The approval comes after results from a randomized study of 301 CLL patients showed that those who took Treanda had better outcomes than those treated with chlorambucil (Leukeran), a drug commonly used to treat CLL (see CLL: Chemotherapy for more information).

Fifty-nine percent of the patients taking Treanda had their disease significantly reduced by the drug, compared to 26% of those taking chlorambucil. After taking the drug, 8% of the patients showed no signs of disease, compared to less than 1% of patients taking chlorambucil. Further, researchers found that the disease didn't get worse for longer periods of time for those patients taking Treanda.

Chronic lymphocytic leukemia accounts for about one third of all leukemias. According to Cancer Facts and Figures 2008, the American Cancer Society's annual report on cancer statistics, an estimated 15,110 new cases of CLL will be diagnosed in the United States this year, and about 4,390 people in the United States will die of the disease. Several chemotherapy drugs are already in use to treat CLL. While it is generally not considered curable at this time, people with this disease often live for many years.

Although researchers aren't sure exactly which mechanisms are involved, Treanda appears to work by disrupting cell division and damaging DNA in tumor cells, leading to cell death. The most commonly reported side effects of the drug include myelosuppression (lowered blood cell counts), fever, nausea, and vomiting.

Cephalon has also submitted a request for the FDA to approve Treanda for the treatment of slow-growing non-Hodgkin lymphoma in patients whose disease has progressed despite taking the monoclonal antibody rituximab (Rituxan). An FDA decision is expected in October 2008.