Bioenvision Signs Manufacturing and Supply Agreements with Ferro Pfanstiehl for Production of Clofarabine.

Business Editors/Health/Medical Writers

NEW YORK--(BUSINESS WIRE)--June 17, 2003

Bioenvision, Inc. (OTCBB: BIOV) today announced that it has signed two separate agreements with Ferro Pfanstiehl Laboratories, Inc. for the development and supply of clofarabine, Bioenvision's lead drug for the treatment of pediatric and adult acute leukemias.

The agreements cover worldwide development and supply of clofarabine, excluding the United States and Canada.

Ferro Pfanstiehl has more than 25 years of experience in potent compound manufacturing. The company's operations are conducted at its modern High Potency Manufacturing Facility in Waukegan, Illinois. The facility is SafeBridge Certified, ensuring compliance and proper assessment and management of risks.

"We are delighted to have added Ferro Pfanstiehl to our development team," said Dr. Christopher B. Wood, Chairman and Chief Executive Officer of Bioenvision. "The clofarabine process is an excellent fit with Ferro's superior technical strength in fluorinated carbohydrate intermediate manufacture and its nucleoside handling capabilities."

Dr. Wood continued, "The Ferro team also brings extensive process development, scale-up and regulatory experience to bear on the program, which will maximize the likelihood that clofarabine is successfully developed and commercialized."

Clofarabine has shown a potential synergistic effect in combination with cytarabine (ara-C) in patients with acute myeloid leukemia (AML). Ferro Pfanstiehl is the leading domestic manufacturer of ara-C.

About Ferro Pfanstiehl

Ferro Pfanstiehl Laboratories, Inc. manufactures proprietary fine chemicals and provides custom synthesis of high potency, active pharmaceutical ingredients. Pfanstiehl provides confidential process development and contract manufacturing services, bringing client products from the bench to commercial scale production. With strengths ranging from isolation and purification of naturally occurring substances to complex, multi-step syntheses, Pfanstiehl manufactures a diverse mix of products. Ferro Pfanstiehl is a division of Ferro Corporation, a global producer of performance materials sold to various manufacturers in approximately 30 markets worldwide.

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 (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) (for which Bioenvision has obtained regulatory 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 approved for certain indications by the FDA in the U.S.

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.