Enzo Biochem Announces New Patent Allowances in Both the U.S. and Canada.

Business Editors

FARMINGDALE, N.Y.--(BUSINESS WIRE)--July 25, 2000

TECHNOLOGIES COVER NUCLEIC ACID APPLICATIONS AND ANTISENSE RNA 

Enzo Biochem, Inc. (NYSE:ENZ) announced today that it has received notices of allowances for two patent applications - one in the U.S. covering broad applications in the field of nucleic acid technology and the second in Canada for antisense RNA (genetic antisense).

The U.S. Patent and Trademark Office issued a notice of allowance dealing with an invention that has numerous applications, including nucleic acid detection, quantification and purification, and determining genetic defects and mutations. The U.S. patent is expected to issue this year.

The Canadian patent application covers Enzo's pioneering technology for antisense RNA. The Canadian Intellectual Property Office issued the notice of allowance after a conflict proceeding was resolved in Enzo's favor. The Canadian patent strengthens Enzo's position as the worldwide holder of basic genetic antisense patents, already issued in Europe, Japan and the U.S. A second patent in Europe related to antisense RNA is expected to be issued this year.

"This is good news for Enzo on all counts," said Elazar Rabbani, Ph.D., Chairman and CEO of Enzo. "The U.S. patent allowance will further strengthen the Company's position in nucleic acid technology, and covers a technology that has already found wide favor in the marketplace. Canada's affirmation of Enzo's rights to our pioneering work in genetic antisense will allow us to move forward with this technology's promising applications, such as the Enzo-sponsored HIV clinical trial now underway in the U.S."

"Today's announcement," added Dr. Rabbani, "further enhances, we believe, the thrust of Enzo's research and development efforts over more than 20 years, the validation for which is growing increasingly evident in the broad array of products we are bringing to market and which other companies under distribution agreements are marketing."

The allowed U.S. patent application, among other uses, covers compositions and processes for trapping nucleic acid on solid supports, a process used in the majority of nucleic acid probe test now being performed. Enzo already has a large number of patents for labeled nucleic acid probes and for their application. This allowance thus importantly further extends the Company's leading position in nucleic acid technology.

The notice of allowance issued by the Canadian Intellectual Property Office is for a patent that covers basic use of antisense RNA in all cells and cellular material (eukaryotic and prokaryotic alike), and broadly covers methods for regulating gene function in all cells using antisense RNA. It extends to antisense polynucleotide constructs and to structures that increase the stability of antisense RNA, as well as non-human organisms containing antisense constructs, among others. The Phase I study of Enzo's HGTV-43 gene medicine for HIV-1 is the most direct application of this technology to date. Favorable preliminary results for this trial, which is being conducted at the University of California, San Francisco, has been reported and Enzo is working on plans for a Phase II clinical study involving antisense that would include AIDS patients.

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 serves to the medical community. The Company's has approximately 200 patents worldwide, many of which cover proprietary labeling and detection products for gene sequencing and genetic analysis and are sold to the life science market throughout the world. The Company's therapeutic division is conducting two human clinical trials, one for HIV infected patients, and one for patients infected with hepatitis B virus. Other potential future therapeutic applications of Enzo's proprietary technologies are directed towards cholesterol management and the treatment of inflammatory bowel disease, including Crohn's disease and ulcerative colitis. The Company also holds a patent covering a method and materials for correcting point mutations or small insertions or deletions of genetic material, which would allow for editing and correcting certain abnormalities in genes.

Except for historical formation, the matters discussed in this news release may be considered 'forward-looking" statements with the meaning of Section 27A c1f the Securities Act of 1933, as amended, and Section 211: 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. Prospective investors are cautioned that any such forward-looking statements are nor guarantees of future performance and involve a number of risks and uncertainties that could materially affect actual results.