bavarian Nordic’s intent is "clearly to disrupt and frustrate competition in the MVA procurement process, both in the U.S. and elsewhere."

Bavarian Nordic, of Kvistgard, Denmark, has two U.S. and one European patent on its MVA technology. Last month it filed a patent infringement case against Acambis in the Commercial Court in Vienna, Austria. The suit is in addition to a patent infringement action at the U.S. International Trade Commission and a misappropriation of trade secrets case at the U.S. Federal District Court in Delaware.

Cameron said Cambridge-based Acambis believes Bavarian Nordic’s patents are invalid and unenforceable. The company will present factual and expert evidence that MVA-BN is not novel, the patent is unenforceable through lack of enablement, Bavarian Nordic failed to supply the U.S. Patent Office with prior art and that the patents rely on scant scientific evidence.

"We will demonstrate that MVA-BN is not novel because all MVA viruses, including MVA-BN and prior art strains, have similar replication characteristics," Cameron said.

Acambis also plans to file oppositions to Bavarian Nordic’s European patent, granted in December.

On the question of stealing trade secrets, Acambis said it will present evidence that information provided at a meeting between the companies in June 2002 was not secret, and in any case, was not used by Acambis.

Acambis obtained the MVA strain used as the basis of MVA3000 from the U.S. National Institute of Allergy and Infectious Diseases (NIAID), which said it had rights to distribute the material and granted Acambis rights of use under a material transfer agreement. NIAID obtained the MVA from Anton Mayr, of the Ludwig Maximilians University in Munich, Germany, who developed the vaccine in the 1960s. Bavarian Nordic has licensed rights from Mayr, but Acambis said Mayr "did not place in writing any restriction on the NIAID’s use of the transferred MVA virus."

The companies are competing for a $1 billion contract to supply 20 million doses of MVA smallpox vaccine, with options to supply another 60 million doses as part of the U.S. BioShield program.

MVA vaccine, a highly attenuated strain that cannot replicate in human cells, is intended to protect people with weak immune systems who cannot tolerate the full-strength vaccine.

As well as forming the basis of its smallpox vaccine, Imvamune, Bavarian Nordic is developing MVA as a vector for other vaccines.