Press Releases

AMERICAN BIOGENETIC SCIENCES' TpP™ TEST IDENTIFIES PATIENTS WITH UNDERLYING CLOTTING DEFECTS

Dr. Test Also Demonstrates Utility In Monitoring Anticoagulant Therapy

COPIAGUE, N.Y., May 10, 1999 -- American Biogenetic Sciences, Inc. (ABS) (Nasdaq: MABXA) announced today that an analysis of data from over 200 patients in an ongoing thrombosis study conducted by Yale S. Arkel, M.D., Director of the Blood Disorder Center at Overlook Hospital showed that increased levels of the Company's Thrombus Precursor Protein (TpPTM) vascular diagnostic test corresponded with patients who had an increased risk of pathological clotting due to hereditary or acquired defects in their clotting mechanisms.

In the study levels of TpP increased from a mean of 1.88 :g/ml in patients with no hereditary defects of the clotting mechanism to 7.38 :g/ml in patients with 3 or more defects in the 101 patients studied who were not on anticoagulant therapy. In 100 patients on anticoagulation therapy the mean TpP levels ranged from 1.04 :g/ml with no defect to 2.64 :g/ml in patients with 3 or more defects. TpP levels below 3.33 :g/ml are considered normal. These findings establish TpP™ to be a useful marker in identifying patients at risk for clotting abnormalities, and show TpP utility in monitoring patients on anticoagulant therapy.

Defects of the coagulation system affect over 50 million people in the U.S.

The more commonly known defects of the coagulation system occur in approximately 30% of the population. This affects over 50 million patients in the U.S. alone. Pathological clotting defects such as Factor V Leiden, prothrombin gene mutation, protein C/S/ATIII deficiency, hyperhomocysteine, anticardiolipin antibodies, and lipoprotein(a) comprise the major known significant risk factors.

“Given the large number of people in the population who have these clotting defects and then go on to have further complications such as myocardial infarction, stroke, pulmonary embolism, deep vein thrombosis, or complications in pregnancy early detection and appropriate medical intervention can have a major impact,” said John S. North, President and CEO of ABS. “The use of TpP as a test in screening for this condition needs to be considered and assessed. In addition, thousands of patients in the U.S. are on some type of anticoagulants therapy and the ability to monitor the effectiveness of this therapy is an important clinical consideration.”

“We have now looked at over 200 patients with hypercoagulability (tendency to pathological clotting) both on anticoagulant therapy and off. What we show is a marked increase in TpP levels as the number of underlying defects in these patients increase. This is an important finding in identifying and following clinically this high risk group of patients,” said Dr. Arkel.

American Biogenetic Sciences, based in Copiague, New York, researches and develops diagnostic tests for cardiac conditions and infectious diseases, as well as new treatments for neurological disorders including epilepsy, migraine, mania, Parkinson's and Alzheimer's disease. ABS also seeks out new technologies and conducts research and development throughout its Global Scientific Network, in the U.S., Europe, Israel, Russia and China.

Statements in this release that are not strictly historical are “forward-looking” statements within the meaning of the Private Securities Litigation Reform Act of 1995, and should be considered as subject to various risks and uncertainties that could cause actual results to differ materially from those anticipated. For further details and a discussion of these risks and uncertainties, see the Company's Securities and Exchange Commission filings, including its annual report or Form 10-K

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