Ghulam Mufti, Department Head and Professor of Hematological Medicineat the University of London King's College Hospital, and an investigator onthe trial, said, 'The activity demonstrated in this study is encouraging,particularly the complete responses observed in those patients that hadreceived prior treatment for MDS.' He concluded, 'Despite recent advances inthe treatment of MDS, most patients will relapse, and it is important that wecontinue to develop new therapies to treat these patients.'

Alan Kessman, Chief Executive Officer, said, 'These data demonstrateCloretazine(R) (VNP40101M)'s potential utility in patients with high-risk MDS.We believe that this signal should be pursued with further clinicalinvestigation to optimize the dose and schedule of Cloretazine(R) (VNP40101M)in this disease.'

The Phase II trial started in March 2004 and was conducted in 14 sites inNorth America and Europe. Enrollment of the study was completed in May 2006.

The study was designed for patients over the age of 60 with previouslyuntreated AML and high-risk MDS (patients were not to have received priorcytotoxic chemotherapy, excluding hydroxyurea, low-dose araC, decitabine, or5-azacytidine). Study objectives were: (i) overall complete response ratemeasured as either complete remission (CR) or CRp, a complete response withincomplete platelet recovery; (ii) the toxicity; and (iii) pharmacokinetics ofCloretazine(R) (VNP40101M) in this patient population.

Patients received induction therapy of 600 mg/m2 of Cloretazine(R)(VNP40101M) in a thirty to sixty minute infusion. Second induction waspermitted in patients with bone marrow improvement but residual disease.Patients who responded could receive consolidation therapy of 400 mg/m2 ofCloretazine(R) (VNP40101M).

About Vion

Vion Pharmaceuticals, Inc. is committed to extending the lives andimproving the quality of life of cancer patients worldwide by developing andcommercializing innovative cancer therapeutics. Vion has two agents inclinical trials. Cloretazine(R) (VNP40101M), a unique alkylating agent, isbeing evaluated in a Phase II pivotal trial as a single agent in elderlypatients with previously untreated de novo poor-risk acute myelogenousleukemia. Clinical trials of Cloretazine(R) (VNP40101M) with cytarabine inelderly patients with acute myelogenous leukemia, with temozolomide in braintumors, and with stem cell transplantation in advanced hematologicmalignancies, are also being conducted. Triapine(R), a potent inhibitor of akey step in DNA synthesis, is being evaluated in clinical trials sponsored bythe National Cancer Institute.