Cytel Corporation announces new development strategies at New York investors' conference.

New York, NY--(BUSINESS WIRE)--December 3, 1996--Today Cytel Corporation (Nasdaq:CYTL) announced new development strategies for its lead drug candidates, Theradigm(TM)-HBV and Cylexin(TM), in a presentation by the company's executive vice president and chief operating officer, Robert L. Roe, M.D., at the Robertson Stephens Medical Conference.

Theradigm in Combination Therapy for Viral Infections

Theradigm is Cytel's proprietary technology for therapeutic vaccines aimed at curing viral infections. In Phase I and II clinical trials to date, Theradigm-HBV -- which, if successful, would be indicated for treating chronic hepatitis B infection -- has safely stimulated a virus-specific cellular immune response (cytotoxic T lymphocytes, or killer T cells) in healthy volunteers and in patients infected with hepatitis B. These studies have indicated that the effects of Theradigm-HBV are highly selective for the hepatitis B virus, and Cytel is developing Theradigm-HBV as an alternative to other immune stimulants, such as alpha interferon, which can cause undesirable, inflammatory side effects because of their lack of viral specificity.

Recently available data suggests that the effectiveness of Theradigm in generating a cellular immune response may be stronger in patients with lower amounts of virus in their bodies. Since several newly developed anti-viral drugs are effective at quickly lowering viral load, this data points to the potential use of Theradigm in combination with these agents.

"The new generation of nucleotide compounds appears to be effective at temporarily lowering viral load, but the infection often recurs when treatment is stopped, and extended therapy introduces the risk of viral mutations leading to drug resistance," Dr. Roe said. "Since Theradigm seems to work best when viral loads are low, we have decided that our most likely chance of achieving a true cure will be to use a combination drug approach: combining a nucleotide to suppress viral activity that overwhelms the immune system, with Theradigm to activate a selective immune response that eradicates the infection. Thus, we plan to initiate clinical studies of Theradigm-HBV in combination with an anti-viral agent in early 1997, and we have no plans at present to conduct additional clinical studies of Theradigm-HBV as a monotherapy. The goal of these new studies is to show that combination therapy can cure chronic hepatitis B infection without a long duration of treatment and the attendant risk of inducing drug resistance."

Cylexin for Blocking Reperfusion Injury 

Cylexin is Cytel's drug candidate for reducing reperfusion injury to organs, damage which can occur when blood flow is temporarily cut off and then restored. Cylexin is a synthesized form of a naturally occurring carbohydrate molecule which plays a key role in amplifying an inflammatory response caused by re-establishment of blood flow. Preclinical studies have indicated that Cylexin can block this response and reduce the severity of reperfusion damage.

Early clinical studies in humans have indicated that the most immediate application for Cylexin may be in the cardiopulmonary bypass setting. Although clinical trials of Cylexin in myocardial infarction (MI) were stopped for lack of effect, Cylexin showed encouraging evidence of a therapeutic effect in a study of patients undergoing surgical removal of chronic blood clots from the lungs in a cardiopulmonary bypass setting. Researchers at Cytel believe that this difference in results may have occurred because reperfusion injury is more relevant in the cardiopulmonary bypass setting than in the MI setting and because the Cylexin drug concentration achieved was higher in the lung trial than that achieved in the MI trial.

"We have now focused our efforts on using Cylexin to improve the outcome of patients who suffer reperfusion injury during the cardiopulmonary bypass procedure," said Dr. Roe. "Preclinical research in neonatal animal models indicates that Cylexin has potential to improve cardiac and pulmonary function and to enhance neurologic recovery in pediatric heart repair surgeries. Early next year, we plan to begin a pharmacokinetic study with Cylexin, followed by a double-blind Phase II/III efficacy study in infants undergoing corrective heart surgery requiring cardiopulmonary bypass. We estimate that in excess of 20,000 of these procedures are undertaken annually in North America and presently there are no drugs available to ameliorate the accompanying reperfusion damage."

Other Cytel Programs

Dr. Roe also outlined Cytel's plans for its newly formed Glycotechnology Business Unit, announced in November. The goals of this program are twofold: near term to generate revenues from manufacturing complex carbohydrates for pharmaceutical, medical, and consumer products companies; and long term to develop other carbohydrate based drug products.

"Our technology can economically produce complex carbohydrate molecules which are not commercially feasible with conventional synthesis methods," said Dr. Roe. "Based on this proprietary technology, we have already established two manufacturing agreements: the Ross Products Division of Abbott Laboratories plans to use our technology to produce a carbohydrate additive for infant formula; and we plan to produce for the Nextran unit of Baxter Healthcare Corporation a carbohydrate to be used for extracting antibodies from patients' blood. These collaborations are potentially very profitable for us, and we plan to pursue additional collaborations during 1997."

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 the timing and cost of conducting human clinical trials, 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 and that anticipated revenues or profits under collaborative agreements will not be achieved. These factors are more fully discussed in Cytel's most recent Form 10-K and Form 10-Qs.

CONTACT: Cytel Corporation

Karin Eastham, Vice President and Chief Financial Officer

619/552-3000