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AMERICAN BIOGENETIC SCIENCES, INC. OBTAINS U.S. PATENT FOR UNIQUE RADIONUCLIDE-LABELING METHOD FOR MH-1 AND OTHER MONOCLONAL ANTIBODIES

New Method Superior to Conventional Labeling Offers
Licensing Opportunities

Copiague, New York, June 28, 2000 - American Biogenetic Sciences, Inc. (ABS) (OTCBB:MABA) announced today that it has been issued United States Patent No. 6,080,384 entitled "Methods For Radionuclide-Labeling Of Biomolecules And Kits Utilizing The Same" with a total of 45 claims. The patent is directed to novel compositions useful for radiolabeling sulfhydryl group-bearing biomolecules, and methods for imaging human tissue employing radiolabeled biomolecules. This invention is particularly useful for labeling peptides such as monoclonal or polyclonal antibodies.The method of labeling biomolecules in this invention is better than conventional labeling methods because it does not require the use of either acidic or basic solutions which may destroy the peptide that is to be labeled, this is especially true for monoclonal or polyclonal antibodies.

This proprietary labeling technology, originally developed for labeling the Fab' fragment of the MH1 antibody, has demonstrated clinical utility in the in vivo imaging of blood clots in both the arterial and venous vasculature. "The expansion of this technology for other radionuclides should permit the development of additional diagnostic and therapeutic applications for both MH1 and other monoclonal antibodies that are currently part of the American Biogenetic Sciences Product Portfolio. Moreover, this technology has license potential to interested third parties for their individual needs," stated Mr. John S. North, President and CEO of ABS. In addition, North commented, "As we define the Human Genome, science will need new tools to diagnose and treat diseases. Antigen free monoclonal antibodies of high specificity and affinity will play an ever increasing role."

Radiolabeled monoclonal or polyclonal antibodies are employed to image normal or diseased target organs. In particular, the compositions of the invention, when administered to a patient, are useful in imaging a tumor, a blood clot such as deep venous thrombosis, an atrial thrombus, a pulmonary embolism, an infectious lesion, a myocardial infarction, an atherosclerotic plaque, and a normal organ or tissue.

American Biogenetic Sciences, Inc. based in Copiague, N.Y., researches and develops diagnostics tests for cardio-pulmonary conditions and infectious diseases, as well as new treatments for neurological disorders including epilepsy, migraine, mania, Parkinson's disease and Alzheimer's disease. ABS also seeks out new technologies and conducts research and development through its Global Scientific Network in the United States, 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 companiesí Securities and Exchange Commission filings including their annual report or Form 10-K.