Cytel and NRC Develop Technology for Large Scale Manufacture of Breast Milk Carbohydrate.

SAN DIEGO--(BW HealthWire)--July 31, 1998--Cytel Corporation (NASDAQ:CYTL) today announced the development of a novel enzymatic synthesis technology that enables the large-scale production of a particular human breast milk carbohydrate at a reasonable cost. In a paper in the August issue of Nature Biotechnology, scientists at Cytel and collaborators from the Institute for Biological Sciences at the National Research Council (NRC) of Canada, reported the construction of a unique enzyme (a fusion protein), that when used within Cytel's proprietary Sugar Nucleotide Cycling Technology (SNC(tm) Technology), enabled the synthesis of difficult to produce carbohydrate compounds in reactions exceeding 98% completion. Cytel is currently producing a bioactive carbohydrate found in human breast milk (sialyl lactose) using this fusion enzyme at a scale of 15kg, several orders of magnitude larger than previously reported. The need for efficient carbohydrate production methods has grown significantly in recent years due to the increasing potential for their use in a variety of markets including pharmaceutical, nutritional and other consumer product markets, according to Jim Paulson, Cytel's chief scientific officer and general manager of Glytec.

"We are especially pleased to see that this technology can be used effectively for the synthesis of commercially important bioactive carbohydrates," said Paulson. "As companies move into late-stage product development and commercialization of carbohydrate products, the mass production of these compounds is critical. With the novel SNC Technology, a new manufacturing facility in operation and the collaborative partnership program we have established through our Glytec division, Cytel is ideally prepared to meet these needs."

The newly created fusion protein combines two enzymes (CMP-Neu5Ac synthetase and (alpha)-2,3-sialyltransferase), involved in the SNC synthesis pathway into a single fusion protein. The resulting bifunctional enzyme can be efficiently produced using Escherichia coli, a factor that is crucial for producing carbohydrate products at a reasonable cost. Using previously available methods, researchers could produce only tens of milligrams of carbohydrate product at one time. Using the novel enzymatic synthesis technology being developed at Cytel and NRC, researchers can produce these compounds in quantities of tens of kilograms instead.

"Typically, there is great difficulty and cost associated with creating sialylated products due to the instability of CMP-Neu5Ac synthetase," added contributing author Robert Bayer, group leader of molecular biology and biochemistry at Cytel. "With this research, we have provided a single enzyme that can do the work of two, making the process more efficient and affordable. The use of fusion proteins appears to be a valuable approach for Cytel's SNC Technology and could be beneficial for enhancing other multi-enzyme processes as well."

Sugar Nucleotide Cycling Technology is used for the assembly of complex and specific bioactive carbohydrates on a commercial scale and is also useful for synthetic remodeling of carbohydrates or recombinant glycoproteins. The technology imitates the natural carbohydrate synthesis process requiring a cascade of chemical reactions initiated by specialized enzymes. The method is more time and cost effective than other chemical synthesis technologies.

Cytel discovers and develops cell adhesion inhibitors for treatment of acute and chronic inflammation, and manufactures bioactive carbohydrates for use in medical and consumer products. Epimmune Inc., its subsidiary, is focused on the discovery and development of a new generation of safer, more potent vaccines for the prevention and treatment of cancer and infectious diseases.

This press release includes forward-looking statements that reflect management's current views of future events. Actual results may differ materially from the above forward-looking statements due to a number of important factors, including but not limited to the risks associated with successfully negotiating and completing definitive agreements for any corporate collaboration, the timing and cost of conducting human clinical trials, the regulatory approval process, and the possibility that testing may reveal undesirable and unintended side effects or other characteristics that may prevent or limit the commercial use of proposed products. These factors are more fully discussed in Cytel's most recent Forms 10-K and 10-Q.

CONTACT: Cytel Corporation/Glytec

Jim Paulson, 619/552-3000

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