United States Board of Patent Appeals Denies Siemens Healthcare Diagnostics' Request for Rehearing on Enzo's Pending Universal Interference Patent

Action Clears Way for Enzo to Receive Patent on Widely Used Nucleic Acid Signal Technology

NEW YORK--(BUSINESS WIRE)-- Enzo Biochem, Inc., (NYSE: ENZ) today reported that the Board of Patent Appeals and Interferences of the United States Patent and Trademark Office has issued a Decision denying a Request for Rehearing filed by Siemens Healthcare Diagnostics (NYSE:SI) in a patent interference proceeding relating to Enzo Life Science's application for nucleic acid signal amplification and Siemens U.S. Patent No. 5,124,246, relating to branched DNA (bDNA) diagnostic systems.

Siemens filed the rehearing request in response to a February 22, 2010 Decision by the Patent Office awarding priority of the invention to Enzo. The result of this latest Decision is that the judgment of the Patent Office is now final. Subject to any appeals that Siemens might file in federal court, Enzo will receive a full 17-year patent for all the inventions covered by the claim, commencing on the date of the patent's issuance.

"This technology is the basis for a number of significant products in clinical diagnostics and in the life sciences field which currently are marketed or licensed by various commercial entities," said Elazar Rabbani, PhD, Chairman and CEO of Enzo. "Additionally, we plan to expand the application of this key technology beyond the scope of gene-based applications into the field of immunodiagnostics."

According to trade reports, industry-wide annual sales of diagnostic products utilizing the nucleic acid signal amplification technology are estimated to exceed $100 million in the United States alone.

Using Enzo's signal amplification technology, direct detection of nucleic acid can be carried out without the need for target amplification and without compromising the sensitivity of the detection assay.

The Diagnostics Division of Bayer HealthCare, which was subsequently acquired by Siemens Medical Solutions, produces and markets the "VERSANT(R) Branched DNA (bDNA) Assays" that utilize the technology now awarded to Enzo.

About Enzo Biochem

Enzo Biochem, Inc., is a growth-oriented integrated life sciences and biotechnology company focused on harnessing biological process to develop research tools, diagnostics and therapeutics, and serves as a provider of test services, including exotic tests, to the medical community. Since our founding in 1976, our strategic focus has been on the development of enabling technologies in the life sciences field. Enzo Life Sciences develops, produces and markets proprietary labeling and detection products for gene sequencing, genetic analysis and immunological research, among others. Its catalog of over 40,000 products serve the molecular biology, drug discovery and pathology research markets worldwide. Enzo Clinical Labs provides laboratory services for a growing roster of physicians in the New York Metropolitan area, as well as parts of New Jersey and Pennsylvania. Its tests include, in addition to routine tests, capabilities for detecting molecular infection disease, molecular oncology, autoimmune disorders and genetics. Enzo Clinical Labs also provides clinical diagnostic services that allow Enzo to capitalize on its extensive advanced molecular and cytogenetic capabilities and the broader trends in predictive and personalized diagnostics. Enzo Therapeutics is a biopharmaceutical venture that has developed multiple novel approaches in the areas of gastrointestinal, infectious, ophthalmic and metabolic diseases. It has focused its efforts on developing treatment regimens for diseases and conditions for which current treatment options are ineffective, costly, and/or cause unwanted side effects. In the course of the company's research and development activities, Enzo has developed a substantial portfolio of intellectual property assets, with 249 issued patents worldwide and over 200 pending patent applications.

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.

    Source: Enzo Biochem, Inc.

Released May 17, 2010