Preclinical data of Introgen’s INGN 241 demonstrate broad anti-cancer activity in multiple tumor types as monotherapy and in combination

Seattle, WA, June 1, 2001 – Introgen Therapeutics, Inc. (NASDAQ: INGN) today reported preclinical findings demonstrating that INGN 241, an Adenoviral vector encoding the mda-7 gene, is a novel cytokine family member that exhibits broad anticancer activity. INGN 241 can inhibit cell growth in multiple tumor types when used alone or in combination with established therapies. These data were presented as three separate studies at the Fourth Annual Meeting of the American Society for Gene Therapy in Seattle, Washington.

Highlights of the studies include:

· Potent in vitro anti-tumor activity in human breast cancer cells in combination with HerceptinÒ or tamoxifen. This in vitro study, conducted by Sunil Chada, Ph.D., director of research and development at Introgen, demonstrates that INGN 241 is very potent in inhibiting breast cancer cell growth when combined with two molecular-based therapies used to treat breast cancer, HerceptinÒ (Trastuzumab, a monoclonal antibody against the Her2 receptor) and tamoxifen (also known as NolvadexÒ, Tamofen and Genox, which blocks the effect of estrogen, a female hormone which can stimulate the growth of breast cancer cells). The addition of INGN 241 to the treatment regimen potently enhanced the anti-tumor effect compared to each individual agent. The authors concluded that the combination of a potent anti-tumor agent like INGN 241 with conventional anti-cancer agents like Herceptin and tamoxifen will increase anti-cancer effects.

“This study shows that INGN 241 is a promising anti-cancer agent that can be combined with conventional therapies for enhanced anti-tumor effects,” said Dr. Chada. “The ability to utilize molecular targets specific for cancer cells may allow us to develop targeted therapies that selectively kill cancer cells while leaving normal tissue unharmed. Further research with these promising gene/drug combinations is warranted.”

· Forced expression of mda-7 by adenoviral gene transfer causes apoptotic cell death in malignant pleural mesothelioma (MPM) in vitro. In this study conducted in collaboration with Roy Smythe, M.D., at The University of Texas M. D. Anderson Cancer Center, treatment of human MPM cells in vitro with INGN 241 demonstrated programmed cell death, or apoptosis, with no observed effect upon normal cells. Malignant Pleural Mesothelioma (MPM) is a cancer of the lung for which there is no effective treatment. Mesothelioma is unresponsive to most chemotherapy and radiotherapy regimens, and it typically recurs even after the most aggressive attempts at surgical resection. Thus, INGN 241 may provide a novel means of treating this incurable cancer.

· mda-7 is a novel cytokine in the IL-10 family. Another study confirms preliminary findings that indicate mda-7 is a novel member of the interleukin-10 cytokine gene family, which stimulates cell death selectively in cancer cells. Introgen is conducting this research in collaboration with Elizabeth Grimm, M.D., at The University of Texas M.D. Anderson Cancer Center.

“We have previously shown that INGN 241 directly kills tumor cells that take up the vector,” said Dr. Chada. “In addition, the MDA-7 protein is secreted from cells treated with INGN 241. Our new results suggest that this secreted protein may act as a cytokine to stimulate the immune response to attack neighboring cancer cells.”

The mda-7 gene was discovered at Columbia University in the laboratory of Dr. Paul Fisher. Commercial rights to the discovery were licensed to Genquest, Inc. which was acquired by Corixa Corporation in 1998. Introgen has an exclusive license from Corixa Corporation for the use of the mda-7 gene for gene therapy applications.

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 drug product candidates, the efficacy of our drug product candidates in treating breast or malignant pleural mesothelioma cancers, and Introgen’s ability to complete its clinical trials or successfully commercialize INGN 241 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.

HerceptinÒ (Trastuzumab) is a registered trademark of Genentech, Inc.
NolvadexÒ is a product of AstraZeneca, Inc.

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).