The purpose of this study is to compare the effectiveness of two dose levels of ONTAK (denileukin diftitox) in treating patients who have recurrent or persistent cutaneous T-cell lymphoma.

Inclusion Criteria:

• Histopathologically confirmed recurrent or persistent CTCL as determined by reference pathology lab;
• Patient must have had 1 to 3 prior CTCL therapies. Repeated use of the same agent is considered to be 1 therapy unless it is part of a different combination regimen. Only 1 prior combination cytotoxic regimen is permitted. Topical or systemic steroids are not considered a therapy;
• Interleukin-2 receptor (IL-2R) expression on at least 20% of tumor cells as determined by immunohistochemistry.
• Stage IA - III disease and unlikely to progress during the first month on study. Life expectancy of at least 12 months.
• Measurable or evaluable disease. Lymph node involvement no greater than LN2. No CTCL involvement of bone marrow.
• No active CNS disease, kidney or liver disease, significant pulmonary disease, or cardiac disease.
• No systemic infections;
• Willingness to be randomized to a placebo treatment only arm;
• ECOG performance status 0 or 1;

Exclusion Criteria:

• Patients must not have previously received treatment with DAB389IL-2 or DAB486IL 2 (previous candidate compound evaluated in a clinical setting).