LONDON - Cantab Pharmaceuticals plc saw its share price fall by 56.5 pence to #2.65 last Thursday after it said an unnamed U.S. university has challenged two of its patents.

The notification of interference refers to U.S. patent No. 5,665,362 granted in September 1997 and No. 5,837,261 granted in November 1998, both of which relate to the company's DISC virus vaccine technology. DISC viruses are genetically engineered, or disabled, so that they can go through only one cycle of replication in the host, provoking an immune response but not causing disease.

Cantab, based in Cambridge, England, licensed the technology to Glaxo Wellcome plc in 1997 for a DISC HSV product for the prevention and treatment of genital herpes, and to Pfizer Inc. in 1995 for veterinary vaccines. Cantab spokeswoman Melissa Hellberg told BioWorld International the two licensees were aware at the time of the university's filing. "They are supportive of our confidence in the validity of our patents," she said.

The first patent application on the DISC technology was filed in the UK in September 1990, which Cantab says predates the university's patent application in 1992 by more than 20 months. However, unlike every other territory, where first to file wins the race, in the U.S. it is possible to make a claim to have invented something before someone else filed a patent.

Rights to use the technology in Europe and elsewhere are not affected by the action, nor is the use of DISC in gene delivery.