Enzo Biochem Unit Allowed Interference Action on Patents Covering a Promising Interferon; Seeks to Establish Rights to Invention.

FARMINGDALE, N.Y. -- Enzo Biochem, Inc. (NYSE:ENZ) announced today that the U.S. Patent and Trademark Office has declared an interference between a patent application for the interferon protein known as Interleukin-6 ("IL-6") owned by Enzo's wholly-owned subsidiary, Enzo Therapeutics, Inc., and four U.S. patents owned by Yeda Research & Development Co., Ltd., the commercial arm of the Weizmann Institute of Science, in Israel.

An interference is a proceeding brought before the Patent Office when two patent applications containing allowed claims, or an issued patent and an allowed patent application, claim essentially the same invention. The purpose of the interference is to determine who was the first to make the invention. The owner of the invention is also determined as a consequence.

Dr. Pravin Sehgal, Professor in the Departments of Cell Biology and Anatomy, and Medicine, at the New York Medical College, Valhalla, New York, is the inventor on Enzo's patent application, all the claims for which have now been allowed by the Patent Office. Dr. Sehgal published his discovery of IL-6 in 1980. Three of the Yeda patents issued in 1995 and the fourth patent issued in 1996. Drs. Michel Revel and Pierre Tiollais are the inventors on the Yeda patents.

IL-6 is a cytokine that plays important roles in host defense, acute phase reactions, immune response and hematopoiesis (production of all types of blood cells). IL-6 is currently the subject of numerous research and clinical investigations on mediating the body's responses to cancer, infection, injury and disease. Through recombinant technology, Enzo Therapeutics scientists have expressed and produced highly purified IL-6 for further applications. A favorable outcome in the interference would pave the way for Enzo's development of its first cytokine-based pharmaceutical and could potentially establish an additional therapeutic platform for the Company.

About Enzo

Enzo Biochem is engaged in the research, development and manufacture of innovative health care products based on molecular biology and genetic engineering techniques, and in providing diagnostic services to the medical community. The Company's proprietary labeling and detection products for gene sequencing and genetic analysis are sold to the life sciences market throughout the world. The Company's therapeutic division is in various stages of clinical evaluation of its proprietary gene medicine for HIV-1 infection and its proprietary immune regulation medicines for hepatitis B and hepatitis C infection and for Crohn's disease. The Company also holds a patent covering a method and materials for correcting point mutations or small insertions or deletions of genetic material that would allow for editing and correcting certain abnormalities in genes. The Company owns or licenses over 230 patents worldwide. For more information visit our website www.enzo.com.

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