Name of the Trial
Phase II Study of LMB-2 Immunotoxin in Patients with CD25-Positive Chronic Lymphocytic Leukemia (NCI-04-C-0121). See the protocol summary at http://cancer.gov/clinicaltrials/NCI-04-C-0121.

Principal Investigator
Dr. Robert J. Kreitman, NCI Center for Cancer Research

Why Is This Trial Important?
Chronic lymphocytic leukemia (CLL) is the most common form of leukemia occurring in individuals aged 50 and over in the United States. Usually a slowly progressive or indolent form of cancer, CLL is characterized by the uncontrolled proliferation of lymphocytes. Most patients with indolent CLL do not require treatment until the disease causes symptoms, at which time they receive standard chemotherapy. Patients with indolent CLL generally survive 5 to 10 years after diagnosis.

Some patients with CLL, however, develop a more rapidly progressive form of the disease that often proves resistant to standard treatment. The average survival of these individuals is less than 24 months following diagnosis.

In this study, researchers are testing the effectiveness of an immunotoxin called LMB-2 in selectively killing CLL cells. LMB-2 is a laboratory-created monoclonal antibody fragment attached to a bacterial toxin. LMB-2 binds to a protein called CD25, which is found on the surface of many human lymphocytes. CD25 is more abundant on CLL cells than on normal lymphocytes, thereby allowing malignant cells to be targeted with great specificity. Once LMB-2 binds to CD25 on the cell surface, the toxin is taken up by the lymphocytes, causing them to die.

Patients enrolled in the study will receive up to 6 courses of LMB-2 over approximately 6 months, providing their disease does not worsen. If and when patients respond completely to LMB-2 (CLL is undetected), they will be given 2 additional courses of treatment.

Who Can Join This Trial?
Researchers plan to enroll 16 to 27 patients aged 18 and older who have been diagnosed with CD25-positive CLL. See the complete list of eligibility criteria at http://cancer.gov/clinicaltrials/NCI-04-C-0121.

Where Is This Trial Taking Place?
The trial is taking place at the NIH Clinical Center in Bethesda, Md.

Contact Information
For more information, contact the NCI Clinical Studies Support Center at 1-888-NCI-1937. The toll-free call is confidential.