Patients are seen by their referring physician every week for the first 4 weeks of the study, every other week for the next 8 weeks, and then monthly until the study is completed. At each visit, blood is drawn to monitor for drug side effects and response to therapy. In addition, patients come to the NIH Clinical Center every 3 months for a complete history and physical examination and for a bone marrow aspiration and biopsy every 6 months to assess the effect of treatment on bone marrow cells.