Study Results Published in `Journal of Biological Chemistry' Show Structural Stability, Potency of Tumstatin Peptides, Announces ILEX.

Business Editors & Health/Medical Writers

BOSTON--(BW HealthWire)--July 23, 2001

ILEX(tm) Oncology Inc. (Nasdaq:ILXO) today announced study results published in the Journal of Biological Chemistry's "Papers in Press" identify for the first time linear peptide sequences derived from tumstatin, an extracellular matrix-derived natural protein involved in controlling angiogenesis.

These peptides exhibit in vivo activity equivalent to the full-length tumstatin and appear to be more active and potent in preclinical models than other protein-based angiogenesis inhibitors currently in clinical development.

The study, entitled "Extracellular matrix derived peptide binds to alpha-v, beta-3 integrin and inhibits angiogenesis," was conducted by Raghu Kalluri, Ph.D., and his laboratory at Beth Israel Deaconess Medical Center (BIDMC) and Harvard Medical School, Boston, in collaboration with scientists at ILEX's Boston laboratory headed by Surender Kharbanda, Ph.D.

Angiogenesis occurs when endothelial cells divide and multiply to form new blood vessel growth that feeds a tumor. "The study showed that the linear tumstatin peptides inhibit the endothelial cells in the presence of vitronectin, fibronectin and collagen I, indicating they have excellent potential to reduce angiogenesis," said Dr. Kharbanda. "This unexpected finding also confirmed that the anti-angiogenic activity of tumstatin is independent of disulfide bond requirement and the tertiary structure of the protein."

Tumstatin is one of ILEX's leading natural extracellular matrix-derived angiogenesis inhibitors among several being researched, said Executive Vice President and Chief Operating Officer Ze'ev Shaked, Ph.D. "These new results further enhance the strength of ILEX's angiogenesis inhibitor program and mean we can expedite the filing of an Investigational New Drug application with the goal of getting this compound into the clinic next year," he said. "This relatively short peptide sequence will enable the administration of these angiogenesis inhibitors via a wide range of drug delivery systems, including oral. This may prove to be critically important as angiogenesis inhibitors are likely to show best results when administered on a daily basis."

Dr. Shaked added that these peptides can be manufactured via conventional peptide synthesis, a more efficient and cost-effective process as compared to the fermentation-based production method necessary to manufacture other anti-angiogenic proteins currently in clinical development.

The paper is currently available online at www.jbc.org/cgi/content/abstract/M103024200v1 and will be published in an upcoming print issue of the journal.

ILEX has exclusive development rights to tumstatin from patents licensed from BIDMC to Convergence Pharmaceuticals, which was acquired by ILEX in 1999. BIDMC is a major patient care, research and teaching affiliate of Harvard Medical School. Dr. Kalluri was a stockholder in Convergence Pharmaceuticals and acquired some shares of ILEX stock at the time of the acquisition. He currently serves on the Research Advisory Panel of ILEX. The research was funded by the National Institutes of Health, the 1998 Hershey Prostate Cancer Research Award to Dr. Kalluri and the Program in Matrix Biology at BIDMC. It also was funded by the 1999 Research Award for Young Scientists from the Inoue Foundation for Science of Japan to another author of the study, Yohei Maeshima, M.D., Ph.D. This study represents preclinical research results, and human clinical trials to evaluate the safety and efficacy of this compound would be required before an application for marketing approval could be submitted to the U.S. Food and Drug Administration.

About ILEX Oncology Inc.

Founded in 1994 as an oncology drug development company, ILEX Oncology Inc. is strategically positioned to become a leading oncology-focused pharmaceutical company. ILEX has a marketed product, Campath(R) in the U.S. and MabCampath(tm) in Europe, and is advancing a deep pipeline of anti-cancer compounds focused on the treatment of both advanced and early disease. The pipeline comprises multiple technologies at all stages of clinical development, including apoptosis-inducing agents, cytotoxic compounds and angiogenesis inhibitors with novel mechanisms of action, and chemoprevention agents. ILEX maintains one of the biopharmaceutical industry's most experienced in-house development organizations for oncology drugs, with locations in San Antonio, Texas; Annapolis, Md.; and Guildford, England. ILEX also conducts drug discovery research in angiogenesis inhibition, targeted medicinal chemistry and nuclear receptor biology from its laboratories in Boston, Mass. and Geneva, Switzerland. Further information about ILEX can be found on the company's Web site at www.ilexonc.com.

Certain statements contained herein are "forward-looking" statements (as such term is defined in the Private Securities Litigation Reform Act of 1995). Because such statements include risks and uncertainties, actual results may differ materially from those expressed or implied by such forward-looking statements. Factors that could cause actual results to differ materially from those expressed or implied by such forward-looking statements include, but are not limited to, risks associated with preclinical and clinical developments in the biopharmaceutical industry in general and in ILEX's compounds under development in particular; the potential failure of tumstatin and the company's other compounds under development to prove safe and effective for treatment of disease; uncertainties inherent in the early stage of the company's compounds under development; failure to successfully implement or complete clinical trials; the development of competing products; uncertainties related to the company's dependence on third parties and partners; uncertainty related to protection of the company's intellectual property; failure to successfully complete clinical trials; failure to receive marketing clearance from regulatory agencies; and those risks described in the Company's Form S-3 filed May 1, 2001, as amended (Commission file No. 333-59954) and the Company's Annual Report on Form 10-K for the year ended Dec. 31, 2000, and in other filings made by ILEX with the SEC. The Company disclaims any obligation to update these forward-looking statements.