Enzo Biochem Granted European Patent for Displacer Technology to Treat Gene Abnormalities; Methodology Could Make Possible Modification or Corrections of Cell Mutations.

Business Editors/Health/Medical Writers

FARMINGDALE, N.Y.--(BUSINESS WIRE)--June 14, 2004

Enzo Biochem, Inc. (NYSE:ENZ), announced today that the European Patent Office has granted it a patent that describes, in part, a method of performing targeted delivery and incorporation of genetic material into chromosomal DNA without using a viral vector, thus making possible the editing and correcting of certain abnormalities in genes.

The patent covers, among other things, constructs and methods that will allow a single stranded nucleic acid molecule to displace one of the strands of a double helical molecule. Among its many possible useful applications is one that can use what is called displacer technology to correct point mutations or effect small deletions or additions, even inside of living cells and tissue. This type of correction could permit individual alleles or genes to be modified, enabling mutations in cells to be corrected, resulting in corrections to the protein encoded by the genes, such that the protein would function more effectively.

"This technology holds promise of being one of the gentlest and most effective means of achieving gene therapy, or of achieving the addition, deletion or improvement of gene functions to improve quality of life for individuals," said Dean Engelhardt, Ph.D., Executive Vice President of Enzo. "One target of this new displacer technology would be to correct the genetic defect leading to sickle cell anemia."

Enzo Biochem holds a complementary U.S. Patent, No. 5,958,681, issued in March 2000, which covers nucleic acid compositions and methods for editing and correcting certain abnormalities in genes. "The essence of both of these patents," commented Dr. Engelhardt, "is to provide the ability to correct inherent errors in the genes of a subject, and of certain other medically important genetic material, where alterations may be indicated."

The newly awarded European patent, EP 0 450 370 B1, in addition to the performance of targeted delivery of genetic material, also provides for simple methods for preparing stable branch migration structures; procedures of simultaneous labeling and identification of specific DNA fragments that are significantly simpler, faster and cheaper than blot analyses; and labeling procedures that permit sequence enrichment or purification by affinity chromatography and selective cloning.

Enzo said it is currently engaged in pre-clinical studies incorporating gene-altering technology to achieve specific therapeutic benefits. "The European patent grant represents further acknowledgement of Enzo's novel approach for treating genetic defects and viral diseases using our Company's pioneering science," said Dr. Engelhardt.

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 over 180 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 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. 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 statements as a result of developments occurring after the date of this press release.