Vion Pharmaceuticals Enters Into Agreement With HOVON to Conduct a Phase III Clinical Trial of Cloretazine(R) in Combination With Frontline AML and MDS Therapy

    NEW HAVEN, Conn., Aug. 19 /EMWNews/ -- VION

PHARMACEUTICALS, INC. (Pink Sheets: VION) announced today that it had

entered into an agreement with the Dutch-Belgian Cooperative Trial Group

for Hematology Oncology (the "HOVON") to conduct a clinical trial of

laromustine (Cloretazine(R) (VNP40101M)) with standard remission-induction

therapy in patients aged 18-65 with previously untreated acute myelogenous

leukemia (AML) and high-risk myelodysplasia (MDS).



    Alan Kessman, Chief Executive Officer, commented, "We are pleased to be

working with HOVON, one of the most prestigious clinical groups in

hematology oncology. We continue to believe that Cloretazine(R) will have

broad utility in the treatment of hematological malignancies as both a

single agent and in combination with other therapies. This trial will

provide important data with regard to Cloretazine(R)'s utility in the

treatment of AML when given in combination with standard

remission-induction therapy for this devastating disease."



    Dr. Bob Lowenberg, Chief Investigator of HOVON, said, "HOVON is

focusing on the clinical development of new therapeutic options for

patients with leukemia. Laromustine is a promising agent for that effort."



    The trial has been designed as a Phase III study in two parts. Part A

will determine the feasibility (based on safety and preliminary

effectiveness) of laromustine administration at three possible dose levels

in combination with cytarabine and idarubicin. Part A will also evaluate

the pharmacokinetics and the clinical efficacy of the laromustine

combination.



    Part B is then designed to evaluate the clinical efficacy of the

laromustine combination versus two cycles of cytarabine and idarubicin

without laromustine with regard to clinical outcome ("event free

survival"), the complete remission rate, disease free survival (DFS), risk

of relapse and overall survival (OS), as well as the tolerance and

toxicity, and pharmacokinetics of the combination.



    The trial is expected to start this fall and will be conducted at

various sites in the Netherlands, Belgium, Switzerland and Norway.

    About Vion



    Vion Pharmaceuticals, Inc. is committed to extending the lives and

improving the quality of life of cancer patients worldwide by developing

and commercializing innovative cancer therapeutics. Vion has two agents in

clinical trials. Laromustine (Cloretazine(R) (VNP40101M)), a unique

alkylating agent, is being evaluated in a Phase II pivotal trial as a

single agent in elderly patients with previously untreated de novo

poor-risk acute myelogenous leukemia. Clinical trials of Cloretazine(R)

(VNP40101M) with cytarabine in elderly patients with acute myelogenous

leukemia, with temozolomide in brain tumors, and with stem cell

transplantation in advanced hematologic malignancies, are also being

conducted. Triapine(R), a potent inhibitor of a key step in DNA synthesis,

is being evaluated in clinical trials sponsored by the National Cancer

Institute. For additional information on Vion and its product development

programs, visit the Company's Internet web site at http://www.vionpharm.com.



    About HOVON



    HOVON is a Dutch-Belgian cooperative clinical trial group in hematology

oncology with a strong clinical development program in leukemia, malignant

lymphomas and multiple myeloma. The HOVON group works with several other

countries in Europe and has a long-standing track record with trials in

acute leukemia. A distinct part of its clinical trials concerns the

analysis of biological variables of the disease in relation to treatment

outcome.



    This news release contains forward-looking statements. Such statements

are subject to certain risk factors which may cause Vion's plans to differ

or results to vary from those expected, including Vion's potential

inability to file a New Drug Application or obtain regulatory approval for

its products, particularly Cloretazine(R) (VNP40101M), delayed or

unfavorable results of drug trials, the possibility that favorable results

of earlier preclinical studies, clinical trials or interim clinical trial

data are not predictive of safety and efficacy results in later or final

clinical trials, the need for additional research and testing, the

inability to manufacture product, the potential inability to secure

external sources of funding to continue operations, the inability to access

capital and funding on favorable terms, continued operating losses and the

inability to continue operations as a result, the delisting of the

Company's common stock from the Nasdaq Capital Market and a variety of

other risks set forth from time to time in Vion's filings with the

Securities and Exchange Commission, including but not limited to the risks

attendant to the forward-looking statements included under Item 1A, "Risk

Factors" in Vion's Form 10-K for the year ended December 31, 2007 and Form

10-Q for the quarter ended June 30, 2008. In particular, there can be no

assurance as to the results of any of the Vion's clinical trials, that any

of these trials will continue to full accrual, or that any of these trials

will not be discontinued, modified, delayed or ceased altogether. Except in

special circumstances in which a duty to update arises under law when prior

disclosure becomes materially misleading in light of subsequent events,

Vion does not intend to update any of these forward-looking statements to

reflect events or circumstances after the date hereof or to reflect the

occurrence of unanticipated events.






    COMPANY CONTACT:  Vion Pharmaceuticals, Inc.

                      Alan Kessman, Chief Executive Officer

                      Howard B. Johnson, President & CFO

                      (203) 498-4210 phone