OBJECTIVES:~Primary~Determine the complete and partial response rate in patients with fludarabine-refractory B-cell chronic lymphocytic leukemia treated with denileukin diftitox.~Secondary~Determine the toxicity profile of this drug in these patients.~Determine the response rate in patients (regardless of CD25 receptor density) treated with this drug.~Determine the progression-free survival and overall survival of patients treated with this drug.~OUTLINE: This is a multicenter study.~Patients receive denileukin diftitox IV over 1 hour on days 1-5. Treatment repeats every 21 days for up to 8 courses in the absence of disease progression or unacceptable toxicity.~Patients achieving a complete response after 8 courses proceed to follow-up. Patients achieving a partial response or stable disease after 8 courses may continue treatment at the discretion of the investigator.~Patients are followed every 3 months for 1 year and then annually until relapse.~PROJECTED ACCRUAL: A total of 12-44 patients will be accrued for this study within 1 year.
RATIONALE: Biological therapies, such as denileukin diftitox, may interfere with the growth of cancer cells and slow the growth of chronic lymphocytic leukemia.~PURPOSE: This phase II trial is studying how well denileukin diftitox works in treating patients with fludarabine-refractory B-cell chronic lymphocytic leukemia.