Enzo Biochem to Begin Clinical Trial on New Immunomodulatory Agent.

Business Editors/Health/Medical Writers

FARMINGDALE, N.Y.--(BUSINESS WIRE)--May 20, 2004

Enzo Biochem, Inc. (NYSE: ENZ), a leading biotechnology company, announced today that the Company has received approval in Israel to begin a Phase I clinical trial to study safety of its new immunomodulatory agent, EGS21, a beta-D-glucosylceramide compound (GC), in human subjects. The study, to be conducted at Hebrew University-Hadassah Medical Center in Jerusalem, is expected to begin early this summer.

The approval was based on preclinical studies in animal model systems that were carried out by Enzo scientists and collaborators. The results of these studies have been presented at several international meetings and demonstrated that the compound acts on immune regulatory (NKT) cells and therefore could impact the immune response in the body by modulating its function and adjusting it to a normal state.

Enzo said that EGS21, together with the Company's current oral immune regulation platform, could accelerate the Company's development and launching of products for treatment of a broad range of immune mediated diseases including hepatitis B virus (HBV) and hepatitis C virus (HCV) associated liver disease, various cancers, Crohn's disease and other forms of inflammatory bowel diseases, HIV, diabetes and graft versus host disease.

Enzo and its collaborators were able to identify a significant correlation in individuals with Gaucher Disease who are also infected with HCV. These patients showed a significant protection of their livers to HCV-associated liver damage when compared to other HCV-infected individuals. Since Gaucher Disease is a condition in which glucosylceramide accumulates in the liver, the scientists concluded that its accumulation protects the patient against immune mediated attack on the liver.

In preclinical studies, laboratory animals were induced to undergo acute liver failure mediated by an immune attack. When these animals were treated with glucosylceramide before induction, liver failure was prevented. Enzo scientists and collaborators also examined the effect of glucosylceramide in a number of other immune-mediated disorders, in which the immune regulatory NKT cells are thought to play a role, including induced experimental, non-alcoholic steatohepatitis (fatty liver), and diabetes. In all of these models, administration of GC was associated with significant amelioration of the immune-mediated disease process.

"These preclinical data strongly support the view that EGS21 could have a therapeutic effect in the treatment of immune mediated diseases and that the compound functions by acting on certain cells that are central to regulating an immune response," said Dean L. Engelhardt, Ph.D., Executive Vice President of Enzo."

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 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 of materials for correcting point mutations or small insertions or deletions of genetic material that would allow for editing and correcting certain abnormalities in genes. For more information visit our website www.enzo.com.

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.