VION BEGINS PHASE I/II CLORETAZINE TRIAL

Vion Pharmaceuticals has initiated a Phase I/II trial of its anticancer agent Cloretazine as a single agent in refractory or relapsed chronic lymphocytic leukemia (CLL) and Richter's Syndrome. Enrollment of patients began at the University of Texas M.D. Anderson Cancer Center's Department of Leukemia.

The objectives of the trial are to determine the toxicities and maximum tolerated dose of Cloret in patients with CLL or Richter's Syndrome who have failed a fludarabine-based regimen, and to observe the efficacy of Cloretazine given at the MTD in the same patient population.

The American Cancer Society estimates that 9,730 patients will be diagnosed in the U.S. with CLL in 2005 and 4,600 patients will die from the disease. In CLL, the bone marrow makes too many lymphocytes (a type of white blood cell). As the amount of lymphocytes increases, there is less room in the blood and bone marrow for healthy white blood cells, red blood cells and platelets. This may result in infection, anemia and bleeding, and ultimately, in death. A small proportion of CLL patients develop Richter's Syndrome, in which the disease progresses to what is more characteristic of an aggressive lymphoma.