Enzo Biochem Awarded Patent Covering Method to Correct Certain Gene Abnormalities.

Business/Health Editors

FARMINGDALE, N.Y.--(BUSINESS WIRE)--March 15, 2000

Technology Would Permit "Editing" of DNA in a Cell

Enzo Biochem, Inc. (NYSE:ENZ) announced today that it has received a patent from the U.S. Patent and Trademark Office that covers nucleic acid compositions and methods for editing and correcting certain abnormalities in genes.

"Given the vast body of knowledge available through charting the human genome, the ability to correct inherent errors in the genes of a subject, and certain other medically important genetic material where alterations may be indicated, becomes very relevant," said Dean L. Engelhardt, Ph.D. Senior Vice President of Enzo. "The procedure outlined in the patent could provide the means for these corrections."

U.S. Patent No. 5,958,681 claims a method and materials suitable for correcting point mutations or small insertions or deletions of genetic material. For example, genetic abnormalities caused by single nucleotide alterations or small deletions could be corrected through the insertion or exchange of the correct or desired sequences into the genome of the cell where the error exists.

Enzo said that this new technology provides the Company with an additional therapeutic platform and another unique approach for treating genetic-based diseases, as well as other applications. Enzo also said that this gene editing technique differs from other gene therapies that usually require the insertion of an entire new gene to correct a nonfunctional or incorrectly functional gene.

This invention could lead to creation of a normally functioning gene by correcting a mutated or altered gene sequence. It could correct, for example, an inborn error of metabolism for a condition such as hemophilia. Potentially, it could also be used to correct a mutated p53 gene that controls cell growth. In the mutated gene, the cell growth is uncontrolled, resulting in cancer. In the corrected p53 gene, the cell growth would be restored to its normal, non-cancerous state.

These genetic alterations could be used to inactivate oncogenes, genes in a cancer cell that function to maintain the cancerous state of the cell, or to inactivate genes in a virus essential for continued growth of the virus. Such genetic alterations could also have application in genetic diseases such as Tay-Sachs and sickle cell anemia.

In addition to its application in human therapeutics, this new technology could fine use in veterinary and agricultural applications.

Enzo said that it has begun discussions leading to possible further application of this technology towards specific therapeutic products. "The fundamentals of the methods and materials covered in the patent have been recognized by researchers, and the `681 patent provides Enzo with a commanding position to pursue what appears to be a highly promising new genetic correcting mechanism," said Dr. Engelhardt. "This technology represents another novel approach for treating genetic defects and viral diseases utilizing Enzo's pioneering science focused on modifying the genetic makeup of an organism."

The method and materials covered by the '681 patent work by correcting the specific gene within cells with defined short gene sequences. These sequences are held in place through formation of a triple helix complex. The principle of the invention is that when the short gene sequence containing the correct sequence is held in close proximity to the target DNA to be corrected, the probability of a double crossover or an editing event becomes quite high. This involves triplex-forming DNA sequences that bind to specific regions in the DNA in a sequence-specific manner to provoke DNA repair. The triple helix holds the sequences in close proximity and at a precise point in the gene long enough for recombination, exchange or insertion to take place with a high frequency.

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 medical research 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 therapeutic applications of Enzo's proprietary technology are directed towards the treatment of cholesterol management, inflammatory bowel disease, including Crohn's disease and ulcerative colitis, and diabetes.

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. Prospective 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.