clofarabine Demonstrates Significant Activity in High Risk, Elderly Acute Myeloid Leukemia (AML) Patients.

ATLANTA -- Bioenvision (Nasdaq:BIVN) today announced an interim analysis of data from the Company's Phase II (EU) regulatory trial of clofarabine in elderly patients with Acute Myeloid Leukemia (AML) who were unsuitable for intensive chemotherapy. The update was given to a meeting of principal investigators and European and Japanese hematologists.

Bioenvision reported that a total of 66 patients have been enrolled in the study and the study is now closed to recruitment. "There are a number of patients still receiving treatment and these data are preliminary," said Dr Andrew Saunders, Bioenvision's Medical Director. He added that "all patients in this trial were considered truly unfit for intensive chemotherapy and, to date, none have gone on to receive any intensive chemotherapy post-clofarabine treatment."

The data presented focused upon the high risk population of AML patients which includes those patients with unfavorable cytogeneics profiles and those over 70 years of age. These patients represent a group with a significant unmet medical need. In the analysis of the first 44 patients, 25% had high-risk cytogenetic profiles and in these patients the response rate to clofarabine was 36%. Professor Alan Burnett, Chairman of the UK National Cancer Research Institute (NCRI) Hematological Oncology Study Group, commented "the responses in this high risk group are very encouraging because with standard non-intensive therapy in this elderly, unfit population we would expect to see very limited activity."

A further analysis of the first 44 patients in the Phase II regulatory study focused on the patients over 70 years of age. This is a particularly high risk group and represents a significant proportion of the overall adult AML patient population. In these patients, clofarabine achieved an overall response rate of 56%. Current standard treatment in the elderly, unfit AML patients, is low dose ara-C, which, achieved an overall response rate of 18% in AML-14, a separate study conducted by the NCRI. The early death rate observed with clofarabine was consistent with reported rates associated with low dose ara-C in this elderly population.

The full data set for the company sponsored Phase II study, including duration of remission and survival, will be presented in 2006.

About clofarabine

clofarabine is a next generation of the drug class, purine nucleoside analogs that inhibit DNA production necessary for cancer cell growth. Bioenvision and Genzyme (Nasdaq:GENZ) are co-developing clofarabine. Bioenvision holds an exclusive worldwide license to clofarabine (outside Japan and Southeast Asia). Bioenvision granted an exclusive sublicense for certain US and Canadian cancer markets to Genzyme. Bioenvision holds an exclusive license in the US and Canada to all non-cancer indications and an exclusive, irrevocable option to develop and market clofarabine for all human applications in Japan and Southeast Asia.

Bioenvision originally obtained clofarabine development and commercialization rights under patents held by Southern Research Institute.

Clofarabine has been granted orphan drug designation for the treatment of adult and pediatric ALL and AML in the U.S. and Europe. In the U.S., orphan drug status extends market exclusivity for seven years. The FDA also recently granted an additional six months market exclusivity to clofarabine under the Best Pharmaceuticals for Children Act. In Europe, the designation provides marketing exclusivity for 10 years. In December 2004, FDA approved the use of clofarabine for treatment of pediatric patients 1 to 21 years old with relapsed or refractory ALL after at least two prior regimens.

In Europe, Bioenvision filed a marketing authorization application (MAA) with EMeA in July 2004 for approval of clofarabine for use in pediatric patients with ALL who are relapsed or refractory to at least two prior regimens of treatment. Bioenvision has received and responded to the CHMP's Day 120 List of Questions and in October 2005, Bioenvision received the CHMP's Day 180 List of Questions. Bioenvision currently are compiling data sufficient to make a complete response to the EMeA.

About Bioenvision

Bioenvision's primary focus is the acquisition, development, distribution and marketing 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 Genzyme Oncology, Inc.), Modrenal(R) (for which Bioenvision has obtained regulatory approval for marketing in the United Kingdom for the treatment of post-menopausal breast cancer following relapse to initial hormone therapy), 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.