Bioenvision Commences European Pivotal Phase II Study in Pediatric Acute Lymphoblastic Leukemia.

Business Editors/Health/Medical Writers

NEW YORK--(BUSINESS WIRE)--Sept. 16, 2003

Bioenvision, Inc. (AMEX:BIV) today announced the commencement of the European multi-center pivotal Phase II study in children with relapsed and / or refractory Acute Lymphoblastic Leukemia (ALL).

An Investigator Meeting was held in London on Thursday September 11, 2003, and was attended by leading pediatric hematologists and oncologists from across Europe.

"Clofarabine has already been shown to demonstrate significant activity in pediatric patients with acute leukemias," said Professor Vaskar Saha, Head of Cancer Research U.K.: Children's Cancer Group. "Study BIOV-111 has been designed to exploit clofarabine's unique profile and provide a new treatment option for pediatric patients who have few alternatives. We are very excited about this opportunity to introduce a new drug for children with high risk leukemia across Europe."

Interim results of an ongoing Phase II multi-center study of clofarabine in the U.S. were presented which showed an overall response rate of 28% for clofarabine in heavily pre-treated children with acute lymphoblastic leukemia. Patients enrolled in the study were refractory to all alternative therapy and had previously failed a median of three chemotherapy regimens. 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).

"The responses to clofarabine observed in this interim analysis are very encouraging," said Mr. Hugh Griffith, Executive Director of Bioenvision. "Investigator interest in our new European study has been overwhelming and we look forward to enrolling the first patients into this important study."

"Working with Bioenvision has been refreshing as the management team have demonstrated a clear understanding of the issues investigators face in conducting clinical trials in pediatric oncology," said Dr. Pamela Kearns, on behalf of the New Agents Group of the U.K. Children's Cancer Study Group.

Clofarabine was recently granted fast track designation by the U.S. Food and Drug Administration (FDA) for the treatment of refractory or relapsed acute lymphoblastic leukemia (ALL) in children. Based on this designation and ongoing discussions with the FDA, it is expected that the current Phase II trial of clofarabine in pediatric ALL will be pivotal for registration.

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 "orphan drug" designation provides marketing exclusivity for 10 years in Europe, during which the drug development process is enhanced by the EMEA's assistance with regulatory strategy and access to the Centralized Procedure for marketing approval application.

About Clofarabine

Clofarabine (Cl-F-ara-A, CAFdA) is a novel, 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 Phase II study of clofarabine in 62 adult patients with refractory or relapsed acute leukemias, 32% of the patients had a complete response rate (CR); 15% had a CR without full platelet recovery (CRp); and 2% had a partial response (PR) for an overall response rate of 48% (Blood, prepublished online June 5, 2003; DOI 10.1182/blood-2003-03-0925).

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 (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 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.