Clofarabine's Duration of Response Improves Outcome for Elderly AML Patients.

NEW YORK -- Bioenvision (Nasdaq:BIVN) today announced significant duration of response data were presented at recent scientific meetings for clofarabine in elderly, unfit patients with Acute Myeloid Leukemia (AML). Presenting to peers at the UK's annual review of Acute Myeloid Leukemia in Birmingham, UK, Professor Alan K. Burnett, Chairman of the UK National Cancer Research Institute Hematological Oncology Study Group announced the median duration of response for clofarabine in these patients is currently 440 days. This is an improvement on data which was first presented to the American Society of Haematology in December 2004, which highlighted clofarabine's outstanding benefit in this group of patients with a complete response rate of 56% and a median duration of response, at that time, of 180 days. These results were from a Phase II investigator sponsored study conducted through the UK National Cancer Research Institute (NCRI) in 2004, with Professor Burnett as the chief investigator.

Professor Burnett, commenting on this data said, "The role of clofarabine in the treatment of AML continues to demonstrate encouraging results. The median duration of response has now gone over 440 days, adding further to the clinical benefit associated with clofarabine treatment in this cohort of patients."

Dr. Christopher Wood, Chairman and CEO of Bioenvision, added, "this continued improvement in duration of response is very promising and supports our belief that clofarabine has much to offer patients with acute leukemia. The significant clinical benefit which is being seen in this group of patients has given the treating physicians and the NCRI the confidence to include clofarabine in further studies not only for the elderly AML group but for those in different age groups and at differing stages of their disease".

Current best practice in this group of patients, which was also derived from a separately conducted clinical study, AML 14, sponsored by the NCRI, in low dose ara-C which shows a similar median duration of response but with a complete response rate of 18% as compared with the complete response rate of 56% which was obtained from the patients evaluated in the NCRI's Phase II clinical study of clofarabine.

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 is compiling data and responses to address these questions.

About Bioenvision

Bioenvision's 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 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 virostat for hepatitis-C and 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.