Clinical Data for Bioenvision's Clofarabine Presented at the 8th Congress of the European Haematology Association.

Business Editors

NEW YORK--(BUSINESS WIRE)--June 12, 2003

Bioenvision, Inc. (OTCBB: BIOV) today presented data from studies of its lead leukemia compound, clofarabine, at the 8th Congress of the European Haematology Association (EHA) in Lyon, France.

During the two-hour satellite symposium, investigators from The University of Texas M.D. Anderson Cancer Center (M.D. Anderson), Houston, reported the latest data from ongoing pediatric and adult acute leukemia clinical trials.

Interim results of a Phase II multi-center study of clofarabine, also recently reported at the 39th Annual Meeting of the American Society of Clinical Oncology in Chicago, showed an overall response rate of 28% for clofarabine in heavily pre-treated children with acute leukemia. Patients enrolled in the study were refractory to all alternative therapy and had previously failed a median of three chemotherapy regimens.

Sima Jeha, M.D., lead investigator on the study, reported data from 39 patients, 14 with acute myelogenous leukemia (AML) and 25 with acute lymphocytic leukemia (ALL). In the ALL study one child achieved complete remission (CR), two children achieved complete marrow remission in the absence of platelet recovery (CRp) and four children achieved partial remission (PR). In a preliminary analysis of the AML study, it was reported that one patient had a CRp and three children achieved a partial response (PR).

Dr Jeha stated, "Children at this highly refractory stage of leukemia have limited treatment options. The response to clofarabine we have seen in this study is incredibly encouraging."

Investigators at EHA also reported interim results from a Phase I/II study combining clofarabine with cytarabine (ara-C) in adult patients with relapsed/refractory acute leukemias. The study showed that clofarabine can be combined with ara-C and that this combination has activity in patients with AML.

An overall response rate of 44% was observed in the first nine relapsed/refractory AML patients enrolled in the dose ranging portion of the study.

Dr Varsha Gandhi, one of the lead investigators on the combination study, stated, "Combination of clofarabine and cytarabine is based on biochemical and pharmacological rationales. This sequential combination should result in augmentation of ara-C triphosphate accumulation. In addition, clofarabine as a single agent is effective in acute leukemias. Hence, we are very optimistic about the initial clinical responses observed in this group of patients."

Professor Alan Burnett, Chairman of the National Cancer Research Institute Haematological Oncology Study Group in the U.K., commented, "There is a considerable need for a new approach to treatment for some patients with AML. Our group is particularly attracted to the use of clofarabine in older patients who are not considered fit for intensive combination chemotherapy based on the promising data in patients with advanced disease. Another potential advantage could be the availability in an oral formulation. The preliminary clinical data is promising and biochemical studies have provided strong rationale for combining the drugs."

Clofarabine has been granted an 'Orphan Medicinal Product' designation by the European Agency for the Evaluation of Medicinal Products (EMEA) as a treatment for ALL and AML in Europe. The Food and Drug Administration (FDA) have also granted clofarabine "orphan status". Obtaining this designation provides marketing exclusivity for 10 years, during which clofarabine's development process is enhanced by the EMEA's assistance with regulatory strategy and access to the Centralised Procedure for marketing approval application.

Bioenvision is initiating two pivotal Phase II multi-center trials of clofarabine in Europe to evaluate the drug's efficacy in children with ALL and in adults with AML. Enrollment in both trials will begin shortly.

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 favourable 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 Toxicity of Deoxyadenoside Analogs", November 15, 2000, Volume 96, Number 10). In a single center 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). Ilex has obtained the right to develop clofarabine in the United States and Canada from Bioenvision, which maintains its rights to develop clofarabine outside of those areas.

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 (in co-development with ILEX Oncology, Inc.), 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. For more information on Bioenvision please visit our Web site as 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.