Introgen’s adenoviral vector demonstrates safety in Phase II study

Biosafety data presented at American Society of Gene Therapy meeting

Seattle, WA, June 1, 2001 – Introgen Therapeutics, Inc. (NASDAQ: INGN) today reported on the safety of its extensively tested adenoviral vector for gene therapy. Results from a Phase II study of INGN 201, Adenoviral-p53, injected intra-tumorally were presented. These results were reported at the Fourth Annual Meeting of the American Society of Gene Therapy meeting in a poster session titled, “Biological Safety of INGN 201, an Adenoviral Vector For Gene Therapy: Data From 190 Subjects Treated Intra-tumorally with INGN 201 (Ad5CMV-p53).”

Data were presented from 190 subjects treated with INGN 201 in a study designed to evaluate the pharmacokinetic profile of the vector and the potential for horizontal transmission of the product to household members of the treated subjects. Analysis of vector DNA recovered from samples, taken from study subjects at various time points post treatment, showed INGN 201 to be genetically stable. In addition, no horizontal transmission was documented in over 400 samples from household members of the patients treated with INGN 201.

“By demonstrating that INGN 201 can be administered without affecting untreated persons, and with the safety record Introgen has with the use of adenoviruses, Introgen moves a step closer to reaping the benefits that gene therapy may hold,” said Deborah R. Wilson, Ph.D., associate vice president of clinical research for Introgen and co-author of the poster.

INGN 201 is a replication-impaired adenoviral vector carrying the human p53 tumor suppressor gene. Introgen has amassed the world’s largest safety database on adenoviruses with over 500 patients treated with INGN 201, currently in pivotal Phase III trials. Human safety has been evaluated following 8 routes of administration, including injections into various organs and tissues, as an instillation into the bronchial tree, mucosal infiltration into healthy surgical wound margins, and a repeated direct intravenous infusion.

Introgen is a leader in the development and production of gene-based drugs for the treatment of cancer and other diseases. Introgen’s product candidates engage precise molecular targets to produce a highly specific therapeutic effect. Introgen specializes in combining appropriate gene delivery systems and therapeutic genes to make its gene-based drugs. Introgen’s lead product candidate, INGN 201 (Adenoviral-p53), is currently in Phase III clinical trials for the treatment of head and neck cancer. INGN 201 has been used in numerous clinical trials worldwide either alone or in combination with conventional treatments such as chemotherapy and radiotherapy. Introgen is also conducting a Phase II clinical trial for INGN 201 in lung cancer and Phase I trials for INGN 201 in additional cancer indications including prostate, ovarian, bladder, brain, and breast cancer. Earlier this year, Introgen announced the published results of preclinical studies which indicate a possible application of INGN 201 whereby the human immune system may be directed to attack tumor cells. Introgen’s second product candidate, INGN 241 (Adenoviral-mda7), for the treatment of solid tumors, is in Phase I clinical development. Introgen controls a broad intellectual property portfolio that includes more than 200 pending and issued patents for a variety of gene therapy technologies. Introgen owns a fully staffed and validated Good Manufacturing Practices (cGMP) production facility that is producing Phase III and commercial inventory of INGN 201. Introgen has received a U.S. patent for the commercial scale production of adenovirus.

Certain statements in this press release that are not strictly historical may be “forward-looking” statements, which involve risks and uncertainties. Such forward-looking statements include, but are not limited to, those relating to safety and efficacy of our drug product candidates, the efficacy of our drug product candidates in treating cancer with an adenoviral vector, and Introgen’s ability to complete its clinical trials or successfully commercialize INGN 201 or any other product candidates. There can be no assurance that Introgen will be able to commercially develop gene-based drugs, that necessary regulatory approvals will be obtained or that any clinical trials or studies undertaken will be successful or that the proposed treatments will prove to be safe and/or effective. The actual results may differ from those described in this press release due to risks and uncertainties that exist in Introgen’s operations and business environment, including, but without limitation, Introgen’s stage of product development and the limited experience in the development of gene-based drugs in general, its dependence upon proprietary technology and current competition, history of operating losses and accumulated deficits, Introgen’s reliance on collaborative relationships, and uncertainties related to clinical trials, safety, efficacy, the ability to obtain the appropriate regulatory approvals, patent protection and market acceptance, as well as other risks detailed from time to time in Introgen’s filings with the Securities and Exchange Commission, including its prospectus dated October 12, 2000 and the 10-Q filed on May 14, 2001. Introgen undertakes no obligation to publicly release the results of any revisions to any forward-looking statements that reflect events or circumstances arising from the date hereof.

Editor's Note: For more information on Introgen Therapeutics, or for a menu of archived press releases, please visit the Company Website at: www.introgen.com, or call Introgen’s toll-free Investor Relations hotline at 1-877-776-GENE (4363).