Bioenvision Obtains Exclusive Option to Market Clofarabine in Japan and South East Asia.

Business Editors

NEW YORK--(BUSINESS WIRE)--Sept. 10, 2003

Bioenvision, Inc. (Amex:BIV) today announced that it has obtained an exclusive, irrevocable option, subject to certain conditions, to manufacture, market and distribute clofarabine, Bioenvision's lead drug for the treatment of pediatric and adult acute leukemias, in Japan and South East Asia. The option is obtained from Southern Research Institute, the inventor of clofarabine. Bioenvision is actively seeking a co-marketing partner to convert this option into a license on terms to be agreed upon between Bioenvision and Southern Research Institute.

"Coupling our ongoing European development activities with our contacts in Japan and Southeast Asia, we are in a fine position to capitalize on this exciting new opportunity and expect to do so by sourcing a co-marketing partner during the term of the option," stated Dr. Christopher B. Wood, M.D., Chairman and Chief Executive Officer of Bioenvision.

"This significantly enhances Bioenvision's business potential and coincides nicely with the expansion of our experienced operating team," added David P. Luci, Director of Finance and General Counsel of Bioenvision.

Bioenvision originally obtained the right to manufacture, market and distribute clofarabine worldwide outside of Japan and Southeast Asia pursuant to its August 1998 co-development agreement with Southern Research Institute. Bioenvision subsequently outsourced an option to develop clofarabine, subject to achievement of certain milestones and certain other conditions, in the U.S. and Canada in March 2001. Bioenvision's European development program for clofarabine is on target with pivotal, Phase II, multi-centre studies about to be initiated in both pediatric and adult acute leukemias.

About Clofarabine

Clofarabine (Cl-F-ara-A, CAFdA) is a second-generation purine nucleoside antimetabolite. Nucleoside analogs are antimetabolites that affect DNA synthesis. Clofarabine was rationally designed to combine many of the favorable properties of the two most commonly used nucleoside analogs, Fludarabine Fludara(R) by Schering AG (NYSE: SHR) and Cladribine, Leustatin(R) by Johnson and Johnson (NYSE: JNJ), but is reported to have greater potency at damaging the DNA of Leukemia cells than these other agents. (Blood, "Mitochondrial Toxity of Deoxyadenoside Analogs", November 15, 2000, Volume 96, Number 10). In a single centre Phase II study of Clofarabine in patients with refractory AML, 42% of the patients had a complete response rate (CR) and a further 13% had a partial response (CRp).

About Bioenvision

Bioenvision's (Amex: BIV) 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) (for which Bioenvision has obtained approval for marketing in the United Kingdom for the treatment of advanced post-menopausal breast cancer), 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.