Methylgene Inc. Receives Key Patent for Inhibition of DNA Methyltransferase

Business Wire, April 25, 2001

Business Editors & Health/Medical Writers

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MONTREAL--(BW HealthWire)--April 25, 2001

Patent Provides Further IP Protection for Company's Innovative

Area of Research

MethylGene Inc. announced today that it has received a patent from the United States Patent and Trademark office entitled "Inhibition of DNA methyltransferase."

U.S. Patent 6,184,211 covers the administration of an agent that could help the human body to restore normally occurring mechanisms to combat or terminate the growth of cancerous tumours. The patent adds to MethylGene's patent portfolio of 14 issued U.S. patents and 21 U.S. patent applications protecting the Company's enzyme targets, inhibitor designs and chemistry approaches.

DNA methyltransferase is an enzyme that mediates the transfer of a methyl group to DNA bases. This transfer results in the silencing of a gene's expression. For instance, when the DNA methyltransferase enzyme is over-expressed in conjunction with cancerous conditions, tumour suppressor genes are "turned off" (hypermethylated) and cancer cells are able to proliferate. The hypermethylation of tumour suppressor genes has been observed to occur in a wide variety of human cancers. Recent findings also suggest that the extent of tumour suppressor gene methylation correlates with disease progression for a variety of tumour types. In addition, it appears this enzyme also affects the expression of other key genes involved in cancer progression, such as DNA repair genes and hormone receptors.

"The issuance of this patent is an important milestone for MethylGene and builds on our intellectual property portfolio in this field," said Donald F. Corcoran, President and CEO of MethylGene. "We believe DNA methyltransferase plays an important role in the tumorigenic process for many cancers. We have demonstrated both in vitro and in vivo that selective inhibition of this enzyme results in tumour growth inhibition or tumour regression. Furthermore, we and our pharmaceutical partner, MGI Pharma Inc. [NASDAQ: MOGN], have entered Phase 2 cancer clinical trials in Canada and the U.S. for MG98, our first DNA methyltransferase inhibitor, and are designing other novel inhibitors of this target."

MethylGene and MGI Pharma are developing MG98 in North America for the purpose of blocking production of the nuclear enzyme DNA methyltransferase. Preventing DNA methyltransferase production allows tumour suppressor genes that have been silenced by methylation, to be re-activated. MG98 has already demonstrated anti-cancer activity in Phase 1 trials. MethylGene and MGI Pharma also initiated a Phase 2 trial of MG98 in head and neck cancer patients, and intends to further evaluate MG98 in other cancers where silencing of tumor suppressor genes by DNA methyltransferase has been documented. In preclinical models, MG98 used alone and in combination with other anti-cancer agents has caused tumour shrinkage or inhibited growth of human tumours.

Along with MG98, MethylGene is also developing complementary small molecule DNA methyltransferase inhibitors, which share the same goal of preventing methylation and silencing tumour suppressor genes. However, the small molecules are being screened for their potential to bind DNA methyltransferase and block its activity, rather than prevent its production.

The inventor of this patent is Dr. Moshe Szyf, Assistant Professor of Pharmacology and Therapeutics at McGill University. MethylGene is the exclusive, world-wide assignee of the patent.

About MGI Pharma

MGI Pharma Inc. is an oncology-focused pharmaceutical company that acquires, develops and commercializes proprietary products that meet patient needs and build shareholder value. MGI focuses its sales efforts solely in the United States and collaborates with other pharmaceutical or biotechnology companies for its products in international markets.

About MethylGene

MethylGene Inc. is a privately held, Canadian biopharmaceutical and chemistry-driven rational drug design company focused on the inhibition of enzyme targets associated with disease. We combine functional genomic technologies with the application of mechanism-based small molecules and mRNA inhibitors to discover, patent, develop and commercialize novel therapeutics for cancer and infectious diseases, particularly bacterial infection. MethylGene's lead compound, MG98, which is partnered for North America with MGI Pharma Inc. is currently in Phase 2 human clinical trials. The Company has other research and development programs to develop small molecule inhibitors of DNA methyltransferases, histone deacetylases, beta-lactamases and other enzyme targets.

This press release may contain forward-looking statements pertaining to MethylGene Inc. Such statements are subject to certain risk factors and uncertainties, particularly those inherent in the process of discovering, researching, developing and commercializing drugs that can be proven to be safe and effective for use as human therapeutics and the endeavor of building a business around such potential products. As a result, the reader is cautioned that actual results could differ materially from those projected or assumed around this release.