Enzo Biochem Reports U.S. Court of Appeals in a Split 2-To-1 Decision Affirms Lower Court Ruling.

Business & Health Editors

NEW YORK--(BW HealthWire)--April 4, 2002

On April 2, 2002, a divided three-judge panel of the U.S. Court of Appeals for the Federal Circuit affirmed by a 2-to-1 vote the summary judgment of the U.S. District Court for the Southern District of New York that Enzo Biochem, Inc. (NYSE:ENZ) U.S. Patent No. 4,900,659 is invalid for lack of written description of the claimed invention. The `659 patent is directed to nucleic acid probes for the detection of the bacteria that causes gonorrhea.

In a dissenting opinion, Circuit Judge Timothy D. Dyk, who noted that the consequence of the majority's approach is "considerable unfairness," objected to the majority's resolution of "significant issues relating to the written description requirement." The dissent noted that the imposition of unique written description rules in the biotechnology field "is open to serious question." The dissent also objected to the invalidation of the `659 patent on summary judgment without any factual showing that the patent violated the general rule of written description.

The majority opinion, written by Circuit Judge Alan D. Lourie with whom Circuit Judge Sharon Proust joined, considered the description of the probes by reference to their relative affinity for different strains of specified bacteria in a hybridization assay inadequate as simply stating a "function" of the probe.

Enzo is disappointed by the court's decision and believes it to be incorrect. The decision will have no financial impact on Enzo, which has over 200 patents in its patent estate including a European patent which covers this very same product and which has been upheld on challenge. Enzo said that it would seek a rehearing before the full Court of Appeals.

The European patent is unaffected by the Court of Appeals decision. Any attempt to manufacture or market products in Europe covered by the European patent is subject to Enzo's patent. Enzo does not receive any revenue from the `659 patent and the decision has no impact on its ongoing activities or current revenue stream.

The Enzo suit named as defendants Gen-Probe Incorporated, Chugai Pharmaceutical Co., Ltd., Chugai Pharma, U.S.A., bioMerieux, Inc., bioMerieux SA and Becton-Dickinson and Co.

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, with approximately 200 patents worldwide, are sold to the life sciences market throughout the world. The Company's therapeutic division is conducting clinical trials for HIV-1-infected patients and for patients infected with hepatitis B and hepatitis C viruses. 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.

Except for historical information, the matters discussed in this news release may be considered "forward-looking" statements within the meaning of Section 27A of the Securities Act of 1933, as amended and Section 21E of the Securities Exchange Act of 1934, as amended. Such statements include declarations regarding the intent, belief or current expectations of the Company and its management. Investors are cautioned that any such forward-looking statements are not guarantees of future performance and involve a number of risks and uncertainties that could materially affect actual results. The Company disclaims any obligations to update any forward-looking statement as a result of developments occurring after the date of this press release.