Cytel Reports Positive Results from Cylexin Phase I/II Trial.

SAN DIEGO--(BW HealthWire)--Sept. 30, 1997--Cytel Corporation (NASDAQ:CYTL) today announced results from a pilot Phase I/II clinical study of Cylexin(TM), a selectin blocker, used to block reperfusion injury in infants undergoing corrective surgery for congenital heart disease.

The results indicated good tolerability and strong trends in favor of reducing some of the important clinical manifestations of reperfusion injury as well as length of hospital stay. The study, conducted by Harvard investigators at Boston Children's Hospital, was an unblinded dose selection and tolerance study. Based on this favorable outcome, Cytel is preparing to start a multicenter registration trial for this indication in the next several months.

The trial was conducted in 17 infants ranging in age from 1 day to 9 months. The patients were given Cylexin beginning just prior to surgery and continuing until 24 hours after surgery. Four ascending dose groups were studied. Data from the two lowest dose groups were pooled (n=6) and intergroup comparisons were then made with the mid-dose (n=5) and high dose (n=6) groups. The endpoints measured were duration of post-operative intubation (an indicator of required respiratory support), increase in thigh circumference after surgery (a measure of edema), total inotropic drug support (which is used to improve heart function) and cardiac output over the first 24 hours after surgery. In addition, total ICU time and duration of hospital stay were assessed as measures of post-operative morbidity.

Comparison of data from the three groups of infants showed strong trends (p<0.07) in favor of the highest dose for reduction in intubation time, reduction in post-operative edema and shortened hospital stay. There was also a one day (30%) decrease in median ICU time for the high dose infants. There were no obvious changes in cardiac output or requirement for inotropic support.

"Because of the small sample size and the anticipated interpatient variability, we did not expect to see any differences between treatment groups in this tolerance trial when we were asked to look at efficacy parameters by our corporate partner," said Robert L. Roe, M.D., Executive Vice President and Chief Operating Officer. "However, we were very pleased with these preliminary efficacy findings, which are supported by a known mechanism of action, are consistent with our preclinical findings and mirror the positive results achieved in an earlier study of reperfusion injury in adults who underwent lung surgery to remove chronic blood clots. We are quite encouraged by these findings and believe Cylexin has strong potential as a therapeutic for reducing reperfusion injury in infants undergoing open heart surgery and will address an important and unmet clinical need."

Cylexin(TM) is the first in a new class of compounds aimed at mitigating reperfusion injury which occurs when blood flow is restored following a period of ischemia or deprivation of an adequate blood supply. Reperfusion injury can occur after open heart surgery requiring cardiopulmonary bypass and circulatory arrest, organ transplantation, severe trauma or stroke. In 1990, researchers at Cytel discovered the identity of a key molecule (termed a "selectin ligand") which is expressed on blood vessel walls following reperfusion and which starts the migration of white blood cells out of the blood stream and into areas of reperfused tissue, a critical mechanism in reperfusion injury.

Cytel Corporation is a leader in the discovery and development of cell adhesion inhibitors for treatment of acute and chronic inflammation, and its Glytec unit is a leader in the manufacture of bioactive carbohydrates for use in medical and consumer products. Epimmune Inc. 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.

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 Corp.

Robert L. Roe, 619/552-3000