Cytel announces Phase II results with Cylexin in lung injury trial.

SAN DIEGO--(BUSINESS WIRE)--April 30, 1996--Cytel Corporation (NASDAQ:CYTL) announced today that results of a Phase II clinical trial with its selectin blocker, Cylexin(TM), demonstrated evidence of a clinical benefit suggesting reduction of reperfusion injury following pulmonary thromboendarterectomy (PTE), the surgical removal of chronic blood clots from the lungs. The trial was conducted under the direction of Dr. Kenneth M. Moser, Professor of Medicine, Director of Pulmonary and Critical Care Medicine at the University of California, San Diego (UCSD), one of the leading centers worldwide for this procedure.

The three most important measurements of efficacy were the overall clinical impression of lung injury and two objective measures of potential lung injury. The overall clinical impression achieved statistical significance (p=0.036) and demonstrated the risk of injury to be twice as great in the placebo group than in the Cylexin group. Statistical significance was not achieved for the objective measures of lung injury; however, one of the objective measures of lung injury, the lung injury score was in the direction of less injury in the Cylexin group (p=0.128) based largely on the measure of successful oxygen exchange. "Reliance exclusively upon such apparently objective measures as the lung injury score can be misleading," stated Dr. Moser, "because other confounding clinical conditions can alter that score. We believe the clinical impression of the physician experienced in the care of these patients is the most accurate measure of which patients developed acute lung injury."

This lung injury study was conducted to give Cytel the opportunity to evaluate the activity of Cylexin in a well-defined surgical population with a high occurrence of acute reperfusion lung injury. In this blinded trial, 51 patients were randomly assigned to receive either Cylexin or placebo intravenously prior to initiation of surgery and then a continuous infusion of drug for the subsequent 10 hours. "The positive trends in this study were important to us because reperfusion injury in these patients is the leading cause of post-operative morbidity and mortality," said Dr. Moser. "This study is the first indication that selectin blockage may modulate this form of acute lung injury."

Patients that are treated with PTE number fewer than 500 per year, thus this indication would represent an orphan drug indication for Cylexin. Cytel's initial target market for Cylexin is the reperfusion injury that occurs upon restoration of blood flow following treatment for heart attack. Cytel is conducting a Phase II trial with Cylexin in reperfusion injury resulting after angioplasty treatment for myocardial infarction, which will be completed later this year. The company is also planning to evaluate Cylexin's ability to prevent reperfusion injury following thrombolytic therapy for acute myocardial infarction.

Cytel is jointly developing Cylexin with Schwarz Pharma AG (Schwarz) of Monheim, Germany. Schwarz has sole responsibility for marketing products in Europe; Schwarz and Cytel share marketing responsibility in North America. Marketing rights for the Far East were granted to Sumitomo Pharmaceuticals Co. Ltd. Cytel retains all worldwide manufacturing rights and has entered into a supply agreement with Schwarz for the joint territories.

Cylexin, a selectin blocker, is a complex carbohydrate and is believed to be the first of its class to enter clinical trials. Cytel has developed a chemical and enzymatic synthesis technology that allows cost effective manufacture of Cylexin. This proprietary technology is also applicable to the synthesis of other complex carbohydrates for use in therapeutic or non-therapeutic settings and was the basis for a collaboration with Abbott Laboratories announced earlier this year, whereby Abbott obtained an option to a worldwide license for use of Cytel's technology in the manufacture of carbohydrates for addition to nutritional products.

Cytel Corporation, founded in 1987, is a leader in the discovery, design and development of immunotherapeutics, a new class of drugs which the Company believes will be more selective and have fewer side effects than drugs currently on the market. Utilizing Cytel's advanced understanding of the immune system's operation both in disease and in health, the Company is developing drug candidates under two distinct approaches: the immune suppression program targets inflammatory diseases and reperfusion injury through the use of cell adhesion blockers that prevent the excessive migration of white blood cells into surrounding tissue, and the immune stimulation program is directed to the development of therapeutic vaccines to treat infectious diseases and cancers by stimulating production of antigen- specific cytotoxic T-lymphocytes by the immune system.

Actual results may differ materially from the above forward- looking statements due to a number of important factors, including but not limited to the timing and cost of conducting human clinical trials and the possibility that further testing of Cylexin may not support the results of the data described above or may reveal undesirable and unintended side effects or other characteristics that may prevent or limit its commercial use. These factors are more fully discussed in the Company's most recent Form 10-K and Form 10-Qs.

CONTACT: Cytel Corporation, San Diego

Karin Eastham, Vice President and Chief Financial

Officer, 619/552-3000