First Patients Enrolled in Three Breast Cancer Studies for Bioenvision's Modrenal(R)

The Phase IV study will evaluate the efficacy of Modrenal(R) inpost-menopausal women who have failed prior aromatase inhibitortherapy. The study is being conducted in nine leading UK centers andthe first 18 patients have been recruited, with a target of 61evaluable patients. The primary objective of the Phase IV study is todetermine the clinical benefit rate associated with Modrenal(R)treatment, and the trial is expected to be completed Q4, calendar2006. The study will add to the existing database for Modrenal(R) inover 700 patients with advanced post-menopausal breast cancer.

The Phase II sponsored clinical study will focus on pre-menopausalwomen with advanced breast cancer who have relapsed or are refractoryto first line treatment. The study is being conducted at eight leadingUK centers and will recruit up to 41 evaluable patients. The primaryobjective of the Phase II study is to determine the clinical benefitrate associated with Modrenal(R) treatment and this trial is alsoexpected to be completed Q4, calendar 2006.

A Phase II, investigator sponsored study will examine the role ofModrenal(R) as first line treatment for post-menopausal patients withthe objective of decreasing the breast cancer tumor mass prior tosurgery. The first 12 patients have been recruited with a target of 30evaluable patients in total. This study is expected to completeenrollment in Q2, calendar 2006.

"These multi-center studies are an important step in thedevelopment of Modrenal(R)," commented Dr. Christopher Wood, CEO andChairman of Bioenvision. "There is an enormous need for new drugs thatoffer alternative treatment options, especially for patients who havedeveloped resistance to existing therapies," added Dr. Wood.

Modrenal(R) is licensed and marketed in the UK to treatpost-menopausal advanced breast cancer following relapse on initialhormone therapy and has demonstrated clinical benefit rates as high as55%.

Instigation of this new clinical trial program follows thediscovery of new mechanisms of action for Modrenal(R), which is nowknown to be effective in cases of acquired endocrine resistance.

About Modrenal(R)

Modrenal(R) is approved in the UK to treat post-menopausaladvanced breast cancer following relapse on initial hormone therapy.Over 800 patients with breast cancer have received Modrenal(R)(trilostane) in clinical trials, and its anti-tumor activity has beenwell documented; it is effective in a significant proportion of breastcancer patients, particularly those with hormone-sensitive tumors.

New Mechanisms of Action

Two novel mechanisms of action for Modrenal(R) have recently beendiscovered: The first unique mechanism of action, published in theInternational Journal of Cancer in 2002, explained how Modrenal(R) canuniquely effect the binding of the hormone estrogen to receptors onthe surface of cancer cells, and in particular to estrogen receptorbeta (ER-beta). ER-beta is now known to be important in controllingthe proliferation of breast cancer and is an influential predictor ofsurvival. Modrenal(R)'s effect on this receptor results in a reversalor reduction in the growth of the cancerous breast tissue.

The second unique mechanism of action, presented at the AmericanSociety of Clinical Oncology 2004 Annual Meeting in New Orleans,outlined how Modrenal(R)'s ability to increase estrogen binding toER-beta and also decrease binding to ER-alpha, brings about a newlydiscovered interaction at the binding site of a protein, AP1. AP1 isknown to be an important component in cell proliferation pathways thatbecome increasingly relevant as the cancer cells develop resistance toendocrine therapies, such as tamoxifen and aromatase inhibitors.Blocking the action of estrogen through the AP1 mechanism provides anadditional means to reduce the rate of cancer cell proliferation.

About Bioenvision

Bioenvision's primary focus is the acquisition, development anddistribution of compounds and technologies for the treatment ofcancer. Bioenvision has a broad pipeline of products for the treatmentof cancer, including: Clofarabine (in co-development with GenzymeCorporation), Modrenal(R) (for which Bioenvision has obtainedregulatory approval for marketing in the United Kingdom for thetreatment of post-menopausal breast cancer following relapse toinitial hormone therapy), and other products in clinical trials.Bioenvision is also developing anti-infective technologies, includingVirostat for hepatitis-C and the OLIGON technology; an advancedbiomaterial that has been incorporated into various FDA approvedmedical devices. For more information on Bioenvision please visit ourweb site at www.bioenvision.com.

Certain statements contained herein are "forward-looking"statements (as such term is defined in the Private SecuritiesLitigation Reform Act of 1995). Because these statements include risksand uncertainties, actual results may differ materially from thoseexpressed or implied by such forward-looking statements. Specifically,factors that could cause actual results to differ materially fromthose expressed or implied by such forward-looking statements include,but are not limited to: risks associated with preclinical and clinicaldevelopments in the biopharmaceutical industry in general and inBioenvision's compounds under development in particular; the potentialfailure of Bioenvision's compounds under development to prove safe andeffective for treatment of disease; uncertainties inherent in theearly stage of Bioenvision's compounds under development; failure tosuccessfully implement or complete clinical trials; failure to receivemarketing clearance from regulatory agencies for our compounds underdevelopment; acquisitions, divestitures, mergers, licenses orstrategic initiatives that change Bioenvision's business, structure orprojections; the development of competing products; uncertaintiesrelated to Bioenvision's dependence on third parties and partners; andthose risks described in Bioenvision's filings with the SEC.Bioenvision disclaims any obligation to update these forward-lookingstatements.