Bioenvision Obtains U.K. Marketing Rights to Modrenal.

Business Editors/Health/Medical Writers

NEW YORK--(BUSINESS WIRE)--Aug. 20, 2003

Bioenvision, Inc. (OTCBB: BIOV) today announced that it has obtained the rights to market Modrenal(TM) (trilostane), its approved compound for the treatment of advanced post-menopausal breast cancer, in the United Kingdom. Stegram Pharmaceuticals, Ltd. transferred the marketing rights to Bioenvision pursuant to an amendment to the July 1998 co-development agreement between the companies. In accordance with the amendment, Bioenvision will also receive all revenue streams for sales of Modrenal as of January 1, 2003.

"We received a highly encouraging response after releasing our positive data in May regarding Modrenal's unique dual mode of action," said Hugh Griffith, Commercial Director of Bioenvision. "We aim to capitalize on this momentum in order to significantly increase the current level of sales of Modrenal in the U.K."

"This is another critical development in Bioenvision's internal growth," said David P. Luci, Director of Finance and General Counsel of Bioenvision. "With the introduction of revenues from sales of Modrenal in the U.K, we expect to significantly reduce our burn rate at a pivotal time in the development of our lead drugs, clofarabine and Modrenal."

In support of the marketing effort, Bioenvision is initiating further clinical trials of Modrenal in Europe, with the intention of increasing physician and patient awareness of the product and the unique characteristics of the drug. A trial of the use of Modrenal in pre-menopausal patients with breast cancer is planned for later this year.

Mr. Griffith added, "We plan to extend the marketing of Modrenal into other European countries via the mutual recognition pathway. This will bring Modrenal to a much wider audience of physicians and patients and greatly increase the marketing opportunity."

Modrenal has shown clinical benefit rates between 35% and 55% in post-menopausal patients with advanced breast cancer who have relapsed following prior therapies. Bioenvision previously reported that Modrenal has two unique mechanisms of action, affecting both the ER alpha and ER beta estrogen receptors. ER beta is known now to play an important role in the development of hormone sensitive cancers, such as breast and prostate cancer, and this receptor has therefore become a prime target for new forms of treatment. Bioenvision believes that Modrenal can alter the effect of estrogen at the binding site ER beta, thereby reversing or slowing the progression of breast cancer. Research published last year in the International Journal of Cancer support Modrenal's activity as an ER beta modulator (Puddefoot JR et al "Non-Competitive Steroid Inhibition of Estrogen Receptor Functions". Int J Cancer: 101, 17-22, 2002).

Bioenvision also plans to run clinical trials in the U.S. to determine Modrenal's effect on prostate cancer in patients refractory to hormone-based therapy.

About Modrenal

Modrenal has been approved for the treatment of advanced post-menopausal breast cancer by United Kingdom regulatory authorities. It has been extensively studied in controlled trials in the United States, Europe and Australia. Over 700 patients with breast cancer have received Modrenal in clinical trials, and its anti-tumor activity has been well documented; it is effective in a significant proportion of breast cancer patients, particularly those with hormone-sensitive tumours.

About Bioenvision

Bioenvision's (OTCBB: BIOV.OB) primary focus is the acquisition, development and distribution of compounds and technologies for the treatment of cancer. Bioenvision has a broad pipeline of products for the treatment of cancer, including: clofarabine, Modrenal(R), and other products in clinical trials. Bioenvision is also developing anti-infective technologies, including the OLIGON technology, an advanced biomaterial that has been incorporated into various FDA approved medical devices. For more information on Bioenvision please visit our Web site at www.bioenvision.com.

Certain statements contained herein are "forward-looking" statements (as such term is defined in the Private Securities Litigation Reform Act of 1995). Because these statements include risks and uncertainties, actual results may differ materially from those expressed or implied by such forward-looking statements. Specifically, 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 Bioenvision's compounds under development in particular; the potential failure of Bioenvision's compounds under development to prove safe and effective for treatment of disease; uncertainties inherent in the early stage of Bioenvision's compounds under development; failure to successfully implement or complete clinical trials; failure to receive marketing clearance from regulatory agencies for our compounds under development; acquisitions, divestitures, mergers, licenses or strategic initiatives that change Bioenvision's business, structure or projections; the development of competing products; uncertainties related to Bioenvision's dependence on third parties and partners; and those risks described in Bioenvision's filings with the SEC. Bioenvision disclaims any obligation to update these forward-looking statements.