Introgen's intravenously administered gene therapy demonstrates safety and establishes basis for systemic treatment for metastatic cancer

Introgen Therapeutics, Inc. (NASDAQ: INGN) today reported data from a Phase I clinical study of the intravenous treatment of patients with advanced cancer and a Phase I clinical study for the treatment of bladder cancer. These data were presented at the 37th Annual Meeting of the American Society for Clinical Oncology in San Francisco, CA.

The Phase I intravenous clinical study presented by Anthony Tolcher, M.D., Associate Director of Clinical Research of the Institute for Drug Development in San Antonio, Texas and principal investigator described data on ten patients with various advanced cancers who received multiple treatments of INGN 201 delivered intravenously multiple times a month for up to ten months. The results suggest that INGN 201 is safe following repeated administration at high doses and provides a rationale for further studies to determine whether INGN 201 provides effective treatment of distant metastatic disease when systemically delivered. These study results were invited to appear on the ASCO virtual meeting site. Introgen is actively studying methods to use gene therapy to treat all stages of cancer, from locally advanced aggressive disease to more widespread disease. In an announcement earlier this year, Introgen described published research in which INGN 201 was used an antigen to prime the human immune system to destroy cancer cells. This therapeutic approach offers another route to the future treatment of widely metastatic disease and is the subject of ongoing research at Introgen.

�This study is important in several respects. Perhaps most importantly, it does away with the idea that systemic delivery of an adenoviral vector, even at high doses, is not safe,� said James A. Merritt, M.D., vice president of clinical affairs for Introgen. �In fact, we showed some time ago that there is systemic exposure of adenoviruses following even localized injections, and we have now shown that high doses can be safely administered repeatedly intravenously. This demonstrates a huge margin of safety to our treatment which is in Phase III testing, delivered intratumorally to tumors in the head and neck. These data also serve to provide a firm scientific footing for treatment of systemic disease with this class of gene therapeutics.�

The safety of high doses of intravenously administered INGN 201 in this clinical study was predicted based upon the accumulation of data in more than 20 clinical studies. Introgen�s vectors are manufactured under rigorous standards using our patented production technologies. Introgen adenoviral vectors have been used to treat over 500 patients with thousands of doses and have not presented any safety concerns to date.

In the bladder study, nine patients with locally advanced bladder cancer were treated with INGN 201 (Adenoviral-p53) delivered intravesically, or, directly to the bladder. These patients were ineligible for cystectomy, a surgical procedure used in 90% of patients with advanced bladder cancer in which the bladder is removed. Two patients are clinically disease-free at a follow-up conducted 23 months after treatment. Seven patients progressed after two months. This study was one of five studies being conducted through Introgen�s Cooperative Research and Development Agreement (CRADA) with the National Cancer Institute (NCI). Introgen�s agreement with the NCI has created the broadest clinical trial program for an adenoviral-p53 therapeutic in the United States. An estimated 53,000 new cases of bladder cancer were diagnosed in the United States in 2000 with estimates of 12,000 deaths annually from this disease.

�The interim results from this study demonstrate that we can safely deliver multiple doses of Adenoviral-p53 directly to the bladder,� said Lance Pagliaro, M.D., of the Department of Genitourinary Medical Oncology at The University of Texas M. D. Anderson Cancer Center and lead investigator of this study. �We plan to continue this trial with an increased dosing schedule to further evaluate the safety profile in this patient population.�

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, 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. 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 has FDA inspected fully staffed validated Good Manufacturing Practices (cGMP) production facilities that are producing Phase III and commercial inventory of INGN 201. Introgen has received U.S. Patent No. 6,194,191 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 drug product candidates in treating bladder and metastatic cancer, 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 February 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).